Critical role of toll-like receptors and nucleotide oligomerisation domain in the regulation of health and disease.
Pathogens are sensed by pattern recognition receptors (PRRs), which are germ line-encoded receptors, including transmembrane Toll-like receptors (TLRs) and cytosolic nucleotide oligomerisation domain (NOD) proteins, containing leucine-rich repeats (NLRs). Activation of PRRs by specific pathogen-associated molecular patterns (PAMPs) results in genomic responses in host cells involving activation transcription factors and the induction of genes. There are now at least 10 TLRs in humans and 13 in mice, and 2 NLRs (NOD1 and NOD2). TLR signalling is via interactions with adaptor proteins including MyD88 and toll-receptor associated activator of interferon (TRIF). NOD signalling is via the inflammasome and involves activation of Rip-like interactive clarp kinase (RICK). Bacterial lipopolysaccharide (LPS) from Gram-negative bacteria is the best-studied PAMP and is activated by or 'sensed' by TLR4. Lipoteichoic acid (LTA) from Gram-positive bacteria is sensed by TLR2. TLR4 and TLR2 have different signalling cascades, although activation of either results in symptoms of sepsis and shock. This review describes the rapidly expanding field of pathogen-sensing receptors and uses LPS and LTA as examples of how these pathways parallel and diverge from each other. The role of pathogen-sensing pathways in disease is also discussed.
Mitchell
Jane A
JA
Cardiothoracic Pharmacology, Unit of Critical Care Medicine, Cardiac Medicine, Royal Brompton Hospital, National Heart and Lung Institute, Imperial College, London SW3 6LY, UK. j.a.mitchell@imperial.ac.uk
Paul-Clark
Mark J
MJ
Clarke
Graham W
GW
McMaster
Shaun K
SK
Cartwright
Neil
N
D000818:Animals; D001424:Bacterial Infections / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D051379:Mice; D053472:Nod Signaling Adaptor Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D051193:Toll-Like Receptors / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism; D014777:Virus Diseases / Q000276:immunology / Q000378:metabolism
D008070:Lipopolysaccharides; D053472:Nod Signaling Adaptor Proteins; D051193:Toll-Like Receptors; D014764:Viral Proteins