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Hyperosmotic stress enhances interleukin‐1β expression in Helicobacter pylori ‐infected murine gastric epithelial cells in vitro
Author(s) -
Zhang Songhua,
Yanaka Akinori,
Tauchi Masafumi,
Suzuki Hideo,
Shibahara Takeshi,
Matsui Hirofumi,
Nakahara Akira,
Tanaka Naomi
Publication year - 2006
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1111/j.1440-1746.2006.04293.x
Subject(s) - apoptosis , helicobacter pylori , gastric mucosa , microbiology and biotechnology , osmotic concentration , interleukin , in vitro , downregulation and upregulation , messenger rna , biology , medicine , immunology , cytokine , stomach , biochemistry , gene
Background and Aim: Gastric cancer is associated not only with Helicobacter pylori ( H. pylori ) infection, but also with the intake of a high salt diet. Interleukin‐1β (IL‐1β) is highly expressed in H. pylori ‐infected gastric mucosa. The aim of the present study was to determine if hyperosmotic stress induces IL‐1β expression in gastric epithelial cells in vitro . Method: Murine gastric epithelial cells, GSM06, were cultured with or without H. pylori (Sydney strain‐1) at different osmolarities in the range of 300–450 mOsM. Expressions of IL‐1β mRNA and mature IL‐1β protein were evaluated by reverse transcription‐polymerase chain reaction (RT‐PCR) and an IL‐1β enzyme‐linked immunosorbent assay (ELISA), respectively. IL‐1β converting enzyme (ICE) activity was measured by an ICE colorimetric assay. Apoptosis was evaluated by a single stranded‐DNA assay. Results: Addition of H. pylori at 300 mosM caused significant increases in IL‐1β mRNA, IL‐1β protein, ICE activity and apoptosis. Hyperosmotic stress alone also caused upregulation of IL‐1β mRNA and IL‐1β protein, enhanced ICE activity and accelerated apoptosis. Hyperosmotic stress accentuated the increases in IL‐1β mRNA, IL‐1β protein, ICE activity and apoptosis induced by H. pylori alone. Enhancement of IL‐1β protein release induced by hyperosmotic stress was significantly attenuated by an ICE inhibitor, Z‐YVAD‐FMK. Conclusions: Hyperosmotic stress enhances the release of bioactive mature IL‐1β protein in H. pylori ‐infected gastric epithelial cells, in part by upregulating IL‐1β mRNA expression, and in part by enhancing ICE activity. These results may explain the mechanisms by which chronic intake of a high salt diet increases the risk of gastric cancer among H. pylori ‐infected human subjects.