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The recent outbreak of monkeypox virus (MPXV) has caused global concern. How the virus evades the interferon (IFN) response is still poorly understood. We analyzed type I/II IFN (IFN-I/II) expression in clinical samples from MPXV-infected patients and measured IFN-I kinetics in MPXV-infected cells. We also evaluated the anti-MPXV activity of IFN-I/II in A549, HeLa and Vero-E6 cell lines. IFN-I/II mRNA expression was detected in skin lesions, anal swabs, nasopharyngeal samples and peripheral blood mononuclear cells (PBMC), with the highest levels in skin lesions (p < 0.05). High MPXV DNA levels in clinical samples were associated with increased IFN-I levels. In vitro, MPXV infection induced a peak of IFN-I between 48 and 72 h post-infection (p < 0.01). Pre-treatment of the A549, HeLa and Vero-E6 cells with high concentrations (≥ 100,000 International Unit, IU/ml) of IFN-α and IFN-ω did not inhibit or had little effect on MPXV replication, while IFN-β moderately reduced MPXV replication by 2.7–1.5 log10 at 100,000 IU/ml. In clinical samples there was a trend for elevated levels of IFN-γ in association with lower MPXV load and in vitro IFN-γ (3,600 IU/ml) strongly reduced viral titers by 3.4–1.6 log10. There were no significant differences in expression of select IFN-stimulated genes (ISGs) in MPXV infection in vitro. This study shows that MPXV delays IFN-I induction and inhibits expression of selected ISGs in vitro and is associated with an IFN-I resistance phenotype in vivo. However, MPXV is less resistant to IFN-γ in vivo and is sensitive to IFN-γ treatment in vitro, suggesting a potential therapeutic role for IFN-γ. [ABSTRACT FROM AUTHOR]

Aim: Postoperative cognitive dysfunction (POCD) is a common postoperative complication, especially in elderly patients. It extends hospital stay, increases the mortality rate and are heavy burdens to the family and society. Accumulating research has indicated that overactivation of pyrin domain-containing protein 3 (NLRP3) inflammasomes is related to POCD andplays a critical role in activating pro-inflammatory cytokines. According to existing studies, indoleamine 2,3-dioxygenase (IDO) is potently up-regulated by inflammatory factors, tryptophan in brain is mainly catalyzed by IDO to kynurenine (KYN), KYN metabolism may contribute to the development of depressive disorder and memory deficits. Hence, this study elucidated whether IDO-Kynurenine pathway mediates NLRP3 inflammasome activation-induced postoperative cognitive impairment in aged mice. Material and Methods: POCD model was established in aged C57BL/6J mice by exploratory laparotomy under isoflurane anesthesia. Learning and memory were determined using Morris water maze. Results: The data showed that IDO and kynurenine aminotransferase-II (KAT-II) mRNA in hippocampus was up-regulated, and NLRP3, caspase recruitment domain (ASC), interleukin-1b (IL-1b) and IDO overexpressed, KYN levels increased after anesthesia and surgery. NLRP3 inflammasome inhibitor (MCC950) reversed NLRP3, ASC, IL-1b and IDO overexpression, and the elevation of KYN levels. To clarify the role of IDO-Kynurenine pathway in postoperative cognitive impairment, IDO inhibitor (1-methyl-Ltryptophan 1-MT) reduced the elevation of KYN and kynurenic acid (KYNA) levels, reduction of tryptophan (TRP), as well as improved learning and memory abilities. Finally, KAT-II inhibitor (PF-04859989) reduced brain KYNA levels and restored the cognitive impairment. Conclusion: These results reveal that IDO-Kynurenine pathway mediates NLRP3 inflammasome activation-induced postoperative cognitive impairment. [ABSTRACT FROM AUTHOR]

Background: Oral lichen planus (OLP) and oral lichenoid lesions (OLL) are inflammatory T‐cell mediated disorders of the oral mucosa (OM). Both are associated with an increased risk of oral squamous cell carcinoma, with OLL possibly having a higher rate of malignant transformation than OLP. Programmed death ligand 1 (PD‐L1) and indoleamine 2,3‐dioxygenase (IDO) are immunosuppressive molecules possessing inhibitory effect on T‐cells and have been implicated in carcinogenesis. The aim of this study was to examine the expression of PD‐L1 and IDO in OLP and OLL. Methods: Sixty‐eight formalin‐fixed, paraffin‐embedded tissue samples diagnosed as OLP, compatible with OLP, or OLL were divided into OLP (n = 39) or OLL (n = 29) groups based on both clinical and histopathological diagnostic criteria. Samples of healthy OM (n = 9) served as controls. Samples were immunohistochemically stained for PD‐L1 and IDO, and staining distribution and intensity were evaluated. Results: Immunohistochemical expression of PD‐L1 was increased in the basal and intermediate layers of epithelium in OLP and in lamina propria in both OLP and OLL compared to controls. OLP and OLL showed increased expression of IDO in epithelium and lamina propria compared to controls. PD‐L1 staining intensity in the basal epithelial layer, and IDO staining intensity in lamina propria were increased in OLP compared to OLL. Conclusion: The results indicate that the expression of PD‐L1 and IDO increases in OLP and OLL, suggesting that these molecules may play a role in the pathogenesis of both disorders. [ABSTRACT FROM AUTHOR]

