Clinical Topics & News

Increased understanding of the pathophysiology of psoriasis has been one of the driving forces in the development of new therapies. An understanding of the processes involved is important in the optimal management of the disease. The last 30 years of research and clinical practice have revolutionized our understanding of the pathogenesis of psoriasis as the dysregulation of immunity triggered by environmental and genetic stimuli. Psoriasis was originally regarded as a primary disorder of epidermal hyperproliferation. However, experimental models and clinical results from immunomodulating therapies have refined this perspective in conceptualizing psoriasis as a genetically programmed pathologic interaction among resident skin cells; infiltrating immunocytes; and a host of proinflammatory cytokines, chemokines, and growth factors produced by these immunocytes. Two populations of immunocytes and their respective signaling molecules collaborate in the pathogenesis: (1) innate immunocytes, mediated by antigen-presenting cells (APCs)(including natural killer [NK] T lymphocytes, Langerhans cells, and neutrophils), and (2) acquired or adaptive immunocytes, mediated by mature CD4⁺ and CD8⁺ T lymphocytes in the skin. Such dysregulation of immunity and subsequent inflammation is responsible for the development and perpetuation of the clinical plaques and histological inflammatory infiltrate characteristic of psoriasis.

Although psoriasis is considered to be an immune-mediated disease in which intralesional T lymphocytes and their proinflammatory signals trigger primed basal layer keratinocytes to rapidly proliferate, debate and research focus on the stimulus that incites this inflammatory process. Our current understanding considers psoriasis to be triggered by exogenous or endogenous environmental stimuli in genetically susceptible individuals. Such stimuli include group A streptococcal pharyngitis, viremia, allergic drug reactions, antimalarial drugs, lithium, beta-blockers, IFN-α, withdrawal of systemic corticosteroids, local trauma (Köbner phenomenon), and emotional stress. These stimuli correlate with the onset or flares of psoriatic lesions. Psoriasis genetics centers on susceptibility loci and corresponding candidate genes, particularly the psoriasis susceptibility (PSORS) 1 locus on the major histocompatibility complex (MHC) class I region. Current research on the pathogenesis of psoriasis examines the complex interactions among immunologic mechanisms, environmental stimuli, and genetic susceptibility. After discussing the clinical presentation and histopathologic features of psoriasis, we will review the pathophysiology of psoriasis through noteworthy developments, including serendipitous observations, reactions to therapies, clinical trials, and animal model systems that have shaped our view of the disease process. In addition to the classic skin lesions, approximately 23% of psoriasis patients develop psoriatic arthritis, with a 10-year latency after diagnosis of psoriasis.¹

Principles of Immunity

The immune system, intended to protect its host from foreign invaders and unregulated cell growth, employs 2 main effector pathways—the innate and the acquired (or adaptive) immune responses—both of which contribute to the pathophysiology of psoriasis.² Innate immunity responses occur within minutes to hours of antigen exposure but fail to develop memory for when the antigen is encountered again. However, adaptive immunity responses take days to weeks to respond after challenged with an antigen. The adaptive immune cells have the capacity to respond to a greater range of antigens and develop immunologic memory via rearrangement of antigen receptors on B and T cells. These specialized B and T cells can then be promptly mobilized and differentiated into mature effector cells that protect the host from a foreign pathogen.

Innate and adaptive immune responses are highly intertwined; they can initiate, perpetuate, and terminate the immune mechanisms responsible for inflammation. They can modify the nature of the immune response by altering the relative proportions of type 1 (T_H1), type 2 (T_H2), and the more recently discovered type 17 (T_H17) subset of helper T cells and their respective signaling molecules. A T_H1 response is essential for a cellular immunologic reaction to intracellular bacteria and viruses or cellular immunity. A T_H2 response promotes IgE synthesis, eosinophilia, and mast cell maturation for extracellular parasites and helminthes as well as humoral immunity, while a T_H17 response is important for cell-mediated immunity to extracellular bacteria and plays a role in autoimmunity.³ The innate and adaptive immune responses employ common effector molecules such as chemokines and cytokines, which are essential in mediating an immune response.

Implicating Dysregulation of Immunity

Our present appreciation of the pathogenesis of psoriasis is based on the history of trial-and-error therapies; serendipitous discoveries; and the current immune targeting drugs used in a variety of chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease. Before the mid-1980s, research focused on the hyperproliferative epidermal cells as the primary pathology because a markedly thickened epidermis was indeed demonstrated on histologic specimens. Altered cell-cycle kinetics were thought to be the culprit behind the hyperkeratotic plaques. Thus, initial treatments centered on oncologic and antimitotic therapies used to arrest keratinocyte proliferation with agents such as arsenic, ammoniated mercury, and methotrexate.⁴

However, a paradigm shift from targeting epidermal keratinocytes to immunocyte populations was recognized when a patient receiving cyclosporine to prevent transplant rejection noted clearing of psoriatic lesions in the 1980s.⁵ Cyclosporine was observed to inhibit messenger RNA transcription of T-cell cytokines, thereby implicating immunologic dysregulation, specifically T-cell hyperactivity, in the pathogenesis of psoriasis.⁶ However, the concentrations of oral cyclosporine reached in the epidermis exerted direct effects on keratinocyte proliferation and lymphocyte function in these patients.⁷ Thus, the question was raised as to whether the keratinocytes or the lymphocytes drove the psoriatic plaques. The use of an IL-2 diphtheria toxin-fusion protein, denileukin diftitox, specific for activated T cells with high-affinity IL-2 receptors and nonreactive with keratinocytes, distinguished which cell type was responsible. This targeted T-cell toxin provided clinical and histological clearing of psoriatic plaques. Thus, T lymphocytes rather than keratinocytes were recognized as the definitive driver behind the psoriatic plaques.⁸

Additional studies have demonstrated that treatments that induce prolonged clearing of psoriatic lesions without continuous therapy, such as psoralen plus UVA irradiation, decreased the numbers of T cells in plaques by at least 90%.⁹ However, treatments that require continual therapy for satisfactory clinical results, such as cyclosporine and etretinate, simply suppress T-cell activity and proliferation.^10,11 Further evidence has linked cellular immunity with the pathogenesis of psoriasis, defining it as a T_H1-type disease. Natural killer T cells were shown to be involved through the use of a severe combined immunodeficient mouse model. They were injected into prepsoriatic skin grafted on immunodeficient mice, creating a psoriatic plaque with an immune response showing cytokines from T_H1 cells rather than T_H2 cells.¹² When psoriatic plaques were treated topically with the toll-like receptor 7 agonist imiquimod, aggravation and spreading of the plaques were noted. The exacerbation of psoriasis was accompanied by an induction of lesional T_H1-type interferon produced by plasmacytoid dendritic cell (DC) precursors. Plasmacytoid DCs were observed to compose up to 16% of the total dermal infiltrate in psoriatic skin lesions based on their coexpression of BDCA2 and CD123.¹³ Additionally, cancer patients being treated with interferon alfa experienced induction of psoriasis.¹⁴ Moreover, patients being treated for warts with intralesional interferon alfa developed psoriatic plaques in neighboring prior asymptomatic skin.¹⁵ Patients with psoriasis who were treated with interferon gamma, a T_H1 cytokine type, also developed new plaques correlating with the sites of injection.¹⁶

Intralesional T Lymphocytes

Psoriatic lesions contain a host of innate immunocytes, such as APCs, NK cells, and neutrophils, as well as adaptive T cells and an inflammatory infiltrate. These cells include CD4 and CD8 subtypes in which the CD8⁺ cells predominate in the epidermis, while CD4⁺ cells show preference for the dermis.¹⁷ There are 2 groups of CD8⁺ cells: one group migrates to the epidermis, expressing the integrin CD103, while the other group is found in the dermis but may be headed to or from the epidermis. The CD8⁺ cells residing in the epidermis that express the integrin CD103 are capable of interacting with E-cadherin, which enables these cells to travel to the epidermis and bind resident cells. Immunophenotyping reveals that these mature T cells represent chiefly activated memory cells, including CD2⁺, CD3⁺, CD5⁺, CLA, CD28, and CD45RO⁺.¹⁸ Many of these cells express activation markers such as HLA-DR, CD25, and CD27, in addition to the T-cell receptor (TCR).

T-Lymphocyte Stimulation

Both mature CD4⁺ and CD8⁺ T cells can respond to the peptides presented by APCs. Although the specific antigen that these T cells are reacting to has not yet been elucidated, several antigenic stimuli have been proposed, including self-proteins, microbial pathogens, and microbial superantigens. The premise that self-reactive T lymphocytes may contribute to the disease process is derived from the molecular mimicry theory in which an exuberant immune response to a pathogen produces cross-reactivity with self-antigens.¹⁹ Considering that infections have been associated with the onset of psoriasis, this theory merits consideration. However, it also has been observed that T cells can be activated without antigens or superantigens but rather with direct contact with accessory cells.²⁰ No single theory has clearly emerged. Researchers continue to search for the inciting stimulus that triggers the T lymphocyte and attempt to determine whether T cells are reacting to a self-derived or non–self-derived antigen.

T-Lymphocyte Signaling

T-cell signaling is a highly coordinated process in which T lymphocytes recognize antigens via presentation by mature APCs in the skin rather than the lymphoid tissues. Such APCs expose antigenic peptides via class I or II MHC molecules for which receptors are present on the T-cell surface. The antigen recognition complex at the T-cell and APC interface, in concert with a host of antigen-independent co-stimulatory signals, regulates T-cell signaling and is referred to as the immunologic synapse. The antigen presentation and network of co-stimulatory and adhesion molecules optimize T-cell activation, and dermal DCs release IL-12 and IL-23 to promote a T_H1 and T_H17 response, respectively. The growth factors released by these helper T cells sustain neoangiogenesis, stimulate epidermal hyperproliferation, alter epidermal differentiation, and decrease susceptibility to apoptosis that characterizes the erythematous hypertrophic scaling lesions of psoriasis.²¹ Furthermore, the cytokines produced from the immunologic response, such as tumor necrosis factor (TNF) α, IFN-γ, and IL-2, correspond to cytokines that are upregulated in psoriatic plaques.²²

Integral components of the immunologic synapse complex include co-stimulatory signals such as CD28, CD40, CD80, and CD86, as well as adhesion molecules such as cytotoxic T-lymphocyte antigen 4 and lymphocyte function-associated antigen (LFA) 1, which possess corresponding receptors on the T cell. These molecules play a key role in T-cell signaling, as their disruption has been shown to decrease T-cell responsiveness and associated inflammation. The B7 family of molecules routinely interacts with CD28 T cells to co-stimulate T-cell activation. Cytotoxic T-lymphocyte antigen 4 immunoglobulin, an antibody on the T-cell surface, targets B7 and interferes with signaling between B7 and CD28. In psoriatic patients, this blockade was demonstrated to attenuate the T-cell response and correlated with a clinical and histological decrease in psoriasiform hyperplasia.²³ Biologic therapies that disrupt the LFA-1 component of the immunologic synapse also have demonstrated efficacy in the treatment of psoriasis. Alefacept is a human LFA-3 fusion protein that binds CD2 on T cells and blocks the interaction between LFA-3 on APCs and CD2 on memory CD45RO⁺ T cells and induces apoptosis of such T cells. Efalizumab is a human monoclonal antibody to the CD11 chain of LFA-1 that blocks the interaction between LFA-1 on the T cell and intercellular adhesion molecule 1 on an APC or endothelial cell. Both alefacept and efalizumab, 2 formerly marketed biologic therapies, demonstrated remarkable clinical reduction of psoriatic lesions, and alefacept has been shown to produce disease remission for up to 18 months after discontinuation of therapy.^24-26

NK T Cells

Natural killer T cells represent a subset of CD3⁺ T cells present in psoriatic plaques. Although NK T cells possess a TCR, they differ from T cells by displaying NK receptors comprised of lectin and immunoglobulin families. These cells exhibit remarkable specificity and are activated upon recognition of glycolipids presented by CD1d molecules. This process occurs in contrast to CD4⁺ and CD8⁺ T cells, which, due to their TCR diversity, respond to peptides processed by APCs and displayed on MHC molecules. Natural killer T cells can be classified into 2 subsets: (1) one group that expresses CD4 and preferentially produces T_H1- versus T_H2-type cytokines, and (2) another group that lacks CD4 and CD8 that only produces T_H1-type cytokines. The innate immune system employs NK T cells early in the immune response because of their direct cytotoxicity and rapid production of cytokines such as IFN-γ, which promotes a T_H1 inflammatory response, and IL-4, which promotes the development of T_H2 cells. Excessive or dysfunctional NK T cells have been associated with autoimmune diseases such as multiple sclerosis and inflammatory bowel disease as well as allergic contact dermatitis.^27-29

In psoriasis, NK T cells are located in the epidermis, closely situated to epidermal keratinocytes, which suggests a role for direct antigen presentation. Furthermore, CD1d is overexpressed throughout the epidermis of psoriatic plaques, whereas normally CD1d expression is confined to terminally differentiated keratinocytes. An in vitro study examining cytokine-based inflammation demonstrative of psoriasis treated cultured CD1d-positive keratinocytes with interferon gamma in the presence of alpha-galactosylceramide of the lectin family.³⁰ Interferon gamma was observed to enhance keratinocyte CD1d expression, and subsequently, CD1d-positive keratinocytes were found to activate NK T cells to produce high levels of IFN-γ, while levels of IL-4 remained undetectable. The preferential production of IFN-γ supports a T_H1-mediated mechanism regulated by NK T cells in the immunopathogenesis of psoriasis.

Dendritic Cells

Dendritic cells are APCs that process antigens in the tissues in which they reside, after which they migrate to local lymph nodes where they present their native antigens to T cells. This process allows the T-cell response to be tailored to the appropriate antigens in the corresponding tissues. Immature DCs that capture antigens mature by migrating to the T-cell center of the lymph node where they present their antigens to either MHC molecules or the CD1 family. This presentation results in T-cell proliferation and differentiation that correlates with the required type of T-cell response. Multiple subsets of APCs, including myeloid and plasmacytoid DCs, are highly represented in the epidermis and dermis of psoriatic plaques as compared with normal skin.³¹ Dermal DCs are thought to be responsible for activating both the T_H1 and T_H17 infiltrate by secreting IL-12 and IL-23, respectively. This mixed cellular response secretes cytokines and leads to a cascade of events involving keratinocytes, fibroblasts, endothelial cells, and neutrophils that create the cutaneous lesions seen in psoriasis.³

Although DCs play a pivotal role in eliciting an immune response against a foreign invader, they also contribute to the establishment of tolerance. Throughout their maturation, DCs are continuously sensing their environment, which shapes their production of T_H1- versus T_H2-type cytokines and subsequently the nature of the T-cell response. When challenged with a virus, bacteria, or unchecked cell growth, DCs mature into APCs. However, in the absence of a strong stimulus, DCs fail to mature into APCs and present self-peptides with MHC molecules, thereby creating regulatory T cells involved in peripheral tolerance.³² If this balance between immunogenic APCs and housekeeping T cells is upset, inflammatory conditions such as psoriasis can result.

Cytokines

Cytokines are low-molecular-weight glycoproteins that function as signals to produce inflammation, defense, tissue repair and remodeling, fibrosis, angiogenesis, and restriction of neoplastic growth.³³ Cytokines are produced by immunocytes such as lymphocytes and macrophages as well as nonimmunocytes such as endothelial cells and keratinocytes. Proinflammatory cytokines include IL-1, IL-2, the IL-17 family, IFN-γ, and TNF-α, while anti-inflammatory cytokines include IL-4 and IL-10. A relative preponderance of T_H1 proinflammatory cytokines or an insufficiency of T_H2 anti-inflammatory cytokines induces local inflammation and recruitment of additional immunocyte populations, which produce added cytokines.³⁴ A vicious cycle of inflammation occurs that results in cutaneous manifestations such as a plaque. Psoriatic lesions are characterized by a relative increase of T_H1-type (eg, IL-2, IFN-γ, TNF-α, TNF-β) to T_H2-type (eg, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13) cytokines and an increase in T_H17-type cytokines. Natural killer T cells stimulated by CD1d-overexpressing keratinocytes increase production of proinflammatory IFN-γ without effect on the anti-inflammatory IL-4. In addition to the cytokines produced by T cells, APCs produce IL-18, IL-23, and TNF-α found in the inflammatory infiltrate of psoriatic plaques. Both IL-18 and IL-23 stimulate T_H1 cells to produce IFN-γ, and IL-23 stimulates T_H17 cells. Clearly, a T_H1- and T_H17-type pattern governs the immune effector cells and their respective cytokines present in psoriatic skin.

Tumor Necrosis Factor α

Although a network of cytokines is responsible for the inflammation of psoriasis, TNF-α has been implicated as a master proinflammatory cytokine of the innate immune response due to its widespread targets and sources. Tumor necrosis factor α is produced by activated T cells, keratinocytes, NK cells, macrophages, monocytes, Langerhans APCs, and endothelial cells. Psoriatic lesions demonstrate high concentrations of TNF-α, while the synovial fluid of psoriatic arthritis patients demonstrates elevated concentrations of TNF-α, IL-1, IL-6, and IL-8.³⁴ In psoriasis, TNF-α supports the expression of adhesion molecules (intercellular adhesion molecule 1 and P- and E-selectin), angiogenesis via vascular endothelial growth factor, the synthesis of proinflammatory molecules (IL-1, IL-6, IL-8, and nuclear factor κβ), and keratinocyte hyperproliferation via vasoactive intestinal peptide.³⁵

A role for TNF-α in psoriasis treatment was serendipitously discovered in a trial for Crohn disease in which infliximab, a mouse-human IgG1 anti–TNF-α monoclonal antibody, was observed to clear psoriatic plaques in a patient with both Crohn disease and psoriasis.³⁶ Immunotherapies that target TNF-α, including infliximab, etanercept, and adalimumab, demonstrate notable efficacy in the treatment of psoriasis.^37-39 Tumor necrosis factor α is regarded as the driver of the inflammatory cycle of psoriasis due to its numerous modes of production, capability to amplify other proinflammatory signals, and the efficacy and rapidity with which it produces clinical improvements in psoriasis.

