Effects of enteropathogenic bacteria & lactobacilli on chemokine secretion & Toll like receptor gene expression in two human colonic epithelial cell lines.
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Date
2009-08
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Abstract
Background & objectives: The intestinal epithelium is part of the innate immune system responding
to contact with pathogenic or commensal bacteria. The objective of this study was to compare innate
responses of intestinal epithelial cell lines to pathogenic bacteria and to lactobacilli.
Methods: Two human intestinal epithelial cell lines, HT29 (enterocyte-like) and T84 (crypt-like), were
exposed to pathogenic bacteria representative of non invasive (Vibrio cholerae O1 and O139), adherent
(enterohaemorrhagic Escherichia coli, EHEC) or invasive (Salmonella Typhimurium and Shigella
flexneri) phenotypes and to non pathogenic Lactobacillus rhamnosus GG or Lactobacillus plantarum.
Interleukin-8 (IL-8) was measured in culture supernatant by ELISA, while mRNA from cells was
subjected to quantitative reverse transcriptase PCR for several other chemokines (CXCL1, CCL5 and
CXCL5) and for Toll-like receptors (TLR) 2, 4, 5 and 9.
Results: V. cholerae, S. Typhimurium, S. flexneri and EHEC induced IL-8 secretion from epithelial
cells into the medium. Salmonella, Shigella and EHEC, but not V. cholerae, significantly increased
mRNA expression of CXCL1. None of the pathogens induced CCL5 or CXCL5. Salmonella and Vibrio
significantly increased TLR4 expression, while Vibrio and EHEC decreased TLR5 expression. EHEC
also decreased TLR9 expression. Lactobacilli attenuated the IL-8 response of the cell lines to V. cholerae,
Salmonella, and EHEC but did not significantly change the IL-8 response to Shigella.
Interpretation & conclusions: Distinct patterns of epithelial cell chemokine responses were induced by
the bacterial pathogens studied and these were modulated by commensal lactobacilli. Alterations in TLR
expression by these pathogens are likely to be important in pathogenesis.
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Keywords
Chemokine, enteropathogenic bacteria, interleukin-8, intestinal epithelial cells, Lactobacillus, Toll-like receptor
Citation
Nandakumar N S, Pugazhendhi S, Ramakrishna B S. Effects of enteropathogenic bacteria & lactobacilli on chemokine secretion & Toll like receptor gene expression in two human colonic epithelial cell lines. Indian Journal of Medical Research. 2009 Aug; 130(2): 170-178.