Introduction: The lens's metabolic demands are met through a continuous circulation of aqueous humor, encompassing a spectrum of components such as organic and inorganic ions, carbohydrates, glutathione, urea, amino acids, proteins, oxygen, carbon dioxide, and water. Metabolomics is a pivotal tool, offering an initial insight into the complexities of integrated metabolism. In this investigative study, we systematically scrutinize the composition of intraocular fluid in individuals afflicted with cataracts. Methods: The investigation involved a comprehensive analysis of aqueous humor samples from a cohort comprising 192 patients. These individuals were stratified by utilizing the SPONCS classification system, delineating distinct groups characterized by the hardness of cataracts. The analytical approach employed targeted quantitative metabolite analysis using HILIC-based liquid chromatography coupled with high-resolution mass spectrometric detection. The metabolomics data analysis was performed with MetaboAnalyst 5.0. Results: The results of the enrichment analysis have facilitated the inference that the discerned disparities among groups arise from disruptions in taurine and hypotaurine metabolism, variations in tryptophan metabolism, and modifications in mitochondrial beta-oxidation of short-chain saturated fatty acids and pyrimidine metabolism. Conclusion: A decline in taurine concentration precipitates diminished glutathione activity, prompting an elevated requirement for NAD+ and instigating tryptophan metabolism along the kynurenine pathway. Activation of this pathway is additionally prompted by interferon-gamma and UV radiation, leading to the induction of IDO. Concurrently, heightened mitochondrial beta-oxidation signifies a distinctive scenario in translocating fatty acids into the mitochondria, enhancing energy production. [ABSTRACT FROM AUTHOR]

Background: High mobility group box 1 (HMGB1) and indoleamino-2, 3-dioxygenase (IDO) participate in the occurrence and development of esophageal squamous cell carcinoma (ESCC), regulate the tumor immune microenvironment, and are closely related to tumor growth and metastasis. However, the regulatory mechanism of serum HMGB1 and IDO has not been clarified and needs further exploration. Methods: Blood samples of 55 ESCC patients initially hospitalized in the Fourth Hospital of Hebei Medical University from August 2021 to January 2022 were selected as the ESCC group, and relevant clinical data were collected, and blood samples from 40 healthy people during the same period were selected as the control group. Serum HMGB1 and IDO levels were determined by ELISA, and lymphocyte subsets in peripheral blood of all subjects were detected by flow cytometry. The correlation between the expression levels of HMGB1 and IDO in ESCC cells was detected by Western blot. Results: Serum HMGB1 and IDO levels were significantly increased in ESCC patients, and with the progression of ESCC patients, serum HMGB1 and IDO levels were also gradually increased; serum HMGB1 was significantly correlated with IDO; serum HMGB1 and IDO combined with CEA and SCC-Ag were of high value in predicting the clinical progression of ESCC patients; the absolute counts of CD4+CD28+T cells and CD8+CD28+T cells in high HMGB1 group were significantly lower than those in low HMGB1 group, while the percentage of CD4+PD-1+T cells was significantly higher than that in low HMGB1 group; the percentage and absolute counts of CD4+CD28+T cells and the absolute counts of CD8+CD28+T cells in high IDO group were significantly lower than those in the low IDO group, while the percentage of CD8+PD-1+T cells was significantly higher than that in the low IDO group; increased serum HMGB1 and IDO expression levels were closely related to poor prognosis in ESCC patients; and HMGB1 may promote IDO expression by activating NF-kB signaling pathway. Conclusion: Serum HMGB1 and IDO have a synergistic effect, they inhibit immune function and promote tumor progression in ESCC patients, and also lead to poor prognosis. [ABSTRACT FROM AUTHOR]

