Ultrastructure of kidney from three patients with HBeAg-associated nephropathy with special reference to virus-like particles in the glomerular tufts

Infection of hepatitis B virus in extrahepatic endothelial tissues mediated by endothelial progenitor cells

Background

Hepatitis B virus (HBV) replication has been reported to be involved in many extrahepatic viral disorders; however, the mechanism by which HBV is trans-infected into extrahepatic tissues such as HBV associated myocarditis remains largely unknown.

Results

In this study, we showed that human cord blood endothelial progenitor cells (EPCs), but not human umbilical vein endothelial cells (HUVECs) could be effectively infected by uptake of HBV in vitro. Exposure of EPCs with HBV resulted in HBV DNA and viral particles were detected in EPCs at day 3 after HBV challenge, which were peaked around day 7 and declined in 3 weeks. Consistently, HBV envelope surface and core antigens were first detected in EPCs at day 3 after virus challenge and were retained to be detectable for 3 weeks. In contrast, HBV covalently closed circular DNA was not detected in EPCs at any time after virus challenge. Intravenous transplantation of HBV-treated EPCs into myocardial infarction and acute renal ischemia mouse model resulted in incorporation of HBV into injured heart, lung, and renal capillary endothelial tissues.

Conclusion

These results strongly support that EPCs serve as virus carrier mediating HBV trans-infection into the injured endothelial tissues. The findings might provide a novel mechanism for HBV-associated myocarditis and other HBV-related extrahepatic diseases as well.

Existence and significance of hepatitis B virus DNA in kidneys of IgA nephropathy

AIM

To investigate the existence and significance of hepatitis B virus (HBV) DNA in the pathogenesis of IgA nephropathy (IgAN).

METHODS

Fifty cases of IgAN with HBV antigenaemia and/or hepatitis B virus antigens (HBAg, or HBsAg, HBcAg) detected by immunohistochemistry in renal tissues were enrolled in our study. The distribution and localization of HBV DNA were observed using in situ hybridization. Southern blot analysis was performed to reveal the state of renal HBV DNA.

RESULTS

Among the 50 patients with IgAN, HBs antigenemia was detected in 17 patients (34%). HBAg in renal tissues was detected in 48 patients (96%), the positive rate of HBAg, HBsAg, and HBcAg was 82% (41/50), 58% (29/50), and 42% (21/50) in glomeruli, respectively; and was 94% (47/50), 56% (28/50) and 78% (39/50) in tubular epithelia, respectively. Positive HBV DNA was detected in 72% (36/50) and 82% (41/50) cases in tubular epithelia and glomeruli respectively by in situ hybridization, and the positive signals were localized in the nuclei of tubular epithelial cells and glomerular mesangial cells as well as infiltrated interstitial lymphocytes. Moreover, 68% (34/50) cases were proved to be HBV DNA positive by Southern blot analysis, and all were the integrated form.

CONCLUSION

HBV infection might play an important role in occurrence and progress of IgAN. In addition to humoral immune damages mediated by HBAg-HBAb immune complex, renal tissues of some IgAN are directly infected with HBV and express HBAg in situ, and the cellular mechanism mediated by HBV originating from renal cells in situ may also be involved in the pathogenesis of IgAN.

Role of hepatitis B virus infection in pathogenesis of IgA nephropathy

AIM: To investigate the role of hepatitis B virus (HBV) in the pathogenesis of IgA nephropathy (IgAN).

METHODS: HBV antigens (HBAg, or HBsAg, HBcAg, and HBeAg) in renal tissues with IgAN were detected by immunohistochemical technique. The distribution and localization of HBV DNA were observed by using in situ hybridization. Southern blot analysis was performed to reveal the state of renal HBV DNA.

RESULTS: Among 100 patients with IgAN, HBs antigenemia was detected in 18 patients (18.00%). HBAg in renal tissues was detected in 31 patients (31.00%), the positive rate of HBAg, HBsAg and HBcAg was 64.52% (20/31), 32.26% (10/31), 32.26% (10/31), respectively in glomeruli. HBcAg was also found in tubular epithelia and interstitia, which was 45.16% (14/31) and 6.45% (2/31), respectively. Five out of six cases with positive HBV DNA by in situ hybridization were proved to be HBV DNA positive by Southern blot analysis, and all were of the integrated form. Eight specimens were demonstrated to be HBV DNA positive by in situ hybridization, which was localized in the nuclei of tubular epithelial cells and glomerular mesangial cells as well as in infiltrated interstitial lymphocytes.

CONCLUSION: There is a relationship between HBV infection and IgAN. In addition to the humoral immune damage mediated by HBAg-HBAb immune complex, the cellular mechanism mediated by HBV originating from renal cells in situ may be also involved in the pathogenesis of IgAN.