OBJECTIVETo study COX-2 expression in H. pylori infected gastric mucosal epithelia and its significance in the carcinogenesis of the stomach.

METHODSRapid urease test and histological examination with basic magnenta staining were used to assess the status of H. pylori infection in the stomach. COX-2 was detected immunohistochemically.

RESULTSCOX-2 immunostaining was positive in 1 out of 12 cases with H. pylori-negative gastric mucosa and also in 1 out of 10 cases with H. pylori-positive gastric mucosa without macroscopic alterations, while COX-2 expression was found to be positive in 5 out of 9 cases with H. pylori related superficial gastritis with mucosal erosions. COX-2 expression was detected in 5 out of 10 cases with H. pylori-positive mild atrophic gastritis, 8 out of 10 cases with H. pylori-positive moderate-severe atrophic gastritis and intestinal metaplasia, and 6 out of 8 cases with H. pylori-positive moderate-severe dysplasia. COX-2 expression was positive in 22 out of 32 cases of gastric cancer.

CONCLUSIONH. pylori may induce COX-2 expression of gastric mucosal epithelia in chronic superficial gastritis, which is related to the development of mucosal injury. According to gastric mucosal carcinogenesis pattern up-regulation of COX-2 expression is associated with gastric mucosal carcinogenesis, and involved in the early development of premalignant lesions.

Adult ; Aged ; Cyclooxygenase 2 ; biosynthesis ; genetics ; Female ; Gastric Mucosa ; enzymology ; Gastritis ; enzymology ; microbiology ; Helicobacter Infections ; enzymology ; Helicobacter pylori ; Humans ; Male ; Middle Aged

The gene encoding urease subunit A (ureA) of Helicobacter pylori (H. pylori) was cloned from H. pylori isolate by polymerase chain reaction (PCR). Sterile distilled water instead of DNA served as negative control. The nucleotide sequence of the amplified product was determined. Homologous analysis of the ureA against that reported by Clayton CL and the GenBank and SwissProt databases were performed with the BLAST program at the Genome Net through the Internet. 0.8 kb PCR product was amplified from all H. pylori clinical isolators. The nucleotide sequence of the ureA was determined. The nucleotide sequence of the ureA began with ATG as the initiation codon and terminated in TAA as stop codon. The coding regions had a 44% G + C content. The DNA sequence was 98% homologous to that reported by Clayton CL (688 out of 702 residues were identical). The derived amino-acid sequences of the ureA were 99% homologous to that reported by Clayton CL (232 out of 234 residues were identical). The nucleotide sequence and the predicted protein showed significant homology to ureA of H. pylori in the NCBI Entrez database.
Base Sequence ; Cloning, Molecular ; DNA, Bacterial/chemistry ; DNA, Bacterial/genetics ; *Genes, Bacterial ; Genetic Code ; Helicobacter Infections/microbiology ; Helicobacter pylori/enzymology ; Helicobacter pylori/*genetics ; Helicobacter pylori/isolation & purification ; Molecular Sequence Data ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Transcription, Genetic ; Urease/*genetics ; Urease/metabolism

PURPOSE: The role of the Ferric Uptake Regulator (FUR) in the acid resistance of Helicobacter pylori (H. pylori) has been thought to be independent of urease. However, we demonstrated in this study that Fur influences urease activity. MATERIALS AND METHODS: A fur knockout mutant of H. pylori was constructed by replacing the Fur gene with a kanamycin resistant marker gene. The wild-type H. pylori and fur mutant were compared for survival. The integrity of the inner membrane of the bacteria was evaluated by confocal microscopy using membrane-permeant and -impermeant fluorescent DNA probes. Urease activity of intact H. pylori was measured between pH 3 and 8. Real time PCR of both strains was performed for urease genes including ureI, ureE, ureF, ureG, and ureH. RESULTS: The fur deletion affected the survival of H. pylori at pH 4. The urease activity curve of the intact fur mutant showed the same shape as the wild-type but was 3-fold lower than the wild-type at a pH of less than 5. Real time PCR revealed that the expression of all genes was consistently down-regulated in the fur mutant. CONCLUSION: The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.
Bacterial Proteins/genetics/*physiology ; Helicobacter pylori/*enzymology/genetics ; Hydrogen-Ion Concentration ; Microscopy, Confocal ; Models, Biological ; Mutation ; Repressor Proteins/genetics/*physiology ; Urease/*metabolism

