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

Gut microbes and adverse food reactions: Focus on gluten related disorders

Immediately following birth, the gastrointestinal tract is colonized with a complex community of bacteria, which helps shape the immune system. Under conditions of health, the immune system is able to differentiate between innocuous antigens, including food protein and commensals, and harmful antigens such as pathogens. However, patients with celiac disease (CD) develop an intolerance to gluten proteins which results in a pro-inflammatory T-cell mediated immune response with production of anti-gluten and anti-tissue transglutaminase antibodies. This adaptive immune response, in conjunction with activation of innate inflammatory cells, lead to destruction of the small intestinal mucosa. Overall 30% of the global population has genetic risk to develop CD. However, only a small proportion develop CD, suggesting that additional environmental factors must play a role in disease pathogenesis. Alterations in small intestinal microbial composition have recently been associated with active CD, indicating a possible role for the microbiota in CD. However, studies demonstrating causality are lacking. This review will highlight the recent data on the potential role of the microbiota in CD pathogenesis, the potential mechanisms, and discuss future research directions.

Paneth cell extrusion and release of antimicrobial products is directly controlled by immune cell-derived IFN-γ

Paneth cells (PCs) are terminally differentiated, highly specialized secretory cells located at the base of the crypts of Lieberkühn in the small intestine. Besides their antimicrobial function, PCs serve as a component of the intestinal stem cell niche. By secreting granules containing bactericidal proteins like defensins/cryptdins and lysozyme, PCs regulate the microbiome of the gut. Here we study the control of PC degranulation in primary epithelial organoids in culture. We show that PC degranulation does not directly occur upon stimulation with microbial antigens or bacteria. In contrast, the pro-inflammatory cytokine Interferon gamma (IFN-γ) induces rapid and complete loss of granules. Using live cell imaging, we show that degranulation is coupled to luminal extrusion and death of PCs. Transfer of supernatants from in vitro stimulated iNKT cells recapitulates degranulation in an IFN-γ-dependent manner. Furthermore, endogenous IFN-γ secretion induced by anti-CD3 antibody injection causes Paneth loss and release of goblet cell mucus. The identification of IFN-γ as a trigger for degranulation and extrusion of PCs establishes a novel effector mechanism by which immune responses may regulate epithelial status and the gut microbiome.

Dietary gluten and the development of type 1 diabetes

Gluten proteins differ from other cereal proteins as they are partly resistant to enzymatic processing in the intestine, resulting in a continuous exposure of the proteins to the intestinal immune system. In addition to being a disease-initiating factor in coeliac disease (CD), gluten intake might affect type 1 diabetes development. Studies in animal models of type 1 diabetes have documented that the pathogenesis is influenced by diet. Thus, a gluten-free diet largely prevents diabetes in NOD mice while a cereal-based diet promotes diabetes development. In infants, amount, timing and mode of introduction have been shown to affect the diabetogenic potential of gluten, and some studies now suggest that a gluten-free diet may preserve beta cell function. Other studies have not found this effect. There is evidence that the intestinal immune system plays a primary role in the pathogenesis of type 1 diabetes, as diabetogenic T cells are initially primed in the gut, islet-infiltrating T cells express gut-associated homing receptors, and mesenteric lymphocytes transfer diabetes from NOD mice to NOD/severe combined immunodeficiency (SCID) mice. Thus, gluten may affect diabetes development by influencing proportional changes in immune cell populations or by modifying the cytokine/chemokine pattern towards an inflammatory profile. This supports an important role for gluten intake in the pathogenesis of type 1 diabetes and further studies should be initiated to clarify whether a gluten-free diet could prevent disease in susceptible individuals or be used with newly diagnosed patients to stop disease progression.

Gliadin intake alters the small intestinal mucosa in indomethacin-treated HLA-DQ8 transgenic mice

Celiac disease (CD) is an enteropathy caused by the ingestion of wheat gluten in genetically susceptible individuals. A complete understanding of the pathogenic mechanisms in CD has been hindered because of the lack of adequate in vivo models. In the present study, we explored the events after the intragastric administration of gliadin and of the albumin/globulin fraction from wheat in human leukocyte antigen-DQ8 transgenic mice (DQ8 mice) treated with indomethacin, an inhibitor of cyclooxygenases (COXs). After 10 days of treatment, mice showed a significant reduction of villus height, increased crypt depth, increased number of lamina propria-activated macrophages, and high basal interferon-γ secretion in mesenteric lymph nodes, all of which were specifically related to gliadin intake, whereas the albumin/globulin fraction of wheat was unable to induce similar changes. Cotreatment with NS-398, a specific inhibitor of COX-2, also induced the intestinal lesion. Enteropathy onset was further characterized by high levels of oxidative stress markers, similar to CD. Biochemical assessment of the small intestine revealed the specific activation of matrix metalloproteinases 2 and 9, high caspase-3 activity, and a significant increase of tissue transglutaminase protein levels associated with the intestinal lesion. Notably, after 30 days of treatment, enteropathic mice developed serum antibodies toward gliadin (IgA) and tissue transglutaminase (IgG). We concluded that gliadin intake in combination with COX inhibition caused a basal inflammatory status and an oxidative stress condition in the small intestine of DQ8 mice, thus triggering the mucosal lesion and, subsequently, an antigen-specific immunity.

Defective expression of scavenger receptors in celiac disease mucosa

Celiac disease (CD) is a gluten sensitive enteropathy characterized by a marked infiltration of the mucosa with immune cells, over-production of inflammatory cytokines and epithelial cell damage. The factors/mechanisms that sustain and amplify the ongoing mucosal inflammation in CD are not however fully understood. Here, we have examined whether in CD there is a defective clearance of apoptotic cells/bodies, a phenomenon that helps promote tolerogenic signals thus liming pathogenic responses. Accumulation of apoptotic cells and bodies was more pronounced in the epithelial and lamina propria compartments of active CD patients as compared to inactive CD patients and normal controls. Expression of scavenger receptors, which are involved in the clearance of apoptotic cells/bodies, namely thrombospondin (TSP)-1, CD36 and CD61, was significantly reduced in active CD as compared to inactive CD and normal mucosal samples. Consistently, lamina propria mononuclear cells (LPMC) of active CD patients had diminished ability to phagocyte apoptotic cells. Interleukin (IL)-15, IL-21 and interferon-γ, cytokines over-produced in active CD, inhibited the expression of TSP-1, CD36, and CD61 in normal intestinal LPMC. These results indicate that CD-related inflammation is marked by diminished clearance of apoptotic cells/bodies, thus suggesting a role for such a defect in the ongoing mucosal inflammation in this disorder.

Noncontaminated dietary oats may hamper normalization of the intestinal immune status in childhood celiac disease

OBJECTIVES:

Life-long, strict gluten-free diet (GFD) is the only treatment for celiac disease (CD). Because there is still uncertainty regarding the safety of oats for CD patients, the aim was to investigate whether dietary oats influence the immune status of their intestinal mucosa.

METHODS:

Paired small intestinal biopsies, before and after >11 months on a GFD, were collected from children with CD who were enrolled in a randomized, double-blind intervention trial to either of two diets: standard GFD (GFD-std; n=13) and noncontaminated oat-containing GFD (GFD-oats; n=15). Expression levels of mRNAs for 22 different immune effector molecules and tight junction proteins were determined by quantitative reverse transcriptase (RT)-PCR.

RESULTS:

The number of mRNAs that remained elevated was higher in the GFD-oats group (P=0.05). In particular, mRNAs for the regulatory T cell (Treg) signature molecules interleukin-10 (IL-10) and transforming growth factor-β1 (TGF-β1), the cytotoxicity-activating natural killer (NK) receptors KLRC2/NKG2C and KLRC3/NKG2E, and the tight junction protein claudin-4 remained elevated. Between the two groups, most significant differences were seen for claudin-4 (P=0.003) and KLRC3/NKG2E (P=0.04).

