Adiponectin, a downstream target gene of peroxisome proliferator-activated receptor γ, controls hepatitis B virus replication

Pre-Existing and New-Onset Metabolic Dysfunctions Increase Cirrhosis and Its Complication Risks in Chronic Hepatitis B

INTRODUCTION

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing among the chronic hepatitis B (CHB) population. This study aimed to explore the impact of metabolic dysfunction (MD) on cirrhosis and cirrhotic complication risks in CHB.

METHODS

Patients with CHB were consecutively recruited between 2006 and 2021. The presence of MD was based on the 5 cardiometabolic criteria specified in the MASLD definition. Patients were categorized into MD/non-MD groups based on these criteria.

RESULTS

Eleven thousand five hundred two treatment-naive noncirrhotic patients with CHB were included with a median follow-up of 5.3 years. Patients in the MD group (n = 7,314) were older and had lower hepatitis B virus DNA levels than non-MD patients (n = 4,188). After adjustment for clinical and viral factors, MD patients had significantly higher risks of cirrhosis (adjusted hazard ratio [aHR]: 1.82, 95% confidence interval [CI]: 1.40-2.37, P < 0.001) and cirrhotic complications (aHR: 1.30 per MD, 95% CI: 1.03-1.63, P = 0.025) in a dose-dependent manner. Furthermore, new-onset diabetes mellitus during the follow-up aggravated the risk of cirrhotic complications (aHR: 2.87, 95% CI: 1.34-6.11, P = 0.006). Hepatic steatosis was associated with lower risks of cirrhosis (aHR: 0.57 within 5 years, 95% CI: 0.44-0.74, P < 0.001) and cirrhotic complications (aHR: 0.45, 95% CI 0.23-0.88, P = 0.020). Among individuals with hepatic steatosis, patients with MASLD exhibited a higher cirrhosis risk than non-MD patients.

DISCUSSION

Concurrent and new-onset MDs increase the risks of cirrhosis and cirrhotic complications in patients with CHB, independent of hepatic steatosis. Proactively investigating metabolic comorbidities in CHB is critical to stratify the risk of liver disease progression.

Love-hate relationship between hepatitis B virus and type 2 diabetes: a Mendelian randomization study

Objective

The impact of hepatitis B virus (HBV) on the risk of type 2 diabetes (T2D) remains a controversial topic. This study aims to analyze the causal relationship between HBV and T2D using Mendelian randomization (MR).

Methods

Single nucleotide polymorphisms on chronic hepatitis B (CHB), liver fibrosis, liver cirrhosis, and T2D were obtained from BioBank Japan Project, European Bioinformatics Institute, and FinnGen. Mendelian randomization was utilized to evaluate exposure-outcome causality. Inverse variance weighted was used as the primary method for MR analysis. To assess horizontal pleiotropy and heterogeneity, we conducted MR-Egger intercept analysis and Cochran's Q test, and the robustness of the MR analysis results was evaluated through leave-one-out sensitivity analysis.

Results

MR analysis revealed that CHB was associated with a decreased genetic susceptibility to T2D (OR, 0.975; 95% CI, 0.962-0.989; p < 0.001) while liver cirrhosis (OR, 1.021; 95% CI, 1.007-1.036; p = 0.004) as well as liver cirrhosis and liver fibrosis (OR, 1.015; 95% CI, 1.002-1.028; p = 0.020) were associated with an increased genetic susceptibility to T2D. MR-Egger intercept showed no horizontal pleiotropy (p > 0.05). Cochran's Q showed no heterogeneity (p > 0.05). Leave-one-out sensitivity analysis showed that the results were robust.

Conclusion

CHB has the potential to act as a protective factor for T2D, but its effectiveness is constrained by viral load and disease stage. This protective effect diminishes or disappears as viral load decreases, and it transforms into a risk factor with the progression to liver fibrosis and cirrhosis.

Correlation analysis of hepatic steatosis and hepatitis B virus: a cross-sectional study

BACKGROUND

The co-occurrence of chronic hepatitis B (CHB) and metabolic dysfunction-associated fatty liver disease (MAFLD) has drawn considerable attention due to its impact on disease outcomes. This study aimed to investigate the association between hepatic steatosis and hepatitis B virus (HBV) and analyzed the influence of hepatic steatosis on hepatitis B virology in patients with CHB.

METHODS

In this cross-sectional study, 272 patients infected with HBV who were treatment-naïve or had ceased antiviral treatment for > 6 months were categorized into the CHB group (n = 128) and CHB + MAFLD group (n = 144). Furthermore, based on whether HBV DNA was higher than 2000 IU/mL, patients were categorized into the high-level HBV DNA group (n = 129) and the low-level HBV DNA group (n = 143). The impact of hepatic steatosis on hepatitis B virology was analyzed within the CHB cohort. Multivariate logistic regression analysis was employed to identify independent factors influencing pre-genomic RNA (pgRNA) levels below the lower limit of detection (LLD) in patients with CHB.

RESULTS

Among the 272 patients, compared with CHB group, HBV DNA levels (4.11 vs. 3.62 log10 IU/mL, P = 0.045), hepatitis B surface antigen (HBsAg) levels (3.52 vs. 3.20 log10 IU/mL, P = 0.008) and the hepatitis B e antigen (HBeAg) positive rate (33.6% vs. 22.2%, P = 0.036) were significantly decreased in the CHB + MAFLD group; In 143 low-level HBV DNA patients, the CHB + MAFLD group exhibited decreased levels of pgRNA and HBsAg compared to the CHB group. However, in 129 high-level HBV DNA patients, a more significant decrease was observed in pgRNA (3.85 vs 3.35 log10 copies/mL, P = 0.044) and HBsAg (3.85 vs 3.59 log10 IU/mL, P = 0.033); Spearman correlation analysis revealed a negative correlation between hepatic steatosis and pgRNA (r =  - 0.529, P < 0.001), HBV DNA (r =  - 0.456, P < 0.001), HBsAg (r =  - 0.465, P < 0.001) and HBeAg (r =  - 0.339, P < 0.001) levels; Multivariate logistic regression analysis identified HBV DNA (odds ratio [OR] = 0.283, P < 0.001), HBsAg (OR = 0.300, P < 0.001), and controlled attenuation parameter (CAP) values (OR = 1.013, P = 0.038) as independent factors influencing pgRNA levels below the LLD in patients with CHB.

