Abstract 13742: PDE3 Inhibitor, Cilostazol, Ameliorates Ischemic Hindlimb Through cAMP and PPARγ Activation

Abstract

Peripheral arterial disease (PAD) is highly prevalent in the elderly and subjects with atherosclerotic risk factors. Approximately 2-4% of those affected with PAD commonly complain of intermittent claudication (IC) that is a strong indicator for the development of systemic atherosclerosis. Cilostazol (CSZ) has been shown to be of benefit in improving pain-free walking distance and quality of life in patients with IC. CSZ may be the most clinically effective pharmacologic option for IC. However, the underlying mechanism for amelioration of IC by CSZ remains largely unclear. Here, we demonstrate that CSZ increases expression of hepatocyte growth factor (HGF) in vascular smooth muscle cells (SMCs) via two distinct pathways, PPAR γ and cAMP pathway. Activation of PPAR γ and cAMP activates HGF promoter leading to increase in capillary density and improvement of perfusion in mouse ischemic hind limb model. Enhancement of angiogenesis by CSZ involves Akt/eNOS activation in endothelial cells by HGF secreted from SMCs. However, this process was essentially absent in aspirin treatment group and CSZ with HGF neutralizing antibody treatment group. As CSZ also increases HGF protein production in interstitial area of skeletal muscle where satellite cells reside, we postulated that CSZ stimulates myogenesis. To proof this hypothesis, BrdU was injected every day for 7days in mouse hind limb model, and animals were sacrificed at day 7 and 28. Embryonic form of myocyte heavy chain (eMHC), BrdU positive myocyte, and nuclear centralization was measured. As predicted, CSZ increases the number of newly formed myocyte in ischemic leg compared to control and Aspirin treated mouse. This beneficial effect of CSZ was blunted by the administration of HGF neutralizing antibody. Additionally, Heart specific HGF overexpression mouse in which serum level of HGF is 4-5 times higher than wild type mouse were generated to proof the role of HGF in angiogenesis and myogenesis. Similar to the data obtained from CSZ treated mouse, HGF Tg mouse ameliorates ischemic hind limb via both angiogenesis and myogenesis. Altogether, our date demonstrates that CSZ improves ischemic hind limb via angiogenesis and myogenesis. This results may account for the beneficial effect of CSZ in PAD patients with IC.