The negative regulation of Toll-like receptor and associated pathways

Toll-like receptors (TLRs) are essential mediators of both innate and adaptive immunity by recognizing and eliciting responses upon invasion of pathogens. The response of TLRs must be stringently regulated as exaggerated expression of signalling components as well as pro-inflammatory cytokines can have devastating effects on the host, resulting in chronic inflammatory diseases, autoimmune disorders and aid in the pathogenesis of TLR-associated human diseases. Therefore, it is essential that negative regulators act at multiple levels within TLR signalling cascades, as well as through eliciting negative-feedback mechanisms in order to synchronize the positive activation and negative regulation of signal transduction to avert potentially harmful immunological consequences. This review explores the various mechanisms employed by negative regulators to ensure the appropriate modulation of both immune and inflammatory responses.