摘要目的 观察硫氧还蛋白还原酶(TrxR)1在燃煤污染型砷中毒病区砷暴露人群和大鼠血液和肝脏中的表达,探讨其在燃煤污染型砷中毒肝损伤中的作用.方法 ①人群研究:选择贵州省燃煤污染型砷中毒病区133例砷暴露者作为观察对象,依据临床检查和诊断结果分为病区非病人组(25例)、无明显肝病组(38例)、轻度(43例)和中重度肝病组(27例);以非砷污染村34名健康居民为对照组.采集上述观察对象的外周血,采用实时荧光定量PCR法检测TrxR1 mRNA表达,并用可见分光光度法检测TrxR酶活力.②动物实验:将30只体质量为80 ～ 100 g的Wiser大鼠,采用随机数字表法按体质量分为对照组、饮水型砷中毒组和低、中、高砷粮食污染组,共5组,每组6只.对照组常规喂养,饮水型砷中毒组饮用含10 mg/kg三氧化二砷(As2O3)的水溶液,低、中、高砷粮食污染组喂饲用病区高砷煤烘烤的玉米粉所配制的饲料(含砷量分别为25、50、100 mg/kg),均喂养3个月.采用实时荧光定量PCR法检测其外周血和肝组织中TrxR1 mRNA表达,免疫组织化学法检测肝组织TrxR1蛋白表达,可见分光光度法检测血清和肝组织中TrxR酶活力.结果 ①人群研究结果:病区非病人组、无明显肝病组、轻度和中重度肝病组外周血TrxR1 mRNA表达[中位数(四分位数)]分别为1.599 8(1.128 9～2.156 8)、1.469 3(1.146 1～1.976 3)、1.203 6(0.463 1～1.816 2)和0.912 3(0.631 8～1.535 0),轻度和中重度肝病组均低于对照组[1.649 7(1.161 1～2.380 2),P均＜0.05];血清TrxR酶活力分别为(3.12±0.76)、(2.81±0.84)、(2.52±0.73)、(2.42±0.76)kU/L,轻度和中重度肝病组均低于对照组[(3.02±0.70)kU/L,P均＜0.05].②动物实验结果:大鼠饮水型砷中毒组和低、中、高砷粮食污染组外周血TrxR1 mRNA表达分别为1.05±0.14、1.18±0.18、1.04±0.10、0.97±0.13,除低砷粮食污染组外,其余各染砷组均低于对照组(1.23±0.15,P均＜0.05);肝组织TrxR1 mRNA表达分别为0.78±0.10、0.83±0.10、0.79±0.09、0.77±0.11,除低砷粮食污染组外,其余各染砷组均低于对照组(0.94±0.12,P均＜0.05);肝组织TrxR1蛋白表达量分别为310.33±38.81、312.50±23.36、305.67±20.57、298.17±23.52,各染砷组均低于对照组(348.50±32.35,P均＜0.05);血清TrxR酶活力分别为(4.22±0.73)、(4.86±0.63)、(4.04±0.57)、(3.73±0.64)kU/L,各染砷组均低于对照组[(9.52±1.08)kU/L,P均＜0.05];肝组织TrxR酶活力分别为(14.82±1.67)、(18.76±2.76)、(14.90±2.17)、(11.55±1.74)U/mg,均低于对照组[(23.71±3.05)U/mg,P均＜0.05].结论 砷通过下调TrxR1转录表达和蛋白表达,降低其酶活力,加重燃煤污染型砷中毒肝损伤的发生发展.

