Critical role of the NADPH oxidase subunit p47phox on vascular TLR expression and neointimal lesion formation in high-fat diet-induced obesity

Reactive oxygen species (ROS) formation is associated with inflammation and vasculature dysfunction. We investigated the potential role of the NADPH oxidase on vascular Toll-like receptor (TLR) expression and carotid neointimal formation in high-fat (HF) diet-induced obesity (DIO) model. Using mice DIO and common carotid artery flow cessation-induced lesion formation models, we examined vascular TLR2 and TLR4 expression and neointimal formation in NADPH oxidase subunit p47(phox)-deficient (p47(phox-/-)) mice. Feeding C57BL/6J mice an HF diet for 22 weeks resulted in significant increases in p47(phox), TLR2 and TLR4 expression in vascular tissues compared with mice fed a low-fat (LF) diet. Minimal changes in TLR2 and TLR4 expression was detected in p47(phox-/-) DIO mice. Furthermore, flow cessation-induced angiogenic and inflammatory response and neointimal formation were significantly attenuated in p47(phox-/-) DIO mice compared with wild-type DIO mice. In addition, exposure of endothelial cells to leptin led to ROS formation; this was accompanied by upregulation of TLR2, TLR4 expression and its downstream signaling. Leptin also increased endothelial cell migration and proliferation. Pharmacological inhibition of NADPH oxidase or genetic deletion of p47(phox) significantly diminished these alterations. Obesity increases neointimal formation via a mechanism involving p47(phox)-TLRs signaling, suggesting that the NADPH oxidase may represent a potential novel therapeutic target for the treatment of obesity-associated vascular inflammation and dysfunction.