Hepatitis E Virus Induces Hepatocyte Apoptosis via Mitochondrial Pathway in Mongolian Gerbils

Abstract

Previous studies demonstrated that Mongolian gerbils can be infected by hepatitis E virus (HEV), which induces the hepatic injury. Here, the mitochondria in hepatocytes from HEV-infected gerbils were considerably swollen, thin cristae. After HEV infection, the activity of superoxide dismutase significantly decreased (p < 0.01), while malondialdehyde concentrations significantly increased, compared with those in the control group (p < 0.01). Adenosine triphosphatase levels decreased significantly in the hepatocyte of the inoculated groups, compared with those in control group (p < 0.05) at days 21, 28, 42 post-inoculation (dpi) as well. Furthermore, the levels of ATP synthetase ATP5A1 significantly decreased during HEV infection, compared with those in the control group (p < 0.05). According to the TdT mediated dUTP nick end labeling (TUNEL) detection, TUNEL positive hepatocytes increased in the inoculated group, compared with that in the control group (p < 0.05). Up-regulation of the mitochondrion-mediated apoptosis regulating proteins, Bax and Bcl-2, in the HEV-infected gerbils (p < 0.05) was observed. However, cytochrome c levels in mitochondria decreased, while this molecule was detected in the cytoplasm of the infected animals, in contrast to that in the control group. Apaf-1, and active caspase-9 and -3 levels were shown to be significantly higher in the inoculated group compared with those in the control group (p < 0.05). Taken together, our results demonstrated that HEV infection induces hepatocyte injuries and activity of the mitochondrial apoptotic pathway, which trigger the hepatocyte apoptosis in Mongolian gerbils.

Hepatitis E Virus Induces Brain Injury Probably Associated With Mitochondrial Apoptosis

“…The steady state of pro-survival Bcl-2 members could also be destroyed after the activation of Bak and Bax (McArthur et al, 2018). The previous study has shown that HEV infection led to mitochondria-mediated apoptosis of hepatocytes, such as induction of Bax, Bcl-2, caspase-9, and caspase-3 (Yang et al, 2018). In our study, increased TUNEL-positive signals were observed in infected brain tissues.…”

“…It has been reported that the release of cytochrome c was increased in BHK-21 cells infected with bovine ephemeral fever virus (BEFV) and activation of caspase-9, as well as the downstream effector caspase-3, were further detected (Lin et al, 2009). In gerbil model of HEV infection, mitochondrial damages such as mitochondria swelling, devoid of mitochondrial cristae were observed in hepatocytes via transmission electron microscope (TEM) (Yang et al, 2018). In Yang's study, up-regulation of mitochondria-mediated apoptosis regulating proteins, Bax and Bcl-2, in HEV-infected gerbils, as well as induction of activated caspase-9 and caspase-3 were observed.…”

Increased Mast Cell Activation in Mongolian Gerbils Infected by Hepatitis E Virus

“…Detailed information of transcription system for RNA and amplifying system for HEV RNA RT-PCR are listed in Supplementary Tables S1 , S2 . Amplification conditions for both round of PCR were: 94°C for 3 min; 30 cycles of 94°C for 30 s, 58°C for 35 s, and 72°C for 30 s; 72°C for 7 min ( Yang et al, 2018 ). Negative (pure water) and positive (HEV RNA) controls were designed in the RT-PCR assay.…”

“…Immunohistochemical staining was performed following the instructions that were included in the Histostain TM -Plus kit (ZSGB-BIO, Beijing, China). 3,3′-Diaminobenzidine tetrahydrochloride (DAB; ZSGB-BIO, Beijing, China) was applied for 5 min to visualize the antigen–antibody compound, Gill’s hematoxylin was applied as the background stain ( Yang et al, 2018 ). The slides were observed under light microscope (Olympus Optical Co., Ltd., Beijing, China) and positive signals for HEV-ORF2 proteins were represented by a brown or yellow granular mass ( Soomro et al, 2016 ).…”

Mitochondria in the biology, pathogenesis, and treatment of hepatitis virus infections

“…Similarly, HCV infection enhances susceptibility to Fas‐mediated apoptosis, whereas several HCV proteins (core, E1, E2, and NS proteins) inhibit TNF‐α‐mediated apoptosis . Recently, HEV has been reported to induce hepatocyte apoptosis via mitochondrial pathway in Mongolian gerbils . However, the underlining interaction between apoptosis and HEV infection remains largely obscure.…”