The functions and mechanisms of kynurenine pathway in cognitive dysfunction / 中国医师杂志

Tryptophan (TRP) is an essential amino-acid and the precursor of many signaling molecules. Under the catalysis of indoleamine 2, 3-dioxygenase, kynurenine pathway can form its metabolites uroquinolinic acid and quinolinic acid, which is the main channel of TRP metabolism.Through different mechanisms in N-methyl-D-aspartate receptor, they participate in nervous modulation, affect cognitive processes and play an important role in many central nervous system diseases development. Kynurenine pathway is different under physiological and pathological conditions. In addition, there are many rate-limiting enzymes in the kynurenine pathway, which can interfere kynurenine pathway. This article reviews the relationship between tryptophan/kynurenine pathway and cognitive dysfunction.

Mesenchymal stem cells inhibit the activation and proliferation of CD4+ T cells in Sj(o)gren syndrome by promoting prostaglandin E2, hepatocyte growth factor and indoleamine 2, 3-dioxygenase secretion / 中华风湿病学杂志

Objective To investigate the suppressive effect of prostaglandin E2 (PGE2),hepatocyte growth factor (HGF) and indoleamine 2,3-dioxygenase (IDO) whose secretion was promoted by human umbilical cord mesenchymal stem cells(MSCs) on the activated peripheral blood CD4+ T cells in primary Sj(o)gren syndrome (pSS) in vitro.Methods Primary cultured umbilical cord MSCs were identified by flow cytometry,and peripheral blood CD4+ T cells were sorted in pSS patients.CD4+ T cells were cultured with CD3,CD28 antibody for 72 h to be the activated(control group);the activated CD4+ T cells were co-cultured with MSCs for 72 h(MSCs group) or MSCs were pre-stimulated with interferon-γ (IFN-γ),then the activated CD4+ T cells were co-cultured with pre-stimulated MSCs for 72 h (pre-stimulated group).The suspension of CD4+ T cells were collected and counted.PGE2,HGF and IDO in the supernatants were detected by ELISA.Mean in groups were compared using ANOVA,and multiple comparisons were used with LSD method.Results The concentrations of PGE2 in the supernataut of the control group,MSCs group and pre-stimulated group were (111 ±4) pg/ml,(2 814±6) pg/ml and (2 716±8) pg/ml (F=167 292.12,P＜0.01) respectively.The concentrations of HGF in the above groups were (597±9) pg/ml,(383±9) pg/ml and (727±12) pg/ml(F=878.61,P＜0.01) respectively.The concentrations of IDO in the above groups were (143±4) pg/ml,(835±5) pg/ml and (588±3) pg/ml (F=21 104.41,P＜0.01) respectively.Compared with the control group,levels of PGE2 significantly increased in the MSCs group and the pre-stimulated group that CD4+ T cells were co-cultured with MSCs (t=509.88,P＜0.01 and t=491.48,P＜0.01),and levels of IDO also significantly increased (t=202.69,P＜0.01 and t=130.39,P＜0.01),while the activation and proliferation of CD4+T cells were inhibited (t=-16.20,P＜0.01 and t=-31.48,P＜0.01).Compared with MSCs group,levels of PGE2 and IDO significantly decreased in pre-stimulated group (t=-18.40,P＜0.01 and t=-72.30,P＜0.01),and levels of HGF significantly increased in pre-stimulated group(t=41.51,P＜0.01),while the activation and proliferation of CD4+ T cells were further inhibited (t=-15.28,P＜0.01).Conclusion MSCs can inhibit the activation and proliferation of CD4+ T cells in pSS in vitro.The suppressive effect of MSCs may be achieved by promoting secretion of cytokines such as PGE2,HGF and IDO.HGF plays a more important role in the suppressive effect of MSCs pre-stimulated with IFN-γ.Too much PGE2 or IDO propably results in negative feedback regulation of MSCs.

