Browse
Submit Data
Databases
API
Help

Dataset Information

13 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Plasmacytoid dendritic cells from mouse tumor-draining lymph nodes directly activate mature Tregs via indoleamine 2,3-dioxygenase.

ABSTRACT: A small population of plasmacytoid DCs (pDCs) in mouse tumor-draining LNs can express the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO). We show that these IDO+ pDCs directly activate resting CD4+CD25+Foxp3+ Tregs for potent suppressor activity. In vivo, Tregs isolated from tumor-draining LNs were constitutively activated and suppressed antigen-specific T cells immediately ex vivo. In vitro, IDO+ pDCs from tumor-draining LNs rapidly activated resting Tregs from non-tumor-bearing hosts without the need for mitogen or exogenous anti-CD3 crosslinking. Treg activation by IDO+ pDCs was MHC restricted, required an intact amino acid-responsive GCN2 pathway in the Tregs, and was prevented by CTLA4 blockade. Tregs activated by IDO markedly upregulated programmed cell death 1 ligand 1 (PD-L1) and PD-L2 expression on target DCs, and the ability of Tregs to suppress target T cell proliferation was abrogated by antibodies against the programmed cell death 1/PD-L (PD-1/PD-L) pathway. In contrast, Tregs activated by anti-CD3 crosslinking did not cause upregulation of PD-Ls, and suppression by these cells was unaffected by blocking the PD-1/PD-L pathway. Tregs isolated from tumor-draining LNs in vivo showed potent PD-1/PD-L-mediated suppression, which was selectively lost when tumors were grown in IDO-deficient hosts. We hypothesize that IDO+ pDCs create a profoundly suppressive microenvironment within tumor-draining LNs via constitutive activation of Tregs.

SUBMITTER: Sharma MD

PROVIDER: S-EPMC1940240 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Expression of indoleamine 2,3-dioxygenase by plasmacytoid dendritic cells in tumor-draining lymph nodes.

Project description:One mechanism contributing to immunologic unresponsiveness toward tumors may be presentation of tumor antigens by tolerogenic host APCs. We show that mouse tumor-draining LNs (TDLNs) contained a subset of plasmacytoid DCs (pDCs) that constitutively expressed immunosuppressive levels of the enzyme indoleamine 2,3-dioxygenase (IDO). Despite comprising only 0.5% of LN cells, these pDCs in vitro potently suppressed T cell responses to antigens presented by the pDCs themselves and also, in a dominant fashion, suppressed T cell responses to third-party antigens presented by nonsuppressive APCs. Adoptive transfer of DCs from TDLNs into naive hosts created profound local T cell anergy, specifically toward antigens expressed by the transferred DCs. Anergy was prevented by targeted disruption of the IDO gene in the DCs or by administration of the IDO inhibitor drug 1-methyl-D-tryptophan to recipient mice. Within the population of pDCs, the majority of the functional IDO-mediated suppressor activity segregated with a novel subset of pDCs coexpressing the B-lineage marker CD19. We hypothesize that IDO-mediated suppression by pDCs in TDLNs creates a local microenvironment that is potently suppressive of host antitumor T cell responses.

| S-EPMC449750 | biostudies-literature

Indoleamine 2,3-dioxygenase controls conversion of Foxp3+ Tregs to TH17-like cells in tumor-draining lymph nodes.

Project description:The immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) is expressed by a subset of murine plasmacytoid DCs (pDCs) in tumor-draining lymph nodes (TDLNs), where it can potently activate Foxp3+ regulatory T cells (Tregs). We now show that IDO functions as a molecular switch in TDLNs, maintaining Tregs in their normal suppressive phenotype when IDO was active, but allowing inflammation-induced conversion of Tregs to a polyfunctional T-helper phenotype similar to proinflammatory T-helper-17 (TH17) cells when IDO was blocked. In vitro, conversion of Tregs to the TH17-like phenotype was driven by antigen-activated effector T cells and required interleukin-6 (IL-6) produced by activated pDCs. IDO regulated this conversion by dominantly suppressing production of IL-6 in pDCs, in a GCN2-kinase dependent fashion. In vivo, using a model of established B16 melanoma, the combination of an IDO-inhibitor drug plus antitumor vaccine caused up-regulation of IL-6 in pDCs and in situ conversion of a majority of Tregs to the TH17 phenotype, with marked enhancement of CD8+ T-cell activation and antitumor efficacy. Thus, Tregs in TDLNs can be actively reprogrammed in situ into T-helper cells, without the need for physical depletion, and IDO serves as a key regulator of this critical conversion.

