表没食子儿茶素没食子酸酯减轻UVB诱导的朗格汉斯细胞凋亡作用

目的 研究中波紫外线(UVB)对人表皮朗格汉斯细胞(LC)的光损伤作用以及绿茶活性成分表没食子儿茶素没食子酸酯(EGCG)的光保护作用。方法 采用密度梯度离心和免疫磁珠的方法分离纯化人表皮LC,将分离纯化的LC随机分为对照组、30 mJ/cm² UVB辐射组以及辐射后加用200μg/mL EGCG处理组,4h后以PI染色并经流式细胞仪检测细胞凋亡率。结果 30 mJ/cm² UVB辐射组的凋亡率明显高于对照组,EGCG干预组的凋亡率低于单纯UVB辐射组,但仍高于非照射对照组;且辐射后S期细胞数明显增加。几乎没有G₂/M期的细胞,EGCG处理辐射细胞后,S期细胞数减少。结论 UVB可诱导人表皮LC凋亡,而EGCG具有一定的保护作用。

Inhibitory effect of EGCG on apoptosis of Langerhans cells after UVB irradiation

Objective To observe the damage to Langerhans cells induced by UVB irradiation,and to evaluate photoprotective effect of these cells from UVB irradiation by epigallocatechin-3-gallate (EGCG).Methods Biopsy specimens were obtained from normal adult foreskin,and epidermal cells were isolated.Density gradient centrifugation and magnetic cell sorting were used simultaneously to purify Langerhans cells from the cell suspension.These cells were then divided into three groups,control (no irradiation or EGCG treatment),UVB (irradiation) and EGCG (irradiation+ECCG treatment) groups.The cells in the UVB and EGCG group were irradiated by UVB (30 mJ/cm²).After the irradiation,the UVB group was incubated with RPMI-1640 containing 10% bovine serum for 4 hours,while the EGCG group with the same medium containing 200μg/mL of EGCG for 4 hours.Another four hours after the treatment,the cells were collected for the detection of apoptosis rate by propidium iodide staining and flow cytometry.Results Exposure to UVB (30 mJ/cm²) significantly increased the apoptotic rate of Langerhans cells.The apoptotic rate in EGCG group was significantly lower than that in the UVB group,but was higher than that in the control group.Conclusion Rate of apoptosis of Langerhans cells could be increased by UVB irradiation,while EGCG could prevent the increase of apoptosis.