Biomarkes of aging.

Ageing is a complex process that negatively impacts the development of the different systems and its ability to function. On the other hand, the rate of ageing in humans is not uniform, due to genetic heterogeneity and the influence of environmental factors. Thus, the ageing rate, measured as the decline of functional capacity and stress resistance, seems to be different in every individual. Therefore, attempts have been made to analyse this individual age, the so-called biological age, in comparison to chronological age. Age-related changes in body function or composition that could serve as a measure of biological age and predict the onset of age-related diseases and/or residual lifetime are termed biomarkers of ageing. Such biomarkers of ageing should help on the one hand to characterise this biological age and, as age is a major risk factor in many degenerative diseases, could be subsequently used on the other hand to identify individuals at high risk of developing age-associated diseases or disabilities. Unfortunately, most of the markers under discussion are related to age-related diseases rather than to age, so none of these markers discussed in literature is a true biomarker of ageing. Hence, we discuss some disease-related biomarkers useful for a better understanding of ageing and the development of new strategies to counteract it, essential for improving the quality of life of the elderly population. Biomarkers discussed are based on immunosenescence, inflammatory responses and oxidative stress, since the review is based on data from author laboratories rather than on an extensive review of the literature. However, this kind of knowledge is useful to anti-ageing strategies aimed to slow ageing and to postpone death by preventing infectious diseases and delaying the onset of age-related diseases.