Holobiont Rebalancing by a Natural Gentian Extract on a Skin Dehydration Model

Human skin homeostasis is partly maintained by a complex microscopic ecosystem known as the microbiota. Together, the skin host and microbiota form a synergistic evolutionary unit referred to as ‘skin holobiont’, which can be modulated by various stresses. By extracting organic wild yellow gentian roots enhanced through fermentation of a rare and resistant bacterium, Sphingomonas faeni, a cosmetic active ingredient was developed to rebalance the holobiont functions as well as hydric and lipidic skin content. Indeed, gentian-fermented extract (GFE) boosts hyaluronic acid (HA) biosynthesis in vitro, stimulates the HA receptor, CD44, and allows water storage and retention through its signaling cascade by epidermal reinforcement. Importantly, GFE also increases lipid synthesis by +147% in vitro, which was confirmed clinically on volunteers with dehydrated and dry skin who presented an increase in hydration and skin surface lipids after 28 days of treatment. Furthermore, a metaproteomic study highlighted that there is a slow-down of skin barrier and antioxidant proteins from both human and microbial origins, with age and dehydration, that can be reversed by GFE after 56 days. In conclusion, acting on the HA metabolism and specific microbiota species, GFE rebalances the skin holobiont for a reinforced and rehydrated skin with optimal lipid content.