Indoleamine 2,3-dioxygenase Activity Research Articles

Tryptophan-Kynurenine Pathway Activation and Cognition in Virally Suppressed Women With HIV

Background: Immune and cognitive dysfunction persists even in virally suppressed women with HIV (VS-WWH). Since inflammation and HIV proteins induce the enzyme IDO (indoleamine 2, 3-dioxygenase), converting tryptophan (T) to kynurenine (K) while producing downstream neurotoxic metabolites, we investigated IDO activation (KT ratio) in relation to cognition in VS-WWH and demographically similar women without HIV (WWoH). Methods: 99 VS-WWH on stable antiretroviral therapy and 102 WWoH (median age 52 vs 54 years; 73% vs 74% Black respectively) from the New York and Chicago sites of the Women’s Interagency HIV Study (WIHS) completed a neuropsychological test battery assessing motor function, processing speed, attention/working memory, verbal fluency, verbal learning and memory, and executive function) and had plasma measured for TK metabolites via liquid chromatography-tandem mass spectrometry and monocyte derived (sCD14, sCD163, MCP-1/CCL-2) plus general inflammatory markers (TNF-RII, hsCRP, hsIL-6) via enzyme-linked immunosorbent assays between 2017-20. Results: VS-WWH had a higher KT ratio (P<0.01) and higher sCD14 levels (P<0.05) compared to WWoH. Higher sCD163 was associated with higher KT ratio (R=0.29, P <0.01), and worse fine motor function in VS-WWH; after adjusting for sCD163 and sCD14 in multivariable regressions, higher KT ratio remained significantly associated with impaired fine motor function in VS-WWH only (standardized β=-0.29, P<0.05). IDO activation was not associated with cognition in WWoH. Conclusions: IDO activation (K:T) was associated with worse fine motor control in VS-WWH independent of measured systemic inflammation. Further studies investigating biological mechanisms linking IDO activation to fine motor function among VS-WWH are warranted.

Taking advantage of the interaction between the sulfoxide and heme cofactor to develop indoleamine 2, 3-dioxygenase 1 inhibitors

Taking advantage of key interactions between sulfoxide and heme cofactor, we used the sulfoxide as the anchor functional group to develop two series of indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitors: 2-benzylsulfinylbenzoxazoles (series 1) and 2-phenylsulfinylbenzoxazoles (series 2). In vitro enzymatic screening shows that both series can inhibit the activity of IDO1 in low micromolar (series 1) or nanomolar (series 2) levels. They also show inhibitory selectivity between IDO1 and tryptophan 2, 3-dioxygenase 2. Interestingly, although series 1 is less potent IDO1 inhibitors of these two series, it exhibited stronger inhibitory activity toward kynurenine production in interferon-γ stimulated BxPC-3 cells. Enzyme kinetics and binding studies demonstrated that 2-sulfinylbenzoxazoles are non-competitive inhibitors of tryptophan, and they interact with the ferrous form of heme. These results demonstrated 2-sulfinylbenzoxazoles as type II IDO1 inhibitors. Furthermore, molecular docking studies supports the sulfoxide being of the key functional group that interacts with the heme cofactor. Compound 22 (series 1) can inhibit NO production in a concentration dependent manner in lipopolysaccharides (LPS) stimulated RAW264.7 cells, and can relieve pulmonary edema and lung injury in LPS induced mouse acute lung injury models.

Design of a targeted dual drug delivery system for boosting the efficacy of photoimmunotherapy against melanoma proliferation and metastasis

IntroductionThe combination of a photosensitizer and indoleamine-2,3 dioxygenase (IDO) inhibitor provides a promising photoimmunotherapy (PIT) strategy for melanoma treatment. A dual drug delivery system offers a potential approach for optimizing the inhibitory effects of PIT on melanoma proliferation and metastasis. ObjectiveTo develop a dual drug delivery system based on PIT and to study its efficacy in inhibiting melanoma proliferation and metastasis. MethodsWe constructed a multifunctional nano-porphyrin material (P18-APBA-HA) using the photosensitizer-purpurin 18 (P18), hyaluronic acid (HA), and 4-(aminomethyl) phenylboronic acid (APBA). The resulting P18-APBA-HA was inserted into a phospholipid membrane and the IDO inhibitor epacadostat (EPA) was loaded into the internal phase to prepare a dual drug delivery system (Lip\\EPA\\P18-APBA-HA). Moreover, we also investigated its physicochemical properties, targeting, anti-tumor immunity, and anti-tumor proliferation and metastasis effects. ResultsThe designed system utilized the pH sensitivity of borate ester to realize an enhanced-targeting strategy to facilitate the drug distribution in tumor lesions and efficient receptor-mediated cellular endocytosis. The intracellular release of EPA from Lip\\EPA\\P18-APBA-HA was triggered by thermal radiation, thereby inhibiting IDO activity in the tumor microenvironment, and promoting activation of the immune response. Intravenous administration of Lip\\EPA\\P18-APBA-HA effectively induced anti-tumor immunity by promoting dendritic cell maturation, cytotoxic T cell activation, and regulatory T cell suppression, and regulating cytokine secretion, to inhibit the proliferation of melanoma and lung metastasis. ConclusionThe proposed nano-drug delivery system holds promise as offers a promising strategy to enhance the inhibitory effects of the combination of EPA and P18 on melanoma proliferation and metastasis.

