Interaction of Helicobacter pylori with C-Type Lectin Dendritic Cell-Specific ICAM Grabbing Nonintegrin

In this study we asked whether Helicobacter pylori whole cells and lipopolysaccharide (LPS) utilize sugar moieties of Lewis (Le) antigenic determinants to interact with DC-SIGN (dendritic cell specific ICAM grabbing nonintegrin) receptor on dendritic cells (DCs). For this purpose the soluble DC-SIGN/Fc adhesion assay and the THP-1 leukemia cells with induced expression of DC-SIGN were used. We showed that the binding specificity of DC-SIGN with H. pylori LeX/Y positive whole cells and H. pylori LPS of LeX/Y type was fucose dependent, whereas in LeXY negative H. pylori strains and LPS preparations without Lewis determinants, this binding was galactose dependent. The binding of soluble synthetic LeX and LeY to the DC-SIGN-like receptor on THP-1 cells was also observed. In conclusion, the LeXY dependent as well as independent binding of H. pylori whole cells and H. pylori LPS to DC-SIGN was described. Moreover, we demonstrated that THP-1 cells may serve as an in vitro model for the assessment of H. pylori-DC-SIGN interactions mediated by LeX and LeY determinants

Antigen-specific lymphocyte proliferation as a marker of immune response in guinea pigs with sustained Helicobacter pylori infection

Helicobacter pylori (H. pylori) bacteria are human pathogens causing symptomatic gastritis, peptic ulcer or gastric cancer. Little is known about the kinetics of immune responses in H. pylori infected patients because the initial moment of infection has not been identified. Various animal models are used to investigate the immune processes related to H. pylori infection. In this study we checked whether H. pylori infection in guinea pigs, mimicking natural H. pylori infection in humans, resulted in the development of specific immune responses to H. pylori antigens by measuring the proliferation of lymphocytes localized in mesenteric lymph nodes, spleen and peripheral blood. The maturity of macrophages and cytokines, delivered by monocyte-macrophage lineage or lymphocytes, were considered as mediators, which might influence the lymphocyte blastogenic response. The obtained results showed the activation of T cells localized in mesenteric lymph nodes by H. pylori antigens in H. pylori infected guinea pigs four weeks postinfection. The blastogenic activity of lymphocytes was shaped by their interaction with antigen presenting cells, which were present in the cell cultures during the whole culture period. Moreover, the balance between cytokines derived from adherent leukocytes including interleukin 8 - IL-8 as well as interferon gamma - IFN-γ, and transforming growth factor beta - TGF-β delivered by lymphocytes, was probably important for the successful proliferation of lymphocytes. The H. pylori specific lymphocytes were not propagated in peripheral blood and spleen of H. pylori infected animals. The modulation of immunocompetent cells by H. pylori antigens or their different distribution cannot be excluded

The microbiological, histological, immunological and molecular determinants of Helicobacter pylori infection in guinea pigs as a convenient animal model to study pathogenicity of these bacteria and the infection dependent immune response of the host

Helicobacter pylori is an etiological agent of chronic gastritis, gastric and duodenal ulcers and gastric cancers. The use of an appropriate animal model for experimental studies on the pathogenesis of H. pylori infections is necessary due to the chronic character of such infections and difficulties in identifying their early stage in humans. The aim of this study was to develop a guinea pig model of H. pylori infection and identify its microbiological, histological, serological and molecular determinants. Guinea pigs were inoculated per os with H. pylori strains: CCUG 17874 or ATCC 700312, both producing vacuolating cytotoxin A (VacA) and cytotoxin associated gene A (CagA) protein, suspended in Brucella broth with fetal calf serum (FCS) and Skirrow supplement of antibiotics. To determine H. pylori colonization, 7 and 28 days after the challenge, a panel of diagnostic methods was used. It included culturing of microorganisms from the gastric tissue, histopathological analysis of gastric sections, stained by Mayer,s haematoxylin and eosin to assess inflammatory response, by Giemsa as well as Warthin-Starry silver staining to visualise Helicobacter-like organisms (HLO) and with anti-Ki-67 antigen to assess epithelial cell proliferation. H. pylori infection was also confirmed by polymerase chain reactions (PCR) for detection in gastric tissue of ureC and cagA genes and by serological assessment of H. pylori antigens in faeces. This study showed the usefulness of microbiological, histological, immunological and molecular methods for the detection of persistent H. pylori infections in guinea pigs, which could be an appropriate model for studying H. pylori pathogenesis and the related immune response against these microbes

Helicobacter pylori antigens as potential modulators of lymphocytes’ cytotoxic activity

