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Inflammatory bowel disease: autoimmune or immune-mediated pathogenesis?
Zhonghui Wen1, Claudio Fiocchi
1Division of Gastroenterology, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4952, USA.
Clinical & Developmental Immunology
|November 24, 2004
Summary
The exact causes of inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), remain unknown. Research suggests a loss of tolerance to gut bacteria, involving immune system abnormalities, triggers these conditions.
Area of Science:
- Immunology
- Gastroenterology
- Pathogenesis of Inflammatory Bowel Disease
Background:
- Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), involves complex autoimmune and immune-mediated processes.
- Specific autoantibodies (e.g., anti-tropomyosin in UC, ASCA in CD, pANCA in UC) and general immune dysregulation against gut bacteria are observed in IBD patients.
Purpose of the Study:
- To elucidate the unclear pathogenesis of Crohn's disease and ulcerative colitis.
- To highlight the roles of autoimmune phenomena and immune-mediated responses in IBD development.
Main Methods:
- Review of existing literature on autoimmune and immune-mediated aspects of IBD.
- Analysis of autoantibody profiles (pANCA, ASCA) and immune reactivity to enteric flora.
Main Results:
- IBD pathogenesis involves both autoimmune markers and immune-mediated abnormalities.
- A generalized heightened reactivity against intestinal bacterial antigens is present in both CD and UC.
- Loss of tolerance to the indigenous enteric flora is considered a central event in IBD.
Conclusions:
- The central event in IBD pathogenesis is likely a loss of tolerance to commensal gut bacteria.
- Factors contributing to this loss of tolerance include regulatory T-cell defects, dendritic cell stimulation, infections, and genetic variations (e.g., NOD2/CARD15 mutations).