CONCLUSIONS:

A substantial fraction of pediatric CD patients seem to not tolerate oats. In these patients, dietary oats influence the immune status of the intestinal mucosa with an mRNA profile suggesting presence of activated cytotoxic lymphocytes and Tregs and a stressed epithelium with affected tight junctions. Assessment of changes in levels of mRNA for claudin-4 and KLC3/NKG2E from onset to after a year on oats containing GFD shows promise to identify these CD patients.

IL-15: a central regulator of celiac disease immunopathology

Interleukin-15 (IL-15) exerts many biological functions essential for the maintenance and function of multiple cell types. Although its expression is tightly regulated, IL-15 upregulation has been reported in many organ-specific autoimmune disorders. In celiac disease, an intestinal inflammatory disorder driven by gluten exposure, the upregulation of IL-15 expression in the intestinal mucosa has become a hallmark of the disease. Interestingly, because it is overexpressed both in the gut epithelium and in the lamina propria, IL-15 acts on distinct cell types and impacts distinct immune components and pathways to disrupt intestinal immune homeostasis. In this article, we review our current knowledge of the multifaceted roles of IL-15 with regard to the main immunological processes involved in the pathogenesis of celiac disease.

Sampling of proximal and distal duodenal biopsies in the diagnosis and monitoring of celiac disease

BACKGROUND

Since celiac disease-associated mucosal lesions are patchy, the diagnosis of the disease requires histological evaluation of multiple duodenal biopsies.

AIM

To examine whether adequate biopsy sampling in either the bulb or distal duodenum is sufficient to diagnose celiac disease.

METHODS

Twenty-five patients with positive celiac disease-specific serology and 17 patients with negative serology, who were on a gluten-containing diet, and 13 celiac disease patients on a gluten-free diet were consecutively and prospectively enrolled. Mucosal damage, anti-transglutaminase-2 IgA deposits, interferon-γ, interleukin-17A and interleukin-15 transcripts were evaluated in bulb and distal duodenal biopsies.

RESULTS

All patients with positive celiac disease-specific serology exhibited villous atrophy in both duodenal sites. In this group, mucosal anti-transglutaminase-2 IgA deposits were found in 24/25 (96%) bulb samples and 22/25 (88%) distal duodenal samples. No villous atrophy was documented in patients with negative serology. Interferon-γ and interleukin-17A were over-expressed in both duodenal sites of patients with villous atrophy, unlike patients with normal duodenal morphology (p<0.001). Among treated celiac disease patients, 2 (15.4%) had villous atrophy exclusively in the bulb and 6 (46.2%) had minimal histological abnormalities at both sites.

CONCLUSION

Sampling in the bulb and distal duodenum could be sufficient to diagnose/exclude celiac disease.

IL-15 controls T cell functions through its influence on CD30 and OX40 antigens in Celiac Disease

AIM

To evaluate the ability of interleukin (IL)-15 to control T cell functions through its influence on CD30 and OX40 expressing cells in Celiac Disease (CD). In peripheral blood (PB), by examining the expression of OX40 in conventional effectors cells and T cells with a phenotypic specialization of regulatory cells [CD4+CD25high forkhead box protein 3 (Foxp3)+], and the co stimulation of IFN-γ and IL-4 production within CD30 and OX40 positive subsets of T cells. At the duodenal mucosa, by assessing the expression of CD30 and OX40 in intraepithelial (IE) and lamina propria (LP) lymphocytes (IEL, LPL).

PATIENTS AND METHODS

PB and duodenal mucosal biopsies were obtained from 38 patients with classic CD (Cel) and 38 healthy controls (HC). Analysis of cell surface and/or intracellular antigens was performed in anti-CD3-treated PB mononuclear cells (PBMC) before and after treatment with recombinant IL-15 (rIL-15), and in IE and LP cellular suspensions prepared from duodenal biopsies pre-treated with/without rIL-15.

RESULTS

A subpopulation of CD3+OX40+ T blasts was induced in Cel and HC by a 3days treatment of PBMC with anti-CD3 and decreased its size thereafter, regardless of the presence of rIL-15. However, the addition of rIL-15 to T blasts distinctively induced the survival of T cells with a regulatory phenotype that expresses OX40 antigen in Cel (p<0.05). Celiac patients showed higher frequencies of IFN-γ-producing CD3+CD30+ blasts before and after treatment with rIL-15 (p<0.05, vs. HC). IL-15 increased the frequencies of CD3+CD30+ LPL (HC: p<0.05, Cel: p<0.05) but not of CD3+OX40+ LPL, and CD30 or OX40 positive IEL.

CONCLUSIONS

The distinctive control of OX40+ cells with a T regulatory phenotype mediated by the influence of IL-15 comes out as new function of this cytokine in the context of CD. The higher production of IFN-γ by a subpopulation of peripheral CD3+CD30+ cells contributes to the type I biased immune response.

Testing safety of germinated rye sourdough in a celiac disease model based on the adoptive transfer of prolamin-primed memory T cells into lymphopenic mice

The current treatment for celiac disease is strict gluten-free diet. Technical processing may render gluten-containing foods safe for consumption by celiac patients, but so far in vivo safety testing can only be performed on patients. We modified a celiac disease mouse model to test antigenicity and inflammatory effects of germinated rye sourdough, a food product characterized by extensive prolamin hydrolysis. Lymphopenic Rag1-/- or nude mice were injected with splenic CD4+CD62L-CD44high-memory T cells from gliadin- or secalin-immunized wild-type donor mice. We found that: 1) Rag1-/- recipients challenged with wheat or rye gluten lost more body weight and developed more severe histological duodenitis than mice on gluten-free diet. This correlated with increased secretion of IFNγ, IL-2, and IL-17 by secalin-restimulated splenocytes. 2) In vitro gluten testing using competitive R5 ELISA demonstrated extensive degradation of the gluten R5 epitope in germinated rye sourdough. 3) However, in nude recipients challenged with germinated rye sourdough (vs. native rye sourdough), serum anti-secalin IgG/CD4+ T helper 1-associated IgG2c titers were only reduced, but not eliminated. In addition, there were no reductions in body weight loss, histological duodenitis, or T cell cytokine secretion in Rag1-/- recipients challenged accordingly.

IN CONCLUSION

1) prolamin-primed CD4+CD62L-CD44high-memory T cells induce gluten-sensitive enteropathy in Rag1-/- mice. 2) Hydrolysis of secalins in germinated rye sourdough remains incomplete. Secalin peptides retain B and T cell stimulatory capacity and remain harmful to the intestinal mucosa in this celiac disease model. 3) Current antibody-based prolamin detection methods may fail to detect antigenic gluten fragments in processed cereal food products.

A metabolomic perspective on coeliac disease

Metabolomics is an "omic" science that is now emerging with the purpose of elaborating a comprehensive analysis of the metabolome, which is the complete set of metabolites (i.e., small molecules intermediates) in an organism, tissue, cell, or biofluid. In the past decade, metabolomics has already proved to be useful for the characterization of several pathological conditions and offers promises as a clinical tool. A metabolomics investigation of coeliac disease (CD) revealed that a metabolic fingerprint for CD can be defined, which accounts for three different but complementary components: malabsorption, energy metabolism, and alterations in gut microflora and/or intestinal permeability. In this review, we will discuss the major advancements in metabolomics of CD, in particular with respect to the role of gut microbiome and energy metabolism.

Expression pattern of T-helper 17 cell signaling pathway and mucosal inflammation in celiac disease

OBJECTIVE

The aim was to investigate the mucosal activation of a broad range of genes associated with the T-helper 17 cell (Th17) signaling pathway in children at different stages of celiac disease (CD), including children with increased risk for CD and children with untreated and gluten-free diet (GFD)-treated CD.

