State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing 210093, China.
State Key Laboratory of Trauma, Burns and Combined Injury, Research Institute of Surgery, Daping Hospital, The Army Medical University, Chongqing 400042, China.
Theranostics. 2022 Jan 1;12(2):675-688. doi: 10.7150/thno.64874. eCollection 2022.
Innate immune memory, also termed "trained immunity", is thought to protect against experimental models of infection, including sepsis. Trained immunity via reprogramming monocytes/macrophages has been reported to result in enhanced inflammatory status and antimicrobial activity against infection in sepsis. However, a safe and efficient way to induce trained immunity remains unclear. β-glucan is a prototypical agonist for inducing trained immunity. Ferumoxytol, superparamagnetic iron oxide (SPIO) with low cytotoxicity, has been approved by FDA for clinical use. We synthesized novel nanoparticles BSNPs by coupling β-glucan with SPIO. BSNPs were further conjugated with fluorescein for quantitative analysis and trace detection of β-glucan on BSNPs. Inflammatory cytokine levels were measured by ELISA and qRT-PCR, and the phagocytosis of macrophages was detected by flow cytometry and confocal microscopy. The therapeutic effect of BSNPs was evaluated on the well-established sepsis mouse model induced by both clinical () and cecal ligation and puncture (CLP). BSNPs were synthesized successfully with a 3:20 mass ratio of β-glucan and SPIO on BSNPs, which were mainly internalized by macrophages and accumulated in the lungs and livers of mice. BSNPs effectively reprogrammed macrophages to enhance the production of trained immunity markers and phagocytosis toward bacteria. BSNP-induced trained immunity protected mice against sepsis caused by and CLP and also against secondary infection. We found that BSNP treatment elevated Akt, S6, and 4EBP phosphorylation, while mTOR inhibitors decreased the trained immunity markers and phagocytosis enhanced by BSNPs. Furthermore, the PCR Array analysis revealed , , and as possible key regulators of mTOR signaling during trained immunity. BSNP-induced trained immunity mainly regulated cellular signal transduction, protein modification, and cell cycle by modulating ATP binding and the kinase activity. Our results indicated that BSNPs induced trained immunity in an mTOR-dependent manner. Our data highlight that the trained immunity of macrophages is an effective strategy against sepsis and suggest that BSNPs are a powerful tool for inducing trained immunity to prevent and treat sepsis and secondary infections.
固有免疫记忆，也称为“训练有素的免疫”，被认为可以预防感染的实验模型，包括败血症。已经报道，通过重编程单核细胞/巨噬细胞来产生训练有素的免疫会导致败血症中炎症状态增强和对抗感染的抗菌活性增强。然而，诱导训练有素的免疫的安全有效的方法仍不清楚。β-葡聚糖是诱导训练有素的免疫的典型激动剂。Ferumoxytol 是一种具有低细胞毒性的超顺磁性氧化铁 (SPIO)，已被 FDA 批准用于临床使用。我们通过将β-葡聚糖与 SPIO 偶联合成了新型纳米颗粒 BSNPs。BSNPs 进一步与荧光素缀合，用于定量分析和痕量检测 BSNPs 上的β-葡聚糖。通过 ELISA 和 qRT-PCR 测量炎症细胞因子水平，并通过流式细胞术和共聚焦显微镜检测巨噬细胞的吞噬作用。通过临床（）和盲肠结扎和穿刺（CLP）建立的成熟败血症小鼠模型评估 BSNPs 的治疗效果。BSNPs 成功合成，β-葡聚糖与 SPIO 的质量比为 3:20，主要被巨噬细胞内化，并在小鼠的肺部和肝脏中积累。BSNPs 有效地重编程巨噬细胞，增强了训练有素的免疫标志物的产生和对细菌的吞噬作用。BSNP 诱导的训练有素的免疫可保护小鼠免受由 和 CLP 引起的败血症以及继发感染。我们发现，BSNP 处理可提高 Akt、S6 和 4EBP 的磷酸化水平，而 mTOR 抑制剂可降低 BSNPs 增强的训练有素免疫标志物和吞噬作用。此外，PCR 阵列分析显示，在训练有素的免疫过程中， 、 、 和 可能是 mTOR 信号的关键调节剂。BSNP 诱导的训练有素的免疫主要通过调节 ATP 结合和激酶活性来调节细胞信号转导、蛋白质修饰和细胞周期。我们的结果表明，BSNPs 通过 mTOR 依赖性方式诱导巨噬细胞的训练有素免疫。我们的数据强调了巨噬细胞的训练有素免疫是对抗败血症的有效策略，并表明 BSNPs 是诱导训练有素免疫以预防和治疗败血症和继发感染的有力工具。
