The severity of glomerular endothelial cell injury is associated with infiltrating macrophage heterogeneity in endocapillary proliferative glomerulonephritis

<jats:title>Abstract</jats:title><jats:p>Endocapillary proliferation occurs in various types of glomerulonephritis (GN), with varying prognoses. We examined 42 renal biopsy samples representing endocapillary proliferative lesions from post-streptococcal acute GN (PSAGN), Henoch–Schönlein purpura nephritis (HSPN), and lupus nephritis (LN). In PSAGN, the glomerular capillary network was maintained, although severe lesions displayed dots or short, curved lines, indicating CD34-positive capillaries and suggesting capillary obstruction. Conversely, patients with LN and HSPN displayed obstruction of CD34-positive capillaries with dissociation from the glomerular basement membrane even in mild lesions. According to computer-assisted morphologic analysis, the cell density did not differ between the diseases. However, in PSAGN, the number of capillary loops was significantly increased, with a larger glomerular capillary luminal area than in the other groups. In addition, the number and frequency of CD163-positive cells (M2 macrophages) tended to be higher in PSAGN, while there were no significant differences in the number of CD68-positive (total) macrophages. These results indicate that in PSAGN, endothelial cell damage is less severe, and angiogenesis may be promoted. The severity of endothelial cell injury in each disease may be associated with differences in infiltrating inflammatory cell phenotypes.</jats:p>