RATIONALE BMX (bone marrow kinase on the X chromosome) is highly expressed in the arterial endothelium from the embryonic stage to the adult stage in mice. It is also expressed in microvessels and the lymphatics in response to pathological stimuli. However, its role in endothelial permeability and sepsis remains unknown. OBJECTIVE We aimed to delineate the function of BMX in thrombin-mediated endothelial permeability and the vascular leakage that occurs with sepsis in cecal ligation and puncture models. METHODS AND RESULTS The cecal ligation and puncture model was applied to WT (wild type) and BMX-KO (BMX global knockout) mice to induce sepsis. Meanwhile, the electric cell-substrate impedance sensing assay was used to detect transendothelial electrical resistance in vitro and, the modified Miles assay was used to evaluate vascular leakage in vivo. We showed that BMX loss caused lung injury and inflammation in early cecal ligation and puncture-induced sepsis. Disruption of BMX increased thrombin-mediated permeability in mice and cultured endothelial cells by 2- to 3-fold. The expression of BMX in macrophages, neutrophils, platelets, and lung epithelial cells was undetectable compared with that in endothelial cells, indicating that endothelium dysfunction, rather than leukocyte and platelet dysfunction, was involved in vascular permeability and sepsis. Mechanistically, biochemical and cellular analyses demonstrated that BMX specifically repressed thrombin-PAR1 (protease-activated receptor-1) signaling in endothelial cells by directly phosphorylating PAR1 and promoting its internalization and deactivation. Importantly, pretreatment with the selective PAR1 antagonist SCH79797 rescued BMX loss-mediated endothelial permeability and pulmonary leakage in early cecal ligation and puncture-induced sepsis. CONCLUSIONS Acting as a negative regulator of PAR1, BMX promotes PAR1 internalization and signal inactivation through PAR1 phosphorylation. Moreover, BMX-mediated PAR1 internalization attenuates endothelial permeability to protect vascular leakage during early sepsis.

中文翻译：

---

BMX在败血症早期抑制凝血酶-PAR1介导的内皮渗透性和血管渗漏。

从小鼠的胚胎期到成年期，RATIONALE BMX（X染色体上的骨髓激酶）在动脉内皮中高表达。它还在微血管和淋巴管中表达，以响应病理刺激。然而，其在内皮通透性和败血症中的作用仍然未知。目的我们旨在描述BMX在盲肠结扎和穿刺模型中在凝血酶介导的内皮通透性和败血症引起的血管渗漏中的功能。方法和结果将盲肠结扎和穿刺模型应用于野生型WT小鼠和BMX-KO全基因敲除小鼠，以诱导败血症。同时，使用细胞-基底阻抗感测法在体外检测跨内皮电阻，并且 改良的Miles分析用于评估体内血管渗漏。我们显示，BMX的丢失在早期盲肠结扎和穿刺引起的败血症中引起肺部损伤和炎症。BMX的破坏使小鼠和培养的内皮细胞中的凝血酶介导的通透性增加了2到3倍。与内皮细胞相比，在巨噬细胞，嗜中性粒细胞，血小板和肺上皮细胞中无法检测到BMX的表达，这表明内皮功能障碍而不是白细胞和血小板功能障碍与血管通透性和败血症有关。从机理上讲，生物化学和细胞分析表明BMX通过直接磷酸化PAR1并促进其内在化和失活而特异性抑制内皮细胞中的凝血酶-PAR1（蛋白酶激活的受体1）信号传导。重要的，选择性PAR1拮抗剂SCH79797预处理可在早期盲肠结扎和穿刺引起的败血症中挽救BMX介导的内皮通透性和肺漏。结论BMX充当PAR1的负调节剂，通过PAR1磷酸化促进PAR1内在化和信号失活。此外，BMX介导的PAR1内在化作用减弱了内皮的通透性，以保护败血症早期的血管渗漏。