IL-23/T_H17 Axis

A new distinct population of helper T cells has been shown to play an important role in psoriasis. These cells develop with the help of IL-23 (secreted by dermal DCs) and subsequently secrete cytokines such as IL-17; they are, therefore, named T_H17 cells. CD161 is considered a surface marker for these cells.⁴⁰ Strong evidence for this IL-23/T_H17 axis has been shown in mouse and human models as well as in genetic studies.

IL-23 is a cytokine that shares the p40 subunit with IL-12 and has been linked to autoimmune diseases in both mice and humans.³ It is required for optimal development of T_H17 cells⁴¹ from a committed CD4⁺ T-cell population after exposure to transforming growth factor β1 in combination with other proinflammatory cytokines.^42,43 IL-23 messenger RNA is produced at higher levels in inflammatory psoriatic skin lesions versus uninvolved skin,⁴⁴ and intradermal IL-23 injections in mice produced lesions resembling psoriasis macroscopically and microscopically.⁴⁵ Furthermore, several systemic therapies have been shown to modulate IL-23 levels and correlate with clinical benefit.³ Alterations in the gene for the IL-23 receptor have been shown to be protective for psoriasis,^46-48 and the gene coding for the p40 subunit is associated with psoriasis.^46,47

Type 17 helper T cells produce a number of cytokines, such as IL-22, IL-17A, IL-17F, and IL-26; the latter 3 are considered to be specific to this lineage.⁴² IL-22 acts on outer body barrier tissues, such as the skin, and has antimicrobial activity. Blocking the activity of IL-22 in mice prevented the development of skin lesions,⁴⁹ and psoriasis patients have elevated levels of IL-22 in the skin and blood.^50,51 The IL-17 cytokines induce the expression of proinflammatory cytokines, colony-stimulating factors, and chemokines, and they recruit, mobilize, and activate neutrophils.⁵² IL-17 messenger RNA was found in lesional psoriatic skin but not unaffected skin,⁵³ and cells isolated from the dermis of psoriatic skin have been shown to produce IL-17.⁵⁴ IL-17A is not elevated in the serum of psoriatic patients (unlike other autoimmune diseases),⁵⁵ and it is, therefore, thought that T_H17 cells and IL-17A production are localized to the affected psoriatic skin. Consistent with this concept is the finding that treatments such as cyclosporin A and anti-TNF agents decrease proinflammatory cytokines in lesional skin but not in the periphery.^56-58 These cytokines released by T_H17 cells in addition to those released by T_H1 cells act on keratinocytes and produce epidermal hyperproliferation, acanthosis, and hyperparakeratosis characteristic of psoriasis.³

New therapies have been developed to target the IL-23/T_H17 axis. Ustekinumab is approved for moderate to severe plaque psoriasis. This treatment’s effect may be sustained for up to 3 years, it is generally well tolerated, and it may be useful for patients refractory to anti-TNF therapy such as etanercept.⁵⁹ Briakinumab, another blocker of IL-12 and IL-23, was studied in phase 3 clinical trials, but its development was discontinued due to safety concerns.⁶⁰ Newer drugs targeting the IL-23/T_H17 axis include secukinumab, ixekizumab, brodalumab, guselkumab, and tildrakizumab.

Genetic Basis of Psoriasis

Psoriasis is a disease of overactive immunity in genetically susceptible individuals. Because patients exhibit varying skin phenotypes, extracutaneous manifestations, and disease courses, multiple genes resulting from linkage disequilibrium are believed to be involved in the pathogenesis of psoriasis. A decade of genome-wide linkage scans have established that PSORS1 is the strongest susceptibility locus demonstrable through family linkage studies; PSORS1 is responsible for up to 50% of the genetic component of psoriasis.⁶¹ More recently, HLA-Cw6 has received the most attention as a candidate gene of the PSORS1 susceptibility locus on the MHC class I region on chromosome 6p21.3.⁶² This gene may function in antigen presentation via MHC class I, which aids in the activation of the overactive T cells characteristic of psoriatic inflammation.

Studies involving the IL-23/T_H17 axis have shown genetics to play a role. Individuals may be protected from psoriasis with a nonsynonymous nucleotide substitution in the IL23R gene,^47-49 and certain haplotypes of the IL23R gene are associated with the disease^47,49 in addition to other autoimmune conditions.

Genomic scans have shown additional susceptibility loci for psoriasis on chromosomes 1q21, 3q21, 4q32-35, 16q12, and 17q25. Two regions on chromosome 17q were recently localized via mapping, which demonstrated a 6 megabase pairs separation, thereby indicating independent linkage factors. Genes SLC9A3R1 and NAT9 are present in the first region, while RAPTOR is demonstrated in the second region.⁶³SLC9A3R1 and NAT9 are players that regulate signal transduction, the immunologic synapse, and T-cell growth. RAPTOR is involved in T-cell function and growth pathways. Using these genes as an example, we can predict that the alterations of regulatory genes, even those yet undetermined, can enhance T-cell proliferation and inflammation manifested in psoriasis.

Conclusion

Psoriasis is a complex disease whereby multiple exogenous and endogenous stimuli incite already heightened innate immune responses in genetically predetermined individuals. The disease process is a result of a network of cell types, including T cells, DCs, and keratinocytes that, with the production of cytokines, generate a chronic inflammatory state. Our understanding of these cellular interactions and cytokines originates from developments, some meticulously planned, others serendipitous, in the fields of immunology, cell and molecular biology, and genetics. Such progress has fostered the creation of targeted immune therapy that has demonstrated remarkable efficacy in psoriasis treatment. Further study of the underlying pathophysiology of psoriasis may provide additional targets for therapy.

Increased understanding of the pathophysiology of psoriasis has been one of the driving forces in the development of new therapies. An understanding of the processes involved is important in the optimal management of the disease. The last 30 years of research and clinical practice have revolutionized our understanding of the pathogenesis of psoriasis as the dysregulation of immunity triggered by environmental and genetic stimuli. Psoriasis was originally regarded as a primary disorder of epidermal hyperproliferation. However, experimental models and clinical results from immunomodulating therapies have refined this perspective in conceptualizing psoriasis as a genetically programmed pathologic interaction among resident skin cells; infiltrating immunocytes; and a host of proinflammatory cytokines, chemokines, and growth factors produced by these immunocytes. Two populations of immunocytes and their respective signaling molecules collaborate in the pathogenesis: (1) innate immunocytes, mediated by antigen-presenting cells (APCs)(including natural killer [NK] T lymphocytes, Langerhans cells, and neutrophils), and (2) acquired or adaptive immunocytes, mediated by mature CD4⁺ and CD8⁺ T lymphocytes in the skin. Such dysregulation of immunity and subsequent inflammation is responsible for the development and perpetuation of the clinical plaques and histological inflammatory infiltrate characteristic of psoriasis.

Although psoriasis is considered to be an immune-mediated disease in which intralesional T lymphocytes and their proinflammatory signals trigger primed basal layer keratinocytes to rapidly proliferate, debate and research focus on the stimulus that incites this inflammatory process. Our current understanding considers psoriasis to be triggered by exogenous or endogenous environmental stimuli in genetically susceptible individuals. Such stimuli include group A streptococcal pharyngitis, viremia, allergic drug reactions, antimalarial drugs, lithium, beta-blockers, IFN-α, withdrawal of systemic corticosteroids, local trauma (Köbner phenomenon), and emotional stress. These stimuli correlate with the onset or flares of psoriatic lesions. Psoriasis genetics centers on susceptibility loci and corresponding candidate genes, particularly the psoriasis susceptibility (PSORS) 1 locus on the major histocompatibility complex (MHC) class I region. Current research on the pathogenesis of psoriasis examines the complex interactions among immunologic mechanisms, environmental stimuli, and genetic susceptibility. After discussing the clinical presentation and histopathologic features of psoriasis, we will review the pathophysiology of psoriasis through noteworthy developments, including serendipitous observations, reactions to therapies, clinical trials, and animal model systems that have shaped our view of the disease process. In addition to the classic skin lesions, approximately 23% of psoriasis patients develop psoriatic arthritis, with a 10-year latency after diagnosis of psoriasis.¹

Principles of Immunity

The immune system, intended to protect its host from foreign invaders and unregulated cell growth, employs 2 main effector pathways—the innate and the acquired (or adaptive) immune responses—both of which contribute to the pathophysiology of psoriasis.² Innate immunity responses occur within minutes to hours of antigen exposure but fail to develop memory for when the antigen is encountered again. However, adaptive immunity responses take days to weeks to respond after challenged with an antigen. The adaptive immune cells have the capacity to respond to a greater range of antigens and develop immunologic memory via rearrangement of antigen receptors on B and T cells. These specialized B and T cells can then be promptly mobilized and differentiated into mature effector cells that protect the host from a foreign pathogen.

Innate and adaptive immune responses are highly intertwined; they can initiate, perpetuate, and terminate the immune mechanisms responsible for inflammation. They can modify the nature of the immune response by altering the relative proportions of type 1 (T_H1), type 2 (T_H2), and the more recently discovered type 17 (T_H17) subset of helper T cells and their respective signaling molecules. A T_H1 response is essential for a cellular immunologic reaction to intracellular bacteria and viruses or cellular immunity. A T_H2 response promotes IgE synthesis, eosinophilia, and mast cell maturation for extracellular parasites and helminthes as well as humoral immunity, while a T_H17 response is important for cell-mediated immunity to extracellular bacteria and plays a role in autoimmunity.³ The innate and adaptive immune responses employ common effector molecules such as chemokines and cytokines, which are essential in mediating an immune response.

Implicating Dysregulation of Immunity

Our present appreciation of the pathogenesis of psoriasis is based on the history of trial-and-error therapies; serendipitous discoveries; and the current immune targeting drugs used in a variety of chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease. Before the mid-1980s, research focused on the hyperproliferative epidermal cells as the primary pathology because a markedly thickened epidermis was indeed demonstrated on histologic specimens. Altered cell-cycle kinetics were thought to be the culprit behind the hyperkeratotic plaques. Thus, initial treatments centered on oncologic and antimitotic therapies used to arrest keratinocyte proliferation with agents such as arsenic, ammoniated mercury, and methotrexate.⁴

However, a paradigm shift from targeting epidermal keratinocytes to immunocyte populations was recognized when a patient receiving cyclosporine to prevent transplant rejection noted clearing of psoriatic lesions in the 1980s.⁵ Cyclosporine was observed to inhibit messenger RNA transcription of T-cell cytokines, thereby implicating immunologic dysregulation, specifically T-cell hyperactivity, in the pathogenesis of psoriasis.⁶ However, the concentrations of oral cyclosporine reached in the epidermis exerted direct effects on keratinocyte proliferation and lymphocyte function in these patients.⁷ Thus, the question was raised as to whether the keratinocytes or the lymphocytes drove the psoriatic plaques. The use of an IL-2 diphtheria toxin-fusion protein, denileukin diftitox, specific for activated T cells with high-affinity IL-2 receptors and nonreactive with keratinocytes, distinguished which cell type was responsible. This targeted T-cell toxin provided clinical and histological clearing of psoriatic plaques. Thus, T lymphocytes rather than keratinocytes were recognized as the definitive driver behind the psoriatic plaques.⁸

Additional studies have demonstrated that treatments that induce prolonged clearing of psoriatic lesions without continuous therapy, such as psoralen plus UVA irradiation, decreased the numbers of T cells in plaques by at least 90%.⁹ However, treatments that require continual therapy for satisfactory clinical results, such as cyclosporine and etretinate, simply suppress T-cell activity and proliferation.^10,11 Further evidence has linked cellular immunity with the pathogenesis of psoriasis, defining it as a T_H1-type disease. Natural killer T cells were shown to be involved through the use of a severe combined immunodeficient mouse model. They were injected into prepsoriatic skin grafted on immunodeficient mice, creating a psoriatic plaque with an immune response showing cytokines from T_H1 cells rather than T_H2 cells.¹² When psoriatic plaques were treated topically with the toll-like receptor 7 agonist imiquimod, aggravation and spreading of the plaques were noted. The exacerbation of psoriasis was accompanied by an induction of lesional T_H1-type interferon produced by plasmacytoid dendritic cell (DC) precursors. Plasmacytoid DCs were observed to compose up to 16% of the total dermal infiltrate in psoriatic skin lesions based on their coexpression of BDCA2 and CD123.¹³ Additionally, cancer patients being treated with interferon alfa experienced induction of psoriasis.¹⁴ Moreover, patients being treated for warts with intralesional interferon alfa developed psoriatic plaques in neighboring prior asymptomatic skin.¹⁵ Patients with psoriasis who were treated with interferon gamma, a T_H1 cytokine type, also developed new plaques correlating with the sites of injection.¹⁶

Intralesional T Lymphocytes

Psoriatic lesions contain a host of innate immunocytes, such as APCs, NK cells, and neutrophils, as well as adaptive T cells and an inflammatory infiltrate. These cells include CD4 and CD8 subtypes in which the CD8⁺ cells predominate in the epidermis, while CD4⁺ cells show preference for the dermis.¹⁷ There are 2 groups of CD8⁺ cells: one group migrates to the epidermis, expressing the integrin CD103, while the other group is found in the dermis but may be headed to or from the epidermis. The CD8⁺ cells residing in the epidermis that express the integrin CD103 are capable of interacting with E-cadherin, which enables these cells to travel to the epidermis and bind resident cells. Immunophenotyping reveals that these mature T cells represent chiefly activated memory cells, including CD2⁺, CD3⁺, CD5⁺, CLA, CD28, and CD45RO⁺.¹⁸ Many of these cells express activation markers such as HLA-DR, CD25, and CD27, in addition to the T-cell receptor (TCR).

T-Lymphocyte Stimulation

Both mature CD4⁺ and CD8⁺ T cells can respond to the peptides presented by APCs. Although the specific antigen that these T cells are reacting to has not yet been elucidated, several antigenic stimuli have been proposed, including self-proteins, microbial pathogens, and microbial superantigens. The premise that self-reactive T lymphocytes may contribute to the disease process is derived from the molecular mimicry theory in which an exuberant immune response to a pathogen produces cross-reactivity with self-antigens.¹⁹ Considering that infections have been associated with the onset of psoriasis, this theory merits consideration. However, it also has been observed that T cells can be activated without antigens or superantigens but rather with direct contact with accessory cells.²⁰ No single theory has clearly emerged. Researchers continue to search for the inciting stimulus that triggers the T lymphocyte and attempt to determine whether T cells are reacting to a self-derived or non–self-derived antigen.

T-Lymphocyte Signaling

T-cell signaling is a highly coordinated process in which T lymphocytes recognize antigens via presentation by mature APCs in the skin rather than the lymphoid tissues. Such APCs expose antigenic peptides via class I or II MHC molecules for which receptors are present on the T-cell surface. The antigen recognition complex at the T-cell and APC interface, in concert with a host of antigen-independent co-stimulatory signals, regulates T-cell signaling and is referred to as the immunologic synapse. The antigen presentation and network of co-stimulatory and adhesion molecules optimize T-cell activation, and dermal DCs release IL-12 and IL-23 to promote a T_H1 and T_H17 response, respectively. The growth factors released by these helper T cells sustain neoangiogenesis, stimulate epidermal hyperproliferation, alter epidermal differentiation, and decrease susceptibility to apoptosis that characterizes the erythematous hypertrophic scaling lesions of psoriasis.²¹ Furthermore, the cytokines produced from the immunologic response, such as tumor necrosis factor (TNF) α, IFN-γ, and IL-2, correspond to cytokines that are upregulated in psoriatic plaques.²²

Integral components of the immunologic synapse complex include co-stimulatory signals such as CD28, CD40, CD80, and CD86, as well as adhesion molecules such as cytotoxic T-lymphocyte antigen 4 and lymphocyte function-associated antigen (LFA) 1, which possess corresponding receptors on the T cell. These molecules play a key role in T-cell signaling, as their disruption has been shown to decrease T-cell responsiveness and associated inflammation. The B7 family of molecules routinely interacts with CD28 T cells to co-stimulate T-cell activation. Cytotoxic T-lymphocyte antigen 4 immunoglobulin, an antibody on the T-cell surface, targets B7 and interferes with signaling between B7 and CD28. In psoriatic patients, this blockade was demonstrated to attenuate the T-cell response and correlated with a clinical and histological decrease in psoriasiform hyperplasia.²³ Biologic therapies that disrupt the LFA-1 component of the immunologic synapse also have demonstrated efficacy in the treatment of psoriasis. Alefacept is a human LFA-3 fusion protein that binds CD2 on T cells and blocks the interaction between LFA-3 on APCs and CD2 on memory CD45RO⁺ T cells and induces apoptosis of such T cells. Efalizumab is a human monoclonal antibody to the CD11 chain of LFA-1 that blocks the interaction between LFA-1 on the T cell and intercellular adhesion molecule 1 on an APC or endothelial cell. Both alefacept and efalizumab, 2 formerly marketed biologic therapies, demonstrated remarkable clinical reduction of psoriatic lesions, and alefacept has been shown to produce disease remission for up to 18 months after discontinuation of therapy.^24-26

NK T Cells

Natural killer T cells represent a subset of CD3⁺ T cells present in psoriatic plaques. Although NK T cells possess a TCR, they differ from T cells by displaying NK receptors comprised of lectin and immunoglobulin families. These cells exhibit remarkable specificity and are activated upon recognition of glycolipids presented by CD1d molecules. This process occurs in contrast to CD4⁺ and CD8⁺ T cells, which, due to their TCR diversity, respond to peptides processed by APCs and displayed on MHC molecules. Natural killer T cells can be classified into 2 subsets: (1) one group that expresses CD4 and preferentially produces T_H1- versus T_H2-type cytokines, and (2) another group that lacks CD4 and CD8 that only produces T_H1-type cytokines. The innate immune system employs NK T cells early in the immune response because of their direct cytotoxicity and rapid production of cytokines such as IFN-γ, which promotes a T_H1 inflammatory response, and IL-4, which promotes the development of T_H2 cells. Excessive or dysfunctional NK T cells have been associated with autoimmune diseases such as multiple sclerosis and inflammatory bowel disease as well as allergic contact dermatitis.^27-29

In psoriasis, NK T cells are located in the epidermis, closely situated to epidermal keratinocytes, which suggests a role for direct antigen presentation. Furthermore, CD1d is overexpressed throughout the epidermis of psoriatic plaques, whereas normally CD1d expression is confined to terminally differentiated keratinocytes. An in vitro study examining cytokine-based inflammation demonstrative of psoriasis treated cultured CD1d-positive keratinocytes with interferon gamma in the presence of alpha-galactosylceramide of the lectin family.³⁰ Interferon gamma was observed to enhance keratinocyte CD1d expression, and subsequently, CD1d-positive keratinocytes were found to activate NK T cells to produce high levels of IFN-γ, while levels of IL-4 remained undetectable. The preferential production of IFN-γ supports a T_H1-mediated mechanism regulated by NK T cells in the immunopathogenesis of psoriasis.

