Cywes C, Hoppe H C, Daffé M, Ehlers M R
Department of Medical Biochemistry, University of Cape Town Medical School, Observatory, South Africa.
Infect Immun. 1997 Oct;65(10):4258-66. doi: 10.1128/iai.65.10.4258-4266.1997.
The choice of host cell receptor and the mechanism of binding (opsonic versus nonopsonic) may influence the intracellular fate of Mycobacterium tuberculosis. We have identified two substrains of M. tuberculosis H37Rv, designated H37Rv-CC and -HH, that differed in their modes of binding to complement receptor type 3 (CR3) expressed in transfected Chinese hamster ovary (CHO-Mac-1) cells: H37Rv-CC bound nonopsonically, whereas H37Rv-HH bound only after opsonization in fresh serum. H37Rv-CC also bound nonopsonically to untransfected CHO cells, whereas H37Rv-HH binding was enhanced by serum and was mediated by the 1D1 antigen, a bacterial adhesin previously identified as a polar phosphatidylinositol mannoside. H37Rv-CC and -HH had identical IS6110 DNA fingerprint patterns. Of five M. tuberculosis clinical isolates examined, four displayed the same binding phenotype as H37Rv-CC, as did the Erdman strain, whereas one isolate, as well as Mycobacterium smegmatis, behaved like H37Rv-HH. Nonopsonic binding of H37Rv-CC to CHO cell-expressed CR3 was apparently to the beta-glucan lectin site, as it was cation independent and inhibited by laminarin (seaweed beta-glucan) and N-acetylglucosamine; laminarin also inhibited the binding of H37Rv-CC to monocyte-derived macrophages. Further, binding of H37Rv-CC to CHO-Mac-1 cells was inhibited by prior agitation of bacteria with glass beads (which strips outer capsular polysaccharides) and by preincubation with amyloglucosidase, as well as by the presence of capsular D-glucan and D-mannan from M. tuberculosis Erdman, but not by Erdman D-arabino-D-mannan, yeast mannan, or capsular components from H37Rv-HH. Analysis of capsular carbohydrates revealed that H37Rv-CC expressed 5-fold more glucose and 2.5-fold more arabinose and mannose than H37Rv-HH. Flow cytometric detection of surface epitopes indicated that H37Rv-CC displayed twofold less surface-exposed phosphatidylinositol mannoside and bound complement C3 less efficiently than H37Rv-HH; these differences were eliminated after treatment of H37Rv-CC with glass beads. Thus, outer capsular polysaccharides mediate the binding of H37Rv-CC to CR3, likely to the beta-glucan site. Moreover, there are strain-dependent differences in the thickness or composition of capsular polysaccharides that determine the mode of binding of M. tuberculosis to mammalian cells.
宿主细胞受体的选择以及结合机制（调理素介导与非调理素介导）可能会影响结核分枝杆菌在细胞内的命运。我们鉴定出了结核分枝杆菌H37Rv的两个亚菌株，分别命名为H37Rv - CC和 - HH，它们与转染的中国仓鼠卵巢细胞（CHO - Mac - 1）中表达的补体受体3（CR3）的结合方式不同：H37Rv - CC以非调理素方式结合，而H37Rv - HH仅在新鲜血清中被调理后才结合。H37Rv - CC也以非调理素方式结合未转染的CHO细胞，而H37Rv - HH的结合在血清存在下增强，并且由1D1抗原介导，1D1抗原是一种先前被鉴定为极性磷脂酰肌醇甘露糖的细菌黏附素。H37Rv - CC和 - HH具有相同的IS6110 DNA指纹图谱。在所检测的5株结核分枝杆菌临床分离株中，4株表现出与H37Rv - CC相同的结合表型，埃尔德曼菌株也是如此，而1株分离株以及耻垢分枝杆菌的行为类似于H37Rv - HH。H37Rv - CC与CHO细胞表达的CR3的非调理素结合显然是与β - 葡聚糖凝集素位点结合，因为它不依赖阳离子，并被海带多糖（海藻β - 葡聚糖）和N - 乙酰葡糖胺抑制；海带多糖也抑制H37Rv - CC与单核细胞衍生巨噬细胞的结合。此外，用玻璃珠搅拌细菌（去除外膜多糖）、用淀粉葡糖苷酶预孵育以及存在来自结核分枝杆菌埃尔德曼的荚膜D - 葡聚糖和D - 甘露聚糖可抑制H37Rv - CC与CHO - Mac - 1细胞的结合，但埃尔德曼D - 阿拉伯糖 - D - 甘露聚糖、酵母甘露聚糖或H37Rv - HH的荚膜成分则无此作用。对荚膜碳水化合物的分析表明，H37Rv - CC表达的葡萄糖比H37Rv - HH多5倍，阿拉伯糖和甘露糖多2.5倍。表面表位的流式细胞术检测表明，H37Rv - CC表面暴露的磷脂酰肌醇甘露糖比H37Rv - HH少两倍，结合补体C3的效率也低于H37Rv - HH；用玻璃珠处理H37Rv - CC后，这些差异消失。因此，外膜多糖介导H37Rv - CC与CR3的结合，可能是与β - 葡聚糖位点结合。此外，荚膜多糖的厚度或组成存在菌株依赖性差异，这些差异决定了结核分枝杆菌与哺乳动物细胞的结合方式。
