VEGF-A: A NOVEL MECHANISTIC LINK BETWEEN CYP2C-DERIVED EET AND NOX4 IN DIABETIC KIDNEY DISEASE
Diabetes is associated with decreased epoxyeicosatrienoic acids (EET) bioavailability and increased levels of glomerular vascular endothelial growth factor A (VEGF-A) expression. We examined whether a soluble epoxide hydrolase (sEH) inhibitor protects against pathologic changes in diabetic kidney disease and whether the inhibition of VEGF-A signaling pathway attenuates diabetes-induced glomerular injury. We also aimed to delineate the crosstalk between cytochrome P450 2C (CYP2C)-derived EETs and VEGF-A. Streptozotocin (STZ)-induced type 1 diabetic (T1D) rats were treated with 25 mg/L of AUDA in drinking water for 6 weeks. In parallel experiments, T1D rats were treated with either SU5416 or humanized monoclonal anti-VEGF-A neutralizing antibody for 8 weeks. Following treatment, the rats were euthanized, 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 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 ROS production. These findings were replicated in vitro in rat and human podocytes cultured in a diabetic milieu. Taken together, our results indicate that hyperglycemia-induced glomerular injury is mediated by the downregulation of CYP2C11-derived EET formation, followed by the activation of the VEGF-A signaling and upregulation 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.