Dendritic Cells

Dendritic cells are APCs that process antigens in the tissues in which they reside, after which they migrate to local lymph nodes where they present their native antigens to T cells. This process allows the T-cell response to be tailored to the appropriate antigens in the corresponding tissues. Immature DCs that capture antigens mature by migrating to the T-cell center of the lymph node where they present their antigens to either MHC molecules or the CD1 family. This presentation results in T-cell proliferation and differentiation that correlates with the required type of T-cell response. Multiple subsets of APCs, including myeloid and plasmacytoid DCs, are highly represented in the epidermis and dermis of psoriatic plaques as compared with normal skin.³¹ Dermal DCs are thought to be responsible for activating both the T_H1 and T_H17 infiltrate by secreting IL-12 and IL-23, respectively. This mixed cellular response secretes cytokines and leads to a cascade of events involving keratinocytes, fibroblasts, endothelial cells, and neutrophils that create the cutaneous lesions seen in psoriasis.³

Although DCs play a pivotal role in eliciting an immune response against a foreign invader, they also contribute to the establishment of tolerance. Throughout their maturation, DCs are continuously sensing their environment, which shapes their production of T_H1- versus T_H2-type cytokines and subsequently the nature of the T-cell response. When challenged with a virus, bacteria, or unchecked cell growth, DCs mature into APCs. However, in the absence of a strong stimulus, DCs fail to mature into APCs and present self-peptides with MHC molecules, thereby creating regulatory T cells involved in peripheral tolerance.³² If this balance between immunogenic APCs and housekeeping T cells is upset, inflammatory conditions such as psoriasis can result.

Cytokines

Cytokines are low-molecular-weight glycoproteins that function as signals to produce inflammation, defense, tissue repair and remodeling, fibrosis, angiogenesis, and restriction of neoplastic growth.³³ Cytokines are produced by immunocytes such as lymphocytes and macrophages as well as nonimmunocytes such as endothelial cells and keratinocytes. Proinflammatory cytokines include IL-1, IL-2, the IL-17 family, IFN-γ, and TNF-α, while anti-inflammatory cytokines include IL-4 and IL-10. A relative preponderance of T_H1 proinflammatory cytokines or an insufficiency of T_H2 anti-inflammatory cytokines induces local inflammation and recruitment of additional immunocyte populations, which produce added cytokines.³⁴ A vicious cycle of inflammation occurs that results in cutaneous manifestations such as a plaque. Psoriatic lesions are characterized by a relative increase of T_H1-type (eg, IL-2, IFN-γ, TNF-α, TNF-β) to T_H2-type (eg, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13) cytokines and an increase in T_H17-type cytokines. Natural killer T cells stimulated by CD1d-overexpressing keratinocytes increase production of proinflammatory IFN-γ without effect on the anti-inflammatory IL-4. In addition to the cytokines produced by T cells, APCs produce IL-18, IL-23, and TNF-α found in the inflammatory infiltrate of psoriatic plaques. Both IL-18 and IL-23 stimulate T_H1 cells to produce IFN-γ, and IL-23 stimulates T_H17 cells. Clearly, a T_H1- and T_H17-type pattern governs the immune effector cells and their respective cytokines present in psoriatic skin.

Tumor Necrosis Factor α

Although a network of cytokines is responsible for the inflammation of psoriasis, TNF-α has been implicated as a master proinflammatory cytokine of the innate immune response due to its widespread targets and sources. Tumor necrosis factor α is produced by activated T cells, keratinocytes, NK cells, macrophages, monocytes, Langerhans APCs, and endothelial cells. Psoriatic lesions demonstrate high concentrations of TNF-α, while the synovial fluid of psoriatic arthritis patients demonstrates elevated concentrations of TNF-α, IL-1, IL-6, and IL-8.³⁴ In psoriasis, TNF-α supports the expression of adhesion molecules (intercellular adhesion molecule 1 and P- and E-selectin), angiogenesis via vascular endothelial growth factor, the synthesis of proinflammatory molecules (IL-1, IL-6, IL-8, and nuclear factor κβ), and keratinocyte hyperproliferation via vasoactive intestinal peptide.³⁵

A role for TNF-α in psoriasis treatment was serendipitously discovered in a trial for Crohn disease in which infliximab, a mouse-human IgG1 anti–TNF-α monoclonal antibody, was observed to clear psoriatic plaques in a patient with both Crohn disease and psoriasis.³⁶ Immunotherapies that target TNF-α, including infliximab, etanercept, and adalimumab, demonstrate notable efficacy in the treatment of psoriasis.^37-39 Tumor necrosis factor α is regarded as the driver of the inflammatory cycle of psoriasis due to its numerous modes of production, capability to amplify other proinflammatory signals, and the efficacy and rapidity with which it produces clinical improvements in psoriasis.

IL-23/T_H17 Axis

A new distinct population of helper T cells has been shown to play an important role in psoriasis. These cells develop with the help of IL-23 (secreted by dermal DCs) and subsequently secrete cytokines such as IL-17; they are, therefore, named T_H17 cells. CD161 is considered a surface marker for these cells.⁴⁰ Strong evidence for this IL-23/T_H17 axis has been shown in mouse and human models as well as in genetic studies.

IL-23 is a cytokine that shares the p40 subunit with IL-12 and has been linked to autoimmune diseases in both mice and humans.³ It is required for optimal development of T_H17 cells⁴¹ from a committed CD4⁺ T-cell population after exposure to transforming growth factor β1 in combination with other proinflammatory cytokines.^42,43 IL-23 messenger RNA is produced at higher levels in inflammatory psoriatic skin lesions versus uninvolved skin,⁴⁴ and intradermal IL-23 injections in mice produced lesions resembling psoriasis macroscopically and microscopically.⁴⁵ Furthermore, several systemic therapies have been shown to modulate IL-23 levels and correlate with clinical benefit.³ Alterations in the gene for the IL-23 receptor have been shown to be protective for psoriasis,^46-48 and the gene coding for the p40 subunit is associated with psoriasis.^46,47

Type 17 helper T cells produce a number of cytokines, such as IL-22, IL-17A, IL-17F, and IL-26; the latter 3 are considered to be specific to this lineage.⁴² IL-22 acts on outer body barrier tissues, such as the skin, and has antimicrobial activity. Blocking the activity of IL-22 in mice prevented the development of skin lesions,⁴⁹ and psoriasis patients have elevated levels of IL-22 in the skin and blood.^50,51 The IL-17 cytokines induce the expression of proinflammatory cytokines, colony-stimulating factors, and chemokines, and they recruit, mobilize, and activate neutrophils.⁵² IL-17 messenger RNA was found in lesional psoriatic skin but not unaffected skin,⁵³ and cells isolated from the dermis of psoriatic skin have been shown to produce IL-17.⁵⁴ IL-17A is not elevated in the serum of psoriatic patients (unlike other autoimmune diseases),⁵⁵ and it is, therefore, thought that T_H17 cells and IL-17A production are localized to the affected psoriatic skin. Consistent with this concept is the finding that treatments such as cyclosporin A and anti-TNF agents decrease proinflammatory cytokines in lesional skin but not in the periphery.^56-58 These cytokines released by T_H17 cells in addition to those released by T_H1 cells act on keratinocytes and produce epidermal hyperproliferation, acanthosis, and hyperparakeratosis characteristic of psoriasis.³

New therapies have been developed to target the IL-23/T_H17 axis. Ustekinumab is approved for moderate to severe plaque psoriasis. This treatment’s effect may be sustained for up to 3 years, it is generally well tolerated, and it may be useful for patients refractory to anti-TNF therapy such as etanercept.⁵⁹ Briakinumab, another blocker of IL-12 and IL-23, was studied in phase 3 clinical trials, but its development was discontinued due to safety concerns.⁶⁰ Newer drugs targeting the IL-23/T_H17 axis include secukinumab, ixekizumab, brodalumab, guselkumab, and tildrakizumab.

Genetic Basis of Psoriasis

Psoriasis is a disease of overactive immunity in genetically susceptible individuals. Because patients exhibit varying skin phenotypes, extracutaneous manifestations, and disease courses, multiple genes resulting from linkage disequilibrium are believed to be involved in the pathogenesis of psoriasis. A decade of genome-wide linkage scans have established that PSORS1 is the strongest susceptibility locus demonstrable through family linkage studies; PSORS1 is responsible for up to 50% of the genetic component of psoriasis.⁶¹ More recently, HLA-Cw6 has received the most attention as a candidate gene of the PSORS1 susceptibility locus on the MHC class I region on chromosome 6p21.3.⁶² This gene may function in antigen presentation via MHC class I, which aids in the activation of the overactive T cells characteristic of psoriatic inflammation.

Studies involving the IL-23/T_H17 axis have shown genetics to play a role. Individuals may be protected from psoriasis with a nonsynonymous nucleotide substitution in the IL23R gene,^47-49 and certain haplotypes of the IL23R gene are associated with the disease^47,49 in addition to other autoimmune conditions.

Genomic scans have shown additional susceptibility loci for psoriasis on chromosomes 1q21, 3q21, 4q32-35, 16q12, and 17q25. Two regions on chromosome 17q were recently localized via mapping, which demonstrated a 6 megabase pairs separation, thereby indicating independent linkage factors. Genes SLC9A3R1 and NAT9 are present in the first region, while RAPTOR is demonstrated in the second region.⁶³SLC9A3R1 and NAT9 are players that regulate signal transduction, the immunologic synapse, and T-cell growth. RAPTOR is involved in T-cell function and growth pathways. Using these genes as an example, we can predict that the alterations of regulatory genes, even those yet undetermined, can enhance T-cell proliferation and inflammation manifested in psoriasis.

Conclusion

Psoriasis is a complex disease whereby multiple exogenous and endogenous stimuli incite already heightened innate immune responses in genetically predetermined individuals. The disease process is a result of a network of cell types, including T cells, DCs, and keratinocytes that, with the production of cytokines, generate a chronic inflammatory state. Our understanding of these cellular interactions and cytokines originates from developments, some meticulously planned, others serendipitous, in the fields of immunology, cell and molecular biology, and genetics. Such progress has fostered the creation of targeted immune therapy that has demonstrated remarkable efficacy in psoriasis treatment. Further study of the underlying pathophysiology of psoriasis may provide additional targets for therapy.

Increased understanding of the pathophysiology of psoriasis has been one of the driving forces in the development of new therapies. An understanding of the processes involved is important in the optimal management of the disease. The last 30 years of research and clinical practice have revolutionized our understanding of the pathogenesis of psoriasis as the dysregulation of immunity triggered by environmental and genetic stimuli. Psoriasis was originally regarded as a primary disorder of epidermal hyperproliferation. However, experimental models and clinical results from immunomodulating therapies have refined this perspective in conceptualizing psoriasis as a genetically programmed pathologic interaction among resident skin cells; infiltrating immunocytes; and a host of proinflammatory cytokines, chemokines, and growth factors produced by these immunocytes. Two populations of immunocytes and their respective signaling molecules collaborate in the pathogenesis: (1) innate immunocytes, mediated by antigen-presenting cells (APCs)(including natural killer [NK] T lymphocytes, Langerhans cells, and neutrophils), and (2) acquired or adaptive immunocytes, mediated by mature CD4⁺ and CD8⁺ T lymphocytes in the skin. Such dysregulation of immunity and subsequent inflammation is responsible for the development and perpetuation of the clinical plaques and histological inflammatory infiltrate characteristic of psoriasis.

Although psoriasis is considered to be an immune-mediated disease in which intralesional T lymphocytes and their proinflammatory signals trigger primed basal layer keratinocytes to rapidly proliferate, debate and research focus on the stimulus that incites this inflammatory process. Our current understanding considers psoriasis to be triggered by exogenous or endogenous environmental stimuli in genetically susceptible individuals. Such stimuli include group A streptococcal pharyngitis, viremia, allergic drug reactions, antimalarial drugs, lithium, beta-blockers, IFN-α, withdrawal of systemic corticosteroids, local trauma (Köbner phenomenon), and emotional stress. These stimuli correlate with the onset or flares of psoriatic lesions. Psoriasis genetics centers on susceptibility loci and corresponding candidate genes, particularly the psoriasis susceptibility (PSORS) 1 locus on the major histocompatibility complex (MHC) class I region. Current research on the pathogenesis of psoriasis examines the complex interactions among immunologic mechanisms, environmental stimuli, and genetic susceptibility. After discussing the clinical presentation and histopathologic features of psoriasis, we will review the pathophysiology of psoriasis through noteworthy developments, including serendipitous observations, reactions to therapies, clinical trials, and animal model systems that have shaped our view of the disease process. In addition to the classic skin lesions, approximately 23% of psoriasis patients develop psoriatic arthritis, with a 10-year latency after diagnosis of psoriasis.¹

Principles of Immunity

The immune system, intended to protect its host from foreign invaders and unregulated cell growth, employs 2 main effector pathways—the innate and the acquired (or adaptive) immune responses—both of which contribute to the pathophysiology of psoriasis.² Innate immunity responses occur within minutes to hours of antigen exposure but fail to develop memory for when the antigen is encountered again. However, adaptive immunity responses take days to weeks to respond after challenged with an antigen. The adaptive immune cells have the capacity to respond to a greater range of antigens and develop immunologic memory via rearrangement of antigen receptors on B and T cells. These specialized B and T cells can then be promptly mobilized and differentiated into mature effector cells that protect the host from a foreign pathogen.

Innate and adaptive immune responses are highly intertwined; they can initiate, perpetuate, and terminate the immune mechanisms responsible for inflammation. They can modify the nature of the immune response by altering the relative proportions of type 1 (T_H1), type 2 (T_H2), and the more recently discovered type 17 (T_H17) subset of helper T cells and their respective signaling molecules. A T_H1 response is essential for a cellular immunologic reaction to intracellular bacteria and viruses or cellular immunity. A T_H2 response promotes IgE synthesis, eosinophilia, and mast cell maturation for extracellular parasites and helminthes as well as humoral immunity, while a T_H17 response is important for cell-mediated immunity to extracellular bacteria and plays a role in autoimmunity.³ The innate and adaptive immune responses employ common effector molecules such as chemokines and cytokines, which are essential in mediating an immune response.

