Update on viral hepatitis: 2008

Synthetic mimetics assigned a major role to IFNAR2 in type I interferon signaling

Type I interferons (IFNs) are potent inhibitors of viral replication. Here, we reformatted the natural murine and human type I interferon-α/β receptors IFNAR1 and IFNAR2 into fully synthetic biological switches. The transmembrane and intracellular domains of natural IFNAR1 and IFNAR2 were conserved, whereas the extracellular domains were exchanged by nanobodies directed against the fluorescent proteins Green fluorescent protein (GFP) and mCherry. Using this approach, multimeric single-binding GFP-mCherry ligands induced synthetic IFNAR1/IFNAR2 receptor complexes and initiated STAT1/2 mediated signal transduction via Jak1 and Tyk2. Homodimeric GFP and mCherry ligands showed that IFNAR2 but not IFNAR1 homodimers were sufficient to induce STAT1/2 signaling. Transcriptome analysis revealed that synthetic murine type I IFN signaling was highly comparable to IFNα4 signaling. Moreover, replication of vesicular stomatitis virus (VSV) in a cell culture-based viral infection model using MC57 cells was significantly inhibited after stimulation with synthetic ligands. Using intracellular deletion variants and point mutations, Y510 and Y335 in murine IFNAR2 were verified as unique phosphorylation sites for STAT1/2 activation, whereas the other tyrosine residues in IFNAR1 and IFNAR2 were not involved in STAT1/2 phosphorylation. Comparative analysis of synthetic human IFNARs supports this finding. In summary, our data showed that synthetic type I IFN signal transduction is originating from IFNAR2 rather than IFNAR1.

Chronic hepatitis B: the demise of the 'inactive carrier' phase

Chronic hepatitis B (CHB) remains a global healthcare burden. Although the recent developments in the field have led to a reduction in incidence, the morbidity and mortality including liver cirrhosis and hepatocellular carcinoma (HCC) remain a formidable challenge. Advances in understanding the immunopathogenesis of CHB have led to a recent change in clinical categorization. EASL introduced the term hepatitis B 'e' antigen (HBeAg)-negative chronic infection, to replace the historical term 'inactive carrier' disease phase, the commonest CHB phase. Although this disease phase is associated with a favorable prognosis, it is not a truly 'inactive' disease phase with no ostensible liver disease, as inferred by the previous anachronistic terminology, and the risk of spontaneous reactivation and the potential risk of disease progression and HCC development are not negligible. Likewise, the APASL also uses the term "Incidentally Detected Asymptomatic Hepatitis B surface antigen (HBsAg)-positive Subject (IDAHS)", comprising all HBsAg-positive subjects who are incidentally detected during routine tests, without any previous or present symptoms of liver disease. This entity includes HBV infection with varied stages of liver disease. Antiviral treatment is generally reserved for patients with active inflammation and/or at risk of disease progression and HCC development. HBsAg loss is considered an optimal treatment endpoint, and may also be achievable in HBeAg-negative chronic infection and IDAHS. In light of this, and the emerging novel HBV therapies, lowering the treatment threshold and a 'Treat All' approach should now be considered. In this review, we summarize the literature and guidance on HBeAg-negative chronic infection, and we make a concerted effort to present the reasons why the one-dimensional term 'inactive carrier' should be abandoned.

Liver disease referrals to an urban, hospital-based hepatology outpatient clinic over the past 25 years

Background

Additional hepatologists are required to manage the rapidly increasing number of patients with liver disease. One disincentive to trainees considering a career in hepatology is the longstanding perception that outpatient hepatology consists largely of managing patients with alcohol‐induced liver disease (ALD).

Objectives

To document the types of liver diseases and changes in liver disease referrals to an urban outpatient liver disease clinic over the past 25 years.

Methods

The nature of the liver disorder, age, gender, and socioeconomic status of patients referred to an urban, hospital‐based, liver diseases outpatient program were documented from 1992 to 2017. Joinpoint analysis was performed to identify significant trends in referral prevalence rates of various disorders.

Results

In 1992/1993, hepatitis C virus (HCV), followed by hepatitis B virus (HBV), “other”, non‐alcoholic fatty liver disease (NAFLD), and primary biliary cholangitis (PBC) were the most common underlying liver diseases in referred patients (39, 36, 12, 4.5, and 3.5% respectively), whereas in 2016/2017, NAFLD, HBV, HCV, “other,” and ALD were most common (60, 15, 12, 8.7, and 3.3%, respectively). Aside from NAFLD referrals, which consistently increased over the 25‐year period, the prevalence of all other liver disease referrals fluctuated but generally declined. Recently referred patients were significantly older (38 ± 13 years in 1992/1993 and 49 ± 15 years in 2016/2017, P < 0.0001), while gender and socioeconomic status have not changed.