The gene encoding urease subunit A (ureA) of Helicobacter pylori (H. pylori) was cloned from H. pylori isolate by polymerase chain reaction (PCR). Sterile distilled water instead of DNA served as negative control. The nucleotide sequence of the amplified product was determined. Homologous analysis of the ureA against that reported by Clayton CL and the GenBank and SwissProt databases were performed with the BLAST program at the Genome Net through the Internet. 0.8 kb PCR product was amplified from all H. pylori clinical isolators. The nucleotide sequence of the ureA was determined. The nucleotide sequence of the ureA began with ATG as the initiation codon and terminated in TAA as stop codon. The coding regions had a 44% G + C content. The DNA sequence was 98% homologous to that reported by Clayton CL (688 out of 702 residues were identical). The derived amino-acid sequences of the ureA were 99% homologous to that reported by Clayton CL (232 out of 234 residues were identical). The nucleotide sequence and the predicted protein showed significant homology to ureA of H. pylori in the NCBI Entrez database.
Base Sequence ; Cloning, Molecular ; DNA, Bacterial ; chemistry ; genetics ; Genes, Bacterial ; Genetic Code ; Helicobacter Infections ; microbiology ; Helicobacter pylori ; enzymology ; genetics ; isolation & purification ; Humans ; Molecular Sequence Data ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Transcription, Genetic ; Urease ; genetics ; metabolism

OBJECTIVETo clone Helicobacter pylori ureB gene, to construct prokaryotic expression system of the gene and to identify immunogenicity of the fusion protein.

METHODSThe ureB gene from a clinical isolate Y06 of H.pylori was amplified by high fidelity PCR. The nucleotide sequence of the target DNA amplification fragment was sequenced after T-A cloning. The expression vector pET32a with inserted ureB gene was constructed. ureB fusion protein was expressed in E.coli strain BL21DE3 induced by IPTG at different dosages. Western blot using antibody against whole cell of H.pylori as well as immunodiffusion assay using antiserum of rabbit against the fusion protein was applied to determine immunogenicity of the fusion protein.

RESULTSIn comparison with the reported corresponding sequences, the homology of nucleotide sequence of the cloned ureB gene was from 96.88% approximate, equals 97.82%, while the homology of its putative amino acid sequence was as high as 99.65% approximate, equals 99.82%. The expression output of UreB protein in pET32a-ureB-BL21DE3 system was approximately 40%of the total bacterial proteins. UreB protein was able to combine with antibody against whole cell of H.pylori and induce rabbit to produce high titer antibody after the animal was immunized with the protein.

CONCLUSIONAn expression system with high efficiency of H.pylori ureB gene has been established successfully. The expressed UreB protein with satisfactory immunogenicity and immunoreactivity can be used as antigen in H.pylori vaccine.

Animals ; Bacterial Vaccines ; immunology ; Base Sequence ; Helicobacter pylori ; enzymology ; immunology ; Humans ; Molecular Sequence Data ; Polymerase Chain Reaction ; Rabbits ; Recombinant Fusion Proteins ; immunology ; Urease ; genetics ; immunology ; Vaccines, Synthetic ; immunology

OBJECTIVETo clone UreB gene of Helicobacter pylori (H. pylori) isolated from children to pGEX-4T-1 expression plasmid, and do sequence analysis.

