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NASHVILLE—Multiple sclerosis (MS) traditionally has been considered a chronic inflammatory autoimmune disease, but inflammation decreases as the disease progresses. Many other biologic processes are dysregulated in MS, such as myelin signal transport, mitochondrial function, and iron metabolism. Lipid metabolism affects all of these processes, including inflammation, and thus could be a valuable therapeutic target, according to research presented at the 2018 CMSC Annual Meeting. 
“MS is not an inflammatory disease,” said John D. Nieland, PhD, Associate Professor of Health Science and Technology at Aalborg University in Denmark. “The inflammatory response is important, but it is not the only component. If you do not focus on the other components, you will never be able to treat the disease.”
The Role of Lipids in the CNS
Healthy brains have a high amount of glucose metabolism, but glucose metabolism is reduced in MS and other neurologic disorders such as Parkinson’s disease and Alzheimer’s disease. “If glucose metabolism is downregulated, something else has to be taking over,” said Dr. Nieland. He and his colleagues hypothesize that lipid metabolism replaces glucose metabolism in MS. They further hypothesize that MS fundamentally is a dysfunction of lipid metabolism.
Lipids have an essential role in the CNS. Proper signal transduction requires lipids to be bound to the myelin sheath. The proteins that compose myelin sheaths are highly immunogenic, and lipids shield them from exposure to the immune system. The half-life of lipids attached to the myelin sheath is three days, so these lipids must be replaced constantly. In addition, lipids are essential for the function of glutamate, cannabinoid, and insulin receptors.
An increase in lipid metabolism decreases glucose metabolism and induces the production of prostaglandin E2, which is a key molecule in the inflammatory response. In the early stages of MS, inflammation attacks the myelin sheath and other brain proteins. Increased lipid metabolism decreases lipid concentrations in the CNS, including around myelin. When lipids are removed from the myelin sheath, they expose the immunogenic proteins that compose it, thus provoking an immune response. Dysregulated lipid metabolism also contributes to oxidative stress, mitochondrial dysfunction, demyelination, and neuronal loss.
Chemical Inhibition of Lipid Metabolism
Dr. Nieland and colleagues hypothesized that blocking lipid metabolism would reverse the inflammatory response and other harmful processes that occur in MS. Previous research by Shriver and colleagues indicated that inhibition of carnitine palmitoyltransferase 1 (CPT1), a molecule essential to lipid metabolism, in encephalitogenic T cells increases apoptosis and reduces the production of inflammatory cytokines. Two of the molecule’s three isoforms, CPT1A and CPT1C, are upregulated in MS. Stress prompts an increase in CPT1 expression, which spurs a shift to lipid metabolism. “If you block CPT1, you jam lipid metabolism,” Dr. Nieland said. “There is no way around it.” Dr. Nieland’s group thus chose CPT1 as its target.
The investigators first conducted studies using etomoxir, which inhibits CPT1 and blocks long-chain fatty acids from entering the mitochondria for beta oxidation. Through these effects, etomoxir causes cells to shift to glucose metabolism.
The researchers immunized 42 mice with myelin oligodendrocyte glycoprotein (MOG35–55) to induce experimental autoimmune encephalopathy (EAE). When the animals first exhibited symptoms at Day 10, they were randomized to receive subcutaneous etomoxir or placebo daily. Disease score decreased significantly in the treated animals, compared with the control animals. On Day 24, more than 50% of the treated mice exhibited normal behavior, compared with approximately 20% of control mice.
In another study, the investigators immunized 47 rats with myelin basic protein to induce EAE. The animals began having symptoms at Day 7, and the investigators randomized them to daily treatment with subcutaneous etomoxir or placebo. At Day 11, disease score was significantly lower among treated animals, compared with control animals. Body weight was significantly higher among rats that received etomoxir, compared with controls, at that time point. Also, 25% of treated animals exhibited normal behavior, but no controls did.
In a third study, the investigators compared etomoxir, interferon beta, and placebo in a rat model of EAE. Each treatment group included 10 rats, and etomoxir had superior effects on disease score and body weight, compared with interferon beta and placebo. When the investigators examined the rats’ serum, they found that levels of antibodies against brain antigens common in EAE were lower in rats treated with etomoxir, compared with those treated with interferon beta or placebo.
