Can the fats in the soil protect bacteria against stress?

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Researchers at the University of Colorado at Boulder (CU Boulder) led a study of Mycobacterium vaccae, an environmental bacterium that feeds on decaying organic matter. Previous studies on cells and laboratory animals have shown that M. vaccae can reduce inflammation and protect against stress.

However, as the authors explain in a recent psychopharmacology In their article, "the molecular mechanisms underlying the anti-inflammatory effects of M. vaccae are not known." In the new study, researchers "purified and identified a unique anti-inflammatory triglyceride" from the soil bacterium. They then synthesized and tested the "free fatty acid" version of the fat in mouse immune cells.

The researchers found that the fatty acid bound to a particular receptor, or signaling protein, in the cells. This event in turn blocked a number of molecular pathways inducing inflammation. The receptor name is peroxisome proliferator-activated receptor (PPAR).

Other experiments have revealed that treating immune cells with the fatty acid before stimulating them increased their resistance to inflammation.

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"We think," says Christopher Lowry, lead author of the study, badociate professor of integrative physiology at CU Boulder, "[that] there is a special sauce that causes the protective effects of this bacteria, and this fat is one of the main ingredients of this special sauce. " He says the discovery is "a huge step forward for us as it identifies an active component of the bacteria".[um] and the receiver for that active component in the host. "

According to Lowry, the interaction between anti-inflammatory fatty acids and immune cells is a product of the coevolution of humans and soil bacteria. Macrophages are immune cells that kill pathogens, such as bacteria, by consuming them. They play a central role in inflammation.

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According to Lowry, it seems that once the soil bacterium enters the immune cell, it releases the anti-inflammatory fatty acid. This then binds to the PPAR and closes the "inflammatory cascade". The results are further evidence that contact with soil bacteria is beneficial to human health in a different way than scientists have thought.

However, researchers such as Lowry and his team are redefining the hygiene hypothesis to add another aspect of the history of coevolution. Exposure to pathogenic bacteria can not only stimulate immunity but also a beneficial soil microbe that can actively improve health through direct molecular interaction with immune cells. In earlier work, Lowry has shown in several ways that exposure to useful bacteria appears to be beneficial to mental health.

One study, for example, showed that children who grow up on farms with animals have an immune system that is more resistant to stress and that they are also less likely to develop a mental illness than children who grow up in the city without pets. Another study showed that the injection of M. vaccae into rodents had a similar effect on antidepressant behavior. The treatment also appears to have a lasting anti-inflammatory effect on the brain.