Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, is expressed by a variety of cells and tissues such as macrophages, dendritic cells, cells of the endocrine system and by the placenta. IFN-γ is the main inducer of this enzyme. IDO acts as an important defense mechanism of innate immunity against pathogens. It also has tumor suppressive activity and prolongs...

Suppression of an excessive systemic inflammatory response is a promising and potent strategy for treating endotoxic sepsis. Indoleamine 2,3-dioxygenase (IDO), which is the rate-limiting enzyme for tryptophan catabolism, may play a critical role in various inflammatory disorders. In this study, we report a critical role for IDO in the dysregulated immune response associated with endotoxin shock...

Although dendritic cells (DCs) strongly stimulate the immune response, they can also induce unresponsiveness. Recently, a human monocyte-derived DC subpopulation was described that constitutively expresses indoleamine 2,3-dioxygenase (IDO). These DCs were defined as nonadherent CD123+/CC chemokine receptor 6+ (CCR6+) cells that suppress the allogeneic T-cell response. In the present study, we g...

UNLABELLED  Background and rationale for the study. Previous studies showed that CTLA4Ig and indoleamine 2,3-dioxygenase (IDO) genes played regulatory role in organ transplantation but failed to reach satisfactory effects. In this study, we constructed an adenovirus- mediated gene expressing CTLA4Ig-IDO and established rat liver transplantation models. Recipients were randomly divided into four...

Rheumatoid arthritis (RA) is a chronic and debilitating inflammatory autoimmune disease of unknown etiology. As with a variety of autoimmune disorders, evidence of elevated tryptophan catabolism has been detected in RA patients indicative of activation of the immunomodulatory enzyme IDO. However, the role that IDO plays in the disease process is not well understood. The conceptualization that I...

Successful long-term treatment of type-1 diabetes mainly relies on replacement of β-cells via islet transplantation. Donor shortage is one of the main obstacles preventing transplantation from becoming the treatment of choice. Although animal organs could be an alternative source for transplantation, common immunosuppressive treatments demonstrate low efficacy in preventing xenorejection. Immun...

PURPOSE The pathologic interactions between tumor and host immune cells within the tumor microenvironment create an immunosuppressive network that promotes tumor growth and protects the tumor from immune attack. In this study, we examined the contribution of the immunomodulatory enzyme indoleamine 2,3-dioxygenase (IDO) on this phenomenon. EXPERIMENTAL DESIGN Expression of IDO was analyzed in ...

Indoleamine 2, 3-dioxygenase (IDO) is a rate-limiting enzyme for tryptophan metabolism inducing immune tolerance of tumors. The purpose of this study is to investigate IDO expression and its prognostic significance in bladder urothelial carcinoma (BUC). In this study, immunohistochemical staining for IDO expression in BUC tissues (n = 84) and normal bladder tissues (n = 22) was performed. The m...

Indoleamine 2,3-dioxygenase (IDO) is the rate-limiting enzyme in the tryptophan-catabolizing pathway and a key regulator of peripheral immune tolerance. As the suppressive effects of IDO are predominantly mediated by dendritic cells (DCs) and IDO-competent DCs promote long-term immunologic tolerance, a detailed understanding of how IDO expression and activity is regulated in these cells is cent...

Heme oxygenase-1 (HO-1) is the rate limiting enzyme of heme catabolism whereas indoleamine 2,3 dioxygenase (IDO) catabolizes tryptophan through the kynurenine pathway. We analyzed the expression and biological effects of these enzymes in rat and human breast cancer cell lines. We show that rat (NMU and 13762) but not human cells (MCF-7 and T47D) express HO-1. When overexpressed, we found this e...