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31 - 10 - 2016

Unlocking the mysteries of the microbiota for better health care

In recent years, research on the intestinal flora or microbiota, has been multiplying. Gradually, we are discovering that the intestinal microbiota is important for the immunity, but also mental health or the metabolism. Here is an overview of the findings and their future therapeutic applications.      



Unlocking the mysteries of the microbiota for better health care
The intestinal microbiota is all bacteria, viruses, and fungi that colonize our digestive system, mainly the small intestine and colon. Far from being harmful, these microorganisms live in harmony with our body since our birth. But in addition to helping us digest certain nutrients, our microbiota plays a big role in our immunity, our metabolism and our mental health.   The microbiota-brain link under study Psychobiotics are probiotics (bacteria that enhance intestinal functions) and prebiotics (nutrients that promote the development and maintenance of the microbiota) that have an effect on the psyche, eg. mental health, the neural network, etc. Ongoing research in mice thus tend to show that the intestinal microbiota influences our moods, our emotions, our reaction to stress and even the way our neurons function, through communication with the brain via the vagus nerve, the bloodstream or the immune system. Mice deprived of their microbiota (known as germ-free mice) have, for example, a greater sensitivity to stress and depression. Research in rodents in this field could lead to new treatments against mental illness (depression, anxiety), neurodegenerative diseases (Alzheimer’s or Parkinson’s) or even autism.  The intestinal microbiota influences our immunity The gut microbiota plays a key role in immunity. Research into germ-free mice has shown that their offspring are less protected against pathogens and have a less effective immune system. Conversely, in mice equipped with a microbiota, the intestinal bacteria are passed on from mother to child via the placenta and breast milk after birth and promote the development of immunity. This could lead to new therapeutic applications, particularly in the management of children’s allergies. The microbiota is also hopeful in the field of immunotherapy against cancer. Indeed, it affects the response of the patient to immunotherapy. Currently, only 10 to 40% of patients are successfully treated. At the Curie Institute, researchers are looking to identify what type pf microbiota stimulates or inhibits the effect of immunotherapy in animal models of breast cancer. Finally, it is now clear that a poor or not very diversified microbiota increases the risk of metabolic diseases (obesity, type 2 diabetes). However, changing diet on the long term by adopting a more diversified diet has beneficial effects on the microbiota. These results were possible thanks to studies in mice (examples is the studies here and here). Hélène Bour  For more information :