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Martine Heyman

Publications and source records attributed to Martine Heyman.

At least 19 recordsLinked to original sources
PubMed2006

Effect of rebamipide on the colonic barrier in interleukin-10-deficient mice.

Our aim was to study the effect of a mucosal protective agent, rebamipide, on the colonic barrier and the immune response in colitis-prone interleukin-10-deficient (IL-10-/-) C57BL/6 mice infected with Helicobacter hepaticus. After sacrifice, in all mice, control, or previously infected with H. hepaticus, or previously infected and treated with rebamipide enema, a histological examination of colonic samples was performed, intestinal permeability was studied in Ussing chamber, and mesenteric lymph node proliferation and cytokine secretion were measured. Mice treated with rebamipide presented a reinforcement of the distal colonic epithelial barrier, an increase of mesenteric lymph node cells proliferation, and of IFNgamma and IL-12 secretion. These results indicate that in IL-10-/- mice with mild colitis, rectally administered rebamipide reinforces the distal colonic barrier and has a slight Th1 immuno-stimulatory effect on mesenteric lymph node cells. These properties could be helpful in the management of some inflammatory bowel diseases.

Alanine↗
PubMed2006

Oral proteases: a new approach to managing coeliac disease.

A life-long but constraining gluten-free diet is the only treatment currently available for coeliac disease. The human gastrointestinal tract does not possess the enzymatic equipment to efficiently cleave the gluten-derived proline-rich peptides driving the abnormal immune intestinal response in patients with coeliac disease. Oral therapy by exogenous prolylendopeptidases able to digest ingested gluten was therefore propounded as an alternative treatment to the diet. The feasibility of this approach is discussed by reviewing recent data on the intestinal transport of gliadin peptides, properties of available enzymes and preliminary clinical assays. Development of new enzymes or enzymatic cocktails offers potentially more potent therapeutic tools that, however, need meticulous evaluation based on clinical, biological and histological criteria.

Administration, Oral↗
PubMed2006

Stimulation of immunity without alteration of oral tolerance in mice fed with heat-treated fermented infant formula.

OBJECTIVES: Little information is available on the properties of fermented milk formula intended to healthy infants. This study analyzes the effect of long-term ingestion of a heat-treated, fermented milk formula on the development of oral tolerance or systemic immune response to soluble antigens in mice. MATERIALS AND METHODS: The C3H/HeN mice, fed with a heat-treated fermented (Bifidobacterium breve C50 and Streptococcus thermophilus 065) infant formula (htFF) or a matched control diet (control), were immunized with ovalbumin (OVA) with or without gavage of 20 mg OVA to induce tolerance or immunity, respectively. Systemic and local anti-OVA immune responses and intestinal barrier function were measured after 5 to 6 weeks. RESULTS: Oral tolerance to OVA developed similarly in htFF- and control-fed mice, attested to by the downregulation of OVA-specific immunoglobulin (Ig) G and IgE after oral OVA administration. In contrast, immunization with OVA led to significantly higher titers in htFF-fed mice than in control-fed mice (log2 IgG titers, 16.45 +/- 1.24 and 15.46 +/- 0.79, respectively; P = 0.012). Jejunal interferon gamma, interleukin 12p40 and interleukin 10 expressions were significantly higher in tolerized mice fed with htFF compared with those fed with the control diet. Mucosal to serosal intact horseradish peroxidase fluxes were lower in htFF-fed mice than in control-fed mice (39 +/- 8 and 118 +/- 38 ng/h x cm2, respectively; P < 0.0001), indicating that the htFF diet reinforces intestinal barrier capacity to macromolecules. CONCLUSIONS: In mice, htFF strengthens intestinal barrier and enhances systemic immune responses to antigens without interfering with the development of oral tolerance, suggesting a potential beneficial effect in host defence and vaccination.

Administration, Oral↗
PubMed2005

Limited efficiency of prolyl-endopeptidase in the detoxification of gliadin peptides in celiac disease.

