Membrane staining for hepatitis B surface antigen on hepatocytes: a sensitive and specific marker of active viral replication in hepatitis B

Distinct histological patterns in chronic hepatitis D with nucleos(t)ide analogue therapy

Background

Chronic hepatitis delta virus (HDV) infection leads to a more severe hepatitis than hepatitis B virus (HBV) infection alone. Specific histological staining patterns have been described in HBV mono-infection, however this has not been extensively investigated in HDV co-infection. This study evaluated whether the use of nucleos(t)ide analogs (NAs) for concurrent HBV infection has an impact on the histological appearance of chronic HDV.

Methods

Liver biopsies of all patients referred for management of HDV infection were reviewed and hepatitis-specific stains for HBV antigens were evaluated. Clinical and histological characteristics were compared between patients on and off-NA therapy.

Results

50 patients were included in our analysis, of which 26 (52%) were on NA therapy at the time of the biopsy. Overall, 8% stained for HBV core antigen and 86% stained for HBV surface antigen. On and off-NA groups had similar degrees of fibrosis and inflammation, however NA patients had an odds ratio of 7.15 for membranous staining and 0.13 for scattered granular staining (p = 0.001). No association was found with markers of disease severity or viral activity, with nonetheless a lower score of total inflammation noted in biopsies with a positive membranous stain (8.5 vs. 10.3 p = 0.04).

Conclusion

In chronic HDV infection, patients treated with nucleos(t)ide analogs demonstrate a unique membranous staining pattern for hepatitis B surface antigen, which is not associated with HBV or HDV replicative activity. These findings may help improve the understanding of the role of HBV directed therapy in HDV pathophysiology.

Highlights

Histological staining is associated with viral activity in chronic HBV, however this has been infrequently explored in HDV. In HDV, staining patterns differ based on HBV treatment status and do not appear to be associated with markers of viral activity.

Correlation of hepatitis B surface antigen expression with clinicopathological and biochemical parameters in liver biopsies: A comprehensive study

BACKGROUND

Chronic viral B hepatitis (CHB) is a potentially life-threatening liver disease that may progress to liver failure and cirrhosis. Currently, although combinations of different laboratory methods are used in the follow-up and treatment of CHB, the failure of these procedures in some cases has led to the necessity of developing new approaches. In CHB, the intrahepatic expression pattern of viral antigens, including hepatitis B surface antigen (HBsAg), is related to different phases of inflammation. However, many studies have focused on the intracytoplasmic properties of HBsAg staining, and HBsAg positivity in liver tissue has not been evaluated by objective quantitative methods.

AIM

To investigate the relationship of image analysis-based quantitative HBsAg expression and its staining patterns with clinicopathological factors and treatment in CHB.

METHODS

A total of 140 liver biopsies from treatment-naïve cases with CHB infection were included in this study. Following diagnosis, all patients were treated with entecavir (0.5 mg) and followed up at three-month intervals. The percentage of immunohistochemical HBsAg (p-HBsAg) expression in the liver was determined in whole tissue sections of biopsies from each case by image analysis. The immunohistochemical staining pattern was also evaluated separately according to 3 different previously defined classifications.

RESULTS

A positive correlation between p-HBsAg and serum levels of hepatitis B virus (HBV) DNA and HBsAg was observed (P < 0.001). The p-HBsAg value was significantly higher in younger patients than in older patients. When the groups were categorized according to the hepatitis B e antigen (HBeAg) status in HBeAg-positive cases, p-HBsAg was correlated with HBV DNA, hepatitis activity index (HAI) and fibrosis scores (P < 0.001). In this group, p-HBsAg and HBsAg expression patterns were also correlated with the viral response (VR) and the serological response (SR) (P < 0.001). Multivariate analysis revealed that p-HBsAg was an independent predictor of either VR or SR (P < 0.001). In HBeAg-negative patients, although HBsAg expression patterns were correlated with both HAI and fibrosis, no relationship was observed among p-HBsAg, clinicopathological factors and VR.

CONCLUSION

In pretreatment liver biopsies, the immunohistochemical determination of HBsAg expression by quantitative methods, beyond its distribution within the cell, may be a good predictor of the treatment response, especially in HBeAg-positive cases.

Role of anti-HBs in functional cure of HBeAg+ chronic hepatitis B patients infected with HBV genotype A

BACKGROUND & AIMS

HBsAg-specific antibody responses are difficult to detect during chronic hepatitis B infection (CHB) and are often overlooked. The aim of this study was to examine whether anti-HBs may be involved in functional cure (FC) by profiling anti-HBs responses in patients with CHB using a panel of specific assays.

METHODS

Longitudinal serum samples were obtained from 25 patients with CHB who were infected with HBV genotype A and were undergoing nucleos(t)ide analogue (NA) treatment: 14 achieved FC while 11 remained infected (non-FC). Anti-HBs immune complexes (HBsAg-IC), FcγRIIIa dimer binding, epitope specificity and neutralisation efficacy were measured.

