Genetic testing: who should do the testing and what is the role of genetic testing in the setting of celiac disease?

Microscopic Colitis and Celiac Disease: Sharing More than a Diagnostic Overlap

Microscopic colitis (MC) is an emergent group of chronic inflammatory diseases of the colon, and celiac disease (CD) is a chronic gluten-induced immune-mediated enteropathy affecting the small bowel. We performed a narrative review to provide an overview regarding the relationship between both disorders, analyzing the most recent studies published at the epidemiological, clinical and pathophysiological levels. In fact, MC and CD are concomitantly prevalent in approximately 6% of the cases, mainly in the subset of refractory patients. Thus, physicians should screen refractory patients with CD against MC and vice versa. Both disorders share more than a simple epidemiological association, being multifactorial diseases involving innate and adaptive immune responses to known or unknown luminal factors based on a rather common genetic ground. Moreover, autoimmunity is a shared characteristic between the patients with MC and those with CD, with autoimmunity in the latter being quite well-established. Furthermore, CD and MC share some common clinical symptoms and risk factors and overlap with other gastrointestinal diseases, but some differences exist between both disorders. More studies are therefore needed to better understand the complex mechanisms involving the common pathogenetic ground contributing to the CD and MC epidemiological association.

Assessment of Novel Proteins Triggering Celiac Disease via Docking-Based Approach

Human leukocyte antigens (HLAs) are pivotal in antigen processing, presenting to CD4+ T cells, and are linked to autoimmune disease susceptibility. In celiac disease, HLA-DQ2.5 and HLA-DQ8.1 bind gluten peptides on APCs, some recognized by CD4+ T cells, prompting inflammation and tissue damage. While extensively studied experimentally, these alleles lack comprehensive in silico analysis. To explore peptide-HLA preferences, we used molecular docking on peptide libraries, deriving quantitative matrices (QMs) for evaluating amino acids at nine-residue peptide binding cores. Our findings tie specific residue preferences to peptide backbone conformations. Validating QMs on known binders and non-binders showed strong predictive power (89-94% accuracy). These QMs excel in screening protein libraries, even whole proteomes, notably reducing time and costs for celiac disease risk assessment in novel proteins. This computational approach aligns with European Food Safety Authority guidance, promising efficient screening for potential celiac disease triggers.

Relationship between gluten availability and celiac disease prevalence: A geo-epidemiologic systematic review

Celiac disease is a global disease requiring genetic susceptibility and gluten exposure to trigger immune-mediated enteropathy. The effect of the degree of gluten-containing grain availability on celiac disease prevalence is unknown. Our objective was to compare country-based gluten availability to celiac prevalence using a systematic literature review. We searched MEDLINE, Embase, Cochrane, and Scopus until May 2021. We included population-based serum screening with confirmatory testing (second serological study or small intestine biopsy) and excluded specific, high-risk, or referral populations. We determined country-specific gluten availability using the United Nations food balance for wheat, barley, and rye. Human leukocyte antigen (HLA) frequencies were obtained from allelefrequencies.net. The primary outcome was association between gluten-containing grain availability and celiac disease prevalence. Generalized linear mixed models method with Poisson's link was used for analysis. We identified 5641 articles and included 120 studies on 427 146 subjects from 41 countries. Celiac disease prevalence was 0-3.1%, median 0.75% (interquartile range 0.35, 1.22). Median wheat supply was 246 g/capita/day (interquartile range 214.8, 360.7). The risk ratio (RR) for wheat availability on celiac disease was 1.002 (95% confidence interval [CI]: 1.0001, 1.004, P = 0.036). A protective association was seen with barley, RR 0.973 (95% CI: 0.956, 0.99, P = 0.003), and rye, RR 0.989 (95% CI: 0.982, 0.997, P = 0.006). The RR for gross domestic product on celiac disease prevalence was 1.009 (95% CI: 1.005, 1.014, P < 0.001). The RR for HLA-DQ2 was 0.982 (95% CI: 0.979, 0.986, P < 0.001), and that for HLA-DQ8 was 0.957 (95% CI: 0.950, 0.964, P < 0.001). In this geo-epidemiologic study, gluten-containing grain availability showed mixed associations with celiac disease prevalence.

The Second Highest Prevalence of Celiac Disease Worldwide: Genetic and Metabolic Insights in Southern Brazilian Mennonites

Celiac disease (CD), despite its high morbidity, is an often-underdiagnosed autoimmune enteropathy. Using a modified version of the Brazilian questionnaire of the 2013 National Health Survey, we interviewed 604 Mennonites of Frisian/Flemish origin that have been isolated for 25 generations. A subgroup of 576 participants were screened for IgA autoantibodies in serum, and 391 participants were screened for HLA-DQ2.5/DQ8 subtypes. CD seroprevalence was 1:29 (3.48%, 95% CI = 2.16-5.27%) and biopsy-confirmed CD was 1:75 (1.32%, 95% CI = 0.57-2.59%), which is superior to the highest reported global prevalence (1:100). Half (10/21) of the patients did not suspect the disease. HLA-DQ2.5/DQ8 increased CD susceptibility (OR = 12.13 [95% CI = 1.56-94.20], p = 0.003). The HLA-DQ2.5 carrier frequency was higher in Mennonites than in Brazilians (p = 7 × 10^-6). HLA-DQ8 but not HLA-DQ2.5 carrier frequency differed among settlements (p = 0.007) and was higher than in Belgians, a Mennonite ancestral population (p = 1.8 × 10^-6), and higher than in Euro-Brazilians (p = 6.5 × 10^-6). The glutathione pathway, which prevents reactive oxygen species-causing bowel damage, was altered within the metabolic profiles of untreated CD patients. Those with lower serological positivity clustered with controls presenting close relatives with CD or rheumatoid arthritis. In conclusion, Mennonites have a high CD prevalence with a strong genetic component and altered glutathione metabolism that calls for urgent action to alleviate the burden of comorbidities due to late diagnosis.

Frontiers in Celiac Disease: Where Autoimmunity and Environment Meet

Celiac disease is a chronic, immune-mediated enteropathy driven by dietary gluten found in genetically susceptible hosts. It has a worldwide distribution, is one of the most common autoimmune disorders globally, and is the only autoimmune condition for which the trigger is known. Despite advances in characterizing mechanisms of disease, gaps in understanding of celiac disease pathogenesis remain. A "frontier" concept is considering what moves an HLA-DQ2 or DQ8-positive individual from asymptomatic gluten tolerance to celiac disease manifestation. In this arena, environmental triggers, including age at the time of initial gluten exposure, the occurrence of usual childhood viral infections, and microbiome alterations have emerged as key events in triggering the symptomatic disease. Pathologists play a major role in frontier aspects of celiac disease. This includes the discovery that duodenal mucosal histology in follow-up biopsies does not correlate with ongoing patient symptoms, antitissue transglutaminase antibody titers and diet adherence in celiac disease patients. Further, in light of recent evidence that the detection of monoclonal T-cell populations in formalin-fixed biopsies is not specific for type II refractory celiac disease, pathologists should resist performing such analyses until common causes of "apparent" refractoriness are excluded. The promise of therapies in celiac disease has led to clinical trials targeting many steps in the inflammatory cascade, which depend upon a pathologist's confirmation of the initial diagnosis and evaluation of responses to therapies. As pathologists continue to be active participants in celiac disease research, partnering with other stakeholders, we will continue to impact this important autoimmune disease.