The plasma kynurenine-to-tryptophan ratio as a biomarker of tuberculosis disease in people living with HIV on antiretroviral therapy: an exploratory nested case–control study

BackgroundNon-sputum-based tests are needed to predict or diagnose tuberculosis (TB) disease in people living with HIV (PWH). The enzyme indoleamine 2, 3-dioxygenase-1 (IDO1) is expressed in tuberculoid granuloma and catabolizes tryptophan (Trp) to kynurenine (Kyn). IDO1 activity compromises innate and adaptive immune responses, promoting mycobacterial survival. The plasma Kyn-to-Trp (K/T) ratio is a potential TB diagnostic and/or predictive biomarker in PWH on long-term antiretroviral therapy (ART).MethodsWe compared plasma K/T ratios in samples from PWH, who were followed up prospectively and developed TB disease after ART initiation. Controls were matched for age and duration of ART. Kyn and Trp were measured at 3 timepoints; at TB diagnosis, 6 months before TB diagnosis and 6 months after TB diagnosis, using ultra performance liquid chromatography combined with mass spectrometry.ResultsThe K/T ratios were higher for patients with TB disease at time of diagnosis (median, 0.086; IQR, 0.069–0.123) compared to controls (0.055; IQR 0.045–0.064; p = 0.006), but not before or after TB diagnosis. K/T ratios significantly declined after successful TB treatment, but increased upon treatment failure. The K/T ratios showed a parabolic correlation with CD4 cell counts in participants with TB (p = 0.005), but there was no correlation in controls.ConclusionsThe plasma K/T ratio helped identify TB disease and may serve as an adjunctive biomarker for for monitoring TB treatment in PWH. Validation studies to ascertain these findings and evaluate the optimum cut-off for diagnosis of TB disease in PWH should be undertaken in well-designed prospective cohorts.Trial registrationClinicalTrials.gov Identifier: NCT00411983.

Improved automated one-pot two-step radiosynthesis of (S)-[18F]FETrp, a radiotracer for PET imaging of indoleamine 2,3-dioxygenase 1 (IDO1)

Background(S)-[18F]FETrp is a promising PET radiotracer for imaging IDO1 activity, one of the main enzymes involved in the tryptophan metabolism that plays a key role in several diseases including cancers. To date, the radiosynthesis of this tryptophan analogue remains highly challenging due to partial racemization occurring during the nucleophilic radiofluorination step. This work aims to develop a short, epimerization-free and efficient automated procedure of (S)-[18F]FETrp from a corresponding enantiopure tosylate precursor.ResultsEnantiomerically pure (S)- and (R)-FETrp references as well as tosylate precursors (S)- and (R)-3 were obtained from corresponding Na-Boc-(L and D)-tryptophan in 2 and 4 steps, respectively. Manual optimisation of the radiolabelling conditions resulted in > 90% radiochemical conversion with more than 99% enantiomeric purity. Based on these results, the (S)-[18F]FETrp radiosynthesis was fully automated on a SynChrom R&D EVOI module to produce the radiotracer in 55.2 ± 7.5% radiochemical yield, 99.9% radiochemical purity, 99.1 ± 0.5% enantiomeric excess, and molar activity of 53.2 ± 9.3 GBq/µmol (n = 3).ConclusionsTo avoid racemisation and complicated purification processes, currently encountered for the radiosynthesis of (S)-[18F]FETrp, we report herein significant improvements, including a versatile synthesis of enantiomerically pure tosylate precursor and reference compound and a convenient one-pot two-step automated procedure for the radiosynthesis of (S)-[18F]FETrp. This optimised and robust production method could facilitate further investigations of this relevant PET radiotracer for imaging IDO1 activity.

