Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America.
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
PLoS Biol. 2019 May 2;17(5):e3000231. doi: 10.1371/journal.pbio.3000231. eCollection 2019 May.
Lifelong infection of the gastric mucosa by Helicobacter pylori can lead to peptic ulcers and gastric cancer. However, how the bacteria maintain chronic colonization in the face of constant mucus and epithelial cell turnover in the stomach is unclear. Here, we present a new model of how H. pylori establish and persist in stomach, which involves the colonization of a specialized microenvironment, or microniche, deep in the gastric glands. Using quantitative three-dimensional (3D) confocal microscopy and passive CLARITY technique (PACT), which renders tissues optically transparent, we analyzed intact stomachs from mice infected with a mixture of isogenic, fluorescent H. pylori strains with unprecedented spatial resolution. We discovered that a small number of bacterial founders initially establish colonies deep in the gastric glands and then expand to colonize adjacent glands, forming clonal population islands that persist over time. Gland-associated populations do not intermix with free-swimming bacteria in the surface mucus, and they compete for space and prevent newcomers from establishing in the stomach. Furthermore, bacterial mutants deficient in gland colonization are outcompeted by wild-type (WT) bacteria. Finally, we found that host factors such as the age at infection and T-cell responses control bacterial density within the glands. Collectively, our results demonstrate that microniches in the gastric glands house a persistent H. pylori reservoir, which we propose replenishes the more transient bacterial populations in the superficial mucosa.
幽门螺杆菌（Helicobacter pylori）在胃黏膜的终身感染可导致消化性溃疡和胃癌。然而，在面对胃中不断的黏液和上皮细胞更新时，细菌如何维持慢性定植尚不清楚。在这里，我们提出了一种新的模型，说明幽门螺杆菌如何在胃中建立和持续存在，该模型涉及到一个专门的微环境或微生境的定植，该微生境位于胃腺的深处。我们使用定量三维（3D）共聚焦显微镜和被动 CLARITY 技术（PACT），对感染了混合同源荧光幽门螺杆菌菌株的小鼠的完整胃进行了分析，具有前所未有的空间分辨率。我们发现，少数细菌创始者最初在胃腺的深处建立菌落，然后扩展到相邻的腺体，形成克隆种群岛，随着时间的推移而持续存在。与表面黏液中自由游动的细菌不同，腺体相关的菌群不会混合，它们争夺空间，并防止新来者在胃中定植。此外，在腺体定植中缺失的细菌突变体被野生型（WT）细菌所淘汰。最后，我们发现宿主因素，如感染时的年龄和 T 细胞反应，控制着腺体中的细菌密度。总的来说，我们的研究结果表明，胃腺中的微生境容纳了一个持久的幽门螺杆菌储库，我们提出该储库补充了浅层黏膜中更短暂的细菌群体。
