Jia Guanghong, Habibi Javad, Aroor Annayya R, Hill Michael A, DeMarco Vincent G, Lee Li E, Ma Lixin, Barron Brady J, Whaley-Connell Adam, Sowers James R
Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA.
Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA.
Metabolism. 2018 Jan;78:69-79. doi: 10.1016/j.metabol.2017.08.008. Epub 2017 Sep 8.
Enhanced activation of cell specific mineralocorticoid receptors (MRs) in obesity plays a key role in the development of cardiovascular disease including cardiac diastolic dysfunction as a critical prognosticator. Our previous investigations demonstrated that selective endothelium MR activation promotes a maladaptive inflammatory response and fibrosis in cardiovascular tissue in female mice fed a western diet (WD), and this was associated with expression and activation of the epithelial sodium channel on the surface of endothelial cells (EnNaC). However, the specific role of EnNaC signaling in the development of cardiac stiffness and diastolic dysfunction has not been examined. We hypothesized that targeted inhibition of EnNaC with low dose amiloride would prevent WD-induced diastolic dysfunction by suppressing abnormal endothelial permeability, inflammation and oxidative stress, and myocardial fibrosis.
MATERIALS/METHODS: Four week-old female C57BL6/J mice were fed a WD with or without a low dose of amiloride (1mg/kg/day) for 16weeks. Left ventricular cardiac function was evaluated by magnetic resonance imaging. In addition, we examined coronary vessel and cardiac remodeling, fibrosis, macrophage infiltration using immunohistochemistry, western blot and real time PCR.
Amiloride, an antagonist of EnNaC, attenuated WD-induced impairment of left ventricular initial filling rate and relaxation time. Cardiac diastolic dysfunction was associated with increases in coronary endothelium remodeling and permeability that paralleled WD-induced increases in F-actin and fibronectin, decreased expression of claudin-5 and occludin, and increased macrophage recruitment, M1 polarization, cardiac oxidative stress, fibrosis and maladaptive remodeling.
Our data support the concept that EnNaC activation mediates endothelium permeability which, in turn, promotes macrophage infiltration, M1 polarization, and oxidative stress, resulting in cardiac fibrosis and diastolic dysfunction in females with diet induced obesity.
肥胖状态下细胞特异性盐皮质激素受体（MRs）的激活增强在包括心脏舒张功能障碍在内的心血管疾病发展中起关键作用，而心脏舒张功能障碍是一个关键的预后指标。我们之前的研究表明，在喂食西方饮食（WD）的雌性小鼠中，选择性内皮MR激活会促进心血管组织中适应性不良的炎症反应和纤维化，这与内皮细胞（EnNaC）表面上皮钠通道的表达和激活有关。然而，EnNaC信号在心脏僵硬和舒张功能障碍发展中的具体作用尚未得到研究。我们假设，用低剂量氨氯吡咪靶向抑制EnNaC可通过抑制异常的内皮通透性、炎症和氧化应激以及心肌纤维化来预防WD诱导的舒张功能障碍。
材料/方法：4周龄雌性C57BL6/J小鼠喂食含或不含低剂量氨氯吡咪（1mg/kg/天）的WD 16周。通过磁共振成像评估左心室心脏功能。此外，我们使用免疫组织化学、蛋白质免疫印迹和实时PCR检查冠状动脉血管和心脏重塑、纤维化、巨噬细胞浸润情况。
氨氯吡咪是EnNaC的拮抗剂，可减轻WD诱导的左心室初始充盈率和舒张时间受损。心脏舒张功能障碍与冠状动脉内皮重塑和通透性增加有关，这与WD诱导的F-肌动蛋白和纤连蛋白增加、claudin-5和闭合蛋白表达降低以及巨噬细胞募集增加、M1极化、心脏氧化应激、纤维化和适应性不良重塑平行。
我们的数据支持这样的概念，即EnNaC激活介导内皮通透性，进而促进巨噬细胞浸润、M1极化和氧化应激，导致饮食诱导肥胖女性出现心脏纤维化和舒张功能障碍。
