Dataset Information

Tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase 1 make separate, tissue-specific contributions to basal and inflammation-induced kynurenine pathway metabolism in mice.

ABSTRACT: BACKGROUND:In mammals, the majority of the essential amino acid tryptophan is degraded via the kynurenine pathway (KP). Several KP metabolites play distinct physiological roles, often linked to immune system functions, and may also be causally involved in human diseases including neurodegenerative disorders, schizophrenia and cancer. Pharmacological manipulation of the KP has therefore become an active area of drug development. To target the pathway effectively, it is important to understand how specific KP enzymes control levels of the bioactive metabolites in vivo. METHODS:Here, we conducted a comprehensive biochemical characterization of mice with a targeted deletion of either tryptophan 2,3-dioxygenase (TDO) or indoleamine 2,3-dioxygenase (IDO), the two initial rate-limiting enzymes of the KP. These enzymes catalyze the same reaction, but differ in biochemical characteristics and expression patterns. We measured KP metabolite levels and enzyme activities and expression in several tissues in basal and immune-stimulated conditions. RESULTS AND CONCLUSIONS:Although our study revealed several unexpected downstream effects on KP metabolism in both knockout mice, the results were essentially consistent with TDO-mediated control of basal KP metabolism and a role of IDO in phenomena involving stimulation of the immune system.

SUBMITTER: Larkin PB

PROVIDER: S-EPMC5808460 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase 1 make separate, tissue-specific contributions to basal and inflammation-induced kynurenine pathway metabolism in mice.

Larkin Paul B PB Sathyasaikumar Korrapati V KV Notarangelo Francesca M FM Funakoshi Hiroshi H Nakamura Toshikazu T Schwarcz Robert R Muchowski Paul J PJ

Biochimica et biophysica acta 20160705 11 Pt A

<h4>Background</h4>In mammals, the majority of the essential amino acid tryptophan is degraded via the kynurenine pathway (KP). Several KP metabolites play distinct physiological roles, often linked to immune system functions, and may also be causally involved in human diseases including neurodegenerative disorders, schizophrenia and cancer. Pharmacological manipulation of the KP has therefore become an active area of drug development. To target the pathway effectively, it is important to unders ...[more]

PMID: 27392942

Similar Datasets

Project description:ObjectivesExtrahepatic tryptophan (Trp)-kynurenine (Kyn) metabolism via indoleamine 2,3-dioxygenase 1 (IDO1) induction was found to be associated with intrinsic immune regulation. However, the Trp-Kyn metabolism-associated immune regulation in dermatomyositis (DM) remains unknown. Therefore, we aimed to investigate the clinical relevance of the Trp-Kyn metabolism via IDO1 induction in DM.MethodsLiquid chromatography-mass spectrometry (HPLC-MS) was used to examine the serum Kyn and Trp concentrations in DM. In addition, we used X-tile software to determine the optimal cutoff value of the Kyn/Trp ratio, a surrogate marker for Trp-Kyn metabolism. Spearman analysis was performed to evaluate the association of Trp-Kyn metabolism with muscle enzymes and inflammatory markers.ResultsDM patients had significantly higher serum Kyn/Trp ratio (× 10-3) when compared with the healthy controls. The serum Kyn/Trp ratio was positively correlated with the levels of muscle enzymes and inflammatory markers. In addition, the serum Kyn/Trp ratio significantly decreased (36.89 (26.00-54.00) vs. 25.00 (18.00-37.00), P = 0.0006) after treatment. DM patients with high serum Kyn/Trp ratio had a significantly higher percentage of muscle weakness symptoms (62.5% vs. 20.0%, P = 0.019) and higher levels of LDH (316.0 (236.0-467.0) vs. 198.0 (144.0-256.0), P = 0.004) and AST (56.5 (35.0-92.2) vs. 23.0 (20.0-36.0), P = 0.002)) than those with low serum Kyn/Trp ratio. Multiple Cox regression analyses identified ln(Kyn/Trp) (HR 4.874, 95% CI 1.105-21.499, P = 0.036) as an independent prognostic predictor of mortality in DM.ConclusionsDM patients with enhanced Trp-Kyn metabolism at disease onset are characterized by more severe disease status and poor prognosis. Intrinsic immune regulation function via enhanced Trp-Kyn metabolism by IDO1 induction may be a potential therapeutic target in DM. Key Points • HPLC-MS identified increased serum Kyn/Trp ratio in DM patients, which positively correlated with levels of muscle enzymes and inflammatory markers and was downregulated upon treatment. • Cox regression analyses identified ln(Kyn/Trp) as an independent prognostic predictor of mortality in DM. • Monitoring intrinsic immune regulation function should be considered a potential therapeutic target in DM patients.