RESULTS

HBsAg-IC peaks were detected prior to HBsAg loss in 10/14 FC patients. These HBsAg-IC peaks overlapped with either an alanine aminotransferase (ALT) flare (8/10 patients), or a rise in ALT (2/10 patients). HBsAg-IC peaks were detected in 7/11 non-FC patients, but were not associated with an ALT flare. FCγRIIIa binding was detected in 9/14 FC patients, independent from detection of overlapping HBsAg-IC/ALT peaks. FC patients had stable HBsAg epitope occupancy across the study, whereas non-FC patients had a reduction in HBsAg epitope occupancy within the first 12-24 weeks of NA treatment. Convalescent sera from FC patients recognised more HBsAg epitopes and neutralised HBV infection more potently than anti-HBs derived from vaccinees. Neutralisation potency appeared to increase post-HBsAg loss in 4/5 FC patients examined.

CONCLUSIONS

Using these assays, we confirm that anti-HBs responses are present and fluctuate over time in this cohort of patients with HBeAg+ CHB, who were infected with HBV genotype A and treated with NAs. Key anti-HBs profiles associated with either FC or failure to achieve FC were also identified, suggesting a role for anti-HBs responses in FC.

LAY SUMMARY

Using a panel of assays to characterise hepatitis B surface antibody (anti-HBs) responses in a group of patients with chronic hepatitis B, we identified anti-HBs profiles associated with either functional cure, or failure to achieve functional cure. Functional cure was associated with immune complex peaks which overlapped with alanine aminotransferase flares. Conversely, in those who did not achieve functional cure, immune complex peaks were present, but were not associated with alanine aminotransferase flares, and a decline in anti-HBs diversity was observed early during treatment.

Hepatitis B virus envelope proteins can serve as therapeutic targets embedded in the host cell plasma membrane

Hepatitis B virus (HBV) infection is a major health threat causing 880,000 deaths each year. Available therapies control viral replication but do not cure HBV, leaving patients at risk to develop hepatocellular carcinoma. Here, we show that HBV envelope proteins (HBs)-besides their integration into endosomal membranes-become embedded in the plasma membrane where they can be targeted by redirected T-cells. HBs was detected on the surface of HBV-infected cells, in livers of mice replicating HBV and in HBV-induced hepatocellular carcinoma. Staining with HBs-specific recombinant antibody MoMab recognising a conformational epitope indicated that membrane-associated HBs remains correctly folded in HBV-replicating cells in cell culture and in livers of HBV-transgenic mice in vivo. MoMab coated onto superparamagnetic iron oxide nanoparticles allowed to detect membrane-associated HBs after HBV infection by electron microscopy in distinct stretches of the hepatocyte plasma membrane. Last but not least, we demonstrate that HBs located on the cell surface allow therapeutic targeting of HBV-positive cells by T-cells either engrafted with a chimeric antigen receptor or redirected by bispecific, T-cell engager antibodies. TAKE AWAYS: HBs become translocated to the plasma membrane. Novel, recombinant antibody confirmed proper conformation of HBs on the membrane. HBs provide an interesting target by T-cell-based, potentially curative therapies.

The CD39+ HBV surface protein-targeted CAR-T and personalized tumor-reactive CD8+ T cells exhibit potent anti-HCC activity

CD39, expressed by tumor-infiltrating lymphocytes (TILs), is a marker to identify tumor-reactive T cells, which is frequently associated with stronger antitumor activity than bystander T cells in a variety of malignancies. Therefore, CD39 could be a promising marker for identifying the active antitumor immune cells used for cellular immunotherapy. To test this possibility, we constructed the hepatitis B virus (HBV) surface protein-specific chimeric antigen receptor T cells (HBVs-CAR-T cells) and generated the personalized tumor-reactive CD8⁺ T cells. We subsequently assessed their antitumor efficiency mainly with a co-culture system for autologous HBVs⁺ HCC organoid and T cells. We found that both CD39⁺ HBVs-CAR-T and CD39⁺ personalized tumor-reactive CD8⁺ T cells induced much more apoptosis in HCC organoids. Although the exhaustion status of CAR-T cells increased in CD39⁺ CAR-T cells, triple knockdown of PD-1, Tim-3, and Lag-3 with shRNAs further enhanced antitumor activity in CD39⁺ CAR-T cells. Furthermore, these CD39⁺ CAR-T cells exerted an increased secretion of interferon-γ and stronger antitumor effect in a patient-derived xenograft mouse model. Our findings demonstrated that CD39 could be a promising biomarker to enrich active immune cells and become an indicator marker for evaluating the prognosis of immunotherapy for HCC patients.

The role of hepatitis B surface antibodies in HBV infection, disease and clearance

The clinical sequelae associated with chronic HBV infection is generally regarded as a consequence of an inadequate and inappropriate immune response to active viral replication, predominantly at the T-cell level. However, recent studies on hepatitis B surface antigen (HBsAg)-specific B cells and hepatitis B surface antibody (anti-HB) responses have identified their previously unrecognized role in the pathogenesis of chronic hepatitis B (CHB). These studies have also uncovered novel therapeutic approaches to more effectively target HBsAg loss and seroconversion, an important end point and regarded as a functional cure. Anti-HBs IgG has also been shown to have multiple direct acting antiviral roles with the Fab component directly blocking viral entry, and release while the Fc component has been linked to antibody dependent cellular cytotoxicity. Likewise, the HBsAg-specific B-cell dysfunctionality can be reversed providing new therapeutic opportunities to achieve functional cure in CHB.