Biologic Inhibition of Lipid Metabolism
In addition to pharmacologic treatment, genetic mutations affect CPT1 function. The Hutterites, an ethnoreligious group in Canada, have a mutation in CPT1A that almost completely blocks the molecule’s activity. Similarly, the Inuit have a mutation in CPT1A that reduces its activity to approximately 22%. The prevalence of MS is one in 1,100 among the Hutterites and one in 50,000 among the Inuit, compared with one in 350 in the Canadian population. These observations suggest that gene therapy could be another way to block CPT1.
Dr. Nieland’s group collaborated with the Netherlands Cancer Institute to develop mouse strains with two distinct mutations in CPT1A. The first mutation mimics that found among the Hutterites, and the other mimics that found among the Inuit. In a preliminary study, the investigators induced EAE in three wild-type mice and two mice with the CPT1A mutation similar to that of the Inuit. The mice were 10 weeks old at the time of immunization.
At 24 days, disease score was lower in the CPT1A mutant mice, compared with the wild-type mice. Furthermore, body weight was higher in the mutant mice, compared with the wild-type mice. The investigators also measured the mice’s grip strength at Day 2 and Day 24. Grip strength decreased in the wild-type mice but remained the same in the mutant mice. At Day 24, grip strength was significantly higher among mutant mice than among wild-type mice.
“These results indicate an interaction of the lipid metabolism in the brain and in the immune system, which supports our hypothesis regarding MS pathology,” said Anne Skøttrup Mørkholt, a doctoral student at Aalborg University, who collaborated with Dr. Nieland on these animal studies. “MS is not a disease of the immune system, but a systemic disease with dysregulation of multiple components.” 
Lipid Metabolism in Other Neurologic Diseases
Data suggest that lipid metabolism may contribute to other neurologic diseases such as amyotrophic lateral sclerosis (ALS) as well. Huang et al found a correlation between serum triglyceride levels and the development of ALS. Dupuis et al observed upregulated lipid metabolism and downregulated glucose metabolism in SOD1 mouse models of the disease, as did subsequent researchers. In addition, a 2015 study by Palamiuc et al found that CPT1B was significantly increased in the muscle tissue of SOD1 mice.
To investigate whether suppressing lipid metabolism affected ALS, Dr. Nieland’s group examined a SOD1 mouse model of the disease. The mice developed symptoms at Day 70 and were randomized at Day 100 to etomoxir or placebo. Etomoxir was associated with less weight loss and better neurologic score, compared with placebo. Etomoxir also was associated with better performance on the wire hanging and rotarod tests, compared with placebo. “It seems like etomoxir was able to slow down the disease progression,” said Michael Sloth Trabjerg, MD, a doctoral student at Aalborg University. 
Because research has found increased beta oxidation and decreased glucose metabolism in Parkinson’s disease, Dr. Nieland’s group studied the effect of CPT1 inhibition in a rotenone mouse model of the disease. They induced the disease in the mice for 32 days before randomizing them to placebo or etomoxir. For all mice, treatment alternated between rotenone on one day and placebo or etomoxir on the next day. The investigators observed significantly better sensorimotor performance among treated mice, compared with controls, on Day 47 and Day 56. At Day 60, mice who received etomoxir had significantly more muscle strength and longer latency to fall on the rotarod test, compared with mice that received placebo. These data are being prepared for publication.
The data suggest that dysregulated glucose metabolism and increased lipid metabolism play a role in ALS and Parkinson’s disease. “CPT1 seems to be a prominent target for moderating these diseases,” said Dr. Trabjerg.
—Erik Greb
Suggested Reading
Dodge JC, Treleaven CM, Fidler JA, et al. Metabolic signatures of amyotrophic lateral sclerosis reveal insights into disease pathogenesis. Proc Natl Acad Sci U S A. 2013;110(26):10812-10817.
Dupuis L, Oudart H, René F, et al. Evidence for defective energy homeostasis in amyotrophic lateral sclerosis: benefit of a high-energy diet in a transgenic mouse model. Proc Natl Acad Sci U S A. 2004;101(30):11159-11164.