abstractsObjective To study the expression and enzyme activity of thioredoxin reductase 1 (TrxR1) in liver and peripheral blood of human and rats exposed to airborne arsenic through coal-burning as well as its role in liver injury of coal-burning-borne arsenic poisoning.Methods This study was divided into 2 parts.Part 1 was a population study:133 local residents exposed to airborne arsenic through coal-burning were selected as arsenic exposure groups including a non-patient group (25 cases),no obvious hepatopathy group (38 cases),mild (43 cases) and moderate to severe hepatopathy groups (27 cases) from areas affected by endemic arsenism in Guizhou Province.Thirty-four healthy residents from arsenic not affected areas were selected as controls.Peripheral blood samples were collected from all these people.The expression of TrxR1 mRNA was determined by real-time fluorescence quantitative PCR (qPCR),and enzyme activity of TrxR was tested by visible spectrophotometry.Part 2 was an animal experiment study:Thirty Wistar rats,weighing about 80-100 g,were divided into control group,drinking-waterborne arsenic poisoning group and coal-burning-borne arsenic poisoning group (including low,medium and high arsenic contaminated grain groups) by means of a table of random number according to body mass,6 rats in each group.The control group was fed with normal diet for 3 months; drinking-water-borne arsenic poisoning group and coal-burning-borne arsenic poisoning group were fed with 10 mg/kg As2O3 solution and different concentrations(25,50,100 mg/kg) of arsenic-containing feed,respectively,for 3 months.The expression of TrxR1 mRNA was determined by qPCR; protein expression level of TrxR1 in liver tissue was detected by immunohistochemistry,and enzyme activity of TrxR in serum and liver tissue was tested by visible spectrophotometry.Results The mRNA expressions of TrxR1 in peripheral blood were 1.599 8 (1.128 9-2.156 8),1.469 3 (1.146 1-1.976 3),1.203 6 (0.463 1-1.816 2) and 0.912 3(0.631 8-1.535 0),respectively,among non-patient group,no obvious hepatopathy group,mild and moderate to severe hepatopathy groups.Compared to the control group[1.649 7(1.161 1-2.380 2)],the differences were significant statistically in mild and moderate to severe hepatopathy groups (all P ＜ 0.05).The enzyme activity of TrxR in peripheral blood was (3.12 ± 0.76),(2.81 ± 0.84),(2.52 ± 0.73),(2.42 ± 0.76)U/ml,respectively,in those corresponding groups.Compared to the control group [(3.02 ± 0.70)U/ml],the differences were significant statistically in mild and moderate to severe hepatopathy groups (all P ＜ 0.05).The mRNA expressions of TrxR1 in peripheral blood were 1.05 ± 0.14,1.18 ± 0.18,1.04 ± 0.10 and 0.97 ± 0.13,respectively,among drinking-water-borne arsenic poisoning group,low,medium and high arsenic contaminated grain groups; all of which were lower than that in the control group (1.23 ± 0.15,all P ＜ 0.05) except that of the low arsenic contaminated grain group.The mRNA expressions of TrxR1 in liver tissue were 0.78± 0.10,0.83 ± 0.10,0.79 ± 0.09 and 0.77 ± 0.11,respectively; all of which were lower than that in the control group (0.94 ± 0.12,all P ＜ 0.05).The protein expression of TrxR1 in liver tissue was 310.33 ± 38.81,312.50 ± 23.36,305.67 ± 20.57 and 298.17 ± 23.52,respectively,among the arsenic poisoning groups; all of which were lower than that in the control group (348.50 ± 32.35,all P ＜ 0.05).The enzyme activity of TrxR in serum was (4.22 ± 0.73),(4.86 ± 0.63),(4.04 ± 0.57),(3.73 ± 0.64)U/ml,respectively; all of which were lower than that in the control group [(9.52 ± 1.08)U/ml,all P ＜ 0.05].The enzyme activity of TrxR in liver tissue was (14.82 ± 1.67),(18.76 ± 2.76),(14.90 ± 2.17),(11.55 ± 1.74) U/mg,respectively; all of which were lower than that in the control group [(23.71 ± 3.05)U/mg,all P ＜ 0.05].Conclusion Arsenic aggravates liver injury of coal-burning arsenic poisoning through down-regulating the expressions of TrxR1 mRNA and protein and reducing its enzyme activity as well.