Wajih Nadeem, Basu Swati, Jailwala Anuj, Kim Hee Won, Ostrowski David, Perlegas Andreas, Bolden Crystal A, Buechler Nancy L, Gladwin Mark T, Caudell David L, Rahbar Elaheh, Alexander-Miller Martha A, Vachharajani Vidula, Kim-Shapiro Daniel B
Department of Physics, Wake Forest University, Winston-Salem, NC 27109, United States; Translational Science Center, Wake Forest University, Winston-Salem, NC 27109, United States.
Department of Physics, Wake Forest University, Winston-Salem, NC 27109, United States.
Redox Biol. 2017 Aug;12:1026-1039. doi: 10.1016/j.redox.2017.05.006. Epub 2017 May 10.
Sickle cell disease is caused by a mutant form of hemoglobin that polymerizes under hypoxic conditions, increasing rigidity, fragility, calcium influx-mediated dehydration, and adhesivity of red blood cells. Increased red cell fragility results in hemolysis, which reduces nitric oxide (NO) bioavailability, and induces platelet activation and inflammation leading to adhesion of circulating blood cells. Nitric Oxide inhibits adhesion and platelet activation. Nitrite has emerged as an attractive therapeutic agent that targets delivery of NO activity to areas of hypoxia through bioactivation by deoxygenated red blood cell hemoglobin. In this study, we demonstrate anti-platelet activity of nitrite at doses achievable through dietary interventions with comparison to similar doses with other NO donating agents. Unlike other NO donating agents, nitrite activity is shown to be potentiated in the presence of red blood cells in hypoxic conditions. We also show that nitrite reduces calcium associated loss of phospholipid asymmetry that is associated with increased red cell adhesion, and that red cell deformability is also improved. We show that nitrite inhibits red cell adhesion in a microfluidic flow-channel assay after endothelial cell activation. In further investigations, we show that leukocyte and platelet adhesion is blunted in nitrite-fed wild type mice compared to control after either lipopolysaccharide- or hemolysis-induced inflammation. Moreover, we demonstrate that nitrite treatment results in a reduction in adhesion of circulating blood cells and reduced red blood cell hemolysis in humanized transgenic sickle cell mice subjected to local hypoxia. These data suggest that nitrite is an effective anti-platelet and anti-adhesion agent that is activated by red blood cells, with enhanced potency under physiological hypoxia and in venous blood that may be useful therapeutically.
镰状细胞病由一种突变形式的血红蛋白引起，该血红蛋白在缺氧条件下会聚合，增加红细胞的硬度、脆性、钙内流介导的脱水以及黏附性。红细胞脆性增加会导致溶血，从而降低一氧化氮（NO）的生物利用度，并诱导血小板活化和炎症，导致循环血细胞黏附。一氧化氮可抑制黏附和血小板活化。亚硝酸盐已成为一种有吸引力的治疗剂，它通过脱氧红细胞血红蛋白的生物活化将NO活性靶向递送至缺氧区域。在本研究中，我们证明了通过饮食干预可达到的剂量下亚硝酸盐的抗血小板活性，并与其他供NO剂的类似剂量进行了比较。与其他供NO剂不同，亚硝酸盐的活性在缺氧条件下红细胞存在时会增强。我们还表明，亚硝酸盐可减少与红细胞黏附增加相关的钙依赖性磷脂不对称性丧失，并且红细胞的变形能力也得到改善。我们表明，在内皮细胞活化后的微流控流动通道试验中，亚硝酸盐可抑制红细胞黏附。在进一步的研究中，我们表明，与对照组相比，在脂多糖或溶血诱导的炎症后，喂食亚硝酸盐的野生型小鼠中白细胞和血小板的黏附受到抑制。此外，我们证明，亚硝酸盐治疗可减少人源化转基因镰状细胞小鼠局部缺氧时循环血细胞的黏附并减少红细胞溶血。这些数据表明，亚硝酸盐是一种有效的抗血小板和抗黏附剂，可被红细胞激活，在生理缺氧和静脉血中效力增强，可能具有治疗作用。
