TLR4 and autoimmune polyendocrinopathy: In conclusion, APS might suppress CD4+CD25+Treg activity, at least in part, via binding TLR4 on the surface of CD4+CD25+Tregs, and trigger a shift of Th2 to Th1 with activation of CD4+ T cell-mediated immunity in burned mice combined with P. aeruginosa infection.