High Indoleamine 2,3-dioxygenase Expression Research Articles

Alleviation of Rheumatoid Arthritis by Inducing IDO Expression with Trichinella spiralis Recombinant Protein 43.

Rheumatoid arthritis (RA) represents the autoimmune disorder that shows aggressive arthritis as the main symptom. It is difficult to treat and can lead to joint deformation and function loss. At present, Trichinella spiralis (T. spiralis) antigen has attracted much attention because it plays a role in host immune regulatory mechanisms. Therefore, we selected T. spiralis recombinant protein 43 (Tsp43) to treat the bovine collagen type II (BCII)-induced mice RA model and explored its therapeutic mechanisms. This work first verified that Tsp43 could promote the expression of indoleamine 2, 3-dioxygenase (IDO) in dendritic cells (DCs) in vitro. Then, we randomized BALB/c mice (8 weeks old) into six groups, including control, phosphate buffer saline (PBS), BCII, BCII + heat inactivated Tsp43 (HiTsp43), BCII + Tsp43, and BCII + Tsp43 + 1-methyl-troptophan (1-MT) groups. To determine the therapeutic effect of Tsp43 on the BCII-induced mice RA model, relevant cytokines in each group and pathological changes in ankle joints were detected. To explore the mechanisms of Tsp43 on the BCII-induced mice RA model, we checked the expression of IDO in each group, CD4+T cell proliferation, and apoptosis. Collectively, Tsp43 decreased tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) expression in BCII-induced mice RA model and recovered the ankle injury to a certain extent. Tsp43 promoted high expression of IDO, caused expression of related apoptotic proteins in CD4+T cells, and caused apoptosis in CD4+T cells. In addition, Tsp43 reduced the proliferation of CD4+T cells. However, these effects can be inhibited by 1-MT (IDO inhibitor). These results suggested that Tsp43 played an important role in the treatment of arthritis by inhibiting the proliferation of CD4+T cells and inducing CD4+T cells apoptosis through the high expression of IDO. The purpose of this experiment was to provide a new idea for the treatment of RA and lay a foundation for the development of parasite-derived drugs for the treatment of RA.

Expression of immune checkpoints (PD-L1 and IDO) and tumour-infiltrating lymphocytes in breast cancer

BackgroundBreast cancer (BC) has become the most common cancer globally in 2020 as well as in the United Arab Emirates. The breast tumor microenvironment is composed of various immune cell types, including lymphocytes. Tumour-infiltrating lymphocytes (TILs) play a crucial role in tumor eradication and progression. Further, immune checkpoint markers such as programmed death receptor ligand 1 (PD-L1) and indoleamine-2,3-dioxygenase (IDO) have been associated with tumor evasion from the immune system. In this study, we aimed to explore the status of TILs, PD-L1 and IDO as well as to investigate their association with the clinicopathological parameters. Materials and methodsA total of 59 patients diagnosed with primary infiltrating BC were selected, after which tissue sections were stained to identify TILs along with immunohistochemical staining of PD-L1 and IDO. Moreover, in-silico tools were used to assess the expression of PD-L1, IDO and CD3ε in various molecular subtypes of BC. ResultsIt was found that the percentage of TILs correlated with estrogen receptor (ER) and progesterone receptor (PR) expression. This was supported by the finding that most of the triple-negative breast cancer (TNBC) cases belonged to the group with a high percentage of TILs (h-TILs). Similarly, the expression of PD-L1 and IDO was correlated with the ER and PR, whereas TNBC cases showed a high expression of PD-L1 and IDO. This goes in line with the in-silico findings where the TNBC group showed the highest expression of PD-L1 and IDO as well as the T cell marker CD3ε. ConclusionThis study highlighted a possible link between the immunosuppressive markers PD-L1 and IDO with TILs density in the BC microenvironment.

P14.02 Expression and Significance of Indoleamine 2,3 Dioxygenase on Tumor Cell and Tumor Stroma Compartments of Lung Squamous Cell Carcinoma

