CD4 and colitis: Along the same line is the demonstration that induction of DSS colitis is associated with an increase in the number of T-cell immunoreceptor with immunoglobulin and ITIM (TIGIT)-expressing CD4 + TRM cells producing IL-17A and IFN-γ and TIGIT deficiency inhibits IL-17A production by such cells, resulting in attenuation of colitis (178).