Neutrophil exocytosis induces podocyte cytoskeletal reorganization and proteinuria in experimental glomerulonephritis

Acute glomerulonephritis is characterized by rapid glomerular neutrophil recruitment, proteinuria, and glomerular hypercellularity. The current study tested the hypothesis that the release of neutrophil granule contents plays a role in both the loss of filtration barrier leading to proteinuria and the increase in glomerular cells. Inhibition of neutrophil exocytosis with a peptide inhibitor prevented proteinuria and attenuated podocyte and endothelial cell injury but had no effect on glomerular hypercellularity in an experimental acute glomerulonephritis model in mice. Cultivation of podocytes with neutrophil granule contents disrupted cytoskeletal organization, an in vitro model for podocyte effacement and loss of filtration barrier. Activated, cultured podocytes released cytokines that stimulated neutrophil chemotaxis, primed respiratory burst activity, and stimulated neutrophil exocytosis. We conclude that crosstalk between podocytes and neutrophils contributes to disruption of the glomerular filtration barrier in acute glomerulonephritis. Neutrophil granule products induce podocyte injury but do not participate in the proliferative response of intrinsic glomerular cells.