Indoleamine 2,3 dioxygenase (IDO), a human immune escape factor, especially in pregnant women, is a immune suppressor that protects the fetus from maternal immune rejection. IDO, the tryptophan-metabolizing enzyme, is an important regulator of tumor immune suppression through inhibiting lymphocytic functions, and is frequently increased expression in solid tumor. This aimed to expound expression and significance of indoleamine 2,3 dioxygenase (IDO) on tumor cell (TC) and tumor stroma compartments (TSC) of lung squamous cell carcinoma (LSCC). Patients with resected specimen from 2015 to 2018 in Taizhou Hospital of Zhejiang Province were enrolled included in this study. The expressions of IDO (ab211017) in on TC and TSC of tumor tissue and adjacent tissue were evaluated by immunohistochemistry (IHC). The results of staining were scored according to the intensity of staining with Fourtier system (level 0–3: negative = 0, weakest = 1, moderate = 2, strong = 3) and staining positive rate score: 0 (negative), 1 (1-25%), 2 (26-50%), 3 (51-75%), 4 (76-100%). Total score was the product of "intensity score" and "positive rate score". And grouping was divided into that < 6 was low expression group, while ≥ 6 was divided into high expression group. Three pathologists, who were blind to all clinical and biological data, performed and analyzed IHC. A total of 86 patients with resected tissue specimen available for IHC analysis were studied. The high and low expression of IDO were identified in 37(43.02%), 49(56.98%) and 12(13.95%), 74(86.05%) on TC of tumor tissue and adjacent tissue from LSCC patients, respective. And, the high and low expression of IDO were identified in 20(23.26%), 66(76.74%) and 45(52.33%), 41(47.67%) in TSC of tumor tissue and adjacent tissue from LSCC patients, respective. Patients with high expression of IDO showed significantly poorer overall survival than those with low expression of IDO (not reached months versus 57 months respectively) (p = 0.025) on TC of tumor tissue. In the same way, the high IDO expression were showed significantly poorer overall survival than those with low expression of IDO (not reached months versus 29 months respectively) (p = 0.025) on TSC of tumor tissue. IDO expression was higher in tumor tissues than in adjacent tissues. IDO expression not only on TC but also on TSC of tumor tissue may be useful for predicting the prognosis in LSCC patients. Further studies on the correlation between IDO and PDL1 and co-expression rates need to be carried out.

IDO in Colorectal Tumorigenesis: Involvement of Immune Tolerance and Significance in Prevention and Therapy

IDO in Colorectal Tumorigenesis: Involvement of Immune Tolerance and Significance in Prevention and Therapy

Forkhead box P3 and indoleamine 2,3-dioxygenase co-expression in Pakistani triple negative breast cancer patients.

BACKGROUNDForkhead box P3 (FOXP3) is a specific marker for immunosuppressive regulatory T (T-reg) cells. T-regs and an immunosuppressive enzyme, indoleamine 2,3-dioxygenase (IDO), are associated with advanced disease in cancer. AIMTo evaluate the co-expression of FOXP3 and IDO in triple negative breast cancer (TNBC) with respect to hormone-positive breast cancer patients from Pakistan. METHODSImmunohistochemistry was performed to analyze the expression of FOXP3, IDO, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor on tissues of breast cancer patients (n = 100): Hormone-positive breast cancer (n = 51) and TNBC (n = 49). A total of 100 patients were characterized as FOXP3 negative vs positive and further categorized based on low, medium, and high IDO expression score. Univariate and multivariate logistic regression models were used.RESULTSOut of 100 breast tumors, 25% expressed FOXP3 positive T-regs. A significant co-expression of FOXP3 and IDO was observed among patients with TNBC (P = 0.01) compared to those with hormone-positive breast cancer. Two variables were identified as significant independent risk factors for FOXP3 positive: IDO expression high (adjusted odds ratio (AOR) 5.90; 95% confidence interval (CI): 1.22-28.64; P = 0.03) and TNBC (AOR 2.80; 95%CI: 0.96-7.95; P = 0.05). CONCLUSIONOur data showed that FOXP3 positive cells might be associated with high expression of IDO in TNBC patients. FOXP3 and IDO co-expression may also suggest its involvement in disease, and evaluation of FOXP3 and IDO expression in TNBC patients may offer a new therapeutic option.

Inflammation-Induced Tryptophan Breakdown is Related With Anemia, Fatigue, and Depression in Cancer.

