Effect of trichloroethylene intake via drinking water on Th17 cells in BALB/c mice

Abstract

This study aimed to investigate the effect of trichloroethylene (TCE) intake via drinking water on Th17 cells in mice. Forty eight six weeks old female BALB/c mice were divided into blank control, vehicle control, 2.5 mg/ml TCE and 5.0 mg/ml TCE groups by random number table (12 mice each group), and exposed to TCE by drinking water. On the 14(th), 28(th), 56(th), 84(th) days, blood were collected and assayed for IL-17, IL-6, and TGF-β concentration in serum through ELISA. Animals were killed and spleen biopsies were taken sterility. The proportion of Th17 cells among CD4(+) T cells and RORγt mRNA expression level in spleen were measured by FCM and real-time PCR. In 2.5 mg/ml TCE and 5.0 mg/ml TCE group mice, Th17 cells/CD4(+) T cells in spleen were (3.46 ± 0.32)% and (5.45 ± 0.45)% on day 14, (3.47 ± 0.33)% and (4.10 ± 0.39)% on day 84, which were significantly higher than those for solvent control group at the same time point ((2.15 ± 0.20)%, (2.16 ± 0.35)%, respectively) (P < 0.01). RORγt mRNA expression levels were (1.870 ± 0.084) and (1.965 ± 0.060) on 14 day, (1.998 ± 0.079) and (2.028 ± 0.073) on day 56, which were also significantly higher than those for solvent control group at the same time point (1.77 ± 0.04 and 1.75 ± 0.09, respectively) (P < 0.05). IL-17 concentrations in serum were (32.28 ± 5.38) and (34.47 ± 5.02) pg/ml on day 14, and (34.87 ± 5.48) and (41.94 ± 6.19) pg/ml on day 28, which were significantly higher than those for solvent control group at the same time point((21.57 ± 5.23), (22.11 ± 5.11) pg/ml). IL-6 concentration in serum were (43.07 ± 6.71) and (47.86 ± 8.52) pg/ml on day14, (41.32 ± 7.04) and (46.74 ± 9.33) pg/ml on day 56, which were significantly higher than solvent control group at the same time point ((7.56 ± 7.71) and (28.26 ± 7.22) pg/ml). TGF-β concentration were (17.48 ± 3.06) and (18.93 ± 3.12) pg/ml on day 14, which did not show significant difference from solvent control group ((15.25 ± 2.95) pg/ml). Correlation analysis showed that IL-6 in serum were significantly positively correlated with the proportion of Th17 cells among CD4(+) T cells and RORγt expression level in spleen (r = 0.741, 0.765, P < 0.01). TCE might promote the differentiation of Th17 cells and increase IL-17 secretion by inducing IL-6 and up-regulating RORγt expression together with TGF-β.