Coeliac disease: dissecting a complex inflammatory disorder

Lack of genetic association of the TGM2 gene with schizophrenia in a Chinese population

The gene coding for transglutaminase 2 (TGM2) has been reported to be associated with schizophrenia in a White population. The present study was then designed to replicate this initial finding in a Chinese population. A total of 428 individuals with schizophrenia and 555 control participants were recruited for genetic analysis. Four single nucleotide polymorphisms present in the TGM2 gene were selected for genotyping, including rs2076380, rs7270785, rs4811528, and rs6023526, by PCR-based restriction fragment length polymorphism analysis. None of these four single nucleotide polymorphisms genotyped showed an association with schizophrenia, although these 428 cases and 555 controls had 97% power to detect a disease association in small effect size (odds ratio=1.5). The present results did not support the TGM2 association with schizophrenia. It is thus possible that the TGM2 finding may have resulted from a random error of sampling.

Evidence of Crohn's disease-related anti-glycoprotein 2 antibodies in patients with celiac disease

BACKGROUND

Autoantibodies to exocrine-pancreatic glycoprotein 2 (anti-GP2) are Crohn's disease (CD) markers. However, CD-specific antibodies have also been found in celiac-disease (CeD) patients, in which type 1 diabetes-specific autoantibodies against endocrine pancreatic targets can be present. We investigated whether anti-GP2 are also present in CeD, a disease like CD which is also characterised by intestinal mucosal inflammation with barrier impairment.

METHODS

Antibodies against GP2, tissue transglutaminase (tTG), deamidated gliadin (dGD), glutamic decarboxylase (GAD), and islet antigen-2 (IA2) were tested in sera from 73 CD patients, 90 blood donors (BD), and 79 (58 de novo) CeD patients (2 consecutive sera were available from 40 patients).

RESULTS

IgA and/or IgG anti-GP2 were found in 15/79 (19.0%) CeD patients on at least one occasion, in 25/73 (34.2%) CD patients, and in 4/90 (4.4%) BD (CeD vs. CD, p=0.042; BD vs. CeD and CD, p<0.001, respectively). Amongst the 58 de novo CeD patients, anti-GP2 IgA and/or IgG were present in 11 (19.0%). Anti-GP2 IgA was significantly less prevalent in CeD compared with CD (p=0.004). Anti-GP2 IgA and IgG in CD patients demonstrated a significantly higher median level compared to patients with CeD (p<0.001, p=0.008, respectively). IgA anti-GP2 levels correlated significantly with IgA anti-tTG and anti-dGD levels in CeD Spearman's coefficient of rank correlation (ρ)=0.42, confidence interval (CI): 0.26-0.56, p<0.001; ρ=0.54, CI 0.39-0.65, p<0.001, respectively.

CONCLUSIONS

The presence of anti-GP2 in CeD patients supports the notion that loss of tolerance to GP2 can probably be a manifestation of an autoinflammatory process in this intestinal disorder.

Metagenomics Reveals Dysbiosis and a Potentially Pathogenic N. flavescens Strain in Duodenum of Adult Celiac Patients

OBJECTIVES

Celiac disease (CD)-associated duodenal dysbiosis has not yet been clearly defined, and the mechanisms by which CD-associated dysbiosis could concur to CD development or exacerbation are unknown. In this study, we analyzed the duodenal microbiome of CD patients.

METHODS

The microbiome was evaluated in duodenal biopsy samples of 20 adult patients with active CD, 6 CD patients on a gluten-free diet, and 15 controls by DNA sequencing of 16S ribosomal RNA libraries. Bacterial species were cultured, isolated and identified by mass spectrometry. Isolated bacterial species were used to infect CaCo-2 cells, and to stimulate normal duodenal explants and cultured human and murine dendritic cells (DCs). Inflammatory markers and cytokines were evaluated by immunofluorescence and ELISA, respectively.

RESULTS

Proteobacteria was the most abundant and Firmicutes and Actinobacteria the least abundant phyla in the microbiome profiles of active CD patients. Members of the Neisseria genus (Betaproteobacteria class) were significantly more abundant in active CD patients than in the other two groups (P=0.03). Neisseria flavescens (CD-Nf) was the most abundant Neisseria species in active CD duodenum. Whole-genome sequencing of CD-Nf and control-Nf showed genetic diversity of the iron acquisition systems and of some hemoglobin-related genes. CD-Nf was able to escape the lysosomal compartment in CaCo-2 cells and to induce an inflammatory response in DCs and in ex-vivo mucosal explants.

CONCLUSIONS

Marked dysbiosis and an abundance of a peculiar CD-Nf strain characterize the duodenal microbiome in active CD patients thus suggesting that the CD-associated microbiota could contribute to the many inflammatory signals in this disorder.

Effects of moderate beer consumption on health and disease: A consensus document

A large evidence-based review on the effects of a moderate consumption of beer on human health has been conducted by an international panel of experts who reached a full consensus on the present document. Low-moderate (up to 1 drink per day in women, up to 2 in men), non-bingeing beer consumption, reduces the risk of cardiovascular disease. This effect is similar to that of wine, at comparable alcohol amounts. Epidemiological studies suggest that moderate consumption of either beer or wine may confer greater cardiovascular protection than spirits. Although specific data on beer are not conclusive, observational studies seem to indicate that low-moderate alcohol consumption is associated with a reduced risk of developing neurodegenerative disease. There is no evidence that beer drinking is different from other types of alcoholic beverages in respect to risk for some cancers. Evidence consistently suggests a J-shaped relationship between alcohol consumption (including beer) and all-cause mortality, with lower risk for moderate alcohol consumers than for abstainers or heavy drinkers. Unless they are at high risk for alcohol-related cancers or alcohol dependency, there is no reason to discourage healthy adults who are already regular light-moderate beer consumers from continuing. Consumption of beer, at any dosage, is not recommended for children, adolescents, pregnant women, individuals at risk to develop alcoholism, those with cardiomyopathy, cardiac arrhythmias, depression, liver and pancreatic diseases, or anyone engaged in actions that require concentration, skill or coordination. In conclusion, although heavy and excessive beer consumption exerts deleterious effects on the human body, with increased disease risks on many organs and is associated to significant social problems such as addiction, accidents, violence and crime, data reported in this document show evidence for no harm of moderate beer consumption for major chronic conditions and some benefit against cardiovascular disease.

The influence of a short-term gluten-free diet on the human gut microbiome

Background

A gluten-free diet (GFD) is the most commonly adopted special diet worldwide. It is an effective treatment for coeliac disease and is also often followed by individuals to alleviate gastrointestinal complaints. It is known there is an important link between diet and the gut microbiome, but it is largely unknown how a switch to a GFD affects the human gut microbiome.

Methods

We studied changes in the gut microbiomes of 21 healthy volunteers who followed a GFD for four weeks. We collected nine stool samples from each participant: one at baseline, four during the GFD period, and four when they returned to their habitual diet (HD), making a total of 189 samples. We determined microbiome profiles using 16S rRNA sequencing and then processed the samples for taxonomic and imputed functional composition. Additionally, in all 189 samples, six gut health-related biomarkers were measured.