CONCLUSIONS

This study establishes a negative correlation between hepatic steatosis and hepatitis B virology, demonstrating decreased HBV expression in patients with CHB + MAFLD.

Metabolic Dysfunction-Associated Fatty Liver Disease and Chronic Viral Hepatitis: The Interlink

Metabolic dysfunction-associated fatty liver disease (MAFLD) has now affected nearly one-third of the global population and has become the number one cause of chronic liver disease in the world because of the obesity pandemic. Chronic hepatitis resulting from hepatitis B virus (HBV) and hepatitis C virus (HCV) remain significant challenges to liver health even in the 21st century. The co-existence of MAFLD and chronic viral hepatitis can markedly alter the disease course of individual diseases and can complicate the management of each of these disorders. A thorough understanding of the pathobiological interactions between MAFLD and these two chronic viral infections is crucial for appropriately managing these patients. In this comprehensive clinical review, we discuss the various mechanisms of chronic viral hepatitis-mediated metabolic dysfunction and the impact of MAFLD on the progression of liver disease.

Distinct effects of hepatic steatosis and metabolic dysfunction on the risk of hepatocellular carcinoma in chronic hepatitis B

OBJECTIVE

Chronic hepatitis B (CHB) and metabolic dysfunction-associated fatty liver disease (MAFLD) are the leading causes of hepatocellular carcinoma (HCC). We aim to explore the impact of concurrent MAFLD on the risk of HCC in CHB.

METHODS

Patients with CHB were consecutively recruited from 2006 to 2021. MAFLD was defined by steatosis and either obesity, diabetes mellitus, or other metabolic abnormalities. The cumulative incidence of HCC and associated factors were compared between the MAFLD and non-MAFLD groups.

RESULTS

10,546 treatment-naïve CHB patients were included with a median follow-up of 5.1 years. CHB patients with MAFLD (n = 2212) had fewer hepatitis B e antigen (HBeAg)-positivity, lower HBV DNA levels, and Fibrosis-4 index compared with the non-MAFLD group (n = 8334). MAFLD was independently associated with a 58% reduced risk of HCC (adjusted hazard ratio [aHR] 0.42, 95% confidence interval [CI] 0.25-0.68, p < 0.001). Furthermore, steatosis and metabolic dysfunction had distinct effects on HCC. Steatosis was protective against HCC (aHR 0.45, 95% CI 0.30-0.67, p < 0.001), while a greater burden of metabolic dysfunction increased the risk (aHR 1.40 per dysfunction increase, 95% CI 1.19-1.66, p < 0.001). The protective effect of MAFLD was further confirmed in analysis with inverse probability of treatment weighting (IPTW), patients who had undergone antiviral therapy, those with probable MAFLD, and after multiple imputation for missing data.

CONCLUSIONS

Concurrent hepatic steatosis is independently associated with a lower risk of HCC, whereas the increasing burden of metabolic dysfunction aggravates the risk of HCC in untreated CHB patients.

Peptidyl-prolyl cis/trans isomerase Pin1 interacts with hepatitis B virus core particle, but not with HBc protein, to promote HBV replication

Here, we demonstrate that the peptidyl-prolyl cis/trans isomerase Pin1 interacts noncovalently with the hepatitis B virus (HBV) core particle through phosphorylated serine/threonine-proline (pS/TP) motifs in the carboxyl-terminal domain (CTD) but not with particle-defective, dimer-positive mutants of HBc. This suggests that neither dimers nor monomers of HBc are Pin1-binding partners. The ¹⁶²TP, ¹⁶⁴SP, and ¹⁷²SP motifs within the HBc CTD are important for the Pin1/core particle interaction. Although Pin1 dissociated from core particle upon heat treatment, it was detected as an opened-up core particle, demonstrating that Pin1 binds both to the outside and the inside of the core particle. Although the amino-terminal domain S/TP motifs of HBc are not involved in the interaction, ⁴⁹SP contributes to core particle stability, and ¹²⁸TP might be involved in core particle assembly, as shown by the decreased core particle level of S49A mutant through repeated freeze and thaw and low-level assembly of the T128A mutant, respectively. Overexpression of Pin1 increased core particle stability through their interactions, HBV DNA synthesis, and virion secretion without concomitant increases in HBV RNA levels, indicating that Pin1 may be involved in core particle assembly and maturation, thereby promoting the later stages of the HBV life cycle. By contrast, parvulin inhibitors and PIN1 knockdown reduced HBV replication. Since more Pin1 proteins bound to immature core particles than to mature core particles, the interaction appears to depend on the stage of virus replication. Taken together, the data suggest that physical association between Pin1 and phosphorylated core particles may induce structural alterations through isomerization by Pin1, induce dephosphorylation by unidentified host phosphatases, and promote completion of virus life cycle.

Contribution of Adiponectin/Carnitine Palmityl Transferase 1A-Mediated Fatty Acid Metabolism during the Development of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease that leads rapidly to death. The present study is aimed at discovering the in-depth pathogenesis of IPF, exploring the role of adiponectin/carnitine palmityl transferase 1A- (APN/CPT1A-) mediated fatty acid metabolism during the development of IPF, and excavating its potential mechanism. Here, THP-1 cells were differentiated into M0 macrophages, followed by polarization to M1 macrophages upon hypoxia. Subsequently, lung fibroblast HFL-1 cells were stimulated by M1 macrophages to simulate hypoxia-related IPF condition in vitro. It was discovered that the stimulation of M1 macrophages promoted fibroblast proliferation and fibrosis formation in vitro, accompanied with a disorder of the APN/CPT1A pathway, an overproduction of lipid peroxides, and a low level of autophagy in HFL-1 cells. Thereafter, APN treatment or CPT1A overexpression greatly suppressed above lipid peroxide accumulation, fibroblast proliferation, and fibrosis but activated autophagy in vitro. Furthermore, an in vivo IPF rat model was established by injection of bleomycin (BLM). Consistently, CPT1A overexpression exerted a protective role against pulmonary fibrosis in vivo; however, the antifibrosis property of CPT1A was partly abolished by 3-methyladenine (an autophagy inhibitor). In summary, APN/CPT1A-mediated fatty acid metabolism exerted its protective role in IPF partly through activating autophagy, shedding a new prospective for the treatment of IPF.

