Coeliac Disease - New Pathophysiological Findings and Their Implications for Therapy

Gliadin Sequestration as a Novel Therapy for Celiac Disease: A Prospective Application for Polyphenols

Celiac disease is an autoimmune disorder characterized by a heightened immune response to gluten proteins in the diet, leading to gastrointestinal symptoms and mucosal damage localized to the small intestine. Despite its prevalence, the only treatment currently available for celiac disease is complete avoidance of gluten proteins in the diet. Ongoing clinical trials have focused on targeting the immune response or gluten proteins through methods such as immunosuppression, enhanced protein degradation and protein sequestration. Recent studies suggest that polyphenols may elicit protective effects within the celiac disease milieu by disrupting the enzymatic hydrolysis of gluten proteins, sequestering gluten proteins from recognition by critical receptors in pathogenesis and exerting anti-inflammatory effects on the system as a whole. This review highlights mechanisms by which polyphenols can protect against celiac disease, takes a critical look at recent works and outlines future applications for this potential treatment method.

[Celiac disease : Pathogenesis, clinics, epidemiology, diagnostics, therapy]

Celiac disease is induced by the consumption of gluten containing cereals (wheat, spelt, barley, rye). With a prevalence of ~ 1 %, it is the most common non-infectious chronic inflammatory intestinal disease worldwide. It manifests in all age groups, either classically with abdominal pain, diarrhoea and growth failure or weight loss, more commonly with indirect consequences of malabsorption, such as anaemia and osteoporosis, or with associated autoimmune diseases like type 1 diabetes, autoimmune thyroiditis or dermatitis herpetiformis. The pathogenesis of celiac disease is well explored. Gluten, the cereal storage protein, is not completely digested and reaches the intestinal mucosa where it activates inflammatory T cells, which cause atrophy of the resorptive villi. This T‑cell activation requires a genetic predisposition (the molecules HLA-DQ2 or -DQ8 on antigen-presenting immune cells). Moreover, the enzyme tissue transglutaminase (TG2) which is released in the mucosa increases the immunogenicity of the gluten peptides by a deamidation reaction. The test for serum antibodies to the autoantigen TG2 is one of the best diagnostic markers in medicine, which in combination with endoscopically obtained biopsies, secures the diagnosis of celiac disease. Despite these tools celiac disease is severely underdiagnosed, with 80-90 % of those affected being undetected. The untreated condition can lead to grave complications. These include the consequences of malabsorption, cancers (especially intestinal T‑cell lymphoma), and likely also the promotion of autoimmune diseases. The therapy of celiac disease, a strict gluten-free diet, is difficult to maintain and not always effective. Alternative, supporting pharmacological therapies are urgently needed and are currently in development.

The Pathophysiology of Malabsorption

Physiological digestion and absorption of nutrients within the gastrointestinal tract requires a complex interaction between motor, secretory, digestive, and absorptive functions that is vulnerable to a multitude of potential disturbances which may lead to global or specific malabsorption syndromes. Potential pathomechanisms that are illustrated in this article include insufficient mechanical breakdown of harder food components due to chewing problems and/or decreased antral contractility, critical reduction of time for absorption in patients with markedly enhanced upper gastrointestinal transit (e.g. dumping syndrome), impaired digestion and absorption of nutrient components caused by reduced gastric acid secretion, pancreatic exocrine insufficiency or reduced biliary secretion, defects of the enteral mucosa with enzyme deficiencies (e.g. disaccharidases) or lack of specific carrier mechanisms (e.g. hexose or aminoacid transporters), and critical quantitative loss of intestinal mucosa in patients with short bowel syndrome.