Hepatitis B, Chronic ; immunology ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; immunology

Immune thrombocytopenia (ITP) is a common acquired autoimmune hematological disorders. Platelet autoantibodies lead to the decrease of platelet production and (or) increase of its destruction. The latest researches showed that the abnormal tryptophan metabolism mediated by indoleamine-2, 3-dioxygenase(IDO) is related with the pathogenesis of ITP. The patients with ITP show less expression of IDO, reduction of Treg cells and increase of autoreactive T cells and autoantibodies. CTLA-4-Ig can improve the expression of IDO in the patients with ITP, which also can inhibit the proliferation and activation of self-reactive T cells. Thus, clarifying the abnormal tryptophan metabolism mediated by IDO may provide a new idea for improving the understand of the pathogenesis and treatment of ITP. This review focuses on reasearch progress of the tryptophan metabolism mediated by IDO and ITP.
Autoantibodies ; Blood Platelets ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; Thrombocytopenia ; Thrombopoiesis ; Tryptophan

Cell Adhesion ; Cell Movement ; Cell Proliferation ; Hep G2 Cells ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; genetics ; Transfection

Munn et al. made a scientific observation of major biological importance. For the first time they showed that in the mammal the fetus does survive an immune attack mounted by the mother, and that the mechanism responsible for the survival depends on the fetus and placenta 'actively' defending itself from attack by maternal T cells by means of an enzyme indoleamine 2,3-dioxygenase (EC 1.13.11.42) dependent localised depletion of L-tryptophan. These findings raise critical questions for disease and its prevention during human pregnancy. Specifically, the role of this mechanism (discovered in mouse) in the human, and the extent to which defective activation of this process is responsible for major clinical diseases are unknown. Therefore some key facts about this enzyme expressed in the human placenta have been studied in order to test whether Munn et al.'s findings in mouse are met for human pregnancy. This short review attempts to describe our experimental work on human placental indoleamine 2,3-dioxygenase.
Animals ; Fetus ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; Mammals ; Mice ; Mothers ; Placenta ; Pre-Eclampsia ; Pregnancy ; T-Lymphocytes ; Tryptophan

PURPOSE: To identify the localization of indoleamine 2,3-dioxygenase (IDO) in human corneal cells and to evaluate its ability to act as a local immunosuppressive factor. METHODS: The expression profile of IDO was obtained with RT-PCR and Western blot of in a primary culture of human corneal cells (fibroblasts, epithelial cells and endothelial cells). In order to investigate the immunosuppressive function of IDO, immune cells were cultured in a human corneal cell-conditioned medium, and their prolifleration was identified by the MTT assay. Moreover, apoptotic effects of IDO in immune cells treated with IFN-gamma were also investigated with apoptosis ELISA. RESULTS: Among the three different types of human corneal cells analyzed, mRNA and protein expression of IDO was observed only in human corneal fibroblasts. Immune cells cultured in a human corneal fibroblast-conditioned medium showed inhibited proliferation. Moreover, IFN-gamma-induced expression of IDO significantly enhanced apoptotic ability in a dose-depandant manner. CONCLUSIONS: Our results suggest that human corneal fibroblasts are relatively immuno-resistant and that expression of IDO may be one of the factors involved in the immune tolerance observed in corneal grafts.
Apoptosis ; Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; Epithelial Cells ; Fibroblasts ; Humans* ; Immune Tolerance ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; RNA, Messenger ; Transplants

OBJECTIVETo review the recent studies about the role of indoleamine 2,3-dioxygenase (IDO) in tumor induced tolerance.

DATA SOURCESPublished articles (1978 - 2009) on IDO and tumor induced tolerance were selected from Medline.

STUDY SELECTIONArticles selected were relevant to development of IDO in tumor induced tolerance. Of all originally identified articles, 50 specially addressed the stated purpose.

RESULTSRecent work has revealed IDO at high levels in tumors and in tumor-draining lymph nodes and a close relationship between IDO activity and the regulatory T cells.

CONCLUSIONUp-regulation of IDO is proven to be a mechanism of acquired tolerance in tumors, in which the closely coupled positive feedback system between IDO and regulatory T cells may be considered to play an important role.

Animals ; Gene Expression Regulation, Neoplastic ; physiology ; Humans ; Immune Tolerance ; physiology ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; metabolism ; Neoplasms ; enzymology ; immunology

