With its 100,000 billion bacteria, viruses and other microorganisms, the intestinal microbiota is not only essential for digestion. Although its activity is still poorly understood, it also plays a role in the immune system, growth and pathologies such as depression, diabetes or Crohn’s disease.
The role of the intestinal microbiota, often referred to as the second brain, is essential for infant growth in the event of malnutrition. This has already been shown by scientists from the Institute of Functional Genomics of Lyon (IGFL, CNRS-ENS of Lyon) in species such as Drosophila insects or mice. This same team, with researchers from other countries, showed that undernourished baby mice that ingested a strain of the bacterium every day Lactiplantibacillus plants saw their growth stimulated compared to the other animals which received a placebo. This work, coordinated by François Leulier, research director at IGFL, has been published in the review Science Thursday February 23.
The study was carried out with weaned pups, at the end of the twenty-one days during which they remained with the lactating mother. They are then placed on protein malnutrition, with daily protein intake reduced by 75% compared to the standard diet. Half of the mice ingest the bacteria, the other the placebo, for up to fifty-six days. At the end of the experiment, those who did not have the bacteria are 10% leaner and 3% to 4% smaller than the others.
How it works ? A strain of this bacterium, Lactiplantibacillus plants, is given orally and is thus found in excess in the small intestine. During its life in the intestine, it releases, among other things, a molecule, muramyldipeptide. Enterocytes (cells of the intestinal epithelium), located in the wall of the small intestine, absorb nutrients and also muramyldipeptide. “NOD2, a receptor present in cells of the intestinal epithelium in mice, will recognize this bacterial molecule and trigger cell signaling. This will cause the proliferation and maturation of the intestinal epithelium and ultimately stimulate the production of insulin and IGF-1., explains François Leulier. Produced primarily and respectively by the liver and pancreas, growth factor IGF-1 and insulin are fundamental molecules to support healthy youthful growth, by stimulating anabolic metabolism and bone growth.
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