Department of Anaesthesia and Critical Care, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Road, Wenzhou, 325027, Zhejiang, People's Republic of China.
Respir Res. 2021 Jul 3;22(1):193. doi: 10.1186/s12931-021-01793-x.
Endothelial glycocalyx loss is integral to increased pulmonary vascular permeability in sepsis-related acute lung injury. Protectin conjugates in tissue regeneration 1 (PCTR1) is a novel macrophage-derived lipid mediator exhibiting potential anti-inflammatory and pro-resolving benefits.
PCTR1 was administrated intraperitoneally with 100 ng/mouse after lipopolysaccharide (LPS) challenged. Survival rate and lung function were used to evaluate the protective effects of PCTR1. Lung inflammation response was observed by morphology and inflammatory cytokines level. Endothelial glycocalyx and its related key enzymes were measured by immunofluorescence, ELISA, and Western blot. Afterward, related-pathways inhibitors were used to identify the mechanism of endothelial glycocalyx response to PCTR1 in mice and human umbilical vein endothelial cells (HUVECs) after LPS administration.
In vivo, we show that PCTR1 protects mice against lipopolysaccharide (LPS)-induced sepsis, as shown by enhanced the survival and pulmonary function, decreased the inflammatory response in lungs and peripheral levels of inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and interleukin-1β. Moreover, PCTR1 restored lung vascular glycocalyx and reduced serum heparin sulphate (HS), syndecan-1 (SDC-1), and hyaluronic acid (HA) levels. Furthermore, we found that PCTR1 downregulated heparanase (HPA) expression to inhibit glycocalyx degradation and upregulated exostosin-1 (EXT-1) protein expression to promote glycocalyx reconstitution. Besides, we observed that BAY11-7082 blocked glycocalyx loss induced by LPS in vivo and in vitro, and BOC-2 (ALX antagonist) or EX527 (SIRT1 inhibitor) abolished the restoration of HS in response to PCTR1.
PCTR1 protects endothelial glycocalyx via ALX receptor by regulating SIRT1/NF-κB pathway, suggesting PCTR1 may be a significant therapeutic target for sepsis-related acute lung injury.
内皮糖萼的丢失是脓毒症相关急性肺损伤中肺血管通透性增加的重要因素。组织再生 1 型保护素（PCTR1）是一种新型的巨噬细胞衍生的脂质介质，具有潜在的抗炎和促解决作用。
脂多糖（LPS）处理后，PCTR1 经腹腔内给予小鼠 100ng/只。用存活率和肺功能来评价 PCTR1 的保护作用。通过形态和炎性细胞因子水平观察肺炎症反应。用免疫荧光、ELISA 和 Western blot 测定内皮糖萼及其相关关键酶。然后，用相关通路抑制剂来鉴定内皮糖萼对 LPS 处理后小鼠和人脐静脉内皮细胞（HUVEC）中 PCTR1 反应的机制。
在体内，我们发现 PCTR1 可增强存活和肺功能，降低肺部炎症反应和外周血中肿瘤坏死因子-α、白细胞介素-6 和白细胞介素-1β等炎性细胞因子水平，从而保护 LPS 诱导的脓毒症小鼠。此外，PCTR1 可恢复肺血管糖萼，并降低血清肝素硫酸盐（HS）、连接蛋白-1（SDC-1）和透明质酸（HA）水平。此外，我们发现 PCTR1 下调硫酸乙酰肝素酶（HPA）表达以抑制糖萼降解，并上调外切糖苷酶-1（EXT-1）蛋白表达以促进糖萼重建。此外，我们观察到 BAY11-7082 可阻断 LPS 在体内和体外诱导的糖萼丢失，而 BOC-2（ALX 拮抗剂）或 EX527（SIRT1 抑制剂）可消除对 PCTR1 响应的 HS 恢复。
PCTR1 通过调节 SIRT1/NF-κB 通路通过 ALX 受体保护内皮糖萼，提示 PCTR1 可能是脓毒症相关急性肺损伤的重要治疗靶点。
