Hepatitis B virus X protein induces hepatic steatosis via transcriptional activation of SREBP1 and PPARgamma

Inverse relationship between hepatic steatosis and hepatitis B viremia: Results of a large case-control study

The potential interaction between chronic hepatitis B (CHB) and nonalcoholic fatty liver disease (NAFLD), two of the most prevalent liver diseases worldwide, has not been well defined. We performed liver stiffness (LS) and controlled attenuation parameter (CAP) measurements using transient elastography in 1202 CHB patients. Of these, 601 steatotic patients were matched with nonsteatotic controls in a 1:1 ratio by age, gender, nucleoside analogue treatment status, and treatment duration. Severe fibrosis was defined according to EASL-ALEH criteria, and steatosis was defined as CAP ≥222 dB m^-1 . Anthropometric measurements and metabolic-related parameters were recorded. The mean age of the 1202 patients (51.4% male) was 51.8 years. 696 patients (57.9%) were on nucleoside analogues for a median duration of 76.2 months. Among treatment-naïve patients, median serum HBV DNA was lower in steatotic individuals than in controls (3.0 vs 3.4 log IU mL^-1 , P < .05), with this inverse relationship remaining significant in multivariate analysis (odds ratio 0.859, 95% CI 0.743-0.994, P < .05). With increased steatosis severity, there was a stepwise decrease in median HBV DNA levels (3.1 and 2.6 log IU mL^-1 in no steatosis and severe steatosis, respectively, P = .032). Steatosis was associated with a higher median LS (5.4 kPa vs 5.0 kPa, P < .001). Severe steatosis, when compared to mild/moderate steatosis, was associated with an increased percentage of severe fibrosis (23.2% and 12.6%, respectively, P = .005). We conclude that severe steatosis was associated with increased fibrosis in CHB patients. Increasing steatosis was independently associated with lower serum HBV DNA levels, suggesting its potential negative effects on viral replication.

Naringenin attenuates hepatitis B virus X protein-induced hepatic steatosis

BACKGROUND

Naringenin (Nar), a common dietary flavonoid abundantly present in fruits, vegetables, and Chinese herbs, is believed to possess strong anti-inflammatory properties and to modulate hepatic apolipoprotein and lipid synthesis. However, there are no reports describing Nar's effects on the hepatitis B virus protein X (HBx) -induced hepatic steatosis, and the detailed molecular mechanisms of the compound's effects are still unclear.

METHODS

Nar was administered by oral gavage to HBx-transgenic mice from 4 to 6 weeks of age. Mice were sacrificed after 14 days of once-daily naringenin administration. Liver tissues and sera were collected for histopathology and biochemical analysis.

RESULTS

Nar counteracted hepatic lipid accumulation and liver dysfunction in HBx-transgenic mice. In addition, Nar significantly decreased expression of adipogenic and lipogenic genes in mice, suggesting that the compound may have therapeutic effects in the early stages of HBx-mediated hepatic steatosis. These results indicated that naringenin inhibits HBx-induced expression of hepatic adipogenic and lipogenic genes through suppression of HBx-induced gene expression, including decreases in the transcriptional activity of SREBP1c, LXRα, and PPARγ in HBx-trangenic mice and HBx-transfected HepG2 cells.

CONCLUSIONS

Results from this study suggested that Nar may serve as a therapeutic agent for preventing HBx-infected hepatic steatosis in humans.

Intracellular hepatitis B virus increases hepatic cholesterol deposition in alcoholic fatty liver via hepatitis B core protein

Hepatitis B virus (HBV) infection is a prevalent infectious disease with serious outcomes like chronic and acute hepatitis, cirrhosis, and hepatocellular carcinoma. However, the metabolic alteration by HBV is rarely taken into consideration. With the high prevalence of alcohol consumption and chronic HBV infection, their overlap is assumed to be an increasing latent hazard; although the extent has not been calculated. Moreover, the impact of chronic alcohol consumption combined with HBV on cholesterol metabolism is unknown. Six-week-old male FVB/Ncrl mice were hydrodynamically injected with a pGEM-4Z-1.3HBV vector and then fed an ethanol diet for 6 weeks. Serum biomarkers and liver histology, liver cholesterol levels, and cholesterol metabolism-related molecules were measured. In vitro assays with HBx, hepatitis B surface (HBs), or hepatitis B core (HBc) protein expression in HepG2 cells costimulated with ethanol were conducted to assess the cholesterol metabolism. HBV expression synergistically increased cholesterol deposition in the setting of alcoholic fatty liver. The increase of intrahepatic cholesterol was due to metabolic alteration in cholesterol metabolism, including increased cholesterol synthesis, decreased cholesterol degradation, and impaired cholesterol uptake. Overexpression of HBV component HBc, but not HBs or HBx, selectively promoted the hepatocellular cholesterol level.

New trends on obesity and NAFLD in Asia

Traditionally, obesity and its related diseases have been considered a problem in Western countries. However, in the past two decades, urbanisation in many Asian countries has led to a sedentary lifestyle and overnutrition, setting the stage for the epidemic of obesity. This article reviews the epidemiological trend of obesity in Asia, with special emphasis on the emerging condition of non-alcoholic fatty liver disease (NAFLD). Currently, the population prevalence of NAFLD in Asia is around 25%, like many Western countries. While hepatocellular carcinoma and end-stage liver disease secondary to NAFLD remain uncommon, a rising trend has emerged. Around 8-19% of Asians with body mass indexes less than 25kg/m² are also found to have NAFLD, a condition often described as "lean" or "non-obese" NAFLD. Although this condition is generally less severe than that in more obese patients, steatohepatitis and fibrotic disease are well recognized. Central adiposity, insulin resistance and weight gain are major risk factors, and genetic predisposition, such as the PNPLA3 polymorphism appears to be more important in the development of NAFLD in the non-obese population. Lifestyle modification remains the cornerstone of management for obesity and NAFLD, but few patients can achieve adequate weight reduction and even fewer can maintain the weight in the long run. While pharmacological agents have entered phase III development for steatohepatitis, Asian patients are under-represented in most drug trials. Future studies should define the optimal management of obesity and NAFLD in Asia.

Hepatitis B virus prevents excessive viral production via reduction of cell death-inducing DFF45-like effectors

The relationship between hepatitis B virus (HBV) infection and lipid accumulation remains largely unknown. In this study, we investigated the effect of HBV propagation on lipid droplet growth in HBV-infected cells and HBV-producing cell lines, HepG2.2.15 and HBV-inducible Hep38.7-Tet. The amount of intracellular triglycerides was significantly reduced in HBV-infected and HBV-producing cells compared with HBV-lacking control cells. Electron and immunofluorescent microscopic analyses showed that the average size of a single lipid droplet (LD) was significantly less in the HBV-infected and HBV-producing cells than in the HBV-lacking control cells. Cell death-inducing DFF45-like effectors (CIDEs) B and C (CIDEB and CIDEC), which are involved in LD expansion for the improvement of lipid storage, were expressed at a significantly lower level in HBV-infected or HBV-producing cells than in HBV-lacking control cells, while CIDEA was not detected in those cells regardless of HBV production. The activity of the CIDEB and CIDEC gene promoters was impaired in HBV-infected or HBV-producing cells compared to HBV-lacking control cells, while CIDEs potentiated HBV core promoter activity. The amount of HNF4α, that can promote the transcription of CIDEB was significantly lower in HBV-producing cells than in HBV-lacking control cells. Knockout of CIDEB or CIDEC significantly reduced the amount of supernatant HBV DNA, intracellular viral RNA and nucleocapsid-associated viral DNA, while the expression of CIDEB or CIDEC recovered HBV production in CIDEB- or CIDEC-knockout cells. These results suggest that HBV regulates its own viral replication via CIDEB and CIDEC.

