The mouse gastric surface epithelial cell and its response to early Helicobacter pylori infection

Helicobacter pylori infection is the main risk factor for gastric cancer. H. pylori easily develop antibiotic resistance and evade host defenses. In-depth knowledge of the first barrier that H. pylori encounter, the gastric surface mucus-producing epithelial cells (SMCs), may enable improved treatment and prevention. This study aimed to characterize SMC gene expression, mucus glycosylation, and identify how H. pylori colonization affects these parameters. The glycosylation of eight H. pylori-infected and eight sham control mice was characterized by mass spectrometry. SMCs from five infected and five sham control mice were extracted with laser microdissection (LCM) and sequenced with RNA sequencing (RNA-Seq). SMCs were characterized by high gene expression for proteins secreted into mucus (Tff1, Gkn1, Gkn2, Psca, and Muc5ac), mitoribosome RNA, and cytoskeleton proteins. Mucin glycans were large, complex, heavily fucosylated, and dense with H-antigen motifs. Two main glycosylation pathways ending in H-antigen glycans were identified and corroborated with glycosyltransferase expression. Glycosylation was consistent between H. pylori-infected and sham control mice. RNA-Seq data was analysed for differential gene expression, gene set enrichment analysis, and network analysis of functionally-related genes. The analyses revealed that genes required for protein synthesis and oxidative phosphorylation were down-regulated in infected mice. Most up-regulated genes were either interferon-stimulated genes or able to induce interferon production themselves. Depletion of Nkx6-3 occurred in the infected mice, indicating initiation of a pre-cancerous cascade. LCM RNA-Seq of SMCs was thus feasible and enabled characterization of the SMC and definition of a gene set showing how H. pylori infection affects SMCs.