Unusual and Promising Approaches to Allergy Prevention and Treatment

As strange as it may seem, early exposure to pets, peanuts, and intestinal worms might actually be good for you. Evidence to support this view has been mounting for more than a decade. But now, for the first time, researchers are beginning to test remedies based on these theories in patients. Other doctors are trying to make use of novel approaches to retrain the immune system once it’s too late and allergies set in.

“What we’ve learned is that it may, in fact, be important to be exposed early on to a sufficient quantity of allergy-causing substances to train the immune system that they are not a threat,” says Andy Saxton of the University of California – Los Angeles. “And in people who already have allergies, we see for the first time where the problems lie, and we have new opportunities to tweak the system.”

If the new approaches work, millions might benefit. More than 50 million people have allergic diseases, which are the sixth-leading cause of chronic illness in the United States, according to the National Intitute of Allergy and Infectious Diseases (NIAID). In fact, allergies cost the health system $18 billion a year.

If educating the immune system is tough, re-educating it after allergies set in appears to be tougher. Allergy shots work, but they’re costly and often must be continued for years. Then the protection fades over time. There are two new strategies being developed that may improve treatment.

One strategy, pioneered by researchers at Dynavax Technologies in Berkeley California, involves disguising a key ragweed protein with DNA from a bacterium. The goal is to create a short course of allergy shots that tricks the immune system into permanently thinking that ragweed is a bacterium, so it will attack it like a germ and not mount an allergic response. The approach has appeared to work in early trials at John Hopkins University.

A second strategy, now being developed by Saxon and his colleagues at UCLA and licensed to the biotech firm Biogen Idec, involves fusing a cat allergen with a snippet of a powerful antibody call IgG. This IgG snippet turns off cells that make histamine, the chemical that produces allergic symptoms. Researchers hope the combo will turn off histamine-producing cells, and in time, retrain the immune system to accept that cats are harmless.

The new approach to allergy prevention and treatment arises from a paradox. Known as the “hygiene hypothesis,” it suggests that growing up in cities and suburbs, away from fields and animals, leaves people more susceptible to a host of immune disorders, including allergies and asthma.

It has been shown through a study by Dennis Ownby of the Medical College of Georgia that children exposed early in a home with two or more cats or dog, are 45% less likely to test positive for allergies than other kids. The study appeared in the August 28, 2002 Journal of the American Medical Association. One possible explanation is that dogs and cats shed a substance called endotoxin from bacteria. A related study by Andy Liu of National Jewish Medical and Research Center in Denver reported in 2002 that infants with the most endotoxin exposure were the least likely to have allergies.

Researchers have also found that worms also have potential as allergy-busters. Weinstock, and his collaborator, David Elliott of the University of Iowa found that worm infections appear to regulate the immune system so that it functions normally. Robert Coffman, vice president of the biotech firm Dynavax Technologies says that the immune system developed two sets of responses: one for bacteria and viruses, and one for worms. Called Th1 for germs and Th2 for worms, they work in opposition. When Th1 is active, Th2 takes a break, and vice versa. All of the symptoms people link with allergy are part of the Th2 response.

Weinstock, Elliott, and other researchers believe that a low-grade infection with intestinal worms – pig whipworms because they cannot reproduce in humans - can restore the immune system. In fact, a small-scale study proved that of 29 people with Crohn’s disease who drank a brew of Gatorade and whipworm eggs, 23 responded to the treatment and 21 of those 23 had complete remission.

Whether it is endotoxin or worms, scientists continue to investigate all of the factors that can confer protection against allergy and other immune diseases.

(Summarized from: USA TODAY, March 19, 2006, article by: Steve Sternberg; Copyright© 2006 USA TODAY. Distributed by Knight-Ridder/Tribune Information Services. March 19, 2006.)