Prevalence of metabolic syndrome among adults with liver function injury in rural area of Southwest China: A cross-sectional study

Abnormal liver function (ALF) plays a key role in metabolic syndrome (MetS), but only few data on the relationship between MetS and the risk factors for ALF (e.g., biotoxins) are available. We aimed to provide the prevalence of MetS and its association with the risk factors for ALF in rural area of Southwest China. A cross-sectional study within the hepatocellular carcinoma cohort was conducted, and included 5493 people with age from 30 to 85 years old. MetS was defined according to the Joint Scientific Statement. We observed that the prevalence of MetS was 31.8% (39.0% in women and 19.8% in men). Logistic regression analysis showed that significantly increased risk of MetS was found in those showing ALF (OR = 3.00, 95% CI: 2.43–3.71). Significantly decreased risk of MetS was found in those with higher HBV DNA titers (OR = 0.49, 95% CI: 0.33–0.74), and in those with higher aflatoxin B1 exposure (estimated daily intake, EDI) (OR = 0.60, 95% CI: 0.53–0.67). No significant change was found in those with higher microcystin-LR exposure (EDI). Therefore, the different risk factors for ALF might exert different effects on MetS. However, there should be an interaction effect existing that might decide the severity of MetS.

Serum HBV surface antigen positivity is associated with low prevalence of metabolic syndrome: A meta-analysis

Background and aim

As there is conflicting evidence for the relationship between hepatitis B virus surface antigen (HBsAg) positivity and the prevalence of metabolic syndrome (MetS), we performed a meta-analysis to investigate whether HBsAg positivity affects the incidence of MetS.

Methods

Observational studies on the relationship between HBsAg positivity and MetS were obtained from PubMed, Web of Science, and the Cochrane Library in April 2016. The pooled odds ratios (ORs) of MetS and its components (central obesity, increased fasting glucose, increased blood pressure, dyslipidemia) for subjects with or without HBsAg positivity were synthesized. The standardized mean difference of MetS components between HBsAg-positive participants and healthy controls was calculated. Heterogeneity was explored with subgroup analysis and sensitivity analysis. Publication bias was detected using Egger’s test and Begg’s test.

Results

Thirty studies were eligible for meta-analysis. The MetS OR for HBsAg-positive participants was significantly decreased compared with the controls [OR = 0.80, 95% confidence interval (CI), 0.70–0.90]. The negative effect of HBsAg positivity on elevated triglycerides (OR = 0.62, 95% CI, 0.59–0.64) was strong, while that for increased fasting blood glucose was weak (OR = 0.94, 95% CI, 0.90–0.98). The pooled ORs of central obesity (OR = 0.97, 95% CI, 0.91–1.04), reduced high-density lipoprotein cholesterol (OR = 0.98, 95% CI, 0.83–1.14), and elevated blood pressure (OR = 1.00, 95% CI, 0.80–1.25) for HBsAg-positive participants were all not significantly different compared with the controls. No publication bias was detected.

Conclusions

Serum HBsAg positivity is inversely associated with the prevalence of MetS. Among the five components of MetS, elevated triglycerides had the strongest inverse relationship with HBsAg positivity.

The prevalence of steatohepatitis in chronic hepatitis B patients and its impact on disease severity and treatment response

BACKGROUND & AIMS

The clinical significance of steatohepatitis in chronic hepatitis B remains unclear. This study aimed to determine the prevalence and risk factors for steatohepatitis in chronic hepatitis B, and to determine its correlation with liver fibrosis and response to antiviral therapy.

METHODS

Liver histopathology of 256 consecutive chronic hepatitis B patients with serum hepatitis B virus DNA >2000 IU/mL were analysed with clinical and laboratory characteristics. Virological and biochemical responses were prospectively assessed in the 112 patients treated with antiviral monotherapy.

RESULTS

Hepatic steatosis was observed in 38% of the entire cohort, and steatohepatitis was diagnosed in 18% of patients with hepatic steatosis according to Brunt's classification. The presence of steatohepatitis was associated with overweight/obese (odds ratio, 5.99; 95% CI, 1.32-27.2) and hypertriglyceridaemia (odds ratio, 2.95; 95% CI, 1.07-8.15). None of the viral characteristics including HBeAg status, genotypes and viraemia levels was associated with the presence of steatohepatitis. Steatohepatitis was an independent predictor of significant fibrosis (odds ratio, 10.0; 95% CI, 2.08-48.5) and advanced fibrosis (odds ratio, 3.45; 95% CI, 1.11-10.7) after adjusting for viraemia levels and features of the metabolic syndrome. The rates of suppression of serum hepatitis B virus DNA <20 IU/mL combined with aminotransferase normalization at week 48 of antiviral therapy were not different between the steatohepatitis and non-steatohepatitis groups (43% vs 53%; P=.475).

CONCLUSIONS

Steatohepatitis is not uncommon in chronic hepatitis B patients. It is associated with metabolic syndrome but not viral factor. This study demonstrates that steatohepatitis is related to the severity of liver fibrosis but it does not affect response to antiviral therapy.

Tumor stroma with senescence-associated secretory phenotype in steatohepatitic hepatocellular carcinoma

Senescence secretome was recently reported to promote liver cancer in an obese mouse model. Steatohepatitic hepatocellular carcinoma (SH-HCC), a new variant of HCC, has been found in metabolic syndrome patients, and pericellular fibrosis, a characteristic feature of SH-HCC, suggests that alteration of the tumor stroma might play an important role in SH-HCC development. Clinicopathological characteristics and tumor stroma showing senescence and senescence-associated secretory phenotype (SASP) were investigated in 21 SH-HCCs and 34 conventional HCCs (C-HCCs). The expression of α-smooth muscle actin (α-SMA), p21^Waf1/Cif1, γ-H2AX, and IL-6 was investigated by immunohistochemistry or immunofluorescence. SH-HCCs were associated with older age, higher body mass index, and a higher incidence of metabolic syndrome, compared to C-HCC (P <0.05, all). The numbers of α-SMA-positive cancer-associated fibroblasts (CAFs) (P = 0.049) and α-SMA-positive CAFs co-expressing p21^Waf1/Cif1 (P = 0.038), γ-H2AX (P = 0.065), and IL-6 (P = 0.048) were greater for SH-HCCs than C-HCCs. Additionally, non-tumoral liver from SH-HCCs showed a higher incidence of non-alcoholic fatty liver disease and a higher number of α-SMA-positive stellate cells expressing γ-H2AX and p21^Waf1/Cif1 than that from C-HCCs (P <0.05, all). In conclusion, SH-HCCs are considered to occur more frequently in metabolic syndrome patients. Therein, senescent and damaged CAFs, as well as non-tumoral stellate cells, expressing SASP including IL-6 may contribute to the development of SH-HCC.

Bioinformatics analysis of the proteins interacting with LASP-1 and their association with HBV-related hepatocellular carcinoma

LIM and SH3 domain protein (LASP-1) is responsible for the development of several types of human cancers via the interaction with other proteins; however, the precise biological functions of proteins interacting with LASP-1 are not fully clarified. Although the role of LASP-1 in hepatocarcinogenesis has been reported, the implication of LASP-1 interactors in HBV-related hepatocellular carcinoma (HCC) is not clearly evaluated. We obtained information regarding LASP-1 interactors from public databases and published studies. Via bioinformatics analysis, we found that LASP-1 interactors were related to distinct molecular functions and associated with various biological processes. Through an integrated network analysis of the interaction and pathways of LASP-1 interactors, cross-talk between different proteins and associated pathways was found. In addition, LASP-1 and several its interactors are significantly altered in HBV-related HCC through microarray analysis and could form a complex co-expression network. In the disease, LASP-1 and its interactors were further predicted to be regulated by a complex interaction network composed of different transcription factors. Besides, numerous LASP-1 interactors were associated with various clinical factors and related to the survival and recurrence of HBV-related HCC. Taken together, these results could help enrich our understanding of LASP-1 interactors and their relationships with HBV-related HCC.

A Noninvasive Score Model for Prediction of NASH in Patients with Chronic Hepatitis B and Nonalcoholic Fatty Liver Disease

Aims. To develop a noninvasive score model to predict NASH in patients with combined CHB and NAFLD. Objective and Methods. 65 CHB patients with NAFLD were divided into NASH group (34 patients) and non-NASH group (31 patients) according to the NAS score. Biochemical indexes, liver stiffness, and Controlled Attenuation Parameter (CAP) were determined. Data in the two groups were compared and subjected to multivariate analysis, to establish a score model for the prediction of NASH. Results. In the NASH group, ALT, TG, fasting blood glucose (FBG), M30 CK-18, CAP, and HBeAg positive ratio were significantly higher than in the non-NASH group (P < 0.05). Multivariate analysis showed that CK-18 M30, CAP, FBG, and HBVDNA level were independent predictors of NASH. Therefore, a new model combining CK18 M30, CAP, FBG, and HBVDNA level was established using logistic regression. The AUROC curve predicting NASH was 0.961 (95% CI: 0.920-1.00, cutoff value is 0.218), with a sensitivity of 100% and specificity of 80.6%. Conclusion. A noninvasive score model might be considered for the prediction of NASH in patients with CHB combined with NAFLD.

