Crohn's Disease

• Crohn's disease


  An inflammatory bowel disease that causes inflammation of the bowel
• Crohn's disease


  • Unlike ulcerative colitis, it affects the entire gastrointestinal tract, from the mouth to the anus
  • Not technically classified as an autoimmune disease, but rather an immune-related disorder
• Autoimmune disease


  The immune system attacks the body's own cells and proteins
• Immune-related disorder


  The immune system is triggered by some foreign pathogen in the gastrointestinal tract
• Pathogens implicated in Crohn's disease

  • Mycobacterium paratuberculosis
  • Pseudomona
  • Listeria species
• Immune response in Crohn's disease


  1. Antigen presentation

  2. T helper cells release cytokines

  3. Inflammatory cells like macrophages release inflammatory substances

  4. Unregulated inflammation causes tissue destruction
• Immune response in Crohn's disease


  • Dysfunctional and leads to an unregulated and out-of-control inflammatory response
• Genetics


  Patients with family members that have Crohn's disease are much more likely to develop it themselves
• NOD2 gene (CARD15)


  A frameshift mutation in this gene is thought to contribute to developing Crohn's disease
• Intestinal wall


  • Has ridges and grooves, and can be separated into mucosal, submucosal, muscle, and serosa layers
  • Defect in the epithelial barrier may allow pathogens to more easily penetrate
• Crohn's disease


  • Inflammation and damage extends beyond the submucosal layer and through the entire depth of the intestinal wall (transmural)
  • Areas of inflammation are scattered with healthy tissue interspersed, giving a "cobblestone appearance"
  • Can affect any part of the GI tract, most commonly the ileum and colon