BACKGROUND & AIMS: The resistance of prolamines to digestive enzymes is thought to be a key contributor to the pathogenesis of celiac disease by promoting the intestinal entrance of peptides able to trigger inflammation in at-risk individuals. Oral administration of a bacterial prolyl-endopeptidase (PEP) therefore was proposed as a treatment for celiac disease. To delineate the feasibility of this treatment, the effect of PEP on gliadin peptides was assessed in vitro, and ex vivo during their transport across intestinal biopsy specimens of active celiac disease patients. METHODS: In vitro degradation by PEP of 3H-labeled gliadin peptides 56-88 (33-mer) and 31-49, was analyzed by radio-reverse-phase high-performance liquid chromatography and mass spectrometry. For ex vivo studies, PEP and 3H-peptides were added together onto the mucosal side of duodenal biopsy specimens mounted in Ussing chambers, and peptide transport and digestion were assessed by radio-reverse-phase high-performance liquid chromatography. RESULTS: Gliadin peptides were degraded partly by 20 mU/mL PEP both in vitro and ex vivo. This concentration of PEP decreased the amount of intact peptides 31-49 and 56-88 crossing the intestinal biopsy specimens of celiac disease patients, but could not prevent the intestinal passage of toxic or immunostimulatory metabolites. PEP concentrations of at least 500 mU/mL for 3 hours were required to achieve full detoxification of peptides and to prevent intestinal transport of active fragments. CONCLUSIONS: After prolonged exposure to high concentrations of PEP, the amount of immunostimulatory gliadin peptides reaching the local immune system in celiac patients is decreased. These results provide a basis to establish whether such conditions are achievable in vivo.

Biopsy↗
PubMed2005

Gut barrier dysfunction in food allergy.

Intestinal permeability tests used in the diagnosis of allergic diseases in response to oral food challenge have led to the conclusion that constitutive defects of the intestinal barrier are not the primary cause of allergic diseases. However, perturbation of environmental factors (infection, stress), by increasing intestinal permeability and enhancing danger signals, may favour food allergy in susceptible individuals. The mechanisms of enhanced permeability to specific and bystander antigens have been delineated as well as the molecular events involved in the sequential phases of allergic reactions. Intestinal absorption of food antigens and immune responses are mutually dependent, and luminal (environmental) and serosal (intrinsic) factors synergize to maintain a self-perpetuating cycle in which antigens penetrate the mucosa and induce allergic inflammation.

Antigens↗
PubMed2005

Differential role for CD23 splice forms in apical to basolateral transcytosis of IgE/allergen complexes.

The low affinity receptor for IgE (CD23) was recently implicated in the trans-epithelial transport of IgE-allergen complexes from the luminal side of enterocytes in animal models for intestinal allergy. Here, the respective functions of CD23 splice forms, b and bDelta5, in this apical to basolateral transport event have been investigated. First, the new bDelta5 splice form was further characterized, providing evidence that it binds IgE with high affinity, that its expression is induced by sensitization, and that bDelta5, unlike the classical b, undergoes constitutive internalization through clathrin-coated pits. These results suggested that the two CD23 splice forms were likely involved in different transcytotic events. MDCK cell lines expressing either b or bDelta5 were generated to directly test this hypothesis. In both cell lines, CD23 splice forms were localized at the apical membrane as in enterocytes from sensitized mice. Using mouse monoclonal IgE, we obtained evidence showing that bDelta5 mediates the apical to basolateral transport of free IgE, whereas classical b is much more efficient in mediating the transcytosis of IgE/allergen complexes. The present results shed new light on the role of CD23 species in IgE/allergen transepithelial transport and provide a new powerful physiological tool to study apical to basolateral transcytosis, a process which remains poorly characterized.

Allergens↗
PubMed2005

Effects of specific lactic acid bacteria on the intestinal permeability to macromolecules and the inflammatory condition.

UNLABELLED: Non-live probiotic bacteria and their fermentation products can be used in milk-based formula intended for healthy infants. The effects of a milk formula fermented with Bifidobacterium breve and Streptococcus thermophilus and heated/dehydrated to inactivate the micro-organisms have been reported over the last few years to decrease the intestinal permeability to macromolecules in experimental animals in vivo and more recently to down-regulate inflammatory condition in vitro. Feeding guinea-pigs with such dehydrated fermented milk reinforced the intestinal barrier resistance to food proteins (HRP, beta-lactoglobulin). In addition, the products secreted by bacteria were capable of inhibiting the lipopolysaccharide (LPS)-induced TNF-alpha secretion by human peripheral mononuclear blood cells. The active secretion products were resistant to digestive enzymes and their anti-inflammatory properties were preserved after transepithelial transport across the filter-grown intestinal epithelial cell line, especially in inflammatory conditions. The binding of LPS to monocytes as well as NFkappaB nuclear translocation leading to pro-inflammatory cytokine transcription were inhibited by bacteria-culture supernatants. CONCLUSION: B. breve and S. thermophilus used as non-live micro-organisms in fermented infant formula seem to induce a reduction in macromolecular absorption and release metabolites exerting an anti-TNF-alpha effect, which persists after intestinal transport. Thus, specific lactic acid bacteria and their metabolites seem to affect positively the intestinal function.

