Gemfibrozil Ameliorates Relapsing-Remitting Experimental Autoimmune Encephalomyelitis Independent of Peroxisome Proliferator-Activated Receptor-α

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Abstract
The present study underlines the importance of gemfibrozil, a lipid-lowering drug and an activator of peroxisome proliferator-activated receptor-α (PPAR-α), in inhibiting the disease process of adoptively transferred experimental allergic encephalomyelitis (EAE), an animal model of relapsing-remitting multiple sclerosis. Clinical symptoms of EAE, infiltration of mononuclear cells, and demyelination were significantly lower in SJL/J female mice receiving gemfibrozil through food chow than those without gemfibrozil. It is noteworthy that the drug was equally effective in treating EAE in PPAR-α wild-type as well as knockout mice. Gemfibrozil also inhibited the encephalitogenicity of MBP-primed T cells and switched the immune response from a Th1 to a Th2 profile independent of PPAR-α. Gemfibrozil consistently inhibited the expression and DNA-binding activity of T-bet, a key regulator of interferon-γ (IFN-γ) expression and stimulated the expression and DNA-binding activity of GATA3, a key regulator of IL-4. Gemfibrozil treatment decreased the number of T-bet–positive T cells and increased the number of GATA3-positive T cells in spleen of donor mice. The histological and immunohistochemical analyses also demonstrate the inhibitory effect of gemfibrozil on the invasion of T-bet–positive T cells into the spinal cord of EAE mice. Furthermore, we demonstrate that the differential effect of gemfibrozil on the expression of T-bet and GATA3 was due to its inhibitory effect on NO production. Although excess NO favored the expression of T-bet, scavenging of NO stimulated the expression of GATA-3. Taken together, our results suggest gemfibrozil, an approved drug for hyperlipidemia in humans, may find further therapeutic use in multiple sclerosis.