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

Cập nhật lúc 11:25, Thứ ba, 10/11/2020 (GMT+7)

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

Consuming lactic acid bacteria that present in fermented milk (yogurt) and sauerkraut…, can offer many health benefits. The beneficial effects of lactic acid bacteria (LAB), permanently colonizing the human intestine or transiently obtained from food, have been extensively reported. However, scientists still don't understand, on a molecular level, why it is helpful to ingest these bacteria and how that affects our immune system.

Now, Stäubert and her colleagues have found one way that lactic acid bacteria interact with our bodies. Initially the researchers were investigating proteins on the surface of cells called hydroxycarboxylic acid (HCA) receptors. These receptors (HCA) are regulators of immune functions and energy homeostasis under changing metabolic and dietary conditions. Most animals have only two types of this receptor but humans and great apes have three in their genomes. Here, we used a combination of evolutionary, analytical and functional methods to unravel the role of HCA3 in vitro and in vivo. The functional studies included different pharmacological assays, analyses of human monocytes…

The researchers discovered that D-phenyllactic acid which has been a metabolite produced by lactic acid bacteria in fermented food, and the interaction of D-phenyllactic acid (D-PLA) with the human host through highly potent activation of HCA3. D-PLA have found in high concentrations in LAB-fermented food such as Sauerkraut, yogurt... We demonstrate that D-PLA from such alimentary sources is well absorbed from the human gut leading to high plasma and urine levels and triggers pertussis toxin-sensitive migration of primary human monocytes.

The study yields new insights into the evolutionary dynamics between microbes and their human hosts and opens new research directions for understanding the multiple positive effects of eating fermented foods

We are convinced that this receptor very likely mediates some beneficial and anti-inflammatory effects of lactic acid bacteria in humans, stated author Claudia Stäubert. That is why we believe it could serve as a potential drug target to treat inflammatory diseases."

Future studies may reveal the more details of how D- phenyllactic acid impacts the immune system through the third HCA receptor.