Genome-Wide Association Study-Guided Exome Rare Variant Burden Analysis Identifies IL1R1 and CD3E as Potential Autoimmunity Risk Genes for Celiac Disease

Celiac disease (CeD) is a multifactorial autoimmune enteropathy characterized by the overactivation of the immune system in response to dietary gluten. The molecular etiology of CeD is still not well-understood. Therefore, this study aims to identify potential candidate genes involved in CeD pathogenesis by applying multilayered system biology approaches. Initially, we identified rare coding variants shared between the affected siblings in two rare Arab CeD families by whole-exome sequencing (WES). Then we used the STRING database to construct a protein network of rare variants and genome-wide association study (GWAS) loci to explore their molecular interactions in CeD. Furthermore, the hub genes identified based on network topology parameters were subjected to a series of computational validation analyses like pathway enrichment, gene expression, knockout mouse model, and variant pathogenicity predictions. Our findings have shown the absence of rare variants showing classical Mendelian inheritance in both families. However, interactome analysis of rare WES variants and GWAS loci has identified a total of 11 hub genes. The multidimensional computational analysis of hub genes has prioritized IL1R1 for family A and CD3E for family B as potential genes. These genes were connected to CeD pathogenesis pathways of T-cell selection, cytokine signaling, and adaptive immune response. Future multi-omics studies may uncover the roles of IL1R1 and CD3E in gluten sensitivity. The present investigation lays forth a novel approach integrating next-generation sequencing (NGS) of familial cases, GWAS, and computational analysis for solving the complex genetic architecture of CeD.

Molecular Biomarkers for Celiac Disease: Past, Present and Future

Celiac disease (CeD) is a complex immune-mediated disorder that is triggered by dietary gluten in genetically predisposed individuals. CeD is characterized by inflammation and villous atrophy of the small intestine, which can lead to gastrointestinal complaints, malnutrition, and malignancies. Currently, diagnosis of CeD relies on serology (antibodies against transglutaminase and endomysium) and small-intestinal biopsies. Since small-intestinal biopsies require invasive upper-endoscopy, and serology cannot predict CeD in an early stage or be used for monitoring disease after initiation of a gluten-free diet, the search for non-invasive biomarkers is ongoing. Here, we summarize current and up-and-coming non-invasive biomarkers that may be able to predict, diagnose, and monitor the progression of CeD. We further discuss how current and emerging techniques, such as (single-cell) transcriptomics and genomics, can be used to uncover the pathophysiology of CeD and identify non-invasive biomarkers.

Beyond the HLA Genes in Gluten-Related Disorders

Most common food grains contain gluten proteins and can cause adverse medical conditions generally known as gluten-related disorders. Celiac disease is an immune-mediated enteropathy triggered by gluten in individuals carrying a specific genetic make-up. The presence of the human leukocyte antigens (HLA)-DQ2 and HLA-DQ8 haplotypes together with gluten intake is a necessary, although not sufficient, condition, to develop celiac disease. Fine mapping of the human genome has revealed numerous genetic variants important in the development of this disease. Most of the genetic variants are small nucleotide polymorphisms located within promoters and transcriptional enhancer sequences. Their importance is underlined by an increased risk in DQ2/DQ8 carriers who also have these non-HLA alleles. In addition, several immune-mediated diseases share susceptibility loci with celiac disease, shedding light on the reasons for co-occurrence between these diseases. Finally, most of the genes potentially involved in celiac disease by fine genetic mapping of non-HLA loci were confirmed in gene expression studies. In contrast to celiac disease, very little is known about the genetic make-up of non-celiac wheat sensitivity (NCWS), a clinically defined pathology that shares symptoms and gluten dependence with the celiac disease. We recently identified differentially expressed genes and miRNAs in the intestinal mucosa of these patients. Remarkably, the differentially expressed genes were long non-coding RNAs possibly involved in the regulation of cell functions. Thus, we can speculate that important aspects of these diseases depend on alteration of regulatory genetic circuits. Furthermore, our finding suggests that innate immune response is involved in the pathogenic mechanism of NCWS. This review is intended to convey the idea that in order to fully understand celiac disease and its relationship with other gluten-related disorders, it is worth learning more about non-HLA variants.

Celiac disease susceptibility: The genome and beyond

Celiac Disease (CeD) is an immune-mediated complex disease that is triggered by the ingestion of gluten and develops in genetically susceptible individuals. It has been known for a long time that the Human Leucocyte Antigen (HLA) molecules DQ2 and DQ8 are necessary, although not sufficient, for the disease development, and therefore other susceptibility genes and (epi)genetic events must participate in CeD pathogenesis. The advances in Genomics during the last 15 years have made CeD one of the immune-related disorders with the best-characterized genetic component. In the present work, we will first review the main Genome-Wide Association Studies (GWAS) carried out in the disorder, and emphasize post-GWAS discoveries, including diverse integrative strategies, SNP prioritization approaches, and insights into the Microbiome through the host Genomics. Second, we will explore CeD-related Epigenetics and Epigenomics, mostly focusing on the emerging knowledge of the celiac methylome, and the vast but yet under-explored non-coding RNA (ncRNA) landscape. We conclude that much has been done in the field although there are still completely unvisited areas in the post-Genomics of CeD. Chromatin conformation and accessibility, and Epitranscriptomics are promising domains that need to be unveiled to complete the big picture of the celiac Genome.

Primary Humoral Immune Deficiencies: Overlooked Mimickers of Chronic Immune-Mediated Gastrointestinal Diseases in Adults

In recent years, the incidence of immune-mediated gastrointestinal disorders, including celiac disease (CeD) and inflammatory bowel disease (IBD), is increasingly growing worldwide. This generates a need to elucidate the conditions that may compromise the diagnosis and treatment of such gastrointestinal disorders. It is well established that primary immunodeficiencies (PIDs) exhibit gastrointestinal manifestations and mimic other diseases, including CeD and IBD. PIDs are often considered pediatric ailments, whereas between 25 and 45% of PIDs are diagnosed in adults. The most common PIDs in adults are the selective immunoglobulin A deficiency (SIgAD) and the common variable immunodeficiency (CVID). A trend to autoimmunity occurs, while gastrointestinal disorders are common in both diseases. Besides, the occurrence of CeD and IBD in SIgAD/CVID patients is significantly higher than in the general population. However, some differences concerning diagnostics and management between enteropathy/colitis in PIDs, as compared to idiopathic forms of CeD/IBD, have been described. There is an ongoing discussion whether CeD and IBD in CVID patients should be considered a true CeD and IBD or just CeD-like and IBD-like diseases. This review addresses the current state of the art of the most common primary immunodeficiencies in adults and co-occurring CeD and IBD.