Background: Immune and cognitive dysfunction persists even in virally suppressed women with HIV (VS-WWH). Since inflammation and HIV proteins induce the enzyme indoleamine 2,3-dioxygenase (IDO), 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: Ninety-nine 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 tryptophan-kynurenine metabolites through liquid chromatography-tandem mass spectrometry and monocyte-derived [soluble cluster of differentiation-14 (sCD14), soluble cluster of differentiation-163 (sCD163), monocyte chemoattractant protein-1 (MCP-1)] plus general inflammatory markers [tumor necrosis factor alpha-2 receptor (TNF-R2), high-sensitivity C-reactive protein, high-sensitivity interleukin-6] through enzyme-linked immunosorbent assays between 2017 and 2020. Results: VS-WWH had a higher KT ratio (P, 0.01) and higher sCD14 levels (P, 0.05) compared with 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 VSWWH only (standardized b = 20.29, 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. [ABSTRACT FROM AUTHOR]

• Women with moderate-severe depressive symptoms in late pregnancy have lower placental QPRT and ACMSD expression. • Low expression of placental IDO and QPRT associates with increased IL-6 levels and QUIN/KYNA ratio in maternal plasma. • Interactions between placental enzyme expression and peripheral cytokine and metabolite patterns differ in depressed women. Perinatal depression (including antenatal-, postnatal-, and depression that spans both timepoints) is a prevalent disorder with high morbidity that affects both mother and child. Even though the full biological blueprints of perinatal depression remain incomplete, multiple studies indicate that, at least for antenatal depression, the disorder has an inflammatory component likely linked to a dysregulation of the enzymatic kynurenine pathway. The production of neuroactive metabolites in this pathway, including quinolinic acid (QUIN), is upregulated in the placenta due to the multiple immunological roles of the metabolites during pregnancy. Since neuroactive metabolites produced by the pathway also may affect mood by directly affecting glutamate neurotransmission, we sought to investigate whether the placental expression of kynurenine pathway enzymes controlling QUIN production was associated with both peripheral inflammation and depressive symptoms during pregnancy. 68 placentas obtained at birth were analyzed using qPCR to determine the expression of kynurenine pathway enzymes. Cytokines and metabolites were quantified in plasma using high-sensitivity electroluminescence and ultra-performance liquid chromatography, respectively. Maternal depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale (EPDS) throughout pregnancy and the post-partum. Associations between these factors were assessed using robust linear regression with ranked enzymes. Low placental quinolinate phosphoribosyl transferase (QPRT), the enzyme responsible for degrading QUIN, was associated with higher IL-6 and higher QUIN/kynurenic acid ratios at the 3rd trimester. Moreover, women with severe depressive symptoms in the 3rd trimester had significantly lower placental expression of both QPRT and 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase (ACMSD); impaired activity of these two enzymes leads to QUIN accumulation. Overall, our data support that a compromised placental environment, featuring low expression of critical kynurenine pathway enzymes is associated with increased levels of plasma cytokines and the dysregulated kynurenine metabolite pattern observed in depressed women during pregnancy. [ABSTRACT FROM AUTHOR]

The application of intracerebroventricular injection of streptozotocin (ICV-STZ) is considered a useful animal model to mimic the onset and progression of sporadic Alzheimer's disease (sAD). In rodents, on day 7 of the experiment, the animals exhibit depression-like behaviors. Indoleamine 2,3-dioxygenase (IDO), a rate-limiting enzyme catalyzing the conversion of tryptophan (Trp) to kynurenine (Kyn), is closely related to depression and AD. The present study aimed to investigate the pathophysiological mechanisms of preliminary depression-like behaviors in ICV-STZ rats in two distinct cerebral regions of the medial prefrontal cortex, the prelimbic cortex (PrL) and infralimbic cortex (IL), both presumably involved in AD progression in this model, with a focus on IDO-related Kyn pathways. The results showed an increased Kyn/Trp ratio in both the PrL and IL of ICV-STZ rats, but, intriguingly, abnormalities in downstream metabolic pathways were different, being associated with distinct biological effects. In the PrL, the neuroprotective branch of the Kyn pathway was attenuated, as evidenced by a decrease in the kynurenic acid (KA) level and Kyn aminotransferase II (KAT II) expression, accompanied by astrocyte alterations, such as the decrease in glial fibrillary acidic protein (GFAP)-positive cells and increase in morphological damage. In the IL, the neurotoxicogenic branch of the Kyn pathway was enhanced, as evidenced by an increase in the 3-hydroxy-kynurenine (3-HK) level and kynurenine 3-monooxygenase (KMO) expression paralleled by the overactivation of microglia, reflected by an increase in ionized calcium-binding adaptor molecule 1 (Iba1)-positive cells and cytokines with morphological alterations. Synaptic plasticity was attenuated in both subregions. Additionally, microinjection of the selective IDO inhibitor 1-Methyl-DL-tryptophan (1-MT) in the PrL or IL alleviated depression-like behaviors by reversing these different abnormalities in the PrL and IL. These results suggest that the antidepressant-like effects linked to Trp metabolism changes induced by 1-MT in the PrL and IL occur through different pathways, specifically by enhancing the neuroprotective branch in the PrL and attenuating the neurotoxicogenic branch in the IL, involving distinct glial cells. [ABSTRACT FROM AUTHOR]

