Immunotoxicogenomics: big word—big potential

There is no cure for allergies. They are a chronic condition. For some, allergies are little more than an annoyance—a runny nose and itchy eyes at certain times of the year. For others, exposure to an allergen can be life-threatening.

Our economy also suffers from allergies—they account for hundreds-of-millions of dollars a year in additional health care costs and lost productivity.

It's been estimated that up to six percent of all children and four percent of adults are allergic to something, and the incidence of allergies is increasing. The biological process that causes us to develop an allergy is fairly well understood—it is our immune system responding to something that it considers a threat.

Our immune system never forgets

What is not understood is why, even though we may have eaten eggs many times, that our immune system suddenly decides eggs are a threat. The allergy becomes chronic, because our immune system has a long memory—once it decides eggs are a threat, it will almost certainly react every time we eat one.

Could chemicals be causing this?

With the support of funding through the Government of Canada's Genomics Research and Development Initiative (GRDI), Drs. David Lefebvre and Genevieve Bondy and their colleagues at Health Canada are studying whether exposure to certain chemicals could be causing our immune system to make these kinds of mistakes.

"When we have an allergic reaction, it's a reaction to a protein in a food we've eaten or something we've contacted," says Dr. Bondy, Head of the Molecular and Applied Toxicology Section at Health Canada. "What we're trying to figure out is whether a chemical can set off an allergic reaction to proteins in foods like eggs or peanuts, or whether it can affect our immune system in a way that makes an existing allergy more intense."

Getting down to the molecular level

Dr. Lefebvre says the research involves looking at how the cells that make up our immune system react to exposure to different chemicals.

"We're looking at how certain chemicals cause changes in gene expression in immune cells, trying to identify what are often referred to as biomarkers—basically, identifying changes that happen in the immune cell when a particular chemical is introduced."

Testing the test

"We're at the very early stage of this research," says Dr. Bondy."We are working with chemicals that we already know will cause some changes in immune responses, looking for the relationship between the changes we see at the cellular level and the changes in immune responses to allergens that have been documented through animal testing in the past," says Dr. Bondy. "The hope is that eventually, we will be able to show a clear link between the changes we see in immune cells and the physical manifestations that are observed when animals are exposed to these same chemicals."

"If we can do that," says Dr. Lefebvre, "This method could be used to look at a proposed new food additive, for example, and ensure it wouldn't stimulate allergy-promoting pathways in immune cells—so, in theory, this could help reduce the incidence of new allergies."

Less testing with animals?

Another possible benefit of the immunotoxicogenomics research Dr. Bondy and her colleagues are doing is the potential to significantly reduce the need for using animals in testing the safety of chemicals.

"There are a lot of very good reasons to want to do less testing with animals—the high cost of those kinds of studies is just one," says Dr. Bondy. "That's a priority for Health Canada and a big part of the value of toxicogenomics—not just in our work on allergies, but in testing the toxicity of any chemical. If we can do those tests with fewer animals and learn more about food allergies, I think most people would agree that would be a good thing."

Could exposure to certain chemicals cause our immune system to suddenly decide we are allergic to a food we've enjoyed for years?