Inhibition of alpha interferon (IFN-α)-induced microRNA-122 negatively affects the anti-hepatitis B virus efficiency of IFN-α. J Virol. 2013;87:137-147. [PMID: 23055569 DOI: 10.1128/jvi.01710-12]

Emerging Therapies for Chronic Hepatitis B and the Potential for a Functional Cure

Worldwide, an estimated 296 million people are living with chronic hepatitis B virus (HBV) infection, with a significant risk of morbidity and mortality. Current therapy with pegylated interferon (Peg-IFN) and indefinite or finite therapy with nucleoside/nucleotide analogues (Nucs) are effective in HBV suppression, hepatitis resolution, and prevention of disease progression. However, few achieve hepatitis B surface antigen (HBsAg) loss (functional cure), and relapse often occurs after the end of therapy (EOT) because these agents have no direct effect on durable template: covalently closed circular DNA (cccDNA) and integrated HBV DNA. Hepatitis B surface antigen loss rate increases slightly by adding or switching to Peg-IFN in Nuc-treated patients and this loss rate greatly increases up to 39% in 5 years with finite Nuc therapy with currently available Nuc(s). For this, great effort has been made to develop novel direct-acting antivirals (DAAs) and immunomodulators. Among the DAAs, entry inhibitors and capsid assembly modulators have little effect on reducing HBsAg levels; small interfering RNA, antisense oligonucleotides, and nucleic acid polymers in combination with Peg-IFN and Nuc may reduce HBsAg levels significantly, even a rate of HBsAg loss sustained for > 24 weeks after EOT up to 40%. Novel immunomodulators, including T-cell receptor agonists, check-point inhibitors, therapeutic vaccines, and monoclonal antibodies may restore HBV-specific T-cell response but not sustained HBsAg loss. The safety issues and the durability of HBsAg loss warrant further investigation. Combining agents of different classes has the potential to enhance HBsAg loss. Compounds directly targeting cccDNA would be more effective but are still in the early stage of development. More effort is required to achieve this goal.

Genome-wide DNA methylation pattern in whole blood of patients with coal-burning arsenic poisoning

Exposure to coal-burning arsenic leads to an increased risk of cancer, multi-systems damage and chronic diseases, with DNA methylation one potential mechanism of arsenic toxicity. There are few studies on genome-wide methylation in the coal-burning arsenic poisoning population. Illumina 850 K methylation beadchip is the most suitable technology for DNA methylation of epigenome-wide association analysis. This study used 850 K to detect changes in Genome-wide DNA methylation in whole blood samples of 12 patients with coal-burning arsenic poisoning ( Arsenic poisoning group) and four healthy control participants (Healthy control group). There is clearly abnormal genome-wide DNA methylation in coal-burning arsenic poisoning, with 647 significantly different methylation positions, 524 different methylation regions and 335 significantly different methylation genes in arsenic poisoning patients compared with healthy controls. Further functional analysis of Gene ontology (GO) and Kyoto encyclopedia of genes (KEGG) found 592 GO items and 131 KEGG pathways between patients of coal-burning arsenic poisoning and healthy control. Then, analysis of gene degree and combined-score identified NAPRT1, NT5C3B, NEDD4L, SLC22A3 and RAB11B as target genes. Further validation by qRT-PCR indicates that mRNA expression of five genes changes significantly in the arsenic poisoning group (n = 72) compared to the healthy control group (n = 72). These results showed the genome-wide methylation pattern and highlighted five critical genes within the coal-burning arsenic poisoning population that involve Nicotinate and nicotinamide metabolism, Choline metabolism in cancer, and Ubiquitin mediated proteolysis. Next, the methylation profile of coal burning arsenic poisoning will be further excavation and the mechanism of coal burning arsenic poisoning will be further explored from five genes related pathways and functions.

Interferon and interferon-stimulated genes in HBV treatment

Human hepatitis B virus (HBV) is a small enveloped DNA virus with a complex life cycle. It is the causative agent of acute and chronic hepatitis. HBV can resist immune system responses and often causes persistent chronic infections. HBV is the leading cause of liver cancer and cirrhosis. Interferons (IFNs) are cytokines with antiviral, immunomodulatory, and antitumor properties. IFNs are glycoproteins with a strong antiviral activity that plays an important role in adaptive and innate immune responses. They are classified into three categories (type I, II, and III) based on the structure of their cell-surface receptors. As an effective drug for controlling chronic viral infections, Type I IFNs are approved to be clinically used for the treatment of HBV infection. The therapeutic effect of interferon will be enhanced when combined with other drugs. IFNs play a biological function by inducing the expression of hundreds of IFN-stimulated genes (ISGs) in the host cells, which are responsible for the inhibiting of HBV replication, transcription, and other important processes. Animal models of HBV, such as chimpanzees, are also important tools for studying IFN treatment and ISG regulation. In the present review, we summarized the recent progress in IFN-HBV treatment and focused on its mechanism through the interaction between HBV and ISGs.

Role of MicroRNAs in the Development of Chronic Liver Disease in Hepatitis Virus-Infected Egyptian Population

Background:  The identification of miRNAs that play a role in the regulation of the viral life cycle and its related liver illness opens the door to the development of diagnostic biomarkers that can categorize patients at higher risk for developing end-stage liver disease. This study was designed to investigate the role of miRNAs in the development of viral hepatitis-induced chronic liver disease (CLD) in the Egyptian population, as well as their potential as possible diagnostic biomarkers for chronic hepatitis virus infection. Methodology: The study involved 100 CLD patients; 55 cases of hepatitis C virus (HCV) and 45 cases of non-viral hepatitis, in addition to 40 healthy controls. The expression of five miRNAs (miR‐30, miR‐122, miR‐296, miR‐351, and miR‐431) was assessed using real-time PCR. Results: Serum levels of miR‐30, miR‐122, miR‐296, miR‐351, and miR‐431 were significantly higher in all patients than the control group (p<0.01). Also, they were significantly greater in viral hepatitis cases compared to the non-viral hepatitis group (p<0.01). The sensitivities and specificities of miR-122a, miR‐30, miR‐296, miR‐351, and miR‐431 were (85.71%, 83.33%), (82.35%, 83.33%), (85.71%, 69.44%), (88.64%, 75.76%), and (87.80%, 65.79%), respectively. Conclusions: miR‐30, miR‐122, miR‐296, miR‐351, and miR‐431 play key roles in the development of CLD as a consequence of viral infection. So, they have the potential to be targeted for the early detection of chronic hepatitis virus infection and allow for exploring a new frontier in the discovery of innovative therapeutics to combat chronic viral infection and its serious life-threatening complications including liver cancer.