Celiac disease-on-chip: Modeling a multifactorial disease in vitro

Conventional model systems cannot fully recapitulate the multifactorial character of complex diseases like celiac disease (CeD), a common chronic intestinal disorder in which many different genetic risk factors interact with environmental factors such as dietary gluten. However, by combining recently developed human induced pluripotent stem cell (hiPSC) technology and organ-on-chip technology, in vitro intestine-on-chip systems can now be developed that integrate the genetic background of complex diseases, the different interacting cell types involved in disease pathology, and the modulating environmental factors such as gluten and the gut microbiome. The hiPSCs that are the basis of these systems can be generated from both diseased and healthy individuals, which means they can be stratified based on their load of genetic risk factors. A CeD-on-chip model system has great potential to improve our understanding of disease etiology and accelerate the development of novel treatments and preventive therapies in CeD and other complex diseases.

Genetic susceptibilty and celiac disease: what role do HLA haplotypes play?

Celiac disease is a chronic immune-mediated enteropathy triggered by exposure to dietary gluten in genetically predisposed individuals. Many genes involved in the pathogenesis have been identified and a crucial role is known to be played by the Human Leukocyte Antigen (HLA) system. The main determinants for genetic susceptibility are HLA-DQA1 and HLA-DQB1 genes encoding for HLA-DQ2 and HLA-DQ8 molecules, carried by almost all patients affected. However, since HLA-DQ2 and HLA-DQ8 heterodimers explain almost 40% of the disease heritability, HLA typing should not be applied in diagnosis, but exclusively to clarify uncertain diagnoses, considering its negative predictive value. (www.actabiomedica.it)

Celiac disease in non-clinical populations of Japan

BACKGROUND

Celiac disease is a chronic autoimmune enteropathy caused by gluten ingestion. While its prevalence in Western countries is reported to be as high as 1%, the prevalence has not been evaluated in a large-scale study of a Japanese population. The aim of our study was to clarify the possible presence of celiac disease in a Japanese non-clinical population as well as in patients showing symptoms suggestive of the disease.

METHODS

Serum samples were collected from 2008 non-clinical adults and 47 patients with chronic unexplained abdominal symptoms between April 2014 and June 2016. The anti-tissue transglutaminase (TTG) immunoglobulin A antibody titer was determined as a screening test for celiac disease in all subjects, and individuals with a value of >2 U/mL subsequently underwent testing for the presence of serum endomysial IgA antibody (EMA) as confirmation. Those testing positive for EMA or with a high concentration (>10 U/mL) of TTG were further investigated by histopathological examinations of duodenal mucosal biopsy specimens and HLA typing tests.

RESULTS

Of the 2008 non-clinical adults from whom serum samples were collected, 161 tested positive for TTG, and all tested negative for EMA. Four subjects who had a high TTG titer were invited to undergo confirmatory testing, and the histopathological results confirmed the presence of celiac disease in only a single case (0.05%). Of the 47 symptomatic patients, one (2.1%) was found to have a high TTG titer and was diagnosed with celiac disease based on duodenal histopathological findings.

CONCLUSION

The presence of celiac disease in a non-clinical Japanese population was low at 0.05% and was rarely found in patients with unexplained chronic abdominal symptoms.

The potential usefulness of human leukocyte antigen typing for celiac disease screening: A systematic review and meta-analysis

BACKGROUND AND AIM

The presence of specific human leukocyte antigen-DQ2 and DQ8 seems to be necessary for celiac disease development, but the real contribution of its typing for screening is still uncertain. We aim to conduct a systematic review and meta-analysis of the diagnostic performance of human leukocyte antigen typing tests for celiac disease screening.

METHODS

Systematic review of published studies assessing accuracy of human leukocyte antigen DQ2 and DQ8 typing for the detection of celiac disease were selected. MEDLINE and EMBASE were searched from 1st January 2004 until 31st December 2013. Two independent researchers carried out selection and classification of studies, data extraction and analysis. Meta-analysis combining sensitivities, specificities and likelihood ratios of HLA-DQ2 and DQ8 for the diagnosis of celiac disease were carried out.

RESULTS

6 studies including 1303 individuals were finally evaluated. Pooled sensitivity was 98% (95% confidence interval: 97-99). Overall specificity was 45% (95% confidence interval: 41-48). Regarding specificity, studies were heterogeneous and a subgroup analysis was done according to the type of population included. Overall negative likelihood ratio was 0.05 (0.03-0.09).

CONCLUSIONS

Due to its great sensitivity and low negative likelihood ratio, human leukocyte antigen-DQ2/DQ8 typing would be an appropriate test for ruling out celiac disease in the general population suffering related symptoms, and even more in at risk population.

Presence of DQ2.2 Associated with DQ2.5 Increases the Risk for Celiac Disease

Background. Celiac disease (CD) is a genetically determined immune-mediated disorder in which gluten immunogenic peptides are presented to CD4 T cells by HLA-DQ2.5, DQ8, DQ2.2, and their combinations. Our aim is to establish a risk gradient for celiac disease based on HLA-DQ profile in a brazilian representative population and the relevance of DQ2.2 in celiac disease development. Materials and Methods. 237 celiac patients and 237 controls (both groups with 164 females and 73 males) were included. All samples were tested for the presence of predisposing HLA-DQ alleles using the PCR-SSP method. Results were considered significant when p < 0.05. Disease risk was expressed as 1 : N for each HLA-DQ category described at this study. Results. DQ2.5 and/or DQ8 were detected in 224 celiac patients (94.5%) and 84 controls (35.4%). Eight celiac patients (3.4%) and 38 controls (16%) disclosed only DQ2.2. Even though DQ2.2 (β2/β2 or β2/x) showed a low CD risk of 1 : 251 and 1 : 550, respectively, the genotype DQ2.5/DQ2.2 (β2/β2) showed high CD risk of 1 : 10 (p < 0.0001). The disease risk gradient ranged from 1 : 3014 to 1 : 7. Conclusion. Our study allowed the determination of a risk gradient for celiac disease development in at-risk population, showing that DQ2.2 variant was relevant when associated with DQ2.5.

Prevalence of celiac disease in first-degree relative of children in Sistan and Baluchestan province (Iran)

OBJECTIVE

To determine the prevalence of elevated antibodies and histological changes of celiac disease (CD) on intestinal biopsies among first-degree relatives (FDR) of Iranian children with known CD and to describe the characteristics of the affected FDR.

METHOD

The FDR of 119 patients with CD in Iran were tested for tissue transglutaminase (TTG) and immunoglobulin A (IgA) levels. Upper endoscopy and duodenal biopsy were recommended to those with elevated TTG-IgA antibodies. The characteristics and clinical features of all CD patients were recorded.

RESULTS

Altogether 480 FDR (52.7% females) participated in the study, of whom 63 had an elevated TTG-IgA and 44 consented to undergo endoscopy with biopsies. Histology revealed Marsh 0 in six, Marsh I in seven, Marsh II in four and Marsh III in 27. Most of those with Marsh II or III changes were siblings (26/31). The prevalence of TTG-IgA positivity among FDR was 13.1% and for biopsy-confirmed CD (Marsh II and III) it was 6.5%. Most FDR with CD had symptoms, with the most common being abdominal pain (45.0%), followed by musculoskeletal pain (35.5%) and constipation (25.8%). FDR with Marsh III changes had significantly higher levels of TTG-IgA.

