Background: In experimental extracapillary glomerulonephritis (EG) podocytes migrate, proliferate and change phenotype, and play a pivotal role in crescent formation. Hepatocyte Growth Factor (HGF) is an injury-induced effector of tissue repair that causes cell migration, growth and transdifferentiation via its receptor Met.
Methods: In 11 patients with EG we measured serum levels of HGF and investigated whether serum induces the release of HGF by Peripheral Blood Mononuclear Cells (PBMC). In renal biopsies we studied the expression of Met. In cultured podocytes we studied Met expression, migration, growth and morphological changes induced by recombinant (r) HGF.
Results: In patients with EG average serum levels of HGF (0.73 ng/ml) were higher than in normal volunteers (N, 0.10 ng/ml, p<0.01) and in patients with non-crescentic glomerular disease (GD, 0.18 ng/ml, p<0.01). Serum of EG induced a significant HGF release by PBMC (mean 0.58 ng/ml) in comparison with serum of N and GD (0.07 and 0.06 ng/ml, respectively, both p<0.001). Met was strongly expressed in crescents. Cultured podocytes expressed Met, and rHGF induced in podocytes a time- and dose-dependent migration, growth and epithelial to mesenchymal transdifferentiation.
Conclusions: These results suggest that HGF/Met system participates in the process of crescent formation by inducing podocyte migration, growth and mesenchymal transformation.