J. Cosmet. Sci., 69, 175–185 (May/June 2018) 175 Understanding Solar Skin Elastosis–Cause and Treatment SABINE PAIN, NICOLAS BERTHÉLÉMY, CORINNE NAUDIN, VÉRONIQUE DEGRAVE, and VALÉRIE ANDRÉ-FREI, BASF Beauty Care Solutions, Lyon 69007, France (S.P., N.B., C.N., V.D., V.A.) Accepted for publication April 4, 2018. Synopsis Photoageing, also called actinic ageing, is the main cause of prematurely aged skin. Our expertise in elastic fi bers has led us to discover a process triggered in response to ultraviolet (UV) light and which upsets the balance of elastin fi bers: there is too much elastin and insuffi cient lysyl oxidase (LOXL1) enzyme to form functional elastic fi bers. This imbalance then leads to an accumulation of nonfunctional elastin, which forms aggregates. In addition to this imbalance, UV rays also induce elafi n synthesis by fi broblasts. Known to be a marker of elastotic aggregates, elafi n crystallizes the elastin fi bers and stimulates the formation of aggregates that cannot be naturally eliminated by the skin. We developed a Hamamelis virginiana leaf extract that was able to restore both the balance between elastin and LOXL1 and to decrease the elafi n synthesis to fi ght and correct the damage. This specifi c Hamamelis virginiana extract increased LOXL1 expression by twofold and decreased elafi n synthesis. As a consequence, elastic fi bers became functional and aggregates of unfunctional fi bers decreased. The specifi c Hamamelis extract activity was confi rmed in vivo with decreasing wrinkles and improving skin fi rmness. INTRODUCTION Cutaneous ageing involves two independent biological processes: chronological (intrin- sic) ageing and extrinsic ageing, the latter of which accelerates normal intrinsic ageing. Tobacco, environmental factors (cold temperature, pollution, and UV rays), mechanical factors, and nutritional factors cause extrinsic ageing (1). However, photoageing (induced by UV radiation) is the main cause of prematurely aged skin, also called actinic ageing. Photoageing principally concerns the exposed parts of the body. The visible effects of actinic ageing depend on the type of individual and are determined by the day-to-day exposure and protection from the sun. During actinic ageing, the epidermis is character- ized by an irregular thickness, either hyperplasic or atrophic (2). As the stratum corneum thickens (keratosic aspect), the superfi cial layers dehydrate. When melanocytes are ex- posed to the sun, their numbers decrease and they are not uniformly spread over the skin, resulting in irregular pigmentary spots. As a consequence, basal cells lose their protection leading to a possible cutaneous carcinoma. Moreover, the dermis is also largely affected by UV radiation. UV-induced ageing is characterized by a signifi cant alteration of conjunc- tive tissue at the collagen and elastic fi ber levels (3). Address all correspondence to Sabine Pain at sabine.pain@basf.com.