Gluten induces an intestinal cytokine response strongly dominated by interferon gamma in patients with celiac disease

Transcriptional regulation of the mucosal immune system mediated by T-bet

The immune system faces the arduous task of defending the mucosal surfaces from invading pathogens, but must simultaneously repress responses against commensal organisms and other inert antigens that are abundant in the external environment, as inappropriate immune activation might expose the host to increased risk of autoimmunity. The behavior of individual immune cells is governed by the expression of transcription factors that are responsible for switching immune response genes on and off. T-bet (T-box expressed in T cells) has emerged as one of the key transcription factors responsible for controlling the fate of both innate and adaptive immune cells, and its expression in different immune cells found at mucosal surfaces is capable of dictating the critical balance between permitting robust host immunity and limiting susceptibility to autoimmunity and allergy.

A genetic perspective on coeliac disease

Coeliac disease is an inflammatory disorder of the small intestine with an autoimmune component and strong heritability. Genetic studies have confirmed strong association to HLA and identified 39 nonHLA risk genes, mostly immune-related. Over 50% of the disease-associated single nucleotide polymorphisms are correlated with gene expression. Most of the coeliac disease-associated regions are shared with other immune-related diseases, as well as with metabolic, haematological or neurological traits, or cancer. We review recent progress in the genetics of coeliac disease and describe the pathways these genes are in, the functional consequences of the associated markers on gene expression and the genes shared between coeliac disease and other traits.

Enzymatic strategies to detoxify gluten: implications for celiac disease

Celiac disease is a permanent intolerance to the gliadin fraction of wheat gluten and to similar barley and rye proteins that occurs in genetically susceptible subjects. After ingestion, degraded gluten proteins reach the small intestine and trigger an inappropriate T cell-mediated immune response, which can result in intestinal mucosal inflammation and extraintestinal manifestations. To date, no pharmacological treatment is available to gluten-intolerant patients, and a strict, life-long gluten-free diet is the only safe and efficient treatment available. Inevitably, this may produce considerable psychological, emotional, and economic stress. Therefore, the scientific community is very interested in establishing alternative or adjunctive treatments. Attractive and novel forms of therapy include strategies to eliminate detrimental gluten peptides from the celiac diet so that the immunogenic effect of the gluten epitopes can be neutralized, as well as strategies to block the gluten-induced inflammatory response. In the present paper, we review recent developments in the use of enzymes as additives or as processing aids in the food biotechnology industry to detoxify gluten.

Bifidobacteria inhibit the inflammatory response induced by gliadins in intestinal epithelial cells via modifications of toxic peptide generation during digestion

Celiac disease (CD) is a chronic enteropathy triggered by intake of gliadin, the toxic component of gluten. This study aims at evaluating the capacity of different Bifidobacterium strains to counteract the inflammatory effects of gliadin-derived peptides in intestinal epithelial (Caco-2) cells. A commercial extract of several gliadin (Gld) types (alpha, beta, gamma, [symbol: see text] ) was subjected to in vitro gastrointestinal digestion (pepsin at pH 3, pancreatin-bile at pH 6), inoculated or not with cell suspensions (10(8) colony forming units/ml) of either B. animalis IATA-A2, B. longum IATA-ES1, or B. bifidum IATA-ES2, in a bicameral system. The generated gliadin-derived peptides were identified by reverse phase-HPLC-ESI-MS/MS. Caco-2 cell cultures were exposed to the different gliadin peptide digestions (0.25 mg protein/ml), and the mRNA expression of nuclear factor kappa-B (NF-kappaB), tumor necrosis factor alpha (TNF-alpha), and chemokine CXCR3 receptor were analyzed by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in stimulated cells. The production of the pro-inflammatory markers NF-kappaB p50, TNF-alpha, and IL-1beta (interleukine 1beta) by Caco-2 cells was also determined by ELISA. The peptides from gliadin digestions inoculated with bifidobacteria did not exhibit the toxic amino acid sequences identified in those noninoculated (alpha/beta-Gld [158-164] and alpha/beta-Gld [122-141]). The RT-PCR analysis evidenced a down-regulation in mRNA expression of pro-inflammatory biomarkers. Consistent with these results the production of NF-kappaB, TNF-alpha, and IL-1beta was reduced (18.2-22.4%, 28.0-64.8%, and abolished, respectively) in cell cultures exposed to gliadin digestions inoculated with bifidobacteria. Therefore, bifidobacteria change the gliadin-derived peptide pattern and, thereby, attenuate their pro-inflammatory effects on Caco-2 cells.

[Celiac disease]

Celiac disease is an enteropathy due to gluten intake in genetically predisposed individuals (HLA DQ2/DQ8). Celiac disease occurs in adults and children at rates approaching 1% of population in Europe and USA. Clinical features observed in celiac disease are extremely various and anaemia, oral aphthous stomatis, amenorrhea or articular symptoms may be the only presenting manifestations. Diagnosis relies on the evidence of histological villous atrophy in proximal small bowel and the presence of specific serum antibodies. Treatment relies on eviction of gluten (wheat, barley, rye) from diet. Gluten free diet allows prevention of malignant complications such as small bowel adenocarcinoma and lymphoma, and osteopenia. The main cause of resistance to gluten free diet is its poor observance. If not the case, serious complications of celiac disease, such as clonal refractory celiac sprue and intestinal T-cell lymphoma should be suspected. Current therapeutic challenges concern alternative to gluten free diet and new efficient treatments of lymphomatous complications.

Different Th1/Th2 responses to Anisakis simplex are related to distinct clinical manifestations in sensitized patients

Anisakis simplex is a fish parasite capable of inducing inflammatory and allergic reactions in humans who eat raw or undercooked fish. The aim of this study was to characterize the T helper type 1 (Th1)/Th2 immune response to parasite crude (CE) and thermostable (TsE) extracts in A. simplex-sensitized patients. Cytokines were quantified by a multiplex flow cytometric method in short-term whole blood cultures. Higher concentrations of IL-2, IL-4 and IL-5, measured with the CE and TsE, were found in patients than in controls. Patients showing urticaria-angio-oedema or anaphylaxis (UA/A) had higher total and specific IgE levels than those with gastrointestinal symptoms (GI). The UA/A group showed high levels of IL-5 and IL-4 and low expression of IFN-gamma than the GI group. The GI group had significantly higher IFN-gamma/IL4 ratio than the UA/A group. Four patients with severe GI symptoms reporting a delayed skin test reaction had very low values of specific IgE to A. simplex and higher IFN-gamma/IL4 ratios than that observed in other patients belonging to the GI group. This short-term whole blood test can be useful for immune response characterization in Anisakis infection and showed that heated parasite antigens are still capable of inducing cellular immune response in sensitized patients.

