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

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

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

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

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

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

BACKGROUNDIndoleamine-2,3-dioxygenase (IDO) is proven to suppress hepatitis B virus (HBV) specific immune response and depletion of IDO may be a useful approach for HBV therapy. To test this concept, we constructed recombinant adenovirus with human IDO and HBV preS, which would form the basis for future in vivo experiments.

METHODSThe fragment of human IDO and HBV preS cDNA were subcloned into multiple cloning sites in an adenoviral vector system containing two cytomegalovirus (CMV) promoters. Recombination was conducted in the Escherichia coli BJ5183. The recombinant adenovirus containing hIDO gene and HBVpreS gene was packaged and amplified in 293 cells. Integration was confirmed by polymerase chain reaction as well as the quantification of viral titers. HepG2 cells were infected with the recombinant adenovirus and mRNA and protein specific for hIDO and HBVpreS was detected by RT-PCR and Western blotting respectively.

RESULTSThe recombinant adenovirus was produced successfully. Its titer was 2.5 × 10(9) efu/ml. IDO and HBVpreS mRNA as well as the encoded proteins could be found in transfected HepG2 cells, but not in control HepG2 cells.

CONCLUSIONThe transfer of hIDO-HBVpreS with double-promoter adenoviral vector was efficient. The recombinant adenovirus with hIDO and HBV preS would provide the experimental basis for future studies.

Adenoviridae ; genetics ; Cloning, Organism ; Genetic Vectors ; Hep G2 Cells ; Hepatitis B virus ; genetics ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; genetics ; Recombination, Genetic

BACKGROUNDIncreasing evidence suggests that, by the production of indoleamine 2,3-dioxygenase (IDO), dendritic cells (DC) may reduce the activity of T lymphocytes and inhibit T lymphocyte proliferation-induced immune tolerance. One promising way is inspired by increasing IDO expression in DC cells for immune tolerance after transplantation. The aim of this work was to examine the effect of interferon-γ (IFN-γ) on the expression of IDO by DC.

METHODSSpleen-derived rat DCs were cultured and induced by cytokines, and the expression of OX62 and surface molecules CD80 and CD86 were measured with flow cytometry. After the DCs were induced by IFN-γ at different concentrations (0, 100, 300, 500 U/ml), the expression levels of IDO mRNA were measured with real-time PCR, and the expression levels of IDO protein in DCs were measured with Western blotting. The allogeneic mixed lymphocyte reaction (MLR) was used to test the effects of DCs incubated with different concentrations of IFN-γ on allogeneic T lymphocyte proliferation.

RESULTSUnder the microscope, the DCs induced by IFN-γ showed a typical dendritic morphology. The expression rate of OX62 was above 80% and the positive expression rates of CD80 and CD86 were both about 80%. The expressions of IDO mRNA and IDO protein increased gradually with the increase of IFN-γ concentration, showing statistical significance in the differences between the groups (P < 0.05). Compared with the control DC, the DC incubated with IFN-γ had a notable decrease in allostimulatory activity (P < 0.05). With the increasing IFN-γ concentration, the T lymphocyte proliferation decreased, and the difference between the groups was also statistically significant (P < 0.05).

CONCLUSIONSThe highly purified spleen derived rat DCs can be successfully acquired through the improved adhesion in-vitro method. IFN-γ can induce increased expression of IDO in spleen-derived rat DCs and reduce the spleen DCs' capacity to stimulate the proliferation of allogeneic T cells.

Animals ; Cell Proliferation ; Cells, Cultured ; Dendritic Cells ; cytology ; Enzyme Induction ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; biosynthesis ; Male ; Rats ; Rats, Wistar ; Spleen ; cytology ; T-Lymphocytes ; cytology

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