Rationale The increased mortality and morbidity seen in critically injured patients appears associated with systemic inflammatory response syndrome (SIRS) and immune dysfunction, which ultimately predisposes to infection. Mitochondria released by injury could generate danger molecules, for example, ATP, which in turn would be rapidly scavenged by ectonucleotidases, expressed on regulatory immune cells. Objective To determine the association between circulating mitochondria, purinergic signalling and immune dysfunction after trauma. Methods We tested the impact of hepatocyte-derived free mitochondria on blood-derived and lung-derived CD8 T cells in vitro and in experimental mouse models in vivo. In parallel, immune phenotypic analyses were conducted on blood-derived CD8 T cells obtained from trauma patients. Results Isolated intact mitochondria are functional and generate ATP ex vivo. Extracellular mitochondria perturb CD8+ T cells in co-culture, inducing select features of immune exhaustion in vitro. These effects are modulated by scavenging ATP, modelled by addition of apyrase in vitro. Injection of intact mitochondria into recipient mice markedly upregulates the ectonucleotidase CD39, and other immune checkpoint markers in circulating CD8+ T cells. We note that mice injected with mitochondria, prior to instilling bacteria into the lung, exhibit more severe lung injury, characterised by elevated neutrophil influx and by changes in CD8+ T cell cytotoxic capacity. Importantly, the development of SIRS in injured humans, is likewise associated with disordered purinergic signalling and CD8 T cell dysfunction. Conclusion These studies in experimental models and in a cohort of trauma patients reveal important associations between extracellular mitochondria, aberrant purinergic signalling and immune dysfunction. These pathogenic factors with immune exhaustion are linked to SIRS and could be targeted therapeutically. All data relevant to the study are included in the article or uploaded as supplementary information.

中文翻译：

---

细胞外线粒体通过上调 CD39 驱动创伤中的 CD8 T 细胞功能障碍

基本原理 在重伤患者中观察到的死亡率和发病率增加似乎与全身炎症反应综合征 (SIRS) 和免疫功能障碍有关，最终导致感染。损伤释放的线粒体可能会产生危险分子，例如 ATP，而 ATP 又会被调节性免疫细胞上表达的外核苷酸酶迅速清除。目的 确定外伤后循环线粒体、嘌呤能信号和免疫功能障碍之间的关联。方法 我们在体外和体内实验小鼠模型中测试了肝细胞来源的游离线粒体对血液来源和肺来源的 CD8 T 细胞的影响。同时，对从创伤患者获得的血源性 CD8 T 细胞进行了免疫表型分析。结果 分离的完整线粒体具有功能并在体外产生 ATP。细胞外线粒体扰乱共培养的 CD8+ T 细胞，诱导体外免疫衰竭的特定特征。这些效应通过清除 ATP 进行调节，通过在体外添加 apyrase 进行建模。将完整的线粒体注射到受体小鼠体内可显着上调循环 CD8+ T 细胞中的外核苷酸酶 CD39 和其他免疫检查点标记物。我们注意到，在将细菌注入肺部之前注射线粒体的小鼠表现出更严重的肺损伤，其特征是中性粒细胞流入增加和 CD8+ T 细胞细胞毒性能力发生变化。重要的是，受伤人体中 SIRS 的发展同样与嘌呤能信号紊乱和 CD8 T 细胞功能障碍有关。结论 这些在实验模型和创伤患者队列中的研究揭示了细胞外线粒体、异常嘌呤能信号和免疫功能障碍之间的重要关联。这些具有免疫耗竭的致病因素与 SIRS 相关，可以作为治疗目标。所有与研究相关的数据都包含在文章中或作为补充信息上传。