Chemerin/CMKLR1 axis influences pulmonary arterial pressure and the NO signaling pathway

Abstract

Pulmonary arterial hypertension (PAH) is a clinical condition associated with sustained elevations in pulmonary arterial pressure, leading to right ventricular failure. The adipokines leptin and adiponectin have shown respectively deleterious and protective effects in animal models of PAH. Chemerin is a novel adipokine implicated in blood pressure regulation and recently associated with atherosclerosis, essential hypertension and obesity-induced hypertension. In this context, we aimed to determine whether the chemerin/CMKLR1 axis could influence pulmonary arterial pressure and the severity of pulmonary hypertension. Age-matched wild-type (WT) and CMKLR1 knockout (KO) mice were used. We localized chemerin and the chemokine-like receptor-1 (CMKLR1) in lung sections, pulmonary artery and thoracic aorta. WT and KO mice were exposed to normoxia (21% O2) or hypoxia (10% O2) for 3 weeks ( N = 6 per group). Right ventricular systolic pressure (RVSP) was measured with a micro-tip catheter. Segments of pulmonary artery and thoracic aorta were incubated, immediately after sacrifice, with recombinant mouse chemerin (10–8 mol/L, 1 hour) or vehicle, then stimulated or not with acetylcholine (ACH) (10–4 mol/L, 5 min) to measure NO production in supernatants by determination of nitrites. RVSP was higher in KO than in WT mice in normoxia (26.6 ± 0.4 vs. 22.2 ± 1 mmHg, P = 0.001) and in hypoxia (37.8 ± 0.5 vs. 31.4 ± 1.2 mmHg, P = 0.001). Hypoxia reduced NO production in WT and KO mice. In WT, ACH-induced NO production was abolished by chemerin pre-incubation. In normoxia and hypoxia, basal NO production was lower in KO than WT mice and ACH-stimulated NO production was totally inhibited in KO mice. These observations provide support for a role of the chemerin/CMKLR1 axis as regulator of pulmonary vascular homeostasis and as a disease-modifier in the context of pulmonary hypertension by the negative modulation of pulmonary vascular NO production.