UNDERSTANDING SOLAR SKIN ELASTOSIS 183 This antiwrinkle effect after 56 d of application of the emulsion containing Hamamelis at 1% is illustrated in the photographs in Figure 6. HAMAMELIS FIRMS THE SKIN OF THE FACE (DYNASKIN®) The depression created by airfl ow on the cheeks was measured to evaluate the fi rming effect of the emulsion containing Hamamelis at 1%. The volume and the depth param- eters of the deformation were measured. Compared with the placebo, after 84 d of treatment with Hamamelis at 1%, we observed a signifi cant reduction of the volume of the depression by 14.6% (p 0.05) and a signifi cant reduction of the maximal depth of the deformation by 9.5% (p 0.05) (Figure 7). This lower deformation of the skin created by the airfl ow, compared with the placebo, indicates a fi rming effect of Hamamelis at 1%. DISCUSSION Year after year, the slackness of the skin becomes more and more noticeable. The lack of elasticity of the skin is one of the major signs of ageing, whether it is caused by time or accelerated by exposure to the sun rays. With age and sun, the oxidative phenomenon leads to the densifi cation of the collagen fi ber network and to the degradation of elastin fi bers. The dermis gets thinner and the elastic fi bers split, which lead to a lack of skin elasticity. Wrinkles and fi ne lines appear. UV radiations increase the synthesis of metalloproteases, which degrade many compo- nents of the extracellular matrix, including collagen IV and VII and functional elastic fi bers. These phenomena involve leveling of the dermoepidermal junction and a signifi cant alteration of the conjunctive tissue. Elastin fi bers are in large numbers, thickened, and tangled. The fi bers stick together to form aggregates that are present throughout the dermis. We called this phenomenon as solar elastosis. In these conditions, elastin is badly Figure 7. Quantitative measurement of the volume of the depression and the maximal depth by Dynaskin® on the cheek. Emulsion with Hamamelis at 1% and emulsion with placebo. Mean percentage of evolution of volume of the depression and the maximal depth compared with the baseline (D0). Statistics versus placebo (Pl).

JOURNAL OF COSMETIC SCIENCE 184 reticulated by LOXL1. Indeed, we have shown that LOXL1 is downregulated under UV radiation. Moreover, LOXL1 has been shown to be degraded by skin elastases. Abnormal and nonfunctional fi brils appear. Furthermore, elafi n is a serine protease inhibitor that is mostly produced by epithelial cells. In the skin, keratinocytes are the main source of this molecule. Although elafi n is not detectable in normal skin, it is abundantly secreted in psoriasis and other infl amma- tory skin disorders (10). Elafi n acts in a varied way on the cutaneous immune homeosta- sis. Elafi n does not only exert an antiprotease effect but also an immunomodulatory and antiproliferative one (11). In solar elastosis, fi broblasts also express elafi n, which binds to elastin. The elafi n–elastin complex limits the elastolytic regular process, leading to the accumulation of disintegrated abnormal elastic fi bers and aggregates. The UV-induced elafi n prevents the proteases to degrade the abnormal fi bers (9). By inhibiting the synthe- sis of elafi n, our specifi c Hamamelis extract gives access back to proteases, to degrade the abnormal fi bers. Therefore, the specifi c Hamamelis extract acts at two levels: (i) it makes more functional elastin fi bers by increasing the elastin–cross-linked enzyme LOXL1 and (ii) prevents the formation of the nonfunctional elastin fi bers by inhibiting elafi n, the peptidase inhibitor. The in vitro results are confi rmed with the clinical data which show a decrease in wrinkles and an improvement in the fi rmness of the skin. CONCLUSION Complementarily to UV fi lters’ sun protection, we developed an active ingredient able to give the skin its own power to fi ght against the damage caused by the sun and to repair the already existing ones. Thanks to our knowledge on elastic fi bers, we discovered a process triggered in response to UV light, which upsets the balance of these fi bers: too much elastin and too little LOXL1 enzyme to assemble them into functional elastic fi bers. This imbalance leads to the accumulation of nonfunctional elastin, which groups together in aggregates and cannot be naturally removed. In addition to this imbalance, the fi bro- blast synthesizes elafi n, known to be a marker of elastotic aggregates. This protein crys- tallizes the elastin fi bers and emphasizes the formation of aggregates, which cannot be naturally eliminated by the skin. We have designed the fi rst active ingredient based on Hamamelis virginiana leaf extract (witch hazel) that corrects the damage caused by solar elastosis and that acts as a powerful shield against photoageing by acting on these two phenomena: the imbalance between LOXL1 and elastin, and the overexpression of elafi n. The active ingredient effi cacy is proven: lines are decreased and the skin recovers its fi rmness. REFERENCES (1) D. C. Calderone and N. A. Fenske, The clinical spectrum of actinic elastosis, J. Am. Acad. Dermatol., 32, 1016–1024 (1995). (2) M. J. Koehler, S. Zimmermann, S. Springer, P. Elsner, K. König, and M. Kaatz, Keratinocyte mor- phology of human skin evaluated by in vivo multiphoton laser tomography, Skin Res. Technol., 17, 17479–17486 (2011). (3) J. Uitto, The role of elastin and collagen in cutaneous ageing: intrinsic ageing versus photoexposure, J. Drugs Dermatol. 7, s12–s16 (2008).