Implicating Dysregulation of Immunity

Our present appreciation of the pathogenesis of psoriasis is based on the history of trial-and-error therapies; serendipitous discoveries; and the current immune targeting drugs used in a variety of chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease. Before the mid-1980s, research focused on the hyperproliferative epidermal cells as the primary pathology because a markedly thickened epidermis was indeed demonstrated on histologic specimens. Altered cell-cycle kinetics were thought to be the culprit behind the hyperkeratotic plaques. Thus, initial treatments centered on oncologic and antimitotic therapies used to arrest keratinocyte proliferation with agents such as arsenic, ammoniated mercury, and methotrexate.⁴

However, a paradigm shift from targeting epidermal keratinocytes to immunocyte populations was recognized when a patient receiving cyclosporine to prevent transplant rejection noted clearing of psoriatic lesions in the 1980s.⁵ Cyclosporine was observed to inhibit messenger RNA transcription of T-cell cytokines, thereby implicating immunologic dysregulation, specifically T-cell hyperactivity, in the pathogenesis of psoriasis.⁶ However, the concentrations of oral cyclosporine reached in the epidermis exerted direct effects on keratinocyte proliferation and lymphocyte function in these patients.⁷ Thus, the question was raised as to whether the keratinocytes or the lymphocytes drove the psoriatic plaques. The use of an IL-2 diphtheria toxin-fusion protein, denileukin diftitox, specific for activated T cells with high-affinity IL-2 receptors and nonreactive with keratinocytes, distinguished which cell type was responsible. This targeted T-cell toxin provided clinical and histological clearing of psoriatic plaques. Thus, T lymphocytes rather than keratinocytes were recognized as the definitive driver behind the psoriatic plaques.⁸

Additional studies have demonstrated that treatments that induce prolonged clearing of psoriatic lesions without continuous therapy, such as psoralen plus UVA irradiation, decreased the numbers of T cells in plaques by at least 90%.⁹ However, treatments that require continual therapy for satisfactory clinical results, such as cyclosporine and etretinate, simply suppress T-cell activity and proliferation.^10,11 Further evidence has linked cellular immunity with the pathogenesis of psoriasis, defining it as a T_H1-type disease. Natural killer T cells were shown to be involved through the use of a severe combined immunodeficient mouse model. They were injected into prepsoriatic skin grafted on immunodeficient mice, creating a psoriatic plaque with an immune response showing cytokines from T_H1 cells rather than T_H2 cells.¹² When psoriatic plaques were treated topically with the toll-like receptor 7 agonist imiquimod, aggravation and spreading of the plaques were noted. The exacerbation of psoriasis was accompanied by an induction of lesional T_H1-type interferon produced by plasmacytoid dendritic cell (DC) precursors. Plasmacytoid DCs were observed to compose up to 16% of the total dermal infiltrate in psoriatic skin lesions based on their coexpression of BDCA2 and CD123.¹³ Additionally, cancer patients being treated with interferon alfa experienced induction of psoriasis.¹⁴ Moreover, patients being treated for warts with intralesional interferon alfa developed psoriatic plaques in neighboring prior asymptomatic skin.¹⁵ Patients with psoriasis who were treated with interferon gamma, a T_H1 cytokine type, also developed new plaques correlating with the sites of injection.¹⁶

Intralesional T Lymphocytes

Psoriatic lesions contain a host of innate immunocytes, such as APCs, NK cells, and neutrophils, as well as adaptive T cells and an inflammatory infiltrate. These cells include CD4 and CD8 subtypes in which the CD8⁺ cells predominate in the epidermis, while CD4⁺ cells show preference for the dermis.¹⁷ There are 2 groups of CD8⁺ cells: one group migrates to the epidermis, expressing the integrin CD103, while the other group is found in the dermis but may be headed to or from the epidermis. The CD8⁺ cells residing in the epidermis that express the integrin CD103 are capable of interacting with E-cadherin, which enables these cells to travel to the epidermis and bind resident cells. Immunophenotyping reveals that these mature T cells represent chiefly activated memory cells, including CD2⁺, CD3⁺, CD5⁺, CLA, CD28, and CD45RO⁺.¹⁸ Many of these cells express activation markers such as HLA-DR, CD25, and CD27, in addition to the T-cell receptor (TCR).

T-Lymphocyte Stimulation

Both mature CD4⁺ and CD8⁺ T cells can respond to the peptides presented by APCs. Although the specific antigen that these T cells are reacting to has not yet been elucidated, several antigenic stimuli have been proposed, including self-proteins, microbial pathogens, and microbial superantigens. The premise that self-reactive T lymphocytes may contribute to the disease process is derived from the molecular mimicry theory in which an exuberant immune response to a pathogen produces cross-reactivity with self-antigens.¹⁹ Considering that infections have been associated with the onset of psoriasis, this theory merits consideration. However, it also has been observed that T cells can be activated without antigens or superantigens but rather with direct contact with accessory cells.²⁰ No single theory has clearly emerged. Researchers continue to search for the inciting stimulus that triggers the T lymphocyte and attempt to determine whether T cells are reacting to a self-derived or non–self-derived antigen.

T-Lymphocyte Signaling

T-cell signaling is a highly coordinated process in which T lymphocytes recognize antigens via presentation by mature APCs in the skin rather than the lymphoid tissues. Such APCs expose antigenic peptides via class I or II MHC molecules for which receptors are present on the T-cell surface. The antigen recognition complex at the T-cell and APC interface, in concert with a host of antigen-independent co-stimulatory signals, regulates T-cell signaling and is referred to as the immunologic synapse. The antigen presentation and network of co-stimulatory and adhesion molecules optimize T-cell activation, and dermal DCs release IL-12 and IL-23 to promote a T_H1 and T_H17 response, respectively. The growth factors released by these helper T cells sustain neoangiogenesis, stimulate epidermal hyperproliferation, alter epidermal differentiation, and decrease susceptibility to apoptosis that characterizes the erythematous hypertrophic scaling lesions of psoriasis.²¹ Furthermore, the cytokines produced from the immunologic response, such as tumor necrosis factor (TNF) α, IFN-γ, and IL-2, correspond to cytokines that are upregulated in psoriatic plaques.²²

Integral components of the immunologic synapse complex include co-stimulatory signals such as CD28, CD40, CD80, and CD86, as well as adhesion molecules such as cytotoxic T-lymphocyte antigen 4 and lymphocyte function-associated antigen (LFA) 1, which possess corresponding receptors on the T cell. These molecules play a key role in T-cell signaling, as their disruption has been shown to decrease T-cell responsiveness and associated inflammation. The B7 family of molecules routinely interacts with CD28 T cells to co-stimulate T-cell activation. Cytotoxic T-lymphocyte antigen 4 immunoglobulin, an antibody on the T-cell surface, targets B7 and interferes with signaling between B7 and CD28. In psoriatic patients, this blockade was demonstrated to attenuate the T-cell response and correlated with a clinical and histological decrease in psoriasiform hyperplasia.²³ Biologic therapies that disrupt the LFA-1 component of the immunologic synapse also have demonstrated efficacy in the treatment of psoriasis. Alefacept is a human LFA-3 fusion protein that binds CD2 on T cells and blocks the interaction between LFA-3 on APCs and CD2 on memory CD45RO⁺ T cells and induces apoptosis of such T cells. Efalizumab is a human monoclonal antibody to the CD11 chain of LFA-1 that blocks the interaction between LFA-1 on the T cell and intercellular adhesion molecule 1 on an APC or endothelial cell. Both alefacept and efalizumab, 2 formerly marketed biologic therapies, demonstrated remarkable clinical reduction of psoriatic lesions, and alefacept has been shown to produce disease remission for up to 18 months after discontinuation of therapy.^24-26

NK T Cells

Natural killer T cells represent a subset of CD3⁺ T cells present in psoriatic plaques. Although NK T cells possess a TCR, they differ from T cells by displaying NK receptors comprised of lectin and immunoglobulin families. These cells exhibit remarkable specificity and are activated upon recognition of glycolipids presented by CD1d molecules. This process occurs in contrast to CD4⁺ and CD8⁺ T cells, which, due to their TCR diversity, respond to peptides processed by APCs and displayed on MHC molecules. Natural killer T cells can be classified into 2 subsets: (1) one group that expresses CD4 and preferentially produces T_H1- versus T_H2-type cytokines, and (2) another group that lacks CD4 and CD8 that only produces T_H1-type cytokines. The innate immune system employs NK T cells early in the immune response because of their direct cytotoxicity and rapid production of cytokines such as IFN-γ, which promotes a T_H1 inflammatory response, and IL-4, which promotes the development of T_H2 cells. Excessive or dysfunctional NK T cells have been associated with autoimmune diseases such as multiple sclerosis and inflammatory bowel disease as well as allergic contact dermatitis.^27-29

In psoriasis, NK T cells are located in the epidermis, closely situated to epidermal keratinocytes, which suggests a role for direct antigen presentation. Furthermore, CD1d is overexpressed throughout the epidermis of psoriatic plaques, whereas normally CD1d expression is confined to terminally differentiated keratinocytes. An in vitro study examining cytokine-based inflammation demonstrative of psoriasis treated cultured CD1d-positive keratinocytes with interferon gamma in the presence of alpha-galactosylceramide of the lectin family.³⁰ Interferon gamma was observed to enhance keratinocyte CD1d expression, and subsequently, CD1d-positive keratinocytes were found to activate NK T cells to produce high levels of IFN-γ, while levels of IL-4 remained undetectable. The preferential production of IFN-γ supports a T_H1-mediated mechanism regulated by NK T cells in the immunopathogenesis of psoriasis.

Dendritic Cells

Dendritic cells are APCs that process antigens in the tissues in which they reside, after which they migrate to local lymph nodes where they present their native antigens to T cells. This process allows the T-cell response to be tailored to the appropriate antigens in the corresponding tissues. Immature DCs that capture antigens mature by migrating to the T-cell center of the lymph node where they present their antigens to either MHC molecules or the CD1 family. This presentation results in T-cell proliferation and differentiation that correlates with the required type of T-cell response. Multiple subsets of APCs, including myeloid and plasmacytoid DCs, are highly represented in the epidermis and dermis of psoriatic plaques as compared with normal skin.³¹ Dermal DCs are thought to be responsible for activating both the T_H1 and T_H17 infiltrate by secreting IL-12 and IL-23, respectively. This mixed cellular response secretes cytokines and leads to a cascade of events involving keratinocytes, fibroblasts, endothelial cells, and neutrophils that create the cutaneous lesions seen in psoriasis.³

Although DCs play a pivotal role in eliciting an immune response against a foreign invader, they also contribute to the establishment of tolerance. Throughout their maturation, DCs are continuously sensing their environment, which shapes their production of T_H1- versus T_H2-type cytokines and subsequently the nature of the T-cell response. When challenged with a virus, bacteria, or unchecked cell growth, DCs mature into APCs. However, in the absence of a strong stimulus, DCs fail to mature into APCs and present self-peptides with MHC molecules, thereby creating regulatory T cells involved in peripheral tolerance.³² If this balance between immunogenic APCs and housekeeping T cells is upset, inflammatory conditions such as psoriasis can result.

Cytokines

Cytokines are low-molecular-weight glycoproteins that function as signals to produce inflammation, defense, tissue repair and remodeling, fibrosis, angiogenesis, and restriction of neoplastic growth.³³ Cytokines are produced by immunocytes such as lymphocytes and macrophages as well as nonimmunocytes such as endothelial cells and keratinocytes. Proinflammatory cytokines include IL-1, IL-2, the IL-17 family, IFN-γ, and TNF-α, while anti-inflammatory cytokines include IL-4 and IL-10. A relative preponderance of T_H1 proinflammatory cytokines or an insufficiency of T_H2 anti-inflammatory cytokines induces local inflammation and recruitment of additional immunocyte populations, which produce added cytokines.³⁴ A vicious cycle of inflammation occurs that results in cutaneous manifestations such as a plaque. Psoriatic lesions are characterized by a relative increase of T_H1-type (eg, IL-2, IFN-γ, TNF-α, TNF-β) to T_H2-type (eg, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13) cytokines and an increase in T_H17-type cytokines. Natural killer T cells stimulated by CD1d-overexpressing keratinocytes increase production of proinflammatory IFN-γ without effect on the anti-inflammatory IL-4. In addition to the cytokines produced by T cells, APCs produce IL-18, IL-23, and TNF-α found in the inflammatory infiltrate of psoriatic plaques. Both IL-18 and IL-23 stimulate T_H1 cells to produce IFN-γ, and IL-23 stimulates T_H17 cells. Clearly, a T_H1- and T_H17-type pattern governs the immune effector cells and their respective cytokines present in psoriatic skin.

Tumor Necrosis Factor α

Although a network of cytokines is responsible for the inflammation of psoriasis, TNF-α has been implicated as a master proinflammatory cytokine of the innate immune response due to its widespread targets and sources. Tumor necrosis factor α is produced by activated T cells, keratinocytes, NK cells, macrophages, monocytes, Langerhans APCs, and endothelial cells. Psoriatic lesions demonstrate high concentrations of TNF-α, while the synovial fluid of psoriatic arthritis patients demonstrates elevated concentrations of TNF-α, IL-1, IL-6, and IL-8.³⁴ In psoriasis, TNF-α supports the expression of adhesion molecules (intercellular adhesion molecule 1 and P- and E-selectin), angiogenesis via vascular endothelial growth factor, the synthesis of proinflammatory molecules (IL-1, IL-6, IL-8, and nuclear factor κβ), and keratinocyte hyperproliferation via vasoactive intestinal peptide.³⁵

A role for TNF-α in psoriasis treatment was serendipitously discovered in a trial for Crohn disease in which infliximab, a mouse-human IgG1 anti–TNF-α monoclonal antibody, was observed to clear psoriatic plaques in a patient with both Crohn disease and psoriasis.³⁶ Immunotherapies that target TNF-α, including infliximab, etanercept, and adalimumab, demonstrate notable efficacy in the treatment of psoriasis.^37-39 Tumor necrosis factor α is regarded as the driver of the inflammatory cycle of psoriasis due to its numerous modes of production, capability to amplify other proinflammatory signals, and the efficacy and rapidity with which it produces clinical improvements in psoriasis.

IL-23/T_H17 Axis

A new distinct population of helper T cells has been shown to play an important role in psoriasis. These cells develop with the help of IL-23 (secreted by dermal DCs) and subsequently secrete cytokines such as IL-17; they are, therefore, named T_H17 cells. CD161 is considered a surface marker for these cells.⁴⁰ Strong evidence for this IL-23/T_H17 axis has been shown in mouse and human models as well as in genetic studies.

IL-23 is a cytokine that shares the p40 subunit with IL-12 and has been linked to autoimmune diseases in both mice and humans.³ It is required for optimal development of T_H17 cells⁴¹ from a committed CD4⁺ T-cell population after exposure to transforming growth factor β1 in combination with other proinflammatory cytokines.^42,43 IL-23 messenger RNA is produced at higher levels in inflammatory psoriatic skin lesions versus uninvolved skin,⁴⁴ and intradermal IL-23 injections in mice produced lesions resembling psoriasis macroscopically and microscopically.⁴⁵ Furthermore, several systemic therapies have been shown to modulate IL-23 levels and correlate with clinical benefit.³ Alterations in the gene for the IL-23 receptor have been shown to be protective for psoriasis,^46-48 and the gene coding for the p40 subunit is associated with psoriasis.^46,47

Type 17 helper T cells produce a number of cytokines, such as IL-22, IL-17A, IL-17F, and IL-26; the latter 3 are considered to be specific to this lineage.⁴² IL-22 acts on outer body barrier tissues, such as the skin, and has antimicrobial activity. Blocking the activity of IL-22 in mice prevented the development of skin lesions,⁴⁹ and psoriasis patients have elevated levels of IL-22 in the skin and blood.^50,51 The IL-17 cytokines induce the expression of proinflammatory cytokines, colony-stimulating factors, and chemokines, and they recruit, mobilize, and activate neutrophils.⁵² IL-17 messenger RNA was found in lesional psoriatic skin but not unaffected skin,⁵³ and cells isolated from the dermis of psoriatic skin have been shown to produce IL-17.⁵⁴ IL-17A is not elevated in the serum of psoriatic patients (unlike other autoimmune diseases),⁵⁵ and it is, therefore, thought that T_H17 cells and IL-17A production are localized to the affected psoriatic skin. Consistent with this concept is the finding that treatments such as cyclosporin A and anti-TNF agents decrease proinflammatory cytokines in lesional skin but not in the periphery.^56-58 These cytokines released by T_H17 cells in addition to those released by T_H1 cells act on keratinocytes and produce epidermal hyperproliferation, acanthosis, and hyperparakeratosis characteristic of psoriasis.³

New therapies have been developed to target the IL-23/T_H17 axis. Ustekinumab is approved for moderate to severe plaque psoriasis. This treatment’s effect may be sustained for up to 3 years, it is generally well tolerated, and it may be useful for patients refractory to anti-TNF therapy such as etanercept.⁵⁹ Briakinumab, another blocker of IL-12 and IL-23, was studied in phase 3 clinical trials, but its development was discontinued due to safety concerns.⁶⁰ Newer drugs targeting the IL-23/T_H17 axis include secukinumab, ixekizumab, brodalumab, guselkumab, and tildrakizumab.

Genetic Basis of Psoriasis

Psoriasis is a disease of overactive immunity in genetically susceptible individuals. Because patients exhibit varying skin phenotypes, extracutaneous manifestations, and disease courses, multiple genes resulting from linkage disequilibrium are believed to be involved in the pathogenesis of psoriasis. A decade of genome-wide linkage scans have established that PSORS1 is the strongest susceptibility locus demonstrable through family linkage studies; PSORS1 is responsible for up to 50% of the genetic component of psoriasis.⁶¹ More recently, HLA-Cw6 has received the most attention as a candidate gene of the PSORS1 susceptibility locus on the MHC class I region on chromosome 6p21.3.⁶² This gene may function in antigen presentation via MHC class I, which aids in the activation of the overactive T cells characteristic of psoriatic inflammation.

Studies involving the IL-23/T_H17 axis have shown genetics to play a role. Individuals may be protected from psoriasis with a nonsynonymous nucleotide substitution in the IL23R gene,^47-49 and certain haplotypes of the IL23R gene are associated with the disease^47,49 in addition to other autoimmune conditions.

Genomic scans have shown additional susceptibility loci for psoriasis on chromosomes 1q21, 3q21, 4q32-35, 16q12, and 17q25. Two regions on chromosome 17q were recently localized via mapping, which demonstrated a 6 megabase pairs separation, thereby indicating independent linkage factors. Genes SLC9A3R1 and NAT9 are present in the first region, while RAPTOR is demonstrated in the second region.⁶³SLC9A3R1 and NAT9 are players that regulate signal transduction, the immunologic synapse, and T-cell growth. RAPTOR is involved in T-cell function and growth pathways. Using these genes as an example, we can predict that the alterations of regulatory genes, even those yet undetermined, can enhance T-cell proliferation and inflammation manifested in psoriasis.

