Scientists recently found out why various allergies arise in the first place. Your immune system overreacts, but why? Allergies in general are increasing around the world. It’s known that a specific birch pollen protein causes the immune system to overreact. What makes birch pollen an allergen has now been discovered by scientists at the Vetmeduni Vienna (University of Veterinary Medicine — Vienna). The pollen protein can bind iron. Without iron load the protein becomes an allergen. Environmental factors are possibly the reason for low iron loads in plants. This could explain the increasing numbers of certain types of allergies. The study’s findings, “Bet v 1 from Birch Pollen is a Lipocalin-like Protein acting as Allergen only when devoid of Iron by promoting Th2 lymphocytes,” recently were published in the Journal of Biological Chemistry.
The reason why many people are allergic to birch pollen has not been fully clarified yet
What makes birch pollen an allergen has now been discovered by scientists at the Vetmeduni Vienna, but not why people are allergic to birch pollen. The pollen protein can bind iron.
Without iron load the protein becomes an allergen. Environmental factors are possibly the reason for low iron loads in plants. This could explain the increasing numbers of allergies. What happened to the pollen’s iron load?
A single pollen protein is responsible for allergies
One of the most well known allergens, for example, substances that cause allergies, is so-called “Bet v 1” from birch pollen (Betula verrucosa). The protein was first produced artificially in the laboratory 25 years ago in Vienna, and is being used as an allergen model for research throughout the world. “Bet v 1” is the principal allergen among hundreds of other proteins of birch pollen. It renders the immune system hypersensitive and leads to the formation of disease-causing antibodies known as IgE immunoglobulins in 95 percent of persons with a pollen allergy.
Allergies in humans and animals are on the increase. An allergic reaction may cause unpleasant symptoms like hay fever, food intolerance or skin rashes. Allergic reactions may also cause acute and life-threatening symptoms, such as asthma or anaphylactic shock.
Birch pollen protein in its iron-loaded state is not allergenic
Until recently it was not known why harmless molecules trigger allergies at all. Scientist Franziska Roth-Walter and her colleagues from the Messerli Research Institute have now found the possible cause. The birch pollen protein “Bet v 1” is very similar to the human protein Lipocalin 2 in terms of structure. Lipocalin 2 is mainly present in the lung. Lipocalin 2, and “Bet v 1” possess so-called molecular pockets with which they can bind iron.
When these pockets remain empty, the birch pollen protein becomes an allergen and is liable to cause allergic reactions in humans and animals. The protein manipulates so-called T-helper 2 cells (Th2 cells), a certain type of immune cells, towards allergy. The human protein Lipocalin 2 also performs tasks of the immune system, depending on its iron loading.
Origin of allergy investigated in the model of birch pollen
In allergic people and other mammals, Th2 cells are predominant compared to Th1 cells. Th2 cells play an important role in allergic reactions and in combating parasites. Th1 cells serve to defend the body against bacterial and viral infections. “A typical feature of allergies is the disruption of the balance between the Th1 and Th2 immune response,” says Professor Erika Jensen-Jarolim, according to the June 5, 2014 news release, “Scientists discover the basis of allergic reactions.” Jensen-Jarolim is head of the Department of Comparative Medicine at the Messerli Research Institute.
“Investigations currently in progress indicate that we can directly transfer the principle of birch pollen allergens to other allergens with a similar molecular structure,” Jensein-Jarolim explains, according to the news release. “We are thus starting to understand – for the first time – why allergies to pollen, foodstuffs and fungal spores actually arise in the first place.”
Environmental factors determine the iron loading of the pollen protein
Scientists at the Messerli Research Institute, a combined facility of the Vetmeduni Vienna, the Meduni Vienna an der University of Vienna, (University of Veterinary Medicine — Vienna) are currently investigating the mechanisms that may contribute to reduced iron loading of “Bet v 1” in plants. “Iron loading of the birch protein may be connected to the aggravated environmental conditions acting on plants,” says Jensen-Jarolim. “In fact, there may be a direct connection between environmental pollution and rising allergy statistics. The most important conclusion from our work is that, in the future, it would make sense to specifically load allergenic molecules of the “Bet v 1” type with iron when they are used as allergy-specific immunotherapy in allergic patients. By doing so, this treatment – which currently takes two to four years – can be greatly shortened and its efficiency can thus be enhanced.”
Authors of the recent study are Franziska Roth-Walter, Cristina Gomez-Casado, Luis F. Pacios, Nadine Mothes-Lucksch, Georg A. Roth, Josef Singer, Araceli Diaz-Perales and Erika Jensen-Jarolim. You may wish to check out the study’s abstract, “Bet v 1 from Birch Pollen is a Lipocalin-like Protein acting as Allergen only when devoid of Iron by promoting Th2 lymphocytes,” recently published in the Journal of Biological Chemistry.