## 3 Results  
All the subjects but one (lost to follow-up) concluded the 42-day treatment period. Both products were very well tolerated. Clinical improvement in comparison with baseline was observed in 53% of subjects at day 14, in 79% at day 28, and in 84% at day 42 (Figure 1). An increase in sebum production is among the factors involved in the etiopathogenesis of acne. In this study, the sebum measurement is based on the internationally recognized Sebumeter(r) photometric method (Sebumeter 815, Courage + Khazaka GmbH). The Sebumeter(r) is a device that can directly measure the amount of lipids on the skin's surface. This system relies on a direct photometric reading of lipids collected on a probe that turns transparent in proportion to the content of skin lipids. The values are then automatically calculated into \(\mathrm{\SIUnitSymbolMicro g}\)sebum/cm\({}^{2}\) of the skin. Figure 2 illustrates the evolution of sebum content expressed in \(\mathrm{\SIUnitSymbolMicro g}\)/cm\({}^{2}\). Skin sebum production significantly (\(p\) < 0.05) reduced at each evaluation time point (\(-9.9\%\) at day 14, \(-19.4\%\) at day 28, and \(-23.7\%\) at day 42) in comparison with baseline, confirming a significant improvement of this parameter. Figure 1: VSIA pictures: (**a**) polarized light; (**b**) standard light, evaluated at baseline (T0) and after 14 (T14), 28 (T28), and 42 (T42) days. Skin radiance/skin brightness is the ability of the skin to reflect the light, and it is measured by using the spectrophotometer/colorimeter CM-700D (Konica-Minolta, Tokyo, Japan). The instrument emits diffuse light that reaches the skin, measuring the reflected light and calculating a parameter known as \"gloss\". A decrease in gloss parameter indicates a mattified effect, an improvement of the aesthetics of the face and its good cosmetic effect. As illustrated in Figure 3, the tested regimen was also able to significantly (\(p<0.05\)) decrease the gloss parameter (mattifying effect) at day 14, 28, and 42 with a maximum reduction of 7.2% at the end of the study period. No significant differences were observed at any checkpoints regarding skin profilometry analysis. Pores area measurement, evaluated by VISIA analysis, demonstrated a significant reduction at each checkpoint evaluation in comparison with baseline. At day 42, the pores area was 10% (\(p<0.001\)) lower than baseline value. Inflammatory and non-inflammatory lesions at baseline were 19 \(\pm\) 2 and were significantly reduced by 16% at day 28 and day 42 (\(p<0.01\)). Lipidomic analysis demonstrated that this cosmetic face care regimen induced significant and positive effects in face sebum lipids composition. In particular, at the end of the treatment period, a significant increase in different ceramides and a significant decrease in fatty acid (FA) and oxidized FA (OxFA) was observed. Ceramides' subclasses increased significantly (\(p=0.002\); Wilcoxon test) by 28% from baseline to day 42 (14 ng/cm\({}^{2}\) vs. 11.1), with a fold change of 1.7 \(\pm\) 0.6 in comparison with baseline. Figure 3: Evolution of gloss parameter (matt effect) (baseline, T0; days 14, 28, and 42). Data are expressed as mean \(\pm\) SE. The intragroup statistical analysis vs. T0  
Ceramides are members of the sphingolipid family. They represent the building blocks of epidermal barrier structure but are also bioactive metabolites involved in epidermal self-renewal and immune regulation. Ceramides constitute a hydrophilic extracellular lipid matrix, which is indispensable for permeability barrier function. In addition, ceramides also act as an active second messenger, regulate keratinocyte proliferation and differentiation, enhance proinflammatory cytokine production, and modulate immune responses [24]. In acne patients, altered ceramide levels have been observed; in particular, the levels of ceramides are reduced [15]. In this study, as we can see from Figure 4, the quantity of ceramides compared to T0 is increased. OxFA sebum content was significantly reduced by 65% (\(p\) = 0.023).