Rapid detection of hepatitis B virus DNA in liver tissue by in situ hybridisation and its combination with immunohistochemistry for simultaneous detection of HBV antigens

Transaminase Elevations during Treatment of Chronic Hepatitis B Infection: Safety Considerations and Role in Achieving Functional Cure

While current therapies for chronic HBV infection work well to control viremia and stop the progression of liver disease, the preferred outcome of therapy is the restoration of immune control of HBV infection, allowing therapy to be removed while maintaining effective suppression of infection and reversal of liver damage. This “functional cure” of chronic HBV infection is characterized by the absence of detectable viremia (HBV DNA) and antigenemia (HBsAg) and normal liver function and is the goal of new therapies in development. Functional cure requires removal of the ability of infected cells in the liver to produce the hepatitis B surface antigen. The increased observation of transaminase elevations with new therapies makes understanding the safety and therapeutic impact of these flares an increasingly important issue. This review examines the factors driving the appearance of transaminase elevations during therapy of chronic HBV infection and the interplay of these factors in assessing the safety and beneficial nature of these flares.

Single Hepatocyte Hepatitis B Virus Transcriptional Landscape in HIV Coinfection

BACKGROUND

Hepatitis B virus (HBV) is a leading cause of liver failure and hepatocellular carcinoma. Approximately 10% of people with HIV also have HBV and are at higher risk of liver disease progression than in HBV monoinfection. Antivirals, common to HIV and HBV, suppress HBV DNA levels but do not eradicate virus because the transcriptional template, covalently closed circular DNA (cccDNA), is long lived in infected hepatocytes.

METHODS

Using single-cell laser capture microdissection, we isolated >1100 hepatocytes from 5 HIV/HBV coinfected persons with increasing exposure to HBV antivirals (HB1-HB5; no exposure to >7 years exposure), quantifying cccDNA and pregenomic RNA (pgRNA) in each cell using droplet digital polymerase chain reaction.

RESULTS

The proportion of infected hepatocytes decreased with antiviral exposure from 96.4% (HB1) to 29.8% (HB5). Upper cccDNA range and median pgRNA decreased from HB1 to HB5 (P < .05 for both). The amount of pgRNA transcribed per cccDNA also decreased from HB1 to HB5 (P < .05). Cells with inactive pgRNA transcription were enriched from 0% (HB1) to 14.3% (HB5) of infected hepatocytes.

CONCLUSIONS

cccDNA transcription is reduced in HIV/HBV coinfected people with longer antiviral duration. Understanding HBV transcriptional regulation may be critical to develop a functional cure.

In situ analysis of intrahepatic virological events in chronic hepatitis B virus infection

Persistent hepatitis B virus (HBV) infection is established by the formation of an intranuclear pool of covalently closed circular DNA (cccDNA) in the liver. Very little is known about the intrahepatic distribution of HBV cccDNA in infected patients, particularly at the single-cell level. Here, we established a highly sensitive and specific ISH assay for the detection of HBV RNA, DNA, and cccDNA. The specificity of our cccDNA probe set was confirmed by its strict intranuclear signal and by a series of Southern blot analyses. Use of our in situ assay in conjunction with IHC or immunofluorescence uncovered a surprisingly mosaic distribution of viral antigens and nucleic acids. Most strikingly, a mutually exclusive pattern was found between HBV surface antigen-positive (HBsA-positive) and HBV DNA- and cccDNA-positive cells. A longitudinal observation of patients over a 1-year period of adeforvir therapy confirmed the persistence of a nuclear reservoir of viral DNA, although cytoplasmic DNA was effectively depleted in these individuals. In conclusion, our method for detecting viral nucleic acids, including cccDNA, with single-cell resolution provides a means for monitoring intrahepatic virological events in chronic HBV infection. More important, our observations unravel the complexity of the HBV life cycle in vivo.

Hepatic expression of cell proliferation markers and growth factors in giant cell hepatitis: implications for the pathogenetic mechanisms involved

OBJECTIVES

The aim of this study is to determine whether amitotic division or nuclear proliferation is involved in the formation of giant cells (GCs) in giant cell hepatitis (GCH).

PATIENTS AND METHODS

Liver sections from 18 pediatric patients with idiopathic infantile GCH and 12 patients with postinfantile GCH were evaluated for the expression of proliferating cell nuclear antigen (PCNA) and human histone 3 (H3) mRNA, transforming growth factor-alpha (TGF-α), TGF-β1, hepatocyte growth factor (HGF), and epidermal growth factor receptor (EGFR).

RESULTS

Proliferation markers were detected in 1% to 80% in the nuclei of GC and non-GC hepatocytes in 10 of 18 (56%) infantile GCH biopsies and 11 of 12 (92%) postinfantile GCH biopsies, but not in normal liver. The expression of proliferation markers in GCs paralleled that in non-GC hepatocytes (P < 0.05 for both markers). TGF-α and EGFR were detected in both GCs (9/29 and 4/30 patients with infantile or postinfantile GCH, respectively) and non-GC hepatocytes (15/29 and 11/30 patients with infantile or postinfantile GCH, respectively). TGF-β1 and HGF were detected mainly in sinusoidal cells in 20 of 29 and 10 of 30 patients with infantile or postinfantile GCH, respectively; the expression of HGF was positively correlated with PCNA and H3 mRNA in non-GC hepatocytes and with H3 mRNA in GCs (P < 0.01).