HBsAg-redirected T cells exhibit antiviral activity in HBV-infected human liver chimeric mice

BACKGROUND

Chronic hepatitis B virus (HBV) infection remains incurable. Although HBsAg-specific chimeric antigen receptor (HBsAg-CAR) T cells have been generated, they have not been tested in animal models with authentic HBV infection.

METHODS

We generated a novel CAR targeting HBsAg and evaluated its ability to recognize HBV+ cell lines and HBsAg particles in vitro. In vivo, we tested whether human HBsAg-CAR T cells would have efficacy against HBV-infected hepatocytes in human liver chimeric mice.

RESULTS

HBsAg-CAR T cells recognized HBV-positive cell lines and HBsAg particles in vitro as judged by cytokine production. However, HBsAg-CAR T cells did not kill HBV-positive cell lines in cytotoxicity assays. Adoptive transfer of HBsAg-CAR T cells into HBV-infected humanized mice resulted in accumulation within the liver and a significant decrease in plasma HBsAg and HBV-DNA levels compared with control mice. Notably, the fraction of HBV core-positive hepatocytes among total human hepatocytes was greatly reduced after HBsAg-CAR T cell treatment, pointing to noncytopathic viral clearance. In agreement, changes in surrogate human plasma albumin levels were not significantly different between treatment and control groups.

CONCLUSIONS

HBsAg-CAR T cells have anti-HBV activity in an authentic preclinical HBV infection model. Our results warrant further preclinical exploration of HBsAg-CAR T cells as immunotherapy for HBV.

Expression of Hepatocyte Hepatitis B Core Antigen and Hepatitis B Surface Antigen as a Marker in the Management of Chronic Hepatitis B Patients

Background/Aims

We aimed to clarify the association of hepatitis B surface antigen (HBsAg)/hepatitis B core antigen (HBcAg) with the disease status and treatment response in patients with chronic hepatitis B (CHB).

Methods

We investigated 171 biopsy-proven entecavir-treated CHB patients (109 hepatitis B e antigen [HBeAg]-positive, 62 HBeAg-negative). HBcAg expression was positive when ≥10% of hepatocytes stained, and classified into nuclear, mixed, and cytoplasmic patterns. HBsAg expressions were intracytoplasmic (diffuse, globular, and submembranous) and membranous. The histologic activity index (HAI) and fibrosis stage followed Ishak system.

Results

In HBeAg-positive patients, older age, increased HAI score, advanced fibrosis, and reduced viral load were observed when HBcAg expression shifted from nucleus to cytoplasm in HBcAg-positive patients, and HBsAg expression from non-submembranous to submembranous in HBcAg-negative patients (all, p<0.05). In HBeAg-negative patients, only intracytoplasmic HBsAg expression patterns had clinical relevance with decreased ALT levels and viremia. In HBeAg-positive patients without favorable predictors of virologic response, negative HBcAg and membranous HBsAg expression predicted greater virologic response (both, p<0.05). The probability of HBeAg seroclearance was higher in patients with increased HAI or lacking HBcAg expression (both, p<0.05). Higher serum HBsAg levels and hepatocyte HBcAg positivity were associated with reduced serum HBsAg during first and post-first year treatment, respectively (both, p<0.05).

Conclusions

Hepatocyte HBcAg/HBsAg expression is a good marker for disease status and predicting treatment response.

Immunotherapy of hepatocellular carcinoma using chimeric antigen receptors and bispecific antibodies

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide with an overall survival rate of less than 15% in developed countries. Despite attempts at new therapeutic strategies, the majority of patients succumb to this cancer. Buttressed by the highly successful clinical impact in melanoma, immunotherapy is gaining momentum as the next treatment modality for many human cancers. Chimeric antigen receptors (CAR) contain the antigen binding moieties of a monoclonal antibody and the co-stimulatory and signaling domains associated with effector receptor signaling. Bispecific antibodies (BsAb) combine the binding specificities of two different monoclonal antibodies, one activating a receptor on a killer effector cell, while the other engaging a tumor-associated antigen to initiate tumor cytotoxicity. In this review, we survey the HCC targets for which CARs and bispecific antibodies have been generated. The pros and cons of these targets for T-cell and Natural Killer cell based immunotherapy will be discussed.

Intrahepatic distribution of hepatitis B virus antigens in patients with and without hepatocellular carcinoma

AIM: To study the intrahepatic expression of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) in chronic hepatitis B patients with and without hepatocellular carcinoma.