Conclusion

Psoriasis is a complex disease whereby multiple exogenous and endogenous stimuli incite already heightened innate immune responses in genetically predetermined individuals. The disease process is a result of a network of cell types, including T cells, DCs, and keratinocytes that, with the production of cytokines, generate a chronic inflammatory state. Our understanding of these cellular interactions and cytokines originates from developments, some meticulously planned, others serendipitous, in the fields of immunology, cell and molecular biology, and genetics. Such progress has fostered the creation of targeted immune therapy that has demonstrated remarkable efficacy in psoriasis treatment. Further study of the underlying pathophysiology of psoriasis may provide additional targets for therapy.

This special issue is dedicated to resident education on psoriasis. With that in mind, we hope to address many topics of interest to those in training. Over the years, diet has been a hot topic among psoriasis patients. They want to know how diet affects psoriasis and what changes can be made to their diet to improve their condition. Although they have expected specific answers, my response has usually been that they should, of course, eat an overall healthy and balanced diet, and lose weight if necessary. I have continued, however, that no specific diet has been recommended. However, now we have some information that may start to give us some answers.

The Mediterranean diet has been regarded as a healthy regimen.¹ This diet emphasizes eating primarily plant-based foods, such as fruits and vegetables; whole grains; legumes; and nuts. Other recommendations include replacing butter with healthy fats such as olive oil and canola oil, using herbs and spices instead of salt to flavor foods, and limiting red meat to no more than a few times a month.¹

As we know, psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk for metabolic syndrome and cardiovascular events.¹ Phan et al¹ hypothesized a positive effect of the Mediterranean diet on psoriasis. They performed a study to assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.¹

The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009.¹ Data were collected and analyzed between April 2017 and June 2017. Individuals with psoriasis were identified utilizing a validated online questionnaire and then categorized by disease severity into 1 of 3 groups: severe psoriasis, nonsevere psoriasis, and psoriasis free.¹

During the initial 2 years of participation in the cohort, data on dietary intake (including alcohol) were gathered to calculate the MEDI-LITE score, ranging from 0 (no adherence) to 18 (maximum adherence).¹ Of the 158,361 total web-based participants, 35,735 (23%) replied to the psoriasis questionnaire.¹ Of the respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (cases occurring >2 years after participant inclusion in the cohort). After adjustment for confounding factors, the investigators found a significant inverse relationship between the MEDI-LITE score and having severe psoriasis (odds ratio [OR], 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile [score of 8 to 9]; and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile [score of 10 to 18]).¹

The authors noted that patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet.¹ They commented that this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.¹ These findings are by no means definitive, but it is a first step in helping us define more specific dietary recommendations for psoriasis.

This issue includes several articles looking at various facets of psoriasis important to residents, including the pathophysiology of psoriasis,² treatment approach using biologic therapies,³ risk factors and triggers for psoriasis,⁴ and the psychosocial impact of psoriasis.⁵ We hope that you find this issue enjoyable and informative.

This special issue is dedicated to resident education on psoriasis. With that in mind, we hope to address many topics of interest to those in training. Over the years, diet has been a hot topic among psoriasis patients. They want to know how diet affects psoriasis and what changes can be made to their diet to improve their condition. Although they have expected specific answers, my response has usually been that they should, of course, eat an overall healthy and balanced diet, and lose weight if necessary. I have continued, however, that no specific diet has been recommended. However, now we have some information that may start to give us some answers.

The Mediterranean diet has been regarded as a healthy regimen.¹ This diet emphasizes eating primarily plant-based foods, such as fruits and vegetables; whole grains; legumes; and nuts. Other recommendations include replacing butter with healthy fats such as olive oil and canola oil, using herbs and spices instead of salt to flavor foods, and limiting red meat to no more than a few times a month.¹

As we know, psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk for metabolic syndrome and cardiovascular events.¹ Phan et al¹ hypothesized a positive effect of the Mediterranean diet on psoriasis. They performed a study to assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.¹

The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009.¹ Data were collected and analyzed between April 2017 and June 2017. Individuals with psoriasis were identified utilizing a validated online questionnaire and then categorized by disease severity into 1 of 3 groups: severe psoriasis, nonsevere psoriasis, and psoriasis free.¹

During the initial 2 years of participation in the cohort, data on dietary intake (including alcohol) were gathered to calculate the MEDI-LITE score, ranging from 0 (no adherence) to 18 (maximum adherence).¹ Of the 158,361 total web-based participants, 35,735 (23%) replied to the psoriasis questionnaire.¹ Of the respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (cases occurring >2 years after participant inclusion in the cohort). After adjustment for confounding factors, the investigators found a significant inverse relationship between the MEDI-LITE score and having severe psoriasis (odds ratio [OR], 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile [score of 8 to 9]; and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile [score of 10 to 18]).¹

The authors noted that patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet.¹ They commented that this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.¹ These findings are by no means definitive, but it is a first step in helping us define more specific dietary recommendations for psoriasis.

This issue includes several articles looking at various facets of psoriasis important to residents, including the pathophysiology of psoriasis,² treatment approach using biologic therapies,³ risk factors and triggers for psoriasis,⁴ and the psychosocial impact of psoriasis.⁵ We hope that you find this issue enjoyable and informative.

This special issue is dedicated to resident education on psoriasis. With that in mind, we hope to address many topics of interest to those in training. Over the years, diet has been a hot topic among psoriasis patients. They want to know how diet affects psoriasis and what changes can be made to their diet to improve their condition. Although they have expected specific answers, my response has usually been that they should, of course, eat an overall healthy and balanced diet, and lose weight if necessary. I have continued, however, that no specific diet has been recommended. However, now we have some information that may start to give us some answers.

The Mediterranean diet has been regarded as a healthy regimen.¹ This diet emphasizes eating primarily plant-based foods, such as fruits and vegetables; whole grains; legumes; and nuts. Other recommendations include replacing butter with healthy fats such as olive oil and canola oil, using herbs and spices instead of salt to flavor foods, and limiting red meat to no more than a few times a month.¹

As we know, psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk for metabolic syndrome and cardiovascular events.¹ Phan et al¹ hypothesized a positive effect of the Mediterranean diet on psoriasis. They performed a study to assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.¹

The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009.¹ Data were collected and analyzed between April 2017 and June 2017. Individuals with psoriasis were identified utilizing a validated online questionnaire and then categorized by disease severity into 1 of 3 groups: severe psoriasis, nonsevere psoriasis, and psoriasis free.¹

During the initial 2 years of participation in the cohort, data on dietary intake (including alcohol) were gathered to calculate the MEDI-LITE score, ranging from 0 (no adherence) to 18 (maximum adherence).¹ Of the 158,361 total web-based participants, 35,735 (23%) replied to the psoriasis questionnaire.¹ Of the respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (cases occurring >2 years after participant inclusion in the cohort). After adjustment for confounding factors, the investigators found a significant inverse relationship between the MEDI-LITE score and having severe psoriasis (odds ratio [OR], 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile [score of 8 to 9]; and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile [score of 10 to 18]).¹

The authors noted that patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet.¹ They commented that this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.¹ These findings are by no means definitive, but it is a first step in helping us define more specific dietary recommendations for psoriasis.

This issue includes several articles looking at various facets of psoriasis important to residents, including the pathophysiology of psoriasis,² treatment approach using biologic therapies,³ risk factors and triggers for psoriasis,⁴ and the psychosocial impact of psoriasis.⁵ We hope that you find this issue enjoyable and informative.

ATLANTA – Among patients with relapsing-remitting multiple sclerosis, higher body mass index, but not vitamin D status, appears to be related to greater loss of gray matter brain volume over time, results from a 5-year analysis showed.

“We had previously known that obesity is a risk factor for developing MS, and among those who already have the disease, obesity-related comorbidities are associated with increased morbidity and mortality,” lead study author Ellen M. Mowry, MD, said in an interview at the annual meeting of the American Neurological Association. “Loss of brain tissue, especially as measured by reduced volume of gray matter noted on brain MRI, is predictive of long-term disability in MS. While we await the results of confirmatory studies and randomized trials, this study adds to the growing body of evidence suggesting there may be a role for modification of lifestyle factors in mitigating longer-term MS-related disability risk.”

In an effort to determine if body mass index (BMI) or vitamin D status is associated with longer-term MRI measures of neurodegeneration, Dr. Mowry and her colleagues drew from 469 patients participating in a longitudinal MS cohort study at the University of California, San Francisco, known as EPIC. Participants had clinical evaluations, brain MRI, and blood draws annually and were followed for 5 years. The main outcomes of interest were BMI and serum 25-hydroxyvitamin D levels measured over the time period, and their relationship to brain volume.


At baseline, the mean age of patients was 42 years, 70% were female, their mean BMI was 25 kg/m², and their mean serum vitamin D level was 27.8 ng/mL. Dr. Mowry, a neurologist at Johns Hopkins University, Baltimore, and her colleagues found that over time, each 1-kg/m² higher BMI was independently associated with reduced gray matter in multivariate models (–1.1 mL; P = .001). In addition, each 1-kg/m² higher BMI over time was independently associated with greater declines in normalized brain parenchymal brain volume (–1.1 mL; P = .039). Elevated vitamin D levels, however, did not appear to be meaningfully associated with brain volumes.

Dr. Mowry acknowledged certain limitations of the study, including its nonrandomized design. “Such a trial may be warranted but I believe will be challenging to conduct,” she said. “Also, this cohort was designed to assess the association of genes with brain MRI outcomes, and so the people included were racially homogeneous – only Caucasians were included. Since MS risk is especially high among African Americans in recent years, and African Americans appear overall to have a higher risk of long-term disability, it is important to evaluate these and other prognostic factors amongst a more representative group of people with MS.”

The study received funding support from the National Institutes of Health, GlaxoSmithKline, and Biogen. Dr. Mowry disclosed that she has received medication from Teva for use in a clinical trial. In addition, she has been the primary investigator for studies sponsored by Biogen and Sun Pharma, and has conducted investigator-initiated studies sponsored by Genzyme and Biogen.

[email protected]

SOURCE: Ann Neurol. 2018;84[S22]:S206-7. Abstract M250.

ATLANTA – Among patients with relapsing-remitting multiple sclerosis, higher body mass index, but not vitamin D status, appears to be related to greater loss of gray matter brain volume over time, results from a 5-year analysis showed.

“We had previously known that obesity is a risk factor for developing MS, and among those who already have the disease, obesity-related comorbidities are associated with increased morbidity and mortality,” lead study author Ellen M. Mowry, MD, said in an interview at the annual meeting of the American Neurological Association. “Loss of brain tissue, especially as measured by reduced volume of gray matter noted on brain MRI, is predictive of long-term disability in MS. While we await the results of confirmatory studies and randomized trials, this study adds to the growing body of evidence suggesting there may be a role for modification of lifestyle factors in mitigating longer-term MS-related disability risk.”

In an effort to determine if body mass index (BMI) or vitamin D status is associated with longer-term MRI measures of neurodegeneration, Dr. Mowry and her colleagues drew from 469 patients participating in a longitudinal MS cohort study at the University of California, San Francisco, known as EPIC. Participants had clinical evaluations, brain MRI, and blood draws annually and were followed for 5 years. The main outcomes of interest were BMI and serum 25-hydroxyvitamin D levels measured over the time period, and their relationship to brain volume.


At baseline, the mean age of patients was 42 years, 70% were female, their mean BMI was 25 kg/m², and their mean serum vitamin D level was 27.8 ng/mL. Dr. Mowry, a neurologist at Johns Hopkins University, Baltimore, and her colleagues found that over time, each 1-kg/m² higher BMI was independently associated with reduced gray matter in multivariate models (–1.1 mL; P = .001). In addition, each 1-kg/m² higher BMI over time was independently associated with greater declines in normalized brain parenchymal brain volume (–1.1 mL; P = .039). Elevated vitamin D levels, however, did not appear to be meaningfully associated with brain volumes.

Dr. Mowry acknowledged certain limitations of the study, including its nonrandomized design. “Such a trial may be warranted but I believe will be challenging to conduct,” she said. “Also, this cohort was designed to assess the association of genes with brain MRI outcomes, and so the people included were racially homogeneous – only Caucasians were included. Since MS risk is especially high among African Americans in recent years, and African Americans appear overall to have a higher risk of long-term disability, it is important to evaluate these and other prognostic factors amongst a more representative group of people with MS.”

The study received funding support from the National Institutes of Health, GlaxoSmithKline, and Biogen. Dr. Mowry disclosed that she has received medication from Teva for use in a clinical trial. In addition, she has been the primary investigator for studies sponsored by Biogen and Sun Pharma, and has conducted investigator-initiated studies sponsored by Genzyme and Biogen.

[email protected]

SOURCE: Ann Neurol. 2018;84[S22]:S206-7. Abstract M250.

ATLANTA – Among patients with relapsing-remitting multiple sclerosis, higher body mass index, but not vitamin D status, appears to be related to greater loss of gray matter brain volume over time, results from a 5-year analysis showed.

“We had previously known that obesity is a risk factor for developing MS, and among those who already have the disease, obesity-related comorbidities are associated with increased morbidity and mortality,” lead study author Ellen M. Mowry, MD, said in an interview at the annual meeting of the American Neurological Association. “Loss of brain tissue, especially as measured by reduced volume of gray matter noted on brain MRI, is predictive of long-term disability in MS. While we await the results of confirmatory studies and randomized trials, this study adds to the growing body of evidence suggesting there may be a role for modification of lifestyle factors in mitigating longer-term MS-related disability risk.”

In an effort to determine if body mass index (BMI) or vitamin D status is associated with longer-term MRI measures of neurodegeneration, Dr. Mowry and her colleagues drew from 469 patients participating in a longitudinal MS cohort study at the University of California, San Francisco, known as EPIC. Participants had clinical evaluations, brain MRI, and blood draws annually and were followed for 5 years. The main outcomes of interest were BMI and serum 25-hydroxyvitamin D levels measured over the time period, and their relationship to brain volume.


At baseline, the mean age of patients was 42 years, 70% were female, their mean BMI was 25 kg/m², and their mean serum vitamin D level was 27.8 ng/mL. Dr. Mowry, a neurologist at Johns Hopkins University, Baltimore, and her colleagues found that over time, each 1-kg/m² higher BMI was independently associated with reduced gray matter in multivariate models (–1.1 mL; P = .001). In addition, each 1-kg/m² higher BMI over time was independently associated with greater declines in normalized brain parenchymal brain volume (–1.1 mL; P = .039). Elevated vitamin D levels, however, did not appear to be meaningfully associated with brain volumes.

Dr. Mowry acknowledged certain limitations of the study, including its nonrandomized design. “Such a trial may be warranted but I believe will be challenging to conduct,” she said. “Also, this cohort was designed to assess the association of genes with brain MRI outcomes, and so the people included were racially homogeneous – only Caucasians were included. Since MS risk is especially high among African Americans in recent years, and African Americans appear overall to have a higher risk of long-term disability, it is important to evaluate these and other prognostic factors amongst a more representative group of people with MS.”

The study received funding support from the National Institutes of Health, GlaxoSmithKline, and Biogen. Dr. Mowry disclosed that she has received medication from Teva for use in a clinical trial. In addition, she has been the primary investigator for studies sponsored by Biogen and Sun Pharma, and has conducted investigator-initiated studies sponsored by Genzyme and Biogen.

[email protected]

SOURCE: Ann Neurol. 2018;84[S22]:S206-7. Abstract M250.

American Indian/Alaska Native (AI/AN) women face the same barriers as all low-income minority women face in accessing preventive care, but according to researchers from Rutgers University in New Jersey and University of Arizona, they also face “unique challenges and circumstances.” The researchers reviewed 18 studies to find out more about facilitators of, and barriers to, breast cancer screening.

Low-income women are more likely to be diagnosed at a later stage and to die of breast cancer, one study found. The factors are well known: cost, lack of a usual source of care, lack of insurance, distance from a facility, and lack of transportation.

However, the researchers of the meta-analysis say, “compounding these barriers,” AI/AN women expressed the belief that preventive care is not a priority, especially when it is their own preventive care. Moreover, some barriers that might be unique to the AI/AN women included concern with “manifest destiny”: the assumption that thinking or talking about breast cancer can cause it, for instance. One study examined “traditionality” and found women who could be seen as more traditional, defining themselves as living an “Indian way of life,” were less likely to be current with screening. Other women expressed mistrust in the technology of screening or spoke about perception of discrimination in the health care system.

Although this population has access to screening through IHS facilities, women who also have insurance (typically Medicaid) are more likely to get screened. Women in rural areas who lived near an IHS facility were more likely than were urban women to get mammograms. The researchers suggest this could be because rural women are more likely to be isolated from other mammogram facilities. Too, the IHS is “chronically underfunded,” the researchers note, likely a cause of the health disparities and limiting scope of services.

Their review made clear that efforts to intervene with AI/AN women to increase breast cancer screening have been limited, the researchers say. The intervention studies they reviewed “were not successful in improving screening rates or adherence.” The qualitative studies, on the other hand, suggest that women may be more responsive to locally supportive, targeted, and culturally appropriate interventions that respect traditionality yet encourage trust in the medical system.

American Indian/Alaska Native (AI/AN) women face the same barriers as all low-income minority women face in accessing preventive care, but according to researchers from Rutgers University in New Jersey and University of Arizona, they also face “unique challenges and circumstances.” The researchers reviewed 18 studies to find out more about facilitators of, and barriers to, breast cancer screening.

Low-income women are more likely to be diagnosed at a later stage and to die of breast cancer, one study found. The factors are well known: cost, lack of a usual source of care, lack of insurance, distance from a facility, and lack of transportation.