| S-EPMC2699232 | biostudies-literature

HIV-activated human plasmacytoid DCs induce Tregs through an indoleamine 2,3-dioxygenase-dependent mechanism.

Project description:Plasmacytoid DCs (pDCs) have been implicated as crucial cells in antiviral immune responses. On recognizing HIV, they become activated, secreting large amounts of IFN-alpha and inflammatory cytokines, thereby potentiating innate and adaptive antiviral immune responses. Here, we have shown that HIV-stimulated human pDCs can also induce the differentiation of naive CD4+ T cells into Tregs with suppressive function. This differentiation was independent of pDC production of IFN-alpha and primarily dependent on pDC expression of indoleamine 2,3-dioxygenase, which was induced through the TLR/MyD88 pathway, following binding of HIV to CD4 and triggering of TLR7 by HIV genomic RNA. Functionally, the Tregs induced by pDCs were shown to inhibit the maturation of bystander conventional DCs. This study therefore reveals what we believe to be a novel mechanism by which pDC may regulate and potentially limit anti-HIV immune responses.

| S-EPMC2528911 | biostudies-literature

Indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors activate the aryl hydrocarbon receptor.

Project description:Indoleamine 2,3-dioxygenase 1 (IDO1) plays a key role in the immune system by regulating tryptophan levels and T cell differentiation. Several tumor types overexpress IDO1 to avoid immune surveillance making IDO1 of interest as a target for therapeutic intervention. As a result, several IDO1 inhibitors are currently being tested in clinical trials for cancer treatment as well as several other diseases. Many of the IDO1 inhibitors in clinical trials naturally bear structural similarities to the IDO1 substrate tryptophan, as such, they fulfill many of the structural and functional criteria as potential AHR ligands. Using mouse and human cell-based luciferase gene reporter assays, qPCR confirmation experiments, and CYP1A1 enzyme activity assays, we report that some of the promising clinical IDO1 inhibitors also act as agonists for the aryl hydrocarbon receptor (AHR), best known for its roles in xenobiotic metabolism and as another key regulator of the immune response. The dual role as IDO antagonist and AHR agonist for many of these IDO target drugs should be considered for full interrogation of their biological mechanisms and clinical outcomes.

| S-EPMC5495139 | biostudies-literature

Indoleamine 2,3-dioxygenase vaccination.

Project description:Indoleamine 2,3-dioxygenase (IDO) is an immunoregulatory enzyme. Remarkably, we discovered IDO-specific T cells that can influence adaptive immune reactions in patients with cancer. Further, a recent phase I clinical trial demonstrated long-lasting disease stabilization without toxicity in patients with non-small-cell lung cancer (NSCLC) who were vaccinated with an IDO-derived HLA-A2-restricted epitope.

| S-EPMC4368142 | biostudies-literature

Diaryl hydroxylamines as pan or dual inhibitors of indoleamine 2,3-dioxygenase-1, indoleamine 2,3-dioxygenase-2 and tryptophan dioxygenase.

Project description:Tryptophan (Trp) catabolizing enzymes play an important and complex role in the development of cancer. Significant evidence implicates them in a range of inflammatory and immunosuppressive activities. Whereas inhibitors of indoleamine 2,3-dioxygenase-1 (IDO1) have been reported and analyzed in the clinic, fewer inhibitors have been described for tryptophan dioxygenase (TDO) and indoleamine 2,3-dioxygenase-2 (IDO2) which also have been implicated more recently in cancer, inflammation and immune control. Consequently the development of dual or pan inhibitors of these Trp catabolizing enzymes may represent a therapeutically important area of research. This is the first report to describe the development of dual and pan inhibitors of IDO1, TDO and IDO2.

| S-EPMC6318801 | biostudies-literature

Expression of indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase in early concepti.