METHODS: A total of 33 chronic hepatitis B patients (mean age of 40.3 ± 2.5 years), comprising of 14 HBeAg positive and 19 HBeAg negative patients; and 13 patients with hepatitis B virus related hepatocellular carcinoma (mean age of 49.6 ± 4.7 years), were included in our study. Immunohistochemical staining for HBcAg and HBsAg was done using standard streptavidin-biotin-immunoperoxidase technique on paraffin-embedded liver biopsies. The HBcAg and HBsAg staining distributions and patterns were described according to a modified classification system.

RESULTS: Compared to the HBeAg negative patients, the HBeAg positive patients were younger, had higher mean HBV DNA and alanine transaminases levels. All the HBeAg positive patients had intrahepatic HBcAg staining; predominantly with “diffuse” distribution (79%) and “mixed cytoplasmic/nuclear” pattern (79%). In comparison, only 5% of the HBeAg-negative patients had intrahepatic HBcAg staining. However, the intrahepatic HBsAg staining has wider distribution among the HBeAg negative patients, namely; majority of the HBeAg negative cases had “patchy” HBsAg distribution compared to “rare” distribution among the HBeAg positive cases. All but one patient with HCC were HBeAg negative with either undetectable HBV DNA or very low level of viremia. Intrahepatic HBcAg and HBsAg were seen in 13 (100%) and 10 (77%) of the HCC patients respectively. Interestingly, among the 9 HCC patients on anti-viral therapy with suppressed HBV DNA, HBcAg and HBsAg were detected in tumor tissues but not the adjacent liver in 4 (44%) and 1 (11%) patient respectively.

CONCLUSION: Isolated intrahepatic HBcAg and HBsAg can be present in tumors of patients with suppressed HBV DNA on antiviral therapy; that may predispose them to cancer development.

Hepatitis B Core Antigen in Hepatocytes of Chronic Hepatitis B: Comparison between Indirect Immunofluorescence and Immunoperoxidase Method

Background

Hepatitis B virus (HBV) infection has many faces. Precore and core promoter mutants resemble inactive carrier status. The identification of hepatitis B core antigen (HBcAg) in hepatocytes may have variable clinical significance. The present study was undertaken to detect HBcAg in chronic hepatitis B (CHB) patients and to assess the efficacy of detection system by indirect immunofluorescence (IIF) and indirect immunoperoxidase (IIP).

Materials and methods

The study was done in 70 chronic HBV-infected patients. Out of 70 patients, eight (11.4%) were hepatitis B e antigen (HBeAg) positive and 62 (88.57%) were HBeAg negative. Hepatitis B core antigen was detected by indirect immunofluorescence (IIF) and indirect immunoperoxidase (IIP) methods in liver tissue.

Results

All HBeAg positive patients expressed HBcAg by both IIF and IIP methods. Out of 62 patients with HBeAg-negative CHB, HBcAg was detected by IIF in 55 (88.7%) patients and by IIP in 51 (82.26%) patients. A positive relation among viral load and HBcAg detection was also found. This was more evident in the case of HBeAg negative patients and showed a positive relation with HBV DNA levels.

Conclusion

Hepatitis B core antigen can be detected using the IIF from formalin fixed paraffin block preparation and also by IIP method. This seems to reflect the magnitudes of HBV replication in CHB.

How to cite this article

Raihan R, Tabassum S, Al-Mahtab M, Nessa A, Jahan M, Kabir CMS, Kamal M, Aguilar JC. Hepatitis B Core Antigen in Hepatocytes of Chronic Hepatitis B: Comparison between Indirect Immunofluorescence and Immunoperoxidase Method. Euroasian J Hepato-Gastroenterol 2015;5(1):7-10.

T cells expressing a chimeric antigen receptor that binds hepatitis B virus envelope proteins control virus replication in mice

BACKGROUND & AIMS

Antiviral agents suppress hepatitis B virus (HBV) replication but do not clear the infection. A strong effector T-cell response is required to eradicate HBV, but this does not occur in patients with chronic infection. T cells might be directed toward virus-infected cells by expressing HBV-specific receptors and thereby clear HBV and help to prevent development of liver cancer. In mice, we studied whether redirected T cells can engraft after adoptive transfer, without prior T-cell depletion, and whether the large amounts of circulating viral antigens inactivate the transferred T cells or lead to uncontrolled immune-mediated damage.

METHODS

CD8(+) T cells were isolated from mice and stimulated using an optimized protocol. Chimeric antigen receptors (CARs) that bind HBV envelope proteins (S-CAR) and activate T cells were expressed on the surface of cells using retroviral vectors. S-CAR-expressing CD8(+) T cells, which carried the marker CD45.1, were injected into CD45.2(+) HBV transgenic mice. We compared these mice with mice that received CD8(+) T cells induced by vaccination, cells that express a CAR without a proper signaling domain, or cells that express a CAR that does not bind HBV proteins (controls).

RESULTS

CD8(+) T cells that expressed HBV-specific CARs recognized different HBV subtypes and were able to engraft and expand in immune-competent HBV transgenic mice. After adoptive transfer, the S-CAR-expressing T cells localized to and functioned in the liver and rapidly and efficiently controlled HBV replication compared with controls, causing only transient liver damage. The large amount of circulating viral antigen did not impair or overactivate the S-CAR-grafted T cells.

