Usefulness of recombinant γ-gliadin 1 for identifying patients with celiac disease and monitoring adherence to a gluten-free diet

• Published in: Journal of allergy and clinical immunology 2015-12, Vol.136 (6), p.1607-1618.e3
• Main Authors: Srinivasan, Bharani, PhD, Focke-Tejkl, Margarete, PhD, Weber, Milena, MSc, Pahr, Sandra, PhD, Baar, Alexandra, PhD, Atreya, Raja, MD, Neurath, Markus F., MD, Vogelsang, Harald, MD, Huber, Wolf-Dietrich, MD, Valenta, Rudolf, MD
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Allergy and Immunology; Amino Acid Sequence; Celiac disease; Celiac Disease - diagnosis; Celiac Disease - immunology; Child; Child, Preschool; cloning; Diet, Gluten-Free; epitope; Epitope Mapping; Escherichia coli; Escherichia coli - genetics; Female; Food, Drug, Insect Sting Allergy, and Anaphylaxis; Gliadin - genetics; Gliadin - immunology; Gliadin - metabolism; Hordeum vulgare; Humans; Immunoglobulin A - immunology; Immunoglobulin G - immunology; Infant; Male; Middle Aged; Molecular Sequence Data; Patient Compliance; recombinant gamma gliadin 1; Recombinant Proteins - genetics; Recombinant Proteins - immunology; Recombinant Proteins - metabolism; Triticum aestivum; Young Adult; Zea mays
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2015.04.040

Background Celiac disease (CD) is an inflammatory disease of the small intestine caused by an immunologic hypersensitivity reaction to dietary wheat gluten. Objectives We sought to clone, express, and perform IgA epitope mapping of a CD-specific wheat antigen and to study its usefulness for identifying patients with CD and monitoring adherence to a gluten-free diet. Methods A synthetic gene coding for γ-gliadin 1 (GG1) was expressed in Escherichia coli . Recombinant γ-gliadin 1 (rGG1) was purified and characterized biochemically, structurally, and immunologically by using sera from patients with CD and control subjects. Overlapping GG1 peptides were synthesized for IgA and IgG epitope mapping. GG1 and peptide-specific antibodies were raised for tracing GG1 in cereals and dietary wheat products and to study its resistance to digestion. Results rGG1 was expressed and purified. rGG1-based IgA ELISAs performed in populations of patients with CD and control subjects showed a specificity of 92.9%, which was higher than that of gliadin extract (e). Furthermore, it allowed monitoring of adherence to a gluten-free diet in patients. A 26-amino-acid peptide from the proline-glutamine–rich repetitive N-terminal region was identified as the immunodominant IgA epitope. GG1-related antigens were found in rye, barley, and spelt but not in oat, rice, or maize. GG1 was detected in dietary wheat products after baking, and in particular, the major IgA epitope–containing region was resistant against digestion. Conclusions rGG1 and its epitope might be useful for identifying patients with CD, monitoring treatment, and studying the pathomechanisms of CD and development of preventive and therapeutic strategies.