Pharmaceutical Biology, Saarland University, Saarbrücken, Germany.
J Innate Immun. 2009;1(1):29-45. doi: 10.1159/000142731. Epub 2008 Jul 2.
Alveolar macrophages are the first line of host defence against mycobacteria, but an insufficient host response allows survival of bacteria within macrophages. We aimed to investigate the role of Toll-like receptor 9 (TLR9) activation in macrophage defence against mycobacteria. Human in vitro differentiated macrophages as well as human and mouse alveolar macrophages showed TLR9 mRNA and protein expression. The cells were markedly activated by DNA isolated from attenuated mycobacterial strains (H37Ra and Mycobacterium bovis BCG) as assessed by measuring cytokine expression by real-time PCR, whereas synthetic phosphorothioate-modified oligonucleotides had a much lower potency to activate human macrophages. Intracellular replication of H37Ra was higher in macrophages isolated from TLR9-deficient mice than in macrophages from wild-type mice, whereas H37Rv showed equal survival in cells from wild-type or mutant mice. Increased bacterial survival in mouse macrophages was accompanied by altered cytokine production as determined by Luminex bead assays. In vivo infection experiments also showed differential cytokine production in TLR9-deficient mice compared to wild-type animals. Both human monocyte-derived macrophages as well as human alveolar macrophages showed reduced activation upon treatment with DNA isolated from bacteria from virulent (M. bovis and H37Rv) compared to attenuated mycobacteria. We suggest attenuated TLR9 activation contributes to the insufficient host response against virulent mycobacteria.
肺泡巨噬细胞是宿主防御分枝杆菌的第一道防线，但宿主的应答不足会允许细菌在巨噬细胞内存活。我们旨在研究 Toll 样受体 9（TLR9）激活在巨噬细胞防御分枝杆菌中的作用。体外分化的人巨噬细胞以及人源和鼠源肺泡巨噬细胞均表达 TLR9 mRNA 和蛋白。通过实时 PCR 测量细胞因子表达来评估，细胞被来自减毒分枝杆菌株（H37Ra 和牛分枝杆菌 BCG）的 DNA 显著激活，而合成的硫代磷酸修饰寡核苷酸对人巨噬细胞的激活作用要低得多。与野生型小鼠的巨噬细胞相比，来自 TLR9 缺陷型小鼠的巨噬细胞中 H37Ra 的细胞内复制更高，而 H37Rv 在野生型或突变型小鼠的细胞中具有相同的存活率。在鼠巨噬细胞中，细菌的存活增加伴随着细胞因子产生的改变，通过 Luminex 珠分析确定。体内感染实验也显示 TLR9 缺陷型小鼠与野生型动物相比产生不同的细胞因子。人单核细胞衍生的巨噬细胞和人肺泡巨噬细胞在用来自毒力（牛分枝杆菌和 H37Rv）分枝杆菌的细菌分离物的 DNA 处理后显示出较低的激活作用，与减毒分枝杆菌相比。我们认为，减弱的 TLR9 激活有助于宿主对毒力分枝杆菌的应答不足。
