Chen Hao-Rong, Huang Huan-Shao, Zeng Si-Yi, Sun Yin-Fu, Chen Lan, Lai Shi-Ying, Wang Jia-Jun, Yang Fen, Pi Jiang, Cong Yan-Guang, Xu Jun-Fa
Dongguan Key Laboratory of Pathogenesis and Experimental Diagnosis of Infectious Diseases, Institute of Laboratory Medicine of School of Medical Technology, The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan 523710, China; Songshan Lake Innovation Center of Medicine & Engineering, Guangdong Medical University, Dongguan 523808, China.
Dongguan Key Laboratory of Pathogenesis and Experimental Diagnosis of Infectious Diseases, Institute of Laboratory Medicine of School of Medical Technology, The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan 523710, China.
Mol Immunol. 2025 Sep;185:105-115. doi: 10.1016/j.molimm.2025.07.012. Epub 2025 Jul 28.
Exosomes carry signaling molecules between cells and play important roles in the interaction between macrophages and Mycobacterium tuberculosis (Mtb). This study aimed to examine the function and content of exosomes secreted by macrophages infected with Bacillus Calmette-Guérin (BCG).
THP-1 monocytes and HEK293T cells were used. Macrophages were infected with BCG. A Transwell system was used to evaluate the effect of the exosomes secreted by macrophages. Cells were transfected with the miR-146a-5p plasmid or inhibitor to examine the effects of miR-146a-5p overexpression or inhibition. qRT-PCR was employed to investigate the expression levels of miR-320a-5p, miR-27a-5p, miR-26a-5p, miR-146a-5p, and miR-223-5p and the mRNA expression of IL-6, TNF-α, and IL-1β. Western blot was used to investigate the protein expression of IRAK1, TRAF6, CD63, CD81, GRP94, Alix, TSG101, P65, and p-P65. A dual luciferase assay was performed to investigate whether miR-146a-5p targets IRAK1 and TRAF6.
The infected cells contained high miR-146a-5p levels that could be secreted into exosomes. Exosomal miR-146a-5p promoted Mtb survival and proliferation after uptake by host cells. Bioinformatics showed that high miR-146a-5p levels were found in exosomes from BCG-infected macrophages and blood samples from patients with tuberculosis. The phagocytosis of exosomes containing miR-146a-5p by BCG-infected macrophages suppressed the expression of inflammatory factors by regulating the IRAK1-TRAF6-NF-κB signaling pathway, ultimately leading to the inhibition of inflammatory factor expression in macrophages and a decrease in the macrophage BCG killing capacity.
The findings indicate a new immune evasion mechanism of Mtb. miR-146a-5p secreted in exosomes by BCG-infected macrophages can decrease the bactericidal potential of macrophages. The results offer a novel theoretical basis and potential biomarkers for diagnosing, treating, and managing tuberculosis.
外泌体在细胞间传递信号分子，在巨噬细胞与结核分枝杆菌（Mtb）的相互作用中发挥重要作用。本研究旨在探讨卡介苗（BCG）感染的巨噬细胞分泌的外泌体的功能和内容物。
使用THP-1单核细胞和HEK293T细胞。巨噬细胞用BCG感染。采用Transwell系统评估巨噬细胞分泌的外泌体的作用。细胞用miR-146a-5p质粒或抑制剂转染，以检测miR-146a-5p过表达或抑制的效果。采用qRT-PCR研究miR-320a-5p、miR-27a-5p、miR-26a-5p、miR-146a-5p和miR-223-5p的表达水平以及IL-6、TNF-α和IL-1β的mRNA表达。采用蛋白质免疫印迹法研究IRAK1、TRAF6、CD63、CD81、GRP94、Alix、TSG101、P65和p-P65的蛋白表达。进行双荧光素酶测定以研究miR-146a-5p是否靶向IRAK1和TRAF6。
感染细胞中miR-146a-5p水平较高，可分泌到外泌体中。外泌体miR-146a-5p被宿主细胞摄取后促进Mtb存活和增殖。生物信息学显示，BCG感染的巨噬细胞的外泌体和结核病患者的血液样本中miR-146a-5p水平较高。BCG感染的巨噬细胞对含miR-146a-5p的外泌体的吞噬作用通过调节IRAK1-TRAF6-NF-κB信号通路抑制炎症因子的表达，最终导致巨噬细胞中炎症因子表达受到抑制，巨噬细胞对BCG的杀伤能力下降。
这些发现表明Mtb有新的免疫逃逸机制。BCG感染的巨噬细胞在外泌体中分泌的miR-146a-5p可降低巨噬细胞的杀菌潜力。这些结果为结核病的诊断、治疗和管理提供了新的理论基础和潜在的生物标志物。
