concanavalin-a and Helicobacter-Infections

Using second generation mucoadhesives may enhance targeting antibiotics for eradication of Helicobacter pylori from the stomach for the treatment of peptic ulcer. The aim of this research was to prepare and characterise ethylcellulose/chitosan microspheres containing clarithromycin with their surfaces functionalised with concanavalin A to produce a floating-mucoadhesive formulation. The microspheres were prepared using an emulsification-solvent evaporation method. Particle size, surface morphology, in vitro buoyancy profile, zeta potential, drug entrapment efficiency, in vitro drug release and release kinetics of the particles were determined. Lectin was conjugated to the microsphere surface using two-stage carbodiimide activation and confirmed using FTIR, fluorescence studies and zeta potential measurements. Conjugation ranged from 11 to 15 μg Con A/mg microspheres which represents over 56% efficiency although there was some drug loss during the conjugation process. Conjugation did not have a significant effect on the buoyancy and release of drug from the microspheres using a mucus diffusion model with 53% and 40% of drug released from unconjugated and conjugated microspheres within 12h. Conjugation improved mucoadhesion and interaction with porcine gastric mucin compared to unconjugated microspheres. The buoyancy and improved mucoadhesion of the microspheres provides potential for delivery of clarithromycin and other drugs to the stomach.

Topics: Adhesiveness; Animals; Anti-Bacterial Agents; Cellulose; Chitosan; Clarithromycin; Concanavalin A; Diffusion; Drug Stability; Gastric Juice; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Membranes, Artificial; Microspheres; Mucins; Mucus; Powder Diffraction; Spectroscopy, Fourier Transform Infrared; Swine; X-Ray Diffraction

In recent studies, the involvement of mast cells in the pathogenesis of Helicobacter pylori infection was suggested. In the present study, using isolated canine gastric mucosal mast cells, we undertook to elucidate the effects of interleukin-8 (IL-8) and H. pylori on histamine release from these cells.. Enriched canine gastric mucosal mast cells (50% target cells) were incubated in Hanks medium with IL-8, or water extract or sonicate of H. pylori for 15 min at 37 degrees C. The content of histamine in the supernatants and the cell pellets after centrifugation was assayed with a histamine radioimmunoassay (RIA) kit.. IL-8 (50 ng/ml) and concanavalin A (20 microg/ml) significantly increased histamine release from enriched gastric mucosal mast cells. Dose-dependent stimulation of histamine release by IL-8 (5-50 ng/ml) was also seen. Water extract and sonicate of H. pylori (10(8) bacteria) increased histamine release from mast cells. A concentration-dependent stimulation of histamine release by water extract or sonicate was also seen. The maximal response of histamine release was seen at the highest concentration of the water extract or sonicate.. The results indicated that IL-8 and H. pylori had stimulatory effects on histamine release from canine gastric mucosal mast cells. The results imply that IL-8 and soluble factors of H. pylori may accelerate inflammation of the gastric mucosa via histamine release from mast cells.

Topics: Animals; Bacterial Proteins; Cells, Cultured; Concanavalin A; Dogs; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Histamine Release; In Vitro Techniques; Interleukin-8; Mast Cells; Stomach Diseases

A plasma cell tumor of the stomach with unusual histology is reported. Macroscopically, the tumor formed two ulcers in the gastric body, and microscopic examination revealed proliferation of plasma cells producing immunoglobulin G kappa monotypic immunoglobulin, with metastatic infiltration in some perigastric lymph nodes. Most of these plasma cells had various-sized Russell bodies in the cytoplasm; hence the tumor may be called Mott cell tumor. The Russell bodies showed a strong affinity to concanavalin A by lectin immunohistochemistry, compared with those in reactive Mott cells. In addition, Helicobacter pylori (H. pylori) infection was proved by Gimenez stain and immunohistochemistry. The mixture of some centrocyte-like cells and presence of reactive lymph follicles with follicular colonization by tumor cells suggest that this lesion may be a variant of mucosa-associated lymphoid tissue lymphoma in association with H. pylori infection. The patient has shown no evidence of recurrence of the tumor after 11 years of follow up.

