ABSTRACT
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gastrointestinal (GI) tract. IBD is most prevalent in North America and Europe (1.4 and 2.2 million sufferers, respectively)1 while other, previously low-incidence areas have reported an increased occurrence in recent years.2 Environmental factors, such as diet and degree of sanitation, are believed to play a role in the development of IBD.3 There is also a large body of evidence suggesting a genetic predisposition to IBD, with genes such as CARD15/NOD2, OCTN1 and 2, and DLG5 all linked to the development of IBD.4 The role of genetics has been comprehensively reviewed by Henckaerts and colleagues.3 Although the exact etiology of IBD remains unknown, it is believed to be the result of a dysfunctional interaction between the gut microbiota and the mucosal immune system.6 While many speculate both CD and UC may be instigated by similar mechanisms, there are a number of differences between the two conditions. UC occurs primarily in the colon, extending proximally from the rectum.7,8 It is characterized by continuous inammation of the colon, super-cial mucosal inammation, increased neutrophil presence in the lamina propria and crypts, and the production of proinammatory mediators such as interleukin (IL)-12 and tumor necrosis factor (TNF)-α.9,10 CD is characterized by the aggregation of macrophages which promotes the formation of noncaseating granulomas.11 In contrast to UC, CD can occur in any region of the GI tract, but is most common in the terminal ileum.7 CD lesions often present as patchy, typically transmural, inammation.12 In addition to UC and CD, other conditions including collagenous colitis, lymphocytic colitis, and Behçet’s syndrome are classied as IBD. Symptoms of IBD include abdominal pain, GI bleeding, malnutrition, and bloody diarrhea13; extraintestinal manifestations have also been reported, and can include disorders of the liver, lungs, eyes, and joints.14 The mortality rates are 1.4 percent and 1.0 percent for CD and UC, respectively.7 Common therapies for IBD, including 5-aminosalicylates, antibiotics, steroids, and growth factors, have been comprehensively reviewed by Kozuch and Hanauer.11
