Distribution and expression of type VI collagen in photoaged skin

Summary Background Several of the characteristic clinical features of photoaged skin, including wrinkling,are thought to be dependent on changes in the dermal matrix brought about by chronic sunexposure. Such changes include reductions in collagens I, III and VII, an increase in elastoticmaterial in the reticular dermis and a marked reduction in the microfibrillar glycoprotein fibrillin.Objectives To examine whether type VI collagen, a microfibrillar collagen necessary for cell–celland cell–matrix communication, is affected by the photoageing process.Methods Six healthy volunteers with moderate to severe photoageing were enrolled into the study.Immunohistochemistry and in situ hybridization histochemistry were used to examine the levels oftype VI collagen in photoprotected and photoaged sites.Results In photoprotected skin, type VI collagen was concentrated in the papillary dermisimmediately below the dermal–epidermal junction, around blood vessels, hair follicles andglandular structures. The distribution of type VI collagen was unchanged in photoaged skin,although we observed an increase in the abundance of the a3 chain of collagen VI in the upperpapillary dermis, at its junction with the dermal–epidermal junction (P , 0·05). No alterationswere observed for any achain at the mRNA level.Conclusions These studies suggest that chronic sun exposure (photoageing) has little or no effecton either the distribution, abundance or levels of expression of type VI collagen in human skin.Thus, type VI collagen, unlike other matrix components so far studied, appears to be relativelyunaffected by the photoageing process.Key words: extracellular matrix, photoageing, type VI collagenType VI collagen is a major constituent of skin andmost other soft extracellular matrices.