Mice treated with antibiotics or bred in a sterile environment develop more severe allergy and asthma, indicates a study published online this week in Nature Medicine. The findings support the ‘hygiene hypothesis’, which purports that certain bacteria can protect against the development of allergic disease.
Numerous epidemiological studies have identified associations between alterations of gut bacteria and increased risk of developing allergic airway diseases, such as asthma. However, the precise cell types and molecules responsible for these effects remain unclear.
David Artis and colleagues found that mice treated with a combination of five antibiotics or bred in germ-free conditions develop more severe allergic airway disease in response to allergens derived from house dust mites. The antibiotic treatments resulted in elevated blood concentrations of IgE antibodies related to allergy, and of basophils, immune cells that are activated in allergy. Beneficial bacteria in the gut signal to immune B cells to limit their secretion of IgE. When beneficial gut bacteria are altered with antibiotic-treatment, B cells release more IgE, which act on bone marrow basophil precursors and promote their development.
These findings disclose a previously unrecognized link between how deliberate alterations of bacterial communities in the gut can influence basophil development in the bone marrow and drive allergic disease.