May 27, 2005

Immune factor may improve Crohn's disease symptoms

A drug that stimulates a specific part of the immune system may improve symptoms of Crohn's disease, according to a study in the May 26 issue of the New England Journal of Medicine (NEJM). An MGH-led research team reports that treatment with the growth factor GM-CSF significantly reduced symptom severity and improved quality of life after 56 days of daily drug injections.

"We've proposed that the inflammation occurring with Crohn's is actually secondary to an earlier problem — a defect with the gastrointestinal innate immune system, which stops microbes from entering the body," says Joshua Korzenik, MD, co-director of the MGH Crohn's and Colitis Center and lead author of the NEJM study. "If normal intestinal bacteria are not controlled by the innate immune system, a compensatory secondary inflammation could produce the symptoms of Crohn's."

Korzenik has been investigating this hypothesis for several years, in collaboration with Brian Dieckgraefe, MD, PhD, of Washington University School of Medicine in St. Louis. The researchers developed their hypothesis based on studies of certain genetic disorders known to affect the innate immune system, some of which feature symptoms virtually identical to those of Crohn's.

Patients with moderate to severe Crohn's disease enrolled in the study at 28 centers across the United States. Of the 94 participants who completed the 56-day treatment cycle, 57 received daily injections of GM-CSF while 37 received placebo injections. Based on a standard index of Crohn's disease symptoms, significantly more participants receiving GM-CSF were judged to have major improvement or remission of their symptoms than were those receiving placebo injections. "We're encouraged that these results support this new understanding of Crohn's and hope they will lead to a new treatment option for the disease," says Korzenik.