Many patients with cancer suffer from anemia, depression, and an impaired quality of life (QoL). These patients often also show decreased plasma tryptophan levels and increased kynurenine concentrations in parallel with elevated concentrations of Th1 type immune activation marker neopterin. In the course of anti-tumor immune response, the pro-inflammatory cytokine interferon gamma (IFN-γ) induces both, the enzyme indoleamine 2,3-dioxygenase (IDO) to degrade tryptophan and the enzyme GTP-cyclohydrolase I to form neopterin. High neopterin concentrations as well as an increased kynurenine to tryptophan ratio (Kyn/Trp) in the blood of cancer patients are predictive for a worse outcome. Inflammation-mediated tryptophan catabolism along the kynurenine pathway is related to fatigue and anemia as well as to depression and a decreased QoL in patients with solid tumors. In fact, enhanced tryptophan breakdown might greatly contribute to the development of anemia, fatigue, and depression in cancer patients. IDO activation and stimulation of the kynurenine pathway exert immune regulatory mechanisms, which may impair anti-tumor immune responses. In addition, tumor cells can degrade tryptophan to weaken immune responses directed against them. High IDO expression in the tumor tissue is associated with a poor prognosis of patients. The efficiency of IDO-inhibitors to inhibit cancer progression is currently tested in combination with established chemotherapies and with immune checkpoint inhibitors. Inflammation-mediated tryptophan catabolism and its possible influence on the development and persistence of anemia, fatigue, and depression in cancer patients are discussed.

Chemoresistance was correlated with elevated expression and activity of indoleamine 2,3-dioxygenase in breast cancer.

Indoleamine 2,3-dioxygenase (IDO) catalyses degradation of the essential amino acid tryptophan leading to the production of immunosuppressive kynurenine and tryptophan exhausting. IDO expression and activity contribute to aggressive tumor growth, inferior therapeutic gain and poor prognosis. The aim of this study was to explore the association between chemoresistance and IDO expression, activity in breast cancer METHODS: Immunohistochemistry was applied for evaluating IDO expression in biopsy tissues. Serum IDO activity was examined via High-performance liquid chromatography (HPLC). Western blots (WB), HPLC and Real-time PCR (RT-PCR) were used to analyze IDO protein, IDO enzyme activity and IDO gene expression in original and paclitaxel-resistant cells respectively. Logistic regression and survival analysis were applied to explore the association between chemoresistance and IDO expression, activity in breast cancer. IDO expression in tumor tissues was associated with serum IDO activity (P = 0.004). Both IDO expression in tumor and serum activity were associated with clinical tumor stage, node stage and estrogen receptor (ER) status (all P < 0.05); clinical response and pathologic complete response (pCR) to NAC were both related to IDO expression and activity prior NAC (all P < 0.05). Multivariate analysis showed IDO activity before NAC was the only independent factor affected pCR (P = 0.032). ROC curves showed that the IDO expression and activity had discriminative ability for predicting the clinical response and pCR. In the prognostic analysis, patients with high IDO expression had significantly impaired overall survival (5year survival rate: 53.57% vs 80.00%) and progression-free survival (5year survival rate: 46.43% vs 72.00%, P = 0.031 and P = 0.046). In vitro, significantly increased IDO protein, IDO mRNA expression and IDO enzyme activity in paclitaxel-resistant cells were demonstrated in comparing of sensitive cells. IDO expression and activity associated with advanced breast cancer, poor response to neoadjuvant chemotherapy and prognosis. IDO expression and activity were significantly increased in paclitaxel-resistant breast cancer cells.

Association between Cyclooxygenase-2 and Indoleamine 2,3-Dioxygenase Expression in Breast Cancer Patients from Pakistan.

Background:Tumors use several immunosuppressive mechanisms to evade immune destruction. Cyclooxygenase-2 (COX-2) expression may be a driver of immunosuppression in breast cancer, but the mechanisms involved remain elusive. COX-2 expression induces the expression of indoleamine 2,3 dioxygenase (IDO) in tumor cells. IDO is an immunosuppressive enzyme which is involved in tumor immune escape mechanisms in breast cancer. Our aim was to evaluate the association between COX-2 and IDO expression to find evidence of immunosuppression in Pakistani breast cancer patients. Methods:Immunohistochemical analysis was performed to evaluate the expression of COX-2, IDO, estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) on formalin-fixed paraffin-embedded breast cancer tissues of 100 patients. Univariable and multivariable logistic regression model was used to identify the independent risk factors of COX-2. Results:A total of 100 patients were included with a mean age and standard deviation of 48.28 ± 11.83. A significant association was observed among COX-2, IDO, ER, PR and tumor grade. In multivariable analysis, three variables were identified as significant independent risk factors for high COX-2: IDO expression high; [adjusted odds ratio (AOR) 6.51; 95% confidence interval (CI) (2.00-21.20), p=0.001], ER; [AOR 5.62; 95% CI (1.80-17.84), p=0.002] and age [AOR 1.04; 95% CI (1.00-1.10), p=0.05] respectively. Conclusion:Our data showed that high IDO expression is associated with high COX-2 expression in Pakistani breast cancer patients. The co-expression of both enzymes may suggest their role in disease pathogenesis. Hence the concurrent targeting of COX-2 and IDO may be a promising therapy for breast cancer.

