Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA.
Department of Surgery, Shanghai Tenth People's Hospital, Tenth People's Hospital of Tongji University, Shanghai, People's Republic of China.
Hepatology. 2018 Mar;67(3):1056-1070. doi: 10.1002/hep.29605. Epub 2018 Jan 24.
The role and regulators of extracellular vesicle (EV) secretion in hepatic ischemia/reperfusion (IR) injury have not been defined. Rab27a is a guanosine triphosphatase known to control EV release. Interferon regulatory factor 1 (IRF-1) is a transcription factor that plays an important role in liver IR and regulates certain guanosine triphosphatases. However, the relationships among IRF-1, Rab27a, and EV secretion are largely unknown. Here, we show induction of IRF-1 and Rab27a both in vitro in hypoxic hepatocytes and in vivo in warm IR and orthotopic liver transplantation livers. Interferon γ stimulation, IRF-1 transduction, or IR promoted Rab27a expression and EV secretion. Meanwhile, silencing of IRF-1 decreased Rab27a expression and EV secretion. Rab27a silencing decreased EV secretion and liver IR injury. Ten putative IRF-1 binding motifs in the 1,692-bp Rab27a promoter region were identified. Chromatin immunoprecipitation and electrophoretic mobility shift assay verified five functional IRF-1 binding motifs, which were confirmed by a Rab27a promoter luciferase assay. IR-induced EVs contained higher oxidized phospholipids (OxPL). OxPLs on the EV surface activated neutrophils through the toll-like receptor 4 pathway. OxPL-neutralizing E06 antibody blocked the effect of EVs and decreased liver IR injury.
These findings provide a novel mechanism by which IRF-1 regulates Rab27a transcription and EV secretion, leading to OxPL activation of neutrophils and subsequent hepatic IR injury. (Hepatology 2018;67:1056-1070).
细胞外囊泡（EV）在肝缺血/再灌注（IR）损伤中的分泌作用及其调节因子尚未确定。Rab27a 是一种已知控制 EV 释放的鸟嘌呤三磷酸酶。干扰素调节因子 1（IRF-1）是一种在肝 IR 中起重要作用并调节某些鸟嘌呤三磷酸酶的转录因子。然而，IRF-1、Rab27a 和 EV 分泌之间的关系在很大程度上尚不清楚。在这里，我们显示在体外缺氧肝细胞中和体内温热 IR 和原位肝移植肝脏中诱导 IRF-1 和 Rab27a 的表达。干扰素 γ 刺激、IRF-1 转导或 IR 促进 Rab27a 表达和 EV 分泌。同时，沉默 IRF-1 降低 Rab27a 表达和 EV 分泌。Rab27a 沉默减少 EV 分泌和肝 IR 损伤。在 1692bp 的 Rab27a 启动子区域中鉴定出 10 个推定的 IRF-1 结合基序。染色质免疫沉淀和电泳迁移率变动分析验证了 5 个功能性 IRF-1 结合基序，通过 Rab27a 启动子荧光素酶测定证实了这些基序。IR 诱导的 EV 中含有更高的氧化磷脂（OxPL）。EV 表面上的 OxPL 通过 toll 样受体 4 途径激活中性粒细胞。OxPL 中和 E06 抗体阻断了 EV 的作用并减少了肝 IR 损伤。
这些发现提供了一个新的机制，即 IRF-1 调节 Rab27a 的转录和 EV 分泌，导致 OxPL 激活中性粒细胞和随后的肝 IR 损伤。（Hepatology 2018;67:1056-1070）。
