Ortalo-Magné Annick, Andersen Åse B, Daffé Mamadou
Laboratoire de Pharmacologie et de Toxicologie Fondamentales du CNRS and Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France.
Mycobacteria Department, Statens Seruminstitut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark.
Microbiology (Reading). 1996 Apr;142 ( Pt 4):927-935. doi: 10.1099/00221287-142-4-927.
It has been shown that phagocyte mannose receptors play an important role in phagocytosis of virulent tubercle bacilli, but not of avirulent strains. Accordingly, we investigated the occurrence and structure of the outermost mannoconjugates of the capsule of five strains of the tubercle bacillus differing in their degrees of virulence. The extracellular and surface-exposed arabinomannan-containing polysaccharides were chemically characterized as being composed mainly of neutral fatty-acyl-free arabinomannans (AMs) possessing a reducing end consisting of mannose. Although no lipoarabinomannan (LAM) was detected, small amounts of acidic polysaccharides, exhibiting the same electrophoretic mobility as LAM, were identified as succinylated AMs (two to three residues per molecule) lacking the phosphatidylinositol anchor of LAM. AMs from the different strains shared the same structural features, notably the capping of a large portion of the arabinan segments with mannosyl residues. However, no correlation was observed between either the percentage of capping or the amount of AMs and the degrees of virulence of the strains. The occurrence and amounts of other mannoconjugates (phosphatidylinositol mannosides and the mannose-associated 19 and 38 kDa lipoproteins) in the various tubercle bacilli were also examined. Although both classes of compounds were identified in all the examined strains, a correlation between the amounts of the glycoconjugates and the degrees of virulence of the strains could not be established. These data do not support the implication of these promising mannosylated molecules in the selective phagocytosis of virulent tubercle bacilli and indicate that the involvement of mannose receptors in phagocytosis of virulent M. tuberculosis needs to be re-investigated.
已表明吞噬细胞甘露糖受体在吞噬有毒力结核杆菌而非无毒力菌株中起重要作用。因此，我们研究了五株毒力程度不同的结核杆菌菌株荚膜最外层甘露糖缀合物的存在情况和结构。细胞外和表面暴露的含阿拉伯甘露聚糖的多糖经化学表征，主要由不含中性脂肪酰基的阿拉伯甘露聚糖（AMs）组成，其还原端由甘露糖构成。虽然未检测到脂阿拉伯甘露聚糖（LAM），但鉴定出少量酸性多糖，其电泳迁移率与LAM相同，为缺乏LAM磷脂酰肌醇锚定的琥珀酰化AMs（每分子两到三个残基）。来自不同菌株的AMs具有相同的结构特征，特别是大部分阿拉伯聚糖片段被甘露糖残基封端。然而，封端百分比或AMs含量与菌株毒力程度之间未观察到相关性。还检查了各种结核杆菌中其他甘露糖缀合物（磷脂酰肌醇甘露糖苷以及与甘露糖相关的19 kDa和38 kDa脂蛋白）的存在情况和含量。虽然在所有检测菌株中都鉴定出了这两类化合物，但糖缀合物含量与菌株毒力程度之间无法建立相关性。这些数据不支持这些有前景的甘露糖基化分子参与有毒力结核杆菌的选择性吞噬作用，并表明甘露糖受体在有毒力结核分枝杆菌吞噬作用中的参与需要重新研究。