Abstract LB-184: The immunotherapeutic role of indoleamine 2,3-dioxygenase (IDO) in head and neck squamous cell carcinoma: a systematic review

Abstract Background: Novel cancer immunotherapy includes application of immune checkpoint inhibitors to the treatment of solid tumors. The body’s own immune system is thereby harnessed to tip the balance in favor of antitumor activity. The intracellular enzyme indoleamine 2,3-dioxygenase (IDO) is a critical regulator of the tumor microenvironment (TME) via tryptophan metabolism. Programmed death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) are immune checkpoints involved in T-cell inhibition and immunosuppression. Another immune checkpoint, IDO1, breaks down tryptophan into its metabolites which results in immunosuppression in the TME. Aim: To assess the evidence on IDO in head and neck squamous cell carcinoma (HNSCC). Methods: Medline, EMBASE using Ovid, Scopus, Web of Science, Cochrane Library databases, and ClinicalTrials.gov were searched from inception until present day. Results: We included 32 studies. Of those, 5 involved cell lines, 7 assessed tumor immunohistochemistry, 6 measured IDO gene transcription, and 14 reported on clinical trials. The human cell lines studied commonly were SCC4, SCC15, and SCC25 in which IDO expression and activation by the Stimulator of Interferon Genes (STING) pathway played a central role. Retrospective immunohistochemistry studies of lower lip, oral cavity, tongue, tonsil, and larynx found that relatively high IDO expression correlated with worse survival. Gene transcription studies showed increased IDO in tumors that expressed PD-L1 and harbored human papillomavirus (HPV). Phase I/II clinical trials showed 1) objective responses (34%) and disease control rates (62%) for IDO1 inhibitor in combination with a PD-1 inhibitor, 2) consistent safety profile in combination versus monotherapy, and 3) IDO gene expression as a predictive biomarker for response to PD-L1 therapy. Conclusions: IDO is integral to TME immunity in HNSCC particularly in HPV positive tumors, modulating existing therapies and application in combinatorial immunotherapy. Retrospective studies have shown the presence of IDO in the TME and suggest a link to prognosis and prediction of HNSCC treatment outcome. However, the exact mechanism of IDO-driven immune modulation in the HNSCC TME remains unclear. We now require prospective longitudinal studies to track IDO activity and expression throughout HNSCC treatment, thence optimise IDO-based immunotherapy. Citation Format: Daniel J. Lin, James C. Ng, Lei Huang, Max Robinson, James O'Hara, Janet A. Wilson, Andrew L. Mellor. The immunotherapeutic role of indoleamine 2,3-dioxygenase (IDO) in head and neck squamous cell carcinoma: a systematic review [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-184.

IDO and intra-tumoral neutrophils were independent prognostic factors for overall survival for hepatocellular carcinoma.

BackgroundBoth Indole‐amine‐2,3‐dioxygenase (IDO) and neutrophils were proved to have pro‐tumor effect in some kinds of solid tumors by immune suppression. However, little is known about their effect on hepatocellular carcinoma (HCC) and the relationship between these two immune‐suppressive factors. The aim of this study was to evaluate the prognostic significance of IDO and intra‐tumoral neutrophils and their correlations in HCC.MethodsSpecimens’ tissue microarray (TMA) for 153 HCC patients was used in this study. We examined intra‐tumoral expression of IDO and CD66b in TMA. The Kaplan‐Meier method and Cox regression models were used to evaluate the prognostic value of IDO expression and CD66b.ResultsMultivariate analysis showed both IDO expression and intra‐tumoral neutrophils infiltration were independent prognostic factors for overall survival (OS). In high IDO expression group, the percentage of intra‐tumoral neutrophils infiltration was higher than that in low IDO expression group.ConclusionBoth IDO and intra‐tumoral neutrophils were independent prognostic factors for overall survival for HCC.

High Expression of Indoleamine 2, 3-Dioxygenase in Adenosquamous Lung Carcinoma Correlates with Favorable Patient Outcome.