SP94 engineered erythrocyte membrane enhanced the targeted delivery of biomimetic nanosuspension with IDO immunotherapy and chemotherapy in liver cancer

The efficient eradication of tumor cells remains a critical challenge in the realm of liver cancer therapies. The combination of chemotherapy and immunotherapy holds more significant potential for improving treatment efficacy. However, the effectiveness of immunotherapy is mainly impeded by the high activity of indoleamine 2,3-dioxygenase (IDO), which creates an immunosuppressive tumor microenvironment via robust proliferation of immunosuppressive T regulatory cells (Tregs) and inhibition of cytotoxic T lymphocytes (CTLs). Herein, we developed SR-ATO-ASIV@NS, a liver cancer-targeting peptide (SP94) modified RBCM-coated biomimetic nanosuspension. This innovative formulation incorporates the chemotherapeutic agent arsenic trioxide (ATO) and the immunomodulator astragaloside IV (AS-IV) as IDO inhibitor for the combined chemoimmunotherapy of liver cancer. The SR-ATO-ASIV@NS increased the solubility of both ATO and AS-IV and displayed excellent stability and exhibited high drug-loading efficiency, rendering it suitable for efficient dual drug delivery. Furthermore, this biomimetic nanosuspension efficiently evaded immune response and showed specific uptake in liver cancer cells via SP94 receptor-mediated endocytosis. The remarkable pharmacokinetic profile, characterized by prolonged blood circulation, enhanced the in vivo anti-tumor efficacy in H22 tumor bearing mice through the synergistic action of the dual drugs. On one hand, the released ATO resulted in excessive reactive oxygen species (ROS) generation, which stimulated the induction of apoptosis pathways via Bax/Bcl-2 and caspase mechanism. While on the other hand, AS-IV effectively blocked the IDO activity and hinders the production of Tregs within the tumor microenvironment. Consequently, the reduced Tregs population fosters the proliferation of CTLs, alleviating ITM and intensifying the immunotherapeutic response for the efficient killing of cancer cells. Additionally, the successful inhibition of liver cancer metastasis to the lungs and robust increase in T memory cells further boosted the anti-tumor therapeutic efficacy of SR-ATO-ASIV@NS. In summary, SR-ATO-ASIV@NS represents a novel and scientifically sophisticated strategy in targeted biomimetic nanotherapeutics. This approach not only enhances site-specific drug delivery but also showcases promising potential for advancing the field of combined chemoimmunotherapy for liver cancer.

Abstract 3065: Targeting of metabolic reprogramming in lung cancer by utilizing patient-derived organoid tissue for precision medicine

Abstract In a preliminary pilot study, we reported elevated activity of indoleamine 2,3-dioxygenase 1 (IDO1) in serum from cisplatin-resistant (CR) lung cancer patients compared to cisplatin-sensitive (CS) patients. This heightened IDO1 activity was associated with increased tryptophan (TRP) catabolism, resulting in the upregulation of kynurenine (KYN) production. The detection of KYN can now be readily achieved through immunohistochemistry (IHC). We demonstrated that this upregulation contributed to increased Treg (regulatory T cell) and MDSC (myeloid-derived suppressor cell) populations resulting in an immunosuppressive tumor microenvironment. To investigate this effect, we used dual inhibition of IDO1/TDO2 (tryptophan2,3-dioxygenase 2) in an orthotopic mouse model of CR-Lewis lung carcinoma. This resulted in a significant reduction in tumor volume compared to LLC-CS (n=7, p<0.01), confirming the role of TRP catabolism in CR tumorigenesis. To determine the relevance of the data derived from this mouse model to clinical settings, we established 50 patient-derived organoid tissues (PDOT) from patients with NSCLC. PDOT is an experimental ex vivo tissue model developed to recapitulate the intricate features of lung architecture, including the lung acinus. Upon optimizing our collection and growth protocols, each PDOT successfully developed into a spherical body within 14 days. Furthermore, through bulk RNA-seq analysis, we showed that PDOT closely mirrors the expression of key molecular markers (PD-L1 and mutations), as observed in the original tumor tissues. PDOT from patients possessing high levels of PD-L1 and KYN were exquisitely sensitive to dual inhibition with 2-3-fold greater sensitivity compared to patients with undetectable KYN expression in growth inhibition assays (GI50=20±5.5μM vs. 65±7.5μM). Increased lipid peroxidation was detected via flow cytometry by accumulation of the C11-BODIPY reporter dye in the dual inhibition treatment group. Moreover, we integrated PDOT with a novel 3D microfluidic culture that can be supplied with patient-matched peripheral blood mononuclear cells (PBMC) to assess immune response. Using CyTOF, we showed that dual inhibitors with Atezolizumab (anti-PD-L1) enhanced immune effector (CD8+, NK) and suppressed immunosuppressive (Treg, MDSC) populations. We believe that our swift progress in PDOT development may bridge the divide between cancer biomarker expression and patient trials by timely complementing conventional drug studies based on cell lines and xenografts to facilitate the design of personalized therapies. As a result, the extensive reporting that we have contributed for KYN expression profiling in CR has the potential to serve as a valuable companion diagnostic tool in the future. This can assist in applying precision oncology by finding the most appropriate patients for immunotherapies. Citation Format: Chunjing Wu, Jonathan D. Nguyen, George Theodore, Estelamari Rodriguez, Sydney Spector, Emily Kim, Taranatee Khan, Pablo Puente, Yujie Wang, Dao M. Nguyen, Cheng-Bang Chen, Diane Lim, Lynn G. Feun, Niramol Savaraj, Medhi Wangpaichitr. Targeting of metabolic reprogramming in lung cancer by utilizing patient-derived organoid tissue for precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3065.

