Gliadin

Gliadin is a class of proteins present in wheat and several other cereals within the grass genus Triticum. Gliadins, which are a component of gluten, are essential for giving bread the ability to rise properly during baking. Gliadins and glutenins are the two main components of the gluten fraction of the wheat seed. This gluten is found in products such as wheat flour. Gluten is split about evenly between the gliadins and glutenins, although there are variations found in different sources.

Gliadin is the water-soluble component of gluten, while glutenin is insoluble.[1] There are three main types of gliadin (α, γ, and ω), to which the body is intolerant in coeliac (or celiac) disease. Diagnosis of this disease has recently been improving.

Gliadin can cross the intestinal epithelium. Breast milk of healthy human mothers who eat gluten-containing foods presents high levels of non-degraded gliadin.[2][3]

Types

The α, γ, and ω gliadin types are separated and distinguished based on their amino acid sequences.[4]

Biochemistry

Gliadins are prolamins and are separated on the basis of electrophoretic mobility and isoelectric focusing.

Metabolism

Gliadins are known for their role, along with glutenin, in the formation of gluten. They are slightly soluble in ethanol and contain only intramolecular disulfide links. They also cause some of the best examples of food-derived pathogenesis. People with gluten-sensitive enteropathy (the severe form of which is celiac disease) are sensitive to α, β, and γ gliadins. Those with WD urticaria and Baker's asthma are sensitive to ω-gliadins.

Tissue transglutaminase

Gliadin can also serve as a useful delivery method for sensitive enzymes (such as superoxide dismutase, which is fused with gliadin to form glisodin) – this helps protect them from stomach acids that cause breakdown.

For useful description of the gliadins see:

Deamidated gliadin

Deamidated gliadin is produced by acid or enzymatic treatment of gluten. The enzyme tissue transglutaminase converts some of the abundant glutamines to glutamic acid. This is done because gliadins are soluble in alcohol and cannot be mixed with other foods (like milk) without changing the foods' qualities. Deamidated gliadin is soluble in water. The cellular immunity to deamidated α-/β-gliadin is much greater than α/β-gliadin and can result in symptomatic gluten-sensitive enteropathy.

Celiac disease

Main article: Coeliac disease

Celiac disease is a chronic, immune-mediated intestinal disorder, in which the body becomes intolerant to gliadin, which is a component of gluten.[5] Individuals with celiac disease exhibit a lifelong intolerance of wheat, barley and rye – all of which contain gliadins.[6] Gliadin proteins have the ability to provoke an autoimmune enteropathy caused by an abnormal immune response in genetically susceptible individuals. Specific amino acid sequences within the gliadin proteins are responsible for this activity.[6][7]

The main problems with this disease is that it often goes unrecognized for many years, in which it can cause serious damage to several organs,[8] and most cases currently remain unrecognized, undiagnosed and untreated.[9][10][11][12] Celiac disease with “non-classic symptoms” is the most common clinical type and occurs in older children (over 2 years old), adolescents and adults.[8] It is characterized by milder or even absent gastrointestinal symptoms and a wide spectrum of non-intestinal manifestations that can involve any organ of the body, and very frequently may be completely asymptomatic[11] both in children (at least in 43% of the cases[13]) and adults.[11] Untreated celiac disease may cause malabsorption, reduced quality of life, iron deficiency, osteoporosis, an increased risk of intestinal lymphomas and greater mortality.[14] It is associated with some autoimmune diseases, such as diabetes mellitus type 1, thyroiditis,[15] gluten ataxia, psoriasis, vitiligo, autoimmune hepatitis, dermatitis herpetiformis, primary sclerosing cholangitis, and more.[15]

The only available treatment for celiac disease is a strict gluten-free diet in which the diseased person does not ingest any gluten. There have been searches for an affordable and much better treatment, but the only treatment remains to abstain from ingesting any gluten.[8]

