Background. Recently, identification of immunosuppressive polymorphonuclear leukocytes (PMNL) that were traditionally described as proinflammatory cells emerged in the field of posttraumatic immunity. To understand their local and remote distribution after trauma, PMNL-subsets and the impact of immunomodulatory Club Cell protein (CC)16 that correlates with pulmonary complications were assessed. Methods. C57BL/6N mice were divided into three groups, receiving isolated blunt chest trauma (TxT), undergoing TxT followed by cecal ligation and puncture (CLP, ) after 24 h, or sham undergoing analgosedation (/group). Further, each group was subdivided into three groups receiving either no treatment (ctrl) or intratracheal neutralization of CC16 by application of anti-CC16-antibody or application of an unspecific IgG control antibody (/group). Treatment was set at the time point after TxT. Analyses followed 6 h post-CLP. PMNL were characterized via expression of CD11b, CD16, CD45, CD62L, and Ly6G by flow cytometry in bone marrow (BM), blood, spleen, lung, liver, and bronchoalveolar and peritoneal lavage fluid (BALF and PL). Apoptosis was assessed by activated (cleaved) caspase-3. Results from untreated ctrl and IgG-treated mice were statistically comparable between all corresponding sham, TxT, and groups. Results. Immature (CD16^dimCD62L^bright) PMNL increased significantly in BM, circulation, and spleen after TxT vs. sham and were significantly attenuated in the lungs, BALF, PL, and liver. Classical-shaped (CD16^brightCD62L^bright) PMNL increased after TxT vs. sham in peripheral tissue and were significantly attenuated in circulation, proposing a trauma-induced migration of mature or peripheral differentiation of circulating immature PMNL. Immunosuppressive (CD16^brightCD62L^dim) PMNL decreased significantly in the lungs and spleen, while they systemically increased after TxT vs. sham. CLP in the group reduced immunosuppressive PMNL in PL and increased their circulatory rate vs. isolated TxT, showing local reduction in affected tissue and their increase in nonaffected tissue. CC16 neutralization enhanced the fraction of immunosuppressive PMNL following TxT vs. sham and decreased caspase-3 in the lungs post-CLP in the group, while apoptotic cells in the liver diminished post-TxT. Posttraumatic CC16 neutralization promotes the subset of immunosuppressive PMNL and antagonizes their posttraumatic distribution. Conclusion. Since CC16 affects both the distribution of PMNL subsets and apoptosis in tissues after trauma, it may constitute as a novel target to beneficially shape the posttraumatic tissue microenvironment and homeostasis to improving outcomes.

中文翻译：

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俱乐部细胞蛋白 16 在创伤后脓毒症引起的肺损伤时减弱受损组织中的 CD16brightCD62dim 免疫抑制性中性粒细胞

背景。最近，在创伤后免疫领域出现了对传统上被描述为促炎细胞的免疫抑制性多形核白细胞 (PMNL) 的鉴定。为了了解它们在创伤后的局部和远程分布，评估了 PMNL 子集和与肺部并发症相关的免疫调节性俱乐部细胞蛋白 (CC)16 的影响。方法。C57BL/6N 小鼠分为三组，分别接受孤立的钝性胸部创伤（TxT）、接受 TxT 后盲肠结扎和穿刺（CLP、) 24 小时后，或进行镇痛的假手术 (/团体）。此外，每组被细分为三组，接受不治疗 (ctrl) 或通过应用抗 CC16 抗体或应用非特异性 IgG 对照抗体对 CC16 进行气管内中和。/团体）。在 TxT 之后的时间点进行治疗。在 CLP 后 6 小时进行分析。PMNL 通过流式细胞仪在骨髓 (BM)、血液、脾脏、肺、肝脏、支气管肺泡和腹腔灌洗液 (BALF 和 PL) 中表达 CD11b、CD16、CD45、CD62L 和 Ly6G 进行表征。通过活化（切割）的 caspase-3 评估细胞凋亡。未经处理的 ctrl 和 IgG 处理的小鼠的结果在所有相应的假、TxT 和团体。结果。在TxT与. ^_ _ ^_ 假手术在肺、BALF、PL 和肝脏中显着减弱。经典型（CD16^亮CD62L^亮）PMNL 在 TxT与. 假在外周组织中，并且在循环中显着减弱，提出了创伤诱导的循环未成熟 PMNL 成熟或外周分化的迁移。免疫抑制（CD16 ^bright CD62L ^dim）PMNL 在肺和脾脏中显着降低，而在 TxT与. 假。中电在组减少了 PL 中的免疫抑制 PMNL 并增加了他们的循环率。分离的 TxT，显示受影响组织的局部减少和非受影响组织的增加。CC16 中和增强了 TxT与. 假手术和 CLP 后肺中的 caspase-3 减少组，而肝脏中的凋亡细胞在 TxT 后减少。创伤后 CC16 中和促进免疫抑制性 PMNL 的子集并拮抗其创伤后分布。结论。由于 CC16 影响 PMNL 亚群的分布和创伤后组织中的细胞凋亡，它可能构成一个新的靶点，有利于塑造创伤后组织微环境和稳态以改善结果。