CONCLUSIONS

Hepatic expressions of nuclear proliferation markers and growth factors were similar in infantile and postinfantile GCH, nuclear proliferation markers were detected in both GCs and non-GC hepatocytes in a high proportion of patients, and expression of HGF correlated positively with the proliferation markers. These data indicate that nuclear proliferation may contribute to the pathogenesis of GCs in at least a proportion of patients with GCH. A model for the pathogenesis of GCH is proposed.

Detection of hepatitis E virus genome and gene products in two patients with fulminant hepatitis E

Non-isotopic in situ hybridization (digoxigenin-labeled probe directed towards hepatitis E virus ORF1) and immunohistochemistry (against hepatitis E virus ORF2 and ORF3) were applied to detect hepatitis E virus genome and gene product in the liver tissue of two patients with fulminant hepatitis E seropositive for hepatitis E virus RNA. Both hepatitis E virus RNA and hepatitis E virus antigens were detected exclusively in the cytoplasm of hepatocytes and not detected in other cell types. In both patients, more than 50% of the hepatocytes were positive for both hepatitis E virus RNA and hepatitis E virus antigens, most of which showed degenerative changes. This is consistent with the histological appearance of marked loss of hepatocytes with acinar collapse. Interestingly, denaturation of the RNA before in situ hybridization was found to enhance hepatitis E virus RNA detection. We conclude that: (1) hepatitis E virus RNA and hepatitis E virus antigens can be demonstrated in the liver in hepatitis E virus-related fulminant hepatitic failure, (2) hepatitis E virus is hepatocyte-tropic within the liver, (3) cytoplasmic localization of hepatitis E virus RNA and hepatitis E virus antigens is consistent with cytoplasmic replication, and (4) the presence of degenerative changes in hepatitis E virus positive cells, together with the histological appearance of hepatocyte loss in the absence of significant inflammatory infiltrate, suggests that hepatitis E virus-related fulminant hepatitic failure is mediated by a cytopathic mechanism.

Detection of hepatitis C virus genome in formalin-fixed paraffin-embedded liver tissue by in situ reverse transcription polymerase chain reaction

Detection of hepatic hepatitis C virus RNA and antigens is difficult since their expression is very low. The technique of in situ reverse transcription polymerase chain reaction (IS-RT-PCR) was developed for the detection and localization of HCV RNA in formalin-fixed paraffin-embedded liver sections. Key steps for achieving a good signal-to-background ratio include appropriate proteolytic digestion, DNase pretreatment, higher Mg2+ concentration, primers from the core region, "hot-start", and between 10-20 cycles of PCR. Using this approach, HCV RNA was detected in the liver in four of the six patients. In those positive samples, the percentage of cells positive for HCV RNA ranges from < 5 to 25%. Using RT-PCR of serum samples and RNA extracted from the corresponding tissue block (10 sections) as the gold standard and sections from four control subjects as negative controls, the sensitivity and specificity of this assay was 4/6 and 4/4, respectively. The specific positive signal was found mainly in the cytoplasm of the hepatocytes and occasionally in mononuclear cells but not in the bile duct epithelium or sinusoidal cells. These positive hepatocytes were scattered in the liver lobules with occasional clustering. These preliminary data confirm the hepatotropic nature of HCV and the localization of HCV RNA is consistent with cytoplasmic replication.

Hepatic expression of interferon-alpha in chronic hepatitis B virus infection

Hepatic expression of interferon-alpha (IFN-alpha) was examined by immunohistochemistry in 90 Chinese patients (M/F 67:23, age: 14-69) with a spectrum of hepatitis B virus (HBV)-related chronic liver diseases. Immunoreactive IFN-alpha was detected in sinusoidal cells in 79 patients (88%) and in mononuclear cells in 59 patients (65.6%). Patients with active liver diseases (chronic active hepatitis, active cirrhosis, N = 55) had a higher level of IFN-alpha expression compared to patients with inactive histology (N = 35; sinusoidal cells, P < 0.01; mononuclear cells, P < 0.01). Cytoplasmic HBsAg, nuclear HBcAg, and cytoplasmic HBcAg were detected in 79 (88%), 42 (47%), and 23 (27%) patients respectively. Expression of IFN-alpha in mononuclear cells correlated with the expression of cytoplasmic HBcAg (P < 0.05) but not with nuclear HBcAg or cytoplasmic HBsAg. When the patients were divided into four different phases according to the natural history of chronic HBV infection, patients in the active liver disease phase had higher IFN-alpha expression compared to the immunotolerant and late phase patients (P < 0.01). Using double immunohistochemical staining, both IFN-alpha and cytoplasmic HBcAg were frequently detected near inflammatory infiltrates but no correlation existed between the hepatic expression of HBsAg and IFN-alpha. These data indicate that IFN-alpha is expressed in the liver in HBV-related active liver diseases and that the reported suboptimal production of IFN-alpha by PBMC in HBV-related chronic active liver diseases may be due to a redistribution of the IFN-alpha-producing mononuclear cells into the liver, the site of inflammation.

