Quantitative analysis of representative proteome components and clustering of Helicobacter pylori clinical strains.

BACKGROUND: Several Helicobacter pylori proteins have been reported to be associated with severe symptoms of gastric disease. However, expression levels of most of these disease-associated proteins require further evaluation in order to clarify their relationships with gastric disease patterns. Representative proteome components of 71 clinical isolates of H. pylori were analyzed quantitatively to determine whether the protein expression levels were associated with gastric diseases and to cluster clinical isolates. METHODS: After two-dimensional electrophoresis (2-DE) of H. pylori isolates, spot intensities were analyzed using pdquest 2-D Gel Analysis Software. The intensities of 10 representative protein spots, identified by peptide fingerprinting using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using quadrupole TOF MS, were subjected to the nonparametric Mann-Whitney test and hierarchical agglomerative cluster analysis. The relationship between clusters and gastric diseases was analyzed by the chi-squared test. RESULTS: Although the spot intensities of the 10 representative proteins were highly variable within each gastric disease group, the expression levels of CagA, UreB, GroEL, EF-Tu, EF-P, TagD, and FldA showed some significant differences among the gastric disease patterns. On the basis of the 10 target protein intensities, hierarchical agglomerative cluster analysis generated a dendrogram with clusters indicative of chronic gastritis/gastric cancers and gastric/duodenal ulcers. CONCLUSION: These results indicated that quantitative analysis of proteome components is a feasible method for examining disease-associated proteins and clustering clinical strains of H. pylori.

Effect of Mycoplasma pneumoniae lysate on interleukin-8 gene expression in human respiratory epithelial cells.

STUDY OBJECTIVES: Mycoplasma pneumoniae is a common cause of lower respiratory disease. Several studies have suggested that respiratory infection by M pneumoniae is associated with reactive airway disease and asthma. Interleukin (IL)-8 has been suggested to have a role in the pathogenesis of the allergic inflammation of bronchial asthma, and is well known to be expressed in bronchial epithelial cells. MEASUREMENTS: An examination was carried out into the effect of M pneumoniae lysate (MPL) and the role of mitogen-activated protein kinases (MAPKs) and extracellular signal-regulated kinase (ERK) on IL-8 expression in human lung epithelial cells. A549 cells were seeded at a density of 5 x 10(4) cells per well and incubated in basal medium for a further 24 h. IL-8 levels were determined by an enzyme-linked immunosorbent assay. MAPK phosphorylation was assessed by Western blotting. RESULTS: In A549 cells, MPL induced IL-8 release in a time- and dose-dependent manner. Pretreatment with PD 98059, which blocks the activation of MAPK/ERK kinase 1, inhibited MPL-induced IL-8 production by 64.4% at 25 micromol/L. Stimulation of A549 cells by MPL also caused an increase in the activity of ERK, compared with the nonstimulated cells. The MPL stimulation had no effect on the activities of p38. CONCLUSION: These observations suggest that activation of ERK by MPL may be one of the mechanisms that result in an increase of the production of IL-8.

Detection of Helicobacter pylori in gastric mucosa of patients with gastroduodenal diseases by PCR-restriction analysis using the RNA polymerase gene (rpoB).

A novel PCR restriction analysis method using the RNA polymerase beta-subunit- coding gene (rpoB) was employed to both detect and identify Helicobacter pylori in biopsy specimens and culture isolates. The rpoB DNAs (458 bp) were specifically amplified by PCR with the Helicobacter-specific primers (HF and HR). Based on the determined rpoB sequences of the culture isolates, an H. pylori-specific restriction site, Tru9I, was found. H. pylori can be identified by observing two discernible DNA fragments (288 and 138 bp) after Tru9I digestion and agarose gel electrophoresis. The rpoB PCR and subsequent restriction analysis (PRA) enabled the specific detection and identification of H. pylori in biopsy specimens from patients with gastroduodenal diseases. The rpoB PRA conferred a compatible or a slightly higher positive rate (53.7%) than did the Campylobacter-like organism (CLO) test (50.4%) and glmM PCR (48.8%), suggesting that it is useful for diagnosing an H. pylori infection without culture in the clinical laboratory.

A change in PBP1 is involved in amoxicillin resistance of clinical isolates of Helicobacter pylori.

Reports on the isolation of amoxicillin-resistant Helicobacter pylori are increasing worldwide, which may cause serious problems in eradication therapy. To elucidate the mechanism of amoxicillin resistance of H. pylori, penicillin-binding proteins (PBPs) of amoxicillin-resistant strains isolated in Korea were analysed. Three PBPs (66, 63 and 60 kDa) were identified in both amoxicillin-resistant and -susceptible strains using biotinylated ampicillin, and the PBP profiles were very similar irrespective of the difference in amoxicillin susceptibility. We obtained clones with moderate resistance from an amoxicillin-susceptible strain, HPK5, by transformation with genomic DNA from an amoxicillin-resistant strain, HPA116. In a resistance-induced clone, HPO1, the affinity of PBP1 for amoxicillin was reduced. The pbp1 genes from HPA116, HPO1 and HPK5 were cloned and sequenced. The nucleotide sequences of pbp1 from HPA116 and HPO1 were almost identical, whereas that of HPK5 was quite different. Both the ORFs of HPA116 and HPO1 pbp1 have four substitutions and one insertion of amino acid residues compared with those of HPK5 and other sensitive strains. All the mutations, except one, are in the C-terminal half of the 659-amino-acid sequence containing the penicillin-binding modules. DNA fragments containing either full-length or a C-terminal half of pbp1 could transform HPK5 to have resistance, indicating that changes in the penicillin-binding core of PBP1 are involved in the amoxicillin resistance of H. pylori isolated in Korea.