Metabolic dysfunction-associated fatty liver disease and chronic hepatitis B

Fatty liver disease and chronic hepatitis B (CHB) are the major causes for chronic liver diseases and the associated adverse outcomes. Concurrent hepatic steatosis has been found to inversely correlate with hepatitis B virus (HBV) activity both in vivo and in vitro; however, the subsequent effects on the prognosis, including advanced fibrosis and hepatocellular carcinoma (HCC) development, remain diverse and inconclusive. Although the newly-proposed criteria of metabolic dysfunction-associated fatty liver disease (MAFLD) help raise disease awareness and facilitate timely diagnosis and management, its clinical impact on patients with CHB, especially after taking the metabolic dysfunction into consideration, is largely unknown and warrants comprehensive investigations to improve the management of CHB population. In this review, these relevant issues are summarized and discussed.

Impact of NAFLD on the outcome of patients with chronic hepatitis B in Asia

Hepatitis B virus (HBV) infection and nonalcoholic fatty liver disease (NAFLD) are two major causes of chronic liver disease (CLD) that can cause liver cirrhosis and hepatocellular carcinoma (HCC). It is a trend to superimpose NAFLD on chronic HBV infection in Asia. This review presents the epidemiology of concurrent NAFLD in chronic hepatitis B (CHB) patients and focuses on the impact of concurrent NAFLD on the outcome of CHB patients in Asia. Although CHB patients tend to have a lower prevalence and incidence of NAFLD than the general population, concurrent NAFLD among CHB patients is still common and has an upward trend over time. Concurrent NAFLD can promote hepatitis B surface antigen (HBsAg) seroclearance and might inhibit HBV replication but exacerbate liver fibrosis. The impacts of concurrent NAFLD on HCC risk, all-cause mortality and antiviral treatment response in CHB patients remain controversial.

Clinical impact and mechanisms of hepatitis B virus infection concurrent with non-alcoholic fatty liver disease

ABSTRACT

Chronic hepatitis B (CHB) virus infection is an important threat to global health despite the administration of vaccines and the use of antiviral treatments. In recent years, as the prevalence of obesity and metabolic syndrome has increased, non-alcoholic fatty liver disease (NAFLD) in patients with CHB has become more common. Both diseases can lead to liver fibrosis and even hepatocellular carcinoma, but the risk of dual etiology, outcome, and CHB combined with NAFLD is not fully elucidated. In this review, we assess the overlapping prevalence of NAFLD and CHB, summarize recent studies of clinical and basic research related to potential interactions, and evaluate the progressive changes of treatments for CHB patients with NAFLD. This review increases the understanding of the relationship and mechanisms of interaction between steatosis and hepatitis B virus infection, and it provides new strategies for the future clinical management and treatment of CHB combined with NAFLD.

Non-Alcoholic Fatty Liver Disease in HIV/HBV Patients - a Metabolic Imbalance Aggravated by Antiretroviral Therapy and Perpetuated by the Hepatokine/Adipokine Axis Breakdown

Non-alcoholic fatty liver disease (NAFLD) is strongly associated with the metabolic syndrome and is one of the most prevalent comorbidities in HIV and HBV infected patients. HIV plays an early and direct role in the development of metabolic syndrome by disrupting the mechanism of adipogenesis and synthesis of adipokines. Adipokines, molecules that regulate the lipid metabolism, also contribute to the progression of NAFLD either directly or via hepatic organokines (hepatokines). Most hepatokines play a direct role in lipid homeostasis and liver inflammation but their role in the evolution of NAFLD is not well defined. The role of HBV in the pathogenesis of NAFLD is controversial. HBV has been previously associated with a decreased level of triglycerides and with a protective role against the development of steatosis and metabolic syndrome. At the same time HBV displays a high fibrogenetic and oncogenetic potential. In the HIV/HBV co-infection, the metabolic changes are initiated by mitochondrial dysfunction as well as by the fatty overload of the liver, two interconnected mechanisms. The evolution of NAFLD is further perpetuated by the inflammatory response to these viral agents and by the variable toxicity of the antiretroviral therapy. The current article discusses the pathogenic changes and the contribution of the hepatokine/adipokine axis in the development of NAFLD as well as the implications of HIV and HBV infection in the breakdown of the hepatokine/adipokine axis and NAFLD progression.

The HBV Core Protein and Core Particle Both Bind to the PPiase Par14 and Par17 to Enhance Their Stabilities and HBV Replication

We recently reported that the PPIase Par14 and Par17 encoded by PIN4 upregulate HBV replication in an HBx-dependent manner by binding to conserved arginine–proline (RP) motifs of HBx. HBV core protein (HBc) has a conserved ¹³³RP¹³⁴ motif; therefore, we investigated whether Par14/Par17 bind to HBc and/or core particles. Native agarose gel electrophoresis (NAGE) and immunoblotting and co-immunoprecipitation were used. Chromatin immunoprecipitation from HBV-infected HepG2-hNTCP-C9 cells was performed. NAGE and immunoblotting revealed that Par14/Par17 bound to core particles and co-immunoprecipitation revealed that Par14/Par17 interacted with core particle assembly-defective, and dimer-positive HBc-Y132A. Thus, core particles and HBc interact with Par14/Par17. Par14/Par17 interacted with the HBc ¹³³RP¹³⁴ motif possibly via substrate-binding E46/D74 and E71/D99 motifs. Although Par14/Par17 dissociated from core particles upon heat treatment, they were detected in 0.2 N NaOH-treated opened-up core particles, demonstrating that Par14/Par17 bind outside and inside core particles. Furthermore, these interactions enhanced the stabilities of HBc and core particles. Like HBc-Y132A, HBc-R133D and HBc-R133E were core particle assembly-defective and dimer-positive, demonstrating that a negatively charged residue at position 133 cannot be tolerated for particle assembly. Although positively charged R133 is solely important for Par14/17 interactions, the ¹³³RP¹³⁴ motif is important for efficient HBV replication. Chromatin immunoprecipitation from HBV-infected cells revealed that the S19 and E46/D74 residues of Par14 and S44 and E71/D99 residues of Par17 were involved in recruitment of ¹³³RP¹³⁴ motif-containing HBc into cccDNA. Our results demonstrate that interactions of HBc, Par14/Par17, and cccDNA in the nucleus and core particle–Par14/Par17 interactions in the cytoplasm are important for HBV replication.

