Extracellular MUC3 mucin secretion follows adherence of Lactobacillus strains to intestinal epithelial cells in vitro

Gut. 2003 Jun;52(6):827-33. doi: 10.1136/gut.52.6.827.

Abstract

Background: Mucins are large complex glycoproteins that protect intestinal mucosal surfaces by limiting access of environmental matter to their epithelial cells. Several mucin genes have been described, including MUC3 that is a membrane associated mucin of the small intestine. Increased MUC3 mRNA transcription is induced by incubation of intestinal epithelial cells with a Lactobacillus strain known to be adherent to them.

Aims: To determine whether increased epithelial cell MUC3 mucin expression in response to Lactobacillus strains results in increased extracellular secretion of MUC3 mucins and the importance of epithelial cell adherence in modulation of MUC3 mucin expression.

Methods: HT29 cells grown to enhance expression of MUC3 mucins were incubated with selected Lactobacillus strains. Spent cell culture medium was collected for detection of secreted MUC3 mucins using dot blot immunoassay with a generated MUC3 antibody. Post-incubation HT29 cell RNA was collected for analysis of MUC3 expression by northern blot analysis using a MUC3 cDNA probe. In vitro binding studies using Lactobacillus strains incubated alone or coincubated with enteropathogenic Escherichia coli strain E2348/69 were used for adherence and inhibition of adherence studies, respectively.

Results: Lactobacillus strains with minimal ability to adhere to HT29 cells failed to induce upregulation of mucin gene expression. There was a direct correlation between upregulation of MUC3 mucin mRNA expression and extracellular secretion of MUC3 mucin. The same Lactobacillus strains that increased extracellular secretion of MUC3 mucin led to reduced adherence of enteropathogen E coli E2348/69 during coincubation experiments.

Conclusion: Probiotic microbes induce MUC3 mucin transcription and translation with extracellular secretion of the MUC3 mucins. Epithelial cell adherence enhances the effects of probiotics on eukaryotic mucin expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Adhesion / physiology*
  • Blotting, Northern
  • Epithelial Cells / metabolism
  • Epithelial Cells / microbiology
  • Escherichia coli / pathogenicity
  • Escherichia coli / physiology
  • Fluorescent Antibody Technique, Indirect
  • HT29 Cells
  • Humans
  • Immune Sera / immunology
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / microbiology
  • Lactobacillus / physiology*
  • Mucin-3
  • Mucins / biosynthesis*
  • Mucins / genetics
  • Mucins / immunology
  • RNA, Messenger / genetics
  • Up-Regulation

Substances

  • Immune Sera
  • Mucin-3
  • Mucins
  • RNA, Messenger