The anti-deamidated gliadin peptide antibodies unmask celiac disease in small children with chronic diarrhoea

Early Antibody Dynamics in a Prospective Cohort of Children At Risk of Celiac Disease

INTRODUCTION

The purpose of this study was to identify possible serum biomarkers predicting celiac disease (CD) onset in children at risk.

METHODS

A subgroup from an ongoing, international prospective study of children at risk of CD was classified according to an early trajectory of deamidated gliadin peptides (DGPs) immunoglobulin (Ig) G and clinical outcomes (CD, potential CD, and CD autoimmunity).

RESULTS

Thirty-eight of 325 children developed anti-tissue transglutaminase IgA antibody (anti-tTG IgA) seroconversion. Twenty-eight of 38 children (73.6%) showed an increase in anti-DGPs IgG before their first anti-tTG IgA seroconversion.

DISCUSSION

Anti-DGPs IgG can represent an early preclinical biomarker predicting CD onset in children at risk.

Diagnostic Accuracy of IgA Anti-Transglutaminase and IgG Anti-Deamidated Gliadin for Diagnosis of Celiac Disease in Children under Two Years of Age: A Systematic Review and Meta-Analysis

The need of adding the determination of anti-deamidated gliadin peptide (DGP) IgG to anti-transglutaminase (TTG) IgA antibodies for diagnosis of celiac disease (CD) in children <2 years of age is controversial. We performed a systematic review and meta-analysis to evaluate, by head-to-head comparison, the diagnostic accuracy of TTG IgA and DGP IgG antibodies. We searched PubMed, MEDLINE, and Embase databases up to January 2021. The diagnostic reference was intestinal biopsy. We calculated the sensitivity and specificity of these tests and the odds ratio (OR) between the tests. Fifteen articles were eligible for the systematic review and ten were eligible for the meta-analysis. Sensitivity and specificity were 0.96 (95% confidence interval (CI), 0.91–0.98) and 0.96 (95% CI, 0.85–0.99) for DGP IgG and 0.93 (95% CI, 0.88–0.97) and 0.98 (95% CI, 0.96–0.99) for TTG IgA, respectively. TTG IgA specificity was significantly higher (OR 9.3 (95% CI, 2.3–37.49); p < 0.001) while the sensitivity of DGP IgG was higher without reaching statistical significance (OR: 0.6 (95% CI, 0.24–1.51); p = 0.28). Both the meta-analysis and the systematic review showed that some children with early CD are missed without the DGP IgG test. In children <2 years of age, TTG IgA is the best CD screening test; however, the addition of DGP IgG may increase the diagnostic sensitivity.

The Gluten-Free Diet for Celiac Disease and Beyond

The gluten-free diet (GFD) has gained popularity beyond its main medical indication as the treatment for gluten-induced immune-mediated disorders such as celiac disease (CD), dermatitis herpetiformis, gluten ataxia, wheat allergy, and non-celiac gluten sensitivity. However, the diet carries some disadvantages such as elevated costs, nutritional deficiencies, and social and psychological barriers. The present work aims to review indications, proven benefits, and adverse events of a gluten-free diet. Close follow-up with patients following the diet is recommended. More data is needed to assess the effectiveness of the diet in managing mental and cognitive disorders and to establish a connection between the brain and gluten.

The Prevalence of Anti-Zein Antibodies: A Comparative Study between Celiac Disease and Irritable Bowel Syndrome

Celiac disease (CD) is a chronic immune-mediated enteropathy triggered by exposure to dietary gluten in genetically predisposed individuals. In contrast, irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder affecting the large intestine, without an autoimmune component. Here, we evaluated the prevalence of IgA and IgG antibodies to maize zeins (AZA) in patients with CD and IBS. Using an in-house ELISA assay, the IgA and IgG anti-zein antibodies in the serum of 37 newly diagnosed CD (16 biopsy proved and 21 serological diagnosis) and 375 IBS patients or 302 healthy control (HC) subjects were measured. Elevated levels of IgA AZA were found in CD patients compared with IBS patients (p < 0.01) and HC (p < 0.05). CD patients had the highest prevalence (35.1%), followed by IBS (4.3%) and HCs (2.3%) (p < 0.0001). IgG AZA antibodies were not found in any CD patients, IBS patients, or HC subjects. A significant positive correlation was found between IgA AZA with IgA anti-gliadin (AGA, r = 0.34, p < 0.01) and IgA anti-deaminated gliadin peptides (DGP, r = 0.42, p < 0.001) in the celiac disease group. Taken together, our results show for the first time a higher prevalence of AZA IgA antibodies in newly diagnosed CD patients than in IBS patients, confirming a biased immune response to other gliadin-related prolamins such as maize zeins in genetically susceptible individuals.

