VEGF-A: A Novel Mechanistic Link Between CYP2C-Derived EETs and Nox4 in Diabetic Kidney Disease

Abstract

Diabetes is associated with decreased epoxyeicosatrienoic acid (EET) bioavailability and increased levels of glomerular vascular endothelial growth factor A (VEGF-A) expression. We examined whether a soluble epoxide hydrolase inhibitor protects against pathologic changes in diabetic kidney disease and whether the inhibition of the VEGF-A signaling pathway attenuates diabetes-induced glomerular injury. We also aimed to delineate the cross talk between cyto-chrome P450 2C (CYP2C)–derived EETs and VEGF-A. Streptozotocin-induced type 1 diabetic (T1D) rats were treated with 25 mg/L of 12-(3-adamantan-1-yl-ureido)-do-decanoic acid (AUDA) in drinking water for 6 weeks. In par-allel experiments, T1D rats were treated with either SU5416 or humanized monoclonal anti–VEGF-A neutralizing antibody for 8 weeks. Following treatment, the rats were eu-thanized, and kidney cortices were isolated for further analysis. Treatment with AUDA attenuated the diabetes-induced decline in kidney function. Furthermore, treatment with AUDA decreased diabetes-associated oxidative stress and NADPH oxidase activity. Interestingly, the downregulation of CYP2C11-derived EET formation is found to be correlated with the activation of the VEGF-A signaling pathway. In fact, inhibiting VEGF-A using anti-VEGF or SU5416 markedly attenuated diabetes-induced glomerular injury through the inhibition of Nox4-induced reactive oxygen species production. These findings were replicated in vitro in rat and human podocytes cultured in a diabetic milieu. Taken together, our results indicate that hy-perglycemia-induced glomerular injury is mediated by the downregulation of CYP2C11-derived EET formation, fol-lowed by the activation of VEGF-A signaling and upregula-tion of Nox4. To our knowledge, this is the first study to highlight VEGF-A as a mechanistic link between CYP2C11-derived EET production and Nox4.