Hepatitis B and concomitant hepatic steatosis

Hepatic steatosis is becoming more common in Asia with prevalence becoming as common as Western countries. Concomitant Hepatitis B and hepatic steatosis is increasingly encountered in clinical practice. The interaction between the two concomitant conditions at both molecular level and clinical outcome remains to be explored. The present review is aimed at summarizing the existing literature on the complex interaction of the two-concomitant disease.

Nonalcoholic fatty liver disease in Asia: emerging perspectives

As in the West, nonalcoholic fatty liver disease (NAFLD) is the commonest chronic liver disease in Asia, with a prevalence higher than 40 % in some countries. The risk factors for NAFLD development are similar to those in Western countries, including increased body mass index, diabetes, insulin resistance, and metabolic syndrome. NAFLD in Asians is associated with different extrahepatic manifestations involving the cardiovascular, gastrointestinal, and renal systems. A considerable proportion of Asians with NAFLD are described as having "lean" NAFLD. Present in approximately 20 % of the Asian population, lean NAFLD is closely linked with insulin resistance, diabetes, and other metabolic complications, but its association with disease progression to nonalcoholic steatohepatitis and cirrhosis remains to be defined. There is emerging evidence of the interactions of NAFLD with hepatitis B virus and hepatitis C virus infection in Asia. Unlike in Western countries, NAFLD constitutes only a minority of cirrhosis and hepatocellular carcinoma cases in Asia. Possible explanations are the lower prevalence of obesity and the overwhelming problem of viral hepatitis in Asia. With aging of the obesity cohort in Asia, NAFLD-related liver complications are expected to increase.

HBx regulates fatty acid oxidation to promote hepatocellular carcinoma survival during metabolic stress

Due to a high rate of nutrient consumption and inadequate vascularization, hepatocellular carcinoma (HCC) cells constantly undergo metabolic stress during tumor development. Hepatitis B virus (HBV) X protein (HBx) has been implicated in the pathogenesis of HBV-induced HCC. In this study, we investigated the functional roles of HBx in HCC adaptation to metabolic stress. Up-regulation of HBx increased the intracellular ATP and NADPH generation, and induced the resistance to glucose deprivation, whereas depletion of HBx via siRNA abolished these effects and conferred HCC cells sensitive to glucose restriction. Though HBx did not affect the glycolysis and oxidative phosphorylation capacity of HCC cells under normal culture conditions, it facilitated fatty acid oxidation (FAO) in the absence of glucose, which maintained NADPH and ATP levels. Further investigation showed that HBx expression, under glucose deprivation, stimulated phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) via a calcium/CaMKK-dependent pathway, which was required for the activation of FAO. Conversely, inhibition of FAO by etomoxir (ETO) restored the sensitivity of HBx-expressing cells to glucose deficiency in vitro and retarded xenograft tumor formation in vivo. Finally, HBx-induced activation of the AMPK and FAO pathways were also observed in xenograft tumors and HBV-associated HCC specimens. Our data suggest that HBx plays a key role in the maintenance of redox and energy homeostasis by activating FAO, which is critical for HCC cell survival under conditions of metabolic stress and might be exploited for therapeutic benefit.

Multi-omics analyses reveal metabolic alterations regulated by hepatitis B virus core protein in hepatocellular carcinoma cells

Chronic hepatitis B virus (HBV) infection is partly responsible for hepatitis, fatty liver disease and hepatocellular carcinoma (HCC). HBV core protein (HBc), encoded by the HBV genome, may play a significant role in HBV life cycle. However, the function of HBc in the occurrence and development of liver disease is still unclear. To investigate the underlying mechanisms, HBc-transfected HCC cells were characterized by multi-omics analyses. Combining proteomics and metabolomics analyses, our results showed that HBc promoted the expression of metabolic enzymes and the secretion of metabolites in HCC cells. In addition, glycolysis and amino acid metabolism were significantly up-regulated by HBc. Moreover, Max-like protein X (MLX) might be recruited and enriched by HBc in the nucleus to regulate glycolysis pathways. This study provides further insights into the function of HBc in the molecular pathogenesis of HBV-induced diseases and indicates that metabolic reprogramming appears to be a hallmark of HBc transfection.

The role of microRNAs in hepatocyte metabolism and hepatitis B virus replication

Though efficient vaccines against hepatitis B virus (HBV) and antiviral therapies are available, chronic HBV infection is still a global health problem. The process of HBV infection and HBV life cycle are extensively studied in last decades, however, the mechanisms of HBV-induced alterations of host cell metabolisms and host factors involved in modulating of viral replication are not fully understood. Thus, it is an important issue to examine these specific HBV-host interactions for development of novel strategies for antiviral therapies. Recently, microRNAs (miRNAs), a class of post-transcriptional regulatory small RNA, seem to be the relevant fine tuning factors of various cellular activities and pathways, including cell growth, metabolism, and viral replication. In this review, we summarize the up to date knowledge concerning the virus-host interactions and emphasizing on the role of miRNAs in regulation of HBV replication and host cell metabolism.

The expression of thymosin β4 in chronic hepatitis B combined nonalcoholic fatty liver disease

The aim of the study was to detect the expression level of thymosin β4 (Tβ4) in serum and tissues of patients with chronic hepatitis B (CHB) combined nonalcoholic fatty liver disease (NAFLD). The effects of Tβ4 in hepatic steatosis, chronic inflammation, and fibrosis development in CHB combined NAFLD patients were also discussed. The study included 46 patients in the case group with CHB and NAFLD and 42 patients in the control group with CHB. ELISA was applied to detect serum Tβ4 and TNF-α level. Furthermore, the correlation analysis of Tβ4 levels with biochemical index, pathological index, and TNF-α level was performed. The Tβ4 immunohistochemical levels of different inflammation fibrosis levels were compared, and the correlation analysis with TNF expression was performed. The Tβ4 levels in patients with CHB combined NAFLD showed no statistical difference when compared to the control group. In patients with CHB combined NAFLD group, the Tβ4 level had no correlation with ALT, AST, TG, FGP, hepatitis B virus (HBV)-DNA levels, and fat grading, but had negative correlation with inflammation score and fibrosis score (P <0.01). The immunohistochemical results of hepatic tissues showed that the expression intensity of severe inflammation fibrosis group had statistical significance compared with that of slight group, and the Tβ4 expression both in serum and in liver tissue negatively correlated with TNF-α expression. Tβ4 could be involved in the regulation of chronic inflammation and fibrosis and plays a defense role in the disease progression of CHB combined NAFLD patients.

Chronic hepatitis B and fatty liver: Issues in clinical management

With an increasing incidence of non-alcoholic fatty livers, the existence of concomitant hepatitis B and fatty liver is becoming more common in clinical practice. In clinical practice, the concomitant existence of hepatitis B and fatty livers raises practical issues in clinical management. It becomes more difficult for the clinician to decide on the mode of treatment in the case of elevated Alanine aminotransferase (ALT) and in deciding potential causes, whether they are related to chronic hepatitis B or to non-alcoholic steatohepatitis (NASH). With evolving changes in the practice and knowledge of non-alcoholic fatty liver disease and chronic hepatitis B, clinical judgment on the predominant disease becomes essential for their coexistence. This short review is aimed at reviewing the evidence available on the frequency of the two diseases existing concomitantly, possible ways of differentiating the two, the prognosis, outcomes of treatment and a possible common pathway.