Topics: Antigens, Bacterial; Concanavalin A; Female; Gastrectomy; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Humans; Immunoglobulin kappa-Chains; Middle Aged; Plasmacytoma; Stomach Neoplasms; Stomach Ulcer

Helicobacter pylori is found within the gastric mucous gel layer and in association with the epithelial surface. The aim of this study was to determine the effect of H. pylori infection on mucin gene expression (MUC6, MUC5, and MUC1) in the gastric epithelium.. Gastric biopsy specimens were examined by immunohistochemistry and in situ hybridization for mucin gene expression.. MUC6 was limited to mucous glands of H. pylori-negative patients, but 72% of H. pylori-positive patients also expressed MUC6 in surface mucous cells. In contrast, MUC5 mucin was found in significantly fewer surface mucous cells of H. pylori-positive specimens. Carbohydrates recognized by Lewis (Le) X and paradoxical concanavalin A (con A) staining were aberrantly expressed in the surface mucous cells of 16 of 27 and 17 of 23 H. pylori-positive tissues, respectively. Surface Le(b) was present in 26 of 27 H. pylori-positive and 19 of 30 H. pylori-negative tissues. Eradication of H. pylori resulted in reversal of surface MUC5 and MUC6 expression toward normal patterns. Purified gastric mucins of H. pylori-positive patients bound more anti-MUC6 and anti-Le(b) than mucins from H. pylori-negative patients.. The type of mucin that is normally limited to mucous glands is aberrantly expressed in surface mucous cells of H. pylori-positive patients, whereas less of the surface epithelium expresses normal surface-type gastric mucin.

Topics: Adult; Aged; Aged, 80 and over; Amino Acid Sequence; Base Sequence; Biopsy; Concanavalin A; DNA; Enzyme-Linked Immunosorbent Assay; Epithelium; Female; Gastric Mucins; Gastric Mucosa; Gene Expression Regulation; Helicobacter Infections; Helicobacter pylori; Humans; Immunohistochemistry; In Situ Hybridization; Lewis X Antigen; Male; Middle Aged; Molecular Sequence Data

Helicobacter pylori, the causative agent of type-B gastritis and duodenal ulcer in man is described as a bacterium able to stimulate the human immune system. This study demonstrates that H. pylori besides this property possesses an immune suppressive activity. The in vitro proliferation of human peripheral blood mononuclear cells to purified protein derivative of tuberculin (PPD), phytohemagglutinin, and concanavalin A was reduced in a dose-dependent manner by bacteria which had been inactivated by incubation at 56 degrees C as well as by a soluble cytoplasmic fraction of H. pylori. The immune suppressive effect on the mitogen-induced proliferation could be increased by preincubation of the mononuclear cells with H. pylori. The observed effect does not seem to be a specific phenomenon depending on prior exposure of the blood donors to H. pylori, since suppression occurred with mononuclear cells of H. pylori-infected patients as well as of antibody-negative healthy control individuals. The suppressive activity was non-dialyzable, heat-labile (100 degrees C, 30 min) and sensitive to trypsin. Furthermore, the treatment at 100 degrees C caused an increase in the capability of H. pylori to induce lymphoproliferation. This fact indicates that the suppressive factor is also effective on H. pylori antigens. While exogenous interleukin-2, could to a certain extent, restore the responsiveness of the lymphocytes after PPD-stimulation in the presence of H. pylori, the addition of interleukin-1 had no effect on the suppressed lymphoproliferation. Cell-separation and cell-mixing experiments indicated that an influence on monocytes rather than on T cells is the major cause of the observed suppressive effect. Although the immunological mechanisms involved in H. pylori-associated gastritis are not clearly defined, it is reasonable to presume that suppression of host defense mechanisms may contribute to the pathogenesis of this disease.

Topics: Cell Separation; Cells, Cultured; Concanavalin A; Helicobacter Infections; Helicobacter pylori; Humans; Immunity, Cellular; Interleukin-6; Lymphocyte Activation; Monocytes; Phytohemagglutinins; T-Lymphocytes; Tuberculin; Tumor Necrosis Factor-alpha