Application of Deamidated Gliadin Antibodies in the Follow-Up of Treated Celiac Disease

Abstract

Introduction: The role of serological tests such as IgA anti-transglutaminase autoantibodies has become increasingly important in celiac disease (CD) diagnosis. However, the efficiency of these tests for patient follow-up is controversial. We investigated the correlation of 12 different serological tests, including recent deamidated gliadin and actin IgA tests, with villous atrophy (VA) in a retrospective cohort of treated celiac patients.

Materials and methods: Serum samples were collected from 100 treated CD patients who had intestinal biopsy in the course of their follow-up. Antibodies against transglutaminase, deamidated gliadin peptides, and native gliadin were measured, along with IgA anti-actin. The biopsy slides were all blind-reviewed and scored according to Marsh classification.

Results: For all deamidated gliadin and transglutaminase tests, we found that a positive result was significantly associated with persistence of intestinal VA, with a diagnostic efficacy up to 80%. Furthermore, antibodies titers directly correlated with the degree of VA, indicating a strong link between disease activity and presence of antibodies in the serum. Interestingly, the tests with the highest association with persistent VA were those for deamidated gliadin IgG. Using a test positivity pattern analysis, we were also able to identify several groups of patients with distinct antibody profiles that showed significant differences in intestinal damage and diet compliance.

Conclusions: Altogether, these results show that deamidated gliadin antibodies are strongly correlated with VA and should be considered valuable tools in CD follow-up and that multiplex serologic analysis for treated CD represents a promising tool for personalized patient management.

Fig 1. Adaptation of serological tests to treated CD patients.

ROC curve analysis was performed on treated celiac patients by plotting sensitivity against 100-specificity for all test values. The presence of VA was used as the positivity criteria. The area under curve (AUC) and its statistical significance were calculated for each curve and are summarized in Table 3.

Fig 2. Association of serological tests with degree of intestinal damage.

Antibody titers for each test were plotted for groups of patients with different intestinal damage as defined by the Marsh score. The horizontal line represents the median titer for each test. (*): the titers rise significantly with degree of intestinal damage (Kruskal-Wallis and Cuzick trend tests). (+): the titers are significantly higher in severe versus partial atrophy groups (Mann-Whitney test). (#): the titers are significantly higher in subnormal versus normal biopsy groups (Mann-Whitney test).

Fig 3. Analysis of antibody positivity profile.

(a): Percentage of positive tests (Mean ±SEM) for each patient group. (b): Unsupervised hierarchical clustering of serological data. Each square represents the result of one test (lines) for one patient (columns), while its color represents the positivity level of the test. The test titers were normalized by calculating the ratio between titer and cut-off. Antibody titers close to cut-off values are represented by yellow squares, titers below cut-off range from yellow (cut-off) to green (very low titers) and titers above cut-off range from yellow (cut-off) to red (very high titers). (c): Proportion of histological scores in the patient clusters. (d): Unsupervised hierarchical clustering of serological data restricted to patients with partial atrophy (Marsh 3a).

Fig 4. Correlation of patient clusters with gluten intake.

Proportion of patients with significant gluten intake, GFD for less than 2 years, GFD for more than 2 years in antibody-defined patient clusters A, B and C, calculated in Fig 3(A): All clustered patients, (b): Partial atrophy (Marsh 3a) patients.