How Stress Impacts Body's Ability To Fight COVID-19, Other Infections

How does stress affect our body's ability to fight off infections, including COVID-19? A new study shows how certain brain regions affect the immune response to infections while under stress.

Stress is known to affect immune function, the researchers wrote in a study, published in Nature. However, the "mechanistic pathways linking stress networks in the brain to peripheral leukocytes remain poorly understood." Leukocyte is a type of blood cell that's a part of the immune system, helping the body fight infections.

For their work, the researchers first looked at the immune systems in groups of relaxed and stressed mice, the Mouth Sinai Hospital noted in a news release. The mice that were stressed quickly had changes in their immune system when compared to the relaxed ones, with the neurons in the brain region, called the paraventricular hypothalamus, triggering a migration of immune cells (leukocytes) from the lymph nodes to the blood and bone marrow.

They then looked at how the relaxed and stressed mice would fare when they were infected with COVID-19 and influenza. The research team found the relaxed mice fought the infection better and actually rid themselves of the virus "more easily."

In contrast, the stressed mice were sicker and had higher death rates. The "large-scale" migration of the immune cells that was triggered due to stress essentially "diminishes" the immune response against viruses, the hospital explained. Researchers also looked at the impact of other brain regions.

"These stress-induced, counter-directional, population-wide leukocyte shifts are associated with altered disease susceptibility," the researchers wrote. "Collectively, these data show that distinct brain regions differentially and rapidly tailor the leukocyte landscape during psychological stress, thus calibrating the immune system's capacity to respond to physical threats."

The work sheds light on the brain's connection to the immune system and why some people have worse outcomes than others, the hospital noted. It added that perhaps the mental state and stress levels of patients should also be on physicians' radars.

"This work tells us that stress has a major impact on our immune system and its ability to fight infections," one of the study authors, Dr. Filip Swirski of the Icahn School of Medicine at Mount Sinai, New York, said, noting the importance of studying the long-term effects of stress. "It will be particularly important to explore how we can build resilience to stress and whether resilience can diminish stress's negative effects on our immune systems."