Celiac disease: from etiological factors to evolving diagnostic approaches

Celiac disease has advanced from a medical rarity to a highly prevalent disorder. Patients with the disease show varying degrees of chronic inflammation within the small intestine due to an aberrant immune response to the digestion of gliadin found in wheat. As a result, cytokines and antibodies are produced in celiac patients that can be used as specific biomarkers for developing diagnostic tests. This review paper describes celiac disease in terms of its etiological cause, pathological effects, current diagnostic tests based on mucosal biopsy, and the genetic basis for the disease. In addition, it discusses the use of gliadin-induced cytokines, antibodies and autoantibodies as a diagnostic tool for celiac disease. Despite good initial results in terms of sensitivity and specificity, when these immunological tests were used on a large scale, even in combination with genetic testing, the results showed lower predictive value. This review addresses that issue and ends with an outlook on future work required to develop diagnostic tests with greater accuracy in predicting celiac disease in the general public, thus avoiding the need for endoscopy and mucosal biopsy.

Coeliac disease in infants: antibodies to deamidated gliadin peptide come first!

Background

The onset of coeliac disease (CD) in the first year of life is uncommon and the diagnosis can be challenging due to the suboptimal sensitivity of tissue transglutaminase antibodies (tTG) at this age and the many other possible causes of malabsorption in infants. Antibodies to deamidated gliadin peptides (anti-DGPs), especially IgG, may appear earlier than IgA anti-tTG in very young children with CD.

Case presentation

We report here on an 8-month-old child who was evaluated for failure to thrive, constipation and developmental delay. The symptoms started following gluten introduction in the diet. Laboratory tests showed high fecal elastase concentration, normal serum IgA levels with positive IgG and IgA anti-DGPs, whereas anti-tTG were not detected. The duodenal biopsy revealed a complete villous atrophy (Marsh-Oberhuber 3C). The culture of biopsy fragments in the presence of gliadin peptides did not stimulate the production of IgA anti-endomysial antibodies. Genetic testing proved the child was positive for HLA-DQ2 (DQA1*05; DQB1*02) and HLA-DQ8 (DQA1*03, DQB1*0302). Having initiated the gluten-free diet, the symptoms disappeared and the infant experienced rapid catch-up growth with normalization of psychomotor development.

Conclusions

This case report highlights the utility of anti-DGPs for screening infants with suspected CD. The pattern with positivity for IgG and IgA anti-DGPs only is rare in IgA-competent children with biopsy-proven CD. It could be explained in infancy as immaturity of the adaptive immune system.

A modular electrochemical peptide-based sensor for antibody detection

We report a modular electrochemical peptide-based sensor targeting the anti-deamidated gliadin peptide (DGP) antibody. A recognition peptide, here DGP, is grafted onto a supporting peptide bearing a redox label. The fabricated peptide-based sensor supports the detection of the target antibody (anti-DGP antibody) in the nanomolar range.

Antibodies to deamidated gliadin peptides: an accurate predictor of coeliac disease in infancy

Immunoglobulin G antibodies against deamidated gliadin peptides are now known to have diagnostic accuracy comparable to tissue transglutaminase and endomysium autoantibodies in patients with coeliac disease. However, little is known about their predictive value in infants with a suspected gluten enteropathy. We tested whether deamidated gliadin immunoglobulin G antibodies are more reliable than traditional tests for coeliac disease screening in infancy. Sixty-five children under 2 years of age (42 with malabsorption, 23 controls) were tested for deamidated gliadin immunoglobulin G, tissue transglutaminase and endomysium immunoglobulin A, and gliadin immunoglobulins A and G . Thirty-seven of the 42 children with malabsorption had deamidated gliadin antibodies, associated with tissue transglutaminase and endomysial antibodies in 33, and with gliadin immunoglobulins A and G in 21 and 29, respectively. Intestinal biopsy was performed in 34 of the 37 children positive for deamidated gliadin antibodies. Thirty-two/34 showed villous atrophy consistent with coeliac disease, while the remaining two had a Marsh 1 and a normal mucosa, respectively. Only gliadin immunoglobulins A (4.3%) and G (39.1%) were found in controls. The sensitivity of deamidated gliadin, tissue transglutaminase and endomysial antibodies for coeliac disease was significantly higher than that of gliadin immunoglobulins G and A. High titre deamidated gliadin antibodies correlated with severe intestinal damage. Deamidated gliadin antibodies showed a higher diagnostic accuracy for coeliac disease than gliadin antibodies in infancy. High titre deamidated gliadin antibodies predict a severe gluten-dependent duodenal damage.

Diagnosis of celiac disease

This article reviews issues related to identifying the appropriate patient to test for celiac disease, the performance characteristics of serologic testing, the role of gene testing for human leukocyte antigen DQ2 and DQ8 haplotypes, and issues related to the performance of small intestinal biopsy. The article concludes with a review of special diagnostic considerations in pediatric patients.