Bta-miR-677 contribute to interferon pathway affecting the proliferation of caprine parainfluenza virus type 3

Caprine parainfluenza virus type 3 (CPIV3), a new strain of virus, was isolated from the goats in 2014 in China. Studies have shown that viral infection can induce changes in the expression profile of host miRNAs, which modulate natural immune responses and viral infection. In this study, we report that bta-miR-677 suppressed CPIV3 replication in Madin-Darby bovine kidney (MDBK) cells and guinea pigs. Bta-miR-677 overexpression promoted type I interferon (IFN-I) and IFN-stimulated genes (ISGs) production, thereby inhibiting CPIV3 replication, while bta-miR-677 inhibitor suppressed the antiviral innate immune response to promoted viral replication in MDBK cells. We showed that bta-miR-677 suppresses CPIV3 replication via directly targeted the 3'-untranslated region (3'-UTR) of mitochondrial antiviral signaling protein (MAVS) thus enhancing IFN pathway in MDBK cells. We also demonstrated that bta-miR-677 agomir could inhibit CPIV3 proliferation in guinea pigs, with much lower viral RNA levels in lung and trachea. Guinea pigs showed no obvious pathological changes and less severe lung lesions in bta-miR-677 agomir treated group at 7 dpi. This study contributes to our understanding of the molecular mechanisms underlying CPIV3 pathogenesis.

Suppression of Interferon-α Treatment Response by Host Negative Factors in Hepatitis B Virus Infection

Chronic hepatitis B virus (CHB) infection remains a major global public health issue for which there is still lacking effective curative treatment. Interferon-α (IFN-α) and its pegylated form have been approved as an anti-HBV drug with the advantage of antiviral activity and host immunity against HBV infection enhancement, however, IFN-α treatment failure in CHB patients is a challenging obstacle with 70% of CHB patients respond poorly to exogenous IFN-α treatment. The IFN-α treatment response is negatively regulated by both viral and host factors, and the role of viral factors has been extensively illustrated, while much less attention has been paid to host negative factors. Here, we summarized evidence of host negative regulators and parameters involved in IFN-α therapy failure, review the mechanisms responsible for these effects, and discuss the possible improvement of IFN-based therapy and the rationale of combining the inhibitors of negative regulators in achieving an HBV cure.

Evaluation of miR-122 Serum Level and IFN-λ3 Genotypes in Patients with Chronic HCV and HCV-Infected Liver Transplant Candidate

BACKGROUND

Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are the most common markers of liver damage, but serum level interpretation can be complicated. In hepatocytes, microRNA-122 (miR-122) is the most abundant miRs and its high expression in the serum is a characteristic of liver disease.

OBJECTIVE

We aimed to compare the circulatory level of miR-122 in patients with Chronic Hepatitis C (CHC), Hepatitis C Virus (HCV) infected Liver Transplant Candidates (LTC) and healthy controls to determine if miR-122 can be considered as an indicator of chronic and advanced stage of liver disease.

METHODS

MiR-122 serum level was measured in 170 Interferon-naïve (IFN-naïve) CHC patients, 62 LTC patients, and 132 healthy individuals via TaqMan real-time PCR. Serum levels of miR-122 were normalized to the serum level of Let-7a and miR-221. Also, the ALT and AST levels were measured.

RESULTS

ALT and AST activities and the expression of circulatory miR-122 were similar in the CHC and LTC groups, but it had significantly increased compared to healthy individuals (P<0.001 and P<0.001, respectively). Up-regulation of miR-122 in the sample of patients with normal ALT and AST activities was also observed, indicating that miR-122 is a good marker with high sensitivity and specificity for diagnosing liver damage.

CONCLUSION

miR-122 seemed to be more specific for liver diseases in comparison with the routine ALT and AST liver enzymes. Since the lower levels of circulating miR-122 were observed in the LTC group compared to the CHC group, advanced liver damages might reduce the release of miR-122 from the hepatocytes, as a sign of liver function deficiency.

PD-L1 upregulation by IFN-α/γ-mediated Stat1 suppresses anti-HBV T cell response

Programmed death ligand 1 (PD-L1) has been recently shown to be a major obstacle to antiviral immunity by binding to its receptor programmed death 1 (PD-1) on specific IFN-γ producing T cells in chronic hepatitis B. Currently, IFN-α is widely used to treat hepatitis B virus (HBV) infection, but its antiviral effect vary greatly and the mechanism is not totally clear. We found that IFN-α/γ induced a marked increase of PD-L1 expression in hepatocytes. Signal and activators of transcription (Stat1) was then identified as a major transcription factor involved in IFN-α/γ-mediated PD-L1 elevation both in vitro and in mice. Blockage of the PD-L1/PD-1 interaction by a specific mAb greatly enhanced HBV-specific T cell activity by the gp96 adjuvanted therapeutic vaccine, and promoted HBV clearance in HBV transgenic mice. Our results demonstrate the IFN-α/γ-Stat1-PD-L1 axis plays an important role in mediating T cell hyporesponsiveness and inactivating liver-infiltrating T cells in the hepatic microenvironment. These data raise further potential interest in enhancing the anti-HBV efficacy of IFN-α and therapeutic vaccines.

Targeting Host Innate and Adaptive Immunity to Achieve the Functional Cure of Chronic Hepatitis B

Despite the availability of an effective preventive vaccine for hepatitis B virus (HBV) for over 38 years, chronic HBV (CHB) infection remains a global health burden with around 257 million patients. The ideal treatment goal for CHB infection would be to achieve complete cure; however, current therapies such as peg-interferon and nucleos(t)ide analogs are unable to achieve the functional cure, the newly set target for HBV chronic infection. Considering the fact functional cure has been accepted as an endpoint in the treatment of chronic hepatitis B by scientific committee, the development of alternative therapeutic strategies is urgently needed to functionally cure CHB infection. A promising target for future therapeutic strategies is immune modulation to restore dysfunctional HBV-specific immunity. In this review, we provide an overview of the progress in alternative therapeutic strategies, including immune-based therapeutic approaches that enhance host innate and adaptive immunity to achieve and increase the functional cure from CHB infection.

The response of hepatitis B virus genotype to interferon is associated with a mutation in the interferon-stimulated response element

Genetic variation and genotype of Hepatitis B virus (HBV) are related to the efficiency of interferon alpha (IFN-α)-based antiviral therapy. However, the correlation of variation in interferon-stimulated response element (ISRE) and HBV genotype response to IFN-α therapy remains elusive.Differences of ISRE between genotype B and C HBV were explored using the HBV sequences retrieved from GenBank, and further investigated by ISRE region cloning and sequencing from 60 clinical samples post-IFN-α therapy. Additionally, ISRE mutants were constructed and their relation to responsiveness of IFN-α was evaluated by real-time PCR and Southern blot analysis.ISRE pattern between genotype B and C were found based on both clinical sample sequencing and full-length sequence alignment. The primary difference is the fourth base within the ISRE region, with T and C for genotype B and C, respectively. HBV with genotype C-type ISRE had a higher replicative capability as compared to HBV with genotype B-type ISRE after IFN-α treatment in huh7 cells. CONCLUSION:: Preference of ISRE between genotype B and C HBV are distinct. Single nucleotide difference (C to T) within the HBV ISRE region may link to the efficacy of IFN-α therapy to genotype B and C HBV. Therefore, this study provides a clue for the determination of IFN-α therapy response to HBV treatment.

