Influence of aging on glycosaminoglycans and small leucine-rich proteoglycans production by skin fibroblasts

Skin aging is characterised by a progressive deterioration of its functional properties, linked to alterations of dermal connective tissue. Whereas many studies have been devoted to collagen alterations during aging, the situation is less clear concerning glycosaminoglycans and proteoglycans. Particularly, the alterations of the expression of small leucine-rich proteoglycans (SLRPs), a family of proteoglycans strongly implicated in cell regulation, have never been studied.In the present study we measured glycosaminoglycans and small leucine-rich proteoglycans synthesis by skin fibroblasts from donors of 1 month to 83 years old. [³H]-glucosamine and [³⁵S]-sulfate incorporation did not show significant differences of sulfated GAG synthesis during aging. On the other hand, a significant positive correlation was found between hyaluronan secretion and donor’s age. Northern blot analysis of SLRPs mRNAs showed a significant negative correlation of lumican mRNA with donor’s age, whereas decorin and biglycan mRNAs were not significantly altered. Immunohistochemical study and quantitative image analysis confirmed a decreased lumican accumulation in aged human skin.Taken together, our results suggest that impairment of glycosaminoglycans and SLRPs synthesis might be involved in the functional alterations of aged skin.