CD44 Plays a Functional Role in Helicobacter pylori-induced Epithelial Cell Proliferation

Abstract

The cytotoxin-associated gene (Cag) pathogenicity island is a strain-specific constituent of Helicobacter pylori (H. pylori) that augments cancer risk. CagA translocates into the cytoplasm where it stimulates cell signaling through the interaction with tyrosine kinase c-Met receptor, leading cellular proliferation. Identified as a potential gastric stem cell marker, cluster-of-differentiation (CD) CD44 also acts as a co-receptor for c-Met, but whether it plays a functional role in H. pylori-induced epithelial proliferation is unknown. We tested the hypothesis that CD44 plays a functional role in H. pylori-induced epithelial cell proliferation. To assay changes in gastric epithelial cell proliferation in relation to the direct interaction with H. pylori, human- and mouse-derived gastric organoids were infected with the G27 H. pylori strain or a mutant G27 strain bearing cagA deletion (∆CagA::cat). Epithelial proliferation was quantified by EdU immunostaining. Phosphorylation of c-Met was analyzed by immunoprecipitation followed by Western blot analysis for expression of CD44 and CagA. H. pylori infection of both mouse- and human-derived gastric organoids induced epithelial proliferation that correlated with c-Met phosphorylation. CagA and CD44 co-immunoprecipitated with phosphorylated c-Met. The formation of this complex did not occur in organoids infected with ∆CagA::cat. Epithelial proliferation in response to H. pylori infection was lost in infected organoids derived from CD44-deficient mouse stomachs. Human-derived fundic gastric organoids exhibited an induction in proliferation when infected with H. pylorithat was not seen in organoids pre-treated with a peptide inhibitor specific to CD44. In the well-established Mongolian gerbil model of gastric cancer, animals treated with CD44 peptide inhibitor Pep1, resulted in the inhibition of H. pylori-induced proliferation and associated atrophic gastritis. The current study reports a unique approach to study H. pylori interaction with the human gastric epithelium. Here, we show that CD44 plays a functional role in H. pylori-induced epithelial cell proliferation.

Gastric Metaplasia Induced by Helicobacter pylori Is Associated with Enhanced SOX9 Expression via Interleukin-1 Signaling

“…After PMSS1 infection, CD44 was expressed at the base of the corpus glands (Fig. 4A, bottom), and there was a significant increase in CD44 expression compared with that in control mice, as reported in previous studies (P Ͻ 0.05) (36,37) (Fig. 4B and C).…”

“…Another stem cell marker, CD44, was recently reported to play a functional role in H. pylori-induced epithelial cell proliferation and metaplasia (21,36). Khurana et al showed that CD44 expression was found in the isthmus in control mice, which expanded to the base after H. pylori infection.…”

Modeling infectious diseases and host-microbe interactions in gastrointestinal organoids

“…In cancer cell line models, CagA binds to the host c-MET receptor and promotes a motogenic response (Churin et al, 2003). In gastric organoids, CagA also binds to c-Met and likely as a response, host cell proliferation is induced in a CagA-dependent manner (Bertaux-Skeirik et al, 2015;McCracken et al, 2014). Together, these studies establish organoids as a model for H. pylori infection by demonstrating that organoids reproduce important hallmarks of the infection.…”

“…Injected bacteria can adhere to the epithelium and target apical cell-cell junctions Wroblewski et al, 2010). The bacteria are viable, as shown by re-culturing of H. pylori from organoids Bertaux-Skeirik et al, 2015) and even expand inside the organoids, suggesting that organoids may provide essential niche factors (Bertaux-Skeirik et al, 2015). Epithelial cells in organoids secrete urea, which induces a chemotactic response in the bacteria and may contribute to the establishment of a replicative niche in the organoids .…”

Pluripotent stem cell-derived organoids: using principles of developmental biology to grow human tissues in a dish

“…Gastrointestinal organoids have also proven useful in investigating other diseases that are difficult to study in animal models. Intestinal organoids infected with Clostridium difficile (Leslie et al, 2015) or gastric organoids infected with Helicobacter pylori (Bertaux-Skeirik et al, 2015;McCracken et al, 2014) have been essential in understanding some of the earliest processes in the epithelial response to pathogens. Additionally, with the advent of CRISPR/Cas9 gene editing, disease modeling, mutation correction and personalized medicine are now possible in patient-specific iPSC-derived organoids (Hockemeyer and Jaenisch, 2016).…”