Huang R, Guo X, Chen X, et al. The serum lipid profiles of amyotrophic lateral sclerosis patients: A study from south-west China and a meta-analysis. Amyotroph Lateral Scler Frontotemporal Degener. 2015;16(5-6):359-365.
Kim SM, Kim H, Kim JE, et al. Amyotrophic lateral sclerosis is associated with hypolipidemia at the presymptomatic stage in mice. PLoS One. 2011;6(3):e17985.
Lieury A, Chanal M, Androdias G, et al. Tissue remodeling in periplaque regions of multiple sclerosis spinal cord lesions. Glia. 2014;62(10):1645-1658.
Mørkholt AS, Kastaniegaard K, Trabjerg MS, et al. Identification of brain antigens recognized by autoantibodies in experimental autoimmune encephalomyelitis-induced animals treated with etomoxir or interferon-β. Sci Rep. 2018;8(1):7092.
Palamiuc L, Schlagowski A, Ngo ST, et al. A metabolic switch toward lipid use in glycolytic muscle is an early pathologic event in a mouse model of amyotrophic lateral sclerosis. EMBO Mol Med. 2015;7(5):526-546.
Shriver LP, Manchester M. Inhibition of fatty acid metabolism ameliorates disease activity in an animal model of multiple sclerosis. Sci Rep. 2011;1:79.
van der Windt GJ, Everts B, Chang CH, et al. Mitochondrial respiratory capacity is a critical regulator of CD8+ T cell memory development. Immunity. 2012;36(1):68-78.
NASHVILLE—Multiple sclerosis (MS) traditionally has been considered a chronic inflammatory autoimmune disease, but inflammation decreases as the disease progresses. Many other biologic processes are dysregulated in MS, such as myelin signal transport, mitochondrial function, and iron metabolism. Lipid metabolism affects all of these processes, including inflammation, and thus could be a valuable therapeutic target, according to research presented at the 2018 CMSC Annual Meeting.
“MS is not an inflammatory disease,” said John D. Nieland, PhD, Associate Professor of Health Science and Technology at Aalborg University in Denmark. “The inflammatory response is important, but it is not the only component. If you do not focus on the other components, you will never be able to treat the disease.”
The Role of Lipids in the CNS
Healthy brains have a high amount of glucose metabolism, but glucose metabolism is reduced in MS and other neurologic disorders such as Parkinson’s disease and Alzheimer’s disease. “If glucose metabolism is downregulated, something else has to be taking over,” said Dr. Nieland. He and his colleagues hypothesize that lipid metabolism replaces glucose metabolism in MS. They further hypothesize that MS fundamentally is a dysfunction of lipid metabolism.
Lipids have an essential role in the CNS. Proper signal transduction requires lipids to be bound to the myelin sheath. The proteins that compose myelin sheaths are highly immunogenic, and lipids shield them from exposure to the immune system. The half-life of lipids attached to the myelin sheath is three days, so these lipids must be replaced constantly. In addition, lipids are essential for the function of glutamate, cannabinoid, and insulin receptors.
An increase in lipid metabolism decreases glucose metabolism and induces the production of prostaglandin E2, which is a key molecule in the inflammatory response. In the early stages of MS, inflammation attacks the myelin sheath and other brain proteins. Increased lipid metabolism decreases lipid concentrations in the CNS, including around myelin. When lipids are removed from the myelin sheath, they expose the immunogenic proteins that compose it, thus provoking an immune response. Dysregulated lipid metabolism also contributes to oxidative stress, mitochondrial dysfunction, demyelination, and neuronal loss.
Chemical Inhibition of Lipid Metabolism
Dr. Nieland and colleagues hypothesized that blocking lipid metabolism would reverse the inflammatory response and other harmful processes that occur in MS. Previous research by Shriver and colleagues indicated that inhibition of carnitine palmitoyltransferase 1 (CPT1), a molecule essential to lipid metabolism, in encephalitogenic T cells increases apoptosis and reduces the production of inflammatory cytokines. Two of the molecule’s three isoforms, CPT1A and CPT1C, are upregulated in MS. Stress prompts an increase in CPT1 expression, which spurs a shift to lipid metabolism. “If you block CPT1, you jam lipid metabolism,” Dr. Nieland said. “There is no way around it.” Dr. Nieland’s group thus chose CPT1 as its target.