Background: Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in tryptophan (Trp) metabolism, is generally considered to be an immunosuppressive molecule. The prognostic role of IDO expression in tumor has not been well studied in non-small cell lung cancer (NSCLC) and even not been reported in adenosquamous lung carcinoma (AdSqLC). Herein, the aim of this study is to investigate the prognostic significance of IDO expression in patients with AdSqLC.Patients and Methods: We conducted immunohistochemical analyses of IDO expression, as well as CD3 and CD8 expression, in 183 primary tumor tissue samples from patients with AdSqLC treated at our institution between July 1999 and September 2014. Patients' clinicopathological characteristics were retrospectively reviewed. Survival analysis was performed in the entire cohort of patients and those who received radical resection, respectively.Results: IDO was expressed in 146 (79.8%) tumor samples. A higher level of IDO expression was significantly associated with increased CD8+ tumor-infiltrating lymphocytes (TILs) in tumor tissues (P<0.001). Surprisingly, overall survival (OS) was significantly better for patients with high IDO expression (hazard ratio (HR)= 0.505; confidence interval (CI)= 0.329-0.775; P=0.002) for the entire cohort. In patients who were unable to be treated with radical resection, IDO expression had no effect on OS (P=0.598). In contrast, a significant, independent association between high expression of IDO and better OS (HR=0.469; CI=0.290-0.758; P=0.002) was identified in patients who received radical resection.Conclusions: IDO is expressed in most AdSqLC tissues, with a higher level of IDO expression associated with an occurrence of CD8+ TILs. Moreover, IDO expression in tumor promises to serve as a strongly independent favorable prognostic factor, particularly in patients who received radical resection.

Indoleamine 2,3-dioxygenase expression and overall survival in patients diagnosed with breast cancer in Pakistan.

BackgroundImmune dysfunction in breast cancer patients is well established. Indoleamine 2,3-dioxygenase (IDO) is an immunosuppressive enzyme that is linked with progression of cancer. IDO is overexpressed in triple-negative breast cancer (TNBC) cases.Materials and methodsWe conducted the first study to analyze IDO expression and overall survival in breast cancer cases in Pakistan. Expression of IDO, estrogen receptor (ER), progesterone receptor (PR), and human EGF receptor 2 (HER2) was evaluated by immunohistochemistry. Formalin-fixed paraffin-embedded breast cancer tissues of 100 (TNBC, n=49 and non-TNBC, n=51) patients were obtained from Shaukat Khanum Memorial Cancer Hospital and Research Centre. IDO expression was analyzed in association with clinicopathological features and overall survival. A total of 100 patients were classified based on the ordinal IDO score variables as low, medium, and high. In addition, overall mean age and SD of patients was 48.28±11.82.ResultsImmunohistochemical analysis showed that high IDO was observed in the TNBC patients (65.3%) compared to that in the non-TNBC patients (33.3%). Multivariable analyses showed that TNBC was an independent risk factor for high IDO expression. Overall survival was also significantly associated with IDO score.ConclusionOur study showed that IDO protein expression is higher in TNBC patients (P<0.01) and may suggest its role in disease pathogenesis. TNBC might be effectively treated with IDO inhibitors. Furthermore, high IDO expression is considerably associated with overall decreased patient survival. IDO might be utilized as a potential biomarker and immunotherapeutic target in breast cancer patients.

Quantitative Assessment of Indoleamine 2,3-Dioxygenase (IDO) Expression at Diagnosis Predicts Clinical Outcome in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation

IntroductionIndoleamine 2,3-dioxygenase (IDO) is an intracellular heme-containing enzyme that catalyzes the initial rate-limiting step in tryptophan degradation along the kynurenine pathway. IDO is physiologically expressed by a wide variety of human cells in response to several stimuli and it is known to have a crucial role in the induction of immune tolerance during pregnancy, infections, transplantation, autoimmunity and tumors. IDO-mediated tryptophan degradation results in inhibition of T-cell proliferation, increase of T-cell apoptosis and T-reg induction. Several studies demonstrated that IDO production can induce the increase of Regulatory T-cells (Tregs) directly through the conversion of CD25- into CD25+ T cells, even in acute myeloid leukemia (AML) patients. IDO expression can be considered a novel mechanism of leukemia escape from immune control and its inhibition may represent an antileukemia therapeutic strategy. Aim of our work is to analyze IDO mRNA expression in a cohort of AML patients and to investigate the presence of any significant correlation between IDO expression and standard prognostic factors or clinical outcome.MethodsWe analyzed a cohort of 68 adult patients aged 18 years or older, who were diagnosed with de novo or secondary AML. IDO mRNA expression was evaluated by Real-Time (RT)-PCR in blood bone marrow and peripheral blood samples at diagnosis. Patients were then retrospectively stratified according to standard risk factors at diagnosis and to IDO mRNA expression levels.ResultsMedian age of analyzed patients was 57 years (range 21-76). Fifty-nine out of 68 patients (87%) had de novo AML, whereas 9 out of 68 patients (13%) had secondary AML. A comprehensive risk assessment was available for 61 patients. Among these 61 patients who were evaluable for risk stratification, 13 patients (21%) resulted to have a favorable risk AML, 30 (49%) had an intermediate risk AML and 17 patients (30%) were stratified as high-risk AML. Sixty out of 68 patients received intensive, standard, induction chemotherapy regimens. The remaining 8 patients were not candidate to receive intensive chemotherapy mainly because of comorbidities. Twenty-three out of 68 patients (34%) were considered eligible for allogeneic stem cells transplantation (alloSCT) as consolidation therapy, after obtaining complete remission with standard chemotherapy. IDO expression in peripheral blood (PB) samples was between 0.07 and 4272.26 (median 5.60). Conversely, IDO expression in bone marrow (BM) samples was between 0.17 and 243.16 (median 1.21). Our data did not establish any significant correlation between IDO expression and leukemia risk factors at diagnosis, in particular cytogenetics, de novo or secondary AML, leukocytosis. Among the 60 patients who received induction chemotherapy, 35 achieved morphological complete remission (CR), 24 did not respond and 1 patient was not evaluable for response. Response to induction chemotherapy was not influenced by IDO mRNA expression levels. Interestingly, among patients undergoing alloSCT, high levels of IDO mRNA expression in PB samples negatively correlated with patients' overall survival. In particular, high IDO expression of more than 10 was associated with worse overall survival after alloSCT even when adjusted by patients' age and disease status at transplant (log rank P=0.02) (Fig.1). With the limitations of the low number of patients, these results from the group of transplanted patients were not likely due to differences in the incidence and severity of graft-versus-host-disease, whereas high IDO mRNA expression level was predictive of increased incidence of relapse.ConclusionsThis work suggests that IDO mRNA expression levels can be considered as predictive of AML outcome, independently from other risk factors at diagnosis. In our set, higher level of IDO mRNA expression at diagnosis was correlated with worse clinical outcome in patients undergoing alloSCT. Larger studies are warranted in order to establish the real predictive role of IDO mRNA expression in influencing AML outcome. DisclosuresCavo:Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Overexpression of indoleamine 2,3-dioxygenase correlates with regulatory T cell phenotype in acute myeloid leukemia patients with normal karyotype.

BackgroundProduction of immunosuppressive enzymes such as indoleamine 2,3-dioxygenase (IDO) is one of the strategies employed by hematologic malignancies, including acute myeloid leukemia (AML), to circumvent immune surveillance. Moreover, IDO has the ability to convert CD4+CD25− conventional T cells into regulatory T cells (Tregs). In this study, we evaluated the expression of IDO in cytogenetically normal acute myeloid leukemia (CN-AML) patients and its correlation with the Treg marker, FOXP3, as well as clinical and laboratory parameters.MethodsThirty-seven newly diagnosed CN-AML patients were enrolled in our study along with 22 healthy individuals. The expression of the IDO and FOXP3 genes was analyzed by SYBR Green real-time PCR.ResultsBoth IDO and FOXP3 were highly upregulated in CN-AML patients compared to control groups (P=0.004 and P=0.031, respectively). A positive correlation was observed between IDO and FOXP3 expression among AML patients (r=0.512, P=0.001). Expression of IDO and FOXP3 showed no significant correlation with laboratory parameters such as white blood cell and platelet counts, hemoglobin levels, bone marrow blast percentage, gender, and FLT3 mutation status (P>0.05).ConclusionHigher IDO expression in CN-AML patients may be associated with an increased Treg phenotype which may promote disease progression and lead to poor prognosis of CN-AML patients.

Immunotolerant indoleamine-2,3-dioxygenase is increased in condyloma acuminata.

The tryptophan-depleting enzyme indoleamine-2,3-dioxygenase (IDO) is critical for the regulation of immunotolerance and plays an important role in immune-associated skin diseases. To analyse the level of IDO in condyloma acuminata (CA) and its role in this condition. IDO expression was assessed in the skin and peripheral blood of healthy controls and patients with CA. To assess the role of skin IDO in immunity, the ability of isolated epidermal cells to metabolize tryptophan and the influence on polyclonal T-cell mitogen (PHA)-stimulated T-cell proliferation were explored. IDO median fluorescence intensities in peripheral blood mononuclear cells from patients with CA were similar to those from healthy controls. Immunohistochemistry showed that IDO+ cells were rare in normal skin and the control skin of patients with CA, but were greatly accumulated in wart tissue. Most fluorescence signals of IDO+ cells did not overlap with those of CD1a+ Langerhans cells. Human papillomavirus (HPV) DNA probe in situ hybridization showed a large number of IDO+ cells in the HPV- site. Keratinocytes in the skin of healthy controls and the circumcised skin of patients with CA could minimally transform tryptophan into kynurenine, but IDO-competent epidermal cells from warts could transform tryptophan. In addition, these IDO-competent epidermal cells could inhibit PHA-stimulated T-cell proliferation. The addition of an IDO inhibitor, 1-methyl-d-tryptophan, restored the inhibited T-cell proliferation. Abnormally localized high IDO expression might be involved in the formation of a local immunotolerant microenvironment.