Hepatic SATB1 induces paracrine activation of hepatic stellate cells and is upregulated by HBx

Chronic hepatitis B virus (HBV) infection is a major cause of chronic liver diseases, but its involvement in hepatic fibrogenesis remains unclear. Special AT-rich binding protein 1 (SATB1) has been implicated in reprogramming chromatin organization and transcription profiles in many cancers and non-cancer-related conditions. We found that hepatic SATB1 expression was significantly up-regulated in fibrotic tissues from chronic hepatitis B virus (HBV)-infected patients and HBV transgenic (HBV-Tg) mouse model. Knockdown of SATB1 in the liver significantly alleviated CCl4-induced fibrosis in HBV-Tg mouse model. Moreover, we suggested HBV encoded x protein (HBx) induced SATB1 expression through activation of JNK and ERK pathways. Enforced expression of SATB1 in hepatocytes promoted the activation and proliferation of hepatic stellate cells (HSCs) by secretion of connective tissue growth factor (CTGF), Interleukin-6 (IL-6) and platelet derived growth factor-A (PDGF-AA). Our findings demonstrated that HBx upregulated hepatic SATB1 which exerted pro-fibrotic effects by paracrine activation of stellate cells in HBV-related fibrosis.

Diagnostic accuracy of APRI and FIB-4 for predicting hepatitis B virus-related liver fibrosis accompanied with hepatocellular carcinoma

BACKGROUND

Aspartate aminotransferase to platelet ratio index (APRI) and the fibrosis index based on four factors (FIB-4) are the two most focused non-invasive models to assess liver fibrosis.

AIMS

We aimed to examine the validity of these two models for predicting hepatitis B virus (HBV)-related liver fibrosis accompanied with hepatocellular carcinoma (HCC).

METHODS

We enrolled HBV-infected patients with liver cancer who had received hepatectomy. The accuracy of APRI and FIB-4 for diagnosing liver fibrosis was assessed based on their sensitivity, specificity, diagnostic efficiency, positive predictive value (PPV), negative predictive value (NPV), kappa (κ) value and area under the receiver-operating characteristic curve (AUC).

RESULTS

Finally 2176 patients were included, with 1682 retrospective subjects and 494 prospective subjects. APRI (rs=0.310) and FIB-4 (rs=0.278) were positively correlated with liver fibrosis. And χ(2) analysis demonstrated that APRI and FIB-4 values correlated with different levels of liver fibrosis with all P values less than 0.01. The AUC values for APRI and FIB-4 were 0.685 and 0.626 (P=0.73) for predicting significant fibrosis, 0.681 and 0.648 (P=0.81) for differentiation of advanced fibrosis and 0.676 and 0.652 (P=0.77) for diagnosing cirrhosis.

CONCLUSION

APRI and FIB-4 correlate with liver fibrosis. However these two models have low accuracy for predicting HBV-related liver fibrosis in HCC patients.

Impact of hepatitis B virus infection on hepatic metabolic signaling pathway

A growing body of epidemiologic research has demonstrated that metabolic derangement exists in patients with hepatitis B virus (HBV) infection, indicating that there are clinical associations between HBV infection and host metabolism. In order to understand the complex interplay between HBV and hepatic metabolism in greater depth, we systematically reviewed these alterations in different metabolic signaling pathways due to HBV infection. HBV infection interfered with most aspects of hepatic metabolic responses, including glucose, lipid, nucleic acid, bile acid and vitamin metabolism. Glucose and lipid metabolism is a particular focus due to the significant promotion of gluconeogenesis, glucose aerobic oxidation, the pentose phosphate pathway, fatty acid synthesis or oxidation, phospholipid and cholesterol biosynthesis affected by HBV. These altered metabolic pathways are involved in the pathological process of not only hepatitis B, but also metabolic disorders, increasing the occurrence of complications, such as hepatocellular carcinoma and liver steatosis. Thus, a clearer understanding of the hepatic metabolic pathways affected by HBV and its pathogenesis is necessary to develop more novel therapeutic strategies targeting viral eradication.

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).

Cooperative effects of hepatitis B virus and TNF may play important roles in the activation of metabolic pathways through the activation of NF-κB

Elevated levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β are often observed in the sera of hepatitis B virus (HBV)-infected patients. It is well known that these cytokines activate nuclear factor-κB (NF-κB)-signaling, and are associated with endoplasmic reticulum (ER) stress. We investigated whether HBV or HBV X protein (HBx) enhanced the activation of NF-κB in the presence of TNF and/or IL-1β, and their effects on the expression of metabolic pathway-associated genes. We examined whether HBV or HBx enhanced cytokine-induced activation of NF-κB in hepatocytes, using a reporter assay, in the presence or absence of TNF and/or IL-1β. The expression of insulin-like growth factor binding protein 1 (IGFBP1), one of the NF-κB target genes was also examined. The expression of metabolic pathway-associated genes in HepG2 and HepG2.2.15 cells in the presence or absence of TNF was evaluated by RT-qPCR. Human hepatocytes expressed TNF receptors and IL-1 receptors. NF-κB was activated by cooperation between HBx and TNF in human hepatocytes. We observed IGFBP1 expression in HBV infection and that a number of metabolic pathway-associated genes were upregulated in HepG2.2.15 cells, compared with HepG2 cells with or without TNF treatment. We observed the cooperative effects of HBV and TNF which enhanced the activation of NF-κB as well as upregulated the expression of metabolic pathway-associated genes in hepatocytes. These effects may be important in the development of HBV-associated metabolic syndrome.

Fatty acid biosynthesis is involved in the production of hepatitis B virus particles

Hepatitis B virus (HBV) proliferates in hepatocytes after infection, but the host factors that contribute to the HBV lifecycle are poorly understood at the molecular level. We investigated whether fatty acid biosynthesis (FABS), which was recently reported to contribute to the genomic replication of hepatitis C virus, plays a role in HBV proliferation. We examined the effects of inhibitors of the enzymes in the FABS pathway on the HBV lifecycle by using recombinant HBV-producing cultured cells and found that the extracellular HBV DNA level, reflecting HBV particle production, was decreased by treatment with inhibitors suppressed the synthesis of long-chain saturated fatty acids with little cytotoxicity. The reduced HBV DNA level was reversed when palmitic acid, which is the product of fatty acid synthase (FAS) during FABS, was used simultaneously with the inhibitor. We also observed that the amount of intracellular HBV DNA in the cells was increased by FAS inhibitor treatment, suggesting that FABS is associated with HBV particle production but not its genome replication. This suggests that FABS might be a potent target for anti-HBV drug with a mode of action different from current HBV therapy.

Relationship Between Hepatic Steatosis and the Elevation of Aminotransferases in HBV-Infected Patients With HBe-Antigen Negativity and a Low Viral Load

Nonalcoholic fatty liver disease has been suggested to be associated with alanine aminotransferase (ALT) elevation in hepatitis B virus (HBV)-infected patients with HBe antigen (HBeAg)-negativity and a low HBV-DNA level. However, few studies have evaluated the association according to histological findings of the liver.Among a total of 198 HBV-infected patients who received a percutaneous liver biopsy, we studied the histological and laboratory findings of HBeAg-negative patients without receiving nucleoside/nucleotide analogues treatment (N = 70) in order to evaluate whether hepatic steatosis and its related metabolic disorders were associated with an elevation in ALT levels in HBeAg-negative patients.In HBeAg-negative patients with a high serum HBV-DNA level (≥2000 IU/mL), the level of HBV-DNA was the only significant factor related to ALT elevation. However, in HBeAg-negative patients with a low HBV-DNA level, the serum ferritin level, and histologically observed hepatic steatosis were significantly associated factors with ALT elevation. When we evaluated 2 metabolic variables (serum ferritin and fasting insulin) that are suggested to be relevant to the presence of progressive disease in Japanese patients, we found that the rate of metabolic disorders was significantly higher among patients with a high ALT level and a low HBV-DNA level than it was among those with other conditions. The triglyceride level and the frequency of moderate or severe hepatic steatosis were significantly higher in patients with a low HBV-DNA level than in those with a high HBV-DNA level.Histologically proven hepatic steatosis and its related metabolic disorders are suggested to be involved in the elevation of aminotransferases of HBeAg-negative patients, particularly those with low HBV-DNA levels.