However, the researchers of the meta-analysis say, “compounding these barriers,” AI/AN women expressed the belief that preventive care is not a priority, especially when it is their own preventive care. Moreover, some barriers that might be unique to the AI/AN women included concern with “manifest destiny”: the assumption that thinking or talking about breast cancer can cause it, for instance. One study examined “traditionality” and found women who could be seen as more traditional, defining themselves as living an “Indian way of life,” were less likely to be current with screening. Other women expressed mistrust in the technology of screening or spoke about perception of discrimination in the health care system.

Although this population has access to screening through IHS facilities, women who also have insurance (typically Medicaid) are more likely to get screened. Women in rural areas who lived near an IHS facility were more likely than were urban women to get mammograms. The researchers suggest this could be because rural women are more likely to be isolated from other mammogram facilities. Too, the IHS is “chronically underfunded,” the researchers note, likely a cause of the health disparities and limiting scope of services.

Their review made clear that efforts to intervene with AI/AN women to increase breast cancer screening have been limited, the researchers say. The intervention studies they reviewed “were not successful in improving screening rates or adherence.” The qualitative studies, on the other hand, suggest that women may be more responsive to locally supportive, targeted, and culturally appropriate interventions that respect traditionality yet encourage trust in the medical system.

American Indian/Alaska Native (AI/AN) women face the same barriers as all low-income minority women face in accessing preventive care, but according to researchers from Rutgers University in New Jersey and University of Arizona, they also face “unique challenges and circumstances.” The researchers reviewed 18 studies to find out more about facilitators of, and barriers to, breast cancer screening.

Low-income women are more likely to be diagnosed at a later stage and to die of breast cancer, one study found. The factors are well known: cost, lack of a usual source of care, lack of insurance, distance from a facility, and lack of transportation.

However, the researchers of the meta-analysis say, “compounding these barriers,” AI/AN women expressed the belief that preventive care is not a priority, especially when it is their own preventive care. Moreover, some barriers that might be unique to the AI/AN women included concern with “manifest destiny”: the assumption that thinking or talking about breast cancer can cause it, for instance. One study examined “traditionality” and found women who could be seen as more traditional, defining themselves as living an “Indian way of life,” were less likely to be current with screening. Other women expressed mistrust in the technology of screening or spoke about perception of discrimination in the health care system.

Although this population has access to screening through IHS facilities, women who also have insurance (typically Medicaid) are more likely to get screened. Women in rural areas who lived near an IHS facility were more likely than were urban women to get mammograms. The researchers suggest this could be because rural women are more likely to be isolated from other mammogram facilities. Too, the IHS is “chronically underfunded,” the researchers note, likely a cause of the health disparities and limiting scope of services.

Their review made clear that efforts to intervene with AI/AN women to increase breast cancer screening have been limited, the researchers say. The intervention studies they reviewed “were not successful in improving screening rates or adherence.” The qualitative studies, on the other hand, suggest that women may be more responsive to locally supportive, targeted, and culturally appropriate interventions that respect traditionality yet encourage trust in the medical system.

In July 2018, The BMJ published a study examining the cardiovascular risks of diclofenac initiation compared with initiation of other traditional non-steroidal anti-inflammatory drugs, initiation of paracetamol, and no initiation. The results showed a 50% increase in adverse events among diclofenac initiators compared with non-initiators (as well as a 20% increase over paracetamol/ibuprofen initiators, and 30% increase over naproxen initiators). (Read the full study here). Here, I asked several of my colleagues to weigh in on the results of this study and its implications for our practices, and then I share my own thoughts on these findings:

Marcelo Bigal, MD, PhD
Chief Medical Officer, Purdue Pharma

It is well established that NSAIDs are associated with increased risk of poor cardiovascular outcomes. This study offers powerful evidence that the risk after frequent diclofenac use is disproportionally increased relative to other commonly used NSAIDs, such as ibuprofen or naproxen. It is relevant to discuss the implications of the findings for the treatment of migraine.

The acute treatment of migraine associated with attack-related disability should favor triptans as first line therapy, not NSAIDs. Because triptans are vasoconstrictive medications, unmet needs exist in patients at cardiovascular risk. Anti-CGRP acute migraine therapies, as well as “ditans” (5HT-1f antagonist) are under regulatory review and may address the needs of these patients. In the context of acute migraine therapy, diclofenac and NSAIDs are typically used instead of triptans, or with triptans when additional efficacy is needed. We certainly find that the use of diclofenac in these situations should be judicious, and reserved to those who clearly need it, have infrequent migraine attacks, and are otherwise healthy.

Diclofenac is also often used in the emergency department in many countries as a rescue therapy. In a series of clinical trials where we tested most commonly used drugs in this setting in Brazil, we found that efficacies were 83.6% for intravenous dipyrone, 66.7% for intramuscular diclofenac and 81.8% for intravenous chlorpromazine. We continue to believe that diclofenac is an important, non-sedative and non-opioid option for the management of headaches in the emergency department, assuming that at discharge, patients would receive proper guidance on the management of migraine without relying on frequent use of NSAIDs.

Jack Schim, MD
Co-Director, The Headache Center of Southern California

This article supports findings of prior epidemiologic studies correlating exposure to NSAIDs with increased cerebrovascular and cardiovascular risk. Prior studies have shown a dose-related response in risk associated with NSAID therapy, supporting a causal association. However, while relative risk is significantly higher in individuals with NSAID exposure, the absolute risk remains very low. The greater risk from NSAIDs continues to be to the kidneys, and to the stomach.  

As with all therapies, we need to weigh the advantages and disadvantages of NSAID therapy with our headache patients. All medications carry their own risks. For acute treatment of migraines, our primary tool, triptans, are contraindicated in a significant subset of individuals, including patients with ischemic coronary artery as well as those with history of stroke or transient ischemic attack (TIA). The alternatives, NSAIDs, dopamine blocking agents, have utility and risks.

Diclofenac powder to be dissolved in water is an effective abortive for migraine for many individuals. In general, our patients have intermittent exposure, preferably not more than 2 days per week. For the appropriate individual, NSAIDS, including diclofenac, remain an important tool in the acute care armamentarium.

Rob Cowan, MD, FAAN, FAHS
Higgins Professor of Neurology and Neurosciences
Chief, Division of Headache Medicine, Dept. of Neurology and Neurosciences
Director, Stanford University School of Medicine

These kinds of large, population-based studies must be interpreted with caution. While they may emulate the protocol of prospective studies, they lack proper inclusion/exclusion criteria, particularly with respect to indication. It may be reasonable to assume that the population of diclofenac users is "sicker" than the general population and the population that is using cheaper, more accessible NSAIDs or paracetamol. Without knowing the access and economic issues in Denmark, it is difficult to weigh these variables in the study. Thus, while it is certainly an important issue to explore (the relative risks and benefits of a given medication within a class), the absence of a well-designed, prospective study precludes any definitive conclusion regarding relative safety and risk profile for Diclofenac.

+++

These are great comments by my colleagues. My impression after seeing the data and reading my colleague’s comments, is that diclofenac may be riskier than other NSAIDs in this study; but when used properly in generally healthy migraineurs, it is probably more effective than dangerous when evaluating the risk/benefit ratio. When diclofenac is used as an oral solution (Cambia), 2 days per week or less, in a patient without serious gastrointestinal, renal, cardiac or hypertensive issues, it appears to pose little risk to the patient. When given to the wrong patient, or when taken too frequently, is could be dangerous. What I really like about this preparation is that it causes fewer adverse events compared to triptans and works very quickly. It can be used when triptans have been used enough that week or if they tend to cause significant adverse events when taken. We can use diclofenac for our headache patients, but we should remain vigilant to give it cautiously and only to patients who have no contraindication to its use.

Please write to us at Neurology Reviews Migraine Resource Center ([email protected]) with your opinions.

Alan M. Rapoport, M.D.
Editor-in-Chief
Migraine Resource Center

Clinical Professor of Neurology
The David Geffen School of Medicine at UCLA
Los Angeles, California

In July 2018, The BMJ published a study examining the cardiovascular risks of diclofenac initiation compared with initiation of other traditional non-steroidal anti-inflammatory drugs, initiation of paracetamol, and no initiation. The results showed a 50% increase in adverse events among diclofenac initiators compared with non-initiators (as well as a 20% increase over paracetamol/ibuprofen initiators, and 30% increase over naproxen initiators). (Read the full study here). Here, I asked several of my colleagues to weigh in on the results of this study and its implications for our practices, and then I share my own thoughts on these findings:

Marcelo Bigal, MD, PhD
Chief Medical Officer, Purdue Pharma

It is well established that NSAIDs are associated with increased risk of poor cardiovascular outcomes. This study offers powerful evidence that the risk after frequent diclofenac use is disproportionally increased relative to other commonly used NSAIDs, such as ibuprofen or naproxen. It is relevant to discuss the implications of the findings for the treatment of migraine.

The acute treatment of migraine associated with attack-related disability should favor triptans as first line therapy, not NSAIDs. Because triptans are vasoconstrictive medications, unmet needs exist in patients at cardiovascular risk. Anti-CGRP acute migraine therapies, as well as “ditans” (5HT-1f antagonist) are under regulatory review and may address the needs of these patients. In the context of acute migraine therapy, diclofenac and NSAIDs are typically used instead of triptans, or with triptans when additional efficacy is needed. We certainly find that the use of diclofenac in these situations should be judicious, and reserved to those who clearly need it, have infrequent migraine attacks, and are otherwise healthy.

Diclofenac is also often used in the emergency department in many countries as a rescue therapy. In a series of clinical trials where we tested most commonly used drugs in this setting in Brazil, we found that efficacies were 83.6% for intravenous dipyrone, 66.7% for intramuscular diclofenac and 81.8% for intravenous chlorpromazine. We continue to believe that diclofenac is an important, non-sedative and non-opioid option for the management of headaches in the emergency department, assuming that at discharge, patients would receive proper guidance on the management of migraine without relying on frequent use of NSAIDs.

Jack Schim, MD
Co-Director, The Headache Center of Southern California

This article supports findings of prior epidemiologic studies correlating exposure to NSAIDs with increased cerebrovascular and cardiovascular risk. Prior studies have shown a dose-related response in risk associated with NSAID therapy, supporting a causal association. However, while relative risk is significantly higher in individuals with NSAID exposure, the absolute risk remains very low. The greater risk from NSAIDs continues to be to the kidneys, and to the stomach.  

As with all therapies, we need to weigh the advantages and disadvantages of NSAID therapy with our headache patients. All medications carry their own risks. For acute treatment of migraines, our primary tool, triptans, are contraindicated in a significant subset of individuals, including patients with ischemic coronary artery as well as those with history of stroke or transient ischemic attack (TIA). The alternatives, NSAIDs, dopamine blocking agents, have utility and risks.

Diclofenac powder to be dissolved in water is an effective abortive for migraine for many individuals. In general, our patients have intermittent exposure, preferably not more than 2 days per week. For the appropriate individual, NSAIDS, including diclofenac, remain an important tool in the acute care armamentarium.

Rob Cowan, MD, FAAN, FAHS
Higgins Professor of Neurology and Neurosciences
Chief, Division of Headache Medicine, Dept. of Neurology and Neurosciences
Director, Stanford University School of Medicine

These kinds of large, population-based studies must be interpreted with caution. While they may emulate the protocol of prospective studies, they lack proper inclusion/exclusion criteria, particularly with respect to indication. It may be reasonable to assume that the population of diclofenac users is "sicker" than the general population and the population that is using cheaper, more accessible NSAIDs or paracetamol. Without knowing the access and economic issues in Denmark, it is difficult to weigh these variables in the study. Thus, while it is certainly an important issue to explore (the relative risks and benefits of a given medication within a class), the absence of a well-designed, prospective study precludes any definitive conclusion regarding relative safety and risk profile for Diclofenac.

+++

These are great comments by my colleagues. My impression after seeing the data and reading my colleague’s comments, is that diclofenac may be riskier than other NSAIDs in this study; but when used properly in generally healthy migraineurs, it is probably more effective than dangerous when evaluating the risk/benefit ratio. When diclofenac is used as an oral solution (Cambia), 2 days per week or less, in a patient without serious gastrointestinal, renal, cardiac or hypertensive issues, it appears to pose little risk to the patient. When given to the wrong patient, or when taken too frequently, is could be dangerous. What I really like about this preparation is that it causes fewer adverse events compared to triptans and works very quickly. It can be used when triptans have been used enough that week or if they tend to cause significant adverse events when taken. We can use diclofenac for our headache patients, but we should remain vigilant to give it cautiously and only to patients who have no contraindication to its use.

Please write to us at Neurology Reviews Migraine Resource Center ([email protected]) with your opinions.

Alan M. Rapoport, M.D.
Editor-in-Chief
Migraine Resource Center

Clinical Professor of Neurology
The David Geffen School of Medicine at UCLA
Los Angeles, California

In July 2018, The BMJ published a study examining the cardiovascular risks of diclofenac initiation compared with initiation of other traditional non-steroidal anti-inflammatory drugs, initiation of paracetamol, and no initiation. The results showed a 50% increase in adverse events among diclofenac initiators compared with non-initiators (as well as a 20% increase over paracetamol/ibuprofen initiators, and 30% increase over naproxen initiators). (Read the full study here). Here, I asked several of my colleagues to weigh in on the results of this study and its implications for our practices, and then I share my own thoughts on these findings:

Marcelo Bigal, MD, PhD
Chief Medical Officer, Purdue Pharma

It is well established that NSAIDs are associated with increased risk of poor cardiovascular outcomes. This study offers powerful evidence that the risk after frequent diclofenac use is disproportionally increased relative to other commonly used NSAIDs, such as ibuprofen or naproxen. It is relevant to discuss the implications of the findings for the treatment of migraine.

The acute treatment of migraine associated with attack-related disability should favor triptans as first line therapy, not NSAIDs. Because triptans are vasoconstrictive medications, unmet needs exist in patients at cardiovascular risk. Anti-CGRP acute migraine therapies, as well as “ditans” (5HT-1f antagonist) are under regulatory review and may address the needs of these patients. In the context of acute migraine therapy, diclofenac and NSAIDs are typically used instead of triptans, or with triptans when additional efficacy is needed. We certainly find that the use of diclofenac in these situations should be judicious, and reserved to those who clearly need it, have infrequent migraine attacks, and are otherwise healthy.

Diclofenac is also often used in the emergency department in many countries as a rescue therapy. In a series of clinical trials where we tested most commonly used drugs in this setting in Brazil, we found that efficacies were 83.6% for intravenous dipyrone, 66.7% for intramuscular diclofenac and 81.8% for intravenous chlorpromazine. We continue to believe that diclofenac is an important, non-sedative and non-opioid option for the management of headaches in the emergency department, assuming that at discharge, patients would receive proper guidance on the management of migraine without relying on frequent use of NSAIDs.

Jack Schim, MD
Co-Director, The Headache Center of Southern California

This article supports findings of prior epidemiologic studies correlating exposure to NSAIDs with increased cerebrovascular and cardiovascular risk. Prior studies have shown a dose-related response in risk associated with NSAID therapy, supporting a causal association. However, while relative risk is significantly higher in individuals with NSAID exposure, the absolute risk remains very low. The greater risk from NSAIDs continues to be to the kidneys, and to the stomach.  

As with all therapies, we need to weigh the advantages and disadvantages of NSAID therapy with our headache patients. All medications carry their own risks. For acute treatment of migraines, our primary tool, triptans, are contraindicated in a significant subset of individuals, including patients with ischemic coronary artery as well as those with history of stroke or transient ischemic attack (TIA). The alternatives, NSAIDs, dopamine blocking agents, have utility and risks.

Diclofenac powder to be dissolved in water is an effective abortive for migraine for many individuals. In general, our patients have intermittent exposure, preferably not more than 2 days per week. For the appropriate individual, NSAIDS, including diclofenac, remain an important tool in the acute care armamentarium.

Rob Cowan, MD, FAAN, FAHS
Higgins Professor of Neurology and Neurosciences
Chief, Division of Headache Medicine, Dept. of Neurology and Neurosciences
Director, Stanford University School of Medicine

These kinds of large, population-based studies must be interpreted with caution. While they may emulate the protocol of prospective studies, they lack proper inclusion/exclusion criteria, particularly with respect to indication. It may be reasonable to assume that the population of diclofenac users is "sicker" than the general population and the population that is using cheaper, more accessible NSAIDs or paracetamol. Without knowing the access and economic issues in Denmark, it is difficult to weigh these variables in the study. Thus, while it is certainly an important issue to explore (the relative risks and benefits of a given medication within a class), the absence of a well-designed, prospective study precludes any definitive conclusion regarding relative safety and risk profile for Diclofenac.

+++

These are great comments by my colleagues. My impression after seeing the data and reading my colleague’s comments, is that diclofenac may be riskier than other NSAIDs in this study; but when used properly in generally healthy migraineurs, it is probably more effective than dangerous when evaluating the risk/benefit ratio. When diclofenac is used as an oral solution (Cambia), 2 days per week or less, in a patient without serious gastrointestinal, renal, cardiac or hypertensive issues, it appears to pose little risk to the patient. When given to the wrong patient, or when taken too frequently, is could be dangerous. What I really like about this preparation is that it causes fewer adverse events compared to triptans and works very quickly. It can be used when triptans have been used enough that week or if they tend to cause significant adverse events when taken. We can use diclofenac for our headache patients, but we should remain vigilant to give it cautiously and only to patients who have no contraindication to its use.

Please write to us at Neurology Reviews Migraine Resource Center ([email protected]) with your opinions.

Alan M. Rapoport, M.D.
Editor-in-Chief
Migraine Resource Center

Clinical Professor of Neurology
The David Geffen School of Medicine at UCLA
Los Angeles, California

BERLIN – Retinal thinning related to ganglion loss may be independent of optic neuritis attacks in patients with neuromyelitis optica spectrum disorders who have anti–aquaporin-4 antibodies.

