Green tea polyphenol (-)-epigallocatechin-3-gallate treatment to mouse skin prevents UVB-induced infiltration of leukocytes, depletion of antigen-presenting cells, and oxidative stress

Ultraviolet (UV) radiation-induced infiltrating leukocytes, depletion of an tigen-presenting cells, and oxidative stress in the skin play an important role in the induction of immune suppression and photocarcinogenesis. Earlie r we have shown that topical application of polyphenols from green tea or i ts major chemopreventive constituent (-)-epigallocatechin-3-gallate (EGCG) prevents W-B-induced immunosuppression in mice, To define the mechanism of prevention, we found that topical application of EGCG (3 mg/mouse/3 cm(2) o f skin area) to C3H/HeN mice before a single dose of UV-B (90 mJ/cm(2)) exp osure inhibited UV-B-induced infiltration of leukocytes, specifically the C D11b+ cell type, and myeloperoxidase activity, a marker of tissue infiltrat ion of leukocytes, EGCG treatment was also found to prevent UV-B-induced de pletion in the number of antigen-presenting cells when immunohistochemicall y detected as class II MHC+ Ia+ cells. UV-B-induced infiltrating cell produ ction of H2O2 and nitric oxide (NO) was determined as a marker of oxidative stress. We found that pretreatment of EGCG decreased the number of UV-B-in duced increases in H2O2-producing cells and inducible nitric oxide synthase -expressing cells and the production of H2O2 and NO in both epidermis and d ermis at a UV-B-irradiated site. Together, these data suggest that preventi on of UV-B-induced infiltrating leukocytes, antigen-presenting cells, and o xidative stress by EGCG treatment of mouse skin may be associated with the prevention of UV-B-induced immunosuppression and photocarcinogenesis.