T cell derived HB-EGF prevents Th17 cell differentiation in an autocrine way

ABSTRACT CD4 T cells critically contribute to host immunity against infections, but can also contribute to the development of autoimmune diseases. The underlying mechanisms that govern differentiation of naïve CD4 T cells into different effector populations remain poorly understood. Here, we show that the expression of the Epidermal Growth Factor (EGF)-like growth factor HB-EGF by CD4 T cells sustained their expression of Interleukin (IL)-2 and reduced their capacity to differentiate into T Helper 17 (Th17) cells. Concordantly, mice with a T cell specific deficiency of HB-EGF showed an enhanced differentiation of naïve CD4 T cells into Th17 cells and a more rapid onset of experimental autoimmune encephalomyelitis (EAE). Furthermore, transfer of naïve HB-EGF-deficient CD4 T cells into Rag1 -/- mice led to the rapid induction of multi-organ inflammation in recipient mice. Together, our data reveal a novel mechanism by which an HB-EGF-mediated constrain on Th17 differentiation prevents the development of autoimmune diseases. SUMMARY CD4 T cell activation induces the expression of the EGFR and its high-affinity ligand HB-EGF. HB-EGF sustains IL-2 expression in an autocrine manner, preventing the differentiation of Th17 cells and the subsequent induction of Th17 cell-mediated autoimmune diseases.