Michele G. Sullivan/MDedge News

These eyes exhibited an annual retinal volume loss of about 0.6 micrometers – 80 times higher than that of normal controls – even though they did not have a history of optic neuritis (ON), Frederike C. Oertel said at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

“The most likely explanation for this seems to be a disease-related primary retinopathy due to the high density of astrocytic cells in the retina and the afferent visual system,” said Ms. Oertel, a doctoral student at NeuroCure Clinical Research Center, Berlin.

The study appeared in the Journal of Neurology, Neurosurgery & Psychiatry (J Neurol Neurosurg Psychiatry. 2018 Jun 19. doi: 10.1136/jnnp-2018-318382).

A previous cross-sectional study by her group found retinal thinning and an alteration of foveal shape in anti–aquaporin-4 (anti-AQP4) positive patients with neuromyelitis optica spectrum disorders (NMOSD) independent of whether they had experienced a clinical attack of optic neuritis (Neurol Neuroimmunol Neuroinflamm. 2017 May;4[3]:e334). In these patients, the fovea changed shape from a characteristic steeply angled “V” to a broader, flatter “U” shape, she said.

In that 2017 paper, Ms. Oertel and her colleagues theorized that the relationship between the water-channel regulator AQP4 and astrocytes could be the root cause of these microstructural alterations.

“The parafoveal area is characterized by a high density of retinal astrocytic Müller cells, which express AQP4 and may thus serve as retinal targets in NMOSD,” they wrote. “Müller cells regulate the retinal water balance and have a relevant role in neurotransmitter and photopigment recycling, as well as in energy and lipid metabolism. Müller cell dysfunction or degeneration could thus lead to impaired retinal function including changes in water homeostasis. Of interest, both the initial cohort and the confirmatory cohort showed a mild increase of peripapillary retinal nerve fiber layer thickness, which could indicate tissue swelling. These findings are supported by animal studies showing retraction of astrocytic end feet in some and astrocyte death in other cases, suggesting a primary astrocytoma in NMOSD also outside acute lesions.”

The study Ms. Oertel presented at ECTRIMS looked at full retinal thickness using the same imaging tool, optical coherence tomography (OCT). The longitudinal cohort comprised 94 eyes in 51 anti–AQP4-IgG seropositive patients who had NMOSD; 60 of these eyes had experienced an optic neuritis attack and 34 had not. Most of the patients were female; the mean age was 47 years. They were compared against 28 age- and sex-matched healthy controls.


OCT measured combined ganglion cell and inner plexiform layer (GCIP), the peripapillary retinal nerve fiber layer (pRNFL), fovea thickness (FT), inner nuclear layer (INL), and total macular volume (TMV).

At baseline, ON eyes already displayed reduced GCIP, FT, and TMV, compared with healthy controls – but so had eyes that had not had ON. Over the follow-up period, eyes without ON continued to show thinning, even in the absence of a clinical attack. Although visual acuity didn’t change over time, the retinas continued to thin, losing an average of 0.6 micrometers each year, a rate 80 times greater than that seen in the control group.

“We saw this significant loss of the ganglion cell layer volume independent of ON, suggesting that retinal neurodegeneration is not dependent on ON in these patients,” Ms. Oertel said.

The results fit well into the group’s prior theory of astrocytic involvement. However, she added, “We still have to think about an alternative theory of drug-induced neuroaxonal damage and retrograde neuroaxonal degeneration.”

The project was supported with grants from the German Ministry for Education and Research. Ms. Oertel had no financial disclosures relevant to the work, but many coauthors reported financial relationships with industry.

[email protected]

SOURCE: Oertel FC et al. ECTRIMS 2018, Abstract 212.

BERLIN – Retinal thinning related to ganglion loss may be independent of optic neuritis attacks in patients with neuromyelitis optica spectrum disorders who have anti–aquaporin-4 antibodies.

Michele G. Sullivan/MDedge News

These eyes exhibited an annual retinal volume loss of about 0.6 micrometers – 80 times higher than that of normal controls – even though they did not have a history of optic neuritis (ON), Frederike C. Oertel said at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

“The most likely explanation for this seems to be a disease-related primary retinopathy due to the high density of astrocytic cells in the retina and the afferent visual system,” said Ms. Oertel, a doctoral student at NeuroCure Clinical Research Center, Berlin.

The study appeared in the Journal of Neurology, Neurosurgery & Psychiatry (J Neurol Neurosurg Psychiatry. 2018 Jun 19. doi: 10.1136/jnnp-2018-318382).

A previous cross-sectional study by her group found retinal thinning and an alteration of foveal shape in anti–aquaporin-4 (anti-AQP4) positive patients with neuromyelitis optica spectrum disorders (NMOSD) independent of whether they had experienced a clinical attack of optic neuritis (Neurol Neuroimmunol Neuroinflamm. 2017 May;4[3]:e334). In these patients, the fovea changed shape from a characteristic steeply angled “V” to a broader, flatter “U” shape, she said.

In that 2017 paper, Ms. Oertel and her colleagues theorized that the relationship between the water-channel regulator AQP4 and astrocytes could be the root cause of these microstructural alterations.

“The parafoveal area is characterized by a high density of retinal astrocytic Müller cells, which express AQP4 and may thus serve as retinal targets in NMOSD,” they wrote. “Müller cells regulate the retinal water balance and have a relevant role in neurotransmitter and photopigment recycling, as well as in energy and lipid metabolism. Müller cell dysfunction or degeneration could thus lead to impaired retinal function including changes in water homeostasis. Of interest, both the initial cohort and the confirmatory cohort showed a mild increase of peripapillary retinal nerve fiber layer thickness, which could indicate tissue swelling. These findings are supported by animal studies showing retraction of astrocytic end feet in some and astrocyte death in other cases, suggesting a primary astrocytoma in NMOSD also outside acute lesions.”

The study Ms. Oertel presented at ECTRIMS looked at full retinal thickness using the same imaging tool, optical coherence tomography (OCT). The longitudinal cohort comprised 94 eyes in 51 anti–AQP4-IgG seropositive patients who had NMOSD; 60 of these eyes had experienced an optic neuritis attack and 34 had not. Most of the patients were female; the mean age was 47 years. They were compared against 28 age- and sex-matched healthy controls.


OCT measured combined ganglion cell and inner plexiform layer (GCIP), the peripapillary retinal nerve fiber layer (pRNFL), fovea thickness (FT), inner nuclear layer (INL), and total macular volume (TMV).

At baseline, ON eyes already displayed reduced GCIP, FT, and TMV, compared with healthy controls – but so had eyes that had not had ON. Over the follow-up period, eyes without ON continued to show thinning, even in the absence of a clinical attack. Although visual acuity didn’t change over time, the retinas continued to thin, losing an average of 0.6 micrometers each year, a rate 80 times greater than that seen in the control group.

“We saw this significant loss of the ganglion cell layer volume independent of ON, suggesting that retinal neurodegeneration is not dependent on ON in these patients,” Ms. Oertel said.

The results fit well into the group’s prior theory of astrocytic involvement. However, she added, “We still have to think about an alternative theory of drug-induced neuroaxonal damage and retrograde neuroaxonal degeneration.”

The project was supported with grants from the German Ministry for Education and Research. Ms. Oertel had no financial disclosures relevant to the work, but many coauthors reported financial relationships with industry.

[email protected]

SOURCE: Oertel FC et al. ECTRIMS 2018, Abstract 212.

BERLIN – Retinal thinning related to ganglion loss may be independent of optic neuritis attacks in patients with neuromyelitis optica spectrum disorders who have anti–aquaporin-4 antibodies.

Michele G. Sullivan/MDedge News

These eyes exhibited an annual retinal volume loss of about 0.6 micrometers – 80 times higher than that of normal controls – even though they did not have a history of optic neuritis (ON), Frederike C. Oertel said at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

“The most likely explanation for this seems to be a disease-related primary retinopathy due to the high density of astrocytic cells in the retina and the afferent visual system,” said Ms. Oertel, a doctoral student at NeuroCure Clinical Research Center, Berlin.

The study appeared in the Journal of Neurology, Neurosurgery & Psychiatry (J Neurol Neurosurg Psychiatry. 2018 Jun 19. doi: 10.1136/jnnp-2018-318382).

A previous cross-sectional study by her group found retinal thinning and an alteration of foveal shape in anti–aquaporin-4 (anti-AQP4) positive patients with neuromyelitis optica spectrum disorders (NMOSD) independent of whether they had experienced a clinical attack of optic neuritis (Neurol Neuroimmunol Neuroinflamm. 2017 May;4[3]:e334). In these patients, the fovea changed shape from a characteristic steeply angled “V” to a broader, flatter “U” shape, she said.

In that 2017 paper, Ms. Oertel and her colleagues theorized that the relationship between the water-channel regulator AQP4 and astrocytes could be the root cause of these microstructural alterations.

“The parafoveal area is characterized by a high density of retinal astrocytic Müller cells, which express AQP4 and may thus serve as retinal targets in NMOSD,” they wrote. “Müller cells regulate the retinal water balance and have a relevant role in neurotransmitter and photopigment recycling, as well as in energy and lipid metabolism. Müller cell dysfunction or degeneration could thus lead to impaired retinal function including changes in water homeostasis. Of interest, both the initial cohort and the confirmatory cohort showed a mild increase of peripapillary retinal nerve fiber layer thickness, which could indicate tissue swelling. These findings are supported by animal studies showing retraction of astrocytic end feet in some and astrocyte death in other cases, suggesting a primary astrocytoma in NMOSD also outside acute lesions.”

The study Ms. Oertel presented at ECTRIMS looked at full retinal thickness using the same imaging tool, optical coherence tomography (OCT). The longitudinal cohort comprised 94 eyes in 51 anti–AQP4-IgG seropositive patients who had NMOSD; 60 of these eyes had experienced an optic neuritis attack and 34 had not. Most of the patients were female; the mean age was 47 years. They were compared against 28 age- and sex-matched healthy controls.


OCT measured combined ganglion cell and inner plexiform layer (GCIP), the peripapillary retinal nerve fiber layer (pRNFL), fovea thickness (FT), inner nuclear layer (INL), and total macular volume (TMV).

At baseline, ON eyes already displayed reduced GCIP, FT, and TMV, compared with healthy controls – but so had eyes that had not had ON. Over the follow-up period, eyes without ON continued to show thinning, even in the absence of a clinical attack. Although visual acuity didn’t change over time, the retinas continued to thin, losing an average of 0.6 micrometers each year, a rate 80 times greater than that seen in the control group.

“We saw this significant loss of the ganglion cell layer volume independent of ON, suggesting that retinal neurodegeneration is not dependent on ON in these patients,” Ms. Oertel said.

The results fit well into the group’s prior theory of astrocytic involvement. However, she added, “We still have to think about an alternative theory of drug-induced neuroaxonal damage and retrograde neuroaxonal degeneration.”

The project was supported with grants from the German Ministry for Education and Research. Ms. Oertel had no financial disclosures relevant to the work, but many coauthors reported financial relationships with industry.

[email protected]

SOURCE: Oertel FC et al. ECTRIMS 2018, Abstract 212.

In contrast to other recent studies, androgen deprivation therapy (ADT) had no link to dementia in a observational cohort study of more than 45,000 men with prostate cancer who received definitive radiotherapy, investigators have reported.

No significant associations were found between ADT and Alzheimer’s disease or vascular dementia, or between shorter or longer courses of ADT and any dementia studied, according to Rishi Deka, PhD, of Veterans Affairs San Diego Health Care System, La Jolla, Calif., and coinvestigators.

“These results may mitigate concerns regarding the long-term risks of ADT on cognitive health in the treatment of prostate cancer,” Dr. Deka and colleagues wrote in JAMA Oncology.

Two other recent studies showed strong, statistically significant associations between ADT and dementia in prostate cancer. However, those studies combined patients with local and metastatic disease, receiving ADT in the upfront or recurrent settings, while the present study looked specifically at men with nonmetastatic prostate cancer who received radiotherapy.

“Different treatment modalities and disease stages are associated with substantial selection bias that may predispose results to false associations,” noted Dr. Deka and coauthors.

Their observational cohort study comprised 45,218 men diagnosed with nonmetastatic prostate cancer at the U.S. Department of Veterans Affairs who underwent radiotherapy with or without ADT. The investigators excluded men who had a diagnosis of dementia within 1 year of the prostate cancer diagnosis or who had prior diagnoses of dementia, stroke, or cognitive impairment.

A total of 1,497 patients were diagnosed with dementia over a median of 6.8 years of follow-up: 404 with Alzheimer disease, 335 with vascular dementia, and 758 with other types or unclassified dementias.

The investigators found no significant association between use of ADT and development of any dementia, the primary outcome of the analysis (subdistribution hazard ratio [SHR], 1.04; 95% confidence interval, 0.94-1.16; P = .43).

Likewise, there was no association between ADT and vascular dementia, specifically, with an SHR of 1.20 (95% CI, 0.97-1.50; P = .10) or Alzheimer’s disease, with an SHR of 1.11 (95% CI, 0.91-1.36; P = .29).

Duration of ADT longer than 1 year was not significantly associated with dementia, nor was duration shorter than 1 year, with SHRs, of 1.08 and 1.01 respectively, the analysis shows.

The SHRs in these and other analysis reported ranged from 1.00 to 1.21. That is substantially lower than hazard ratios of 1.66 to 2.32 in one previous study linking ADT to dementia, according to the investigators, suggesting that the results of the current analysis were not due to inadequate power to detect differences.

Nevertheless, the findings may not be generalizable to some other populations, they cautioned, since it was focused demographically on veterans, and was limited to radiotherapy-treated patients.

Dr. Deka and coauthors reported no conflict of interest. Their study was funded by grants from the University of California San Diego Center for Precision Radiation Medicine.

SOURCE: Deka R et al. JAMA Oncol. 2018 Oct 11. doi: 10.1001/jamaoncol.2018.4423.

In contrast to other recent studies, androgen deprivation therapy (ADT) had no link to dementia in a observational cohort study of more than 45,000 men with prostate cancer who received definitive radiotherapy, investigators have reported.

No significant associations were found between ADT and Alzheimer’s disease or vascular dementia, or between shorter or longer courses of ADT and any dementia studied, according to Rishi Deka, PhD, of Veterans Affairs San Diego Health Care System, La Jolla, Calif., and coinvestigators.

“These results may mitigate concerns regarding the long-term risks of ADT on cognitive health in the treatment of prostate cancer,” Dr. Deka and colleagues wrote in JAMA Oncology.

Two other recent studies showed strong, statistically significant associations between ADT and dementia in prostate cancer. However, those studies combined patients with local and metastatic disease, receiving ADT in the upfront or recurrent settings, while the present study looked specifically at men with nonmetastatic prostate cancer who received radiotherapy.

“Different treatment modalities and disease stages are associated with substantial selection bias that may predispose results to false associations,” noted Dr. Deka and coauthors.

Their observational cohort study comprised 45,218 men diagnosed with nonmetastatic prostate cancer at the U.S. Department of Veterans Affairs who underwent radiotherapy with or without ADT. The investigators excluded men who had a diagnosis of dementia within 1 year of the prostate cancer diagnosis or who had prior diagnoses of dementia, stroke, or cognitive impairment.

A total of 1,497 patients were diagnosed with dementia over a median of 6.8 years of follow-up: 404 with Alzheimer disease, 335 with vascular dementia, and 758 with other types or unclassified dementias.

The investigators found no significant association between use of ADT and development of any dementia, the primary outcome of the analysis (subdistribution hazard ratio [SHR], 1.04; 95% confidence interval, 0.94-1.16; P = .43).

Likewise, there was no association between ADT and vascular dementia, specifically, with an SHR of 1.20 (95% CI, 0.97-1.50; P = .10) or Alzheimer’s disease, with an SHR of 1.11 (95% CI, 0.91-1.36; P = .29).

Duration of ADT longer than 1 year was not significantly associated with dementia, nor was duration shorter than 1 year, with SHRs, of 1.08 and 1.01 respectively, the analysis shows.

The SHRs in these and other analysis reported ranged from 1.00 to 1.21. That is substantially lower than hazard ratios of 1.66 to 2.32 in one previous study linking ADT to dementia, according to the investigators, suggesting that the results of the current analysis were not due to inadequate power to detect differences.

Nevertheless, the findings may not be generalizable to some other populations, they cautioned, since it was focused demographically on veterans, and was limited to radiotherapy-treated patients.

Dr. Deka and coauthors reported no conflict of interest. Their study was funded by grants from the University of California San Diego Center for Precision Radiation Medicine.

SOURCE: Deka R et al. JAMA Oncol. 2018 Oct 11. doi: 10.1001/jamaoncol.2018.4423.

In contrast to other recent studies, androgen deprivation therapy (ADT) had no link to dementia in a observational cohort study of more than 45,000 men with prostate cancer who received definitive radiotherapy, investigators have reported.

No significant associations were found between ADT and Alzheimer’s disease or vascular dementia, or between shorter or longer courses of ADT and any dementia studied, according to Rishi Deka, PhD, of Veterans Affairs San Diego Health Care System, La Jolla, Calif., and coinvestigators.

“These results may mitigate concerns regarding the long-term risks of ADT on cognitive health in the treatment of prostate cancer,” Dr. Deka and colleagues wrote in JAMA Oncology.

Two other recent studies showed strong, statistically significant associations between ADT and dementia in prostate cancer. However, those studies combined patients with local and metastatic disease, receiving ADT in the upfront or recurrent settings, while the present study looked specifically at men with nonmetastatic prostate cancer who received radiotherapy.

