Starossom Sarah C, Veremeyko Tatyana, Dukhinova Marina, Yung Amanda W Y, Ponomarev Eugene D
Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America; Institute for Medical Immunology and NeuroCure, Charité - Universitätsmedizin Berlin, Berlin, Germany.
School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong.
PLoS One. 2014 May 2;9(5):e96256. doi: 10.1371/journal.pone.0096256. eCollection 2014.
Glatiramer acetate (GA, Copaxone, Copolymer-1) is an FDA approved drug for the treatment of MS and it is very effective in suppressing neuroinflammation in experimental autoimmune encephalitis (EAE), an animal model of MS. Although this drug was designed to inhibit pathogenic T cells, the exact mechanism of EAE/MS suppression by GA is still not well understood. Previously we presented evidence that platelets become activated and promote neuroinflammation in EAE, suggesting a possible pathogenic role of platelets in MS and EAE. We hypothesized that GA could inhibit neuroinflammation by affecting not only immune cells but also platelets.
METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effect of GA on the activation of human platelets in vitro: calcium influx, platelet aggregation and expression of activation markers. Our results in human platelets were confirmed by in-vitro and in-vivo studies of modulation of functions of platelets in mouse model. We found that GA inhibited thrombin-induced calcium influx in human and mouse platelets. GA also decreased thrombin-induced CD31, CD62P, CD63, and active form of αIIbβ3 integrin surface expression and formation of platelet aggregates for both mouse and human platelets, and prolonged the bleeding time in mice by 2.7-fold. In addition, we found that GA decreased the extent of macrophage activation induced by co-culture of macrophages with platelets.
GA inhibited the activation of platelets, which suggests a new mechanism of GA action in suppression of EAE/MS by targeting platelets and possibly preventing their interaction with immune cells such as macrophages. Furthermore, the reduction in platelet activation by GA may have additional cardiovascular benefits to prevent thrombosis.
醋酸格拉替雷（GA，考帕松，共聚物-1）是一种经美国食品药品监督管理局（FDA）批准用于治疗多发性硬化症（MS）的药物，在实验性自身免疫性脑脊髓炎（EAE，一种MS的动物模型）中，它在抑制神经炎症方面非常有效。尽管该药物旨在抑制致病性T细胞，但GA抑制EAE/MS的确切机制仍未完全清楚。此前我们提供的证据表明，血小板在EAE中被激活并促进神经炎症，提示血小板在MS和EAE中可能具有致病作用。我们推测GA可能不仅通过影响免疫细胞，还通过影响血小板来抑制神经炎症。
方法/主要发现：我们研究了GA对人血小板体外激活的影响：钙内流、血小板聚集及激活标志物的表达。我们在人血小板上得到的结果通过对小鼠模型中血小板功能调节的体外和体内研究得到了证实。我们发现GA抑制凝血酶诱导的人和小鼠血小板中的钙内流。GA还降低了凝血酶诱导的小鼠和人血小板中CD31、CD62P、CD63以及αIIbβ3整合素活性形式的表面表达和血小板聚集体的形成，并使小鼠的出血时间延长了2.7倍。此外，我们发现GA降低了巨噬细胞与血小板共培养诱导的巨噬细胞激活程度。
GA抑制血小板的激活，这提示了GA在抑制EAE/MS中的一种新作用机制，即靶向血小板并可能阻止它们与巨噬细胞等免疫细胞相互作用。此外，GA降低血小板激活可能对预防血栓形成有额外的心血管益处。
