Treating Obesity-Related Diseases with Parasitic Worms

New research has revealed that many parasitic worms, once inside a host, secrete a sugar-based anti-inflammatory molecule that might help treat metabolic disorders linked with obesity.

Although the latest pharmaceutical agents have made parasitic worm infection less of a threat in some areas, these organisms are still a major cause of disease and infirmity throughout much of the developing world. However, parasites are not all bad, according to new research by a team of scientists now at the University of Georgia (UGA; Atlanta, GA, USA), the Harvard School of Public Health (Boston, MA, USA), the Université François Rabelais (Tours, France), and the Central South University, Changsha (Hunan, China).

The study’s findings were published October 28, 2012, in the journal Nature Medicine. The sugar molecule (glycan) is released by parasites to help them evade the body’s immune system. By lessening 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 Dr. Donald Harn, study coauthor who worked on the research while at Harvard School of Public Health (Boston, MA, USA) and is now an investigator in the UGA College of Veterinary Medicine’s (Atlanta, GA, USA) department of infectious diseases.

The researchers assessed their theory on mice fed a high-fat diet. Those in the control group showed many of the symptoms associated with excessive weight gain, such as insulin resistance, high triglycerides, and high cholesterol. 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 Dr. Harn, who is also a member of UGA’s Faculty of Infectious Diseases and the Center for Tropical and Emerging Global Diseases (Atlanta, GA, USA). “It won’t prevent obesity, but it will help alleviate some of the problems caused by it.”

The same sugars excreted by the parasites are also found in the developing human fetus and in human breast milk, which Dr. Harn suspects 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.

Because parasites coevolved with mammals over millions of years, some scientists believe that the relationship between humans and worms is more symbiotic than parasitic, and that small worm infections might actually have some advantages. “Prevalence of inflammation-based diseases is very low in countries where people are commonly infected with worms,” Dr. Harn said. “But the minute you start deworming people, it doesn’t take too long for these autoimmune diseases to pop up.”

This does not imply that people should actively seek out parasitic infections as treatment, he said. But it is an indication that the compounds secreted by worms may serve as the basis for future therapies. In addition to obesity-related disease, Dr. Harn and his colleagues have demonstrated that the sugar molecule released by parasites may relieve a range of other serious inflammatory medical disorders. The glycan appears to serve as a powerful antirejection drug that may one day be used in patients who have received organ transplants. Moreover, it has been shown to block or even reverse the symptoms of multiple sclerosis in mice. Additionally, it may be used as a treatment for psoriasis, a disease that causes skin redness and irritation.

More research is needed before this sugar molecule can be tested in humans; however, the investigators are hopeful that they can create effective treatments that provide all the advantages 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.

Related Links:
University of Georgia, Atlanta College of Veterinary Medicine
University of Georgia’s Faculty of Infectious Diseases and the Center for Tropical and Emerging Global Diseases
Harvard School of Public Health