Skin Biomechanics and miRNA Expression Following Chronic UVB Irradiation.

Exposure to ultraviolet (UV) light from the sun is known to accelerate the skin aging process and leads to significant alterations in skin biomechanics; however, the molecular mechanisms by which chronic UVB affects biomechanical properties of the skin have not been well described. A murine model for chronic UVB exposure was used to examine changes in epidermal barrier function, skin biomechanics, and miRNA expression as a result of UVB. UVB irradiation caused skin to be weaker, less elastic, stiffer, and less pliable. Notably, these changes were not reversed after a 5-week period of recovery. Following UVB exposure, dermal collagen fibrils were significantly smaller in diameter and expression of the miR-34 family was significantly increased. To our knowledge, this is the first study to concurrently examine alterations in skin function, miRNA expression, and tissue biomechanics in response to chronic UVB exposure. The data suggest that UVB alters miR-34 family expression in skin, in addition to dysregulating collagen structure with subsequent reductions in strength and elasticity. miRNAs may play a pivotal role in regulating extracellular matrix deposition and skin biomechanics following chronic UVB exposure, and thus may be a possible target for therapeutic development. However, additional studies are needed to directly probe the link between UVB exposure, miRNA production, and skin biomechanics.