Research progress of the IDO in reproductive immunology / 中国医师杂志

Indoleamine 2,3-dioxygenase (IDO) is a kind of immune regulation enzyme.IDO is the only rate-limiting enzyme that can catalyze the oxidative clearage of indole ring in tryptophan and its catabolism along the kynurenine pathway.IDO1 is one of the important mechanisms in maternal immune tolerance,which participates in the regulation of maternal-fetal immune relationship.The newly discovered IDO2 also plays an important role in this relationship.The abnormal expression of IDO2 is associated with the male infertility.

The differential effects of traditional Chinese medicine Danchaiheji on dendritic cells / 天津医药

Objective To explore the effects of traditional Chinese formula Danchaiheji on the differentiation of regula?tory dendritic cells (DCs) and the underlying mechanism. Methods The rat blood serums with or without the formula Dan?chaiheji were prepared. The peripheral blood mononuclear cells were separated from the peripheral venous blood of healthy donors. CD14+monocytes were isolated using CD14+magnetic beads and cultured for 5-7 days to obtain immature dendritic cells (imDCs). Then the cells was divided into control group and Danchaiheji containing rat serum group. Control group was divided into two subgroups (containing LPS and without LPS). Danchaiheji containing rat serum group was also divided into two subgroups (containing LPS and without LPS). The surface markers CD86, CD11b and HLA-DR of DCs were detected by flow cytometry. The level of IL-10 was determined by enzyme-linked immunosorbent assays (ELISA). The proliferation of al?logeneic T-cells was detected by flow cytometry and the expression level of indoleamine 2,3-dioxygenase (IDO) was deter?mined using quantitative real-time PCR. Results DCs treated with the formula Danchaiheji exhibited high CD11b and low CD86 and HLA-DR expression levels as well as promoted the secretion of IL-10. In addition, the drug could inhibit the pro?motion of DCs on the proliferation of T cells, which was associated with the up-regulation of IDO expression. Conclusion The traditional Chinese formula Danchaiheji can induce the differentiation of DCs into regulatory DCs and play a role in in?hibitory effect on immune function.

Relationship between Visceral Sensitivity and Tryptophan Metabolic Pathway in Patients with Diarrhea-predominant Irritable Bowel Syndrome / 胃肠病学

Background:Tryptophan(TRP)is an essential amino acid,and can produce 5-hydroxytryptamine(5-HT)via 5-HT signal pathway and kynurenine( KYN)metabolic pathway under the catalysis of enzyme,thereby participating in the pathogenesis of visceral hypersensitivity in diarrhea-predominant irritable bowel syndrome(IBS-D). Aims:To investigate the relationship between visceral sensitivity and TRP metabolic pathway in patients with IBS-D. Methods:Thirty patients with IBS-D and 30 healthy controls from June 2012 to January 2014 at Guangdong Provincial TCM Hospital were enrolled. Score of gastrointestinal symptom rating scale( GSRS)was evaluated. Visceral sensitivity was measured by anorectal manometry. RT-PCR and Western blotting were used to detect mRNA and protein expressions of colon mucosal IDo, respectively. Serum 5-HT,5-HIAA,TRP,IDo,KYN,KYNA concentrations and IDo activity,KAT activity were determined by high performance liquid chromatography assay. Results:Compared with control group,GSRS score was significantly increased(P < 0. 05),initial perception threshold,defecation threshold,pain threshold were significantly decreased(P < 0. 05),anorectal constriction pressure was significantly increased( P < 0. 05),serum 5-HT,5-HIAA concentrations were significantly increased(P < 0. 05),mRNA and protein expressions of IDo were significantly increased (P < 0. 05),serum KYN was significantly increased(P < 0. 05),KYNA was significantly decreased(P < 0. 01),IDo activity was significantly incseased(P < 0. 01),and KAT activity was significantly decreased in IBS-D group(P < 0. 01). Correlation analysis showed that initial perception threshold,defecation threshold,pain threshold and anorectal constriction pressure were correlated with 5-HT,5-HIAA,TRP,KYN,KYNA,IDo activity and KAT activity in patients with IBS-D (P < 0. 05). Conclusions:TRP metabolic pathway is correlated with visceral hypersensitivity in patients with IBS-D.

