IgA anti-tissue transglutaminase antibodies and IgG antibodies against deamidated gliadin peptides as predictors of celiac disease

Mode of presentation and performance of serology assays for diagnosing celiac disease: A single-center study in the United Arab Emirates

Objective

To characterize patients with celiac disease (CD), examines the clinical spectrum of CD, and evaluate the performance of serologic tests used for CD screening, in the United Arab Emirates (UAE).

Methods

Medical charts of patients received at the Digestive Diseases Institute of Cleveland Clinic Abu Dhabi from January 2015 to December 2020 were reviewed. Patients who were screened for four serologic biomarkers (anti-tissue transglutaminase IgA [Anti-tTG-IgA], anti-tissue transglutaminase IgG [Anti-TtG-IgG], anti-deamidated gliadin peptide IgG [Anti-DGP-IgG], and anti-deamidated gliadin peptide IgA [Anti-DGP-IgA]) were included. Histopathology was performed on patients with the seropositive test. Marsh score > 1 considered to confirm CD. Characteristics of the Anti-tTG-IgA seropositive patients were described and that correlated with histopathologically confirmed CD were explored.

Results

Of the 6,239 patients, 1.4, 2.9, 4.7, and 4.9%, were seropositive to Anti-tTG-IgG, Anti-TtG-IgA, Anti-DGP-IgA, and Anti-DGP-IgG, respectively. Overall, 7.7% were seropositive to either of the four biomarkers. Of the biopsy-screened 300 patients, 38.7% (1.9% of the total serologically screened) were confirmed with CD. The mean age of Anti-TtG-IgA seropositive patients was 32.1 ± 10.3 SD years, 72% of them were females, and 93.4% were Emirati. In those patients, overweight (28.7%) and obesity (24.7%) were common while 5.8% of patients were underweight. Anemia prevalence was 46.7%, 21.3% had Gastroesophageal reflux disease (GERD), 7.7% with autoimmune thyroid disease, 5.5% (type 1), and 3.3% (type 2) were diabetic. Vitamin D deficiency was observed in 47.8% of the Anti-TtG IgA seropositive patients. Twelve (10.3%) histopathologically confirmed CD patients were seronegative to Anti-TtG-IgA but seropositive to anti-DGP-IgA and/or Anti-DGP-IgG. Body mass index, GERD, autoimmune thyroid disease, type 1 diabetes, asthma, hemoglobin, and vitamin D concentration, were all correlated with biopsy-confirmed CD (P < 0.05). Compared to the gold-standard biopsy test, Anti-TtG-IgA had the highest sensitivity (89.7%) and specificity (83.7%).

Conclusion

Three and two of every 100 patients were serologically (anti-tTG-IgA positive) and histopathologically diagnosed with CD, respectively. Although Anti-TtG-IgA is the most sensitive, specific, and commonly used test, one of every ten histopathologically confirmed patients and Anti-tTG-IgA seronegative were seropositive to Anti-DGP. To avoid missing patients with CD, a comprehensive serological investigation covering DGP-IgG/IgA is warranted.

Autoantibodies - enemies, and/or potential allies?

Autoantibodies are well known as potentially highly harmful antibodies which attack the host via binding to self-antigens, thus causing severe associated diseases and symptoms (e.g. autoimmune diseases). However, detection of autoantibodies to a range of disease-associated antigens has enabled their successful usage as important tools in disease diagnosis, prognosis and treatment. There are several advantages of using such autoantibodies. These include the capacity to measure their presence very early in disease development, their stability, which is often much better than their related antigen, and the capacity to use an array of such autoantibodies for enhanced diagnostics and to better predict prognosis. They may also possess capacity for utilization in therapy, in vivo. In this review both the positive and negative aspects of autoantibodies are critically assessed, including their role in autoimmune diseases, cancers and the global pandemic caused by COVID-19. Important issues related to their detection are also highlighted.

Association between intestinal neoplasms and celiac disease: A review

Celiac disease (CD) is a chronic immune-mediated intestinal disease with genetic susceptibility. It is characterized by inflammatory damage to the small intestine after ingestion of cereals and products containing gluten protein. In recent years, the global prevalence rate of CD has been approximately 1%, and is gradually increasing. CD patients adhere to a gluten-free diet (GFD) throughout their entire life. However, it is difficult to adhere strictly to a GFD. Untreated CD may be accompanied by gastrointestinal symptoms, such as diarrhea, abdominal pain, and extraintestinal symptoms caused by secondary malnutrition. Many studies have suggested that CD is associated with intestinal tumors such as enteropathy-associated T-cell lymphoma (EATL), small bowel cancer (SBC), and colorectal cancer. In this study, we reviewed related studies published in the literature to provide a reference for the prevention and treatment of intestinal tumors in patients with CD. Compared with the general population, CD patients had a high total risk of SBC and EATL, but not colorectal cancer. The protective effect of GFD on CD-related malignancies is controversial. Further studies are needed to confirm whether GFD treatment can reduce the risk of intestinal neoplasms in CD.