Social stress accelerates aging of the immune system

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Los Angeles – Losing a job, marital crises or discrimination in everyday life can apparently 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 in the immune system in old age.

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

The competencies of the immune system decrease with increasing age. This immune senescence is reflected in an increased number of terminally differentiated “worn out” T cells that are no longer available to fight off pathogens or clear cancer cells.

At the same time, the pool of so-called naïve, i.e. “fresh” B and T cells that can respond to new challenges, decreases. Older people are therefore more susceptible to infectious diseases, which was recently shown in the corona pandemic. The rise in cancer and cardiovascular diseases has also been linked to immune senescence.

Physicians at the Leonard Davis School of Gerontology in Los Angeles have investigated the effects of social stress on immune senescence. For this purpose, the answers of 5,744 participants of 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. The participants are asked about their lifestyle and health every 2 years. Blood samples are also taken.

In a questionnaire, the participants were asked about stressful life events (e.g. job loss or robbery), chronic stress (e.g. financial problems or marital crises), discrimination in everyday life (lack of respect from others) or lifelong 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. A direct damage would be conceivable via the activation of hormonal stress reactions. Indirectly, social stress could lead to depression or health neglect.

As Eric Klopack and colleagues report, all 5 aspects had a negative effect on the immune system. Experiencing 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 were associated with a lower percentage of naïve CD8 cells and an increase in terminally differentiated CD8 cells.

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

Another factor that doesn’t seem to be related to social stress at first glance could be infections. A marker here was CMV seropositivity. CMV is one of the herpesviruses.

The infections are chronic, but they usually do not cause symptoms. Nevertheless, they are a challenge for the immune system, which must prevent reactivation. 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. In fact, part of the stress-induced immune senescence could be attributed to CMV seropositivity. A vaccination, which is currently not available, could therefore have a beneficial effect on immune senescence, Klopack believes. © rme / aerzteblatt.de

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