TLR4 and infectious otitis media: Although complete deletion of TLR4 in TLR4-/- mice did not protect from severe DSS-induced inflammation (36), the specific lack of TLR4 signaling on colonic epithelial cells inhibited CAC development, as well as recruitment and activation of Cyclooxygenase (Cox)-2 expressing macrophages in the AOM/DSS model (14, 16).