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ibd

inflammatory bowel disease (IBD)

introduction

  • inflammatory bowel disease is the generic term for a range of “autoinflammatory” diseases including:
    • microscopic colitis:
      • more common in older adults (50-70 years old) and women
      • normal colonoscopy appearance
      • may have higher rates of autoimmune disorders like celiac disease, thyroid disorders, and rheumatoid arthritis
      • Rx options include dietary changes, anti-diarrheal medications, and anti-inflammatory drugs like budesonide. Most people respond well to treatment.
      • types:
        • lymphocytic colitis
        • collagenous colitis

pathogenesis

  • mechanisms are not well understood as yet
  • Hepworth et al 1) propose the following mechanism:
    • a subset of innate lymphoid cells called ILC3 cells which normally reside in the lamina propria of the bowel and in mesenteric lymph nodes, selectively kill CD4 T cell lymphocytes that are capable of responding to bacterial antigen originating from the gut.
    • normally these ILC3 cells prevent the immune system from mounting an inflammatory response to these non-pathogenic bacteria gut flora in a similar way as thymic medullary epithelial cells or dendritic cells of the thymus kill off specific CD4 T cells to reduce the risk of auto-immune diseases
    • biopsies of children with Crohn's disease reveal a deficiency in the expression of ILC3-instrinsic MHC class II suggesting this could be a key component of the pathogenesis

pharmacologic Rx options

  • sulphasalazine (salazopyrine)
  • TNF antagonists
  • monoclonal antibodies to integrin:
    • iv vedolizumab every 8wks (introduced in Australia in 2015)
1)
NEJM 373;24 Dec 10 2015 and Science 2015; 348:1031-5;
ibd.txt · Last modified: 2024/07/12 23:58 by gary1

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