背景:血小板活化和与白细胞的相互作用在炎症中是至关重要的。神经节苷脂,含唾液酸的鞘糖脂,与心脏和神经退行性疾病相关的不同炎症状况有关。神经节苷脂在血小板和白细胞功能中的作用,尽管有报道,仍需进一步调查。我们在体外研究了神经节苷脂对血小板活化和血小板-白细胞相互作用的作用。
方法:通过来自明显健康的人类志愿者的富含血小板的血浆中的聚集测定法研究了血小板活化。通过免疫印迹分析信号蛋白磷酸化。通过流式细胞术测量血小板P-选择素表达和血小板-白细胞聚集体形成。
结果:神经节苷脂GM1、GD1a和GT1b本身没有诱导任何血小板聚集。相反,当与血小板预孵育时,它们增强亚最大ADP和胶原蛋白浓度诱导的血小板聚集,并增加P-选择素表达。将血小板与游离唾液酸和GM1的可溶性部分一起孵育对血小板聚集有类似的增强作用,但对血小板P-选择素的表达没有影响。始终如一,分析信号蛋白磷酸化,只有整个神经节苷脂激活ERK1,2,这表明完整的神经节苷脂对于其对血小板的作用至关重要。阿司匹林阻止了对血小板聚集和ERK1,2活化的启动作用。此外,与未经处理的血液相比,柠檬酸化全血与神经节苷脂孵育诱导的血小板-白细胞聚集体形成伴随粒细胞和单核细胞CD11b的表达增加,提示原发性白细胞活化。
结论:神经节苷脂可能在体外作用于血小板和白细胞的活化及其相互作用。观察到的效果可能有助于临床病症中的炎症过程。
BACKGROUND: Platelet activation and interaction with leukocytes are crucial in inflammation. Gangliosides, sialic acid-containing glycosphingolipids, have been linked to different inflammatory conditions related to cardio- and neurodegenerative disorders. The role of gangliosides in platelet and leukocyte function, although reported, still needs further investigation. We studied the role of gangliosides on platelet activation and platelet-leukocyte interaction in vitro.
METHODS: Platelet activation was studied through aggregometry in platelet-rich plasma from apparently healthy human volunteers. Signaling protein phosphorylation was analyzed by immunoblotting. Platelet P-selectin expression and platelet-leukocyte aggregate formation were measured by flow cytometry.
RESULTS: The gangliosides GM1, GD1a and GT1b did not induce by themselves any platelet aggregation. Conversely, when pre-incubated with platelets, they potentiate platelet aggregation induced by submaximal ADP and collagen concentrations and increased P-selectin expression. Incubation of platelets with free sialic acid and the soluble part of GM1 induced a similar potentiating effect on platelet aggregation but not on platelet P-selectin expression. Consistently, analyzing the signaling protein phosphorylation, only the entire gangliosides activated ERK1,2 suggesting that a complete ganglioside is crucial for its action on platelets. Both the priming effect on platelet aggregation and ERK1,2 activation were prevented by aspirin. Moreover, incubation of citrated whole blood with gangliosides induced platelet-leukocyte aggregate formation accompanied by increased expression of granulocyte and monocyte CD11b compared to untreated blood, suggesting a primary leukocyte activation.
CONCLUSIONS: Gangliosides may act in vitro both on platelet and leukocyte activation and on their interaction. The observed effects might contribute to inflammatory processes in clinical conditions.