CONCLUSIONS

T cells with a CAR specific for HBV envelope proteins localize to the liver in mice to reduce HBV replication, causing only transient liver damage. This immune cell therapy might be developed for patients with chronic hepatitis B, regardless of their HLA type.

What is expected from the pathologist in the diagnosis of viral hepatitis?

The clinician expects from the pathologist a clinically relevant diagnosis on the basis of liver biopsy interpretation. Today, a liver biopsy, as invasive procedure, is only justified when a significant benefit for the patient can be expected particularly with respect to the clinical management. Consequently, liver biopsy is usually not required in uncomplicated acute viral hepatitis. It is, however, an important diagnostic tool in chronic hepatitis and in transplanted liver to confirm the clinical diagnosis and to assess stage and grade of necroinflammation, treatment efficiency, and concurrent diseases. The diagnosis of liver disease is based on teamwork between clinician and pathologist. Evaluation of the biopsy in the clinical context requires clinical information and appropriate size and handling of the biopsy specimen. Aim of this review is the discussion of morphologic features of acute and chronic viral hepatitis with regard to their clinical relevance.

Pathology of chronic hepatitis B and chronic hepatitis C

Histologic evaluation of the liver is a major component in the medical management and treatment algorithm of patients with chronic hepatitis B (HBV) and chronic hepatitis C (HCV). Liver biopsy in these patients remains the gold standard, and decisions on treatment are often predicated on the degree of damage and stage of fibrosis. This article outlines the clinical course and serologic diagnosis of HBV and HCV for the clinician and the pathologist, who together have a close working relationship in managing patients with acute and chronic liver disease. The salient histologic features are elucidated in an attempt to provide the clinician with an understanding of the basic histopathology underlying chronic HCV and HBV.

Can engineered "designer" T cells outsmart chronic hepatitis B?

More than 350 million people worldwide are persistently infected with human heptatitis B virus (HBV) and at risk to develop liver cirrhosis and hepatocellular carcinoma making long-term treatment necessary. While a vaccine is available and new antiviral drugs are being developed, elimination of persistently infected cells is still a major issue. Recent efforts in adoptive cell therapy are experimentally exploring immunotherapeutic elimination of HBV-infected cells by means of a biological attack with genetically engineered "designer" T cells.

Liver biopsy findings in chronic hepatitis B

Liver biopsy plays a central role in treatment algorithms in patients with hepatitis B and remains the gold standard for evaluating hepatic pathology. The pathology of hepatitis B is diverse and reflects the natural history of infection. An acute hepatitic pattern with lobular disarray is seen in acute infection, during acute flares of disease, and with acute hepatitis D superinfection. In chronic hepatitis B, inflammation is less pronounced in the immune-tolerant phase and is prominent during immune-mediated viral clearance. Active inflammation appears to be the driving force for development of fibrosis. Inflammatory grades and fibrosis stage are assigned as is done for hepatitis C. Although current management guidelines recommend liver biopsies only in select patients based on age, viral levels, and hepatitis B e antigen status, these clinical and biochemical parameters do not show consistent correlations with liver histology. Liver biopsy also helps identify preneoplastic lesions including large cell and small cell change. Unlike in other causes of chronic hepatitis, immunostains are widely used and can help determine the phase of infection. Liver biopsies can also identify additional pathology that may contribute to liver disease such as steatohepatitis, iron overload, autoimmune hepatitis, and drug-induced injury. Thus, liver biopsy can play an important role in staging and grading chronic hepatitis B and should be more widely used in assessing the need for therapy.

Associations of Expressions of HBcAg and HBsAg with the Histologic Activity of Liver Disease and Viral Replication

BACKGROUND/AIMS

Subcellular localization of hepatitis B virus (HBV) core antigen (HBcAg) and HBV surface antigen (HBsAg) is known to be related to the activity of liver disease and the level of HBV replication. The aim of this study was to determine the correlation between histologic activity, viral replication, and the intracellular distributions of HBcAg and HBsAg.

METHODS

We enrolled 670 patients with chronic hepatitis B who underwent liver biopsy at Bundang CHA hospital between 1997 to 2007. The data from medical records were reviewed retrospectively.

RESULTS

The stage of fibrosis was higher (3.31+/-1.34 vs. 2.43+/-1.39, mean+/-SD, p<0.01) and the grade of necroinflammatory activity was higher (9.39+/-3.11 vs. 6.13+/-3.40, p<0.001) for the cytoplasmic expression of HBcAg (cHBcAg) than for the nuclear expression of HBcAg (nHBcAg). The serum HBV DNA level was 677.30+/-983.14 pg/mL in cHBcAg, 1274.46+/-1417.28 pg/mL in nHBcAg, 1121.01+/-1121.0 pg/mL in c-nHBcAg, and 229.47+/-678.92 pg/mL in negative (p<0.001). HBeAg was seropositive in 74.7% of patients with cHBcAg, 90.6% in those with nHBcAg, 90.3% in those with n-cHBcAg, and 55.6% in those with negative (p<0.001). The histologic stage and grade of hepatitis were not significantly correlated with the subcellular localization of intrahepatic HBsAg (p>0.05).

