Study On The Change Of Maternal-fetal Bile Acid Levels And The Placental Expression Of BSEP, AE2 In Intrahepatic Cholestasis Of Pregnacy

Object To explore the placental expression of AE2,BSEP along with pregnancy and in intrahepatic cholestasis of pregnancy (ICP), as well as their relationships with bile acid levels in maternal and umbilical venous serum. To evaluate the role of placental bile salt transporters in pathological mechanism of ICP.Methods Total bile acid (TBA) and nine bile acids levels in maternal and umbilical venous serum were measured by velocimetry and HPLC-MS/MS respectively in 20 gravidas complicated with ICP (ICP group) and 20 normal gravidas (control group) of late pregnancy. The placental BSEP and AE2 mRNA expression of 8 early pregnancy, 7 middle pregnancy and two above groups were tested by real time RT-PCR.The locatization of AE2 in placenta was analyzed by immunohistochemistry.Results (1) Both maternal and umbilical cord serum TBA levels in ICP group were significantly higher than those in control group (46.15±62.82 VS 2.82±1.82μmol/L; 18.23±16.77μmol/L VS 4.79±1.26, P＜0.05). Maternal serum TBA level was significantly higher than that of umbilical serum in ICP group (46.15±62.82 VS 18.23±16.77μmol/L, P＜0.05), and significantly lower than that of umbilical serum in control group (4.79±1.26 VS 2.82±1.82μmol/L, P＜0.05). (2) Matemal serum TCA,CA,TDCA,GCA,GCDCA,TCDCA levels were significantly higher in ICP group than those in control group(P＜0.05), DCA was significantly lower in ICP group than that in control group(P＜0.05); umbilical serum TCA,CA,TDCA,GCA,GCDCA,LCA levels were significantly higher in ICP group than those in control group(P＜0.05); maternal serum TCA,DCA,TDCA,TCDCA,GCA levels were significantly higher than those in umbilical serum of ICP group(P＜0.05);maternal serum DCA,TDCA,LCA levels were significantly higher than those in umbilical cord serum of control group(P＜0.05), TCDCA was significantly lower in maternal serum than that in umbilical serum of control group(P＜0.05). There were significant positive correlations between nine bile acid levels of maternal serum and those of umbilical serum in ICP group(r=0.478～0.952, P＜0.05), as well as positive correlations between GCA,DCA,LCA levels of maternal serum and those of umbilical serum in control group(r=0.585,0.764,0.595, P＜0.05). (3) AE2 mRNA expression was detected both in ICP placenta and in normal placentas along with pregnancy, but we did not find expression of BSEP mRNA in any placenta. AE2 mRNA expression in placenta of late pregnancy was significantly higher than those of early and middle pregnancy (3.35±2.30 VS 0. 81±0.54,1.01±0.89, P＜0.05). AE2 mRNA expression was significantly increased in ICP group than that in control group (5.75±4.37 VS 3.35±2.30, P＜0.05). (4) AE2 expression was detected in trophoblast by immunohistochemistry. (5) There were significant positive correlations between maternal serum DCA, LCA levels and placental AE2 mRNA expression in ICP group(r=0.476,0.451, P＜0.05), as well as positive correlations between umbilical serum DCA,CDCA levels and placental AE2 mRNA expression (r=0.523,0.448, P＜0.05). There were no significant correlations between maternal or umbilical serum bile acids levels and placental AE2 mRNA expression in control group (r=-0.399～0.523, P＞0.05).Conclusion Our results suggested that TBA and majority of bile acids increase obviously both in the maternal and fetal profiles in ICP. Increased placental expression of AE2 may improve transporting of bile acids across the placenta toward fetus and result in fetal cholestasis, this is probably involved in the mechanism of poor prognosis of perinatal outcome in ICP.