The expression of Toll-like receptors in human gingival epithelium

Introduction: Epithelial lining of our skin and digestive tract has long been recognized as the first line of barrier against the invasion of innumerous overlying microflora. It was recently suggested that the epithelium not only functions as a physical barrier but also actively interacts with our immune system to maintain an optimal level of immune response. Toll-like receptors (TLR) are considered as the crucial molecules in linking innate and adaptive immune responses. The activation of TLRs will induce the expression several proinflammatory cytokines that have been found related to the occurrence and severity of periodontitis. Objectives: In this study, our group investigated the expression of TLRs in human gingival tissues and studied the effects of TLRs activation in epithelial cells. Methods: Human gingival tissues were collected from periodontally diseased and sound subjects (n=7 for each group) for immunohistochemical (IHC) and immunofluorescent (IF) detection of the expression of TLR2, TLR4, and TLR9. The effects of TLRs activation in epithelial cells were studied in epithelial cell lines. The expression of type I interferons and tumor necrosis factor-a (TNF-a) in the epithelial culture upon activation of TLRs was measured with enzyme-linked immunosorbent assay (ELISA). Results: The expression of TLRs in human gingival epithelium was found correlated with the periodontal status of the subjects. Conclusions: TLRs signaling in gingival epithelium may play an important role in the maintenance of periodontal health.