SEARCH RESULTS FOR: microscopic-colitis-pathogenesis-and-clinical-findings

microscopic-colitis-pathogenesis-and-clinical-findings

Microscopic Colitis: Pathogenesis and clinical findings Genetic Author: Tony Gu, Kayleigh Yang Reviewers: Yoyo Chan, Vina Fan, Ben Campbell, Dr. Edwin Cheng* * MD at time of publication Release of cytokines (e.g. interferon gamma (IFNγ)) Downregulation of intestinal tight junction proteins ↓ Epithelial barrier function ↑ Transmucosal permeability Infiltration of bacteria or antigens ↑ Expression of nuclear factor kappa B (NF-kB) in colonic epithelial cells NF-kB increases transcriptional activity in specific genes ↑ Inflammatory molecules (histamine, prostaglandins, and nitric oxide) in epithelium predisposition Unknown trigger ↑ Transforming growth factor beta 1 (TGF- β1) and vascular endothelial growth factor (VEGF) expression in colonic epithelial cells Equilibrium shift to more production of collagen (fibrinogenesis) than breakdown (fibrinolysis) Drug exposure (e.g., non- steroidal anti- (+) inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs)) Inflammation and accumulation of immature subepithelial collagen matrix Subtype: Collagenous Colitis Intestinal mucosal inflammation Subtype: Lymphocytic Colitis characterized by a colonic subepithelial characterized by intraepithelial collagen band on histology lymphocytic infiltrates on histology Microscopic Colitis Intestinal epithelial damage Malabsorption of nutrients (including bile acids) Weight loss ↑ Intestinal transmucosal permeability Water drawn into lumen through osmosis Ions and water back leak into intestinal lumen Non-bloody watery diarrhea Dehydration and electrolyte disturbances Continuous release of inflammatory mediators Peripheral afferent nerve sensitization Visceral hypersensitivity Abdominal pain Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 8, 2018, Updated October 18, 2022 on www.thecalgaryguide.com