Inactivation of Bacillus anthracis spores in murine primary macrophages
Inactivation of Bacillus anthracis spores in murine primary macrophages
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DOI：
10.1111/j.1462-5822.2006.00738.x
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发表时间：
2006-10-01
影响因子：
3.4
通讯作者：
Zhou, Daoguo
中科院分区：
文献类型：
--
作者：
Hu, Haijing;Sa, Qila;Zhou, Daoguo
目前的吸入性炭疽发病机制模型表明，肺泡巨噬细胞对炭疽芽孢杆菌孢子的摄取和命运对感染过程至关重要。我们采用了原代巨噬细胞，这是更有效的孢子摄取比巨噬细胞样细胞系RAW 264.7，调查孢子摄取和生存。我们发现，在感染复数（moi）为5时，仅含有pXO 1质粒的Sterne菌株的孢子在1小时内被内化超过80%。在感染后4小时内，内化的Sterne孢子的活力下降至约40%。在整个感染过程中，细胞内营养细菌占总孢子接种物的不到1%，这表明有效杀死萌发的孢子和/或营养细菌。与溶酶体相关膜蛋白1（LAMP 1）的共定位表明，斯特恩孢子迅速贩运到吞噬溶酶体。显性负Rab 7的表达，阻断溶酶体融合增强斯特恩孢子存活。此外，D-丙氨酸的感染导致75%的孢子萌发抑制和增加的存活率的内化孢子的Sterne菌株和致病菌株含有pXO 1和pXO 2质粒。通过添加L-丙氨酸逆转抑制，其恢复孢子萌发和随后的孢子杀灭。我们的数据表明，B.炭疽孢子在原代巨噬细胞中萌发并随后被其杀死。
The current model for pathogenesis of inhalation anthrax indicates that the uptake and fate of Bacillus anthracis spores in alveolar macrophages are critical to the infection process. We have employed primary macrophages, which are more efficient for spore uptake than the macrophage-like cell line RAW264.7, to investigate spore uptake and survival. We found that at a multiplicity of infection (moi) of 5, greater than 80% of the spores of the Sterne strain containing only the pXO1 plasmid were internalized within 1 h. Within 4 h post infection, viability of internalized Sterne spores decreased to approximately 40%. Intracellular vegetative bacteria represented less than 1% of the total spore inoculum throughout the course of infection suggesting effective killing of germinated spores and/or vegetative bacteria. The Sterne spores trafficked quickly to phagolysosomes as indicated by colocalization with lysosome-associated membrane protein 1 (LAMP1). Expression of a dominant-negative Rab7 that blocked lysosome fusion enhanced Sterne spore survival. Addition of D-alanine to the infection resulted in 75% inhibition of spore germination and increased survival of internalized spores of the Sterne strain and a pathogenic strain containing both the pXO1 and pXO2 plasmids. Inhibition was reversed by the addition of L-alanine, which resumed spore germination and subsequent spore killing. Our data indicate that B. anthracis spores germinate in and are subsequently killed by primary macrophages.