Macrophage uptake, intracellular localization, and degradation of poly-gamma-D-glutamic acid, the capsular antigen of Bacillus anthracis.
Macrophage uptake, intracellular localization, and degradation of poly-gamma-D-glutamic acid, the capsular antigen of Bacillus anthracis.
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巨噬细胞摄取、细胞内定位和聚-γ-D-谷氨酸（炭疽杆菌荚膜抗原）的降解。
DOI：
10.1128/iai.01009-08
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发表时间：
2009
影响因子：
3.1
通讯作者：
Kozel,ThomasR
中科院分区：
文献类型：
--
作者：
Sutherland,MarjorieD;Kozel,ThomasR
炭疽芽孢杆菌被由聚-γ-d-谷氨酸（PGA）组成的荚膜多肽包围。这种抗吞噬细胞胶囊是一种重要的毒力因子，在小鼠肺炭疽模型中会脱落到体液中。我们之前对小鼠抗原清除模型的研究表明，纯化的 PGA 在肝脏和脾脏中积聚，最明显的是在脾巨噬细胞以及肝脏的库普弗细胞和肝窦内皮细胞中。尽管组织和细胞库已被鉴定，但人们对 PGA 的摄取和细胞内命运知之甚少。因此，我们检查了小鼠巨噬细胞样细胞系 J774.2 中 PGA 的细胞摄取和细胞器定位。我们发现 PGA 与 J774.2 细胞结合并被其内化，并在 CD71 转铁蛋白受体阳性内体中积累。受体介导的内吞作用抑制剂金刚烷胺和苯胂氧化物抑制这些细胞中 PGA 的结合和摄取。细胞松弛素 D 和长春花碱、肌动蛋白和微管抑制剂分别未能完全抑制结合和摄取。最后，我们发现 J774.2 细胞中的 PGA 在摄取后 4 小时开始降解，并持续降解至少 24 小时。 PGA 的这种降解可以解释体内观察到的 PGA 的快速清除与荚膜多糖的缓慢清除相比。
Bacillus anthracisis surrounded by a capsular polypeptide composed of poly-γ-d-glutamic acid (PGA). This antiphagocytic capsule is an essential virulence factor and is shed into body fluids during a murine model of pulmonary anthrax. Our previous studies of a murine model for antigen clearance showed that purified PGA accumulates in the liver and spleen, most notably in splenic macrophages and the Kupffer cells and sinusoidal endothelial cells of the liver. Although the tissue and cellular depots have been identified, there is little known about the uptake and intracellular fate of PGA. As a consequence, we examined the cellular uptake and organelle localization of PGA in the murine macrophage-like cell line J774.2. We found that PGA binds to and is internalized by J774.2 cells and accumulates in CD71 transferrin receptor-positive endosomes. The receptor-mediated endocytosis inhibitors amantadine and phenylarsine oxide inhibited the binding and uptake of PGA in these cells. Cytochalasin D and vinblastine, actin and microtubule inhibitors, respectively, failed to completely inhibit binding and uptake. Finally, we found that PGA is degraded in J774.2 cells starting 4 h after uptake, with continued degradation occurring for at least 24 h. This degradation of PGA may explain the rapid clearance of PGA that is observed in vivo compared to the slow clearance noted with capsular polysaccharides.