Toll-Like Receptor 4 in Ventilator-Induced Lung Injuries

Toll like receptors (TLRs) recognize pathogens and generate an immediate defense response by inducing the production of pro-inflammatory cytokines, which rapidly destroy or limit the pathogens. In their bridging role, TLR downstream signals link innate and adaptive immunity, particularly by mediating DC maturation and activation of pathogen specific T lymphocytes. These pathways lead to the activation of professional APCs, which is followed by enhanced expression of surface molecules, MHC and co-stimulatory molecules [CD40, CD80, CD86 and CD70].TLRs are expressed in a variety of cell types, mostly within the immune system where they have been linked to different cellular activation states, immune defense, maintenance of homeostasis, and various diseases. TLRs and related immunological pathways are being extensively studied for research, diagnostic and therapeutic purposes. Most mammalian species have between ten and fifteen types of TLRs. Ten functional TLRs (TLR1-10) have been identified in human.?