ArticleLiterature Review

Non-Host Factors Influencing Onset and Severity of Celiac Disease

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... Genetic predispositions (e.g., HLA genes) and environmental factors such as diet and the microbiome significantly influence the onset and severity of celiac disease. The role of nonhost factors in celiac disease development provides mechanistic insights from animal studies and discusses their implications for preventive and therapeutic interventions [126]. HLA genetic variants may affect COVID-19 susceptibility, severity, and mortality. ...
... studies revealing how these factors modulate pathogenesis. Understanding these nonhost factors can enhance preventive and therapeutic strategies for celiac disease [126]. Epigenetic dysregulation significantly contributes to systemic lupus erythematosus (SLE), an autoimmune disease marked by autoantibody production and inflammation. ...
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Celiac disease (CeD) is an immune-mediated disease, triggered by gluten ingestion, in genetically susceptible individuals. The gluten-free diet (GFD) is the only current treatment for CeD, but is difficult to follow, has high non-adherence rates, and does not always lead to symptomatic or mucosal remission. Microbially-mediated mechanisms have been proposed to contribute to disease pathogenesis, and clinical studies support an association, but mechanistic insight has been difficult to obtain. Recent advances using translational approaches have provided clues to the mechanisms through which bacteria could contribute to CeD pathogenesis. In this review we discuss these bacterially mediated mechanisms, which include the modulation of pathogenic or protective pathways. Targeting these pathways through microbial therapeutics could provide adjuvant therapies to the GFD.
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Other than exposure to gluten and genetic compatibility, the gut microbiome has been suggested to be involved in celiac disease (CD) pathogenesis by mediating interactions between gluten/environmental factors and the host immune system. However, to establish disease progression markers, it is essential to assess alterations in the gut microbiota before disease onset. Here, a prospective metagenomic analysis of the gut microbiota of infants at risk of CD was done to track shifts in the microbiota before CD development. We performed cross-sectional and longitudinal analyses of gut microbiota, functional pathways, and metabolites, starting from 18 mo before CD onset, in 10 infants who developed CD and 10 matched nonaffected infants. Cross-sectional analysis at CD onset identified altered abundance of six microbial strains and several metabolites between cases and controls but no change in microbial species or pathway abundance. Conversely, results of longitudinal analysis revealed several microbial species/strains/pathways/metabolites occurring in increased abundance and detected before CD onset. These had previously been linked to autoimmune and inflammatory conditions (e.g., Dialister invisus, Parabacteroides sp., Lachnospiraceae, tryptophan metabolism, and metabolites serine and threonine). Others occurred in decreased abundance before CD onset and are known to have anti-inflammatory effects (e.g., Streptococcus thermophilus, Faecalibacterium prausnitzii, and Clostridium clostridioforme). Additionally, we uncovered previously unreported microbes/pathways/ metabolites (e.g., Porphyromonas sp., highmannose–type N-glycan biosynthesis, and serine) that point to CD-specific biomarkers. Our study establishes a road map for prospective longitudinal study designs to better understand the role of gut microbiota in disease pathogenesis and therapeutic targets to reestablish tolerance and/or prevent autoimmunity.
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The intestinal microbiome may trigger celiac disease (CD) in individuals with a genetic disposition when exposed to dietary gluten. Research demonstrates that nutrition during infancy is crucial to the intestinal microbiome engraftment. Very few studies to date have focused on the breast milk composition of subjects with a history of CD on a gluten-free diet. Here, we utilize a multi-omics approach with shotgun metagenomics to analyze the breast milk microbiome integrated with metabolome profiling of 36 subjects, 20 with CD on a gluten-free diet and 16 healthy controls. These analyses identified significant differences in bacterial and viral species/strains and functional pathways but no difference in metabolite abundance. Specifically, three bacterial strains with increased abundance were identified in subjects with CD on a gluten-free diet of which one (Rothia mucilaginosa) has been previously linked to autoimmune conditions. We also identified five pathways with increased abundance in subjects with CD on a gluten-free diet. We additionally found four bacterial and two viral species/strains with increased abundance in healthy controls. Overall, the differences observed in bacterial and viral species/strains and in functional pathways observed in our analysis may influence microbiome engraftment in neonates, which may impact their future clinical outcomes.
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Background Although intestinal fungi are known to interact with the immune system, the relationship between intestinal fungi and childhood celiac disease (CeD), an immune-mediated condition, has rarely been reported.AimsThe aim of this study was to describe gut fungal profiles in a cohort of children with new-onset CeD.Methods Mucosal and fecal samples were collected from children with CeD and controls and subjected to metagenomics analysis of fungal microbiota communities. DNA libraries were sequenced using Illumina HiSeq platform 2 × 150 bp. Bioinformatic analysis was performed to quantify the relative abundance of fungi. Shannon alpha diversity metrics and beta diversity principal coordinate (PCo) analyses were calculated, and DESeq tests were performed between celiac and non-celiac groups.ResultsOverall more abundant taxa in samples of children with CeD included Tricholomataceae, Saccharomycetaceae, Saccharomycetes Saccharomyces cerevisiae, and Candida, whereas less abundant taxa included Pichiaceae, Pichia kudriavzevii, Pneumocystis, and Pneumocystis jirovecii. Alpha diversity between CeD and control individuals did not differ significantly, and beta diversity PCo analysis showed overlap of samples from CeD and controls for both fecal or mucosal samples; however, there was a clear separation between mucosal and fecal overall samplesConclusions We report fungal dysbiosis in children with CeD, suggesting a possible role in the pathogenesis of CeD. Further larger, controlled, prospective and longitudinal studies are needed to verify the results of this study and clarify the functional role of fungi in CeD.