METHODSA pair of specific primer was designed according to H. pylori UreB gene in the GenBank. Using H. pylori strains isolated from children as a template, a UreB gene was obtained by PCR. After EcoR I and Not I digestion, the PCR production was linked with pGEX-4T-1 which was digested with the same enzymes. The recombinant plasmid was transformed into E.coli BL21 and identified by double enzyme digestion and sequence analysis. The sequence results were compared with the gene sequence in the GenBank.

RESULTSA UreB gene was successfully amplified from children's H. pylori strain GZCH1. It was 1710 bp in size. The objective band was identified by double enzyme digestion. DNA sequence showed that UreB was in the correct open reading frame. The sequence comparison analysis showed that DNA and amino acid sequence identities of UreB gene with other strains were 98%. The sequence of UreB of H. pylori strain GZCH1 was submitted to GenBank (accession number:FJ455126).

CONCLUSIONSUreB of H. pylori strain GZCH1 is successfully cloned to pGEX-4T-1, which provides a basis for research of oral H. pylori vaccine.

Amino Acid Sequence ; Bacterial Vaccines ; immunology ; Child ; Cloning, Molecular ; Helicobacter pylori ; enzymology ; immunology ; Humans ; Male ; Molecular Sequence Data ; Urease ; chemistry ; genetics ; immunology

OBJECTIVETo prepare the live recombinant vaccine of attenuated Salmonella typhimurium SL3261 expressing Helicobacter pylori (H. pylori) B subunit (UreB) and to determine whether it could be used as an oral vaccine against H. pylori infection.

METHODSUsing genomic DNA of H. pylori Sydney strain (SSI) as template, the H. pylori UreB gene fragment was amplified by PCR and subcloned into the expression vector pTC01. The recombinant plasmid pTC01-UreB was then transferred into LB5000 to obtain modified forms, and further conversed into the attenuated Salmonella typhimurium SL3261 to obtain recombinant SL3261/pCT01-UreB as an oral immunization reagent, which was then used to orally immunize Balb/c mice twice at a three-week interval. Twelve weeks later, anti-UreB IgA antibodies in intestinal fluid and IgG antibodies in sera were determined by ELISA. The relating data in control groups (including body weight, gastric inflammation, etc.) were also collected.

RESULTSThe sequencing analysis showed that the UreB gene fragment amplified by PCR was consistent with the sequence of the H. pylori UreB gene. The restriction enzyme digestion revealed that the correct pTC01-UreB was obtained. SDS-PAGE and Western blot showed that a 61KD protein was expressed in SL3261/pTC01-UreB, which could be recognized by anti-H. pylori UreB antiserum and was absent in the control containing only Salmonella typhimurium SL3261 strain. The multiple oral immunization with SL3261/pTC01-UreB could significantly induce H. pylori specific mucosal IgA response as well as serum IgG responses. IFN-gamma and IL-10 levels were significantly increased in SL3261/pTC01-UreB group, and no obvious side effect and change in gastric inflammation were observed.

CONCLUSIONThe attenuated vaccine of Salmonella typhimurium expressing H. pylori UreB can be used as an oral vaccine against H. pylori infection.

Animals ; Antibodies, Bacterial ; blood ; Bacterial Vaccines ; administration & dosage ; immunology ; Female ; Gene Expression Regulation, Bacterial ; Gene Expression Regulation, Enzymologic ; Helicobacter Infections ; immunology ; prevention & control ; Helicobacter pylori ; enzymology ; genetics ; immunology ; Immunoglobulin G ; blood ; Interferon-gamma ; metabolism ; Interleukin-10 ; metabolism ; Mice ; Mice, Inbred BALB C ; Salmonella typhimurium ; genetics ; immunology ; metabolism ; Urease ; genetics ; immunology ; metabolism ; Vaccines, Attenuated ; genetics ; immunology ; Weight Loss

