The immune system is a very complex network of many different cell types, signals, and layered responses. It is much more subdivided and varied than the broad distinction between innate and adaptive immune components might lead one to believe. As a whole the immune system runs awry in later life, becoming both overly active and incompetent at the same time. Chronic inflammation and an inability to adequately defend against pathogens is the result. Many researchers are engaged in picking apart the details of this failure state, and the work here is a representative example of this sort of work, with a narrow focus on one smaller portion of the immune system and its responsibilities.
Chronic sub-clinical inflammation of aging, resulting from lifetime exposures to pathogens in concert with impaired immune responses, poses an obstinate challenge to the health span of the growing elderly population. Several factors contribute to the increased morbidity/mortality of older adults, including loss of naïve lymphocytes, exhaustion of adaptive immunity, and a skew toward proinflammatory responses. Additionally, loss of intestinal homeostasis and perturbations in epithelial barrier protective immune functions have recently emerged as key factors underlying chronic inflammation and age-related comorbidities.
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