Stress and aging of the immune system
Frequent stress accelerates the aging of the immune system
The concept of "stress" is quite multifaceted: there is cellular stress, there is psycho-emotional. But the body's response to any stress has common features, and any chronic stress is harmful to health, including the work of the immune system. Recently, scientists in a large sample confirmed the link between stress and immune aging and suggested ways to combat this harmful influence – although there is no sensation in them.
As we age, so does our immune system. Thus, the ratio of "worn out" (terminally differentiated) immune T-cells and young ("naive") cells that have not yet encountered pathogens is changing in the body. There are more of the former and fewer of the latter, which reduces our ability to cope with possible threats. Immune aging increases the risk of developing not only infections, but also cancer, cardiovascular diseases; even vaccines are less effective with age.
However, the rate of changes in the composition of immune cells in elderly people of the same age can vary greatly. To understand the reason for this phenomenon, scientists from the University of California at Los Angeles and the University of Southern California (USA) we studied the relationship between the activity of the immune system and the impact of such a negative factor as chronic stress.
It is known that frequent stressful situations throughout life increase the risk of developing "age-related" diseases and premature death. Most often, prolonged activation of the sympathoadrenal and hypothalamic-pituitary-adrenal systems is considered as the mechanisms of this effect. Such activation leads to the deterioration of the body at all levels of its organization. In cells, the number of DNA molecule damages increases, the length of telomeres – "protective caps" at the ends of chromosomes decreases, inflammatory processes increase. In other words, cellular aging accelerates.
In this case, scientists investigated the effects of various forms of social stress. To do this, they analyzed the answers to questionnaires of almost 6 thousand people over 50 years of age, participants in the study "Health and Retirement" of the University of Michigan (USA), and also examined their blood samples to assess the ratio of naive and terminally differentiated T-lymphocytes.
As expected, social stress was associated with accelerated immune aging. Maturation of T-lymphocytes occurs in the thymus (thymus gland) located in the upper part of the chest. With age, thymus tissue is replaced by adipose tissue, which leads to a decrease and eventually to an almost complete halt in the production of immune T cells.
It is known that thymus involution is accelerated by factors such as poor nutrition and a sedentary lifestyle. And when the researchers analyzed the data taking into account these parameters, the link between stress and immune aging was not so clear. People who experience stress usually tend to "jam" it and are not physically active enough – this behavior can largely explain their accelerated immune aging.
The recommendations of scientists – to monitor your diet and move more – may seem banal, but their effectiveness can hardly be disputed.
At the same time, scientists remind of another possible cause of rapid immune aging – cytomegalovirus infection. Like the herpes virus familiar to many, cytomegalovirus is a frequent "guest" in the human body, but it usually "sleeps", so the infection is asymptomatic. But in a situation of stress, the disease can worsen, and an active virus causes pathological changes in the immune system, contributing to its aging. And to reduce the effects of stress on the immune system, vaccination against this pathogen will be useful.
Article by Klopack et al. Social stressors associated with age-related T lymphocyte percentages in older US adults: Evidence from the US Health and Retirement Study is published in the journal Proceedings of the National Academy of Sciences.
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