Conclusions

Hepatology is a diverse, dynamic subspecialty where ALD continues to constitute less than 5% of all patient referrals.

Hepcidin and IL-1β

Hepcidin expression is determined through transcriptional regulation by systemic iron status. However, acute or chronic inflammation also increases the expression of hepcidin, which is associated with the dysregulation of iron metabolism in pathological conditions. Interleukin (IL)-6 has been suggested to be a principal molecule to confer inflammation-related hepcidin transcription, which is mediated via signal transducer and activator of transcription (STAT)-binding site on the hepcidin promoter. Recently, it has been uncovered that another pro-inflammatory cytokine IL-1β stimulates hepcidin expression through the distinct mechanism underlying IL-6-mediated hepcidin transcription. In addition to IL-6 induction, IL-1β stimulates expression of CCAAT-enhancer-binding protein (C/EBP)δ, a transcription factor, leading to transcriptional activation of hepcidin via C/EBP-binding site on the hepcidin promoter. Thus, hepcidin transcription is stimulated through multiple elements in response to proinflammatory cytokines. Relationships between increased production of IL-1β and dysregulated iron metabolism have been suggested in various diseases, which may be linked to overproduction of hepcidin.

The feasibility of discontinuing lamivudine in lamivudine-resistant chronic hepatitis B patients on lamivudine and adefovir combination therapy

OBJECTIVES

This study investigated the antiviral efficacy of adefovir (ADV) rescue therapy and the feasibility of lamivudine (LAM) discontinuation in LAM-resistant chronic hepatitis B (CH-B) patients who had attained a virological response (VR) with LAM + ADV combination therapy.

METHODS

The VR and virological breakthrough (VBT) were analyzed in 106 consecutively enrolled LAM-resistant CH-B patients who received ADV rescue therapy during a mean follow-up period of 55.2 months. Seventy-four patients achieved VR, and were divided into the LAM-discontinuation group (n = 39) and the LAM-continuation group (n = 35). The VR and VBT between the 2 groups were compared.

RESULTS

For all 106 LAM-resistant CH-B patients, the overall cumulative probabilities of VR at 1, 2, 3 and 5 years of ADV rescue therapy were 40.6, 55.7, 64.6 and 81.3%, respectively. The cumulative probabilities of VBT at 1, 2, 3 and 5 years were 0, 2.9, 8.8 and 13.9%, respectively. Whether they discontinued or continued LAM after achieving VR on LAM + ADV therapy, VR and VBT were not significantly different during a mean follow-up period of 40.4 months.

CONCLUSIONS

There was a good long-term VR with ADV rescue therapy for LAM-resistant CH-B patients. Moreover, discontinuing LAM was found to be feasible for patients who attained VR during ADV + LAM therapy.

Molecular epidemiology and genotyping of hepatitis B virus of HBsAg-positive patients in Oman

Background

Hepatitis B virus (HBV) infection is a major global health burden with distinct geographic public health significance. Oman is a country with intermediate HBV carrier prevalence; however, little is known about the incidence of HBV variants in circulation. We investigated the HBV genotype distribution, the occurrence of antiviral resistance, and HBV surface antigen (HBsAg) escape mutations in HBsAg-positive patients in Oman.

Methods

Serum samples were collected from 179 chronically HBV-infected patients enrolled in various gastroenterology clinics in Oman. HBV genotypes were determined by sequencing and phylogenetic analysis. Mutations in the HBV polymerase and the HBsAg gene were characterized by mutational analysis.

Results

HBV genotypes D (130/170; 76.47%) and A (32/170; 18.28%) are predominant in Oman. The HBV genotypes C and E were less frequent (each 1.18%), while the HBV genotypes B, G, F, and H were not detected. Four patients revealed HBV genotype mixtures (HBV-A/D and D/C). The analyses of vaccine escape mutations yield that 148/170 (87.06%) HBV sequences were wild type. 22/170 (12.94%) HBV sequences showed mutations in the “a” determinant of the HBsAg domain. Two patients showed the described HBV vaccine escape mutation sP120T. 8/146 (5.48%) HBV isolates harbored mutations in the HBV polymerase known to confer resistance against antiviral therapy. Especially the lamivudine resistance mutations rtL180M/rtM204V and rtM204I were detected.

Conclusion

This study shows the distribution of HBV genotypes, therapy resistance, and vaccine escape mutations in HBV-infected patients in Oman. Our findings will have a major impact on therapy management and diagnostics of chronic HBV infections in Oman to control HBV infection in this intermediate HBV-endemic country.

Comparison of the efficacy of Lamivudine plus adefovir versus entecavir in the treatment of Lamivudine-resistant chronic hepatitis B: a systematic review and meta-analysis

BACKGROUND

Hepatitis B virus infection remains 1 of the major health threats worldwide. Currently, lamivudine plus adefovir combination therapy or entecavir monotherapy is usually used for the treatment of patients with lamivudine-resistant chronic hepatitis B (CHB). However, there are few systematic comparisons between the efficacy of lamivudine plus adefovir and the efficacy of entecavir in the treatment of these patients.

