Age-related changes in the proteoglycans of human skin

Skin undergoes dramatic age-related changes in its mechanical properties, i ncluding changes in tissue hydration and resiliency, Proteoglycans are macr omolecular conjugates of protein and carbohydrate (glycosaminoglycan) which are involved in these tissue properties. In order to examine whether age-r elated changes in skin proteoglycans may contribute to the age-related chan ges in the mechanical properties of skin, proteoglycans from human skin of various ages were extracted and analyzed, Samples were obtained from two di fferent fetal ages, from mature skin, and from senescent skin, As a functio n of age, there is a decrease in the proportion of large chondroitin sulfat e proteoglycans (versican) and a concomitant increase in the proportion of small dermatan sulfate proteoglycans (decorin), Based on reactivity with an tibodies to various chondroitin sulfate epitopes, fetal versican differs fr om the versican found in older skin with respect to the chondroitin sulfate chains. Also, the decorin of fetal skin is slightly larger, while the deco rin of older skin shows greater polydispersity in both its size and its cha rge to mass ratio. There are also age-related differences in the size and p olydispersity of the core proteins of decorin, The most pronounced change i n skin proteoglycans is the appearance in mature skin of a proteoglycan whi ch is smaller than decorin, but which has the same amino terminal amino aci d sequence as decorin, This small proteoglycan is abundant in mature skin a nd may be a catabolic fragment of decorin or an alternatively spliced form of decorin. In light of the known ability of decorin to influence collagen fibrillogenesis and fibril diameter, the appearance of this small decorin-r elated proteoglycan may have a significant effect on skin elasticity. The o bservation that proteoglycans in skin show dramatic age-related differences suggests that these changes may be involved in the age-related changes in the physical properties of skin. (C) 2000 Academic Press.