mRNA expression of cytokines and chemokines in the normal gastric surface mucous epithelial cell line GSM06 during bacterial infection with Helicobacter felis

Exaggerated expression of inflammatory mediators in vasoactive intestinal polypeptide knockout (VIP-/-) mice with cyclophosphamide (CYP)-induced cystitis

Vasoactive intestinal polypeptide (VIP) is an immunomodulatory neuropeptide distributed in micturition pathways. VIP(-/-) mice exhibit altered bladder function and neurochemical properties in micturition pathways after cyclophosphamide (CYP)-induced cystitis. Given VIP's role as an anti-inflammatory mediator, we hypothesized that VIP(-/-) mice would exhibit enhanced inflammatory mediator expression after cystitis. A mouse inflammatory cytokine and receptor RT2 profiler array was used to determine regulated transcripts in the urinary bladder of wild type (WT) and VIP(-/-) mice with or without CYP-induced cystitis (150 mg/kg; i.p.; 48 h). Four binary comparisons were made: WT control versus CYP treatment (48 h), VIP(-/-) control versus CYP treatment (48 h), WT control versus VIP(-/-) control, and WT with CYP treatment (48 h) versus VIP(-/-) with CYP treatment (48 h). The genes presented represent (1) greater than 1.5-fold change in either direction and (2) the p value is less than 0.05 for the comparison being made. Several regulated genes were validated using enzyme-linked immunoassays including IL-1beta and CXCL1. CYP treatment significantly (p < or = 0.001) increased expression of CXCL1 and IL-1beta in the urinary bladder of WT and VIP(-/-) mice, but expression in VIP(-/-) mice with CYP treatment was significantly (p < or = 0.001) greater (4.2- to 13-fold increase) than that observed in WT urinary bladder (3.6- to 5-fold increase). The data suggest that in VIP(-/-) mice with bladder inflammation, inflammatory mediators are increased above that observed in WT with CYP. This shift in balance may contribute to increased bladder dysfunction in VIP(-/-) mice with bladder inflammation and altered neurochemical expression in micturition pathways.

NF-kappaB activation during acute Helicobacter pylori infection in mice

Nuclear factor kappaB (NF-kappaB) plays a key regulatory role in host cell responses to Helicobacter pylori infection in humans. Although mice are routinely used as a model to study H. pylori pathogenesis, the role of NF-kappaB in murine cell responses to helicobacters has not been studied in detail. We thus investigated the abilities of different Helicobacter isolates to induce NF-kappaB-dependent responses in murine gastric epithelial cells (GECs) and in transgenic mice harboring an NF-kappaB-responsive lacZ reporter gene. H. pylori and Helicobacter felis strains up-regulated the synthesis in mouse GECs of the NF-kappaB-dependent chemokines KC (CXCL1) and MIP-2 (CXCL2). These responses were cag pathogenicity island (cagPAI) independent and could be abolished by pretreatment with a pharmacological inhibitor of NF-kappaB. Consistent with the in vitro data, experimental Helicobacter infection of transgenic mice resulted in increased numbers of GECs with nuclear beta-galactosidase activity, which is indicative of specific NF-kappaB activation. The numbers of beta-galactosidase-positive cells in mice were significantly increased at day 1 postinoculation with wild-type H. pylori strains harboring or not harboring a functional cagPAI, compared to naive animals (P = 0.007 and P = 0.04, respectively). Strikingly, however, no differences were observed in the levels of gastric NF-kappaB activation at day 1 postinoculation with H. felis or at day 30 or 135 postinoculation with H. pylori. This work demonstrates for the first time the induction of NF-kappaB activation within gastric mucosal cells during acute H. pylori infection. Furthermore, the data suggest that helicobacters may be able to regulate NF-kappaB signaling during chronic infection.

