Parasitic worms used to fight bowel disease

Although most of us cringe at the sound of the words "parasitic worms," it's a fact that some of these creatures are actually good for us.

At Michigan State University, researcher Linda Mansfield is part of a national team of scientists investigating the role that parasites can play in treating inflammatory bowel disease, or IBD, in humans.

Her research is part of a more than $10 million National Institutes of Health grant supporting the Food and Waterborne Diseases Integrated Research Network of laboratories launched by the National Institutes of Allergy and Infectious Diseases.

Some researchers argue that improved hygiene throughout the developed world may be responsible for inflammatory bowel disease, as well as a whole range of autoimmune disorders. According to this "hygiene hypothesis," immune systems require exposure to infections of all sorts early in life in order to develop sufficiently.

Intriguingly, inflammatory bowel disease, which has two forms – Crohn's disease and ulcerative colitis – is virtually unknown in the developing world, while it is increasing dramatically in developed societies. When people from developing countries move to developed ones, their incidence of the disease tends to increase.

"We know from veterinary medicine that many bacterial and protozoan pathogens, especially those that multiply inside of cells, elicit an immune response in the host that would normally cause inflammation, but that worm parasites mount an anti-inflammatory defense that modulates it," said Mansfield, a professor of large animal clinical sciences. "The greater the immune response, the greater the anti-inflammatory effect.

"It's possible that the human immune system developed in a way that is dependent on parasitic worms to regulate immune responses."

The particular worm that Mansfield and colleagues are studying as a potential treatment is known as the whipworm, or Trichuris suis, which is a parasite that afflicts pigs. Early studies have shown that giving humans a concoction of whipworm eggs and Gatorade is very effective in treating inflammatory bowel disease.

Mansfield and colleagues are using some of the NIH funding to develop an animal model to test the effectiveness of the worms on inflammatory bowel disease and other maladies. Also, she is waiting for word on a new NIH grant that will support efforts to learn how the treatment works.

"The bottom line right now is that we know none of the mechanisms of how this works," she said.

Mansfield, as well as other researchers, also wants to apply this effort to a variety of autoimmune conditions, such as asthma, diabetes and multiple sclerosis. Some researchers suggest that all of these conditions can be explained as combinations of the hygiene hypothesis and genetics.

Source : Michigan State University