The stomach bug that stops asthma in mice

Researchers at the University of Zürich infected newborn mice with the bacterium and then exposed the animals to the kind of allergens that normally trigger asthma attacks.

The infected mice developed far less allergic airway inflammation than uninfected mice given the same allergens. Depleting their regulatory T cells erased the protection entirely, and transferring those same T cells into uninfected mice passed the protection along with them, pointing to those immune cells as the route of protection.

The protection was strongest when mice were infected as newborns rather than as adults, which matches a pattern seen in people: places where H. pylori infection is common in childhood tend to have lower rates of asthma. Nobody is suggesting a deliberate infection as treatment, since H. pylori also raises the risk of ulcers and stomach cancer, but the mouse data pointed research toward the immune pathway instead.

Old germ, new theory for asthma.