CONCLUSIONS

These observations suggest that the histologic activity of hepatitis is higher and viral replication is lower in cHBcAg positive patients than in those with nHBcAg.

Correlation of hepatocyte expression of hepatitis B viral antigens with histological activity and viral titer in chronic hepatitis B virus infection: an immunohistochemical study

BACKGROUND AND AIM

The localization of hepatitis B virus (HBV) core antigen to the nucleus or cytoplasm of hepatocytes has biological implications for viral packaging and persistence. This study examined the relationship between the localization of hepatitis B virus antigens, histological activity, and viral titer in patients with chronic HBV infection.

METHODS

Liver biopsies from 110 patients with chronic HBV infection were studied. Ishak's scoring system was used for the histological analysis. The localization of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) and the percentage of hepatocytes stained positive by immunohistochemistry were correlated with viral titer, histological activity, and fibrosis indices using Spearman rank correlation.

RESULTS

In 88 hepatitis B e-antigen (HBeAg)-positive individuals, the nuclear localization of HBcAg correlated significantly with DNA titer (r = 0.435, P = 0.001) and negatively with fibrosis (r = -0.297, P = 0.005). The cytoplasmic localization correlated significantly with histological activity (r = 0.211, P = 0.049). In 22 HBeAg-negative individuals, the nuclear localization of HBcAg correlated significantly with histological activity (r = 0.625, P = 0.002), DNA titer (r = 0.651, P = 0.009), and fibrosis (r = 0.447, P = 0.042). The cytoplasmic localization correlated significantly with DNA titer (r = 0.524, P = 0.045) and fibrosis (r = 0.528, P = 0.012). There was no correlation of HBsAg expression with DNA titer, histological activity index, or fibrosis in both groups. HBeAg-positive patients presented at a younger age.

CONCLUSION

In HBeAg-positive individuals, nuclear core antigen correlated with DNA titer, and cytoplasmic localization with histological activity, whereas in HBeAg-negative individuals, nuclear localization correlated with DNA titer, histological activity, and fibrosis, and cytoplasmic localization correlated with DNA titer and fibrosis, but not with histological activity. These observations suggest biological differences between HBeAg-positive and -negative disease.

T cells redirected against hepatitis B virus surface proteins eliminate infected hepatocytes

BACKGROUND & AIMS

The final goal in hepatitis B therapy is eradication of the hepatitis B virus (HBV) replication template, the so-called covalently closed circular DNA (cccDNA). Current antiviral treatment of chronic hepatitis B depends on interferon alpha or nucleoside analogues inhibiting the viral reverse transcriptase. Despite treatment, cccDNA mostly persists in the host cell nucleus, continues to produce hepatitis B surface antigen (HBsAg), and causes relapsing disease. We therefore aimed at eliminating persistently infected hepatocytes carrying HBV cccDNA by redirecting cytolytic T cells toward HBsAg-producing cells.

METHODS

We designed chimeric T-cell receptors directed against HBV surface proteins present on HBV-infected cells and used them to graft primary human T cells with antibody-like specificity. The receptors were composed of a single chain antibody fragment directed against HBV S or L protein fused to intracellular signalling domains of CD3xi and the costimulatory CD28 molecule.

RESULTS

Our results show that these chimeric receptors, when retrovirally delivered and expressed on the cell surface, enable primary human T cells to recognize HBsAg-positive hepatocytes, release interferon gamma and interleukin 2, and, most importantly, lyse HBV replicating cells. When coincubated with HBV-infected primary human hepatocytes, these engineered, antigen-specific T cells selectively eliminated HBV-infected and thus cccDNA-positive target cells.

CONCLUSIONS

Elimination of HBV cccDNA-positive hepatocytes following antiviral therapy is a major therapeutic goal in chronic hepatitis B, and adoptive transfer of grafted T cells provides a promising novel therapeutic approach. However, T-cell therapy may also cause liver damage and therefore needs further preclinical evaluation.

Does increased body mass index with hepatic steatosis contribute to seroclearance of hepatitis B virus (HBV) surface antigen in chronic HBV infection?

BACKGROUND

Overweight and hepatic steatosis have been increasingly recognized recently. This study aimed to test whether substantial amount of fatty infiltration in liver, which may interfere with cytoplasmic distribution of hepatitis B surface antigen (HBsAg), can contribute to HBsAg seroclearance in HBsAg carriers.

METHODS

Clinical and laboratory data including ultrasound grading of hepatic steatosis were studied in 54 HBsAg carriers with HBsAg seroclearance, and the results were compared with 108 age- and sex-matched carriers with HBsAg persistence.

