RESUMEN
Bacterial growth in multicellular communities, or biofilms, offers many potential advantages over single-cell growth, including resistance to antimicrobial factors. Here we describe the interaction between the biofilm-promoting components curli fimbriae and cellulose of uropathogenic E. coli and the endogenous antimicrobial defense in the urinary tract. We also demonstrate the impact of this interplay on the pathogenesis of urinary tract infections. Our results suggest that curli and cellulose exhibit differential and complementary functions. Both of these biofilm components were expressed by a high proportion of clinical E. coli isolates. Curli promoted adherence to epithelial cells and resistance against the human antimicrobial peptide LL-37, but also increased the induction of the proinflammatory cytokine IL-8. Cellulose production, on the other hand, reduced immune induction and hence delayed bacterial elimination from the kidneys. Interestingly, LL-37 inhibited curli formation by preventing the polymerization of the major curli subunit, CsgA. Thus, even relatively low concentrations of LL-37 inhibited curli-mediated biofilm formation in vitro. Taken together, our data demonstrate that biofilm components are involved in the pathogenesis of urinary tract infections by E. coli and can be a target of local immune defense mechanisms.
Asunto(s)
Catelicidinas/fisiología , Fimbrias Bacterianas/inmunología , Escherichia coli Uropatógena/inmunología , Adulto , Péptidos Catiónicos Antimicrobianos , Proteínas Bacterianas , Biopelículas/crecimiento & desarrollo , Línea Celular , Celulosa/metabolismo , Niño , Células Epiteliales/microbiología , Femenino , Humanos , Inmunidad , Interleucina-8/biosíntesis , Masculino , Infecciones Urinarias/etiología , Infecciones Urinarias/microbiologíaRESUMEN
Cytotoxic necrotizing factor 1 (CNF1) is a well-defined virulence factor of uropathogenic Escherichia coli. We studied the role of CNF1 in uroepithelial cells as well as in children and adults with sporadic and recurrent UTI. Our study suggests that CNF1 may promote bacterial attachment and invasion and can induce an inflammatory response in the urinary tract in vitro but that its role in vivo is possibly minor in comparison with other virulence factors of the uropathogenic E. coli.