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Enterovirus and adenovirus infections have been linked to the development of celiac disease. We evaluated this association in children who developed biopsy-proven celiac disease (N = 41) during prospective observation starting from birth, and in control children (N = 53) matched for the calendar time of birth, sex, and HLA-DQ genotype. Enterovirus and adenovirus infections were diagnosed by seroconversions in virus antibodies in longitudinally collected sera using EIA. Enterovirus infections were more frequent in case children before the appearance of celiac disease-associated tissue transglutaminase autoantibodies compared to the corresponding period in control children (OR 6.3, 95% CI 1.8–22.3; p = 0.005). No difference was observed in the frequency of adenovirus infections. The findings suggest that enterovirus infections may contribute to the process leading to celiac disease.
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Celiac disease is characterized by a chronic immune-mediated inflammation of the small intestine, triggered by gluten contained in wheat, barley, and rye. Rothia aeria, a gram-positive natural colonizer of the oral cavity and the upper digestive tract is able to degrade and detoxify gluten in vitro. The objective of this study was to assess gluten-degrading activity of live and dead R. aeria bacteria in vitro, and to isolate the R. aeria gluten-degrading enzyme. Methods: After an overnight fast, Balb/c mouse were fed a 1 g pellet of standard chow containing 50% wheat (and 4% gliadin) with or without 1.6 × 107 live R. aeria bacteria. After 2 h, in vivo gluten degradation was assessed in gastric contents by SDS-PAGE and immunoblotting, and immunogenic epitope neutralization was assessed with the R5 gliadin ELISA assay. R. aeria enzyme isolation and identification was accomplished by separating proteins in the bacterial cell homogenate by C18 chromatography followed by gliadin zymography and mass spectrometric analysis of excised bands. Results: In mice fed with R. aeria, gliadins and immunogenic epitopes were reduced by 20% and 33%, respectively, as compared to gluten digested in control mice. Killing of R. aeria bacteria in ethanol did not abolish enzyme activity associated with the bacteria. The gluten degrading enzyme was identified as BAV86562.1, here identified as a member of the subtilisin family. Conclusion: This study shows the potential of R. aeria to be used as a first probiotic for gluten digestion in vivo, either as live or dead bacteria, or, alternatively, for using the purified R. aeria enzyme, to benefit the gluten-intolerant patient population.
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Introduction: Celiac disease is an autoimmune disorder where intestinal immunopathology arises after gluten consumption. Previous studies suggested that hookworm infection restores gluten tolerance; however, these studies were small (n = 12) and not placebo controlled. Methods: We undertook a randomized, placebo-controlled trial of hookworm infection in 54 people with celiac disease. The 94-week study involved treatment with either 20 or 40 Necator americanus third-stage larvae (L3-20 or L3-40) or placebo, followed by escalating gluten consumption (50 mg/d for 12 weeks, 1 g intermittent twice weekly for 12 weeks, 2 g/d sustained for 6 weeks, liberal diet for 1 year). Results: Successful study completion rates at week 42 (primary outcome) were similar in each group (placebo: 57%, L3-20: 37%, and L3-40: 44%; P = 0.61), however gluten-related adverse events were significantly reduced in hookworm-treated participants: Median (range) adverse events/participant were as follows: placebo, 4 (1-9); L3-20, 1 (0-9); and L3-40, 0 (0-3) (P = 0.019). Duodenal villous height:crypt depth deteriorated similarly compared with their enrolment values in each group (mean change [95% confidence interval]: placebo, -0.6 [-1.3 to 0.2]; L3-20, -0.5 [-0.8 to 0.2]; and L3-40, -1.1 [-1.8 to 0.4]; P = 0.12). A retrospective analysis revealed that 9 of the 40 L3-treated participants failed to establish hookworm infections. Although week 42 completion rates were similar in hookworm-positive vs hookworm-negative participants (48% vs 44%, P = 0.43), quality of life symptom scores were lower in hookworm-positive participants after intermittent gluten challenge (mean [95% confidence interval]: 38.9 [33.9-44] vs 45.9 [39.2-52.6]). Discussion: Hookworm infection does not restore tolerance to sustained moderate consumption of gluten (2 g/d) but was associated with improved symptom scores after intermittent consumption of lower, intermittent gluten doses.