Results

Inter-individual variation in the gut microbiota remained stable during this short-term GFD intervention. A number of taxon-specific differences were seen during the GFD: the most striking shift was seen for the family Veillonellaceae (class Clostridia), which was significantly reduced during the intervention (p = 2.81 × 10⁻⁰⁵). Seven other taxa also showed significant changes; the majority of them are known to play a role in starch metabolism. We saw stronger differences in pathway activities: 21 predicted pathway activity scores showed significant association to the change in diet. We observed strong relations between the predicted activity of pathways and biomarker measurements.

Conclusions

A GFD changes the gut microbiome composition and alters the activity of microbial pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-016-0295-y) contains supplementary material, which is available to authorized users.

HLA class II sequence variants influence tuberculosis risk in populations of European ancestry

Mycobacterium tuberculosis infections cause 9 million new tuberculosis cases and 1.5 million deaths annually. To identify variants conferring risk of tuberculosis, we tested 28.3 million variants identified through whole-genome sequencing of 2,636 Icelanders for association with tuberculosis (8,162 cases and 277,643 controls), pulmonary tuberculosis (PTB) and M. tuberculosis infection. We found association of three variants in the region harboring genes encoding the class II human leukocyte antigens (HLAs): rs557011[T] (minor allele frequency (MAF) = 40.2%), associated with M. tuberculosis infection (odds ratio (OR) = 1.14, P = 3.1 × 10(-13)) and PTB (OR = 1.25, P = 5.8 × 10(-12)), and rs9271378[G] (MAF = 32.5%), associated with PTB (OR = 0.78, P = 2.5 × 10(-12))--both located between HLA-DQA1 and HLA-DRB1--and a missense variant encoding p.Ala210Thr in HLA-DQA1 (MAF = 19.1%, rs9272785), associated with M. tuberculosis infection (P = 9.3 × 10(-9), OR = 1.14). We replicated association of these variants with PTB in samples of European ancestry from Russia and Croatia (P < 5.9 × 10(-4)). These findings show that the HLA class II region contributes to genetic risk of tuberculosis, possibly through reduced presentation of protective M. tuberculosis antigens to T cells.

Simultaneous detection of celiac disease-specific IgA antibodies and total IgA

Purpose

Celiac disease (CD) serology requires analysis of tissue transglutaminase type-2 (TG2autoAbs), deamidated gliadin (DGAbs), and as reference endomysial autoantibodies (EmA). Total IgA assessment helps to determine IgA-deficient CD patients. The novel multiplex indirect immunofluorescence (IIF) technique CytoBead was used to develop the first quantitative one-step serological CD assay comprising both simultaneous IgA autoAb and total IgA testing.

Methods

CytoBead CeliAK detecting TG2autoAb, DGAb, EmA, and simultaneously total IgA uses fluorescent microparticles for antigen and antibody immobilization along with monkey-esophagus tissue sections on glass slides. The assay was interpreted visually by classical fluorescent microscopy and digital IIF using AKLIDES^®. Overall, 380 samples (155 CD patients, 5 with IgA deficiency, 68 with cystic fibrosis, 59 with eye disease, 93 blood donors) were run for performance analysis. Data were compared with classical IgA autoAb analysis by ELISA and IIF.

Results

Comparing CD-specific IgA autoAb testing by CytoBead with classical IIF and ELISA, very good agreements for EmA, TG2autoAb, and DGAb were determined (Cohen’s κ = 0.98, 0.96, 0.85, respectively). The difference between multiplex and single testing revealed a significant difference for TG2autoAb testing only (McNemar, p = 0.0078). Four CD patients and 4 controls demonstrated TG2autoAb positivity by ELISA but were negative by CytoBead. Further, 140/155 (90.9 %) CD patients demonstrated TG2autoAb levels above ten times the upper normal and all five IgA-deficient samples IgA levels <0.2 g/L by CytoBead.

Conclusions

The novel multiplex CytoBead CeliAK enables simultaneous CD-specific autoAb and IgA deficiency analyses comparable with classical testing by single-parameter assays. Thus, comprehensive CD serology by CytoBead can alleviate the workload in routine laboratories.

Electronic supplementary material

The online version of this article (doi:10.1007/s13317-016-0073-2) contains supplementary material, which is available to authorized users.

Mouse models of food allergy: how well do they simulate the human disorder?

Food allergy is a growing health problem with serious concerns due to high potential for fatality. Rapid advances in the knowledge on causes and mechanisms as well as in developing effective prevention/therapeutic strategies are needed. To meet these goals, mouse models that simulate the human disorder are highly desirable. During the past decade, several mouse models of food allergies have been reported. Here, we briefly reviewed the human disorder and then critically evaluated these models seeking answers to the following important questions: To what extent do they simulate the human disorder? What are the strengths and limitations of these models? What are the challenges facing this scientific area? Our analysis suggest that: (i) the mouse models, with inherent strengths and limitations, are available for many major food allergies; there is scope for additional model development and validation; (ii) models mostly simulate the severe forms of human disorder with similar immune and clinical features; (iii) the approaches used to develop some of the mouse models may be questionable; and (iv) the specific mechanisms of sensitization as wells as oral elicitation of fatal reactions in both humans and mice remains incompletely understood and therefore warrants further research.

The potential utility of tight junction regulation in celiac disease: focus on larazotide acetate

Celiac disease (CD) is a common chronic immune disease triggered by gluten. Gliadin peptides pass through the epithelial layers, either paracellularly or transcellularly, to launch a potent adaptive immune response in the lamina propria. This aberrant immune response leads to diverse gastrointestinal and extra-gastrointestinal symptoms. Currently, the only treatment for CD is a strict lifelong adherence to a gluten-free diet (GFD), which can be challenging. An early effect of gluten in CD is an increase in gut permeability. Larazotide acetate, also known as AT-1001, is a synthetic peptide developed as a permeability regulator primarily targeting CD. In vitro studies indicate that larazotide acetate is capable of inhibiting the actin rearrangement caused by gliadin and clinical studies have been conducted using this peptide as a therapy for CD.

Presenting Pattern of Pediatric Celiac Disease

OBJECTIVES

Celiac disease (CD) is an autoimmune disease that can be complicated by impaired nutrition and growth. With the development of sensitive serologic tests, safe endoscopy, and efforts to educate primary care physicians, more children are diagnosed as having CD. The aim of this study is to evaluate the pattern of the presentation of pediatric CD in western New York.

METHODS

Chart review of pediatric patients with CD was undertaken. Patients' demographics, presenting features, disaccharidase assay (DA), celiac serology, and Marsh score were reviewed from patients seen at the Digestive Diseases and Nutrition Center, State University of New York at Buffalo from January 2003 through March 2013.

RESULTS

A total of 165 patients with CD were evaluated. Mean age was 10.7 ± 4.3 years, 76 male patients. The presenting features were abdominal pain (n = 87, 52.7%), constipation (n = 65, 38.9%), diarrhea (n = 52, 31.1%), family history of first-degree relative (n = 47, 28.1%), diabetes mellitus type 1 (n = 37, 22.2%), failure to thrive (n = 36, 21.8%), reflux (n = 25, 15.1%), vomiting (n = 24, 14.5%), fatigue (n = 15, 9%), short stature (n = 9, 5.4%), thyroid disease (n = 9, 5.4%), Down syndrome (n = 8, 4.8%). We found no correlation between Marsh score and serum tissue transglutaminase (tTG) immunoglobulin (Ig) A level at diagnosis and no correlation between DA and serum tTG IgA level, presenting feature and tTG IgA level, presenting feature and Marsh score, tTG IgA and DA, or between the age and the presenting feature.

