Effective generation of reactive oxygen species in the mycobacterial phagosome requires K plus efflux from the bacterium
Effective generation of reactive oxygen species in the mycobacterial phagosome requires K plus efflux from the bacterium
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DOI：
10.1111/j.1462-5822.2010.01463.x
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发表时间：
2010-08-01
影响因子：
3.4
通讯作者：
Stewart, Graham R.
中科院分区：
文献类型：
--
作者：
Butler, Rachel E.;Cihlarova, Vera;Stewart, Graham R.
宿主巨噬细胞对分枝杆菌的有效杀灭依赖于许多机制，包括吞噬体NADPH氧化酶NOX2产生的活性氧物种(ROS)。致病分枝杆菌在吞噬小体中的生存取决于控制吞噬小体成熟的能力，因此与含有非致病细菌的吞噬小体相比，吞噬小体在生物和化学上发生了改变。在这项研究中，我们发现NOX2在分枝杆菌吞噬小体中产生ROS的作用与细菌的钾转运体是矛盾的。我们发现，缺乏Kef-型K+转运体的牛分枝杆菌卡介苗突变体(BCG Delta Kef)在静息和激活的巨噬细胞中表现出增加的细胞内存活表型，但仍保持抑制吞噬小体酸化的能力，并且对酸性条件或ROS没有表现出更强的抵抗力。ROS清除剂的加入在感染野生型BCG的巨噬细胞中复制了这一表型，与野生型BCG感染的巨噬细胞相比，感染BCG Delta Kef的巨噬细胞产生的ROS显著减少。我们的结果表明，BCG Delta Kef细胞内存活率的增加是通过诱导巨噬细胞氧化爆发减少而实现的，这与Kef改变吞噬小体的离子含量和促进ROS产生NOX2的作用是一致的。
P>Efficient killing of mycobacteria by host macrophages depends on a number of mechanisms including production of reactive oxygen species (ROS) by the phagosomal NADPH oxidase, NOX2. Survival of pathogenic mycobacteria in the phagosome relies on the ability to control maturation of the phagosome such that it is biologically and chemically altered in comparison to phagosomes containing non-pathogenic bacteria. In this study we show that the action of NOX2 to produce ROS in the mycobacterial phagosome is paradoxically dependent on a bacterial potassium transporter. We show that a Mycobacterium bovis BCG mutant (BCG Delta kef), deficient in a Kef-type K+ transporter, exhibits an increased intracellular survival phenotype in resting and activated macrophages, yet retains the ability to inhibit phagosome acidification, and does not show increased resistance to acidic conditions or ROS. Addition of a ROS scavenger replicates this phenotype in macrophages infected with wild-type BCG, and the production of ROS by macrophages infected with BCG Delta kef is substantially decreased compared with those infected with wild-type BCG. Our results suggest that increased intracellular survival of BCG Delta kef is mediated by inducing a decreased macrophage oxidative burst, and are consistent with Kef acting to alter the ionic contents of the phagosome and promoting NOX2 production of ROS.