Bifidobacterium↗
PubMed2005

Bifidobacterium breve and Streptococcus thermophilus secretion products enhance T helper 1 immune response and intestinal barrier in mice.

Lactic acid bacteria or their secretion products can modulate immune responses differently in normal and inflammatory conditions. This comparative study analyzes the effect of oral administration of living lactic acid bacteria, or their conditioned media, on the epithelial and immune functions of colitis-prone C57BL/6 IL-10-deficient mice. Mice were untreated (control) or infected with Helicobacter hepaticus with or without oral treatment with living bacteria, Bifidobacterium breve C50 and Streptococcus thermophilus 065 (LB), or their culture-conditioned media (CM). Histology, cytokine mRNA, electrical resistance, and barrier capacity of colonic samples as well as cytokine secretion by mesenteric lymph node (MLN) cells were studied. Helicobacter hepaticus mice developed only mild colitis, which was not modified in LB or CM groups. In the CM (but not the LB) group, the colonic barrier was reinforced as compared to the other groups, as evidenced by decreased horseradish peroxidase (HRP) transcytosis and mannitol fluxes and increased electrical resistance. In MLN, the percentage of CD4+ and CD8+ T cells secreting IFNgamma was significantly higher in CM (2.06% and 1.98%, respectively) mice than in H. hepaticus (1.1% and 0.47%, P < 0.05) or control mice. In addition, the nonspecific stimulation of IFNgamma, TNFalpha, and IL-12 secretion by MLN cells was significantly higher in the CM group as compared to the other groups. In the absence of severe colitis, Bifidobacterium breve C50- and Streptococcus thermophilus 065-conditioned media can reinforce intestinal barrier capacity and stimulate Th1 immune response, highlighting the involvement of lactic acid bacteria-derived components in host defense.

Animals↗
PubMed2004

Food allergens are protected from degradation during CD23-mediated transepithelial transport.

BACKGROUND: CD23 (FcepsilonRII) is expressed by intestinal epithelial cells (IEC) following allergic stimulation and increases the uptake of IgE/allergen complexes. The aim of this study was to further analyze the role of CD23 in the intraepithelial processing of food allergens during transepithelial transport. METHODS: Balb-C mice were sensitized intraperitoneally with horseradish peroxidase (HRP) or beta-lactoglobulin (beta-LG) in the presence of pertussis toxin. In control and sensitized mice, 3H-HRP, intact HRP, or 14C-beta-LG fluxes were measured across jejunal segments mounted in Ussing chambers, in the presence or absence of mucosal anti-CD23 antibodies. HPLC analysis of serosal buffer was performed to detect HRP- or beta-LG-derived radiolabelled metabolites generated during transepithelial transport. RESULTS: In HRP-sensitized mice, 3H-HRP fluxes and intact HRP fluxes (3,836 +/- 476 and 290 +/- 86 ng/h x cm2, respectively) were significantly increased compared to control mice (1,677 +/- 297 ng/h x cm2, p < 0.01, and 106 +/- 23 ng/h x cm2, p < 0.02, respectively). HPLC analysis indicated the presence of intact HRP in the serosal compartment already 10 min after addition of HRP to the mucosal compartment, a result not observed in the control mice. In the presence of anti-CD23 antibodies, intact HRP fluxes were significantly decreased (131 +/- 27 ng/h x cm2) compared to control values in sensitized mice (290 +/- 86 ng/h x cm2, p < 0.02), suggesting that CD23 is involved is this 'protected' transport pathway. A similar protection during intestinal transport was observed for beta-LG in beta-LG sensitized mice. CONCLUSIONS: These results confirm that CD23 is involved in the rapid transepithelial transport of intact allergens in sensitized animals, and indicate that CD23 opens a 'protected' transport pathway in IECs.

