Modulation of Transcriptional and Inflammatory Responses in Murine Macrophages by the Mycobacterium tuberculosis Mammalian Cell Entry (Mce) 1 Complex

The outcome of many infections depends on the initial interactions between agent and host. Aiming at elucidating the effect of the M. tuberculosis Mce1 protein complex on host transcriptional and immunological responses to infection with M. tuberculosis, RNA from murine macrophages at 15, 30, 60 min, 4 and 10 hrs post-infection with M. tuberculosis H37Rv or Δ-mce1 H37Rv was analyzed by whole-genome microarrays and RT-QPCR. Immunological responses were measured using a 23-plex cytokine assay. Compared to uninfected controls, 524 versus 64 genes were up-regulated by 15 min post H37Rv- and Δ-mce1 H37Rv-infection, respectively. By 15 min post-H37Rv infection, a decline of 17 cytokines combined with up-regulation of Ccl24 (26.5-fold), Clec4a2 (23.2-fold) and Pparγ (10.5-fold) indicated an anti-inflammatory response initiated by IL-13. Down-regulation of Il13ra1 combined with up-regulation of Il12b (30.2-fold), suggested switch to a pro-inflammatory response by 4 hrs post H37Rv-infection. Whereas no significant change in cytokine concentration or transcription was observed during the first hour post Δ-mce1 H37Rv-infection, a significant decline of IL-1b, IL-9, IL-13, Eotaxin and GM-CSF combined with increased transcription of Il12b (25.1-fold) and Inb1 (17.9-fold) by 4 hrs, indicated a pro-inflammatory response. The balance between pro-and anti-inflammatory responses during the early stages of infection may have significant bearing on outcome.诸多感染的转归取决于病原体与宿主间的初始相互作用。本研究旨在阐明结核分枝杆菌（Mycobacterium tuberculosis）Mce1蛋白复合物对宿主感染结核分枝杆菌后的转录组与免疫应答的影响：针对感染结核分枝杆菌H37Rv株或Δ-mce1 H37Rv株的小鼠巨噬细胞，在感染后15、30、60分钟及4、10小时时提取的RNA，通过全基因组微阵列（whole-genome microarrays）与逆转录实时定量聚合酶链反应（RT-QPCR）进行分析；免疫应答则通过23联细胞因子检测试剂盒完成测定。与未感染对照组相比，感染H37Rv株与Δ-mce1 H37Rv株的小鼠巨噬细胞在感染后15分钟时，分别有524个和64个基因出现上调表达。感染H37Rv株后15分钟时，17种细胞因子的表达水平下调，同时Ccl24（26.5倍）、Clec4a2（23.2倍）与Pparγ（10.5倍）的表达上调，提示IL-13介导的抗炎应答被激活；至感染后4小时，Il13ra1表达下调同时Il12b（30.2倍）表达上调，表明机体转向促炎应答。而感染Δ-mce1 H37Rv株后的最初1小时内，未观察到细胞因子浓度或基因转录的显著变化；直至感染后4小时，IL-1β、IL-9、IL-13、Eotaxin与粒细胞-巨噬细胞集落刺激因子（GM-CSF）的水平显著下降，同时Il12b（25.1倍）与Inb1（17.9倍）的转录水平升高，提示促炎应答被激活。感染早期阶段促炎与抗炎应答间的动态平衡，可能对感染结局具有关键影响。