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Intestinal toxicity induced by chemotherapeutics has become an important reason for the interruption of therapy and withdrawal of approved agents. In this study, we demonstrated that chemotherapeutics-induced intestinal damage were commonly characterized by the sharp upregulation of tryptophan (Trp)-kynurenine (KYN)-kynurenic acid (KA) axis metabolism. Mechanistically, chemotherapy-induced intestinal damage triggered the formation of an interleukin-6 (IL-6)-indoleamine 2,3-dioxygenase 1 (IDO1)-aryl hydrocarbon receptor (AHR) positive feedback loop, which accelerated kynurenine pathway metabolism in gut. Besides, AHR and G protein-coupled receptor 35 (GPR35) negative feedback regulates intestinal damage and inflammation to maintain intestinal integrity and homeostasis through gradually sensing kynurenic acid level in gut and macrophage, respectively. Moreover, based on virtual screening and biological verification, vardenafil and linagliptin as GPR35 and AHR agonists respectively were discovered from 2388 approved drugs. Importantly, the results that vardenafil and linagliptin significantly alleviated chemotherapy-induced intestinal toxicity
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Objective To establish double-transfected Madin-Darby canine kidney (MDCK) [Ⅱ cells expressing human organic anion transporting polypeptide 1B1 (hOATP1B1) and multidrug resistanceassociated protein 2 (hMRP2)and to testify their functions,moreover,to study the transcellur transport of indoleamine 2,3-dioxygenase (IDO) inhibitor 1-methyltryptophan (1-MT) in the transfectants.Methods hOATP1B1/hMRP2 eukaryotic vectors pVITRO2-SLCO1B1-ABCC2 was obtained by genetic engineering method and then transfected into MDCK cells.Stably expressed MDCK cells were screened by using the geneticin G418.Real-time PCR,Western blot analysis and immuno fluorescent confocal microscopy were used to verify the proteins expression.Transport of the representative substrate pravastatin in different pH values and substrate concentrations and 1-MT were evaluated using the double transfectants.Results MDCK-OATP1B1/MRP2 was successfully established.Pravastatin displayed the optimal transcellular transport when pH value was 6.5.Transport of pravastatin demonstrated the concentration-dependent in the concertation range of 0) to 500 μmol/L.Transport of 1-MT showed no significant difference in MDCK cells and transfectants.Conclusions MDCK-OATP1B1/MRP2 was successful established;1-MT was not the substrate of OATP1B1 or MRP2 protein;and the eatablished double transfectant cell lines can be used to evaluate OATP1B1/MRP2-medicated transport of xenobiotics (e.g.new drug candidates) and endogenous compounds (e.g.bilirubin).
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This study examined whether 1-methyl-tryptophan[1-MT,an indoleamine 2,3-dioxygenase(IDO)inhibitor]could reduce CD4+CD25+regulatory T cells(Tregs)proliferation and improve the anti-tumor efficacy of dendritic cells(DCs)pulsed with tumor cell lysate in the mice bearing pancreatic adenocarcinoma.The models of pancreatic adenocarcinoma were established in C57BL/6 mice by subcutaneous injection of Pan02 cells.Eight mice which were subcutaneously injected with PBS served as control.The expression of IDO was determined in tumor draining lymph nodes(TDLNs)and spleens of the murine pancreatic adenocarcinoma models.The prevalence of Tregs was measured in the TDLNs and spleens before and after 1-MT administration.The dendritic cells were pulsed with tumor cell lysate for preparing DC vaccine.The DC vaccine,as a single agent or in combination with 1-MT,was administered to pancreatic adenocarcinoma mice.The anti-tumor efficacy was determined after different treatments by regular observation of tumor size.The results showed that the levels of IDO mRNA and protein in tumor-bearing mice were significantly higher than those in the normal control mice.The percentage of Tregs in the spleen and TDLNs was also higer in tumor-bearing mice than in normal control mice(P<0.05).Foxp3 expression was significantly lower in the TDLNs and spleens of tumor-bearing mice administrated with 1-MT than that in normal control mice.Furthemore,in the mice that were administered 1-MT plus DC vaccine,the tumor was increased more slowly than in mice treated with DC vaccine or 1-MT alone,or PBS on day 36(P<0.01).Our results indicated that 1-MT may enhance anti-tumor efficacy of dendritic cells pulsed with tumor cell lysate by downregulating the percentage of Tregs.
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Objective:To investigate the mechanism of indoleamine 2,3-dioxygenase(IDO)in HepG2 cells contributing to tumor immune escape.Methods:T-lymphocyte and HepG2 cell were cocultured,and 1-methyl-tryptophan(1-MT)was added to make an intervening experiment.The expression of IDO mRNA in HepG2 cell cocultured with T-lymphocyte was detected by RT-PCR;the apoptosis rate of HepG2 cell cocultured with T-lymphocyte was analyzed by flow cytometer;The cytotoxicity of T-lymphocyte against HepG2 cell was examined by MTT assay.Results:In combine reaction system,the expression of IDO mRNA was strongly induced in HepG2 cell cocultured with T-lymphocyte and faintly induced when cultured with 1-MT;the earlier apoptosis rate of HepG2 cell in control group and experiment group(1-MT:1.25 mmol/l,2.5 mmol/l,5mmol/l)was respectively(3.48?0.34)%,(7.82?0.41)%,(18.62?0.42)%,(25.32?0.40)%(P