Roles of T helper 17 and regulatory T cell infiltration in hepatic injury induced by arsenic in rats / 中华地方病学杂志

ABSTRACT

Objective 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.