MATERIAL AND METHODS

Small intestinal biopsies were taken from children with untreated and GFD-treated CD, transglutaminase antibody (TGA)-positive children with potential CD, and reference children. Real-time polymerase chain reaction (PCR) arrays were used to study the gene expression pattern of Th17-related genes, and quantitative PCR was used to study the interleukin (IL)-17A expression.

RESULTS

The mucosal expression of CD8A was elevated at all stages of CD. Children with untreated CD had diminished levels of IL-17RE, IL-23R, RORc, STAT6, CCL22, NFATC2, IL-18, CD4, CD247, and matrix metalloproteinase (MMP)9 but had elevated levels of MMP3, IL-17, interferon-γ (IFN-γ) and CD8A, compared to references. The majority of the aforementioned genes, being differentially expressed in untreated CD, displayed similar expression in GFD-treated children and references. Children with untreated and GFD-treated CD had elevated expression of IFN-γ but had reduced expression of CD247. Interestingly, children with potential CD displayed reduced FOXP3, IL-21, and IL-17A levels.

CONCLUSION

Mucosal upregulation of Th17 immunity occurs at the late stage of disease and is downregulated with dietary treatment, thus indicating that IL-17 immunity is not a fundamental feature of CD as Th1 immunity, which is not fully downregulated by GFD.

Molecular mechanisms of the adaptive, innate and regulatory immune responses in the intestinal mucosa of celiac disease patients

Celiac disease is a complex genetic disorder that affects the small intestine of genetically predisposed individuals when they ingest gluten, a dietary protein. Although several genome screens have been successful in identifying susceptibility loci in celiac disease, the only genetic contributors identified so far are the human leukocyte antigen (HLA)-DQ2/DQ8 molecules. One of the most important aspects in the pathogenesis of celiac disease is the activation of a T-helper 1 immune response, when the antigen-presenting cells that express HLA-DQ2/DQ8 molecules present the toxic gluten peptides to reactive CD4(+) T-cells. Recently, new insights into the activation of an innate immune response have also been described. It is generally accepted that the immune response triggers destruction of the mucosa in the small intestine of celiac disease patients. Hence, the activation of a detrimental immune response in the intestine of celiac disease patients appears to be key in the initiation and progression of the disease. This review summarizes the immunologic pathways that have been studied in celiac disease thus far, and will point to new potential candidate genes and pathways involved in the etiopathogenesis of celiac disease, which should lead to novel alternatives for diagnosis and treatment.

Increased production of interleukin-21, but not interleukin-17A, in the small intestine characterizes pediatric celiac disease

Celiac disease (CD) is caused by inflammatory CD4(+) T-cell responses to dietary gluten. It is unclear whether interleukin (IL)-21 and IL-17A contribute to CD onset and lesion severity; therefore, we investigated IL-21 and IL-17A expression in biopsies from pediatric CD patients with different histopathological scores. High numbers of IL-21-producing cells were observed in pediatric CD lesions, even Marsh 1-2 lesions, whereas increased numbers of IL-17 secreting cells were not observed. Intraepithelial lymphocytes, CD4(+) T cells and also neutrophils secreted IL-21. Flow cytometry of lamina propria cells revealed a large population of IL-21- and interferon-γ (IFN-γ)-secreting CD3(+) T cells that did not secrete IL-17A. Adult CD patient biopsies also contained high numbers of IL-21-positive cells; however, enhanced numbers of IL-17-positive cells were observed in a small subgroup of patients with severe lesions. As duodenal tissue damage increases contact with microbe-associated molecular patterns, we hypothesized that microbial sensing by Toll-like receptors (TLRs) modulates T cell-derived cytokine secretion. Costimulation with TLR3 ligands during polyclonal T-cell activation significantly increased IL-21 secretion, whereas TLR2 ligands selectively enhanced IL-17A. These results demonstrate that an IL-17A-independent increase in IL-21 production by CD4(+) T cells is characteristic of pediatric CD. We hypothesize that incidental IL-17 secretion is caused by tissue damage rather than gluten-specific responses.

Immunoregulatory pathways are active in the small intestinal mucosa of patients with potential celiac disease

OBJECTIVES

Potential celiac disease (CD) relates to subjects with a normal small intestinal mucosa who are at increased risk of developing CD as indicated by positive CD-associated serology. The objective of this study was to investigate in the small intestinal mucosa of such patients the state of immunological activation with special emphasis on immunoregulatory circuits.

METHODS

Duodenal biopsies from active CD (n=48), potential CD (n=58), and control patients (n=45) were studied. RNA expression for interferon γ (IFNγ) and interleukin-10 (IL-10) were quantified by real-time quantitative PCR. The percentage of CD4+CD25+Foxp3+ T regulatory cells (Foxp3+Tregs) was determinated by flow cytometry and the number of Foxp3+ and IL-15+ cells by immunohistochemistry. Furthermore, we analyzed the suppressive function of CD4+CD25+ T cells, isolated from potential CD biopsy samples, as well as the effect of IL-15, on autologous peripheral blood responder CD4+CD25- T cells.

RESULTS

In potential CD patients with Marsh 1 lesion, IFNγ-RNA expression was significantly less than in active, but enhanced if compared with potential CD patients with Marsh 0 lesion and with controls (P<0.001). The number of IL-15+ cells in subjects with potential CD was increased in comparison with controls (P<0.05), but lower than active CD (P<0.01). IL-10-RNA expression was upregulated in Marsh 0 potential CD patients if compared with those with Marsh 1 lesion (P<0.01) and controls (P<0.001), whereas there were no differences with active CD. The ratio IL-10/IFNγ reached the highest value in Marsh 0 potential CD compared with the other groups (P<0.05). The percentage of Foxp3+Tregs was also higher in potential CD compared with controls (P<0.05), although it was lower than in active CD (P<0.01). In co-culture assay, intestinal CD4+CD25+ T cells from potential CD patients exerted suppressive effects on T responder cells, and their activity was not impaired by IL-15.

CONCLUSIONS

Potential CD patients show a low grade of inflammation that likely could be due to active regulatory mechanisms preventing the progression toward a mucosal damage.

Maize prolamins could induce a gluten-like cellular immune response in some celiac disease patients

Celiac disease (CD) is an autoimmune-mediated enteropathy triggered by dietary gluten in genetically prone individuals. The current treatment for CD is a strict lifelong gluten-free diet. However, in some CD patients following a strict gluten-free diet, the symptoms do not remit. These cases may be refractory CD or due to gluten contamination; however, the lack of response could be related to other dietary ingredients, such as maize, which is one of the most common alternatives to wheat used in the gluten-free diet. In some CD patients, as a rare event, peptides from maize prolamins could induce a celiac-like immune response by similar or alternative pathogenic mechanisms to those used by wheat gluten peptides. This is supported by several shared features between wheat and maize prolamins and by some experimental results. Given that gluten peptides induce an immune response of the intestinal mucosa both in vivo and in vitro, peptides from maize prolamins could also be tested to determine whether they also induce a cellular immune response. Hypothetically, maize prolamins could be harmful for a very limited subgroup of CD patients, especially those that are non-responsive, and if it is confirmed, they should follow, in addition to a gluten-free, a maize-free diet.

Duodenal-mucosal bacteria associated with celiac disease in children

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of cereal gluten proteins. This disorder is associated with imbalances in the gut microbiota composition that could be involved in the pathogenesis of CD. The aim of this study was to characterize the composition and diversity of the cultivable duodenal mucosa-associated bacteria of CD patients and control children. Duodenal biopsy specimens from patients with active disease on a gluten-containing diet (n = 32), patients with nonactive disease after adherence to a gluten-free diet (n = 17), and controls (n = 8) were homogenized and plated on plate count agar, Wilkins-Chalgren agar, brain heart agar, or yeast, Casitone, and fatty acid agar. The isolates were identified by partial 16S rRNA gene sequencing. Renyi diversity profiles showed the highest diversity values for active CD patients, followed by nonactive CD patients and control individuals. Members of the phylum Proteobacteria were more abundant in patients with active CD than in the other child groups, while those of the phylum Firmicutes were less abundant. Members of the families Enterobacteriaceae and Staphylococcaceae, particularly the species Klebsiella oxytoca, Staphylococcus epidermidis, and Staphylococcus pasteuri, were more abundant in patients with active disease than in controls. In contrast, members of the family Streptococcaceae were less abundant in patients with active CD than in controls. Furthermore, isolates of the Streptococcus anginosus and Streptococcus mutans groups were more abundant in controls than in both CD patient groups, regardless of inflammatory status. The findings indicated that the disease is associated with the overgrowth of possible pathobionts that exclude symbionts or commensals that are characteristic of the healthy small intestinal microbiota.