CONCLUSIONS

The prevalence of CD in FDR in Iran is much higher compared with the general population (6.5% vs 0.5-0.6%). Testing should be considered for all FDR of Iranian patients with known CD and in particular in symptomatic cases.

Understanding Celiac Disease by Genomics

Celiac disease (CeD) is a complex immune-mediated disease. Genetic studies have implicated 43 predisposing loci that collectively explain some 50% of the genetic variance in CeD. More than ∼90% of CeD-associated single nucleotide polymorphisms (SNPs) localize to the non-coding genome, which we need to better understand to translate genetic knowledge into clinical practice. New genomic technologies and resources are permitting a systematic analysis of the functional elements in the non-coding part of the genome. Here we explain how investigating the regulatory and epigenomic landscape will help to pinpoint the cell types involved in CeD, and the driver genes and gene regulatory networks that are affected by CeD-associated SNPs.

Clinical relevance and cost-effectiveness of HLA genotyping in children with Type 1 diabetes mellitus in screening for coeliac disease in the Netherlands

AIMS

To investigate the clinical relevance and cost-effectiveness of human leukocyte antigen (HLA)-genotyping in the Netherlands as a screening tool for the development of coeliac disease in children with Type 1 diabetes mellitus.

METHODS

A retrospective analysis was performed in 110 children with Type 1 diabetes mellitus diagnosed between January 1996 and January 2013. All children were screened for coeliac disease using coeliac disease-specific antibodies and HLA genotyping was performed in all children.

RESULTS

One hundred and ten children were screened for coeliac disease, and coeliac disease could be confirmed in seven. Eighty-six per cent of the children with Type 1 diabetes mellitus had one of the variants of HLA-DQ2.5 and DQ8. HLA genotypes observed in children with Type 1 diabetes mellitus children and coeliac disease were heterozygote DQ2.5, homozygote DQ2.5 and heterozygote DQ2.5/DQ8. HLA genotyping in coeliac disease screening in children with Type 1 diabetes mellitus is more expensive than screening for coeliac disease with antibodies alone (€326 vs. €182 per child).

CONCLUSIONS

The risk of coeliac disease development in children with Type 1 diabetes mellitus is increased when they are heterozygote DQ2.5/DQ8, homozygote or heterozygote DQ2.5. The implementation of HLA genotyping as a first-line screening tool has to be reconsidered because it is not distinctive or cost-effective.

Genetics and celiac disease: the importance of screening

The prevalence of celiac disease (CD) is increasing. Despite an increased awareness and an improvement in diagnostic testing, the majority of individuals with CD remain undiagnosed. Currently, genetic testing in screening for CD is used only to exclude a diagnosis or reinforce a strong clinical suspicion. In this paper, we review the most current literature regarding genetic testing in CD. In response to important data revealing that an individual's HLA haplotype is one of the strongest known predictors of CD, we propose genetic screening for at-risk infants to stratify individuals based on genetic risk to ultimately create genetic specific screening algorithms.

Overview of biomarkers for diagnosis and monitoring of celiac disease

Among the adverse reactions caused by wheat, celiac disease (CD) is the longest studied and best-known pathology. The more recently defined non-celiac gluten sensitivity (NCGS) presents with symptoms which are often indistinguishable from CD. Diagnosis of CD is based on serologic, molecular, and bioptic testing. The IgA anti-transglutaminase (tTG) test is considered highly important, as it shows high sensitivity and specificity and its levels correlate to the degree of intestinal damage. Small bowel biopsy can be avoided in symptomatic patients with IgA anti-tTG levels above 10× the manufacturer's cut-off. Recently, tests of anti-deamidated peptides of gliadin (DGP) have replaced classic anti-native gliadin (AGA) tests. DGP assays have a considerably higher diagnostic accuracy than AGA assays, especially in the IgG class, and can replace anti-tTG tests in patients with selective IgA deficiency. The combination of IgG anti-DGP plus IgA anti-tTG assays show greater sensitivity than a single test, with very high specificity. EMA tests have great diagnostic accuracy but are not recommended by all the latest guidelines because they are observer dependent. Biopsy must still be considered the gold standard for CD diagnosis. HLA-DQ genotyping can be used to screen asymptomatic children and in cases of histology/serology disagreement. About half of NCGS patients are DQ2 positive and have IgG AGA. To diagnose NCGS, first CD and wheat allergy must be excluded; then the wheat dependence of symptoms must be verified by a gluten-free diet and subsequent gluten challenge.

Clinical utility of celiac disease-associated HLA testing

BACKGROUND

Negative predictive value (NPV) of celiac disease (CD)-related human leukocyte antigens (HLA) DQ2 and DQ8 approaches 100 % in individual patients. However, studies evaluating its exclusionary utility in patient groups are lacking.

AIM

We aim to assess the performance of HLA testing when applied to patient groups with varying characteristics and propose evidence-based recommendations for its clinical use.

METHODS

Demographic and clinical information was recorded in patients undergoing HLA testing. Using predetermined criteria, patients were classified as CD, non-CD, or indeterminate. Diagnostic yield of HLA testing was defined as the percentage of patients in whom CD could be excluded based on negative HLA test.

RESULTS

Two hundred and fifty-six patients underwent testing for CD-related HLA DQ2 and DQ8. 102 (100 non-CD, 2 CD) patients tested HLA negative for a 98 % NPV and 39 % diagnostic yield. Diagnostic yield was highest (60 %) in patients with intraepithelial lymphocytosis plus normal IgA tissue transglutaminase antibody (IgA-tTG) and lowest in patients with positive IgA-tTG plus villous atrophy (0 %). CD was diagnosed in two HLA-negative patients, who carried half of DQ2.5 trans genotype.

CONCLUSIONS

Diagnostic yield of CD-related HLA testing varies widely depending on clinical indication. HLA testing is a practical and valuable test for most patients in whom initial evaluation for CD is inconclusive. A negative HLA result usually obviates the need for further celiac testing including endoscopy and gluten challenge. Rarely, in patients reported as HLA negative, half of HLA DQ2.5 (cis or trans) is sufficient for development of CD.

Palaeodiet reconstruction in a woman with probable celiac disease: a stable isotope analysis of bone remains from the archaeological site of Cosa (Italy)

Stable isotope analysis in the reconstruction of human palaeodiets can yield clues to early human subsistence strategies, origins and history of farming and pastoralist societies, and intra- and intergroup social differentiation. In the last 10 years, the method has been extended to the pathological investigation. Stable isotope analysis to better understand a diet-related disease: celiac disease in ancient human bones was carried out. To do this, we analyzed the nitrogen and carbon isotopic composition of human (n = 37) and faunal (n = 8) bone remains from the archaeological site of Cosa at Ansedonia, on the Tyrrhenian coast near Orbetello (Tuscany), including the skeletal remains of a young woman (late 1st century-early 2nd century Common Era [CE]) with morphological and genetic features suggestive of celiac disease. We compared the young woman's isotopic data with those of other individuals recovered at the same site but from two later time periods (6th century CE; 11-12th century CE) and with literature data from other Italian archaeological sites dating to the same period. Her collagen δ(13) C and δ(15) N values differed from those of the samples at the same site, and from most but not all of the contemporary sites. Although the woman's diet appears distinct, chronic malnutrition resulting from severe malabsorption of essential nutrients due to celiac disease may have affected the isotopic composition of her bone collagen.