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Background: Celiac disease (CD) is an autoimmune digestive disorder that occurs in genetically susceptible individuals in response to ingesting gluten, a protein found in wheat, rye, and barley. Research shows that genetic predisposition and exposure to gluten are necessary but not sufficient to trigger the development of CD. This suggests that exposure to other environmental stimuli early in life, e.g., cesarean section delivery and exposure to antibiotics or formula feeding, may also play a key role in CD pathogenesis through yet unknown mechanisms. Here, we use multi-omics analysis to investigate how genetic and early environmental risk factors alter the development of the gut microbiota in infants at risk of CD. Results: Toward this end, we selected 31 infants from a large-scale prospective birth cohort study of infants with a first-degree relative with CD. We then performed rigorous multivariate association, cross-sectional, and longitudinal analyses using metagenomic and metabolomic data collected at birth, 3 months and 6 months of age to explore the impact of genetic predisposition and environmental risk factors on the gut microbiota composition, function, and metabolome prior to the introduction of trigger (gluten). These analyses revealed several microbial species, functional pathways, and metabolites that are associated with each genetic and environmental risk factor or that are differentially abundant between environmentally exposed and non-exposed infants or between time points. Among our significant findings, we found that cesarean section delivery is associated with a decreased abundance of Bacteroides vulgatus and Bacteroides dorei and of folate biosynthesis pathway and with an increased abundance of hydroxyphenylacetic acid, alterations that are implicated in immune system dysfunction and inflammatory conditions. Additionally, longitudinal analysis revealed that, in infants not exposed to any environmental risk factor, the abundances of Bacteroides uniformis and of metabolite 3-3-hydroxyphenylproprionic acid increase over time, while those for lipoic acid and methane metabolism pathways decrease, patterns that are linked to beneficial immunomodulatory and anti-inflammatory effects. Conclusions: Overall, our study provides unprecedented insights into major taxonomic and functional shifts in the developing gut microbiota of infants at risk of CD linking genetic and environmental risk factors to detrimental immunomodulatory and inflammatory effects. Video Abstract.
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Background & Aims It is not clear whether alterations in the intestinal microbiota of children with celiac disease cause the disease or are a result of disease and/or its treatment with gluten-free diet (GFD). Methods We obtained 167 fecal samples from 141 children (20 with new-onset celiac disease, 45 treated with a GFD, 57 healthy children, and 19 unaffected siblings of children with celiac disease) in Glasgow, Scotland. Samples were analyzed by 16S rRNA sequencing and diet-related metabolites were measured by gas chromatography. We obtained fecal samples from 13 of the children with new-onset CD after 6 and 12 months on GFD. Relationships between microbiota with diet composition, gastrointestinal function, and biomarkers of GFD compliance were explored. Results Microbiota α diversity did not differ among groups. Microbial dysbiosis was not observed in children with new-onset celiac disease. In contrast, 2.8% (Bray-Curtis dissimilarity index, P=.025) and 2.5% (UniFrac distances, P=.027) of the variation in microbiota composition could be accounted for by the GFD. Between 3% to 5% of all taxa differed among all group comparisons. Eleven distinctive operational taxonomic units composed a microbe signature specific to celiac disease with high diagnostic probability. Most of the operational taxonomic units that differed between patients on GFD with new-onset celiac disease vs healthy children were associated with nutrient and food group intake (from 75% to 94%), and with biomarkers of gluten ingestion. Fecal levels of butyrate and ammonia decreased during the GFD. Conclusions Although several alterations in the intestinal microbiota of children with established celiac disease appear to be effects of a GFD, there are specific bacteria that are distinct biomarkers of celiac disease. Studies are needed to determine whether these bacteria contribute to pathogenesis of celiac disease.
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Introduction: Many patients with celiac disease (CD) experience persistent symptoms despite adhering to the gluten-free diet. Different studies have assessed the use of probiotics as an adjuvant treatment for CD. We performed a systematic review and meta-analysis to evaluate the efficacy of probiotics in improving gastrointestinal (GI) symptoms and quality of life (QOL) in patients with CD. Methods: We searched EMBASE, MEDLINE, CINAHL, Web of Science, CENTRAL, and DARE databases up to February 2019 for randomized controlled trials (RCTs) evaluating probiotics compared with placebo for treating CD. We collected data on GI symptoms, QOL, adverse events, serum tumor necrosis factor-α, intestinal permeability, and microbiota composition. Results: We screened 2,831 records and found that 7 articles describing 6 RCTs (n = 5,279 participants) were eligible for quantitative analysis. Probiotics improved GI symptoms when assessed by the GI Symptoms Rating Scale (mean difference symptom reduction: 228.7%; 95% confidence interval [CI] 243.96-213.52; P = 0.0002). There was no difference in GI symptoms after probiotics when different questionnaires were pooled. The levels of Bifidobacteria increased after probiotics (mean difference: 0.85 log colony-forming units (CFU) per gram; 95% CI 0.38-1.32 log CFU per gram; P = 0.0003). There were insufficient data on tumor necrosis factor-a levels or QOL for probiotics compared with placebo. No difference in adverse events was observed between probiotics and placebo. The overall certainty of the evidence ranged from very low to low. Discussion: Probiotics may improve GI symptoms in patients with CD. High-quality clinical trials are needed to improve the certainty in the evidence (see Visual abstract, Supplementary Digital Content 2, http://links.lww.com/AJG/B595).
