Review article: potential therapeutic applications and mechanisms of action of heparin in inflammatory bowel disease

Unfractioned heparin was recently reported to be beneficial in the treatmen t of inflammatory bowel disease. The available uncontrolled data show that it may be effective in steroid-resistant ulcerative colitis with a percenta ge of complete clinical remission of over 70% after an average of 4-6 weeks of therapy. The administration of unfractioned heparin is not currently ju stified by the very limited available data. The worsening of rectal bleeding is infrequent in treated ulcerative coliti s patients and only rarely does it require blood transfusion or a colectomy . Low molecular weight heparin was used in a single trial in patients with steroid-refractory ulcerative colitis, with results similar to those observ ed with unfractioned heparin. Since a prothrombotic state has been described in inflammatory bowel diseas e, and microvascular intestinal occlusion seems to play a role in the patho genesis of inflammatory bowel disease, it is reasonable that part of the be neficial effects of unfractioned heparin in inflammatory bowel disease may result from its anticoagulant properties. However, beyond its well-known an ticoagulant activity, unfractioned heparin also exhibits a broad spectrum o f immunomodulating and anti-inflammatory properties, by inhibiting the recr uitment of neutrophils and reducing pro-inflammatory cytokines. Moreover, i t can restore the high-affinity receptor binding of basic fibroblast growth factor and this would aid healing of the ulcerated mucosa. In conclusion, unfractioned heparin may represent a safe therapeutic option for severe, steroid-resistant ulcerative colitis, although randomized, con trolled trials are needed to confirm these data.