PPAR signaling pathway and cancer-related proteins are involved in celiac disease-associated tissue damage

Celiac disease (CD) is an immune-mediated disorder triggered by the ingestion of wheat gliadin and related proteins in genetically predisposed individuals. To find a proteomic CD diagnostic signature and to gain a better understanding of pathogenetic mechanisms associated with CD, we analyzed the intestinal mucosa proteome alterations using two dimensional difference gel electrophoresis (2D-DIGE) coupled with matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF ms) of CD patients with varying degrees of histological abnormalities defined by Marsh criteria and controls. Our results clearly evidenced the presence of two groups of patients: Group A, including controls and Marsh 0-I CD patients; and Group B, consisting of CD subjects with grade II-III Oberhuber-Marsh classification. Differentially expressed proteins were involved mainly in lipid, protein and sugar metabolism. Interestingly, in Group B, several downregulated proteins (FABP1, FABP2, APOC3, HMGCS2, ACADM and PEPCK) were implicated directly in the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Moreover, Group B patients presented a deregulation of some proteins involved in apoptosis/survival pathways: phosphatidylethanolamine-binding protein 1 (PEBP1), Ras-related nuclear protein (Ran) and peroxiredoxin 4 (PRDX4). PEBP1 downregulation and RAN and PRDX4 upregulation were associated with more severe tissue damage. Likewise, IgMs were found strongly upregulated in Group B. In conclusion, our results indicate that a downregulation of proteins involved in PPAR signaling and the modulation of several cancer-related proteins are associated with the highest CD histological score according to Oberhuber-Marsh classification.

Celiac disease: Alternatives to a gluten free diet

Celiac disease is a chronic inflammatory disorder of the small intestine caused by the ingestion of gluten or related rye and barley proteins. At present, the only available treatment is a strict gluten-exclusion diet. However, recent understanding of the molecular basis for this disorder has improved and enabled the identification of targets for new therapies. This article aims to critically summarize these recent studies.

Serum cytokine elevations in celiac disease: association with disease presentation

Celiac disease (CD) is an autoimmune disorder that is triggered by an immune response to gluten in genetically predisposed individuals. Although considered a primary gastrointestinal disease, CD is now known to have widespread systemic manifestations. We attempted to define the nature and role of systemic cytokine levels in the pathophysiology of CD. Multiplex cytokine assays were performed on four different groups of adult patients; patients with active CD (ACD), patients on a gluten-free diet (GFD) with positive TTG IgA antibodies, patients on a GFD with negative antibodies, and those with refractory CD (RCD). The results were compared with values in healthy adult controls. Patients with active CD and those on GFD with positive antibodies had significantly higher levels of proinflammatory cytokines, such as interferon-gamma, interleukin (IL)-1beta, tumor necrosis factor-alpha, IL-6 and IL-8, and also T(h)-2 cytokines such as IL-4 and IL-10, compared with normal controls and patients on GFD without antibodies. Interestingly patients on GFD for less than 1 year had significantly higher levels of both proinflammatory cytokines and T(h)2 cytokines compared with the patients on GFD for more than 1 year. In addition, a statistically significant correlation between levels of TTG IgA titers and serum levels of T(h)-2 cytokines IL-4 (p < 0.001), IL-10 (p < 0.001) and inflammatory cytokines such as IL-1alpha (p < 0.001), IL-1beta (p < 0.005), and IL-8 (p < 0.05) was observed.

Characterization of IL-17A-producing cells in celiac disease mucosa

Celiac disease (CD) is a gluten-sensitive enteropathy associated with a marked infiltration of the mucosa with IFN-gamma-secreting Th1 cells. Recent studies have shown that a novel subset of T cells characterized by expression of high levels of IL-17A, termed Th17 cells, may be responsible for pathogenic effects previously attributed to Th1 cells. In this study, we characterized the expression of IL-17A-producing cells in CD. By real-time PCR and ELISA, it was shown that expression of IL-17A RNA and protein is more pronounced in active CD biopsy specimens in comparison with inactive CD and normal mucosal biopsy specimens. Flow cytometry confirmed that IL-17A is overproduced in CD mucosa and that CD4(+) and CD4(+)CD8(+) cells were major sources. The majority of IL-17A-producing CD4(+) and CD4(+)CD8(+) cells coexpressed IFN-gamma but not CD161. The addition of a peptic-tryptic digest of gliadin to ex vivo organ cultures of duodenal biopsy specimens taken from inactive CD patients enhanced IL-17A production by both CD4(+) and CD4(+)CD8(+) cells. Because we previously showed that IL-21, a T cell-derived cytokine involved in the control of Th17 cell responses, is overproduced in CD, we next assessed whether IL-17A expression is regulated by IL-21. Blockade of IL-21 activity by a neutralizing IL-21 Ab reduced IL-17A expression in cultures of active CD and peptic-tryptic digest of gliadin-treated CD biopsy specimens. In conclusion, our data show that IL-17A is increased in CD and is produced by cells that also make IFN-gamma.

Noninflammatory gluten peptide analogs as biomarkers for celiac sprue

New tools are needed for managing celiac sprue, a lifelong immune disease of the small intestine. Ongoing drug trials are also prompting a search for noninvasive biomarkers of gluten-induced intestinal change. We have synthesized and characterized noninflammatory gluten peptide analogs in which key Gln residues are replaced by Asn or His. Like their proinflammatory counterparts, these biomarkers are resistant to gastrointestinal proteases, susceptible to glutenases, and permeable across enterocyte barriers. Unlike gluten peptides, however, they are not appreciably recognized by transglutaminase, HLA-DQ2, or disease-specific T cells. In vitro and animal studies show that the biomarkers can detect intestinal permeability changes as well as glutenase-catalyzed gastric detoxification of gluten. Accordingly, controlled clinical studies are warranted to evaluate the use of these peptides as probes for abnormal intestinal permeability in celiac patients and for glutenase efficacy in clinical trials and practice.

Tissue-mediated control of immunopathology in coeliac disease

Coeliac disease is an inflammatory disorder with autoimmune features that is characterized by destruction of the intestinal epithelium and remodelling of the intestinal mucosa following the ingestion of dietary gluten. A common feature of coeliac disease and many organ-specific autoimmune diseases is a central role for T cells in causing tissue destruction. In this Review, we discuss the emerging hypothesis that, in coeliac disease, intestinal tissue inflammation--induced either by infectious agents or by gluten--is crucial for activating T cells and eliciting their tissue-destructive effector functions.

Pivotal Advance: Bifidobacteria and Gram-negative bacteria differentially influence immune responses in the proinflammatory milieu of celiac disease

CD is a chronic inflammatory disorder of the small intestine that presents in genetically predisposed individuals following gluten consumption. In this study, the effects of Bifidobacterium (Bifidobacterium bifidum IATA-ES2 and Bifidobacterium longum ATCC15707) and Gram-negative bacteria (Bacteroides fragilis DSM2451, Escherichia coli CBL2, and Shigella CBD8 isolated from CD patients), alone and in the presence of CD triggers (gliadins and/or IFN-gamma) on surface marker expression and cytokine production by PBMCs, were determined. These effects were also evaluated in cocultures of PBMCs and Caco-2 cells. The Gram-negative bacteria induced higher secretion of Th1-type proinflammatory cytokines (IL-12 and/or IFN-gamma) than the Bifidobacterium strains. Shigella CBD8 and E. coli CBL2 up-regulated mainly HLA-DR and CD40 expression involved in Th1 activation, and Bifidobacterium strains up-regulated CD83 expression. Specific interactions among the studied bacteria, gliadins, and IFN-gamma, which favored the CD immune features, were also detected. Therefore, intestinal bacteria could be additional factors that regulate the ability of monocytes recruited to the mucosa to respond to gliadins and IFN-gamma in CD patients, influencing the course of the disease.

