Department of Zoology, School of Basic Sciences, Central University of Punjab, Ghudda, Bathinda, India.
Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Cell Biol Int. 2024 Sep;48(9):1266-1284. doi: 10.1002/cbin.12192. Epub 2024 Jun 4.
Platelets are essential component of circulation that plays a major role in hemostasis and thrombosis. During activation and its demise, platelets release platelet-derived microvesicles, with lysophosphatidylcholine (LPC) being a prominent component in their lipid composition. LPC, an oxidized low-density lipoprotein, is involved in cellular metabolism, but its higher level is implicated in pathologies like atherosclerosis, diabetes, and inflammatory disorders. Despite this, its impact on platelet function remains relatively unexplored. To address this, we studied LPC's effects on washed human platelets. A multimode plate reader was employed to measure reactive oxygen species and intracellular calcium using HDCF-DA and Fluo-4-AM, respectively. Flow cytometry was utilized to measure phosphatidylserine expression, mitochondrial membrane potential (ΔΨm), and mitochondrial permeability transition pore (mPTP) formation using FITC-Annexin V, JC-1, and CoCl/calcein-AM, respectively. Additionally, platelet morphology and its ultrastructure were observed via phase contrast and electron microscopy. Sonoclot and light transmission aggregometry were employed to examine fibrin formation and platelet aggregation, respectively. The findings demonstrate that LPC induced oxidative stress and increased intracellular calcium in platelets, resulting in increased phosphatidylserine expression and reduced ΔΨm. LPC triggered caspase-independent platelet death and mPTP opening via cytosolic and mitochondrial calcium, along with microvesiculation and reduced platelet counts. LPC increased the platelet's size, adopting a balloon-shaped morphology, causing membrane fragmentation and releasing its cellular contents, while inducing a pro-coagulant phenotype with increased fibrin formation and reduced integrin αIIbβ3 activation. Conclusively, this study reveals LPC-induced oxidative stress and calcium-mediated platelet death, necrotic in nature with pro-coagulant properties, potentially impacting inflammation and repair mechanisms during vascular injury.
血小板是循环系统的重要组成部分，在止血和血栓形成中起着主要作用。在激活和凋亡过程中，血小板释放血小板衍生的微泡，其中溶血磷脂酰胆碱（LPC）是其脂质组成的主要成分。LPC 是一种氧化的低密度脂蛋白，参与细胞代谢，但在动脉粥样硬化、糖尿病和炎症性疾病等病理过程中，其水平升高与疾病相关。尽管如此，其对血小板功能的影响仍相对未知。为了解决这个问题，我们研究了 LPC 对洗涤后的人血小板的影响。使用多模式平板读数器，分别使用 HDCF-DA 和 Fluo-4-AM 测量活性氧和细胞内钙。使用流式细胞术，分别使用 FITC-Annexin V、JC-1 和 CoCl/calcein-AM 测量血小板表面磷脂酰丝氨酸表达、线粒体膜电位（ΔΨm）和线粒体通透性转换孔（mPTP）形成。此外，通过相差和电子显微镜观察血小板形态及其超微结构。使用 Sonoclot 和光传输聚集仪分别检测纤维蛋白形成和血小板聚集。研究结果表明，LPC 诱导血小板氧化应激和细胞内钙增加，导致磷脂酰丝氨酸表达增加和 ΔΨm 降低。LPC 通过细胞质和线粒体钙触发细胞凋亡非依赖性的血小板死亡和 mPTP 开放，同时导致微泡形成和血小板计数减少。LPC 增加了血小板的大小，呈气球状形态，导致膜碎片和细胞内容物释放，同时诱导促凝表型，增加纤维蛋白形成和整合素 αIIbβ3 激活减少。总之，本研究揭示了 LPC 诱导的氧化应激和钙介导的血小板死亡，其本质上是坏死性的，具有促凝特性，可能影响血管损伤过程中的炎症和修复机制。
