Polymorphonuclear neutrophils (PMNs) play an important role in sepsis-related acute lung injury (ALI). Accumulating evidence suggests PMN-derived exosomes as a new subcellular entity acting as a fundamental link between PMN-driven inflammation and tissue damage. However, the role of PMN-derived exosomes in sepsis-related ALI and the underlying mechanisms remains unclear. Tumor necrosis factor-α (TNF-α), a key regulator of innate immunity in sepsis-related ALI, was used to stimulate PMNs from healthy C57BL/6J mice in vitro. Exosomes isolated from the supernatant were injected to C57BL/6J wild-type mice intraperitoneally (i.p.) and then examined for lung inflammation, macrophage (Mϕ) polarization and pyroptosis. In vitro co-culture system was applied where the mouse Raw264.7 macrophages or bone marrow-derived macrophages (BMDMs) were co-cultured with PMN-derived exosomes to further confirm the results of in vivo animal study and explore the potential mechanisms involved. Exosomes released by TNF-α-stimulated PMNs (TNF-Exo) promoted M1 macrophage activation after in vivo i.p. injection or in vitro co-culture. In addition, TNF-Exo primed macrophage for pyroptosis by upregulating NOD-like receptor 3 (NLRP3) inflammasome expression through nuclear factor κB (NF-κB) signaling pathway. Mechanistic studies demonstrated that miR-30d-5p mediated the function of TNF-Exo by targeting suppressor of cytokine signaling (SOCS-1) and sirtuin 1 (SIRT1) in macrophages. Furthermore, intravenous administration of miR-30d-5p inhibitors significantly decreased TNF-Exo or cecal ligation and puncture (CLP)-induced M1 macrophage activation and macrophage death in the lung, as well as the histological lesions. The present study demonstrated that exosomal miR-30d-5p from PMNs contributed to sepsis-related ALI by inducing M1 macrophage polarization and priming macrophage pyroptosis through activating NF-κB signaling. These findings suggest a novel mechanism of PMN-Mϕ interaction in sepsis-related ALI, which may provide new therapeutic strategies in sepsis patients.

中文翻译：

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中性粒细胞的外泌体 miR-30d-5p 在脓毒症相关的急性肺损伤中诱导 M1 巨噬细胞极化并引发巨噬细胞焦亡

多形核中性粒细胞 (PMN) 在败血症相关的急性肺损伤 (ALI) 中发挥重要作用。越来越多的证据表明，PMN 衍生的外泌体是一种新的亚细胞实体，是 PMN 驱动的炎症和组织损伤之间的基本联系。然而，PMN 衍生的外泌体在脓毒症相关 ALI 中的作用及其潜在机制尚不清楚。肿瘤坏死因子-α (TNF-α) 是败血症相关 ALI 中先天免疫的关键调节剂，用于体外刺激健康 C57BL/6J 小鼠的 PMN。从上清液中分离的外泌体被注射到 C57BL/6J 野生型小鼠腹腔内 (ip)，然后检查肺部炎症、巨噬细胞 (Mφ) 极化和细胞焦亡。体外共培养系统应用于小鼠 Raw264。将 7 种巨噬细胞或骨髓衍生巨噬细胞 (BMDM) 与 PMN 衍生的外泌体共培养，以进一步证实体内动物研究的结果并探索所涉及的潜在机制。体内 ip 注射或体外共培养后，TNF-α 刺激的 PMN（TNF-Exo）释放的外泌体促进 M1 巨噬细胞活化。此外，TNF-Exo 通过核因子 κB (NF-κB) 信号通路上调 NOD 样受体 3 (NLRP3) 炎性体表达，从而引发巨噬细胞焦亡。机制研究表明，miR-30d-5p 通过靶向巨噬细胞中的细胞因子信号抑制因子 (SOCS-1) 和沉默调节蛋白 1 (SIRT1) 来介导 TNF-Exo 的功能。此外，静脉注射 miR-30d-5p 抑制剂可显着降低 TNF-Exo 或盲肠结扎穿孔 (CLP) 诱导的肺中 M1 巨噬细胞活化和巨噬细胞死亡，以及组织学病变。本研究表明，来自 PMN 的外泌体 miR-30d-5p 通过激活 NF-κB 信号传导诱导 M1 巨噬细胞极化和引发巨噬细胞焦亡，从而导致败血症相关的 ALI。这些发现表明了脓毒症相关 ALI 中 PMN-Mφ 相互作用的新机制，这可能为脓毒症患者提供新的治疗策略。本研究表明，来自 PMN 的外泌体 miR-30d-5p 通过激活 NF-κB 信号传导诱导 M1 巨噬细胞极化和引发巨噬细胞焦亡，从而导致败血症相关的 ALI。这些发现表明了脓毒症相关 ALI 中 PMN-Mφ 相互作用的新机制，这可能为脓毒症患者提供新的治疗策略。本研究表明，来自 PMN 的外泌体 miR-30d-5p 通过激活 NF-κB 信号传导诱导 M1 巨噬细胞极化和引发巨噬细胞焦亡，从而导致败血症相关的 ALI。这些发现表明了脓毒症相关 ALI 中 PMN-Mφ 相互作用的新机制，这可能为脓毒症患者提供新的治疗策略。