Regulation of Endothelial-Neutrophil Interaction and Lung Vascular Permeability in Sepsis

本提案的总体目标是了解肺微血管系统如何获得“促炎性和 为了鉴定控制脓毒症诱导急性 肺损伤（ALI）。具体而言，我们将确定脾酪氨酸激酶（Syk）在 肺血管内皮细胞（EC）屏障破坏和炎症，并评估 靶向Syk对抗脓毒症小鼠的ALI。这项研究的基本原理是基于我们的新发现， 作为EC渗透性和炎症的关键调节剂，EC限制性Syk敲除小鼠 显著保护LPS诱导的肺血管损伤。我们也有证据证明 Syk可能通过细胞表面血管内皮钙粘蛋白（VE-钙粘蛋白）的丢失发挥其屏障破坏作用， 引起粘附连接的解体，并通过募集组蛋白发挥促炎作用 乙酰转移酶（HAT）p300以增加NF-κB信号传导。此外，我们的数据显示Syk抑制剂R788 在类风湿性关节炎中显示出积极的临床益处， 并提高脓毒症小鼠模型的存活率。这些令人兴奋的新发现让我们假设， 内皮细胞中的Syk/VE-cadherin和Syk/p300轴是肺血管炎症的重要组成部分 抑制Syk可能是控制脓毒症小鼠ALI的有效治疗方法。 目的1将测试Syk通过介导内皮细胞粘附连接（AJs）破坏的可能性。 VE-钙粘蛋白的酪氨酸磷酸化和蛋白水解/内吞作用。目标2将测试Syk 调节EC促炎表型，导致EC-中性粒细胞（PMN）相互作用和跨内皮 通过募集p300促进PMN迁移，p300催化RelA的乙酰化以增加NF-κB信号传导。目的 3（i）将使用EC消融的Syk小鼠评价内皮Syk在炎性肺损伤中的因果作用， (ii)评估Syk抑制对控制ALI的治疗潜力。我们将结合使用细胞， 分子和生物化学方法，并利用EC消融的Syk和脓毒症小鼠模型 （盲肠结扎穿刺[CLP]或腹腔内LPS激发）进行这些研究。体外的创造性整合 而体内方法将提供关于Syk在ALI中的作用的有价值的机制信息， 导致新的治疗干预，包括抑制Syk以控制与脓毒症相关的ALI/ARDS。

The overall objective of this proposal is to understand how lung microvasculature acquires “proinflammatory and leaky” phenotype during sepsis with a view to identifying viable therapeutic target to control sepsis-induced acute lung injury (ALI). Specifically, we will determine the role of Spleen Tyrosine Kinase (Syk) in the mechanism of lung vascular endothelial cell (EC) barrier disruption and inflammation and assess the therapeutic benefit of targeting Syk against ALI in mice with sepsis. The rationale for the study is based on our novel findings that Syk acts as a critical regulator of EC permeability and inflammation and that EC-restricted Syk knockout mice are markedly protected against LPS-induced lung vascular injury. We also have evidence that support the notion that Syk may exert its barrier disruptive effect via loss of cell surface vascular endothelial cadherin (VE-cadherin) to cause disassembly of adherens junctions, and its proinflammatory effect via recruitment of histone acetyltransferase (HAT) p300 to increase NF-κB signaling. Additionally our data show that Syk inhibitor R788 (fostamatinib), which has shown positive clinical benefits in rheumatoid arthritis, ameliorates lung tissue edema and improves survival in mouse models of sepsis. These new exciting findings have led us to hypothesize that Syk/VE-cadherin and Syk/p300 axes in the endothelium are critical components of lung vascular inflammation and injury, and that inhibiting Syk may be an effective therapeutic approach to control ALI in mice with sepsis. Aim 1 will test the possibility that Syk causes disruption of endothelial adherens junctions (AJs) by mediating tyrosine phosphorylation and proteolysis/endocytosis of VE-cadherin. Aim 2 will test the possibility that Syk regulates EC proinflammatory phenotype, leading to EC-neutrophil (PMN) interactions and transendothelial migration of PMN via recruitment of p300 which catalyzes acetylation of RelA to increase NF-κB signaling. Aim 3 (i) will evaluate the causal role of endothelial Syk in inflammatory lung injury using EC-ablated Syk mice and (ii) evaluate the therapeutic potential of Syk inhibition to control ALI. We will use a combination of cellular, molecular, and biochemical approaches, and take advantage of EC-ablated Syk and mouse models of sepsis (cecal ligation puncture [CLP] or i.p. LPS challenge) to pursue these studies. The creative integration of in vitro and in vivo approaches will provide valuable mechanistic information concerning the role of Syk in ALI and may lead to novel therapeutic interventions involving inhibition of Syk to control ALI/ARDS associated with sepsis.