Differential effects of varying concentrations of clostridium difficile toxin A on epithelial barrier function and expression of cytokines

J Infect Dis. 2004 Jun 1;189(11):2110-9. doi: 10.1086/386287. Epub 2004 Apr 30.


Background: Presentation after Clostridium difficile infection may depend on the level of epithelial exposure to toxins. We investigated epithelial barrier function and expression of interleukin (IL)-8 and transforming growth factor (TGF)-beta in response to varying concentrations of C. difficile toxin A.

Methods: T84 cells were either preexposed or continuously exposed to C. difficile toxin A (0.01-1000 ng/mL). Barrier function was assessed by measurements of transepithelial electrical resistance.

Results: Preexposure to < or =10 ng/mL toxin A led to an increase in the release of TGF-beta 1, but there was no change in the expression of IL-8. In contrast, after preexposure to >10 ng/mL toxin A, there was enhanced expression of IL-8, but release of TGF-beta 1 was similar to that in control monolayers. After preexposure to >10 ng/mL toxin A, there was complete and irreversible loss of electrical resistance. At lower concentrations, loss of resistance across monolayers was followed by recovery, which was enhanced by all 3 recombinant isoforms of TGF-beta. Pretreatment with recombinant isoforms of TGF-beta or coculture with TGF-beta 3-expressing colonic subepithelial myofibroblasts was also protective.

Conclusions: In C. difficile infection, the development and severity of colonic inflammation may depend on the exposure of intestinal epithelial cells to toxins and the expression of proinflammatory (IL-8) and protective (TGF-beta) factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / pharmacology*
  • Biological Assay
  • Clostridium difficile / chemistry*
  • Coculture Techniques
  • Electric Impedance
  • Enterotoxins / pharmacology*
  • Enzyme-Linked Immunosorbent Assay
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Fibroblasts
  • Humans
  • Interleukin-8 / biosynthesis*
  • Interleukin-8 / metabolism
  • Intestinal Mucosa / cytology
  • Intestinal Mucosa / drug effects*
  • Intestinal Mucosa / metabolism
  • Protein Isoforms
  • Transforming Growth Factor beta / biosynthesis*
  • Transforming Growth Factor beta / metabolism


  • Bacterial Toxins
  • Enterotoxins
  • Interleukin-8
  • Protein Isoforms
  • Transforming Growth Factor beta
  • tcdA protein, Clostridium difficile