Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, School of Medicine, Zhongda Hospital, Southeast University, Nanjing, 210009, China.
Department of Physiology, School of Medicine, Southeast University, Nanjing, 210009, China.
Cell Commun Signal. 2024 May 27;22(1):293. doi: 10.1186/s12964-024-01672-0.
Acute respiratory distress syndrome (ARDS) is a severe and fatal disease. Although mesenchymal stem cell (MSC)-based therapy has shown remarkable efficacy in treating ARDS in animal experiments, clinical outcomes have been unsatisfactory, which may be attributed to the influence of the lung microenvironment during MSC administration. Extracellular vesicles (EVs) derived from endothelial cells (EC-EVs) are important components of the lung microenvironment and play a crucial role in ARDS. However, the effect of EC-EVs on MSC therapy is still unclear. In this study, we established lipopolysaccharide (LPS) - induced acute lung injury model to evaluate the impact of EC-EVs on the reparative effects of bone marrow-derived MSC (BM-MSC) transplantation on lung injury and to unravel the underlying mechanisms.
EVs were isolated from bronchoalveolar lavage fluid of mice with LPS - induced acute lung injury and patients with ARDS using ultracentrifugation. and the changes of EC-EVs were analysed using nanoflow cytometry analysis. In vitro assays were performed to establish the impact of EC-EVs on MSC functions, including cell viability and migration, while in vivo studies were performed to validate the therapeutic effect of EC-EVs on MSCs. RNA-Seq analysis, small interfering RNA (siRNA), and a recombinant lentivirus were used to investigate the underlying mechanisms.
Compared with that in non-ARDS patients, the quantity of EC-EVs in the lung microenvironment was significantly greater in patients with ARDS. EVs derived from lipopolysaccharide-stimulated endothelial cells (LPS-EVs) significantly decreased the viability and migration of BM-MSCs. Furthermore, engrafting BM-MSCs pretreated with LPS-EVs promoted the release of inflammatory cytokines and increased pulmonary microvascular permeability, aggravating lung injury. Mechanistically, LPS-EVs reduced the expression level of isocitrate dehydrogenase 2 (IDH2), which catalyses the formation of α-ketoglutarate (α-KG), an intermediate product of the tricarboxylic acid (TCA) cycle, in BM-MSCs. α-KG is a cofactor for ten-eleven translocation (TET) enzymes, which catalyse DNA hydroxymethylation in BM-MSCs.
This study revealed that EC-EVs in the lung microenvironment during ARDS can affect the therapeutic efficacy of BM-MSCs through the IDH2/TET pathway, providing potential strategies for improving the therapeutic efficacy of MSC-based therapy in the clinic.
急性呼吸窘迫综合征（ARDS）是一种严重且致命的疾病。虽然间充质干细胞（MSC）为基础的治疗在动物实验中已显示出治疗 ARDS 的显著疗效，但临床结果并不令人满意，这可能归因于 MSC 给药期间肺微环境的影响。内皮细胞衍生的细胞外囊泡（EC-EVs）是肺微环境的重要组成部分，在 ARDS 中发挥着关键作用。然而，EC-EVs 对 MSC 治疗的影响尚不清楚。在这项研究中，我们建立了脂多糖（LPS）诱导的急性肺损伤模型，以评估 EC-EVs 对骨髓来源的 MSC（BM-MSC）移植治疗肺损伤的修复作用，并揭示其潜在机制。
使用超速离心法从 LPS 诱导的急性肺损伤小鼠和 ARDS 患者的支气管肺泡灌洗液中分离 EVs，并通过纳米流细胞术分析来分析 EC-EVs 的变化。进行体外实验以确定 EC-EVs 对 MSC 功能（包括细胞活力和迁移）的影响，同时进行体内研究以验证 EC-EVs 对 MSC 的治疗效果。使用 RNA-Seq 分析、小干扰 RNA（siRNA）和重组慢病毒来研究潜在机制。
与非 ARDS 患者相比，ARDS 患者肺微环境中的 EC-EVs 数量明显增加。来自脂多糖刺激的内皮细胞的 EVs（LPS-EVs）显著降低了 BM-MSCs 的活力和迁移。此外，植入用 LPS-EVs 预处理的 BM-MSCs 会促进炎性细胞因子的释放，并增加肺微血管通透性，从而加重肺损伤。机制上，LPS-EVs 降低了 BM-MSCs 中异柠檬酸脱氢酶 2（IDH2）的表达水平，IDH2 催化三羧酸（TCA）循环中间产物α-酮戊二酸（α-KG）的形成。α-KG 是 ten-eleven translocation（TET）酶的辅助因子，该酶在 BM-MSCs 中催化 DNA 羟甲基化。
本研究揭示了 ARDS 期间肺微环境中的 EC-EVs 可以通过 IDH2/TET 途径影响 BM-MSCs 的治疗效果，为改善 MSC 为基础的治疗在临床上的治疗效果提供了潜在策略。
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