As people age, their immune system naturally begins to decline. This aging of the immune system, called immunosenescence, may be a contributing factor to age-related health problems such as cancer and heart disease, as well as an important part of older people’s less effective responses to vaccines.
But not all immune systems age at the same rate. In our recently published study, my colleagues and I found that social stress is associated with accelerated immune system aging signs.
stress and immunity
To better understand why people with the same chronological age might have different immunological ages, my colleagues and I looked at data from the Health and Retirement Study, a study of American adults over the age of 50. Large, nationally representative survey. HRS researchers ask participants about different types. They have experienced stressful life events, including the loss of a job; discrimination, such as being treated unfairly or being denied care; Major lifelong trauma, such as a life-threatening illness to a family member; and chronic stress, such as financial stress.
Recently, HRS researchers have also begun collecting blood from a sample of participants to count the number of different types of immune cells present, including white blood cells. These cells play a central role in the immune response to viruses, bacteria, and other invaders. This is the first time such detailed information about immune cells has been collected in a large national survey.
By analyzing data from 5,744 HRS participants who provided blood and answered survey questions about stress, my research team and I found that those who experienced more stress had a lower proportion of “naive” T cells. tha – the fresh cells the immune system has not encountered before, needed to take on new invaders. They have a greater proportion of “late differentiated” T cells — older cells that have exhausted their ability to fight off invaders and instead produce proteins that can exacerbate harmful inflammation. People with a low proportion of new T cells and a high proportion of old T cells have a more aged immune system.
After controlling for poor diet and less exercise, however, the association between stress and accelerated immune aging was not as strong. This suggests that improving these health behaviors may help to address the dangers associated with stress.
Similarly, when we accounted for potential exposure to cytomegalovirus—a common, usually asymptomatic virus known to accelerate immune aging—the link between stress and immune cell aging was diminished. While CMV typically lies dormant in the body, researchers have found that stress can cause CMV to flare up and force the immune system to do more processing to control the reactivated virus. Continued infection control may use up the nave T cell supply and result in more depleted T cells that circulate throughout the body and cause chronic inflammation, a significant contributor to age-related disease.
understanding immune aging
Our study helps to elucidate the association between social stress and rapid immune ageing. It also highlights possible ways to slow immune aging, such as how people deal with stress and improve lifestyle behaviors such as diet, smoking and exercise. Developing effective cytomegalovirus vaccines may help reduce the aging of the immune system.
However, it is important to note that epidemiological studies cannot fully establish cause and effect. More research is needed to confirm whether stress reduction or lifestyle changes will improve immune aging, and to better understand how stress and latent pathogens such as cytomegalovirus cause disease and death. Huh. We are currently using additional data from the Health and Retirement Study to examine how these and other factors such as childhood adversity affect immune aging over time.
The younger the immune system is, the better able it is to fight off infection and generate protective immunity from vaccines. Immunosenescence may help explain why people are more likely to have more severe cases of COVID-19 and have a weaker response to vaccines as they age. Understanding what affects immune aging may help researchers better address age-related disparities in health and disease.