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Coeliac disease is a complex, polygenic inflammatory enteropathy caused by exposure to dietary gluten that occurs in a subset of genetically susceptible individuals who express either the HLA-DQ8 or HLA-DQ2 haplotypes1,2. The need to develop non-dietary treatments is now widely recognized3, but no pathophysiologically relevant gluten- and HLA-dependent preclinical model exists. Furthermore, although studies in humans have led to major advances in our understanding of the pathogenesis of coeliac disease4, the respective roles of disease-predisposing HLA molecules, and of adaptive and innate immunity in the development of tissue damage, have not been directly demonstrated. Here we describe a mouse model that reproduces the overexpression of interleukin-15 (IL-15) in the gut epithelium and lamina propria that is characteristic of active coeliac disease, expresses the predisposing HLA-DQ8 molecule, and develops villous atrophy after ingestion of gluten. Overexpression of IL-15 in both the epithelium and the lamina propria is required for the development of villous atrophy, which demonstrates the location-dependent central role of IL-15 in the pathogenesis of coeliac disease. In addition, CD4+ T cells and HLA-DQ8 have a crucial role in the licensing of cytotoxic T cells to mediate intestinal epithelial cell lysis. We also demonstrate a role for the cytokine interferon-γ (IFNγ) and the enzyme transglutaminase 2 (TG2) in tissue destruction. By reflecting the complex interaction between gluten, genetics and IL-15-driven tissue inflammation, this mouse model provides the opportunity to both increase our understanding of coeliac disease, and develop new therapeutic strategies. An HLA- and gluten-dependent mouse model of coeliac disease with villous atrophy provides evidence for the cooperative role of IL-15 and gluten-specific CD4+ T cells in licensing the full activation of cytotoxic T cells that are necessary for inducing epithelial damage.
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The human leukocyte antigen (HLA) locus is strongly associated with T cell-mediated autoimmune disorders. HLA-DQ2.5-mediated celiac disease (CeD) is triggered by the ingestion of gluten, although the relative roles of genetic and environmental risk factors in CeD is unclear. Here we identify microbially derived mimics of gliadin epitopes and a parental bacterial protein that is naturally processed by antigen-presenting cells and activated gliadin reactive HLA-DQ2.5-restricted T cells derived from CeD patients. Crystal structures of T cell receptors in complex with HLA-DQ2.5 bound to two distinct bacterial peptides demonstrate that molecular mimicry underpins cross-reactivity toward the gliadin epitopes. Accordingly, gliadin reactive T cells involved in CeD pathogenesis cross-react with ubiquitous bacterial peptides, thereby suggesting microbial exposure as a potential environmental factor in CeD. Structural, biochemical and cellular analyses show that bacterial antigens can mimic gliadin epitopes involved in celiac disease being presented by HLA-DQ2.5 and recognized by T cells derived from patients.
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Objective Higher gluten intake, frequent gastrointestinal infections and adenovirus, enterovirus, rotavirus and reovirus have been proposed as environmental triggers for coeliac disease. However, it is not known whether an interaction exists between the ingested gluten amount and viral exposures in the development of coeliac disease. This study investigated whether distinct viral exposures alone or together with gluten increase the risk of coeliac disease autoimmunity (CDA) in genetically predisposed children. Design The Environmental Determinants of Diabetes in the Young study prospectively followed children carrying the HLA risk haplotypes DQ2 and/or DQ8 and constructed a nested case–control design. From this design, 83 CDA case–control pairs were identified. Median age of CDA was 31 months. Stool samples collected monthly up to the age of 2 years were analysed for virome composition by Illumina next-generation sequencing followed by comprehensive computational virus profiling. Results The cumulative number of stool enteroviral exposures between 1 and 2 years of age was associated with an increased risk for CDA. In addition, there was a significant interaction between cumulative stool enteroviral exposures and gluten consumption. The risk conferred by stool enteroviruses was increased in cases reporting higher gluten intake. Conclusions Frequent exposure to enterovirus between 1 and 2 years of age was associated with increased risk of CDA. The increased risk conferred by the interaction between enteroviruses and higher gluten intake indicate a cumulative effect of these factors in the development of CDA.
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OBJECTIVES Increased intestinal permeability seems to be a key factor in the pathogenesis of autoimmune diseases, including celiac disease (CeD). However, it is unknown whether increased permeability precedes CeD onset. This study’s objective was to determine whether intestinal permeability is altered before celiac disease autoimmunity (CDA) in at-risk children. We also examined whether environmental factors impacted zonulin, a widely used marker of gut permeability. METHODS We evaluated 102 children in the CDGEMM study from 2014–2022. We included 51 CDA cases and matched controls, who were enrolled for 12 months or more and consumed gluten. We measured serum zonulin from age 12 months to time of CDA onset, and the corresponding time point in controls, and examined clinical factors of interest. We ran a mixed-effects longitudinal model with dependent variable zonulin. RESULTS Children who developed CDA had a significant increase in zonulin in the 18.3 months (range 6–78) preceding CDA compared to those without CDA (slope differential = β = 0.1277, 95% CI: 0.001, 0.255). Among metadata considered, zonulin trajectory was only influenced by increasing number of antibiotic courses, which increased the slope of trajectory of zonulin over time in CDA subjects (P = .04). CONCLUSIONS Zonulin levels significantly rise in the months that precede CDA diagnosis. Exposure to a greater number of antibiotic courses was associated with an increase in zonulin levels in CDA subjects. This suggests zonulin may be used as a biomarker for preclinical CeD screening in at-risk children, and multiple antibiotic courses may increase their risk of CDA by increasing zonulin levels.