Molecular diagnosis of celiac disease: are we there yet?

BACKGROUND

Celiac disease (CD) is a complex genetic disorder of the small intestine resulting from aberrant cellular responses to gluten peptides. It may affect as much as 1% of the Western population and the only treatment is a lifelong gluten-free diet. Allelic variants of the HLA-DQ locus, coding for the HLA-DQ2 and HLA-DQ8 molecules, contribute to ∼ 40% of CD etiology, whereas other genes, such as MYO9B, CTLA4, IL2, IL21, PARD3 and MAGI2, have only a modest effect. Most of these genes have shown varied association among different populations and an overlap with other autoimmune or inflammatory disorders, indicating that such disorders may share common pathways.

OBJECTIVES

In this review, a molecular approach into diagnostics of celiac disease is shown.

CONCLUSIONS

Genome-wide association studies will allow more genes to be identified, and knowing how risk variants combine will help to predict better the risk for the individual. HLA typing can already be used to identify high-risk individuals.

HLA-DQA1 and HLA-DQB1 in Celiac disease predisposition: practical implications of the HLA molecular typing

Celiac disease (CD) is a multifactorial disorder with an estimated prevalence in Europe and USA of 1:100 and a female:male ratio of approximately 2:1. The disorder has a multifactorial etiology in which the triggering environmental factor, the gluten, and the main genetic factors, Human Leukocyte Antigen (HLA)-DQA1 and HLA-DQB1 loci, are well known. About 90-95% of CD patients carry DQ2.5 heterodimers, encoded by DQA1*05 and DQB1*02 alleles both in cis or in trans configuration, and DQ8 molecules, encoded by DQB1*03:02 generally in combination with DQA1*03 variant. Less frequently, CD occurs in individuals positive for the DQ2.x heterodimers (DQA1≠*05 and DQB1*02) and very rarely in patients negative for these DQ predisposing markers. HLA molecular typing for Celiac disease is, therefore, a genetic test with a negative predictive value. Nevertheless, it is an important tool able to discriminate individuals genetically susceptible to CD, especially in at-risk groups such as first-degree relatives (parents, siblings and offspring) of patients and in presence of autoimmune conditions (type 1 diabetes, thyroiditis, multiple sclerosis) or specific genetic disorders (Down, Turner or Williams syndromes).

HLA-DQB1 Haplotypes and their Relation to Oral Signs Linked to Celiac Disease Diagnosis

Objectives:

Celiac disease (CD) is an autoimmune disorder that can be divided into typical and atypical forms. Atypical forms can show extraintestinal manifestations among which oral signs are very frequent. Considering that the pathogenesis of CD is related to a positivity to specific HLA-DQB1 haplotypes, we tested whether the presence of the HLA-DQB1*02 allele could be a hypothetical cause of the development of oral manifestations.

Subjects and Methods:

For this study was been examined the oral condition of 98 Sardinian patients, all affected by CD and all on a gluten-free diet for at least 1 year. Then was been determined each patient’s HLA-DQB1 haplotype and compared these results with clinical information.

Results:

The statistical analysis evidenced that the absence of the HLA-DQB1*02 allele predisposes to oral manifestations such as dental enamel defects (DED) and recurrent aphthous stomatitis (RAS) (Pvalue=5.98x10^-05, OR = 0.23, CI: (0.10 - 0.45) per each copy of the HLA allele).

Conclusions:

These results showed that the presence of the HLA-DQB1*02 allele influences the development of oral signs in a dose-dependent manner and also how the HLA haplotype connected to oral signs could have a fundamental role for the diagnosis of atypical forms of CD.

Selective IgA deficiency in autoimmune diseases

Selective immunoglobulin A deficiency (IgAD) is the most common primary immunodeficiency in Caucasians. It has previously been suggested to be associated with a variety of concomitant autoimmune diseases. In this review, we present data on the prevalence of IgAD in patients with Graves disease (GD), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), celiac disease (CD), myasthenia gravis (MG) and rheumatoid arthritis (RA) on the basis of both our own recent large-scale screening results and literature data. Genetic factors are important for the development of both IgAD and various autoimmune disorders, including GD, SLE, T1D, CD, MG and RA, and a strong association with the major histocompatibility complex (MHC) region has been reported. In addition, non-MHC genes, such as interferon-induced helicase 1 (IFIH1) and c-type lectin domain family 16, member A (CLEC16A), are also associated with the development of IgAD and some of the above diseases. This indicates a possible common genetic background. In this review, we present suggestive evidence for a shared genetic predisposition between these disorders.

Mild enteropathy as a cause of iron-deficiency anaemia of previously unknown origin

BACKGROUND AND AIMS

We assessed whether mild enteropathy with negative coeliac serology may be gluten-dependent, and a cause of iron-deficiency anaemia. In cases not responding to gluten-free diet, the role of Helicobacter pylori infection was evaluated.

METHODS

55 consecutive unexplained iron-deficiency anaemia patients were included. In all of them we performed: HLA-DQ2/DQ8 coeliac genetic study, distal duodenum biopsies, and tests to assess H. pylori infection. A gluten-free diet or H. pylori eradication was used as indicated. Final diagnosis was established based on response to specific therapy after a 12-month follow-up period.

RESULTS

Histological findings were: (1) group A (positive genetics): 21 Marsh I, 2 Marsh IIIA, 12 normal; (2) group B (negative genetics): 16 Marsh I, 4 normal. Final diagnosis of anaemia in patients with enteropathy were: group A, gluten-sensitive enteropathy, 45%; H. pylori infection, 20%; gluten-sensitive enteropathy plus H. pylori, 10%; other, 10%; unknown, 15%; group B, gluten-sensitive enteropathy, 10%; H. pylori infection, 0% (1 non-eradicated case, 10%); non-steroidal anti-inflammatory drug intake, 20%; other, 20%; unknown, 40% (p=0.033).

CONCLUSIONS

Mild enteropathy is frequent in patients with unexplained iron-deficiency anaemia and negative coeliac serology. Most cases are secondary to either gluten-sensitive enteropathy or H. pylori infection, or both; however, there is also a substantial number of patients without a definitive diagnosis.

[Clinical manifestations of adult celiac disease]

Celiac disease is an enteropathy due to gluten intake in genetically predisposed persons (HLA DQ2/DQ8). Celiac disease occurs in adults and children at rates approaching 1% of population in Europe and USA. Celiac disease is extremely various and anaemia, oral aphthous stomatis, amenorrhea or articular symptoms may be the only revealing symptoms. Diagnosis releases on evidence of histological villous atrophy in proximal small bowel and presence of specific serum antibodies. Treatment relies on eviction of gluten. Gluten free diet allows prevention of malignant complications such as small bowel adenocarcinoma and lymphoma and osteopenia. The main cause of resistance to gluten free diet is its bad observance. On the contrary, serious complications of celiac disease, such as clonal refractory celiac sprue and intestinal T-cell lymphoma need to be screen.

