Immortalized gastric epithelial cell line GSM06 synthesizes hyaluronan under the influence of simian virus 40 large T-antigen expression

The Helicobacter heilmannii hofE and hofF Genes are Essential for Colonization of the Gastric Mucosa and Play a Role in IL-1β-Induced Gastric MUC13 Expression

BACKGROUND

Helicobacter heilmannii is a zoonotic bacterium associated with gastric disease in humans. We recently showed that H. heilmannii binds to human gastric mucins and epithelial cells and highlighted a potential role for the murine Muc13 mucin in gastric Helicobacter colonization. The aims of this study were to investigate the role of the H. heilmannii hof gene locus encoding HofH/F/E/G/C/D in adhesion to the gastric mucosa and induction of increased gastric Muc13 expression.

METHODS

Bacterial hof gene and host gene expression experiments, Helicobacter binding assays and experimental infection studies in mice were performed. H. pylori and its ΔhofF mutant were included for comparison.

RESULTS

Helicobacter heilmannii strains lacking HofE or HofF showed a clear decrease in binding to gastric mucins and epithelial cells as well as a lower gastric colonization level in the stomach of Balb/c mice at 4 and 9 weeks post-infection compared to the H. heilmannii wildtype strain. Interestingly, H. heilmannii ΔhofE and ΔhofF and H. pylori ΔhofF did not induce an increased expression of MUC13 in human gastric epithelial cells and of Muc13 in the stomach of mice. Finally, we demonstrated that IL-1β is induced in the stomach as a response to Helicobacter colonization which on its turn is involved in the expression of MUC13/Muc13 in the gastric epithelium.

CONCLUSION

These novel results in Helicobacter research identified H. heilmannii HofE and HofF as adhesins and suggest an important role of H. heilmannii HofE and HofF and H. pylori HofF in IL-1β-induced gastric MUC13/Muc13 expression.

Helicobacter pylori infection of gastrointestinal epithelial cells in vitro induces mesenchymal stem cell migration through an NF-κB-dependent pathway

The role of bone marrow-derived mesenchymal stem cells (MSC) in the physiology of the gastrointestinal tract epithelium is currently not well established. These cells can be recruited in response to inflammation due to epithelial damage, home, and participate in tissue repair. In addition, in the case of tissue repair failure, these cells could transform and be at the origin of carcinomas. However, the chemoattractant molecules responsible for MSC recruitment and migration in response to epithelial damage, and particularly to Helicobacter pylori infection, remain unknown although the role of some chemokines has been suggested. This work aimed to get insight into the mechanisms of mouse MSC migration during in vitro infection of mouse gastrointestinal epithelial cells by H. pylori. Using a cell culture insert system, we showed that infection of gastrointestinal epithelial cells by different H. pylori strains is able to stimulate the migration of MSC. This mechanism involves the secretion by infected epithelial cells of multiple cytokines, with a major role of TNFα, mainly via a Nuclear Factor-kappa B-dependent pathway. This study provides the first evidence of the role of H. pylori infection in MSC migration and paves the way to a better understanding of the role of bone marrow-derived stem cells in gastric pathophysiology and carcinogenesis.

A novel in vitro infection model of Helicobacter pylori using mucin-producing murine gastric surface mucous cells

BACKGROUND

Helicobacter pylori is found within the gastric surface mucous gel layer and in the epithelial surface. Gastric cancer cells have been used in experimental H. pylori infection in vitro, although cancer cells have some abnormalities in cellular properties. The aim of this study was to develop an in vitro H. pylori infection model using normal gastric surface cells that produce gastric mucin.

MATERIALS AND METHODS

Normal murine gastric surface mucous cells (GSM06) were cultured by the liquid interface method using a serum-free medium and a collagen gel containing a fibroblast cell line (L929) and infected with H. pylori. Infection by H. pylori was assessed by enumerating the colony-forming units (CFU) of H. pylori adhered to GSM06 cells and by transmission electron microscopy. The production of mucin was determined by a lectin binding assay, sugar analysis, and MUC5AC gene expression.

RESULTS

GSM06 cells cultured under these conditions produced mucin containing N-acetylgalactosamine and MUC5AC as the core protein. Significantly higher numbers of H. pylori adhered to GSM06 cells under mucin-producing conditions than under nonproducing conditions. Microscopic observation showed a filamentous structure resembling a type IV secretion system apparatus formed between the surface of GSM06 cells and H. pylori.

CONCLUSIONS

This study demonstrates a novel in vitro H. pylori infection model using mucin-producing murine GSM06 cells for early stages of infection.

