Co-localization of gluten consumption and HLA-DQ2 and -DQ8 genotypes, a clue to the history of celiac disease

Characterisation of T cell receptor repertoires in coeliac disease

AIMS

Characterise T-cell receptor gene (TR) repertoires of small intestinal T cells of patients with newly diagnosed (active) coeliac disease (ACD), refractory CD type I (RCD I) and patients with CD on a gluten-free diet (GFD).

METHODS

Next-generation sequencing of complementarity-determining region 3 (CDR3) of rearranged T cell receptor β (TRB) and γ (TRG) genes was performed using DNA extracted from intraepithelial cell (IEC) and lamina propria cell (LPC) fractions and a small subset of peripheral blood mononuclear cell (PBMC) samples obtained from CD and non-CD (control) patients. Several parameters were assessed, including relative abundance and enrichment.

RESULTS

TRB and TRG repertoires of CD IEC and LPC samples demonstrated lower clonality but higher frequency of rearranged TRs compared with controls. No CD-related differences were detected in the limited number of PBMC samples. Previously published LP gliadin-specific TRB sequences were more frequently detected in LPC samples from patients with CD compared with non-CD controls. TRG repertoires of IECs from both ACD and GFD patients demonstrated increased abundance of certain CDR3 amino acid (AA) motifs compared with controls, which were encoded by multiple nucleotide variants, including one motif that was enriched in duodenal IECs versus the PBMCs of CD patients.

CONCLUSIONS

Small intestinal TRB and TRG repertoires of patients with CD are more diverse than individuals without CD, likely due to mucosal recruitment and accumulation of T cells because of protracted inflammation. Enrichment of the unique TRG CDR3 AA sequence in the mucosa of patients with CD may suggest disease-associated changes in the TCRγδ IE lymphocyte (IEL) landscape.

Prospects for the treatment of gluten-associated diseases: on our daily bread, celiac disease, gluten proteins and more…

Food safety all over the world is largely dependent on production of grains that are cultivated in 60% of agricultural lands. Wheat is the main food for millions of people and one of the three most commonly cultivated grain cultures worldwide, along with corn and rice. Modern wheat is a product of gene engineering interventions aimed at increased productivity, yields, nutrient quota, and storage time, as well as immunogenic properties. However, the consumption of gluten, a proline and glutamine-rich wheat, rye and barley protein, triggers gluten-dependent disorders, such as celiac disease, wheat allergy, baker's asthma and wheat-dependent exercise-induced anaphylaxis. This group of disorders are curable provided the correct diagnosis has been made and strict lifelong gluten-free diet is implemented. Continuous patient's adherence to the gluten-free diet is associated with a number of medical and paramedical challenges, and the adherence level of the most compliant patients does not exceed 80%. The paper discuss other treatment strategies to improve the nutrition of people with gluten-sensitive disorders, in particular, the reduction grain gluten content, gluten sequestration in the gut before its digestion, prevention of gluten absorption and subsequent immune cell activation, and administration of tissue transglutaminase 2 inhibitors.

Meta-Analysis and Systematic Review of HLA DQ2/DQ8 in Adults with Celiac Disease

Although people with human leukocyte antigens (HLA) DQ2 and/or DQ8 are more likely to develop celiac disease (CD), the condition cannot be fully explained by this genetic predisposition alone. Multiple, as yet unidentified, factors contribute to the genesis of CD, including genetics, the environment, and the immune system. In order to provide insight into a prospective possibility and an expanded screening technique, we aim to undertake a comprehensive and meta-analytical study of the assessment and distribution of HLA class II (HLA-DQ2/DQ8) in adult CD patients. A systematic review was conducted using an electronic search of databases (PubMed, Google Scholar, Embase, and Direct Science) from January 2004 to February 2022. DQ2/DQ2 homozygotes have the highest risk of developing CD. DQ2/DQ8 typing is an effective test to exclude CD from the differential diagnosis of a patient with CD symptoms. Although other non-HLA genes have been associated with CD, they are rarely considered at diagnosis because they account for only a small proportion of the heritability of CD. This finding, together with the information gathered previously, may be useful in considering widely available and economically feasible screening options for celiac disease in young people.

Characteristics of Children With Inflammatory Bowel Disease and Coexisting Celiac Disease Seropositivity

OBJECTIVES

Celiac disease (CeD) autoimmunity and coexisting inflammatory bowel disease (IBD) present a diagnostic dilemma. Our aims were to describe the phenotype of children with IBD and CeD seropositivity and evaluate provider confidence for diagnosing CeD in this population.

METHODS

We performed a single-center retrospective cohort study of subjects ≤18 years old with IBD and CeD seropositivity between 2006 and 2020. Subjects were considered to have IBD-CeD if they met CeD diagnosis by serology and histology per North American Society For Pediatric Gastroenterology, Hepatology and Nutrition guidelines and if providers suspected CeD as evaluated by a survey. The IBD-only cohort included seropositive participants that did not meet criteria for CeD. Demographic, histologic, gross endoscopic, and laboratory features were compared using Fisher exact test.

