Ageing: collagenase-mediated collagen fragmentation as a rejuvenation target.

We are honoured to provide this celebratory editorial marking the 125th anniversary of the British Journal of Dermatology. Human skin, like all organs, undergoes cumulative deleterious alterations that result in a decline of function due to the passage of time. However, unlike other organs, with the exception of the eye, skin experiences cumulative damage due to ultraviolet (UV) irradiation from the sun. Deleterious changes due to sun exposure are superimposed on natural ageing, giving rise to photoageing on sun-exposed skin. Photoageing and natural ageing can be viewed as variations on a theme, making them distinguishable by clinical, histological and molecular features. However, the underlying common theme, namely fragmentation of the dermal collagenous extracellular matrix and its impact on fibroblast function, justifies photoageing being considered a form of accelerated or premature ageing. During the last 30 years, largely owing to the ability to study the effects of acute exposure of human skin to solar-like UV, much progress has been made regarding the molecular basis of photoageing. Knowledge gained from the study of photoageing has greatly informed our understanding of natural ageing. While photoageing and natural ageing affect more than the dermis, alterations to collagen are among the most prominent and are likely the primary causes of the common appearance-related and clinical manifestations of aged skin. This editorial will therefore focus on the collagenous microenvironment as a target for damage during the ageing process and as a driving force for perpetuating both photoageing and natural ageing.