The investigators first conducted studies using etomoxir, which inhibits CPT1 and blocks long-chain fatty acids from entering the mitochondria for beta oxidation. Through these effects, etomoxir causes cells to shift to glucose metabolism.
The researchers immunized 42 mice with myelin oligodendrocyte glycoprotein (MOG35–55) to induce experimental autoimmune encephalopathy (EAE). When the animals first exhibited symptoms at Day 10, they were randomized to receive subcutaneous etomoxir or placebo daily. Disease score decreased significantly in the treated animals, compared with the control animals. On Day 24, more than 50% of the treated mice exhibited normal behavior, compared with approximately 20% of control mice.
In another study, the investigators immunized 47 rats with myelin basic protein to induce EAE. The animals began having symptoms at Day 7, and the investigators randomized them to daily treatment with subcutaneous etomoxir or placebo. At Day 11, disease score was significantly lower among treated animals, compared with control animals. Body weight was significantly higher among rats that received etomoxir, compared with controls, at that time point. Also, 25% of treated animals exhibited normal behavior, but no controls did.
In a third study, the investigators compared etomoxir, interferon beta, and placebo in a rat model of EAE. Each treatment group included 10 rats, and etomoxir had superior effects on disease score and body weight, compared with interferon beta and placebo. When the investigators examined the rats’ serum, they found that levels of antibodies against brain antigens common in EAE were lower in rats treated with etomoxir, compared with those treated with interferon beta or placebo.
Biologic Inhibition of Lipid Metabolism
In addition to pharmacologic treatment, genetic mutations affect CPT1 function. The Hutterites, an ethnoreligious group in Canada, have a mutation in CPT1A that almost completely blocks the molecule’s activity. Similarly, the Inuit have a mutation in CPT1A that reduces its activity to approximately 22%. The prevalence of MS is one in 1,100 among the Hutterites and one in 50,000 among the Inuit, compared with one in 350 in the Canadian population. These observations suggest that gene therapy could be another way to block CPT1.
Dr. Nieland’s group collaborated with the Netherlands Cancer Institute to develop mouse strains with two distinct mutations in CPT1A. The first mutation mimics that found among the Hutterites, and the other mimics that found among the Inuit. In a preliminary study, the investigators induced EAE in three wild-type mice and two mice with the CPT1A mutation similar to that of the Inuit. The mice were 10 weeks old at the time of immunization.
At 24 days, disease score was lower in the CPT1A mutant mice, compared with the wild-type mice. Furthermore, body weight was higher in the mutant mice, compared with the wild-type mice. The investigators also measured the mice’s grip strength at Day 2 and Day 24. Grip strength decreased in the wild-type mice but remained the same in the mutant mice. At Day 24, grip strength was significantly higher among mutant mice than among wild-type mice.
“These results indicate an interaction of the lipid metabolism in the brain and in the immune system, which supports our hypothesis regarding MS pathology,” said Anne Skøttrup Mørkholt, a doctoral student at Aalborg University, who collaborated with Dr. Nieland on these animal studies. “MS is not a disease of the immune system, but a systemic disease with dysregulation of multiple components.”
Lipid Metabolism in Other Neurologic Diseases
Data suggest that lipid metabolism may contribute to other neurologic diseases such as amyotrophic lateral sclerosis (ALS) as well. Huang et al found a correlation between serum triglyceride levels and the development of ALS. Dupuis et al observed upregulated lipid metabolism and downregulated glucose metabolism in SOD1 mouse models of the disease, as did subsequent researchers. In addition, a 2015 study by Palamiuc et al found that CPT1B was significantly increased in the muscle tissue of SOD1 mice.
To investigate whether suppressing lipid metabolism affected ALS, Dr. Nieland’s group examined a SOD1 mouse model of the disease. The mice developed symptoms at Day 70 and were randomized at Day 100 to etomoxir or placebo. Etomoxir was associated with less weight loss and better neurologic score, compared with placebo. Etomoxir also was associated with better performance on the wire hanging and rotarod tests, compared with placebo. “It seems like etomoxir was able to slow down the disease progression,” said Michael Sloth Trabjerg, MD, a doctoral student at Aalborg University.