RESULTS

Of 475 children with IBD, 8 had concomitant CeD, 5 had tissue transglutaminase (tTG) immunoglobulin A (IgA) > 10x upper limit of normal (ULN, P = 0.006), and 8 had villous atrophy (VA, P = 0.003) when compared with 17 seropositive participants with IBD-only. No children with IBD-CeD had esophageal eosinophilia, duodenal cryptitis, duodenal ulceration, or fecal calprotectin >250 µg/g. Factors that contributed to provider uncertainty for diagnosing CeD in IBD included the absence of VA and intraepithelial lymphocytes, the presence of neutrophilic and eosinophilic duodenitis, diffuse ulceration, elevated inflammatory markers, and immunosuppression therapy.

CONCLUSIONS

Diagnosing CeD in children with IBD continues to be challenging. Although high titers of tTG IgA and VA increased provider confidence for diagnosing CeD in IBD, development of evidence-based guidelines are needed. They should better assess the importance of features atypical of concomitant CeD that contribute to uncertainty.

Review article: Epidemiology of coeliac disease

Coeliac disease is an immune-mediated disease caused by ingestion of gluten in genetically susceptible individuals. Coeliac disease has been thought to affect mainly people of European origin but subsequently many studies revealed that it affects people living in North America, Oceania, South America, Asia as well as Africa. The global pooled seroprevalence and prevalence of biopsy-confirmed coeliac disease are 1.4% and 0.7% respectively. The pooled incidence rates in women and men are 17.4 (95% CI: 13.7-21.1) and 7.8 (95% CI: 6.3-9.2) per 100 000 person-years respectively. The systematic reviews, based on many population-based data, suggest that both the prevalence and the incidence of coeliac disease has increased over past three decades, which may be attributable not only to an increase in the detection rate (improvement in diagnostic tests, simplification of diagnostic criteria and increase in awareness about the disease) but also because of modernisation and globalisation related changes in the dietary practices including increase in the use of convenience food and dietary gluten. In addition to genetic factors, while there are many environmental risk factors, including age at the first introduction of gluten, breastfeeding, caesarean section, exposure to antibiotics and gut microbiome; the amount of gluten ingestion during early part of life, however, has been shown to increase the risk of coeliac disease, and this is relevant from the point of view of primary prevention. In this review, we have reviewed and summarised the literature, up till year 2021, related to the global and continent-wise epidemiology and risk factors associated with coeliac disease.

Distribution of celiac disease predisposing genes HLA-DQ2 and HLA-DQ8 in the native population of southern India

BACKGROUND

Celiac disease (CD) is an intestinal inflammatory condition caused by the ingestion of gluten peptides in wheat and related grains in individuals carrying HLA-DQ2 and/or HLA-DQ8 genes. In comparison to HLA-DQ8, a higher HLA-DQ2 prevalence is reported in European population where wheat has been the staple food for thousands of years. In non-European population, this pattern of HLA-DQ CD-predisposing gene distribution has not always been found. The aim of this study was to evaluate the HLA-DQ2 and HLA-DQ8 distribution in the native low-gluten consuming southern Indian population.

METHODS

Overall, 211 dried blood spots (DBS) were collected from native southern Indian individuals. HLA-DQ characterization and the determination of homozygous/heterozygous status were performed using commercially available HLA-DQ typing kits.

RESULTS

Of 211 collected DBS, 88 (42%, 95% CI: 36-48) were positive for HLA-DQ2 and/or HLA-DQ8 heterodimers. Overall, 40 (19%, 95% CI: 14-24) samples typed positive for HLA-DQ2 and 48 (23%, 95% CI: 18-28) typed positive for HLA-DQ8 genotypes. Of 40 HLA-DQ2-positive individuals, only one subject tested homozygous for the DQB1*02 allele.

CONCLUSIONS

In the southern Indian native general population, the prevalence of HLA-DQ8 is higher in comparison to HLA-DQ2 prevalence. This finding could be related to the delayed introduction of wheat in the diet of the southern Indian population.

Latitude and Celiac Disease Prevalence: A Meta-Analysis and Meta-Regression

BACKGROUND & AIMS

The latitudinal gradient effect is described for several autoimmune diseases including celiac disease in the United States. However, the association between latitude and global celiac disease prevalence is unknown. We aimed to explore the association between latitude and serology-based celiac disease prevalence through meta-analysis.

METHODS

We searched MEDLINE, Embase, Cochrane, and Scopus databases from their beginning through June 29, 2018, to identify screening studies that targeted a general population sample, used serology-based screening tests, and provided a clear location from which we could assign a latitude. Studies were excluded if sampling was based on symptoms, risk factors, or referral. Study selection and data extraction were performed by independent reviewers. The association measures between latitude and prevalence of serology-based celiac disease were evaluated with random-effects meta-analyses and meta-regression.