Marked IDO2 expression and activity related to autophagy and apoptosis in brain tissue of fatal tuberculous meningitis

In about 1% of tuberculosis (TB) patients, Mycobacterium tuberculosis (M. tuberculosis) can disseminate to the meninges, causing tuberculous meningitis (TBM) with mortality rate up to 60%.Chronic granulomatous inflammation (non-necrotizing and necrotizing) in the brain is the histological hallmark of TBM. The tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase 1 (IDO1) and the generated kynurenine metabolites exert major effector functions relevant to TB granuloma functioning. Here we have assessed immunohistochemically IDO1 expression and activity and its effector function and that of its isoform, IDO2, in post-mortem brain tissue of patients that demised with neurotuberculosis. We also related these findings to brain tissue of fatal/severe COVID-19. In this study, IDO1 and IDO2 were abundantly expressed and active in tuberculoid granulomas and were associated with the presence of M. tuberculosis as well as markers of autophagy and apoptosis. Like in fatal/severe COVID-19, IDO2 was also prominent in specific brain regions, such as the inferior olivary nucleus of medulla oblongata and cerebellum, but not associated with granulomas or with M. tuberculosis. Spatially associated apoptosis was observed in TBM, whereas in fatal COVID-19 autophagy dominated. Together, our findings highlight IDO2 as a potentially relevant effector enzyme in TBM, which may relate to the symptomology of TBM.

Pteridine and tryptophan pathways in children with type 1 diabetes: Isoxanthopterin as an indicator of endothelial dysfunction

AimType 1 diabetes (T1D) and its complications are known to be associated with oxidative stress. Pteridine derivatives and indoleamine 2,3-dioxygenase (IDO) activity can be used as biomarkers in the evaluation of oxidative stress. In this study, our aim is to compare the concentrations of serum and urinary pteridine derivatives, as well as serum IDO activity, in children and adolescents diagnosed with T1D and those in a healthy control group. MethodA cross-sectional study was performed and included 93 patients with T1D and 71 healthy children. Serum and urine biopterin, neopterin, monapterin, pterin, isoxanthopterin, and pterin-6-carboxylic acid (6PTC) and serum tryptophan and kynurenine levels were analyzed and compared with healthy controls. High-performance liquid chromatography was used for the analysis of pteridine derivatives, tryptophan, and kynurenine. Xanthine oxidase (XO) activity, a marker of oxidative stress, was defined by measurement of serum and urine isoxanthopterin. As an indicator of indolamine 2,3-dioxygenase (IDO) activity, the ratio of serum kynurenine/tryptophan was used. ResultsSerum isoxanthopterin and tryptophan concentrations were increased, and serum 6PTC concentration was decreased in children with T1D (p=0.01, p=0.021, p<0.001, respectively). In children with T1D, IDO activity was not different from healthy controls (p>0.05). Serum neopterin level and duration of diabetes were weakly correlated (p=0.045, r=0.209); urine neopterin/creatinine and isoxanthopterin/creatinine levels were weakly correlated with HbA1c levels (p=0.005, r=0.305; p=0.021, r=0.249, respectively). Urine pterin/creatinine level negatively correlated with body mass index-SDS. (p=0.015, r=-0.208). ConclusionWe found for the first time that isoxanthopterin levels increased and 6PTC levels decreased in children and adolescents with T1D. Elevated isoxanthopterin levels suggest that the XO activity is increased in TID. Increased XO activity may be an indicator of vascular complications reflecting T1D-related endothelial dysfunction.

Targeting Large-Conductance Calcium-Activated Potassium Channels to Ameliorate Lipopolysaccharide-Induced Depressive-Like Behavior in Mice.

Neuroinflammation plays crucial role in the development and progression of depression. Large conductance calcium- and voltage-dependent potassium (BK) channels mediate the activation of microglia. Herein, we investigated whether BK channels could serve as a target for the treatment of inflammation-associated depression. Lipopolysaccharide (LPS, 0.83mg/kg) was injected intraperitoneally (i.p.) to induce neuroinflammation and depressive-like behavior in 6-8week ICR mice. Adeno-associated virus (AAV) constructs (AAV9-Iba1p-BK shRNA-EGFP (BK shRNA-AAV) or AAV9-Iba1p-NC shRNA-EGFP (NC shRNA-AAV)) were unilaterally injected intracerebroventricularly to selectively knock down BK channels in microglia. The tail suspension test (TST) and forced-swim test (FST) were used to evaluate depressive-like behavior in mice 24h after LPS challenge. The morphology of microglia, expression of BK channels, levels of cytokines, and expression and activity of indoleamine 2,3-dioxygenase (IDO) were measured by immunohistochemistry, western blot, quantitative real time PCR, and enzyme-linked immunosorbent assay (ELISA), respectively. Either paxilline (i.p.), a specific BK channel blocker, or BK shRNA-AAV effectively inhibited the activation of microglia, reduced the production of IL-1β in the hippocampus and suppressed the expression and activity of IDO in the hippocampus and prefrontal cortex, resulting in the amelioration of depressive-like behavior in mice. These data suggest for the first time that BK channels are involved in LPS-induced depressive-like behaviors. Thus, microglia BK channels may be a potential drug target for the depression treatment.

