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Escherichia coli K12: An evolving opportunistic commensal gut microbe distorts barrier integrity in human intestinal

Mohd Iqbal Bhat1, Kandukuri Sowmya1, Suman Kapila1

  • 1Animal Biochemistry Division, ICAR-National Dairy Research Institute, Karnal, Haryana, India.

Microbial Pathogenesis
|May 22, 2019
PubMed

Insights

Commensal gut bacteria like E. coli K12 can disrupt intestinal barrier function. This study shows E. coli K12 damages intestinal cells, increasing permeability and altering tight junction proteins in vitro.

Area of Science:

  • Microbiology
  • Cell Biology
  • Gastroenterology

Background:

  • Commensal enteric microbes can adopt pathogenic phenotypes under specific conditions.
  • Disruption of intestinal epithelial barrier function is linked to various diseases.

Purpose of the Study:

  • To investigate how the commensal gut microbe E. coli K12 disrupts intestinal epithelial barrier function in vitro.
  • To elucidate the molecular mechanisms underlying E. coli K12-induced barrier dysfunction.

Main Methods:

  • Utilized Caco-2 cell monolayers to model the intestinal epithelial barrier.
  • Assessed barrier integrity by measuring transepithelial electrical resistance (TEER) and phenol red flux.
  • Analyzed gene expression of tight junction proteins (ZO-1, Claudin-1, Occludin, Cingulin-1, PIgR, hBD-2) using RT-qPCR.
  • Examined protein localization and cellular morphology via immunofluorescence and electron microscopy.

Main Results:

  • E. coli K12 exposure significantly decreased TEER and increased phenol red flux in Caco-2 cells, indicating increased permeability.
  • Suppressed mRNA levels of tight junction proteins (ZO-1, Claudin-1, Occludin, Cingulin-1) were observed.
  • Upregulated mRNA levels of PIgR and hBD-2 were noted.
  • Disrupted distribution of ZO-1 and Claudin-1, along with actin filament alterations and cellular deformation, were evident in infected cells.

Conclusions:

  • E. coli K12 disrupts intestinal barrier function in a compromised in vitro environment.
  • This disruption involves decreased expression of key tight junction genes and altered protein distribution.
  • Increased intestinal permeability is a direct consequence of E. coli K12-induced barrier defects.
Keywords:
Caco-2Commensal microbesEscherichia coliHyperpermeabilityTransepithelial electrical resistance

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