Reactivity to dietary gluten: new insights into differential diagnosis among gluten‑related gastrointestinal disorders

The ingestion of dietary gluten sometimes may trigger allergic, autoimmune or nonallergic and nonautoimmune response. The typical gluten‑related allergic disorder is the wheat allergy (WA). Celiac disease (CD) is a well‑known gluten‑related autoimmune condition. The clinical expression of a gluten‑related nonallergic and nonautoimmune response is nonceliac gluten sensitivity (NCGS), an emerging condition whose framework is yet unclear and whose diagnosis is suggested only by demonstration of gluten‑dependency in patient' symptoms after exclusion of WA and CD. This review discusses the current tools to identify patients suffering from WA, CD, and NCGS, as well as the most recent insights in the differential diagnosis among these gluten‑related gastrointestinal disorders .

Validation of morphometric analyses of small-intestinal biopsy readouts in celiac disease

Background

Assessment of the gluten-induced small-intestinal mucosal injury remains the cornerstone of celiac disease diagnosis. Usually the injury is evaluated using grouped classifications (e.g. Marsh groups), but this is often too imprecise and ignores minor but significant changes in the mucosa. Consequently, there is a need for validated continuous variables in everyday practice and in academic and pharmacological research.

Methods

We studied the performance of our standard operating procedure (SOP) on 93 selected biopsy specimens from adult celiac disease patients and non-celiac disease controls. The specimens, which comprised different grades of gluten-induced mucosal injury, were evaluated by morphometric measurements. Specimens with tangential cutting resulting from poorly oriented biopsies were included. Two accredited evaluators performed the measurements in blinded fashion. The intraobserver and interobserver variations for villus height and crypt depth ratio (VH:CrD) and densities of intraepithelial lymphocytes (IELs) were analyzed by the Bland-Altman method and intraclass correlation.

Results

Unevaluable biopsies according to our SOP were correctly identified. The intraobserver analysis of VH:CrD showed a mean difference of 0.087 with limits of agreement from −0.398 to 0.224; the standard deviation (SD) was 0.159. The mean difference in interobserver analysis was 0.070, limits of agreement −0.516 to 0.375, and SD 0.227. The intraclass correlation coefficient in intraobserver variation was 0.983 and that in interobserver variation 0.978. CD3⁺ IEL density countings in the paraffin-embedded and frozen biopsies showed SDs of 17.1% and 16.5%; the intraclass correlation coefficients were 0.961 and 0.956, respectively.

Conclusions

Using our SOP, quantitative, reliable and reproducible morphometric results can be obtained on duodenal biopsy specimens with different grades of gluten-induced injury. Clinically significant changes were defined according to the error margins (2SD) of the analyses in VH:CrD as 0.4 and in CD3⁺-stained IELs as 30%.

Possible ameliorative effect of breastfeeding and the uptake of human colostrum against coeliac disease in autistic rats

AIM: To examine the possible ameliorative effect of breastfeeding and the uptake of human colostrum against coeliac disease in autistic rats.

METHODS: Female rats were fed a standard diet and received a single intraperitoneal injection of 600 mg/kg sodium valproate on day 12.5 after conception. In study 1, neonatal rats were randomly subjected to blood tests to investigate autism. In study 2, the 1^st group was fed by the mother after an injection of interferon-γ (IFN-γ) and administration of gliadin. The pups in the 2^nd group were prevented from accessing maternal milk, injected IFN-γ, administered gliadin, and hand-fed human colostrum. The normal littermates fed by the table mothers were injected with physiological saline and served as normal controls in this study.

RESULTS: The protein concentration was higher in group 2 than in group 1 in the duodenum (161.6 ± 9 and 135.4 ± 7 mg/g of tissue, respectively, P < 0.01). A significant increase (P < 0.001) in body weight was detected in human colostrum-treated pups on post natal day (PND) 7 and 21 vs suckling pups in group 1. A delay in eye opening was noticed in the treated rats in group 1 on PND 13 compared with the control group and group 2. Administration of a single intraperitoneal injection of 600 mg/kg sodium valproate on day 12.5 after conception resulted in significantly reduced calcium and vitamin D levels in study 1 compared with the control groups (P < 0.001). However, human colostrum uptake inhibited increases in the level of transglutaminase antibody in autistic pups with coeliac disease.

CONCLUSION: The effects of early-life nutrition and human colostrum on the functional maturation of the duodenal villi in autistic rats with coeliac disease that might limit or prevent the coeliac risk with autism.

