Table 1_circ-0001875 downregulation is associated with M1 macrophage activation and lung inflammation in severe asthma.docx

BackgroundAsthma is a heterogeneous group of diseases. The mechanism by which dysregulated circRNAs affect severe asthma by regulating macrophage polarization remains unclear.
MethodsHigh-throughput RNA sequencing technology was used to analyze circRNA expression in peripheral blood mononuclear cells (PBMCs) from patients with severe asthma. RT-qPCR and ELISA were used to analyze the expression of inflammatory factors in a mouse model of severe asthma induced by ovalbumin-lipopolysaccharide. The effect of circ-0001875 on macrophage activation and the underlying mechanism were analyzed by RT-qPCR, Western blot, and ELISA. Subsequently, the regulatory relationships among circ-0001875, miR-31-5p, and SP1 were examined through dual luciferase reporter gene assay, and the mechanism by which they regulate macrophage polarization was analyzed by Western blot.
ResultsCompared with the healthy control group, 420 circRNAs were differentially expressed in PBMCs from patients with severe asthma. Among them, circ-0001875, which was mainly expressed in the cytoplasm of monocytes, was significantly downregulated in asthmatics, especially those with severe disease. circ-0001875 overexpression inhibited M1 macrophage activation in vitro and alleviated lung inflammation in a mouse model of severe asthma. Mechanistically, circ-0001875 promoted SP1 translation by competitively binding to miR-31-5p, thereby reducing its inhibitory effect on SP1 translation; SP1 then inhibited M1 macrophage polarization, which is associated with severe asthma, through the NF-κB signaling pathway.
ConclusionsWe found that circ-0001875 plays an important role in regulating M1 macrophage polarization, which is associated with a severe pro-inflammatory response.

背景
哮喘是一组异质性疾病。失调的环状RNA（circRNA）通过调控巨噬细胞极化影响重症哮喘的具体机制仍不明确。

方法
本研究采用高通量RNA测序技术，分析重症哮喘患者外周血单个核细胞（PBMCs）中的环状RNA表达情况；采用实时定量聚合酶链反应（RT-qPCR）与酶联免疫吸附测定（ELISA），分析卵清蛋白-脂多糖诱导的重症哮喘小鼠模型的炎症因子表达水平；通过RT-qPCR、蛋白质印迹法（Western blot）及ELISA，分析circ-0001875对巨噬细胞活化的影响及其潜在机制。随后通过双荧光素酶报告基因实验，检测circ-0001875、miR-31-5p与SP1之间的调控关系，并通过Western blot分析三者调控巨噬细胞极化的具体机制。

结果
与健康对照组相比，重症哮喘患者PBMCs中共有420个环状RNA存在差异表达。其中，主要在单核细胞胞质中表达的circ-0001875在哮喘患者，尤其是重症哮喘患者体内显著下调。体外实验证实，circ-0001875过表达可抑制M1型巨噬细胞活化，并缓解重症哮喘小鼠模型的肺部炎症。机制研究显示，circ-0001875通过竞争性结合miR-31-5p，促进SP1的翻译，从而削弱miR-31-5p对SP1翻译的抑制作用；随后SP1通过核因子κB（NF-κB）信号通路，抑制与重症哮喘相关的M1型巨噬细胞极化。

结论
本研究发现，circ-0001875在调控M1型巨噬细胞极化中发挥重要作用，该过程与重症促炎反应密切相关。