TLR5 gene

The TLR5 gene (TLR5 stands for Toll Like Receptor 5) is a protein-coding gene located on chromosome 1q41. An important paralog of this gene is TLR8 (see also Toll-like receptors).

The TLR5 gene encodes a member of the Toll-like receptor (TLR) family, which plays a fundamental role in the recognition of pathogens and the activation of innate immune responses. The receptors recognize various pathogen-associated molecular patterns(PAMPs) that are expressed on infectious agents.

TLR5 is a pattern recognition receptor (PRR) on the cell surface that is involved in the activation of innate immunity and the inflammatory response (Hayashi F et al. 2001; Blohmke CJ et al. 2008).

TLTR5 recognizes small molecular motifs called pathogen-associated molecular patterns (PAMPs), which are expressed by pathogens, and microbe-associated molecular patterns (MAMPs), which are normally expressed by the resident microbiota (Bielaszewska M et al. 2018).

For example, TLRr5 recognizes bacterial flagellin, the main component of bacterial flagella and a virulence factor (see below Borrelia burgdorferii s.l.)( (Hayashi F et al. 2001). After binding ligands such as bacterial flagellins, it recruits the intracellular adapter proteins MYD88 and TRIF, which leads to the activation of NF-kappa-B, the secretion of cytokines and the triggering of the inflammatory response (Blohmke CJ et al. 2008). It thus plays an important role in the relationship between the intestinal epithelium and the intestinal microbes and contributes to the composition of the intestinal microbiota throughout life.

Mutations in the TLR5 gene have been associated with both resistance and susceptibility to systemic lupus erythematosus and susceptibility to Legionnaires' disease and melioidosis.

1. Bielaszewska M et al. (2018) Enterohemorrhagic Escherichia coli O157 outer membrane vesicles induce interleukin 8 production in human intestinal epithelial cells by signaling via Toll-like receptors TLR4 and TLR5 and activation of the nuclear factor NF-κB. Int J Med Microbiol 308:882-889
2. Blohmke CJ et al. (2008) Innate immunity mediated by TLR5 as a novel anti-inflammatory target for cystic fibrosis lung disease. J Immunol 180:7764-7773.
3. Hayashi F et al. (2001) The innate immune response to bacterial flagellin is mediated by Toll-like receptor 5. Nature 410:1099-1103.