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Abstract Glioblastoma (GBM) continues to exhibit a discouraging survival rate despite extensive research into new treatments. One factor contributing to its poor prognosis is the tumor's immunosuppressive microenvironment, in which the kynurenine pathway (KP) plays a significant role. This study aimed to explore how KP impacts the survival of newly diagnosed GBM patients. We examined tissue samples from 108 GBM patients to assess the expression levels of key KP markers—tryptophan 2,3-dioxygenase (TDO2), indoleamine 2,3-dioxygenase (IDO1/2), and the aryl hydrocarbon receptor (AhR). Using immunohistochemistry and QuPath software, three tumor cores were analyzed per patient to evaluate KP marker expression. Kaplan–Meier survival analysis and stepwise multivariate Cox regression were used to determine the effect of these markers on patient survival. Results showed that patients with high expression of TDO2, IDO1/2, and AhR had significantly shorter survival times. This finding held true even when controlling for other known prognostic variables, with a hazard ratio of 3.393 for IDO1, 2.775 for IDO2, 1.891 for TDO2, and 1.902 for AhR. We suggest that KP markers could serve as useful tools for patient stratification, potentially guiding future immunomodulating trials and personalized treatment approaches for GBM patients.

Introduction: Immunomodulation is the predominant mechanism via which Mesenchymal stromal cells (MSCs) mediate their therapeutic benefits. However, inconsistent success in numerous clinical trials warrants a better understating of the molecular mechanisms regulating their immunomodulatory properties. CD73, an ecto-5′-nucleotidase is abundantly expressed by MSCs, however its precise role in regulating their immunomodulatory properties is still elusive. The present study explored the role of CD73 in Interferon-gamma (IFNγ) sensing and in turn their ability to suppress “inflammatory” M1 macrophages. Materials and methods: CD73 knockdown MSCs (CD73-KDN) were initially assessed for expression of immunoregulatory molecules and IFNγ sensing ability by analysing expression of IFNγ signalling downstream targets such as pSTAT-1, Interferon-Stimulated Genes (ISG) and Indoleamine 2,3-dioxygnease (IDO), a prototypic IFNγ-induced immunomodulator. Next CD73-KDN MSCs were co-cultured with inflammatory M1 macrophages and evaluated for their ability to suppress them. To delineate the contributory role of CD73 and IFNγ signalling downstream target IDO, they were overexpressed independently in CD73-KDN MSCs and re-evaluated for their ability to suppress M1 macrophages. Results: CD73-KDN MSCs exhibited reduced expression of immunoregulatory molecules and were refractory to IFNγ signalling as indicated by attenuated expression of pSTAT-1, Interferon-Stimulated Genes (ISG) and Indoleamine 2,3-dioxygnease (IDO) upon IFNγ exposure. Since sensing of inflammation is critical for MSC mediated immunomodulation, CD73-KDN MSCs were functionally evaluated for their ability to immune-modulate “inflammatory” M1 macrophages wherein they failed to suppress M1 macrophages. Interestingly, ectopic expression of either CD73 or IFNγ signalling target IDO1 in CD73-KDN MSCs restored their ability to suppress M1 macrophages, establishing the importance of CD73-IFNγ signalling axis in MSC-mediated inflammatory macrophage suppression. Conclusion: The present study uncovers the unexplored role of CD73-IFNγ axis in MSC-mediated M1 macrophage suppression. MSC-educated macrophages are the actual immune-modulators at MSC transplant sites, thus CD73 can serve as a key immune-potency marker for benchmarking therapeutically relevant MSCs.

Abstract Background Non-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). Methods We 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. Results The 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. Conclusions The 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 registration ClinicalTrials.gov Identifier: NCT00411983.

Indoleamine 2,3-dioxygenase 2 (IDO2) is a tryptophan-catabolizing enzyme and a homolog of IDO1 with a distinct expression pattern compared with IDO1. In dendritic cells (DCs), IDO activity and the resulting changes in tryptophan level regulate T-cell differentiation and promote immune tolerance. Recent studies indicate that IDO2 exerts an additional, non-enzymatic function and pro-inflammatory activity, which may play an important role in diseases such as autoimmunity and cancer. Here, we investigated the impact of aryl hydrocarbon receptor (AhR) activation by endogenous compounds and environmental pollutants on the expression of IDO2. Treatment with AhR ligands induced IDO2 in MCF-7 wildtype cells but not in CRISPR-cas9 AhR-knockout MCF-7 cells. Promoter analysis with IDO2 reporter constructs revealed that the AhR-dependent induction of IDO2 involves a short-tandem repeat containing four core sequences of a xenobiotic response element (XRE) upstream of the start site of the human ido2 gene. The analysis of breast cancer datasets revealed that IDO2 expression increased in breast cancer compared with normal samples. Our findings suggest that the AhR-mediated expression of IDO2 in breast cancer could contribute to a pro-tumorigenic microenvironment in breast cancer.

