Possible role of infrared or heat in sun-induced changes of dermis of human skin in vivo

摘要

The signs of photoaging in human skin have been attributed almost exclusively to the ultraviolet radiation (UVR) which represents just 6.8% of solar radiation, compared to the infrared and visible radiation which account for 54.3% and 38.9%, respectively, of the incident solar energy [1]. Little is known about the biologic effects of non-UVR components of solar radiation on human skin. Recent studies suggest that infrared radiation induces extracellular matrix (ECM) changes including increased matrix metalloproteinases and decreased procollagen expression [2,3], which manifest over time as wrinkles [4]. Additionally, increased skin temperature by infrared radiation [5] as well as heat alone [2,6,7] can cause ECM changes similar to UVR.