High-resolution mapping reveals that microniches in the gastric glands control Helicobacter pylori colonization of the stomach

Abstract

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.

Comparison of motility of H. pylori in broth and mucin reveals the interplay of effect of acid on bacterium and the rheology of the medium it swims in

“…Our observation that when pH becomes too low (around pH 3) the flagellar motors do not function well is in agreement with the finding of Sachs et al [14], although our experiments were done without adding urea in the medium to prevent external pH from increasing [11]. The lack of added urea in broth or PGM medium could have impaired cytoplasmic pH regulation as the urease receptors on the external surface of the bacterium were probably not activated, although the internal ones probably were active [14,15,36].…”

“…There is other evidence which supports that H. pylori thrives in acidic environment, such as in presence of urea, an acidic environment was necessary for the survival of H. pylori [15] and the urease and metabolic activities of the bacteria increase at pH 4 and below [35]. H. pylori is also able to both survive and colonize deep in the parietal glands, where acid is secreted [36].…”

“…We also observed that stuck bacteria rotate faster than motile ones, perhaps indicating a mechanosensing ability of H. pylori trapped in a gel network. Mechanosensing has been observed in recent studies of the flagellar motor with varying load and viscosity of the medium [38,39] and they suggest that the bacterial flagellar motor senses external load and mediates the strength of stator binding to the rest of the motor. The motor of H. pylori , like other ε-proteobacters such as C. jejuni , has adapted to high torque generation by having a large scaffold of proteinaceous, periplasmic rings to increase the radius of the contact lever point and to accommodate the large number of stators (17 for C. jejuni [21,40] and 18 for H. pylori [20,21], and by having high stator occupancy [21].…”

Distinct but Intertwined Evolutionary Histories of Multiple Salmonella enterica Subspecies

“…enterica (I) and the non-enterica subspecies are not exclusively isolated from each other, and both can sometimes be found together in cold-and warm-blooded animals. Hence, another possible explanation for the variation in recombination is that different Salmonella subspecies occupy distinct microecological niches (48), which may even be separated by a few millimeters, within a human or animal host and therefore reduce the opportunity for genetic exchange. The existence of cryptic niches and their role in structuring bacterial populations have been previously reported.…”

Three decades of listeriology through the prism of technological advances

“…Current imaging techniques also reveals phenotypic heterogeneity of microbial and cellular populations that can be further studied by systems biology approaches (Bumann, 2015;Kreibich & Hardt, 2015). Many microbial pathogens interact in complex microenvironments with diverse host microbiota, dynamic polymicrobial communities that start to be successfully imaged by specific techniques such as passive clarity technique (Fung et al, 2019;Yang et al, 2014) and light sheet fluorescence microscopy (Parthasarathy, 2018). Imaging progress spread to a wide range of models, for example, animal or plant infection by viruses, bacteria, fungi or protozoan parasites (Levraud et al, 2009;Barbier, Bevere, & Damron, 2018;Musetti & Buxa, 2019).…”