Evaluation of therapeutic properties of fermented vegetables extract (OM-X®) in the model of colitis induced by Citrobacter rodentium in mice

AbstractInfection of mice with Citrobacter rodentium serves as a model to study human intestinal infections. C. rodentium infection leads to increased production of inflammatory cytokines, immune cell infiltration and damage to the gut barrier. We used this model of colitis to evaluate the therapeutic properties of OM-X®, an extract prepared by fermentation of vegetables, seaweeds, fruits and mushrooms. Administration of OM-X® to C. rodentium-infected mice reduced damage to the intestinal epithelium, lowered inflammation scores, increased IL-10 expression and maintained FoxP3 gene expression. OM-X® also partially prevented bacterial translocation, increased expression of tight junction genes and increased proliferation of epithelial cells. PCR analysis of stool samples showed that OM-X® significantly reduced the populations of bacteria harboring buk gene (mostly Clostridium species). It is suggested that alterations of microbiota composition, following OM-X® consumption, contribute to protection against infection and epithelial damage, and lead to an increased expression of anti-inflammatory cytokines

Intestinal antiinflammatory effect of 5-aminosalicylic acid is dependent on peroxisome proliferator–activated receptor-γ

5-aminosalicylic acid (5-ASA) is an antiinflammatory drug widely used in the treatment of inflammatory bowel diseases. It is known to inhibit the production of cytokines and inflammatory mediators, but the mechanism underlying the intestinal effects of 5-ASA remains unknown. Based on the common activities of peroxisome proliferator–activated receptor-γ (PPAR-γ) ligands and 5-ASA, we hypothesized that this nuclear receptor mediates 5-ASA therapeutic action. To test this possibility, colitis was induced in heterozygous PPAR-γ+/− mice and their wild-type littermates, which were then treated with 5-ASA. 5-ASA treatment had a beneficial effect on colitis only in wild-type and not in heterozygous mice. In epithelial cells, 5-ASA increased PPAR-γ expression, promoted its translocation from the cytoplasm to the nucleus, and induced a modification of its conformation permitting the recruitment of coactivators and the activation of a peroxisome-proliferator response element–driven gene. Validation of these results was obtained with organ cultures of human colonic biopsies. These data identify PPAR-γ as a target of 5-ASA underlying antiinflammatory effects in the colon

Le récepteur gamma activé par les proliférateurs de péroxysomes et les Maladies Inflammatoires Chroniques de l'Intestin (MICI et PPAR

PPAR$\gamma$ vient d'être récemment décrit comme étant un gène de susceptibilité pour les Maladies Inflammatoires Chroniques de l'Intestin (MICl), tout comme le gène NOD2/CARDl5. Les MICI sont des pathologies dues à une réponse immunitaire anormale, génétiquement déterminée, contre les bactéries de la flore intestinale. PPARã, connu pour son rôle important dans l'adipogenèse, est fortement exprimé au niveau de la muqueuse colique par les cellules épithéliales. PPAR$\gamma$ est impliqué dans la régulation de l'inflammation. En effet, les agonistes de ce récepteur nucléaire diminuent fortement l'inflammation au cours de colite expérimentale induite par des agents chimiques. Un déficit de l'expression de PPARγ a été mis en évidence chez les patients atteints de rectocolite hémorragique, ce qui pourrait en partie expliquer l'inflammation aiguë. D'autre part, les bactéries, y compris celles de la flore commensale, sont capables de réguler PPARã. Le récepteur Toll Like Receptor-4 (TLR-4), responsable de la reconnaissance de motifs bactériens comme le lipopolysaccharide (LPS), intervient en effet dans la régulation de PPARã et de ses propriétés anti-inflammnatoires. Tous ces arguments font de PPAR$\gamma$ une cible thérapeutique très intéressante pour le traitement des MICI

Helicobacter pylori module l'expression des gènes impliqués dans la biogenèse des mucines (études in vitro)

