Lipoteichoic acid of Streptococcus mutans interacts with Toll-like receptor 2 through the lipid moiety for induction of inflammatory mediators in murine macrophages
Lipoteichoic acid of Streptococcus mutans interacts with Toll-like receptor 2 through the lipid moiety for induction of inflammatory mediators in murine macrophages
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DOI：
10.1016/j.molimm.2013.10.004
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发表时间：
2014-02-01
影响因子：
3.6
通讯作者：
Han, Seung Hyun
中科院分区：
文献类型：
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作者：
Hong, Sun Woong;Baik, Jung Eun;Han, Seung Hyun
变形链球菌是一种致病性革兰氏阳性细菌，与龋齿和牙髓炎症密切相关。虽然脂磷壁酸(LTA)被认为是革兰氏阳性菌的主要毒力因子，但对变形链球菌LTA的天然免疫力知之甚少。在本研究中，我们通过正丁醇提取、疏水作用柱层析和离子交换柱层析从变形链球菌(Sm.LTA)中纯化了LTA，并用小鼠巨噬细胞研究了其免疫学性质。Sm.LTA制剂没有检测到内毒素、蛋白质或核酸的污染。小鼠巨噬细胞系RAW 264.7细胞暴露于Sm.LTA后，以剂量依赖的方式产生肿瘤坏死因子-α和一氧化氮(NO)。Sm.LTA优先结合并激活CHO/CD14/TLR2细胞，而不是CHO/CD14/TLR4细胞，后者分别是稳定表达CD14和TLR2或CD14和TLR4的转染体。Sm.LTA不能诱导TLR2基因缺陷小鼠巨噬细胞产生肿瘤坏死因子-α或一氧化氮，而对野生型巨噬细胞则呈剂量依赖性地诱导这些炎症介质的产生。在RAW 264.7细胞中，使用阻断TLR2的特异性抗体也证实了Sm.LTA对TLR2依赖的NO的诱导。此外，Sm.LTA经碱解脱酰后既不能刺激TLR2，也不能诱导肿瘤坏死因子-α。与具有强大免疫刺激活性的金黄色葡萄球菌LTA不同，Sm.LTA对NO的诱导作用与其他口腔细菌粪肠球菌和植物乳杆菌的LTA相当。综上所述，我们的结果表明，Sm.LTA通过脂质部分与TLR2相互作用，诱导巨噬细胞中的炎症介质。(C)2013爱思唯尔有限公司。保留所有权利。
Streptococcus mutans is a pathogenic Gram-positive bacterium that is closely associated with dental caries and subsequent pulpal inflammation. Although lipoteichoic acid (LTA) is considered a major virulence factor of Gram-positive bacteria, little is known about the innate immunity to S. mutans LTA. In this study, we purified LTA from S. mutans (Sm.LTA) through n-butanol extraction, hydrophobic interaction column chromatography, and ion-exchange column chromatography to investigate its immunological properties using murine macrophages. The Sm.LTA preparation had no detectable contamination with endotoxins, proteins, or nucleic acids. Upon exposure to Sm.LTA, the murine macrophage cell-line RAW 264.7 cells produced TNF-alpha and nitric oxide (NO) in a dose-dependent manner. Sm.LTA preferentially bound to and activated CHO/CD14/TLR2 cells rather than CHO/CD14/TLR4 cells, which are stable transfectants expressing CD14 and TLR2 or CD14 and TLR4, respectively. Sm.LTA could not induce TNF-alpha or NO production in macrophages derived from TLR2-deficient mice whereas it dose-dependently induced those inflammatory mediators in wild-type macrophages. TLR2-dependent induction of NO by Sm.LTA was also confirmed in RAW 264.7 cells using specific antibodies blocking TLR2. Furthermore, Sm.LTA deacylated by alkaline hydrolysis neither stimulated TLR2 nor induced TNF-alpha. or NO production, suggesting that Sm.LTA lipid moieties are crucial for the immuno-stimulatory activity of Sm.LTA. Unlike Staphylococcus aureus LTA, which has potent immuno-stimulating activity, Sm.LTA showed a modest induction of NO production comparable to LTAs of other oral bacteria Enterococcus faecalis and Lactobacillus plantarum. In conclusion, our results suggest that the Sm.LTA interacts with TLR2 through the lipid moiety for the induction of inflammatory mediators in macrophages. (C) 2013 Elsevier Ltd. All rights reserved.