Exploring the importance of kynurenine pathway (KP) approaches in colorectal cancer (CRC)

One of the main causes of cancer-related fatalities is colorectal cancer (CRC). The majority of patients frequently receive a late diagnosis of colorectal cancer (CRC) due to the absence of accurate prognostic and predictive biomarkers. Furthermore, greater metastasis and shorter survival rates were seen in colorectal cancer (CRC) patients. Recent advances in cancer treatment have been made possible by therapeutic immune system potentiation. The immune system and the kynurenine pathway (KP) are closely related. As a result of kynurenine's promotion of T Reg (regulatory) differentiation, more anti-inflammatory cytokines are produced and the cytotoxic activity of T cells is suppressed. In malignancies, the overactivation of the kynurenine pathway (KP) creates a micro environment where mutant cells can survive and invade neighboring tissues.The poor prognosis of several cancers, including gastrointestinal cancers, gynecological cancers, hematologic malignancies, breast cancer, lung cancer, glioma, melanoma, prostate cancer, and pancreatic cancer, is predicted by overactivation of the kynurenine pathway (KP), particularly the overactivation of indoleamine 2,3-dioxygenase (IDO). Additionally, kynurenine promotes cancer cell invasion, metastasis, and chemoresistance. The evolving understanding of the kynurenine pathway (KP) and its use in colorectal cancer (CRC) is covered in this review. An essential amino acid called tryptophan can be processed by several different pathways, with the kynurenine pathway (KP) being one of the more important ones. Kynurenine (KYN) is recognized as an oncometabolite in colon cancer, and colorectal cancer (CRC) that results from its subsequent metabolites. For several physiological activities, indoleamine 2,3-dioxygenase (IDO), a crucial enzyme that catalyzes kynurenine metabolism, is required. We talked about IDO's role in colorectal cancer (CRC) in this review. IDO knockdown decreased the expression of cancer stem cell markers as well as the ability of colorectal cancer (CRC) cells to migrate and invade. The application of an inhibitor to restrict the enzymatic activity of IDO also prevented the formation of spheres and hindered cell motility in colorectal cancer (CRC) cells. These findings demonstrate the clinical significance of IDO in the growth and tumorigenicity of colorectal cancer (CRC) tumors.

A lipid/PLGA nanocomplex to reshape tumor immune microenvironment for colon cancer therapy.

Immune checkpoint blockade therapy provides a new strategy for tumor treatment; however, the insufficient infiltration of cytotoxic T cells and immunosuppression in tumor microenvironment lead to unsatisfied effects. Herein, we reported a lipid/PLGA nanocomplex (RDCM) co-loaded with the photosensitizer Ce6 and the indoleamine 2,3-dioxygenase (IDO) inhibitor 1MT to improve immunotherapy of colon cancer. Arginine-glycine-aspartic acid (RGD) as the targeting moiety was conjugated on 1,2-distearoyl-snglycero-3-phosphoethanolamine lipid via polyethylene glycol (PEG), and programmed cell death-ligand 1 (PD-L1) peptide inhibitor DPPA (sequence: CPLGVRGK-GGG-d(NYSKPTDRQYHF)) was immobilized on the terminal group of PEG via matrix metalloproteinase 2 sensitive peptide linker. The Ce6 and 1MT were encapsulated in PLGA nanoparticles. The drug loaded nanoparticles were composited with RGD and DPPA modified lipid and lecithin to form lipid/PLGA nanocomplexes. When the nanocomplexes were delivered to tumor, DPPA was released by the cleavage of a matrix metalloproteinase 2-sensitive peptide linker for PD-L1 binding. RGD facilitated the cellular internalization of nanocomplexes via avβ3 integrin. Strong immunogenic cell death was induced by 1O2 generated from Ce6 irradiation under 660 nm laser. 1MT inhibited the activity of IDO and reduced the inhibition of cytotoxic T cells caused by kynurenine accumulation in the tumor microenvironment. The RDCM facilitated the maturation of dendritic cells, inhibited the activity of IDO, and markedly recruited the proportion of tumor-infiltrating cytotoxic T cells in CT26 tumor-bearing mice, triggering a robust immunological memory effect, thus effectively preventing tumor metastasis. The results indicated that the RDCM with dual IDO and PD-L1 inhibition effects is a promising platform for targeted photoimmunotherapy of colon cancer.

