Key Laboratory of Ministry of Education for TCM Viscera-State Theory and Applications, Liaoning University of Traditional Chinese Medicine, Shenyang, China.
Department of Medical Science of Laboratory, Liaoning University of Traditional Chinese Medicine, Shenyang, China.
Scand J Immunol. 2019 Jul;90(1):e12766. doi: 10.1111/sji.12766. Epub 2019 Apr 22.
Signal regulatory protein alpha (SIRPa) is an essential signalling molecule that modulates inflammatory responses in macrophages. However, the regulation of SIRPs and its dynamic changes in macrophages under inflammatory stimulation in atherosclerosis remain uncertain.
The study aimed to identify the miRNAs that regulate SIRPa transcription and their roles in modulating phagocytosis, differentiation and cholesterol efflux in macrophages.
ApoE knockout mice were fed with a high-fat diet for 12 weeks. Intimal lesion areas and lipid accumulation were assessed by haematoxylin and eosin (HE) and oil red O staining. The expression of mRNAs/miRNAs was assessed by RNA-seq (RNA sequencing) and RT-qPCR (real-time quantitative polymerase chain reaction). The identification of miR-378a associated with SIRPa regulation in macrophages induced by ox-LDL was confirmed by RT-qPCR and Western blot. The phagocytosis and differentiation of macrophages were detected to figure out the role of miR-378a and SIRPa.
SIRPa was proved to be a target of miR-378a. Reduced miR-378a can promote the expression of SIRPa. RNA-seq data showed that the levels of mRNA associated with macrophage phenotypes and SIRPa-CD47 axis were increasing significantly with a decreasing phagocytic phenotype in ApoE mice vs wild-type (WT) mice (P < 0.01). The level of miR-378a was reduced in the aorta of ApoE mice vs WT mice. The experiment in vitro showed that overexpression of miR-378a in macrophages decreased the level of Sirpa mRNA obviously vs control (P < 0.01). The phagocytic activity of miR-378a-transfected macrophages was promoted vs control (P < 0.05). miR-378a significantly depleted Sirpa levels in oxidized low-density lipoprotein (ox-LDL)-stimulated macrophages (P < 0.05), and depletion of miR-378a reversed Sirpa reduction obviously (P < 0.05). miR-378a promoted the secretion of TNF-a and IL-6 indirectly.
It has been demonstrated that miR-378a regulates SIRPa-mediated phagocytosis and polarization of macrophages by a direct or indirect way. This research may provide a new path to promote reverse cholesterol transport of macrophages and hinder the progress of atherosclerosis.
信号调节蛋白 alpha（SIRPa）是一种重要的信号分子，可调节巨噬细胞中的炎症反应。然而，在动脉粥样硬化中炎症刺激下 SIRP 的调节及其在巨噬细胞中的动态变化尚不确定。
本研究旨在鉴定调节 SIRPa 转录的 miRNAs 及其在调节巨噬细胞吞噬作用、分化和胆固醇流出中的作用。
apoE 基因敲除小鼠喂食高脂肪饮食 12 周。通过苏木精和伊红（HE）和油红 O 染色评估内膜病变面积和脂质积聚。通过 RNA-seq（RNA 测序）和 RT-qPCR（实时定量聚合酶链反应）评估 mRNA/miRNA 的表达。通过 RT-qPCR 和 Western blot 验证 ox-LDL 诱导的巨噬细胞中与 SIRPa 调节相关的 miR-378a 的鉴定。检测巨噬细胞的吞噬作用和分化，以确定 miR-378a 和 SIRPa 的作用。
SIRPa 被证明是 miR-378a 的靶标。减少 miR-378a 可促进 SIRPa 的表达。RNA-seq 数据显示，apoE 小鼠与野生型（WT）小鼠相比，与巨噬细胞表型和 SIRPa-CD47 轴相关的 mRNA 水平显著增加，吞噬表型减少（P<0.01）。apoE 小鼠主动脉中的 miR-378a 水平降低。体外实验表明，与对照相比，巨噬细胞中转染 miR-378a 明显降低 Sirpa mRNA 水平（P<0.01）。转染 miR-378a 的巨噬细胞的吞噬活性增强（P<0.05）。miR-378a 明显耗尽 ox-LDL 刺激的巨噬细胞中的 Sirpa 水平（P<0.05），而 miR-378a 的耗竭明显逆转 Sirpa 减少（P<0.05）。miR-378a 间接促进 TNF-a 和 IL-6 的分泌。
研究表明，miR-378a 通过直接或间接方式调节 SIRPa 介导的巨噬细胞吞噬作用和极化。这项研究可能为促进巨噬细胞的胆固醇逆向转运和阻止动脉粥样硬化的进展提供新的途径。
