It has been known for some time that chronic stress (such as that which many of us have experienced during the coronavirus emergency) may also have “physical” consequences on the body, triggering, for example, inflammation of the nervous system. This can be measured, by looking for the molecules that typically cause inflammation, like cytokine (which appears in greater quantities than normal) in the blood, and by measuring the activity of microglial cells, important elements of the brain’s immune defences. A ground-breaking study conducted by neuroscientists at Florida Atlantic University and Ohio State University has now made it possible to have a better understanding of the connection between stress and inflammation. It is the first to explain the crucial role played by a receptor found in our neurons, called nIL-1R, which interleukin 1 – a classic inflammatory molecule produced by the immune system – (literally) attaches to. The results of this study appeared in the journal Molecular Psychiatry (Nature Publishing Group).
nIL-1R receptors are found in particular in the neurons of one of the brain structures, the hippocampus, which is connected to memory and learning. According to the US researchers, it is the introduction of interleukin 1 to these exact cells that plays a central role in causing neuroinflammation, and associated disorders, including anxiety. If new studies confirm the role of this circuit, all of this could lead to the possibility of creating targeted therapies that are much more selective than those currently available to treat the consequences of chronic stress.
How did the researchers reach this conclusion? They deactivated, or actually “deleted” the nIL-1R receptors in laboratory animals, using complex genetic engineering techniques, and they saw that when they subjected the animals to a series of ad hoc stressful situations, they no longer caused inflammation in the neurons, or even the most classic consequences, such as memory loss and behavioural abnormalities. When, on the other hand, the nIL-1R receptors were restored, the effects of stress could be seen once again and were measurable.
According to the World Health Organization, one person in 13 suffers from anxiety, the most common mental disorder worldwide and which, as we said, can be connected to stress-related inflammation. “We are experiencing unprecedented levels of stress following the Covid-19 pandemic that will likely have long-lasting effects on millions of people”, said Randy Blakely, Executive Director of Florida Atlantic University’s Brain Institute, “When psychosocial stress becomes chronic, the effects are not just emotionally debilitating, they also are physically debilitating and can lead to high blood pressure, heart disease and even addictive behaviour. Findings from this cutting-edge study will assist scientists and clinicians to develop more tailored treatments and therapies for people who struggle with anxiety, depression and other psychological disorders.”