Abstract 14575: Celastramycin Inhibits Pulmonary Arterial Smooth Muscle Cell Proliferation and Ameliorates Hypoxia-induced Pulmonary Hypertension in Mice
Background: Pulmonary arterial hypertension (PAH) is a fatal disease characterized by enhanced proliferation of pulmonary arterial smooth muscle cells (PASMCs). However, all the drugs in clinical use target pulmonary microvascular dilatation, which is not effective for patients with advanced PAH. Celastramycin, a benzoyl pyrrole-type compound originally found in a bacteria extract, possess anti-inflammatory effects.
Methods and Results: To discover a novel drug for PAH patients from the original library of Tohoku University (5,562 compounds), we performed high-throughput screening with PASMCs from PAH patients (PAH-PASMCs). In the first screening, we treated PAH-PASMCs with each compound (5 μmol/L) in 384-well plates. After 24 hours of treatment, we performed MTT assay and found 80 compounds that effectively inhibited proliferation compared with controls (>20%). In the second screening, we performed a repeatability assay for the 80 compounds (5 μmol/L) in 96-well plates. Additionally, we also performed a counter assay for the 80 compounds with normal PASMCs and excluded compounds that blocked cell proliferation. Furthermore, we performed a concentration-dependent assay. Altogether, we discovered 5 compounds that inhibit PAH-PASMCs proliferation without any toxicity for normal PASMCs. Among the 5 compounds, celastramycin, a compound that represses the natural immune system, significantly inhibited PAH-PASMCs proliferation without any cell cytotoxicity. Mechanistic analysis demonstrated that celastramycin significantly reduced ERK and NFκB signaling in PAH-PASMCs compared with controls (both P<0.05, n=4 each). Furthermore, IL-6 gene expression was significantly suppressed by celastramycin compared with controls (P<0.01, n=3). Next, we evaluated the effects of celastramycin in 10-week-old mice that were exposed to chronic hypoxia (10% O2) for 4 weeks. Celastramycin (10 mg/kg/day,SC) significantly reduced RV systolic pressure (31.9±0.4 vs. 36.6±1.2 mmHg) compared with controls (P<0.01, n=4 each).
Conclusions: By using high-throughput screening and PAH-PASMCs, we selected celastramycin that has novel pharmacological properties for PAH therapy. Celastramycin may be a promising drug for the treatment of PAH.
Author Disclosures: R. Kurosawa: None. K. Satoh: None. N. Kikuchi: None. J. Omura: None. T. Satoh: None. M. Nogi: None. S. Sunamura: None. K. Numano: None. K. Suzuki: None. M. Siddique: None. E. Al-Mamun: None. H. Shimokawa: Speakers Bureau; Modest; Daiichi-Sankyo, Bayer Yakuhin.
- © 2016 by American Heart Association, Inc.