Crohn's disease is a chronic inflammatory disorder that causes ulcerations in the small and large intestines. Many scientists consider Crohn's to be an autoimmune disease--an illness that occurs when the body tissues are attacked by its own immune system. However, Anthony Segal (University College London, UK) and colleagues have found that, counter intuitively, the inflammation in Crohn's arises due to a weak immune response.

The investigators looked at the quantities of neutrophils (white blood cells) that patients with Crohn's disease produce in response to trauma at sites in the bowel (intestinal biopsy) and on the skin surface (skin abrasion). They found that in response to trauma, Crohn's disease patients produced much lower quantities of neutrophils and inflammatory mediators when compared with healthy individuals. Cultured blood cells were also abnormal in the patients. To test the inflammatory response to bacteria, the team also measured local inflammatory and blood flow changes in participants after injecting a harmless form of Escherichia Coli under their skin. In the healthy controls, blood flow in the area of inflammation increased approximately ten-fold by 24 hours. Crohn's disease patients, however, had much lower blood flow than controls. The researchers found that the abnormally low blood flow in Crohn's patients could be corrected by treatment with Viagra, indicating a possible role for the drug in the treatment of the disease.

The authors believe that in Crohn's disease, reduced or delayed recruitment of neutrophils to sites at which bacteria penetrate the intestinal wall might lead to the persistence of bacteria and other organic debris in the tissue.
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Contact: Joe Santangelo
j.santangelo@elsevier.com
212-633-3810
Lancet
23-Feb-2006