Alpha-Gliadin

Alpha-Gliadin

Alpha-Gliadin is a type of protein found in wheat and other related grains such as barley and rye. It is a component of gluten, which is a mixture of proteins that gives dough its elastic texture. Alpha-Gliadin is of particular interest in medical research due to its role in celiac disease, an autoimmune disorder.

Structure and Composition

Alpha-Gliadin is a prolamin, a group of plant storage proteins rich in proline and glutamine. These proteins are resistant to complete digestion by human gastrointestinal enzymes, which can lead to immune responses in susceptible individuals.

Role in Celiac Disease

Celiac disease is triggered by the ingestion of gluten in genetically predisposed individuals. The immune system mistakenly targets the small intestine's lining, leading to inflammation and villous atrophy. Alpha-Gliadin contains specific peptide sequences, such as the 33-mer peptide, that are resistant to digestion and can trigger this immune response.

Pathophysiology

When alpha-gliadin is ingested, it is partially digested in the gastrointestinal tract. The resulting peptides, particularly the 33-mer, are deamidated by the enzyme tissue transglutaminase (tTG). This modification enhances the binding of these peptides to HLA-DQ2 or HLA-DQ8 molecules on antigen-presenting cells, which then activate T-cells and initiate an inflammatory response.

Diagnosis and Testing

The diagnosis of celiac disease often involves serological tests for antibodies against tissue transglutaminase (tTG) and endomysium, as well as genetic testing for HLA-DQ2 and HLA-DQ8. A biopsy of the small intestine may be performed to confirm villous atrophy.

Treatment

The primary treatment for celiac disease is a strict gluten-free diet, which involves the elimination of all sources of gluten, including alpha-gliadin. This diet helps to heal the intestinal lining and alleviate symptoms.

Research and Developments

Research is ongoing to develop alternative treatments for celiac disease, such as enzyme supplements that can degrade gluten peptides, vaccines to induce immune tolerance, and genetically modified grains that lack immunogenic gliadin sequences.

See Also

• Gluten
• Celiac disease
• Tissue transglutaminase
• HLA-DQ2
• HLA-DQ8

References

• Fasano, A., & Catassi, C. (2012). Celiac disease. The New England Journal of Medicine, 367(25), 2419-2426.
• Schuppan, D., & Zimmer, K. P. (2013). The diagnosis and treatment of celiac disease. Deutsches Ärzteblatt International, 110(49), 835-846.