Mechanisms of platelet exosome-mediated acute chest syndrome in sickle cell disease

项目摘要 急性胸部综合征（ACS）是一种急性肺损伤，是镰状细胞病死亡的主要原因之一 疾病（SCD）。目前对ACS的治疗主要是支持性的，并且迫切需要抢救 可以阻止ACS进展的疗法。ACS通常是急性全身性血管闭塞危象的后遗症 并伴有血小板减少症然而，血小板在ACS发病机制中的作用仍然很大程度上是 未知我们假设ACS与NLRP 3-炎性体介导的携带IL-1β的血小板释放有关 SCD中的外泌体，其促进血小板-中性粒细胞聚集，导致肺中血流停滞。我们也 提出靶向抑制血小板中的TLR 4/NLRP 3-caspase-1信号传导是ACS的潜在治疗方法。 为了验证这一假设，我们将使用一个综合的生理方法，利用我们最近验证的模型 脂多糖（LPS）诱导的转基因SCD小鼠血管闭塞危象，体内多光子激发 (MPE)活SCD小鼠中肺脉管系统的成像、SCD人血液流入肺中的活细胞成像、 体外微流控通道，血小板中缺乏半胱天冬酶-1的SCD小鼠， 外来体在目的1中，我们将确定SCD中携带IL-1β的血小板外泌体的释放是否促进血小板外泌体的释放。 血小板-中性粒细胞在肺小动脉中聚集，导致肺中血流损失。在目标2中， 将确定血小板中TLR 4/NLRP 3-炎性体介导的半胱天冬酶-1的活化是否是负责 用于从SCD中的血小板释放携带IL-1β的外泌体。我们已经开发出了针对血小板的 纳米药物（PTN），特异性招募到体内血小板聚集和血栓形成的部位， 药物输送在目标3中，我们将确定是否有携带TLR 4或半胱天冬酶-1抑制剂或IL-1受体的PTNs， 拮抗剂（IL-1 RA）可以选择性地募集到血小板聚集位点以阻断血小板外泌体释放， 信号传导，并停止SCD小鼠肺血管系统中的血小板-嗜中性粒细胞聚集。这项研究将确定一个 一种新的血小板源性外泌体介导的ACS机制。调查结果还将确定， 递送包封在PTNs中的TLR 4或半胱天冬酶-1抑制剂或IL-1 RA可以是一种潜在的补救疗法， 急性冠脉综合征在伴有血管闭塞危象和血小板减少症的高危SCD患者中的应用

PROJECT SUMMARY Acute chest syndrome (ACS), a type of acute lung injury, is one of the leading causes of mortality in Sickle Cell Disease (SCD). Current treatments for ACS are primarily supportive, and there is a critical need for rescue therapies that can halt the progression of ACS. ACS is often a sequela of acute systemic vaso-occlusive crisis and preceded by thrombocytopenia. However, the role of platelets in the pathogenesis of ACS remains largely unknown. We hypothesize that ACS involves NLRP3-inflammasome mediated release of IL-1β-carrying platelet exosomes in SCD, which promote platelet-neutrophil aggregation leading to arrest of blood flow in lung. We also propose that targeted inhibition of TLR4/NLRP3-caspase-1 signaling in platelets is a potential therapy for ACS. To test this hypothesis, we will use an integrative physiologic approach that utilizes our recently validated model of lipopolysaccharide (LPS) induced vaso-occlusive crisis in transgenic SCD mice, in vivo multi-photon excitation (MPE) imaging of the lung vasculature in live SCD mice, live cell imaging of SCD human blood flowing in microfluidic channels in vitro, SCD mice lacking caspase-1 in platelets and nanoparticle tracking analyses of exosomes. In Aim 1, we will determine whether release of IL-1β-carrying platelet exosomes in SCD promote platelet-neutrophil aggregates in pulmonary arterioles that result in loss of blood flow in the lung. In Aim 2, we will determine whether TLR4/NLRP3-inflammasome mediated activation of caspase-1 in platelets is responsible for release of IL-1β-carrying exosomes from platelets in SCD. We have developed platelet-targeted nanomedicine (PTN) that specifically recruits to sites of platelet aggregation and thrombosis in vivo for targeted drug delivery. In Aim 3, we will determine whether PTNs carrying TLR4 or caspase-1 inhibitors, or IL-1 receptor antagonist (IL-1RA) can selectively recruit to sites of platelet aggregation to block platelet exosome release and signaling, and stop platelet-neutrophil aggregation in the lung vasculature of SCD mice. This study will identify a novel, platelet-derived exosome-mediated mechanism contributing to ACS. The findings will also establish that delivery of TLR4 or caspase-1 inhibitor, or IL-1RA encapsulated in PTNs can be a potential rescue therapy for ACS in high risk SCD patients presenting with vaso-occlusive crisis and thrombocytopenia.