RESULTS

Body mass index and ultrasound grading of hepatic steatosis were significantly higher in HBsAg carriers with HBsAg seroclearance than in those with HBsAg persistence. The degrees of hepatic steatosis correlated significantly with body mass index (P<0.001). The prevalence of mild hepatic steatosis showed no significant difference (33% (18/54) vs 31% (33/108), P=0.72), but moderate-severe hepatic steatosis was significantly more prevalent in patients with HBsAg seroclearance (33% (18/54) vs 13% (17/108), P=0.01). HBsAg carriers with moderate and severe hepatic steatosis were associated with a 3.2-fold (95% confidence interval: 1.2-8.4, P=0.02) and 3.9-fold (95% confidence interval: 1.1-14.2, P=0.04), respectively, increased odds of HBsAg seroclearance compared to those without hepatic steatosis.

CONCLUSION

Moderate-severe hepatic steatosis may contribute to HBsAg seroclearance in HBsAg carriers.

The degrees of hepatocyte cytoplasmic expression of hepatitis B core antigen correlate with histologic activity of liver disease in the young patients with chronic hepatitis B infection

Subcellular localizaton of HBcAg have been found to be related to the activity of liver disease and HBV replication. The aim of this study was to determine whether the degree of expression of HBcAg in the hepatocyte nucleus and cytoplasm reflects the level of viral replication and histological activity in chronic HBV infection. A total of 102 patients with biopsy proven chronic hepatitis B were included. There was a highly significant correlation between the levels of HBV DNA in serum and the degree of expression of HBcAg in the nucleus for HBeAg-positive(p=0.000) and negative patients(p=0.04). There was a highly significant, correlation between the degrees of expression of HBcAg in hepatocyte cytoplasm and histologic activities (p<0.01) for HBeAg-positive patients. The degrees of expression of HBcAg in the hepatocyte cytoplasm correlated positively with the lobular activities (p<0.01), but not correlated with the portal activity and fibrosis for HBeAg-negative patients. In conclusion, in the young patients with chronic B viral hepatitis, the degree of expression of HBcAg in the hepatocyte nucleus may affect viral load, and the degree of expression of HBcAg in the hepatocyte cytoplasm may affect histologic activities of liver disease.

Immune-mediated destruction of transfected myocytes following DNA vaccination occurs via multiple mechanisms

The delivery of antigenic proteins in the context of a DNA vaccine leads to the intracellular synthesis of antigen and the induction of both humoral and cellular immune responses. Subsequent to immune activation, any transfected cell expressing the immunogenic protein should, by the rules of immunology, become a legitimate target for removal by immune-mediated mechanisms. Herein, we have used an indirect assay of myocyte integrity following intra-muscular (i.m.) delivery of a DNA vaccine, in mice with various immune deficiencies, to determine which immunological mechanisms may be involved in destruction of antigen-expressing cells. We demonstrate that destruction of antigen- expressing myocytes following i.m. injection of a DNA vaccine is dependent on major histocompatibility complex (MHC) class II restricted CD4+ T cell activation, but is not mediated solely by MHC I-restricted or perforin-mediated lysis and appears to have a component that is antibody-mediated. Although we studied myocytes, the results likely represent what happens to any transfected cell expressing a foreign antigen. This study underscores the ability of DNA vaccines at inducing antigen-specific immune responses that include a number of effector mechanisms. From the perspective of gene therapy, this study highlights the significance of immune activation when considering strategies where maintenance of therapeutic gene expression is desired.

Low-level viremia and intracellular expression of hepatitis B surface antigen (HBsAg) in HBsAg carriers with concurrent hepatitis C virus infection

Assays of hepatitis B virus (HBV) replication and antigen expression in HBV surface antigen (HBsAg) carriers with concurrent hepatitis C or D virus (HCV or HDV) infection revealed that HCV and HDV can suppress HBV replication but that HCV also substantially suppresses HBV surface protein expression. HBsAg carriers with concurrent HCV infection thus have low-level viremia and intracellular HBsAg.

Natural history of chronic hepatitis B virus infection: an immunopathological study

Three clinicopathological phases of chronic hepatitis B virus (HBV) infection are identified. First, is immune tolerance of HBV. High levels of viraemia are associated with normal alanine aminotransferase (ALT) levels and minimal histological lesions. More than 30-40% of hepatocytes have the hepatitis B core antigen (HBcAg), predominantly in their nuclei. Maternally derived hepatitis B e antigen (HBeAg) crossing the placenta may result in the elimination of T helper cells responsive to HBeAg/HBcAg. This phase can last for periods ranging from a few weeks to 10 or more years until the immune tolerance is lost. Second, is the immune clearance of HBV. Intermediate levels of viraemia are associated with fluctuating ALT levels and active and ongoing hepatitis. Approximately 20-30% of hepatocytes have HBcAg, predominantly in their cytoplasm. Expression of pre-core defective HBV mutants during chronic HBV infection may lead to a reduction in the secretion of HBeAg and may trigger the beginning of the immuno-elimination phase. The mechanism of intrahepatic shift of HBcAg from the nucleus to the cytoplasm and the decreased levels of viraemia in this phase may be, at least in part, secondary to liver damage and regeneration. Third, is latent infection with residual integrated HBV. Undetectable viraemia is associated with normal ALT levels and no virus-induced liver damage. With regard to hepatocyte expression of HBsAg in chronic HBV infection, membrane staining of HBsAg on hepatocytes has been shown to correlate well with the presence of viraemia. The degree of cytoplasmic hepatitis B surface antigen (HBsAg) expression inversely correlates with the level of viraemia. Therefore, HBsAg carriers with high levels of viraemia have low levels of cytoplasmic hepatitis B surface antigen (HBsAg) expression, while those with low levels of viraemia have high levels of cytoplasmic HBsAg expression. However, several exceptions have been identified. High levels of viraemia associated with high levels of cytoplasmic HBsAg expression were recognized in patients with fibrosing cholestatic hepatitis. In contrast, low levels of viraemia associated with low levels of cytoplasmic HBsAg expression were recognized in patients with hepatitis C virus but not hepatitis D virus superinfection.

