We now understand why some healthy people take a long time to recover from COVID -19 and flu.
This is the first study to illustrate how specific brain regions affect the body’s cellular immune response when infected with COVID-19 or influenza and under acute stress.
Acute stress causes neurons in the paraventricular hypothalamus to rapidly activate a large-scale migration of white blood cells (immune cells, or leukocytes) from lymph nodes to the circulation and bone marrow, according to the study.
This reduces the body’s immunological response to viruses like COVID-19 and influenza, making it less resistant to infection and increasing the risk of complications and death.
This important link between the brain and the immune system explains how stress impacts the body’s reaction to a virus, as well as why certain people are more prone to severe disease and worse results.
First, researchers examined the immune systems of groups of relaxed and stressed mouse models. When compared to the relaxed mouse group, mice undergoing acute stress revealed significant changes in their immune system within minutes.
Stress, in particular, caused a massive movement of immune cells across the body from one location to another. Researchers wanted to figure out what was going on.
Researchers used advanced techniques like optogenetics and chemogenetics to find that neurons in the paraventricular hypothalamus were telling immune cells to move from lymph nodes into the blood and bone marrow.
The researchers then looked at how mice in the relaxed and stressed models responded to influenza and COVID-19 infection.
They discovered that mice in the relaxed group performed better than mice in the stressed group in terms of fighting infection and getting rid of the virus.
Mice in the stressed group were sicker, had lower immunity, and died from the illness at a faster rate. The researchers also looked into how distinct types of immune cells moving from the bone marrow to the blood are controlled by other brain regions associated with motor function.
During acute stress in mice, different brain areas influence leukocyte distribution and activity throughout the body.
It’s crucial to understand how stress affects white blood cells and how that affects their ability to fight viruses in order to better understand outcomes and develop solutions to increase immunity.
White blood cells entering the bloodstream on a regular basis could have negative consequences for cardiovascular health.
This research shows how the brain regulates inflammation and how it is linked to a reduced immune response during times of stress.
The findings of this study could lead doctors to take a closer look at their patients’ mental health, particularly their sleep habits and stress levels.
It could lead to changes in how people live, so they can not only be healthier and less stressed, but also help their bodies fight infections better and have better outcomes.
“This work tells us that stress has a major impact on our immune system and its ability to fight infections. It raises many questions about how socioeconomic factors, lifestyle, and environments we inhabit control how our bodies can defend themselves against infection,” adds Dr. Filip Swirski, Director of the Cardiovascular Research Institute at the Icahn School of Medicine at Mount Sinai.
Image Credit: Getty
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