Multifaceted Interaction Between Hepatitis B Virus Infection and Lipid Metabolism in Hepatocytes: A Potential Target of Antiviral Therapy for Chronic Hepatitis B

Hepatitis B virus (HBV) is considered a “metabolic virus” and affects many hepatic metabolic pathways. However, how HBV affects lipid metabolism in hepatocytes remains uncertain yet. Accumulating clinical studies suggested that compared to non-HBV-infected controls, chronic HBV infection was associated with lower levels of serum total cholesterol and triglycerides and a lower prevalence of hepatic steatosis. In patients with chronic HBV infection, high ALT level, high body mass index, male gender, or old age was found to be positively correlated with hepatic steatosis. Furthermore, mechanisms of how HBV infection affected hepatic lipid metabolism had also been explored in a number of studies based on cell lines and mouse models. These results demonstrated that HBV replication or expression induced extensive and diverse changes in hepatic lipid metabolism, by not only activating expression of some critical lipogenesis and cholesterolgenesis-related proteins but also upregulating fatty acid oxidation and bile acid synthesis. Moreover, increasing studies found some potential targets to inhibit HBV replication or expression by decreasing or enhancing certain lipid metabolism-related proteins or metabolites. Therefore, in this article, we comprehensively reviewed these publications and revealed the connections between clinical observations and experimental findings to better understand the interaction between hepatic lipid metabolism and HBV infection. However, the available data are far from conclusive, and there is still a long way to go before clarifying the complex interaction between HBV infection and hepatic lipid metabolism.

Roles of Adipokines in Digestive Diseases: Markers of Inflammation, Metabolic Alteration and Disease Progression

Adipose tissue is a highly dynamic endocrine tissue and constitutes a central node in the interorgan crosstalk network through adipokines, which cause pleiotropic effects, including the modulation of angiogenesis, metabolism, and inflammation. Specifically, digestive cancers grow anatomically near adipose tissue. During their interaction with cancer cells, adipocytes are reprogrammed into cancer-associated adipocytes and secrete adipokines to affect tumor cells. Moreover, the liver is the central metabolic hub. Adipose tissue and the liver cooperatively regulate whole-body energy homeostasis via adipokines. Obesity, the excessive accumulation of adipose tissue due to hyperplasia and hypertrophy, is currently considered a global epidemic and is related to low-grade systemic inflammation characterized by altered adipokine regulation. Obesity-related digestive diseases, including gastroesophageal reflux disease, Barrett's esophagus, esophageal cancer, colon polyps and cancer, non-alcoholic fatty liver disease, viral hepatitis-related diseases, cholelithiasis, gallbladder cancer, cholangiocarcinoma, pancreatic cancer, and diabetes, might cause specific alterations in adipokine profiles. These patterns and associated bases potentially contribute to the identification of prognostic biomarkers and therapeutic approaches for the associated digestive diseases. This review highlights important findings about altered adipokine profiles relevant to digestive diseases, including hepatic, pancreatic, gastrointestinal, and biliary tract diseases, with a perspective on clinical implications and mechanistic explorations.

An Alternatively Spliced Sirtuin 2 Isoform 5 Inhibits Hepatitis B Virus Replication from cccDNA by Repressing Epigenetic Modifications Made by Histone Lysine Methyltransferases

Sirtuin 2 (Sirt2), an NAD⁺-dependent protein deacetylase, deacetylates tubulin, AKT, and other proteins. Previously, we showed that Sirt2 isoform 1 (Sirt2.1) increased replication of hepatitis B virus (HBV). Here, we show that HBV replication upregulates the expression of Sirt2 primary and alternatively spliced transcripts and their respective isoforms, 1, 2, and 5. Since Sirt2 isoform 5 (Sirt2.5) is a catalytically inactive nuclear protein with a spliced-out nuclear export signal (NES), we speculated that its different localization affects its activity. The overexpression of Sirt2.5 reduced expression of HBV mRNAs, replicative intermediate DNAs, and covalently closed circular DNA (cccDNA), an activity opposite that of Sirt2.1 and Sirt2.2. Unlike the Sirt2.1-AKT interaction, the Sirt2.5-AKT interaction was weakened by HBV replication. Unlike Sirt2.1, Sirt2.5 activated the AKT/GSK-3β/β-catenin signaling pathway very weakly and independently of HBV replication. When the NES and an N-terminal truncated catalytic domain were added to the Sirt2.5 construct, it localized in the cytoplasm and increased HBV replication (like Sirt2.1 and Sirt2.2). Chromatin immunoprecipitation assays revealed that more Sirt2.5 was recruited to cccDNA than Sirt2.1. The recruitment of histone lysine methyltransferases (HKMTs), such as SETDB1, SUV39H1, EZH2, and PR-Set7, and their respective transcriptional repressive markers, H3K9me3, H3K27me3, and H4K20me1, to cccDNA also increased in Sirt2.5-overexpressing cells. Among these, the Sirt2.5-PR-Set7 and -SETDB1 interactions increased upon HBV replication. These results demonstrate that Sirt2.5 reduces cccDNA levels and viral transcription through epigenetic modification of cccDNA via direct and/or indirect association with HKMTs, thereby exhibiting anti-HBV activity.IMPORTANCE Sirt2, a predominant cytoplasmic α-tubulin deacetylase, promotes the growth of hepatocellular carcinoma; indeed, HBV replication increases Sirt2 expression, and overexpression of Sirt2 is associated with hepatic fibrosis and epithelial-to-mesenchymal transition. Increased amounts of Sirt2 isoforms 1, 2, and 5 upon HBV replication might further upregulate HBV replication, leading to a vicious cycle of virus replication/disease progression. However, we show here that catalytically inactive nuclear Sirt2.5 antagonizes the effects of Sirt2.1 and Sirt2.2 on HBV replication, thereby inhibiting cccDNA level, transcription of cccDNA, and subsequent synthesis of replicative intermediate DNA. More Sirt2.5 was recruited to cccDNA than Sirt2.1, thereby increasing epigenetic modification by depositing transcriptional repressive markers, possibly through direct and/or indirect association with histone lysine methyltransferases, such as SETDB1, SUV39H1, EZH2, and/or PR-Set7, which represses HBV transcription. Thus, Sirt2.5 might provide a functional cure for HBV by silencing the transcription of HBV.

