B cell-derived transforming growth factor-β1 expression limits the induction phase of autoimmune neuroinflammation

Studies in experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS), have shown that regulatory B cells modulate the course of the disease via the production of suppressive cytokines. While data indicate a role for transforming growth factor (TGF)-β1 expression in regulatory B cell functions, this mechanism has not yet been tested in autoimmune neuroinflammation. Transgenic mice deficient for TGF-β1 expression in B cells (B–TGF-β1(−/−)) were tested in EAE induced by recombinant mouse myelin oligodendrocyte glycoprotein (rmMOG). In this model, B–TGF-β1(−/−) mice showed an earlier onset of neurologic impairment compared to their littermate controls. Exacerbated EAE susceptibility in B–TGF-β1(−/−) mice was associated with augmented CNS T helper (Th)1/17 responses. Moreover, selective B cell TGF-β1–deficiency increased the frequencies and activation of myeloid dendritic cells, potent professional antigen-presenting cells (APCs), suggesting that B cell-derived TGF-β1 can constrain Th1/17 responses through inhibition of APC activity. Collectively our data suggest that B cells can down-regulate the function of APCs, and in turn encephalitogenic Th1/17 responses, via TGF-β1, findings that may be relevant to B cell-targeted therapies.