Department of Immunology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China.
Department of Pharmaceutics, Zhuhai Campus of Zunyi Medical University, Zhuhai, China.
Inflamm Res. 2024 Feb;73(2):175-181. doi: 10.1007/s00011-023-01827-8. Epub 2023 Dec 13.
The study aimed to explore the immunomodulatory effects of clinically relevant concentrations of metformin on macrophages during sepsis, which is characterized by an initial hyperinflammatory phase followed by a period of immunosuppression. METHODS: We employed the RAW 264.7 mouse macrophage cell line as an in vitro model to induce inflammatory responses and immune suppression through primary and secondary stimulation by lipopolysaccharide (LPS). The cells were exposed to clinically relevant concentrations of metformin, and their responses were gauged through cytotoxicity assays, enzyme-linked immunosorbent assay for cytokine quantification, and assessments of intracellular reactive oxygen species (ROS) production. Moreover, to probe the role of AMPK in mediating the effects of metformin, we conducted an AMP-activated protein kinase (AMPK) activity assay and knocked down AMPK using siRNA. RESULTS: Our study revealed that clinically relevant concentrations of metformin considerably decreased the LPS-induced secretion of tumor necrosis factor-α and interleukin-6, which indicates the suppression of the initial hyperinflammatory response. Furthermore, metformin prevented LPS-induced immunosuppression. Notably, these immunomodulatory effects of metformin were not mediated by the activation of the AMPK pathway, as evidenced by the unaltered AMPK activity and siRNA experiments. The modulation of intracellular ROS levels emerged as the critical mechanism underlying the inhibition of hyperinflammation and impediment of immunosuppression by metformin.
A certain therapeutic dose of metformin inhibited hyperinflammatory responses and alleviated immunosuppression in LPS-induced macrophages through the bidirectional modulation of intracellular ROS generation.
本研究旨在探讨临床相关浓度的二甲双胍在脓毒症期间对巨噬细胞的免疫调节作用，脓毒症的特征是初始的过度炎症期，随后是免疫抑制期。
我们采用 RAW 264.7 小鼠巨噬细胞系作为体外模型，通过脂多糖（LPS）的初次和二次刺激来诱导炎症反应和免疫抑制。将细胞暴露于临床相关浓度的二甲双胍中，并通过细胞毒性测定、细胞因子定量酶联免疫吸附试验以及细胞内活性氧（ROS）产生的评估来测量其反应。此外，为了探究 AMPK 在介导二甲双胍作用中的作用，我们进行了 AMP 激活蛋白激酶（AMPK）活性测定，并使用 siRNA 敲低 AMPK。
我们的研究表明，临床相关浓度的二甲双胍可显著降低 LPS 诱导的肿瘤坏死因子-α和白细胞介素-6的分泌，这表明抑制了初始的过度炎症反应。此外，二甲双胍可预防 LPS 诱导的免疫抑制。值得注意的是，这些二甲双胍的免疫调节作用不是通过 AMPK 途径的激活介导的，这一点可以从 AMPK 活性和 siRNA 实验中未改变的 AMPK 活性得到证明。二甲双胍通过双向调节细胞内 ROS 的产生，成为抑制过度炎症和阻止 LPS 诱导的巨噬细胞免疫抑制的关键机制。
一定治疗剂量的二甲双胍通过双向调节细胞内 ROS 的产生，抑制 LPS 诱导的巨噬细胞过度炎症反应和缓解免疫抑制。
