16 January 2013

Parasitic worms could treat obesity disorders

by Will Parker

On the list of unwelcome medical conditions, a parasitic worm infection ranks fairly high. But according to an international team of scientists, the sugar-based anti-inflammatory molecule that many parasitic worms secrete inside the human body might actually help treat the metabolic disorders associated with obesity.

The researchers, from the University of Georgia, the Harvard School of Public Health, the Université François Rabelais (France) and the Central South University (Hunan, China), have published details of their investigation in Nature Medicine.

The sugar molecule, or glycan, is released by parasites to help them evade the body's immune system. By reducing inflammation, they are better able to hide in tissues, and humans experience fewer symptoms that might reveal their presence.

"Obesity is an inflammatory disease, so we hypothesized that this sugar might have some effect on complications related to it," said Donald Harn, study co-author who worked on the research while at Harvard School of Public Health.

The researchers tested their hypothesis on mice fed a high-fat diet. Those in the control group exhibited many of the symptoms associated with excessive weight gain, such as insulin resistance, high triglycerides and high cholesterol. The mice that received treatment with the sugar still gained weight, but they did not suffer the same negative health effects as those in the control.

"All of the metabolic indicators associated with obesity were restored to normal by giving these mice this sugar conjugate," said Harn. "It won't prevent obesity, but it will help alleviate some of the problems caused by it."

Intriguingly, the same sugars excreted by the parasites are also found in the developing human fetus and in human breast milk. Harn suspects their presence may establish proper metabolic functions in the newborn infant. Beyond infancy, however, sugar expression is only found on a few cells, and the only external source for the sugar is parasitic worms.

Harn and other scientists speculate that the relationship between humans and worms might be more symbiotic than parasitic, and that small worm infections might actually have some benefits. "Prevalence of inflammation-based diseases is extremely low in countries where people are commonly infected with worms," Harn said. "But the minute you start deworming people, it doesn't take too long for these autoimmune diseases to pop up."

Harn adds that people shouldn't actively seek out parasitic infections as treatment, "but it is an indication that the compounds secreted by worms may serve as the basis for future therapies."

In addition to obesity-related disorders, Harn and his colleagues have demonstrated that the sugar molecule released by the worms may alleviate a number of other serious inflammatory conditions, including psoriasis and multiple sclerosis. He cautions that these results have only been demonstrated in mice, and more research is needed before the molecule can be tested in humans.

The researchers are, however, hopeful the new findings may lead to effective treatments that provide all the benefits of parasitic worms without the worms themselves. "We see great promise in this sugar, and we hope that future research and collaborations will eventually lead to marketable therapies for people suffering from disease," he concluded.

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Source: University of Georgia