Duodenal villous atrophy: a cause of chronic diarrhea after solid-organ transplantation

Persistent diarrhea is commonly observed after solid organ transplantation (SOT). A few cases of mycophenolate mofetil (MMF)-induced duodenal villous atrophy (DVA) have been previously reported in kidney-transplant patients with chronic diarrhea. Herein, we report on the incidence and characteristics of DVA in SOT patients with chronic diarrhea. One hundred thirty-two SOT patients with chronic diarrhea underwent an oesophago-gastroduodenoscopy (OGD) and a duodenal biopsy after classical causes of diarrhea have been ruled out. DVA was diagnosed in 21 patients (15.9%). It was attributed to mycophenolic acid (MPA) therapy in 18 patients (85.7%) (MMF [n = 14] and enteric-coated mycophenolate sodium [n = 4]). MPA withdrawal or dose reduction resulted in diarrhea cessation. The incidence of DVA was significantly higher in patients with chronic diarrhea receiving MPA compared to those who did not (24.6% vs. 5.1%, p = 0.003). DVA was attributed to a Giardia lamblia parasitic infection in two patients (9.5%) and the remaining case was attributed to azathioprine. In these three patients, diarrhea ceased after metronidazole therapy or azathioprine dose reduction. In conclusion, DVA is a frequent cause of chronic diarrhea in SOT recipients. MPA therapy is the most frequent cause of DVA. An OGD should be proposed to all transplant recipients who present with persistent diarrhea.

Association of Budd-Chiari syndrome and celiac disease

BACKGROUND AND AIMS

An association between Budd-Chiari syndrome (BCS) and celiac disease (CD) is uncommon. The aims of our study were to investigate the etiology of BCS and to search for a particular HLA Ag pattern among patients.

PATIENTS AND METHODS

BCS diagnosis was based on Doppler ultrasound and CD diagnosis on duodenal biopsy, transglutaminase (TGAb) and gliadin antibodies (GAb). Patients were screened for prothrombotic disorders and seven had a PCR-SSO test for HLA genotypes. Patients were treated with anticoagulants and gluten-free diet.

RESULTS

Nine patients were included; mean age 27 years (20-42); sex ratio (F/M) 2; mean follow-up duration 31 months (6-54). All patients had endoscopic and histological features of CD. GAb/TGAb were found in 78 % (n=7). Ag HLA found were HLA DQβ1(*)02 (n=6) and DQβ1(*)03 (n=3). Prothrombotic conditions identified were latent myeloproliferative disorder (n=1), protein C deficiency (n=1), probable factor V Leiden (n=1) and oral contraceptive use (n=1). No prothrombotic state could be identified in the five other patients.

CONCLUSION

The BCS-CD association is relatively frequent in our country. Underlying prothrombotic conditions were absent in more than 50 % of cases, suggesting CD plays a role in the occurrence of thrombosis. HLA alleles found are strongly associated with CD, without any particular pattern for the BCS-CD association.

Gluten-sensitive enteropathy (celiac disease): controversies in diagnosis and classification

CONTEXT

Celiac disease, or gluten-sensitive enteropathy, is a chronic inflammatory disorder of the small intestine characterized by malabsorption after ingestion of gluten in individuals with a certain genetic background. Clinical presentation can vary from full-blown malabsorption to subtle and atypical symptoms. Diagnosis currently relies on clinicopathologic studies including mucosal biopsy, serologic tests, and the effects of a diet free of gluten on the symptoms. Mucosal pathologic features are also variable, ranging from mild abnormalities, including intraepithelial lymphocytosis, to completely flat mucosa. Since patients with minimal histologic lesion of intraepithelial lymphocytosis often present with normal serologic findings, biopsy diagnosis becomes more important for identifying such individuals. Classification of mucosal pathology in gluten-sensitive enteropathy has been a subject of controversy among pathologists and needs to be revised according to the current understanding of the disease.

OBJECTIVES

To highlight the variations in clinical and pathologic presentation of gluten-sensitive enteropathy, to emphasize the importance of small-intestinal biopsy evaluation in the diagnosis, and to propose a new classification of mucosal pathology in gluten-sensitive enteropathy, in an effort to overcome the problems related to the classification systems currently available.

DATA SOURCES

A review of the literature on clinicopathologic features and the morphologic spectrum of gluten-sensitive enteropathy is presented.

CONCLUSIONS

Considering that there are many entities in the differential diagnosis of gluten-sensitive enteropathy, because of the varied clinicopathologic spectrum of the disease, diagnosis depends on good clinicopathologic communication. The classification that is presented in this review is a simple and practical approach to improve clinicopathologic correlation in gluten-sensitive enteropathy.

[Celiac disease]

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

Prevalence, human leukocyte antigen typing and strategy for screening among Asian first-degree relatives of children with celiac disease

BACKGROUND AND AIM

Data on prevalence, human leukocyte antigen (HLA) typing and small bowel histology among first-degree relatives of subjects with celiac disease (CD) is scarce. This prospective study evaluated the prevalence and role of HLA DQ2/8 testing in screening of first-degree relatives of children with CD.

METHODS

Thirty confirmed children with CD and 91/94 first-degree relatives (parents and siblings) were enrolled. HLA DQ2/8 testing was carried out in all index CD cases. Clinical evaluation with a questionnaire, total serum immunoglobulin A (IgA), human IgA-tissue transglutaminase (IgA-tTGA) and HLA DQ2/8 testing was carried out in all first-degree relatives. Subjects who were positive for IgA-tTGA were recommended endoscopic duodenal biopsy to document histological changes of CD.

RESULTS

Nine first-degree relatives were positive for IgA-tTGA, seven underwent duodenal biopsy and four subjects had Marsh IIIa changes suggestive of CD. The prevalence of histologically confirmed CD in first-degree relatives was 4.4%. The prevalence of potential CD was 9.8%. IgA-tTGA-positive subjects (4/9) were significantly more often symptomatic than IgA-tTGA-negative first-degree relatives (2/82). Twenty-nine (96.6%) index cases of CD and all IgA-tTGA-positive first-degree relatives were positive for HLA DQ2. None of the index CD cases or first-degree relatives were HLA DQ8-positive. A total of 85% of the first-degree relatives were positive for HLA DQ2 and thus at risk of developing CD.

CONCLUSIONS

In this first Asian study on a limited number of families of children with CD, 4.4% of the first-degree relatives had CD. Only 15% of the first-degree relatives were negative for HLA DQ2/DQ8. Initial evaluation with HLA and serology followed by only serial serology in HLA-positive relatives is recommended.

Stratifying risk for celiac disease in a large at-risk United States population by using HLA alleles

BACKGROUND & AIMS

Susceptibility to celiac disease (CD) is related to HLA-DQ2 and DQ8 alleles and the heterodimers they encode. The objective of this study was to stratify risk for CD on the basis of HLA-DQ genotype.