Effect of inherent depression on chronic visceral hypersensitivity induced by colon acetate stimulation in neonatal rats / 北京大学学报(医学版)

Objective:To explore the effect of inherent depression on chronic visceral hypersensitivity. The differences of visceral sensitivity, colitis, and brain activation between Fawn-Hooded ( FH/Wjd) and Sprague-Dawley( SD) rats were identified after neonatal colon acetate stimulation.Methods:The specific pathogen free Fawn-Hooded (FH/Wjd) and Sprague-Dawley(SD) rats were used to establish irritable bowel syndrome (IBS) model.The visceral sensitivity was measured by colorectal distension (CRD). The expression of 5-hydroxytryptamine (5-HT), mast cell (MC), indoleamine 2,3-dioxygenase (IDO) in colon and IDO in specific cerebral regions were detected through immunohistochemistry.Results:Ab-dominal withdrawal reflex ( AWR) scores showed that visceral sensitivity of acetate-enema groups was sig-nificantly higher than that of saline-enema groups ( FH/Wjd:2.44 ±0.04 vs.1.96 ±0.07, P Besides, the MC amounts of control and IBS group of FH/Wjd rats were significantly more than that of SD IBS group rats ( P<0 .01 ) .The IDO and 5-HT positive cells in colonic mucosa of IBS group of both SD and FH/Wjd rats were significantly more than those of their control groups, respectively(P <0.01). The IDO, 5-HT positive cells in colonic mucosa of both control and IBS group of FH/Wjd rats were significantly more than those of both control and IBS group of SD rats ( control:IDO,24.64 ±2.22 vs. 15.52 ±1.39;5-HT,21.32 ±1.26 vs.12.72 ±1.12.IBS: IDO,44.92 ±2.31 vs.20.85 ±1.72;5-HT, 31.84 ±1.57 vs.19.65 ±1.09.P <0.01).The expression of IDO in prelimbic cortex (PrL) areas of FH/Wjd IBS rats was significantly higher than that of IBS group of SD rats (49.60 ±4.31 vs. 35.60 ±2.42, P <0.01) , and the expression of IDO in rostral anterior cingulate cortex ( rACC) areas of FH/Wjd IBS rats was significantly more than that of FH/Wjd control rats (45.44 ±1.16 vs.34.08 ± 2.76, P <0.01) .Conclusion:Inherent depressive FH/Wjd rats were more sensitive to neonatal colon acetate stimulation, presenting as visceral hypersensitivity which maybe associated with increased MC amounts and over-expression of 5-HT and IDO in colon, suggesting that depression disorder may aggra-vate functional disturbance of gastrointestinal tract by regulating the response to inflammatory stimulation.

Vascular endothelial growth factor-A enhances indoleamine 2,3-dioxygenase expression by dendritic cells and subsequently impacts lymphocyte proliferation

Dendritic cells (DCs) are antigen (Ag)-presenting cells that activate and stimulate effective immune responses by T cells, but can also act as negative regulators of these responses and thus play important roles in immune regulation. Pro-angiogenic vascular endothelial growth factor (VEGF) has been shown to cause defective DC differentiation and maturation. Previous studies have demonstrated that the addition of VEGF to DC cultures renders these cells weak stimulators of Ag-specific T cells due to the inhibitory effects mediated by VEGF receptor 1 (VEGFR1) and/or VEGFR2 signalling. As the enzyme indoleamine 2,3-dioxygenase (IDO) is recognised as an important negative regulator of immune responses, this study aimed to investigate whether VEGF affects the expression of IDO by DCs and whether VEGF-matured DCs acquire a suppressor phenotype. Our results are the first to demonstrate that VEGF increases the expression and activity of IDO in DCs, which has a suppressive effect on Ag-specific and mitogen-stimulated lymphocyte proliferation. These mechanisms have broad implications for the study of immunological responses and tolerance under conditions as diverse as cancer, graft rejection and autoimmunity.