Helicobacter pylori est l'agent étiologique responsable des gastrites chroniques, des ulcères et est aussi impliqué dans le cancer gastrique. Cette bactérie vit dans le mucus qui recouvre la muqueuse gastrique. Le mucus est constitué essentiellement de mucines, glycoprotéines de haut poids moléculaire dont l'expression varie selon les tissus et les cellules. Des modifications de l'expression des gènes de mucines, ainsi que de leur profil de glycosylation ont été rapportées dans la gastrite chronique et le cancer gastrique. On ignore si ces modifications sont des conditions préexistantes favorisant la colonisation et la persistance de cette bactérie ou si elles sont dues à sa présence. Afin de déterminer le rôle de H. pylori et plus précisément celui de certains de ces facteurs de virulence sur la biogénèse des mucines, nous avons mis au point un modèle d'infection cellulaire. Il nous a permis de tester des mutants isogéniques déficients pour chacun des facteurs de virulence et de mesurer leurs effets sur l'expression et l'activité fonctionnelle des promoteurs des gènes de mucines et sur la sialylation. Nous avons montré qur H. pylori altère la transcription des gènes de mucines dont l'expression varie dans les pathologies associées à cette bactérie. [...] H. pylori perturbe donc la biogénèse des mucines. L'uréase joue un rôle prépondérant dans la modification de l'expression des gènes de mucines rencontrées dans la gastrite à H. pylori, alors que l'îlot de pathogénicité perturbe l'expression des gènes caractéristiques du stade précancéreux de métaplasie intestinale. La flagelline intervient également mais dans une moindre mesure.LILLE1-BU (590092102) / SudocSudocFranceF

Yersinia pseudotuberculosis Anti-Inflammatory Components Reduce Trinitrobenzene Sulfonic Acid-Induced Colitis in the Mouse

Rectal instillation of trinitrobenzene sulfonic acid (TNBS) induces acute colitis in the mouse. We tested the efficacy of Yersinia pseudotuberculosis anti-inflammatory components in preventing TNBS-triggered colitis. Animals were orally inoculated with virulence-attenuated Yersinia cells (a phoP mutant) prior to TNBS administration. Under these experimental conditions, colonic lesions and tumor necrosis factor alpha mRNA levels were significantly reduced

Helicobacter pylori urease and flagellin alter mucin gene expression in human gastric cancer cells

International audienceBackground Helicobacter pylori (Hp), which is one of the causative agents in human gastric adenocarcinoma, is known to interact with mucous gel and alter mucin gene expression. The aim of this work was to study, using an in vitro model of cell infection, the effects of urease, flagellin, and CagA vir-ulence factors on the regulation of the four 11p15 mucin genes (MUC2, MUC5AC, MUC5B, and MUC6). Methods KATO-III and AGS gastric cancer cells were infected for 1, 3 or 6 h with Hp wild-type strains (ATCC 43504, N6, and SS1) or corresponding isogenic mutants deficient for urease subunit B, flagellin subunit A, and CagA. mRNA levels of MUC2, MUC5B, MUC5AC and MUC6 were assessed by RT-PCR, and functional activity of their promoters was measured by transient transfection assays. Results Infection of KATO-III cells with Hp wild-type strains resulted in an early (at 1 h) transient expression of MUC2, MUC5AC, and MUC6 mRNA concomitant with those of interleukin (IL)-1b, IL-8, and TNF-a cytokines. In these cells, the UreB-isogenic mutant induced strong activation of MUC5AC expression, and UreB-responsive elements were located in the-486/-1 region of the promoter. FlaA-and CagA-mutants had no effect on mucin gene mRNA levels in KATO-III cells. In AGS cells, Hp-responsive elements were identified in all promoters, and overexpression of NF-jB induced upregulation of MUC5AC promoter activity when infected with the UreB-isogenic mutant. Conclusion These results indicate that Hp infection of gastric cancer cells alters 11p15 mucin gene transcription and that MUC5AC downregulation is mediated by urease virulence factor

Chitin-glucan improves important pathophysiological features of irritable bowel syndrome.

