Abstract 15492: ADAM12 Modifies Severity of Peripheral Arterial Disease; Evidence From Preclinical and Human Studies
Objective: Peripheral arterial disease (PAD) results from atherosclerotic occlusion in the arteries of the lower extremities. Recent evidence suggests genetic factors may affect severity of PAD in the setting of an occlusion, however the specific genes involved are not known. We previously showed a locus on mouse chromosome 7 (LSq-1) modified PAD severity. The goal of this study was to identify the function of a leading candidate gene within this locus.
Method: Perfusion recovery following experimental PAD was analyzed in 9 mouse strains. Haplotype blocks were generated based on SNP alleles common in strains that recover well but absent in strains that recover poorly. Gene expression was assessed by quantitative RT-PCR. Effect of gain or loss of our candidate gene was assessed in vitro and in vivo. In a human cohort with critical limb ischemia (CLI, N=162) and intermittent claudication (IC, N=627), tagged SNPs were genotyped for association with CLI using multivariable logistic regression.
Results: We identified 4 haplotype blocks containing 25 genes of which 4 were expressed at higher levels in ischemic hind limbs of mice that recover well (C57BL/6) compared to expression in mice that recover poorly (Balb/c). Of the 4 genes, ADAM12 showed the most differential expression with (>3 fold) up-regulation in ischemic endothelial cells (EC). In simulated ischemia, in vitro, over expression of ADAM12 in EC’s increased cell proliferation and survival. “Knock down” of ADAM12 by shRNA decreased AKT phosphorylation, impaired EC proliferation and increased apoptosis in simulated ischemia. In vivo, augmentation of ADAM12 expression in Balb/c hind limbs by gene transfer improved perfusion recovery following experimental PAD (change in perfusion = 81%±6.5 vs 40%±7.6 p=0.001). Moreover “knock down” of ADAM12 in C57BL/6 hind limbs impaired perfusion recovery (79%±4.5 vs 95%±3.3 p=0.01). Lastly, in humans, RS1471244 in ADAM12 was strongly associated with CLI (odds ratio 2.4 [95% CI 1.5-4.0), p=0.0006 for dominant model; OR 2.2 [1.3-3.5], p=0.002 for additive model), even after adjustment for diabetes.
Conclusion: ADAM12 is a gene that is associated with PAD outcomes in mice and humans likely through modulation of endothelial cell proliferation and survival.
- © 2013 by American Heart Association, Inc.