Role of myeloid KLF2 in antiphospholipid antibody-mediated thrombosis

项目总结： 抗磷脂抗体综合征(APS)的特点是反复出现动脉和静脉血栓 在抗磷脂抗体检测持续阳性的小血管和大血管中。这种情况 常影响年轻患者(尤其是育龄妇女)，并与显著 发病率和死亡率。传统上，对血栓形成的研究主要集中在血小板(动脉血栓)，红色 血细胞(静脉血栓)和凝血因子。然而，过去收集的越来越多的数据 十年支持炎症和血栓形成之间的密切联系，因此炎症产生 血栓形成和血栓形成会放大炎症反应。具体地说，中性粒细胞激活和 中性粒细胞胞外陷阱(Net)的产生已被证明是导致血栓形成的原因之一 抗磷脂抗体。此外，Net为炎症体的激活和释放而启动巨噬细胞 细胞因子和组织因子涉及髓系成员之间的串扰，以产生 促炎和血栓前环境。目前，血栓形成的风险是通过终身抗凝剂来管理的。 仅有适度有效且与出血风险高相关的治疗方法，这表明替代或 新的方法是必要的。这些观察结果助长了一种观点，即治疗靶向 髓系可能对动脉和静脉血栓形成有潜在的影响。然而， 髓系细胞激活在协调血栓炎症反应中的分子机制 人们对此知之甚少。 我们的观察结果(已发表的和新出现的)证实转录因子KLF2是一种强效补药 髓系细胞活化和炎症的抑制因子以及动脉和血液循环的重要决定因素 静脉血栓形成。从机制上讲，KLF2被发现调节两个保守的古代程序的生成 中性粒细胞胞外陷阱(Net)和炎症小体的激活。具体到这项提议，我们发现 (I)APLA输注增加了小鼠的动脉和静脉血栓形成；(Ii)APLA治疗导致 巨噬细胞KLF2表达和炎性小体激活减少，净生成增加 (3)髓系特异性过表达KLF2在APLA存在的情况下提供血栓保护。 最后，靶向KLF2的治疗潜力通过我们的发现揭示了抗癌药物 低剂量的波特佐米(BZ)无毒，可诱导髓系KLF2，并具有强大的抗血栓作用 (在不改变止血的情况下)在依赖KLF2的动脉和静脉床上。这些观察结果 为中心假说提供了基础，即髓系KLF2是 APS中的血管血栓形成，可以作为治疗的靶点。为了探索这一假设， 本研究的主要目的如下：(1)研究改变髓系细胞KLF2对APLA诱导的细胞凋亡的影响 大血管和微血管的血栓形成，(2)阐明相关的分子机制 在KLF2中，S在APLA的背景下调节网络形成和炎性小体激活的能力，以及 (3)了解BZ抗血栓作用的分子基础 APLA治疗。这些研究将揭示基因改变的分子基础和功能后果 髓系KLF2对APLA环境下血栓形成的影响。此外，它们还将阐明髓系细胞的重要性。 KLF2中抗血栓/抗炎作用的BZ在此背景下。总体而言，结果不仅是 提供深入的生物学见解，但可能会刺激临床研究，评估BZ在APS中的疗效 有可能改变这一毁灭性疾病的护理标准。

Project Summary: The Antiphospholipid Antibody Syndrome (APS) is characterized by recurrent arterial and venous thrombosis in small and large vessels accompanied by persistently positive antiphospholipid antibody tests. This condition often affects young patients (particularly women of child-bearing age) and is associated with significant morbidity and mortality. Classically, studies of thrombosis have focused largely on platelets (arterial clots), red blood cells (venous clots) and the coagulation factors. However a growing body of data gathering over the past decade supports an intimate link between inflammation and thrombosis such that inflammation begets thrombosis and thrombosis amplifies the inflammatory response. Specifically, neutrophil activation and generation of neutrophil extracellular traps (NETs) have been shown to contribute to thrombosis in the setting of antiphospholipid antibodies. Further, NETs prime macrophages for inflammasome activation and release of cytokines and tissue factor implicating cross talk between members of the myeloid system to generate a proinflammatory and prothrombotic milieu. Presently, thrombosis risk is managed with lifelong anticoagulant therapy that is only modestly effective and associated with a high risk of bleeding, suggesting that alternate or novel approaches are necessary. These observations fuel the momentum for the view that therapies targeting the myeloid lineage may have potential impact on both arterial and venous thrombosis. However, the molecular mechanisms underlying myeloid cell activation in orchestrating this thrombo-inflammatory response is poorly understood. Our observations (both published and nascent) establish transcription factor KLF2 as a potent tonic repressor of myeloid cell activation and inflammation as well as an essential determinant of both arterial and venous thrombosis. Mechanistically, KLF2 is found to regulate two conserved ancient programs — generation of neutrophil extracellular traps (NETs) and activation of the inflammasome. Specific to this proposal, we find that (i) APLA infusion increases both arterial and venous thrombosis in mice; (ii) APLA treatment leads to decreased KLF2 expression and inflammasome activation of macrophages and increased NET generation in neutrophils; (iii) myeloid-specific overexpression of KLF2 offers thromboprotection in the presence of APLA. Finally, the therapeutic potential of targeting KLF2 is revealed by our discovery that the anti-cancer agent bortezomib (BZ), at low non-toxic doses, induces myeloid KLF2 and confers potent anti-thrombotic effects (without altering hemostasis) in both arterial and venous beds that are KLF2-dependent. These observations provide the foundation for the central hypothesis that myeloid KLF2 is a central determinant of vascular thrombosis in APS that can be targeted for therapeutic gain. To explore this hypothesis, the following aims are proposed: (1) To investigate the effect of altering myeloid KLF2 on APLA-induced thrombosis in the macro- and microvasculature, (2) To elucidate the molecular mechanisms involved in KLF2’s ability to regulate NET formation and inflammasome activation in the context of APLA, and (3) To understand the molecular basis for the antithrombotic effect noted with BZ in the context of APLA treatment. These studies will reveal the molecular basis and functional consequences of altering myeloid KLF2 on thrombosis in the setting of APLA. Further, they will illuminate the importance of myeloid KLF2 in the antithrombotic/anti-inflammatory effects of BZ in this setting. Collectively, the results will not only provide deep biologic insights but may stimulate clinical studies evaluating the efficacy of BZ in APS with the potential to change standard of care for this devastating illness.