分泌型PRDX1介导ARDS机械通气相关性肺纤维化的分子机制

ARDS is a common fatal complication of critical ill patients. Mechanical ventilation is the primary strategy for ARDS treatment, but improper ventilation can cause ventilator-induced lung injury. Persistent pulmonary epithelial cell damage and pathological repair easily cause pulmonary fibrosis in ARDS patients, which is associated with poor prognosis. Currently, the mechanism of mechanical stretch-induced pulmonary fibrosis is unclear. Our previous studies have shown that PRDX1 is elevated in the lung tissue of hyper-ventilation induced lung injury in rats. Our preliminary experiments found that lung epithelial cells could undergo Epithelial–mesenchymal transition by the treatment of recombinant PRDX1, which was able to activate NF-κB activity. In the current project, we are aiming to investigate secreted PRDX1, a damage-associated molecular pattern molecule (DAMP), promotes the activation of TLR- NF-κB signaling pathway to induce EMT, resulting in ventilator-associated pulmonary fibrosis. In combination with our ARDS clinical specimens bio-bank, we will also analyze the relationship between PRDX1 expression level in the serum of ARDS patients with pulmonary fibrosis and their prognosis of the disease. The project will further clarify the important role of PRDX1 in mechanical ventilation induce pulmonary fibrosis, thus providing new targets for ARDS-related fibrosis diagnosis and treatment.

ARDS是重症病人最常见的致死性并发症，机械通气是救治ARDS的主要手段，但不当的机械通气可以造成肺损伤，肺上皮细胞的持续损伤和病理性修复容易诱导肺纤维化，肺纤维化提示ARDS患者的不良预后。目前，机械牵张引起肺纤维化的机制不清楚。我们前期研究表明抗氧化应激蛋白PRDX1在过度通气肺损伤动物模型中的肺组织异常升高；我们的预实验发现PRDX1重组蛋白可以诱导上皮细胞间质转化（EMT），并增强NF-κB活性。本项目将进一步证实分泌型PRDX1作为一种损伤相关分子模式分子（DAMP），可能通过与细胞表面的TLR4受体结合，激活TLR4-NF-κB通路，促进EMT介导的机械通气相关肺纤维化；结合本课题组丰富的ARDS临床标本库，将分析ARDS患者血浆中PRDX1水平和肺纤维化及临床预后关系。本项目将阐明PRDX1在机械通气肺损伤相关纤维化中的重要作用，为ARDS相关肺纤维化的诊断和治疗提供新靶点。

ARDS是重症监护室最常见的致死性并发症，机械通气是救治ARDS患者的主要手段，但不当的机械通气可以造成呼吸机相关肺损伤。肺上皮细胞的持续损伤和病理性修复可以导致肺纤维化发生，ARDS出现肺纤维化提示不良预后。目前，机械通气引起肺损伤和纤维化的机制并不清楚。我们的前期研究表明PRDX1是过度通气肺损伤动物模型中肺组织高表达的一种蛋白，但其在ARDS机械通气相关肺损伤和肺纤维化的作用和分子机制并未见报道。在本项目中，我们的研究发现1、机械牵张BEAS-2B细胞PRDX1的表达增加、细胞上清分泌型PRDX1含量增高；2、沉默PRDX1的表达可以降低机械牵张诱导的BEAS-2B细胞炎症因子的表达，而重组PRDX1蛋白刺激肺上皮细胞可促进炎症因子的表达；3、重组PRDX1刺激可导致HPMVECs通透性升高，沉默PRDX1受体TLR4的表达可以部分减轻PRDX1刺激导致的内皮细胞通透性增加；4、PRDX1在机械牵张诱导的上皮细胞间质转化中起关键作用；5、机械牵张BEAS-2B细胞促进NF-κB信号通路激活，沉默PRDX1的表达可以抑制机械牵张介导的的肺上皮细胞NF-κB信号通路的激活；6、ARDS患者血浆中PRDX1的浓度相较于健康志愿者明显增高，PRDX1的浓度与SP-D和炎症因子的浓度呈正相关；在机械通气相关的肺损伤动物模型中肺组织的PRDX1的表达升高。此外我们还发现microRNA -19b通过直接下调PTEN的表达水平进而激活AKT通路促进机械牵张诱导的上皮间质转分化。我们还进一步完善了本单位ARDS患者临床资料数据库和扩大了ARDS临床标本库，并研究了ARDS相关的血浆分子标记物Gelatin-3的临床意义。通过本项目的研究了阐明了PRDX1在ARDS机械通气相关肺损伤和纤维化的作用及分子机制，为ARDS的诊疗提供了新的分子标记物和治疗靶点。