CONCLUSIONS

Children newly diagnosed as having CD in western New York presented most frequently with abdominal pain and constipation and were older at the time of diagnosis than those described in the classical presentation of CD. We speculate that our patients may have a different long-term natural history and risk factors than originally described for patients with CD.

Elevated Transglutaminase Activity Triggers Angiotensin Receptor Activating Autoantibody Production and Pathophysiology of Preeclampsia

BACKGROUND

Preeclampsia (PE) is a life-threatening hypertensive disorder of pregnancy associated with autoantibodies, termed AT1-AA, that activate the AT1 angiotensin receptor. Although the pathogenic nature of these autoantibodies has been extensively studied, little is known about the molecular cause of their generation.

METHODS AND RESULTS

Here we show that tissue transglutaminase (TG2), an enzyme that conducts posttranslational modification of target proteins, directly modified the 7-amino acid (7-aa) epitope peptide that localizes to the second extracellular loop of the AT1 receptor. These findings led us to further discover that plasma transglutaminase activity was induced and contributed to the production of AT1-AA and disease development in an experimental model of PE induced by injection of LIGHT, a tumor necrosis factor superfamily member. Key features of PE were regenerated by adoptive transfer of purified IgG from LIGHT-injected pregnant mice and blocked by the 7-amino acid epitope peptide. Translating our mouse research to humans, we found that plasma transglutaminase activity was significantly elevated in PE patients and was positively correlated with AT1-AA levels and PE features.

CONCLUSIONS

Overall, we provide compelling mouse and human evidence that elevated transglutaminase underlies AT1-AA production in PE and highlight novel pathogenic biomarkers and innovative therapeutic possibilities for the disease.

The localisation of the apical Par/Cdc42 polarity module is specifically affected in microvillus inclusion disease

BACKGROUND INFORMATION

Microvillus inclusion disease (MVID) is a genetic disorder affecting intestinal absorption. It is caused by mutations in MYO5B or syntaxin 3 (STX3) affecting apical membrane trafficking. Morphologically, MVID is characterised by a depletion of apical microvilli and the formation of microvillus inclusions inside the cells, suggesting a loss of polarity. To investigate this hypothesis, we examined the location of essential apical polarity determinants in five MVID patients.

RESULTS

We found that the polarity determinants Cdc42, Par6B, PKCζ/ι and the structural proteins ezrin and phospho-ezrin were lost from the apical membrane and accumulated either in the cytoplasm or on the basal side of enterocytes in patients, which suggests an inversion of cell polarity. Moreover, microvilli-like structures were observed at the basal side as per electron microscopy analysis. We next performed Myo5B depletion in three dimensional grown human Caco2 cells forming cysts and found a direct link between the loss of Myo5B and the mislocalisation of the same apical proteins; furthermore, we observed that a majority of cysts displayed an inverted polarity phenotype as seen in some patients. Finally, we found that this loss of polarity was specific for MVID: tissue samples of patients with Myo5B-independent absorption disorders showed normal polarity but we identified Cdc42 as a potentially essential biomarker for trichohepatoenteric syndrome.

CONCLUSION

Our findings indicate that the loss of Myo5B induces a strong loss of enterocyte polarity, potentially leading to polarity inversion.

SIGNIFICANCE

Our results show that polarity determinants could be useful markers to help establishing a diagnosis in patients. Furthermore, they could be used to characterise other rare intestinal absorption diseases.

Gluten consumption during late pregnancy and risk of celiac disease in the offspring: the TEDDY birth cohort

BACKGROUND

Maternal diet during pregnancy has been proposed to increase the risk of autoimmune diseases.

OBJECTIVE

The objective was to investigate the association between maternal consumption of gluten-containing foods during late pregnancy and subsequent risk of celiac disease in the offspring.

DESIGN

Genetically susceptible children prospectively followed from birth were screened annually for tissue transglutaminase autoantibodies (tTGAs). Children testing persistently positive for tTGAs were further evaluated for celiac disease. Diagnosis of celiac disease was confirmed by intestinal biopsy or was considered likely if the mean tTGA concentration was >100 units in 2 consecutive samples. A questionnaire on the mother's diet in late pregnancy was completed by 3-4.5 mo postpartum. Mothers were divided into 3 groups based on the tertiles of their consumption of gluten-containing foods (servings/d). The association between maternal gluten-containing food consumption and the risk of celiac disease was studied by using a time-to-event analysis.

RESULTS

At the time of analysis, 359 (5%) of the 6546 children developed celiac disease. Compared with the middle category of maternal gluten-containing food consumption (servings/d), low (HR: 0.87; 95% CI: 0.67, 1.13; P = 0.296) and high (HR: 0.84; 95% CI: 0.65, 1.09; P = 0.202) consumption was not associated with risk of celiac disease in the child after adjustment for country, human leukocyte antigen genotype, family history of celiac disease, maternal education, and sex of the child. Median maternal daily consumption frequency of gluten-containing foods was higher (P < 0.0001) in Finland (5.3; IQR: 3.9-6.9), Germany (4.3; IQR: 3.1-5.5), and Sweden (3.7; IQR: 2.8-4.9) than in the United States (3.4; IQR: 2.3-4.9). No significant interaction was found between country of residence and the mothers' consumption of gluten-containing foods in relation to risk of celiac disease.

CONCLUSION

The frequency of gluten-containing food consumption during late pregnancy is not associated with risk of celiac disease in the offspring.

Celiac Disease: Background and Historical Context

Medical descriptions of celiac disease date to the first century BC, and the first modern description was published in 1888. Further insights were gained throughout the 1900s, culminating in the identification of the dietary component, the major genetic determinant, and the autoantigen by the turn of the century. Understanding of the age of onset, population prevalence, and the extent of subclinical celiac disease developed in tandem. Thanks to advances in genomics, currently established loci account for over 50 % of the genetic risk. Nonetheless, much remains to be discovered. Advances in high-throughput genomic, biochemical, and cell analyses, as well as the bioinformatics needed to process the data, promise to deepen our understanding further. Here we present a primer of celiac disease, viewing the condition in turn from the historical, epidemiological, immunological, molecular, and genetic points of view. Research into any ailment has specific requirements: study subjects must be identified and relevant tissue samples collected and stored with the appropriate timing and conditions. These requirements are summarized. To conclude, a short discussion of future prospects is presented.

Igs as Substrates for Transglutaminase 2: Implications for Autoantibody Production in Celiac Disease

Autoantibodies specific for the enzyme transglutaminase 2 (TG2) are a hallmark of the gluten-sensitive enteropathy celiac disease. Production of the Abs is strictly dependent on exposure to dietary gluten proteins, thus raising the question how a foreign Ag (gluten) can induce an autoimmune response. It has been suggested that TG2-reactive B cells are activated by gluten-reactive T cells following receptor-mediated uptake of TG2-gluten complexes. In this study, we propose a revised model that is based on the ability of the BCR to serve as a substrate to TG2 and become cross-linked to gluten-derived peptides. We show that TG2-specific IgD molecules are preferred in the reaction and that binding of TG2 via a common epitope targeted by cells using the IgH variable gene segment (IGHV)5-51 results in more efficient cross-linking. Based on these findings we hypothesize that IgD-expressing B cells using IGHV5-51 are preferentially activated, and we suggest that this property can explain the previously reported low number of somatic mutations as well as the overrepresentation of IGHV5-51 among TG2-specific plasma cells in the celiac lesion. The model also couples gluten peptide uptake by TG2-reactive B cells directly to peptide deamidation, which is necessary for the activation of gluten-reactive T cells. It thereby provides a link between gluten deamidation, T cell activation, and the production of TG2-specific Abs. These are all key events in the development of celiac disease, and by connecting them the model may explain why the same enzyme that catalyzes gluten deamidation is also an autoantigen, something that is hardly coincidental.