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Celiac disease (CD) is an autoimmune condition presenting with a wide variety of nonspecific gastrointestinal symptoms. It can be difficult to diagnose due to the vagueness of complaints such as diarrhea, anemia due to malabsorption, vitamin or electrolyte deficiencies, and/or failure to thrive. This condition is characterized by a sensitivity to ingested gluten-containing compounds. Blood tests can be used for screening, though confirmatory testing by a small intestine biopsy is needed for diagnosis. Viral infections can trigger autoimmune conditions in individuals. It is possible that viral infections, such as Ebsetein-Barr virus(EBV) or Cytomegalovirus (CMV), can trigger the clinical presentation of celiac disease in certain individuals with genetic predispositions. Early recognition of celiac disease is important to prevent both short and long-term complications and improve the quality of life for the individual. Here, we discuss a case where the patient developed celiac disease only months after a diagnosis of mononucleosis.
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Among human leukocyte antigen (HLA)-associated disorders, celiac disease has an immunopathogenesis that is particularly well understood. The condition is characterized by hypersensitivity to cereal gluten proteins, and the disease lesion is localized in the gut. Still, the diagnosis can be made by detection of highly disease-specific autoantibodies to transglutaminase 2 in the blood. We now have mechanistic insights into how the disease-predisposing HLA-DQ molecules, via presentation of posttranslationally modified gluten peptides, are connected to the generation of these autoantibodies. This review presents our current understanding of the immunobiology of this common disorder that is positioned in the border zone between food hypersensitivity and autoimmunity. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 18 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Article
Background & Aims Genes and gluten are necessary but insufficient to cause celiac disease (CeD). Altered gut microbiota has been implicated as an additional risk factor. Variability in sampling site may confound interpretation and mechanistic insight, as CeD affects primarily the small intestine. Thus, we characterized CeD microbiota along the duodenum and in feces and verified functional impact in gnotobiotic mice. Methods We used 16S rRNA gene sequencing (Illumina) and predicted gene function (PICRUSt2) in duodenal biopsies (D1, D2 and D3), aspirates, and stool from active CeD patients and controls. CeD alleles were determined in consented participants. A subset of duodenal samples stratified according to similar CeD risk genotypes (controls DQ2-/- or DQ2+/- and CeD DQ2+/-), were used for further analysis and to colonize germ-free mice for gluten metabolism studies. Results Microbiota composition and predicted function in CeD was largely determined by intestinal location. In the duodenum, but not stool, there was higher abundance of Escherichia coli (D1), Prevotella salivae (D2), and Neisseria (D3) in CeD versus controls. Predicted bacterial protease and peptidase genes were altered in CeD and impaired gluten degradation was detected only in mice colonized with CeD microbiota. Summary and Conclusions Our results show luminal and mucosal microbial niches along the gut in CeD. We identify novel microbial proteolytic pathways involved in gluten detoxification that are impaired in CeD, but not in controls carrying DQ2, suggesting association with active duodenal inflammation. Sampling site should be considered a cofounding factor in microbiome studies in CeD.
Article
Coeliac disease is an autoimmune disorder that primarily affects the small intestine, and is caused by the ingestion of gluten in genetically susceptible individuals. Prevalence in the general population ranges from 0·5% to 2%, with an average of about 1%. The development of the coeliac enteropathy depends on a complex immune response to gluten proteins, including both adaptive and innate mechanisms. Clinical presentation of coeliac disease is highly variable and includes classical and non-classical gastrointestinal symptoms, extraintestinal manifestations, and subclinical cases. The disease is associated with a risk of complications, such as osteoporosis and intestinal lymphoma. Diagnosis of coeliac disease requires a positive serology (IgA anti-transglutaminase 2 and anti-endomysial antibodies) and villous atrophy on small-intestinal biopsy. Treatment involves a gluten-free diet; however, owing to the high psychosocial burden of such a diet, research into alternative pharmacological treatments is currently very active.
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Accumulating evidence implicates Epstein-Barr virus (EBV) as an etiological factor in multiple sclerosis (MS). If EBV is a “driver” that causes antiviral immunity with associated autoimmune components rather than a “trigger” that unleashes self-perpetuating autoimmunity, then elimination of EBV would be a rational therapy for MS.
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Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system of unknown etiology. We tested the hypothesis that MS is caused by Epstein-Barr virus (EBV) in a cohort comprising more than 10 million young adults on active duty in the US military, 955 of whom were diagnosed with MS during their period of service. Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus. Serum levels of neurofilament light chain, a biomarker of neuroaxonal degeneration, increased only after EBV seroconversion. These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS.
Article
Celiac disease (CeD) is a frequent immune-mediated disease that affects not only the small intestine but also many extraintestinal sites. The role of gluten proteins as dietary triggers, HLA-DQ2 or DQ8 as major necessary genetic predisposition, and tissue transglutaminase (TG2) as mechanistically involved autoantigen, are unique features of CeD. Recent research implicates many cofactors working in synergism with these key triggers, including the intestinal microbiota and their metabolites, non-gluten dietary triggers, intestinal barrier defects, novel immune cell phenotypes, and mediators and cytokines. In addition, apart from HLA-DQ2 and -DQ8, multiple and complex predisposing genetic factors and interactions have been defined, most of which overlap with predispositions in other, usually autoimmune, diseases that are linked to CeD. The resultant better understanding of CeD pathogenesis, and its manifold manifestations has already paved the way for novel therapeutic approaches, beyond the lifelong strict gluten-free diet, that poses a burden to patients and often does not lead to complete mucosal healing. Thus, supported by improved mouse models for CeD and in vitro organoid cultures, several targeted therapies are in phase 2-3 clinical studies, such as highly effective gluten degrading oral enzymes, inhibition of TG2, cytokine therapies, induction of tolerance to gluten ingestion, but also adjunctive and preventive approaches using beneficial probiotics and micronutrients. These developments are supported by novel non-invasive markers of CeD severity and activity that may be used as companion diagnostics, allow an easy-to perform and reliable monitoring of patients, and finally support a personalized therapy of CeD.