A "systems medicine" approach to the study of non-alcoholic fatty liver disease

The prevalence of fatty liver (steatosis) in the general population is rapidly increasing worldwide. The progress of knowledge in the physiopathology of fatty liver is based on the systems biology approach to studying the complex interactions among different physiological systems. Similarly, translational and clinical research should address the complex interplay between these systems impacting on fatty liver. The clinical needs drive the applications of systems medicine to re-define clinical phenotypes, assessing the multiple nature of disease susceptibility and progression (e.g. the definition of risk, prognosis, diagnosis criteria, and new endpoints of clinical trials). Based on this premise and in light of recent findings, the complex mechanisms involved in the pathology of fatty liver and their impact on the short- and long-term clinical outcomes of cardiovascular, metabolic liver diseases associated with steatosis are presented in this review using a new "systems medicine" approach. A new data set is proposed for studying the impairments of different physiological systems that have an impact on fatty liver in different subsets of subjects and patients.

Relationship between chronic hepatitis B and metabolic syndrome: A structural equation modeling approach

OBJECTIVE

Investigate the nature of the relationship between chronic hepatitis B virus (HBV) infection and metabolic syndrome among nondiabetic adults.

METHODS

This was a cross-sectional analysis of 17,030 nondiabetic adults (7437 males and 9593 females; mean age, 36.0 ± 3.9 years) in northern Taiwan from 2008 to 2009. The associations of hepatitis B surface antigen (HBsAg) seropositivity with metabolic syndrome and cardio-metabolic parameters were assessed. A structural equation model was constructed to elucidate the pathways between chronic HBV infection and individual cardiometabolic risk factors.

RESULTS

A total of 2982 (17.5%) participants were HBsAg-seropositive. Of the seropositive and seronegative subjects, 15.5 and 16.9% had metabolic syndrome, respectively. The HBsAg-seropositive subjects had a lower odds of having metabolic syndrome compared with the seronegative subjects irrespective of gender and age (OR: 0.76, 95% CI: 0.68-0.85). The inverse associations remained significant after adjusting for body mass index and serum alanine aminotransferase levels. HBsAg seropositivity was inversely associated with hypertriglyceridemia (OR: 0.59, 95% CI: 0.52-0.66), and low serum levels of high-density lipoprotein cholesterol (OR: 0.86, 95% CI: 0.79-0.93) after adjustments. The structural equation model revealed chronic HBV infection had a significant negative effect on dyslipidemia both in males (B = -0.054) and females (B = -0.064).

CONCLUSIONS

The inverse relationship between chronic HBV infection and metabolic syndrome may be attributable to the net beneficial effects on lipid profiles.

Hepatitis B Virus X and Regulation of Viral Gene Expression

The efficient replication of hepatitis B virus (HBV) requires the HBV regulatory hepatitis B virus X (HBx) protein. The exact contributions of HBx are not fully understood, in part because of the limitations of the assays used for its study. When HBV replication is driven from a plasmid DNA, the contribution of HBx is modest. However, there is an absolute requirement for HBx in assays that recapitulate the infectious virus life cycle. There is much evidence that HBx can contribute directly to HBV replication by acting on viral promoters embedded within protein coding sequences. In addition, HBx may also contribute indirectly by modulating cellular pathways to benefit virus replication. Understanding the mechanism(s) of HBx action during virus replication may provide insight into novel ways to disrupt chronic HBV replication.

Hepatitis B Virus X Protein Induces Hepatic Steatosis by Enhancing the Expression of Liver Fatty Acid Binding Protein

Hepatitis B virus (HBV) has been implicated as a potential trigger of hepatic steatosis although molecular mechanisms involved in the pathogenesis of HBV-associated hepatic steatosis still remain elusive. Our prior work has revealed that the expression level of liver fatty acid binding protein 1 (FABP1), a key regulator of hepatic lipid metabolism, was elevated in HBV-producing hepatoma cells. In this study, the effects of HBV X protein (HBx) mediated FABP1 regulation on hepatic steatosis and the underlying mechanism were determined. mRNA and protein levels of FABP1 were measured by quantitative RT-PCR (qPCR) and Western blotting. HBx-mediated FABP1 regulation was evaluated by luciferase assay, coimmunoprecipitation, and chromatin immunoprecipitation. Hepatic lipid accumulation was measured by using Oil-Red-O staining and the triglyceride level. It was found that expression of FABP1 was increased in HBV-producing hepatoma cells, the sera of HBV-infected patients, and the sera and liver tissues of HBV-transgenic mice. Ectopic overexpression of HBx resulted in upregulation of FABP1 in HBx-expressing hepatoma cells, whereas HBx abolishment reduced FABP1 expression. Mechanistically, HBx activated the FABP1 promoter in an HNF3β-, C/EBPα-, and PPARα-dependent manner, in which HBx increased the gene expression of HNF3β and physically interacted with C/EBPα and PPARα. On the other hand, knockdown of FABP1 remarkably blocked lipid accumulation both in long-chain free fatty acids treated HBx-expressing HepG2 cells and in a high-fat diet-fed HBx-transgenic mice. Therefore, FABP1 is a key driver gene in HBx-induced hepatic lipid accumulation via regulation of HNF3β, C/EBPα, and PPARα. FABP1 may represent a novel target for treatment of HBV-associated hepatic steatosis.

IMPORTANCE

Accumulating evidence from epidemiological and experimental studies has indicated that chronic HBV infection is associated with hepatic steatosis. However, the molecular mechanism underlying HBV-induced pathogenesis of hepatic steatosis still remains to be elucidated. In this study, we found that expression of liver fatty acid binding protein (FABP1) was dramatically increased in the sera of HBV-infected patients and in both sera and liver tissues of HBV-transgenic mice. Forced expression of HBx led to FABP1 upregulation, whereas knockdown of FABP1 remarkably diminished lipid accumulation in both in vitro and in vivo models. It is possible that HBx promotes hepatic lipid accumulation through upregulating FABP1 in the development of HBV-induced nonalcoholic fatty liver disease. Therefore, inhibition of FABP1 might have therapeutic value in steatosis-associated chronic HBV infection.

Interactions of Hepatitis B Virus Infection with Nonalcoholic Fatty Liver Disease: Possible Mechanisms and Clinical Impact

Hepatitis B virus (HBV) infection is a major etiology of chronic liver disease worldwide. In the past decade, nonalcoholic fatty liver disease (NAFLD) has emerged as a common liver disorder in general population. Accordingly, the patient number of chronic hepatitis B (CHB) concomitant with NAFLD grows rapidly. The present article reviewed the recent studies aiming to explore the relationship between CHB and NAFLD from different aspects, including the relevant pathogenesis of CHB and NAFLD, the intracellular molecular mechanisms overlaying HBV infection and hepatic steatosis, and the observational studies with animal models and clinical cohorts for analyzing the coincidence of the two diseases. It is concluded that although numerous cross-links have been suggested between the molecular pathways in HBV infection and NAFLD pathogenesis, regarding whether HBV infection can substantially interfere with the occurrence of NAFLD or vice versa in the patients, there is still far from a conclusive agreement.

Association Between Chronic Hepatitis B Virus Infection and Risk of Osteoporosis: A Nationwide Population-Based Study

The effect of hepatitis B virus (HBV) infection on bone mineral density in patients without advanced liver disease remains unclear. Hence, we assessed the association between HBV infection and the risk of osteoporosis. From 2000 to 2011, patients older than 20 years with HBV infection were identified from the Longitudinal Health Insurance Database 2000. Of the 180,730 sampled patients, 36,146 and 144,584 patients were categorized into HBV infection and comparison cohorts, respectively. Compared with the comparison cohort, the HBV infection patients had a higher risk of osteoporosis (adjusted hazard ratio [aHR]: 1.14, 95% confidence interval [CI]: 1.03-1.25) after adjusting for age, sex, frequency of medical visits, and comorbidities of diabetes, hypertension, hyperlipidemia, heart failure, cirrhosis, chronic kidney disease, thyroid diseases, medication of steroid, PPI, warfarin, aspirin, and estrogen replacement therapy. The patients with HBV infection exhibited a 1.13-fold (95% CI = 1.03-1.25) higher risk of developing osteoporosis, but the risk of osteoporotic fracture was comparable between patients with HBV infection and the comparison cohort (aHR = 1.20, 95% CI = 0.77-1.86). The incidence of osteoporosis increased with the increment of age (age  ≤ 49: aHR = 1; age 50-64: aHR = 5.67, 95% CI = 5.09-6.32; age  ≧ 65: aHR = 13.3, 95% CI = 11.8-14.9) and coexisting cirrhosis (aHR = 1.62, 95% CI = 1.24-2.12). However, the osteoporosis risk contributed by HBV infection decreased with age and the age-specific risk analyses showed that patients with HBV infection exhibited the highest risk of osteoporosis than patients without HBV infection for the patients aged ≤49 (aHR = 1.42, 95% CI = 1.19-1.70). Furthermore, the osteoporosis risk contributed by HBV infection has decreased with the presence of comorbidity (aHR = 1.27, 95% CI = 1.09-1.48 vs aHR = 1.04, 95% CI = 0.91-1.15). HBV increases the risk of osteoporosis, but HBV infection may be less influential than other risk factors. Moreover, HBV has no detrimental effect on osteoporotic fracture in this study.

