BACKGROUND Acute spinal cord injury (SCI) could cause mainly two types of pathological sequelae, the primary mechanical injury, and the secondary injury. The macrophage in SCI are skewed toward the M1 phenotype that might cause the failure to post-SCI repair. METHODS SCI model was established in Balb/c mice, and the changes in macrophage phenotypes after SCI were monitored. Bioinformatic analyses were performed to select factors that might regulate macrophage polarization after SCI. Mouse bone marrow-derived macrophages (BMDMs) were isolated, identified, and induced for M1 or M2 polarization; the effects of lncRNA guanylate binding protein-9 (lncGBP9) and suppressor of cytokine signaling 3 (SOCS3) on macrophages polarization were examined in vitro and in vivo. The predicted miR-34a binding to lncGBP9 and SOCS3 was validated; the dynamic effects of lncGBP9 and miR-34a on SOCS3, signal transducer and activator of transcription 1 (STAT1)/STAT6 signaling, and macrophage polarization were examined. Finally, we investigated whether STAT6 could bind the miR-34a promoter to activate its transcription. RESULTS In SCI Balb/c mice, macrophage skewing toward M1 phenotypes was observed after SCI. In M1 macrophages, lncGBP9 silencing significantly decreased p-STAT1 and SOCS3 expression and protein levels, as well as the production of Interleukin (IL)-6 and IL-12; in M2 macrophages, lncGBP9 overexpression increased SOCS3 mRNA expression and protein levels while suppressed p-STAT6 levels and the production of IL-10 and transforming growth factor-beta 1 (TGF-β1), indicating that lncGBP9 overexpression promotes the M1 polarization of macrophages. In lncGBP9-silenced SCI mice, the M2 polarization was promoted on day 28 after the operation, further indicating that lncGBP9 silencing revised the predominance of M1 phenotype at the late stage of secondary injury after SCI, therefore improving the repair after SCI. IncGBP9 competed with SOCS3 for miR-34a binding to counteract miR-34a-mediated suppression on SOCS3 and then modulated STAT1/STAT6 signaling and the polarization of macrophages. STAT6 bound the promoter of miR-34a to activate its transcription. CONCLUSIONS In macrophages, lncGBP9 sponges miR-34a to rescue SOCS3 expression, therefore modulating macrophage polarization through STAT1/STAT6 signaling. STAT6 bound the promoter of miR-34a to activate its transcription, thus forming two different regulatory loops to modulate the phenotype of macrophages after SCI.

中文翻译：

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LncGBP9 / miR-34a轴通过STAT1 / STAT6和SOCS3将巨噬细胞推向有利于脊髓损伤修复的表型。

背景技术急性脊髓损伤（SCI）可能主要引起两种类型的病理后遗症，即原发性机械损伤和继发性损伤。SCI中的巨噬细胞偏向M1表型，这可能导致SCI修复后失败。方法建立Balb / c小鼠SCI模型，监测SCI后巨噬细胞表型的变化。进行了生物信息学分析，以选择可能调节SCI后巨噬细胞极化的因子。分离，鉴定小鼠骨髓来源的巨噬细胞（BMDM），并诱导其产生M1或M2极化；体外和体内研究了lncRNA鸟苷酸结合蛋白9（lncGBP9）和细胞因子信号传导抑制剂3（SOCS3）对巨噬细胞极化的影响。验证了预测的miR-34a与lncGBP9和SOCS3的结合；研究了lncGBP9和miR-34a对SOCS3，信号转导子和转录激活因子1（STAT1）/ STAT6信号转导以及巨噬细胞极化的动态影响。最后，我们研究了STAT6是否可以结合miR-34a启动子来激活其转录。结果在SCI Balb / c小鼠中，SCI后观察到巨噬细胞向M1表型倾斜。在M1巨噬细胞中，lncGBP9沉默可显着降低p-STAT1和SOCS3的表达和蛋白质水平，以及白介素（IL）-6和IL-12的产生。在M2巨噬细胞中，lncGBP9的过表达增加了SOCS3 mRNA表达和蛋白质水平，同时抑制了p-STAT6的水平以及IL-10和转化生长因子β1（TGF-β1）的产生，表明lncGBP9的过表达促进了巨噬细胞的M1极化。在lncGBP9沉默的SCI小鼠中，术后28天M2极化得到促进，进一步表明lncGBP9沉默在SCI继发性损伤后期改变了M1表型的优势，从而改善了SCI的修复。IncGBP9与SOCS3竞争miR-34a结合，以抵消miR-34a介导的对SOCS3的抑制，然后调节STAT1 / STAT6信号传导和巨噬细胞极化。STAT6结合miR-34a的启动子以激活其转录。结论在巨噬细胞中，lncGBP9使miR-34a海绵能够拯救SOCS3表达，因此可通过STAT1 / STAT6信号调节巨噬细胞极化。STAT6结合miR-34a的启动子以激活其转录，从而形成两个不同的调节环来调节SCI后的巨噬细胞表型。进一步表明，lncGBP9沉默在SCI后继发性损伤的晚期改变了M1表型的优势，因此改善了SCI后的修复。IncGBP9与SOCS3竞争miR-34a结合，以抵消miR-34a介导的对SOCS3的抑制，然后调节STAT1 / STAT6信号传导和巨噬细胞极化。STAT6结合miR-34a的启动子以激活其转录。结论在巨噬细胞中，lncGBP9使miR-34a海绵能够拯救SOCS3表达，因此可通过STAT1 / STAT6信号调节巨噬细胞极化。STAT6结合miR-34a的启动子以激活其转录，从而形成两个不同的调节环来调节SCI后的巨噬细胞表型。进一步表明，lncGBP9沉默在SCI后继发性损伤的晚期改变了M1表型的优势，因此改善了SCI后的修复。IncGBP9与SOCS3竞争miR-34a结合，以抵消miR-34a介导的对SOCS3的抑制，然后调节STAT1 / STAT6信号传导和巨噬细胞极化。STAT6结合miR-34a的启动子以激活其转录。结论在巨噬细胞中，lncGBP9使miR-34a海绵能够拯救SOCS3表达，因此可通过STAT1 / STAT6信号调节巨噬细胞极化。STAT6结合miR-34a的启动子以激活其转录，从而形成两个不同的调节环来调节SCI后的巨噬细胞表型。