School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Cell Host Microbe. 2015 Jan 14;17(1):32-46. doi: 10.1016/j.chom.2014.11.016. Epub 2014 Dec 24.
Nonreplicating and metabolically quiescent bacteria are implicated in latent tuberculosis infections and relapses following "sterilizing" chemotherapy. However, evidence linking bacterial dormancy and persistence in vivo is largely inconclusive. Here we measure the single-cell dynamics of Mycobacterium tuberculosis replication and ribosomal activity using quantitative time-lapse microscopy and a reporter of ribosomal RNA gene expression. Single-cell dynamics exhibit heterogeneity under standard growth conditions, which is amplified by stressful conditions such as nutrient limitation, stationary phase, intracellular replication, and growth in mouse lungs. Additionally, the lungs of chronically infected mice harbor a subpopulation of nongrowing but metabolically active bacteria, which are absent in mice lacking interferon-γ, a cytokine essential for antituberculosis immunity. These cryptic bacterial forms are prominent in mice treated with the antituberculosis drug isoniazid, suggesting a role in postchemotherapeutic relapses. Thus, amplification of bacterial phenotypic heterogeneity in response to host immunity and drug pressure may contribute to tuberculosis persistence.
非复制和代谢静止的细菌与潜伏性结核感染以及“灭菌”化疗后的复发有关。然而，将细菌休眠与体内持久性联系起来的证据在很大程度上尚无定论。在这里，我们使用定量延时显微镜和核糖体 RNA 基因表达的报告基因来测量结核分枝杆菌复制和核糖体活性的单细胞动力学。在标准生长条件下，单细胞动力学表现出异质性，而在营养限制、静止期、细胞内复制和在小鼠肺部生长等应激条件下，这种异质性会被放大。此外，慢性感染小鼠的肺部存在一群非生长但代谢活跃的细菌，而在缺乏干扰素-γ（一种对抗结核免疫至关重要的细胞因子）的小鼠中则不存在。在接受抗结核药物异烟肼治疗的小鼠中，这些隐匿细菌形式更为突出，提示其与化疗后复发有关。因此，宿主免疫和药物压力对细菌表型异质性的放大可能导致结核病的持续存在。