Background: Non-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). Methods: We 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. Results: The 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. Conclusions: The 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 registration: ClinicalTrials.gov Identifier: NCT00411983. [ABSTRACT FROM AUTHOR]

Background and aim: Type 2 diabetes mellitus (T2DM) and depression are often linked. Several studies have reported the role of molecular markers either in diabetes or depression. The present study aimed at molecular level profiling of Indoleamine-2,3-dioxygenase (IDO), brain-derived neurotrophic factor (BDNF) and cellular senescence in patients with type 2 diabetes with and without depression compared to individuals with healthy controls. Methods: A total of 120 individuals diagnosed with T2DM were enlisted for the study, with a subset of participants with and without exhibiting depression. The gene expression analysis was done using quantitative real-time PCR. Results: Indoleamine 2,3 dioxygenase (p < 0.001) and senescence genes (p < 0.001) were significantly upregulated, while brain derived neurotrophic factor (p < 0.01) was significantly downregulated in T2DM patients comorbid with and without depression when compared to healthy controls. Conclusion: Indoleamine 2,3 dioxygenase, Brain derived neurotrophic factor and cellular senescence may play a role in the progression of the disease. The aforementioned discoveries offer significant contributions to our understanding of the molecular mechanisms that underlie T2DM with depression, potentially aiding in the advancement of prediction and diagnostic methods for this particular ailment. [ABSTRACT FROM AUTHOR]

Introduction: Chagas disease causes a cardiac illness characterized by immunoinflammatory reactions leading to myocardial fibrosis and remodeling. The development of Chronic Chagas Cardiomyopathy (CCC) in some patients while others remain asymptomatic is not fully understood, but dysregulated inflammatory responses are implicated. The Aryl hydrocarbon receptor (AhR) plays a crucial role in regulating inflammation. Certain tryptophan (Trp) metabolites have been identified as AhR ligands with regulatory functions. Methods, results, and discussion: We investigated AhR expression, agonist response, ligand production, and AhR-dependent responses, such as IDO activation and regulatory T (Treg) cells induction, in two T. cruzi-infected mouse strains (B6 and Balb/c) showing different polymorphisms in AhR. Furthermore, we assessed the metabolic profile of Trp catabolites and AhR agonistic activity levels in plasma samples from patients with chronic Chagas disease (CCD) and healthy donors (HD) using a luciferase reporter assay and liquid chromatography-mass spectrophotometry (LC-MS) analysis. T. cruziinfected B6 mice showed impaired AhR-dependent responses compared to Balb/c mice, including reduced IDO activity, kynurenine levels, Treg cell induction, CYP1A1 up-regulation, and AhR expression following agonist activation. Additionally, B6 mice exhibited no detectable AhR agonist activity in plasma and displayed lower CYP1A1 up-regulation and AhR expression upon agonist activation. Similarly, CCC patients had decreased AhR agonistic activity in plasma compared to HD patients and exhibited dysregulation in Trp metabolic pathways, resulting in altered plasma metabolite profiles. Notably, patients with severe CCC specifically showed increased N-acetylserotonin levels in their plasma. The methods and findings presented here contribute to a better understanding of CCC development mechanisms and may identify potential specific biomarkers for T. cruzi infection and the severity of associated heart disease. These insights could be valuable in designing new therapeutic strategies. Ultimately, this research aims to establish the AhR agonistic activity and Trp metabolic profile in plasma as an innovative, non-invasive predictor of prognosis for chronic Chagas disease. [ABSTRACT FROM AUTHOR]

