The Gram negative bacterium Helicobacter pylori is a human pathogen which infects the gastric mucosa and causes an inflammatory process leading to gastritis, ulceration and cancer. A systematic, proteome based approach was chosen to detect candidate antigens of H. pylori for diagnosis, therapy and vaccine development and to investigate potential associations between specific immune responses and manifestations of disease. Sera from patients with active H. pylori infection (n = 24), a control group with unrelated gastric disorders (n = 12) and from patients with gastric cancer (n = 6) were collected and analyzed for the reactivity against proteins of the strain HP 26695 separated by two-dimensional electrophoresis. Overall, 310 antigenic protein species were recognized by H. pylori positive sera representing about 17% of all spots separated. Out of the 32 antigens most frequently recognized by H. pylori positive sera, nine were newly identified and 23 were confirmed from other studies. Three newly identified antigens which belong to the 150 most abundant protein species of H. pylori, were specifically recognized by H. pylori positive sera: the predicted coding region HP0231, serine protease HtrA (HP1019) and Cag3 (HP0522). Other antigens were recognized differently by sera from gastritis and ulcer patients, which may identify them as candidate indicators for clinical manifestations. The data from these immunoproteomic analyses are added to our public database (http://www.mpiib-berlin.mpg.de/2D-PAGE). This platform enables one to compile many protein profiles and to integrate data from other studies, an approach which will greatly assist the search for more immunogenic proteins for diagnostic assays and vaccine design.

Helicobacter pylori is the causative agent of a variety of gastric diseases, but the clinical relevance of bacterial virulence factors is still controversial. Virulent strains carrying the cag pathogenicity island (cagPAI) are thought to be key players in disease development. Here, we have compared cagPAI-dependent in vitro responses in H. pylori isolates obtained from 75 patients with gastritis, peptic ulcer, and gastric cancer (n ‫؍‬ 25 in each group). AGS gastric epithelial cells were infected with each strain and assayed for (i) CagA expression, (ii) translocation and tyrosine phosphorylation of CagA, (iii) c-Src inactivation, (iv) cortactin dephosphorylation, (v) induction of actin cytoskeletal rearrangements associated with cell elongation, (vi) induction of cellular motility, and (vii) secretion of interleukin-8. Interestingly, we found high but similar prevalences of all of these cagPAI-dependent host cell responses (ranging from 56 to 80%) among the various groups of patients. This study revealed CagA proteins with unique features, CagA subspecies of various sizes, and new functional properties for the phenotypic outcomes. We further showed that induction of AGS cell motility and elongation are two independent processes. Our data corroborate epidemiological studies, which indicate a significant association of cagPAI presence and functionality with histopathological findings in gastritis, peptic ulcer, and gastric cancer patients, thus emphasizing the importance of the cagPAI for the pathogenicity of H. pylori. Nevertheless, we found no significant association of the specific H. pylori-induced responses with any particular patient group. This may indicate that the determination of disease development is highly complex and involves multiple bacterial and/or host factors.

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A large membrane proteinase 3 (mPR3)-positive neutrophil subset (mPR3 high ) is a risk for Wegener's granulomatosis (WG).The relationship between mPR3 expression and clinical manifestations was investigated in 81 WG patients and mPR3 expression was studied in CD34 ؉ stem cell-derived human neutrophils. The mPR3 high neutrophil percentage correlated with renal function, anemia, and albumin at the time of presentation. The mPR3 high neutrophil percentage and renal failure severity correlated directly after 5 yr. For elucidating mechanisms that govern mPR3 expression, studies were conducted to determine whether the genetic information that governs mPR3 expression resides within the neutrophils, even without stimuli possibly related to disease. CD34 ؉ hematopoietic stem cells were differentiated to neutrophils, and their mPR3 expression was determined. A two-step amplification/differentiation protocol was used to differentiate human CD34 ؉ hematopoietic stem cells into neutrophils with G-CSF. The cells progressively expressed the neutrophil surface markers CD66b, CD35, and CD11b. The ferricytochrome C assay demonstrated a strong respiratory burst at day 14 in response to PMA but none at day 0. Intracellular PR3 was detectable from day 4 by Western blotting. An increasing percentage of a mPR3-positive neutrophil subset became detectable by flow cytometry, whereas a second subset remained negative, consistent with a bimodal expression. Finally, human PR3-anti-neutrophil cytoplasmic autoantibodies induced a stronger respiratory burst, compared with human control IgG in stem cell-derived neutrophils. Taken together, these studies underscore the clinical importance of the WG mPR3 phenotype. The surface mPR3 on resting cells is probably genetically determined rather than being dictated by external factors.