NOS2 and colitis: In addition, NO was shown to protect the gut barrier function in certain circumstances,47 and a previous report suggested that MDSCs expressing NOS2 accumulate in the gut to suppress inflammation in a T cell-dependent murine colitis model.48 Therefore, it is tempting to speculate that the early migration of NO-producing MDSC-PGE2 in the gut could be responsible for the observed suppression of Th17 cells at the systemic level and their lower infiltration into the CNS.