Harmful influences in the process of photoaging and skin damage are associated with infrared A (IRA) radiation, such as, disturbance of dermal extracellular matrix by up regulation of matrix metalloproteinase-1 (MMP1). Furthermore, DNA damage, induction of cytotoxicity and oxidative stress by decreasing natural antioxidant ability has been reported after acute exposure to IRA. The present study provides additional evidence that IRA radiation response in human skin fibroblasts produces deleterious effects to the cell, such as accelerating aging and weakening of their antioxidant defense mechanism. Human skin fibroblasts were exposed to a non-cytotoxic dose of IRA radiation and cultured for different periods for further collection of cell-free supernatants and lysates, and quantification of MMP-1, catalase, superoxide dismutase, and GADD45a. Our results corroborate previous published data and strongly indicate a negative impact of IRA radiation on the skin physiological by mechanisms involving reduced endogenous antioxidant enzymatic defense, increased MMP-1 and decreased repair process of DNA by reducing GADD45a protein, in cultured human fibroblasts. From a clinical perspective, IRA radiation acts by mechanisms distinct from those observed in ultraviolet radiation indicating the need for developing and making available cosmetics for skin care with properties beyond protection exerted by traditional sunscreens.
Keywords: Infrared A radiation, MMP-1, catalase, superoxide dismutase, GADD45a, reactive oxygen species (ROS).