IntroductionChagas disease causes a cardiac illness characterized by immunoinflammatory reactions leading to myocardial fibrosis and remodeling. The development of Chronic Chagas Cardiomyopathy (CCC) in some patients while others remain asymptomatic is not fully understood, but dysregulated inflammatory responses are implicated. The Aryl hydrocarbon receptor (AhR) plays a crucial role in regulating inflammation. Certain tryptophan (Trp) metabolites have been identified as AhR ligands with regulatory functions.Methods, results, and discussionWe investigated AhR expression, agonist response, ligand production, and AhR-dependent responses, such as IDO activation and regulatory T (Treg) cells induction, in two T. cruzi-infected mouse strains (B6 and Balb/c) showing different polymorphisms in AhR. Furthermore, we assessed the metabolic profile of Trp catabolites and AhR agonistic activity levels in plasma samples from patients with chronic Chagas disease (CCD) and healthy donors (HD) using a luciferase reporter assay and liquid chromatography-mass spectrophotometry (LC-MS) analysis. T. cruzi-infected B6 mice showed impaired AhR-dependent responses compared to Balb/c mice, including reduced IDO activity, kynurenine levels, Treg cell induction, CYP1A1 up-regulation, and AhR expression following agonist activation. Additionally, B6 mice exhibited no detectable AhR agonist activity in plasma and displayed lower CYP1A1 up-regulation and AhR expression upon agonist activation. Similarly, CCC patients had decreased AhR agonistic activity in plasma compared to HD patients and exhibited dysregulation in Trp metabolic pathways, resulting in altered plasma metabolite profiles. Notably, patients with severe CCC specifically showed increased N-acetylserotonin levels in their plasma. The methods and findings presented here contribute to a better understanding of CCC development mechanisms and may identify potential specific biomarkers for T. cruzi infection and the severity of associated heart disease. These insights could be valuable in designing new therapeutic strategies. Ultimately, this research aims to establish the AhR agonistic activity and Trp metabolic profile in plasma as an innovative, non-invasive predictor of prognosis for chronic Chagas disease.

Nasopharyngeal carcinoma‐derived small extracellular vesicles (NPCSEVs) have an immunosuppressive impact on the tumour microenvironment. In this study, we investigated their influence on the generation of tolerogenic dendritic cells and the potential involvement of the galectin‐9 (Gal9) they carry in this process. We analysed the phenotype and immunosuppressive properties of NPCSEVs and explored the ability of DCs exposed to NPCSEVs (NPCSEV‐DCs) to regulate T cell proliferation. To assess their impact at the pathophysiological level, we performed real‐time fluorescent chemoattraction assays. Finally, we analysed phenotype and immunosuppressive functions of NPCSEV‐DCs using a proprietary anti‐Gal9 neutralising antibody to assess the role of Gal9 in this effect. We described that NPCSEV‐DCs were able to inhibit T cell proliferation despite their mature phenotype. These mature regulatory DCs (mregDCs) have a specific oxidative metabolism and secrete high levels of IL‐4. Chemoattraction assays revealed that NPCSEVs could preferentially recruit NPCSEV‐DCs. Finally, and very interestingly, the reduction of the immunosuppressive function of NPCSEV‐DCs using an anti‐Gal9 antibody clearly suggested an important role for vesicular Gal9 in the induction of mregDCs. These results revealed for the first time that NPCSEVs promote the emergence of mregDCs using a galectin‐9 dependent mechanism and open new perspectives for antitumour immunotherapy targeting NPCSEVs. [ABSTRACT FROM AUTHOR]

The effect of recombinant human chorionic gonadotropin (hCG) at pregnancy-appropriate concentrations (10 and 100 IU/mL) on differentiation and functional activity of myeloid-derived suppressor cells (MDSCs) was studied. The object of the study was isolated CD11b+ cells that were converted to the MDSC phenotype by two-step activation with GM-CSF cytokines, IL1β and lipopolysaccharide (LPS). After a week of cultivation, the total MDSC level was determined considering the subpopulations M-MDSC and PMN-MDSC, the expression of arginase-1 (Arg1) and indoleamn-2,3-dioxydiogenase (IDO) in these cells, as well as the cytokine profile in cell culture supernatant. It was shown that hCG increased the total number of MDSCs, and its lower concentration (10 IU/mL) contributed to the differentiation of the M-MDSC subpopulation. hCG did not affect the expression of IDO expression in MDSCs, but there was a tendency to increase IDO expression under the influence of hCG at a concentration of 10 IU/mL. CD11b+ cells converted to the MDSC phenotype had a low Arg 1 content, making it impossible to evaluate the effect of the hormone on the expression of this enzyme. Evaluation of the cytokine profile by multiplex analysis showed that hCG did not modulate cytokine production in the culture of CD11b+ cells converted the MDSC phenotype. This is the first time that hCG has been shown to induce differentiation of MDSCs. [ABSTRACT FROM AUTHOR]

