Ottawa Hospital Research Institute, Neuroscience, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada.
University of Ottawa, Neuroscience Graduate Program, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada.
Biochem Biophys Res Commun. 2014 Jul 18;450(1):912-7. doi: 10.1016/j.bbrc.2014.06.096. Epub 2014 Jun 26.
Circulating microparticles (MPs) are involved in many physiological processes and numbers are increased in a variety of cardiovascular disorders. The present aims were to characterize levels of MPs in a rodent model of chronic cerebral hypoperfusion (CCH) and to determine their signaling properties. MPs were isolated from the plasma of rats exposed to CCH and quantified by flow cytometry. When MPs were added to cultured endothelial cells or normal rat kidney cells they induced cell death in a time and dose dependent manner. Analysis of pellets by electron microscopy indicates that cell death signals are carried by particles in the range of 400 nm in diameter or less. Cell death involved the activation of caspase 3 and was not a consequence of oxidative stress. Inhibition of the Fas/FasL signaling pathway also did not improve cell survival. MPs were found to contain caspase 3 and treating the MPs with a caspase 3 inhibitor significantly reduced cell death. A TNF-α receptor blocker and a TRAIL neutralizing antibody also significantly reduced cell death. Levels of circulating MPs are elevated in a rodent model of chronic cerebral ischemia. MPs with a diameter of 400 nm or less activate the TNF-α and TRAIL signaling pathways and may deliver caspase 3 to cultured cells.
循环微颗粒 (MPs) 参与许多生理过程，并且在各种心血管疾病中数量增加。本研究旨在表征慢性大脑低灌注 (CCH) 啮齿动物模型中 MPs 的水平，并确定其信号特性。通过流式细胞术从暴露于 CCH 的大鼠血浆中分离 MPs 并进行定量。当将 MPs 添加到培养的内皮细胞或正常大鼠肾细胞中时，它们以时间和剂量依赖的方式诱导细胞死亡。电子显微镜分析表明，细胞死亡信号由直径在 400nm 或以下的颗粒携带。细胞死亡涉及 caspase 3 的激活，而不是氧化应激的结果。抑制 Fas/FasL 信号通路也不能改善细胞存活。发现 MPs 中含有 caspase 3，用 caspase 3 抑制剂处理 MPs 可显著减少细胞死亡。TNF-α 受体阻滞剂和 TRAIL 中和抗体也显著减少了细胞死亡。在慢性脑缺血的啮齿动物模型中，循环 MPs 的水平升高。直径为 400nm 或以下的 MPs 激活 TNF-α 和 TRAIL 信号通路，并可能将 caspase 3 递送到培养细胞中。
