Abstract 10742: Implication of the Importins KPNA2 and KPNB1 in Pulmonary Arterial Hypertension

Abstract

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by the elevation of mean pulmonary arterial pressure and resistance, culminating in right ventricular failure and premature death. Pulmonary artery smooth muscle cells (PASMCs) isolated from PAH patients exhibit cancer-like phenotypes such as exaggerated proliferation and resistance to apoptosis, key elements contributing to pulmonary arteries (PA) remodeling. Taking benefits of our previously published proteomic study realized on PASMCs isolated from PAH and control patients, we identified the upregulation of importins proteins, namely KPNA2 and KPNB1. The importins contribute to the nucleocytoplasmic shuttling of macromolecules and transcription factors. Cancer studies highlighted the contribution of the KPNA2 and KPNB1 complex in the pro-proliferative and anti-apoptotic phenotypes of cancer cells. Given the cancer-like phenotype of PAH cells, we hypothesized that increased KPNA2-KPNB1 expression promotes PASMCs survival and adverse PA remodeling.We confirmed that KPNA2 and KPNB1 expression is increased in PASMCs and distal PAs isolated from PAH patients compared to controls (western-blot, n=8-9, p<0.05). Similarly, we reported an increased expression of KPNA2-KPNB1 in 3 preclinical models of PH: hypoxic mice, monocrotaline rats and Sugen-hypoxia (Su-Hx) rats (n=8-12, p<0.05). In vitro , molecular (siRNA) and pharmacological (Ivermectin) inhibition of KPNA2-KPNB1 complex decreases PAH-PASMCs proliferation (WB: PCNA; IF: Ki67 and EdU incorporation labeling) and resistance to apoptosis (WB: Survivin; IF: Annexin V labeling) (n=5, p<0.5). Those results are associated with decreased expression of NFAT, NF-kB and STAT3. In vivo , Ivermectin improved PA remodeling (EVG staining) and hemodynamic parameters as assessed by echocardiography (PAAT, TAPSE) and right heart catheterization (RVSP, SV, CO) in Su-Hx rats (n=20, p<0.05). We demonstrated 1) an increased expression of the importins KPNA2 and KPNB1 in PAH, 2) targeting KPNA2-KPNB1 reverses adverse PA remodeling and PH development. Thus, the repurposing of Ivermectin could represent a novel therapeutic strategy from the laboratory bench to patients’ bedside to reverse PAH development.