TRAIL inhibits HBV replication and expression by down-regulating liver-enriched transcription factors

BACKGROUND AND STUDY AIMS

To investigate the role of low-concentration TRAIL on HBV replication and expression.

MATERIAL AND METHODS

MTT assay was performed to determine the minimum concentrations of TRAIL protein in HepG2 cell apoptosis. HepG2 cells were transfected by HBV replication plasmid pHBV4.1. After the treatment with low concentration of TRAIL, the culture supernatant was collected to detect HBsAg and HBeAg by ELISA. Proteins were extracted from the resulted cells, followed by total RNA and HBV DNA intermediate replication. Southern Blot and Northern Blot were carried out to detect HBV RNA and HBV DNA replication intermediates, respectively. RT-PCR and Western Blot were carried out to detect gene and protein expressions for HNF4α, PPARα, and RXRα, respectively.

RESULTS

50 ng/ml of TRAIL protein led to significant decline on the secretions of HBsAg and HBeAg. Expression levels of HBV RNA and HBV DNA replication intermediates were significantly decreased too. In addition, gene and protein expressions of HNF4α, PPARα and RXRα also dropped, especially for PPARα whose expressions significantly decreased.

CONCLUSION

TRAIL could inhibit HBV replication and expression by downregulating the expressions of liver-enriched transcription factors HNF4α, PPARα, and RXRα.

Chronic hepatitis B and non-alcoholic fatty liver disease: Conspirators or competitors?

Despite the widespread use of vaccines and antiviral drugs, approximately 350-400 million patients with chronic hepatitis B (CHB) remain worldwide, who carry high risk of cirrhosis and liver carcinoma. Moreover, owing to improvements in global living standards and lifestyle changes, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease. Coexistence of NAFLD and CHB is commonly observed, especially in Asian CHB populations; however, little is known regarding the relationship between these two diseases as comorbidities. In this review, we summarize recent advances in clinical and basic researches related to the underlying mutual interactions, as well as potential animal models to facilitate further investigation.

Sirtuin 2 Isoform 1 Enhances Hepatitis B Virus RNA Transcription and DNA Synthesis through the AKT/GSK-3β/β-Catenin Signaling Pathway

Sirtuin 2 (Sirt2), a NAD⁺-dependent protein deacetylase, is overexpressed in many hepatocellular carcinomas (HCCs) and can deacetylate many proteins, including tubulins and AKT, prior to AKT activation. Here, we found that endogenous Sirt2 was upregulated in wild-type hepatitis B virus (HBV WT)-replicating cells, leading to tubulin deacetylation; however, this was not the case in HBV replication-deficient-mutant-transfected cells and 1.3-mer HBV WT-transfected and reverse transcriptase inhibitor (entecavir or lamivudine)-treated cells, but all HBV proteins were expressed. In HBV WT-replicating cells, upregulation of Sirt2 induced AKT activation, which consequently downregulated glycogen synthase kinase 3β (GSK-3β) and increased β-catenin levels; however, downregulation of Sirt2 in HBV-nonreplicating cells impaired AKT/GSK-3β/β-catenin signaling. Overexpression of Sirt2 isoform 1 stimulated HBV transcription and consequently HBV DNA synthesis, which in turn activated AKT and consequently increased β-catenin levels, possibly through physical interactions with Sirt2 and AKT. Knockdown of Sirt2 by short hairpin RNAs (shRNAs), inhibition by 2-cyano-3-[5-(2,5-dichlorophenyl)-2-furanyl]-N-5-quinolinyl-2-propenamide (AGK2), or dominant negative mutant expression inhibited HBV replication, reduced AKT activation, and decreased β-catenin levels. Through HBV infection, we demonstrated that Sirt2 knockdown inhibited HBV replication from transcription. Although HBx itself activates AKT and upregulates β-catenin, Sirt2-mediated signaling and upregulated HBV replication were HBx independent. Since constitutively active AKT inhibits HBV replication, the results suggest that upregulated Sirt2 and activated AKT may balance HBV replication to prolong viral replication, eventually leading to the development of HCC. Also, the results indicate that Sirt2 inhibition may be a new therapeutic option for controlling HBV infection and preventing HCC.IMPORTANCE Even though Sirt2, a NAD⁺-dependent protein deacetylase, is overexpressed in many HCCs, and overexpressed Sirt2 promotes hepatic fibrosis and associates positively with vascular invasion by primary HCCs through AKT/GSK-3β/β-catenin signaling, the relationship between Sirt2, HBV, HBx, and/or HBV-associated hepatocarcinogenesis is unclear. Here, we show that HBV DNA replication, not HBV expression, correlates positively with Sirt2 upregulation and AKT activation. We demonstrate that overexpression of Sirt2 further increases HBV replication, increases AKT activation, downregulates GSK-3β, and increases β-catenin levels. Conversely, inhibiting Sirt2 decreases HBV replication, reduces AKT activation, and decreases β-catenin levels. Although HBx activates AKT to upregulate β-catenin, Sirt2-mediated effects were not dependent on HBx. The results also indicate that a Sirt2 inhibitor may control HBV infection and prevent the development of hepatic fibrosis and HCC.

Peroxisome Proliferators Activated Receptor (PPAR) agonists activate hepatitis B virus replication in vivo

Background

PPAR agonists are often used in HBV infected patients with metabolic disorders. However, as liver-enriched transcriptional factors, PPARs would activate HBV replication. Risks exsit in such patients. This study aimed to assess the influence of commonly used synthetic PPAR agonists on hepatitis B virus (HBV) transcription, replication and expression through HBV replicative mouse models, providing information for physicians to make necessary monitoring and therapeutic adjustment when HBV infected patients receive PPAR agonists treatment.

