The Warsaw Voice » The Polish Science Voice » Monthly - November 3, 2015
Medicine
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Protecting with Parasites
   
Some parasites inhibit the activity of the human immune system. As a result, they can be used to fight autoimmune diseases such as asthma, allergies and lupus, says a Polish scientist, who plans to develop drugs that will affect the human immune system the same way as parasites such as the whipworm (Trichuris trichiura) and the hookworm.

In order to survive in the human body, parasites had to learn to inhibit the activity of a person’s immune system. “In the course of evolution they became our inseparable companions, teaching our immune system how not to become hyperactive,” says Piotr Bąska, Ph.D., from the Warsaw University of Life Sciences (SGGW).

This mechanism worked when the living standards and sanitary and hygienic conditions of the population were not high. Parasitic infestations were the order of the day back then. Today, especially in Europe and the United States, medical science has gotten rid of some parasites. Bąska says as a result, the human immune system has lost its braking mechanism, which leads to allergies, asthma, inflammatory bowel disease or autoimmune diseases such as rheumatoid arthritis, type 1 diabetes, lupus and multiple sclerosis. All these conditions are caused by excessive activity of the immune system, Bąska says, and their incidence is growing especially in developed countries. In addition to health problems, they entail economic losses. “In the European Union, asthma and inflammatory bowel disease alone generate losses running into billions of euros a year,” Bąska says.

For this reason, doctors sometimes have little choice but to administer parasites to patients. One of the most effective parasites is a nematode called the whipworm. This is a roundworm that causes trichuriasis when it infects a human large intestine. It is commonly known as the whipworm because it looks like a whip with wider “handles” at the posterior end. Studies have shown this worm can help patients suffering from inflammatory bowel disease. This is a chronic condition with bloody diarrhea, fever and other unpleasant symptoms.

Another parasite that may be used is the hookworm. This inhabits the intestines of humans and other animals and has hook-like mouth parts with which it attaches itself to the wall of the gut, puncturing the blood vessels and feeding on the blood.

Although clinical trials have not shown the expected effectiveness of the hookworm, this may be because only 10 worms were administered to patients during tests on humans for safety reasons, according to Bąska. “Such a dose may simply be too small to produce the desired therapeutic effect,” he says. He plans to use parasites, particularly hookworms, in a research project to weaken the symptoms of inflammatory bowel disease. Subsequently he wants to check how parasites affect the human immune system, which biochemical pathways they activate and which pathways they inhibit.

This will make it possible to design modern drugs emulating the effect produced by hookworms. These would be safer for humans than parasites. “We hope to be able to isolate, and offer in the form of a pill, what’s best in hookworms while eliminating the adverse effects,” says Bąska.

If someone is suffering from bloody diarrhea and life-threatening asthma attacks and must continually take steroids, Bąska says, the side effects of parasite-based therapy may be less burdensome than what the patient is going through every day.

At the same time, Bąska says he strongly discourages patients from taking parasites on their own. Such a “cure” can have adverse health effects, he says, and that’s why it should be supervised by a doctor. “People can react differently to a parasite invasion; for some it may be very dangerous,” Bąska says.
Olga Majewska