A Deeper Delve into the Mechanisms of Thymic Atrophy

The faltering quality of the immune system in later life is driven by several quite different factors, but the one that is perhaps most evident in the immune declines of middle age is the atrophy of the thymus. The thymus is a small organ located under the sternum and over the heart; it is where thymocytes produced in the bone marrow mature into T cells. As ever more of the active tissue of the thymus is replaced with fat, the ongoing supply of new T cells diminishes. The adaptive immune system becomes ever more a closed system and its cells become ever more dysfunctional: exhausted, senescent, misconfigured and overly focused on persistent viral infections such as cytomegalovirus, lacking the ability to respond to new threats. Thus older people have increased cancer risk, increased senescent cell burden, and reduced ability to defend themselves against infectious pathogens. This is why a number of research groups and biotech startups, including the company that I cofounded with Bill Cherman, Repair Biotechnologies, are working on ways to regenerate the thymus. Why does the thymus atrophy? There are at least two stages. Initially thymic involution takes place in early life. By the end of teenage years, the thymus is much reduced from childhood. This is a developmental program. Afterwards, however, different mechanisms take over: evidence strongly suggests chronic inflammation to play an important role in reducing the ability of thymic progenitor cells to sustain thymic...
Source: Fight Aging! - Category: Research Authors: Tags: Medicine, Biotech, Research Source Type: blogs