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

这项建议的总体目标是了解肺微血管如何获得“促炎和 脓毒症时的“渗漏”表型，以期找到可行的治疗靶点来控制脓毒症所致的急性 肺损伤(ALI)。具体地说，我们将确定脾酪氨酸激酶(Syk)在血管紧张素转换酶的作用机制中的作用。 肺血管内皮细胞(EC)屏障破坏和炎症，并评估其治疗益处 在脓毒症小鼠体内靶向Syk抗ALI。这项研究的理论基础是基于我们的新发现，即Syk 作为EC通透性和炎症的关键调节因子，EC限制性Syk基因敲除小鼠 对脂多糖诱导的肺血管损伤有明显的保护作用。我们也有证据支持这一观点 Syk可能通过细胞表面血管内皮钙粘附素(VE-cadherin)的丢失发挥其屏障破坏作用 引起黏附连接的解体，及其通过组蛋白募集而产生的促炎作用 乙酰基转移酶(HAT)p300，以增加核因子-κB信号。此外，我们的数据显示，Syk抑制剂R788 (福斯塔替尼)对类风湿性关节炎有积极的临床疗效，可改善肺组织浮肿。 并提高脓毒症小鼠模型的存活率。这些令人兴奋的新发现使我们假设 内皮细胞中的Syk/VE-钙粘蛋白和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。 目标1将测试Syk通过介导内皮细胞黏附连接(AJs)破坏的可能性 VE-钙粘蛋白的酪氨酸磷酸化和蛋白降解/内吞作用。目标2将测试赛克 调节EC前炎症表型，导致EC-中性粒细胞(PMN)相互作用和跨内皮细胞 中性粒细胞通过募集p300进行迁移，p300可以催化RELA的乙酰化，从而增加NF-κB信号转导。目标 3(I)将利用EC消融的Syk小鼠和 (Ii)评价Syk抑制剂控制ALI的治疗潜力。我们将结合使用蜂窝， 分子和生化方法，并利用EC消融的Syk和小鼠脓毒症模型 (盲肠结扎穿刺术[CLP]或I.P.LP挑战)来继续这些研究。体外创造性整合 体内方法将提供有关Syk在ALI中的作用的有价值的机械性信息，并可能 导致新的治疗干预措施，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.