The elimination of a stomach ulcer bug from western society may be fuelling increasing rates of asthma and allergy, according to a European study.
Research on laboratory mice has found a direct link between the organism Helicobacter pylori and asthma caused by allergy.
The Swiss researchers say the link is so strong that the H.pylori germ may provide a way of "vaccinating" against allergic asthma.
In recent decades doctors have sought to eliminate H.pylori from the human body after discovering it was a prime cause of stomach ulcers.
The finding is linked to the so-called "hygiene" hypothesis – which argues that excessive cleanliness leaves the immune systems of human babies underdeveloped and unable to cope with allergens.
The study tested the impact of infecting mice with the bug a few days after birth. They found that these mice developed immune reactions to the bacteria – and showed minimal reactions to attempts to trigger asthma using common allergens.
The findings were reported in the Journal of Clinical Investigation.
They show that immune system T-cells could be transplanted between mice to provide allergy protection – but that eliminating H.pylori with antibiotics removed the asthma protection enjoyed by the animals.
Researcher Professor Anne Müller, of the University of Zurich, Switzerland, said that early infection triggered the creation of T-cells that play a key role in preventing asthma.
Fellow researcher Dr Christian Taube, of the Johannes Gutenberg University, Mainz, Germany, said: "The study of these fundamental mechanisms is extremely important for us to understand asthma and be able to develop preventative and therapeutic strategies later on."
* A second study in the same journal, from Stanford University, California, USA, links a component of the immune system called gamma-interferon to asthma – suggesting that high levels contribute to severity of disease.
Helicobacter pylori infection prevents allergic asthma in mouse models through the induction of regulatory T-cells. Isabelle C. Arnold, Nina Dehzad, Sebastian Reuter, Helen Martin, Burkhard Becher, Christian Taube, Anne Müller. Journal of Clinical Investigation, Vol. 121, Nr. 8, doi 10.1172/YCI45041
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