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Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a human pathogen until the 1960s, when outbreaks were reported. Key technological advances, including in vitro cultivation, genomic and proteomic databases, and advances in microscopic and molecular approaches, have led to an understanding that this is a eukaryotic organism with a reduced genome rather than a truly premitochondriate eukaryote. This has included the discovery of mitosomes (vestiges of mitochondria), a transport system with many of the features of the Golgi apparatus, and even evidence for a sexual or parasexual cycle. Cell biology approaches have led to a better understanding of how Giardia survives with two nuclei and how it goes through its life cycle as a noninvasive organism in the hostile environment of the lumen of the host intestine. Studies of its immunology and pathogenesis have moved past the general understanding of the importance of the antibody response in controlling infection to determining the key role of the Th17 response. This work has led to understanding of the requirement for a balanced host immune response that avoids the extremes of an excessive response with collateral damage or one that is unable to clear the organism. This understanding is especially important in view of the remarkable ranges of early manifestations, which range from asymptomatic to persistent diarrhea and weight loss, and longer-term sequelae that include growth stunting in children who had no obvious symptoms and a high frequency of postinfectious irritable bowel syndrome (IBS).
Article
There has been a steep increase in allergic and autoimmune diseases, reaching epidemic proportions and now affecting more than one billion people worldwide. These diseases are more common in industrialized countries, and their prevalence continues to rise in developing countries in parallel to urbanization and industrialization. Intact skin and mucosal barriers are crucial for the maintenance of tissue homeostasis as they protect host tissues from infections, environmental toxins, pollutants and allergens. A defective epithelial barrier has been demonstrated in allergic and autoimmune conditions such as asthma, atopic dermatitis, allergic rhinitis, chronic rhinosinusitis, eosinophilic esophagitis, coeliac disease and inflammatory bowel disease. In addition, leakiness of the gut epithelium is also implicated in systemic autoimmune and metabolic conditions such as diabetes, obesity, multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis and autoimmune hepatitis. Finally, distant inflammatory responses due to a ‘leaky gut’ and microbiome changes are suspected in Alzheimer disease, Parkinson disease, chronic depression and autism spectrum disorders. This article introduces an extended ‘epithelial barrier hypothesis’, which proposes that the increase in epithelial barrier-damaging agents linked to industrialization, urbanization and modern life underlies the rise in allergic, autoimmune and other chronic conditions. Furthermore, it discusses how the immune responses to dysbiotic microbiota that cross the damaged barrier may be involved in the development of these diseases. In this review, Cezmi Akdis discusses how epithelial barrier-damaging agents linked to industrialization, urbanization and modern life may explain the increased prevalence of allergic disease as well as a wide range of autoimmune and metabolic conditions in which immune responses to translocated bacteria have systemic effects.
Article
Background & aims: In celiac disease (CeD), gluten induces immune activation, leading to enteropathy. TAK-101, gluten protein (gliadin) encapsulated in negatively charged poly(dl-lactide-co-glycolic acid) nanoparticles, is designed to induce gluten-specific tolerance. Methods: TAK-101 was evaluated in phase 1 dose escalation safety and phase 2a double-blind, randomized, placebo-controlled studies. Primary endpoints included pharmacokinetics, safety, and tolerability of TAK-101 (phase 1) and change from baseline in circulating gliadin-specific IFN-γ-producing cells at day 6 of gluten challenge, in patients with CeD (phase 2a). Secondary endpoints in the phase 2a study included changes from baseline in enteropathy (villus height to crypt depth ratio [Vh:Cd]), and frequency of intestinal intraepithelial lymphocytes (IELs) and peripheral gut-homing T cells. Results: In phase 2a, thirty-three randomized patients completed the 14-day gluten challenge. TAK-101 induced an 88% reduction in change from baseline in IFN-γ spot-forming units versus placebo (2.01 vs 17.58, P=.006). Vh:Cd deteriorated in the placebo group (-0.63, P=.002), but not in the TAK-101 group (-0.18, P=.110), although the intergroup change from baseline was not significant (P=0.08). IEL numbers remained equal. TAK-101 reduced changes in circulating α4β7+CD4+ (0.26 vs 1.05, P=.032), αEβ7+CD8+ (0.69 vs 3.64, P=.003), and γδ (0.15 vs 1.59, P=.010) effector memory T cells. TAK-101 (up to 8 mg/kg) induced no clinically meaningful changes in vital signs or routine clinical laboratory evaluations. No serious adverse events occurred. Conclusions: TAK-101 was well tolerated and prevented gluten-induced immune activation in CeD. The findings from the present clinical trial suggest that antigen-specific tolerance was induced and represent a novel approach translatable to other immune-mediated diseases.
