Regulation of IL-10 and IL-17 mediated experimental autoimmune encephalomyelitis by S-nitrosoglutathione

In this study, we investigated IL-10 and IL-17 specific immunomodulatory potential of S-nitrosoglutathione (GSNO), a physiological nitric oxide carrier molecule, in experimental autoimmune encephalomyelitis (EAE). In active EAE model, GSNO treatment attenuated EAE severity and splenic CD4⁺ T cells isolated from these mice exhibited decreased IL-17 expression without affecting the IFN-γ expression compared to the cells from untreated EAE mice. Similarly, adoptive transfer of these cells to nave mice resulted in reduction in IL-17 expression in the spinal cords of recipient mice with milder EAE severity. CD4⁺ T cells isolated from GSNO treated EAE mice, as compared to untreated EAE mice, still expressed lower levels of IL-17 under T_H17 skewing conditions, but expressed similar levels of IFN-γ under T_H1 skewing condition. Interestingly, under both T_H17 and T_H1 skewing condition, CD4⁺ T cells isolated from GSNO treated EAE mice, as compared to untreated EAE mice, expressed higher levels of IL-10 and adoptive transfer of these T_H17 and T_H1 skewed cells seemingly exhibited milder EAE disease. In addition, adoptive transfer of CD4⁺ T cells from GSNO treated EAE mice to active EAE mice also ameliorated EAE disease with induction of spinal cord expression of IL-10 and reduction in of IL-17, thus suggesting the participation of IL-10 mechanism in GSNO mediated immunomodulation. GSNO treatment of mice passively immunized with CD4⁺ T cells either from GSNO treated EAE mice or untreated mice further ameliorated EAE disease, supporting efficacy of GSNO for prophylaxis and therapy in EAE. Overall, these data document a modulatory role of GSNO in IL-17/IL-10 axis of EAE and other autoimmune diseases.