Plasma biomarkers of oxidative and AGE-mediated damage of proteins and glycosaminoglycans during healthy ageing: A possible association with ECM metabolism

The aim of this study was to examine whether oxidative and AGE-mediated processes correlates with the metabolic changes of proteoglycans (PGs) and proteins during physiological ageing. The age and gender-associated changes of PGs metabolism were evaluated by plasma chondroitin sulfates (CS), dermatan sulfates (DS) and heparan sulfates and heparin (HS/H). We found a linear age-related decline in CS, DS and HS/H, the first one being the predominant plasma GAG during ageing. The possible deleterious effect of oxidative phenomenon on proteins’ and proteoglycans’ metabolism during ageing process was analyzed by plasma carbonyls (PCO) and thiols (PSH) as well as by total antioxidant capacity (TAS). An age-dependent increase in PCO and decrease in PSH concentrations were found, both strongly correlated with decreasing with age plasma TAS. Intensity of glycation was assessed by circulating Nɛ-(carboxymethyl)lysine (CML) and endogenous secretory receptor for AGE (esRAGE), both of them founding associated with ageing. Moreover, all markers of oxidative and AGE-mediated damage correlated with CS and DS level and could be contributing factors to age-related changes of these GAG types. Thus, plasma CS and DS could become promising biomarkers of human ageing to date, owning to its close association with oxidative status and glycation processes.

► Plasma CS and DS closely related with oxidative and glycation processes represent promising biomarkers of ageing.
► Decreasing with age plasma TAS favors oxidative damage of these macromolecules.
► System of AGE and their receptors play important role in PG/GAG metabolism.