Diagnostic value of anti-deamidated gliadin peptide IgG antibodies for celiac disease in children and IgA-deficient patients

OBJECTIVES

The aim of the study was to analyze the diagnostic performance of anti-deamidated gliadin peptide (dGp) immunoglobulin (Ig) G and IgA regarding the age at celiac disease (CD) diagnosis and the anti-dGp IgG usefulness for diagnosing CD IgA-deficient patients.

METHODS

Anti-dGp IgG and IgA and anti-native gliadin (nGlia) IgA were determined by enzyme fluoroimmunoassay in 100 newly diagnosed anti-tissue transglutaminase (tTG) IgA-positive pediatric and adult patients with CD and in 100 age-matched patients with other digestive pathologies. Anti-dGp IgG was evaluated in 6 CD IgA-deficient patients.

RESULTS

When analyzing all of the patients, the anti-dGp IgG assay showed higher diagnostic accuracy (area under receiver operating characteristic curve), specificity, and positive predictive value than anti-dGp IgA and anti-nGlia IgA. All of the diagnostic parameters corresponding to anti-dGp IgG reached the same values as anti-tTG IgA in children 7 years or younger. In older patients, both anti-dGp isotypes showed an inverse behavior, IgG having a higher specificity and positive predictive value but a lower sensitivity and negative predictive value than IgA. Anti-dGp levels were associated with the severity of intestinal lesions, and an inverse association was found regarding age at diagnosis. Both anti-dGp IgG and IgA were found to be positive in the 9 patients with minimal intestinal changes included in the study. All of the patients with CD with IgA deficiency were positive for anti-dGp IgG.

CONCLUSIONS

The diagnostic performance of anti-dGp depends on the antibody isotype and on the age at CD diagnosis, anti-dGp IgG being a serological marker at least as useful as anti-tTG IgA for detecting CD in children ages 7 years or younger. Our data also indicate that anti-dGp IgG can improve the diagnosis of IgA-deficient patients.

Determination of IgG and IgA antibodies against native gliadin is not helpful for the diagnosis of coeliac disease in children up to 2 years old

OBJECTIVE

Assays for antibodies against native gliadin (anti-nGli) are still often assumed to perform better in the diagnosis of coeliac disease in young children than tests for antibodies to deamidated gliadin (anti-dGli), tissue transglutaminase (anti-tTG), and endomysium (EmA). We compared the performance of assays for anti-nGli, anti-dGli, anti-tTG, and EmA in this age group.

METHODS

We investigated retrospectively 184 children (42 with coeliac disease under normal diet and 142 controls) up to 2 years of age. Immunoglobulin (Ig) A- and IgG-anti-dGli, IgA- and IgG-anti-nGli, IgA- and IgG-anti-tTG, and IgA-EmA were measured in serum. Areas under receiver operating characteristics curves, sensitivities, specificities, positive and negative predictive values, positive and negative likelihood ratios, as well as diagnostic odds ratios were calculated.

RESULTS

From all of the tests investigated, only assays for IgG-anti-dGli, IgA-anti-tTG, and IgA-EmA had high specificity (≥ 0.96) connected with high sensitivity (≥ 0.86), with high positive predictive values (≥ 0.52 and ≥ 0.69 at pretest probabilities of 0.05 and 0.1, respectively) and negative predictive values (≥ 0.99 and ≥ 0.98 at pretest probabilities of 0.05 and 0.1, respectively). These assays also showed high positive likelihood ratio (≥ 24) at low negative likelihood ratio (≤ 0.15) and high diagnostic odds ratios (≥ 136).

CONCLUSIONS

Our results do not support the use of assays of anti-nGli to diagnose coeliac disease in young children. IgA-anti-tTG, IgA-EmA, and IgG-anti-dGli perform better than anti-nGli.

Advances in coeliac disease

PURPOSE OF REVIEW

This article critically summarizes the recent scientific and clinical advances in coeliac disease.

RECENT FINDINGS

Epidemiological studies have shown that coeliac disease is as common in parts of Asia, Africa and Eastern Europe as in the western world. Genome-wide association studies continue to identify genetic susceptibilities that are both unique to coeliac disease and overlap with other autoimmune diseases. Human leukocyte antigen genotyping offers additional sensitivity in detecting coeliac disease in individuals who have self-prescribed gluten-free diets (GFD) or have atypical presentations. Immunological advances have highlighted the potential proinflammatory pitfalls of vitamin A supplementation in active coeliac disease and have enabled identification of oat and barley subsets that may be safely incorporated into coeliac diets. Large population-based studies have expanded our knowledge of the long-term risks of coeliac disease, in addition to excluding infertility as a cause for concern once a GFD has been established.

SUMMARY

The long-term implications of active coeliac disease emphasize the need for early detection and strict adherence to GFD, which remains the cornerstone of management. Technological advances in food modulation and immuno-therapies offer promise, but remain in the translational phases of clinical trials at present.