The potential role of indoleamine 2,3 dioxygenase (IDO) as a predictive and therapeutic target for diabetes treatment: a mythical truth

Type 1 diabetes (T1D) is an autoimmune disease in which a T-cell-mediated reaction demolishes insulinproducing cells of pancreatic islets. Inadequacy of insulin therapy has motivated research focused on mechanisms by which autoimmune reactions can be suppressed. In recent years, the role of indoleamine 2,3 dioxygenase (IDO) in regulation of immune system has been extensively investigated. Initially, IDOwas recognized as a host defensemechanism. However, recent studies have suggested an immunomodulatory role for IDO which may contribute to the induction of immune tolerance. In this review, we concentrate on the role of IDO in several pathologic conditions with a focus on T1D to rationalize our hypothesis regarding the potential for inclusion of IDO in certain therapeutic strategies aimed at early detection, treatment or ideally cure of chronic and autoimmune diseases such as T1D.