Allergies: the role of microbiota
Balance in the microbiotas – the collections of microorganisms (bacteria, yeasts, fungi, viruses) that live in the human body – is essential for good health. The Biocodex Microbiota Institute, an expert in research and distribution of advances in the field, regularly releases themed dossiers on its website www.biocodexmicrobiotainstitute.com.
The themed dossier « Allergies: the role of microbiota » published at the end of May reports on the latest advances on the role of the microbiota on respiratory diseases. Recent scientific publications have added new data on the involvement of the various microbiota in asthma, food allergies (eggs, milk, peanuts, etc.), allergic rhinitis, and atopic dermatitis.
THE ONLY MICROBIOTA INVOLVED IN ASTHMA IS THAT OF THE BRONCHI AND LUNGS
FALSE. The nasal microbiota is also responsible for this respiratory disease. In effect, the microbes found there vary depending on whether the patient has asthma or not, as well as whether the disease is exacerbated or stable. This suggests that the nasal microbiota, from which samples are much more easily taken, less invasively than an exam of the inside of the bronchi, could be used to detect asthma, study its evolution, and potentially give rise to therapeutic solutions.
THE COMPOSITION OF BREAST MILK PLAYS A CRUCIAL ROLE IN THE OCCURENCE OF FOOD ALLERGIES IN CHILDREN
TRUE. Japanese researchers discovered that newborns who developed food allergies before the age of two have fewer lactic acid-producing bacteria than healthy newborns, starting at the age of two months. Researchers also detected notable differences in the volume of bacteria that assimilate lactate, which are underrepresented in children with allergies. According to other studies, these disparities come from the presence or absence of certain species in the breast milk, which themselves come from the mother’s intestinal microbiota.
SOME OF THE INTESTINAL BACTERIA AFFECT METABOLIC ACTIVITY IN EGG-ALLERGIC CHILDREN
TRUE. Egg allergies affect almost 10% of children with allergies under three. Recent studies have yielded information specifically on the connection between the early intestinal microbiota and egg allergies. The early intestinal microbiota in children with egg allergies is more diverse than that of healthy children. This is the opposite of what is often observed in other diseases, like obesity. Dedicated genetic analyses also led researchers to note that certain bacteria present in the intestinal microbiota of people with egg allergies change the metabolism of certain molecules. These discoveries that have already been made will open the door to preventive or therapeutic strategies for this widespread allergy.
HERE IS NO CONNECTION BETWEEN THE RESPIRATORY MICROBIOTA AND THE INTESTINAL MICROBIOTA IN ALLERGIC RHINITIS
FALSE. A strain of bacteria, Ruminococcus gnavus, that is responsible for a localized allergic reaction in the airways that causes allergic rhinitis, has also been found in abundance in the stool of children with allergies, compared to the proportion found in healthy children. It causes inflammation in the digestive tract. This unprecedented discovery sheds light on the major role of microbes in the lung-gut axis, and gives rise to ideas of targeted, effective treatments.
STAPHYLOCOCCUS AUREUS CAUSES ATOPIC DERMATITIS
TRUE. Recent analyses have shown that the bacteria was present on the skin of newborns with atopic dermatitis with lesions in more than 90% of cases (78% in cases of dermatitis without lesions, and 10% if the skin is healthy). The density of Staphylococcus aureus is clearly correlated to the severity of the disease. However, solutions exist, like emollients, already selected as a preventative treatment in newborns with atopic dermatitis. These treatments allow the cutaneous pH to return to normal.
EXPERT’S POINT OF VIEW
Professor Michel Gillet, a professor on the Faculty of Biology and Medicine at UNIL (University of Lausanne), is the head of the Department of Dermatology and Venereology at the CHUV (University Hospital Center of Vaud) in Switzerland. According to him, “a connection between imbalance in the cutaneous microbiota and atopic dermatitis is well established. Studies in newborns have furthermore shown that cutaneous dysbiosis can be very early and that it precedes the development of atopic dermatitis and respiratory allergies. Successful reestablishment of the microbial equilibrium very early in life has become the focus of interventions. In the space of a few years, recent technological advances have opened new research perspectives and options, as we have learned to identify bacterial subspecies and clarify the role of each. This is a particularly timely development, as the WHO predicts that one out of every two people will have one or more allergies by 2050. We have time to make great progress in the next 30 years!”