Indoleamine-pyrrole 2,3-dioxygenase might be a prognostic biomarker for patients with renal cell carcinoma / 中南大学学报(医学版)

Objective:To explore the role of indoleamine-pyrrole 2,3-dioxygenase (IDO),an immunomodulatory enzyme,in renal cell carcinoma (RCC).Methods:A total of 40 patients diagnosed as RCC in the Second Xiangya Hospital were included in this study.All patients received nephrectomy.The histopathological features of samples were assessed semi-quantitatively.IDO mRNA level in RCC and non-RCC renal tissues was determined by real-time quantitative PCR (RT-qPCR).And the expression of IDO protein in endothelial cells was examined by immunohistochemistry; a Kaplan-Meier survival curves was calculated on the basis of IDO mRNA level.Results:Level of IDO mRNA in RCC samples was significantly higher than that in tumor-free samples with P＜0.001.Patients with high IDO expression had an significantly longer survival time than those with low IDO expression (P=0.01).There was a statistically significant inverse correlation between IDO and proliferation marker Ki67.Patients with high IDO level were of low Ki67 level,and vice versa (P＜0.01).Conclusion:IDO might be a prognostic biomarker for patients with RCC.

Myeloid differentiation primary response protein 88 blockade upregulates indoleamine 2,3-dioxygenase expression in rheumatoid synovial fibroblasts

Indoleamine 2,3-dioxygenase (IDO) is a key negative regulator of immune responses and has been implicated in tumor tolerance, autoimmune disease and asthma. IDO was detected in the joint synovial tissue in the inflammatory microenvironment of rheumatoid arthritis (RA), but IDO expression in joint synovial tissue is not sufficient to overcome the inflamed synovial environment. This study aimed to unravel the mechanisms involving the failure to activate tolerogenic IDO in the inflamed joint. We demonstrate that both poly (I:C) and lipopolysaccharide (LPS) induce expression of IDO in synovial fibroblasts. However, inflammatory cytokines such as IL-17, TNF-alpha, IL-12, IL-23 and IL-16 did not induce IDO expression. Poly (I:C) appeared to induce higher IDO expression than did LPS. Surprisingly, toll-like receptor (TLR)4-mediated IDO expression was upregulated after depletion of myeloid differentiation primary response protein 88 (MyD88) in synovial fibroblasts using small interfering RNA (siRNA). IDO, TLR3 and TLR4 were highly expressed in synovial tissue of RA patients compared with that of osteoarthritis patients. In addition, RA patients with severe disease activity had higher levels of expression of IDO, TLR3 and TLR4 in the synovium than patients with mild disease activity. These data suggest that upregulation of IDO expression in synovial fibroblasts involves TLR3 and TLR4 activation by microbial constituents. We showed that the mechanisms responsible for IDO regulation primarily involve MyD88 signaling in synovial fibroblasts, as demonstrated by siRNA-mediated knockdown of MyD88.

Construction and identification of a recombinant adenovirus vector with indoleamine 2,3-deoxygenase and chimeric albumin promoter / 中华普通外科杂志

Objective To construct a recombinant adenovirus vector encoding for indoleamine 2,3-dioxygenase(IDO)and chimetric albumin promoter,evaluate the mRNA and protein expression levels in Hepa 1-6cell.Methods Full-length mouse derived IDO cDNA was subeloned into pAdTraek-ALB shuttle Plasmid.The product was linearized to homologous recombination with AdEasy-l vector in BJ5183 bacteria.The positive clone was identified by restriction endonuclease digestion and further confirmed by sequencing.The recombined adenoviruses DNA were transfected into AD-293 cells for packaging and amplification of Ad-ALB/IDO.The expression of IDO was monitored by RT-PCR and EGFP fluorescence in infected cells.The recombinant viruses with Hepa 1-6 cells were cultured and the mRNA and protein expression levels monitored bv RT-PCR and Western blot, respectively. Results Construction of recombinant andenoviruses containing IDO and albumin promoter was confirmed by restriction endonuclease digestion and sequencing.The expression of IDO was identified by RT-PCR in transfected AD-293 cell.The virus titer was 2.9×10~6 pfu/ml.The IDO mRNA and protein expression levels were detectable after transfected Hepa 1-6 cells by RT-PCR and Western blot. Conclusion A recombinant adenovirus Ad-ALB/IDO was susceessfullyconstructed.

