Endothelial cell premature senescence exacerbates pulmonary arterial hypertension through contact-mediated interaction with vascular smooth muscle cells

Abstract

Abstract Introduction Pulmonary arterial hypertension (PAH) is characterized by remodelling and stenosis of the pulmonary arteries, ultimately leading to the right heart failure and death. Endothelial cell (EC) dysfunction is thought to play a central role in the pathogenesis of PAH by mediating the structural changes in pulmonary vasculatures. Various stresses promote premature senescence in EC, which may modify vascular disorders; however, the role of EC senescence in the development of PAH remains poorly understood. Purpose We aimed at investigating the potential role of EC premature senescence in the development of PAH. Methods We recently generated EC-specific progeroid mice in which ECs specifically undergo premature senescence by overexpressing the dominant-negative form of telomere repeat-binding factor 2 (published in Nat Commun 2020). These EC-specific progeroid mice were exposed to hypoxia (10% O2 for three weeks) to induce pulmonary hypertension. Also, we prepared premature senescent ECs using human pulmonary artery ECs (hPAECs) and explored their interaction with human pulmonary artery smooth muscle cells (hPASMCs) in two different conditions; direct and indirect interactions. For indirect coculture, hPASMCs were seeded onto the culture insert, while hPAECs were plated on the culture plate, and they were cocultured in the same well and medium so that secreted factors derived from senescent ECs could access to SMCs through the insert pores. For direct coculture, hPAECs were seeded onto the bottom side of the insert, while hPASMCs were cultured on the top side of the same insert, so that cell-to-cell contact could be made through the pores. Results After chronic hypoxia exposure, the EC-specific progeroid mice showed higher right ventricular systolic pressure and increased right ventricular mass as compared to wild-type (WT) mice, indicating exacerbated pulmonary hypertension. Histological analysis of the lung revealed a significantly enhanced muscularization in the small pulmonary arteries in EC-specific progeroid mice compared to WT mice. Mechanistically, we identified that direct coculture with premature senescent hPAECs enhanced proliferation and migration in hPASMCs, while no such effects were detected in indirect coculture condition. Conclusion To our knowledge, this is the first report that reveals a crucial role of EC premature senescence in the development of PAH. Our in vitro studies suggest that contact-mediated interaction between premature senescent ECs and SMCs is critically involved in its underlying mechanism. Therefore, EC premature senescence is a novel attractive pharmacotherapeutic target for the treatment of PAH. Funding Acknowledgement Type of funding source: None