“Different treatment modalities and disease stages are associated with substantial selection bias that may predispose results to false associations,” noted Dr. Deka and coauthors.

Their observational cohort study comprised 45,218 men diagnosed with nonmetastatic prostate cancer at the U.S. Department of Veterans Affairs who underwent radiotherapy with or without ADT. The investigators excluded men who had a diagnosis of dementia within 1 year of the prostate cancer diagnosis or who had prior diagnoses of dementia, stroke, or cognitive impairment.

A total of 1,497 patients were diagnosed with dementia over a median of 6.8 years of follow-up: 404 with Alzheimer disease, 335 with vascular dementia, and 758 with other types or unclassified dementias.

The investigators found no significant association between use of ADT and development of any dementia, the primary outcome of the analysis (subdistribution hazard ratio [SHR], 1.04; 95% confidence interval, 0.94-1.16; P = .43).

Likewise, there was no association between ADT and vascular dementia, specifically, with an SHR of 1.20 (95% CI, 0.97-1.50; P = .10) or Alzheimer’s disease, with an SHR of 1.11 (95% CI, 0.91-1.36; P = .29).

Duration of ADT longer than 1 year was not significantly associated with dementia, nor was duration shorter than 1 year, with SHRs, of 1.08 and 1.01 respectively, the analysis shows.

The SHRs in these and other analysis reported ranged from 1.00 to 1.21. That is substantially lower than hazard ratios of 1.66 to 2.32 in one previous study linking ADT to dementia, according to the investigators, suggesting that the results of the current analysis were not due to inadequate power to detect differences.

Nevertheless, the findings may not be generalizable to some other populations, they cautioned, since it was focused demographically on veterans, and was limited to radiotherapy-treated patients.

Dr. Deka and coauthors reported no conflict of interest. Their study was funded by grants from the University of California San Diego Center for Precision Radiation Medicine.

SOURCE: Deka R et al. JAMA Oncol. 2018 Oct 11. doi: 10.1001/jamaoncol.2018.4423.

Checkpoint inhibitors are so new that not enough patients have received them to allow clinicians to predict who will benefit most. But researchers from the National Cancer Institute, Center for Cancer Institute; Harvard University in Cambridge, Massachusetts; University of Pennsylvania in Philadelphia; and University of Maryland in College Park may have found a clue: A gene expression predictor.

They began by looking at neuroblastoma cases where the immune system seemed to mount “an unprompted, successful immune response” to cancer, causing spontaneous tumor regression. The researchers were able to define gene expression features that separated regressing from nonregressing disease.

The researchers then computed Immuno-PREdictive Scores (IMPRES) for each patient sample. The higher the score, the more likely was spontaneous regression. Analyzing 297 samples from several studies, they found the predictor identified nearly all patients who responded to the inhibitors and more than half of those who did not. “Importantly,” the researchers say, their predictor was accurate across many different melanoma patient datasets.

Checkpoint inhibitors are so new that not enough patients have received them to allow clinicians to predict who will benefit most. But researchers from the National Cancer Institute, Center for Cancer Institute; Harvard University in Cambridge, Massachusetts; University of Pennsylvania in Philadelphia; and University of Maryland in College Park may have found a clue: A gene expression predictor.

They began by looking at neuroblastoma cases where the immune system seemed to mount “an unprompted, successful immune response” to cancer, causing spontaneous tumor regression. The researchers were able to define gene expression features that separated regressing from nonregressing disease.

The researchers then computed Immuno-PREdictive Scores (IMPRES) for each patient sample. The higher the score, the more likely was spontaneous regression. Analyzing 297 samples from several studies, they found the predictor identified nearly all patients who responded to the inhibitors and more than half of those who did not. “Importantly,” the researchers say, their predictor was accurate across many different melanoma patient datasets.

Checkpoint inhibitors are so new that not enough patients have received them to allow clinicians to predict who will benefit most. But researchers from the National Cancer Institute, Center for Cancer Institute; Harvard University in Cambridge, Massachusetts; University of Pennsylvania in Philadelphia; and University of Maryland in College Park may have found a clue: A gene expression predictor.

They began by looking at neuroblastoma cases where the immune system seemed to mount “an unprompted, successful immune response” to cancer, causing spontaneous tumor regression. The researchers were able to define gene expression features that separated regressing from nonregressing disease.

The researchers then computed Immuno-PREdictive Scores (IMPRES) for each patient sample. The higher the score, the more likely was spontaneous regression. Analyzing 297 samples from several studies, they found the predictor identified nearly all patients who responded to the inhibitors and more than half of those who did not. “Importantly,” the researchers say, their predictor was accurate across many different melanoma patient datasets.

BERLIN – Neurofilament light chain (Nf-L) levels are higher in the plasma of patients with secondary progressive multiple sclerosis (SPMS) than primary progressive multiple sclerosis (PPMS) irrespective of age, according to an analysis of blood samples from two large phase 3 trials.

Sara Freeman/MDedge News

SOURCE: Kuhle J et al. ECTRIMS 2018. Mult Scler. 2018;24(Suppl 2):111, Abstract 286.

BERLIN – Neurofilament light chain (Nf-L) levels are higher in the plasma of patients with secondary progressive multiple sclerosis (SPMS) than primary progressive multiple sclerosis (PPMS) irrespective of age, according to an analysis of blood samples from two large phase 3 trials.

Sara Freeman/MDedge News

SOURCE: Kuhle J et al. ECTRIMS 2018. Mult Scler. 2018;24(Suppl 2):111, Abstract 286.

BERLIN – Neurofilament light chain (Nf-L) levels are higher in the plasma of patients with secondary progressive multiple sclerosis (SPMS) than primary progressive multiple sclerosis (PPMS) irrespective of age, according to an analysis of blood samples from two large phase 3 trials.

Sara Freeman/MDedge News

SOURCE: Kuhle J et al. ECTRIMS 2018. Mult Scler. 2018;24(Suppl 2):111, Abstract 286.

BERLIN – Spinal cord volume deficits in patients with multiple sclerosis may contribute to clinical disability that appears out of proportion to lesion load on brain imaging, according to new research.

Kari Oakes/MDedge News

In a pool of 362 patients with mild to moderate MS-related disability but identical white matter lesion load identified by MRI, those with higher disability had significantly lower spinal cord volumes when compared against those with disability scores in the mild range (P less than .001).

Though brain MRI is a key tool used to track disease severity and progression in MS, some patients have relatively high disability but a low burden of white matter intracerebral lesions on MRI. Little is known about spinal cord volume in MS patients with pronounced dissociation between intracerebral lesion load and disability, Michaela Andelova, MD, said in an interview during a poster session at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

Dr. Andelova, of Charles University, Prague, said that she and her colleagues hypothesized that spinal cord volume would differ between patients who had varying levels of disability, despite identical white matter lesion load.

To test this, she and her colleagues looked at records of 1,245 patients with relapsing-remitting MS. They divided them into three groups by severity of clinical disability, and also by extent of cerebral T2 hyperintense lesion load. The investigators identified a group of patients (n = 53) whose total volume of T2-weighted hyperintense lesions was less than 3 mL, but whose Expanded Disability Status Scale (EDSS) scores were at least 3.5; this was the low lesion load/high disability (LLHD) group.

Dr. Andelova and her colleagues then identified another group of patients (n = 71) who had a volume of T2-weighted hyperintensities that was greater than 9 mL, but whose EDSS score was less than 1.5. This was the high lesion load/low disability (HLLD) group.

The remaining patients (n = 1,121), who did not have these paradoxical associations, were analyzed separately.

For all patients, mean upper cervical cord area (MUCCA) was also measured. Using images acquired by a 3 T MRI scanner, MUCCA was calculated as the mean sum of spinal cord area in 21 slices centered at the C3/4 intervertebral disk, using an in-house, semiautomated method.

“Despite higher disability, LLHD patients demonstrated significantly higher normalized total brain volume, higher normalized volumes of thalamus and callosum, and smaller lateral ventricles than [the] HLLD group,” wrote Dr. Andelova and her collaborators.

However, the LLHD patients had MUCCA values that were significantly lower than the other groups: The nonparadoxical group’s mean MUCCA was 84.02 mm², while the HLLD group had a mean MUCCA of 85.75 mm². This difference was not statistically significant. By contrast, the LLHD group’s mean MUCCA was significantly smaller, at 80.40 mm² (P = .023 versus nonparadoxical patients, and P = .007 versus HLLD patients).

Looking at the data another way, Dr. Andelova and her colleagues compared 362 evenly divided patients with moderate disability (EDSS 3.5-6.5) with matched patients who had mild MS-related disability (EDSS less than 3) and identical cerebral lesion loads. They found that MUCCA was significantly smaller in the moderate disability group (78.86 versus 84.44 mm²; P less than .001).

In addition to having identical lesions loads, the mild and moderate disability groups didn’t differ significantly in normalized total brain volume or regional brain volumes. The group with moderate disability did have slightly less white matter volume (P = .039), Dr. Andelova pointed out.

All differences found between groups retained statistical significance even after adjustment for such potential confounders as age, sex, and duration of disease, Dr. Andelova said.

“Reduced spinal cord volume may explain part of the clinical-radiological paradox in patients who have high disability despite low intracranial lesion load,” Dr. Andelova and her collaborators wrote. “In line with this finding, relatively preserved spinal cord volume may be associated with functional reserve and less physical disability in patients with low disability despite high cerebral lesion load.”

Further work looking more precisely at cerebral lesion distribution and quantitative MRI investigation of lesion distribution is in the works for Dr. Andelova and her collaborators. They are hoping to see some association between various distribution patterns and accelerated spinal atrophy.

The research was supported by the Czech government. Dr. Andelova and several of her collaborators reported financial relationships with pharmaceutical companies.

[email protected]

SOURCE: Andelova M et al. Mult Scler. 2018;24(Suppl 2):211, Abstract P477.

BERLIN – Spinal cord volume deficits in patients with multiple sclerosis may contribute to clinical disability that appears out of proportion to lesion load on brain imaging, according to new research.

Kari Oakes/MDedge News

In a pool of 362 patients with mild to moderate MS-related disability but identical white matter lesion load identified by MRI, those with higher disability had significantly lower spinal cord volumes when compared against those with disability scores in the mild range (P less than .001).

Though brain MRI is a key tool used to track disease severity and progression in MS, some patients have relatively high disability but a low burden of white matter intracerebral lesions on MRI. Little is known about spinal cord volume in MS patients with pronounced dissociation between intracerebral lesion load and disability, Michaela Andelova, MD, said in an interview during a poster session at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

Dr. Andelova, of Charles University, Prague, said that she and her colleagues hypothesized that spinal cord volume would differ between patients who had varying levels of disability, despite identical white matter lesion load.

To test this, she and her colleagues looked at records of 1,245 patients with relapsing-remitting MS. They divided them into three groups by severity of clinical disability, and also by extent of cerebral T2 hyperintense lesion load. The investigators identified a group of patients (n = 53) whose total volume of T2-weighted hyperintense lesions was less than 3 mL, but whose Expanded Disability Status Scale (EDSS) scores were at least 3.5; this was the low lesion load/high disability (LLHD) group.

Dr. Andelova and her colleagues then identified another group of patients (n = 71) who had a volume of T2-weighted hyperintensities that was greater than 9 mL, but whose EDSS score was less than 1.5. This was the high lesion load/low disability (HLLD) group.

The remaining patients (n = 1,121), who did not have these paradoxical associations, were analyzed separately.

For all patients, mean upper cervical cord area (MUCCA) was also measured. Using images acquired by a 3 T MRI scanner, MUCCA was calculated as the mean sum of spinal cord area in 21 slices centered at the C3/4 intervertebral disk, using an in-house, semiautomated method.

“Despite higher disability, LLHD patients demonstrated significantly higher normalized total brain volume, higher normalized volumes of thalamus and callosum, and smaller lateral ventricles than [the] HLLD group,” wrote Dr. Andelova and her collaborators.

However, the LLHD patients had MUCCA values that were significantly lower than the other groups: The nonparadoxical group’s mean MUCCA was 84.02 mm², while the HLLD group had a mean MUCCA of 85.75 mm². This difference was not statistically significant. By contrast, the LLHD group’s mean MUCCA was significantly smaller, at 80.40 mm² (P = .023 versus nonparadoxical patients, and P = .007 versus HLLD patients).

Looking at the data another way, Dr. Andelova and her colleagues compared 362 evenly divided patients with moderate disability (EDSS 3.5-6.5) with matched patients who had mild MS-related disability (EDSS less than 3) and identical cerebral lesion loads. They found that MUCCA was significantly smaller in the moderate disability group (78.86 versus 84.44 mm²; P less than .001).

In addition to having identical lesions loads, the mild and moderate disability groups didn’t differ significantly in normalized total brain volume or regional brain volumes. The group with moderate disability did have slightly less white matter volume (P = .039), Dr. Andelova pointed out.

All differences found between groups retained statistical significance even after adjustment for such potential confounders as age, sex, and duration of disease, Dr. Andelova said.

“Reduced spinal cord volume may explain part of the clinical-radiological paradox in patients who have high disability despite low intracranial lesion load,” Dr. Andelova and her collaborators wrote. “In line with this finding, relatively preserved spinal cord volume may be associated with functional reserve and less physical disability in patients with low disability despite high cerebral lesion load.”

Further work looking more precisely at cerebral lesion distribution and quantitative MRI investigation of lesion distribution is in the works for Dr. Andelova and her collaborators. They are hoping to see some association between various distribution patterns and accelerated spinal atrophy.

The research was supported by the Czech government. Dr. Andelova and several of her collaborators reported financial relationships with pharmaceutical companies.

[email protected]

SOURCE: Andelova M et al. Mult Scler. 2018;24(Suppl 2):211, Abstract P477.

BERLIN – Spinal cord volume deficits in patients with multiple sclerosis may contribute to clinical disability that appears out of proportion to lesion load on brain imaging, according to new research.

Kari Oakes/MDedge News

In a pool of 362 patients with mild to moderate MS-related disability but identical white matter lesion load identified by MRI, those with higher disability had significantly lower spinal cord volumes when compared against those with disability scores in the mild range (P less than .001).

Though brain MRI is a key tool used to track disease severity and progression in MS, some patients have relatively high disability but a low burden of white matter intracerebral lesions on MRI. Little is known about spinal cord volume in MS patients with pronounced dissociation between intracerebral lesion load and disability, Michaela Andelova, MD, said in an interview during a poster session at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

Dr. Andelova, of Charles University, Prague, said that she and her colleagues hypothesized that spinal cord volume would differ between patients who had varying levels of disability, despite identical white matter lesion load.

To test this, she and her colleagues looked at records of 1,245 patients with relapsing-remitting MS. They divided them into three groups by severity of clinical disability, and also by extent of cerebral T2 hyperintense lesion load. The investigators identified a group of patients (n = 53) whose total volume of T2-weighted hyperintense lesions was less than 3 mL, but whose Expanded Disability Status Scale (EDSS) scores were at least 3.5; this was the low lesion load/high disability (LLHD) group.

Dr. Andelova and her colleagues then identified another group of patients (n = 71) who had a volume of T2-weighted hyperintensities that was greater than 9 mL, but whose EDSS score was less than 1.5. This was the high lesion load/low disability (HLLD) group.

The remaining patients (n = 1,121), who did not have these paradoxical associations, were analyzed separately.

For all patients, mean upper cervical cord area (MUCCA) was also measured. Using images acquired by a 3 T MRI scanner, MUCCA was calculated as the mean sum of spinal cord area in 21 slices centered at the C3/4 intervertebral disk, using an in-house, semiautomated method.

“Despite higher disability, LLHD patients demonstrated significantly higher normalized total brain volume, higher normalized volumes of thalamus and callosum, and smaller lateral ventricles than [the] HLLD group,” wrote Dr. Andelova and her collaborators.

However, the LLHD patients had MUCCA values that were significantly lower than the other groups: The nonparadoxical group’s mean MUCCA was 84.02 mm², while the HLLD group had a mean MUCCA of 85.75 mm². This difference was not statistically significant. By contrast, the LLHD group’s mean MUCCA was significantly smaller, at 80.40 mm² (P = .023 versus nonparadoxical patients, and P = .007 versus HLLD patients).

Looking at the data another way, Dr. Andelova and her colleagues compared 362 evenly divided patients with moderate disability (EDSS 3.5-6.5) with matched patients who had mild MS-related disability (EDSS less than 3) and identical cerebral lesion loads. They found that MUCCA was significantly smaller in the moderate disability group (78.86 versus 84.44 mm²; P less than .001).

In addition to having identical lesions loads, the mild and moderate disability groups didn’t differ significantly in normalized total brain volume or regional brain volumes. The group with moderate disability did have slightly less white matter volume (P = .039), Dr. Andelova pointed out.

All differences found between groups retained statistical significance even after adjustment for such potential confounders as age, sex, and duration of disease, Dr. Andelova said.

“Reduced spinal cord volume may explain part of the clinical-radiological paradox in patients who have high disability despite low intracranial lesion load,” Dr. Andelova and her collaborators wrote. “In line with this finding, relatively preserved spinal cord volume may be associated with functional reserve and less physical disability in patients with low disability despite high cerebral lesion load.”

Further work looking more precisely at cerebral lesion distribution and quantitative MRI investigation of lesion distribution is in the works for Dr. Andelova and her collaborators. They are hoping to see some association between various distribution patterns and accelerated spinal atrophy.

The research was supported by the Czech government. Dr. Andelova and several of her collaborators reported financial relationships with pharmaceutical companies.

[email protected]

SOURCE: Andelova M et al. Mult Scler. 2018;24(Suppl 2):211, Abstract P477.