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Toll-like receptor 4 expression and cytokine responses in the human urinary tract mucosa.

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Author

Summary, in English

Mucosal pathogens trigger a local innate host response by activating epithelial cells. Bacterial adherence and Toll-like receptor 4 (TLR4) signaling have been implicated as key events in this process. This study addressed the molecular basis of the epithelial response to gram-negative infection in the human urinary tract. Mucosal biopsies were obtained from kidneys, ureters, and bladders of patients undergoing urinary tract surgery, and epithelial TLR4 and CD14 expression was examined by immunohistochemistry. TLR4 was detected in epithelial cells lining the entire urinary tract and in the renal tubular epithelium. CD14, in contrast, was completely absent from the epithelial tissue. The response of the epithelial cells to infection was studied by in vitro challenge of the biopsies with uropathogenic Escherichia coli bacteria. A rapid cytokine response was observed, with production of interleukin-1ß (IL-1ß), IL-6, and IL-8 but not of IL-4 or gamma interferon. Adhering, P- or type 1-fimbriated E. coli activated IL-6 and IL-8 production more efficiently than the nonfimbriated control, as shown by cellular staining and analysis of secreted cytokines. The results demonstrate that human uroepithelial cells possess the molecular machinery needed to respond to uropathogenic E. coli. This includes recognition receptors for fimbriae and TLR4 for transmembrane signaling. We speculate that the lack of membrane-bound CD14 allows the epithelium to regulate its sensitivity to lipopolysaccharide and to discriminate between more-virulent and less-virulent strains.

Publishing year

2004

Language

English

Pages

3179-3186

Publication/Series

Infection and Immunity

Volume

72

Issue

6

Document type

Journal article

Publisher

American Society for Microbiology

Topic

  • Microbiology in the medical area
  • Immunology in the medical area
  • Urology and Nephrology

Status

Published

Research group

  • Urology

ISBN/ISSN/Other

  • ISSN: 1098-5522