Recent advances in biological therapy for inflammatory bowel disease.

Immune system is a major determinant of pathophysiology of inflammatory bowel disease (IBD), and cytokines are well known mediators of immune system. Recently, informations on pro-inflammatory cytokines and their role in IBD have led to development of potential therapeutic approach to manipulate these cytokines and there by inhibiting inflammation in IBD. These therapeutic approaches include inhibitors of the tumour necrosis factor (TNF)-alpha lymphocyte trafficking, type 1 T helper (Th1) cell polarization and nuclear factor type beta; immunoregulatory cytokines and various growth factors. Studies on these therapies have documented variable results and the outcomes of many clinical trials are awaited. However, these potential therapies, if become real may revolutionise approach in patients with IBD. Analysis of the inflammed mucosa from patients with Crohn disease (CD) and ulcerative colitis (UC) have shown increased expression of certain proinflammatory cytokines such as interleukin-1 (IL-1), interleukin 6 (IL-6) and TNF-alpha. The latter is important in the recruitment of neutrophils into inflammed tissue, a process which results from three physiological steps: (i) rolling, (ii) adhesion, and (iii) transendothelial migration. Understanding of the biology of chronic inflammation has expanded the therapies available for IBD and particularly CD. At present, the biological therapies that are being used in clinical practice or investigated for the treatment of IBD are predominantly proteins, usually delivered intravenously or subcutaneously. The therapies used include: 1. TNF-alpha inhibitors: infliximab, CDP 571, etanercept, onercept, CNI- 1493 and thalidomide. 2. Inhibitors of lymphocyte trafficking: natalizumab, LPD-02 and ICAM-1. 3. Inhibitors of Th1 polarization: monoclonal antibodies for IL-12, interferon (IFN)-gamma and anti IFN-gamma. 4. Immunoregulatory cytokines: IL-10 and IL-11. 5. Inhibitors of nuclear factor kappa (beta NF-kbeta.) 6. Growth factors: epidermal growth factor (EGF) and Keratinocyte growth factor (KGF).