Helicobacter pylori (H.p) colonizes human gastric mucosa and causes gastric and duodenal ulcer disease or gastric cancer. Various H.p compounds may modulate the host immune response in regards to tolerance of the infection or disease development. The aim of this study was to determine whether H.p lipopolysaccharide (LPS) and glycine acid extract antigens (GE) or E. coli LPS influence the cytotoxic activity of peripheral blood lymphocytes from H.p infected H.p (+) or uninfected H.p (-) individuals, in the presence or absence of exogenous interleukin (IL)12. Individual H.p status was defined by the urea breath test. Lymphocytes, stimulated or not with H.p, and control antigens, with or without IL-12, were used as effector cells and epithelial HeLa cells as targets. The cytotoxicity of lymphocytes was expressed as the percentage of dead target cells unable to reduce tetrazolium salt. The supernatants from HeLa/lymphocyte cultures were used for detection of the cellular cytotoxicity markers granzyme B and caspase 8. The natural cytotoxic activity of lymphocytes from H.p (+) was less than that of H.p (-) donors. This may have been due to fewer natural killer cells of CD3-CD56+Nkp46+ phenotype in H.p (+) in comparison to H.p (-) subjects. H.p GE and standard E. coli LPS enhanced the cytotoxicity of lymphocytes towards target cells whereas H.p LPS downregulated this activity. The decrease in lymphocyte cytotoxicity in response to H.p LPS correlated with a lack of IL-2 and IL-12 production, inhibition of interferon-? production, and low IL-10 secretion by mononuclear leukocytes. IL-12 significantly enhanced the natural as well as H.p LPS and H.p GE driven cytotoxic capacity of lymphocytes. In conclusion, H.p LPS may negatively modulate natural cytotoxic activity and cytokine secretion by immunocompetent cells and thus be involved in the maintenance of infection and development of gastric pathologies

Anti-KC Autoantibody:KC Complexes Cause Severe Lung Inflammation in Mice via IgG Receptors

We have shown previously that high concentrations of IL-8 associated with anti-IL-8 autoantibodies (anti–IL-8:IL-8 complexes) are present in lung fluids from patients with the acute respiratory distress syndrome (ARDS), and correlate both with the development and outcome of ARDS. We also detected deposition of these complexes in lung tissues from patients with ARDS but not in control tissues. Moreover, we determined that IgG receptors (FcγRs) mediate activity of anti–IL-8:IL-8 complexes. In the current study, we generated anti-KC (KC = chemokine (CXC motif) ligand 1 (CXCL1)) autoantibody:KC immune complexes (KC–functional IL-8) in lungs of mice to develop a mouse model of autoimmune complex–induced lung inflammation. Both wild-type (WT) and γ-chain–deficient mice that lack receptors for immune complexes (FcγRs) were studied. First, the mice were immunized with KC to induce anti-KC autoantibodies. Then, KC was administered intratracheally to generate anti-KC:KC complexes in the lung. Presence of anti-KC:KC complexes was associated with development of severe pulmonary inflammation that was, however, dramatically suppressed in γ-chain–deficient mice. Second, because sepsis is considered the major risk factor for development of ARDS, we evaluated LPS-treated WT as well as γ-chain–deficient mice for the presence of anti-KC:KC complexes and pulmonary inflammatory responses. We detected complexes between anti-KC autoantibodies and KC in lung lavages and tissues of mice treated with LPS. Moreover, γ-chain–deficient mice that lack receptors for immune complexes were protected from LPS-induced pulmonary inflammation. Our results suggest that immune complexes containing autoantibodies contribute to development of lung inflammation in LPS-treated mice

Different effectiveness of helicobacter pylori lipopolysaccharides with or without lewisxy determinants in stimulating the secretion of proinflammatory cytokines il-8 and tnf-α by peripheral blood mononuclear leukocytes

Introduction: Helicobacter pylori is an aetiological agent of chronic gastritis, gastric and duodenal ulcers, and gastric cancers. It is suggested that H. pylori must have undergone evolutionary changes that enable the bacteria to overcome the host immune response. The molecular mimicry between Lewis (Le) determinants present in H. pylori lipopolysaccharide (LPS) and on the host cells may play a role in the outcome of H. pylori infections. Aim: In this study we investigated the production of inflammatory cytokines tumour necrosis factor alpha (TNF-alpha) and interleukin 8 (IL-8), by human peripheral blood mononuclear leukocytes (PBML) from H. pylori infected (11) and uninfected (10) subjects (21 women, aged 25-50 years), in response to H. pylori-LPS with LeXY(+) or without LeXY(-) determinants. Material and methods: Peripheral blood was collected using the Vacutainer heparin system and constituted a source of total or monocyte and lymphocyte enriched PBML fractions. Tumour necrosis factor alpha and IL-8 were assessed by immunosorbent assay (ELISA) in the supernatants from leukocyte cultures stimulated or not with H. pylon LPS or standard Escherichia coli LPS. Results: The results showed that adherent but not non-adherent PBML responded to H. pylori-LPS by TNF-alpha and IL-8 production. The H. pylori-LPS LeXY(+) was a stronger stimulus for macrophage-derived cytokines, as compared with H. pylori-LPS LeXY(-). Helicobacter pylori-LPS LeXY(+) driven production of TNF-alpha and IL-8 was significantly inhibited with antibodies to LPS-binding protein (LBP) and to CD14 proteins. Conclusions: It is possible that LeXY determinants of H. pylori-LPS could be involved in LPS signalling for inflammatory cytokines and thus regulate the outcome of H. pylon infections