Prevalence and sensitization of atopic allergy and coeliac disease in the Northern Sweden Population Health Study

Background

Atopic allergy is effected by a number of environmental exposures, such as dry air and time spent outdoors, but there are few estimates of the prevalence in populations from sub-arctic areas.

Objective

To determine the prevalence and severity of symptoms of food, inhalation and skin-related allergens and coeliac disease (CD) in the sub-arctic region of Sweden. To study the correlation between self-reported allergy and allergy test results. To estimate the heritability of these estimates.

Study design

The study was conducted in Karesuando and Soppero in Northern Sweden as part of the Northern Sweden Population Health Study (n=1,068). We used a questionnaire for self-reported allergy and CD status and measured inhalation-related allergens using Phadiatop, food-related allergens using the F×5 assay and IgA and IgG antibodies against tissue transglutaminase (anti-tTG) to indicate prevalence of CD.

Results

The prevalence of self-reported allergy was very high, with 42.3% reporting mild to severe allergy. Inhalation-related allergy was reported in 26.7%, food-related allergy in 24.9% and skin-related allergy in 2.4% of the participants. Of inhalation-related allergy, 11.0% reported reactions against fur and 14.6% against pollen/grass. Among food-related reactions, 14.9% reported milk (protein and lactose) as the cause. The IgE measurements showed that 18.4% had elevated values for inhalation allergens and 11.7% for food allergens. Self-reported allergies and symptoms were positively correlated (p<0.01) with age- and sex-corrected inhalation allergens. Allergy prevalence was inversely correlated with age and number of hours spent outdoors. High levels of IgA and IgG anti-tTG antibodies, CD-related allergens, were found in 1.4 and 0.6% of participants, respectively. All allergens were found to be significantly (p<3 e–10) heritable, with estimated heritabilities ranging from 0.34 (F×5) to 0.65 (IgA).

Conclusions

Self-reported allergy correlated well with the antibody measurements. The prevalence of allergy was highest in the young and those working inside. Heritability of atopy and sensitization was high. The prevalence of CD-related autoantibodies was high and did not coincide with the self-reported allergy.

Duodenal microbiota composition and mucosal homeostasis in pediatric celiac disease

BACKGROUND

Celiac disease (CD) is an autoimmune disorder of the small intestine which is triggered by dietary gluten in genetically predisposed (HLA-DQ2/DQ8 positive) individuals. Only a fraction of HLA-DQ2/DQ8 positive individuals develop CD indicating that other factors have a role in the disorder. Several studies have addressed intestinal microbiota aberrancies in pediatric CD, but the results are inconsistent. Previously, we demonstrated that pediatric CD patients have lower duodenal expression of TLR2 and higher expression of TLR9 as compared to healthy controls (HC) indicating that microbiota may have a role in CD.

METHODS

We used bacterial phylogenetic microarray to comprehensively profile the microbiota in duodenal biopsies of CD (n = 10) and HC (n = 9) children. The expression of selected mucosa-associated genes was assessed by qRT-PCR in CD and HC children and in treated CD adults (T-CD, n = 6) on gluten free diet.

RESULTS

The overall composition, diversity and the estimated microbe associated molecular pattern (MAMP) content of microbiota were comparable between CD and HC, but a sub-population profile comprising eight genus-like bacterial groups was found to differ significantly between HC and CD. In HC, increased TLR2 expression was positively correlated with the expression of tight junction protein ZO-1. In CD and T-CD, the expression of IL-10, IFN-g and CXCR6 were higher as compared to HC.

CONCLUSIONS

The results suggest that microbiota and altered expression of mucosal receptors have a role in CD. In CD subjects, the increased expression of IL-10 and IFN-g may have partly resulted from the increased TLR9 expression and signaling.

Mucosal cytokine response after short-term gluten challenge in celiac disease and non-celiac gluten sensitivity

OBJECTIVES

In celiac disease (CD), gluten induces both adaptive and innate immune responses. Non-celiac gluten sensitivity (NCGS) is another form of gluten intolerance where the immune response is less characterized. The aim of our study was to explore and compare the early mucosal immunological events in CD and NCGS.

METHODS

We challenged 30 HLA-DQ2(+) NCGS and 15 CD patients, all on a gluten-free diet, with four slices of gluten-containing bread daily for 3 days. Duodenal biopsy specimens were collected before and after challenge. The specimens were examined for cytokine mRNA by quantitative reverse transcriptase-PCR and for MxA-expression and CD3(+) intraepithelial lymphocytes (IELs) by immunohistochemistry and compared with specimens from untreated CD patients and disease controls.

RESULTS

In CD patients, tumor necrosis factor alpha (P=0.02) and interleukin 8 (P=0.002) mRNA increased after in vivo gluten challenge. The interferon gamma (IFN-γ) level of treated CD patients was high both before and after challenge and did not increase significantly (P=0.06). Four IFN-γ-related genes increased significantly. Treated and untreated CD patients had comparable levels of IFN-γ. Increased expression of MxA in treated CD patients after challenge suggested that IFN-α was activated on gluten challenge. In NCGS patients only IFN-γ increased significantly (P=0.03). mRNA for heat shock protein (Hsp) 27 or Hsp70 did not change in any of the groups. Importantly, we found that the density of IELs was higher in NCGS patients compared with disease controls, independent of challenge, although lower than the level for treated CD patients.

CONCLUSIONS

CD patients mounted a concomitant innate and adaptive immune response to gluten challenge. NCGS patients had increased density of intraepithelial CD3(+) T cells before challenge compared with disease controls and increased IFN-γ mRNA after challenge. Our results warrant further search for the pathogenic mechanisms for NCGS.

IL-15 positively regulates IL-21 production in celiac disease mucosa

Celiac disease (CD)-associated inflammation is characterized by high interleukin- 21 (IL-21), but the mechanisms that control IL-21 production are not fully understood. Here we analyzed IL-21 cell sources and examined how IL-21 production is regulated in CD. Intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs), isolated from CD patients and non-CD controls, were analyzed for cell markers, cytokines, and transcription factors by flow cytometry. IL-21 was highly produced by CD4+ and CD4+/CD8+ IELs and LPLs in active CD. IL-21-producing cells coexpressed interferon-γ (IFN-γ) and to a lesser extent T helper type 17 (Th17) cytokines. Treatment of control LPLs with IL-15, a cytokine overproduced in CD, activated Akt and STAT3 (signal transducer and activator of transcription 3), thus enhancing IL-21 synthesis. Active CD biopsies contained elevated levels of Akt, and blockade of IL-15 in those samples reduced IL-21. Similarly, neutralization of IL-15 in biopsies of inactive CD patients inhibited peptic-tryptic digest of gliadin-induced IL-21 expression. These findings indicate that in CD, IL-15 positively regulates IL-21 production.

Immunogenicity of monococcum wheat in celiac patients

BACKGROUND

Research is intense to find wheat of low or null toxicity for patients with celiac disease (CD). Among candidates, there are diploid wheat species.

OBJECTIVE

We compared the immunological properties of 2 lines of diploid monococcum wheat (Triticum monococcum ssp. monococcum), Monlis and ID331, with those of common wheat (Triticum aestivum).