Patatin-Like Phospholipase Domain-Containing 3 I148M Variant Is Associated with Liver Steatosis and Fat Distribution in Chronic Hepatitis B

BACKGROUND

The patatin-like phospholipase domain-containing 3 gene (PNPLA3) has been associated with liver steatosis and disease progression in nonalcoholic steatohepatitis and chronic hepatitis C.

AIMS

The aim of the present study was to evaluate the influence of the PNPLA3 I148M polymorphisms on the clinical, histological, viral, and host parameters in Italian patients with chronic hepatitis B (CHB).

METHODS

Ninety-nine patients with CHB entered the study and underwent a clinical, histological, virological, and biochemical evaluation. PNPLA3 (p.I148M) variants were genotyped.

RESULTS

PNPLA3 rare variant (148M) was significantly associated with liver steatosis (p = 0.0019) and cholesterol (p = 0.04) levels, but not with fibrosis or histological activity index. The 13 patients with severe liver steatosis (score > 3) (38%) were more frequently homozygous for PNPLA3 148M variant than the 86 without (6%, p = 0.003). At logistic regression analysis, severe steatosis was independently associated with the rare allele (p = 0.001) and waist circumference, but not with body mass index (BMI).

CONCLUSIONS

In our CHB patients, the PNPLA3 polymorphisms influenced the development of liver steatosis, but not fibrosis status. The association of PNPLA3 p.I148M with liver steatosis increased with the greater amount of abdominal fat, irrespective of BMI.

Prognostic significance of catalase expression and its regulatory effects on hepatitis B virus X protein (HBx) in HBV-related advanced hepatocellular carcinomas

Hepatitis B virus X protein (HBx) plays a role in liver cancer development. We previously showed that ROS increased HBx levels and here, we investigated the role of antioxidants in the regulation of HBx expression and their clinical relevance. We found that overexpression of catalase induced a significant loss in HBx levels. The cysteine null mutant of HBx (Cys-) showed a dramatic reduction in its protein stability. In clonogenic proliferation assays, Huh7-X cells produced a significant number of colonies whereas Huh7-Cys- cells failed to generate them. The Cys at position 69 of HBx was crucial to maintain its protein stability and transactivation function in response to ROS. Among 50 HBV-related hepatocellular carcinoma (HCC) specimens, 72% of HCCs showed lower catalase levels than those of surrounding non-tumor tissues. In advanced stage IV, catalase levels in non-tumor tissues were increased whereas those in tumors were further reduced. Accordingly, patients with a high T/N ratio for catalase showed significantly longer survival than those with a low T/N ratio. Together, catalase expression in HCC patients can be clinically useful for prediction of patient survival, and restoration of catalase expression in HCCs could be an important strategy for intervention in HBV-induced liver diseases.

Chronic hepatitis B associated with hepatic steatosis, insulin resistance, necroinflammation and fibrosis

BACKGROUND

The effect of hepatitis B virus (HBV) infection on fatty liver disease is unclear.

OBJECTIVES

The aim of this study was to investigate the viral and host causes of fatty liver in chronic hepatitis B (CHB) patients. This study included 88 CHB patients of which 17 were not treated. Liver biopsy was performed in each patient. Group 1 included those with hepatic steatosis (n=28) and group 2 those without hepatic steatosis. The groups were compared in terms of age, body mass index (BMI), Homeostasis Model Assessment- Insulin Resistance (HOMA-IR), viral load, biochemical parameters and histological findings. Patients in group 1 were subdivided according to the degree of steatosis as follows: grade 1 (15 patients, 53.6%), grade 2 (6 patients, 21.4%), and grade 3 (7 patients, 25%).

RESULTS

In group 1 (n=28), mean age, BMI, cholesterol, and HOMA-IR were found to be significantly higher than in group 2 (n=60). There were no significant differences in the positivity of viral load, HbeAg, treatment, fibrosis and other laboratory parameters between the two groups. HOMA-IR was the only independent predictive factor of liver steatosis in patients with CHB in logistic regression analysis.

CONCLUSION

Hepatic steatosis in CHB patients was associated with host metabolic factors.

Hepatic STAMP2 alleviates high fat diet-induced hepatic steatosis and insulin resistance

BACKGROUND & AIMS

Most studies on the role of STAMP2 in metabolism have used adipose tissue. Little knowledge exists concerning the role of STAMP2 in the liver, which is a metabolically central target. We hypothesized that STAMP2 is involved in non-alcoholic fatty liver disease (NAFLD) pathogenesis.

METHODS

We examined our hypothesis using human NAFLD patient pathology samples and a high-fat diet (HFD)-induced NAFLD mouse model. The molecular mechanism underlying hepatic STAMP2-mediated lipid imbalance was explored using an oleic acid (OA)-induced NAFLD in vitro model.

RESULTS

Noticeably, the expression level of STAMP2 protein was reduced in the livers obtained from NAFLD patients and HFD-induced NAFLD mice. In vivo knockdown of hepatic STAMP2 by siRNA accelerated hepatic steatosis and insulin resistance in mice fed a HFD. Conversely, the delivery of adenoviral STAMP2 (Ad-STAMP2) improved hepatic steatosis in HFD-induced NAFLD mice. The expression of lipogenic or adipogenic factors was increased in both in vitro and in vivo NAFLD models but was reversed by Ad-STAMP2. Adenoviral overexpression of STAMP2 improved insulin resistance in the HFD-induced NAFLD mice. In vivo and in vitro assays demonstrated that STAMP2 modulates insulin sensitivity and glucose metabolism and that STAMP2 counteracts OA-induced insulin resistance by modulating insulin receptor substrate-1 stability.

CONCLUSIONS

The present study revealed that hepatic STAMP2 plays a pivotal role in preventing HFD-induced NAFLD and that STAMP2 overexpression improves hepatic steatosis and insulin resistance in NAFLD. Our findings indicate that STAMP2 may represent a suitable target for interventions targeting NAFLD.

The metabolic responses to hepatitis B virus infection shed new light on pathogenesis and targets for treatment

Chronic infection caused by the hepatitis B virus (HBV), is strongly associated with hepatitis, fatty liver and hepatocellular carcinoma. To investigate the underlying mechanisms, we characterize the metabolic features of host cells infected with the virus using systems biological approach. The results show that HBV replication induces systematic metabolic alterations in host cells. HBV infection up-regulates the biosynthesis of hexosamine and phosphatidylcholine by activating glutamine-fructose-6-phosphate amidotransferase 1 (GFAT1) and choline kinase alpha (CHKA) respectively, which were reported for the first time for HBV infection. Importantly suppressing hexosamine biosynthesis and phosphatidylcholine biosynthesis can inhibit HBV replication and expression. In addition, HBV induces oxidative stress and stimulates central carbon metabolism and nucleotide synthesis. Our results also indicate that HBV associated hepatocellular carcinoma could be attributed to GFAT1 activated hexosamine biosynthesis and CHKA activated phosphatidylcholine biosynthesis. This study provides further insights into the pathogenesis of HBV-induced diseases, and sheds new light on drug target for treating HBV infection.

Hepatitis B virus infection and metabolic syndrome: fact or fiction?

