[Role of the extracellular matrix in extrinsic skin aging]

Photoaged skin is clinically characterized by wrinkling, laxity and a leather-like appearance. These symptoms of actinic aging are causally connected to histological and ultrastructural changes of the connective tissue of the dermis. Changes include both enzymatic degradation and reduced de novo synthesis of collagen which cause premature wrinkling of the skin. Changes in the hyaluronan and proteoglycan matrix lead to reduced water content and thereby increased laxity of the skin. Furthermore, the UV-induced remodeling of the extracellular matrix strongly affects the cellular phenotypes such as the regenerative capacity of dermal fibroblasts. In recent years considerable progress has been made towards the understanding of molecular and cellular mechanisms underlying the UV-induced changes of the extracellular matrix. Current findings in this field reveal interesting insights in the dermal aging and provide new targets and strategies for the treatment of photoaging.