On the Aging of the Kidneys
The longevity-associated gene klotho is known to act in kidney tissue, in ways that are protective of cell function in the aging environment of damage and inflammation. One of the conclusions that might be drawn from the extended life span produced by increased klotho expression in animal studies is that declining kidney function is an important aspect of aging. If the kidneys are not efficiently clearing waste from the bloodstream, and otherwise providing their contribution to bodily function, then all organs suffer as a result. Faster loss of kidney function means a faster decline into disease and mortality.
The renal condition is one of the crucial predictors of longevity; therefore, early diagnosis of any dysfunction plays an important role. The key role of the kidneys is to remove waste products from the blood and also regulate the levels of many essential compounds. Chronic kidney disease is one of the major causes of death worldwide, as well as a leading cause of years of life lost. Kidneys are highly susceptible to the aging process. Unfavorable conditions may lead to a significant disturbance of the body's homeostasis.
Despite the characteristic changes in the functioning and appearance of the kidneys being wholly assumed, the exact mechanisms of kidney senescence are still uncertain. It is challenging to distinguish between changes in the physiological aging of the kidneys and those in age-related kidney diseases and comorbidities. Apart from physiological changes, there are some conditions such as hypertension, diabetes, or obesity which contribute to the acceleration of the aging process. A determination of macroscopic and microscopic changes is essential for assessing the progression of aging. With age, we observe a decrease in the volume of renal parenchyma and an increase in adipose tissue in the renal sinuses. Senescence may also be manifested by the roughness of the kidney surface or simple renal cysts. The main microscopic changes are a thickening of the glomerular basement membrane, nephrosclerosis, an accumulation of extracellular matrix, and mesangial widening.
A vital factor that also should be taken into consideration in renal aging is oxidative stress mediated by SIRT1, PGC-1α, PPARα, and Klotho. Studies have shown that resveratrol or renin-angiotensin-aldosterone system blockers can be helpful to mitigate renal aging. Yet something that seems to be the most beneficial for renal function is simple habits such as appropriate diet and exercise.
A cursory review of this and other materials on the internet is telling me that most (perhaps all?) kidney disease is result of diabetes which, in turn, is at root a metabolic disorder. Again, its looking like its all in the mitochondria.