Institute for Medical Microbiology, Justus-Liebig-University, Giessen, Germany.
Int J Med Microbiol. 2011 Nov;301(7):547-55. doi: 10.1016/j.ijmm.2011.05.001. Epub 2011 Jun 21.
IFN-γ-activated macrophages are considered to be the primary effector cells in host defense against Listeria monocytogenes infections. However despite the induction of the complex host defense mechanisms, survival of L. monocytogenes in activated macrophages is still observed. Here we used a whole genome-based transcriptome approach to examine for bacterial genes specifically induced in IFN-γ-activated macrophages. We demonstrated that cells activated by IFN-γ had elevated oxidative and nitrosative stress levels in both the activated macrophages as well as in the intracellular replicating bacteria isolated from these infected cells. We found that a subset of 21 transcripts were specifically differentially regulated in bacteria growing in cells pretreated with IFN-γ. Bioinformatics and functional analysis revealed that many of these genes have roles involved in overcoming oxidative stress and contribute to bacterial survival within activated macrophages. We detected increased transcription of the putative trpE gene of L. monocytogenes, encoding an anthranilate synthase, in bacteria growing in IFN-γ cells indicating host cell metabolic restriction of bacterial growth. Indeed we found enhanced activation of host cell genes involved in the kynurenine pathway indicating an increased need of L. monocytogenes for tryptophan during replication in IFN-γ-activated macrophages.
IFN-γ 激活的巨噬细胞被认为是宿主防御李斯特菌感染的主要效应细胞。然而，尽管诱导了复杂的宿主防御机制，但李斯特菌在激活的巨噬细胞中仍然存活。在这里，我们使用基于全基因组的转录组方法来研究 IFN-γ 激活的巨噬细胞中特异性诱导的细菌基因。我们证明，IFN-γ 激活的细胞在激活的巨噬细胞以及从这些感染细胞中分离的细胞内复制细菌中都具有升高的氧化和硝化应激水平。我们发现，在 IFN-γ 预处理的细胞中生长的细菌中，有 21 个转录本子集特异性地差异调节。生物信息学和功能分析表明，这些基因中的许多基因在克服氧化应激方面具有作用，并有助于细菌在激活的巨噬细胞内的存活。我们检测到在 IFN-γ 细胞中生长的李斯特菌中假定的 trpE 基因（编码邻氨基苯甲酸合酶）的转录增加，表明宿主细胞代谢限制了细菌的生长。事实上，我们发现参与犬尿氨酸途径的宿主细胞基因的激活增强，表明李斯特菌在 IFN-γ 激活的巨噬细胞中复制时对色氨酸的需求增加。