Although hepatitis C virus infection is known to be linked with insulin resistance, dyslipidemia, and hepatic steatosis, the relationship between hepatitis B virus (HBV) infection and metabolic factors remains unclear. HBV infection is a health problem worldwide, especially in endemic regions such as Asia and Africa. It induces liver decompensation, cirrhosis, hepatocellualr carcinoma, and premature mortality. The prevalence of metabolic syndrome continues to increase in parallel with the epidemic of obesity, which is closely associated with the development of diabetes, cardiovascular disease, or even cancer. The systemic review shows that chronic HBV infection protects against instead of promotes fatty liver. The mechanism is possibly due to a lower frequency of dyslipidemia profile in patients with chronic HBV infection. The association of HBV with metabolic syndrome, insulin resistance, and the risk of arteriosclerosis is still inconclusive. In addition, obesity, diabetes, and metabolic syndrome may accelerate the progression of liver disease in patients with chronic HBV infection and synergistically induce cirrhosis or even hepatocellualr carcinoma development.

Comparison of diagnostic accuracy of aspartate aminotransferase to platelet ratio index and fibrosis-4 index for detecting liver fibrosis in adult patients with chronic hepatitis B virus infection: a systemic review and meta-analysis

The aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis index based on the four factors (Fibrosis 4 index; FIB-4) are the two most widely studied noninvasive tools for assessing liver fibrosis. Our aims were to systematically review the performance of APRI and FIB-4 in hepatitis B virus (HBV) infection in adult patients and compare their advantages and disadvantages. We examined the diagnostic accuracy of APRI and FIB-4 for significant fibrosis, advanced fibrosis, and cirrhosis based on their sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUROC). Heterogeneity was explored using metaregression. Our systemic review and meta-analysis included 16 articles of APRI only, 21 articles of APRI and FIB-4 and two articles of FIB-4 for detecting different levels of liver fibrosis. With an APRI threshold of 0.5, 1.0, and 1.5, the sensitivity and specificity values were 70.0% and 60.0%, 50.0% and 83.0%, and 36.9% and 92.5% for significant fibrosis, advanced fibrosis, and cirrhosis, respectively. With an FIB-4 threshold of 1.45 and 3.25, the sensitivity and specificity values were 65.4% and 73.6% and 16.2% and 95.2% for significant fibrosis. The summary AUROC values using APRI and FIB-4 for the diagnosis of significant fibrosis, advanced fibrosis, and cirrhosis were 0.7407 (95% confidence interval [CI]: 0.7033-0.7781) and 0.7844 (95% CI: 0.7450-0.8238; (Z = 1.59, P = 0.06), 0.7347 (95% CI: 0.6790-0.7904) and 0.8165 (95% CI: 0.7707-0.8623; Z = 2.01, P = 0.02), and 0.7268 (95% CI: 0.6578-0.7958) and 0.8448 (95% CI: 0.7742-0.9154; (Z = 2.34, P = 0.01), respectively.

CONCLUSIONS

Our meta-analysis suggests that APRI and FIB-4 can identify hepatitis B-related fibrosis with a moderate sensitivity and accuracy.

Hepatocellular carcinoma in chronic HBV-HCV co-infection is correlated to fibrosis and disease duration

Hepatocellular carcinoma (HCC) is a development of severe liver disease frequently due to HBV and/or HCV infection. The aim of this retrospective study was to evaluate the development of HCC in patients with HBV-HCV chronic infection compared with patients with single HBV or HCV infection and the viral and host factors correlated to HCC in co-infected patients. We studied 268 patients with histology proven chronic hepatitis: 56 had HBV-HCV co-infection (HBV-HCV group), 46 had HBV infection (HBV group) and 166 had HCV infection (HCV group). Patients were followed up for at least 3 years. Viral and host factors were studied. HCC was more frequent in HBV-HCV group (14%) compared with HBV (2%, p = 0.006) and HCV monoinfected (4%, p = 0.006). The Mantel-Haenszel test used to investigate the relationship between HBV-HCV co-infection and development of HCC indicated an association between development of HCC and HBV-HCV co-infection (p < 0.001). In the HBV-HCV group, patients with HCC were significantly older (p = 0.000), had longer disease duration (p = 0.001), higher blood glucose levels (p = 0.001), lower levels of steatosis (p = 0.02), higher levels of fibrosis (p = 0.000), higher HCV RNA (p = 0.01) than those without HCC. ALT, lipid profile, PNPLA3 variant distribution and HBV viral load did not differ among co-infected patients with or without HCC. In conclusion HCC was more frequent in our patients with HBV-HCV co-infection, than in those with HBV or HCV mono-infection; possible associated risk factors for HCC development seem a long duration of disease, high levels of fibrosis and carbohydrate intolerance.

Binding of hepatitis B virus to its cellular receptor alters the expression profile of genes of bile acid metabolism

Chronic hepatitis B virus (HBV) infection has been associated with alterations in lipid metabolism. Moreover, the Na+-taurocholate cotransporting polypeptide (NTCP), responsible for bile acid (BA) uptake into hepatocytes, was identified as the functional cellular receptor mediating HBV entry. The aim of the study was to determine whether HBV alters the liver metabolic profile by employing HBV-infected and uninfected human liver chimeric mice. Humanized urokinase plasminogen activator/severe combined immunodeficiency mice were used to establish chronic HBV infection. Gene expression profiles were determined by real-time polymerase chain reaction using primers specifically recognizing transcripts of either human or murine origin. Liver biopsy samples obtained from HBV-chronic individuals were used to validate changes determined in mice. Besides modest changes in lipid metabolism, HBV-infected mice displayed a significant enhancement of human cholesterol 7α-hydroxylase (human [h]CYP7A1; median 12-fold induction; P<0.0001), the rate-limiting enzyme promoting the conversion of cholesterol to BAs, and of genes involved in transcriptional regulation, biosynthesis, and uptake of cholesterol (human sterol-regulatory element-binding protein 2, human 3-hydroxy-3-methylglutaryl-coenzyme A reductase, and human low-density lipoprotein receptor), compared to uninfected controls. Significant hCYP7A1 induction and reduction of human small heterodimer partner, the corepressor of hCYP7A1 transcription, was also confirmed in liver biopsies from HBV-infected patients. Notably, administration of Myrcludex-B, an entry inhibitor derived from the pre-S1 domain of the HBV envelope, provoked a comparable murine CYP7A1 induction in uninfected mice, thus designating the pre-S1 domain as the viral component triggering such metabolic alterations.

CONCLUSION

Binding of HBV to NTCP limits its function, thus promoting compensatory BA synthesis and cholesterol provision. The intimate link determined between HBV and liver metabolism underlines the importance to exploit further metabolic pathways, as well as possible NTCP-related viral-drug interactions.

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.

Quantitative proteomics identifies host factors modulated during acute hepatitis E virus infection in the swine model

Hepatitis E virus (HEV) causes acute enterically transmitted hepatitis. In industrialized countries, it is a zoonotic disease, with swine being the major reservoir of human HEV contamination. The occurrence and severity of the disease are variable, with clinical symptoms ranging from asymptomatic to self-limiting acute hepatitis, chronic infection, or fulminant hepatitis. In the absence of a robust cell culture system or small-animal models, the HEV life cycle and pathological process remain unclear. To characterize HEV pathogenesis and virulence mechanisms, a quantitative proteomic analysis was carried out to identify cellular factors and pathways modulated during acute infection of swine. Three groups of pigs were inoculated with three different strains of swine HEV to evaluate the possible role of viral determinants in pathogenesis. Liver samples were analyzed by a differential proteomic approach, two-dimensional difference in gel electrophoresis, and 61 modulated proteins were identified by mass spectroscopy. The results obtained show that the three HEV strains replicate similarly in swine and that they modulate several cellular pathways, suggesting that HEV impairs several cellular processes, which can account for the various types of disease expression. Several proteins, such as heterogeneous nuclear ribonucleoprotein K, apolipoprotein E, and prohibitin, known to be involved in other viral life cycles, were upregulated in HEV-infected livers. Some differences were observed between the three strains, suggesting that HEV's genetic variability may induce variations in pathogenesis. This comparative analysis of the liver proteome modulated during infection with three different strains of HEV genotype 3 provides an important basis for further investigations on the factors involved in HEV replication and the mechanism of HEV pathogenesis.

