Current methods to diagnose the unresponsive and complicated forms of coeliac disease

Do Serological Tests Eliminate the Need for Endoscopic Biopsy for the Diagnosis of Symptomatic Patients with Celiac Disease? A Retrospective Study with Review of Literature

Background: Celiac disease is one of the most common genetic allergies worldwide. The prevalence of celiac disease in Iran is similar to or even higher than the global prevalence. Celiac disease is a chronic inflammatory disease that affects the small intestine. Affected patients are allergic to gluten protein that exists in some grains, such as wheat and barley. Methods: Serological endomysial IgA antibody (EMA-AB) and tissue transglutaminase IgA antibody (TTG-IgA) tests were performed on 114 patients aged the ages of 0-18 years with histopathological findings of celiac disease. The results of these tests were compared to the results of the histopathological study of the duodenal biopsy. Results: Based on the receiver operating characteristic (ROC) curve and a calculation of the TTG-IgA test's sensitivity and specificity, the best diagnostic limit for the TTG-IgA test is 144, which has the best sensitivity and specificity. At this value (cut-off), the test's sensitivity was 62%, and the specificity was 93.7%. For the endomysial test, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 80%, 93%, 90%, and 75%, respectively. Conclusion: The diagnostic accuracy of the endomysial test is better than that of the TTG-IgA test in general for diagnosing patients with celiac disease. In the TTG-IgA test, false-positive cases are high due to a cut-off of 20, reducing the test's specificity. In these false-positive cases, the endomysial test helps in better diagnosis.

Immunogenetic Pathogenesis of Celiac Disease and Non-celiac Gluten Sensitivity

Celiac disease is the most common oral intolerance in Western countries. It results from an immune response towards gluten proteins from certain cereals in genetically predisposed individuals (HLA-DQ2 and/or HLA-DQ8). Its pathogenesis involves the adaptive (HLA molecules, transglutaminase 2, dendritic cells, and CD4(+) T-cells) and the innate immunity with an IL-15-mediated response elicited in the intraepithelial compartment. At present, the only treatment is a permanent strict gluten-free diet (GFD). Multidisciplinary studies have provided a deeper insight of the genetic and immunological factors and their interaction with the microbiota in the pathogenesis of the disease. Similarly, a better understanding of the composition of the toxic gluten peptides has improved the ways to detect them in food and drinks and how to monitor GFD compliance via non-invasive approaches. This review, therefore, addresses the major findings obtained in the last few years including the re-discovery of non-celiac gluten sensitivity.

Monitoring of gluten-free diet compliance in celiac patients by assessment of gliadin 33-mer equivalent epitopes in feces

BACKGROUND

Certain immunotoxic peptides from gluten are resistant to gastrointestinal digestion and can interact with celiac-patient factors to trigger an immunologic response. A gluten-free diet (GFD) is the only effective treatment for celiac disease (CD), and its compliance should be monitored to avoid cumulative damage. However, practical methods to monitor diet compliance and to detect the origin of an outbreak of celiac clinical symptoms are not available.

OBJECTIVE

We assessed the capacity to determine the gluten ingestion and monitor GFD compliance in celiac patients by the detection of gluten and gliadin 33-mer equivalent peptidic epitopes (33EPs) in human feces.

DESIGN

Fecal samples were obtained from healthy subjects, celiac patients, and subjects with other intestinal pathologies with different diet conditions. Gluten and 33EPs were analyzed by using immunochromatography and competitive ELISA with a highly sensitive antigliadin 33-mer monoclonal antibody.

RESULTS

The resistance of a significant part of 33EPs to gastrointestinal digestion was shown in vitro and in vivo. We were able to detect gluten peptides in feces of healthy individuals after consumption of a normal gluten-containing diet, after consumption of a GFD combined with controlled ingestion of a fixed amount of gluten, and after ingestion of <100 mg gluten/d. These methods also allowed us to detect GFD infringement in CD patients.

CONCLUSIONS

Gluten-derived peptides could be sensitively detected in human feces in positive correlation with the amount of gluten intake. These techniques may serve to show GFD compliance or infringement and be used in clinical research in strategies to eliminate gluten immunotoxic peptides during digestion. This trial was registered at clinicaltrials.gov as NCT01478867.