Neutrophil extracellular traps (NETs)-mediated tissue damage is a hallmark in abdominal sepsis. Under certain conditions, microRNAs (miRs) can regulate protein expression and cellular functions. The aim of this study was to investigate the role of miR-155 in sepsis-induced NET formation, lung inflammation, and tissue damage. Abdominal sepsis was induced in wild-type (WT) C57BL/6 and miR-155 gene-deficient mice by cecal ligation and puncture (CLP). The amount of DNA–histone complex formation as well as myeloperoxidase (MPO) and citrullinated histone 3 in neutrophils isolated from bone marrow were examined by ELISA and flow cytometry. NETs were detected by electron microscopy in the septic lung. Levels of PAD4 and citrullinated histone 3 were determined by Western blot in the blood neutrophils. Lung levels of MPO, CXC chemokines, and plasma levels of DNA–histone complexes and CXC chemokines were quantified. In vitro studies revealed that neutrophils from miR-155 gene-deficient mice had less NETs forming ability than WT neutrophils. In the miR-155 gene-deficient mice, CLP yielded much less NETs in the lung tissue compared with WT control. CLP-induced PAD4 levels, histone 3 citrullination, edema, MPO activity, and neutrophil recruitment in the lung were markedly reduced in the mice lacking miR-155. Furthermore, tissue and plasma levels of CXCL1 and CXCL2 were significantly lower in the miR-155 gene-deficient mice compared with WT after induction of abdominal sepsis. Taken together, our findings suggest that miR-155 regulates pulmonary formation of NETs in abdominal sepsis via PAD4 up-regulation and histone 3 citrullination. Thus, targeting miR-155 could be a useful target to reduce pulmonary damage in abdominal sepsis.

中文翻译：

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MiR-155 调节腹部脓毒症中性粒细胞胞外陷阱的形成和肺损伤

中性粒细胞胞外陷阱 (NETs) 介导的组织损伤是腹部脓毒症的标志。在某些条件下，microRNAs (miRs) 可以调节蛋白质表达和细胞功能。本研究的目的是研究 miR-155 在脓毒症诱导的 NET 形成、肺部炎症和组织损伤中的作用。通过盲肠结扎和穿刺 (CLP) 在野生型 (WT) C57BL/6 和 miR-155 基因缺陷小鼠中诱导腹部脓毒症。通过 ELISA 和流式细胞术检测从骨髓分离的嗜中性粒细胞中 DNA-组蛋白复合物的形成量以及髓过氧化物酶 (MPO) 和瓜氨酸组蛋白 3。通过电子显微镜在脓毒性肺中检测到 NET。通过蛋白质印迹测定血液中性粒细胞中 PAD4 和瓜氨酸化组蛋白 3 的水平。MPO、CXC 趋化因子的肺水平，对 DNA-组蛋白复合物和 CXC 趋化因子的血浆水平进行定量。体外研究表明，来自 miR-155 基因缺陷小鼠的中性粒细胞的 NETs 形成能力低于 WT 中性粒细胞。在 miR-155 基因缺陷小鼠中，与 WT 对照相比，CLP 在肺组织中产生的 NET 少得多。在缺乏 miR-155 的小鼠中，CLP 诱导的 PAD4 水平、组蛋白 3 瓜氨酸化、水肿、MPO 活性和肺中的中性粒细胞募集显着降低。此外，在诱导腹部脓毒症后，与 WT 相比，miR-155 基因缺陷小鼠的组织和血浆中 CXCL1 和 CXCL2 水平显着降低。总之，我们的研究结果表明 miR-155 通过 PAD4 上调和组蛋白 3 瓜氨酸化来调节腹部脓毒症中 NET 的肺部形成。因此，