Expression of CXCR-4 and IDO in human colorectal cancer: An immunohistochemical approach.

C-X-C chemokine receptor type 4 (CXCR4), the receptor for the chemokine stromal cell-derived factor (SDF)-1 [also known as C-X-C motif chemokine 12 (CXCL12)], is involved in lymphocyte trafficking. Recent studies have demonstrated that, during pregnancy, a placental enzyme called indoleamine 2, 3-dioxygenase (IDO) exerts a key role in suppressing the maternal T-cell response against the fetus. In the present study, the significance of CXCR4 and IDO expression in human colorectal cancer (CRC) has been investigated by immunohistochemical assay, and their association with survival was analyzed. Tumor specimens (n=60) from patients with different American Joint Committee on Cancer (AJCC) stages of CRC (I or IV) were assessed. In the stage IV group, 23 of 30 cases (77%) stained positive for CXCR4, and 9 of 30 (30%) were positive for IDO. By contrast, in the stage I group, 7 of 30 cases (23%) stained positive for CXCR4, and 15 of 30 cases (50%) were positive for IDO. The 5-year survival rate of those with high CXCR4 expression in tumor specimens (n=30) was significantly worse compared with those with negative CXCR4 expression (16.3 vs. 60.7%, P=0.02). By contrast, the 5-year survival rate of those with high IDO expression in tumor specimens (n=24) was not significantly different compared with those with negative IDO expression (36.4 vs. 56.8%). In the stage I group, 4 patients in the high IDO expression group (n=15) had distant metastases (2 in the liver 1 in the brain, and 1 in the lung). Taken together, CXCR4 appears to be a novel predictive indicator of survival, and IDO expression in the early stage may be a predictor of distant metastasis.

Expression and Prognostic Value of Indoleamine 2,3-dioxygenase in Pancreatic Cancer

Background:Indoleamine 2,3-dioxygenase (IDO), an enzyme for tryptophan metabolism through the kynurenine pathway, exhibits an immunosuppressive effect and induces immune tolerance in tumor cells. The effects of IDO on pancreatic cancer are poorly understood. This study aimed to investigate the expression and prognostic significance of IDO in pancreatic cancer.Methods:We evaluated the protein expression of IDO in PANC-1, CFPAC-1, and BxPC-3 cell lines with or without 48 h treatment by 500 U/ml interferon-γ (IFN-γ). We performed immunohistochemical staining and Western blot analysis for IDO expression in both pancreatic cancer and normal pancreas tissues obtained from Chinese PLA General Hospital from July 2012 to December 2013. Survival analysis was performed to correlate IDO expression and histopathologic parameters with overall survival. The Kaplan-Meier method and Cox proportional hazards regression model were conducted.Results:PANC-1, CFPAC-1, and BxPC-3 cell lines expressed IDO at the protein level, and the relative expression amount increased after stimulation with 500 U/ml IFN-γ. Immunohistochemical analysis results revealed that high IDO expression was observed in 59% of pancreatic adenocarcinoma tissues. Compared with normal pancreatic tissues, pancreatic adenocarcinoma showed significantly higher IDO expression levels, especially among patients with high tumor node metastasis (TNM) stages (χ2 = 4.550, P = 0.030), poor histological differentiation (χ2 = 5.690, P = 0.017), and lymph node metastasis (χ2 = 4.340 P = 0.037). Kaplan-Meier survival curves showed that high IDO expression was correlated with low survival rates (hazard ratio [HR] = 0.49 P = 0.009). Multivariate analysis using Cox proportional hazards model indicated that lymph node metastasis (HR = 0.35 P = 0.010) and IDO expression (HR = 0.42 P = 0.020) were two independent prognostic predictors of pancreatic adenocarcinoma.Conclusions:The study confirmed that high IDO expression in pancreatic adenocarcinoma was related to poor prognosis of patients. These findings provided evidence that IDO was involved in pancreatic adenocarcinoma progression and might serve as a relevant therapeutic target.

