Thymic health and ageing of the T cell system; impact of loss of kidney function

Loss of kidney function is associated with premature immunological aging involving loss of naïve T cells and expansion of pro-inflammatory memory T cells. The changes in the adaptive T cell system contribute to the uremia-related complications of increases susceptibility for infection, poor vaccination response and increased cardiovascular disease burden. Recently, it has become evident that the functional status of the thymus, called thymic health, may have a central role in key aspects of immunological aging such as loss of naïve T cells, expansion of oligoclonal memory T cells and a decrease in the T cell receptor diversity. The negative impact of poor thymic health on mortality, cardiovascular disease, and cancer incidence appears substantial. Although thymic function/health declines with increasing age, thymic function may still be present in the elderly, but variation is large and is, for instance, dependent on metabolic health, exercise, smoking and kidney function. Loss of kidney function leads to increased inflammation and oxidative stress which negatively impact thymic health that in turn can negatively affect decline of kidney function. The possible mechanisms involved in the latter feedback loop are decreased clearance of senescent kidney cells and an increase in symptomatic atherosclerotic disease. As such, the effects of progressing of chronic kidney disease on thymic function may explain the findings of premature immunological aging and offer new insights on the importance of this relationship and mechanisms involved.