Abstract
The cell surface mucin MUC1 is an important host factor limiting Helicobacter pylori (H. pylori) pathogenesis in both humans and mice by providing a protective barrier and modulating mucosal epithelial and leukocyte responses. The aim of this study was to establish the time-course of molecular events in MUC1-modulated gene expression profiles in response to H. pylori infection in wild type (WT) and MUC1-deficient mice using microarray-determined mRNA expression, gene network analysis and Ingenuity Pathway Analysis (IPA). A time-course over the first 72 h of infection showed significantly higher mucosal loads of bacteria at 8 h of infection in Muc1−/− mice compared with WT, confirming its importance in the early stages of infection (P = 0.0003). Microarray analysis revealed 266 differentially expressed genes at one or more time-points over 72 h in the gastric mucosa of Muc1−/− mice compared with WT control using a threshold of 2-fold change. The SPINK1 pancreatic cancer canonical pathway was strongly inhibited in Muc1−/− mice compared with WT at sham and 8 h infection (P = 6.08E-14 and P = 2.25 E-19, respectively) but potently activated at 24 and 72 h post-infection (P = 1.38E-22 and P = 5.87E-13, respectively). The changes in this pathway are reflective of higher expression of genes mediating digestion and absorption of lipids, carbohydrates, and proteins at sham and 8 h infection in the absence of MUC1, but that this transcriptional signature is highly down regulated as infection progresses in the absence of MUC1. Uninfected Muc1−/− gastric tissue was highly enriched for expression of factors involved in lipid metabolism and 8 h infection further activated this network compared with WT. As infection progressed, a network of antimicrobial and anti-inflammatory response genes was more highly activated in Muc1−/− than WT mice. Key target genes identified by time-course microarrays were independently validated using RT-qPCR. These results highlight the dynamic interplay between the host and H. pylori, and the role of MUC1 in host defense, and provide a general picture of changes in cellular gene expression modulated by MUC1 in a time-dependent manner in response to H. pylori infection.
Highlights
Chronic infection with the gram-negative bacterium Helicobacter pylori (H. pylori) induces a chronic gastritis in susceptible individuals, which can lead to gastric ulcers, and adenocarcinoma, a malignancy of the glandular epithelium of the stomach
Consistent with our previous finding of higher H. pylori colonization in Muc1−/− mice 24 h after infection, we found that Muc1−/− mice displayed ∼10-fold greater levels of H. pylori colonization in the stomach compared with wild-type (WT) mice as early as 8 h post-infection
To better understand the molecular mechanism by which MUC1 mediates the inhibition of gastric H. pylori colonization, we applied a microarray approach to examine the effect of Muc1 gene ablation on gastric gene expression in the absence of infection
Summary
Chronic infection with the gram-negative bacterium Helicobacter pylori (H. pylori) induces a chronic gastritis in susceptible individuals, which can lead to gastric ulcers, and adenocarcinoma, a malignancy of the glandular epithelium of the stomach. One host factor linked with susceptibility to Helicobacterassociated gastritis and gastric cancer is allelic variation in the gene that encodes the MUC1 mucin. Several epidemiologic studies have linked MUC1 polymorphisms in humans with susceptibility to H. pylori-induced disease (Carvalho et al, 1997; Vinall et al, 2002), suggesting a direct effect of MUC1 polymorphisms on the development of Helicobacterassociated pathology. We have shown that mice deficient in MUC1 are more susceptible to infection by H. pylori and that differences emerge very early in infection and are sustained, with characteristically more severe chronic inflammation (McGuckin et al, 2007). We have shown that MUC1 in gastric epithelial cells limits H. pylori infection both by steric hindrance and by acting as a releasable decoy (Linden et al, 2009), and that MUC1 in macrophages suppresses inflammation by negatively regulating the inflammasome (Ng et al, 2016). The aim of this study was to elucidate the time-course of molecular events and dynamic networks in gastric tissue from Muc1−/− and wild type (WT) mice in response to the very early stages of H. pylori infection, and to validate key target genes involved in the molecular changes in gastric tissue during H. pylori infection
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
