绿茶提取物对光老化、光免疫抑制的防护作用

Protective effect of green tea extracts on photoaging and photo-immunosuppression

目的探讨不同浓度的绿茶霜对光老化、光免疫抑制的防护作用。方法招募20名健康志愿者，在背部7个非曝光部位分别涂抹以不同浓度（2％～5％）的绿茶霜（保湿霜基质中添加不同浓度的绿茶提取物配制而成）或基质，并予1．5倍最小红斑量的模拟日光照射。免疫组化染色观察细胞角蛋白5／6、16含量及CD1a、HLA—DR阳性细胞密度。结果2％及3％的绿茶霜可有效地防护模拟日光照射引起的明显的红斑及色素沉着。模拟日光照射后CK5／6阳性＋强阳性比例在只照光部位达50％，在3％绿茶霜的部位仅达25％。CK16阳性＋强阳性比例在只照光部位达69％，在2％绿茶霜的部位仅达31％。与正常人对照相比，只照光部位表皮CD1a^＋或HLA—DR^＋的朗格汉斯细胞密度下降75％以上。一定浓度的绿茶霜可较好地抑制这种密度下降，其中3％绿茶霜的防护效果最佳。结论绿茶提取物可以有效地防护皮肤光老化、光免疫抑制。最适合的添加浓度为2％或3％.

Objective To investigate the protective effect of green tea-based cream at different concentrations on photoaging and photo-immunosuppression. Methods Twenty healthy female volunteers were enrolled into this study with informed consent. Green tea-based cream with a mass fraction of 2%-5% （prepared by adding green tea extracts to an emollient formulation）, excipient or green tea extracts alone were applied to six unexposed sites on the back of these volunteers. Thirty minutes later, these treated sites were subjected to solar-simulated ultraviolet irradiation （ssUVR） with a 1.5-fold minimal erythema dose once a day for 4 days. At 6, 24 and 48 hours after the last irradiation, green tea-based cream were applied repeatedly to the corresponding sites. Biopsy specimens were obtained from the seven sites 72 hours following the last irradiation, and immunohistochemical staining was performed to detect cytokeratin 5/6 and 16 expression, as well as the densities of CDlaor HLA-DR-positive cells. Results Green tea-based cream at a mass fraction of 2% to 3% could effectively prevent ssUVR-induced obvious erythema and hyperpigmentation. The positivity （＋） rates plus strong positivity （＋＋） rates reached 50% and 25% for CK5/6 in the sites treated with ssUVR only and those irradiated and protected with green tea cream at a mass fraction of 3%, respectively, 69% and 31% in the sites treated with ssUVR only and those irradiated and protected with green tea-based cream at a mass fraction of 2%, respectively. Compared with the control site without irradiation or protection, a decrease over 75% was noticed in the density of epidermal CDla- or HLA-DR- positive Langerhans cells in the irradiated sites without protection, and green tea-based cream, especially those at a mass fraction of 3%, could effectively inhibit the density decrease. Conclusion Green tea extracts could effectively protect skin from photoaging and photo-immunosuppression with the optimal mass fraction at 2% or 3%.