HBeAg-positive hepatitis delta: virological patterns and clinical long-term outcome

BACKGROUND AND AIMS

The presence of the hepatitis B virus (HBV)-eAg in patients with hepatitis B is associated with higher HBV replication and with an increased risk to develop liver-related clinical endpoints defined as liver related death, liver transplantation, development of hepatocellular carcinoma and hepatic decompensation. The aim of this study was to investigate the role of HBeAg in patients co-infected with the hepatitis D virus (HDV).

METHODS

We studied virological markers of HBV and HDV infection and as well as biochemical and clinical features of liver disease in a cohort of 534 anti-HDV-positive patients. In addition, we compared the clinical long-term outcome of HBeAg-positive HDV-infected patients with HBeAg-negative control patients matched for age, gender and baseline-MELD score.

RESULTS

HBeAg-positive hepatitis delta was detected in 71 of 534 patients (13.3%). HBeAg positivity was associated with a higher biochemical disease activity and higher HBsAg levels in HDV co-infected patients. Sixty one per cent of the HBeAg-positive HDV-infected patients presented with HBV DNA levels below 2000 IU/ml, at least once during follow-up. Both HBeAg-positive and -negative patients showed a similar severe clinical long-term course with about half of the patients developing a liver-related clinical complication after a median follow-up period of 51 months (range: 9-193 months).

CONCLUSIONS

HBV DNA levels are low in both HBeAg-negative and HBeAg-positive patients suggesting suppressive effects of HDV on HBV irrespective of the phase of HBV infection. The clinical long-term outcome of HBeAg-positive patients is not different to HBeAg-negative patients infected with the HDV.

Ectopic expression of murine CD47 minimizes macrophage rejection of human hepatocyte xenografts in immunodeficient mice

Macrophages play an important role in the rejection of xenogeneic cells and therefore represent a major obstacle to generating chimeric mice with human xenografts that are useful tools for basic and preclinical medical research. The signal inhibitory regulatory protein α (SIRPα) receptor is a negative regulator of macrophage phagocytic activity and interacts in a species-specific fashion with its ligand CD47. Furthermore, SIRPα polymorphism in laboratory mouse strains significantly affects the extent of human CD47-mediated toleration of human xenotransplants. Aiming to minimize macrophage activity and thus optimize human cell engraftment in immunodeficient mice, we lentivirally transduced murine CD47 (Cd47) into human liver cells. Human HepG2 liver cells expressing Cd47 were less frequently contacted and phagocytosed by murine RAW264.7 macrophages in vitro than their Cd47-negative counterparts. For the generation of human-mouse chimeric livers in immunodeficient BALB-ΔRAG/γ(c) -uPA (urokinase-type plasminogen activator) mice, freshly thawed cryopreserved human hepatocytes were transduced with a lentiviral expression vector for Cd47 using a refined in vitro transduction protocol immediately before transplantation. In vivo, Cd47-positive human primary hepatocytes were selectively retained following engraftment in immunodeficient mice, leading to at least a doubling of liver repopulation efficiencies.

CONCLUSION

We conclude that ectopic expression of murine Cd47 in human hepatocytes selectively favors engraftment upon transplantation into mice, a finding that should have a profound impact on the generation of robust humanized small animal models. Moreover, dominance of ectopically expressed murine Cd47 over endogenous human CD47 should also widen the spectrum of immunodeficient mouse strains suitable for humanization.

Development of a protocol for the quantitative determination of HBeAg using the Elecsys® HBeAg immunoassay

Loss of hepatitis 'e' antigen (HBeAg) in patients with HBeAg-positive chronic hepatitis B is associated with improved long-term clinical outcome and is defined as a goal of antiviral treatment by clinical practice guidelines. Recent studies suggest that baseline levels and on-treatment monitoring of HBeAg levels may identify patients most likely to respond to therapy. The aim of this study was the development of a protocol for the quantitative determination of HBeAg using the Elecsys® HBeAg immunoassay. The linear range of the Elecsys® HBeAg immunoassay was established using recombinant HBeAg and five different diluents. The assay was validated against the Paul Ehrlich Institute (PEI) international standard serum. Linearity was demonstrated up to a cut-off index (COI) of 1000, independent of the diluent used. Optimal linearity was obtained using the Elecsys® Universal Diluent. Using the PEI reference standard, conversion factors were established as 4.50 COI for 1 PEIU/mL corresponding to 0.222 PEIU/mL for a COI of 1. Based on the results from these analyses, a simple algorithm for the quantitative measurement of HBeAg using the Elecsys® HBeAg immunoassay was developed. Using a simple algorithm with an initial 1:40 dilution, the Elecsys® HBeAg assay provides robust quantification of serum HBeAg in an easy-to-use and rapid system. The use of a commercially available, standardized diluent improves comparability between laboratories.