Scavenger receptor B1 as a new target for pollution-induced oxidative skin damage

Scavenger receptor B1 (SRB1), is a membrane receptor involved in several physiological functions including cholesterol and lipid soluble vitamins uptake, pathogens recognition and vesicles trafficking. Although this receptor is mainly localized in the liver and steroidogenic tissues, it has been shown to be expressed also in human skin. Recent studies have evidenced SRB1 susceptibility to oxidative stress and considering that cutaneous tissue is the main organ exposed to the outdoor stressors, it was our interest to understand whether the exposure of skin to environmental pollutants could affect its expression and consequently skin physiology. To answer our questions, we have performed experiments with homemade 3D skin models exposed to different pollutants: ozone, PM and cigarette smoke. Surprisingly all the stressors were able to down-regulate SRB1. In addition, the loss of SRB1 (after the challenges or by siRNA) prevented tissue wound closure and proliferation. Moreover, by the use of SR-B1 knockdown organotypic skin model, we showed a striking change in lipids organization within the epidermis. Our findings suggest that SR-B1 loss upon outdoor insults may influence cutaneous repair and lipid homeostasis making it as a key player in maintaining skin homeostasis.