Toll-like receptor 4 plays significant roles during allergic rhinitis.

Allergic rhinitis is a nasal hypersensitivity and allergic disease which leads to inflammation of nasal mucosa. Previous investigations revealed that innate immune receptors play a key role in the pathogenesis of inflammatory diseases including allergic diseases. Toll-like receptors (TLRs), which are important innate immune receptors, play crucial roles in the recognition of foreign antigens, including allergens, and subsequently for the induction of immune responses such as inflammation. There are several controversial reports regarding the roles of TLR4 in the pathogenesis of allergic rhinitis. This review presents current information regarding the roles of TLR4 in the pathogenesis of allergic rhinitis and the plausible mechanisms which lead to the expression and function of TLR4 in this disease.