Helicobacter pylori (H. pylori) is an important risk factor for chronic gastritis, peptic ulcer, and gastric cancer. Proteinase-activated receptor 2 (PAR2), subgroup of G-protein coupled receptor family, is highly expressed in gastric cancer, and chronic expression of cyclooxygenase-2 (COX-2) plays an important role in H. pylori-associated gastric carcinogenesis and inflammation. We previously demonstrated that H. pylori induced the expression of PAR2 and COX-2 in gastric epithelial cells. Present study aims to investigate whether COX-2 expression induced by H. pylori in Korean isolates is mediated by PAR2 via activation of Gi protein and Src kinase in gastric epithelial AGS cells. Results showed that H. pylori-induced COX-2 expression was inhibited in the cells transfected with antisense oligonucleotide for PAR2 or treated with Gi protein blocker pertussis toxin, Src kinase inhibitor herbimycin A and soybean trypsin inbitor, indicating that COX-2 expression is mediated by PAR2 through activation of Gi protein and Src kinase in gastric epithelial cells infected with H. pylori in Korean isolates. Thus, targeting the activation of PAR2 may be beneficial for prevention or treatment of gastric inflammation and carcinogenesis associated with H. pylori infection.
Benzoquinones/*pharmacology ; Cell Line, Tumor ; Cyclooxygenase 2/genetics/*metabolism ; Epithelial Cells/enzymology/metabolism/microbiology ; GTP-Binding Protein alpha Subunits, Gi-Go/metabolism ; Gastric Mucosa/enzymology/metabolism/*microbiology ; *Helicobacter pylori ; Humans ; Lactams, Macrocyclic/*pharmacology ; Oligonucleotides, Antisense ; Pertussis Toxin/*pharmacology ; RNA, Messenger/metabolism ; Receptor, PAR-2/*physiology ; src-Family Kinases/metabolism

OBJECTIVECytotoxin-associated protein (CagA) of H. pylori has been confirmed to be closely associated with gastric inflammation and tumorigenesis, but the mechanism behind it is little understood. In this study, we try to determine roles of CagA(+) strain in activating PI3K/Akt1 signaling pathway, and affecting expression of p21(WAF1/CIP1) and p27(KIP1), and also in releasing IL-8 in host cells.

METHODSAkt1 phosphorylation and IL-8 levels of CagA(+) and CagA⁻ strain infected AGS cells were detected by ELISAs. Two quantitative RT-PCRs were established to measure p21(WAF1/CIP1) and p27(KIP1) mRNA levels in the CagA(+) and CagA⁻ strain infected cells. LY294002, an inhibitor of PI3K/Akt pathway, was used to define effect of the pathway in IL-8 release.

RESULTSCagA(+) strain could induce an obvious elevation of Akt1 phosphorylation in the infected AGS cells while CagA? strain failed to do so. The CagA(+) H. pylori strain infected AGS cells showed significant drops both in p21(WAF1/CIP1) and p27(KIP1) mRNA levels, whereas the CagA⁻ H. pylori strain caused a remarkable increase in p21(WAF1/CIP1) mRNA without affecting p27(KIP1) gene transcription in the AGS cells. Both the CagA(+) and CagA⁻ H. pylori strains enabled AGS cells to produce close elevated levels of IL-8, and the LY294002 block resulted in unexpected elevations of IL-8 levels.

CONCLUSIONSCagA can activate PI3K/Akt1 pathway that plays an inhibitory role in IL-8 release in H. pylori infected AGS cells. Activation of PI3K/Akt1 pathway and subsequent negative regulation of p21(WAF1/CIP1) and p27(KIP1) expression might be involved in CagA-associated carcinogenesis.

Antigens, Bacterial ; genetics ; physiology ; Bacterial Proteins ; genetics ; physiology ; Cell Line ; Cyclin-Dependent Kinase Inhibitor p21 ; biosynthesis ; Cyclin-Dependent Kinase Inhibitor p27 ; Gastric Mucosa ; cytology ; enzymology ; microbiology ; Helicobacter pylori ; metabolism ; pathogenicity ; physiology ; Humans ; Interleukin-8 ; secretion ; Intracellular Signaling Peptides and Proteins ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; Transcription, Genetic ; Virulence