Celiac disease and non-celiac gluten sensitivity

Celiac disease is a multisystem immune based disorder that is triggered by the ingestion of gluten in genetically susceptible individuals. The prevalence of celiac disease has risen in recent decades and is currently about 1% in most Western populations. The reason for this rise is unknown, although environmental factors related to the hygiene hypothesis are suspected. The pathophysiology of celiac disease involves both the innate and adaptive immune response to dietary gluten. Clinical features are diverse and include gastrointestinal symptoms, metabolic bone disease, infertility, and many other manifestations. Although a gluten-free diet is effective in most patients, this diet can be burdensome and can limit quality of life; consequently, non-dietary therapies are at various stages of development. This review also covers non-celiac gluten sensitivity. The pathophysiology of this clinical phenotype is poorly understood, but it is a cause of increasing interest in gluten-free diets in the general population.

Engineering of Kuma030: A Gliadin Peptidase That Rapidly Degrades Immunogenic Gliadin Peptides in Gastric Conditions

Celiac disease is characterized by intestinal inflammation triggered by gliadin, a component of dietary gluten. Oral administration of proteases that can rapidly degrade gliadin in the gastric compartment has been proposed as a treatment for celiac disease; however, no protease has been shown to specifically reduce the immunogenic gliadin content, in gastric conditions, to below the threshold shown to be toxic for celiac patients. Here, we used the Rosetta Molecular Modeling Suite to redesign the active site of the acid-active gliadin endopeptidase KumaMax. The resulting protease, Kuma030, specifically recognizes tripeptide sequences that are found throughout the immunogenic regions of gliadin, as well as in homologous proteins in barley and rye. Indeed, treatment of gliadin with Kuma030 eliminates the ability of gliadin to stimulate a T cell response. Kuma030 is capable of degrading >99% of the immunogenic gliadin fraction in laboratory-simulated gastric digestions within physiologically relevant time frames, to a level below the toxic threshold for celiac patients, suggesting great potential for this enzyme as an oral therapeutic for celiac disease.

Dietary protein ingested before and during short photoperiods makes an impact on affect-related behaviours and plasma composition of amino acids in mice

In mammals, short photoperiod is associated with high depression- and anxiety-like behaviours with low levels of the brain serotonin and its precursor tryptophan (Trp). Because the brain Trp levels are regulated by its ratio to large neutral amino acids (Trp:LNAA) in circulation, this study elucidated whether diets of various protein sources that contain different Trp:LNAA affect depression- and anxiety-like behaviours in C57BL/6J mice under short-day conditions (SD). In the control mice on a casein diet, time spent in the central area in the open field test (OFT) was lower in the mice under SD than in those under long-day conditions (LD), indicating that SD exposure induces anxiety-like behaviour. The SD-induced anxiety-like behaviour was countered by an α-lactalbumin diet given under SD. In the mice that were on a gluten diet before transition to SD, the time spent in the central area in the OFT under SD was higher than that in the SD control mice. Alternatively, mice that ingested soya protein before the transition to SD had lower immobility in the forced swim test, a depression-like behaviour, compared with the SD control. Analysis of Trp:LNAA revealed lower Trp:LNAA in the SD control compared with the LD control, which was counteracted by an α-lactalbumin diet under SD. Furthermore, mice on gluten or soya protein diets before transition to SD exhibited high Trp:LNAA levels in plasma under SD. In conclusion, ingestion of specific proteins at different times relative to photoperiodic transition may modulate anxiety- and/or depression-like behaviours, partially through changes in plasma Trp:LNAA.

Potential role of the IL-33/ST2 axis in celiac disease

The IL-33/ST2 axis has been implicated in the pathogenesis of several tissue-specific autoimmune diseases. Celiac disease (CD) is the only autoimmune disease in which both the major genetic factors (HLA-DQ2/DQ8) and etiologic ones (dietary gluten) for susceptibility are known. We have measured serum levels and determined intestinal tissue expression of IL-33 and its receptor soluble ST2 in patients with CD to investigate their association with disease activity. Serum and tissue levels of both IL-33 and sST2 were significantly higher in patients with CD compared with those in control patients without CD. We show that toxic peptides extracted from barley and wheat gliadin significantly stimulate the production of IL-33 and ST2 in cultured peripheral blood mononuclear cell from celiac patients, strongly implicating the IL-33/ST2 axis in the pathogenesis of CD. The higher levels of IL-33 and its receptor ST2 in tissue and serum reflect an active inflammatory state and may represent a potential biomarker for disease activity. A better understanding of IL-33/ST2 release, mode of action, and regulation will be crucial to develop therapeutics that target the IL-33/ST2 pathway to treat CD.Cellular & Molecular Immunology advance online publication, 7 September 2015; doi:10.1038/cmi.2015.85.

Interaction study between wheat-derived peptides and procyanidin B3 by mass spectrometry

Tannins have the ability to complex and precipitate proteins, being particularly reactive towards the proline-rich ones. The main structural feature of the wheat peptides responsible for the onset of Celiac Disease (CD) is their high content in proline residues. The aim of this work was to characterize the binding between a common food tannin (procyanidin B3) and different wheat-derived peptidic fractions. For this, seven peptide mixtures were obtained after in vitro digestion of a wheat gliadins crude extract and further characterized by LC-ESI-MS/MS. Several soluble B3-peptide complexes were identified by ESI-MS. The peptides involved in complex formation varied in terms of their size and diversity in CD epitopes. Although binding selectivity of procyanidin B3 towards peptides containing CD epitopes was not found, the major complexes contained or could contain immunoreactive peptides. This study highlights the potential beneficial effects of food polyphenols as a nutritional approach in the modulation of CD.

Genes involved in muscle contractility and nutrient signaling pathways within celiac disease risk loci show differential mRNA expression

Background

Risk gene variants for celiac disease, identified in genome-wide linkage and association studies, might influence molecular pathways important for disease development. The aim was to examine expression levels of potential risk genes close to these variants in the small intestine and peripheral blood and also to test if the non-coding variants affect nearby gene expression levels in children with celiac disease.

Methods

Intestinal biopsy and peripheral blood RNA was isolated from 167 children with celiac disease, 61 with potential celiac disease and 174 disease controls. Transcript levels for 88 target genes, selected from celiac disease risk loci, were analyzed in biopsies of a smaller sample subset by qPCR. Differentially expressed genes (3 from the pilot and 8 previously identified) were further validated in the larger sample collection (n = 402) of both tissues and correlated to nearby celiac disease risk variants.