RESULTS

Of the identified 4667 unique citations, 128 studies were included, with 155 prevalence estimates representing 40 countries. Celiac disease was more prevalent at the higher latitudes of 51° to 60° (relative risk [RR], 1.62; 95% CI, 1.09-2.38) and 61° to 70° (RR, 2.30; 95% CI, 1.36-3.89) compared with the 41° to 50° reference level. No statistically significant difference was observed at lower latitudes. When latitude was treated as continuous, we found a statistically significant association between CD prevalence and latitude overall in the world (RR, 1.03, 95% CI, 1.01-1.05) and a subregional analysis of Europe (RR, 1.05; 95% CI, 1.02-1.07) and North America (RR, 1.1; 95% CI, 1.0-1.2).

CONCLUSIONS

In this comprehensive review of screening studies, we found that a higher latitude was associated with greater serology-based celiac disease prevalence.

The global burden of coeliac disease: opportunities and challenges

Coeliac disease is a systemic disorder characterized by immune-mediated enteropathy, which is caused by gluten ingestion in genetically susceptible individuals. The clinical presentation of coeliac disease is highly variable and ranges from malabsorption through solely extra-intestinal manifestations to asymptomatic. As a result, the majority of patients with coeliac disease remain undiagnosed, misdiagnosed or experience a substantial delay in diagnosis. Coeliac disease is diagnosed by a combination of serological findings of disease-related antibodies and histological evidence of villous abnormalities in duodenal biopsy samples. However, variability in histological grading and in the diagnostic performance of some commercially available serological tests remains unacceptably high and confirmatory assays are not readily available in many parts of the world. Currently, the only effective treatment for coeliac disease is a lifelong, strict, gluten-free diet. However, many barriers impede patients' adherence to this diet, including lack of widespread availability, high cost, cross-contamination and its overall restrictive nature. Routine follow-up is necessary to ensure adherence to a gluten-free diet but considerable variation is evident in follow-up protocols and the optimal disease management strategy is not clear. However, these challenges in the diagnosis and management of coeliac disease suggest opportunities for future research.

Circulating circular RNA profiles associated with celiac disease seropositivity in children with type 1 diabetes

INTRODUCTION

The frequency of celiac disease autoantibody (CDAb) positivity in type 1 diabetes (T1D) has increased due to unclear mechanisms, including autoimmune injury. Circular ribonucleic acids (circRNAs) participate in autoimmune diseases, but the roles of circRNAs in T1D with CDAbs are currently unknown. This study aimed to determine the frequency of CDAbs in Chinese children with T1D and describe the relationship between CDAbs and circRNAs.

MATERIALS AND METHODS

Eighty patients diagnosed with T1D were screened for CDAbs and CD-predisposing genes, and circRNAs in peripheral blood mononuclear cells (PBMCs) were collected from 47 patients. The Gene Expression Omnibus (GEO) database was searched for candidate circRNAs in related studies on T1D PBMCs. Data on clinical characteristics (i.e., blood glucose control, residual islet function, and daily insulin dosage) and immunophenotypes (i.e., islet autoantibodies and immune cell subsets) were collected.

RESULTS

In total, 35.0% of patients were positive for CDAbs. CD-predisposing genes accounted for 52.5% of the genes, and no significant difference in frequency was found between the CDAb-positive (CDAb⁺) and CDAb-negative (CDAb^-) groups. In addition, among the differentially expressed circRNAs from the GEO database, five highly conserved circRNAs homologous to humans and mice were screened, and only the expression of hsa_circ_0004564 in the CDAb⁺ group significantly decreased (CDAb⁺ vs. CDAb^-:1.72 ± 1.92 vs. 11.12 ± 8.59, p = 6.0 × 10^-6), while the expression of hsa_circ_0004564 was upregulated in the general T1D population. Moreover, its parental gene RAPH1 was significantly upregulated (CDAb⁺ vs. CDAb^-:1.26 ± 0.99 vs. 0.61 ± 0.46, p = 0.011). Importantly, the positive correlation between hsa_circ_0004564 and CD3⁺ cells was validated in children with T1D after adjustments for CDAbs (p = 0.029), while there were no correlations between hsa_circ_0004564 and clinical characteristics or other immune cell subsets (i.e., CD4⁺ T cells, CD8⁺ T cells, and natural killer cells).

CONCLUSION

This study highlights the importance of screening for CD in Chinese children with T1D, considering the high prevalence of CDAb positivity and CD-predisposing genes. The profile of candidate circRNAs in children with T1D with CDAbs was different from that in previous reports on general T1D patients from the GEO database. Moreover, hsa_circ_0004564 and its parental gene RAPH1 may be new targets for studying immune mechanisms in children with T1D and CD.

Wheat Breeding, Fertilizers, and Pesticides: Do They Contribute to the Increasing Immunogenic Properties of Modern Wheat?

