Abstract 1295: Role of glycine N-methyltransferase in the regulation of T cell responses in experimental autoimmune encephalomyelitis

Glycine N-methyltransferase (GNMT) is known for its function as a tumor suppressor gene. Since 100% of female Gnmt −/− mice developed hepatocellular carcinoma, we hypothesized that Gnmt −/− mice may have defective immune surveillance. In this study, we examined the immune modulation of GNMT in T cell responses using experimental autoimmune encephalomyelitis (EAE). The results showed that EAE severity was significantly reduced in Gnmt −/− mice. Pathological examination of the spinal cords revealed that Gnmt −/- mice had significantly lower level of mononuclear cell infiltration and demyelination than the wild-type mice. In addition, quantitative real-time PCR showed that expression levels of pro-inflammatory cytokines, including IFN-gamma and IL-17A, were much lower in the spinal cord of Gnmt −/- than in that of wild-type mice. Accordingly, myelin oligodendrocyte glycoprotein (MOG)-specific T cell proliferation and induction of T helper (Th) 1 and Th17 cells were markedly suppressed in MOG 35-55 induced Gnmt −/- mice. Moreover, the amount of regulatory T cells was significantly increased in these mice. When the T cell receptor was stimulated, the proliferative capacity and the activation status of mTOR-associated downstream signaling were significantly decreased in GNMT −/- CD4 + T cells via an IL-2 and CD25-independent manner. Moreover, GNMT deficiency enhanced the differentiation of regulatory T cells without affecting the differentiation of Th1 and Th17 cells. Furthermore, the severity of EAE in mice adoptive transferred with GNMT-deficient CD4 + T cells was much milder than in those with wild-type CD4 + T cells. In summary, our findings suggest that GNMT is involved in the pathogenesis of EAE and plays a crucial role in the regulation of CD4 + T cell functions. Citation Format: Chung-Hsien Li, Ming-Hong Lin, Yen-Fu Chen, Shih-Han Chu, Pang-Hsien Tu, Cheng-Chieh Fang, Chia-Hung Yen, Peir-In Liang, Jason C. Huang, Yu-Chia Su, Huey-Kang Sytwu, Yi-Ming A. Chen. Role of glycine N-methyltransferase in the regulation of T cell responses in experimental autoimmune encephalomyelitis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1295. doi:10.1158/1538-7445.AM2015-1295