Celiac disease: from pathogenesis to novel therapies

Celiac disease has become one of the best-understood HLA-linked disorders. Although it shares many immunologic features with inflammatory bowel disease, celiac disease is uniquely characterized by (1) a defined trigger (gluten proteins from wheat and related cereals), (2) the necessary presence of HLA-DQ2 or HLA-DQ8, and (3) the generation of circulating autoantibodies to the enzyme tissue transglutaminase (TG2). TG2 deamidates certain gluten peptides, increasing their affinity to HLA-DQ2 or HLA-DQ8. This generates a more vigorous CD4(+) T-helper 1 T-cell activation, which can result in intestinal mucosal inflammation, malabsorption, and numerous secondary symptoms and autoimmune diseases. Moreover, gluten elicits innate immune responses that act in concert with the adaptive immunity. Exclusion of gluten from the diet reverses many disease manifestations but is usually not or less efficient in patients with refractory celiac disease or associated autoimmune diseases. Based on the advanced understanding of the pathogenesis of celiac disease, targeted nondietary therapies have been devised, and some of these are already in phase 1 or 2 clinical trials. Examples are modified flours that have been depleted of immunogenic gluten epitopes, degradation of immunodominant gliadin peptides that resist intestinal proteases by exogenous endopeptidases, decrease of intestinal permeability by blockage of the epithelial ZOT receptor, inhibition of intestinal TG2 activity by transglutaminase inhibitors, inhibition of gluten peptide presentation by HLA-DQ2 antagonists, modulation or inhibition of proinflammatory cytokines, and induction of oral tolerance to gluten. These and other experimental therapies will be discussed critically.

A deregulated immune response to gliadin causes a decreased villus height in DQ8 transgenic mice

Celiac disease (CD) is an enteropathy triggered by gluten and mediated by CD4+ T cells. A complete understanding of CD immunopathogenesis has been hindered due to the lack of adequate in vivo models. Here, we explored the effect of the inhibition of COX by indomethacin in wheat gliadin-sensitized transgenic mice expressing the HLA-DQ8 heterodimer, a molecule associated with CD. Treated mice showed a gliadin-specific immune response with a significant reduction of villus height, not linked to crypt hyperplasia and to expansion of intraepithelial T cells. Notably, treated mice showed increased numbers of CD25+ and apoptotic cells in the lamina propria, whereas high basal levels of IFN-gamma secretion, along with a reduced gliadin-specific IL-2 expression were detected in MLN. Biochemical assessment of the lesion revealed increased mRNA of Lamb3 and Adamts2, encoding for ECM proteins, and enhanced activities of metalloproteinases MMP1, 2 and 7. We conclude that an intestinal sensitivity to gliadin, in connection with COX inhibition, caused a decreased villus height in DQ8 tg mice. The lesion was induced by a deregulated mucosal cell immunity to gliadin, thus triggering activation of a specific ECM protein pathway responsible for lamina propria remodeling.

The effects of ALV003 pre-digestion of gluten on immune response and symptoms in celiac disease in vivo

Effective treatment of celiac disease is an unmet medical need. A glutenase that destroys immunogenic gluten peptides may be clinically valuable. Twenty patients with celiac disease were randomly assigned to ingest a large gluten meal (16 g daily for 3 days) pre-treated with ALV003, a mixture of highly specific glutenases (n=10), or pre-treated with placebo (n=10). Peripheral blood T-cell IFN-gamma ELISpot responses to gliadin and an immunogenic 33mer and symptoms were assessed. While baseline IFN-gamma ELISpot responses to gliadin and the 33mer were negative in all patients, a significant ELISpot response to gliadin or the 33mer was observed in 6 of 10 patients consuming placebo-treated gluten and 0 of 10 consuming ALV003 pre-treated gluten (p=0.011). Symptoms typically associated with gluten ingestion occurred in both groups and were not significantly reduced by ALV003 pre-treatment. ALV003 pre-treatment can abolish immune responses induced by gluten in patients with celiac disease.

Differential mucosal IL-17 expression in two gliadin-induced disorders: gluten sensitivity and the autoimmune enteropathy celiac disease

BACKGROUND

The immune-mediated enteropathy, celiac disease (CD), and gluten sensitivity (GS) are two distinct clinical conditions that are both triggered by the ingestion of wheat gliadin. CD, but not GS, is associated with and possibly mediated by an autoimmune process. Recent studies show that gliadin may induce the activation of IL-17-producing T cells and that IL-17 expression in the CD mucosa correlates with gluten intake.

METHODS

The small-intestinal mucosa of patients with CD and GS and dyspeptic controls was analyzed for expression of IL-17A mRNA by quantitative RT-PCR. The number of CD3+ and TCR-gammadelta lymphocytes and the proportion of CD3+ cells coexpressing the Th17 marker CCR6 were examined by in situ small-intestinal immunohistochemistry.

RESULTS

Mucosal expression of IL-17A was significantly increased in CD but not in GS patients, compared to controls. This difference was due to enhanced IL-17A levels in >50% of CD patients, with the remainder expressing levels similar to GS patients or controls, and was paralleled by a trend toward increased proportions of CD3+CCR6+ cells in intestinal mucosal specimens from these subjects.

CONCLUSION

We conclude that GS, albeit gluten-induced, is different from CD not only with respect to the genetic makeup and clinical and functional parameters, but also with respect to the nature of the immune response. Our findings also suggest that two subgroups of CD, IL-17-dependent and IL-17-independent, may be identified based on differential mucosal expression of this cytokine.

The IL6-174G/C polymorphism is associated with celiac disease susceptibility in girls

The aim of this paper was to study the role of IL6 and IL6R polymorphisms in celiac disease (CD) susceptibility. Because previous literature describes IL-6-related gender differences, sex-stratified analyses were performed. We undertook a case-control study with 374 pediatric CD patients and 853 healthy controls, all white Spaniards, and a family study using an independent sample including 303 trios for replication purposes. Three single-nucleotide polymorphisms tagging most of the variability of the IL6 gene (rs2069827, rs1800795 [-174G/C], and rs2069840) and one functional polymorphism in IL6R (rs8192284, Asp358Ala) were genotyped using TaqMan technology. Case-control comparisons were performed with the chi2 test and family data were analyzed with the transmission disequilibrium test. No association was observed between any tested polymorphism and overall CD. However, after sex stratification, we found that the IL6 promoter variant -174C increases the risk of developing CD specifically in female patients. This effect was observed both in the case-control and in the family studies (considering girls included in both studies vs boys: p = 0.021, odds ratio [OR] = 1.31, 95% confidence interval [CI] 1.03-1.66; and vs controls: p = 0.003, OR = 1.30, 95% CI 1.09-1.55). The functional -174G/C IL6 polymorphism seems to influence CD susceptibility in girls. The gender-specific role of IL-6 in this pathology must be further investigated.

Involvement of interleukin-15 and interleukin-21, two γ-chain-related cytokines, in celiac disease

Celiac disease (CD), an enteropathy caused by dietary gluten in genetically susceptible individuals, is histologically characterized by villous atrophy, crypt cell hyperplasia, and increased number of intra-epithelial lymphocytes. The nature of CD pathogenesis remains unclear, but recent evidence indicates that both innate and adaptive immune responses are necessary for the phenotypic expression and pathologic changes characteristic of CD. Extensive studies of molecules produced by immune cells in the gut of CD patients have led to identification of two cytokines, namely interleukin (IL)-15 and IL-21, which are thought to play a major role in orchestrating the mucosal inflammatory response in CD. Here we review the current knowledge of the expression and function of IL-15 and IL-21 in CD.

Diagnostic efficacy of the ELISA test for the detection of deamidated anti-gliadin peptide antibodies in the diagnosis and monitoring of celiac disease

BACKGROUND AND AIM

We evaluated the diagnostic performance of an ELISA test for anti-gliadin IgA and IgG antibodies, which uses synthetic deamidated gliadin peptides (anti-gliadin antibodies, AGAs) as coating; the results were compared with a test that uses extracted gliadin (AGAe).

