Department of Tuberculosis, Shanghai Pulmonary Hospital, Shanghai, China.
Eur Rev Med Pharmacol Sci. 2019 Sep;23(18):8028-8038. doi: 10.26355/eurrev_201909_19019.
Tuberculosis (TB), a major public health problem worldwide, is induced by Mycobacterium tuberculosis (M.tb) infection. Macrophages serve as the cellular home in immunoreaction against M.tb infection, which is tightly adjusted by host microRNAs (miRNAs) expression. The purpose of this research was to investigate the function mechanism of miR-708-5p in mycobacterial vitality and immunoreaction in human macrophages (HTP-1 and U937 cells) after M.tb infection.
Colony-forming unit (CFU) assay was used to measure mycobacterial survival. The interferon-γ (IFN-γ), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) expression in cell supernatants were detected by enzyme-linked immunosorbent assay (ELISA). The relationship between miR-708-5p and toll-like receptor 4 (TLR4) was predicted and revealed by TargetScan and Dual-Luciferase Reporter Assay.
Our results suggested that the miR-708-5p level was increased in a concentration-dependent and time-dependent manner in M.tb-infected human macrophages. Compared with the control group, miR-708-5p mimic enhanced the intracellular mycobacterial survival during M.tb infection, while miR-708-5p downregulation suppressed the mycobacteria survival. Moreover, the secretion of the pro-inflammatory factors, including IFN-γ, IL-6, IL-1β, and TNF-α significantly enhanced in M.tb-induced macrophages, while miR-708-5p mimic reduced these inflammatory cytokines. Conversely, miR-708-5p inhibitor dramatically promoted the accumulation of the inflammatory factors in macrophages after M.tb treatment. In addition, evidence indicated that TLR4 was a direct and functional target of miR-708-5p. MiR-708-5p negatively regulated the TLR4 level in macrophages.
The findings indicated that miR-708-5p level was upregulated in macrophages after M.tb infection. And miR-708-5p could regulate mycobacterial vitality and inflammatory response to M.tb infection in human macrophages by targeting TLR4.
结核病（TB）是全球主要的公共卫生问题，由结核分枝杆菌（M.tb）感染引起。巨噬细胞作为针对 M.tb 感染的细胞内固有免疫反应的场所，其功能受到宿主 microRNAs（miRNAs）表达的严格调控。本研究旨在探讨 miR-708-5p 在人巨噬细胞（HTP-1 和 U937 细胞）感染 M.tb 后对分枝杆菌活力和免疫反应的作用机制。
采用集落形成单位（CFU）测定法检测分枝杆菌的存活情况。酶联免疫吸附试验（ELISA）检测细胞上清液中干扰素-γ（IFN-γ）、白细胞介素-6（IL-6）、白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）的表达。通过 TargetScan 和双荧光素酶报告基因检测预测并揭示 miR-708-5p 与 Toll 样受体 4（TLR4）之间的关系。
研究结果表明，M.tb 感染人巨噬细胞后，miR-708-5p 的水平呈浓度和时间依赖性增加。与对照组相比，miR-708-5p 模拟物增强了 M.tb 感染期间细胞内分枝杆菌的存活，而 miR-708-5p 下调抑制了分枝杆菌的存活。此外，M.tb 诱导的巨噬细胞中促炎因子 IFN-γ、IL-6、IL-1β 和 TNF-α 的分泌显著增强，而 miR-708-5p 模拟物则降低了这些炎症细胞因子。相反，miR-708-5p 抑制剂在 M.tb 处理后显著促进了巨噬细胞中炎症因子的积累。此外，有证据表明 TLR4 是 miR-708-5p 的直接和功能靶标。miR-708-5p 在巨噬细胞中负调控 TLR4 水平。
研究结果表明，M.tb 感染后巨噬细胞中 miR-708-5p 水平上调。miR-708-5p 可以通过靶向 TLR4 调节人巨噬细胞中分枝杆菌活力和对 M.tb 感染的炎症反应。
