The Protective Effects Of Vitamin E Against UVA Induced Photodamage In Human Skin Fibroblasts

The natural ultraviolet A (UVA) in sunlight can lead to photoaging in human skin.After absorbing UVA, chromophores (e.g., porphyrin, melanin, methotrexate, flavin)within skin cells are undergoing complex biochemical reactions, thus produce reactiveoxygen species (ROS). ROS can cause serious damage to biological macromolecules,such as proteins, lipids and DNA. Cells that show the effect of oxidative stress canhighly induce the matrix metalloproteinases (MMPs) expression, which subsequentlycontribute to the degradation of collagen and elastin in extracellular matrix (i.e., losingelasticity and toughness in skin), and finally form photoaging. Under UVA irradiation,skin cells will produce oxidative stress, which caused damage effects in the balance ofoxidation and antioxidant systems in the body, it can induce the expression ofantioxidant enzymes such as heme oxygenase1(HO-1). It is the fact that HO-1in avariety of tissues or organs may protect cells from oxidative damage. Many researchershave attempted to reduce the oxidative damage and prevent skin photoaging byeliminating ROS with antioxidants. They also found that the HO-1could be induced toprotect cells with some antioxidants through Nrf2/ARE pathway. However, it is not yetclear that whether HO-1could make effect on UVA-induced MMPs to protect cells fromoxidative damage in human skin cells. Therefore, in this study, we first try to establish aUVA-induced oxidative damage model in human skin fibroblasts, then research theprotective effect of vitamin E on oxidative damage of skin after UVA irradiation. Wefurther study the effect of vitamin E on UVA induced MMPs and the interactionbetween HO-1and MMPs.The main methods used in this study are as follows: MTS assay for detecting cellproliferation, phalloidin staining for observing cell morphology, fluorescent probe DHEstaining for detecting intracellular ROS levels, western blotting for detecting Col I andHO-1protein expression, semi-quantitative RT-PCR for detecting MMP-1, MMP-2,MMP-3, Col I, Col III, HO-1gene transcription in FEK4cells.Results:①UVA irradiation causes dose-dependent oxidative damage in human skin FEK4cells.②V itamin Epretreatment can increase cells proliferation, reduce intracellular ROSlevels, maitain cells morphology, enhance Col I and Col III expression after UVAirradiation, decrease UVA-induced MMP-1, MMP-2and HO-1expression after UVA irradiation. On contrast, vitamin E pretreatment can also promote MMP-1expression atdose of10μM and25μM.Conclusion:Vitamin E can protect oxidative damage caused by UVA irradiation atphysiological dose of250kJ/m2in human skin FEK4cells. The protective mechanismsmay relate to increase cells proliferation, reduce intracellular ROS levels, maitain cellsmorphology, enhance Col I and Col III expression in cells after UVA irradiation,decrease UVA-induced MMP-1, MMP-2and HO-1expression in cells after UVAirradiation.