Results

All genes were significantly down- or up-regulated in the intestinal mucosa of celiac disease children, NTS being most down-regulated (Fold change 3.6, p < 0.001). In contrast, PPP1R12B isoform C was up-regulated in the celiac disease mucosa (Fold change 1.9, p < 0.001). Allele specific expression of GLS (rs6741418, p = 0.009), INSR (rs7254060, p = 0.003) and NCALD (rs652008, p = 0.005) was also detected in the biopsies. Two genes (APPL2 and NCALD) were differentially expressed in peripheral blood but no allele specific expression was observed in this tissue.

Conclusion

The differential expression of NTS and PPP1R12B indicate a potential role for smooth muscle contractility and cell proliferation in celiac disease, whereas other genes like GLS, NCALD and INSR suggests involvement of nutrient signaling and energy homeostasis in celiac disease pathogenesis. A disturbance in any of these pathways might contribute to development of childhood celiac disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-015-0190-1) contains supplementary material, which is available to authorized users.

Characterization of Antibodies and Development of an Indirect Competitive Immunoassay for Detection of Deamidated Gluten

Diversification of gluten applications in the food and cosmetics industries was achieved through the production of water-soluble gluten that can be obtained by deamidation. Current analytical methods dedicated to gluten detection failed to detect deamidated gluten. After immunizing mice with the peptide LQPEEPFPE conjugated to keyhole limpet hemocyanin, five mouse monoclonal antibodies (mAbs) were produced and sequences of bound epitopes were determined as XPXEPFPE, where X is Q or E. The mAbs exhibited high specificity for deamidated gliadins and low molecular weight glutenin subunits. A competitive enzyme-linked immunosorbent assay (ELISA) based on INRA-DG1 mAb was developed with an IC50% of 85 ng/mL and a limit of detection of 25 ng/mL. The intra- and interassay coefficients of variation (CV) were <10% except for the interassay CV of the low-level control (40 ng/mL), which was 20%. This assay was capable of detecting three of the four deamidated gluten samples spiked in rice flour at 20 mg/kg.

Celiac disease can be predicted by high levels of anti-tissue transglutaminase antibodies in population-based screening

OBJECTIVES

The aim of the present study was to evaluate any potential correlation between anti-tissue transglutaminase antibodies of type immunoglobulin A (tTG-IgA) and the degree of gluten-induced enteropathy in children participating in a screening study for celiac disease (CD) and to assess to what extent the revised European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) guidelines cover this group of patients.

METHODS

The present study is a substudy of a cross-sectional CD screening study, Exploring the Iceberg of Celiacs in Sweden, a 2-phased study performed during 2005 to 2006 and 2009 to 2010. The 13,279 participating children had a blood test obtained, and those with positive tTG-IgA were recommended a small intestinal biopsy. The tTG-IgA levels at the time of biopsy were compared with those at the assessment of the biopsy.

RESULTS

There were 267 children included, of whom 230 were diagnosed as having CD. Of all of the children, 67 children had low tTG-IgA levels (<5 U/mL), of whom 55% had Marsh 3 lesions. All of the children with tTG-IgA levels exceeding 10 times the upper limit of normal values of 5 U/mL, that is, 50 U/mL, were diagnosed as having CD. Lowering the cutoff to 3 U/mL, all but 1 child with 30 U/mL got CD diagnosis.

CONCLUSIONS

By adopting the revised ESPGHAN criteria, biopsies could have been omitted in one-fourth of all of the patients. Our results indicate that the criteria may be useful even in screened children. Further studies are needed to confirm whether the 2012 ESPGHAN guidelines should be revised to also apply to the populations being screened.

Identification of Pseudolysin (lasB) as an Aciduric Gluten-Degrading Enzyme with High Therapeutic Potential for Celiac Disease

OBJECTIVES

Immunogenic gluten proteins implicated in celiac disease (CD) largely resist degradation by human digestive enzymes. Here we pursued the isolation of gluten-degrading organisms from human feces, aiming at bacteria that would digest gluten under acidic conditions, as prevails in the stomach.

METHODS

Bacteria with gluten-degrading activities were isolated using selective gluten agar plates at pH 4.0 and 7.0. Proteins in concentrated bacterial cell sonicates were separated by diethylaminoethanol chromatography. Enzyme activity was monitored with chromogenic substrates and gliadin zymography. Elimination of major immunogenic gluten epitopes was studied with R5 and G12 enzyme-linked immunosorbent assays.

RESULTS

Gliadin-degrading enzyme activities were observed for 43 fecal isolates, displaying activities in the ~150-200 and <50 kDa regions. The active strains were identified as Pseudomonas aeruginosa. Gliadin degradation in gel was observed from pH 2.0 to 7.0. Liquid chromatography-electrospray ionization-tandem mass spectrometry analysis identified the enzyme as pseudolysin (lasB), a metalloprotease belonging to the thermolysin (M4) family proteases. Its electrophoretic mobility in SDS-polyacrylamide gel electrophoresis and gliadin zymogram gels was similar to that of a commercial lasB preparation, with tendency of oligomerization. Pseudolysin eliminated epitopes recognized by the R5 antibody, while those detected by the G12 antibody remained intact, despite destruction of the nearby major T-cell epitope QPQLPY.

CONCLUSIONS

Pseudolysin was identified as an enzyme cleaving gluten effectively at extremely low as well as near-neutral pH values. The potential to degrade gluten during gastric transport opens possibilities for its application as a novel therapeutic agent for the treatment of CD.

Modified primers for rapid and direct electrochemical analysis of coeliac disease associated HLA alleles

Direct detection of PCR product via hybridisation assay, would facilitate the development of rapid tools for genetic analysis. Here, a PCR primer designed to generate a PCR amplicon tagged with single stranded DNA tails at each end of the duplex, which can be used for direct hybridisation with a surface immobilised probe and an enzyme labelled reporter probe is presented. Four modified sequence specific primers (SSP) pairs were designed for the selective amplification of coeliac disease associated alleles (DQA1*05, DQB1*02, DQB1*03:02 alleles), and human growth hormone (positive control). Multiplex PCR products were electrochemically detected in less than 5 min at 37 °C via direct hybridisation to short probes immobilised on individual electrodes of a genosensor array, and subsequent hybridisation to an enzyme labelled reporter probe. The developed electrochemical genosensor array exploiting the modified primers for the direct detection of PCR products was applied to the genotyping of real patient samples.