Hepatocyte proliferation as an indicator of outcome in acute alcoholic hepatitis

To determine whether clinical outcome in patients with acute alcoholic hepatitis is related to the regenerative capability of the liver, liver biopsy specimens from 25 prospectively recruited patients with acute alcoholic hepatitis were studied for hepatic expression of mRNA for two proliferation markers, proliferating cell nuclear antigen and human histone, and for transforming growth factor alpha (TGF alpha) and TGF beta 1 and hepatocyte growth factor (HGF), which regulate hepatocyte proliferation. Proliferation markers were detected to varying degrees in 0-80% of hepatocytes and occasionally in sinusoidal cells and bile-duct epithelium in 19 patients (76%). Patients who survived for 6 months had greater expression of proliferation markers than those who did not survive (p < 0.01). TGF alpha was detected in hepatocytes and bile-duct epithelium, whereas TGF beta 1 was detected mainly in sinusoidal cells and was associated with perivenular fibrosis. Patients who survived for 6 months had greater expression of TGFs than non-survivors (p < 0.02). HGF was detected in sinusoidal cells in 7 patients and correlated with survival (p < 0.01). These data indicate that hepatocyte proliferation, which is possibly related to the pattern of hepatotrophic factor expression, is a good indicator of outcome in acute alcoholic hepatitis.

Detection of hepatitis C virus RNA genome in liver tissue by nonisotopic in situ hybridization

A rapid technique for the detection of hepatitis C virus (HCV) RNA in liver section using nonisotopic in situ hybridization was described. Only 3 of the 10 patients seropositive for antibody to HCV and HCV RNA had detectable HCV RNA in the hepatocytes (1%, 2%, and 15% of cells positive). No specific signal was detected in sinusoidal, biliary epithelial, and mononuclear cells. The positive hepatocytes were scattered in the liver lobule with occasional clusters. The positive signal was confined to the cytoplasmic compartment. These data support the previous observation of the hepatocyte tropism of HCV.

Fibrosing cholestatic hepatitis in a transplant recipient with hepatitis B virus precore mutant

A patient with hepatitis B virus (HBV) precore mutant (seropositive for hepatitis B surface antigen [HBsAg], anti-hepatitis B e antigen [HBeAg], and HBV DNA) who underwent orthotopic liver transplantation for end-stage liver disease is described. Sequencing of the HBV precore region of the pretransplant serum sample confirmed the presence of the precore stop-codon mutant (G-->A mutation in codon 1896) only. The patient received HBV immunoglobulin prophylaxis for 6 months but HBV recurred thereafter with a mild hepatitic flare, and he remained seropositive for HBsAg, anti-HBe, and HBV DNA. The initial hepatitic illness resolved in 3 months. The patient remained well for another 16 months before presenting with fibrosing cholestatic hepatitis (FCH). During his entire initial hepatitic flare, quiescent period, and final FCH phase, he remained seropositive for HBsAg, anti-HBe, and HBV DNA. Moreover, sequencing of the serum HBV DNA in final FCH phase showed the presence of the identical HBV precore mutant. Immunohistochemical staining showed extensive expression of HBsAg/pre-S1, pre-S2, and hepatitis B core antigen, but HBeAg was scarcely detectable. This case illustrates that (1) recurrence of HBV precore mutant infection can occur in liver; (2) it can give rise to FCH; and (3) hepatic accumulation of HBeAg is not essential for the development of FCH.

Hepatic HLA antigen display in chronic hepatitis B virus infection. Relation to hepatic expression of HBV genome/gene products and liver histology

To determine the relationship between hepatitis B virus (HBV) replication and HLA antigen display at a cellular level, the hepatic expression of HLA antigens and HBV genome (HBV-DNA)/gene products (HBsAg/HBcAg) was studied in 24 patients with chronic HBV infection using simultaneously immunohistochemistry and nonisotopic in situ hybridization. The effect of interferon-alpha and interferon-gamma on hepatocyte HLA antigen expression was also evaluated using primary hepatocyte culture in eight patients with chronic HBV infection. HLA class I antigens were detected on hepatocyte membrane in 23 patients (95.8%). Hepatocytes positive for HBcAg and HBV-DNA (cytoplasmic +/- nuclear) were either negative or only faintly positive for HLA class I antigens, while hepatocytes positive for HBsAg showed similar levels of HLA class I antigen expression compared with those hepatocytes with no HBsAg expression. In contrast, hepatocytes adjacent to inflammatory infiltrates, whether positive for HBV-DNA or HBV antigens or not, were always strongly positive for HLA class I antigens. Furthermore, active liver histology (N = 12) was associated with a higher overall level of hepatic HLA class I antigen expression as compared with inactive histology (N = 12, P = 0.003). Both interferon-alpha and interferon-gamma treatment in vitro enhanced hepatocyte HLA class I antigen expression. These data indicate that expression of HLA class I antigens is not enhanced on the membrane of hepatocytes with HBV replication, and this may be one factor that permits the development of viral persistence.