Autophagic flux inhibition, apoptosis, and mitochondrial dysfunction in bile acids-induced impairment of human placental trophoblast

Intrahepatic cholestasis of pregnancy (ICP) is a common pregnancy-specific disease, characterized by increased bile acid levels and adverse fetal outcomes. We previously reported excessive bile acids led to dysfunction of placental trophoblasts in ICP. However, the detailed mechanism is still unclear. Autophagy is fundamental process for protecting cell survival against adverse conditions. Here, we evaluated the effect of increased concentration of bile acids on autophagy in trophoblasts in vitro and in vivo. First, we demonstrated that the autophagy substrate p62/sequestosome-1 was accumulated in placental tissues from patients with ICP and in human trophoblasts treated with hydrophobic bile acids, including chenodeoxycholic acid and deoxycholic acid. Furthermore, we found that treatment with hydrophobic bile acids impaired autophagic flux in both time- and concentration-dependent manners, by suppressing the AMP-activated protein kinase/unc-51-like kinase 1 autophagic signaling pathway. Notably, trophoblasts were prone to apoptotic cell death upon starvation along with bile-acids treatment in vitro or in an ICP mouse model in vivo. Additionally, we revealed mitochondrial dysfunction was the predominant biological process in excessive bile acids induced trophoblast impairment under starvation by proteomic assay. Collectively, our study proposed a complex interaction of excessive bile acids induced autophagic flux, mitochondrial dysfunction, and cellular apoptosis in placental trophoblasts may play a critical role in the pathogenesis of ICP.