Bacteria in fermented foods signal the human immune system, explaining the health benefits

Bacteria in fermented foods signal the human immune system, explaining the health benefits

We found that D-phenylactic acid is absorbed by fermented lactic acid bacteria (eg Sauerkraut) and induces HCA3-dependent migration in human monocytes. Future studies should examine how the activation of HCA3 by lactic acid-derived metabolites modulates immune function and energy storage. Credit: Claudia Stäubert

Researchers have discovered that humans and great apes have a receptor on their cells that detects metabolites from bacteria commonly found in fermented foods and triggers the movement of immune cells. Claudia Stäubert of the University of Leipzig and colleagues report these findings in a new study published on May 23 in PLOS genetics.

The consumption of lactic bacteria – the type that turns milk into yoghurt and cabbage into sauerkraut – can offer many health benefits, but scientists still do not understand, at the molecular level, why it is useful to ingest these bacteria and how this affects our system. Now, Stäubert and his colleagues have found a way in which the lactic acid bacteria interact with our bodies. Initially the researchers were studying the proteins on the surface of cells called hydroxy carboxylic acid receptors (HCA). Most animals have only two types of this receptor, but humans and great apes have three. The researchers found that a metabolite produced by the bacteria of lactic acid, the D-phenylactic acid, binds strongly to the third HCA receptor, signaling their presence to the immune system. The researchers suggest that the third HCA receptor arose in a common ancestor of humans and great apes and allowed them to consume foods that are beginning to decay, such as fruits harvested from the ground.

The study provides new information on the evolutionary dynamics between microbes and their human hosts and opens up new research directions to understand the multiple positive effects of fermented food consumption. "We believe that this receptor most likely mediates some beneficial and anti-inflammatory effects of lactic acid bacteria in humans," said author Claudia Stäubert. "This is why we believe it could serve as a potential target for drugs to treat inflammatory diseases."

Future studies could reveal the details of how D-phenylactic acid affects the immune system and whether the metabolite also affects fat cells, which also carry the third HCA receptor on their surface.

The small metabolites have great effects on the intestinal immune response

More information:
Peters A, Krumbholz P, Jäger E, Heintz-Buschart A, Çakir MV, Rothemund S, et al. (2019) The metabolites of lactic acid bacteria present in fermented foods are very potent agonists of the human hydroxy carboxylic acid receptor 3. PLoS Genet 15 (5): e1008145.

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Bacteria in fermented foods signal the human immune system, explaining the health benefits (2019, May 23)
recovered on May 23, 2019

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