Low indoleamine 2, 3 dioxygenase (IDO) activity is associated with psycho-obstetric risk

ObjectivesPreeclampsia and depression in pregnancy are among the most prevalent obstetric disorders with no known cures. While depression and preeclampsia each increase risk for the other, shared mechansisms are unclear. One possibility is low levels of Indoleamine 2,3 dioxygenase (IDO), which links immune dysregulation and oxidative arterial damage resulting in poor vascular function in both preeclampsia and depression. We hypothesized low circulating IDO activity levels in pregnancy would correspond to poor vascular function and depression symptoms. Study designIn this nested case-control study, clinical, demographic, and biologic data from a cohort of pregnant women recruited to longitudinal studies measuring noninvasive vascular function and circulating factors were analyzed. Main outcome measureIDO activity across all three trimesters of pregnancy was measured using a colorimetric assay. Carotid-femoral pulse wave velocity (cfPWV), a measure of arterial stiffness, was also assessed throughout gestation by non-invasive applanation tonometry. Depression symptoms were assessed in pregnancy via the validated patient health questionnaire 9 (PHQ9). ResultsParticipants with low second and third trimester IDO activity had significantly decreased cfPWV. This association remained statistically significant when controlled for confounders such as BMI and chronic hypertension in the third but not second trimester. While PHQ9 scores were not associated with cfPWV differences, IDO activity was lower in moderate and severely depressed relative to non-depressed pregnant individuals. Conclusion: These results implicate IDO in arterial stiffness and depression symptoms, suggesting that decreased IDO may be a central target for improved psycho-obstetric health.

The Unique BCR Inhibiting Properties of BMS-986205 in Chronic Lymphocytic Cells

B cell receptor (BCR) signaling is recognised as a central pathway in the pathogenesis of chronic lymphocytic leukaemia (CLL), the most common leukemia in the western world. In CLL, the BCR pathway is activated by antigens in the tissue microenvironment to promote the maintenance and expansion of leukemic cells. The impressive inhibition of clonal expansion of CLL cells and the disease control achieved with tyrosine kinase inhibitors that block BCR signaling provided further evidence of the role of BCR in CLL. Indoleamine 2,3-dioxygenase 1 (IDO1) is the inducible and rate-limiting enzyme involved in the catabolism of tryptophan to kynurenine. It was discovered as a modulator of the innate immune response during infection. Subsequent discoveries have implicated IDO1 as a player in acquired immune tolerance. IDO1 activity has been identified in several types of cancer cells as well as in their tumor-surrounding microenvironment. We have previously investigated and characterized the impact of IDO1 expression in CLL. Our results show that CLL microenvironmental stimuli positively modulate IDO1 expression in leukemic cells and that increased IDO1 activity leads to sustained survival of malignant lymphocytes and impaired drug sensitivity through the autocrine/paracrine activation of the aryl hydrocarbon receptor by kynurenine (Atene CG et al. 2022). To assess the functional and clinical significance of IDO1 enzymatic activity in CLL, we used several inhibitors that are currently in late-stage clinical trials. Using BMS-986205 (BMS), an irreversible inhibitor of IDO1 with the best cell-based potency, in primary patient cells, we observed not only a reduction in kynurenine production due to enzymatic inhibition of IDO1, but also lower levels of IDO1 RNA and protein following BCR stimulation with α-IgM. As we have previously shown that BCR activation can induce IDO1 expression, we treated CLL cells with increasing doses of BMS for 3 hours and then added α-IgM to the culture. BMS is able to counteract the pro-survival effect of BCR triggering, leading to significant apoptosis of CLL cells, while the viability of CLL cells in the absence of external stimuli was not significantly modulated. Focusing on the complex signaling cascade activated by BCR engagement, we observed that BMS impaired the phosphorylation of upstream kinases such as SYK and BTK, but also CD79a, CD19 and BLNK, in addition to downstream effectors such as AKT. We therefore investigated which factors that negatively regulate the BCR pathway are modulated by BMS treatment. By analyzing both mRNA and protein levels, we measured a significant induction of the phosphatases PTPN6, PTPN22 and SHIP1. Since BMS also showed a downregulation of total SYK expression, we are analyzing the expression of the proto-oncogene CBL, an E3 ubiquitin ligase known to be involved in the negative regulation of SYK. Further studies should be undertaken to determine whether, in addition to its role as an IDO1 inhibitor, BMS may also have the ability to indirectly modulate and disrupt BCR signaling. Efforts are underway to identify the proteome-wide direct target of BMS in CLL cells. In conclusion, our limited and preliminary data suggest that BMS could be considered as a potential therapeutic strategy to target CLL cells with a double hit: by blocking the pro-survival effect of BCR signaling, one of the driving forces for CLL cell survival and proliferation, and by inhibiting IDO1/kynurenine action to restore sensitivity to key leukemia treatments.

Elevated indoleamine 2,3-dioxygenase activity is associated with endothelial dysfunction in people living with HIV and ROS production in human aortic endothelial cells in vitro.

