Gesundheit! Patrick Holt smothers allergies and asthma

Despite a flood of research on the topic, rates of allergy and allergy-induced asthma continue to climb in most industrialized nations. Holt, a professor at the Telethon Institute for Child Health Research in Perth, Australia, wants to reverse that trend. To accomplish this, he needs to know what triggers airborne allergy and asthma, starting at the moment babies draw their first breath. He's currently co-leading the first clinical trial to test a treatment that could prevent asthma in children who are genetically predisposed to the disease. The idea behind the treatment, consisting of daily drops of dust mite, cat, and grass antigen placed under the tongue, builds on his earlier studies showing that inhaled antigens can induce immunological tolerance (1), a process that involves regulatory T cells (2). Dendritic cells (DCs) in airways feature prominently in Holt's research. These potent antigen-presenting cells help determine whether responses to inhaled allergens will be dominated by Th1 or Th2 cells (3). But even before DCs get involved, a bevy of factors—genetics, pre-and postnatal antigen exposure , and nitric oxide levels, to name just a few— determine whether exposure will lead to tolerance or hyperreactivity. Holt has studied these factors and believes many of them can be overcome. The main obstacle in taming asthma, he says, is an outdated mind-set. Is it true that Australia has one of the highest rates of asthma in the world? It's true. Australia and New Zealand were on top for a long time, but now we've been joined by lots of European countries and the US, so we aren't as far in front as we used to be. Why has Australia remained high? Everyone has pet theories, but I think we're just an archetypal example of what has happened in the western world since World War II. Since the '60s, there has been a slow surge in the prevalence of allergic disease and allergic asthma in westernized countries. We see the same rise now happening in second world countries as they move into fi rst world economies. Are there any confounding factors in this trend? There isn't anything major; this is a real thing. We're talking about 35 years of research. When we look at pediatric records starting in the '70s, we can see changes occurring in succeeding birth cohorts so that each new generation of children has a progressively higher risk for allergic sensitization and subsequent asthma. …