Methods

The HBV replicative mouse model was established by hydrodynamic injection of HBV replicative plasmid and the mice were divided into four groups and treated daily for 3 days with saline, PPAR pan-agonist (bezafibrate), PPARα agonist (fenofibrate) and PPARγ agonist (rosiglitazone) respectively. Their serum samples were collected for ECLIA analysis of HBsAg and HBeAg and real-time PCR analysis of Serum HBV DNA. The liver samples were collected for DNA (Southern) filter hybridization of HBV replication intermediates, real-time PCR analysis of HBV mRNA and immunohistochemistry (IHC) analysis of hepatic HBcAg. The alternation of viral transcription, replication and expression were compared in these groups.

Result

Serum HBsAg, HBeAg and HBV DNA were significantly elevated after PPAR agonist treatment. So did the viral replication intermediates in mouse livers. HBV mRNA was also significantly increased by these PPAR agonists, implying that PPAR agonists activate HBV replication at transcription level. Moreover, hepatic HBcAg expression in mouse livers with PPAR agonist treatment was elevated as well.

Conclusion

Our in vivo study proved that synthetic PPAR agonists bezafibrate, fenofibrate and rosiglitazone would increase HBV replication. It suggested that when HBV infected patients were treated with PPARs agonists because of metabolic diseases, HBV viral load should be monitored and regimens may need to be adjusted, an antiviral therapy may be added.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0765-x) contains supplementary material, which is available to authorized users.

HELZ2 Is an IFN Effector Mediating Suppression of Dengue Virus

Flaviviral infections including dengue virus are an increasing clinical problem worldwide. Dengue infection triggers host production of the type 1 IFN, IFN alpha, one of the strongest and broadest acting antivirals known. However, dengue virus subverts host IFN signaling at early steps of IFN signal transduction. This subversion allows unbridled viral replication which subsequently triggers ongoing production of IFN which, again, is subverted. Identification of downstream IFN antiviral effectors will provide targets which could be activated to restore broad acting antiviral activity, stopping the signal to produce endogenous IFN at toxic levels. To this end, we performed a targeted functional genomic screen for IFN antiviral effector genes (IEGs), identifying 56 IEGs required for antiviral effects of IFN against fully infectious dengue virus. Dengue IEGs were enriched for genes encoding nuclear receptor interacting proteins, including HELZ2, MAP2K4, SLC27A2, HSP90AA1, and HSP90AB1. We focused on HELZ2 (Helicase With Zinc Finger 2), an IFN stimulated gene and IEG which encodes a promiscuous nuclear factor coactivator that exists in two isoforms. The two unique HELZ2 isoforms are both IFN responsive, contain ISRE elements, and gene products increase in the nucleus upon IFN stimulation. Chromatin immunoprecipitation-sequencing revealed that the HELZ2 complex interacts with triglyceride-regulator LMF1. Mass spectrometry revealed that HELZ2 knockdown cells are depleted of triglyceride subsets. We thus sought to determine whether HELZ2 interacts with a nuclear receptor known to regulate immune response and lipid metabolism, AHR, and identified HELZ2:AHR interactions via co-immunoprecipitation, found that AHR is a dengue IEG, and that an AHR ligand, FICZ, exhibits anti-dengue activity. Primary bone marrow derived macrophages from HELZ2 knockout mice, compared to wild type controls, exhibit enhanced dengue infectivity. Overall, these findings reveal that IFN antiviral response is mediated by HELZ2 transcriptional upregulation, enrichment of HELZ2 protein levels in the nucleus, and activation of a transcriptional program that appears to modulate intracellular lipid state. IEGs identified in this study may serve as both (1) potential targets for host directed antiviral design, downstream of the common flaviviral subversion point, as well as (2) possible biomarkers, whose variation, natural, or iatrogenic, could affect host response to viral infections.

Diverse impacts of the rs58542926 E167K variant in TM6SF2 on viral and metabolic liver disease phenotypes

A genome-wide exome association study has identified the transmembrane 6 superfamily member 2 (TM6SF2) rs58542926 variant encoding an E167K substitution as a genetic determinant of hepatic steatosis in nonalcoholic fatty liver disease (NAFLD). The roles of this variant across a spectrum of liver diseases and pathologies and on serum lipids comparing viral hepatitis to NAFLD and viral load in chronic viral hepatitis, as well as its intrahepatic molecular signature, have not been well characterized. We undertook detailed analyses in 3260 subjects with viral and nonviral liver diseases and in healthy controls. Serum inflammatory markers and hepatic expression of TM6SF2 and genes regulating lipid metabolism were assessed in a subset with chronic hepatitis C (CHC). The rs58542926 T allele was more prevalent in 502 NAFLD patients than controls (P = 0.02) but not different in cohorts with CHC (n = 2023) and chronic hepatitis B (n = 507). The T allele was associated with alterations in serum lipids and hepatic steatosis in all diseases and with reduced hepatic TM6SF2 and microsomal triglyceride transfer protein expression. Interestingly, the substitution was associated with reduced CHC viral load but increased hepatitis B virus DNA. The rs58542926 T allele had no effect on inflammation, impacted ≥F2 fibrosis in CHC and NAFLD assessed cross-sectionally (odds ratio = 1.39, 95% confidence interval 1.04-1.87, and odds ratio = 1.62, 95% confidence interval 1.03-2.52, respectively; P < 0.03 for both), but had no effect on fibrosis progression in 1174 patients with CHC and a known duration of infection.

CONCLUSION

The TM6SF2 E167K substitution promotes steatosis and lipid abnormalities in part by altering TM6SF2 and microsomal triglyceride transfer protein expression and differentially impacts CHC and chronic hepatitis B viral load, while effects on fibrosis are marginal. (Hepatology 2016;64:34-46).

