Nakatsutsumi Keita, Choi Wooil, Johnston William, Pool Katie, Park Dong Jun, Weaver Jessica L, Coimbra Raul, Eliceiri Brian, Costantini Todd W
From the Division of Trauma, Surgical Critical Care, Burns and Acute Care Surgery, Department of Surgery (K.N., W.C., W.J., K.P., D.P., J.W., B.E., T.C.), UC San Diego School of Medicine, San Diego; Comparative Effectiveness and Clinical Outcomes Research Center (R.C.), Riverside University Health System, Loma Linda University School of Medicine, Riverside, California; and Trauma and Acute Critical Care Center (K.N.), Tokyo Medical and Dental University Hospital, Bunkyo-ku, Tokyo, Japan.
J Trauma Acute Care Surg. 2025 Jan 1;98(1):55-63. doi: 10.1097/TA.0000000000004499. Epub 2024 Nov 29.
Lung contusion (LC) complicated by pneumonia is associated with a higher risk of acute lung injury (ALI) mediated by activation of immune cells and injury to the lung epithelium. Small extracellular vesicles (sEVs) are essential mediators of cellular crosstalk; however, their role in the development of postinjury ALI remains unclear. We hypothesized that LC complicated by pneumonia increases the pro-inflammatory effect of alveolar sEVs on macrophages and the cytotoxicity of alveolar sEVs to pulmonary epithelial cells, worsening the severity of ALI.
Studies in C57BL/6 mice were designed with four groups: sham, LC, Pneumonia (Pneu), and LC + Pneu. Lung contusion was induced by a cortical controlled impactor, while pneumonia was conducted by intratracheal injection of 10 5 cfu Pseudomonas aeruginosa . Bronchoalveolar lavage fluid (BAL) was harvested 24 hours postinfection, and sEVs were purified by centrifugation and size exclusion chromatography. To evaluate the effect of alveolar sEV on cells, sEVs from each group were cocultured with macrophages (RAW 264.7) to assess cytokine release and lung epithelial cells (MLE 12) to assess epithelial cytotoxicity.
The LC + Pneu group severely injured lungs histologically and increased the susceptibility to the bacteria. The LC + Pneu group showed higher concentrations of proteins, macrophage inflammatory protein 1-alpha (MIP1α), and intercellular adhesion molecule 1 (ICAM-1) in BAL. MIP1α and ICAM-1 expression in the macrophages increased after incubation with sEVs from the LC + Pneu group. Moreover, the sEVs demonstrated higher cytotoxicity to epithelial cells and increased apoptosis in epithelial cells after incubation with sEVs from the LC + Pneu group.
Lung contusion complicated by pneumonia increased the pro-inflammatory effect of alveolar sEVs on macrophages and the cytotoxicity of alveolar sEVs to pulmonary epithelial cells, worsening the severity of ALI. These results demonstrate the potential importance of alveolar sEVs in lung inflammation following a bacterial infection after trauma.
肺挫伤（LC）合并肺炎与免疫细胞激活和肺上皮损伤介导的急性肺损伤（ALI）风险较高相关。小细胞外囊泡（sEVs）是细胞间通讯的重要介质；然而，它们在损伤后ALI发展中的作用仍不清楚。我们假设LC合并肺炎会增加肺泡sEVs对巨噬细胞的促炎作用以及肺泡sEVs对肺上皮细胞的细胞毒性，从而加重ALI的严重程度。
在C57BL/6小鼠中设计了四组研究：假手术组、LC组、肺炎（Pneu）组和LC + Pneu组。通过皮质控制撞击器诱导肺挫伤，同时通过气管内注射10⁵ cfu铜绿假单胞菌诱发肺炎。感染后24小时收集支气管肺泡灌洗液（BAL），并通过离心和尺寸排阻色谱法纯化sEVs。为了评估肺泡sEV对细胞的作用，将每组的sEVs与巨噬细胞（RAW 264.7）共培养以评估细胞因子释放，并与肺上皮细胞（MLE 12）共培养以评估上皮细胞毒性。
LC + Pneu组在组织学上肺损伤严重，并增加了对细菌的易感性。LC + Pneu组BAL中蛋白质、巨噬细胞炎性蛋白1-α（MIP1α）和细胞间黏附分子1（ICAM-1）的浓度较高。与LC + Pneu组的sEVs孵育后，巨噬细胞中MIP1α和ICAM-1的表达增加。此外，与LC + Pneu组的sEVs孵育后，sEVs对上皮细胞表现出更高的细胞毒性，并增加了上皮细胞的凋亡。
LC合并肺炎增加了肺泡sEVs对巨噬细胞的促炎作用以及肺泡sEVs对肺上皮细胞的细胞毒性，从而加重了ALI的严重程度。这些结果证明了肺泡sEVs在创伤后细菌感染后肺部炎症中的潜在重要性。