Association between ipilimumab and celiac disease

A 62-year-old man with chemotherapy-naive, castration-resistant metastatic prostate cancer presented with refractory diarrhea despite prolonged high-dose corticosteroid treatment after receiving 3 doses of ipilimumab as part of a phase 3 clinical trial. The investigative work-up and response to a gluten-free diet essentially confirm celiac disease. Although ipilimumab-induced enterocolitis is a well-reported complication, there have been no reported cases of celiac disease with ipilimumab therapy, to our knowledge. We suspect that ipilimumab may have amplified the symptomatic presentation of previously unrecognized celiac disease or perhaps even triggered the disease itself. With ipilimumab being used more commonly in the treatment of melanoma and prostate cancer, we believe that physicians should be aware of this potential adverse outcome when evaluating a patient who experiences persistent diarrhea during or after ipilimumab treatment.

Larazotide acetate regulates epithelial tight junctions in vitro and in vivo

Tight junctions (TJs) control paracellular permeability and apical-basolateral polarity of epithelial cells, and can be regulated by exogenous and endogenous stimuli. Dysregulated permeability is associated with pathological conditions, such as celiac disease and inflammatory bowel disease. Herein we studied the mechanism by which larazotide acetate, an 8-mer peptide and TJ regulator, inhibits the cellular changes elicited by gliadin fragments, AT-1002, and cytokines. Previously, we demonstrated that AT-1002, a 6-mer peptide derived from the Vibrio cholerae zonula occludens toxin ZOT, caused several biochemical changes in IEC6 and Caco-2 cells resulting in decreased transepithelial electrical resistance (TEER) and increased TJ permeability. In this study, larazotide acetate inhibited the redistribution and rearrangement of zonula occludens-1 (ZO-1) and actin caused by AT-1002 and gliadin fragments in Caco-2 and IEC6 cells. Functionally, larazotide acetate inhibited the AT-1002-induced TEER reduction and TJ opening in Caco-2 cells. Additionally, larazotide acetate inhibited the translocation of a gliadin 13-mer peptide, which has been implicated in celiac disease, across Caco-2 cell monolayers. Further, apically applied larazotide acetate inhibited the increase in TJ permeability elicited by basolaterally applied cytokines. Finally, when tested in vivo in gliadin-sensitized HLA-HCD4/DQ8 double transgenic mice, larazotide acetate inhibited gliadin-induced macrophage accumulation in the intestine and preserved normal TJ structure. Taken together, our data suggest that larazotide acetate inhibits changes elicited by AT-1002, gliadin, and cytokines in epithelial cells and preserves TJ structure and function in vitro and in vivo.

Validation of a new enzyme-linked immunosorbent assay to detect the triggering proteins and peptides for celiac disease: interlaboratory study

The performance of Gluten-Tec (EuroProxima, Arnhem, The Netherlands) was tested through an interlaboratory study in accordance with AOAC guidelines. Gluten-Tec is a competitive ELISA that detects an immunostimulatory epitope of a-gliadin in dietary food for celiacs. Fifteen laboratories, representing 14 different countries, announced their interest in taking part in this study. Of the 12 laboratories that sent the results within the established timeframe, two submitted inappropriate standard curves and were excluded from the statistical analysis. Four different food matrixes (rice-based baby food, maize bread, chocolate cake mix, and beer) were selected for preparing the test samples. Two gliadin extraction procedures were used: the conventional 60% ethanol, and a new method based on the reducing reagent dithiothreitol. The 38 samples (19 blind duplicates) tested in this study were prepared by diluting the different extracts in order to cover a wide range of gliadin levels. Both sample extraction and dilution were performed by EuroProxima; the present interlaboratory study was focused only on testing the ELISA part of the Gluten-Tec kit protocol. Repeatability values (within-laboratory variance), expressed as RSD(r) ranged from 6.2 to 25.7%, while reproducibility values (interlaboratory variance), expressed as RSD(R), ranged from 10.6 to 45.9%. Both statistical parameters were in the acceptable range of ELISAs under these conditions, and the method will be presented to the Codex Alimentarius as a preferred method for gluten analysis.

