Inflammatory bowel disease–like conditions: other immune-mediated gastrointestinal disorders

Inflammatory bowel disease (IBD) with the primary two forms, Crohn’s disease and ulcerative colitis, has been considered as immune-mediated disorders (IMDs). IMDs,however, consist of a wide spectrum of gastrointestinal (GI) and extraintestinal disorders, in addition to the classic forms of IBD. Dysregulated innate and adaptive immunities are involved in IMDs. For example, abnormal innate immunity plays a major role in the pathogenesis of autoinflammatory diseases, while dysregulated adaptive immunity exerts the role in autoimmune enteropathy. There are overlaps in etiopathogenetic pathways, clinical presentations, endoscopic features, and histologic characteristics between classic IBD, autoimmune disorders, and autoinflammatory disorders. IMDs can be triggered by factors, such as bowel altering surgery and certain medications. Immune checkpoint inhibitors are known to cause IBD-like, immune-mediated colitis. The association between GI IMDs and extraintestinal IMDs is mutual and multi-persective.