Nox1-based NADPH oxidase-derived superoxide is required for VSMC activation by advanced glycation end-products

Vascular diseases are important clinical complications of diabetes. Advanced glycation end-products (AGE) are mediators of vascular dysfunction, but their effects on vascular smooth muscle cell (VSMC) ROS production are unclear. We studied the source and downstream targets of AGE-mediated ROS and reactive nitrogen species production in these cells. Significant increases in superoxide production in AGE-treated VSMC were measured using lucigenin (7650 ± 433 vs 4485 ± 424 LU/10⁶ cells, p < 0.001) or coelenterazine (277,907 ± 71,295 vs 120,456 ± 4140 LU/10⁶ cells, p < 0.05) and confirmed by ESR spectroscopy. These signals were blocked by the flavin-containing oxidase inhibitor diphenylene iodonium (DPI). AGE-stimulated NF-κB activity was abolished by DPI and the superoxide scavenger MnTBAP. AGE differentially regulated VSMC NADPH oxidase catalytic subunits, stimulating the transcription of Nox1 (201 ± 12.7%, p < 0.0001), while having no effect on Nox4. AGE also increased 3-nitrotyrosine formation, which was inhibited by MnTBAP, DPI, or the NOS inhibitor L-NAME. Regarding the source of NO, AGE stimulated inducible nitric oxide synthase mRNA (1 vs 9.7 ± 3.0, p = 0.046), which was abolished by a NF-κB inhibitor, SOD, catalase, or siRNA against Nox1. This study establishes that AGE activate iNOS in VSMC through a ROS-sensitive, NF-κB-dependent mechanism involving ROS generation by a Nox1-based oxidase.