Indoleamine 2,3-dioxygenase and regulatory T cells in acute myeloid leukemia

Background and objectives: The microenvironment of acute myeloid leukemia (AML) is suppressive for immune cells. Regulatory T cells (Tregs) have been recognized to play a role in helping leukemic cells to evade immunesurveillance. The mesenchymal stem cells (MSCs) are essential contributors in immunomodulation of the microenvironment as they can promote differentiation of Tregs via the indoleamine 2,3-dioxygenase (IDO) pathway.The aim of the present work was to evaluate the expression of IDO in bone marrow derived MSCs and to study its correlation to percentage of Tregs.Methods: Thirty-seven adult bone marrow samples were cultured in appropriate culture medium to isolate MSCs. Successful harvest of MSCs was determined by plastic adherence, morphology, and positive expression of CD271 and CD105; negative expression of CD34 and CD45 using flowcytometry. MSCs were examined for IDO expression by immunocytochemistry using anti-IDO monoclonal antibody. CD4+ CD25+ cells (Tregs) were measured in bone marrow samples by flowcytometry.Results: MSCs were successfully isolated from 20 of the 37 bone marrow samples cultured. MSCs showed higher expression of IDO and Tregs percentage was higher in AML patients compared to control subjects (P = 0.002 and P < 0.001, respectively). A positive correlation was found between IDO expression and Tregs percentage (P value = 0.012, r = 0.5).Conclusion: In this study, we revealed an association between high IDO expression in MSCs and elevated levels of Tregs which could have an important role in the pathogenesis of AML, providing immunosuppressive microenvironment.

Prognostic value of indoleamine 2,3-dioxygenase activity and expression in nasopharyngeal carcinoma

Indoleamine 2,3-dioxygenase (IDO) is an enzyme with an immunosuppressive effect whose function is diverted by tumor cells to counteract immune cell functions, inducing immune escape of tumor cells. The aim of this study was to investigate the clinical significance of IDO in nasopharyngeal carcinoma (NPC). Compared to controls, NPC patients’ plasma IDO activity was significantly higher, especially among patients with metastatic cancer (p=0.005). The immunohistochemical analysis revealed that high IDO expression was observed in 74% of NPC tissues and the epithelial IDO expression was inversely correlated to T-cell infiltration. Kaplan–Meier survival analysis showed that whatever the localization, intratumoral or stromal, patients with a high IDO expression and low T-cell infiltration have significantly lower survival rates. Moreover, in multivariate analysis, intratumoral and stromal IDO expression were found to be independent prognostic factors for disease-free survival (p=0.016; HR: 3.52) and overall survival (p=0.015; HR: 4.76) respectively. Our findings provide evidence that IDO is involved in tumor immune evasion of NPC, suggesting that it could be a relevant therapeutic target for NPC.

Low expression of Bin1, along with high expression of IDO in tumor tissue and draining lymph nodes, are predictors of poor prognosis for esophageal squamous cell cancer patients.

Indoleamine 2,3-dioxygenase (IDO) has been reported to be involved in esophageal squamous cell cancer (ESCC) progression by promoting immune escape. Previous studies have revealed bridging integrator-1 (Bin1) can inhibit cancer cell growth by suppressing expression of IDO, thus we investigated the correlation between the expression of Bin1 and IDO and their prognostic significances for ESCC patients. Specimens were collected from 196 ESCC patients and detected with flow cytometry, reverse transcription-polymerase chain reaction and immunohistochemistry. We found that in tumor microenvironment (TME) and tumor draining lymph node (TDLN), the proportions of CD3(+) CD4(+) T cell, CD3(+) CD8(+) T cell and CD3(-) CD16(+) CD56(+) NK cell were lower while the proportions of CD3(-) CD19(+) B cell and CD4(+) CD25(+) Treg were higher in specimens with high IDO expression when compared to the specimens with low IDO expression (p < 0.01). In addition, IDO expression was negatively correlated with Bin1 expression at gene and protein level in TME and TDLN. Both the expression of Bin1 and IDO were associated with some clinicopathological parameters including differentiation grade, TNM stage, invasion range, lymph node metastasis (p < 0.05). Moreover, multivariate survival analysis suggested that, along with some other parameters, low expression of Bin1 and high expression of IDO might be independent prognostic factor for ESCC patients. Our results demonstrate that low expression of Bin1, along with high expression of IDO, are predictor for poor prognosis in ESCC and thereby could be used to establish new therapeutic strategies.