METHODS

DNA from 10,191 subjects who are at risk for CD was analyzed for HLA-DQ haplotypes. Individuals with CD were identified as those who tested positive for anti-endomysial immunoglobulin A (EMA+) in an immunofluorescence assay.

RESULTS

Samples homozygous for DQ2.5 (HLA-DQA1 05-DQB1 02) or DQ2.2/DQ2.5 (HLA-DQA1 05-DQB1 02 and HLA-DQA1 0201-DQB1 02) comprised 5.38% of the total; 28.28% of these were EMA+ (95% confidence interval [CI], 24.55-32.26). Of the samples that were DQ2.5 heterozygous (HLA-DQA1 05-DQB1 02); 9.09% were EMA+ (95% CI, 7.82-10.51). Among samples in which HLA-DQ8 (HLA-DQA1 03-DQB1 0302) was detected, 8.42% of homozygotes (95% CI, 3.71-15.92) and 2.11% of heterozygotes (95% CI, 1.43-3.00) were EMA+. Samples with DQ2.2/DQ8 or DQ2.5/DQ8 comprised 5.08% of the total, and 11.78% of these were EMA+ (95% CI, 9.13-14.87). HLA-DQ2 and HLA-DQ8 were absent in 4283 samples (42.03% of the total); 0.16% of these samples were EMA+ (95% CI, 0.07-0.34).

CONCLUSIONS

High-resolution, sequence-specific oligonucleotide probe typing with 35 DQA1-specific and 37 DQB1-specific probes of DNA from more than 10,000 subjects was used to stratify risk of CD in an at-risk U.S. population. DQ2 homozygosity (DQ2.5/DQ2.2+2.5) increased risk for CD, estimated by the rate of EMA positivity, compared with the entire sample population and other DQ genotypes. These data suggest a quantitative relationship between the type/proportion of DQ heterodimers and the risk of CD and identify potential immunotherapeutic targets.

Inflammatory Disease Processes and Interactions with Nutrition

Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain ω-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (ω-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.

HLA and autoimmune digestive disease: a clinically oriented review for gastroenterologists

OBJECTIVES

The human leukocyte antigen (HLA) system includes genes involved in graft-vs-host rejection and in immune response. The discovery that HLAs are associated with several diseases led to appealing developments both in basic biomedical research and in clinical medicine, and offered the opportunity to improve the understanding of pathogenesis and classification of diseases, as well as to provide diagnostic and prognostic indicators. The aim of this article is to review the association between HLA alleles and autoimmune digestive disease and its current relationship with modern HLA nomenclature and clinical practice.

METHODS

Articles dealing with the association between HLAs and autoimmune digestive disease (including celiac disease, inflammatory bowel disease, autoimmune hepatitis, sclerosing cholangitis and primary biliary cirrhosis) were searched for using Pubmed and SCOPUS databases from earliest records to January 2008.

RESULTS

The review has provided two sections. In the first, we explain the basic principles of HLA structure, function, and nomenclature, as an introduction to the second section, which describes current associations between HLA alleles and digestive diseases. The clinical implications of each HLA association are critically discussed. Actually, a clinical role for HLA typing is suggested for only a few conditions, e.g., celiac disease.

CONCLUSIONS

The knowledge of current HLA nomenclature and of its association with some digestive diseases such as celiac disease can be useful in clinical practice for diagnostic and prognostic purposes. This can avoid improper HLA typing as well as stressing the need for further studies on other possible clinical applications.

A rapid and sensitive method to detect specific human lymphocyte antigen (HLA) class II alleles associated with celiac disease

BACKGROUND

Celiac disease (CD) is a complex disorder triggered by gluten affecting genetically predisposed individuals. More than 90% of patients carry human lymphocyte antigen (HLA)-DQ2 (DQA1*05, DQB1*02) and/or HLA-DQ8 (DQA1*03, DQB1*0302). We propose the use of the DQ-CD Typing kit that allows identification of the HLA class II alleles (DQA1*0201,*03,*05, DQB1*02,*0302, DRB1*03,*04,*07) selected to be informative in the CD risk evaluation and of a second kit, namely DQ-CD Zygosis, for DQB1*02 homozygosity determination.

METHODS

The study was performed on a cohort of 100 individuals previously HLA typed with commercial kits. Fresh blood or previously extracted DNA was amplified in a unique PCR program using allele-specific primers and visualized on agarose gel.

RESULTS

DNA amplification yielded strong and clear products without non specific signals or ghost bands. All the samples showed the expected alleles in accordance with the previous HLA typing.

CONCLUSIONS

The DQ-CD Typing and Zygosis kits are fast, simple, economical and accurate tools that can be used to determinate the HLA-DQ2/DQ8 status in laboratory practice addressed for the diagnosis of CD. Molecular HLA testing is considered a valid support in the confirmation/exclusion of CD, especially in high-risk groups, such as CD relatives, or when serological and histological data are ambiguous.

Diagnostic value of duodenal antitissue transglutaminase antibodies in gluten-sensitive enteropathy

BACKGROUND

In gluten-sensitive enteropathy, antitissue transglutaminase antibodies are synthesized in the duodenum.

AIM

To compare the diagnostic yield of these autoantibodies in cultured duodenal biopsies, duodenal aspirate and serum.

METHODS

Patients (n = 315, 135 female, 180 male; age: 37.3 +/- 1.1 years) referred for duodenal biopsies, were recruited and HLA-DQ2/DQ8 haplotyped. Histological measurements were made from duodenal biopsies and cultured duodenal biopsies were used for antitissue transglutaminase antibodies analysis by enzyme-linked immunosorbent assay. Duodenal aspirate was collected in a subgroup of 81 patients. Patients were classified, according to their histology, response to a gluten-free diet and DQ2/DQ8 status, as definite, likely or nongluten-sensitive enteropathy.

RESULTS

Histology was normal in 59% of patients; 28% had lymphocytic enteritis, 1% had crypt hyperplasia and 13% showed atrophy. In Marsh III patients, there was complete agreement between duodenal and serological antitissue transglutaminase antibodies measurements. Marsh I patients showed a slight antitissue transglutaminase antibodies sensitivity improvement in cultured duodenal biopsy compared to serum in definite (22% vs. 19%) and likely gluten-sensitive enteropathy (20% vs. 14%) patients. Combined serum and cultured duodenal biopsy antitissue transglutaminase antibodies assessment increased serological sensitivity from 19% to 30% in Marsh I patients.

CONCLUSION

Duodenal antitissue transglutaminase antibodies detection improves serological determination sensitivity in Marsh I patients, providing diagnostic value and therapeutic impact.

Genetic background of celiac disease and its clinical implications

Celiac disease (CD) is a complex genetic disorder with multiple contributing genes. Linkage studies have identified several genomic regions that probably contain CD susceptibility genes. The most important genetic factors identified are HLA-DQ2 and HLA-DQ8, which are necessary but not sufficient to predispose to CD. The associations found in non-HLA genomewide linkage and association studies are much weaker. This might be because a large number of non-HLA genes contributes to the pathogenesis of CD. Hence, the contribution of a single predisposing non-HLA gene might be quite modest. Practically all CD patients carry HLA-DQ2 or HLA-DQ8, while the absence of these molecules has a negative predictive value for CD close to 100%. Genetic risk profiles for CD would be helpful in clinical practice for predicting disease susceptibility and progression.

