What do immune cells look like when they age and why do some immune systems grow more gray hair than others? When we talk through a mall, we can usually separate strangers by age through a variety of characteristics like gray hair and wrinkles. Sometimes, though, we marvel at how certain people seem to age so gracefully and retain their youthful features for much longer. Likewise, with our immune system we know that as people age, their immune systems fade somewhat, but some immune systems age better than others. What influences this aging and how do we measure it?
Researchers from the USC Leonard Davis School of Gerontology knew that changes in the immune system not only affect our risk of infections, but multiple other inflammation related diseases like heart disease and cancer. A better understanding of how aging affects the immune system could lead to interventions that lowered the risk of these late life diseases. With these factors in mind, they evaluated whether lifetime exposure to stress might affect the immune aging we see.
The researchers utilized a database of over 5000 adults who filled out a survey estimating the subject’s experience of various stress and looked at the health of their immune cells using a flow cytometry machine. The questionnaire survey addressed episodes of “stressful life events, chronic stress, everyday discrimination and lifetime discrimination.” The flow cytometry compared the number of fresh (“naïve”) groups of immune T cells versus “worn out” (“terminally differentiated”) T Cells. This was known to be a good measure of the immune system’s ability to respond to infections when more “naïve” T cells were present. Because the other factors like smoking, drinking, BMI, and race could affect outcomes, these factors were statistically accounted for.
So what did all this research effort and statistical work conclude? Various forms and timescales of stress did negatively impact these objectives measures of immune health. Let’s look at a few examples of what they found. Life trauma and chronic stress subjects demonstrated a lower percentage of CD4+ naïve cells. From another angle chronic stress and discrimination showed a greater percentage of CD4+ that were terminally differentiated. Life trauma, stressful life events, and lifetime experience of discrimination demonstrated a lower percentage CD8+ naïve cells. These and a few other findings indicated that these types of stress influence the ability of the immune system to respond to new infections. These influences continued despite factoring out CMV (cytomegalovirus) infections and of lifestyle factors like exercise although the effects were less.
One interesting, but secondary detail regards their mention that CMV, a common childhood viral infection, can reactivate under stressful conditions. In other clinical research, transplant surgeons are intensely aware of the possibility of a latent, hidden viral infection like CMV to reawaken and be life threatening in their organ transplant patients on immune suppression. This article acknowledges that even outside of the less common transplant situation, stressful events can allow CMV to age and disrupt the immune system.
In the final big picture, we have to recognize that stress impacts our health mostly negatively, but we can do some things that will alleviate the unavoidable stresses in our life. Exercise and healthy nutrition seem to lessen the impact of these stressors from this study. I would argue that other research supports the importance of healthy emotional/spiritual coping to limit the effects of stress. Having a variety of tools to deal with inevitable stresses is important. With those tools in place we can then work to address and limit the stressors themselves. Living a healthier more abundant life requires this approach.
Eric T. Klopack, Eileen M. Crimmins, Steve W. Cole, Teresa E. Seeman, Judith E. Carroll. Social stressors associated with age-related T lymphocyte percentages in older US adults: Evidence from the US Health and Retirement Study. Proceedings of the National Academy of Sciences, 2022; 119 (25) DOI: 10.1073/pnas.2202780119
Thanks to Science Daily:
University of Southern California. “Stress accelerates immune aging, study finds: Traumatic life events, discrimination prematurely weaken body’s mix of immune cells.” ScienceDaily. ScienceDaily, 13 June 2022. <www.sciencedaily.com/releases/2022/06/220613150648.htm>. Accessed June 15, 2202.
Sanctuary Functional Medicine, under the direction of Dr Eric Potter, IFMCP MD, provides functional medicine services to Nashville, Middle Tennessee and beyond. We frequently treat patients from Kentucky, Alabama, Mississippi, Georgia, Ohio, Indiana, and more... offering the hope of healthier more abundant lives to those with chronic illness.