TNF-α Producing Innate Lymphoid Cells (ILCs) Are Increased in Active Celiac Disease and Contribute to Promote Intestinal Atrophy in Mice

Innate lymphoid cells (ILCs) are an emerging family of innate hematopoietic cells producing inflammatory cytokines and involved in the pathogenesis of several immune-mediated diseases. The aim of this study was to characterize the tissue distribution of ILCs in celiac disease (CD), a gluten-driven enteropathy, and analyze their role in gut tissue damage. ILC subpopulations were analyzed in lamina propria mononuclear cells (LPMCs) isolated from duodenal biopsies of CD patients and healthy controls (CTR) and jejunal specimens of patients undergoing gastro-intestinal bypass by flow cytometry. Cytokines and Toll-like receptors (TLR) were assessed in ILCs either freshly isolated or following incubation of control LPMC with peptidoglycan, poly I:C, or CpG, the agonists of TLR2, TLR3, or TLR9 respectively, by flow cytometry. The role of ILCs in gut tissue damage was evaluated in a mouse model of poly I:C-driven small intestine atrophy. Although the percentage of total ILCs did not differ between CD patients and CTR, ILCs producing TNF-α and IFN-γ were more abundant in CD mucosa compared to controls. ILCs expressed TLR2, TLR3 and TLR9 but neither TLR7 nor TLR4. Stimulation of LPMC with poly I:C but not PGN or CpG increased TNF-α and IFN-γ in ILCs. RAG1-deficient mice given poly I:C exhibited increased frequency of TNF-α but not IFN-γ/IL17A-producing ILCs in the gut and depletion of ILCs prevented the poly I:C-driven intestinal damage. Our data indicate that CD-related inflammation is marked by accumulation of ILCs producing TNF-α and IFN-γ in the mucosa. Moreover, ILCs express TLR3 and are functionally able to respond to poly I:C with increased synthesis of TNF-α thus contributing to small intestinal atrophy.

Mucosal immunity induced by gliadin-presenting spores of Bacillus subtilis in HLA-DQ8-transgenic mice

The induction of mucosal immunity requires efficient antigen delivery and adjuvant systems. Probiotic bacterial strains are considered to be very promising tools to address both of these needs. In particular, Bacillus subtilis spores are currently under investigation as a long-lived, protease-resistant adjuvant system for different antigens. Furthermore, a non-recombinant approach has been developed based on the stable adsorption of antigen on the spore surface. In the present study, we explored this strategy as a means of modulating the immune response to wheat gliadin, the triggering agent of celiac disease (CD), an enteropathy driven by inflammatory CD4(+) T cells. Gliadin adsorption was tested on untreated or autoclaved wild-type (wt) and mutant (cotH or cotE) spores. We found that gliadin was stably and maximally adsorbed by autoclaved wt spores. We then tested the immune properties of the spore-adsorbed gliadin in HLA-DQ8-transgenic mice, which express one of the two HLA heterodimers associated with CD. In vitro, spore-adsorbed gliadin was efficiently taken up by mouse dendritic cells (DCs). Interestingly, gliadin-pulsed DCs efficiently stimulated splenic CD4(+) T cells from mice immunised with spore-adsorbed gliadin. Nasal pre-dosing with spore-adsorbed gliadin failed to down-regulate the ongoing cellular response in gliadin-sensitised DQ8 mice. Notably, naïve mice inoculated intranasally with multiple doses of spore-adsorbed gliadin developed an intestinal antigen-specific CD4(+) T cell-mediated response. In conclusion, our data highlight the ability of spore-adsorbed gliadin to elicit a T-cell response in the gut that could be exploitable for developing immune strategies in CD.

Vaccination and other antigen-specific immunomodulatory strategies in celiac disease

BACKGROUND

Celiac disease (CD) results from an alteration in the oral tolerance to dietary gluten. The response to gluten is normally tightly regulated and involves the secretion of TGF-β and IL-10 from different subtypes of regulatory T cells (Tregs). Interestingly, in addition to proinflammatory cytokines, the inflamed CD mucosa also contains high levels of T cell-derived IL-10 compared with treated CD patients or normal donors. Furthermore, most studies describe an increase in the number of Foxp3+ Tregs in the small intestinal mucosa in CD patients compared to controls. This paradoxical condition suggests that regulatory mechanisms might operate to counterbalance the abnormal gliadin-triggered immune activation in untreated mucosa. Indeed, addition of exogenous IL-10 to mucosal cultures from treated CD patients can suppress gliadin-induced T cell activation. Considering the central role of adaptive immunity in CD, the development of strategies to stimulate these mechanisms is a primary goal of efforts to restore gluten tolerance. Key Messages: Different immunomodulatory strategies have been explored. NexVax2, a desensitizing vaccine that uses three dominant gluten peptides administered subcutaneously to induce a tolerogenic response in CD patients, is under development. Alternatively, the potential of substituted, cyclic or dimeric peptide analogues as blockers to prevent HLA from binding to the immunodominant gliadin epitopes has been demonstrated in vitro. In line with these results, we recently found that modified (transamidated) gliadins influenced the immune response in intestinal biopsy samples from CD patients with overt disease by drastically reducing the production of IFN-γ. Notably, in a mouse model, transamidated gliadins reverted the phenotype of the gliadin-inducible immune response from an inflammatory phenotype to an anti-inflammatory phenotype.

CONCLUSIONS

Various approaches are currently under investigation to recover gluten tolerance based on the use of both modified and native antigen molecules. More specific studies are now required to test the efficacy of such strategies for preventing CD.

Prolactin may be increased in newly diagnosed celiac children and adolescents and decreases after 6 months of gluten-free diet

BACKGROUND/AIMS

Prolactin (PRL) is produced by the anterior pituitary gland. It exerts its role on the breast gland but also plays a modulatory role in autoimmune mechanisms. Celiac disease (CD) is a gluten-sensitive autoimmune enteropathy sometimes associated with autoimmune endocrinopathies. No data on PRL levels in CD patients are available at diagnosis, and no conclusive data are reported.

METHODS

We aimed to evaluate PRL secretion in newly diagnosed CD pediatric patients and, in the case of hyperprolactinemia, any changes in its levels while the patients were on a gluten-free diet (GFD). We recruited 67 patients and 39 healthy controls.

RESULTS

PRL was statistically higher in the CD patients (13.5±9.2 ng/ml) than in the controls (8.5±5.0 ng/ml). In the CD group, PRL was inversely correlated with the age at diagnosis (r=-0.326; p=0.007). In patients with hyperprolactinemia at diagnosis, PRL decreased after 6 months of GFD.

CONCLUSION

This paper confirms that PRL may be increased at diagnosis of CD and shows, for the first time, that it decreases after a short course of GFD. Changes in the levels of inflammatory cytokines in CD may account for changes in PRL levels. Younger patients seem more prone to develop hyperprolactinemia than older ones.

The interaction between tannins and gliadin derived peptides in a celiac disease perspective

The demonstration that food tannins are able to complex with gliadin-derived peptides, in a way that is dependent on both structural features, highlights their potential as modulators of celiac disease.

Candidate Gene Knockdown in Celiac Disease

RNA interference (RNAi) is a powerful genetic tool that has created new opportunities in cell biology by allowing the specific modulation of gene expression under controlled conditions. Knockdown of genes associated with disease can provide valuable information pertaining to their function and potentially their role in the disease etiology. In the context of celiac disease, it allows us to examine closely the cellular changes that occur when the expression levels of genes of interest are reduced. Utilizing informative assays that demonstrate changes in cell behavior or other measurable endpoints such as cytokine production or migratory phenotypes can further our understanding of the pathogenic mechanisms in this prevalent autoimmune disorder. This chapter outlines protocols for examining the effects of RNAi on candidate genes and subsequent changes to migratory phenotype, transmigration, and adhesion.

High adherence to a gluten-free diet in adolescents with screening-detected celiac disease

OBJECTIVES

The aim of the study was to evaluate the gluten-free diet (GFD) adherence after 1 year of follow-up in children with screening-detected celiac disease (CD) in a general population.