Association of the S267F variant on NTCP gene and treatment response to pegylated interferon in patients with chronic hepatitis B: a multicentre study

BACKGROUND

Sodium taurocholate co-transporting polypeptide (NTCP) is a cell receptor for HBV. The S267F variant on the NTCP gene is inversely associated with the chronicity of HBV infection, progression to cirrhosis and hepatocellular carcinoma in East Asian populations. The aim of this study was to determine whether the S267F variant was associated with response to pegylated interferon (PEG-IFN) in patients with chronic HBV infection.

METHODS

A total of 257 patients with chronic HBV, treated with PEG-IFN for 48 weeks, were identified from 13 tertiary hospitals included in the hepatitis B database of the Thai Association for the Study of the Liver (THASL).

RESULTS

Of these, 202 patients were infected with HBV genotype C (84.9%); 146 patients were hepatitis B e antigen (HBeAg)-positive (56.8%). Genotypic frequencies of the S267F polymorphism were 85.2%, 14.8% and 0% for the GG, GA and AA genotypes, respectively. S267F GA was associated with sustained alanine aminotransferase (ALT) normalization (OR = 3.25, 95% CI 1.23, 8.61; P=0.02) in HBeAg-positive patients. Patients with S267F variant tended to have more virological response, sustained response with hepatitis B surface antigen (HBsAg) loss at 24 weeks following PEG-IFN treatment. There was no association between the S267F variant and improved patient outcomes in HBeAg-negative patients.

CONCLUSIONS

The S267F variant on the NTCP gene is independently associated with sustained normalization of ALT following treatment with PEG-IFN in patients with HBV infection who are HBeAg-positive. The findings of this study provide additional support for the clinical significance of the S267F variant of NTCP beyond HBV entry.

Steroid receptor coactivator 3 inhibits hepatitis B virus gene expression through activating Akt signaling to prevent HNF4α nuclear translocation

Background

Chronic hepatitis B virus (HBV) infection is one of the most serious global public health problems. The role of steroid receptor coactivator 3 (SRC-3) in HBV biosynthesis is unknown. The aim of this study is to investigate the function of SRC-3 in regulating HBV biosynthesis both in vitro and in vivo and to identify the underlying mechanism.

Results

In this study, we found that knockdown of SRC-3 could increase the levels of HBV mRNA and HBV proteins HBsAg and HBeAg in human liver cancer cell line HepG2 transfected with pHBV1.3 plasmids. In contrast, enforced expression of SRC-3 in SRC-3-knockdown HepG2 cells reduced the levels of HBV mRNA and HBV proteins HBsAg and HBeAg. Knockdown of SRC-3 dampened the Akt signaling, which has been shown to play a negative role in HBV transcription. Ectopic expression of constitutively activated Akt impaired the enhancement of HBV transcription by SRC-3 knockdown, indicating that SRC-3 inhibits HBV transcription by enhancing Akt signaling. Both SRC-3 and constitutively activated Akt could inhibit hepatocyte nuclear factor 4α (HNF4α)-mediated upregulation of HBV core promoter activity by preventing HNF4α nuclear translocation. Consistent with the in vitro results, in an in vivo chronic HBV replication mouse model developed by hydrodynamic injection of pHBV1.3 plasmids into mouse tail vein, enforced expression of SRC-3 in mouse liver reduced the levels of HBV mRNA in the liver and HBV antigens in serum, whereas knockout of SRC-3 in mouse increased the levels of HBV mRNA in the liver and HBV antigens in the serum.

Conclusion

Our study suggests that SRC-3 inhibits HBV gene expression by activating Akt signaling to prevent HNF4α nuclear translocation.

Electronic supplementary material

The online version of this article (10.1186/s13578-019-0328-5) contains supplementary material, which is available to authorized users.

A peptide-based inhibitor of gp96 suppresses HBsAg expression and HBV replication by upregulation of p53

In hepatitis B virus (HBV) infection, the virus produces redundant hepatitis B surface antigen (HBsAg) that plays a key role in driving T-cell tolerance and viral persistence. However, currently available anti-HBV agents have no direct effect on HBsAg transcription and protein expression. In this study, we designed a heat shock protein gp96 inhibitor p37 with the cell penetrating peptide PTD (protein transduction domain of trans-activator of transcription), which mediated p37 internalization into hepatocytes. PTD-p37 effectively suppressed HBsAg expression and viral replication both in vitro and in vivo. We further provide evidence that PTD-p37 suppressed HBV enhancer/promoter activity via p53 upregulation. Moreover, PTD-p37 had antiviral activity against a lamivudine-resistant HBV strain. Considering that suppression of HBsAg expression is a major goal for treatment of HBV infection, our results provide a basis for developing a new therapeutic approaches targeting host factors against viral expression.

Long Non-coding RNAs: Regulators of Viral Infection and the Interferon Antiviral Response

Interferons (IFNs) are a family of cytokines providing a robust first line of host innate defense against pathogenic infection, and have now been part of the standard treatment for viral infection. However, IFN based therapy can best be described as modestly effective. Long non-coding RNAs (lncRNAs) are a novel class of non-protein-coding RNAs that are capable of regulating gene expression at different levels, including chromatin, transcription, post-transcription, and translation. Recently, lncRNAs are found to be deregulated upon viral infection or IFN treatment, and some of them can modulate viral infection in an IFN-dependent or -independent manner. Due to the crucial roles of lncRNAs in viral infection and the IFN antiviral response, the modulation of specific lncRNAs may be involved to increase the IFN antiviral response and improve the clinical result of IFN-based therapy. In this review, we summarize lncRNAs that are deregulated by viral infection, with special focus on the functions and underlying mechanisms of some essential lncRNAs, and discuss their roles in viral infection and the antiviral response of IFN.

