Social stress accelerates the aging of the immune system

/ vectorfusionart,

Los Angeles – Job loss, marital crises, or discrimination in everyday life can seemingly leave their mark on the immune system. After a study in the Proceedings of the National Academy of Sciences (PNAS 2022; DOI: 10.1073 / pnas.2202780119), social stress accelerates the decline of the immune system in old age.

This was partly due to obesity and an unhealthy lifestyle. However, latent cytomegalovirus (CMV) infections could also play a role.

The powers of the immune system decrease with increasing age. This immune senescence is reflected in a greater number of terminal differentiated “consumed” T cells that are no longer available to fight pathogens or eliminate cancer cells.

At the same time, the pool of so-called naïve, ie “fresh” B and T lymphocytes that can respond to new challenges, decreases. Older people are therefore more susceptible to infectious diseases, as was recently shown in the corona pandemic. The rise in cancer and cardiovascular disease is also associated with immune senescence.

Doctors at the Leonard Davis School of Gerontology in Los Angeles studied the effects of social stress on immune senescence. To this end, the responses of 5,744 participants to the “Health and Retirement Study” in a questionnaire were compared with the results of a blood test.

The study accompanies a group of seniors to explore the effects of aging on health. Participants are asked about their lifestyle and health every 2 years. Blood samples are also taken.

In a questionnaire, participants were asked about stressful life events (e.g. job loss or robbery), chronic stress (e.g. financial problems or marital crisis), discrimination in everyday life (disrespect towards others ) or permanent disadvantages (disadvantage in working life) and life trauma (loss of a partner, drug problems in the family).

All of these experiences could directly or indirectly damage the immune system. Direct damage would be conceivable through the activation of hormonal stress reactions. Indirectly, social stress could lead to depression or neglect of health.

As Eric Klopack and colleagues report, all 5 aspects had a negative effect on the immune system. Experience of life trauma and chronic stress was associated with a lower percentage of naïve CD4 cells. Discrimination and chronic stress increased the proportion of terminally differentiated CD4 cells. Stressful life events, lifelong disadvantages, and life trauma have been associated with a lower percentage of naïve CD8 cells and an increase in terminal differentiated CD8 cells.

According to Klopack, part of the association was due to lifestyle factors such as obesity, smoking, alcohol consumption and low education. Social stress would therefore indirectly accelerate immune senescence.

Another factor that at first does not appear to be related to social stress could be infections. A marker here was CMV seropositivity. CMV is one of the herpesviruses.

Infections are chronic but usually cause no symptoms. However, they pose a challenge to the immune system, which must prevent it from reactivating. In the long run, this could lead to a weakening of the immune system, according to Klopack.

Stress can promote reactivation of CMV infection, as is known for other herpesviruses such as herpes labialis or chickenpox / zoster. Indeed, part of the stress-induced immune senescence could be attributed to CMV seropositivity. A vaccination, which is currently unavailable, could therefore have a beneficial effect on immune senescence, Klopack believes. © rme /

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