Hyperosmotic stress enhances interleukin-1beta expression in Helicobacter pylori-infected murine gastric epithelial cells in vitro

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-1beta (IL-1beta) is highly expressed in H. pylori-infected gastric mucosa. The aim of the present study was to determine if hyperosmotic stress induces IL-1beta 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-1beta mRNA and mature IL-1beta protein were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and an IL-1beta enzyme-linked immunosorbent assay (ELISA), respectively. IL-1beta 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-1beta mRNA, IL-1beta protein, ICE activity and apoptosis. Hyperosmotic stress alone also caused upregulation of IL-1beta mRNA and IL-1beta protein, enhanced ICE activity and accelerated apoptosis. Hyperosmotic stress accentuated the increases in IL-1beta mRNA, IL-1beta protein, ICE activity and apoptosis induced by H. pylori alone. Enhancement of IL-1beta 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-1beta protein in H. pylori-infected gastric epithelial cells, in part by upregulating IL-1beta 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.

Helicobacter pylori induces RANTES through activation of NF-kappa B

Helicobacter pylori-infected gastric mucosa displays a conspicuous infiltration of mononuclear cells and neutrophils. RANTES (short for "regulated upon activation, normal T cell expressed and secreted") is a chemoattractant cytokine (chemokine) important in the infiltration of T lymphocytes and monocytes. RANTES may therefore contribute to the cellular infiltrate in the H. pylori-infected gastric mucosa. The aim of this study was to analyze the molecular mechanism responsible for H. pylori-mediated RANTES expression. We observed that gastric epithelial cells produced RANTES upon coculture with H. pylori. In addition, H. pylori induced RANTES mRNA expression and an increase in luciferase activity in cells which were transfected with a luciferase reporter construct derived from the RANTES promoter, in gastric epithelial cells, indicating that the induction of RANTES production occurred at the transcriptional level. Induction of RANTES was dependent on an intact cag pathogenicity island. Activation of the RANTES promoter by H. pylori occurred through the action of NF-kappa B. Transfection of kinase-deficient mutants of I kappa B kinase (IKK) and NF-kappa B-inducing kinase (NIK) inhibited H. pylori-mediated RANTES activation. In contrast, tumor necrosis factor alpha- or interleukin-1/Toll-like receptor signaling molecules-such as mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1, MyD88, and interleukin-1 receptor-associated kinase-did not play a role in RANTES activation by H. pylori. Collectively, H. pylori induced NF-kappa B activation through an intracellular signaling pathway that involved IKK and NIK, leading to RANTES gene transcription. RANTES induction by H. pylori may play an important role in gastric inflammation.

Changes in urinary bladder cytokine mRNA and protein after cyclophosphamide-induced cystitis

Cyclophosphamide (CYP)-induced cystitis alters micturition function and produces reorganization of the micturition reflex. This reorganization may involve cytokine expression in the urinary bladder. These studies have determined candidate cytokines in the bladder that may contribute to the reorganization process. An RNase protection assay was used to measure changes in rat bladder cytokine mRNA [interferon-gamma (IFN)-gamma, interleukin-1alpha/beta (IL-1alpha/beta), IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, and tumor necrosis factor-alpha/beta (TNF-alpha/beta)] after acute (4 h), intermediate (48 h), or chronic (10 day) cystitis. The correlation between bladder cytokine mRNA and protein expression was also determined by immunoassay. Although at each time point after cystitis significant changes in bladder cytokine mRNA were observed, the magnitude differed (acute > intermediate > chronic). Acute cystitis demonstrated the most robust changes (P </= 0.005; IL-1beta, 330-fold increase; IL-2, 20-fold increase; IL-4, 8-fold increase; IL-6, 80-fold increase) in cytokine mRNA expression and TNF-alpha or TNF-beta mRNA were only increased (2-10-fold) after acute cystitis. More modest increases in cytokine mRNA expression were observed after 48-h or 10-day cystitis. Cytokine protein expression generally paralleled that of mRNA. Increased cytokine expression after CYP-induced cystitis, alone or in combination with other inflammatory mediators or growth factors, may contribute to altered lower urinary tract function after cystitis.