Epithelial cell extrusion leads to breaches in the intestinal epithelium

Inflamm Bowel Dis. 2013 Apr;19(5):912-21. doi: 10.1097/MIB.0b013e3182807600.

Abstract

Background: Two distinct forms of intestinal epithelial cell (IEC) extrusion are described: 1 with preserved epithelial integrity and 1 that introduced breaches in the epithelial lining. In this study, we sought to determine the mechanism underlying the IEC extrusion that alters the permeability of the gut epithelium.

Methods: IEC extrusions in polarized T84 monolayer were induced with nigericin. Epithelial permeability was assessed with transepithelial electrical resistance and movements of latex microspheres and green fluorescent protein-transfected Escherichia coli across the monolayer. In vivo IEC extrusion was modulated in wild-type and a colitic (interleukin-10 knock-out) mouse model with caspase-1 activation and inhibition. Luminal aspirates and mucosal biopsies from control patients and patients with inflammatory bowel disease were analyzed for caspase-1 and caspase-3&7 activation.

Results: Caspase-1-induced IEC extrusion in T84 monolayers resulted in dose-dependent and time-dependent barrier dysfunction, reversible with caspase-1 inhibition. Moreover, the movements of microspheres and microbes across the treated epithelial monolayers were observed. Increased caspase-1-mediated IEC extrusion in interleukin-10 knock-out mice corresponded to enhanced permeation of dextran, microspheres, and translocation of E. coli compared with wild type. Caspase-1 inhibition in interleukin-10 knock-out mice resulted in a time-dependent reduction in cell extrusion and normalization of permeability to microspheres. Increased IEC extrusion in wild-type mice was induced with caspase-1 activation. In human luminal aspirates, the ratio of positively stained caspase-1 to caspase-3&7 cells were 1:1 and 2:1 in control patients and patients with inflammatory bowel disease, respectively; these observations were confirmed by cytochemical analysis of mucosal biopsies.

Conclusions: IEC extrusion mediated by caspase-1 activation contributes to altered intestinal permeability in vitro and in vivo.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Blotting, Western
  • Case-Control Studies
  • Caspase 1 / metabolism
  • Caspase 3 / metabolism
  • Cell Differentiation
  • Cell Membrane Permeability*
  • Cell Proliferation
  • Cell Surface Extensions / metabolism
  • Cell Surface Extensions / pathology*
  • Cells, Cultured
  • Cytokines / metabolism
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology*
  • Fluorescent Antibody Technique
  • Humans
  • Inflammatory Bowel Diseases / metabolism
  • Inflammatory Bowel Diseases / pathology*
  • Interleukin-10 / physiology*
  • Intestinal Mucosa / metabolism
  • Intestinal Mucosa / pathology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout

Substances

  • Cytokines
  • Interleukin-10
  • Caspase 3
  • Caspase 1