Yang Zhaogang, Wang Luowei, Yu Hongmei, Wang Ruonan, Gou Yawei, Zhang MingMing, Kang Chen, Liu Tongzheng, Lan Yu, Wang Xiaobing, Liu Jiwei, Cooper Merideth A, Li Xin, Yue Kai, Yu Yongli, Wang Liying, Kim Betty Y S, Jiang Wen, Sun Wei
Department of Molecular Biology, College of Basic Medical Sciences Jilin University, Changchun 130021, China.
Department of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Theranostics. 2019 Aug 14;9(21):6269-6283. doi: 10.7150/thno.37139. eCollection 2019.
Sepsis is a major cause of patient mortality and morbidity from bacterial infections. Although neutrophils are known to be important in the development of sepsis, how distinctive neutrophil subtypes regulate inflammatory processes involved in septicemia remains unclear. Preconditioning protects organisms against subsequent higher-dose exposures to the same, or even different, stimuli. Several studies have reported various effects of preconditioning on immune cells. However, the detailed mechanisms underlying neutrophil-mediated protection through preconditioning in sepsis remain unknown. : Flow cytometry was conducted to sort the mice peritoneal lavage cells and the blood samples from patients with sepsis. Western blotting and ELISA were carried out to elucidate the expression of TLR9 signal transduction pathway proteins. Histological analysis was used to assess the effect of InP on intestine and liver structure in and mice. Fluorescence microscopy, Co-IP, and FRET were carried out to determine the association of TLR9 with Cav-1. : We show that membrane toll-like receptor-9 positive (mTLR9) neutrophils exert a protective effect against fatal bacterial infections through the process of inflammatory preconditioning (InP). InP, which occurs in the setting of a low-dose bacterial challenge, active ingredient is Monophosphoryl lipid A (MPLA), triggers the membrane translocation of TLR9 from the neutrophil cytosol, where it binds to Cav-1. Our findings showed that InP enables TLR9 to facilitate MyD88-mediated TRAF3 and IRF3 signal transduction. Depletion of either TLR9 or Cav-1 largely eliminates the neutrophil-mediated InP effect in sepsis models and . Further, examination of clinical samples from patients with sepsis showed that clinical outcomes and likelihood of recovery are closely correlated with mTLR9 and Cav-1 expression in circulating neutrophils. : These results demonstrate that the TLR9-Cav-1 axis is a critical signaling pathway involved in the regulation of neutrophil-dependent MPLA mediated InP, and the presence of mTLR9 neutrophils could be an attractive indicator of clinical outcomes in bacterial sepsis that could be further explored as a potential therapeutic target.
脓毒症是细菌感染导致患者死亡和发病的主要原因。尽管已知中性粒细胞在脓毒症的发生发展中起重要作用，但独特的中性粒细胞亚群如何调节败血症相关的炎症过程仍不清楚。预处理可保护生物体免受随后更高剂量的相同或甚至不同刺激。几项研究报道了预处理对免疫细胞的各种影响。然而，脓毒症中通过预处理实现中性粒细胞介导的保护的详细机制仍不清楚。：通过流式细胞术对小鼠腹腔灌洗细胞和脓毒症患者的血样进行分选。采用蛋白质免疫印迹法和酶联免疫吸附测定法来阐明Toll样受体9（TLR9）信号转导通路蛋白的表达。组织学分析用于评估InP对野生型和Cav-1基因敲除小鼠肠道和肝脏结构的影响。采用荧光显微镜、免疫共沉淀和荧光能量共振转移技术来确定TLR9与小窝蛋白-1（Cav-1）的关联。：我们发现，膜型Toll样受体9阳性（mTLR9）中性粒细胞通过炎症预处理（InP）过程对致命细菌感染发挥保护作用。InP发生在低剂量细菌攻击的情况下，其活性成分是单磷酰脂质A（MPLA），可触发TLR9从嗜中性粒细胞胞质溶胶向膜的转位，在胞质溶胶中它与Cav-1结合。我们的研究结果表明，InP使TLR9能够促进髓样分化因子88（MyD88）介导的肿瘤坏死因子受体相关因子3（TRAF3）和干扰素调节因子3（IRF3）信号转导。在脓毒症模型中，TLR9或Cav-1的缺失在很大程度上消除了中性粒细胞介导的InP效应。此外，对脓毒症患者临床样本的检测表明，临床结局和恢复可能性与循环中性粒细胞中mTLR9和Cav-1的表达密切相关。：这些结果表明，TLR9-Cav-1轴是参与调节中性粒细胞依赖性MPLA介导的InP的关键信号通路，mTLR9中性粒细胞的存在可能是细菌性脓毒症临床结局的一个有吸引力的指标，可作为潜在治疗靶点进一步探索。
