Worming their way to a cure

From The Irish Times
By Claire O’Connell

Researchers in Trinity are looking at a new way to tackle allergies – the downside is, it involves worms. Claire O’Connell reports

An apple a day might keep the doctor away, but a worm could also have its uses. It may sound unpalatable, but researchers are increasingly looking at parasitic worm species to treat disease. In particular, there’s a growing trend of looking to worms to help treat conditions where the immune system over-reacts inappropriately, such as allergies, asthma and intense inflammation.

The use of parasites to treat disease will be the subject of a public discussion tomorrow evening in Dublin led by Dr Pádraic Fallon, a research senior lecturer at the school of biochemistry and immunology in Trinity College Dublin (TCD). It is of particular interest to Ireland, because Irish children rank fourth in the world for allergies, he says.

One new approach to developing treatments for allergies looks at how parasitic worms change our immune systems, says Fallon. Unlike today’s industrialised setting, we evolved in a very different environment where we had parasitic worms in our bodies. These worms developed ways of dampening down our immune reactions so they could survive in us, and this bypassing mechanism could point the way to new therapies.

“What the worm wants to stop is the responses that are associated with allergies or intense inflammation,” he says.

So effective are some species that clinical trials in the United Kingdom and United States are using live roundworms to treat patients with conditions like inflammatory bowel disease and hay fever, according to Fallon. And while the mere thought of signing up for a live infection of worms might put you off your dinner, he says there is no shortage of volunteers for the trial treatments.

Fallon’s own research focuses on identifying the mechanism by which a flatworm called Schistosoma mansoni subdues the immune system. “In Africa, where some people are still infected, studies have shown that schoolchildren infected with schistosomes have lower allergic responses to dust mites,” he says. “The worm is ticking away inside you, suppressing responses that can cause allergies and other diseases.”

But the Schistosoma infection, which can last 10-40 years if left untreated, can be damaging or even kill, so he does not advocate live schistosome worms as a therapy. Instead, his group is identifying molecules the flatworms use to suppress the immune system, with a view to developing the molecules as drug treatments for conditions like asthma and inflammation. “We think it’s the safest way,” he says. “A molecule from a worm is just a therapeutic, whereas when treating someone with a live parasite there is an issue with safety and also people would find that undesirable.”

So far the TCD group has identified a molecule from the flatworm that helps reduce tissue inflammation in mice. “It has specifically evolved to remove proteins in the circulation that produce inflammation, so there we have got an individual therapeutic molecule isolated.” They have also narrowed the search for molecules that dampen allergic responses in the mice.

Fallon notes there is a real need for these new approaches of learning from parasites to treat allergies. But he is not a fan of the “hygiene” theory that in order to challenge and strengthen our immune systems we need to ease back on over-cleaning our environment, noting that this view is too simplistic. “In the last 30 or 40 years, asthma and other allergies have exploded in developed countries, so it’s a very recent change in our lifestyle that has caused this allergy epidemic,” he says, listing a wide range of possible contributing factors like obesity, smoking, soft furnishings and widespread use of antibiotics. “There are people who say it’s all down to dirt, but it is more complicated than that and the evidence is not there to advocate a drastic change in people’s lifestyle.”

Dr Pádraic Fallon will discuss the use of parasitic worms to cure disease at The Alchemist Café, at Dublin’s Central Hotel on Exchequer Street tomorrow at 7.45pm. Admission is free. See www.alchemistcafe.cjb.net

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