Pulmonary arterial hypertension (PAH) is a severe disease associated with inflammation and endothelial damage, leading to pulmonary vascular remodelling, right ventricular failure and death. Circulating levels of miR-150 are reduced in PAH and act as an independent predictor of patient survival. miR-150 expression in endothelial cells is regulated by shear-dependent transcription factor Krueppel-like factor 2 (KLF2). However, mechanistic links between changes in miR-150 levels and dysregulation of endothelial function are not fully understood.
To study the role of miR150 in the regulation of on endothelial function in vitro and investigate the effect of therapeutic supplementation of miR-150 in Sugen/hypoxia mice.
Methods and Results
Human Pulmonary Artery Endothelial Cells (HPAECs) were transfected with miR-150 mimics or inhibitors and exposed to hypoxia, growth factor depletion or inflammatory cytokines. miR-150 reduced endothelial apoptosis, proliferation and pro-inflammatory activation and enhanced endothelial repair in vitro, while miR-150 inhibitor had opposite effects. Overexpression of KLF2 and flow shear stress significantly increased intracellular levels of miR-150.
Downstream mediators of miR-150 were identified by miRNA target prediction and gene sequencing analysis, and validated by qPCR and RNAscope in situ hybridization. miR-150 most significant target genes regulated mitochondrial function (PTPMT1), haematopoiesis (MYB), and vascular integrity (NOTCH3).
Endothelium-specific delivery of miR-150 to the lung via Lipoplex Formulation DACC9 (Silence Therapeutics) was studied in a Sugen/hypoxia mice model of PAH (3 weeks). Endothelial miR-150 levels were reduced in the lungs of Sugen/hypoxia mice. Preventive treatment with miR-150 reduced pulmonary artery pressure and pulmonary vessel muscularisation, and downregulated the expression of miR-150 target genes in the lung.
Furthermore, KLF2 and miR-150 expression levels were significantly reduced in blood-derived endothelial progenitor cells (BOECs) from PAH patients (n=7), leading to increased PTPMT1 and MYB expression levels in these cells.
Supplementation of miR-150 may be considered as potential therapeutic strategy in PAH.