Pathogen-specific TLR signaling in mucosa: mutual contribution of microbial TLR agonists and virulence factors

SIRARD JC; BAYARDO M; DIDIERLAURENT A

EUROPEAN JOURNAL OF IMMUNOLOGY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2006

0014-2980

Detection of microorganisms through microbe-associated molecular patterns (MAMP)by Toll-like receptors (TLR) is crucial to trigger protective immunity. In the mucosa,sentinel cells are exposed to MAMP from both pathogens and commensals; however, theTLR response is tightly controlled to avoid inflammation in response to commensals.Uropathogenic Escherichia coli (UPEC) trigger innate responses during urinary tractinfection in a TLR4-dependent and CD14-independent manner. UPEC express virulencefactors, such as type 1 fimbriae and/or P fimbriae, allowing bacterial attachment to theepithelium. In this issue of the European Journal of Immunology, Fisher et al. show thatfimbriae are required to induce a TLR4-specific epithelial response. Depending on thefimbriae expressed by UPEC, different adaptor molecules are involved in TLR4signaling. These data add to the recent body of evidence suggesting that TLR responsesare regulated by co-receptors, such as receptors for virulence factors. In conclusion, the?pathogenic? TLR stimulation provides a novel way for the host to ignore commensalbacteria.