Hepatic mitochondrial DNA/Toll-like receptor 9/MicroRNA-223 forms a negative feedback loop to limit neutrophil overactivation and acetaminophen hepatotoxicity in mice.
Hepatic mitochondrial DNA/Toll-like receptor 9/MicroRNA-223 forms a negative feedback loop to limit neutrophil overactivation and acetaminophen hepatotoxicity in mice.
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肝线粒体 DNA/Toll 样受体 9/MicroRNA-223 形成负反馈环，限制小鼠中性粒细胞过度激活和对乙酰氨基酚肝毒性
DOI：
10.1002/hep.29153
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发表时间：
2017-07
期刊：
影响因子：
--
通讯作者：
Gao B
中科院分区：
文献类型：
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作者：
He Y;Feng D;Li M;Gao Y;Ramirez T;Cao H;Kim SJ;Yang Y;Cai Y;Ju C;Wang H;Li J;Gao B
对乙酰氨基酚（APAP）过量是全球急性肝功能衰竭的主要原因，其中受损肝细胞释放的线粒体DNA（mtDNA）通过结合TLR 9激活中性粒细胞，进一步加重肝损伤。在这里，我们证明了mtDNA/TLR 9还通过诱导microRNA-223（miR-223）激活负反馈通路，以限制中性粒细胞过度激活和肝损伤。在小鼠中注射APAP后，中性粒细胞中最丰富的miRNA miR-223的水平在中性粒细胞中高度升高。miR-223基因的破坏加剧了APAP诱导的肝脏中性粒细胞浸润、氧化应激和损伤，并增强了中性粒细胞中TLR 9配体介导的促炎介质活化。细胞间粘附分子1（ICAM-1）基因的额外缺失改善了miR-223敲除小鼠中APAP诱导的中性粒细胞浸润和肝损伤。体外实验显示，miR-223缺陷型中性粒细胞对TLR 9激动剂介导的促炎介质和NF-κB信号传导的诱导更敏感;而miR-223过表达减弱了中性粒细胞中的这些作用。此外，通过用TLR 9抑制剂处理或通过破坏TLR 9基因来抑制TLR 9信号传导部分但显著地抑制APAP注射后中性粒细胞中的miR-223表达。相反，TLR 9的激活在体内和体外上调中性粒细胞中的miR-223表达。在机制上，TLR 9的激活通过增强NF-κB与miR-223启动子的结合上调miR-223;而miR-223通过靶向IKKα表达减弱TLR 9/NF-κ B介导的炎症。总之，miR-223的上调在终止急性嗜酸性反应中起关键作用，并且是治疗APAP诱导的肝衰竭的治疗靶点。
Acetaminophen (APAP) overdose is a leading cause of acute liver failure worldwide, in which mitochondrial DNA (mtDNA) released by damaged hepatocytes activates neutrophils via the binding of TLR9, further aggravating liver injury. Here, we demonstrated that mtDNA/TLR9 also activates a negative feedback pathway via the induction of microRNA-223 (miR-223) to limit neutrophil over-activation and liver injury. After injection of APAP in mice, levels of miR-223, the most abundant miRNAs in neutrophils, were highly elevated in neutrophils. Disruption of the miR-223 gene exacerbated APAP-induced hepatic neutrophil infiltration, oxidative stress, and injury, and enhanced TLR9 ligand-mediated activation of pro-inflammatory mediators in neutrophils. An additional deletion of the intercellular adhesion molecule 1 (ICAM-1) gene ameliorated APAP-induced neutrophil infiltration and liver injury in miR-223 knockout mice. In vitro experiments revealed that miR-223-deficient neutrophils were more susceptible to TLR9 agonist-mediated induction of pro-inflammatory mediators and NF-κB signaling; whereas overexpression of miR-223 attenuated these effects in neutrophils. Moreover, inhibition of TLR9 signaling via either treatment with a TLR9 inhibitor or via the disruption of TLR9 gene partially but significantly suppressed miR-223 expression in neutrophils post APAP injection. In contrast, activation of TLR9 upregulated miR-223 expression in neutrophils in vivo and in vitro. Mechanistically, activation of TLR9 upregulated miR-223 by enhancing NF-κB binding on miR-223 promoter; while miR-223 attenuated TLR9/NF-κB-mediated inflammation by targeting IKKα expression. Collectively, upregulation of miR-223 plays a key role in terminating the acute neutrophilic response and is a therapeutic target for the treatment of APAP-induced liver failure.