Toll- like receptors: Sensing the dangers within !!!!

Toll- like receptors (TLRs) are a class of proteins that play a key role in the innate immune system and are present in gingival crevicular fluid and the epithelial cell layer in addition to other immune cells such as macrophages, Langerhans cells, tissue dendritic cells, and migratory neutrophils which was revealed on histological examination of healthy periodontal tissue. Since the gingiva is considered exposed to bacterial pathogen - associated molecular patterns, the TLRs present on gingival epithelial cells are continuously stimulated, resulting in production of cytokines and defensins that help to maintain oral health. If the epithelial barrier is breached, allowing invasion of bacteria into the underlying connective tissue, the TLRs on other resident and non-resident cells of the periodontium become activated. This leads to an exaggerated release of pro-inflammatory cytokines and other biological mediators, which may cause host tissue destruction. Toll - like receptor sensing and signalling in periodontal tissue could indeed play an important role in the innate immune response and maintain periodontal health.