Bifidobacterium longum CECT 7347 modulates immune responses in a gliadin-induced enteropathy animal model

Coeliac disease (CD) is an autoimmune disorder triggered by gluten proteins (gliadin) that involves innate and adaptive immunity. In this study, we hypothesise that the administration of Bifidobacterium longum CECT 7347, previously selected for reducing gliadin immunotoxic effects in vitro, could exert protective effects in an animal model of gliadin-induced enteropathy. The effects of this bacterium were evaluated in newborn rats fed gliadin alone or sensitised with interferon (IFN)-γ and fed gliadin. Jejunal tissue sections were collected for histological, NFκB mRNA expression and cytokine production analyses. Leukocyte populations and T-cell subsets were analysed in peripheral blood samples. The possible translocation of the bacterium to different organs was determined by plate counting and the composition of the colonic microbiota was quantified by real-time PCR. Feeding gliadin alone reduced enterocyte height and peripheral CD4+ cells, but increased CD4+/Foxp3+ T and CD8+ cells, while the simultaneous administration of B. longum CECT 7347 exerted opposite effects. Animals sensitised with IFN-γ and fed gliadin showed high cellular infiltration, reduced villi width and enterocyte height. Sensitised animals also exhibited increased NFκB mRNA expression and TNF-α production in tissue sections. B. longum CECT 7347 administration increased NFκB expression and IL-10, but reduced TNF-α, production in the enteropathy model. In sensitised gliadin-fed animals, CD4+, CD4+/Foxp3+ and CD8+ T cells increased, whereas the administration of B. longum CECT 7347 reduced CD4+ and CD4+/Foxp3+ cell populations and increased CD8+ T cell populations. The bifidobacterial strain administered represented between 75-95% of the total bifidobacteria isolated from all treated groups, and translocation to organs was not detected. These findings indicate that B. longum attenuates the production of inflammatory cytokines and the CD4+ T-cell mediated immune response in an animal model of gliadin-induced enteropathy.

Celiac disease manifested during the treatment of chronic hepatitis C by pegylated alpha interferon and ribavirin

Authors report a case of patient suffering from haemophilia A and hepatitis C virus infection acquired probably after blood transfusions and substitution factors application. He was treated with pegylated interferon alpha and ribavirin, with the development of malabsorption symptoms during the therapy. Celiac disease was established by histological, histochemical and serological examinations. oth, interferon alpha and ribavirin treatment as well as virus of hepatitis C may trigger coeliac disease in genetically predisposed individuals. The immunological mechanism of celiac disease include balance disruption between Th1 and Th2 immunological response with Th1 predominance. Only few similar cases have been published in the professional literature to date. Development of celiac disease during interferon alpha therapy with haemophilia A was not published until now (Fig. 3, Ref. 13).

Overactivity of the intestinal endocannabinoid system in celiac disease and in methotrexate-treated rats

The endocannabinoid system is upregulated in both human inflammatory bowel diseases and experimental models of colitis. In this study, we investigated whether this upregulation is a marker also of celiac disease-induced atrophy. The levels of the cannabinoid CB(1) receptor, of the endocannabinoids, anandamide, and 2-arachidonoyl-glycerol (2-AG), and of the anti-inflammatory mediator palmitoylethanolamide (PEA) were analyzed in bioptic samples from the duodenal mucosa of celiac patients at first diagnosis assessed by the determination of antiendomysial antibodies and histological examination. Samples were analyzed during the active phase of atrophy and after remission and compared to control samples from non-celiac patients. The levels of anandamide and PEA were significantly elevated (approx. 2- and 1.8-fold, respectively) in active celiac patients and so were those of CB(1) receptors. Anandamide levels returned to normal after remission with a gluten-free diet. We also analyzed endocannabinoid and PEA levels in the jejunum of rats 2, 3, and 7 days after treatment with methotrexate, which causes inflammatory features (assessed by histopathological analyses and myeloperoxidase activity) similar to those of celiac patients. In both muscle/serosa and mucosa layers, the levels of anandamide, 2-AG, and PEA peaked 3 days after treatment and returned to basal levels at remission, 7 days after treatment. Thus, intestinal endocannabinoid levels peak with atrophy and regress with remission in both celiac patients and methotrexate-treated rats. The latter might be used as a model to study the role of the endocannabinoid system in celiac disease.

