Role of the haem oxygenase/carbon monoxide pathway in Clostridium difficile toxin A-induced enteritis in mice

J Med Microbiol. 2011 Aug;60(Pt 8):1146-1154. doi: 10.1099/jmm.0.028910-0. Epub 2011 Mar 3.


Clostridium difficile is the major cause of antibiotic-associated colitis, a disease with significant morbidity and mortality. This study investigated the role of the haem oxygenase-1 (HO-1)/carbon monoxide (CO) pathway in C. difficile toxin A-induced enteritis in mice. The HO substrate haemin, zinc protoporphyrin IX (ZnPP IX), a specific HO-1 inhibitor, dimanganese decacarbonyl (DMDC), a CO donor, or an equivalent volume of their respective vehicles were injected subcutaneously 30 min prior to local challenge with toxin A (25 or 50 µg per ileal loop) or PBS. Intestinal ileal loop weight/length ratios were calculated 3 h later. Ileal tissues were collected for histological analysis and measurement of myeloperoxidase (MPO) activity, tumour necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) production by ELISA and immunohistochemistry for HO-1. Treatment of mice subjected to C. difficile toxin A (TcdA) with haemin or DMDC prevented oedema, mucosal disruption and neutrophil infiltration observed in histological analysis. It also decreased TcdA-induced MPO activity and TNF-α or IL-1β production. In contrast, the specific HO-1 inhibitor (ZnPP IX) exacerbated all these evaluated parameters. TcdA increased HO-1 expression as seen by immunohistochemistry. These results suggest that the HO-1/CO pathway exerts a protective role in TcdA-induced enteritis and that its pharmacological modulation might be important for the management of C. difficile-associated disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Toxins / toxicity*
  • Carbon Monoxide / metabolism*
  • Deoxyuridine / analogs & derivatives
  • Deoxyuridine / pharmacology
  • Enteritis / chemically induced*
  • Enteritis / prevention & control
  • Enterotoxins / toxicity*
  • Heme Oxygenase (Decyclizing) / genetics
  • Heme Oxygenase (Decyclizing) / metabolism*
  • Hemin / pharmacology
  • Ileum / drug effects
  • Intestinal Mucosa / drug effects
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Protoporphyrins / pharmacology


  • Bacterial Toxins
  • Enterotoxins
  • Protoporphyrins
  • Ro 09-3431
  • tcdA protein, Clostridium difficile
  • zinc protoporphyrin
  • Hemin
  • Carbon Monoxide
  • Heme Oxygenase (Decyclizing)
  • Deoxyuridine