A parasitic worm that lives in the gut might be the key to helping some people with Crohn's disease, a new study published in Science suggests. The idea springs from the discovery that in certain parts of the world, parasitic worm infections correlate to lower rates of autoimmune disorders such as Crohn's and other inflammatory bowel diseases. Gaining a clear understanding of how those worms work might provide hope for many of the more than 700,000 people suffering from the disease in the U.S.
Crohn’s disease is a chronic inflammation of the gastrointestinal tract, usually in the small intestine. People who have Crohn’s can suffer diarrhea, abdominal cramping and pain, weight loss and fatigue.
What lab tests with mice reveal
To test the idea that the parasitic whipworm might prevent Crohn’s disease, researchers used mice with a defective Nod2 gene, the same genetic defect found in some Crohn's cases. When the scientists gave the mice a drug that inflamed the small intestine, the mucus layer of the intestine thinned, bacteria from the Clostridiales family decreased and another common microbe called bacteroides vulgatus increased.
The mice then were infected with whipworms. Mucus production in the small intestine increased while inflammation declined. In addition, the levels of bacteroides vulgatus decreased and clostriadiales bacteria increased. A second worm proved even more effective.
The scientists found that the worms produced a specific immune response known as Type 2 immunity. This sparked the production of mucus and helped restore the balance of bacteria in the small intestine.
The senior author of the study, Dr. Ken Cadwell, a professor of biomolecular medicine at New York University, sees promise in the lab mice results. Now the question is: How can scientists produce the same results – but without the worms?
Earlier tests in Malaysia
Prior to their lab tests with mice, the research team examined bacteria in the intestines of people living in a rural Malaysian village. A majority of the villagers showed signs of worm infestation. After undergoing a de-worming treatment, the villagers’ levels of bacteroides vulgatus rose, while Clostridiales bacteria declined.
Comparing these results with the mice study seems to suggest that Clostridiales might be the key to helping balance intestinal bacteria.
Results from clinical human trials
While this study offers hope for Crohn's sufferers, there are still unanswered questions. People with Crohn’s all share a chronic inflammation of the small intestine, but the cause varies from person to person.
Only about a third of people with Crohn's have the Nod2 gene mutation, and it is only in those patients that bacteroidales microbes agitate the immune system. The study suggests that the worm therapy may only help these patients. It might also explain why clinical trials using the worms on humans have proved unsuccessful so far.
Questions?
If you want to stay up to date on information about inflammatory bowel diseases including Crohn's, visit the Crohn’s & Colitis Foundation of America.
If you have questions about Crohn's or other intestinal problems, find a Providence provider near you.