DESIGN

Interferon-γ production and the proliferation of intestinal gliadin-specific T cell lines and clones were measured as evidence of T cell activation by peptic and tryptic (PT) digests of gliadins from 2 monococcum lines. Furthermore, organ cultures of jejunal biopsies from 28 CD patients were set up to assess the effects of PT gliadin on innate and adaptive immune response by using immunohistochemistry.

RESULTS

Monlis and ID331 induced interferon-γ production and proliferation in celiac mucosal T cells. In organ cultures, Monlis PT digest induced a significant increase of IL-15 epithelial expression and crypt enterocyte proliferation, whereas ID331 had no effect. Both monococcum lines caused intraepithelial T cell infiltration and lamina propria T cell activation.

CONCLUSIONS

Our data show that the monococcum lines Monlis and ID331 activate the CD T cell response and suggest that these lines are toxic for celiac patients. However, ID331 is likely to be less effective in inducing CD because of its inability to activate the innate immune pathways.

Serum parameters in the spectrum of coeliac disease: beyond standard antibody testing--a cohort study

BACKGROUND

Invasive techniques are still required to distinguish between uncomplicated and complicated forms of CD.

METHODS

We set out to investigate the potential use of novel serum parameters, including IL-6, IL-8, IL-17, IL-22, sCD25, sCD27, granzyme-B, sMICA and sCTLA-4 in patients diagnosed with active CD, CD on a GFD, Refractory coeliac disease (RCD) type I and II, and enteropathy associated T-cell lymphoma (EATL).

RESULTS

In both active CD and RCDI-II elevated levels of the proinflammatory IL-8, IL-17 and sCD25 were observed. In addition, RCDII patients displayed higher serum levels of soluble granzyme-B and IL-6 in comparison to active CD patients. In contrast, no differences between RCDI and active CD or RCDII were observed. Furthermore, EATL patients displayed higher levels of IL-6 as compared to all other groups.

CONCLUSIONS

A series of novel serum parameters reveal distinctive immunological characteristics of RCDII and EATL in comparison to uncomplicated CD and RCDI.

Novel therapeutic/integrative approaches for celiac disease and dermatitis herpetiformis

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of gluten in genetically susceptible individuals. Gluten is a protein component in wheat and other cereals like rye and barley. At present, the only available treatment is a strict gluten-free diet. Recent advances have increased our understanding of the molecular basis for this disorder. Last decade has seen new scientific developments in this disease and led to the formulation of new concepts of pathophysiology that offer possible targets for new treatments or interventions integrative to the gluten-free diet.

Pathophysiology of celiac disease

Celiac disease results from the interplay of genetic, environmental, and immunologic factors. An understanding of the pathophysiology of celiac disease, in which the trigger (wheat, rye, and barley) is known, will undoubtedly reveal basic mechanisms that underlie other autoimmune diseases (eg, type 1 diabetes) that share many common pathogenic perturbations. This review describes seminal findings in each of the 3 domains of the pathogenesis of celiac disease, namely genetics, environmental triggers, and immune dysregulation, with a focus on newer areas of investigation such as non-HLA genetic variants, the intestinal microbiome, and the role of the innate immune system.

Reintroduction of gluten following flour transamidation in adult celiac patients: a randomized, controlled clinical study

A lifelong gluten-free diet (GFD) is mandatory for celiac disease (CD) but has poor compliance, justifying novel strategies. We found that wheat flour transamidation inhibited IFN-γ secretion by intestinal T cells from CD patients. Herein, the primary endpoint was to evaluate the ability of transamidated gluten to maintain GFD CD patients in clinical remission. Secondary endpoints were efficacy in prevention of the inflammatory response and safety at the kidney level, where reaction products are metabolized. In a randomized single blinded, controlled 90-day trial, 47 GFD CD patients received 3.7 g/day of gluten from nontransamidated (12) or transamidated (35) flour. On day 15, 75% and 37% of patients in the control and experimental groups, respectively, showed clinical relapse (P = 0.04) whereas intestinal permeability was mainly altered in the control group (50% versus 20%, P = 0.06). On day 90, 0 controls and 14 patients in the experimental group completed the challenge with no variation of antitransglutaminase IgA (P = 0.63), Marsh-Oberhuber grading (P = 0.08), or intestinal IFN-γ mRNA (P > 0.05). Creatinine clearance did not vary after 90 days of treatment (P = 0.46). In conclusion, transamidated gluten reduced the number of clinical relapses in challenged patients with no changes of baseline values for serological/mucosal CD markers and an unaltered kidney function.

Genetic variations in interleukin-12 related genes in immune-mediated diseases

The interleukin-12 (IL-12) family comprises a group of heterodimeric cytokines and their respective receptors that play key roles in immune responses. A growing number of autoimmune diseases has been found to be associated with genetic variation in these genes. Based on their respective associations with the IL-12 genes, autoimmune diseases appear to cluster in two groups that either show strong associations with the Th1/Th17 pathway (as indicated by genetic association with IL12B and IL23R) or the Th1/IL-35 pathway as the consequence of their association with polymorphisms in the IL12A gene region. The genetic associations are described in relation to what is known of the functionality of these genes in the various diseases. Comparing association data for gene families in different diseases may lead to better insight in the function of the genes in the onset and course of the disease.

The immunopathogenesis of celiac disease reveals possible therapies beyond the gluten-free diet

Celiac disease is a T cell-mediated autoimmune inflammatory disease of the small intestine that is activated by gluten. The diagnosis of celiac disease is challenging as patients display a wide range of symptoms and some are asymptomatic. A lifelong gluten-free diet is the only currently approved treatment of celiac disease. Although the diet is safe and effective, the compliance rates and patient acceptance vary. Furthermore, many patients treated with a gluten-free diet continue to be mildly to severely symptomatic with persistent histological abnormalities, and a small number of patients develop refractory celiac disease. New therapeutic adjuncts and potential alternatives to the gluten-free diet could improve the treatment options for these patients. Advances in understanding the immunopathogenesis of celiac disease have suggested several types of therapeutic strategies that may augment or supplant the gluten-free diet. Some of these strategies attempt to decrease the immunogenicity of gluten-containing grains by manipulating the grain itself or by using oral enzymes to break down immunogenic peptides that normally remain intact during digestion. Other strategies focus on preventing the absorption of these peptides, preventing tissue transglutaminase from rendering gluten peptides more immunogenic, or inhibiting their binding to celiac disease-specific antigen-presenting molecules. Strategies that limit T cell migration to the small intestine or that reestablish mucosal homeostasis and tolerance to gluten antigens are also being explored. Additionally, it is vital to develop new therapeutic options for refractory celiac disease patients. This review highlights therapeutic strategies that may ultimately improve the health and well-being of individuals with celiac disease.

Enzyme linked immuno-spot; a useful tool in the search for elusive immune markers in common pediatric immunological diseases

In order to provide better therapy we strive to increase our knowledge of how the immune system behaves and communicates in common pediatric immunological diseases, such as type 1 diabetes, allergic and celiac diseases. However, when dealing with pediatric diseases, where study subjects are almost exclusively children, blood volumes available for immunological studies are limited and as such must be carefully handled and used to their full extent. Single immune markers can easily be detected by a traditional Enzyme Linked Immunosorbent Assay (ELISA), whereas multiple markers can be detected by a fluorochrome (Luminex) or electrochemiluminescence (MSD) technique. These techniques however are sometimes not sensitive enough to detect low levels of secreted immune markers in limited sample sizes. To detect immune markers at the single-cell level, an Enzyme Linked Immuno-spot (ELISPOT) can be used to pin-point elusive immune markers in common pediatric immunological diseases.