Because research has found increased beta oxidation and decreased glucose metabolism in Parkinson’s disease, Dr. Nieland’s group studied the effect of CPT1 inhibition in a rotenone mouse model of the disease. They induced the disease in the mice for 32 days before randomizing them to placebo or etomoxir. For all mice, treatment alternated between rotenone on one day and placebo or etomoxir on the next day. The investigators observed significantly better sensorimotor performance among treated mice, compared with controls, on Day 47 and Day 56. At Day 60, mice who received etomoxir had significantly more muscle strength and longer latency to fall on the rotarod test, compared with mice that received placebo. These data are being prepared for publication.
The data suggest that dysregulated glucose metabolism and increased lipid metabolism play a role in ALS and Parkinson’s disease. “CPT1 seems to be a prominent target for moderating these diseases,” said Dr. Trabjerg.
—Erik Greb
Suggested Reading
Dodge JC, Treleaven CM, Fidler JA, et al. Metabolic signatures of amyotrophic lateral sclerosis reveal insights into disease pathogenesis. Proc Natl Acad Sci U S A. 2013;110(26):10812-10817.
Dupuis L, Oudart H, René F, et al. Evidence for defective energy homeostasis in amyotrophic lateral sclerosis: benefit of a high-energy diet in a transgenic mouse model. Proc Natl Acad Sci U S A. 2004;101(30):11159-11164.
Huang R, Guo X, Chen X, et al. The serum lipid profiles of amyotrophic lateral sclerosis patients: A study from south-west China and a meta-analysis. Amyotroph Lateral Scler Frontotemporal Degener. 2015;16(5-6):359-365.
Kim SM, Kim H, Kim JE, et al. Amyotrophic lateral sclerosis is associated with hypolipidemia at the presymptomatic stage in mice. PLoS One. 2011;6(3):e17985.
Lieury A, Chanal M, Androdias G, et al. Tissue remodeling in periplaque regions of multiple sclerosis spinal cord lesions. Glia. 2014;62(10):1645-1658.
Mørkholt AS, Kastaniegaard K, Trabjerg MS, et al. Identification of brain antigens recognized by autoantibodies in experimental autoimmune encephalomyelitis-induced animals treated with etomoxir or interferon-β. Sci Rep. 2018;8(1):7092.
Palamiuc L, Schlagowski A, Ngo ST, et al. A metabolic switch toward lipid use in glycolytic muscle is an early pathologic event in a mouse model of amyotrophic lateral sclerosis. EMBO Mol Med. 2015;7(5):526-546.
Shriver LP, Manchester M. Inhibition of fatty acid metabolism ameliorates disease activity in an animal model of multiple sclerosis. Sci Rep. 2011;1:79.
van der Windt GJ, Everts B, Chang CH, et al. Mitochondrial respiratory capacity is a critical regulator of CD8+ T cell memory development. Immunity. 2012;36(1):68-78.
NASHVILLE—Multiple sclerosis (MS) traditionally has been considered a chronic inflammatory autoimmune disease, but inflammation decreases as the disease progresses. Many other biologic processes are dysregulated in MS, such as myelin signal transport, mitochondrial function, and iron metabolism. Lipid metabolism affects all of these processes, including inflammation, and thus could be a valuable therapeutic target, according to research presented at the 2018 CMSC Annual Meeting.
“MS is not an inflammatory disease,” said John D. Nieland, PhD, Associate Professor of Health Science and Technology at Aalborg University in Denmark. “The inflammatory response is important, but it is not the only component. If you do not focus on the other components, you will never be able to treat the disease.”
The Role of Lipids in the CNS
Healthy brains have a high amount of glucose metabolism, but glucose metabolism is reduced in MS and other neurologic disorders such as Parkinson’s disease and Alzheimer’s disease. “If glucose metabolism is downregulated, something else has to be taking over,” said Dr. Nieland. He and his colleagues hypothesize that lipid metabolism replaces glucose metabolism in MS. They further hypothesize that MS fundamentally is a dysfunction of lipid metabolism.
Lipids have an essential role in the CNS. Proper signal transduction requires lipids to be bound to the myelin sheath. The proteins that compose myelin sheaths are highly immunogenic, and lipids shield them from exposure to the immune system. The half-life of lipids attached to the myelin sheath is three days, so these lipids must be replaced constantly. In addition, lipids are essential for the function of glutamate, cannabinoid, and insulin receptors.
