Musculin does not modulate the disease course of Experimental Autoimmune Encephalomyelitis and DSS colitis

Previous evidences show that Musculin (Msc), a repressor member of basic helix-loop-helix transcription factors, is responsible in vitro for the low responsiveness of human Th17 cells to the growth factor IL-2, providing an explanation for Th17 cells rarity in inflammatory tissue. However, how and to what extent Musculin gene can regulate the immune response in vivo in an inflammatory context is still unknown. Here, exploiting two animal models of inflammatory diseases, the Experimental Autoimmune Encephalomyelitis (EAE) and the dextran sodium sulfate (DSS)-induced colitis, we evaluated the effect of Musculin gene knock-out on clinical course, performing also a deep immune phenotypical analysis on T cells compartment and an extended microbiota analysis in colitis-sick mice. We found that, at least during the early phase, Musculin gene has a very marginal role in modulating both the diseases. Indeed, the clinical course and the histological analysis showed no differences between wild type and Msc knock-out mice, whereas immune system appeared to give rise to a regulatory milieu in lymph nodes of EAE mice and in the spleen of DSS colitis-sick mice. Moreover, in the microbiota analysis, we found irrelevant differences between wild type and Musculin knock-out colitis-sick mice, with a similar bacterial strains' frequency and diversity after the DSS treatment. This work strengthened the idea of a negligible Msc gene involvement in these models.