OBJECTIVE

The goal of this systematic study and meta-analysis was to assess the efficacy of lamivudine plus adefovir compared with entecavir for the treatment of patients with lamivudine-resistant CHB.

METHODS

A comprehensive literature search of PUBMED, Web of Science, WANFANG database, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Review, were screened to obtain citations from January 1990 to January 2012 in this study. Data analysis was done by using the Review Manager Software 5.1.

RESULTS

Eight studies were suitable for analysis. A total of 696 patients with lamivudine-resistant CHB were studied and grouped according to treatment: 341 patients in the entecavir group and 355 patients in the lamivudine plus adefovir group. The results found that the rates of undetectable hepatitis B virus DNA levels, alanine aminotransferase normalization, hepatitis B e antigen loss, and hepatitis B e antigen seroconversion were not significantly different between the lamivudine plus adefovir group and the entecavir group. Moreover, the rate of adverse reactions was also not significantly different between the 2 groups. However, virologic breakthrough for the patients with lamivudine resistance was higher in the entecavir group than in the lamivudine plus adefovir group.

CONCLUSIONS

For these CHB patients with lamivudine resistance, lamivudine plus adefovir was a better treatment option than entecavir alone.

Combination lamivudine and adefovir versus entecavir for the treatment of naïve chronic hepatitis B patients: a pilot study

BACKGROUND

The aim of this study was to compare the effect of combination lamivudine (LAM) and adefovir dipivoxil (ADV) versus entecavir (ETV) monotherapy for naïve HBeAg-positive chronic hepatitis B (CHB) patients.

MATERIAL/METHODS

Fifty enrolled patients with CHB were evenly divided into 2 groups: a group treated with of lamivudine (LAM) (100 mg/day) plus adefovir (ADV) (10 mg/day) combination, and a group treated with entecavir (ETV) (0.5 mg/day). Serum levels of ALT, AST, creatinine, bilirubin, HBsAg, HBeAg and HBV viral load, and genotypic resistance were analyzed at 0, 12, 24, 52, and 104 weeks. HBV DNA levels were determined by real-time PCR and HBsAg and HBeAg by chemiluminescence. Serum levels of ALT, AST, creatinine, and bilirubin were measured by an automatic biochemical analyzer. Data analysis was performed with SPSS 12.0 software.

RESULTS

There were no significant differences in the virological response (VR) rates between LAM+ADV and ETV cohorts at 24, 52, and 104 weeks (P>0.05). The HBeAg seroconversion rates were 28% and 20%, and the biochemical response (BR) rates were 88% and 84% at week 104 in the LAM+ADV and ETV groups, respectively. The rates of undetectable HBV DNA, HBeAg seroconversion, and ALT normalization rates were similar in both cohorts. No virological breakthrough or serious adverse effects were noted for any patient during the study period.

CONCLUSIONS

Both LAM+ADV combination therapy and ETV monotherapy were effective and safe in the treatment of -naïve HBeAg-positive CHB patients. However, further studies are needed to obtain long-term results.

De novo combination of lamivudine and adefovir versus entecavir monotherapy for the treatment of naïve HBeAg-negative chronic hepatitis B patients

PURPOSE

Either combination treatment or monotherapy using agents with a high genetic barrier are recommended for hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). The aim of this study was to compare effect of naïve HBeAg-negative CHB patients with either de novo combination of lamivudine (LAM) and adefovir dipivoxil (ADV) or entecavir (ETV) monotherapy.

METHODS

HBeAg-negative CHB patients (n = 71) with ALT levels between 2 and 10 times the upper normal limit and HBV DNA levels >10(4) copies/mL were enrolled. Patients were treated with either LAM 100 mg plus ADV 10 mg per day (n = 31) or ETV 0.5 mg per day (n = 40) for 48 weeks.

RESULTS

The average reduction in HBV DNA level compared with baseline were 5.16 ± 1.69 log in the LAM + ADV group and 5.36 ± 1.70 log in the ETV group by week 48 (P = 0.624). The virological response (VR) rates were 80.65 and 77.5%, the biochemical response (BR) rates were 93.55 and 90.00% at week 48 in the LAM + ADV and ETV groups, respectively. There was no significant difference in the VR and BR between the two groups. During the 48-week treatment period, virological breakthrough and serious side effects were not noted in any patient.

CONCLUSIONS

Both LAM + ADV combination therapy and ETV monotherapy are effective in naïve HBeAg-negative CHB patients, but further studies are needed to obtain long-term results.

