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. Author manuscript; available in PMC: 2017 Aug 1.
Published in final edited form as: Nat Rev Dis Primers. 2016 Jun 30;2:16045. doi: 10.1038/nrdp.2016.45

Figure 1. Cell-surface and intracellular receptors that are responsible for the recognition of microbial products and endogenous danger signals (alarmins).

Figure 1

Sepsis is initiated upon host recognition of pathogen- associated molecular patterns (PAMPs) and is characterized by the activation of inflammatory signalling pathways. A large number of cell-associated and intracellular receptors are available to detect PAMPs or damage-associated molecular patterns (DAMPs), a few examples of which are illustrated here. PAMPs and DAMPs can be microbial and host glycoproteins, lipoproteins and nucleic acids. The associated pattern- recognition receptors include Toll-like receptors (TLRs), C-type lectin domain family 7 member A (dectin 1) and C-type lectin domain family 6 member A (dectin 2). At least ten different TLRs are known, and in many cases they exist as either homodimers or heterodimers. Once activated, the ensuing signalling pathways generally converge towards interferon regulatory factor (IRF) signalling and nuclear factor-κB (NF-κB). IRF is responsible for type I interferon (IFN) production. NF-κB and activator protein 1 (AP-1) signalling are predominately responsible for the early activation of inflammatory genes, such as TNF, IL1 and those encoding endothelial cell-surface molecules. CARD9, caspase recruitment domain-containing protein 9; dsDNA, double-stranded DNA; dsRNA, double-stranded RNA; FcRγ, Fcγ receptor; HMGB1, high-mobility group protein B1; iE-DAP, d-glutamyl-meso-diaminopimelic acid; LGP2, laboratory of genetics and physiology 2 (also known as DHX58); LPL, lipoprotein lipase; LPS, lipopolysaccharide; LY96, lymphocyte antigen 96; MAPK, mitogen- activated protein kinase; MCG, mannose-containing glycoprotein; MDA5, melanoma differentiation-associated protein 5 (also known as IFIH1); MDP, muramyl dipeptide; MCL, mannose-capped lipoarabinomannan; Mincle, also known as CLEC4E; MYD88, myeloid differentiation primary response protein 88; NIK, NF-κB-inducing kinase (also known as MAP3K14); NOD, nucleotide-binding oligomerization domain; RAF1, RAF proto-oncogene serine/threonine-protein kinase; RAGE, advanced glycosylation end product-specific receptor; RIG-I, retinoic acid-inducible gene 1 protein (also known as DDX58); ssRNA, single-stranded RNA; STING, stimulator of interferon genes protein; SYK, spleen tyrosine kinase; TDM, trehalose-6,6′-dimycolate; TICAM1, TIR domain-containing adaptor molecule 1.