Jana Sirsendu, Meng Fantao, Hirsch Rhoda E, Friedman Joel M, Alayash Abdu I
Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, United States.
Hematology Division, Department of Medicine and Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, United States.
Front Physiol. 2017 Dec 19;8:1082. doi: 10.3389/fphys.2017.01082. eCollection 2017.
Cell free hemoglobin (Hb), becomes oxidized in the circulation during hemolytic episodes in sickle cell disease (SCD) or thalassemia and may potentially cause major complications that are damaging to the vascular system. Hemolytic anemias are commonly associated with pulmonary hypertension (PH) and often result from dysfunction of lung endothelial cells. The aim of this study was to determine the effect of different Hbs on cultured human lung endothelial function. Toward this goal, endothelial permeability, oxidative stress response parameters, glycolytic and mitochondrial bioenergetic functions were monitored in cultured human pulmonary arterial endothelial cells (HPAEC) following incubation with human adult Hb (HbA), and Hb isolated from patients with sickle cell Hb (HbS, βV6E) and HbE (βE26K) that commonly co-exist with β-thalassemia. These mutant Hbs are known for their distinct oxidative profiles. HPAEC treated with the ferrous forms of HbE, HbS for 24 h showed higher loss of endothelial monolayer integrity with concomitant rise in reactive oxygen radical production, lipid hydroperoxide formation and higher expressions of oxidative stress response proteins including heme oxygenase-1 (HO-1) accompanied by a rise in uncoupled mitochondrial respiration. Loss of membrane permeability was diminished in part by haptoglobin (Hp, protein scavenger), hemopexin (Hpx, heme scavenger) or ascorbate (reducing agent). To understand the role of Hb oxidation, HPAEC were exposed to ferric or ferryl states of the mutant Hbs. Ferryl forms of all proteins caused a significant damage to the endothelial monolayer integrity at a higher degree than their respective ferric Hbs. Ferryl forms of HbS and HbE also caused a loss of respiratory chain complex activities in isolated endothelial mitochondria and basal oxygen consumption in HPAEC. However, longer incubation with ferryl Hbs produced bioenergetic reprogramming including higher degree of uncoupled respiration and glycolytic rate. The data in this report collectively indicate that higher oxidation forms of HbS and HbE cause endothelial dysfunction through distinct damaging mechanisms involving mitochondrial bioenergetic function.
在镰状细胞病（SCD）或地中海贫血的溶血发作期间，游离血红蛋白（Hb）在循环中被氧化，并可能引发对血管系统造成损害的主要并发症。溶血性贫血通常与肺动脉高压（PH）相关，且常常源于肺内皮细胞功能障碍。本研究的目的是确定不同血红蛋白对培养的人肺内皮功能的影响。为实现这一目标，在将人成年血红蛋白（HbA）、从镰状细胞血红蛋白（HbS，βV6E）患者中分离出的血红蛋白以及与β地中海贫血共同存在的血红蛋白E（βE26K）与人肺动脉内皮细胞（HPAEC）孵育后，监测其内皮通透性、氧化应激反应参数、糖酵解和线粒体生物能量功能。这些突变血红蛋白以其独特的氧化特征而闻名。用亚铁形式的血红蛋白E、血红蛋白S处理HPAEC 24小时后，内皮单层完整性丧失更高，同时活性氧自由基生成增加、脂质氢过氧化物形成增加，包括血红素加氧酶-1（HO-1）在内的氧化应激反应蛋白表达升高，同时伴随解偶联线粒体呼吸增加。触珠蛋白（Hp，蛋白质清除剂）、血红素结合蛋白（Hpx，血红素清除剂）或抗坏血酸盐（还原剂）部分减轻了膜通透性的丧失。为了解血红蛋白氧化的作用，将HPAEC暴露于突变血红蛋白的三价铁或高铁血红素状态。所有蛋白质的高铁血红素形式对内皮单层完整性造成的损害比其各自的三价铁血红蛋白更严重。血红蛋白S和血红蛋白E的高铁血红素形式还导致分离的内皮线粒体中呼吸链复合物活性丧失以及HPAEC中基础氧消耗减少。然而，与高铁血红素血红蛋白长时间孵育会产生生物能量重编程，包括更高程度的解偶联呼吸和糖酵解速率。本报告中的数据共同表明，血红蛋白S和血红蛋白E的更高氧化形式通过涉及线粒体生物能量功能的不同损伤机制导致内皮功能障碍。