An increase in lipid metabolism decreases glucose metabolism and induces the production of prostaglandin E2, which is a key molecule in the inflammatory response. In the early stages of MS, inflammation attacks the myelin sheath and other brain proteins. Increased lipid metabolism decreases lipid concentrations in the CNS, including around myelin. When lipids are removed from the myelin sheath, they expose the immunogenic proteins that compose it, thus provoking an immune response. Dysregulated lipid metabolism also contributes to oxidative stress, mitochondrial dysfunction, demyelination, and neuronal loss.
Chemical Inhibition of Lipid Metabolism
Dr. Nieland and colleagues hypothesized that blocking lipid metabolism would reverse the inflammatory response and other harmful processes that occur in MS. Previous research by Shriver and colleagues indicated that inhibition of carnitine palmitoyltransferase 1 (CPT1), a molecule essential to lipid metabolism, in encephalitogenic T cells increases apoptosis and reduces the production of inflammatory cytokines. Two of the molecule’s three isoforms, CPT1A and CPT1C, are upregulated in MS. Stress prompts an increase in CPT1 expression, which spurs a shift to lipid metabolism. “If you block CPT1, you jam lipid metabolism,” Dr. Nieland said. “There is no way around it.” Dr. Nieland’s group thus chose CPT1 as its target.
The investigators first conducted studies using etomoxir, which inhibits CPT1 and blocks long-chain fatty acids from entering the mitochondria for beta oxidation. Through these effects, etomoxir causes cells to shift to glucose metabolism.
The researchers immunized 42 mice with myelin oligodendrocyte glycoprotein (MOG35–55) to induce experimental autoimmune encephalopathy (EAE). When the animals first exhibited symptoms at Day 10, they were randomized to receive subcutaneous etomoxir or placebo daily. Disease score decreased significantly in the treated animals, compared with the control animals. On Day 24, more than 50% of the treated mice exhibited normal behavior, compared with approximately 20% of control mice.
In another study, the investigators immunized 47 rats with myelin basic protein to induce EAE. The animals began having symptoms at Day 7, and the investigators randomized them to daily treatment with subcutaneous etomoxir or placebo. At Day 11, disease score was significantly lower among treated animals, compared with control animals. Body weight was significantly higher among rats that received etomoxir, compared with controls, at that time point. Also, 25% of treated animals exhibited normal behavior, but no controls did.
In a third study, the investigators compared etomoxir, interferon beta, and placebo in a rat model of EAE. Each treatment group included 10 rats, and etomoxir had superior effects on disease score and body weight, compared with interferon beta and placebo. When the investigators examined the rats’ serum, they found that levels of antibodies against brain antigens common in EAE were lower in rats treated with etomoxir, compared with those treated with interferon beta or placebo.
Biologic Inhibition of Lipid Metabolism
In addition to pharmacologic treatment, genetic mutations affect CPT1 function. The Hutterites, an ethnoreligious group in Canada, have a mutation in CPT1A that almost completely blocks the molecule’s activity. Similarly, the Inuit have a mutation in CPT1A that reduces its activity to approximately 22%. The prevalence of MS is one in 1,100 among the Hutterites and one in 50,000 among the Inuit, compared with one in 350 in the Canadian population. These observations suggest that gene therapy could be another way to block CPT1.
Dr. Nieland’s group collaborated with the Netherlands Cancer Institute to develop mouse strains with two distinct mutations in CPT1A. The first mutation mimics that found among the Hutterites, and the other mimics that found among the Inuit. In a preliminary study, the investigators induced EAE in three wild-type mice and two mice with the CPT1A mutation similar to that of the Inuit. The mice were 10 weeks old at the time of immunization.
At 24 days, disease score was lower in the CPT1A mutant mice, compared with the wild-type mice. Furthermore, body weight was higher in the mutant mice, compared with the wild-type mice. The investigators also measured the mice’s grip strength at Day 2 and Day 24. Grip strength decreased in the wild-type mice but remained the same in the mutant mice. At Day 24, grip strength was significantly higher among mutant mice than among wild-type mice.
