Hepatocyte hepatitis B surface antigen expression in chronic hepatitis B virus carriers in Singapore: correlation with viral replication and liver pathology

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.

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.

Pathogenesis and screening for hepatocellular carcinoma

Hepatocellular carcinoma is an increasingly common clinical problem. Investigators have begun to understand aspects of the pathogenesis of the tumor, mainly from a morphologic point of view. Preneoplastic lesions and early cancer may be difficult to distinguish radiologically. Nonetheless, programs for surveillance of liver cancer have been developed. Little uniformity exists in methods of surveillance, and even less in methods of investigation and follow-up after an abnormal result is obtained. This article attempts to bring some rigor to the understanding of hepatocellular carcinoma.

Identification of a pre-S2 mutant in hepatocytes expressing a novel marginal pattern of surface antigen in advanced diseases of chronic hepatitis B virus infection

BACKGROUND AND AIMS

The expression of hepatitis B viral (HBV) antigens in liver tissue reflects the replicative status of chronic HBV infection. We have previously recognized a novel marginal pattern of hepatitis B surface antigen (HBsAg) in hepatocytes, which usually clusters in groups and emerges at the late non-replicative phase. This study was designed to investigate whether the marginal-type HBsAg represented the gene product of a specific HBV-surface mutant.

METHODS

Microdissection of cirrhotic nodules homogeneously expressing marginal HBsAg was performed on two of 12 resected livers from HBsAg-seropositive patients with hepatocellular carcinoma. The gene presumably encoding marginal HBsAg was polymerase chain reaction (PCR)-cloned, sequenced and analysed. In vitro transfection and expression of the cloned surface mutant plasmids were performed on the Huh7 cell line to illustrate intrahepatic HBsAg expression.

RESULTS

Immunohistochemical staining revealed that the marginal HBsAg was positive for pre-S1 and thus contained large surface proteins. The PCR cloning and sequencing of the genes presumably encoding marginal-type HBsAg in both cases revealed the same deletion at the 5' terminus (nt 2-55) of pre-S2. A point mutation on the small-surface (S) antigen was also found in one case. The pre-S2 deletion sequence and the mutation sites of the S gene coincide with human lymphocyte antigen-restricted T- and/or B-cell epitopes. In vitro transfection of the mutant plasmid revealed a blot-like retention or accumulation of HBsAg in the cytoplasm or at the periphery of hepatocytes, accompanied by a decreased secretion of HBsAg in the culture supernatant, mimicking intrahepatic expression.

CONCLUSION

A natural pre-S2 deletion mutant was identified in hepatocytes expressing a novel marginal pattern of HBsAg, which probably contains mutant, large, surface proteins. The biological significance of the pre-S2 deletion mutant should be interesting in view of the clustering proliferation of hepatocytes expressing marginal HBsAg.