Therapeutic effect of urocortin and adrenomedullin in a murine model of Crohn's disease.

Urocortin 1 (UCN) and adrenomedullin (AM) are two recently discovered neuropeptides that, due to their distribution and binding to receptors in immune cells, have emerged as potential endogenous anti-inflammatory factors. Crohn's disease is a chronic debilitating disease characterised by a Th1 driven severe inflammation of the gastrointestinal tract. This study investigated the therapeutic effect of UCN and AM in a murine model of colitis. Treatment with UCN or AM ameliorated significantly the clinical and histopathological severity of the inflammatory colitis, abrogating body weight loss, diarrhoea, and inflammation, and increased the survival rate of colitic mice. The therapeutic effect was associated with downregulation of both inflammatory and Th1 driven autoimmune responses, including regulation of a wide spectrum of inflammatory mediators. In addition, partial involvement of interleukin 10 secreting regulatory cells in this therapeutic effect was demonstrated. Importantly, UCN or AM treatments were therapeutically effective in established colitis and avoided recurrence of the disease. This work identifies UCN and AM as two potent anti-inflammatory factors with the capacity to deactivate the intestinal inflammatory response and restore mucosal immune tolerance at multiple levels. Consequently, both peptides represent novel multistep therapeutic approaches for the treatment of Crohn's disease and other Th1 mediated inflammatory diseases.