BACKGROUND: Immune regulatory dendritic cells (DCs) play an important role in maintaining self-tolerance. Recent evidences demonstrate that DCs expressing indoleamine 2,3-dioxygenase (IDO), which is involved in tryptophan catabolism, play an important role in immunoregulation and tolerance and induce T cell apoptosis. This study was devised to examine the role of IDO in the oral tolerance induction in collagen-induced arthritis (CIA) mouse model. METHODS: Beginning 2 weeks before immunization, CII was fed six times to DBA/1 mice and the effect on arthritis was assessed. In tolerized mice, CD11c+ DCs were isolated and stimulated with CII, IFN-gamma, and LPS with or without IDO inhibitor, 1-methyl-DL-tryptophan (1-MT) and IDO expression by CD11c+ DCs was analyzed using FACS and RT-PCR. The expression of IDO, MHC II, CD80, and CD86 by CD11c+ DCs were examined using confocal microscopy. Regulatory effect of CD11c+ DCs on Ag-specific T cell proliferative response to CII was examined by mixed lymphocyte reaction (MLR) with or without 1-MT. RESULTS: The proportion of IDO-expressing CD11c+ DCs was slightly higher in tolerized mice than in CIA mice and significantly increased after stimulation with CII, IFN-gamma, and LPS in an IDO- dependent manner. On confocal microscopic examination, the expression of IDO was higher and those of MHC II and CD86 were lower in CD11c+ DCs from tolerized mice compared to those from CIA mice. On MLR, CD11c+ DCs from tolerized mice inhibited T cell proliferative response to CII in an IDO-dependent manner. CONCLUSION: Enhanced IDO expression by CD11c+ DCs from tolerized mice may contribute to the regulation of proliferative response of CII-reactive T cells and could be involved in the induction of oral tolerance to CII.
Animals* ; Apoptosis ; Arthritis ; Arthritis, Experimental ; Dendritic Cells* ; Immunization ; Indoleamine-Pyrrole 2,3,-Dioxygenase* ; Lymphocyte Culture Test, Mixed ; Metabolism ; Mice ; Microscopy, Confocal ; Models, Animal* ; T-Lymphocytes ; Tryptophan

The decrease in maternal plasma total (free + albumin-bound) tryptophan (Trp) during the third pregnancy trimester is attributed to induction of indoleamine 2,3-dioxygenase (IDO). When measured, free [Trp] is increased because of albumin depletion and non-esterified fatty acid elevation. The Trp depletion concept in pregnancy is therefore not supported because of incorrect interpretation of changes in Trp disposition and also for not addressing mouse strain differences in Trp-related responses and potential inhibition of Trp transport by the IDO inhibitor 1-methyl tryptophan. Application of the Trp utilization concept in pregnancy offers several physiological advantages favoring fetal development and successful outcome, namely provision of Trp for fetal protein synthesis and growth, serotonin for signaling pathways, kynurenic acid for neuroprotection, quinolinic acid for NAD+ synthesis, and other kynurenines for suppression of T cell responses. An excessive increase in Trp availability could compromise pregnancy by undermining T cell suppression, e.g., in pre-eclampsia.
Animals ; Female ; Fetal Development ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; Kynurenic Acid ; Mice ; Plasma ; Pre-Eclampsia ; Pregnancy Trimester, Third ; Pregnancy* ; Quinolinic Acid ; Serotonin ; Tryptophan*

In order to confirm the existence of indoleamine 2, 3-dioxygenase (IDO) gene in swine, and to clone the novel gene followed by the molecule structure properties and expression pattern analysis, the porcine mRNA sequences homologous to human IDO were obtained from GenBank database by bioinformatics method. By using RT-PCR, the IDO gene was cloned from porcine endothelial cell line and the accuracy of the nucleic acid sequence was confirmed, and the expression pattern of the gene was detected. The three-dimensional structure model of porcine IDO was built referring to the tertiary structure of human IDO using biological sequence analysis software and database. The results showed that the porcine IDO was identified by sequencing. The nucleotide sequences were confirmed as a novel gene after submitted to Genbank. Porcine IDO was expressed in the lung, thymus, epididymis and anterior chamber with a basic level, however in peripheral blood mononuclear cells (PBMCs) the IDO gene was highly expressed. The three-dimensional structure model of porcine IDO was similar to that of human IDO. It was suggested that identification of the structure information of porcine IDO is essential to further investigate the immunologic function of the gene. Study of IDO on NK cells-mediated xenograft rejection will be a novel therapeutic target for the development of xenotransplantation.
Amino Acid Sequence ; Animals ; Base Sequence ; Cell Line ; Cloning, Molecular ; methods ; Endothelial Cells ; metabolism ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; genetics ; metabolism ; Molecular Sequence Data ; Sequence Alignment ; Swine

This study was aimed to investigate the mechanism of indoleamine 2, 3-dioxygenase (IDO) activity in acute myeloid leukemia cells contributing to tumor immune escape. Myeloid leukemia cells were isolated from bone marrow of 23 patients with acute myeloid leukemia (AML) and IDO expression was detected by immunochemistry and RT-PCR methods. Then mixed lymphocyte reaction (MLR) of one way was carried out, leukemia cells were used as stimulating cells and T-lymphocytes were used as reactive cells in culture with or without 1-MT. T-lymphocyte proliferation rate was determined by MTT assay and IDO activity in supernatant of MLR was detected by high-performance liquid chromatography (HPLC). The results showed that IDO expression was found in 17 out of 23 cases of acute myeloid leukemia cells; IDO enzyme activity in leukemia cells inhibited T-lymphocyte proliferation in MLR cultures. It is concluded that IDO activity expressing in leukemia cells can suppress T-lymphocyte proliferation responses, which may be contributing to tumor immune escape.
Cell Proliferation ; Humans ; Immune Tolerance ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; metabolism ; Leukemia, Myeloid, Acute ; enzymology ; immunology ; pathology ; T-Lymphocytes ; cytology ; immunology ; Tumor Cells, Cultured ; Tumor Escape ; immunology