Antiadhesive properties of Abelmoschus esculentus (Okra) immature fruit extract against Helicobacter pylori adhesion.

BACKGROUND: Traditional Asian and African medicine use immature okra fruits (Abelmoschus esculentus) as mucilaginous food to combat gastritis. Its effectiveness is due to polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach tissue. The present study investigates the antiadhesive effect in mechanistic detail. METHODOLOGY: A standardized aqueous fresh extract (Okra FE) from immature okra fruits was used for a quantitative in vitro adhesion assay with FITC-labled H. pylori J99, 2 clinical isolates, AGS cells, and fluorescence-activated cell sorting. Bacterial adhesins affected by FE were pinpointed using a dot-blot overlay assay with immobilized Lewis(b), sialyl-Lewis(a), H-1, laminin, and fibronectin. (125)I-radiolabeled Okra FE polymer served for binding studies to different H. pylori strains and interaction experiments with BabA and SabA. Iron nanoparticles with different coatings were used to investigate the influence of the charge-dependence of an interaction on the H. pylori surface. PRINCIPAL FINDINGS: Okra FE dose-dependently (0.2 to 2 mg/mL) inhibited H. pylori binding to AGS cells. FE inhibited the adhesive binding of membrane proteins BabA, SabA, and HpA to its specific ligands. Radiolabeled compounds from FE bound non-specifically to different strains of H. pylori, as well as to BabA/SabA deficient mutants, indicating an interaction with a still-unknown membrane structure in the vicinity of the adhesins. The binding depended on the charge of the inhibitors. Okra FE did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors. CONCLUSION: Non-specific interactions between high molecular compounds from okra fruits and the H. pylori surface lead to strong antiadhesive effects

Effects of polysaccharide isolated from Streptococcus thermophilus CRL1190 on human gastric epithelial cells

EPS1190 was isolated from skim milk fermented with Stretococcus thermophilus CRL1190. The polysaccha-ride consisted of 33% glucose and 66% galactose with 1,4- and 1,4,6-galactose residues as main buildingblocks beside a high amount of 1,4-linked glucose. The polymer was characterized additionally con-cerning viscosity and zeta potential. EPS1190 stimulated cellular vitality and proliferation of humanstomach AGS cells and human buccal KB cells significantly. EPS1190 stimulated phagocytosis rate ofmurine macrophages RAW264.7 significantly. NO-release or anti-inflammatory effects by inhibition ofLPS-induced NO release were not observed. Confocal laser scanning microscopy revealed that EPS1190 ispartially internalized into AGS cells via endosomes. The bioadhesive absorption of FITC-labeled EPS1190into the mucus layer on the apical side of the epithelium using histological tissue sections from humanstomach was observed. Specific interaction of EPS1190 with mucin can be excluded as shown by micro-viscosimetry studies. EPS1190 increased the adhesion of H. pylori to AGS cells, which resulted in increasedsecretion of proinflammatory cytokines TNFa, IL-6 and IL-8. Summarizing, EPS1190 seems to stimulateepithelial cell regeneration and immunological innate defense mechanisms, which again can rationalizedthe use of this polysaccharide as cytoprotective compound in probiotioc preparations.Fil: Marcial, Guillermo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Centro de Referencia Para Lactobacilos (i); Argentina; University of Münster. Institute for Pharmaceutical Biology and Phytochemistry; Alemania;Fil: Messing, Jutta. University of Münster. Institute for Pharmaceutical Biology and Phytochemistry; Alemania;Fil: Menchicchi, Bianca. University of Münster. Institute of Plant Biology and Biotechnology; Alemania;Fil: Goycoolea, Francisco. University of Münster. Institute of Plant Biology and Biotechnology; Alemania;Fil: Faller, Gerhard. St. Vincentius Hospital. Institute for Pathology; Alemania;Fil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Centro de Referencia Para Lactobacilos (i); Argentina; Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; Argentina;Fil: Hensel, Andreas. University of Münster. Institute for Pharmaceutical Biology and Phytochemistry; Alemania

Antiadhesive Properties of Arabinogalactan Protein from Ribes nigrum Seeds against Bacterial Adhesion of Helicobacter pylori

Fruit extracts from black currants (Ribes nigrum L.) are traditionally used for treatment of gastritis based on seed polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach cells. For detailed investigations an arabinogalactan protein (F2) was isolated from seeds and characterized concerning molecular weight, carbohydrate, amino acid composition, linkage, configuration and reaction with beta-glucosyl Yariv. Functional testing of F2 was performed by semiquantitative in situ adhesion assay on sections of human gastric mucosa and by quantitative in vitro adhesion assay with FITC-labled H. pylori strain J99 and human stomach AGS cells. Bacterial adhesins affected were identified by overlay assay with immobilized ligands. I-125-radiolabeled F2 served for binding studies to H. pylori and interaction experiments with BabA and SabA. F2 had no cytotoxic effects against H. pylori and AGS cells; but inhibited bacterial binding to human gastric cells. F2 inhibited the binding of BabA and fibronectin-binding adhesin to its specific ligands. Radiolabeled F2 bound non-specifically to different strains of H. pylori; and to BabA deficient mutant. F2 did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors. From these data the non-specific interactions between F2 and the H. pylori lead to moderate antiadhesive effects

Adhesion assay with MNPs.

<p>Amount of bacteria in the untreated control was calculated as 100% and is indicated as broken line. Results of the samples incubated with MNPs are related to the values of the untreated control. Samples are named according to the type of MNPs added. Results are mean values with ± SD from six independent experiments with *: <i>p</i><0.05 and **: <i>p</i><0.01. Significance values refer to the comparison with the fluidMAG-DX® values, as indicated by the brackets.</p

Influence of Okra FE on <i>H. pylori</i> strain 17875/Le^b binding to Le^b-HSA.

<p>Data are related to the Le^b-HSA binding of the control (only 17875/Le^b together with Le^b,  = 100% Le^b binding).</p

Differential gene expression of <i>H. pylori</i> pretreated with Okra FE.

<p>Endogenous control: 23S rRNA. Data are related to untreated control (UC) <i>H. pylori</i> in liquid growth medium (RQ = 1), with n = 2 replicates from three independent experiments (mean ± SD). * <i>p</i>≤0.05</p

Binding of radiolabeled fractions Okra FE subfractions FE3, 4 and 5 to different <i>H. pylori</i> bacterial strains and <i>E. coli</i> reference strain.

<p>Binding of radiolabeled fractions Okra FE subfractions FE3, 4 and 5 to different <i>H. pylori</i> bacterial strains and <i>E. coli</i> reference strain.</p

Influence of Okra FE on <i>H. pylori</i> strain 17875<i>babA1A2</i> binding to sialyl-Le^x-HSA.

<p>Data are related to the control (only 17875<i>babA1A2</i> with sLe^x-HAS  =  100%).</p