MicroRNA-130a can inhibit hepatitis B virus replication via targeting PGC1α and PPARγ

In hepatitis B virus (HBV)-replicating hepatocytes, miR-130a expression was significantly reduced. In a reciprocal manner, miR-130a reduced HBV replication by targeting at two major metabolic regulators PGC1α and PPARγ, both of which can potently stimulate HBV replication. We proposed a positive feed-forward loop between HBV, miR-130a, PPARγ, and PGC1α. Accordingly, HBV can significantly enhance viral replication by reducing miR-130a and increasing PGC1α and PPARγ. NF-κB/p65 can strongly stimulate miR-130a promoter, while miR-130a can promote NF-κB/p65 protein level by reducing PPARγ and thus NF-κB/p65 protein degradation. We postulated another positive feed-forward loop between miR-130a and NF-κB/p65 via PPARγ. During liver inflammation, NF-κB signaling could contribute to viral clearance via its positive effect on miR-130a transcription. Conversely, in asymptomatic HBV carriers, persistent viral infection could reduce miR-130a and NF-κB expression, leading to dampened inflammation and immune tolerance. Finally, miR-130a could contribute to metabolic homeostasis by dual targeting PGC1α and PPARγ simultaneously.

Frienemies of infection: A chronic case of host nuclear receptors acting as cohorts or combatants of infection

Macrophages and dendritic cells provide critical effector functions to efficiently resist and promptly eliminate infection. Pattern recognition receptors signaling operative in these cell types is imperative for their innate properties. However, it is now emerging that besides these conventional signaling pathways, nuclear receptors coupled gene regulation and transrepression pathways assemble immune regulatory networks. A couple of these networks associated with members of nuclear receptor superfamily decide heterogeneity in macrophages and dendritic cells population and thereby play decisive role in determining protective immunity against bacteria, viruses, fungi, protozoa and helminths. Pathogens also direct shift in the expression of nuclear receptors and their target genes and this is proclaimed to be a sui generis mechanism whereby microbes disconnect the genomic component from the peripheral immune response. Many endogenous and synthetic nuclear receptor ligands have been tested in various in vitro and in vivo infection models to study their effect on pathogen burden. Here, we discuss current advances in our understanding of the composite interactions between nuclear receptor and pathogens and their implications on the causatum infectious diseases.

Association between metabolic factors and chronic hepatitis B virus infection

There are limited data regarding the relationship between chronic hepatitis B virus (HBV) infection and metabolic factors. This article aims to highlight the link of metabolic factors with hepatitis B surface antigen (HBsAg) serostatus, HBV load, and HBV-related hepatocellular carcinoma (HCC). Although HBsAg-positive serostatus was positively correlated with a high risk of metabolic syndrome in students, chronic HBV-infected individuals have high serum adiponectin levels. The androgen pathway in HBV carriers with a low body mass index is more triggered which leads to enhanced HBV replication. High HBV load was inversely associated with obesity in hepatitis B e antigen (HBeAg)-seropositive HBV carriers; while in HBeAg-seronegative HBV carriers, high HBV load was inversely related to hypertriglyceridemia rather than obesity. For overweight and obese HBV-infected patients, high HBV load was positively associated with serum adiponectin levels. Several large cohort studies have revealed a positive link of diabetes with incidence of HBV-related HCC. However, the association between incidence of HCC and metabolic factors other than diabetes is still inconclusive. More long-term prospective studies should elucidate the association of chronic HBV infection and its outcomes with metabolic factors in clinical practice.

Plasma adipokines and risk of hepatocellular carcinoma in chronic hepatitis B virus-infected carriers: a prospective study in taiwan

BACKGROUND

Obesity is considered a risk factor for hepatocellular carcinoma (HCC). The relationship between adipocytokine and HCC in hepatitis B virus (HBV) carriers remains unclear. We prospectively investigated the association of adiponectin, leptin, and visfatin levels with HCC.

METHODS

We conducted a nested case-control study in a community-based cohort with 187 incident HCC and 374 HCC-free HBV carriers. Unconditional logistic regression was conducted to estimate the ORs and 95% confidence intervals (CI).

RESULTS

Adiponectin, but not leptin and visfatin, levels were associated with an increased risk of HCC after adjustment for other metabolic factors and HBV-related factors. The risk was increased [OR = 0.51; 95% CI, 0.12-2.11; OR = 4.88 (1.46-16.3); OR = 3.79 (1.10-13.0); OR = 4.13 (1.13-15.1) with each additional quintiles, respectively] with a significant dose-response trend (P(trend) = 0.003). HCC risk associated with higher adiponectin level was higher in HBV carriers with ultrasonographic fatty liver, genotype C infection, higher viral load, and with elevated alanine aminotransferase. Longitudinally, participants with higher adiponectin were less likely to achieve surface antigen of hepatitis B virus (HBsAg) seroclearance and more likely to have persistently higher HBV DNA. Eventually, they were more likely to develop liver cirrhosis [OR = 1.65 (0.62-4.39); OR = 3.85 (1.47-10.1); OR = 2.56 (0.96-6.84); OR = 3.76 (1.33-10.7) for the second, third, fourth, and fifth quintiles, respectively; P(trend) = 0.017] before HCC.

CONCLUSIONS

Elevated adiponectin levels were independently associated with an increased risk of HCC.

IMPACT

Adiponectin may play different roles in the virus-induced and metabolic-related liver diseases, but the underlying mechanism remains unknown.

DNA methylation patterns of peroxisome proliferator-activated receptor gamma gene associated with liver fibrosis and inflammation in chronic hepatitis B

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor that regulates gene expression of inflammatory mediators in liver injury. Hepatitis B virus (HBV) suppresses the PPAR gamma-mediated transactivation in liver cancerous cell lines. However, the role of PPAR gamma in patients with chronic HBV infection has not fully demonstrated. Our present study was firstly to determine the clinical relevance of peripheral PPAR gamma mRNA levels in chronic hepatitis B (CHB) patients, and then, the DNA methylation of PPAR gamma promoter was investigated. Peripheral blood mononuclear cells (PBMCs) were isolated from 91 CHB patients and 18 healthy controls. The mRNA level of PPAR gamma was determined by quantitative real-time PCR; meanwhile, the CpG island methylation was assessed by methylation-specific PCR. CHB patients showed significantly lower mRNA level of PPAR gamma than healthy controls (P = 0.005). The mRNA level was decreased in HBV-DNA-positive group than HBV-DNA-negative group (P = 0.041). Interaction analysis demonstrated that the DNA methylation pattern was responsible for the suppression of peripheral PPAR gamma transcription in CHB patients (P = 0.003). Furthermore, the hypermethylation of PPAR gamma gene promoter was significantly associated with liver inflammation and fibrosis in CHB. In conclusion, DNA methylation patterns were responsible for the decreased mRNA level of peripheral PPAR gamma in CHB patients. Liver inflammation and fibrosis were found to be associated with hypermethylation of PPAR gamma promoter.