METHODS

The study was conducted on the sera of 144 patients suffering from celiac disease (CD), including 20 patients with IgA deficiency and 9 who were following a gluten-free diet (GFD), and 129 controls.

RESULTS

In the 115 CD patients (without IgA deficiency), the sensitivity of AGAe IgA and IgG was 32.2 and 60.9%, whereas that of AGAs IgA and IgG was 59.1 and 72.2%. The specificity for AGAe IgA and IgG, and AGAs IgA and IgG was 93.8 and 89.9%, and 96.9% and 99.2%, respectively. Of the 20 patients with CD and IgA deficiency, 7 tested positive for AGAe IgG and 14 for AGAs IgG. The test using deamidated gliadin peptides performed better in terms of sensitivity and specificity than the AGA tests with extracted antigen.

CONCLUSIONS

The very high specificity of the AGAs IgG test (99.2%) also suggests that patients who test positive with this assay require a thorough followup, even if the anti-tissue transglutaminase antibodies (anti-tTG) and anti-endomysial autoantibodies (EMA) assays are negative.

Biochemical and Immuno-pathological Aspects of Tissue Transglutaminase in Coeliac Disease

Tissue transglutaminase (tTg) has been identified as the major autoantigen in coeliac disease (CD). ELISA methods have been developed for measuring the autoantibody. There are divergent reports on the effects of calcium on the antibody binding to tTg. Furthermore, zinc is a potent inhibitor of tTg. To better understand the role of transglutaminase in CD, we have studied the stability of commercial tTG, the effect of CD serum on tTg-activity and the effects of calcium and zinc on the antibody binding. The inclusion of calcium during the coating of the ELISA plates significantly increases the binding of the antibody, while zinc at physiological concentrations inhibits the binding. Moreover, our results show that commercial guinea pig liver Tg treated with calcium contains at least four major antigenic molecules and is a labile enzyme, which is degraded rapidly by contaminating proteases. Human serum contains anti-proteases that protect the enzyme. Probably, the labile character of commercial tTG explains the divergent reports on the effects of calcium on antibody binding. Finally, antibodies in serum from a CD patient do not seem to inhibit tTg activity. Hypothetically, low, intestinal Zn2+ -levels facilitate Ca2+-activation of tTg, which deamidates gliadin. A complex between tTg and modified gliadin forms the antigen and triggers the immune reaction leading to manifest CD. Hypozincaemia secondary to villous atrophy aggravates the induced disease.

Resistance to celiac disease in humanized HLA-DR3-DQ2-transgenic mice expressing specific anti-gliadin CD4+ T cells

Celiac disease is a chronic inflammatory enteropathy caused by cellular immunity to dietary gluten. More than 90% of patients carry HLA-DQ2 encoded by HLA-DQA1*05 and DQB1*02, and gluten-specific CD4(+) T cells from intestinal biopsies of these patients are HLA-DQ2-restricted, produce Th1 cytokines and preferentially recognize gluten peptides deamidated by tissue transglutaminase. We generated mice lacking murine MHC class II genes that are transgenic for human CD4 and the autoimmunity and celiac disease-associated HLA-DR3-DQ2 haplotype. Immunization with the alpha-gliadin 17-mer that incorporates the overlapping DQ2-alpha-I and DQ2-alpha-II epitopes immunodominant in human celiac disease generates peptide-specific HLA-DQ2-restricted CD4(+) T cells. When exposed to dietary gluten, naive or gliadin-primed mice do not develop pathology. Coincident introduction of dietary gluten and intestinal inflammation resulted in low-penetrance enteropathy and tissue transglutaminase-specific IgA. Two further strains of transgenic mice expressing HLA-DR3-DQ2 and human CD4, one with a NOD background and another TCR transgenic having over 90% of CD4(+) T cells specific for the DQ2-alpha-II epitope with a Th1 phenotype, were also healthy when consuming gluten. These humanized mouse models indicate that gluten ingestion can be tolerated without intestinal pathology even when HLA-DQ2-restricted CD4(+) T cell immunity to gluten is established, thereby implicating additional factors in controlling the penetrance of celiac disease.

Genetics and pathogenesis of coeliac disease

Coeliac disease is a common complex disease caused by a dietary intolerance to wheat gluten. Susceptibility is determined by both environmental and genetic factors. Coeliac disease results from complex interactions between the innate immune system, an adaptive T and B cell response and the mucosal barrier where inflammation is ultimately manifested. Genetic variants within the HLA region are well established, while variants outside of the HLA region have recently been identified. These variants are beginning to enhance our understanding of the immunology of the condition. This review focuses on the immunological pathogenesis of coeliac disease with special reference to the influence of genetic susceptibility on disease development.

Interferon-gamma released by gluten-stimulated celiac disease-specific intestinal T cells enhances the transepithelial flux of gluten peptides

Celiac sprue is a T-cell-mediated enteropathy elicited in genetically susceptible individuals by dietary gluten proteins. To initiate and propagate inflammation, proteolytically resistant gluten peptides must be translocated across the small intestinal epithelium and presented to DQ2-restricted T cells, but the effectors enabling this translocation under normal and inflammatory conditions are not well understood. We demonstrate that a fluorescently labeled antigenic 33-mer gluten peptide is translocated intact across a T84 cultured epithelial cell monolayer and that preincubation of the monolayer with media from gluten-stimulated, celiac patient-derived intestinal T cells enhances the apical-to-basolateral flux of this peptide in a dose-dependent, saturable manner. The permeability-enhancing activity of activated T-cell media is inhibited by blocking antibodies against either interferon-gamma or its receptor and is recapitulated using recombinant interferon-gamma. At saturating levels of interferon-gamma, activated T-cell media does not further increase transepithelial peptide flux, indicating the primacy of interferon-gamma as an effector of increased epithelial permeability during inflammation. Reducing the assay temperature to 4 degrees C reverses the effect of interferon-gamma but does not reduce basal peptide flux occurring in the absence of interferon-gamma, suggesting active transcellular transport of intact peptides is increased during inflammation. A panel of disease-relevant gluten peptides exhibited an inverse correlation between size and transepithelial flux but no apparent sequence constraints. Anti-interferon-gamma therapy may mitigate the vicious cycle of gluten-induced interferon-gamma secretion and interferon-gamma-mediated enhancement of gluten peptide flux but is unlikely to prevent translocation of gluten peptides in the absence of inflammatory conditions.

Coeliac disease

Coeliac disease is a chronic inflammatory disorder of the small bowel induced in genetically susceptible people by the irritant gluten and possibly other environmental cofactors. The disorder is characterised by a diverse clinical heterogeneity that ranges from asymptomatic to severely symptomatic, and it manifests with frank malabsorption, an increased morbidity attributable to the frequent association with autoimmune disorders and increased mortality resulting from the emergence of T-cell clonal proliferations that predispose the patient to enteropathy-type T-cell lymphoma. Our understanding of the molecular basis for this disorder has improved and enabled the identification of targets for new therapies, although a strict gluten-free diet remains the mainstay of safe and effective treatment. In this Seminar we critically reassess the clinical and diagnostic aspects of this disease and new perspectives in its pathogenesis and treatment.

