Department of Pathology and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju, South Korea.
Infect Immun. 2014 May;82(5):1914-20. doi: 10.1128/IAI.01226-13. Epub 2014 Feb 24.
Toll-like receptors (TLRs) orchestrate a repertoire of immune responses in macrophages against various pathogens. Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans are two important periodontal pathogens. In the present study, we investigated TLR signaling regulating cytokine production of macrophages in response to F. nucleatum and A. actinomycetemcomitans. TLR2 and TLR4 are redundant in the production of cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNF-α]) in F. nucleatum- and A. actinomycetemcomitans-infected macrophages. The production of cytokines by macrophages in response to F. nucleatum and A. actinomycetemcomitans infection was impaired in MyD88-deficient macrophages. Moreover, cytokine concentrations were lower in MyD88-deficient macrophages than in TLR2/TLR4 (TLR2/4) double-deficient cells. An endosomal TLR inhibitor, chloroquine, reduced cytokine production in TLR2/4-deficient macrophages in response to F. nucleatum and A. actinomycetemcomitans, and DNA from F. nucleatum or A. actinomycetemcomitans induced IL-6 production in bone marrow-derived macrophages (BMDMs), which was abolished by chloroquine. Western blot analysis revealed that TLR2/4 and MyD88 were required for optimal activation of NF-κB and mitogen-activated protein kinases (MAPKs) in macrophages in response to F. nucleatum and A. actinomycetemcomitans, with different kinetics. An inhibitor assay showed that NF-κB and all MAPKs (p38, extracellular signal-regulated kinase [ERK], and Jun N-terminal protein kinase [JNK]) mediate F. nucleatum-induced production of cytokines in macrophages, whereas NF-κB and p38, but not ERK and JNK, are involved in A. actinomycetemcomitans-mediated cytokine production. These findings suggest that multiple TLRs may participate in the cytokine production of macrophages against periodontal bacteria.
Toll 样受体 (TLR) 协调巨噬细胞针对各种病原体的免疫反应谱。具核梭杆菌和伴放线放线杆菌是两种重要的牙周病原体。在本研究中，我们研究了 TLR 信号通路调节巨噬细胞对具核梭杆菌和伴放线放线杆菌的细胞因子产生。TLR2 和 TLR4 在具核梭杆菌和伴放线放线杆菌感染的巨噬细胞中细胞因子（白细胞介素 6 [IL-6]和肿瘤坏死因子-α [TNF-α]）的产生中是冗余的。MyD88 缺陷型巨噬细胞中，对具核梭杆菌和伴放线放线杆菌感染的巨噬细胞产生细胞因子的能力受损。此外，MyD88 缺陷型巨噬细胞中的细胞因子浓度低于 TLR2/TLR4（TLR2/4）双缺陷细胞。内体 TLR 抑制剂氯喹可降低 TLR2/4 缺陷型巨噬细胞对具核梭杆菌和伴放线放线杆菌的细胞因子产生，具核梭杆菌或伴放线放线杆菌的 DNA 可诱导骨髓来源的巨噬细胞（BMDMs）产生 IL-6，该作用可被氯喹消除。Western blot 分析显示，TLR2/4 和 MyD88 是巨噬细胞对具核梭杆菌和伴放线放线杆菌的 NF-κB 和丝裂原活化蛋白激酶（MAPKs）的最佳激活所必需的，其动力学不同。抑制剂实验表明，NF-κB 和所有 MAPKs（p38、细胞外信号调节激酶 [ERK]和 Jun N-末端蛋白激酶 [JNK]）介导巨噬细胞中具核梭杆菌诱导的细胞因子产生，而 NF-κB 和 p38，而不是 ERK 和 JNK，参与伴放线放线杆菌介导的细胞因子产生。这些发现表明，多种 TLR 可能参与巨噬细胞针对牙周细菌的细胞因子产生。