Article
Introduction: To test whether parechovirus and anellovirus, frequent enteric viruses, were associated with subsequent celiac disease (CD). We hypothesized that children who later developed CD would have increased frequency of parechovirus infections before transglutaminase 2 (TG2) antibody development. Anellovirus testing was exploratory, as a potential marker of immune status. Methods: Matched case-control design nested within a longitudinal birth cohort (the MIDIA study) of children at genetic risk of CD (carrying the human leukocyte antigen genotype DR4-DQ8/DR3-DQ2, recruited throughout Norway during 2001-2007). We retrospectively tested blood samples taken at age 3, 6, 9, and 12 months, and then annually, to determine when TG2 antibodies developed. Of 220 genetically at-risk children tested, 25 were diagnosed with CD (cases; ESPGHAN 2012 criteria) and matched for follow-up time, birthdate, and county of residence with 2 randomly selected children free from CD (controls) from the cohort. Viruses were quantified in monthly stool samples (collected from 3 through 35 months of age) using real-time polymerase chain reaction methods. Results: Parechovirus was detected in 222 of 2,005 stool samples (11.1%) and was more frequent in samples from cases before developing TG2 antibodies (adjusted odds ratio 1.67, 95% confidence interval 1.14-2.45, P = 0.01). The odds ratio was higher when a sample was positive for both parechovirus and enterovirus (adjusted odds ratio 4.73, 95% confidence interval 1.26-17.67, P = 0.02). Anellovirus was detected in 1,540 of 1,829 samples (84.2%), but did not differ significantly between case and control subjects. Discussion: Early-life parechovirus infections were associated with development of CD in genetically at-risk children.
Article
Coeliac disease is a common enteropathy that occurs in genetically susceptible individuals in response to the ingestion of gluten proteins present in wheat, rye and barley. Currently, the only available treatment for the condition is a strict, life-long gluten-free diet that, despite being safe and often effective, is associated with several challenges. Due to the high cost, particularly restrictive nature and perception of decreased quality of life associated with the diet, some patients are continuously exposed to gluten, which prevents an adequate disease control. Moreover, a subgroup of patients does not respond to the diet adequately, and healing of the small-bowel mucosa can be incomplete. Thus, there is a need for alternative treatment forms. The increasingly understood pathogenetic process of coeliac disease has enabled the identification of various targets for future therapies. Multiple investigational therapies ranging from tolerogenic to immunological approaches are in the pipeline, and several drug candidates have entered phase II/III clinical trials. This Review gives a broad overview of the different investigative treatment modalities for coeliac disease and summarizes the latest advances in this field.
Article
Metabolism of tryptophan by the gut microbiota into derivatives that activate the aryl hydrocarbon receptor (AhR) contributes to intestinal homeostasis. Many chronic inflammatory conditions, including celiac disease involving a loss of tolerance to dietary gluten, are influenced by cues from the gut microbiota. We investigated whether AhR ligand production by the gut microbiota could influence gluten immunopathology in nonobese diabetic (NOD) mice expressing DQ8, a celiac disease susceptibility gene. NOD/DQ8 mice, exposed or not exposed to gluten, were subjected to three interventions directed at enhancing AhR pathway activation. These included a high-tryptophan diet, gavage with Lactobacillus reuteri that produces AhR ligands or treatment with an AhR ago-nist. We investigated intestinal permeability, gut microbiota composition determined by 16S rRNA gene sequencing, AhR pathway activation in intestinal contents, and small intestinal pathology and inflammatory markers. In NOD/ DQ8 mice, a high-tryptophan diet modulated gut microbiota composition and enhanced AhR ligand production. AhR pathway activation by an enriched tryptophan diet, treatment with the AhR ligand producer L. reuteri, or pharmacological stimulation using 6-formylindolo (3,2-b) carbazole (Ficz) decreased immunopathology in NOD/ DQ8 mice exposed to gluten. We then determined AhR ligand production by the fecal microbiota and AhR activation in patients with active celiac disease compared to nonceliac control individuals. Patients with active celiac disease demonstrated reduced AhR ligand production and lower intestinal AhR pathway activation. These results highlight gut microbiota-dependent modulation of the AhR pathway in celiac disease and suggest a new therapeutic strategy for treating this disorder.
Article
Microbial transglutaminase (mTG) catalyses the formation of protein crosslinks, deamidating glutamine in a side-reaction. Gluten deamidation by human tissue transglutaminase is critical to activate celiac disease pathogenesis making the addition of mTG to wheat-based products controversial. The ability of mTG (0-2000 U.kg⁻¹) to alter gluten’s structure, digestibility and the deamidation state of six immunogenic gluten peptides within bread was investigated. Gluten’s structure was altered when mTG exceeded 100 U.kg⁻¹, determined by confocal microscopy, extractability and free sulfhydryl assays. The effect of mTG on six immunogenic peptides was investigated by in vitro digestion (INFOGEST) and mass spectrometry. The addition of mTG to bread (0-2000 U.kg⁻¹) did not alter the deamidation state or digestibility of the immunogenic peptides investigated. Overall, this investigation indicated that the addition of mTG to bread does not create activated gluten peptides. This analysis provides evidence for risk assessments of mTG as a food processing aid.