Indoleamine 2,3-dioxygenase and immune tolerance in tumor / 国际肿瘤学杂志

Clonal suppression induced by CD4+ CD25+ regulatory T cells is one of the principal factors to evoke the immune tolerance in tumor. Through the activation of CD4+ CD25+ regulatory T cells, the indoleamine 2,3-dioxygenase (IDO) reduces the immune response in tumor micro-environment of various systems , and induces the formation of host immune tolerance. IDO inhibitor 1-MT is expected to become a new target for cancer treatment.

Soluble mediators from mesenchymal stem cells suppress T cell proliferation by inducing IL-10

Mesenchymal stem cells (MSCs) can inhibit T cell proliferation; however, the underlying mechanisms are not clear. In this study, we investigated the mechanisms of the immunoregulatory activity of MSCs on T cells. Irradiated MSCs co-cultured with either naive or pre-activated T cells in a mixed lymphocyte reaction (MLR) significantly suppressed T cell proliferation in a dose-dependent manner, irrespective of allogeneic disparity between responders and MSCs. Transwell assays revealed that the suppressive effect was primarily mediated by soluble factors that induced apoptosis. Splenocytes stimulated with alloantigen in the presence of the MSC culture supernatant (CS) produced a significant amount of IL-10, which was attributed to an increase in the number of IL-10 secreting cells, confirmed by an ELISPOT assay. The blockade of IL-10 and IL-10 receptor interaction by anti-IL-10 or anti-IL-10-receptor antibodies abrogated the suppressive capacity of MSC CS, indicating that IL-10 plays a major role in the suppression of T cell proliferation. The addition of 1-methyl-DL-tryptophan (1-MT), an indoleamine 2,3-dioxygenase (IDO) inhibitor, also restored the proliferative capacity of T cells. In conclusion, we demonstrated that soluble mediators from culture supernatant of MSCs could suppress the proliferation of both naive and pre-activated T cells in which IL-10 and IDO play important roles.

Soluble mediators from mesenchymal stem cells suppress T cell proliferation by inducing IL-10

Mesenchymal stem cells (MSCs) can inhibit T cell proliferation; however, the underlying mechanisms are not clear. In this study, we investigated the mechanisms of the immunoregulatory activity of MSCs on T cells. Irradiated MSCs co-cultured with either naive or pre-activated T cells in a mixed lymphocyte reaction (MLR) significantly suppressed T cell proliferation in a dose-dependent manner, irrespective of allogeneic disparity between responders and MSCs. Transwell assays revealed that the suppressive effect was primarily mediated by soluble factors that induced apoptosis. Splenocytes stimulated with alloantigen in the presence of the MSC culture supernatant (CS) produced a significant amount of IL-10, which was attributed to an increase in the number of IL-10 secreting cells, confirmed by an ELISPOT assay. The blockade of IL-10 and IL-10 receptor interaction by anti-IL-10 or anti-IL-10-receptor antibodies abrogated the suppressive capacity of MSC CS, indicating that IL-10 plays a major role in the suppression of T cell proliferation. The addition of 1-methyl-DL-tryptophan (1-MT), an indoleamine 2,3-dioxygenase (IDO) inhibitor, also restored the proliferative capacity of T cells. In conclusion, we demonstrated that soluble mediators from culture supernatant of MSCs could suppress the proliferation of both naive and pre-activated T cells in which IL-10 and IDO play important roles.