Cataloging Sex Differences in the Aging of the Human Immune System
Humans, and most other mammals, exhibit a common set of differences between males and females in the trajectory of aging and age-related disease. Females live longer, but with greater disability, for example. Dive deeper to look at the fine details of specific tissues and biological systems, and the list of differences expands. Researchers here report on their assessment of differences between men and women in the aging of the immune system, for example. While interesting, it isn't clear that differences in the progression of aging will be all that important in a future of effective rejuvenation therapies. It is certainly possible that any given narrow approach to rejuvenation that targets just one mechanism of aging will prove to be more or less effective to some degree in men versus women, but a package of approaches that produces comprehensive rejuvenation, addressing all of the causes of aging, should make the whole question of sex differences in aging moot.
Statistics show clear differences in the population's immune system according to sex: men are more susceptible to infections and cancers, while women have stronger immune responses, which translate, for example, into better responses to vaccines. Even so, with a more reactive immune system, the probability of the body attacking itself also increases, causing 80% of autoimmune disease development to occur in women. A new study has demonstrate that immunological aging follows different dynamics between men and women, identifying the cells and genes responsible for the process, and providing a molecular explanation for the differences that previously were only observed globally in the population.
The results reveal that women present more pronounced changes in the immune system with age, with an increase in inflammatory immune cells. This finding could help explain why autoimmune diseases are mainly developed by women, especially at advanced ages, as well as the worsening of certain inflammatory pathologies after menopause. On the other hand, the changes associated with immune system aging observed in men are globally less extensive, but an increase in certain blood cells presenting pre-leukemia alterations was observed, a fact that could explain why some blood cancers are more frequent in older men.
Finding these patterns was possible thanks to the analysis of blood samples from nearly 1,000 people of different ages covering the entire adult life, combined with a technology capable of analyzing each cell individually, called single-cell RNA sequencing. In total, the researchers analyzed the activity of 20,000 genes in more than one million blood cells, which allowed them to identify how the immune system changes over the years and detect clear differences between sexes.