Interferon-γ activates transglutaminase 2 via a phosphatidylinositol-3-kinase-dependent pathway: implications for celiac sprue therapy

The mechanism for activation of extracellular transglutaminase 2 (TG2) in the small intestine remains a fundamental mystery in our understanding of celiac sprue pathogenesis. Using the T84 human enterocytic cell line, we show that interferon-γ (IFN-γ), the predominant cytokine secreted by gluten-reactive T cells in the celiac intestine, activates extracellular TG2 in a dose-dependent manner. IFN-γ mediated activation of TG2 requires phosphatidylinositol-3-kinase (PI3K) activity, but is uninfluenced by a number of other kinases reported to be active in T84 cells. Pharmacological inhibition of PI3K in the presence of IFN-γ prevents TG2 activation as well as the previously characterized increase in transepithelial permeability. Our findings therefore establish PI3K as an attractive target for celiac sprue therapy, a possibility that is underscored by the encouraging safety profiles of several PI3K inhibitors undergoing human clinical trials.

Proof of concept of microbiome-metabolome analysis and delayed gluten exposure on celiac disease autoimmunity in genetically at-risk infants

Celiac disease (CD) is a unique autoimmune disorder in which the genetic factors (DQ2/DQ8) and the environmental trigger (gluten) are known and necessary but not sufficient for its development. Other environmental components contributing to CD are poorly understood. Studies suggest that aspects of gluten intake might influence the risk of CD occurrence and timing of its onset, i.e., the amount and quality of ingested gluten, together with the pattern of infant feeding and the age at which gluten is introduced in the diet. In this study, we hypothesize that the intestinal microbiota as a whole rather than specific infections dictates the switch from tolerance to immune response in genetically susceptible individuals. Using a sample of infants genetically at risk of CD, we characterized the longitudinal changes in the microbial communities that colonize infants from birth to 24 months and the impact of two patterns of gluten introduction (early vs. late) on the gut microbiota and metabolome, and the switch from gluten tolerance to immune response, including onset of CD autoimmunity. We show that infants genetically susceptible to CD who are exposed to gluten early mount an immune response against gluten and develop CD autoimmunity more frequently than at-risk infants in which gluten exposure is delayed until 12 months of age. The data, while derived from a relatively small number of subjects, suggest differences between the developing microbiota of infants with genetic predisposition for CD and the microbiota from infants with a non-selected genetic background, with an overall lack of bacteria of the phylum Bacteriodetes along with a high abundance of Firmicutes and microbiota that do not resemble that of adults even at 2 years of age. Furthermore, metabolomics analysis reveals potential biomarkers for the prediction of CD. This study constitutes a definite proof-of-principle that these combined genomic and metabolomic approaches will be key to deciphering the role of the gut microbiota on CD onset.

Up-regulation of small intestinal interleukin-17 immunity in untreated coeliac disease but not in potential coeliac disease or in type 1 diabetes

Up-regulation of interleukin (IL)-17 in small intestinal mucosa has been reported in coeliac disease (CD) and in peripheral blood in type 1 diabetes (T1D). We explored mucosal IL-17 immunity in different stages of CD, including transglutaminase antibody (TGA)-positive children with potential CD, children with untreated and gluten-free diet-treated CD and in children with T1D. Immunohistochemistry was used for identification of IL-17 and forkhead box protein 3 (FoxP3)-positive cells and quantitative polymerase chain reaction (qPCR) for IL-17, FoxP3, retinoic acid-related orphan receptor (ROR)c and interferon (IFN)-γ transcripts. IL-1β, IL-6 and IL-17 were studied in supernatants from biopsy cultures. Expression of the apoptotic markers BAX and bcl-2 was evaluated in IL-17-stimulated CaCo-2 cells. The mucosal expression of IL-17 and FoxP3 transcripts were elevated in individuals with untreated CD when compared with the TGA-negative reference children, children with potential CD or gluten-free diet-treated children with CD (P < 0·005 for all IL-17 comparisons and P < 0·01 for all FoxP3 comparisons). The numbers of IL-17-positive cells were higher in lamina propria in children with CD than in children with T1D (P < 0·05). In biopsy specimens from patients with untreated CD, enhanced spontaneous secretion of IL-1β, IL-6 and IL-17 was seen. Activation of anti-apoptotic bcl-2 in IL-17-treated CaCo-2 epithelial cells suggests that IL-17 might be involved in mucosal protection. Up-regulation of IL-17 could, however, serve as a biomarker for the development of villous atrophy and active CD.

The sourdough fermentation may enhance the recovery from intestinal inflammation of coeliac patients at the early stage of the gluten-free diet

PURPOSE

This study aimed at investigating the effect of corn, rice and amaranth gluten-free (GF) sourdoughs on the release of nitric oxide (NO) and synthesis of pro-inflammatory cytokines by duodenal mucosa biopsies of eight coeliac disease (CD) patients.

METHODS

Selected lactic acid bacteria were used as starters for the manufacture of corn, rice or amaranth sourdoughs. Chemically acidified doughs, without bacterial starters, and doughs started with baker's yeast alone were also manufactured from the same GF matrices. Pepsin-trypsin (PT) digests were produced from all sourdoughs and doughs, and used to assay the rate of recovery of biopsy specimens from eight CD patients at diagnosis. The release of NO and the synthesis of pro-inflammatory cytokines interferon-γ (IFN-γ) were assayed.

RESULTS

During fermentation, lactic acid bacteria acidified and grew well (ca. log 9.0 CFU/g) on all GF matrices, showing intense proteolysis. Duodenal biopsy specimens still released NO and IFN-γ when subjected to treatments with basal medium (control), PT-digest from chemically acidified doughs and PT-digest from doughs fermented with baker's yeast alone. On the contrary, the treatment of all the biopsy specimens with PT-digests from all GF matrices subjected to sourdough fermentation significantly decreased the release of NO and the synthesis of IFN-γ.

CONCLUSIONS

During manufacture of GF baked goods, the use of sourdough fermentation could be considered as an adjuvant to enhance the recovery from intestinal inflammation of coeliac patients at the early stage of the gluten-free diet.

Oral enzyme therapy for celiac sprue

Celiac sprue is an inflammatory disease of the small intestine caused by dietary gluten and treated by adherence to a life-long gluten-free diet. The recent identification of immunodominant gluten peptides, the discovery of their cogent properties, and the elucidation of the mechanisms by which they engender immunopathology in genetically susceptible individuals have advanced our understanding of the molecular pathogenesis of this complex disease, enabling the rational design of new therapeutic strategies. The most clinically advanced of these is oral enzyme therapy, in which enzymes capable of proteolyzing gluten (i.e., glutenases) are delivered to the alimentary tract of a celiac sprue patient to detoxify ingested gluten in situ. In this chapter, we discuss the key challenges for discovery and preclinical development of oral enzyme therapies for celiac sprue. Methods for lead identification, assay development, gram-scale production and formulation, and lead optimization for next-generation proteases are described and critically assessed.

New clues in celiac disease epidemiology, pathogenesis, clinical manifestations, and treatment

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of gluten in genetically susceptible individuals. It is one of the most common lifelong disorders on a worldwide basis. Celiac enteropathy is the final consequence of an abnormal immune reaction, showing features of both an innate and an adaptive response to gluten prolamins. The clinical spectrum is wide, including cases with either typical intestinal or atypical extraintestinal features, and silent forms. The only available treatment consists in dietary exclusion of grains containing gluten. New pharmacological treatment are currently under scrutiny.

Psoriasis in a nationwide cohort study of patients with celiac disease

Earlier studies on the association between celiac disease (CD) and psoriasis show contradictory results. The purpose of this study was to assess the risk of psoriasis in patients with biopsy-verified CD. Through 28 pathology departments in Sweden, we identified individuals with CD diagnosed between 1969 and 2008 (Marsh 3: villous atrophy; n = 28,958 unique individuals). We then used Cox regression to compare individuals with CD with 143,910 sex- and age-matched controls regarding their risk of psoriasis. CD was a risk factor for future psoriasis (hazard ratio (HR) = 1.72; 95% confidence interval (CI) = 1.54-1.92; during follow-up, 401 individuals with CD and 1,139 controls had a diagnosis of psoriasis). The absolute risk of future psoriasis in patients with CD was 135/100,000 person-years (excess risk = 57/100,000). In all, 42% of all psoriasis in patients with CD could be attributed to the underlying CD. Moreover, in children we saw a positive association between CD and psoriasis (HR = 2.05; 95% CI = 1.62-2.60). The association between CD and psoriasis seems to be independent of a temporal relationship, as we also found a positive association between CD and psoriasis before CD diagnosis (odds ratio = 1.91; 95% CI = 1.58-2.31). In conclusion, individuals with CD were at increased risk of psoriasis both before and after CD diagnosis.