Positive Regulation of Hepatitis E Virus Replication by MicroRNA-122

The molecular mechanisms of liver pathology and clinical disease in hepatitis E virus (HEV) infection remain unclear. MicroRNAs (miRNAs) are known to modulate viral pathogenesis either by directly altering viral gene expression or by enhancing cellular antiviral responses. Given the importance of microRNA-122 (miR-122) in liver pathobiology, we investigated possible role of miR-122 in HEV infection. In silico predictions using HEV genotype 1 (HEV-1), HEV-2, HEV-3, and HEV-4 sequences showed that the majority of genomes (203/222) harbor at least one miR-122/microRNA-122-3p (miR-122*) target site. Interestingly, HEV-1 genomes showed a highly (97%) conserved miR-122 target site in the RNA-dependent RNA polymerase (RdRp) region (RdRp_c). We analyzed the significance of miR-122 target sites in HEV-1/HEV-3 (HEV-1/3) genomes by using a replicon-based cell culture system. HEV infection did not change the basal levels of miR-122 in hepatoma cells. However, transfection of these cells with miR-122 mimics enhanced HEV-1/3 replication and depletion of miR-122 with inhibitors led to suppression of HEV-1/3 replication. Mutant HEV-1 replicons with an altered target RdRp_c sequence (CACTCC) showed a drastic decrease in virus replication, whereas introduction of alternative miR-122 target sites in mutant replicons rescued viral replication. There was enrichment of HEV-1 RNA and miR-122 molecules in RNA-induced silencing complexes in HEV-infected cells. Furthermore, pulldown of miR-122 molecules from HEV-infected cells resulted in pulldown of HEV genomic RNA along with miR-122 molecules. These observations indicate that miR-122 facilitates HEV-1 replication, probably via direct interaction with a target site in the viral genome. The positive role of miR-122 in viral replication presents novel opportunities for antiviral therapy and management of hepatitis E.IMPORTANCE Hepatitis E is a problem in both developing and developed countries. HEV infection in most patients follows a self-limited course; however, 20% to 30% mortality is seen in infected pregnant women. HEV superinfections in patients with chronic hepatitis B or hepatitis C virus infections are associated with adverse clinical outcomes, and both conditions warrant therapy. Chronic HEV infections in immunocompromised transplant recipients are known to rapidly progress into cirrhosis. Currently, off-label use of ribavirin (RBV) and polyethylene glycol-interferon (PEG-IFN) as antiviral therapy has shown promising results in both acute and chronic hepatitis E patients; however, the teratogenicity of RBV limits its use during pregnancy, while alpha IFN (IFN-α) increases the risk of transplant rejections. Experimental data determined with genotype 1 virus in the current study show that miR-122 facilitates HEV replication. These observations present novel opportunities for antiviral therapy and management of hepatitis E.

Inducible microRNA-122 modulates RIG-I signaling pathway via targeting DAK in miiuy croaker after poly(I:C) stimulation

MicroRNA-122 (miR-122) was originally identified in mouse and then lots of researches on miR-122 had been performed in mammals. However, the functional study of miR-122 were restricted in fish. In miiuy croaker, miR-122 is sensitive to poly(I:C) stimulation. In this study, a combination of bioinformatics and experimental techniques were used to investigate the functions of miR-122. DAK is a putative target gene of miR-122 which was predicted by bioinformatics, and further the luciferase reporter assays were used to confirm the target sites in DAK 3'untranslated region. The inhibiting effect of miR-122 mimics or pre-miR-122 on DAK presented the dose and time dependent manners, and the pre-miR-122 showed stronger inhibiting effect on DAK than the miR-122 mimics. Therefore, the miR-122 participate in regulating RIG-I-like receptors signaling pathway via inhibiting DAK which is the inhibitors of MDA5. The expression of miR-122 and DAK showed negative relationship in both miiuy croaker spleen and macrophages, which imply that miR-122 may regulate DAK at the post-transcriptional level. These results will enhance our understanding about the regulation of miRNAs on immune response in fish.

Long Non-Coding RNAs in Hepatitis B Virus-Related Hepatocellular Carcinoma: Regulation, Functions, and Underlying Mechanisms

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death in the world. Hepatitis B virus (HBV) and its X gene-encoded protein (HBx) play important roles in the progression of HCC. Although long non-coding RNAs (lncRNAs) cannot encode proteins, growing evidence indicates that they play essential roles in HCC progression, and contribute to cell proliferation, invasion and metastasis, autophagy, and apoptosis by targeting a large number of pivotal protein-coding genes, miRNAs, and signaling pathways. In this review, we briefly outline recent findings of differentially expressed lncRNAs in HBV-related HCC, with particular focus on several key lncRNAs, and discuss their regulation by HBV/HBx, their functions, and their underlying molecular mechanisms in the progression of HCC.

Circulating miR-210 and miR-22 combined with ALT predict the virological response to interferon-alpha therapy of CHB patients

Interferon-alpha (IFN-α) therapy of chronic hepatitis B (CHB) patients is constrained by limited response and side effects. We described a panel of circulating microRNAs (miRNAs) which could potentially predict outcome of IFN-α therapy. Here, we report development of a simplified scoring model for personalized treatment of CHB patients. 112 CHB patients receiving IFN-α treatment were randomly divided into a training (n = 75) or a validation group (n = 37). The expression of 15 candidate miRNAs was detected in training group with 5 miRNAs exhibiting significantly different levels (p < 0.0001) between early virological response (EVR) and non-early virological response (N-EVR). These 5 miRNAs were further tested in validation phase. Refinement analyses of results from training phase established a model composed of miR-210, miR-22 and alanine aminotransferase (ALT), with area under ROC curve (AUC) of 0.874 and 0.816 in training and validation groups, respectively. In addition, this model showed prognostic value for sustained virological response (SVR) (AUC = 0.821). Collectively, this simplified scoring model composed of miR-210, miR-22 and ALT can reproducibly predict the EVR and SVR of IFN-α therapy in CHB patients. The model should help to forecast the outcome of IFN-α treatment prior to therapy decision involving nucleoside analogs or IFNs.

Development of a Novel Site-Specific Pegylated Interferon Beta for Antiviral Therapy of Chronic Hepatitis B Virus

Although nucleot(s)ide analogues and pegylated interferon alpha 2a (PEG-IFN-α2a) can suppress hepatitis B virus (HBV) replication, it is difficult to achieve complete HBV elimination from hepatocytes. A novel site-specific pegylated recombinant human IFN-β (TRK-560) was recently developed. In the present study, we evaluated the antiviral effects of TRK-560 on HBV replication in vitro and in vivo. In vitro and in vivo HBV replication models were treated with antivirals including TRK-560, and changes in HBV markers were evaluated. To analyze antiviral mechanisms, cDNA microarray analysis and an enzyme-linked immunoassay (ELISA) were performed. TRK-560 significantly suppressed the production of intracellular HBV replication intermediates and extracellular HBV surface antigen (HBsAg) (P < 0.001 and P < 0.001, respectively), and the antiviral effects of TRK-560 were enhanced in combination with nucleot(s)ide analogues, such as entecavir and tenofovir disoproxil fumarate. The reduction in HBV DNA levels by TRK-560 treatment was significantly higher than that by PEG-IFN-α2a treatment both in vitro and in vivo (P = 0.004 and P = 0.046, respectively), and intracellular HBV covalently closed circular DNA (cccDNA) reduction by TRK-560 treatment was also significantly higher than that by PEG-IFN-α2a treatment in vivo (P = 0.0495). cDNA microarrays and ELISA for CXCL10 production revealed significant differences between TRK-560 and PEG-IFN-α2a in the induction potency of interferon-stimulated genes. TRK-560 shows a stronger antiviral potency via higher induction of interferon-stimulated genes and stronger stimulation of immune cell chemotaxis than PEG-IFN-α2a. As HBsAg loss and HBV cccDNA eradication are important clinical goals, these results suggest a potential role for TRK-560 in the development of more effective treatment for chronic hepatitis B infection.

Regulation of type I interferon signaling in immunity and inflammation: A comprehensive review

Type I interferons (IFNs) play essential roles in establishing and modulating host defense against microbial infection via induction of IFN-stimulated genes (ISGs) through Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. However, dysregulation of IFNs production and function could also mediate immune pathogenesis such as inflammatory autoimmune diseases and infectious diseases via aberrantly activating inflammatory responses or improperly suppressing microbial controls. Thus, IFN responses need to be tightly regulated to achieve protective immunity against microbial infection while avoiding harmful toxicity caused by improper or prolonged IFN signaling. Multiple levels of cellular and molecular events act in a cooperated manner to regulate IFN responses, in especial, post-translational modification (PTMs) of signaling molecules and epigenetic modification of gene expression programs are two important mechanisms for regulation of IFN signaling and thus critical for orchestrating IFN-mediated host immune response to the complex pathogenic or environmental stimuli. Conventional PTMs such as phosphorylation and polyubiquitylation, as well as numerous other PTMs including acetylation, ISGylation, SUMOylation and methylation have been shown to potently modulate type I IFN signaling transduction via targeting distinct signaling steps or components. Moreover, epigenetic mechanisms, such as histone modification, DNA methylation, non-coding RNAs play critical roles in regulating chromatin structure and function, leading to flexible and dynamic gene expression patterns downstream type I IFN signaling. Herein, we summarize the recent advances in the PTMs and epigenetic mechanisms in regulation of type I IFN signaling and responses. The involvement of dysregulated IFN signaling in inflammatory and autoimmune diseases are also discussed.

The mechanism of apoliprotein A1 down-regulated by Hepatitis B virus

Background

Hepatitis B virus (HBV) infection correlated with the development of cirrhosis, liver failure and hepatocellular carcinoma (HCC), poses a huge health burden on the global community. However, the pathogenesis of chronic hepatitis B (CHB) remains unclear. Apolipoprotein A1 (ApoA1) mainly secreted by hepatocytes, represents the major protein component of high-density lipoprotein. ApoA1 secretion may be disrupted by HBV infection. In this study, we mainly investigated the molecular mechanism of ApoA1 down regulated by HBV for revealing the pathogenesis of CHB.

Methods

ApoA1 expression in livers of CHB patients as well as healthy controls were performed by Real-time PCR (RT-PCR) and Western blot. The serum ApoA1 levels were measured by Enzymed-linked immunosorbent assay (ELISA). Expression of ApoA1 mRNA and protein levels were performed by RT-PCR and Western blot in human hepatoma HepG2 cells and subline HepG2.2.15 cells. HBV expression construct, pHBV1.3 were transfected into HepG2, the changes of ApoA1 mRNA and protein expression were detected by RT-PCR and Western blot. To further study the mechanism of ApoA1 down regulation by HBV, 11 CpG islands in ApoA1 promotor were tested for DNA methylation status by MSP. HepG2.2.15 cell lines were treated with DNA methyltransferase inhibitor 5-aza-deoxycytidine (5-aza-dC), then, expression of ApoA1 mRNA and HBV particles in the supernatant, as well as ApoA1 protein levels were detected by RT-PCR and Western blot. Secretion of HBsAg and HBeAg in HepG2 cells cotransfected with pApoA1 and pHBV1.3 constructs was tested by ELISA. Meanwhile, secretion of HBsAg and HBeAg in the supernatant were quantified by ELISA in the HepG2.2.15 cells treated with 5-aza-dC plus ApoA1 siRNA.

Results

Expression of ApoA1 mRNA and protein levels, as well as serum ApoA1 levels in CHB patients were decreased corresponding healthy controls in vivo. In addition, the expression of ApoA1 mRNA and protein levels were down regulated in HepG2.2.15 cells correponding HepG2 cells, 11 CpG islands in ApoA1 promoter were tested for methylation status by MSP in HepG2.2.15 cells compared to HepG2 cells, while two CpG islands were found hypermethylated. Expression of ApoA1 mRNA and protein levels were increased in HepG2.2.15 cells treated with DNA methyltransferase inhibitor 5-aza-dC. Furthermore, overexpression of ApoA1 can enhance HBV expression in HepG2 cells while the inhibitory effect of 5-aza-dC on HBV expression was completely abolished by blocking 5-aza-dC-induced up-regulation of ApoA1 using RNAi.

Conclusions

Epigenetic silencing of ApoA1 gene expression by CpG island DNA hypermethylation induced by HBV may contribute to the pathogenesis of CHB.

PTD-fused p53 as a potential antiviral agent directly suppresses HBV transcription and expression

In Hepatitis B virus (HBV) infection, the virus generates numerous viral mRNAs/proteins and viral loads, which plays a major role in driving T cell tolerance, viral persistence, and hepatocellular carcinoma. However, currently available anti-HBV agents have no direct effect on viral mRNA transcription and protein expression. In this study, we designed a recombinant fusion of p53 protein with the cell-penetrating peptide PTD (protein transduction domain of trans-activator of transcription), which mediated p53 internalization into hepatocytes. PTD-p53 effectively suppressed HBV transcription and antigen expression by interaction with viral enhancers. We further provide evidence that PTD-p53 counteracts the viral transcription feedback loop and effectively suppressed HBV production of viral mRNAs, as well as HBsAg, HBeAg, and HBcAg, both in vitro and in vivo. Our results thereby provide a basis for developing a new therapeutic approach against HBV infection.

A Pilot Study of MicroRNAs Expression Profile in Serum and HBsAg Particles: Predictors of Therapeutic Vaccine Efficacy in Chronic Hepatitis B Patients

Chronic hepatitis B (CHB) remains a global health problem. Therapeutic vaccination has been successfully employed to treat a subpopulation of CHB patients. Personalized treatment can not only improve therapeutic efficacy, but also decrease the cost of medical care. Since microRNAs (miRNAs) are highly conserved and are involved in many cellular processes, exploring their expression profiles in CHB patients in association with responsiveness to therapeutic vaccination may be an approach for personalized treatment. In this study, we examined the kinetic expression profiles of 13 miRNAs in sera and serum-derived hepatitis surface antigen (HBsAg) particles in 10 CHB patients including 5 responders and 5 nonresponders selected from a large cohort of 136 patients enroled in a phase III clinical trial using antigen-antibody immunogenic complex based therapeutic vaccine (YIC). Eight miRNAs were detected in both sera and HBsAg particles. Among them, the levels of serum miRNAs and serum-derived HBsAg-carried miRNAs (let-7f, miR-22, miR-30a, and miR-122) were significantly lower in the responders group compared to those in the nonresponders group at baseline and throughout the course of treatment. The lower baseline levels of serum miRNAs and HBsAg-carried miRNAs were also associated with hepatitis e antigen clearance at week 76 and hepatitis e antigen seroconversion during the study period. In summary, our study suggests that lower baseline levels of serum miRNAs and HBsAg-carried miRNAs (let-7f, miR-22, miR-30a, and miR-122) associated with YIC treatment response and the variation trend of these 4 miRNAs could have a prognostic value for responsiveness to YIC treatment.

Present and future therapies of hepatitis B: From discovery to cure

Hepatitis B virus (HBV) is a significant global pathogen, infecting more than 240 million people worldwide. While treatment for HBV has improved, HBV patients often require lifelong therapies and cure is still a challenging goal. Recent advances in technologies and pharmaceutical sciences have heralded a new horizon of innovative therapeutic approaches that are bringing us closer to the possibility of a functional cure of chronic HBV infection. In this article, we review the current state of science in HBV therapy and highlight new and exciting therapeutic strategies spurred by recent scientific advances. Some of these therapies have already entered into clinical phase, and we will likely see more of them moving along the development pipeline.

CONCLUSION

With growing interest in developing and efforts to develop more effective therapies for HBV, the challenging goal of a cure may be well within reach in the near future.

IFN-α-Induced Downregulation of miR-221 in Dendritic Cells: Implications for HCV Pathogenesis and Treatment

Although interferon (IFN)-α is known to exert immunomodulatory and antiproliferative effects on dendritic cells (DCs) through induction of protein-coding IFN-stimulated genes (ISGs), little is known about IFN-α-regulated miRNAs in DCs. Since several miRNAs are involved in regulating DC functions, it is important to investigate whether IFN-α's effects on DCs are mediated through miRNAs as well. In this study, we examined miRNA expression patterns in myeloid DCs (mDCs) and plasmacytoid DCs after exposing them to IFN-α. We report that IFN-α downregulates miR-221 in both DC subsets via inhibition of STAT3. We validated proapoptotic proteins BCL2L11 and CDKN1C as miR-221 targets suggesting that IFN-α can induce DC apoptosis via miR-221 downregulation. In addition, we validated another miR-221 target, SOCS1, which is known to be a negative regulator of JAK/STAT signaling. Consistent with this, miR-221 overexpression in mDCs enhanced the secretion of proinflammatory cytokines IL-6 and TNF-α. In peripheral blood mononuclear cells (PBMCs) of HIV-1/HCV co-infected individuals undergoing IFN-α-based treatment the baseline miR-221 expression was lower in non-responders compared with responders; and miR-221 expression directly correlated with DC frequency and IL-6/TNF-α secretion. In addition to PBMCs, we isolated total liver cells and kupffer cells from HCV-infected individuals and individuals with alcoholic cirrhosis. We found that both total liver cells and kupffer cells from HCV-infected individuals had significantly higher miR-221 levels compared with individuals with cirrhosis. Overall, we demonstrate that IFN-α exerts both antiproliferative and immunomodulatory effects on mDCs via miR-221 downregulation; and IFN-miR-221 axis can play important role in HCV pathogenesis and treatment.

A cross-talk between Hepatitis B virus and host mRNAs confers viral adaptation to liver

Hepatitis B virus (HBV) chronically infects approximately 350 million people worldwide. The replication of HBV which genome is only 3.2 kb long relies heavily on host factors. Previous studies demonstrated that a highly expressed liver-specific microRNA (miRNA) miR-122 suppresses HBV expression and replication in multiple ways. In this study, we found that the miR-122 response elements in viral genome facilitate HBV expression and replication in miR-122 highly-expressed hepatocytes. Moreover, mutations in miR-122 response elements are correlated with viral loads and disease progression in HBV-infected patients. We next found that HBV mRNA with miR-122 response elements alone could lead to altered expression of multiple host genes by whole genome expression analysis. HBV mRNA-mediated miR-122 down-regulation plays a major role in HBV mRNA-induced differential gene expression. HBV mRNA could enhance viral replication via miR-122 degradation and the up-regulation of its target cyclin G1. Our study thereby reveals that under the unique condition of high abundance of miR-122 and viral mRNAs and much lower level of miR-122 target in HBV infection, HBV may have evolved to employ the miRNA-mediated virus and host mRNAs network for optimal fitness within hepatocytes.

Hepatitis B virus hijacks CTHRC1 to evade host immunity and maintain replication

Hepatitis B virus (HBV) infection causes acute and chronic liver diseases, but is not directly cytopathic. Liver injury results from repeated attempts of the cellular immune response system to control the viral infection. Here, we investigate the roles of cellular factors and signaling pathways involved in the regulation of HBV replication to reveal the mechanism underlying HBV infection and pathogenesis. We show that collagen triple helix repeat containing 1 (CTHRC1) expression is elevated in HBV-infected patients and in HBV-transfected cells through epigenetic modification and transcriptional regulation. CTHRC1 facilitates HBV replication in cultured cells and BALB/c mice by activating the PKCα/ERK/JNK/c-Jun cascade to repress the IFN/JAK/STAT pathway. HBV-activated CTHRC1 downregulates the activity of type I interferon (IFN), the production of IFN-stimulated genes (ISGs), and the phosphorylation of signal transducer and activator of transcription 1/2 (STAT1/2), whereas it upregulates the phosphorylation and ubiquitination of type I IFN receptors (IFNARα/β). Thus, our results show that HBV uses a novel mechanism to hijack cellular factors and signal cascades in order to evade host antiviral immunity and maintain persistent infection. We also demonstrate that CTHRC1 has a novel role in viral infection.

MiR-122 in hepatitis B virus and hepatitis C virus dual infection

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the most common causes of chronic liver diseases and hepatocelluar carcinomas. Over the past few years, the liver-enriched microRNA-122 (miR-122) has been shown to differentially regulate viral replication of HBV and HCV. It is notable that the level of miR-122 is positively and negatively regulated by HCV and HBV, respectively. Consistent with the well-documented phenomenon that miR-122 promotes HCV accumulation, inhibition of miR-122 has been shown as an effective therapy for the treatment of HCV infection in both chimpanzees and humans. On the other hand, miR-122 is also known to block HBV replication, and HBV has recently been shown to inhibit miR-122 expression; such a reciprocal inhibition between miR-122 and HBV suggests an intriguing possibility that miR-122 replacement may represent a potential therapy for treatment of HBV infection. As HBV and HCV have shared transmission routes, dual infection is not an uncommon scenario, which is associated with more advanced liver disease than either HBV or HCV mono-infection. Thus, there is a clear need to further understand the interaction between HBV and HCV and to delineate the role of miR-122 in HBV/HCV dual infection in order to devise effective therapy. This review summarizes the current understanding of HBV/HCV dual infection, focusing on the pathobiological role and therapeutic potential of miR-122.

Down-regulation of suppressor of cytokine signaling 3 by miR-122 enhances interferon-mediated suppression of hepatitis B virus

MicroRNA-122 (miR-122) is involved in the pathogenesis of several liver diseases, including chronic hepatitis B infection and hepatocellular carcinoma. This study aimed to explore the potential role of miR-122 in the interferon (IFN)-mediated suppression of hepatitis B virus (HBV) in hepatocytes. We found that elevated expression of suppressor of cytokine signaling 3 (SOCS3) following HBV infection, contributed to the inactivation of the IFN signaling pathway. Based on previous studies from our laboratory showing that miR-122 can modulate type I IFN expression by inhibiting SOCS1 expression, we analyzed the SOCS3 mRNA sequence for putative miR-122 binding sites. We demonstrate that miR-122 inhibits SOCS3 expression by targeting the 3'-untranslated region of the SOCS3 mRNA within the region 1887-1910 nucleotides. Finally, we demonstrate that significantly increased levels of IFN lead to decreased HBV expression in miR-122 mimic-treated Huh7 cells, whereas inhibition of endogenous miR-122 leads to enhanced viral production, owing to a marked decrease in IFN expression. Taken together, our results demonstrate that miR-122 down-regulates SOCS3, thus positively affecting the anti-HBV efficiency of endogenous type I IFN. Our study suggests that suppression of miR-122 induced by HBV infection, leads to the inactivation of IFN expression, which in turn enhances HBV replication, contributing to viral persistence and hepatocarcinogenesis.

MicroRNAs in virus-induced tumorigenesis and IFN system

Numerous microRNAs (miRNAs), small non-coding RNAs encoded in the human genome, have been shown to be involved in cancer pathogenesis and progression. There is evidence that some of these miRNAs possess proapoptotic or proliferation promoting roles in the cell by negatively regulating target mRNAs. Oncogenic viruses are able to produce persistent infection, favoring tumor development by deregulating cell proliferation and inhibiting apoptosis. It has been recently suggested that cellular miRNAs may participate in host-virus interactions, influencing viral replication. Many mammalian viruses counteract this cellular antiviral defense by using viral proteins but also by encoding viral miRNAs involved in virus-induced tumorigenesis. Interferons (IFNs) modulate a number of non-coding RNA genes, especially miRNAs, that may be used by mammalian organisms as a mechanism of IFN system to combat viral infection and related diseases. In particular, IFNs might induce specific cellular miRNAs that target viral transcripts thereby using this strategy as part of their effectiveness against invading viruses. Therefore IFNs, interferon stimulated genes and miRNAs could act synergistically as innate response to virus infection to induce a potent non-permissive cellular environment for virus replication and virus-induced cancer. The relevance of this reviewed research topic is clearly related to the observation that although virus infections are responsible of specific tumors, other unidentified genetic alterations are likely involved in the induction of malignant transformation. The identification of such genetic alterations, i.e. miRNA expression in transformed cells, would be of considerable importance for the analysis of the pathogenesis and for the treatment of cancer induced by specific viruses as well as for the advancement of the current knowledge on the molecular mechanisms underlying virus-host interaction. In this respect, we will review also the important, still little explored, roles of miRNAs acting both as IFN-stimulated anti-viral molecules and as critical regulators of IFNs and IFN-stimulated genes.

Exosomes from hepatitis C infected patients transmit HCV infection and contain replication competent viral RNA in complex with Ago2-miR122-HSP90

Antibodies targeting receptor-mediated entry of HCV into hepatocytes confer limited therapeutic benefits. Evidence suggests that exosomes can transfer genetic materials between cells; however, their role in HCV infection remains obscure. Here, we show that exosomes isolated from sera of chronic HCV infected patients or supernatants of J6/JFH1-HCV-infected Huh7.5 cells contained HCV RNA. These exosomes could mediate viral receptor-independent transmission of HCV to hepatocytes. Negative sense HCV RNA, indicative of replication competent viral RNA, was present in exosomes of all HCV infected treatment non-responders and some treatment-naïve individuals. Remarkably, HCV RNA was associated with Ago2, HSP90 and miR-122 in exosomes isolated from HCV-infected individuals or HCV-infected Huh7.5 cell supernatants. Exosome-loading with a miR-122 inhibitor, or inhibition of HSP90, vacuolar H+-ATPases, and proton pumps, significantly suppressed exosome-mediated HCV transmission to naïve cells. Our findings provide mechanistic evidence for HCV transmission by blood-derived exosomes and highlight potential therapeutic strategies.

MiRNA-548ah, a potential molecule associated with transition from immune tolerance to immune activation of chronic hepatitis B

OBJECTIVE

The present study aims to identify the differently expressed microRNA (miRNA) molecules and target genes of miRNA in the immune tolerance (IT) and immune activation (IA) stages of chronic hepatitis B (CHB).

METHODS

miRNA expression profiles of peripheral blood mononuclear cells (PBMCs) at the IT and IA stages of CHB were screened using miRNA microarrays and authenticated using a quantitative real-time polymerase chain reaction (RT-PCR). Gene ontology (GO) and the Kyoto encyclopedia of genes and genomes (KEGG) were used to analyze the significant functions and pathways of possible target genes of miRNAs. Assays of the gain and loss of function of the miRNAs were performed to verify the target genes in THP-1 cell lines. The luciferase reporter test was used on 293T cells as direct targets.

RESULTS

Significantly upregulated miR-548 and miR-4804 were observed in the miRNA microarrays and confirmed by RT-PCR in PBMCs at the IT and IA stages of CHB. GO and KEGG analysis revealed that MiR-548 and miR-4804 could be involved in numerous signaling pathways and protein binding activity. IFNγR1 was predicted as a target gene and validated as the direct gene of MiR-548. Significant negative correlation was found between the miR-548ah and mRNA levels of IFN-γR1 in CHB patients.

CONCLUSIONS

The abnormal expression profiles of miRNA in PBMCs could be closely associated with immune activation of chronic HBV infection. miR-548, by targeting IFN-γR1, may represent a mechanism that can facilitate viral pathogenesis and help determine new therapeutic molecular targets.

