Li Yinjiao, Xiao Jinglei, Tan Yongchang, Wang Jun, Zhang Yan, Deng Xiaoming, Luo Yan
a Department of Anesthesiology , Ruijin Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China.
b Department of Anesthesiology and Intensive Care , Changhai Hospital, Second Military Medical University , Shanghai , China.
Immunopharmacol Immunotoxicol. 2017 Aug;39(4):165-172. doi: 10.1080/08923973.2017.1303839. Epub 2017 May 17.
Acute lung injury (ALI) is characterized by dramatic lung inflammation and alveolar epithelial cell death. Although protein kinase R (PKR) (double-stranded RNA-activated serine/threonine kinase) has been implicated in inflammatory response to bacterial cell wall components, whether it plays roles in lipopolysaccharide (LPS)-induced ALI remains unclear. This study was aimed to reveal whether and how PKR was involved in LPS-induced ALI pathology and the potential effects of its specific inhibitor, C16 (CHNOS). During the experiment, mice received C16 (100 or 500 ug/kg) intraperitoneally 1 h before intratracheal LPS instillation. Then, whole lung lavage was collected for analysis of total protein levels and proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6. The lungs were tested for Western blot, transferase-mediated dUTP nick-end labeling (TUNEL) stain and immunohistochemistry. Results showed that PKR phosphorylation increased significantly after LPS instillation. Furthermore, PKR specific inhibition attenuated LPS-induced lung injury (hematoxylin and eosin stain), reduced lung protein permeability (total protein levels in whole lung lavage) and suppressed proinflammatory cytokines (TNF-α, IL-1β and IL-6) and lung apoptosis (TUNEL stain and caspase3 activation). Moreover, mechanism-study showed that C16 significantly suppressed I kappa B kinase (IKK)/I kappa B alpha (IκBα)/NF-κB signaling pathway after LPS challenge. These findings suggested that PKR inhibition ameliorated LPS-induced lung inflammation and apoptosis in mice by suppressing NF-κB signaling pathway.
急性肺损伤（ALI）的特征是肺部出现剧烈炎症和肺泡上皮细胞死亡。尽管蛋白激酶R（PKR，双链RNA激活的丝氨酸/苏氨酸激酶）已被证明参与对细菌细胞壁成分的炎症反应，但它是否在脂多糖（LPS）诱导的ALI中发挥作用仍不清楚。本研究旨在揭示PKR是否以及如何参与LPS诱导的ALI病理过程及其特异性抑制剂C16（CHNOS）的潜在作用。实验过程中，小鼠在气管内注入LPS前1小时腹腔注射C16（100或500μg/kg）。然后，收集全肺灌洗液分析总蛋白水平和促炎细胞因子，包括肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）和IL-6。对肺组织进行蛋白质免疫印迹法、末端脱氧核苷酸转移酶介导的缺口末端标记（TUNEL）染色和免疫组织化学检测。结果显示，注入LPS后PKR磷酸化显著增加。此外，PKR特异性抑制减轻了LPS诱导的肺损伤（苏木精-伊红染色），降低了肺蛋白通透性（全肺灌洗液中的总蛋白水平），并抑制了促炎细胞因子（TNF-α、IL-1β和IL-6）和肺细胞凋亡（TUNEL染色和半胱天冬酶3激活）。此外，机制研究表明，C16在LPS攻击后显著抑制了IκB激酶（IKK）/IκBα/NF-κB信号通路。这些发现表明，PKR抑制通过抑制NF-κB信号通路改善了LPS诱导的小鼠肺部炎症和细胞凋亡。
