Zhang Zhi-Min, Zhang Ai-Rong, Xu Min, Lou Jun, Qiu Wei-Qiang
Department of Clinical Laboratory, the Central Hospital of Zhumadian, Zhumadian, Henan 463000, PR China.
Department of Clinical Laboratory, the Central Hospital of Zhumadian, Zhumadian, Henan 463000, PR China.
Exp Cell Res. 2017 Mar 15;352(2):313-321. doi: 10.1016/j.yexcr.2017.02.025. Epub 2017 Feb 16.
Macrophages play a pivotal role in host immune response against mycobacterial infection, which is tightly modulated by multiple factors, including microRNAs. The purpose of the present study was to investigate the biological function and potential mechanism of miR-32-5p in human macrophages during Mycobacterium tuberculosis (M.tb) infection. The results demonstrated that miR-32-5p was robustly enhanced in THP-1 and U937 cells in response to M.tb infection. TLR-4 signaling was required for upregulation of miR-32-5p induced by M.tb infection. Additionally, the introduction of miR-32-5p strongly increased the survival rate of intracellular mycobacteria, whereas inhibition of miR-32-5p suppressed intracellular growth of mycobacteria during M.tb challenged. Furthermore, forced expression of miR-32-5p dramatically attenuated the accumulation of inflammatory cytokines IL-1β, IL-6 and TNF-α induced by M.tb infection. Conversely, downregulated expression of miR-32-5p led to enhancement in these inflammatory cytokines. More importantly, our study explored that Follistatin-like protein 1 (FSTL1) was a direct and functional target of miR-32-5p. qRT-PCR and western blot analysis further validated that miR-32-5p negatively regulated the expression of FSTL1. Mechanistically, re-expression of FSTL1 attenuated the ability of miR-32-5p to promote mycobacterial survival. Meanwhile, miR-32-5p-mediated inhibition of the inflammatory cytokine production were completely reversed by overexpression of FSTL1. Collectively, our findings demonstrated a novel role of TLR-4/miRNA-32-5p/FSTL1 in the modulation of host defense against mycobacterial infection, which may provide a better understanding of the pathogenesis of tuberculosis and useful information for developing potential therapeutic interventions against the disease.
巨噬细胞在宿主针对分枝杆菌感染的免疫反应中起关键作用，其受到多种因素（包括微小RNA）的严格调控。本研究的目的是探讨miR-32-5p在结核分枝杆菌（M.tb）感染期间人巨噬细胞中的生物学功能及潜在机制。结果表明，M.tb感染可使THP-1和U937细胞中的miR-32-5p显著上调。M.tb感染诱导的miR-32-5p上调需要TLR-4信号传导。此外，引入miR-32-5p可显著提高细胞内分枝杆菌的存活率，而抑制miR-32-5p则可在M.tb攻击期间抑制分枝杆菌的细胞内生长。此外，强制表达miR-32-5p可显著减弱M.tb感染诱导的炎性细胞因子IL-1β、IL-6和TNF-α的积累。相反，miR-32-5p表达下调导致这些炎性细胞因子增加。更重要的是，我们的研究发现卵泡抑素样蛋白1（FSTL1）是miR-32-5p的直接功能性靶标。qRT-PCR和蛋白质印迹分析进一步证实miR-32-5p负向调节FSTL1的表达。机制上，FSTL1的重新表达减弱了miR-32-5p促进分枝杆菌存活的能力。同时，FSTL1的过表达完全逆转了miR-32-5p介导的炎性细胞因子产生的抑制作用。总体而言，我们的研究结果证明了TLR-4/miRNA-32-5p/FSTL1在调节宿主抗分枝杆菌感染防御中的新作用，这可能有助于更好地理解结核病的发病机制，并为开发针对该疾病的潜在治疗干预措施提供有用信息。