Objective: Ferulic acid (FA) is a common food ingredient that is abundantly present in various routinely consumed food and beverages. Like many cinnamic acid derivatives, FA produces wide-ranging effects in a dose-dependent manner and various studies link FA consumption with reduced risk of depressive disorders. The aim of this study was to exploit the neuroprotective mechanisms of FA including indoleamine 2,3-dioxygenase (IDO), brain-derived neurotrophic factor (BDNF), and other pro-inflammatory cytokines by employing lipopolysaccharide (LPS)-induced depressive-like behaviour model. Methods: C57BL/6J male mice were divided into 4 groups consisting of saline (SAL), LPS, FA and Imipramine (IMI). Animals were pretreated orally with FA (10 mg/kg) and IMI (10 mg/kg) for 21 days once daily and all groups except SAL were challenged with LPS (0.83 mg/kg) intraperitoneally on day 21. Results: LPS administration produced a biphasic change in the behaviour of the animals where the animals lost a significant weight and express high immobility time at 24 h. Proinflammatory cytokines including, TNF-α, IL-6, IL-1β, and IFN-γ were significantly increased along with increased lipid peroxidation and reduced BDNF. Furthermore, the increased kynurenine to tryptophan ratio was indicative of elevated IDO activity. Conclusion: The results of this study emphasise that low dose of FA is effective in attenuating depressive-like behaviour by modulating IDO, BDNF and reducing neuroinflammation. [ABSTRACT FROM AUTHOR]

Cancer is classified into metabolic and/or genetic disorders; notably, the tryptophan catabolism pathway is vital in different cancer types. Here, we focused on the interaction and molecular connection between the cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) receptor and indoleamine-2,3-dioxygenase (IDO) enzyme. To test the impact of the selected immunotherapies on breast cancer cell migration and cell survival, we used in vitro assays. Also, we test the impact of anti-CTLA-4 antibody on the IDO-positive cells. The results of cell migration and clonogenic assays showed that anti-CTLA-4 antibody reduces cancer cell migration and clonogenic abilities of murine breast cancer cells. In addition, the result of flow cytometry showed that the anti-CTLA-4 antibody did not change the percentage of IDO-positive cancer cells. Notably, administrating an IDO blocker, 1-Methyl-DL-tryptophan (1MT), reduces the efficiency of the antiCTLA-4 antibody. The enzymatic blocking of the IDO reduces the efficiency of the anti-CTLA-4 antibody on cell migration and clonogenic abilities suggesting that there is an inhibitory interaction at the molecular level between functions of CTLA-4 and IDO. It is unclear via which mechanism(s) IDO interacts with CTLA-4 signaling and also why blocking IDO makes disruption in CTLA-4 signaling in cancer cells. Indeed, evaluating the role of IDO in CTLA-4 signaling in cancer cells may assist in clarifying a poor response to CTLA-4 immunotherapies by some patients. Hence, further investigation of the molecular interaction between CTLA-4 and IDO might help to improve the efficiency of CTLA-4 immunotherapy. [ABSTRACT FROM AUTHOR]

The article focuses on the kynurenine metabolic pathway and its increasing attention across various fields, discussing its fundamental physiological aspects and potential future diagnostic and therapeutic applications. Topics include the synthesis of kynurenine from tryptophan, the role of key enzymes like Tryptophan 2,3-Dioxygenase 2 (TDO2) and Indolamine 2,3-Dioxygenase 1 (IDO1), and the involvement of IDO in acquired immune tolerance.

Abstract Nasopharyngeal carcinoma‐derived small extracellular vesicles (NPCSEVs) have an immunosuppressive impact on the tumour microenvironment. In this study, we investigated their influence on the generation of tolerogenic dendritic cells and the potential involvement of the galectin‐9 (Gal9) they carry in this process. We analysed the phenotype and immunosuppressive properties of NPCSEVs and explored the ability of DCs exposed to NPCSEVs (NPCSEV‐DCs) to regulate T cell proliferation. To assess their impact at the pathophysiological level, we performed real‐time fluorescent chemoattraction assays. Finally, we analysed phenotype and immunosuppressive functions of NPCSEV‐DCs using a proprietary anti‐Gal9 neutralising antibody to assess the role of Gal9 in this effect. We described that NPCSEV‐DCs were able to inhibit T cell proliferation despite their mature phenotype. These mature regulatory DCs (mregDCs) have a specific oxidative metabolism and secrete high levels of IL‐4. Chemoattraction assays revealed that NPCSEVs could preferentially recruit NPCSEV‐DCs. Finally, and very interestingly, the reduction of the immunosuppressive function of NPCSEV‐DCs using an anti‐Gal9 antibody clearly suggested an important role for vesicular Gal9 in the induction of mregDCs. These results revealed for the first time that NPCSEVs promote the emergence of mregDCs using a galectin‐9 dependent mechanism and open new perspectives for antitumour immunotherapy targeting NPCSEVs.

