In vitro study on hepatitis B virus infecting human choriocarcinoma JEG3 cells and its mechanism

Presence of entry receptors and viral markers suggest a low level of placental replication of hepatitis B virus in a proportion of pregnant women infected with chronic hepatitis B

The transplacental route of vertical transmission of Hepatitis B Virus (HBV) has been known for over a decade. Here we present evidence which suggest HBV can replicate in placenta. Forty-one HBsAg positive and 10 control pregnant women were enrolled in the study after obtaining informed consent. HBV positives were further divided in the High Viral Load (HVL) Group and Low Viral Load (LVL) Group according to INASL guidelines 2018. The Presence of the HBV DNA and expression of NTCP in the placenta was analyzed by qPCR/RT-qPCR and/or immunohistochemistry (IHC). The presence of cccDNA was assessed using Digital Droplet PCR while the presence of pre-genomic (pg) RNA was assessed through qRT-PCR and sequencing. The presence of HBeAg and HBcAg in the placenta was assessed by IHC. Immunostaining of NTCP, HBeAg and HBcAg on trophoblasts along with the presence of total HBV DNA, cccDNA and pgRNA indicated, that these cells are not only susceptible to HBV infection but may also support viral replication. This is further supported by the finding that trophoblasts of the several HBeAg seronegative samples harbored the HBeAg. Although, we did not find any correlation in NTCP expression and viral markers with viral load indicates placental replication may not aping hepatocytes. The presence of the HBV receptor, NTCP along with the presence of cccDNA, pgRNA, and HBeAg in placenta of HBV infected females without circulating HBeAg suggest that placenta act as a replication host.

The S100A10-AnxA2 complex is associated with the exocytosis of hepatitis B virus in intrauterine infection

Mother-to-child transmission (MTCT) is the major cause of chronic infection of hepatitis B virus (HBV) in patients. However, whether and how HBV crosses the placenta to cause infection in utero remains unclear. In this study, we investigate the mechanism as to how the HBV virions pass through layers of the trophoblast. Our data demonstrate the exocytosis of virions from the trophoblast after exposure to HBV where the endocytosed HBV virions co-localized with an S100A10/AnxA2 complex and LC3, an autophagosome membrane marker. Knockdown of either AnxA2 or S100A10 in trophoblast cells led to a reduction of the amount of exo-virus in Transwell assay. Immunohistochemistry also showed a high expression of AnxA2 and S100A10 in the placental tissue samples of HBV-infected mothers with congenital HBV-positive infants (HBV+/+). We conclude that in HBV intrauterine infection and mother-to-child transmission, a proportion of HBV hijacks autophagic protein secretion pathway and translocate across the trophoblast via S100A10/AnxA2 complex and multivesicular body (MVB)-mediated exocytosis. Our study provides a potential target for the interference of the mechanisms of HBV intrauterine infection and mother-to-child transmission.

Programmed cell death protein 1 promotes hepatitis B virus transmission through the regulation of ERK1/2-mediated trophoblasts differentiation

PURPOSE

The purpose of our research is to evaluate the mechanism of PD-1 in the promotion of HBV transmission.

METHODS

HBV was used to infect two human choriocarcinoma cell line, including JEG-3, as well as BeWo. We used PCR and western blotting to detect PD-1 gene and protein expression levels in cells. Stable knockdown of the PD-1 gene in JEG-3 cells was obtained by lentiviral transfection. Trophoblast cell proliferation was evaluated using CCK8 and flow cytometry. The concentration of HBV antibody in the cell supernatant was measured by ELISA. DNA was then extracted from the cells and the copy number of the HBV virus was detected by PCR. Finally, ERK1/2 expression was detected by western blot.

RESULTS

High PD-1 gene expression in HBV-infected trophoblasts and the knockdown of PD-1 gene can, respectively, improve the proliferation of HBV-infected trophoblasts and reduce viral replication in trophoblasts. In addition, PD-1 and ERK1/2 proteins were co-expressed in HBV-infected trophoblasts and inhibited the activation of ERK1/2 pathway in HBV-infected trophoblasts. ERK1/2 expression significantly increased after PD-1 knockdown. Therefore, PD-1 might be an important protein in trophoblast cells infected with HBV.

CONCLUSIONS

PD-1 promoted HBV transmission through regulating ERK1/2-mediated trophoblasts differentiation. Therefore, our research may provide new ideas and methods for preventing mother-to-child transmission of HBV infection during pregnancy.

miRNAs as common regulators of the transforming growth factor (TGF)-β pathway in the preeclamptic placenta and cadmium-treated trophoblasts: Links between the environment, the epigenome and preeclampsia

Preeclampsia (PE) is a pregnancy disorder characterized by high blood pressure and proteinuria that can cause adverse health effects in both mother and fetus. There is no current cure for PE other than delivery of the fetus/placenta. While the etiology is unknown, poor placentation due to aberrant signaling of growth and angiogenic factors has been postulated as a causal factor of PE. In addition, environmental contaminants, such as the metal cadmium (Cd), have been linked to placental toxicity and increased risk of developing PE. Here, we use a translational study design to investigate genomic and epigenomic alterations in both placentas and placental trophoblasts, focused on the angiogenesis-associated transforming growth factor-beta (TGF-β) pathway. Genes within the TGF-β pathway displayed increased expression in both the preeclamptic placenta and Cd-treated trophoblasts. In addition, miRNAs that target the TGF-β pathway were also significantly altered within the preeclamptic placenta and Cd-treated trophoblasts. Integrative analysis resulted in the identification of a subset of Cd-responsive miRNAs, including miR-26a and miR-155, common to preeclamptic placentas and Cd-treated trophoblasts. These miRNAs have previously been linked to PE and are predicted to regulate members of the TGF-β pathway. Results from this study provide future targets for PE treatment.