International audienceIrritable bowel syndrome (IBS) is one of the most frequent and debilitating conditions leading to gastroenterological referrals. However, recommended treatments remain limited, yielding only limited therapeutic gains. Chitin-glucan (CG) is a novel dietary prebiotic classically used in humans at a dosage of 1.5-3.0 g/d and is considered a safe food ingredient by the European Food Safety Authority. To provide an alternative approach to managing patients with IBS, we performed preclinical molecular, cellular, and animal studies to evaluate the role of chitin-glucan in the main pathophysiological mechanisms involved in IBS.AIMTo evaluate the roles of CG in visceral analgesia, intestinal inflammation, barrier function, and to develop computational molecular models.METHODSVisceral pain was recorded through colorectal distension (CRD) in a model of long-lasting colon hypersensitivity induced by an intra-rectal administration of TNBS [15 milligrams (mg)/kilogram (kg)] in 33 Sprague-Dawley rats. Intracolonic pressure was regularly assessed during the 9 wk-experiment (weeks 0, 3, 5, and 7) in animals receiving CG (n = 14) at a human equivalent dose (HED) of 1.5 g/d or 3.0 g/d and compared to negative control (tap water, n = 11) and positive control (phloroglucinol at 1.5 g/d HED, n = 8) groups. The anti-inflammatory effect of CG was evaluated using clinical and histological scores in 30 C57bl6 male mice with colitis induced by dextran sodium sulfate (DSS) administered in their drinking water during 14 d. HT-29 cells under basal conditions and after stimulation with lipopolysaccharide (LPS) were treated with CG to evaluate changes in pathways related to analgesia (µ-opioid receptor (MOR), cannabinoid receptor 2 (CB2), peroxisome proliferator-activated receptor alpha, inflammation [interleukin (IL)-10, IL-1b, and IL-8] and barrier function [mucin 2-5AC, claudin-2, zonula occludens (ZO)-1, ZO-2] using the real-time PCR method. Molecular modelling of CG, LPS, lipoteichoic acid (LTA), and phospholipomannan (PLM) was developed, and the ability of CG to chelate microbial pathogenic lipids was evaluated by docking and molecular dynamics simulations. Data were expressed as the mean ± SEM.RESULTSDaily CG orally-administered to rats or mice was well tolerated without including diarrhea, visceral hypersensitivity, or inflammation, as evaluated at histological and molecular levels. In a model of CRD, CG at a dosage of 3 g/d HED significantly decreased visceral pain perception by 14% after 2 wk of administration (P < 0.01) and reduced inflammation intensity by 50%, resulting in complete regeneration of the colonic mucosa in mice with DSS-induced colitis. To better reproduce the characteristics of visceral pain in patients with IBS, we then measured the therapeutic impact of CG in rats with TNBS-induced inflammation to long-lasting visceral hypersensitivity. CG at a dosage of 1.5 g/d HED decreased visceral pain perception by 20% five weeks after colitis induction (P < 0.01). When the CG dosage was increased to 3.0 g/d HED, this analgesic effect surpassed that of the spasmolytic agent phloroglucinol, manifesting more rapidly within 3 wk and leading to a 50% inhibition of pain perception (P < 0.0001). The underlying molecular mechanisms contributing to these analgesic and anti-inflammatory effects of CG involved, at least in part, a significant induction of MOR, CB2 receptor, and IL-10, as well as a significant decrease in pro-inflammatory cytokines IL-1b and IL-8. CG also significantly upregulated barrier-related genes including muc5AC, claudin-2, and ZO-2. Molecular modelling of CG revealed a new property of the molecule as a chelator of microbial pathogenic lipids, sequestering gram-negative LPS and gram-positive LTA bacterial toxins, as well as PLM in fungi at the lowesr energy conformations.CONCLUSIONCG decreased visceral perception and intestinal inflammation through master gene regulation and direct binding of microbial products, suggesting that CG may constitute a new therapeutic strategy for patients with IBS or IBS-like symptoms