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

Abstract

Ultraviolet (UV) radiation-induced infiltrating leukocytes, depletionof antigen-presenting cells, and oxidative stress in the skin play animportant role in the induction of immune suppression andphotocarcinogenesis. Earlier we have shown that topical application ofpolyphenols from green tea or its major chemopreventive constituent(−)-epigallocatechin-3-gallate (EGCG) prevents UV-B-inducedimmunosuppression in mice. To define the mechanism of prevention, wefound that topical application of EGCG (3 mg/mouse/3 cm2 ofskin area) to C3H/HeN mice before a single dose of UV-B (90mJ/cm2) exposure inhibited UV-B-induced infiltration ofleukocytes, specifically the CD11b+ cell type, and myeloperoxidaseactivity, a marker of tissue infiltration of leukocytes. EGCG treatmentwas also found to prevent UV-B-induced depletion in the number ofantigen-presenting cells when immunohistochemically detected as classII MHC+ Ia+ cells. UV-B-induced infiltrating cell production of H2O2 and nitric oxide (NO) was determined as amarker of oxidative stress. We found that pretreatment of EGCGdecreased the number of UV-B-induced increases inH2O2-producing cells and inducible nitric oxidesynthase-expressing cells and the production of H2O2 and NO in both epidermis and dermis at aUV-B-irradiated site. Together, these data suggest that prevention of UV-B-induced infiltrating leukocytes, antigen-presenting cells, andoxidative stress by EGCG treatment of mouse skin may be associated withthe prevention of UV-B-induced immunosuppression andphotocarcinogenesis.