Free fatty acids or high-concentration glucose enhances hepatitis A virus replication in association with a reduction in glucose-regulated protein 78 expression

Recent advances in hepatitis A virus research and clinical practice guidelines for hepatitis A virus infection in Japan

In 2018, there was a hepatitis A outbreak in Japan, and hepatitis A virus (HAV) infection is considered a sexually transmitted disease. In general, patients with hepatitis A should be given attention, and this disease should be prevented more than ever. The Japan Agency for Medical Research and Development (AMED) Hepatitis A and E viruses (HAV and HEV) Study Group has worked on the project to create "Recent Advances in Hepatitis A Virus (HAV) Research and Clinical Practice Guidelines for HAV Infection in Japan". The group consists of expert hepatologists and virologists who gathered at virtual meeting on August 5, 2023. Data about the pathogenesis, infection routes, diagnosis, complications, several factors for the severities, vaccination, and current and future treatments for hepatitis A were discussed and debated for a draft version. The participants assessed the quality of cited studies. The finalized recommendations are presented in this review. The recent advances in HAV research and clinical practice for HAV infection in Japan, have been reviewed by the AMED HAV and HEV Study Group.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

Knockdown of Mitogen-Activated Protein Kinase Kinase 3 Negatively Regulates Hepatitis A Virus Replication

Zinc chloride is known to be effective in combatting hepatitis A virus (HAV) infection, and zinc ions seem to be especially involved in Toll-like receptor (TLR) signaling pathways. In the present study, we examined this involvement in human hepatoma cell lines using a human TLR signaling target RT-PCR array. We also observed that zinc chloride inhibited mitogen-activated protein kinase kinase 3 (MAP2K3) expression, which could downregulate HAV replication in human hepatocytes. It is possible that zinc chloride may inhibit HAV replication in association with its inhibition of MAP2K3. In that regard, this study set out to determine whether MAP2K3 could be considered a modulating factor in the development of the HAV pathogen-associated molecular pattern (PAMP) and its triggering of interferon-β production. Because MAP2K3 seems to play a role in antiviral immunity against HAV infection, it is a promising target for drug development. The inhibition of MAP2K3 may also prevent HAV patients from developing a severe hepatitis A infection.

A functional interaction between GRP78 and Zika virus E protein

Zika virus (ZIKV) is a mosquito-transmitted virus that has caused significant public health concerns around the world, partly because of an association with microcephaly in babies born to mothers who were infected with ZIKV during pregnancy. As a recently emerging virus, little is known as to how the virus interacts with the host cell machinery. A yeast-2-hybrid screen for proteins capable of interacting with the ZIKV E protein domain III, the domain responsible for receptor binding, identified 21 proteins, one of which was the predominantly ER resident chaperone protein GRP78. The interaction of GRP78 and ZIKV E was confirmed by co-immunoprecipitation and reciprocal co-immunoprecipitation, and indirect immunofluorescence staining showed intracellular and extracellular co-localization between GRP78 and ZIKV E. Antibodies directed against the N-terminus of GRP78 were able to inhibit ZIKV entry to host cells, resulting in significant reductions in the levels of ZIKV infection and viral production. Consistently, these reductions were also observed after down-regulation of GRP78 by siRNA. These results indicate that GRP78 can play a role mediating ZIKV binding, internalization and replication in cells. GRP78 is a main regulator of the unfolded protein response (UPR), and the study showed that expression of GRP78 was up-regulated, and the UPR was activated. Increases in CHOP expression, and activation of caspases 7 and 9 were also shown in response to ZIKV infection. Overall these results indicate that the interaction between GRP78 and ZIKV E protein plays an important role in ZIKV infection and replication, and may be a potential therapeutic target.

Co-Occurrence of Hepatitis A Infection and Chronic Liver Disease

Hepatitis A virus (HAV) infection occasionally leads to a critical condition in patients with or without chronic liver diseases. Acute-on-chronic liver disease includes acute-on-chronic liver failure (ACLF) and non-ACLF. In this review, we searched the literature concerning the association between HAV infection and chronic liver diseases in PubMed. Chronic liver diseases, such as metabolic associated fatty liver disease and alcoholic liver disease, coinfection with other viruses, and host genetic factors may be associated with severe hepatitis A. It is important to understand these conditions and mechanisms. There may be no etiological correlation between liver failure and HAV infection, but there is an association between the level of chronic liver damage and the severity of acute-on-chronic liver disease. While the application of an HAV vaccination is important for preventing HAV infection, the development of antivirals against HAV may be important for preventing the development of ACLF with HAV infection as an acute insult. The latter is all the more urgent given that the lives of patients with HAV infection and a chronic liver disease of another etiology may be at immediate risk.

The Host Cell ViroCheckpoint: Identification and Pharmacologic Targeting of Novel Mechanistic Determinants of Coronavirus-Mediated Hijacked Cell States

Most antiviral agents are designed to target virus-specific proteins and mechanisms rather than the host cell proteins that are critically dysregulated following virus-mediated reprogramming of the host cell transcriptional state. To overcome these limitations, we propose that elucidation and pharmacologic targeting of host cell Master Regulator proteins-whose aberrant activities govern the reprogramed state of coronavirus-infected cells-presents unique opportunities to develop novel mechanism-based therapeutic approaches to antiviral therapy, either as monotherapy or as a complement to established treatments. Specifically, we propose that a small module of host cell Master Regulator proteins (ViroCheckpoint) is hijacked by the virus to support its efficient replication and release. Conventional methodologies are not well suited to elucidate these potentially targetable proteins. By using the VIPER network-based algorithm, we successfully interrogated 12h, 24h, and 48h signatures from Calu-3 lung adenocarcinoma cells infected with SARS-CoV, to elucidate the time-dependent reprogramming of host cells and associated Master Regulator proteins. We used the NYS CLIA-certified Darwin OncoTreat algorithm, with an existing database of RNASeq profiles following cell perturbation with 133 FDA-approved and 195 late-stage experimental compounds, to identify drugs capable of virtually abrogating the virus-induced Master Regulator signature. This approach to drug prioritization and repurposing can be trivially extended to other viral pathogens, including SARS-CoV-2, as soon as the relevant infection signature becomes available.

