Findings may lead to new treatments for debilitating bowel diseases, experts say
Wednesday, December 1, 2010
WEDNESDAY, Dec. 1 (HealthDay News) -- The case of a man who swallowed parasite eggs to treat his ulcerative colitis -- and actually got better -- sheds light on how "worm therapy" might help heal the gut, a new study suggests.
"Our findings in this case report suggest that infection with the eggs of the T. trichiura roundworm can alleviate the symptoms of ulcerative colitis," said study leader P'ng Loke, an assistant professor in the department of medical parasitology at NYU Langone Medical Center. A human parasite, Trichuris trichiura infects the large intestine.
The findings could also lead to new ways to treat the debilitating disease, a form of inflammatory bowel disease (IBD) currently treated with drugs that don't always work and can cause serious side effects, said Loke.
The study findings are published in the Dec. 1 issue of Science Translational Medicine.
Loke and his team followed a 35-year-old man with severe colitis who tried worm (or "helminthic") therapy to avoid surgical removal of his entire colon. He researched the therapy, flew to a doctor in Thailand who had agreed to give him the eggs, and swallowed 1,500 of them.
The man contacted Loke after his self-treatment and "was essentially symptom-free," Loke said. Intrigued, he and his colleagues decided to follow the man's condition.
The study analyzed slides and samples of the man's blood and colon tissue from 2003, before he swallowed the eggs, to 2009, a few years after ingestion. During this period, he was virtually symptom-free for almost three years. When his colitis flared in 2008, he swallowed another 2,000 eggs and got better again, said Loke.
Tissue taken during active colitis showed a large number of CD4+ T-cells, which are immune cells that produce the inflammatory protein interleukin-17, the team found. However, tissue taken after worm therapy, when his colitis was in remission, contained lots of T-cells that make interleukin-22 (IL-22), a protein that promotes wound healing.
Further, after worm therapy, the man's colon produced significantly more mucus, said Loke, who noted that a lack of mucus in the colon is linked with severe symptoms. "We think the worms increase or restore mucus production in the colon," he said. "Basically, the gut is trying to expel the worms. This increase in mucus may play a role in relieving the symptoms."
"This is not the usual clinical trial, but you take your opportunities for unique observation where you can," said Dr. Gerald W. Dryden Jr., director of the clinical research division of gastroenterology, hepatology and nutrition at the University of Louisville, in Kentucky.
Before this study, IL-22 had not been associated with beneficial effect in IBD, said Dryden. "While it doesn't determine cause-and-effect, the study does seem to demonstrate an important, previously unknown association between IL-22 and response to helminthic therapy," he said.
Causing abdominal pain, diarrhea and other symptoms, colitis affects about 700,000 Americans, according to the Crohn's and Colitis Foundation of America. Scientists don't know what causes the disease, but theorize that immune-system dysfunction plays a role.
Colitis is common in developed countries such as America -- where parasitic worm infections are rare -- and in Asia, Africa and Latin America, where virtually the entire population is infected, the study noted. Clinical trials with the pig whipworm Trichuris suis have improved the symptoms of both ulcerative colitis and Crohn's disease, and animal studies suggest that various parasitic worms can suppress inflammation, the study noted.
The study also suggests new, worm-based treatments for both ulcerative colitis and IBD. Research might identify molecules derived from worms that suppress inflammation, or pathways activated by worms that can be targeted by more conventional approaches, Loke said.
Right now, however, worm therapy is still not well-understood and could potentially backfire, the study warned. "The problem is that these worms themselves can cause harm and damage the gut," said Loke. "The individual in this study is lucky to have responded so well, but for other people the worm infection may exacerbate bowel inflammation." Studies that use the pig worm, which should pose less risk to humans, are under way, he added.
SOURCES: P'ng Loke, assistant professor, department of medical parasitology, NYU Langone Medical Center, New York City; Gerald W. Dryden Jr., director, clinical research division, gastroenterology, hepatology and nutrition, University of Louisville, Kentucky; Dec. 1, 2010, Science Translational Medicine