The degrees of hepatocyte nuclear but not cytoplasmic expression of hepatitis B core antigen reflect the level of viral replication in chronic hepatitis B virus infection

Although immunodetection of hepatitis B core antigen (HBcAg) in the liver has long been recognized as a marker of active hepatitis B virus (HBV) replication, the correlation between the level of viral replication and the degrees of expression of HBcAg in hepatocytes remains to be established. In this study, we examined the semiquantitative relationship between the level of HBV DNA in serum and the degree of expression of HBcAg in the hepatocyte nucleus or cytoplasm in 80 adults with chronic hepatitis B. Expression of HBcAg in hepatocytes was studied by the avidin-biotin immunoperoxidase method, and the results were scored on a scale of 0 to 4, values corresponding to the positivity of 0, 1 to 10, 11 to 25, 26 to 50, and > 50%, respectively, of hepatocytes examined. Serum HBV DNA was tested by a liquid hybridization assay, and the results were scored on a scale of 0 to 5, values corresponding to undetectable levels and levels of < or = 50, 51 to 100, 101 to 150, 151 to 200, and > 200 pg/ml, respectively. The results revealed a highly significant, positive correlation between the level of HBV DNA in serum and the degree of expression of HBcAg in nuclei (Spearman rank correlation coefficient [rs] = 0.653, P < 0.001). The mean scores (95% confidence intervals) of levels of HBV DNA in sera of patients whose levels of expression of HBcAg in nuclei received a score of 0 (n = 33), 1 or 2 (n = 35), and 3 or 4 (n = 12) were 1.3 (1.1 to 1.5), 2.5 (2.1 to 2.9), and 3.9 (3.1 to 4.7), respectively. However, no correlation between the level of HBV DNA in serum and the degree of expression of HBcAg in the cytoplasm was noted (rs = 0.026, P > 0.8). In conclusion, the degree of expression of HBcAg in the hepatocyte nucleus but not the cytoplasm can accurately reflect the level of viral replication in patients with chronic hepatitis B.

Histopathological aspects of viral hepatitis

The main method of classification of chronic viral hepatitis is now by cause, and the old histology-based classification is no longer considered appropriate. However, liver biopsy remains an important part of patient assessment and, in the context of clinical trials, biopsy findings are often scored in a semiquantitative manner. The concepts of grading and staging, borrowed from tumour pathology, have been introduced, representing the severity of the necroinflammatory lesion and the extent of its structural consequences respectively. The pathology of the individual forms of viral hepatitis A to G shows more similarities than differences. However, some pathological features are commonly associated with specific viruses. The combination of portal lymphoid follicles, bile duct damage, lobular activity and steatosis give chronic hepatitis C a characteristic histological profile. Very similar appearances have been noted in the limited number of biopsies so far reported from patients with known combined hepatitis C and G virus infection.

Subcellular localization of hepatitis B core antigen in relation to hepatocyte regeneration in chronic hepatitis B

BACKGROUND & AIMS

To test whether the dominant cytoplasmic expression of hepatitis B core antigen (HBcAg) in active chronic hepatitis B is secondary to liver damage and regeneration, the relationship between subcellular localization of HBcAg, liver inflammatory activity, and hepatocyte regeneration in chronic hepatitis B was studied.

METHODS

Correlation of the clinical and laboratory data with the topographical distribution of HBcAg was studied in 30 patients. The subcellular localization of HBcAg in relation to hepatocyte cell cycles was studied by double immunostaining of HBcAg and proliferating cell nuclear antigen.

RESULTS

Patients with predominant cytoplasmic HBcAg had significantly higher levels of biochemical and histological activities and proliferating cell nuclear antigen expression than patients with predominant nuclear HBcAg. The levels of proliferating cell nuclear antigen expression correlated positively with biochemical and histological activities and degrees of cytoplasmic HBcAg expression but negatively with degrees of nuclear HbcAg expression. Proliferating cell nuclear antigen expression was shown in 49% of hepatocytes with cytoplasmic HBcAg but in only 2% of hepatocytes with nuclear HBcAg.

CONCLUSIONS

These findings suggested that, following liver damage, the regeneration of surviving hepatocytes might cause the shift of intracellular HBcAg from nucleus to cytoplasm. As a result, the extent of nuclear HBcAg expression reduces with concomitant increase in cytoplasmic HBcAg expression.