Celiac Disease: An Overview

• Celiac disease is an inflammatory disease affecting the small bowel, causing mucosal lesions
• It stems from an immune reaction triggered by gluten consumption in genetically susceptible individuals
• Gluten contains gliadin, found in wheat, barley, and rye
• This leads to gastrointestinal malabsorption with symptoms like diarrhea, constipation, abdominal pain, and distention
• Affects 1–2% of adults across all ages but more common in women in their 30's and 40's
• Diagnosing can be difficult
• CT and MR enterography are noninvasive techniques used to assess small bowel abnormalities, including celiac disease

Introduction to Celiac Disease

• Celiac disease is an inflammatory condition where the small bowel experiences villi loss in the proximal part.
• The disease is triggered by gluten intake among genetically predisposed individuals by immune response
• Symptoms are gastrointestinal malabsorption causing abdominal pain and distention
• Diagnosis requires biopsy for confirmation, revealing increased intraepithelial lymphocytes (IELs), crypt hyperplasia, and villous atrophy
• CT and MR enterography reveal essential information, including abnormal fold patterns and mesenteric lymphadenopathy, among other imaging features

Epidemiology and Risk Factors

• Celiac disease has a general adult population prevalence of 1%-2%
• 0.2% to 1% is the prevalence in children from US studies
• Europe has approximately 3 million affected people, with at least 3 million in the United States
• The disease is relatively common in Asia, approximately 1.5%
• Women are more likely to have this in their 3rd or 4th decade of life, approximately 2:1 to 3:1
• The global distribution is affected by human leukocyte antigen (HLA) genotypes when exposed to gluten
• Recognized celiac disease cases are just a small amount of the total patients
• Siblings have 8.9% prevalence, children at 7.9%, and parents at 3%
• Celiac disease is associated with type 1 diabetes and Hashimoto thyroiditis and can affect autoimmune liver and muscular function

Gluten Sensitivity

• Gluten sensitivity entities show intestinal symptoms in those unaffected by celiac disease
• Non-celiac gluten sensitivity (NCGS) or wheat allergy patients do not suffer from the autoimmune process that causes intestinal epithelial cell damage
• High suspicion of celiac required because its often not diagnosed

Pathogenesis of Celiac Disease

• Triggered in individuals with genetic predispositions by consuming gluten proteins from grains
• Linked to HLA-DR3/DQ2 and HLA-DR4/DQ8 gene loci
• Digestion by host/microbial enzymes then transported to lamina propria
• Activated transglutaminase 2 (TG2) deamidates glutamine residues on gluten peptides
• Gluten peptide binding improved to HLA-DQ2 or HLA-DQ8 grooves of antigen-presenting cells
• Autoantibodies produced by TG2-gluten which serves as a diagnostic tool
• Proinflammatory mediators such as interferon γ secreted by T-helper cells
• B cells Release deamidated gluten peptides binding to HLA-DQ2 or HLA-DQ8 activating gluten-specific T cells
• Infectious/inflammatory markers and HLA class I in intestinal epithelial cells upregulated by signals
• Intestinal epithelial cells interact through natural killer cell receptors via intraepithelial lymphocytes (IELs)
• IL-15 cytokine drives IEL cytotoxicity, mucosal destruction, and intestinal atrophy

Clinical Manifestations and Diagnosis

• Symptoms can be nonspecific
• Symptoms include diarrhea, abdominal pain, bloating, vomiting, anemia, or osteoporosis
• Definitions related to celiac disease include classic, nonclassic, subclinical, refractory, latent, and potential forms
• American College of Gastroenterology (ACG) suggests testing with biopsy-confirmed disease, even with no symptoms
• Diagnosis involves pathologic small bowel changes plus serologic test results
• First-line test is IgA tissue transglutaminase antibody test, with 95% sensitivity and specificity
• False-negative results may occur with IgA deficiency, necessitating an immunoglobulin-G antideamidated gliadin peptide test
• ACG also advises serologic screening for asymptomatic first-degree relatives of celiac patients
• Tissue sampling required during endoscopic small bowel biopsy for adults with positive serologic results to confirm
• Testing should be considered if patients are using corticosteroids which can affect the testing accuracy

Extraintestinal Manifestations

• Mucocutaneous features dermatitis herpetiformis, eczema, psoriasis, or atrophic glossitis
• Metabolic bone disorders causes calcium and vitamin D malabsorption increasing the risk of fractures
• Hematologic causes hemorrhage increasing the risk of iron deficiency anemia
• Neurologic from nutritional, immunologic, toxic, and metabolic disturbances
• Can cause headaches, anxiety, depression, ataxia, epilepsy, and peripheral neuropathy

Imaging features of Celiac Disease

• Wide range of intestinal and extraintestinal imaging findings due to severity
• Intestinal fold pattern abnormalities, destruction, flattening of mucosa leads to patterns
• Fold patterns, square ends of folds with squared margins, jejunal inversion and total fold abscense
• MR enterography can be used on patients with lower kidney function
• Mucosal recovery after treatment with a gluten-free diet depends on the severity at treatment
• First imaging can be intestinal fold and wall thickening
• In optimal Luminal Distinction, they can be defined as more than 3mm in thickness and diameter