Project description:Indoleamine 2,3-dioxygenase (IDO)-initiated tryptophan degradation in the placenta has been implicated in the prevention of the allogeneic fetus rejection [Munn, Zhou, Attwood, Bondarev, Conway, Marshall, Brown, and Mellor (1998) Science 281, 1191-1193]. To determine how IDO is associated with the development of the fetus and placenta, the time course of IDO expression (tryptophan-degrading activity, IDO protein and IDO mRNA) in the embryonic and extra-embryonic tissues as well as maternal tissues of mice was examined. A high tryptophan-degrading activity was detected in early concepti on days 6.5 and 7.5, whereas IDO protein and its mRNA were not expressed during early gestation, but appeared 2-3 days later, lasted for about 3 days and declined rapidly thereafter. The expression of IDO basically coincided with the formation of the placenta. On the contrary, the early tryptophan-degrading activity was due to gene expression of tryptophan 2,3-dioxygenase (TDO), as shown by Northern and Western analysis. These findings indicate that IDO is transiently expressed in the placenta but that the expression does not last until birth, and that the IDO expression is preceded by expression of another tryptophan-degrading enzyme, TDO, in the maternal and/or embryonic tissues in early concepti.

| S-EPMC1221754 | biostudies-other

Indoleamine 2,3-dioxygenase and dendritic cell tolerogenicity.

Project description:This article summarizes the molecular and cellular mechanisms that regulate the activity of indoleamine 2,3-dioxygenase (IDO), a potent immune-suppressive enzyme, in dendritic cells (DCs). Specific attention is given to differential up-regulation of IDO in distinct DC subsets, its function in immune homeostasis/autoimmunity, infection and cancer; and the associated immunological outcomes. The review will conclude with a discussion of the poorly defined mechanisms that mediate the long-term maintenance of IDO-expression in response to inflammatory stimuli and how selective modulation of IDO activity may be used in the treatment of disease.

| S-EPMC3645912 | biostudies-literature

NADH oxidase activity of indoleamine 2,3-dioxygenase.

Project description:The heme enzyme indoleamine 2,3-dioxygenase (IDO) was found to oxidize NADH under aerobic conditions in the absence of other enzymes or reactants. This reaction led to the formation of the dioxygen adduct of IDO and supported the oxidation of Trp to N-formylkynurenine. Formation of the dioxygen adduct and oxidation of Trp were accelerated by the addition of small amounts of hydrogen peroxide, and both processes were inhibited in the presence of either superoxide dismutase or catalase. Anaerobic reaction of IDO with NADH proceeded only in the presence of a mediator (e.g. methylene blue) and resulted in formation of the ferrous form of the enzyme. We propose that trace amounts of peroxide previously proposed to occur in NADH solutions as well as solid NADH activate IDO and lead to aerobic formation of superoxide and the reactive dioxygen adduct of the enzyme.

| S-EPMC3190733 | biostudies-literature

Indole peroxygenase activity of indoleamine 2,3-dioxygenase.

Project description:The heme enzyme indoleamine 2,3-dioxygenase (IDO) was found to catalyze the oxidation of indole by H(2)O(2), with generation of 2- and 3-oxoindole as the major products. This reaction occurred in the absence of O(2) and reducing agents and was not inhibited by superoxide dismutase or hydroxyl radical scavengers, although it was strongly inhibited by L-Trp. The stoichiometry of the reaction indicated a one-to-one correspondence for the consumption of indole and H(2)O(2). The (18)O-labeling experiments indicated that the oxygen incorporated into the monooxygenated products was derived almost exclusively from H(2)(18)O(2), suggesting that electron transfer was coupled to the transfer of oxygen from a ferryl intermediate of IDO. These results demonstrate that IDO oxidizes indole by means of a previously unrecognized peroxygenase activity. We conclude that IDO inserts oxygen into indole in a reaction that is mechanistically analogous to the "peroxide shunt" pathway of cytochrome P450.

| S-EPMC3435167 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data