Gliadin stimulation of murine macrophage inflammatory gene expression and intestinal permeability are MyD88-dependent: role of the innate immune response in Celiac disease

Recent studies have demonstrated the importance of TLR signaling in intestinal homeostasis. Celiac disease (CD) is an autoimmune enteropathy triggered in susceptible individuals by the ingestion of gliadin-containing grains. In this study, we sought to test the hypothesis that gliadin initiates this response by stimulating the innate immune response to increase intestinal permeability and by up-regulating macrophage proinflammatory gene expression and cytokine production. To this end, intestinal permeability and the release of zonulin (an endogenous mediator of gut permeability) in vitro, as well as proinflammatory gene expression and cytokine release by primary murine macrophage cultures, were measured. Gliadin and its peptide derivatives, 33-mer and p31-43, were found to be potent inducers of both a zonulin-dependent increase in intestinal permeability and macrophage proinflammatory gene expression and cytokine secretion. Gliadin-induced zonulin release, increased intestinal permeability, and cytokine production were dependent on myeloid differentiation factor 88 (MyD88), a key adapter molecule in the TLR/IL-1R signaling pathways, but were neither TLR2- nor TLR4-dependent. Our data support the following model for the innate immune response to gliadin in the initiation of CD. Gliadin interaction with the intestinal epithelium increases intestinal permeability through the MyD88-dependent release of zonulin that, in turn, enables paracellular translocation of gliadin and its subsequent interaction with macrophages within the intestinal submucosa. There, the interaction of gliadin with macrophages elicits a MyD88-dependent proinflammatory cytokine milieu that facilitates the interaction of T cells with APCs, leading ultimately to the Ag-specific adaptive immune response seen in patients with CD.

Coeliac Disease: Background and biochemical aspects

Coeliac Disease has to be considered a main food related affliction, with life long consequences for the people having the disease. Coeliac Disease patients suffer from adverse effects that can be related to specific gluten peptide sequences that trigger a sequence of immune related reactions leading to damage of the intestine and related malabsorption symptoms. Recently, detailed information has come available on peptide sequences that are toxic for Coeliac Disease patients. This information is discussed in relation to prevention of the disease and the development of safe cereals for Coeliac Disease patients.

Silent celiac disease in chronic hepatitis C: impact of interferon treatment on the disease onset and clinical outcome

GOALS

To assess the impact of interferon treatment on celiac disease onset in hepatitis C patients and to clarify its clinical relevance and outcome.

BACKGROUND

Hepatitis C is associated with autoimmunity, which can be exacerbated by interferon treatment. Cases of celiac disease activation during interferon treatment have been reported.

STUDY

Retrospective evaluation of 534 hepatitis C patients with or without symptoms compatible with celiac disease onset during interferon treatment and 225 controls. Anti-transglutaminase antibodies were assayed. HLA-DQA1 and -B1 loci were typed. Upper gastrointestinal endoscopy was applied to confirm the diagnosis in antibody-positive patients.

RESULTS

Anti-transglutaminase antibodies were detected before treatment in 1.3% of hepatitis C patients and in 0.4% of controls (not significant). Eighty-six percent of patients with anti-transglutaminase antibodies showed activation of celiac disease while on interferon. Symptoms ranged from mild to severe, and interferon had to be discontinued in 2 of 7 (29%) patients. Symptoms disappeared in 6 of 7 patients after interferon withdrawal. Onset of symptoms compatible with celiac disease during interferon therapy was significantly associated with the presence of anti-transglutaminase antibodies (OR 53).

CONCLUSIONS

In hepatitis C patients, the activation of silent celiac disease during interferon treatment is almost universal and should be suspected, but it uncommonly requires interferon treatment discontinuation. Symptoms subside after interferon withdrawal.

Celiac disease onset after pegylated interferon and ribavirin treatment of chronic hepatitis C

AIM

Report of a case of a woman patient who developed celiac disease after pegylated interferon alpha-2a and ribavirin use for chronic hepatitis C.

PATIENT AND METHOD

A 34-year-old woman with chronic hepatitis C, genotype 3, receiving pegylated interferon alpha-2a and ribavirin for 6 months, developed progressive malaise and anemia 6 months after the end of treatment.

RESULT

Additional investigation revealed duodenal villous atrophy and positivity for anti-endomysium and anti-gliadin antibodies. Celiac disease diagnosis was performed and symptoms and laboratory abnormalities improved after gluten-free diet.

CONCLUSION

Celiac disease must be ruled out in patients with malabsorption complaints in or after interferon (or pegylated interferon) therapy. Screening for celiac disease with detection of anti-endomysium antibodies would be done in susceptible patients.

Characterization of cereal toxicity for celiac disease patients based on protein homology in grains

BACKGROUND AND AIMS

Celiac disease is caused by T-cell responses to wheat gluten-derived peptides. The presence of such peptides in other widely consumed grains, however, has hardly been studied.

METHODS

We have performed homology searches to identify regions with sequence similarity to T-cell stimulatory gluten peptides in the available gluten sequences: the hordeins of barley, secalins of rye, and avenins of oats. The identified peptides were tested for T-cell stimulatory properties.