Two-dimensional gel proteome reference map of human small intestine

Background

The small intestine is an important human organ that plays a central role in many physiological functions including digestion, absorption, secretion and defense. Duodenal pathologies include, for instance, the ulcer associated to Helicobacter Pylori infection, adenoma and, in genetically predisposed individuals, celiac disease. Alterations in the bowel reduce its capability to absorb nutrients, minerals and fat-soluble vitamins. Anemia and osteopenia or osteoporosis may develop as a consequence of vitamins malabsorption. Adenoma is a benign tumor that has the potential to become cancerous. Adult celiac disease patients present an overall risk of cancer that is almost twice than that found in the general population. These disease processes are not completely known.

To date, a two dimensional (2D) reference map of proteins expressed in human duodenal tissue is not yet available: the aim of our study was to characterize the 2D protein map, and to identify proteins of duodenal mucosa of adult individuals without duodenal illness, to create a protein database. This approach, may be useful for comparing similar protein samples in different laboratories and for the molecular characterization of intestinal pathologies without recurring to the use of surgical material.

Results

The enrolled population comprised five selected samples (3 males and 2 females, aged 19 to 42), taken from 20 adult subjects, on their first visit at the gastroenterology unit for a suspected celiac disease, who did not turn to be affected by any duodenal pathology after gastrointestinal and histological evaluations. Proteins extracted from the five duodenal mucosal specimens were singly separated by 2D gel electrophoresis. After image analysis of each 2D gel, 179 protein spots, representing 145 unique proteins, from 218 spots tested, were successfully identified by MALDI-TOF ms analysis. Normalized volumes, for each protein, have been reported for every gel. Proteins have been grouped according to their biological/metabolic functions.

Conclusion

This study represents to date the first detailed and reproducible 2D protein map of human duodenum. Spots identifications, reported in a database, will be helpful to identify the variability in protein expression levels, in isoforms expression, or in post-translational modifications associated to pathology or to a therapy.

Acute experimental colitis and human chronic inflammatory diseases share expression of inflammation-related genes with conserved Ets2 binding sites

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) are characterized by chronic inflammation of the gastrointestinal tract, with overlapping clinical characteristics and unknown etiology. We reasoned that in intestinal inflammation the initial activation of the innate immune response fails to resolve, finally resulting in uncontrolled chronic inflammatory bowel disease.

METHODS

To identify the early inflammatory events in colitis that remain active in human chronic colitis, we analyzed the changes of the colonic transcriptome during acute experimental colitis and compared the outcome with previously published profiles of affected tissues from patients with UC and CD, and as a control for intestinal inflammation in general, tissues from celiac disease patients. Rheumatoid arthritis synovial tissues were included as a nonintestinal inflammatory disease. The expression profiles of each disease were analyzed separately, in which diseased tissues were compared to unaffected tissues from the same anatomical location.

RESULTS

Gene ontology analysis of significantly regulated genes revealed a marked activation of immunity and defense processes in all diseases, except celiac disease, where immune activation is less prominent. The control region of upregulated genes contained an increase in Ets2 binding sites in experimental colitis, UC, and rheumatoid arthritis, and were associated with upregulated immune activity. In contrast, upregulated genes in celiac disease harbored the transcription factor binding site GLI, which binds to the Gli family of transcription factors involved in hedgehog signaling, affecting development and morphogenesis.

CONCLUSION

Ets2 may be an important transcription factor driving inflammation in acute as well as chronic inflammatory disease

Bifidobacterium strains suppress in vitro the pro-inflammatory milieu triggered by the large intestinal microbiota of coeliac patients

Background

Coeliac disease (CD) is an enteropathy characterized by an aberrant immune response to cereal-gluten proteins. Although gluten peptides and microorganisms activate similar pro-inflammatory pathways, the role the intestinal microbiota may play in this disorder is unknown. The purpose of this study was to assess whether the faecal microbiota of coeliac patients could contribute to the pro-inflammatory milieu characteristic of CD and the possible benefits of bifidobacteria.

Methods

The effect of faeces of 26 CD patients with active disease (mean age 5.5 years, range 2.1–12.0 years), 18 symptom-free coeliac disease (SFCD) patients (mean age 5.5 years, range 1.0–12.3 years) on a gluten-free diet for 1–2 years; and 20 healthy children (mean age 5.3 years, range 1.8–10.8 years) on induction of cytokine production and surface antigen expression in peripheral blood mononuclear cells (PBMCs) were determined. The possible regulatory roles of Bifidobacterium longum ES1 and B. bifidum ES2 co-incubated with faecal samples were also assessed in vitro.

Results

Faeces of both active CD and SFCD patients, representing an imbalanced microbiota, significantly increased TNF-α production and CD86 expression in PBMCs, while decreased IL-10 cytokine production and CD4 expression compared with control samples. Active CD-patient samples also induced significantly higher IFN-γ production compared with controls. However, Bifidobacterium strains suppressed the pro-inflammatory cytokine pattern induced by the large intestinal content of CD patients and increased IL-10 production. Cytokine effects induced by faecal microbiota seemed to be mediated by the NFκB pathway.

Conclusion

The intestinal microbiota of CD patients could contribute to the Th1 pro-inflammatory milieu characteristic of the disease, while B. longum ES1 and B. bifidum ES2 could reverse these deleterious effects. These findings hold future perspectives of interest in CD therapy.

Translational mini-review series on the immunogenetics of gut disease: immunogenetics of coeliac disease

Recent advances in immunological and genetic research in coeliac disease provide new and complementary insights into the immune response driving this chronic intestinal inflammatory disorder. Both approaches confirm the central importance of T cell-mediated immune responses to disease pathogenesis and have further begun to highlight other relevant components of the mucosal immune system, including innate immunity and the control of lymphocyte trafficking to the mucosa. In the last year, the first genome wide association study in celiac disease led to the identification of multiple new risk variants. These risk regions implicate genes involved in the immune system. Overlap with autoimmune diseases is striking with several of these regions being shown to confer susceptibility to other chronic immune-mediated diseases, particularly type 1 diabetes.

Adjuvant effect of Lactobacillus casei in a mouse model of gluten sensitivity

Probiotic strains have been reported to exert immunomodulatory activities in the gut-associated lymphoid tissue. In this study we explored the effect of Lactobacillus casei in transgenic mice expressing the human DQ8 heterodimer, a HLA molecule linked to Celiac Disease (CD). DQ8 mice, mucosally immunized with the gluten component gliadin, mounted an intestinal Th1-like response as observed in CD, without developing enteropathy. Co-administration of L. casei in sensitized mice specifically enhanced the gliadin-specific response mediated by CD4(+) T cells. Notably, both a strong increase of the gliadin-specific IFNgamma expression and a pro-inflammatory polarization of the cytokine milieu in the small intestinal mucosa were associated to the presence of the probiotic strain. However, this condition did not bring on any mucosal alteration. These findings suggest that the gliadin-specific enteropathy is not merely related to the HLA DQ8-restricted massive production of IFNgamma, but additional parameters are involved. Moreover, our data imply that the intrinsic adjuvanticity of L. casei can be exploited to further enhance both mucosal and systemic T cell-mediated responses.

Altered gene expression in highly purified enterocytes from patients with active coeliac disease

Background

Coeliac disease is a multifactorial inflammatory disorder of the intestine caused by ingestion of gluten in genetically susceptible individuals. Genes within the HLA-DQ locus are considered to contribute some 40% of the genetic influence on this disease. However, information on other disease causing genes is sparse. Since enterocytes are considered to play a central role in coeliac pathology, the aim of this study was to examine gene expression in a highly purified isolate of these cells taken from patients with active disease. Epithelial cells were isolated from duodenal biopsies taken from five coeliac patients with active disease and five non-coeliac control subjects. Contaminating T cells were removed by magnetic sorting. The gene expression profile of the cells was examined using microarray analysis. Validation of significantly altered genes was performed by real-time RT-PCR and immunohistochemistry.