Celiac disease (CD) is a small intestinal inflammatory condition where consumption of gluten induces a T-cell mediated immune response that damages the intestinal mucosa in susceptible individuals. CD affects at least 1% of the world’s population. The increasing prevalence of CD has been reported over the last few decades. However, the reason for this increase is not known so far. Certain factors such as increase in awareness and the development of advanced and highly sensitive diagnostic screening markers are considered significant factors for this increase. Wheat breeding strategies, fertilizers, and pesticides, particularly herbicides, are also thought to have a role in the increasing prevalence. However, less is known about this issue. In this review, we investigated the role of these agronomic practices in depth. Our literature-based results showed that wheat breeding, use of nitrogen-based fertilizers, and herbicides cannot be solely responsible for the increase in celiac prevalence. However, applying nitrogen fertilizers is associated with an increase in gluten in wheat, which increases the risk of developing celiac-specific symptoms in gluten-sensitive individuals. Additionally, clustered regularly interspaced short palindromic repeats (CRISPR) techniques can edit multiple gliadin genes, resulting in a low-immunogenic wheat variety that is safe for such individuals.

Wheat consumption and prevalence of celiac disease: Correlation from a multilevel analysis

Celiac disease (CD) is triggered by both genetic and environmental factors. More than 1% of the world's population is affected by CD. In recent years, studies have confirmed a worldwide rising trend in CD prevalence. "Westernized diet" is one of the main factors of this increasing prevalence. However, the relationship between wheat consumption, its dynamics, and CD has not been adequately investigated on a global scale. This study aimed to perform a multilevel analysis of the association between wheat consumption and CD. Wheat consumption data from countries and continents were obtained from the database. The relative increase/decrease in wheat consumption over a long period (since 1961) and a short period (since 2004) were calculated using various statistical tools. The relationship between wheat consumption and celiac frequency was determined using the R-commander R package version 2.6-2. Pearson's correlation coefficient (r = 0.88) confirmed a high positive correlation between wheat consumption and the prevalence of biopsy-proven CD by estimating continent-wide wheat consumption data, but an insignificant correlation was found when the data were compared country-wide.

Alpha-enolase involvement in intestinal and extraintestinal manifestations of celiac disease

Celiac disease is a life-long intestinal autoimmune disease, characterized by the gluten intolerance and chronic enteric inflammation. Traditionally presented by intestinal manifestations, however, a shift toward extra intestinal presentation is taking place. One of the affected organs is the nervous systems presented by neuropsychiatric manifestations, hence the mechanism and pathways are not clear. The presence of neuronal and alpha-enolases and their corresponding antibodies were noticed in the mucosa and serum of celiac disease patients, as well as in other various autoimmune diseases with psycho-neurological manifestations. The aims of the present review are to screen the literature on different isoforms of enolase, mainly alpha enolase, and their specific antibodies and to suggest their potential pathophysiological mechanisms relaying the enolases to intestinal or extraintestinal celiac disease manifestations. The shared aspects between the enolases and celiac disease and the cross-talks between alpha-enolase and tissue transglutaminase suggest new potential pathophysiological mechanisms that might drive celiac disease evolvement.

Celiac Disease: Fallacies and Facts

Our understanding of the pathophysiology of celiac disease has progressed greatly over the past 25 years; however, some fallacies about the clinical characteristics and management persist. Worldwide epidemiologic data are now available showing that celiac disease is ubiquitous. An elevated body mass index is common at the time of the diagnosis. The gluten-free diet (GFD) is an imperfect treatment for celiac disease; not all individuals show a response. This diet is widely used by people without celiac disease, and symptomatic improvement on a GFD is not sufficient for diagnosis. Finally, the GFD is burdensome, difficult to achieve, and thus has an incomplete efficacy, opening exciting opportunities for novel, nondietary treatments.

HLA class II genes in precision-based care of childhood diseases: what we can learn from celiac disease

Celiac disease (CeD) is a chronic immuno-mediated enteropathy caused by dietary gluten with marked autoimmunity traits. The human leukocyte antigen (HLA) class II heterodimers represent the main predisposing factor, although environmental agents, as viral infection, gut microbiota, and dietary regimen, also contribute to CeD risk. These molecules are involved in autoimmunity as they present self-antigens to autoreactive T cells that have escaped the thymic negative selection. In CeD, the HLA class II risk alleles, DQA1*05-DQB1*02 and DQA1*03-DQB1*03, encode for DQ2.5 and DQ8 heterodimers, and, furthermore, disease susceptibility was found strictly dependent on the dose of these genes. This finding questioned how the expression of HLA-DQ risk genes, and of relative surface protein on antigen-presenting cells, might be relevant for the magnitude of anti-gluten inflammatory response in CeD patients, and impact the natural history of disease, its pathomechanisms, and compliance to dietary treatment. In this scenario, new personalized medical approaches will be desirable to support an early, accurate, and non-invasive diagnosis, and to define genotype-guided preventive and therapeutic strategies for CeD. To reach this goal, a stratification of genetic risk, disease outcome, and therapy compliance based on HLA genotypes, DQ2.5/DQ8 expression measurement and magnitude of T cell response to gluten is mandatory. IMPACT: This article revises the current knowledge on how different HLA haplotypes, carrying the DQ2.5/DQ8 risk alleles, impact the onset of CeD. This review discusses how the expression of susceptibility HLA-DQ genes can determine the risk assessment, outcome, and prevention of CeD. The recent insights on the environmental factors contributing to CeD in childhood are reviewed. This review discusses the use of HLA risk gene expression as a tool to support medical precision approaches for an early and non-invasive diagnosis of CeD, and to define genotype-guided preventive and therapeutic strategies.