The precise role of indoleamine 2,3-dioxygenase (IDO) in cardiovascular diseases (CVD) among people living with HIV (PLWH) is still under debate, despite recognized links. This study aimed to investigate the impact of elevated IDO activity on endothelial dysfunction in PLWH. A total of 38 PLWH, who had not previously received anti-retroviral therapy (ART), were enrolled in the study. These participants were monitored for 36 months following the initiation of ART. Measurements including plasma levels of IDO activity, markers of endothelial dysfunction, inflammatory factors, and lipids. In vitro, human aortic endothelial cells (HAEC) were exposed to interferon-γ, an IDO inhibitor, a kynurenine 3-hydroxylase (KMO) inhibitor, as well as different concentrations of kynurenine. Pre-ART, PLWH demonstrated notably elevated plasma concentrations of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1(sVCAM-1), and IDO activity in comparison to healthy controls. Post-ART, both IDO activity and sICAM-1 levels experienced a significant decrease, with IDO activity reaching levels comparable to those observed in healthy controls. Furthermore, a positive correlation was observed between IDO activity and sICAM-1 (p = 0.0002), as well as sVCAM-1 (p < 0.0001) before ART. In vitro, the augmentation of kynurenine concentration in the medium and the induction of IDO expression in HAEC resulted in increased production of reactive oxygen species (ROS), with minimal impact on endothelial dysfunction. From these findings, it can be concluded that long-term ART has the potential to restore the heightened IDO activity observed in PLWH. The overexpression of IDO primarily influences the expression of ROS in HAEC.

Immuno-modulation of tumor and tumor draining lymph nodes through enhanced immunogenic chemotherapy by nano-complexed hyaluronic acid/polyvinyl alcohol microneedle

Certain chemo-drugs could induce immunogenic cell death (ICD) activating T cell antitumor immunity while trigger indoleamine-2,3-dioxygenase (IDO) upregulation suppressing immune responses. Moreover, to achieve therapeutic efficacies on both primary tumors and tumor draining lymph nodes (TDLNs) in the meantime is still a big challenge. In this study, transfersomes functionalized with a tumor targeting, cell penetrating peptide tLyp1 (CGNKRTR) was developed to co-encapsulate doxorubicin (DOX, ICD inducer) and 1MT (IDO inhibitor). The functionalized transfersomes were complexed with microneedles (MNs) to realize co-delivery towards primary tumors and TDLNs via transdermal administration. The transfersomes were concentrated in the needles of MNs and released with needle dissolution after insertion into skin. After being internalized by cells, DOX induced tumor ICD effect to promote DCs maturation and dramatically activated cytotoxic T lymphocytes (CD8+ T), while 1MT inhibited IDO activity in DCs and reduced the immunosuppressive Tregs, thus mitigating tumor suppressive microenvironment. The nano-complexed microneedles exhibited 2.2-fold suppression in tumor growth compared with the I.V. group, which significantly enhanced anti-tumor effect.

Indoleamine 2,3-dioxygenase level and oxidative stress parameters in the serum of patients with chronic renal failure

Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-degrading enzyme belonging to the kynurenine pathway. IDO activity has been suggested as a biomarker for diagnosis of chronic kidney disease. The aim of the study was to estimate the level of IDO, urea, creatinine, uric acid, phosphate, calcium, albumin, MDA, GSH, and activity of peroxidase, catalase, arylesterase in the serum of chronic renal failure (CRF) patients treated with dialysis compared to the healthy control group. The results showed a significant increment in IDO level in patients compared with the control. Linear regression analysis using the Pearson correlation coefficient showed that increased IDO level correlates positively with urea, creatinine, uric acid, phosphate, MDA level and peroxidase activity whereas negatively with albumin, calcium, glutathione level, catalase activity and glomerular filtration rate. We concluded that IDO level might be a possible marker of oxidative stress and inflammation in patients with CRF. Keywords: 3-dioxygenase, biochemical parameters, correlation analysis, indoleamine 2, renal failure, serum

Evaluation of neopterin levels and kynurenine pathway in patients with acute coronary syndrome.

