You’re more prone to bacterial infections when you’re stressed out, study shows

If there’s at least one thing we should all stop to do today, it’s taking a moment to destress. New research finds that when you (or your pet) get overwhelmed, stress hormones activate and make the body vulnerable to bacterial infections.

Stress hormones can leave a way for bacteria to infect cells by opting to bind with a bacterial protein called CheW rather than their usual receptors. Stress activates a group of chemicals in the brain, including epinephrine, norepinephrine, and dopamine. Prior work has shown a lower defense against bacterial infections when the body is under stress, but it remained unknown why this happened.

“We therefore suspected that some bacteria use such hormones as signals to recognize the eukaryotic host environment,” says Kirsten Jung, a professor of microbiology at Ludwig-Maximilians-Universität München in Germany and study in a university release

The team’s experiment focused on how bacteria recognized stress hormones and which receptors triggered the process to make the body susceptible to infection. They chemically modified epinephrine and phenylephrine so that they could later pull apart, allowing them to analyze how bacterial proteins were binding to the hormone receptors.

The bacteria under study is called Vibrio campbellii, and they chose it because it infects several marine animals including fish and squid. The bacterium was exposed to chemically modified stress hormones and then cells were cut to study the interactions inside the cell. The team isolated all bacterial proteins bound to a molecule. Protein analysis showed bacterial protein infected cells through a protein called CheW.

When the researchers isolated the CheW protein directly from bacteria, they made a startling discovery. The stress hormones did not bid to chemoreceptors as they usually do, but preferred to bind with the CheW protein.

“The biological significance of the mechanism is that bacteria recognize, for example, that they are no longer in sea water, but in the intestine of a host,” explains Dr. Jung. “Our study provides new insights into the communication of bacteria with their host.”

The study is published and available to read in PNAS.

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