Scavenger receptor B1, a cutaneous sensor of pollution-induced oxidative damage

Scavenger receptor B1 (SR-B1) is a cell membrane receptor expressed in multiple tissues and exerts functions such as cholesterol and vitamins uptake, vesicles trafficking and pathogens recognition. SR-B1 is expressed also in human skin, especially in epidermis and sebaceous glands. Recent studies have shown the ability of environmental stressors (i.e. cigarette smoke, CS) to affect SR-B1 levels in cultured keratinocytes. Skin acts as a barrier against outdoor environment and its physical integrity together with its physiological composition are crucial to accomplish its functions. In this study we aimed to evaluate SR-B1 role in cutaneous barrier maintenance. We attested that SR-B1 redox susceptibility not only applies to 2D cultured cells, but also to wholly differentiated skin, by using 3D reconstructed epidermis. CS and other pollutants like ozone and particulate matter decreased SR-B1 levels within the tissue. We demonstrated SR-B1 implication in cutaneous integrity preservation; indeed, it appeared actively involved in skin wound healing, by regulating keratinocytes proliferation, migration and pro-migratory cytoskeleton rearrangement. By using SR-B1 knockdown organotypic skin model, we showed a striking change in lipids organization within the epidermal layers. Our findings suggest that SR-B1 loss upon external insults may influence cutaneous repair and lipid homeostasis.