Deteriorated outcome of recent patients with acute liver failure and late-onset hepatic failure caused by infection with hepatitis A virus: A subanalysis of patients seen between 1998 and 2015 and enrolled in nationwide surveys in Japan

AIM

A nationwide survey of acute liver failure (ALF) and late-onset hepatic failure (LOHF) has revealed that the outcomes of recent patients whose diseases were caused by infection with hepatitis A virus (HAV) have worsened, compared with those of previously reported patients. The factors associated with this deterioration were evaluated.

METHODS

A total of 83 patients with HAV infection seen between 1998 and 2015 were enrolled. All the patients had a prothrombin time-international normalized ratio of 1.5 or more and hepatic encephalopathy of grade 2 or more severe. The demographic and clinical features of 45 patients seen prior to 2003 (cohort 1) and 38 patients seen during 2004 and thereafter (cohort 2) were compared.

RESULTS

Three and four patients in cohort 1 and cohort 2, respectively, received liver transplantations; the survival rates among the remaining patients were 56% for cohort 2 and 79% for cohort 1 (P < 0.05). The mean age (±standard deviation) of the patients was higher in cohort 2 than in cohort 1 (58 ± 11 vs. 48 ± 13 years; P < 0.01). The percentages of patients with underlying metabolic diseases were 22% in cohort 1 and 61% in cohort 2 (P < 0.01). Diabetic mellitus was more common among deceased patients than among rescued patients (29% vs. 8%; P < 0.05) among patients who did not receive liver transplantations, and a multivariate analysis revealed that patient age and disease type were significantly and independently associated with the outcome.

CONCLUSION

The outcomes of recent patients with ALF or LOHF caused by HAV infection have recently worsened mainly because of an increase in underlying metabolic diseases as a consequence of aging.

Possible association of arrestin domain-containing protein 3 and progression of non-alcoholic fatty liver disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) is increasing worldwide. Several effective drugs for these diseases are now in development and under clinical trials. It is important to reveal the mechanism of the development of NAFLD and NASH. We investigated the role of arrestin domain-containing protein 3 (ARRDC3), which is linked to obesity in men and regulates body mass, adiposity and energy expenditure, in the progression of NAFLD and NASH. We performed knockdown of endogenous ARRDC3 in human hepatocytes and examined the inflammasome-associated gene expression by real-time PCR-based array. We also examined the effect of conditioned medium from endogenous ARRDC3-knockdown-hepatocytes on the apoptosis of hepatic stellate cells. We observed that free acids enhanced the expression of ARRDC3 in hepatocytes. Knockdown of ARRDC3 could lead to the inhibition of inflammasome-associated gene expression in hepatocytes. We also observed that conditioned medium from endogenous ARRDC3-knockdown-hepatocytes enhances the apoptosis of hepatic stellate cells. ARRDC3 has a role in the progression of NAFLD and NASH and is one of the targets for the development of the effective treatment of NAFLD and NASH.

Inhibitory effect of Japanese rice-koji miso extracts on hepatitis A virus replication in association with the elevation of glucose-regulated protein 78 expression

Hepatitis A virus (HAV) infection is one of the major causes of acute hepatitis and acute liver failure in developing and developed countries. Although effective vaccines for HAV infection are available, outbreaks of HAV infection still cause deaths, even in developed countries. One approach to control HAV infection is prevention through diet, which can inhibit HAV propagation and replication. Glucose-regulated protein 78 (GRP78) is a member of the heat shock protein 70 family of molecular chaperone required for endoplasmic reticulum stress and stress-induced autophagy. We previously showed that the elevation of GRP78 expression inhibits HAV replication. It has been reported that Japanese miso extracts, which was made from rice-koji, enhance GRP78 expression. In the present study, we used human hepatoma Huh7 cells and human hepatocyte PXB cells to examine the efficacy of Japanese miso extracts as antiviral agents against HAV. Japanese miso extracts enhanced GRP78 expression and inhibited HAV replication in human hepatocytes. Together, these results demonstrate that Japanese miso extracts may partly modulate GRP78 expression and additively or synergistically work as antivirals against HAV infection. Japanese miso extracts can be used as effective dietary supplements for severe hepatitis A.

Glucose-regulated protein 78 is an antiviral against hepatitis A virus replication

Infection with hepatitis A virus (HAV) is a major cause of acute hepatitis globally and it is important to identify the mechanisms of HAV replication. Glucose-regulated protein 78 (GRP78) is an endoplasmic reticulum (ER) chaperone and serves a role in unfolded protein response pathways. Previous studies have demonstrated that GRP78 functions as an endogenous antiviral factor. In the present study, two loss-of-function studies using GRP78 were completed to elucidate the role of GRP78 in HAV infection. HAV replication was observed to be enhanced by deficient GRP78 although GRP78-deficiency also led to lower expression of ER stress molecules downstream of GRP78. Therefore, GRP78 appears to be a potential novel defensive molecule against HAV in hepatocytes.