Abstract 14054: Monocyte Vascular Endothelial Growth Factor Receptor-1 Signaling in Peripheral Artery Disease

Abstract

Introduction: Peripheral artery disease (PAD) is caused by atherosclerosis of large arteries of the leg(s). Beyond complications from poor perfusion to the legs, patients with PAD suffer higher than expected rates of heart attack and strokes. Monocytes are subdivided into three subtypes: CD14++CD16- (classical), CD14+CD16+ (intermediate), and CD14-CD16+ (non-classical). The intermediate monocyte subtype is linked to PAD. Vascular Endothelial Growth Factor receptor (VEGFR)-1 is a member of tyrosine kinase family that is expressed in monocytes and has high affinity for the VEGF-A ligand. Recent studies showed that inhibition of VEGFR1/STAT-3 signaling decreases angiogenesis in PAD. We hypothesized that in patients with PAD, intermediate monocytes would have less VEGFR1/STAT3 activation than controls. Methods: Blood samples were collected from PAD patients (n=11) and risk factor closely matched controls (n=17). PBMCs were isolated by gradient centrifugation. By flow cytometry, gating strategy on monocytes was done by excluding granulocytes (CD66b), B and T lymphocytes (CD3,CD19), and natural killer cells (CD56). Next, monocytes were subdivided into three populations (intermediate, classical, and non-classical) by gating according to their CD14/CD16 expression. Within each population, levels of p(Y1333)VEGFR1, VEGFR1, pSTAT3, and STAT3 were determined. Results: Data from flow cytometry analysis showed a significant increase in the intermediate monocyte population in PAD vs control (~1.5-fold change; p=0.01). However, there was no significant difference in the non-classical or classical monocytes between PAD and control. Within the intermediate monocytes, P(Y1333) VEGFR1/VEGFR1 was decreased (~2-fold change) and pSTAT3/STAT3 was significantly decreased (~2-fold change) in PAD vs control. In both the non-classical and classical monocytes, there was no significant difference in either phosphorylated receptor between PAD and control. Conclusions: The data confirm the intermediate monocyte is associated with PAD and suggest that VEGFR1/STAT3 signaling is decreased in intermediate monocytes in PAD vs control. Understanding the mechanism of VEGFR1 activation may prove to be a promising therapeutic target for patients with PAD.