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.

The HLA complex and coeliac disease

The Human Leukocyte Antigen (HLA) has a crucial role in the development and pathogenesis of coeliac disease (CD). The genes HLA-DQA1 and HLA-DQB1, both lying in this region and encoding the HLA-DQ heterodimer, are the main genetic predisposing factors to CD. Approximately 90% of CD patients carry the heterodimer HLA-DQ2.5, leaving only a small proportion of patients with lower risk heterodimers (HLA-DQ8, HLA-DQ2.2 or HLA-DQ7.5). These HLA-DQ molecules act as receptors present in the surface of antigen presenting cells and show high affinity for deamidated gluten peptides, which bind and present to CD4⁺ T cells. This triggers the immunological reaction that evolves into CD. Since specific HLA genetics is present in almost the totality of CD patients, HLA typing has a very high negative predictive value, and it can be used to support diagnosis in specific scenarios. HLA risk has been associated to different CD-related features, such as age at onset, clinical outcomes, antibody levels and grade of histological lesion; but further research is needed. HLA-DQ genotypes have been also suggested to modulate the composition of the gut microbiota.

The Two Faces of Wheat

Wheat-based foods have been staple foods since about 10,000 years and constitute a major source of energy, dietary fiber, and micronutrients for the world population. The role of wheat in our diet, however, has recently been scrutinized by pseudoscientific books and media reports promoting the overall impression that wheat consumption makes people sick, stupid, fat, and addicted. Consequently, numerous consumers in Western countries have started to question their dietary habits related to wheat consumption and voluntarily decided to adopt a wheat-free diet without a medical diagnosis of any wheat-related disorder (WRD), such as celiac disease, wheat allergy, or non-celiac gluten sensitivity. The aim of this review is to achieve an objective judgment of the positive aspects of wheat consumption as well as adverse effects for individuals suffering from WRDs. The first part presents wheat constituents and their positive nutritional value, in particular, the consumption of products from whole-grain flours. The second part is focused on WRDs that affect predisposed individuals and can be treated with a gluten-free or -reduced diet. Based on all available scientific knowledge, wheat consumption is safe and healthy for the vast majority of people. There is no scientific evidence to support that the general population would benefit from a wheat-free diet.

Diagnosing coeliac disease: Out with the old and in with the new?

Coeliac disease (CD) is a complex condition resulting from an interplay between genetic and environmental factors. When diagnosing the condition, serological testing and genotyping are useful in excluding CD, although the gold standard of testing is currently histopathological examination of the small intestine. There are drawbacks associated with this form of testing however and because of this, novel forms of testing are currently under investigation. Before we develop completely novel tests though, it is important to ask whether or not we can simply use the data we gather from coeliac patients more effectively and build a more accurate snapshot of CD through statistical analysis of combined metrics. It is clear that not one single test can accurately diagnose CD and it is also clear that CD patients can no longer be defined by discrete classifications, the continuum of patient presentation needs to be recognised and correctly captured to improve diagnostic accuracy. This review will discuss the current diagnostics for CD and then outline novel diagnostics under investigation for the condition. Finally, improvements to current protocols will be discussed with the need for a holistic "snapshot" of CD using a number of metrics simultaneously.

Celiac disease in type 1 diabetes mellitus in the Kingdom of Saudi Arabia. Characterization and meta-analysis

Objectives:

To characterize and meta-analyze the pertinent studies concerning celiac disease (CD) among patients with type 1 diabetes mellitus (T1DM) in the Kingdom of Saudi Arabia.

Methods:

Data (from the relevant articles) were analyzed using both the Statistical Package for Social Sciences, version 20 (IBM Corp., Armonk, NY, USA) program and the comprehensive meta-analysis (CMA) program. This study was conducted between March and July 2018 at King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia. Written ethical approval was not obtained because this study was a retrospective literature review and analysis.

