The role of VEGF-A in glomerular development and function

Vascular endothelial growth factor is a major regulator of blood vessel biology and is highly expressed in presumptive and mature podocytes within the glomerulus. It has long been recognized that dysregulation of this factor occurs in a number of glomerular diseases; however, definitive proof that it plays a pathogenic or developmental role in glomerular biology has remained elusive. This review will summarize some of the recent advances in our understanding of the role(s) of VEGF in these processes.

Gene targeting in the mouse has shown that tight regulation of vascular endothelial growth factor is required for development and maintenance of the glomerular filtration barrier. Podocyte-specific deletion of both alleles leads to congenital nephropathy and perinatal lethality. The glomeruli of mice that lack the 164 and 184 isoforms but express the 120 isoform, are smaller and have fewer capillary loops, whereas mice with podocyte-specific haploinsufficiency for all isoforms develop glomerular endotheliosis, the renal lesion seen in preeclampsia. Elevated levels of the soluble vascular endothelial growth factor receptor 1, which binds and inhibits circulating forms of VEGF were identified in patients with preeclampsia; rats injected with this soluble receptor develop hypertension, endotheliosis and proteinuria, similar to the lesion seen in podocyte-specific haploinsufficient VEGF mice. Conversely, podocyte-specific overexpression of the 164 isoform leads to collapsing glomerulopathy, the classic lesion seen in HIV-associated nephropathy.

These results demonstrate that vascular endothelial growth factor plays a critical role in glomerular development and function, and provides the foundation to develop novel diagnostic or therapeutic tools for patients with glomerular disease.