Extracellular Histones in Burn-induced Microvascular Hyperpermeability

摘要 细胞外组蛋白是在组织破坏或细胞分裂过程中释放到细胞外环境的核蛋白。 损伤新出现的证据表明它们是具有免疫刺激能力的危险相关分子。 负责其组织或细胞特异性效应的受体信号传导机制知之甚少。在 在最近的研究中，我们检测到烧伤患者和动物血浆中组蛋白水平升高。管理 引起微血管渗漏和内皮细胞高渗透性的病理学特征 烧伤后多器官功能障碍，而组蛋白抑制剂减弱烧伤诱导的屏障渗漏。 此外，我们获得了新的证据，C型凝集素受体2d（Clec 2d）介导的酪氨酸的关键作用， 内皮细胞对组蛋白反应中的激酶信号传导。基于这些有趣的发现，这项研究将描述 组蛋白的释放，病理生理功能和分子机制，作为一个重要的贡献， 烧伤诱导的易水肿组织（包括肺和肠道/肠系膜微血管）的内皮屏障损伤。 我们提出了三个目标：目标1：表征烧伤患者和动物中循环组蛋白的特征， 目的2：确定组蛋白对微血管通透性增高的因果作用， 目的3探讨组蛋白诱导内皮屏障破坏的分子机制。的 待检验的具体机制假设是，在组织的热破坏之后，受损细胞释放 组蛋白进入循环，在那里它们通过结合Clec 2d直接与血管内皮相互作用， 激活由Syk/Src-FAK介导的下游细胞内信号传导;这些酪氨酸激酶磷酸化 构成细胞-细胞连接和细胞-基质粘着斑的蛋白质，从而触发它们的构象 变化，导致渗透性增加。这种新的途径将在创新实验中进行测试， 将新开发成像技术和分子分析纳入烧伤的比较分析 患者、人体器官和动物/细胞模型。通过这种翻译研究，我们期望获得新的见解 这不仅将改变目前血管内皮细胞生物学的范式， 了解烧伤病理生理学。循环组蛋白作为烧伤诱导的细胞凋亡的关键介质的鉴定 组织/器官损伤可能导致开发用于热创伤的新诊断和治疗。

ABSTRACT Extracellular histones are nuclear proteins released to the extracellular environment during tissue destruction or injury. Emerging evidence implicates them as danger associated molecules with immunostimulatory capability. The receptor-signaling mechanisms responsible for their tissue or cell-specific effects are poorly understood. In recent studies, we detected elevated plasma levels of histones in burn patients as well as animals. Administration of histones caused microvascular leakage and endothelial hyperpermeability-characteristic pathology underlying multiple organ dysfunction following burns, whereas histone inhibitors attenuated burn-induced barrier leakage. Moreover, we obtained novel evidence for the critical role of C-type lectin receptor 2d (Clec2d)-mediated tyrosine kinase signaling in endothelial response to histones. Built on these intriguing findings, this study will characterize the release, pathophysiological function, and molecular mechanisms of histones as an important contributor to burn-induced endothelial barrier injury in edema-prone tissues, including lungs and gut/mesenteric microvessels. We propose three aims: Aim 1 to characterize circulating histones in burn patients and animals correlated with organ dysfunction; Aim 2 to determine the causal effects of histones on microvascular hyperpermeability during burns; Aim 3 to explore the molecular mechanisms by which histones induce endothelial barrier breakdown. The specific mechanistic hypothesis to be tested is that following thermal destruction of tissues, injured cells release histones into the circulation where they directly interact with the vascular endothelium by binding to Clec2d and activating downstream intracellular signaling mediated by Syk/Src-FAK; these tyrosine kinases phosphorylate proteins that constitute cell-cell junctions and cell-matrix focal adhesions, thereby triggering their conformational changes and leading to increased permeability. This novel pathway will be tested in innovative experiments that incorporate newly developed imaging techniques and molecular assays into a comparative analysis of burn patients, human organs, and animal/cell models. Through this translational study, we expect to gain new insights that will not only shift the current paradigms in vascular endothelial cell biology, but also fill the gaps of knowledge in understanding burn pathophysiology. Identification of circulating histones as a key mediator of burn-induced tissue/organ injury may lead to the development of new diagnostics and therapies for thermal trauma.