Gut microbiota and immune defenses
Balance in the microbiota – the collections of microorganisms (bacteria, yeasts, fungi, viruses) that live in the human body – essential for good health. To share microbiota knowledge, the Biocodex Microbiota Institute, an expert in research and distribution of advances in the field, regularly releases themed dossiers for health professionals on its website www.biocodexmicrobiotainstitute.com/en/pro.
The thematic paper titled Gut microbiota and immune defenses describes the latest advances on the link between gut flora and immune defenses. It sheds light on the current knowledge and outlooks and focuses on 3 key points: the involvement of the microbiota in the development of the immune system, its role in diseases with strong immunity and inflammatory components (T1DM, CIBD, among others), and the benefits of the modulation of commensal gut bacteria to prevent some infections.
GUT MICROBIOTA AND IMMUNITY: A DUO FORMED EARLY IN LIFE
The development and regulation of the immune system are conditioned by several factors such as the delivery mode and diet. We have recently discovered that the gut microbiota is an adjuvant that plays a significant role in these processes, from birth and throughout life.
Once the intestine’s epithelial barrier has been built, it is where bacteria and immunity interact. It ensures the proper coexistence of all components and serves as a barrier against aggressions towards the body. We could say that immune system and gut microbiota act on one another in a bidirectional way.
ON THE TRACK OF THE COMMON DENOMINATOR
When the inflammatory process is triggered, a disease occurs and persists. Type 1 diabetes mellitus (T1DM), chronic inflammatory bowel diseases (CIBD), graft-versus-host disease…: all these diseases could share common mechanisms such as increased gut permeability and disrupted immune homeostasis.
Alterations within the gut microbiota, induced by diet, hormones, etc. are involved. For instance, the thinning of the intestinal mucus layer observed in cases of CIBD makes possible the invasion of pathogens into the epithelium and triggers an immune reaction that leads to a state of chronic inflammation.
MODULATION OF THE MICROBIOTA: PREVENTING AND TREATING?
The respiratory microbiota is involved in numerous respiratory diseases, like pulmonary infections related to cystic fibrosis. In children, the evolution of the disease already correlates with variations in microbial populations in the respiratory tract. Researchers are attempting to identify therapeutic options by identifying the mechanisms at work.
A connection between the nasal microbiota and bronchiolitis in newborns has also been the subject of recent studies. Less invasive than nasopharyngeal aspiration, nasal swabs are a reliable marker of the severity of the disease and offer a promising potential alternative.
INTESTINAL MICROBIOTA AND DIGESTIVE DISEASES
This subject has been drawing the attention of researchers in the past few years because of the impact of the gut microbiota on the stimulation of innate and adaptative immune responses.
Encouraging results have been found in the treatment of several pathologies with fecal microbiota transplant (FMT), or the use of prebiotics, probiotics or synbiotics. As research progresses, treatment and/or prevention could be based on personalized medicine.
Patrice Debré is Professor Emeritus of Immunology at the Sorbonne University and member of the French National Academy of Medicine. He lends its expertise regarding the links between gut microbiota and immunity and claims that modulation of gut bacteria (or shaping) will become critical in the years to come.