RESULTS

With 1 exception, no identical matches with T-cell stimulatory gluten peptides were found in the other grains. However, less stringent searches identified 11 homologous sequences in hordeins, secalins, and avenins located in regions similar to those in the original gluten proteins. Seven of these 11 peptides were recognized by gluten-specific T-cell lines and/or clones from patients with celiac disease. Comparison of T-cell stimulatory sequences with homologous but non-T-cell stimulatory sequences indicated key amino acids that on substitution either completely or partially abrogated the T-cell stimulatory activity of the gluten peptides. Finally, we show that single nucleotide substitutions in gluten genes will suffice to induce these effects.

CONCLUSIONS

These results show that the disease-inducing properties of barley and rye can in part be explained by T-cell cross-reactivity against gluten-, secalin-, and hordein-derived peptides. Moreover, the results provide a first step toward a rational strategy for gluten detoxification via targeted mutagenesis at the genetic level.

Experimentally induced gluten enteropathy and protective effect of epidermal growth factor in artificially fed neonatal rats

BACKGROUND

A protective effect of breast-feeding against the development of celiac disease has been described, but the nature and effects of the actual milk components have not been established. Epidermal growth factor (EGF), a milk cytokine affecting the proliferation and differentiation of mucosal epithelial cells, was studied as to its potential protective effect on the damage of intestinal mucosa by gliadin in a model system.

METHODS

Enteropathy was induced by gliadin in inbred AVN strain rat pups delivered by cesarean section, breast-fed, or hand-fed a milk formula. All experimental groups were treated with interferon-gamma (1,000 U per animal, administered intraperitoneally) after birth. Gliadin (0.5 and 3 mg) was intragastrically administered to the pups on days 0 and 3, and a 30-mg challenge dose was given on day 20 (24 hours before the termination of the experiment). One group of artificially fed pups received EGF (100 ng/ml) continuously in the diet.

RESULTS

Gliadin- and interferon-gamma-treated formula-fed rat pups showed villus atrophy, increase of inflammatory cells, including CD4+ T lymphocytes in the lamina propria, and damage to epithelial tight junctions and the enterocyte brush border. Morphometrically, the villus height was significantly less than in other groups. Recombinant EGF was markedly increased in the epithelial cells of injured jejunum. The intestinal mucosa of gliadin- and interferon-gamma-treated pups kept on a EGF-supplemented artificial diet resembled that of breast-fed pups.

CONCLUSION

Pathologic changes in jejunal mucosa (villus atrophy and inflammation) resembling gliadin-induced atrophy appeared on administration of interferon-gamma and gliadin to rat pups fed an artificial milk diet immediately after birth. Addition of EGF to the diet protected the rats against pathologic mucosal changes.

Coeliac disease following high-dose chemotherapy

This report describes an interesting case of severe diarrhoea following high-dose chemotherapy for non-Hodgkin's lymphoma. This caused significant morbidity and resolved on a gluten-free diet.

In vivo gluten challenge in celiac disease

In vivo gluten challenge has been used since the early 1950s to study the role of cereal fractions in celiac disease. While early studies relied on crude indicators of celiac toxicity, the advent of jejunal biopsy and sophisticated immunohistochemical techniques has allowed accurate studies to be performed. Studies to determine the nature of the cereal component that is toxic to patients with celiac disease have concentrated on wheat because of its nutritional importance. A number of in vitro studies indicated the presence of one or more celiac-activating epitopes with the N-terminus of the A-gliadin molecule. In vivo challenge with three synthetic peptides subsequently indicated the toxicity of a peptide corresponding to amino acids 31 to 49 of A-gliadin. In vivo gluten challenge is the gold standard for the assessment of celiac toxicity; however, jejunal biopsy is a relatively invasive procedure, thus, other methods have been investigated. Direct infusion of the rectum with gluten has been shown to result in an increase in mucosal intraepithelial lymphocytes, occurring only in celiac patients. This method has been used to study the celiac toxicity of gliadin subfractions. The in vitro technique of small intestinal biopsy organ culture is also a useful tool and appears to give the same results as in vivo challenge. The importance of tiny amounts of gliadin in the diet, such as that which occurs in wheat starch, has been studied by in vivo challenge; this technique has clarified the position of oats in the gluten-free diet. Several studies suggest that this cereal may be included in the diet of most adult celiac patients. Studies of the transport of gliadin across the enterocyte following ingestion or challenge suggest that gliadin may be metabolized by a different pathway in celiac disease. This could result in an abnormal presentation to the immune system, triggering a pathogenic rather than a tolerogenic response.