The human body is inhabited by billions of symbiotic bacteria, carrying a diversity that is unique to each individual. The microbiota is involved in many mechanisms, including digestion, vitamin synthesis and host defense. It is well established that a loss of bacterial symbionts promotes the development of allergies. Scientists at the Institut Pasteur have succeeded in explaining this phenomenon, and demonstrate how the microbiota acts on the balance of the immune system: the presence of microbes specifically blocks the immune cells responsible for triggering allergies. These results are published in Science on July 9, 2015.
Epidemiological studies have substantiated this hypothesis, by showing that children living in contact with farm animals - and therefore with more microbial agents - develop fewer allergies during their lifetime. Conversely, experimental studies have shown that administering antibiotics to mice within the first days of life results in a loss of microbiota, and subsequently, in an increased incidence in allergy.
These studies were funded by the French National Agency for Research, the French Medical Research Foundation, the Simone & Cino Del Duca Foundation, the European Commission and the "Integrative Biology of Emerging Infectious Diseases" Laboratory of Excellence.