“These results indicate an interaction of the lipid metabolism in the brain and in the immune system, which supports our hypothesis regarding MS pathology,” said Anne Skøttrup Mørkholt, a doctoral student at Aalborg University, who collaborated with Dr. Nieland on these animal studies. “MS is not a disease of the immune system, but a systemic disease with dysregulation of multiple components.”
Lipid Metabolism in Other Neurologic Diseases
Data suggest that lipid metabolism may contribute to other neurologic diseases such as amyotrophic lateral sclerosis (ALS) as well. Huang et al found a correlation between serum triglyceride levels and the development of ALS. Dupuis et al observed upregulated lipid metabolism and downregulated glucose metabolism in SOD1 mouse models of the disease, as did subsequent researchers. In addition, a 2015 study by Palamiuc et al found that CPT1B was significantly increased in the muscle tissue of SOD1 mice.
To investigate whether suppressing lipid metabolism affected ALS, Dr. Nieland’s group examined a SOD1 mouse model of the disease. The mice developed symptoms at Day 70 and were randomized at Day 100 to etomoxir or placebo. Etomoxir was associated with less weight loss and better neurologic score, compared with placebo. Etomoxir also was associated with better performance on the wire hanging and rotarod tests, compared with placebo. “It seems like etomoxir was able to slow down the disease progression,” said Michael Sloth Trabjerg, MD, a doctoral student at Aalborg University.
Because research has found increased beta oxidation and decreased glucose metabolism in Parkinson’s disease, Dr. Nieland’s group studied the effect of CPT1 inhibition in a rotenone mouse model of the disease. They induced the disease in the mice for 32 days before randomizing them to placebo or etomoxir. For all mice, treatment alternated between rotenone on one day and placebo or etomoxir on the next day. The investigators observed significantly better sensorimotor performance among treated mice, compared with controls, on Day 47 and Day 56. At Day 60, mice who received etomoxir had significantly more muscle strength and longer latency to fall on the rotarod test, compared with mice that received placebo. These data are being prepared for publication.
The data suggest that dysregulated glucose metabolism and increased lipid metabolism play a role in ALS and Parkinson’s disease. “CPT1 seems to be a prominent target for moderating these diseases,” said Dr. Trabjerg.
—Erik Greb
Suggested Reading
Dodge JC, Treleaven CM, Fidler JA, et al. Metabolic signatures of amyotrophic lateral sclerosis reveal insights into disease pathogenesis. Proc Natl Acad Sci U S A. 2013;110(26):10812-10817.
Dupuis L, Oudart H, René F, et al. Evidence for defective energy homeostasis in amyotrophic lateral sclerosis: benefit of a high-energy diet in a transgenic mouse model. Proc Natl Acad Sci U S A. 2004;101(30):11159-11164.
Huang R, Guo X, Chen X, et al. The serum lipid profiles of amyotrophic lateral sclerosis patients: A study from south-west China and a meta-analysis. Amyotroph Lateral Scler Frontotemporal Degener. 2015;16(5-6):359-365.
Kim SM, Kim H, Kim JE, et al. Amyotrophic lateral sclerosis is associated with hypolipidemia at the presymptomatic stage in mice. PLoS One. 2011;6(3):e17985.
Lieury A, Chanal M, Androdias G, et al. Tissue remodeling in periplaque regions of multiple sclerosis spinal cord lesions. Glia. 2014;62(10):1645-1658.
Mørkholt AS, Kastaniegaard K, Trabjerg MS, et al. Identification of brain antigens recognized by autoantibodies in experimental autoimmune encephalomyelitis-induced animals treated with etomoxir or interferon-β. Sci Rep. 2018;8(1):7092.
Palamiuc L, Schlagowski A, Ngo ST, et al. A metabolic switch toward lipid use in glycolytic muscle is an early pathologic event in a mouse model of amyotrophic lateral sclerosis. EMBO Mol Med. 2015;7(5):526-546.
Shriver LP, Manchester M. Inhibition of fatty acid metabolism ameliorates disease activity in an animal model of multiple sclerosis. Sci Rep. 2011;1:79.
van der Windt GJ, Everts B, Chang CH, et al. Mitochondrial respiratory capacity is a critical regulator of CD8+ T cell memory development. Immunity. 2012;36(1):68-78.