Article
In celiac disease, exogenous gluten drives T cell–B cell interactions that cause autoimmunity
Article
Background & aims: Celiac disease could be treated, and potentially cured, by restoring T-cell tolerance to gliadin. We investigated the safety and efficacy of negatively charged, 500 nm, poly(lactide-co-glycolide) nanoparticles encapsulating gliadin protein (TIMP-GLIA) in 3 mouse models of celiac disease. Uptake of these nanoparticles by antigen-presenting cells was shown to induce immune tolerance in other animal models of autoimmune disease. Methods: We performed studies with C57BL/6, RAG1-/- (C57BL/6), and HLA-DQ8, huCD4 transgenic Ab0 NOD mice. Mice were given 1 or 2 tail-vein injections of TIMP-GLIA or control nanoparticles. Some mice were given intradermal injections of gliadin in complete Freund's adjuvant (immunization), or of soluble gliadin or ovalbumin (ear challenge). RAG-/- mice were given intraperitoneal injections of CD4+CD62L-CD44hi T cells from gliadin-immunized C57BL/6 mice, and were fed with AIN-76A-based diet containing wheat gluten (oral challenge), or without gluten. Spleen or lymph node cells were analyzed in proliferation and cytokine secretion assays, or by flow cytometry, RNA sequencing or real-time quantitative PCR. Serum samples were analyzed by gliadin antibody ELISA, and intestinal tissues were analyzed by histology. Human PBMC, or immature dendritic cells derived from human PBMC, were cultured in medium containing TIMP-GLIA, anti-CD3 antibody, or LPS (controls) and analyzed in proliferation and cytokine secretion assays or by flow cytometry. Whole blood or plasma from healthy volunteers was incubated with TIMP-GLIA, and hemolysis, platelet activation and aggregation, and complement activation or coagulation were analyzed. Results: TIMP-GLIA did not increase markers of maturation on cultured human dendritic cells or induce activation of T cells from patients with active or treated celiac disease. In the delayed-type hypersensitivity (model 1), the HLA-DQ8 transgenic (model 2), and the gliadin memory T cell enteropathy (model 3) models of celiac disease, intravenous injections of TIMP-GLIA significantly decreased gliadin-specific T cell proliferation (in models 1 and 2), inflammatory cytokine secretion (in models 1, 2, and 3), circulating gliadin-specific IgG/IgG2c (in models 1 and 2), ear swelling (in model 1), gluten-dependent enteropathy (in model 3), and body weight loss (in model 3). In model 1, the effects were shown to be dose dependent. Splenocytes from HLA-DQ8 transgenic mice given TIMP-GLIA nanoparticles, but not control nanoparticles, had increased levels of FOXP3, and gene expression signatures associated with tolerance induction. Conclusions: In mice with gliadin sensitivity, injection of TIMP-GLIA nanoparticles induced unresponsiveness to gliadin, and reduced markers of inflammation and enteropathy. This strategy might be developed for treatment of celiac disease.
Article
Importance High gluten intake during childhood may confer risk of celiac disease. Objectives To investigate if the amount of gluten intake is associated with celiac disease autoimmunity and celiac disease in genetically at-risk children. Design, Setting, and Participants The participants in The Environmental Determinants of Diabetes in the Young (TEDDY), a prospective observational birth cohort study designed to identify environmental triggers of type 1 diabetes and celiac disease, were followed up at 6 clinical centers in Finland, Germany, Sweden, and the United States. Between 2004 and 2010, 8676 newborns carrying HLA antigen genotypes associated with type 1 diabetes and celiac disease were enrolled. Screening for celiac disease with tissue transglutaminase autoantibodies was performed annually in 6757 children from the age of 2 years. Data on gluten intake were available in 6605 children (98%) by September 30, 2017. Exposures Gluten intake was estimated from 3-day food records collected at ages 6, 9, and 12 months and biannually thereafter until the age of 5 years. Main Outcomes and Measures The primary outcome was celiac disease autoimmunity, defined as positive tissue transglutaminase autoantibodies found in 2 consecutive serum samples. The secondary outcome was celiac disease confirmed by intestinal biopsy or persistently high tissue transglutaminase autoantibody levels. Results Of the 6605 children (49% females; median follow-up: 9.0 years [interquartile range, 8.0-10.0 years]), 1216 (18%) developed celiac disease autoimmunity and 447 (7%) developed celiac disease. The incidence for both outcomes peaked at the age of 2 to 3 years. Daily gluten intake was associated with higher risk of celiac disease autoimmunity for every 1-g/d increase in gluten consumption (hazard ratio [HR], 1.30 [95% CI, 1.22-1.38]; absolute risk by the age of 3 years if the reference amount of gluten was consumed, 28.1%; absolute risk if gluten intake was 1-g/d higher than the reference amount, 34.2%; absolute risk difference, 6.1% [95% CI, 4.5%-7.7%]). Daily gluten intake was associated with higher risk of celiac disease for every 1-g/d increase in gluten consumption (HR, 1.50 [95% CI, 1.35-1.66]; absolute risk by age of 3 years if the reference amount of gluten was consumed, 20.7%; absolute risk if gluten intake was 1-g/d higher than the reference amount, 27.9%; absolute risk difference, 7.2% [95% CI, 6.1%-8.3%]). Conclusions and Relevance Higher gluten intake during the first 5 years of life was associated with increased risk of celiac disease autoimmunity and celiac disease among genetically predisposed children.