H. pylori infection protects against allergic asthma
MedWire News: Infection with Helicobacter pylori seems to confer protection against the development of allergic asthma, a study in mice reveals.
The research, which appears in the Journal of Clinical Investigation, adds weight to the so-called "hygiene hypothesis," which postulates that the dramatic increase in allergic disease in developed countries is linked to the eradication of specific microorganisms that colonize the body.
Atopic asthma is nearing epidemic proportions in many industrialized nations and has been attributed to air pollution, smoking, the hygiene hypothesis, and widespread use of antibiotics.
In this study, Anne Müller (University of Zürich, Switzerland) and team used a mouse model to investigate the impact of infection with H. Pylori - a bacterial pathogen that persistently colonizes the human stomach - on subsequent airway inflammation and hyperresponsiveness.
The researchers infected wild-type mice with H. Pylori at either 6 days or 6 weeks of age, before experimentally inducing allergic airway disease using either ovalbumin or house dust mite allergen.
The study revealed that infected mice were efficiently protected from airway hyperresponsiveness, tissue inflammation, and goblet cell metaplasia - all hallmarks of asthma.
H. Pylori infection also prevented allergen-induced pulmonary and broncheoalveolar infiltration with eosinophils and CD4+ T helper cells. Importantly, the protection against asthma was most robust in mice infected in the neonatal period and was abrogated by antibiotic eradication of H. Pylori, notes the team.
In a second experiment, the researchers transferred regulatory T-cells from infected to uninfected mice. This caused the recipient mice to develop resistance to asthma, suggesting that the protection is mediated by these long-lived, inducible T-cells.
Taken together, these findings "provide experimental evidence for a beneficial effect of H. Pylori colonization on the development of allergen-induced asthma," say the authors.
They add: "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."
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By Joanna Lyford