Results

Enterocyte suspensions of high purity (98–99%) were isolated from intestinal biopsies. Of the 3,800 genes investigated, 102 genes were found to have significantly altered expression between coeliac disease patients and controls (p < 0.05). Analysis of these altered genes revealed a number of biological processes that are potentially modified in active coeliac disease. These processes include events likely to contibute to coeliac pathology, such as altered cell proliferation, differentiation, survival, structure and transport.

Conclusion

This study provides a profile of the molecular changes that occur in the intestinal epithelium of coeliac patients with active disease. Novel candidate genes were revealed which highlight the contribution of the epithelial cell to the pathogenesis of coeliac disease.

Parallels between pathogens and gluten peptides in celiac sprue

Pathogens are exogenous agents capable of causing disease in susceptible organisms. In celiac sprue, a disease triggered by partially hydrolyzed gluten peptides in the small intestine, the offending immunotoxins cannot replicate, but otherwise have many hallmarks of classical pathogens. First, dietary gluten and its peptide metabolites are ubiquitous components of the modern diet, yet only a small, genetically susceptible fraction of the human population contracts celiac sprue. Second, immunotoxic gluten peptides have certain unusual structural features that allow them to survive the harsh proteolytic conditions of the gastrointestinal tract and thereby interact extensively with the mucosal lining of the small intestine. Third, they invade across epithelial barriers intact to access the underlying gut-associated lymphoid tissue. Fourth, they possess recognition sequences for selective modification by an endogenous enzyme, transglutaminase 2, allowing for in situ activation to a more immunotoxic form via host subversion. Fifth, they precipitate a T cell–mediated immune reaction comprising both innate and adaptive responses that causes chronic inflammation of the small intestine. Sixth, complete elimination of immunotoxic gluten peptides from the celiac diet results in remission, whereas reintroduction of gluten in the diet causes relapse. Therefore, in analogy with antibiotics, orally administered proteases that reduce the host's exposure to the immunotoxin by accelerating gluten peptide destruction have considerable therapeutic potential. Last but not least, notwithstanding the power of in vitro methods to reconstitute the essence of the immune response to gluten in a celiac patient, animal models for the disease, while elusive, are likely to yield fundamentally new systems-level insights.

Infiltration of forkhead box P3-expressing cells in small intestinal mucosa in coeliac disease but not in type 1 diabetes

Because the role of regulatory T cells in the intestinal inflammation is unknown in coeliac disease (CD) and type 1 diabetes (T1D), the expression of forkhead box P3 (FoxP3), CD25, transforming growth factor-beta, interferon (IFN)-gamma, interleukin (IL)-4, IL-8, IL-10, IL-15 and IL-18 was measured by quantitative reverse transcription-polymerase chain reaction in the small intestinal biopsies from paediatric patients with active or potential CD, T1D and control patients. The numbers of FoxP3- and CD25-expressing cells were studied with immunohistochemistry. Enhanced intestinal expressions of FoxP3, IL-10 and IFN-gamma mRNAs were found in active CD when compared with controls (P-values < 0.001, 0.004, <0.001). In potential CD, only the expression of IFN-gamma mRNA was increased. The numbers of FoxP3-expressing cells were higher in active and potential CD (P < 0.001, P = 0.05), and the ratio of FoxP3 mRNA to the number of FoxP3-positive cells was decreased in potential CD when compared with controls (P = 0.007). The ratio of IFN-gamma to FoxP3-specific mRNA was increased in active and potential CD (P = 0.001 and P = 0.002). Patients with T1D had no changes in regulatory T cell markers, but showed increased expression of IL-18 mRNA. The impaired up-regulation of FoxP3 transcripts despite the infiltration of FoxP3-positive cells in potential CD may contribute to the persistence of inflammation. The increased ratio of IFN-gamma to FoxP3 mRNA in active and potential CD suggests an imbalance between regulatory and effector mechanisms. The increased intestinal expression of IL-18 mRNA in patients with T1D adds evidence in favour of the hypothesis that T1D is associated with derangements in the gut immune system.

Gliadin activates HLA class I-restricted CD8+ T cells in celiac disease intestinal mucosa and induces the enterocyte apoptosis

BACKGROUND & AIMS

The extensive infiltration of CD8(+) T cells in the intestinal mucosa of celiac disease (CD) patients is a hallmark of the disease. We identified a gliadin peptide (pA2) that is selectively recognized by CD8(+) T cells infiltrating intestinal mucosa of HLA-A2(+) CD patients. Herein, we investigated the phenotype, the tissue localization, and the effector mechanism of cells responsive to pA2 by using the organ culture of CD intestinal mucosa. The target of pA2-mediated cytotoxicity was also investigated by using the intestinal epithelial cell lines Caco2 and HT29, A2(+) and A2(-), respectively, as target cells.

METHODS

Jejunal biopsy specimens from CD patients were cultured in vitro with pA2, and cellular activation was evaluated by immunohistochemistry and cytofluorimetric analysis. Cytotoxicity of pA2-specific, intestinal CD8(+) T cells was assayed by granzyme-B and interferon-gamma release and by apoptosis of target cells.

RESULTS

pA2 challenge of A2(+) CD mucosa increased the percentage of CD8(+)CD25(+) and of CD80(+) cells in the lamina propria, the former mainly localized beneath the epithelium, as well as the number of terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling-positive cells (TUNEL(+)) in the epithelium. Intraepithelial CD3(+) cells and enterocyte expression of Fas were also increased. CD8(+)CD25(+) and CD8(+)FASL(+) T cells were significantly increased in cell preparations from biopsy specimens cultured with pA2. CD8(+) T-cell lines released both granzyme-B and interferon-gamma following recognition of pA2 when presented by Caco2 and not by HT29.

CONCLUSIONS

These data indicate that gliadins contain peptides able to activate, through a TCR/HLA class I interaction, CD8-mediated response in intestinal CD mucosa and to induce the enterocyte apoptosis.

IL23R: a susceptibility locus for celiac disease and multiple sclerosis?

Recent studies have shown association of the IL23R gene with inflammatory bowel disease, psoriasis and ankylosing spondylitis. We aimed at studying the involvement of IL23R in celiac disease (CD) and multiple sclerosis (MS). We performed a case-control study including 598 patients with CD, 414 with MS and 546 healthy controls, all of them white Spaniards. All samples were genotyped for two single nucleotide polymorphisms: rs7517847 and rs11209026 (Arg381Gln). Statistical analyses were performed using chi(2-)tests or the Fisher's exact test. The minor allele (Gln) of the coding variant Arg381Gln was significantly increased in CD and MS patients when compared to controls (8% in CD vs 6% in controls, P=0.02; 9% in MS, P=0.006). In MS, a stronger effect was observed in patients showing primary-progressive disease (16%, P=0.004). Moreover, heterozygotes for rs7517847 were significantly increased in this group of MS patients (81% in MS vs 48% in controls, P=0.0002). In conclusion, contrary to what has been described previously, the less frequent allele of the functional polymorphism Arg381Gln (rs11209026) seems to be increasing susceptibility to CD and MS, although in this last group of patients a stronger effect is observed in patients affected of a primary-progressive form.