Project description:BackgroundInflammatory cytokine interleukin-6 (IL-6) plays a pivotal role in skeletal muscle degradation after intra-abdominal sepsis (IAS), with mechanism remained to be elucidated. Indoleamine 2,3-dioxygenase 1 (IDO-1), a key enzyme in converting tryptophan into kynurenine, could be activated by IL-6, and kynurenine has been shown to be involved in muscle degradation. We hypothesized that IL-6 could promote muscle degradation via tryptophan-IDO-1-kynurenine pathway in IAS patients.MethodsSerum and rectus abdominis (RA) were obtained from IAS or non-IAS patients. Mouse model of IAS-induced muscle wasting was generated by caecal ligation and puncture (CLP) and lipopolysaccharide (LPS) injection. IL-6 signalling was blocked by anti-mouse IL-6 antibody (IL-6-AB), and the IDO-1 pathway was blocked by navoximod. To elucidate the role of kynurenine in muscle mass and physiology, kynurenine was administered to IAS mice treated with IL-6-AB.ResultsCompared to non-IAS patients, kynurenine levels in serum (+2.30-fold vs. non-IAS, P < 0.001) and RA (+3.11-fold vs. non-IAS, P < 0.001) were elevated, whereas tryptophan levels in serum (-53.65% vs. non-IAS, P < 0.01) and RA (-61.39% vs. non-IAS, P < 0.01) were decreased. Serum IL-6 level of the IAS group was significantly higher compared to non-IAS patients (+5.82-fold vs. non-IAS, P = 0.01), and muscle cross-sectional area (MCSA) was markedly reduced compared to non-IAS patients (-27.73% vs. non-IAS, P < 0.01). In animal experiments, IDO-1 expression was up-regulated in the small intestine, colon and blood for CLP or LPS-treated mice, and there was correlation (R2 = 0.66, P < 0.01) between serum and muscle kynurenine concentrations. Navoximod significantly mitigated IAS-induced skeletal muscle loss according to MCSA analysis (+22.94% vs. CLP, P < 0.05; +23.71% vs. LPS, P < 0.01) and increased the phosphorylated AKT (+2.15-fold vs. CLP, P < 0.01; +3.44-fold vs. LPS, P < 0.01) and myosin heavy chain (+3.64-fold vs. CLP, P < 0.01; +2.13-fold vs. LPS, P < 0.01) protein expression in myocytes. In the presence of anti-IL-6 antibody, a significantly decreased IDO-1 expression was observed in the small intestine, colon and blood in CLP or LPS mice (all P < 0.01), whereas the decrease of MCSA was alleviated (+37.43% vs. CLP + IgG, P < 0.001; +30.72% vs. LPS + IgG, P < 0.001). In contrast, additional supplementation of kynurenine decreased the MCSA in septic mice treated with IL-6-AB (both P < 0.01).ConclusionsThis study provided novel insights into the tryptophan-IDO-1-kynurenine-dependent mechanisms that underlie inflammatory cytokine-induced skeletal muscle catabolism during intra-abdominal sepsis.

Project description:Kynurenine (Kyn), a metabolite of tryptophan (Trp), is a key regulator of mammal immune responses such as cancer immune tolerance. Indoleamine-2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO) are main enzymes regulating the first and rate-limiting step of the Kyn pathway. To identify new small molecule inhibitors of TDO, we selected A172 glioblastoma cell line constitutively expressed TDO. Characterization of this cell line using kinase inhibitor library resulted in identification of MEK/ERK pathway-dependent TDO expression. After knowing the properties for TDO expression, we further proceeded to screen chemical library for TDO inhibitors. We previously determined that S-benzylisothiourea derivatives are enzymatic inhibitors of indoleamine 2,3-dioxygenase 1 (IDO1) and suggested that the isothiourea moiety could be an important pharmacophore for binding to heme. Based on this premise, we screened an in-house library composed of various isothiourea derivatives and identified a bisisothiourea derivative, PVZB3001, as an inhibitor of TDO. Interestingly, PVZB3001 also inhibited the enzymatic activity of IDO1 in both cell-based and cell-free assays but did not inhibit other heme enzymes. Molecular docking studies suggested the importance of isothiourea moieties at the ortho position of the phenyl ring for the inhibition of catalytic activity. PVZB3001 showed competitive inhibition against TDO, and this was supported by the docking simulation. PVZB3001 recovered natural killer (NK) cell viability and functions by inhibiting Kyn accumulation in conditioned medium of both IDO1- and TDO-expressing cells. Furthermore, oral administration of IDO1-overexpressing tumor-bearing mice with PVZB3001 significantly inhibited tumor growth. Thus, we identified a novel selective dual inhibitor of IDO1 and TDO using the Kyn production assay with a glioblastoma cell line. This inhibitor could be a useful pharmacological tool for modulating the Kyn pathway in a variety of experimental systems.

Dataset Information

Tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase 1 make separate, tissue-specific contributions to basal and inflammation-induced kynurenine pathway metabolism in mice.

Publications

Tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase 1 make separate, tissue-specific contributions to basal and inflammation-induced kynurenine pathway metabolism in mice.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets