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.     

Effect of mutation in the hepatitis C virus nonstructural 5B region on HCV replication

Background We have reported that the presence of a mutation at the hepatitis C virus (HCV) nonstructural protein 5B (NS5B), defined as a change in amino acids at sites specific for a different reported genotype, was related to complete response (CR) to interferon (IFN) therapy in patients with chronic hepatitis C (CHC) with genotype 1b. The present study assessed the impact of the NS5B mutation on the replication of HCV in these patients.Methods Genotype-specific mutations of HCV NS5B were determined by direct sequencing. We measured HCV-RNA titers in serum by real-time detected polymerase chain reaction (PCR), and serum HCV core protein levels (as a marker of HCV-RNA replication) were measured using an enzyme immunoassay in patients with CHC genotype 1b. RNA-dependent RNA polymerase (RdRp) activity was measured by Behrens method in liver cirrhosis patients infected with HCV (n = 13) and in those infected with hepatitis B virus (HBV; n = 2).Results The titers of HCV-RNA (n = 44) and the levels of HCV core protein (n = 41) were significantly lower in patients with the HCV genotype 1b mutant compared with wild-type HCV (P < 0.05). RdRp activity in liver tissue did not show any correlation with the HCV NS5B mutation.Conclusions HCV NS5B genotype-specific mutations in HCV genotype 1b may influence HCV replication.     

Treatment of chronic hepatitis B or C in HIV-infected patients with dual viral hepatitis

Dual chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are recognized in 3%-5% of human immunodeficiency virus (HIV)-infected individuals. More severe liver disease is seen in these patients. Viral interference may account for the fact that replication of one virus generally predominates over replication of the other. The impact that treatment of HBV or HCV infection has on this reciprocal inhibition is not well established. No evidence of reactivation of either HBV or HCV was seen when complete suppression of the other predominant virus was achieved with specific therapy in 21 subjects with HIV infection and dual HBV/HCV infections. This information has important pathogenic implications and may influence therapeutic decisions.     

Profound suppression of chronic hepatitis C following superinfection with hepatitis B virus.

BACKGROUND: Hepatitis B virus (HBV) and hepatitis C virus (HCV) share similar transmission routes; thus, coinfection is frequent. The consequences of acute HBV infection in patients with chronic hepatitis C are unknown. METHODS: We describe a 47-year-old male with chronic hepatitis C who acquired HBV and then spontaneously and apparently completely cleared HCV but developed chronic hepatitis B. Five serum samples collected over 14 months and lymphoid cells obtained after acquiring HBV were tested for HCV and HBV by both standard assays and ultra-sensitive polymerase chain reaction/nucleic acid hybridization (PCR/NAH) (sensitivity approximately 2 IU/ml). RESULTS: After superinfection with HBV, HBV surface antigen-positive chronic hepatitis developed with readily detectable HBV DNA. All sera collected after acquisition of HBV, which tested negative for HCV RNA by standard laboratory assay, were positive for HCV genomes when analysed by PCR/NAH. Peripheral lymphoid cells carried HBV DNA and covalently closed circular DNA, but were negative for HCV. CONCLUSIONS: This is the first reported case of profound suppression of chronic hepatitis C after superinfection with HBV and establishment of chronic hepatitis B. It is hypothesized that HBV infection precipitated generalized and/or virus-specific cellular immune responses that profoundly suppressed HCV replication and yet failed to inhibit progression to chronic hepatitis B.     

Role of hepatitis B virus, hepatitis D virus and other determinants on suppression of hepatitis C viraemia in HIV infected patients with chronic HCV infection: a longitudinal evaluation

The role of hepatitis B virus (HBV) or hepatitis D virus (HDV) coinfections as determinants of hepatitis C virus (HCV) suppression in the setting of HIV-HCV coinfection are poorly understood. Our aim was to assess whether HCV viral replication may be affected by HBV or HDV coinfection in the setting of immunodeficiency driven by HIV.Among the 138 enrolled patients 28(20.3%) tested HCV RNA negative and 110 (79.7%) tested HCV RNA negative. The HCV RNA negative patients showed an higher rate of HBsAg positivity compared with those tested HCVRNA positive [12/28 (42.9%) and 5/110 (4.6%), respectively]. Patients with HCV-HBV-HDV coinfection had the highest chance of having an undetectable HCV RNA (adjusted odds ratio (AOR): 92.0, 95% confidence interval (CI) 5.7-1483.5, p<0.0001). Furthermore, HBV coinfection per se was also found to be independently associated with negative HCV viraemia (AOR: 18.5, 95% CI 2.4-143.5, p<0.0001). HBsAg-positive patients with negative HCV viraemia maintained undetectable levels over time. Our results support a direct role of HBV and HDV coinfections in suppressing HCV viraemia in HIV infected patients. This effect is durable over time, and is not influenced by HAART including anti-HBV drugs.     

Suppression of hepatitis B virus replication mediated by hepatitis A-induced cytokine production

BACKGROUND: Acute hepatitis A virus (HAV) infection can cause severe hepatitis especially in patients with underlying chronic liver disease. In patients with pre-existing chronic hepatitis B (HBV) acute HAV infection can suppress HBV replication. The exact mechanism of HBV suppression during acute HAV infection is still a subject of debate. One mechanism may be the production of HAV infection-induced cytokines leading to suppression of HBV replication and viral clearance. AIM: To evaluate cytokine production and HBV-specific lympho-proliferative responses (LPR) during acute HAV infection in a patient with chronic HBV infection-clearing markers of active HBV replication. DESIGN: Early detection of a case of acute HAV infection in an HBeAg-positive, HBV DNA-positive chronic HBV patient treated with lamivudine. RESULTS: At the time of HAV infection a sharp peak in the gamma-interferon (IFN-gamma) level occurred just before the rise in serum transaminase activity. This was subsequently followed by a decrease in HBV DNA and HBeAg below the limit of detection of the assay. However the HBV-specific T-cell response was not modified. After resolution of the acute HAV infection and withdrawal of antiviral therapy HBV replication relapsed. CONCLUSION: The sharp rise in IFN-gamma production mediated by the acute HAV infection may be pivotal in the suppression of HBV replication in chronic hepatitis B.     

Single (B or C), dual (BC or BD) and triple (BCD) viral hepatitis in HIV-infected patients in Madrid, Spain

INTRODUCTION: There are very limited data about the prevalence of multiple hepatitis virus infections in HIV infected individuals. In HIV uninfected individuals with triple BCD hepatitis, hepatitis D virus (HDV) appears to be the dominant virus. However, in HIV infected patients with triple hepatitis it is not known if HDV replication inhibits hepatitis B virus (HBV) and/or hepatitis C virus (HCV) replication. METHODS: We calculated the prevalence of single (B or C), dual (BC) and triple (BCD) hepatitis in 423 HIV-infected patients with positive HCV serum antibodies and/or positive serum HBsAg. In patients with multiple infections we performed an evaluation of serum markers of HBV, HCV and HDV replication. RESULTS: The prevalence of multiple hepatitis was 4.7% (95% confidence interval, 2.7-6.7%). Multiple hepatitis occurred only among patients who acquired HIV through injection drug use. The most common multiple hepatitis was triple BCD. Patients with hepatitis BC and past or chronic hepatitis D were significantly more likely to have cirrhosis and a negative serum HBeAg and HCV PCR than patients with single hepatitis B or hepatitis C. Patients with chronic hepatitis D showed uniform suppression of HBV and HCV replication markers. CONCLUSIONS: In our geographic area approximately 5% of HIV infected patients with hepatitis suffer multiple hepatitis virus infection. In patients with triple hepatitis BCD virus infection, HDV appears to be the dominant virus causing inhibition of both HBV and HCV replication.     

De novo hepatitis B virus infection in hepatocellular carcinoma following eradication of hepatitis C virus by interferon therapy

Epidemiological studies have revealed that hepatocellular carcinoma (HCC) is still observed in hepatitis C virus (HCV)‐positive patients with a sustained response to interferon (IFN) treatment, although a substantial decrease in the incidence of hepatocellular carcinoma (HCC) has been achieved in those patients. Why HCC develops in patients who have a complete clearance of HCV remains unclear. Here, we provided evidence of latent hepatitis B virus (HBV) infection in an initially HCV‐positive chronic hepatitis patient who developed HCC after the complete eradication of HCV by IFN therapy. Although he was initially negative for anti‐hepatitis B surface antigen (HBsAg) or circulating HBV DNA but positive for anti‐hepatitis B core antigen (anti‐HBc) in his sera, he developed HBsAg and HBV DNA during the course of the management of a series of cancers. HBV DNA was detectable in the liver tissues before HBV reactivation and the viral sequences derived from his anti‐HBc‐positive liver showed 100% homology to that from the serum after HBsAg appearance. These findings indicates that HCV‐positive individuals who are positive for anti‐HBc in the absence of HBsAg could have latent HBV infection in their liver tissues and intrahepatic HBV infection may play a pivotal role in the development of HCC after the IFN‐mediated eradication of HCV.     

Suppression of hepatitis C virus replication by cyclosporin a is mediated by blockade of cyclophilins

BACKGROUND & AIMS: Cyclosporin A specifically suppresses hepatitis C virus (HCV) replication in vitro at clinically achievable concentrations. In this study, we investigated the mechanisms of action of cyclosporin A against HCV replication. METHODS: The in vitro effects of cyclosporin A on HCV replication were analyzed using an HCV replicon system that expresses chimeric luciferase reporter protein. RESULTS: The significant effects of cyclosporin A on expression of an HCV replicon and the absence of such effects of FK506, which shares mechanisms of action with cyclosporin A, suggested the involvement of intracellular ligands of cyclosporin A, the cyclophilins. Transient and stable knockdown of the expression of cytoplasmic cyclophilins A, B, and C by short hairpin RNA-expressing vectors suppressed HCV replication significantly. A cyclosporin analogue, cyclosporin D, which lacks immunosuppressive activity but exhibits cyclophilin binding, induced a similar suppression of HCV replication. Furthermore, cyclosporin A treatment of Huh7 cells induced an unfolded protein response exemplified by expression of cellular BiP/GRP78. Treatment of cells with thapsigargin and mercaptoethanol, which induce the unfolded protein responses, suppressed HCV replication, suggesting that the cyclosporin-induced unfolded protein responses might contribute to the suppression of HCV protein processing and replication. CONCLUSIONS: The anti-HCV activity of cyclosporin A is mediated through a specific blockade of cyclophilins, and these molecules may constitute novel targets for anti-HCV therapeutics.     

Liver histology and immunohistochemical findings in asymptomatic Indians with incidental detection of hepatitis B virus infection.

BACKGROUND AND OBJECTIVES: The relationship between hepatocyte expression of hepatitis B virus (HBV) antigens, liver histology and viral replication in asymptomatic subjects with incidental detection of hepatitis B surface antigen (HBsAg) remains unclear. We evaluated the histological activity index (HAI) and hepatocyte expression of viral antigens with replicative status in asymptomatic chronic HBV infection. METHODS: Asymptomatic subjects with incidental detection of HBsAg and ALT levels less than twice the upper limit of normal were grouped as follows: Group A - negative for HBeAg and HBV DNA (no HBV replication); B - HBeAg negative, HBV DNA positive (low HBV replication or pre-core mutant); C - positive HBeAg and HBV DNA (high viral replication). Liver biopsies were assessed for HAI (Ishak's scoring system). These were also subjected to immunohistochemistry for expression of HBsAg and hepatitis B core antigen (HBcAg); distribution, staining pattern and quantitative measurement of antigen expression were assessed. RESULTS: Median HAI was similar in the three groups (1.0, 2.0 and 2.0 in groups A, B and C, respectively). All subjects in Group C showed discrete cytoplasmic expression of HBsAg, whereas the other two groups showed heterogeneity in distribution and pattern of HBsAg staining. Quantitative measurement of cytoplasmic HBsAg revealed similar results in the three groups. Core antigen (nuclear) was detected in 4 of 5 subjects in Group C and none of those in Groups A and B. Ground-glass hepatocytes were seen in 20 and orcein-positive cells in 26 cases. HBsAg was detected by immunohistochemistry in 37 biopsies. CONCLUSIONS: Among asymptomatic subjects with chronic HBV infection, those with high rate of viral replication had discrete cytoplasmic HBsAg expression and nuclear expression of core antigen; these findings were uncommon in subjects with low or no viral replication.     

Histomorphological characteristics of liver tissue in patients with chronic viral hepatitis

OBJECTIVE : Chronic viral hepatitis and cirrhosis caused by hepatitis B virus (HBV), hepatitis C virus (HBC) or both constitute the majority of cases of liver diseases in China. Pathologists often need to differentiate between the morphological features of HBV and HCV. The aim of this study was to explore the differences in inflammatory activity, fibrosis and morphological characteristics in various types of chronic viral hepatitis. METHODS : Inflammatory activity and degree of fibrosis in liver biopsies taken from 224 patients with chronic hepatitis were determined according to the Diagnostic Criteria of Chronic Hepatitis, China, 1995. Each of hepatitis B surface antigen (HBsAg), hepatitis B core antigen (HBcAg) and the hepatitis C virus nuclear core protein (CP₁₀) were detected on paraffin sections of the biopsies by using immunohistochemical methods. Patients were divided into HBV, HCV and HBV + HCV infection groups and the differences among these groups were assessed on the basis of histopathological characteristics including inflammatory activity, fibrosis, steatosis, intrahepatic cholestasis, Councilman bodies and ground‐glass hepatocytes. RESULTS : The HCV infection group had more severe inflammatory activity, fibrosis and intrahepatic cholestasis than did the HBV infection group. The degree of inflammatory activity and fibrosis in the HBV + HCV infection group was moderate, but the degree of intrahepatic cholestasis was the most severe of the three study groups. Ground‐glass hepatocytes were only noted in HBV‐infected specimens. There was no difference in the occurrences of steatosis and Councilman bodies among the three study groups. CONCLUSIONS : The degree of inflammatory activity and fibrosis induced by HCV in hepatocytes is more severe than that induced by HBV. The histological changes observed in liver infected by both HBV and HCV are no more severe than those observed in liver infected with either HBV or HCV. Intrahepatic cholestasis may play an important role in aggravating damage to hepatocytes.     

Clinical and histological impact of previous hepatitis B virus infection in patients with chronic hepatitis C

Background: Recent reports suggest that hepatitis C virus (HCV) carriers with serological markers of prior hepatitis B virus (HBV) infection have more advanced liver fibrosis, irrespective of HBV‐DNA detection. Aims: We sought to assess the prevalence and impact of previous HBV infection in patients with HCV chronic infection. Methods: This cross‐sectional study included hepatitis B surface antigen‐ and human immunodeficiency virus‐negative subjects with positive HCV‐RNA. All patients had prior parenteral exposure as the probable source of HCV infection. Serum samples were tested for HBV‐DNA using a commercial assay. The METAVIR system was used for histological analysis. Results: One‐hundred and eleven patients were evaluated. Thirty‐one out of 111 patients (28%) tested positive for antihepatitis B core antigen (anti‐HBc). HBV‐DNA was not detected in any sample. Anti‐HBc‐positive patients showed higher histological grading, staging and a higher fibrosis progression rate. By multivariate analysis, anti‐HBc‐positivity was predictive of moderate to severe activity [odds ratio (OR)=3.532; P=0.032] and significant hepatic fibrosis (OR=3.364; P=0.017). After approximately 20 years of infection, advanced liver fibrosis (F3/F4) can be expected in 13% of anti‐HBc‐negative subjects who acquired HCV before the age of 30 and in 57% of those anti‐HBc‐positive patients who were infected by HCV after 30 years of age (P<0.001). Conclusion: Previous HBV infection is common among HCV carriers and may exert a negative impact on the natural history of HCV infection, independently of the presence of significant HBV replication.     

HBsAg stimulates NKG2D receptor expression on natural killer cells and inhibits hepatitis C virus replication

Background: Higher hepatitis B surface antigen(HBs Ag) facilitates hepatitis C virus(HCV) clearance in patients with hepatitis B virus(HBV)/HCV co-infection. We investigated the effect of exogenous HBs Ag on the inhibition of HCV replication mediated by natural killer(NK) cells.Methods: After isolated from peripheral blood of 42 chronic hepatitis B(CHB) patients and 16 healthy individuals, NK cells were co-cultured with HCV-infected Huh7 cells, respectively, with or without HBs Ag.Three days later, the co-cultured supernatants were collected and HCV RNA levels were measured by realtime quantitative PCR. NKG2 D, NKp46 and NKG2 A expression levels were measured by flow cytometry.NKG2 D on NK cells from CHB responsive subgroup was blocked and HCV RNA levels were examined again.Results: HCV RNA levels in the co-cultured system were significantly reduced by NK cells isolated from healthy donors(P 0.01) but not from CHB patients. However, HCV RNA levels in CHB cultures were significantly decreased following HBs Ag addition(P 0.05), whereas no such effect was seen in control cultures. No significant difference was observed in basic NKG2 D expression between the CHB patients and healthy donors. On NK cells from CHB patients, the expression of NKG2 D was increased significantly by HBs Ag stimulation(P 0.01), and higher than that from healthy controls(P 0.05). HCV RNA levels were increased significantly after the blockage of NKG2 D on NK cells from responsive CHB patients in the co-cultured system(P 0.05).Conclusion: Exogenous HBs Ag stimulated NKG2 D expression on NK cells from CHB patients which inhibit HCV replication, suggesting that HBs Ag may facilitate the clearance of HCV in patients with HBV/HCV co-infection.