Beta-carotene prevents ozone-induced proinflammatory markers in murine skin

Beta-carotene has been thought to protect against oxidative stress generated by ultraviolet radiation and thus prevents skin cancer and skin aging (Biesalski and Obermueller-Jevic, 2001). However, nothing is known about its potential effects against other environmental sources of oxidative stress such as ozone (O(3)) in skin. Intake of oral beta-carotene supplements before exposure to sunlight (and thus inevitably also to O(3)) has been recommended on a population-wide basis. However, although some studies have shown beta-carotene as providing skin protection as an antioxidant, other studies using skin cells in culture have shown that beta-carotene may have unexpected prooxidant properties (Obermuller-Jevic, et al., 2001). Given this, there is an ongoing debate regarding the protective or potentially harmful role(s) of beta-carotene in human skin. In this study, the effect of beta-carotene on ozone's effects on the skin of hairless mice was assessed. After feeding a diet supplemented with 0.5% beta-carotene for 1 month, mice were subjected to O(3) exposure (0.8 ppm 6 h/day; 7 days) and the induction of proinflammatory markers such as tumor necrosis factor-a (TNF alpha), macrophage inflammatory protein 2 (MIP2), and inducible nitric oxide synthase (iNOS), and markers of oxidative stress, heme-oxygenase-1 (HO-1), were quantitated. The data showed that beta-carotene downregulated the induction of TNFa, MIP2, iNOS, and HO-1 in response to O(3). We conclude that beta-carotene provides protection against O(3)-induced skin oxidative stress in vivo, which is consistent with a protective role for beta-carotene in the skin. Toxicology and Industrial Health 2009; 25: 241-247.