Allergens↗
PubMed2004

In vitro and ex vivo activation of the TLR5 signaling pathway in intestinal epithelial cells by a commensal Escherichia coli strain.

The capacity of non-pathogenic enteric bacteria to induce a pro-inflammatory response is under debate in terms of its effect on the symbiosis between the mammalian host and its commensal gut microflora. Activation of NF-kappaB and induction of interleukin-8 (IL-8) and CCL-20 by the commensal Escherichia coli strain MG1655 were first studied in vitro in the human intestinal epithelial cell (IECs) lines HT29-19A and Caco-2, transfected or not with plasmids encoding dominant negative Toll-like receptor (TLR) 5 and myeloid differentiation factor-88 (MyD88) adaptor protein. The response of enterocytes in situ was then assessed using murine ileal biopsies mounted in Ussing chambers. Commensal E. coli induced NF-kappaB DNA binding, NF-kappaB transcriptional activity, CCL-20 expression, and IL-8 secretion in the human IEC lines. E. coli MG1655 flagellin was necessary and sufficient to trigger this pro-inflammatory pathway via its interaction with TLR5 and the subsequent recruitment of the adaptor protein MyD88. Following epithelial cell polarization, signaling could be induced by live E. coli and flagellin on the apical side of HT29-19A. The in vivo relevance of our findings was confirmed, because immunohistochemical staining of murine ileum demonstrated expression of TLR5 in the apical part of enterocytes in situ. Furthermore, flagellin added on the mucosal side of murine ileal biopsies mounted in Ussing chambers induced a basolateral production of KC, a functional murine homolog of human IL-8. These findings provide strong evidence that flagellin released by flagellated commensal bacteria in the intestinal lumen can induce a pro-inflammatory response in enterocytes in vivo.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Helicobacter pylori increases the epithelial permeability to a food antigen in human gastric biopsies.

AIMS: We have previously shown that H. pylori increases the passage of intact protein across the digestive epithelium, in vitro and in vivo in mice. The aim of this study was to test whether H. pylori can alter gastric permeability to a food-type antigen in humans. METHODS: Antral and corpus gastric biopsies obtained from H. pylori-positive and H. pylori-negative patients suffering from nonulcer dyspepsia with normal esogastroduodenal endoscopy were mounted in adapted Ussing chambers to measure gastric permeability. Electrical resistance (R, an index of epithelial integrity) and fluxes of 14C-mannitol (JMan, a marker of paracellular permeability) and 3H-horseradish peroxidase (HRP, a test protein of antigen transport and processing) under intact (JHRPi) and degraded (JD) form, across the biopsies, were measured. RESULTS: At the corpus level, biopsies obtained from H. pylori-positive patients, as compared to H. pylori-negative patients, presented significantly higher intact--but not degraded--HRP fluxes (JHRPi = 446 +/- 297 and 219 +/- 265 ng/h cm2, p < 0.05; JD = 4,247 +/- 3,884 and 3,575 +/- 2,594 ng/h x cm2, respectively), and an increase in paracellular permeability (Jman = 0.35 +/- 0.1 vs 0.24 +/- 0.08 micromol/h x cm2, p < 0.02, respectively). At the antrum level, a tendency to increased intact HRP fluxes in H. pylori-positive patients, as compared to H. pylori-negative patients, was observed (JHRPi = 284 +/- 250 vs 207 +/- 203 ng/h x cm2, p < 0.09), without modifications of paracellular permeability. CONCLUSIONS: H. pylori infection increases absorption of an intact food antigen across the corpus gastric mucosa. This phenomenon may contribute to the maintenance of gastric inflammation and could play a role in the development of allergic sensitization to dietary antigens in susceptible individuals.

Adult↗
PubMed2003

Alterations of the intestinal transport and processing of gliadin peptides in celiac disease.

