Hepatitis B virus-associated nephropathy

A direct causal association between hepatitis B virus (HBV) infection and the development of nephropathy remains controversial. Epidemiological studies have shown that chronic carriage of HBV in some individuals (particularly children) leads to the development of nephrotic syndrome with a strong male predominance, the commonest histological type being membranous nephropathy (MN). Spontaneous clearance of HBV antigens (particularly the HBeAg) leads to abrogation of proteinuria. The isolation of immune complexes in the kidney suggests that the pathogenesis of the disease may have an immune-complex basis. Recent studies showing expression of HBV viral antigens in kidney tissue suggest direct viral-induced pathological alterations and chronic immunologic injury. Biosocial studies have detected no correlation between HBV carriage and proteinuria using both quantitative and qualitative urinary protein analysis. Genetic studies of HLA class I and II genes showed a predisposition to MN but no similar correlation in those with milder degrees of proteinuria. These findings suggest that milder proteinuria is unrelated to HBV carriage or genetic factors but the development of nephropathy, particularly MN, in patients with chronic HBV carriage (HBsAg and/or HBV DNA positive) is based on an interaction of virus and host factors. Although the natural history of the disease tends to remission with preservation of renal function, there is considerable morbidity and a small but significant mortality. Use of naturally occurring cytokines (such as interferon-alpha2b) and other candidate therapies accelerates clearance of the virus and proteinuria. The most effective tool in reducing the incidence of the disease is the use of HBV vaccines.