Endothelial cell injury in acute and chronic glomerular lesions in patients with IgA nephropathy

Summary Endothelial cell injury may contribute to the progression of various glomerular diseases. In the present study, we examined glomerular capillary injury in acute and chronic glomerular lesions in patients with Immunoglobulin A nephropathy (IgAN). We selected renal biopsy samples of IgAN (n = 200), and glomerular capillary injury in the acute and chronic glomerular lesions was assessed using immunohistochemistry for CD34 and electron microscopy. We examined the correlations between acute and chronic glomerular lesions and proteinuria, hematuria, and the renal function. The injured glomerular capillaries in the acute glomerular lesions were characterized morphologically by the separation of CD34+ endothelial cells from the glomerular basement membrane and the loss of glomerular endothelial cells and capillaries, together with inflammatory cell infiltration, fibrin exudation, rupture of the glomerular basement membrane, and/or crescent formation. In addition, the injured capillaries in the chronic glomerular lesions were characterized by the loss of CD34+ glomerular endothelial cells and capillaries exhibiting segmental and global glomerular sclerosis with or without fibrous crescents. In the acute glomerular lesions, the presence of endocapillary hypercellularity, fibrinoid necrosis, and cellular and fibrocellular crescents correlated significantly with hematuria, with or without proteinuria. In the chronic glomerular lesions, a significant relationship was evident between segmental or global sclerosis and proteinuria and/or the serum creatinine level. In conclusion, injuries of glomerular capillaries and the loss of endothelial cells occurred in the acute and chronic glomerular lesions in IgAN and may contribute to the development of hematuria, proteinuria, and renal dysfunction.