Gliadin fragments promote migration of dendritic cells

In genetically predisposed individuals, ingestion of wheat gliadin provokes a T-cell-mediated enteropathy, celiac disease. Gliadin fragments were previously reported to induce phenotypic maturation and Th1 cytokine production by human dendritic cells (DCs) and to boost their capacity to stimulate allogeneic T cells. Here, we monitor the effects of gliadin on migratory capacities of DCs. Using transwell assays, we show that gliadin peptic digest stimulates migration of human DCs and their chemotactic responsiveness to the lymph node-homing chemokines CCL19 and CCL21. The gliadin-induced migration is accompanied by extensive alterations of the cytoskeletal organization, with dissolution of adhesion structures, podosomes, as well as up-regulation of the CC chemokine receptor (CCR) 7 on cell surface and induction of cyclooxygenase (COX)-2 enzyme that mediates prostaglandin E2 (PGE₂) production. Blocking experiments confirmed that gliadin-induced migration is independent of the TLR4 signalling. Moreover, we showed that the α-gliadin-derived 31–43 peptide is an active migration-inducing component of the digest. The migration promoted by gliadin fragments or the 31–43 peptide required activation of p38 mitogen-activated protein kinase (MAPK). As revealed using p38 MAPK inhibitor SB203580, this was responsible for DC cytoskeletal transition, CCR7 up-regulation and PGE₂ production in particular. Taken together, this study provides a new insight into pathogenic features of gliadin fragments by demonstrating their ability to promote DC migration, which is a prerequisite for efficient priming of naive T cells, contributing to celiac disease pathology.

Immunological evaluation of the alcohol-soluble protein fraction from gluten-free grains in relation to celiac disease

Celiac disease (CD) is a gluten-sensitive enteropathy with an immune basis. We established the immune reactivity of the alcohol-soluble fraction from two minor cereals (tef and millet) and two pseudocereals (amaranth and quinoa) which are believed to be nontoxic based on taxonomy. Grains were examined in intestinal T-cell lines (iTCLs), cultures of duodenal explants from HLA-DQ2(+) CD patients and HLA-DQ8 transgenic mice for signs of activation. Our data indicated that tef, millet, amaranth, and quinoa did not show any immune cross-reactivity toward wheat gliadin, and therefore confirming their safety in the diet of CD patients.

Influence of Bifidobacterium longum CECT 7347 and gliadin peptides on intestinal epithelial cell proteome

Celiac disease is an enteropathy caused by an abnormal immune response to cereal gluten proteins (gliadin). To unravel the possible role of the interactions between gliadin peptides and specific intestinal bacteria, the response of intestinal epithelial (Caco-2) cells to gliadin subjected to gastrointestinal digestion in the presence or absence of Bifidobacterium longum CECT 7347 has been studied. Changes in the proteome of Caco-2 cells were determined by 2DE and MALDI-TOF. Gliadins digested without B. longum altered the expression of a higher number of proteins than in the presence of the bacterium (21 versus 9), and these proteins were involved in disorganization of cell cytoskeleton, inflammation, and apoptosis. Gliadins digested in the presence of the bacterium influenced the production of proteins involved in calcium homeostasis and cell survival and function. Therefore, B. longum CECT 7347 might ameliorate gliadin toxicity and modify the responses of intestinal epithelial cells to the gliadin challenge.

IL-15 interferes with suppressive activity of intestinal regulatory T cells expanded in Celiac disease

OBJECTIVES

Celiac disease (CD) is a condition in which the regulation of the mucosal immune response to dietary gliadin might be altered. The transcription factor forkhead box P3 (Foxp3) has been identified as a marker of a subset of regulatory T cells (Treg). In this study, we have investigated the presence and the suppressive function of Treg cells in the celiac small intestinal mucosa, their correlation with the disease state, and the inducibility by gliadin in an organ culture system; moreover, we tried to define whether interleukin 15 (IL-15), overexpressed in CD, could influence the regulatory activity of such cells.

METHODS

The expression of Foxp3, CD3, CD4, and CD8 were analyzed by immunohistochemistry and flow cytometry in duodenal biopsies taken from patients with untreated CD, treated CD, and from non-CD controls, as well as in vitro cultured biopsy samples from treated CD patients, upon challenge with gliadin. Furthermore, we analyzed the suppressive function of CD4+CD25+ T cells, isolated from untreated CD biopsy samples, on autologous responder CD4+CD25- T cells, in the presence of a polyclonal stimulus, with or without IL-15.

RESULTS

Higher density of CD4+CD25+Foxp3+ T cells was seen in duodenal biopsy samples from active CD patients in comparison with treated CD and non-CD controls. In coculture, CD4+CD25+ T cells were functionally suppressive, but their activity was impaired by IL-15. Cells from CD subjects showed increased sensitivity to the IL-15 action, likely due to enhanced expression of IL-15 receptor. Finally, we demonstrated an expansion of Foxp3 in treated CD mucosa following in vitro challenge with gliadin.

CONCLUSIONS

These data suggest that CD4+CD25+Foxp3+ T cells are induced in situ by gliadin. However, their suppressor capacity might be impaired in vivo by IL-15; this phenomenon contributes to maintain and expand the local inflammatory response in CD.

Integration of genetic and immunological insights into a model of celiac disease pathogenesis

Celiac disease (CD) is a gluten-sensitive enteropathy that develops in genetically susceptible individuals by exposure to cereal gluten proteins. This review integrates insights from immunological studies with results of recent genetic genome-wide association studies into a disease model. Genetic data, among others, suggest that viral infections are implicated and that natural killer effector pathways are important in the pathogenesis of CD, but most prominently these data converge with existing immunological findings that CD is primarily a T cell-mediated immune disorder in which CD4(+) T cells that recognize gluten peptides in the context of major histocompatibility class II molecules play a central role. Comparison of genetic pathways as well as genetic susceptibility loci between CD and other autoimmune and inflammatory disorders reveals that CD bears stronger resemblance to T cell-mediated organ-specific autoimmune than to inflammatory diseases. Finally, we present evidence suggesting that the high prevalence of CD in modern societies may be the by-product of past selection for increased immune responses to combat infections in populations in which agriculture and cereals were introduced early on in the post-Neolithic period.

Coeliac disease and gluten sensitivity

Coeliac disease (CD) is a systemic immune-mediated disorder elicited by gluten in genetically susceptible individuals. The common factor for all patients with CD is the presence of a variable combination of gluten-dependent clinical manifestations, specific autoantibodies (anti-tissue transglutaminase/anti-endomysium), HLA-DQ2 and/or DQ8 haplotypes and different degrees of enteropathy. Recently, gluten sensitivity has received much interest, although the limits and possible overlap between gluten sensitivity and CD remain poorly defined. At present, a number of morphological, functional and immunological disorders that are lacking one or more of the key CD criteria (enteropathy, associated HLA haplotypes and presence of anti-transglutaminase two antibodies) but respond to gluten exclusion are included under the umbrella of gluten sensitivity. The possible immunological mechanisms underlying these conditions are discussed. Emphasis is given to specific autoantibodies as markers of the coeliac spectrum and to the hypothesis that innate epithelial stress can exist independently from adaptive intestinal immunity in gluten sensitivity.