BACKGROUND & AIMS: The hypothesis of a defect in the intestinal transport and processing of toxic (31-49) or immunostimulant (57-68 and the 33-mer 56-89) gliadin peptides was tested in patients with active celiac disease (ACD), patients with treated celiac disease (TCD), and controls. METHODS: Using duodenal biopsy specimens mounted in Ussing chambers, we measured electrical resistance, mucosal-to-serosal radiolabeled-peptide fluxes, and peptide processing during transport using radio-reverse-phase high-performance liquid chromatography. RESULTS: Peptide 31-49 fluxes (24.7 microg x 3 h(-1). cm(-2)) were increased in patients with ACD compared with controls and patients with TCD (12.7 and 12.3 microg x 3 h(-1). cm(-2); P < 0.01). In contrast, no increase was observed for peptide 57-68 or 56-89 (33-mer). Electrical resistance was decreased in patients with ACD versus controls (15.3 vs. 23.9 ohms. cm(2); P < 0.001). Peptide 57-68 was partially degraded by brush-border peptidases in controls but not in patients with celiac disease. However, it was totally degraded after intestinal transport both in controls and patients with celiac disease. Peptides 31-49 and 56-89 were resistant to brush-border peptidases in all groups of patients but were totally degraded during intestinal transport in controls and patients with TCD. In patients with ACD, however, 50% of peptide 31-49 was delivered intact into the serosal compartment and only partial degradation of the 33-mer was observed. These abnormalities were not related to a nonspecific paracellular leakage. CONCLUSIONS: Our data indicate that gliadin peptides, although poorly or not digested by intraluminal enzymes, can be fully digested by enterocytes in controls and patients with TCD. In patients with ACD, incomplete degradation of the 33-mer and protected transport of the peptide 31-49 might favor their respective immunostimulatory and toxic effects.

Adult↗
PubMed2003

Gastric Helicobacter infection inhibits development of oral tolerance to food antigens in mice.

The increase in the transcellular passage of intact antigens across the digestive epithelium infected with Helicobacter pylori may interfere with the regulation of mucosal immune responses. The aim of this work was to study the capacity of Helicobacter infection to inhibit the development of oral tolerance or to promote allergic sensitization and the capacity of a gastro-protective agent, rebamipide, to interfere with these processes in mice. Oral tolerance to ovalbumin (OVA) was studied in 48 C3H/He 4-week-old mice divided into four groups: (i) OVA-sensitized mice; (ii) OVA-"tolerized" mice (that is, mice that were rendered immunologically tolerant); (iii) H. felis-infected, OVA-tolerized mice; (iv) and H. felis-infected, OVA-tolerized, rebamipide-treated mice. Oral sensitization to hen egg lysozyme (HEL) was studied in 48 mice divided into four groups: (i) controls; (ii) HEL-sensitized mice; (iii) H. felis-infected, HEL-sensitized mice; and (iv) H. felis-infected, HEL-sensitized, rebamipide-treated mice. Specific anti-OVA or anti-HEL immunoglobulin E (IgE) and IgG1/IgG2a serum titers were measured by enzyme-linked immunosorbent assay. Additionally, the capacity of rebamipide to interfere with antigen presentation and T-cell activation in vitro, as well as absorption of rebamipide across the epithelial monolayer, was tested. H. felis infection led to the inhibition of oral tolerance to OVA, but rebamipide prevented this inhibitive effect of H. felis. H. felis infection did not enhance the sensitization to HEL, but rebamipide inhibited the development of this sensitization. Moreover, rebamipide inhibited in a dose-dependent manner antigen presentation and T-cell activation in vitro and was shown to be able to cross the epithelium at a concentration capable of inducing this inhibitory effect. We conclude that H. felis can inhibit the development of oral tolerance to OVA in mice and that this inhibition is prevented by rebamipide.

Administration, Oral↗
PubMed2002

In vitro transfer of clarithromycin and amoxicillin across the epithelial barrier: effect of Helicobacter pylori.

The mode of absorption of amoxicillin and clarithromycin, two antibiotics used in the treatment of Helicobacter pylori infection, has not been completely elucidated. The aims of this study were to investigate the passage of these antibiotics across normal and infected epithelium and to measure their accumulation in HT29-19A or Caco2 epithelial cell monolayers. In non-infected cultures, basal-to-apical fluxes were significantly higher than apical-to-basal fluxes for both antibiotics, but this difference disappeared in monolayers infected with H. pylori. In 24 h studies, clarithromycin, but not amoxicillin, showed rapid intracellular accumulation. No difference was found between the transepithelial passage of amoxicillin across the HT29-19A and Caco2 monolayers.

Amoxicillin↗