The Biogenesis of Platelet-Derived Extracellular Vesicles and their Impact on Megakaryocyte Maturation

血小板源性细胞外囊泡的生物发生及其对巨核细胞成熟的影响

• 批准号: 10613503
• 负责人: Kellie Rae Machlus
• 金额: $ 57.73万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-20 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10613503
• 关键词: Acute; Address; Agonist; Binding; Biogenesis; Biology; Blood Platelets; Bone Marrow; Bone Marrow Cells; Cardiovascular Diseases; Cell Communication; Cell membrane; Cells; Clinical; Collagen; Data; Dependence; Development; Disease; Environment; Family; Gene Expression; Generations; Goals; Hematopoietic; Hemorrhage; Human; In Vitro; Inflammation; Inflammatory; Knowledge; Life; Link; Mediating; Megakaryocytes; Megakaryocytopoieses; Membrane Fusion; Messenger RNA; MicroRNAs; Modeling; Monomeric GTP-Binding Proteins; Morbidity - disease rate; Mothers; Mus; Outcome Study; Pathogenicity; Pathologic; Pathway interactions; Patients; Plasma; Platelet Activation; Platelet Count measurement; Production; Property; Regulation; Research; Signal Transduction; Steroids; Systemic Lupus Erythematosus; Therapeutic Intervention; Thrombin; Thrombocytopenia; Thrombopoiesis; Thrombopoietin; Time; Transcript; Up-Regulation; blood product; experimental study; extracellular vesicles; in vivo; inhibitor; insight; member; microvesicles; mimetics; mortality; new therapeutic target; novel; prevent; response; rho; rho GTP-Binding Proteins; side effect; thrombocytosis; transcription factor; transcriptome; uptake

The Biogenesis of Platelet-Derived Extracellular Vesicles and their Impact on Megakaryocyte Maturation Abstract Thrombocytopenia is a major clinical problem encountered in multiple conditions, and severe thrombocytopenia (platelet counts <50 x 10^9/L) can lead to life threatening bleeding. Current treatment options have severe side effects, are in limited supply, involve blood products, and the platelet response typically takes up to 12 days. Therefore, there is an urgent need to identify new thrombopoietic agents that increase platelet counts for patients. In many inflammatory conditions platelet counts rise, resulting in thrombocytosis, but what initiates this platelet up-regulation is not well understood. Our lab uses inflammation as a model of exacerbated thrombopoiesis that results in differences in platelet quality and quantity in order to 1) gain a better understanding of the basic biology of megakaryocyte (MK) maturation their production of platelets, 2) identify thrombopoietin (TPO) independent pathways of MK maturation, and 3) determine ways to reduce platelet-related morbidity and mortality in inflammation. We have discovered a novel regulator of MK maturation during inflammation: platelet-derived extracellular vesicles (PEVs) in the bone marrow. Our preliminary data indicate that platelets package and shed MVs in an agonist-specific mechanism dependent on Rho GTPase signaling; the mechanism of Rho-mediated regulation of PEV formation and packaging will be explored in Aim 1. We also found that PEVs enter the bone marrow from the plasma, and bind to and are endocytosed by MKs both in vitro and in vivo. In Aim 2, we will examine how platelet-derived MVs interact with MKs. Specifically, we will determine the mechanisms by which they bind to and are internalized by MKs and how their cargo transferred. In inflammatory conditions such as SLE, ongoing platelet activation increases levels of circulating PEVs. These PEVs deliver disease-related changes from the plasma milieu directly to MKs in the bone marrow, reprogramming the MKs to make more pathogenic platelets. In Aim 3, we will identify the PEV factors that alter MK gene expression and platelet content in SLE. Successful completion of the proposed experiments will, for the first time, provide a detailed roadmap of how PEVs alter the hematopoietic environment in the setting of inflammatory disease. The insights gained may identify novel therapeutic targets that (i) alter PEV poduction independent of platelet activation (Aim 1), (ii) hijack the PEV/MK interaction to alter MK maturation (Aim 2), and (iii) inhibit pathologic MK reprogramming during SLE and other inflammatory diseases (Aim 3).

血小板衍生的细胞外囊泡的生物发生及其对 巨核细胞成熟 抽象的 血小板减少症是多种情况下遇到的主要临床问题，并且严重 血小板减少症（血小板计数<50 x 10^9/L）可导致危及生命的出血。目前治疗 选择有严重副作用，供应有限，涉及血液制品和血小板反应 通常最多需要 12 天。因此，迫切需要寻找新的血小板生成剂 增加患者的血小板计数。在许多炎症条件下，血小板计数上升，导致 血小板增多症，但引发血小板上调的原因尚不清楚。我们的实验室使用炎症 作为加剧血小板生成的模型，导致血小板质量和数量的差异，以便 1) 更好地了解巨核细胞 (MK) 成熟及其产生的基本生物学 血小板，2) 识别血小板生成素 (TPO) 独立的 MK 成熟途径，以及 3) 确定方法 降低血小板相关炎症的发病率和死亡率。我们发现了一种新的 MK 调节剂 炎症过程中的成熟：骨髓中血小板衍生的细胞外囊泡（PEV）。我们的 初步数据表明，血小板以激动剂特异性机制包装和释放 MV，具体取决于 Rho GTPase 信号传导； Rho 介导的 PEV 形成和包装调节机制将是 在目标 1 中进行了探索。我们还发现 PEV 从血浆进入骨髓，并结合并被 在体外和体内均被 MK 内吞。在目标 2 中，我们将研究血小板衍生的 MV 如何与 MK。具体来说，我们将确定它们与 MK 结合并被 MK 内化的机制， 他们的货物如何转移。在系统性红斑狼疮等炎症性疾病中，持续的血小板活化会增加 循环 PEV 水平。这些 PEV 将血浆环境中的疾病相关变化直接传递给 MK 在骨髓中，对 MK 进行重新编程以产生更多致病性血小板。在目标 3 中，我们将确定 改变 SLE 中 MK 基因表达和血小板含量的 PEV 因子。顺利完成拟议的 实验将首次提供 PEV 如何改变造血系统的详细路线图 炎症性疾病的环境。获得的见解可能会确定新的治疗靶点 (i) 独立于血小板激活改变 PEV 生成（目标 1），(ii) 劫持 PEV/MK 相互作用以改变 MK 成熟（目标 2），以及 (iii) 抑制 SLE 和其他炎症期间的病理性 MK 重编程 疾病（目标 3）。