Placenta-derived gp96 as a multivalent prophylactic cancer vaccine

A major challenge for designing prophylactic cancer vaccines is to define immunogenic and safe cancer antigens. Given the striking similarity of antigen expression patterns between cancer and embryonic tissues, we defined a prototype strategy of using placenta-derived heat shock protein gp96, which induces prophylactic anti-tumor T cell responses. Immunization with placental gp96 provided partial protection and long-term (at least 3 months) anti-tumor immunity against growth of transplantable melanoma or breast tumors in mice, elicited total protection against 7, 12-dimethylbenz(a)-anthracene (DMBA)-induced mammary tumors in rats, and significantly reduced the occurrence and growth of autochthonous breast tumors in HER2 transgenic mice. Placental gp96 activated HER2- and MUC1-specific T cell responses through binding to tumor-associated antigens. Our results reveal the novel immunogenicity of placental gp96 and its potential use as a multivalent cancer vaccine.

Competitive virus and host RNAs: the interplay of a hidden virus and host interaction

During virus infection, viral RNAs and mRNAs function as blueprints for viral protein synthesis and possibly as pathogen-associated molecular patterns (PAMPs) in innate immunity. Here, considering recent research progress in microRNAs (miRNAs) and competitive endogenous RNAs (ceRNAs), we speculate that viral RNAs act as sponges and can sequester endogenous miRNAs within infected cells, thus cross-regulating the stability and translational efficiency of host mRNAs with shared miRNA response elements. This cross-talk and these reciprocal interactions between viral RNAs and host mRNAs are termed “competitive viral and host RNAs” (cvhRNAs). We further provide recent experimental evidence for the existence of cvhRNAs networks in hepatitis B virus (HBV), as well as Herpesvirus saimiri (HVS), lytic murine cytomegalovirus (MCMV) and human cytomegalovirus (HCMV) infections. In addition, the cvhRNA hypothesis also predicts possible cross-regulation between host and other viruses, such as hepatitis C virus (HCV), HIV, influenza virus, human papillomaviruses (HPV). Since the interaction between miRNAs and viral RNAs also inevitably leads to repression of viral RNA function, we speculate that virus may evolve either to employ cvhRNA networks or to avoid miRNA targeting for optimal fitness within the host. CvhRNA networks may therefore play a fundamental role in the regulation of viral replication, infection establishment, and viral pathogenesis.

Hepatitis C virus and human miR-122: insights from the bench to the clinic

MicroRNAs (miRNAs) are small non-coding RNAs that function as part of RNA-induced silencing complexes that repress the expression of target genes. Over the past few years, miRNAs have been found to mediate complex regulation of a wide variety of mammalian viral infections, including Hepatitis C virus (HCV) infection. Here, we focus on a highly abundant, liver-specific miRNA, miR-122. In a unique and unusual interaction, miR-122 binds to two sites in the 5' untranslated region (UTR) of the HCV genome and promotes viral RNA accumulation. We will discuss what has been learned about this important interaction to date, provide insights into how miR-122 is able to modulate HCV RNA accumulation, and how miR-122 might be exploited for antiviral intervention.

MicroRNAs: role and therapeutic targets in viral hepatitis

MicroRNAs regulate gene expression by binding to the 3'-untranslated region (UTR) of target messenger RNAs (mRNAs). The importance of microRNAs has been shown for several liver diseases, for example, viral hepatitis. MicroRNA-122 is highly abundant in the liver and is involved in the regulation of lipid metabolism. MicroRNA-122 is also an important host factor for the HCV and promotes HCV replication. In contrast to HCV, microRNA-122 inhibits replication of the HBV. MicroRNA-122 acts as a tumour suppressor and reduced levels of microRNA-122 are associated with hepatocellular carcinoma. MicroRNAs other than microRNA-122 have been linked to viral hepatitis, fibrosis and inflammation. In this review, we discuss function and clinical implications of microRNA-122 and other microRNAs in liver diseases, especially viral hepatitis.

Roadmap of miR-122-related clinical application from bench to bedside

INTRODUCTION

microRNA (miRNA) regulates target gene expression to influence many physiological and pathophysiological processes. The liver-specific miRNA, miR-122, contributes to liver function and plays a very important role in hepatic diseases including the viral hepatitis C (HCV). For this reason, developing an miR-122-related clinical application could be very useful in managing or treating many hepatic disorders.

AREAS COVERED

This review introduces the basic concepts of miRNA and miR-122. It also discusses the possibility of miR-122 as a biomarker and summarizes the results of anti-miR-122 treatment from basic research to a Phase IIa clinical trial. Furthermore, the authors discuss the potential opportunities and challenges found in clinical trials with miravirsen.

EXPERT OPINION

miR-122 may be a useful biomarker as both a diagnostic and prognostic tool. Furthermore, miravirsen is a novel treatment with great potential for hepatic disease treatment, especially in HCV. However, there is certainly the need for future investigations to better determine whether miR-122 is really specific for liver. It is also important to elucidate whether miR-122 is actually specific for HCV genome and further investigate the therapeutic potential of miravirsen. Only once these studies have been completed can anti-miR-122 treatment potentially enter the clinical practice.

Serum microRNA-122 level correlates with virologic responses to pegylated interferon therapy in chronic hepatitis C

MicroRNA-122 (miR-122) facilitates hepatitis C virus replication in vitro. Serum miR-122 has been implicated as a biomarker for various liver diseases; however, its role in chronic hepatitis C remains unclear. To address this issue, 126 patients with chronic hepatitis C who completed pegylated IFN plus ribavirin therapy with sustained virologic response (SVR) or nonresponse (NR) were retrospectively included, and their pretreatment clinical profiles and treatment responses were collected. Serum miR-122 was quantified before and during treatment. Another 51 patients in SVR and NR groups were prospectively enrolled for validation. Serum miR-122 was found to be a surrogate for hepatic miR-122 and positively correlated with hepatic necroinflammation. Patients who showed complete early virologic response and SVR had significantly higher pretreatment serum miR-122 levels than those with NR (P = 0.001 and P = 0.008, respectively), especially in subgroups of patients with hepatitis C virus genotype 2 and IL-28B rs8099917 TT genotype. Patients with IL-28B TT genotype had significantly better treatment responses and higher pretreatment serum miR-122 level than those with GT or GG genotypes. Univariate analysis showed that pretreatment body mass index, γ-glutamyl transpeptidase, triglyceride, IL-28B TT genotype, and serum miR-122 are predictors for SVR. Multivariate analysis specifically in IL-28B TT genotype demonstrated that pretreatment serum miR-122 independently predicted SVR. The validation cohort confirmed a significantly greater pretreatment serum miR-122 level in patients with SVR compared with NR (P = 0.025). In conclusion, serum miR-122 may serve as a surrogate of hepatic miR-122, and a higher pretreatment serum miR-122 level can help predict virologic responses to pegylated IFN plus ribavirin therapy.