Pediatric viral hepatitis: avoiding liver failure

Acute liver failure (ALF) is defined as a multisystem disorder of severe impairment of liver function, with or without encephalopathy, which is associated with hepatocellular necrosis (reflected as liver synthetic failure in patients with no recognized chronic liver disease), and can lead to death. ALF can be due to hepatotoxic drugs, natural toxins, autoimmune disease, severe bacterial infection and some neoplastic processes, or ALF can be idiopathic. In the pediatric group, the most frequent cause is viral agents; hepatitis A is the most common among these. The pathophysiologic changes in ALF consist of alterations in coagulation, elevated serum ammonia, hypoalbuminemia and hypoglycemia. In recent years, N-acetylcysteine has been utilized to treat this condition. Using this drug during the early stages of the disease has the potential to improve outcomes for the patient, including the avoidance liver transplantation. This article focuses on the criteria that help to identify ALF and emphasizes accessible alternative medical treatments.

Antiviral activity of 5'-O-carbonate-2',3'-dideoxy-3'-thiacytidine prodrugs against hepatitis B virus in HepG2 2.2.15 cells

The antiviral activities of lamivudine (3TC; 2',3'-dideoxy-3'-thiacytidine) and six 5'-O-carbonates of 3TC were determined by inhibition of hepatitis B virus (HBV) replication in HepG2 2.2.15 cells. HBV DNA in cell supernatants was quantified by real-time polymerase chain reaction (PCR). The results showed that 3TC-Etha was six times more active than 3TC and that 3TC-Buta, 3TC-Hexa and 3TC-Octa were approximately three times more active than 3TC. In contrast, 3TC-Penta and 3TC-Metha showed anti-HBV activity similar to that of the parent compound 3TC. In conclusion, 5'-O-carbonates of 3TC appear to be promising candidates as anti-HBV compounds. This modification could optimise the use of 3TC, a well-tolerated, effective and inexpensive drug, in monotherapy or combined therapy for chronic HBV infections as well as human immunodeficiency virus (HIV)/HBV co-infections.

Hepatitis B e antigen seroconversion: a critical event in chronic hepatitis B virus infection

BACKGROUND

Replication of hepatitis B virus (HBV) is the primary driver of disease progression and clinical outcomes in patients with chronic hepatitis B (CHB), but other factors, such as hepatitis B e antigen (HBeAg) status, also influence disease course. The importance of HBeAg seroconversion is underscored by current CHB treatment guidelines that recommend limiting the duration of antiviral therapy in HBeAg-positive patients who achieve seroconversion.

AIMS

A 2-day meeting of leading hepatologists with extensive experience managing patients with CHB in the Asia-Pacific region was held with the overall goals of reviewing and evaluating (1) available data on the relationship between HBeAg seroconversion and clinical outcomes for patients with HBeAg-positive CHB, and (2) the ways in which seroconversion should influence patient management.

CONCLUSIONS

It was agreed that HBeAg seroconversion is an important serologic end point for patients with CHB and that achieving this goal should be an important consideration in treatment selection. Patients with HBeAg-positive CHB should consider pegylated interferon if they are aged < 40 years (especially women), have lower HBV DNA levels, can afford this treatment, and have a lifestyle that would support adherence to injection therapy. Alternatively, nucleos(t)ide analogs are recommended in patients with alanine aminotransferase levels ≥ 2 × the upper limit of normal, HBV DNA levels < 9 log(10) IU/ml, and compensated CHB. Entecavir, telbivudine, and tenofovir may be used as first-line therapy; they can be administered as a finite therapeutic course in HBeAg-positive patients who seroconvert. Telbivudine and tenofovir should be considered in women of child-bearing potential.

Plasma prohepcidin levels in patients with chronic viral hepatitis: relationship with liver fibrosis

OBJECTIVES

Iron is deemed to play a crucial role in the pathophysiology of liver damage in patients with chronic viral hepatitis. Hepcidin has recently emerged as the key hormone in the regulation of iron balance and recycling. We assessed plasma prohepcidin levels in patients with chronic viral hepatitis and investigated the association of this molecule with iron parameters, histologic activity index, and liver fibrosis scores.

METHODS

We enrolled 35 patients with chronic hepatitis C, 27 with chronic hepatitis B, and 21 healthy controls. Plasma levels of prohepcidin were measured by enzyme-linked immunosorbent assay.

RESULTS

Mean prohepcidin levels were significantly lower in patients with chronic hepatitis B than in those with chronic hepatitis C (P<0.001) and healthy comparison controls (P<0.05). In patients with chronic hepatitis C, prohepcidin was independently associated with liver fibrosis scores (beta=-0.009, standard error=0.003, P<0.05). No association of prohepcidin with iron parameters was found.

CONCLUSION

Significantly lower prohepcidin levels are frequently found in patients with chronic hepatitis B. Levels of this molecule may represent a biochemical correlate of fibrosis in chronic hepatitis C virus infection.