TNF-alpha sensitizes HT-29 colonic epithelial cells to intestinal lactobacilli

Vance J McCracken, Taehoon Chun, Manuel E Baldeón, Siv Ahrné, Göran Molin, Roderick I Mackie, H Rex Gaskins

Research output: Contribution to journalArticlepeer-review


The ability of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) to influence epithelial interleukin (IL)-8 responses to the intestinal bacterium Lactobacillus plantarum 299v was analyzed in the human HT-29 colonic epithelial cell line. In the absence of TNF-alpha, IL-8 mRNA expression was not detectable by Northern blot analysis in HT-29 cells alone or in HT-29 cells co-cultured with L. plantarum 299v. However, TNF-alpha induced IL-8 mRNA expression, and co-culture of TNF-alpha-treated HT-29 cells with L. plantarum 299v significantly increased IL-8 mRNA expression above levels induced by TNF-alpha alone in an adhesion-dependent manner. The increase in IL-8 mRNA expression was not observed in TNF-alpha-treated HT-29/L. plantarum 299v co-cultures using heat-killed lactobacilli or when L. plantarum adhesion was prevented using mannoside or a trans-well membrane. Paradoxically, IL-8 secretion was decreased in TNF-alpha-treated HT-29 cells with L. plantarum 299v relative to cells treated with TNF-alpha alone. TNF-alpha-mediated responsiveness to L. plantarum 299v was further investigated by analyzing expression of a coreceptor for bacterial cell wall products CD14. HT-29 cells expressed CD14 mRNA and cell-surface CD14; however, TNF-alpha did not alter CD14 mRNA or cell-surface expression, and blockade of CD14 with monoclonal antibody MY4 did not alter the IL-8 response to L. plantarum 299v in TNF-alpha-treated HT-29 cells. These results indicate that although TNF-alpha sensitizes HT-29 epithelial cells to intestinal lactobacilli, the bacteria exert a protective effect by downregulating IL-8 secretion.

Original languageEnglish (US)
Pages (from-to)665-670
Number of pages6
JournalExperimental Biology and Medicine
Issue number8
StatePublished - Sep 2002


  • Antibodies, Monoclonal/pharmacology
  • Bacterial Adhesion/drug effects
  • Cell Line/drug effects
  • Colon/cytology
  • Epithelial Cells/drug effects
  • Gene Expression Regulation/drug effects
  • Humans
  • Interleukin-8/biosynthesis
  • Intestinal Mucosa/cytology
  • Lactobacillus/physiology
  • Lipopolysaccharide Receptors/biosynthesis
  • Mannosides/pharmacology
  • Methylmannosides
  • RNA, Messenger/biosynthesis
  • Recombinant Fusion Proteins/pharmacology
  • Tumor Necrosis Factor-alpha/pharmacology


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