The simultaneous presence of IL-1B and TNFA two-positions risk haplotypes enhances the susceptibility for celiac disease

To assess the joint contribution of interleukin 1 beta (IL-1B) and tumor necrosis factor alpha (TNFalpha) to the genetic risk of developing celiac disease (CD), we analyzed four biallelic polymorphisms of TNFA and IL-1B genes in 228 patients and 244 healthy controls. The individual contribution of TNFA -308A and IL-1B -511C alleles was weak (OR 1.47 and 1.66, respectively) and was null for TNFA -238 A/G and IL-1B +3953 C/T single nucleotide polymorphisms (SNPs). Due to the potential linkage disequilibrium between TNFA, human leukocyte antigen (HLA) -DQA1 and HLA-DQB1 genes, only individuals carrying DQ2 antigen (DQ2-positive) were considered to perform haplotype analyses. Two-position risk haplotypes were first defined by the combined presence of -511C and +3953T alleles for IL-1B (OR 9.402) or -308A and -238A alleles for TNFA (OR 15.389). The TNFA/IL-1B combined haplotype-stratified association analysis showed that the simultaneous presence of TNFA risk and IL-1B non-risk haplotypes (OR 13.32) but not TNFA non-risk and IL-1B risk haplotypes (OR 0.71) is associated with CD. Interestingly, our data suggest that the coexistence of both risk haplotypes seems to work synergistically (OR 29.59), which enhances the risk of developing CD.

Gluten affects epithelial differentiation-associated genes in small intestinal mucosa of coeliac patients

In coeliac disease gluten induces an immunological reaction in genetically susceptible patients, and influences on epithelial cell proliferation and differentiation in the small-bowel mucosa. Our aim was to find novel genes which operate similarly in epithelial proliferation and differentiation in an epithelial cell differentiation model and in coeliac disease patient small-bowel mucosal biopsy samples. The combination of cDNA microarray data originating from a three-dimensional T84 epithelial cell differentiation model and small-bowel mucosal biopsy samples from untreated and treated coeliac disease patients and healthy controls resulted in 30 genes whose mRNA expression was similarly affected. Nine of 30 were located directly or indirectly in the receptor tyrosine kinase pathway starting from the epithelial growth factor receptor. Removal of gluten from the diet resulted in a reversion in the expression of 29 of the 30 genes in the small-bowel mucosal biopsy samples. Further characterization by blotting and labelling revealed increased epidermal growth factor receptor and beta-catenin protein expression in the small-bowel mucosal epithelium in untreated coeliac disease patients compared to healthy controls and treated coeliac patients. We found 30 genes whose mRNA expression was affected similarly in the epithelial cell differentiation model and in the coeliac disease patient small-bowel mucosal biopsy samples. In particular, those genes involved in the epithelial growth factor-mediated signalling pathways may be involved in epithelial cell differentiation and coeliac disease pathogenesis. The epithelial cell differentiation model is a useful tool for studying gene expression changes in the crypt-villus axis.

Evidence for the role of interferon-alfa production by dendritic cells in the Th1 response in celiac disease

BACKGROUND & AIMS

Dendritic cells (DCs) play a crucial role in immune responses by controlling the extent and type of T-cell response to antigen. Celiac disease is a condition in which T-cell immunity to gluten plays an important pathogenic role, yet information on DCs is scant. We examined mucosal DCs in celiac disease in terms of phenotype, activation/maturation state, cytokine production, and function.

METHODS

Mucosal DCs from 48 celiacs and 30 controls were investigated by flow cytometry. In situ distribution of DCs was analyzed by confocal microscopy. Interferon (IFN)-alfa, interleukin (IL)-4, IL-5, IL-12p35, IL-12p40, IL-18, IL-23p19, IL-27, and transforming growth factor-beta transcripts were measured by real-time reverse-transcription polymerase chain reaction in sorted DCs. DC expression of IL-6, IL-12p40, and IL-10 was assessed by intracellular cytokine staining. The effect of IFN-alfa and IL-18 blockade on the gluten-induced IFN-gamma response in celiac biopsy specimens grown ex vivo also was investigated.

RESULTS

Mucosal DCs were increased in untreated, but not treated, celiacs. The majority of them were plasmacytoid with higher levels of maturation (CD83) and activation (CD80/CD86) markers. Higher transcripts of Th1 relevant cytokines, such as IFN-alfa, IL-18, and IL-23p19, were produced by celiac DCs, but because IL-12p40 was undetectable, a role for IL-23 is unlikely. Intracellular cytokine staining of celiac DCs showed higher IL-6, but lower IL-10 expression, and confirmed the lack of IL-12p40. Blocking IFN-alfa inhibited IFN-gamma transcripts in ex vivo organ culture of celiac biopsy specimens challenged with gluten.

CONCLUSIONS

These data suggest that IFN-alfa-producing DCs contribute to the Th1 response in celiac disease.

Transamidation of wheat flour inhibits the response to gliadin of intestinal T cells in celiac disease

BACKGROUND & AIMS

Celiac disease is characterized by activation of HLA-DQ2/DQ8-restricted intestinal gluten-specific CD4(+) T cells. In particular, gluten becomes a better T-cell antigen following deamidation catalyzed by tissue transglutaminase. To date, the only available therapy is represented by adherence to a gluten-free diet. Here, we examined a new enzyme strategy to preventively abolish gluten activity.

METHODS

Enzyme modifications of the immunodominant alpha-gliadin peptide p56-68 were analyzed by mass spectrometry, and peptide binding to HLA-DQ2 was simulated by modeling studies. Wheat flour was treated with microbial transglutaminase and lysine methyl ester; gliadin was subsequently extracted, digested, and deamidated. Gliadin-specific intestinal T-cell lines (iTCLs) were generated from biopsy specimens from 12 adult patients with celiac disease and challenged in vitro with different antigen preparations.

RESULTS

Tissue transglutaminase-mediated transamidation with lysine or lysine methyl ester of p56-68 or gliadin in alkaline conditions inhibited the interferon gamma expression in iTCLs; also, binding to DQ2 was reduced but not abolished, as suggested by in silico analysis. Lysine methyl ester was particularly effective in abrogating the activity of gliadin. Notably, a block in the response was observed when iTCLs were challenged with gliadin extracted from flour pretreated with microbial transglutaminase and lysine methyl ester.

CONCLUSIONS

Transamidation of wheat flour with a food-grade enzyme and an appropriate amine donor can be used to block the T cell-mediated gliadin activity. Considering the crucial role of adaptive immunity in celiac disease, our findings highlight the potential of the proposed treatment to prevent cereal toxicity.

Celiac disease: diagnosis, autoimmune mechanisms and treatment

Celiac disease is a systemic autoimmune disorder triggered by the ingestion of gluten found in wheat and related grains. Once considered rare, celiac disease is now thought to affect more than one in 100 individuals, and is commonly associated with other autoimmune disorders. It predisposes patients to an increased risk of malignancy if left untreated. Celiac disease is HLA restricted as only HLA-DQ2 and -DQ8 are able to bind deamidated gluten with sufficient affinity to trigger an immune response. Both cellular and humoral immune activation occur, leading to local tissue damage and antibody formation. These antibodies, primarily to tissue transglutaminase, are the basis for highly accurate serologic testing, although the gold standard for celiac disease diagnosis remains small intestinal biopsy. Currently, the only treatment for celiac disease is a life-long gluten-free diet, although multiple novel therapeutic modalities are being studied. Although most individuals with celiac disease respond completely to gluten withdrawal, 10-20% have persistent symptoms at some point during their course and less than 1% develop refractory celiac disease, an entity of substantial morbidity.

