PDF(Pubmed)
Abstract：
Primary graft dysfunction (PGD) is a severe form of acute lung injury resulting from lung ischemia/reperfusion injury (I/R) in lung transplantation (LTx), associated with elevated post-transplant morbidity and mortality rates. Neutrophils infiltrating during reperfusion are identified as pivotal contributors to lung I/R injury by releasing excessive neutrophil extracellular traps (NETs) via NETosis. While alveolar macrophages (AMs) are involved in regulating neutrophil chemotaxis and infiltration, their role in NETosis during lung I/R remains inadequately elucidated. Extracellular histones constitute the main structure of NETs and can activate AMs. In this study, we confirmed the significant involvement of extracellular histone-induced M1 phenotype of AMs (M1-AMs) in driving NETosis during lung I/R. Using secretome analysis, public protein databases, and transwell co-culture models of AMs and neutrophils, we identified Cathepsin C (CTSC) derived from AMs as a major mediator in NETosis. Further elucidating the molecular mechanisms, we found that CTSC induced NETosis through a pathway dependent on NADPH oxidase-mediated production of reactive oxygen species (ROS). CTSC could significantly activate p38 MAPK, resulting in the phosphorylation of the NADPH oxidase subunit p47phox, thereby facilitating the trafficking of cytoplasmic subunits to the cell membrane and activating NADPH oxidase. Moreover, CTSC up-regulated and activated its substrate membrane proteinase 3 (mPR3), resulting in an increased release of NETosis-related inflammatory factors. Inhibiting CTSC revealed great potential in mitigating NETosis-related injury during lung I/R. These findings suggests that CTSC from AMs may be a crucial factor in mediating NETosis during lung I/R, and targeting CTSC inhition may represent a novel intervention for PGD in LTx.
摘要：
原发性移植物功能障碍（PGD）是肺移植（LTx）中由肺缺血/再灌注损伤（I/R）引起的严重急性肺损伤，与移植后发病率和死亡率升高有关。通过NETosis释放过多的中性粒细胞胞外陷阱（NETs），在再灌注过程中浸润的中性粒细胞被确定为肺I/R损伤的关键贡献者。而肺泡巨噬细胞（AM）参与调节中性粒细胞趋化和浸润，它们在肺I/R期间NETosis中的作用仍未充分阐明。细胞外组蛋白构成了NETs的主要结构并能激活AMs。我们证实了肺I/R期间细胞外组蛋白诱导的AMsM1表型（M1-AMs）在驱动NETosis中的显着参与。使用分泌组分析，公共蛋白质数据库，以及AM和中性粒细胞的transwell共培养模型，我们确定源自AMs的组织蛋白酶C（CTSC）是NETosis的主要介质。进一步阐明分子机制，我们发现CTSC通过依赖于NADPH氧化酶介导的活性氧（ROS）产生的途径诱导NETosis。CTSC能显著激活p38MAPK,导致NADPH氧化酶亚基p47phox的磷酸化，从而促进细胞质亚基向细胞膜的运输并激活NADPH氧化酶。此外，CTSC上调并激活其底物膜蛋白酶3（mPR3），导致NETosis相关炎症因子的释放增加。抑制CTSC显示出减轻肺I/R期间NETosis相关损伤的巨大潜力。这些发现表明，来自AM的CTSC可能是介导肺I/R期间NETosis的关键因素，靶向CTSC抑制可能是LTx中PGD的一种新型干预措施。
