Surface-exposed glycopeptidolipids of Mycobacterium smegmatis specifically inhibit the phagocytosis of mycobacteria by human macrophages -: Identification of a novel family of glycopeptidolipids
Surface-exposed glycopeptidolipids of Mycobacterium smegmatis specifically inhibit the phagocytosis of mycobacteria by human macrophages -: Identification of a novel family of glycopeptidolipids
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DOI：
10.1074/jbc.m306554200
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发表时间：
2003-12-19
影响因子：
4.8
通讯作者：
Astarie-Dequeker, C
中科院分区：
文献类型：
--
作者：
Villeneuve, C;Etienne, G;Astarie-Dequeker, C
巨噬细胞的吞噬作用代表了分枝杆菌感染的早期阶段。它由所用宿主受体的性质和暴露在细菌上的配体决定。通过机械处理提取非致病性耻垢分枝杆菌的最外层分子，发现其特异性和剂量依赖性地抑制两种M.耻垢病和机会致病菌M. kansasii通过来源于单核细胞的人巨噬细胞。抑制活性归因于表面脂质，因为它是由氯仿提取和碱水解，但不是由蛋白酶处理减少。通过吸附色谱法对表面脂质进行分级，表明主要抑制化合物由磷脂和糖肽脂（GPLs）组成。质谱和核磁共振光谱分析，结合化学降解方法，证明了一种新的GPL家族的存在，该家族由长链三肽基氨基醇组成的核心组成，其中二-O-乙酰基-6-脱氧塔罗糖基单元取代了别苏糖基残基，2-琥珀酰基-3，4-二-O-CH3-鼠李糖基单元连接到分子的丙氨醇末端。这些化合物以及丙氨醇末端的二糖基化GPL和去-O-酰化GPL，但非血清型特异性的二-O-乙酰化GPL，抑制M的吞噬作用。耻垢分枝杆菌和M.酵母聚糖的内化速率与人巨噬细胞在几纳摩尔浓度下对avium的吞噬作用无关。在微摩尔浓度下，天然GPL也抑制两种M的摄取。结核和M.堪萨斯。脱-O-酰化实验确立了琥珀酰基和乙酰基取代基的关键作用。总的来说，这些数据提供的证据表明，表面暴露的分枝杆菌糖缀合物是巨噬细胞和分枝杆菌之间相互作用的有效竞争者，因此，可以代表用于控制分枝杆菌感染的药理学工具。
Phagocytosis by macrophages represents the early step of the mycobacterial infection. It is governed both by the nature of the host receptors used and the ligands exposed on the bacteria. The outermost molecules of the nonpathogenic Mycobacterium smegmatis were extracted by a mechanical treatment and found to specifically and dose dependently inhibit the phagocytosis of both M. smegmatis and the opportunistic pathogen M. kansasii by human macrophages derived from monocytes. The inhibitory activity was attributed to surface lipids because it is extracted by chloroform and reduced by alkaline hydrolysis but not by protease treatment. Fractionation of surface lipids by adsorption chromatography indicated that the major inhibitory compounds consisted of phospholipids and glycopeptidolipids (GPLs). Mass spectrometry and nuclear magnetic resonance spectroscopy analyses, combined with chemical degradation methods, demonstrated the existence of a novel family of GPLs that consists of a core composed of the long-chain tripeptidyl amino-alcohol with a di-O-acetyl-6-deoxytalosyl unit substituting the allo-threoninyl residue and a 2-succinyl-3,4-di-O-CH3-rhamnosyl unit linked to the alaninol end of the molecules. These compounds, as well as diglycosylated GPLs at the alaninol end and de-O-acylated GPLs, but not the non-serovar-specific di-O-acetylated GPLs, inhibited the phagocytosis of M. smegmatis and M. avium by human macrophages at a few nanomolar concentration without affecting the rate of zymosan internalization. At micromolar concentrations, the native GPLs also inhibit the uptake of both M. tuberculosis and M. kansasii. De-O-acylation experiments established the critical roles of both the succinyl and acetyl substituents. Collectively, these data provide evidence that surface-exposed mycobacterial glycoconjugates are efficient competitors of the interaction between macrophages and mycobacteria and, as such, could represent pharmacological tools for the control of mycobacterial infections.