Results:

The prevalence of seropositive-CD was 15.88% with high heterogeneity (I²=84.0), while the prevalence of biopsy-proven CD was 12% with high heterogeneity (I²=82.7). Anti-transglutaminase was used in 7 of the 8 studies; alone in 4; with endomysial antibodies in 2; and with antigliadin antibodies (AGA) in one. In the remaining study, antireticulin antibodies was used with AGA. The age of the involved patients ranged from 8 months to 50 years old.

Conclusion:

The prevalence of biopsy-proven CD among T1DM patients in Kingdom of Saudi Arabia (12.0%) was double the global prevalence (6.0%), and much higher than the normal Saudi population (1.4%). The female-to-male ratio (2:1) of CD patients in T1DM was the same as in the normal population in Kingdom of Saudi Arabia. No significant difference was detected between the reported serologically-proven rates and the reported biopsy-proven rates (p=0.093).

Celiac Disease in Asia

Celiac disease, once thought to be very uncommon in Asia, is now emerging in many Asian countries. Although the absolute number of patients with celiac disease at present is not very high, this number is expected to increase markedly over the next few years/decades owing to increasing awareness. It is now that the medical community across the Asia should define the extent of the problem and prepare to handle the impending epidemic of celiac disease in Asia.

Global Prevalence of Celiac Disease: Systematic Review and Meta-analysis

BACKGROUND & AIMS

Celiac disease is a major public health problem worldwide. Although initially it was reported from countries with predominant Caucasian populations, it now has been reported from other parts of the world. The exact global prevalence of celiac disease is not known. We conducted a systematic review and meta-analysis to estimate the global prevalence of celiac disease.

METHODS

We searched Medline, PubMed, and EMBASE for the keywords celiac disease, celiac, celiac disease, tissue transglutaminase antibody, anti-endomysium antibody, endomysial antibody, and prevalence for studies published from January 1991 through March 2016. Each article was cross-referenced with the words Asia, Europe, Africa, South America, North America, and Australia. The diagnosis of celiac disease was based on European Society of Pediatric Gastroenterology, Hepatology, and Nutrition guidelines. Of 3843 articles, 96 articles were included in the final analysis.

RESULTS

The pooled global prevalence of celiac disease was 1.4% (95% confidence interval, 1.1%-1.7%) in 275,818 individuals, based on positive results from tests for anti-tissue transglutaminase and/or anti-endomysial antibodies (called seroprevalence). The pooled global prevalence of biopsy-confirmed celiac disease was 0.7% (95% confidence interval, 0.5%-0.9%) in 138,792 individuals. The prevalence values for celiac disease were 0.4% in South America, 0.5% in Africa and North America, 0.6% in Asia, and 0.8% in Europe and Oceania; the prevalence was higher in female vs male individuals (0.6% vs 0.4%; P < .001). The prevalence of celiac disease was significantly greater in children than adults (0.9% vs 0.5%; P < .001).

CONCLUSIONS

In a systematic review and meta-analysis, we found celiac disease to be reported worldwide. The prevalence of celiac disease based on serologic test results is 1.4% and based on biopsy results is 0.7%. The prevalence of celiac disease varies with sex, age, and location. There is a need for population-based prevalence studies in many countries.

Genetic susceptibility for celiac disease is highly prevalent in the Saudi population

BACKGROUND/AIM

To determine the frequency of celiac disease (CD)-predisposing human leukocyte antigen (HLA)-DQ genotypes in the Saudi population, where the prevalence of CD is 1.5% as recently reported in a mass screening study.

PATIENTS AND METHODS

In a cross-sectional population-based study, a total of 192 randomly selected healthy school children (97 females, mean age 10.5 ± 2.2 years, all negative for tissue transglutaminase-IgA) were typed for D QA1 and D QB1 genes by polymerase chain reaction sequence-specific oligonucleotide probes.

RESULTS

Of the 192 children, 52.7% carried the high-risk CD-associated HLA-DQ molecules: homozygous DQ2.5 ( 2.6%), DQ2.5/DQ2.2 ( 4.7%), heterozygous DQ2.5 ( 28.15%), homozygous DQ8 ( 4.2%), DQ8/DQ2.2 ( 3.6%), and double dose DQ2.2 ( 9.4%). Low-risk CD-associated HLA-DQ molecules (single dose DQ2.2 and heterozygous DQ8) constituted 3.6% and 9.4%, respectively. Among the very low-risk groups, individuals lacking alleles that contribute to DQ2/DQ8 variants (33.5%), 13.5% carried only one of the alleles of the high-risk HLA-DQ2.5 heterodimer called "half-heterodimer" (HLA-DQA1*05 in 12% and HLA-DQB1* 02 in 1.5%), and 20.8% lacked all the susceptible alleles (DQX.x). Gender distribution was not significantly different among the CD-risk groups.

CONCLUSION

We report one of the highest frequencies of CD-predisposing HLA-DQ genotypes among healthy general populations (52.7%) worldwide, which might partly explain the high prevalence of CD in the Saudi community.

A review on the relationship between gluten and schizophrenia: Is gluten the cause?

