View Abstract

A2074 - Pentosan Polysulfate Inhibits Hypoxia-Induced Pulmonary Vascular Remodeling in Mice
Author Block: R. Ramchandran1, M. Sun1, J. Chen2, T. Chen1, J. Raj3; 1Pediatrics, UIC, Chicago, IL, United States, 2Dept of Medicine, Univ of Illinois at Chicago, Chicago, IL, United States, 3Univ of Illinois At Chicago, Chicago, IL, United States.
Rationale: There is significant crosstalk between the pulmonary arterial endothelial (PAEC) and smooth muscle cells (PASMC) in the pathogenesis of vascular remodeling in pulmonary hypertension (PH) that is yet to be fully understood. Recently we showed that extracellular microvesicles (MV) from hypoxic PAECs induced PASMC proliferation in vitro and PH in mice. Here we report that ADAMTS4, a disintegrin-like and metalloproteinase with thrombospondin motifs-4, is a component of the endothelial MVs that can induce proliferation of PASMC. We tested the effect of pentosan polysulfate (PPS), an inhibitor of ADAMTS4, on pulmonary vascular remodeling in hypoxia-induced PH in mice. Methods: Mouse PAECs were exposed to hypoxia (1% for 24 hours) or normoxia and MVs were isolated from the conditioned medium by sedimentation. Hypoxic and normoxic microvesicles (HMV, NMV) were characterized by nanoparticle tracking analysis and western analysis of MV lysates. Quantitative proteomic analysis of HMVs and NMVs was performed with TMT label and LC-MS/MS. Effect of HMV and NMV on PASMC proliferation was assessed using a BrdU-based assay and a scratch assay. 8 week-old C57BL/6 mice were administered pentosan polysufate (25mg/kg/day in drinking water) and exposed to hypoxia (10%) or room air for 3 weeks. Right ventricular systolic pressures (RSVP), right ventricular hypertrophy (RVH; Fulton’s index) and pulmonary vessel wall thickness were determined to assess PH phenotype. Results: Proteomic analysis of PAEC extracellular MVs identified cell specific protein markers and showed increased ADAMTS4 protein levels in hypoxic MVs compared with normoxic MVs. Increased ADAMTS4 protein immunoreactivity in HMV was confirmed by western blot analysis. Recombinant ADAMTS4 protein induced PASMC proliferation and migration in-vitro and induced the AKT signaling pathway in normoxia. Treatment with PPS led to a modest reduction in RVSP but a significant reduction in pulmonary vascular remodeling in mice exposed to chronic hypoxia. Conclusion: Our results suggest that increased ADAMTS4 in PAEC microvesicles during hypoxia is one of many factors that induce PASMC proliferation and vascular remodeling leading to PH. Our data show that pentosan polysulfate, an inhibitor of ADAMTS4, mitigates chronic hypoxia-induced pulmonary vessel remodeling and that ADAMTS4 may be one possible therapeutic target in the treatment of PH. Support: NIH HL 123804 to JUR