Reduced endothelial Tie2 expression occurs in diverse experimental models of critical illness, and experimental Tie2 suppression is sufficient to increase spontaneous vascular permeability. Looking for a common denominator among different critical illnesses that could drive the same Tie2 suppressive (thereby leak inducing) phenotype, we identified “circulatory shock” as a shared feature and postulated a flow-dependency of Tie2 gene expression in a GATA3 dependent manner. Here, we analyzed if this mechanism of flow-regulation of gene expression exists in vivo in the absence of inflammation. To experimentally mimic a shock-like situation, we developed a murine model of clonidine-induced hypotension by targeting a reduced mean arterial pressure (MAP) of approximately 50% over 4 h. We found that hypotension-induced reduction of flow in the absence of confounding disease factors (i.e., inflammation, injury, among others) is sufficient to suppress GATA3 and Tie2 transcription. Conditional endothelial-specific GATA3 knockdown (B6-Gata3tm1-Jfz VE-Cadherin(PAC)-cerERT2) led to baseline Tie2 suppression inducing spontaneous vascular leak. On the contrary, the transient overexpression of GATA3 in the pulmonary endothelium (jet-PEI plasmid delivery platform) was sufficient to increase Tie2 at baseline and completely block its hypotension-induced acute drop. On the functional level, the Tie2 protection by GATA3 overexpression abrogated the development of pulmonary capillary leakage. The data suggest that the GATA3–Tie2 signaling pathway might play a pivotal role in controlling vascular barrier function and that it is affected in diverse critical illnesses with shock as a consequence of a flow-regulated gene response. Targeting this novel mechanism might offer therapeutic opportunities to treat vascular leakage of diverse etiologies.

中文翻译：

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体内 GATA3 对内皮 Tie2 的流量依赖性调节


内皮 Tie2 表达减少发生在多种危重疾病实验模型中，实验性 Tie2 抑制足以增加自发血管通透性。为了寻找不同危重疾病之间可能驱动相同 Tie2 抑制（从而诱导渗漏）表型的共同点，我们将“循环休克”确定为共同特征，并假设 Tie2 基因表达以 GATA3 依赖方式存在流量依赖性。在这里，我们分析了在没有炎症的情况下这种基因表达流量调节机制是否存在于体内。为了通过实验模拟类似休克的情况，我们开发了可乐定诱导的低血压小鼠模型，目标是在 4 小时内将平均动脉压 (MAP) 降低约 50%。我们发现，在没有混杂疾病因素（即炎症、损伤等）的情况下，低血压引起的血流减少足以抑制 GATA3 和 Tie2 转录。有条件的内皮特异性 GATA3 敲低 (B6-Gata3tm1-Jfz VE-Cadherin(PAC)-cerERT2) 导致基线 Tie2 抑制，从而诱导自发性血管渗漏。相反，GATA3 在肺内皮细胞（jet-PEI 质粒递送平台）中的短暂过度表达足以增加 Tie2 的基线水平，并完全阻止其低血压引起的急性下降。在功能水平上，GATA3 过表达对 Tie2 的保护消除了肺毛细血管渗漏的发展。数据表明，GATA3-Tie2 信号通路可能在控制血管屏障功能中发挥关键作用，并且它在多种危重疾病中受到影响，其中休克是血流调节基因反应的结果。 针对这种新机制可能为治疗不同病因的血管渗漏提供治疗机会。