Offspring Treg/Th17 Imbalance Induced By Perinatal Exposed To BPA Associated With Expression Of Ahr

Backgroud Bisphenol A is widely used as industrial raw material in the world, and it is the structural basis for synthesis of epoxy resin and polycarbonate plastic, which have been widely used in food and beverage packaging, dental sealants and other plastic products. As an environmental endocrine disrupting chemical(EDC), BPA has a close relationship with estrogen receptor. Population can be exposed to BPA by eating, breathing and skin contact. Environmental exposure to low-dose BPA has an adverse toxic effect on the body, especially has a lasting impact on the immune system in perinatal exposure. Many researches indicated that transcription factor aryl hydrocarbon receptor(Ah R), activated by ligands, could mediate the toxicity of environmental pollutants and influence the balance between Th17 and Treg cells and their function by adjusting the differentiation of Th0 cells into Treg or Th17 cells, as well. However, the effects of perinatal BPA exposure on postnatal expression of Ahr and Treg/Th17 cell balance in offspring is not clear yet.Objective To investigate the mechanism of Ah R expression and Treg/Th17 balance in perinatal BPA exposure by analysing the correlation between the ratio of Treg/Th17, Foxp3/Rorγt, IL-10/IL-17 and Ahr expression level. And to provide basic research data for illustrating the developmental immunotoxicity of BPA.Methods 8-week-old female and 9-week-old male ICR mice were selected and fed in a SPF animal room and mated after 1 week, then vaginal plug was checked as the sign of pregnancy. The pregnant mice were randomly divided into 5 groups: blank control group, vehicle control group, 10, 100 and 1000 nmol/L BPA group, and were exposedto BPA by drinking water from gestational day 0(GD 0) to postnatal day 21(PND 21). Fetuses were sacrificed on PND 21. The level of IL-10 and IL-17 in serum were detected by ELISA, and the proportion of CD4+ IL17+ Th17 and CD4+ CD25+ Treg cells in spleen were measured by flow cytometry. Real-time PCR was conducted to detect the m RNA levels of Foxp3, Rorγt and Ahr in spleen. The protein level of Ah R was detected by western blotting. Experimental data was analyzed by SPSS 16.0.Results1 General situation During the whole experiment, pregnant mice and their offspring were generally in good condition, and no death or abortion was observed. As compared to the control group, there was no significant difference in maternal body weight, fetal body weight at birth and PND 21, and the number of fetuses per litter in BPA groups.2 Effects of perinatal maternal exposure to BPA on Treg and Th17 cells in offspring mice spleen by drinking waterIn fetuses on PND 21, the number of Treg cells was decreased with the increase of BPA dose, and the number of Th17 cells was increased. The ratio of Treg and Th17 cells was decreased with the increase of BPA exposure dose. Compared with the control group, the proportion of Treg/Th17 was decreased in 10 nmol/L BPA groups(P<0.05), and significantly decreased in 100 and 1 000 nmol/L BPA group(P<0.01).3 Effects of perinatal maternal exposure to BPA on the expression of Foxp3 and Rorγt m RNA in offspring mice by drinking waterIn fetuses on PND 21, the expression of Foxp3 was decreased with the increase of BPA exposure dose, and the expression of Rorγt was increased. The ratio of Foxp3 and Rorγt was decreased with the increase of BPA exposure dose. Compared with the control group, the proportion of Foxp3/Rorγt was significantly decreased in 10 nmol/L BPA groups(P<0.05), and more significant difference in 100 and 1 000 nmol/L BPA group(P<0.01).4 Effects of perinatal maternal exposure to BPA on IL-10 and IL-17 level in offspring mice by drinking waterIn fetuses on PND 21, the ratio of IL-10 and IL-17 was decreased with the increase of BPA exposure dose. Compared with the control group, the proportion of IL-10/IL-17 was decreased in 10 nmol/L BPA groups(P<0.05), and significantly decreased in 100 and 1 000 nmol/L BPA groups(P<0.01).5 Effects of perinatal maternal exposure to BPA on Ah R in offspring mice by drinking waterIn fetuses on PND 21, the expression of Ahr and the level of Ah R protein were increased with the increase of BPA exposure dose.6 Correlation analysis6.1 Correlation of the level of Ahr m RNA expression and the ratio of Treg/Th17A negative correlation was observed between the level of Ahr mRNA expression and the ratio of Treg/Th17(r=-0.870,P<0.01).6.2 Correlation of the level of Ahr m RNA expression and the ratio of Foxp3/RorγtA negative correlation was observed between the level of Ahr m RNA expression and the ratio of Foxp3/Rorγt(r=-0.815,P<0.01).6.3 Correlation of the level of Ahr mRNA expression and the ratio of IL-10/IL-17A negative correlation was observed between the level of Ahr m RNA expression and the ratio of IL-10/IL-17(r=-0.774,P<0.01).Conclusion1 There is no significant effect on the litter size, body weight of pregnant mice and offspring that exposure to BPA before PND 21.2 The ratio of Treg/Th17, Foxp3/Rorγt and IL-10/IL-17 were decreased with the increase of BPA exposure dose.3 The level of Ahr m RNA expression was increased with the increase of BPA exposuredose. Negative correlations were observed between the level and the ratio of Treg/Th17, Foxp3/ Rorγt and IL-10/IL-17. Perinatal exposure to BPA at a low dose can affect Treg/Th17 balance through regulating the expression of Ahr m RNA.