[Podocyte depletion in children with hepatitis B virus-associated membranous nephropathy]

Hepatitis B virus-associated membranous nephropathy (HBV-MN) is a disease characterized by podocytopathy. Podocyte is a terminally differentiated cell with limited capability of proliferation. Thus, damage of podocyte might result in decreased cell number, and then lead to the development of marked proteinuria and glomerulosclerosis. The present study aimed to investigate the changes of glomerular podocyte number in the children with hepatitis B virus-associated membranous nephropathy (HBV-MN), and their significance in the pathogenesis of HBV-MN.

Podocytes were identified through specific immunohistological staining of Wilms tumor gene protein 1 (WT1), a characteristic marker for podocyte nuclei, and podocyte numerical density (Nv), mean glomerular tuft volume (V) and the podocyte number per glomerulus (Npodo) were estimated through Weibel-Gomez method in 19 children with biopsy-proven HBV-MN and 8 children with thin basement membrane disease (control group), and analyses were made for possible correlation with clinical, serological and pathological data.

Among the 19 cases with HBV-MN, 3 showed microvillus-like foot process of podocytes, granular degeneration of podocyte were found in 4 cases, vacuolization in 1 case and podocyte detachment in 2 cases. Nv and Npodo were significantly decreased in children with HBV-MN compared with control group (t = 12.851, P = 0.0002 and t = 6.433, P = 0.0002, respectively). Moreover, the number of podocytes decreased more significantly in patients with stronger HBsAg deposition (> ++) than those with weak HBsAg deposition (< or = ++), P = 0.004, but no significant difference was found between patients with phase III or IV of HBV-MN and those with phase Ior II in podocyte number per glomerulus (P = 0.5262) and podocyte numerical density (P = 0.3564). Podocyte numerical density decreased more significantly in patients with massive proteinuria (> or = 2 g/24 h) than those with moderate proteinuria (< 2 g/24 h), P = 0.0488. The numbers of podocyte correlated significantly with serum levels of C(3) (r = 0.548, P = 0.028), but did not correlate with serum levels of albumin (r = -0.037, P = 0.891).

All patients with HBV-MN showed podocyte damage and decreased number per glomerulus, which may play an important role in the pathogenesis of HBV-MN in children.