Basic And Clinical Research In Treating Hepatitis B Virus-associated Glomerulonephritis

Background: HBV infection is a global public health problem, Of the approximately 3.5 billion people who have been infected worldwide, more than 1.3 billion are chronic carriers of HBV in our country. Extrahepatic tropism of HBV has been increasingly recognized in recent years, kidney is thought to be involved in HBV infection usually. The precise pathogenesis of hepatitis B virus-associated glomerulonephritis (HBV-GN) has not been determined. Until now, there has not an effective therapeutic principle to follow in the treatment of HBV-GN. The proportion of HBV-GN leads to end stage renal failure is growing rapidly, with the rising cost of therapies in our country. So, the purpose of our study is to research the precise pathogenesis and the intractable cause of HBV-GN, also to preliminarily explore an effective therapeutic principle fit to HBV-GN patients. The meaning of our study is not only economical, but also sociological.Objective: To investigate the pathological changes of liver and kidney in HBV-GN patients, to make sure the severity of the renal lesions is accord with that of the liver lesions or not. To explore an effective therapeutic principle fit to HBV-GN patients, the time when prednisone and immunosuppressive agent should be administrated. To investigate the relationship between cell apoptosis and the expression of Bax/ Bcl-2 protein in the kidney of HBV-GN patients, identify the effect of tubular and interstitial lesions in the pathogenesis of HBV-GN. To explore HBV mutation and HBV genetype in HBV-GN patients, and investigate the relationship between clinic outcome.Methods: Forty-four HBV-GN patients (aged from 15-70 years)underwent renal and liver biopsy, the degree of pathological changes were compared. The morphological changes of renal biopsy specimens were observed by light microscopy with HE, PAS, PASM, and Masson staining, immunofluorescent staining of IgG, IgA, IgM, C3, C4 as well as C1q and Fib were analyzed, immunohistochemical techniques were used to observe HBV markers(HBsAg,HBcAg,HBeAg)in renal and liver specimens, HBVDNA was detected by molecular hybridization in situ, the ultrastructural and microscopic changes of renal and liver were observed via transmission and scanning electron microscopy. Retrospective analysis of 44 cases from 1996 to 2006, these patients were divided into 3 groups, group A treated with steroid+mycophenolate mofetil(MMF)+lamivudine, group B treated with lamivudine only, group C treated with ACEI or ARB or diuretic agent. Clinical response of different therapy and side effects were considered. Apoptosis was evaluated by means of terminal deoxynucleotidyl transferase mediated d-UTP nick end labeling(TUNEL), immunohistochemistry was used to detect the protein of Bax and Bcl-2.Results: Among the renal lesions of HBV-GN, IgA nephropathy accounted for 27.3%(12/44), followed by membranous glomerulopathy 22.7%(10/44), the third was minimal change glomerulonephritis. Patients had different degrees of hepatic lesions, mild lesions accounting for 80%(8/10). HBsAg positive was presented in 24 patients kidney tissues, HBcAg positive was presented in 8 patients kidney tissues. HBsAg and/or HBcAg were presented in IgAN and MsPGN, mainly located in mesangial regionrenal, glomerular capillary and tubular epithelial cell. HBsAg only expressed in MN,MCD and MPGN. HBsAg positive was the most common in the liver tissue 80% (8/10). Two patients presented with HBcAg positive in both live and kidneys. HBV DNA was detected mainly in the cytoplasm of proximal tubular epithelia but not in glomerular cells. The ultrastructural and microscopic changes of renal and liver had no specificity. The severity of the renal lesions was not accord with that of the liver lesions. The degree of proteinuria reduction was significantly lower in steroid+mycophenolate mofetil+lamivudine treated group, most of the cases in group A were responsive to therapy, the clinical symptoms were improved accompany with anti-viral treatment. During our study, no severe HBV replication and severe side effects were reported. Compared with control group,apoptotic cells were more in number in renal tubular epithelial cell rather than glomerular cells, the expression of Bax and Bcl-2 was higher in the kidneys of HBV-GN patients. Positive staining of Bcl-2 and Bax were mainly located in renal tubular cells. Further, Bax and Bcl-2 may play important roles in the mechanism of. promoting apoptotic damage in human renal tubular cells. The incidence rate of HBV mutation was very low, only one YMDD mutations had been detected from serum specimens, one patient had same sense mutation with amino acids sequence no changing. HBV genetype in these HBV-GN patients were mainly C, Only 1 patients in this group reported having genetype B. Conclusions: The severity of the renal lesions was not accord with that of the liver lesions. the appearance of both HBcAg and HBsAg in liver indicated severe lesions of the organ. It is suggested that a liver-kidney holistic treatment is necessary for HBV-GN patients. Our studies have provided the evidence that HBV-GN has beneficial response to steroid+mycophenolate mofetil +lamivudine therapy, no severe HBV replication and severe side effects were reported.Apoptosis in the kidney may play an important role in the progression of HBV-GN, the change in Bax and Bcl-2 activities may be responsible for apoptosis in HBV-GN kidney. The incidence rate of HBV mutation was very low in our group, HBV genetype were mainly C.