INTRODUCTION

Schizophrenia is a chronic disease that possesses various clinical manifestations. It presents rather heterogeneous characteristics with respect to onset type, symptoms, and the course of the disease. Although the lifetime prevalence is as low as 1%, it can cause serious disability. Thus, it is very important to develop efficient treatment methods. In some studies, it is hypothesized that removing gluten from the diet leads to a significant improvement in disease symptoms. Epidemiological studies revealed that the prevalence of celiac disease among schizophrenic patients is almost two times higher than that of the general population.

OBJECTIVE

In this review, we evaluate the effects of gluten and celiac disease on the onset of schizophrenia. Efficacy of gluten-free diet applications, antibody response against gluten, and the interaction of the brain-gut axis and the presence of common genetic points are also investigated.

METHODS

Without any publication date restriction, Pubmed database searches were made for 'schizophrenia, gluten, gliadin, celiac disease, exorphin, brain-gut axis, psychiatric disorders.' The keywords and the articles about the schizophrenia-celiac disease relationship are included in our review.

RESULTS

Several studies presented evidence to suggest that symptoms associated with schizophrenia were minimized when gluten was excluded from patients' diets. Immunological searches revealed that most schizophrenic patients with increased anti-gliadin antibodies did not possess celiac disease; yet, the presence of increased antibodies against gliadin can be the share point of the immunological abnormalities found in both of the diseases.

DISCUSSION

There were no consistent results in the clinical, immunological, microbiological, and epidemiological studies that investigated the relationship between schizophrenia and celiac disease. This presents a need for a larger scale study to confirm the presence of this suggested correlation between schizophrenia and celiac disease. The underlying mechanisms between the two diseases should be explored.

Nomenclature and diagnosis of gluten-related disorders: A position statement by the Italian Association of Hospital Gastroenterologists and Endoscopists (AIGO)

BACKGROUND

"Gluten-related disorders" is a term that encompasses different diseases induced by the ingestion of gluten-containing food. Because of their incidence the scientific community has been intensively studying them.

AIM

To support gastroenterologists with a correct nomenclature and diagnostic approach to gluten-related disorders in adulthood.

METHODS

The Italian Association of Hospital Gastroenterologists and Endoscopists (AIGO) commissioned a panel of experts to prepare a position statement clarifying the nomenclature and diagnosis of gluten-related disorders, focusing on those of gastroenterological interest. Each member was assigned a task and levels of evidence/recommendation have been proposed.

RESULTS

The panel identified celiac disease, wheat allergy and non-celiac gluten sensitivity as the gluten-related disorders of gastroenterological interest. Celiac disease has an autoimmune nature, wheat allergy is IgE-mediated while the pathogenesis of non-celiac gluten sensitivity is still unknown as is the case of non-IgE mediated allergy. Diagnosis should start with the serological screening for celiac disease and wheat allergy. In case of normal values, the response to a gluten-free diet should be evaluated and a confirmatory blind food challenge carried out.

CONCLUSIONS

Gluten-related disorders are clinically heterogeneous. Patients should be carefully managed and specific protocols applied for a correct differential diagnosis in gastroenterological setting.

High Frequency of Haplotype HLA-DQ7 in Celiac Disease Patients from South Italy: Retrospective Evaluation of 5,535 Subjects at Risk of Celiac Disease

Background

Celiac disease (CD) has a strong genetic component mainly due to HLA DQ2/DQ8 encoding genes. However, a minority of CD patients are DQ2/DQ8-negative. To address this issue, we retrospectively characterized HLA haplotypes in 5,535 subjects at risk of CD (either relatives of CD patients or subjects with CD-like symptoms) referred to our center during a 10-year period.

Methods

We identified loci DQA1/DQB1/DRB1 by sequence-specific oligonucleotide-PCR and sequence-specific primer-PCR; anti-transglutaminase IgA/IgG and anti-endomysium IgA by ELISA and indirect immunofluorescence, respectively.

Results

We diagnosed CD in 666/5,535 individuals, 4.2% of whom were DQ2/DQ8-negative. Interestingly, DQ7 was one of the most abundant haplotypes in all CD patients and significantly more frequent in DQ2/DQ8-negative (38%) than in DQ2/DQ8-positive CD patients (24%) (p<0.05).

Conclusion

Our data lend support to the concept that DQ7 represents an additive or independent CD risk haplotype with respect to DQ2/DQ8 haplotypes but this finding should be verified in other large CD populations.

