In vivo Endothelial Cell‐specific Expression of AMPKα Attenuates Cold‐induced Pulmonary Vascular Dysfunction and Hypertension by Mitigating Inflammation

Abstract

Background and AimIn lung biopsies from patients with pulmonary hypertension (PH), mononuclear cells are often observed in pulmonary arterial plexiform lesions, mainly consisting of leukocytes and macrophages. Endothelial AMP‐activated protein kinase α (AMPKα) is downregulated in the pulmonary arteries of patients with PH. AMPK is involved in the cellular response to metabolic stress. AMPKα expression was decreased in pulmonary arteries in a rat model of PH induced by exposure to cold. The aim of this study is to investigate whether in vivo endothelial cell‐specific expression of AMPKα attenuates cold‐induced inflammation and PH.MethodsTo investigate the role of AMPKα1 in PH, we generated Lentivirus carrying AMPKα1 full‐length cDNA driven by an endothelial‐specific promoter, Tie2 (Tie2.AMPKα1). Lentivirus with Tie2.LacZ was used as the control construct. Four groups of Sprague‐Dawley male rats (7/each group) received IV delivery of PBS, PBS, Tie2.LacZ and Tie2.AMPKα1 respectively. Following injection, one PBS group was kept at the room temperature and serve as a control. Other three groups were exposed to cold temperatures (5±1°C). The right ventricular (RV) pressure was measured by end‐point cannulation after 11 weeks of cold‐exposure.ResultsRV systolic pressure was elevated in cold‐PBS and cold‐Tie2.LacZ groups compared with the warm‐PBS controls, suggesting that continuous cold exposure causes pulmonary vascular dysfunction and pulmonary PH, namely cold‐induced PH (CIPH). By contrast, AAV delivery of Tie2.AMPKα1 prevented cold‐induced elevation of RV pressure, suggesting that downregulation of endothelial AMPK α1 plays a critical role in the pathogenesis of cold‐induced pulmonary vascular dysfunction and CIPH. RV developed hypertrophy as evidenced by a significant increase in the RV weight in cold‐exposed rats. Western blot and RT‐PCR data confirmed that Tie2.AMPKα1 effectively rescued the cold‐induced downregulation of AMPK α1 and eNOS expression in the lung. Cold exposure caused strong inflammatory responses as seen with robust infiltration of leukocytes and macrophages in cold‐exposed rats. Cold‐induced activation of macrophages also led to upregulation of TNFα and IL‐1β levels in the lung. Tie2.AMPKα1 effectively attenuated cold‐induced infiltration of leukocytes and macrophages and elevation of TNFα and IL‐1β levels.ConclusionCold exposure causes pulmonary vascular dysfunction and CIPH via downregulation of endothelial AMPKα expression. In vivo endothelial cell‐specific expression of AMPK α1 attenuates CIPH partially by suppressing cold‐induced inflammatory responses.Support or Funding InformationNIH R01 HL116863, HL122166.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.