Cytokines in inflammatory bowel disease

Inflammatory bowel disease (IBD) denotes chronic inflammatory disorders of gastrointestinal tract of unknown etiology that comprises 2 major groups: ulcerative colitis (UC) and Crohn's disease (CD). Disregulation of the intestinal immune system both at humoral and cellular level constitutes an important element in the multifactorial pathogenesis of IBD. The expression of pro-inflammatory cytokines, most notably IL-1, IL-6, TNF-alpha and chemokines (IL-8, ENA-78, MCP-1, RANTES) in intestinal mucosa from IBD patients is markedly enhanced, however, it is not always accompanied by increases in cytokines' serum levels. In IBD also significant changes occur in the tissue expression of immunoregulatory cytokines: increased levels of IL-2 mRNA and IFN-gamma mRNA, and decreased expression of IL-4 were found in affected intestinal mucosa. Chronic intestinal lesions of patients with Crohn's disease are associated with a Th1 type cytokine profile. The clinical effectiveness of anti-TNF-alpha antibodies and of IL-10 has been demonstrated in steroid-refractory Crohn's disease patients. The data demonstrating the role of cytokines in the pathogenesis of IBD should be carefully analyzed because of limitations imposed by the patient- and sample-related parameters. Further investigations will clarify the significance of the impairments in cytokine network for the initiation and progression of the IBD.