Abstract 13024: Cardiopulmonary Best Abstract Award: A Disintegrin and Metalloproteinase With Thrombospondin Motifs 8 Downregulates AMP-activated Protein Kinase and Promotes Matrix Metalloproteinases Activation and Pulmonary Hypertension
Background: Pulmonary arterial hypertension (PAH) is characterized by structural remodeling of pulmonary arteries (PA) and excessive proliferation of PA smooth muscle cells (PASMCs). ADAMTS8, a member of the disintegrin and metalloproteinase, is a secreted extracellular enzyme that is specifically expressed in lung tissue.
Methods and Results: To explore a novel therapeutic target of PAH, we performed microarray analysis of PASMCs from patients with PAH (PAH-PASMCs) and found a significant up-regulation of ADAMTS8 in PAH-PASMCs compared with controls (>5-fold, P<0.01). Protein levels of ADAMTS8 were significantly increased in PAH-PASMCs compared with controls (>1.3-fold, P<0.05, n=5 each). Indeed, immunoreactivity of ADAMTS8 was enhanced in the thickened medial layer of PA in PAH patients (n=2-3). Additionally, hypoxia increased protein level of ADAMTS8 in mouse lung homogenates compared with controls (P<0.05, n=6-10 each). Human recombinant ADAMTS8 (hrADAMTS8, 25 ng/mL) suppressed AMP-activated protein kinase (AMPK) signaling, activated matrix metalloproteinases (MMPs), and promoted PASMC proliferation (all P<0.05). In contrast, ADAMTS8 siRNA reduced PASMC proliferation (P<0.05). PASMC-specific ADAMTS8-/- mice exposed to hypoxia (10% O2, 4 weeks) showed significantly reduced RV systolic pressure (33.5±0.3 vs. 38.9±0.4 mmHg), RV hypertrophy (0.26±0.06 vs. 0.33±0.09), and PA remodeling compared with controls (all P<0.05, n=9 each). In situ zymography with DQ gelatin showed reduced MMP activities in PA in ADAMTS8-/-compared with controls (P<0.05). Primary cultured PASMCs from ADAMTS8-/- mice showed AMPK activation, reduced migration and proliferation compared with controls (P<0.05, n=6 each). Importantly, hrADAMTS8 treatment suppressed VEGFA-induced AMPK activation and VEGF receptor-2 phosphorylation in PA endothelial cells (P<0.05, n=6 each). Consistently, PAEC-specific AMPK-/- mice exposed to hypoxia showed significantly increased RV systolic pressure (39.3±1.0 vs. 33.1±0.9 mmHg), RV hypertrophy, and PA remodeling compared with controls (all P<0.05).
Conclusions: ADAMTS8 downregulates AMPK in PA endothelial cells and induces MMP activation and PASMCs proliferation, thus promoting the development of PH.
Author Disclosures: J. Omura: None. K. Satoh: None. N. Kikuchi: None. T. Satoh: None. R. Kurosawa: None. M. Nogi: None. S. Sunamura: None. T. Ohtsuki: None. K. Kozu: None. K. Numano: None. K. Sugimura: None. S. Tatebe: None. T. Aoki: None. K. Suzuki: None. N. Yaoita: None. H. Shimokawa: Speakers Bureau; Modest; Daiichi-Sankyo, Bayer Yakuhin.
- © 2016 by American Heart Association, Inc.