Department of Emergency, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou 570311, Hainan Province, PR China; Key Laboratory of Emergency and Trauma, Ministry of Education, Key Laboratory of Hainan Trauma and Disaster Rescue, The First Affiliated Hospital of Hainan Medical University, College of Emergency and Trauma, Hainan Medical University, Haikou, 571199, China.
Department of Cardiology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou 570311, Hainan Province, PR China.
Immunobiology. 2022 Jul;227(4):152219. doi: 10.1016/j.imbio.2022.152219. Epub 2022 Apr 12.
Sepsis causes severe acute lung injury (ALI). Circular RNA is involved in the regulation of sepsis-related ALI progression. The regulation mechanism of circEXOC5 in sepsis-induced ALI is still unclear. Whether circEXOC5 is involved in the regulation of ferroptosis remains to be explored.
We constructed a mouse model of sepsis through cecal ligation and puncture (CLP). LPS induced mouse lung microvascular endothelial cells (MPVECs) to construct a sepsis cell model. The expression of circEXOC5 in the sepsis model was detected by qPCR. The extent of lung injury in mice was analyzed by HE staining. The contents of GSH/GSSG, iron, MDA and 4HNE in mice lung tissues and cells were detected by the kit. And further the ROS content was detected in the cells. Finally, the binding relationship between circEXOC5 and PTBP1 was detected by RIP and RNA pulldown.
Our results showed that the circEXOC5 expression was significantly increased in the in vivo and in vitro models of sepsis. And after inhibiting circEXOC5, it improved the lung injury of septic mice. It was confirmed in cell models that ROS levels and ferroptosis in cells were reduced after knocking down circEXOC5. In addition, the expressions of ACSL4 and Gpx4 proteins were regulated by the level of circEXOC5. Finally, we also found that circEXOC5 had a direct binding relationship with PTBP1.
Our study found that the expression of cell ferroptosis and circEXOC5 increased in ALI induced by sepsis, and circEXOC5 aggravated ferroptosis in septic cells by regulating the PTBP1/ACSL4 axis.
脓毒症可导致严重的急性肺损伤（ALI）。环状 RNA 参与了脓毒症相关 ALI 进展的调控。circEXOC5 在脓毒症诱导的 ALI 中的调控机制尚不清楚。circEXOC5 是否参与铁死亡的调控仍有待探讨。
我们通过盲肠结扎穿孔（CLP）构建了脓毒症小鼠模型。用 LPS 诱导小鼠肺微血管内皮细胞（MP-VECs）构建脓毒症细胞模型。通过 qPCR 检测脓毒症模型中 circEXOC5 的表达。通过 HE 染色分析小鼠肺部损伤程度。通过试剂盒检测小鼠肺组织和细胞中 GSH/GSSG、铁、MDA 和 4HNE 的含量。进一步检测细胞内 ROS 含量。最后，通过 RIP 和 RNA 下拉实验检测 circEXOC5 与 PTBP1 的结合关系。
我们的结果表明，在脓毒症的体内和体外模型中，circEXOC5 的表达明显增加。抑制 circEXOC5 后，改善了脓毒症小鼠的肺损伤。在细胞模型中证实，敲低 circEXOC5 后，细胞内 ROS 水平和铁死亡减少。此外，ACSL4 和 Gpx4 蛋白的表达受 circEXOC5 水平的调节。最后，我们还发现 circEXOC5 与 PTBP1 有直接的结合关系。
本研究发现，脓毒症诱导的 ALI 中细胞铁死亡和 circEXOC5 的表达增加，circEXOC5 通过调节 PTBP1/ACSL4 轴加重脓毒症细胞的铁死亡。
