iPSC 衍生 MSC 分泌的小细胞外囊泡通过递送 miR-125b-5p 减轻脓毒症引起的肺部炎症和肺损伤。

BACKGROUND: Sepsis-induced acute lung injury is a common critical illness in intensive care units with no effective treatment is currently available. Small extracellular vesicles, secreted by mesenchymal stem cells (MSCs), derived from human-induced pluripotent stem cells (iMSC-sEV), possess striking advantages when incorporated MSCs and iPSCs, which are considered extremely promising cell-free therapeutic agents. However, no studies have yet been conducted to systemically examine the effects and underlying mechanisms of iMSC-sEV application on attenuated lung injury under sepsis conditions. METHOD: iMSC-sEV were intraperitoneally administered in a rat septic lung injury model induced by cecal ligation and puncture (CLP). The efficacy of iMSC-sEV was assessed by histology, immunohistochemistry, and pro-inflammatory cytokines of bronchoalveolar lavage fluid. We also evaluated the in vitro effects of iMSC-sEV on the activation of the inflammatory response in alveolar macrophages (AMs). Small RNA sequencing was utilized to detect changes in the miRNA expression profile in lipopolysaccharide (LPS)-treated AMs after iMSC-sEV administration. The effects of miR-125b-5p on the function of AMs were studied. RESULTS: iMSC-sEV were able to attenuate pulmonary inflammation and lung injury following CLP-induced lung injury. iMSC-sEV were internalized by AMs and alleviated the release of inflammatory factors by inactivating the NF-B signaling pathway. Moreover, miR-125b-5p showed a fold-change in LPS-treated AMs after iMSC-sEV administration and was enriched in iMSC-sEV. Mechanistically, iMSC-sEV transmitted miR-125b-5p into LPS-treated AMs to target TRAF6. CONCLUSION: Our findings demonstrated that iMSC-sEV treatment protects against septic lung injury and exerts anti-inflammatory effects on AMs at least partially through miR-125b-5p, suggesting that iMSC-sEV may provide a novel cell-free strategy for the treatment of septic lung injury.

背景：脓毒症诱导的急性肺损伤是重症监护病房的一种常见危重病，目前尚无有效的治疗方法。源自人诱导多能干细胞（iPSC）的间充质干细胞（MSC）分泌的小细胞外囊泡（sEV），在整合 MSC 和 iPSC 时具有显著优势，被认为是极有前途的无细胞治疗剂。然而，目前尚无研究系统地检查 iMSC-sEV 在减轻脓毒症条件下肺损伤中的作用及其潜在机制。

方法：在盲肠结扎和穿刺（CLP）诱导的大鼠脓毒症肺损伤模型中，通过腹腔内给予 iMSC-sEV。通过组织学、免疫组织化学和支气管肺泡灌洗液中的促炎细胞因子评估 iMSC-sEV 的疗效。我们还评估了 iMSC-sEV 对肺泡巨噬细胞（AMs）炎症反应激活的体外作用。利用小 RNA 测序检测 LPS 处理的 AMs 在给予 iMSC-sEV 后 miRNA 表达谱的变化。研究了 miR-125b-5p 对 AM 功能的影响。

结果：iMSC-sEV 能够减轻 CLP 诱导的肺损伤后肺部炎症和肺损伤。iMSC-sEV 被 AMs 内化，并通过抑制 NF-B 信号通路减轻炎症因子的释放。此外，在给予 iMSC-sEV 后，LPS 处理的 AMs 中 miR-125b-5p 的倍数变化，并在 iMSC-sEV 中富集。在机制上，iMSC-sEV 将 miR-125b-5p 传递到 LPS 处理的 AMs 中，以靶向 TRAF6。

结论：我们的研究结果表明，iMSC-sEV 治疗可防止脓毒症肺损伤，并通过 miR-125b-5p 对 AMs 发挥抗炎作用，至少部分表明 iMSC-sEV 可能为脓毒症肺损伤的治疗提供一种新的无细胞策略。