Coronary atherosclerosis is the leading cause of coronary artery disease. Several investigations have indicated that tear-sensitive plaques contain macrophages and T cells. Neopterin is an essential cellular immune response biomarker. The main goal of this study was to see if there were any changes in biomarkers like unconjugated pteridines, neopterin, and biopterin, as well as kynurenine pathway enzymes like indoleamine 2,3-dioxygenase (IDO), which catalyzes the rate-limiting step in tryptophan degradation, in patients with the acute coronary syndrome (ACS) caused by angiographic atherosclerosis. High-performance liquid chromatography was used to determine the amounts of neopterin, biopterin, and creatinine in urine samples, as well as tryptophan and kynurenine in serum samples. The enzyme-linked immunosorbent assay was used to assess the amounts of neopterin in serum samples. The measured parameters were evaluated between ACS patients and controls. The measured levels of neopterin, biopterin and the kynurenine to tryptophan ratio reflecting IDO activity, and the specifically known biomarkers such as cardiac troponin, creatine kinase, myoglobin, and natriuretic peptides are statistically higher in ACS patients compared to control subjects. On the other hand, the measured parameters are inadequate to classify the conventional kinds of ACS, ST-elevation- and non-ST-elevation- myocardial infarction. The study found that determining and using neopterin and IDO parameters as biomarkers in individuals with the ACS can support traditional biomarkers. However, it can be concluded that evaluating pteridine biomarkers solely have no privilege to clinical findings in ACS diagnosis and classification.

The role of cytokines and Indolamine-2.3 dioxygenase in experiencing a psycho-neurological symptom cluster in hematological cancer patients: IL-1alpha, IL-1beta, IL-4, IL-6, TNF-alpha, kynurenine, and tryptophan

ObjectiveThis study examined (a) whether there are a subgroup of cancer patients experiencing the selected psycho-neurological symptoms as a cluster (depression, cognitive impairment, fatigue, sleep disturbance, and pain); (b) whether demographic and clinical characteristics and pro-inflammatory cytokines (IL-1α, IL-1β, IL-4, IL-6, TNF-alpha) are associated with subgroup membership; and (c) whether the activity of indolamine-2.3 dioxygenase(IDO) is associated with pro-inflammatory cytokine activity and psycho-neurological symptom cluster experience. MethodsThis was a prospective cohort study where 149 hematologic patients were recruited from a university hospital and 65 healthy volunteers provided control data. Latent profile analyses were conducted to identify subgroups at two time points: the last day of chemotherapy and 1 week after chemotherapy completion. Influencing factors of subgroup membership were examined by logistic regression. ResultsA substantial number of patients (33%, 34% at each time point) experienced the selected psycho-neurological symptoms as a cluster. Older age and elevated IL-1α and IL-6 were associated with experiencing the psycho-neurological symptom cluster. IDO activity was higher in the patients experiencing psycho-neurological symptom cluster; and was positively associated with IL-6. Symptom severity, IL-1α, IL-6, and IDO activity were all significantly higher in cancer patients than in the healthy controls. The findings were preserved across time points. ConclusionsThe activation of pro-inflammatory cytokines and their cross-talk with IDO may be a common biological mechanism, underlying a psycho-neurological symptom cluster experience. The novel approaches for symptom assessment and management can be developed by assessing multiple psycho-neurological symptoms as a cluster and by targeting their common biological pathway.

Lipopolysaccharide-Induced Delirium-like Behaviour in a Rat Model of Chronic Cerebral Hypoperfusion Is Associated with Increased Indoleamine 2,3-Dioxygenase Expression and Endotoxin Tolerance.

Indoleamine 2,3-dioxygenase (IDO) and the tryptophan-kynurenine pathway (TRP-KP) are upregulated in ageing and could be implicated in the pathogenesis of delirium. This study evaluated the role of IDO/KP in lipopolysaccharide (LPS)-induced delirium in an animal model of chronic cerebral hypoperfusion (CCH), a proposed model for delirium. CCH was induced by a permanent bilateral common carotid artery ligation (BCCAL) in Sprague Dawley rats to trigger chronic neuroinflammation-induced neurodegeneration. Eight weeks after permanent BCCAL, the rats were treated with a single systemic LPS. The rats were divided into three groups: (1) post-BCCAL rats treated with intraperitoneal (i.p.) saline, (2) post-BCCAL rats treated with i.p. LPS 100 μg/kg, and (3) sham-operated rats treated with i.p. LPS 100 μg/kg. Each group consisted of 10 male rats. To elucidate the LPS-induced delirium-like behaviour, natural and learned behaviour changes were assessed by a buried food test (BFT), open field test (OFT), and Y-maze test at 0, 24-, 48-, and 72 h after LPS treatment. Serum was collected after each session of behavioural assessment. The rats were euthanised after the last serum collection, and the hippocampi and cerebral cortex were collected. The TRP-KP neuroactive metabolites were measured in both serum and brain tissues using ELISA. Our data show that LPS treatment in CCH rats was associated with acute, transient, and fluctuated deficits in natural and learned behaviour, consistent with features of delirium. These behaviour deficits were mild compared to the sham-operated rats, which exhibited robust behaviour impairments. Additionally, heightened hippocampal IDO expression in the LPS-treated CCH rats was associated with reduced serum KP activity together with a decrease in the hippocampal quinolinic acid (QA) expression compared to the sham-operated rats, suggested for the presence of endotoxin tolerance through the immunomodulatory activity of IDO in the brain. These data provide new insight into the underlying mechanisms of delirium, and future studies should further explore the role of IDO modulation and its therapeutic potential in delirium.