Dear Doc: Conference topics relate environment to children’s allergies, plus’ traffic cop Tregs’
Dr. Patrick Klemawesch had the opportunity to attend the annual meeting of the American Academy of Allergy Asthma and Immunology (AAAAI) this month. This is the largest annual allergy conference — four days of lectures, seminars, and presentation of data from researchers and clinicians around the world.
Some of the most interesting research presented came from the Cincinnati Allergy and Air Pollution Study. Many studies are currently looking at the effects of people’s surroundings on their development of allergies and asthma. This is a unique project, because rather than starting with allergic kids and looking backward in time to try to root out causes, the study started following children at birth. “High-risk” kids (those with allergic and asthmatic parents) were enrolled in the study at birth and assessed annually.
One significant finding was that children of all ages had more frequent wheezing when exposed to diesel exhaust, and that the exposure was highest within 400 meters of a “stop-and-go” thoroughfare with bus and trucking routes. However, these effects did not imply higher risk of developing asthma. In fact, no environmental effect on the development of asthma was demonstrated. Re-analysis of the data did show one striking finding, though: obese children were more than twice as likely to develop asthma by age 7.
Another focus of the conference was on regulatory T cells, also called “Tregs.” These are the “traffic cops” of the immune system that act as brakes on inflammatory reactions. Since recent research has failed to show a correlation between a mother’s diet during pregnancy/ breastfeeding and the development of food allergy in her child (what the child is exposed to), researchers are shifting focus to other things that affect how the developing immune system responds to foods.
One hypothesis regarding the development of allergy is that the fundamental problem is a lack of appropriate Treg activity. Both Tregs and allergic-type T cells develop in the thymus, and the balance between the two can determine whether a person becomes allergic.
Mice allergic to egg protein can be given large amounts of egg without any reactivity if they are given infusions of Treg cells prior to an allergic challenge. Also, researchers have tried to stimulate mice to make higher levels of their own Tregs instead of infusing them.
One promising idea is the use of stem cells with allergy particles that come from our own body combined with the cell membrane. Peanut-allergic mice that were given “peanut-labeled” stem cells developed Tregs specific for the peanut protein and then tolerated peanut exposure without anaphylaxis. Furthermore, their levels of peanut-specific IgE (allergic antibody) seem to have been driven down significantly by the Tregs that they developed.
Preliminary research is being done on other things that affect levels of Tregs in a developing baby. Cigarette smoke, viral infections and certain pollutants can all affect the developing thymus. Interestingly, fatty acid and fiber content of the maternal diet may play a significant role in the allergic/Treg balance in the developing thymus. It is too early to recommend fish oil supplements to all pregnant or nursing moms, but the research is ongoing.