The type I NADH dehydrogenase of Mycobacterium tuberculosis counters phagosomal NOX2 activity to inhibit TNF-alpha-mediated host cell apoptosis.
The type I NADH dehydrogenase of Mycobacterium tuberculosis counters phagosomal NOX2 activity to inhibit TNF-alpha-mediated host cell apoptosis.
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DOI：
10.1371/journal.ppat.1000864
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发表时间：
2010-04-22
期刊：
影响因子：
6.7
通讯作者：
Briken V
中科院分区：
文献类型：
--
作者：
Miller JL;Velmurugan K;Cowan MJ;Briken V
受感染细胞在受到病原体损伤后发生凋亡的能力是一种古老的先天免疫防御机制。因此，持续存在的细胞内病原体如人类病原体结核分枝杆菌（Mtb）抑制感染诱导的巨噬细胞凋亡的能力对于毒力是重要的。Mtb的nuoG基因编码I型NADH脱氢酶NDH-1的NuoG亚基，在Mtb介导的宿主巨噬细胞凋亡的抑制中是重要的，但是这种宿主病原体相互作用的分子机制仍然难以捉摸。在这里，我们发现，在用caspase-3和-8抑制剂、TNF-α中和抗体处理的人巨噬细胞中，以及在感染小鼠TNF-/-巨噬细胞后，MtbΔnuoG的致瘤表型显著降低。有趣的是，巨噬细胞与活性氧（ROS）抑制剂一起孵育不仅减少了nuoG突变体诱导的细胞凋亡，而且减少了其增加巨噬细胞TNF-α分泌的能力。与原代鼠和人肺泡巨噬细胞中的Mtb吞噬体相比，MtbΔnuoG吞噬体显示出增加的ROS水平。MtbΔnuoG诱导的ROS和凋亡的增加在NOX-2缺陷型（gp 91 −/−）巨噬细胞中被消除。这些结果表明，Mtb，通过NuoG依赖性机制，可以中和NOX 2衍生的ROS，以抑制TNF-α介导的宿主细胞凋亡。因此，Mtb突变体分泌的过氧化氢酶缺陷诱导吞噬体ROS和宿主细胞凋亡的增加，这两者都依赖于巨噬细胞NOX-2活性。总之，这些结果意外地揭示了感染诱导的巨噬细胞凋亡过程中NOX 2活性、吞噬体ROS和TNF-α信号之间的新联系。此外，我们的研究揭示了NOX 2活性在先天免疫中的一种新功能，超越了最初的呼吸爆发，这是持续的细胞内病原体的传感和随后诱导宿主细胞凋亡作为第二道防线。 结核分枝杆菌是结核病的病原体，其高度适应于在其人类宿主的巨噬细胞中存活。宿主细胞自杀是一种古老的宿主细胞防御机制，被生物体用来抵御入侵的病原体。M.结核病操纵受感染的细胞以抑制宿主细胞死亡，但这种相互作用的分子机制尚未阐明。在这里，我们描述了M。结核病使用一种酶复合物（NDH-1），该酶复合物通常是产生能量所需的，以便中和宿主细胞的NOX-2酶介导的有毒氧自由基（ROS）的产生。我们证明了一个M。NDH-1缺陷的结核病突变体在巨噬细胞内积累ROS，其诱导炎性细胞因子（TNF-α）的分泌和随后的宿主细胞死亡。ROS的增加依赖于功能性NOX-2，因为缺失NOX-2组分的宿主细胞在被突变体感染后不经历细胞死亡。我们提出，一种新的功能的宿主细胞NOX-2复合物是允许传感的细胞内病原体的宿主细胞，以自杀，从而限制细菌的生存。
The capacity of infected cells to undergo apoptosis upon insult with a pathogen is an ancient innate immune defense mechanism. Consequently, the ability of persisting, intracellular pathogens such as the human pathogen Mycobacterium tuberculosis (Mtb) to inhibit infection-induced apoptosis of macrophages is important for virulence. The nuoG gene of Mtb, which encodes the NuoG subunit of the type I NADH dehydrogenase, NDH-1, is important in Mtb-mediated inhibition of host macrophage apoptosis, but the molecular mechanism of this host pathogen interaction remains elusive. Here we show that the apoptogenic phenotype of MtbΔnuoG was significantly reduced in human macrophages treated with caspase-3 and -8 inhibitors, TNF-α-neutralizing antibodies, and also after infection of murine TNF−/− macrophages. Interestingly, incubation of macrophages with inhibitors of reactive oxygen species (ROS) reduced not only the apoptosis induced by the nuoG mutant, but also its capacity to increase macrophage TNF-α secretion. The MtbΔnuoG phagosomes showed increased ROS levels compared to Mtb phagosomes in primary murine and human alveolar macrophages. The increase in MtbΔnuoG induced ROS and apoptosis was abolished in NOX-2 deficient (gp91−/−) macrophages. These results suggest that Mtb, via a NuoG-dependent mechanism, can neutralize NOX2-derived ROS in order to inhibit TNF-α-mediated host cell apoptosis. Consistently, an Mtb mutant deficient in secreted catalase induced increases in phagosomal ROS and host cell apoptosis, both of which were dependent upon macrophage NOX-2 activity. In conclusion, these results serendipitously reveal a novel connection between NOX2 activity, phagosomal ROS, and TNF-α signaling during infection-induced apoptosis in macrophages. Furthermore, our study reveals a novel function of NOX2 activity in innate immunity beyond the initial respiratory burst, which is the sensing of persistent intracellular pathogens and subsequent induction of host cell apoptosis as a second line of defense. Mycobacterium tuberculosis, the causative agent of tuberculosis, is highly adapted to survive in macrophages of its human host. Host cell suicide is an ancient host cell defense mechanism employed by organisms to wall off invading pathogens. M. tuberculosis manipulates infected cells to inhibit host cell death but the molecular mechanism of this interaction has not been elucidated. Here we describe that M. tuberculosis uses an enzyme complex (NDH-1) usually needed for energy generation in order to neutralize the NOX-2 enzyme-mediated production of toxic oxygen radicals (ROS) by the host cell. We demonstrate that an M. tuberculosis mutant deficient in NDH-1 accumulates ROS inside the macrophage which induces the secretion of an inflammatory cytokine (TNF-α) and subsequent host cell death. The increase of ROS is dependent upon functional NOX-2, since host cells missing a NOX-2 component do not undergo cell death upon infection with the mutant. We propose that a novel function of the host cell NOX-2 complex is to allow sensing of intracellular pathogens by the host cell in order to commit suicide and thus limit bacterial survival.
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DOI：
10.1084/jem.175.4.1111
发表时间：
1992-04-01
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Chan J;Xing Y;Magliozzo RS;Bloom BR
通讯作者：
Bloom BR
影响因子：
15.9
作者：
Hinchey, Joseph;Lee, Sunhee;Porcelli, Steven A.
通讯作者：
Porcelli, Steven A.
影响因子：
30.5
作者：
Gan H;Lee J;Ren F;Chen M;Kornfeld H;Remold HG
通讯作者：
Remold HG
影响因子：
3
作者：
GUNASEKAR, PG;KANTHASAMY, AG;ISOM, GE
通讯作者：
ISOM, GE
影响因子：
3.1
作者：
Briken V;Miller JL
通讯作者：
Miller JL