METHODS

A total of 18,325 twelve-year-olds were invited to participate in a population-based CD screening (Exploring the Iceberg of Celiacs in Sweden), of whom 13,279 participated. In 240 children, CD was detected through elevated anti-tissue transglutaminase antibodies 2 (TG2-IgA) and verified by a small-intestinal biopsy. This substudy included 210 children with TG2-IgA, evaluated both at the initial biopsy occasion and at 1-year follow-up. GFD adherence was evaluated by a combination of TG2-IgA measurements and self-reported adherence (n = 193).

RESULTS

After 1 year, 85% (179/210) had normalized TG2-IgA levels (<5 U/mL). Among those who had >50 U/mL at diagnosis, 25% (16/63) still had elevated TG2-IgA, but for the majority their initial values were more than halved. Most reported a high level of GFD adherence ("always" 82% [158/193] and "often" 16% [30/193]), and 75% [145/193] reported always adhering combined with normalized TG2-IgA. Although reporting that they were always adherent, 13 (6.7%) had not yet normalized their TG2-IgA levels completely; however, a majority of these initially had the highest TG2-IgA levels.

CONCLUSIONS

GFD adherence is high in adolescents with CD detected by screening of the general population of Swedish 12-year-olds. Almost all of them had normalized serology and reported GFD adherence at the 1-year follow-up. A few adolescents who reported GFD adherence, however, had elevated TG2-IgA levels, suggesting more severe disease and/or nonadherence.

Identification and characterization of intestinal lactobacilli strains capable of degrading immunotoxic peptides present in gluten

AIM

Identify and characterize bacteria from the proximal gastrointestinal tract of pigs capable of degrading immunogenic gluten peptides.

METHODS AND RESULTS

Bacteria were cultured from the small intestine of pigs fed a 20% gluten diet and from an enrichment media with the 18-mer peptide LQLQPFPQPQLPYPQPQL. Isolates were screened for the production of specialized proteolytic enzymes and the ability to degrade and remove metastable peptides from α-gliadin (16-mer and 33-mer) and ω-gliadin (17-mer), with established roles in the aetiology of coeliac disease. Degradation was determined by ELISA and mass spectrometry (UHPLC-MS/MS in MRM mode), and hydrolysis fragments were characterized by LC-MS/MS. Four strains from the species Lactobacillus ruminis, Lactobacillus johnsonii, Lactobacillus amylovorus and Lactobacillus salivarius showed the highest peptide-degrading activities. Strains displayed different degradation rates and cleavage patterns that resulted in reduction but not complete removal of immunotoxic epitopes.

CONCLUSIONS

We employed a unique enrichment process to select for bacteria adapted to the conditions of the proximal gastrointestinal tract with the ability to partially detoxify well-characterized peptides involved in coeliac disease.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides a basis for the selection of Lactobacillus strains for probiotic applications aimed to reduce epitope-containing gluten peptides before reaching the epithelium of the small intestine of patients with coeliac disease.

Hematopoietic stem cell transplantation for non-malignant gastrointestinal diseases

Both, autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can be used to cure or ameliorate a variety of malignant and non-malignant diseases. The rationale behind this strategy is based on the concept of immunoablation using high-dose chemotherapy, with subsequent regeneration of naive T-lymphocytes derived from reinfused hematopoietic progenitor cells. In addition, the use of HSCT allows for the administration of high-dose chemotherapy (whether or not combined with immunomodulating agents such as antithymocyte globulin) resulting in a prompt remission in therapy-refractory patients. This review gives an update of the major areas of successful uses of HSCT in non-malignant gastrointestinal disorders. A Medline search has been conducted and all relevant published data were analyzed. HSCT has been proved successful in treating refractory Crohn’s disease (CD). Patients with refractory celiac disease type II and a high risk of developing enteropathy associated T-cell lymphoma have shown promising improvement. Data concerning HSCT and mesenchymal SCT in end-stage chronic liver diseases are encouraging. In refractory autoimmune gastrointestinal diseases high-dose chemotherapy followed by HSCT seems feasible and safe and might result in long-term improvement of disease activity. Mesenchymal SCT for a selected group of CD is promising and may represent a significant therapeutic alternative in treating fistulas in CD.

Activity-regulating structural changes and autoantibody epitopes in transglutaminase 2 assessed by hydrogen/deuterium exchange

The multifunctional enzyme transglutaminase 2 (TG2) is the target of autoantibodies in the gluten-sensitive enteropathy celiac disease. In addition, the enzyme is responsible for deamidation of gluten peptides, which are subsequently targeted by T cells. To understand the regulation of TG2 activity and the enzyme's role as an autoantigen in celiac disease, we have addressed structural properties of TG2 in solution by using hydrogen/deuterium exchange monitored by mass spectrometry. We demonstrate that Ca(2+) binding, which is necessary for TG2 activity, induces structural changes in the catalytic core domain of the enzyme. Cysteine oxidation was found to abolish these changes, suggesting a mechanism whereby disulfide bond formation inactivates the enzyme. Further, by using TG2-specific human monoclonal antibodies generated from intestinal plasma cells of celiac disease patients, we observed that binding of TG2 by autoantibodies can induce structural changes that could be relevant for the pathogenesis. Detailed mapping of two of the main epitopes targeted by celiac disease autoantibodies revealed that they are located adjacent to each other in the N-terminal part of the TG2 molecule.

BL-7010 demonstrates specific binding to gliadin and reduces gluten-associated pathology in a chronic mouse model of gliadin sensitivity

Celiac disease (CD) is an autoimmune disorder in individuals that carry DQ2 or DQ8 MHC class II haplotypes, triggered by the ingestion of gluten. There is no current treatment other than a gluten-free diet (GFD). We have previously shown that the BL-7010 copolymer poly(hydroxyethyl methacrylate-co-styrene sulfonate) (P(HEMA-co-SS)) binds with higher efficiency to gliadin than to other proteins present in the small intestine, ameliorating gliadin-induced pathology in the HLA-HCD4/DQ8 model of gluten sensitivity. The aim of this study was to investigate the efficiency of two batches of BL-7010 to interact with gliadin, essential vitamins and digestive enzymes not previously tested, and to assess the ability of the copolymer to reduce gluten-associated pathology using the NOD-DQ8 mouse model, which exhibits more significant small intestinal damage when challenged with gluten than HCD4/DQ8 mice. In addition, the safety and systemic exposure of BL-7010 was evaluated in vivo (in rats) and in vitro (genetic toxicity studies). In vitro binding data showed that BL-7010 interacted with high affinity with gliadin and that BL-7010 had no interaction with the tested vitamins and digestive enzymes. BL-7010 was effective at preventing gluten-induced decreases in villus-to-crypt ratios, intraepithelial lymphocytosis and alterations in paracellular permeability and putative anion transporter-1 mRNA expression in the small intestine. In rats, BL-7010 was well-tolerated and safe following 14 days of daily repeated administration of 3000 mg/kg. BL-7010 did not exhibit any mutagenic effect in the genetic toxicity studies. Using complementary animal models and chronic gluten exposure the results demonstrate that administration of BL-7010 is effective and safe and that it is able to decrease pathology associated with gliadin sensitization warranting the progression to Phase I trials in humans.

