Stacia+Background+Information

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Celiac Disease: Background Information

Celiac Disease is a multifactoral autoimmune disorder that has a strong heritable component, triggered by ingesting a protein in wheat, called //gluten//. When someone has an autoimmune disorder, their immune system attacks the bodies own tissues (Fasano, 2009, p. 54). Gluten is a protein complex formed by glutenin and gliadin proteins. Gliadin is the active disease component and is rich in proline and glutamine causing it to be partially resistant to enzymatic proteolytic degradation (Galvan, 2009, p. 705).

Celiac Disease is caused not only by exposure to gluten, but by predisposing genes and abnormalities in the structure of the small intestine. Celiac Disease is triggered by the ingestion of wheat gluten or related rye and barley proteins in genetically susceptible individuals. British Physician Samuel Gee is credited as the modern father of Celiac Disease, although he did not quite understand the disease as his dietary prescription consisted of feeding children thinly sliced bread toasted on both sides. When agriculture started to become a huge source of food for much of the population, many people but mostly children started dying. Repeatedly eating these proteins eventually rendered sensitive individuals unable to properly absorb nutrients from food and caused abdominal pain and diarrhea. the identification of gluten as the main trigger for Celiac Disease happened after WWII when there was a shortage of bread in the Netherlands due to the war. This led to a significant drop in deaths among children. A Dutch pediatrician by the name of Willem-Karel Dicke made this connection (Fasano, 2009, p. 55).

Repeated exposure to gluten in Celiac Disease patients causes the villi in the small intestine to become chronically inflamed and damaged, so they are unable to carry out the normal function of breaking down food and shunting nutrients across the intestinal wall to the bloodstream. Gluten causes inflammation and intestinal damage by eliciting activity by various cells of the immune system. These cells harm healthy tissue in an attempt to destroy what they perceive to be an infectious agent. Our gastrointestinal system usually breaks down most undigested proteins into standard amino acids (Fasano, 2009, p. 56).

Gluten has a peculiar structure made up of mostly glutamine and proline. People affected by Celiac Disease have inherited a mix of genes that heightened immune sensitivity to gluten. For example, certain gene variants encoding proteins called Histocompatibility leukocyte antigens play a role (Bertini, 2009, p. 170). The majority of people affected by Celiac Disease present HLA-DQ2 and HLA-DQ8, where people without Celiac Disease typically possess either one or neither of the two. HLA-DQ2 and HLA-DQ8 proteins made by antigen-presenting cells take up foreign organisms and proteins, chop them up and fit the fragments into grooves on HLA molecules. They display the complexes on cells in reach of helper-t lymphocytes. Non-HLA genes however, have also been found to contribute to the disease (Bertini, 2009, p. 170-171).

A hallmark to the immune response to gluten is the production of antibody molecules targeted to an enzyme called tissue transglutaminase. This enzyme leaks out of damaged cells in the small intestine in attempts to heal the surrounding tissue. Tissue transglutaminase is released by intestinal epithelial cells which attach to undigested gluten and modifies the peptides so that they can bind extremely strong to HLA-DQ2 and HLA-DQ8. When intestinal epithelial cells release tissue transglutaminase, B cells ingest it and release antibodies targeted to the enzyme (Fasano, 2009, p. 56-57).

SYMPTOMS AND DIAGNOSIS:

Untreated Celiac patients often report symptoms of chronic fatigue with feelings of tiredness, muscle weakness, depression, and irritability (Bertini, 2009, p. 173).

The old diagnosis for Celiac Disease was to review the patient's symptoms, take a gut biopsy to confirm intestinal inflammation, and to see if a gluten-free diet relieved the patient of symptoms (Fasano, 2009, p. 56). Because of the newer findings of the antibody production caused by tissue transglutaminase, we have another way of detecting the presence of Celiac Disease in patients. If the antibodies are present in the patient's blood, it may simple to diagnose the disease. There is still an issue with this method, because the antibodies can be found in patients who do not have Celiac Disease as well.

Celiac Disease causes malabsorption of many necessary substances for life. For example, if someone is affected by Celiac Disease and they are not absorbing iron, then they may become anemic as well. If they have poor folate absorption, then this could lead to many neurological problems. Celiac Disease can produce symptoms such as osteoporosis, joint pain, chronic fatigue, skin lesions, epilepsy, dementia, schizophrenia and seizures (Bertini, 2009, p. 171).

Although untreated symptomatic Celiac Disease can be associated with the result being death, clinical and histological improvement are usually seen when following a strict gluten-free diet. Until recently, Celiac Disease has been considered to be a rare disease, but with many screening studies, we are seeing that it is much more common than once thought, affecting 1% of the population in both North America and Europe (Fasano, 2009, p. 56).

Celiac Disease is a great model for understanding autoimmune diseases and disorders because it is the only example where adding or taking away a simple environmental component can turn the disease process on and off. It is associated with many other autoimmune disorders such as type 1 diabetes, autpimmune thyroiditis, ad Addison's Disease. All autoimmune disorders have three major pinpoints: they all have an environmental substance presented to the body, genetically based tendency of the immune system to overreact to substances, and an unusually permeable gut (Fasano, 2009, p. 58-59).

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