Involvement of CD40-CD40 ligand in uncomplicated and refractory celiac disease

OBJECTIVES

Cognate interaction between CD40 on antigen-presenting cells and CD40 ligand (CD40L) on T cells is a crucial costimulatory signal in T-cell activation. In this study, we investigated CD40-CD40L expression in the duodenum of uncomplicated and refractory celiac disease patients, and explored the ex vivo effects of CD40L blockade on cytokine production and the T-helper cell type 1-specific transcription factor T-bet.

METHODS

CD40L and colocalization of CD40 with the dendritic cell markers CD11c and CD123 were investigated by confocal microscopy on tissue sections of duodenal biopsy samples obtained from 14 uncomplicated celiac patients before and after 12 months of gluten-free diet, 5 refractory celiac patients, and 12 controls. CD40 was also analyzed by flow cytometry on single cell suspension of mucosal biopsies. Treated celiac biopsies were stimulated with peptic-tryptic digest of gliadin (PT-gliadin) with or without an anti-CD40L-neutralizing antibody. Interferon (IFN)-γ and interleukin (IL)-17 were measured by ELISA (enzyme-linked immunosorbent assay). T-bet, CD40, and CD40L were determined by immunoblotting.

RESULTS

CD40 and CD40L expression was higher in uncomplicated untreated and refractory celiac patients than in controls; the expression returned to normal after gluten-free diet in uncomplicated patients. Flow cytometric analysis confirmed that most CD40(+) cells were dendritic cells. The addition of the anti-CD40L antibody to treated celiac biopsies significantly inhibited the PT-gliadin-induced production of IFN-γ and IL-17, and mucosal T-bet.

CONCLUSIONS

Our results indicate that the CD40-CD40L pathway has a key role in celiac disease. Disruption of CD40-CD40L interaction may offer a therapeutic alternative in refractory celiac disease.

Characterization of gliadin-specific Th17 cells from the mucosa of celiac disease patients

OBJECTIVES

Celiac disease (CD) is a disorder characterized by a deregulated immune response to ingested wheat gluten and related cereal proteins in susceptible individuals. It has been considered that the onset of CD is mediated by a skewed Th1 response. However, the participation of Th17 cells in the pathogenesis of the disease, a key cell population in other autoimmune disorders, has not been studied in detail. We have investigated the presence of Th17 cells in the mucosa of active CD patients and their functional implications in the pathogenesis of the disease.

METHODS

T cells obtained from duodenum biopsies from 15 untreated patients and 11 control individuals were characterized by flow cytometry, immunoassays, and real-time PCR.

RESULTS

We found gliadin-specific CD4(+) interleukin (IL)-17A-producing T cells in the mucosa of CD patients with a phenotype consisting of TCR (T-cell receptor)αβ(+) CD45RO(+) CD161(+) CCR6(+) (C-C chemokine receptor type 6) and IL-23R(+). Functional analysis showed that Th17 cells from CD patients are different from those of control individuals in terms of cytokines production. Th17 cells from CD patients, but not from controls, simultaneously express transforming growth factor-β (TGFβ). Th17 CD cells also produce interferon-γ (IFNγ), IL-21, and IL-22. The analysis of the transcription factors revealed a high expression of interferon regulatory factor-4 as a feature of gliadin-specific cells from CD patients with respect to controls.

CONCLUSIONS

Gliadin-specific Th17 cells are present in the mucosa of CD patients having a dual role in the pathogenesis of the disease as they produce proinflammatory cytokines (such as IL-17, IFNγ, IL-21), mucosa-protective IL-22, and regulatory TGFβ, which actively modulates IL-17A production by T cells in the celiac mucosa.

Identification of gliadin-binding peptides by phage display

Background

Coeliac disease (CD) is a common and complex disorder of the small intestine caused by intolerance to wheat gluten and related edible cereals like barley and rye. Peptides originating from incomplete gliadin digestion activate the lamina propria infiltrating T cells to release proinflammatory cytokines, which in turn cause profound tissue remodelling of the small intestinal wall. There is no cure for CD except refraining from consuming gluten-containing products.

Results

Phage from a random oligomer display library were enriched by repeated pannings against immobilised gliadin proteins. Phage from the final panning round were plated, individual plaques picked, incubated with host bacteria, amplified to a population size of 10¹¹ to 10¹² and purified. DNA was isolated from 1000 purified phage populations and the region covering the 36 bp oligonucleotide insert from which the displayed peptides were translated, was sequenced. Altogether more than 150 different peptide-encoding sequences were identified, many of which were repeatedly isolated under various experimental conditions. Amplified phage populations, each expressing a single peptide, were tested first in pools and then one by one for their ability to inhibit binding of human anti-gliadin antibodies in ELISA assays. These experiments showed that several of the different peptide-expressing phage tested inhibited the interaction between gliadin and anti-gliadin antibodies. Finally, four different peptide-encoding sequences were selected for further analysis, and the corresponding 12-mer peptides were synthesised in vitro. By ELISA assays it was demonstrated that several of the peptides inhibited the interaction between gliadin molecules and serum anti-gliadin antibodies. Moreover, ELISA competition experiments as well as dot-blot and western blot revealed that the different peptides interacted with different molecular sites of gliadin.

Conclusions

We believe that several of the isolated and characterised gliadin-binding peptides described here could provide valuable tools for researchers in the field of CD by facilitating studies on localisation and uptake of various gliadin peptides in the small intestine. In future work, the potential of these peptides to detoxify gluten will be investigated.

Gluten-dependent enteropathy and atypical human leukocyte antigen alleles

The risk for developing celiac disease is associated with the major histocompatibility complex class II human leukocyte antigen DQ2 and DQ8. We retrospectively reviewed the medical records of 127 consecutive cases of adult-onset celiac disease evaluated at a single United States center to determine the distribution of the associated human leukocyte antigen DQA1 and DQB1 alleles. The median patient age of diagnosis was 41 (range, 16-81) years. Ninety-five adults underwent human leukocyte antigen DQ typing. Eighty patients were DQ2 positive, 24 were DQ8 positive, and 11 were DQ2 and DQ8 positive. Four patients carried the uncommon, low-risk haplotype DQ2.2 (DQA1*02 and DQB1*02) without DQA1*05. Two patients did not carry human leukocyte antigen DQ2 or DQ8. All of the patients with atypical human leukocyte antigen DQ responded to a gluten-free diet. Although the majority of patients carry the human leukocyte antigen DQ2 or DQ8, gluten-dependent enteropathy periodically presents in adults with low-risk alleles.

HLA-G 14 bp deletion/insertion polymorphism in celiac disease

OBJECTIVES

Nonclassical major histocompatibility class I HLA-G antigen is a tolerogenic molecule that inhibits lytic activity of natural killer (NK) cells and cytotoxic T lymphocytes. Because of its immunomodulatory and tolerogenic properties, HLA-G molecules may have a role in celiac disease (CD). We analyzed the HLA-G 14 bp deletion/insertion polymorphism, known to have a functional effect on mRNA stability, in a group of 522 CD patients, stratified for the presence of HLA-DQ2 genotype, and 400 healthy individuals to evaluate the possible effect of the polymorphism on the risk to develop the disease.

METHODS

HLA-G 14 bp deletion/insertion polymorphism (rs1704) was detected by polymerase chain reaction and double-checked by direct sequencing.

RESULTS

The 14 bp inserted (I) allele and the homozygous I/I genotype were significantly more frequent in CD patients than in healthy controls. The presence of I allele was associated with an increased risk of CD (OR 1.35) and the effect of I allele was consistent with a recessive genetic model (P<0.001).

CONCLUSIONS

Our results also indicate that the effect of the HLA-G D/I polymorphism is restricted for HLA-DQ2, and not simply due to the presence of linkage disequilibrium with the major known risk factor; moreover we found that the presence of the I allele confers an increased risk of CD in addition to the risk conferred by HLA-DQ2 alone and that subjects that carry both DQ2 and HLA-G I alleles have an increased risk of CD than subjects that carry DQ2 but not the I allele.