Effect of Rothia mucilaginosa enzymes on gliadin (gluten) structure, deamidation, and immunogenic epitopes relevant to celiac disease

Rothia mucilaginosa, a natural microbial inhabitant of the oral cavity, cleaves gluten (gliadin) proteins at regions that are resistant to degradation by mammalian enzymes. The aim of this study was to investigate to what extent the R. mucilaginosa cell-associated enzymes abolish gliadin immunogenic properties. Degradation of total gliadins and highly immunogenic gliadin 33-mer or 26-mer peptides was monitored by SDS-PAGE and RP-HPLC, and fragments were sequenced by liquid chromatography and electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS). Peptide deamidation by tissue transglutaminase (TG2), a critical step in rendering the fragments more immunogenic, was assessed by TG2-mediated cross-linking to monodansyl cadaverine (MDC), and by a +1-Da mass difference by LC-ESI-MS. Survival of potential immunogenic gliadin epitopes was determined by use of the R5 antibody-based ELISA. R. mucilaginosa-associated enzymes cleaved gliadins, 33-mer and 26-mer peptides into smaller fragments. TG2-mediated cross-linking showed a perfect inverse relationship with intact 33-mer and 26-mer peptide levels, and major degradation fragments showed a slow rate of MDC cross-linking of 6.18 ± 2.20 AU/min compared with 97.75 ± 10.72 and 84.17 ± 3.25 AU/min for the intact 33-mer and 26-mer, respectively, which was confirmed by reduced TG2-mediated deamidation of the fragments in mass spectrometry. Incubation of gliadins with Rothia cells reduced R5 antibody binding by 20, 82, and 97% after 30 min, 2 h, and 5 h, respectively, which was paralleled by reduced reactivity of enzyme-treated 33-mer and 26-mer peptides in the R5 competitive ELISA. Our broad complementary approach to validate gluten degrading activities qualifies R. mucilaginosa-associated enzymes as promising tools to neutralize T cell immunogenic properties for treatment of celiac disease.

Potential blood-based markers of celiac disease

Background

Blood-based diagnostics has the potential to simplify the process of diagnosing celiac disease (CD). Although high levels of autoantibodies against tissue transglutaminase (anti-TG2) are strongly indicative of active CD, several other scenarios involve a need for additional blood-based CD markers.

Methods

We investigated the levels of messenger RNA (mRNA) in whole blood (n = 49) and protein in plasma (n = 22) from cases with active CD (n = 20), with confirmed CD and normalized histology (n = 15), and without a CD diagnosis (n = 14). Group differences were analyzed using Kruskal-Wallis one-way analysis of variance by ranks. We also investigated correlations between levels of potential markers, histopathology according to the modified Marsh scale, and CD risk gradient based on HLA type, using Spearman rank correlation. The relation between HLA-DQ2 gene dose effect and the expression levels of selected blood-based markers was investigated using the Mann–Whitney U test. Finally, the diagnostic performance of anti-TG2, potential blood-based CD markers, and logistic regression models of combined markers was evaluated using receiver operating characteristic (ROC) curve analysis.

Results

CXCL11 protein levels and TNFRSF9 and TNFSF13B mRNA levels were identified as potential CD markers. These are all affected by or involved in the regulation of the NF-κB complex. CXCL11 protein levels and IL21 and IL15 mRNA levels were correlated with histopathology according to the modified Marsh scale, as were the established CD markers. HLA genotype risk and HLA-DQ2 gene dose effect did not show any significant relations with either the potential CD markers or the established CD markers. ROC curve analysis revealed a slight, non-significant increase in the area under the curve for the combined use of anti-TG2 and different constellations of potential blood-based CD markers compared to anti-TG2 alone.

Conclusions

The CD markers identified in this study further emphasize the significance of components related to NF-κB regulation in relation to CD. However, the relevance of CXCL11, TNFSF13B, TNFRSF9, and other NF-κB interacting proteins recognized by pathway analysis, needs to be further investigated in relation to diagnosis and monitoring of CD.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-230X-14-176) contains supplementary material, which is available to authorized users.

Autoreactive T cells specific for insulin B:11-23 recognize a low-affinity peptide register in human subjects with autoimmune diabetes

Previous studies in type 1 diabetes (T1D) in the nonobese diabetic mouse demonstrated that a crucial insulin epitope (B:9-23) is presented to diabetogenic CD4 T cells by IA(g7) in a weakly bound register. The importance of antigenic peptides with low-affinity HLA binding in human autoimmune disease remains less clear. The objective of this study was to investigate T-cell responses to a low-affinity self-epitope in subjects with T1D. HLA-DQ8 tetramers loaded with a modified insulin peptide designed to improve binding the low-affinity register were used to visualize T-cell responses following in vitro stimulation. Positive responses were only detectable in T1D patients. Because the immunogenic register of B:9-23 presented by DQ8 has not been conclusively demonstrated, T-cell assays using substituted peptides and DQ8 constructs engineered to express and present B:9-23 in fixed binding registers were used to determine the immunogenic register of this peptide. Tetramer-positive T-cell clones isolated from T1D subjects that responded to stimulation by B:11-23 peptide and denatured insulin protein were conclusively shown to recognize B:11-23 bound to HLA-DQ8 in the low-affinity register 3. These T cells also responded to homologous peptides derived from microbial antigens, suggesting that their initial priming could occur via molecular mimicry. These results are in accord with prior observations from the nonobese diabetic mouse model, suggesting a mechanism shared by mouse and man through which T cells that recognize a weakly bound peptide can circumvent tolerance mechanisms and play a role in the initiation of autoimmune diseases, such as T1D.

Intestinal titres of anti-tissue transglutaminase 2 antibodies correlate positively with mucosal damage degree and inversely with gluten-free diet duration in coeliac disease

It has always been known that anti-tissue transglutaminase 2 (anti-TG2) antibodies are produced in the small intestine. Their serum titres correlate with mucosal damage degree and decrease on a gluten-free diet (GFD). We aimed to correlate intestinal anti-TG2 antibodies levels with degree of mucosal damage and GFD duration. Thirty-four active, 71 potential and 24 CD patients on GFD for at least 2 years were enrolled. Anti-TG2 deposits were detected in intestinal biopsies by double immunofluorescence. Biopsies were cultured for 24 h with medium, and with gliadin peptic tryptic digest (PTG) or A-gliadin peptide 31-43 (P31-43). Anti-TG2 antibodies secreted into supernatants were measured by enzyme-linked immunosorbent assay (ELISA). All active CD patients secreted high titres of anti-TG2 antibodies into culture medium that increased with the worsening of mucosal injury (Spearman's r = 0·71; P < 0·0001). Seventy of 71 potential CD patients and 15 of 24 treated CD patients secreted low titres of anti-TG2 antibodies into supernatants, eight of nine negative treated patients being on GFD for more than 10 years. An inverse correlation between antibody titres and duration of GFD was found, (Spearman's r = -0·52; P < 0·01). All active, 53 of 71 potential and six of 24 treated, CD patients showed anti-TG2 mucosal deposits. Five of six positive treated CD patients had been on GFD for fewer than 6 years and were also positive for secreted anti-TG2. In treated patients, PTG/P31-43 was not able to induce secretion of anti-TG2 antibodies into culture medium. Measurement of anti-TG2 antibodies in biopsy supernatants proved to be more sensitive than detection by immunofluorescence to reveal their intestinal production. Intestinal antiTG2 antibodies titres correlated positively with the degree of mucosal damage and inversely with the duration of GFD.