IMPORTANCE

Hepatitis E virus (HEV) is responsible for acute hepatitis, with clinical symptoms ranging from asymptomatic to self-limiting acute hepatitis, chronic infection, or fulminant hepatitis. In industrialized countries, HEV is considered an emerging zoonotic disease, with swine being the principal reservoir for human contamination. The viral and cellular factors involved in the replication and/or pathogenesis of HEV are still not fully known. Here we report that several cellular pathways involved in cholesterol and lipid metabolism or cell survival were modulated during HEV infection in the swine model. Moreover, we observed a difference between the different swine strains, suggesting that HEV's genetic variability could play a role in pathogenesis. We also identified some proteins known to be involved in other viral cycles. Our study provides insight into the mechanisms modulated during HEV infection and constitutes a useful reference for future work on HEV pathogenesis and virulence.

Mitochondrial dysfunction in obesity-associated nonalcoholic fatty liver disease: the protective effects of pomegranate with its active component punicalagin

AIMS

Punicalagin (PU) is one of the major ellagitannins found in the pomegranate (Punica granatum), which is a popular fruit with several health benefits. So far, no studies have evaluated the effects of PU on nonalcoholic fatty liver disease (NAFLD). Our work aims at studying the effect of PU-enriched pomegranate extract (PE) on high fat diet (HFD)-induced NAFLD.

RESULTS

PE administration at a dosage of 150 mg/kg/day significantly inhibited HFD-induced hyperlipidemia and hepatic lipid deposition. As major contributors to NAFLD, increased expression of pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukins 1, 4, and 6 as well as augmented oxidative stress in hepatocytes followed by nuclear factor (erythroid-derived-2)-like 2 (Nrf2) activation were normalized through PE supplementation. In addition, PE treatment reduced uncoupling protein 2 (UCP2) expression, restored ATP content, suppressed mitochondrial protein oxidation, and improved mitochondrial complex activity in the liver. In contrast, mitochondrial content was not affected despite increased peroxisomal proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and elevated expression of genes related to mitochondrial beta-oxidation after PE treatment. Finally, PU was identified as the predominant active component of PE with regard to the lowering of triglyceride and cholesterol content in HepG2 cells, and both PU- and PE-protected cells from palmitate induced mitochondrial dysfunction and insulin resistance.

INNOVATION

Our work presents the beneficial effects of PE on obesity-associated NAFLD and multiple risk factors. PU was proposed to be the major active component.

CONCLUSIONS

By promoting mitochondrial function, eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of NAFLD.

Lipid droplets and viral infections

The lifecycle of several viruses is intimately tied to the lipid metabolism of their host cells, and lipid droplets (LDs) have emerged as crucial organelles in the propagation of these viral infections. Investigating the roles of LDs in viral infection requires expertise in both virology and cell metabolism pertaining to LDs. In this review, we offer an updated list and review of the multiples methods we have used in our laboratory to study both the role of LDs in viral infection and the effect of viral infection on cellular LDs, with a special emphasis on hepatitis C virus and other RNA viruses.

The IGF2 mRNA binding protein p62/IGF2BP2-2 induces fatty acid elongation as a critical feature of steatosis

Liver-specific overexpression of the insulin-like growth factor 2 (IGF2) mRNA binding protein p62/IGF2BP2-2 induces a fatty liver, which highly expresses IGF2 Because IGF2 expression is elevated in patients with steatohepatitis, the aim of our study was to elucidate the role and interconnection of p62 and IGF2 in lipid metabolism. Expression of p62 and IGF2 highly correlated in human liver disease. p62 induced an elevated ratio of C18:C16 and increased fatty acid elongase 6 (ELOVL6) protein, the enzyme catalyzing the elongation of C16 to C18 fatty acids and promoting nonalcoholic steatohepatitis in mice and humans. The p62 overexpression induced the activation of the ELOVL6 transcriptional activator sterol regulatory element binding transcription factor 1 (SREBF1). Recombinant IGF2 induced the nuclear translocation of SREBF1 and a neutralizing IGF2 antibody reduced ELOVL6 and mature SREBF1 protein levels. Concordantly, p62 and IGF2 correlated with ELOVL6 in human livers. Decreased palmitoyl-CoA levels, as found in p62 transgenic livers, can explain the lipogenic action of ELOVL6. Accordingly, p62 represents an inducer of hepatic C18 fatty acid production via a SREBF1-dependent induction of ELOVL6. These findings underline the detrimental role of p62 in liver disease.

Fatty acids increase hepatitis B virus X protein stabilization and HBx-induced inflammatory gene expression

The protein level of human hepatitis B virus (HBV) in infection is variable, depending on patient context. We previously reported that HBV X protein (HBx) induces hepatic lipid accumulation and inflammation. Here, we show that abnormal levels of hepatic fatty acids increase HBx protein stability during HBV expression, resulting in the potentiation of HBx-induced inflammation. Reactive oxygen species, Ca(2+) signaling and expression levels of various lipid metabolic genes were investigated in HBx-expressing cells and in HBx transgenic mice. Fatty acids, including palmitate, stearate and oleate, increased HBx protein stability by preventing proteasome-dependent degradation. Hepatic inflammation induced by a high fat diet (HFD) and HBx was measured based on the expression of interleukin-6 and tumor necrosis factor α. In addition, the protein level of HBx increased in HFD-HBx transgenic mice. Reactive oxygen species production and intracellular Ca(2+) signal activation play critical roles in fatty-acid-induced HBx stabilization. Abnormal levels of hepatic fatty acids resulted in synergistic induction of HBx protein and liver inflammatory gene expression through HBx protein stabilization. These results indicate that different fatty acid levels in the liver might affect HBV-induced pathogenesis.

Differential expression of selected candidate genes in bovine embryos produced in vitro and cultured with chemicals modulating lipid metabolism

Lipid accumulated in embryos produced in vitro has been linked to reductions in both quality and postcryopreservation viability. Therefore, the objective of the present study was to investigate the influence of lipid-reducing chemicals on embryo development, quality, and postcryopreservation viability, in addition to expression profiles of selected lipid metabolism-regulating genes. Bovine cumulus-oocyte complexes were matured and fertilized in vitro; eight-cell stage embryos were cultured in IVC medium supplemented with phenazine ethosulfate (PES), L-carnitine (LC), PES + LC, or no supplementation (control). Culturing embryos in medium with LC increased (P < 0.05) blastocyst rate (38.8%) compared with the other groups (control = 28.1%, PES = 27.1%, PES + LC = 26.3%). Embryos cultured with supplements had greater total cell number and fewer apoptotic cells than the control. Cytoplasmic lipid content was reduced, whereas mitochondria density was increased in embryos treated with culture supplements; this was linked to altered expression profiles of selected genes regulating lipid metabolism. For example, transcript abundance of transmembrane lipid gene (SGPP1) was greater in LC- and PES-treated embryos, and they had increased postcryopreservation hatching ability (indicative of embryo cryotolerance). In conclusion, the two lipid metabolism regulators added to the culture media had improved embryo quality and cryotolerance, but embryo development rate and downstream lipid metabolism-regulating genes were more influenced with LC supplementation.

Fatty acid elongation in non-alcoholic steatohepatitis and hepatocellular carcinoma

Non-alcoholic steatohepatitis (NASH) represents a risk factor for the development of hepatocellular carcinoma (HCC) and is characterized by quantitative and qualitative changes in hepatic lipids. Since elongation of fatty acids from C16 to C18 has recently been reported to promote both hepatic lipid accumulation and inflammation we aimed to investigate whether a frequently used mouse NASH model reflects this clinically relevant feature and whether C16 to C18 elongation can be observed in HCC development. Feeding mice a methionine and choline deficient diet to model NASH not only increased total hepatic fatty acids and cholesterol, but also distinctly elevated the C18/C16 ratio, which was not changed in a model of simple steatosis (ob/ob mice). Depletion of Kupffer cells abrogated both quantitative and qualitative methionine-and-choline deficient (MCD)-induced alterations in hepatic lipids. Interestingly, mimicking inflammatory events in early hepatocarcinogenesis by diethylnitrosamine-induced carcinogenesis (48 h) increased hepatic lipids and the C18/C16 ratio. Analyses of human liver samples from patients with NASH or NASH-related HCC showed an elevated expression of the elongase ELOVL6, which is responsible for the elongation of C16 fatty acids. Taken together, our findings suggest a detrimental role of an altered fatty acid pattern in the progression of NASH-related liver disease.