Paraoxonases are associated with intestinal inflammatory diseases and intracellularly localized to the endoplasmic reticulum

We demonstrated previously that the paraoxonase (PON1/2/3) genes and proteins are expressed in human intestinal biopsies and in Caco-2 cells. The current study aims were to explore whether PON1/2/3 expression is different in inflammatory bowel diseases (IBD) or celiac disease compared to healthy controls, and to explore the intracellular localization of PON1/2/3. Our results showed that significantly fewer biopsies expressed PON1 and PON3 in the duodenum of celiac patients (PON1, P<0.0001; PON3, P=0.03), in the terminal ileum of Crohn's patients (PON1, P=0.001; PON3, P=0.008), and in the colon of UC patients (PON1, P=0.02; PON3, P=0.06) compared to controls. Since all three disorders share markedly elevated inflammatory mediators we explored the PON1/2/3 mRNA expression on cytokine stimulation. No changes were observed in Caco-2 and HT29 cells. Immunofluorescence experiments localized PON1/2/3 exclusively to the endoplasmic reticulum (ER) in both CaCo-2 and HT29 cells. These results demonstrate for the first time a novel relationship between PON1 and PON3 expression and several inflammatory gastrointestinal disorders. Together with the localization of PON1/2/3 enzymes to the ER, it may be suggested that PON1/2/3 may have extracellular functions as part of the host response in IBD and celiac disease.

Gliadin regulates the NK-dendritic cell cross-talk by HLA-E surface stabilization

We analyzed the autologous NK cell interaction with gliadin-presenting dendritic cells. Gliadin is the known Ag priming the celiac disease (CD) pathogenesis. We demonstrate that gliadin prevents immature dendritic cells (iDCs) elimination by NK cells. Furthermore, cooperation between human NK cells-iDCs and T cells increases IFN-gamma production of anti-gliadin immune response. Gliadin fractions were analyzed for their capability to stabilize HLA-E molecules. The alpha and omega fractions conferred the protection from NK cell lysis to iDCs and increased their HLA-E expression. Gliadin pancreatic enzyme digest and a peptide derived from gliadin alpha increased HLA-E levels on murine RMA-S/HLA-E-transfected cells. Analysis of HLA-E expression in the small intestinal mucosa of gluten-containing diet celiac patients and organ culture experiments confirmed the in vitro data.

Reduced chemokine receptor 9 on intraepithelial lymphocytes in celiac disease suggests persistent epithelial activation

BACKGROUND & AIMS

Celiac disease is caused by an inappropriate immune response to dietary gluten, with increased epithelial lymphocyte infiltration in the duodenum/jejunum as a hallmark. The chemokine receptor 9 (CCR9) is a small intestinal homing receptor normally found on most mucosal T cells in this organ. Because CCR9 expression appears to be activation dependent, we examined CCR9 on duodenal T cells from untreated and treated (gluten-free diet) patients with celiac disease and healthy controls.

METHODS

Duodenal biopsy specimens and blood samples were obtained for histologic analysis and flow-cytometric CCR9 analysis of isolated lymphocytes. CCR9 expression after activation was studied in peripheral blood T cells from healthy volunteers.

RESULTS

The median number of CCR9(+) cells among CD3(+) T cells in epithelium and lamina propria, respectively, was 56% and 48% in controls, 11% and 40% in treated patients, and 1% and 8% in untreated patients. Significant differences occurred between controls and treated or untreated patients in the epithelium but only between controls and untreated patients in the lamina propria (P=.008, all comparisons). No such differences were seen in peripheral blood, but stimulation with phorbol myristate acetate and ionomycin and, to a lesser extent, stimulation via NKG2D reduced the CCR9 expression on blood T cells.

CONCLUSIONS

CCR9 expression is reduced on epithelial and lamina propria T cells in untreated celiac disease. Down-regulation of CCR9 persists in intraepithelial T cells from well-treated patients. This suggests ongoing immune activation preferentially within the epithelium.

Highly efficient gluten degradation by lactobacilli and fungal proteases during food processing: new perspectives for celiac disease

Presently, the only effective treatment for celiac disease is a life-long gluten-free diet. In this work, we used a new mixture of selected sourdough lactobacilli and fungal proteases to eliminate the toxicity of wheat flour during long-time fermentation. Immunological (R5 antibody-based sandwich and competitive enzyme-linked immunosorbent assay [ELISA] and R5 antibody-based Western blot), two-dimensional electrophoresis, and mass spectrometry (matrix-assisted laser desorption ionization-time of flight, strong-cation-exchange-liquid chromatography/capillary liquid chromatography-electrospray ionization-quadrupole-time of flight [SCX-LC/CapLC-ESI-Q-TOF], and high-pressure liquid chromatography-electrospray ionization-ion trap mass spectrometry) analyses were used to determine the gluten concentration. Assays based on the proliferation of peripheral blood mononuclear cells (PBMCs) and gamma interferon production by PBMCs and intestinal T-cell lines (iTCLs) from 12 celiac disease patients were used to determine the protein toxicity of the pepsin-trypsin digests from fermented wheat dough (sourdough). As determined by R5-based sandwich and competitive ELISAs, the residual concentration of gluten in sourdough was 12 ppm. Albumins, globulins, and gliadins were completely hydrolyzed, while ca. 20% of glutenins persisted. Low-molecular-weight epitopes were not detectable by SCX-LC/CapLC-ESI-Q-TOF mass spectrometry and R5-based Western blot analyses. The kinetics of the hydrolysis of the 33-mer by lactobacilli were highly efficient. All proteins extracted from sourdough activated PBMCs and induced gamma interferon production at levels comparable to the negative control. None of the iTCLs demonstrated immunoreactivity towards pepsin-trypsin digests. Bread making was standardized to show the suitability of the detoxified wheat flour. Food processing by selected sourdough lactobacilli and fungal proteases may be considered an efficient approach to eliminate gluten toxicity.

Neutrophil recruitment and barrier impairment in celiac disease: a genomic study

BACKGROUND & AIMS

Celiac disease is an enteropathy featuring villous atrophy, crypt hyperplasia, and lymphocytosis. Tissue remodeling is driven by an inflammatory reaction to gluten in genetically susceptible individuals. The adaptive pathway is considered the major immune response but recent evidence has indicated the involvement of innate immunity as well. To assess the contribution of either immune response we performed global gene expression profiling of the regenerating mucosa.

METHODS

Microarray hybridizations were performed with biopsy samples from 13 untreated patients, 31 patients on a gluten-free diet in various stages of remission, and 21 controls. Additional data were generated using low-density array and conventional quantitative reverse-transcription polymerase chain reaction, and immunohistochemistry.

RESULTS

A total of 108 differentially expressed immune-related genes were identified (50 innate, 43 adaptive, 9 both innate/adaptive, and 6 immunoregulatory). Expression levels showed a gradual change as opposed to the discrete histological transitions. In addition to details provided on the adaptive and innate immune pathways used, we observed a chronic recruitment of activated neutrophils. Neutrophil involvement was unabated in otherwise completely normalized remission patients.

CONCLUSIONS

We observed a contribution of both the innate and adaptive immune response in celiac disease pathogenesis. The discrepancy between the histological classification and the observed incremental change in immune-gene expression may have consequences for current diagnostic inclusion criteria. Enhanced neutrophil infiltration in both active and remission patients points to a genetic impairment of the intestinal barrier that may contribute to the cause rather than the consequence of celiac disease.