Department of Geriatrics, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Xuhui District, Shanghai 200032, China.
Department of Respiratory, Shanghai Pulmonary Hospital, Tongji University, No. 507 Zhengmin Road, Yangpu District, Shanghai 200433, China.
Int Immunopharmacol. 2022 Jun;107:108690. doi: 10.1016/j.intimp.2022.108690. Epub 2022 Mar 14.
Alveolar macrophages (AMs) play a demonstrative role in acute lung injury (ALI). Exosomes act as signaling molecules to regulate cell-to-cell communication by releasing RNAs. Transfer RNA-derived fragments (tRFs) possess potential functions in multiple diseases through ferroptosis. The present study aims to reveal the role of AM-derived exosomal tRFs in ALI and to identify the relationship to ferroptosis.
ALI mice model was established by lipopolysaccharide (LPS) induction. RNA sequencing was performed to identify the tRFs profile in bronchoalveolar lavage fluid (BALF) exosomes of ALI mice. After interfering with the expression of candidate tRFs in AMs or alveolar epithelial cells (MLE-12), the effect of oxidative stress and expression of ferroptosis-related proteins were detected.
Exosomes isolated from BALF of ALI mice were dominated by a macrophage immunophenotype. RNA-sequencing identified 4 up- and 10 down-regulated differentially expressed tRFs (DEtRFs), among which tRF-22-8BWS7K092 expression was significantly increased in LPS-induced macrophage-derived exosomes (LPS-exo). Hippo signaling pathway was the most significantly enriched KEGG pathways for DEtRFs. LPS-exo inhibited cell viability and the expression of GPX4 and FTH1, and enhanced oxidative stress in MLE-12 cells. Ferroptosis inhibitor reversed the inhibition of LPS-exo on cell viability and tRF-22-8BWS7K092 inhibitor rescued above effect of LPS-exo on MLE-12 cells. Besides, tRF-22-8BWS7K092 could activate Hippo signaling pathway by binding Wnt5B, inducing ferroptosis in MLE-12 cells.
BALF exosomes of ALI mice were mainly derived from AMs. AM-derived exosomal tRF-22-8BWS7K092 activates the Hippo signaling pathway to induce ferroptosis, thus contributing to the pathogenesis of ALI.
肺泡巨噬细胞（AMs）在急性肺损伤（ALI）中发挥着显著作用。外泌体作为信号分子，通过释放 RNA 来调节细胞间通讯。转移 RNA 衍生的片段（tRFs）通过铁死亡在多种疾病中具有潜在功能。本研究旨在揭示 AM 来源的外泌体 tRFs 在 ALI 中的作用，并确定与铁死亡的关系。
通过脂多糖（LPS）诱导建立 ALI 小鼠模型。对 ALI 小鼠支气管肺泡灌洗液（BALF）外泌体中的 tRFs 谱进行 RNA 测序。在 AM 或肺泡上皮细胞（MLE-12）中干扰候选 tRFs 的表达后，检测氧化应激和铁死亡相关蛋白的表达。
从 ALI 小鼠 BALF 中分离的外泌体以巨噬细胞免疫表型为主。RNA 测序鉴定出 4 个上调和 10 个下调的差异表达 tRFs（DEtRFs），其中 LPS 诱导的巨噬细胞来源外泌体（LPS-exo）中 tRF-22-8BWS7K092 的表达显著增加。DEtRFs 最显著的富集 KEGG 通路是 Hippo 信号通路。LPS-exo 抑制 MLE-12 细胞活力和 GPX4、FTH1 的表达，并增强细胞内氧化应激。铁死亡抑制剂逆转了 LPS-exo 对 MLE-12 细胞活力的抑制作用，tRF-22-8BWS7K092 抑制剂挽救了 LPS-exo 对 MLE-12 细胞的上述作用。此外，tRF-22-8BWS7K092 通过与 Wnt5B 结合激活 Hippo 信号通路，诱导 MLE-12 细胞发生铁死亡。
ALI 小鼠 BALF 外泌体主要来源于 AM。AM 来源的外泌体 tRF-22-8BWS7K092 激活 Hippo 信号通路诱导铁死亡，从而促进 ALI 的发病机制。
