Objective Intrinsic skin ageing is mainly caused by cellular senescence. p16 and p21 are two important tumour suppressor proteins that play essential roles during cell proliferation and ageing through regulating the expression of several genes. Moreover, physical changes between the ages of 55 and 60 years affect one's physical and disrupt self‐esteem. The cosmetics industry has focused on bioactive substances derived from natural products such as plants, mushrooms and marine algae to counteract the deleterious effect on skin senescence. Besides these products, compounds produced by bacteria may decelerate individual senescence. Methods In order to evaluate the potential benefits of bacteria extract over skin ageing, we investigated whether a Sphingomonas hydrophobicum (SH) extract is able to protect our skin against senescence mechanisms. We used an ageing full‐thickness skin equivalent model, which was treated or not with the bacteria extract in a systemic way for 42 days. p21 and p16 and senescence‐associated galactosidase activity were used to detect cellular senescence with immunohistology. Using a psychobiological approach, we evaluated in vivo the effect of SH extract on self‐esteem, isotropy and suppleness. Results Sphingomonas extract significantly suppressed senescence associated with β‐galactosidase activation. It also significantly inhibited the expression of cell cycle inhibitors (p21 and p16). At the same time, the bacteria extract has a significant positive impact on the issue by increasing the expression of versican and fibrillin‐1. Significant improvements of self‐esteem were reported after 56 days of SH extract application. These psychological benefits were accompanied by a significant improvement in skin suppleness and isotropy. Conclusion Sphingomonas extract delays intrinsic skin ageing process by inhibiting cellular senescence, and has also the capability to restructure the skin. These beneficial physiological effects induced by SH extract have a positive influence on self‐esteem. Because skin ageing causes emotional distress, SH extract can serve as an anti‐ageing cosmeceutical agent and help to build a better psychological health, and help individuals to assume ageing.

BackgroundBiomimetic membrane models tethered on solid supports are important tools for membrane protein biochemistry and biotechnology. The supported membrane systems described up to now are composed of a lipid bilayer tethered or not to a surface separating two compartments: a ”trans” side, one to a few nanometer thick, located between the supporting surface and the membrane; and a “cis” side, above the synthetic membrane, exposed to the bulk medium. We describe here a novel biomimetic design composed of a tethered bilayer membrane that is assembled over a surface derivatized with a specific intracellular protein marker. This multilayered biomimetic assembly exhibits the fundamental characteristics of an authentic biological membrane in creating a continuous yet fluid phospholipidic barrier between two distinct compartments: a “cis” side corresponding to the extracellular milieu and a “trans” side marked by a key cytosolic signaling protein, calmodulin.Methodology/Principal FindingsWe established and validated the experimental conditions to construct a multilayered structure consisting in a planar tethered bilayer assembled over a surface derivatized with calmodulin. We demonstrated the following: (i) the grafted calmodulin molecules (in trans side) were fully functional in binding and activating a calmodulin-dependent enzyme, the adenylate cyclase from Bordetella pertussis; and (ii) the assembled bilayer formed a continuous, protein-impermeable boundary that fully separated the underlying calmodulin (trans side) from the above medium (cis side).ConclusionsThe simplicity and robustness of the tethered bilayer structure described here should facilitate the elaboration of biomimetic membrane models incorporating membrane embedded proteins and key cytoplasmic constituents. Such biomimetic structures will also be an attractive tool to study translocation across biological membranes of proteins or other macromolecules.

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