Development and characterization of conditionally immortalized gastric epithelial cell lines from transgenic rats harboring temperature-sensitive simian virus 40 large T-antigen gene

Conditionally immortalized gastric epithelial cell lines were established from transgenic rats harboring temperature-sensitive simian virus 40 (tsSV40) large T-antigen gene. Gastric mucosal cells and epithelial tissues isolated from the stomach of the transgenic rats were cultured at permissive temperature (33 degrees C), and proliferative cells were cloned by colony formation. Six cell lines (designated as RGE1-01, RGE1-02, RGE1-03, RGE1-21, RGE1-22 and RGE2-01) showing epithelial-like morphology have been established. All cells grew at 33 degrees C, but did not at nonpermissive temperature (39 degrees C). High expression level of large T-antigen in the nuclei was observed at 33 degrees C, whereas the expression level was gradually decreased in a time-dependent manner at 39 degrees C. These results suggest that the temperature-sensitive growth characteristics arise as a result of a function of the tsSV40 large T-antigen. None of the cell lines were transformed as judged by anchorage-independent growth assay. Immunocytochemical findings indicated that all cells expressed epithelial cell markers including cytoskeletal (cytokeratin and actin), basement membrane (laminin and collagen type IV) and junctional complex (ZO-1 and desmoplakin I+II) proteins at 33 degrees C. All cells expressed mRNA of cathepsin E, a pit cell marker. Moreover, transepithelial resistance was observed between apical and basolateral sides in the cells. RGE1-22 cells produced prostaglandin E(2). Levels of mRNA for cathepsin E, transepithelial resistance and prostaglandin E(2) were influenced by the nonpermissive temperature. Thus, these conditionally immortalized gastric cell lines which preserve some epithelial cell characteristics will provide a useful in vitro model of gastric epithelium.

Characterization and application of a gastric surface mucous cell line GSM06 established from temperature-sensitive simian virus 40 large T-antigen transgenic mice

It has been indicated that transgenic mouse harboring a temperature-sensitive simian virus 40 large T-antigen gene is useful for establishing cell lines from tissues that have proved difficult to culture in vitro. The gastric surface mucous cell line GSM06 was established from a primary culture of gastric fundic mucosal cells of the transgenic mice. GSM06 cells showed temperature-sensitive growth in culture and expressed large T-antigen at a permissive temperature (33 degrees C) but not at a nonpermissive temperature (39 degrees C). At 39 degrees C, the cells produced periodic acid-Schiff positive glycoconjugates that formed a mucous sheet like the gastric surface mucosa in the stomach. Insulin markedly increased the production of glycoconjugates. In addition, proprotein-processing endoprotease furin suppression retarded cell growth, but accelerated cell differentiation. An air-liquid interface promoted the differentiation of GSM06 cells in a reconstruction culture with nitrocellulose membrane and collagen gel. The gastric surface mucous cell line GSM06 with unique characteristics, therefore, should be useful as an in vitro model of the gastric mucosa for physiological and pharmacological investigations. Moreover, experiments using immortalized cells established in vitro and having specific functions may offer an alternative to experiments using living animals and thereby offer a solution to this ethical issue.

Establishment and characterization of a colonic epithelial cell line MCE301 from transgenic mice harboring temperature-sensitive simian virus 40 large T-antigen gene

We produced an immortalized colonic epithelial cell line, MCE301, using fetal mice transgenic for the temperature-sensitive simian virus 40 large T-antigen gene. MCE301 cells showed epithelial-like morphology and maintained tight connections with neighboring cells. The cells grew at a permissive temperature (33 degrees C), but the growth of the cells was significantly prevented at the nonpermissive temperature (39 degrees C). The cells expressed large T-antigen at 33 degrees C but not at 39 degrees C. MCE301 cells were not transformed, as judged by the absence of anchorage-independent growth in soft agar gel and lack of tumor formation in nude mice. Electron microscopic studies showed that the cells formed microvilli-like structures on the cell surface and junctional complexes such as tight junctions and desmosomes between the cells. The cells expressed cytosketal (acidic cytokeratins and actin), basement membrane (laminin and collagen type IV) and junctional complex proteins (ZO-1 and desmoplakin I + II), as judged by specific antibodies. Fetal bovine serum, epidermal growth factor, insulin-like growth factor and insulin significantly increased the cell growth at 33 degrees C. Moreover, MCE301 cells expressed colonic mucin Muc2 mRNA as demonstrated by reverse transcriptase-polymerase chain reaction, indicating that the cells originate from mucus-secreting cells. Alkaline phosphatase, a brush border-associated enzyme, was detected in the cells. Sodium butyrate (2 mM), an inducer of cellular differentiation, markedly elevated alkaline phosphatase activity. Thus, the present mouse colonic epithelial cell line MCE301 possessing these unique characteristics should provide a useful in vitro model of colonic epithelium.

Characterization of JOK-1, a human gastric epithelial cell line

Human gastric epithelial cells were isolated from samples of human gastric lining and immortalized with simian virus 40 (SV40) to generate the stable human gastric epithelial cell line "JOK-l." These cells express conventional epithelial markers (vimentin, cytokeratin-18, occludin, N- and E-cadherins, beta-catenin, ZO-1, ZO-2, mucin, epithelial specific antigen) as well as SV40 large T-antigen. These cells rapidly externalized E-cadherin in response to acidic medium, and exhibited epithelial-like barrier properties that are also regulated by media pH. In contrast, the kidney epithelial cell line "MDCK" also expresses several epithelial markers (vimentin, cytokeratin-18, occludin, N- and E-cadherin, beta-catenin, ZO-1, ZO-2, epithelial specific antigen), but does not express mucin, or large T-antigen. However, MDCK rapidly internalize their E-cadherin from the cell surface and increase the solute flux in an acidic medium. These data suggest that the JOK-1 cell line is a potentially useful cell line for developing models of gastric epithelial function, development, and disease.