Non-celiac gluten sensitivity: Time for sifting the grain

In the last few years, a new nomenclature has been proposed for the disease induced by the ingestion of gluten, a protein present in wheat, rice, barley and oats. Besides celiac disease and wheat allergy, the most studied forms of gluten-related disorders characterized by an evident immune mechanism (autoimmune in celiac disease and IgE-mediated in wheat allergy), a new entity has been included, apparently not driven by an aberrant immune response: the non-celiac gluten sensitivity (NCGS). NCGS is characterized by a heterogeneous clinical picture with intestinal and extraintestinal symptoms arising after gluten ingestion and rapidly improving after its withdrawal from the diet. The pathogenesis of NCGS is largely unknown, but a mixture of factors such as the stimulation of the innate immune system, the direct cytotoxic effects of gluten, and probably the synergy with other wheat molecules, are clues for the complicated puzzle. In addition, the diagnostic procedures still remain problematic due to the absence of efficient diagnostic markers; thus, diagnosis is based upon the symptomatic response to a gluten-free diet and the recurrence of symptoms after gluten reintroduction with the possibility of an important involvement of a placebo effect. The temporary withdrawal of gluten seems a reasonable therapy, but the timing of gluten reintroduction and the correct patient management approach are have not yet been determined.

Celiac disease from a global perspective

Celiac disease (CD) is one of the commonest lifelong disorders in countries populated by individuals of European origin, affecting approximately 1% of the general population. This is a common disease also in North Africa, Middle East and India. The widespread diffusion of CD is not surprising given that its causal factors (HLA predisposing genotypes and consumption of gluten-containing cereals) show a worldwide distribution. Further studies are needed to quantify the incidence of CD in apparently "celiac-free" areas such as Sub-Saharan Africa and Far East. Several reports have shown that CD is increasing in frequency in different geographic areas. Genetic factors do not explain the rising incidence during the last decades; environmental or lifestyle factors may be responsible for these changes over time. The majority of patients with CD are still undiagnosed all over the world, leading to debate about the need of screening program.

World perspective and celiac disease epidemiology

In Europe and the USA, the mean frequency of celiac disease (CD) in the general population is approximately 1%, with some regional differences, the reasons for which remain elusive. A similar disease prevalence has been found in other countries mostly populated by individuals of European origin, e.g. Australia and Argentina. In Western countries, a true rise in overall CD prevalence of CD has been documented. CD is a common disorder in North Africa, the Middle East and India; however, the diagnostic rate is low in these countries due to low availability of diagnostic facilities and poor disease awareness. The highest CD prevalence in the world (5.6%) has been described in an African population originally living in Western Sahara, the Saharawi, of Arab-Berber origin. The reasons for this high CD frequency are unclear but could be primarily related to recent dietary changes and genetic factors, given the high level of consanguinity of this population. Further studies are needed to quantify the incidence of the celiac condition in apparently 'celiac-free' areas such as Sub-Saharan Africa and the Far East. In many developing countries, the frequency of CD is likely to increase in the near future given the diffuse tendency to adopt Western, gluten-rich dietary patterns. As most cases currently escape diagnosis all over the world, an effort should be made to increase the awareness of CD polymorphism. A cost-effective case-finding policy and new strategies of mass CD screening could significantly reduce the morbidity and mortality associated with untreated disease. The current high prevalence of CD is just the last link in a chain of events started about 10,000 years ago after wheat domestication and diffusion from the Middle East. We hypothesize different mechanisms to explain the so-called evolutionary celiac paradox of co-localization of gluten consumption and HLA CD-predisposing genotypes.

Prevalence of celiac disease and celiac autoimmunity in the Toba Native Amerindian community of Argentina

BACKGROUND

Celiac disease (CD) is mostly recognized among subjects with a Caucasian ethnic ancestry. No studies have explored conditions predisposing Amerindians to CD.

OBJECTIVE

To prospectively assess environmental, genetic and serological conditions associated with CD among members of the Toba native population attending a multidisciplinary sanitary mission.

METHODS

An expert nutritionist determined daily gluten intake using an established questionnaire. Gene typing for the human leukocyte antigen (HLA) class II alleles was performed on DNA extracted from peripheral blood (HLA DQ2⁄DQ8 haplotype). Serum antibodies were immunoglobulin (Ig) A tissue transglutaminase (tTG) and the composite deamidated gliadin peptides⁄tTG Screen test. Positive cases were tested for IgA endomysial antibodies.

RESULTS

A total of 144 subjects (55% female) were screened. The estimated mean gluten consumption was 43 g⁄day (range 3 g⁄day to 185 g⁄day). Genetic typing showed that 73 of 144 (50.7%) subjects had alleles associated with CD; 69 (94.5%) of these subjects had alleles for HLA DQ8 and four had DQ2 (5.5%). Four and six subjects had antibody concentrations above the cut-off established by the authors' laboratory (>3 times the upper limit of normal) for IgA tTG and deamidated gliadin peptides⁄tTG screen, respectively. Four of these had concomitant positivity for both assays and endomysial antibodies were positive in three subjects who also presented a predisposing haplotype.

CONCLUSION

The present study was the first to detect CD in Amerindians. The native Toba ethnic population has very high daily gluten consumption and a predisposing genetic background. We detected subjects with persistent CD autoimmunity and, at least, three of them fulfilled serological criteria for CD diagnosis.