Sumatriptan is an agonist at 5-HT receptors on myenteric neurones in the guinea-pig gastric antrum

Sumatriptan, a 5-hydroxytryptamine(1D) (5-HT(1D))-receptor agonist used in the treatment in migraine, inhibits gastric motility via the enteric nervous system. As no studies have reported enteric neuronal 5-HT(1D) receptors, we used conventional intracellular recordings to characterize the actions of sumatriptan on 145 guinea-pig antral myenteric neurones. In 24 of 29 neurones with a 5-HT(1P) receptor-mediated depolarizing response to 5-HT, application of sumatriptan caused a dose-dependent depolarization, accompanied by increased membrane resistance and enhanced excitability. Depolarizing responses to sumatriptan occurred both in cholinergic and in nitrergic neurones. Sumatriptan did not mimic the 5-HT(3) receptor-mediated fast-depolarizing responses or 5-HT(1A) receptor-mediated inhibitory responses to 5-HT. Sumatriptan had no effect on neurones not responding to 5-HT. The depolarizing response to sumatriptan was inhibited by renzapride, but not by 5-HT(1-7) receptor antagonists. We conclude that sumatriptan behaves as an agonist at the 5-HT(1P) receptor on myenteric neurones in the guinea-pig gastric antrum. The actions of sumatriptan on gastric motility seem to be attributable to a direct action on enteric neurones.

FOXP3 polymorphisms in type 1 diabetes and coeliac disease

The FOXP3 gene encodes a transcription factor thought to be essential for the development and function of T regulatory cells. Two previous studies have tested common polymorphisms in FOXP3 for association with type 1 diabetes (T1D) with conflicting results. The aim of our study was to see whether there is any evidence of association between the FOXP3 polymorphisms previously reported to be associated with T1D, in a Caucasian population regarding T1D and coeliac disease (CD). We further looked for evidence of interaction between FOXP3 polymorphisms and HLA-DR3 in conferring susceptibility to T1D. Initially, we analysed two microsatellites in the FOXP3 gene in 363 T1D nuclear families. Our results indicated an association between FOXP3 and T1D (global p=0.004) and a possible interaction between FOXP3 and the HLA-DR3-DQ2 susceptibility haplotype. We then genotyped an additional independent set of 826 T1D patients and 1459 controls as well as one CD dataset consisting of 325 families. A similar tendency was revealed in the CD family material (pnc=0.055 for the associated allele). On the other hand, we were unable to reproduce our initial findings in the T1D case-control dataset (global p=0.6). Our results suggest that the tested FOXP3 markers do not have any major impact on susceptibility for these diseases.

Bone marrow transplantation ameliorates pathology in interleukin-10 knockout colitic mice

The authors have previously reported the derivation of colonic subepithelial myofibroblasts (SEMFs) in both humans and mice from bone marrow (BM). In the pathogenesis of inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis, colonic SEMFs mediate several types of inflammatory response. In the present study, interleukin (IL)-10-/- mice were used as a model of IBD to investigate the involvement of BM-derived cells in the inflamed mucosa. Male whole BM [either C57/BL10 (wild type: WT) or IL-10-/- donor mice] was used to perform bone marrow transplantation (BMT) into both WT and IL-10-/- female mice. Tissue samples were evaluated by immunohistochemistry for alpha-smooth muscle actin expression and by in situ hybridization using a Y-chromosome-specific probe to track the donor-derived colonic SEMFs. The mucosal expression of mRNA for pro-inflammatory cytokines was analysed by reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, mRNA expression of matrix metalloproteinase (MMP)-7 and osteopontin in the inflamed mucosa was assessed using in situ hybridization. Body weights and histological scores showed that IL-10-/- mice that received WT BM had an improved course of colitis, decreased mucosal pro-inflammatory mRNA expression, and up to 30% of their SEMFs were of BM origin. Conversely, IL-10-/- mice receiving IL-10-/- BM progressed to extensive colitis, and Y probe analysis revealed that up to 45% of colonic SEMFs were of BM origin. WT mice receiving IL-10-/- or WT BM had no signs of colonic inflammation. The expression of MMP-7 and osteopontin was up-regulated in the inflamed mucosa. In conclusion, IL-10-/- mice displayed ameliorated disease activity after WT BMT, whilst colitis was not induced in WT mice by IL-10-/- BMT. The contribution of BM-derived cells to colonic SEMFs was significantly increased in the inflamed mucosa compared with non-inflamed mucosa.

Update on the evaluation and diagnosis of celiac disease

PURPOSE OF REVIEW

Our understanding of the pathophysiology of celiac disease has advanced with associated improvement in diagnostic modalities. Recent studies have placed the prevalence of celiac disease in Western populations at between 1:250 and 1:67. Celiac disease is common throughout the world and most cases go undiagnosed. Understanding the risk factors, clinical presentations and diagnostic modalities is necessary to identify and treat patients with this commonly misdiagnosed disorder.

RECENT FINDINGS

Increased prevalence of celiac disease in individuals with autoimmune diseases, reduced bone mineral density and undiagnosed liver disease have been confirmed. However, celiac disease may not be associated with Down's syndrome or epilepsy. Evidence supports high sensitivity and specificity of endomysial- and tissue transglutaminase-based tests in most settings. In children, high or low tissue transglutaminase levels may preclude the need for duodenal biopsy. Cost-effectiveness studies suggest using tissue transglutaminase or endomysial initially, while distal duodenal or jejunal biopsy may confirm celiac disease in the absence of proximal changes.

SUMMARY

There is insufficient evidence to support mass screening for celiac disease. However, case finding in individuals with risk factors for celiac disease is recommended. Further study is necessary to define diagnostic algorithms and target populations likely to benefit from testing.

Enteric nervous system

PURPOSE OF REVIEW

Our aim was to provide a synopsis of how the field of enteric neurobiology has advanced during the past year.

RECENT FINDINGS

With such a large number of studies to choose from and given our emphasis in last year's issue on developmental aspects of the enteric nervous system, we have focused on several key themes reflecting the current interest in the way the enteric nervous system is altered in disease.

SUMMARY

The new basic science information gathered during the past year provides insight into pathophysiological processes and will pave the way for improved understanding of both organic and 'functional' gastrointestinal disorders.

Gluten sensitive enteropathy and other causes of small intestinal lymphocytosis

Recent studies on gluten sensitive enteropathy (GSE) have heightened the pathologist's awareness of intraepithelial lymphocytes in duodenal biopsies. Mild histologic forms of GSE are now recognized with increased IELs as the only histologic change. In this review, both the classic morphology and "minimal deviation" GSE are discussed in detail, with special emphasis on the differential diagnosis and how to avoid overdiagnosing this condition. The Marsh-Oberhuber classification is described and contrasted with a more practical diagnostic terminology that is recommended for use in pathology reports. Other important conditions associated with duodenal lymphocytosis, such as refractory sprue, autoimmune enteropathy, and Helicobacter pylori-associated duodenitis, are also presented.