Role of interferon-stimulated responsive element-like element in interleukin-8 promoter in Helicobacter pylori infection.
OBJECTIVE
Gastric mucosal interleukin (IL)-8 levels are related to the presence of both the cag pathogenicity island (PAI) and OipA. We investigated the regions of the IL-8 promoter and the upstream signaling involved in IL-8 gene transcription.


METHODS
We cocultured parental Helicobacter pylori and isogenic oipA, hopZ, or cagE gene knockout mutants with gastric cancer cells. The regulatory sites in the IL-8 promoter were examined by luciferase reporter gene assay, electrophoretic mobility shift assays, and immunoblot analyses. Phosphorylated signal transducers and activators of transcription 1 (STAT1) levels in the antral gastric mucosa were measured by enzyme-linked immunosorbent assay.


RESULTS
Maximal H. pylori -induced IL-8 gene transcription required the presence of the interferon-stimulated responsive element (ISRE)-like element, nuclear factor (NF)-kappa B and activator protein (AP)-1 binding sites. In vitro studies showed that OipA and the cag PAI were involved in inducing interferon regulatory factor (IRF)-1 to bind and activate the ISRE-like element and that the cag PAI, but not OipA, was involved in activating AP-1 and NF-kappa B. Both in vitro and in vivo studies showed that OipA, but not the cag PAI, was involved in STAT1 phosphorylation, as upstream signaling of IRF-1.


CONCLUSIONS
OipA and the cag PAI are both necessary for full activation of the IL-8 promoter but act via different pathways that diverge upstream of IRF-1 where only OipA is involved in the STAT1-IRF1-ISRE pathway. The mucosal inflammatory response to H. pylori infection is complex and involves different pathways converging on the IL-8 promoter.
Yamaoka
Yoshio
Y
Department of Medicine, Veterans Affairs Medicial Center and Baylor College of Medicine, Houston, TX 77030, USA. yyamaoka@bcm.tmc.edu
Kudo
Takahiko
T
Lu
Hong
H
Casola
Antonella
A
Brasier
Allan R
AR
Graham
David Y
DY
D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D005756:Gastritis / Q000276:immunology* / Q000382:microbiology / Q000503:physiopathology*; D005786:Gene Expression Regulation / Q000276:immunology; D017930:Genes, Reporter; D016481:Helicobacter Infections / Q000276:immunology* / Q000382:microbiology / Q000503:physiopathology*; D016480:Helicobacter pylori / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D050856:Interferon Regulatory Factor-1; D016209:Interleukin-8 / Q000235:genetics*; D016296:Mutagenesis; D016328:NF-kappa B / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000276:immunology; D013274:Stomach Neoplasms; D015534:Trans-Activators / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015533:Transcriptional Activation / Q000276:immunology
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; D016209:Interleukin-8; D016328:NF-kappa B; D010750:Phosphoproteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D018808:Transcription Factor AP-1; C080866:cagA protein, Helicobacter pylori