Serum adiponectin levels are associated with hepatitis B viral load in overweight to obese hepatitis B virus carriers

OBJECTIVE

This study aimed to investigate the association between serum adiponectin and chronic hepatitis B virus (HBV) infection.

DESIGN AND METHODS

We conducted a campus-based cross-sectional study in Northern Taiwan, an HBV-endemic country. A total of 506 participants, including 147 chronic HBV-infected individuals and 359 healthy controls, were assessed for anthropometric indices, serum adiponectin levels, serum HBV viral load and markers, serum alanine aminotransferase levels and metabolic factors.

RESULTS

Older age, male gender, higher alanine aminotransferase, higher body mass index, greater waist circumference, lower fasting glucose, higher triglycerides, and higher adiponectin were associated with chronic HBV infection in univariate analyses. In multivariate analysis, the presence of chronic HBV infection was positively associated with serum adiponectin levels (P < 0.0001) and high adiponectin levels over the 75th percentile (odds ratio, 4.25; 95% confidence interval, 2.36-7.66; P < 0.0001) after adjusting for age, gender, body mass index, and insulin resistance index. Furthermore, serum adiponectin levels were positively associated with HBV viral load in overweight to obese HBV-infected subjects (P = 0.018).

CONCLUSION

Although chronic HBV-infected individuals were heavier than healthy controls, they had significantly higher serum adiponectin levels than healthy counterparts. Additionally, adiponectin levels were positively associated with HBV viral load in overweight to obese HBV-infected subjects. Future research should focus on elucidating adiponectin pathways, which may contribute to the development of adjuvant treatments for chronic HBV infection.

PPARs in Liver Diseases and Cancer: Epigenetic Regulation by MicroRNAs

Peroxisome-proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors that exert in the liver a transcriptional activity regulating a whole spectrum of physiological functions, including cholesterol and bile acid homeostasis, lipid/glucose metabolism, inflammatory responses, regenerative mechanisms, and cell differentiation/proliferation. Dysregulations of the expression, or activity, of specific PPAR isoforms in the liver are therefore believed to represent critical mechanisms contributing to the development of hepatic metabolic diseases, disorders induced by hepatic viral infections, and hepatocellular adenoma and carcinoma. In this regard, specific PPAR agonists have proven to be useful to treat these metabolic diseases, but for cancer therapies, the use of PPAR agonists is still debated. Interestingly, in addition to previously described mechanisms regulating PPARs expression and activity, microRNAs are emerging as new important regulators of PPAR expression and activity in pathophysiological conditions and therefore may represent future therapeutic targets to treat hepatic metabolic disorders and cancers. Here, we reviewed the current knowledge about the general roles of the different PPAR isoforms in common chronic metabolic and infectious liver diseases, as well as in the development of hepatic cancers. Recent works highlighting the regulation of PPARs by microRNAs in both physiological and pathological situations with a focus on the liver are also discussed.

Hepatitis B virus infection and fatty liver in the general population

BACKGROUND & AIMS

In animal studies, expression of hepatitis B virus (HBV) proteins causes hepatic steatosis. We aimed to study the prevalence of fatty liver in people with and without HBV infection in the general population.

METHODS

We performed a cross-sectional population study in Hong Kong Chinese. Intrahepatic triglyceride content (IHTG) was measured by proton-magnetic resonance spectroscopy.

RESULTS

One thousand and thirteen subjects (91 HBV patients and 922 controls) were recruited. The median IHTG was 1.3% (0.2-33.3) in HBV patients and 2.1% (0-44.2) in controls (p <0.001). Excluding subjects with significant alcohol consumption, the prevalence of nonalcoholic fatty liver disease was 13.5% (95% confidence interval [CI] 6.4%, 20.6%) in HBV patients and 28.3% (95% CI 25.3%, 31.2%) in controls (p=0.003). The fatty liver prevalence differed in HBV patients and controls aged 40-59 years but was similar in those aged 60 years or above. After adjusting for demographic and metabolic factors, HBV infection remained an independent factor associated with lower risk of fatty liver (adjusted odds ratio 0.42; 95% CI 0.20, 0.88; p=0.022). HBV patients also had a lower prevalence of metabolic syndrome (11.0% vs. 20.2%; p=0.034), but the difference was mainly attributed to lower triglyceride levels. Among HBV patients, viral genotypes, HBV DNA level and hepatitis B e antigen status were not associated with fatty liver.

CONCLUSIONS

HBV infection is associated with a lower prevalence of fatty liver, hypertriglyceridemia and metabolic syndrome. Viral replication may affect lipid metabolism and this warrants further studies.

Peroxisome proliferator-activated receptor-γ cross-regulation of signaling events implicated in liver fibrogenesis

Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear receptor with transcriptional activity controlling multiple physical and pathological processes. Recently, PPARγ has been implicated in the pathogenesis of liver fibrosis. Its depleted expression has strong associations with the activation and transdifferentiation of hepatic stellate cells, the central event in liver fibrogenesis. Studies over the past decade demonstrate that PPARγ cross-regulates a number of signaling pathways mediated by growth factors and adipokines, and cellular events including apoptosis and senescence. These signaling and cellular events and their molecular interactions with PPARγ system are profoundly involved in liver fibrogenesis. We critically summarize these mechanistic insights into the PPARγ regulation in liver fibrogenesis based on the updated findings in this area. We conclude with a discussion of the impacts of these discoveries on the interpretation of liver fibrogenesis and their potential therapeutic implications. PPARγ activation could be a promising strategy for antifibrotic therapy.