摘要目的 了解砷暴露后大鼠肝脏中辅助性T细胞-17(T helper 17,Thl7)、调节性T细胞(regulatory T cell,Treg)的浸润情况,探讨Th17与Treg细胞浸润在砷致大鼠肝脏免疫损伤中的作用.方法 选取健康初断乳Wistar大鼠32只,雌雄各半,按体质量(80 ～ 100 9)采用随机数字表法分为对照组,低、中、高砷剂量组,每组8只.对照组给予去离子水灌胃,染砷各组按体质量用2.00 g/L的亚砷酸钠(NaAsO2)水溶液进行灌胃,灌胃量依次为1.25、2.50、5.00 ml/kg,每周6d,染砷时间持续4个月.4个月后处死大鼠,取大鼠肝脏组织,采用电感耦合等离子体质谱仪(ICP-MS)检测肝砷含量;苏木精-伊红染色(HE)观察大鼠肝脏组织形态学变化情况;免疫组织化学方法检测肝脏组织白细胞介素(IL)-17A(Th17细胞分泌的炎性因子)、叉头翼状螺旋因子3(Foxp3,Treg细胞的谱系特异性转录因子)蛋白表达情况.结果 ①低、中、高砷剂量组肝砷含量[中位数(四分位数):63.83(52.79～ 80.26)、59.16(51.38 ～ 76.58)、79.26(69.59 ～ 107.44)μg/g]高于对照组[2.86(1.76 ～ 3.56)μg/g,P均＜ 0.05],且高砷剂量组高于中砷剂量组(P＜0.05).②随大鼠染砷剂量的增加,肝脏组织中炎细胞数增加,高砷剂量组大鼠肝脏组织呈现空泡样变,部分区域有点状坏死等病理改变.③与对照组,低、中砷剂量组比较(0.00l±0.001、0.010±0.020、0.030±0.080),高砷剂量组IL-17A蛋白在肝脏组织中的表达(0.220±0.130)均显著增高(P均＜0.05),组间比较差异有统计学意义(F=14.776,P＜0.05);低、中、高砷剂量组Foxp3蛋白表达量(0.270±0.050、0.330±0.040、0.320±0.070)高于对照组(0.070±0.020),组间比较差异有统计学意义(F=56.990,P＜0.05).④大鼠肝砷含量与肝脏组织中IL-17A、Foxp3蛋白表达呈正相关关系(r=0.48、0.81,P均＜0.05).结论 砷可致大鼠肝脏组织砷负荷含量增加,引发肝脏出现Thl7和Treg细胞浸润,机体免疫状态的改变,提示Thl7和Treg细胞在砷致免疫损伤的发生发展中起重要作用.

abstractsObjective To investigate the infiltration of T helper 17 (Th17) and regulatory T cells (Treg) in the liver of rats exposed to arsenic,and to investigate the roles of Th17 and Treg in infiltration of liver injury induced by arsenic.Methods Thirty-two Wistar rats,half male and half female,were randomly divided into control,low,medium and high arsenic dose groups by body weight via the random number table method,8 rats per group.Rats in control group were given oral garage of deionized water,while other groups were given oral gavage doses of 2.00 g/L sodium arsenite (NaAsO2) according to their body weight for 6 days every week,the concentrations of NaAsO2 were 1.25,2.50 and 5.00 ml/kg,respectively.After 4 months,liver tissue samples of rats were collected,the content of arsenic in liver was determined by inductively coupled plasma mass spectrometry (ICP-MS);Hematoxylin-eosin staining (HE) method was used to observe the morphological changes of liver tissue in rats;the protein expressions of interleukin-17A (IL-17A,the imflammatory factor secreted by Th17 cells) and Forkhead Box P3 (Foxp3,the lineage-specific transcription factor of Treg cells) were measured with immunohistochemistry.Results ① Arsenic content in liver of low,medium,and high arsenic exposed groups [63.83 (52.79-80.26),59.16 (51.38-76.58),79.26 (69.59-107.44) μg/g] were higher than those of the control group [2.86 (1.76-3.56)μg/g,P ＜ 0.05],and the high arsenic dose group was higher than the medium arsenic dose group (P ＜ 0.05).② With increasing doses of arsenic,the numbers of inflammatory cells in the liver tissue of rats were increased,and the liver tissue of the high arsenic dose group showed vacuolar degeneration and pathological changes in some areas.③ Compared with the control group,low and medium arsenic dose groups (0.001 + 0.001,0.010 ± 0.020,0.030 ± 0.080),the expression of IL-17A protein in the liver in high arsenic dose group were significantly increased (0.220 ± 0.130,P ＜ 0.05),the differences were statistically significant between groups (F =14.776,P ＜0.05).The expressions of Foxp3 protein in the liver in low,medium,and high arsenic dose groups were significantly higher (0.270 ± 0.050,0.330 ± 0.040,0.320 ± 0.070) than that in the control group (0.070 ± 0.020),the differences were statistically significant between groups (F =56.990,P ＜ 0.05).④ There was a positive correlation between hepatic arsenic levels and protein levels of IL-17A and Foxp3 in liver (r =0.48,0.81,P ＜ 0.05).Conclusion Arsenic exposure can increase the content of arsenic in liver tissue of rats,which causes the changes of infiltration of Th17 and Treg cells,leading to the change of immune status,suggesting that Thl7 and Treg cells play an important role in the development of arsenic-induced immune injury.