Fibrillin-rich microfibrils are reduced in photoaged skin. Distribution atthe dermal-epidermal junction

Chronic sun exposure results in photoaged skin with deep coarse wrinkles an d loss of elasticity. We have examined the distribution and abundance of fi brillin-rich microfibrils, key structural components of the elastic fiber n etwork, in photoaged and photoprotected skin. Punch biopsies taken from pho toaged forearm and from photoprotected hip and upper inner arm of 16 subjec ts with a clinical range of photoaging were examined for fibrillin-1 and fi brillin-2 expression and microfibril distribution. lit situ hybridization r evealed decreased fibrillin-1 mRNA but unchanged fibrillin-2 mRNA levels in severely photoaged forearm biopsies relative to photoprotected dermal site s. An immunohistochemical approach demonstrated that microfibrils at the de rmal-epidermal junction were significantly reduced in moderate to severely photoaged forearm skin. Confocal microscopy revealed that the papillary der mal microfibrillar network was truncated and depleted in photoaged skin. Th ese studies highlight that the fibrillin-rich microfibrillar network associ ated with the upper dermis undergo es extensive remodeling following solar irradiation. These changes may contribute to the clinical features of photo aging, such as wrinkle formation and loss of elasticity.