See also

References

  1. ↑ Ribeiro, Miguel; Nunes-Miranda, Júlio D.; Branlard, Gérard; Carrillo, Jose Maria; Rodriguez-Quijano, Marta; Igrejas, Gilberto (2013-11-01). "One hundred years of grain omics: identifying the glutens that feed the world". Journal of Proteome Research. 12 (11): 4702–4716. doi:10.1021/pr400663t. ISSN 1535-3907. PMID 24032428.
  2. ↑ Bethune MT, Khosla C (Feb 2008). "Parallels between pathogens and gluten peptides in celiac sprue". PLoS Pathog. 4 (2): e34. doi:10.1371/journal.ppat.0040034. PMC 2323203Freely accessible. PMID 18425213.
  3. ↑ Chirdo FG, Rumbo M, Añón MC, Fossati CA (Nov 1998). "Presence of high levels of non-degraded gliadin in breast milk from healthy mothers". Scand J Gastroenterol. 33 (11): 1186–92. doi:10.1080/00365529850172557. PMID 9867098.
  4. ↑ CID 17787981 from PubChem
  5. ↑ Mowat, AM (2003). "Coeliac disease--a meeting point for genetics, immunology, and protein chemistry". Lancet. 361 (9365): 1290–2. doi:10.1016/S0140-6736(03)12989-3. PMID 12699968.
  6. 1 2 McGough, Norma; Cummings, John H. (2005-11-01). "Coeliac disease: a diverse clinical syndrome caused by intolerance of wheat, barley and rye". The Proceedings of the Nutrition Society. 64 (4): 434–450. ISSN 0029-6651. PMID 16313685.
  7. ↑ Ciccocioppo, R.; Di Sabatino, A.; Corazza, G. R. (2005-06-01). "The immune recognition of gluten in coeliac disease". Clinical and Experimental Immunology. 140 (3): 408–416. doi:10.1111/j.1365-2249.2005.02783.x. ISSN 0009-9104. PMID 15932501.
  8. 1 2 3 Ludvigsson JF, Card T, Ciclitira PJ, Swift GL, Nasr I, Sanders DS, Ciacci C (Apr 2015). "Support for patients with celiac disease: A literature review". United European Gastroenterol J. 3 (2): 146–59. doi:10.1177/2050640614562599. PMC 4406900Freely accessible. PMID 25922674.
  9. ↑ Lundin KE, Wijmenga C (Sep 2015). "Coeliac disease and autoimmune disease-genetic overlap and screening". Nat Rev Gastroenterol Hepatol. 12 (9): 507–15. doi:10.1038/nrgastro.2015.136. PMID 26303674.
  10. ↑ Lionetti E, Gatti S, Pulvirenti A, Catassi C (Jun 2015). "Celiac disease from a global perspective". Best Pract Res Clin Gastroenterol (Review). 29 (3): 365–79. doi:10.1016/j.bpg.2015.05.004. PMID 26060103.
  11. 1 2 3 Fasano A (Apr 2005). "Clinical presentation of celiac disease in the pediatric population". Gastroenterology. 128 (4 Suppl 1): S68–73. doi:10.1053/j.gastro.2005.02.015. PMID 15825129.
  12. ↑ Elli L, Branchi F, Tomba C, Villalta D, Norsa L, Ferretti F, Roncoroni L, Bardella MT (Jun 2015). "Diagnosis of gluten related disorders: Celiac disease, wheat allergy and non-celiac gluten sensitivity". World J Gastroenterol. 21 (23): 7110–9. doi:10.3748/wjg.v21.i23.7110. PMC 4476872Freely accessible. PMID 26109797.
  13. ↑ Vriezinga SL, Schweizer JJ, Koning F, Mearin ML (Sep 2015). "Coeliac disease and gluten-related disorders in childhood". Nature Reviews. Gastroenterology & Hepatology (Review). 12 (9): 527–36. doi:10.1038/nrgastro.2015.98. PMID 26100369.
  14. ↑ Lebwohl B, Ludvigsson JF, Green PH (Oct 2015). "Celiac disease and non-celiac gluten sensitivity". BMJ (Review). 351: h4347. doi:10.1136/bmj.h4347. PMC 4596973Freely accessible. PMID 26438584.
  15. 1 2 Lundin KE, Wijmenga C (Sep 2015). "Coeliac disease and autoimmune disease-genetic overlap and screening". Nat Rev Gastroenterol Hepatol. 12 (9): 507–15. doi:10.1038/nrgastro.2015.136. PMID 26303674.

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