HIV and TB are the cause of significant worldwide mortality and pose a grave danger to the global public health. TB is the leading cause of death in HIV-infected persons, with one in four deaths attributable to TB. While the majority of healthy individuals infected with M. tuberculosis (Mtb) are able to control the infection, co-infection with HIV increases the risk of TB infection progressing to TB disease by over 20-fold. While antiretroviral therapy (ART), the cornerstone of HIV care, decreases the incidence of TB in HIV-uninfected people, this remains 4- to 7-fold higher after ART in HIV-co-infected individuals in TB-endemic settings, regardless of the duration of therapy. Thus, the immune control of Mtb infection in Mtb/HIV-co-infected individuals is not fully restored by ART. We do not fully understand the reasons why Mtb/HIV-co-infected individuals maintain a high susceptibility to the reactivation of LTBI, despite an effective viral control by ART. A deep understanding of the molecular mechanisms that govern HIV-induced reactivation of TB is essential to develop improved treatments and vaccines for the Mtb/HIV-co-infected population. We discuss potential strategies for the mitigation of the observed chronic immune activation in combination with both anti-TB and anti-retroviral approaches. [ABSTRACT FROM AUTHOR]

Objective: To investigate the expression inhibition and correlation of indoleamine 2, 3-dioxygenase （IDO） and cytokine signal transduction inhibitor protein-3 （SOCS3） in placenta of patients with hypertensive disorder complicating pregnancy （HDP）. Methods: The expressions of IDO and SOCS3 in placenta of HDP were detected by Western blot method, and the expressions and correlation of them in placenta were analyzed. Results: IDO and SOCS3 were expressed in placenta of patients with HDP and normal pregnancy, and their expression was negatively correlated with the progression of HDP. There was a positive correlation between the expressions of IDO and SOCS3 in placenta of the three groups, and the correlation in preeclampsia group was higher than that in HDP group and normal pregnancy group, and the correlation in HDP group was significantly higher than that in normal pregnancy group. Conclusion: IDO and SOCS3 play an important role in immune tolerance in the third trimester of pregnancy, and may be involved in the pathogenesis of HDP. IDO and SOCS3 expressions and the degree of correlation can pre-reveal the progression of HPD. [ABSTRACT FROM AUTHOR]

Indoleamine 2,3‐dioxygenase 1 (IDO), an enzyme that metabolizes tryptophan (Trp) to kynurenine (Kyn), is an important microenvironmental factor suppressing antitumor immunity. Here, we investigated the clinical impact of aberrant Trp metabolism in patients with multiple myeloma (MM) treated with lenalidomide (Len) and evaluated its effects on T cell immunity ex vivo. Kyn and Trp concentrations were quantified in sera from 72 patients with relapsed or refractory MM prior to the initiation of therapy with Len plus dexamethasone (Ld). Associations of the Kyn/Trp ratio with progression‐free survival (PFS) and overall survival (OS) were analyzed. The expressions of IDO in tumor and stromal cells were evaluated during co‐culture, and the effects of culture medium containing low Trp and high Kyn concentrations on T cells in the presence of Len were investigated. Patients with high serum Kyn/Trp ratios (≥46.0, n = 22) had significantly shorter PFS and OS than those with low ratios (4.9 vs. 12.6 months, and 15.5 vs. 45.7 months, respectively). MM cells promoted IDO expression in stromal cells during co‐culture in both a direct contact and an indirect manner. Incubation in medium with a high Kyn/Trp ratio significantly inhibited T cell cytokine production and upregulated the expression of inhibitory immune receptors. These effects were sustained even in the presence of Len. In conclusion, a high serum Kyn/Trp ratio is associated with poor prognosis in patients with MM. We propose that aberrant Trp metabolism reduces anti‐tumor immunity and the efficacy of Len therapy. [ABSTRACT FROM AUTHOR]

B-cell precursor acute lymphoblastic leukemia (BCP-ALL), the most common childhood cancer, originates from lymphoid precursor cells in bone marrow committed to the B-cell lineage. Environmental factors and genetic abnormalities disturb the normal maturation of these precursor cells, promoting the formation of leukemia cells and suppressing normal hematopoiesis. The underlying mechanisms of progression are unclear, but BCP-ALL incidence seems to be increasing in parallel with the adoption of modern lifestyles. This study hypothesized that air pollution and haze are risk factors for BCP-ALL progression. The current study revealed that indeno(1,2,3-cd)pyrene (IP), a major component of polycyclic aromatic hydrocarbons (PAHs) in air, promotes oncogenic activities (proliferation, transformation, and disease relapse) in vitro and in vivo. Mechanistically, IP treatment activated the aryl hydrocarbon receptor (AHR)–indoleamine-2,3-dioxygenase (IDOs) axis, thereby enhancing tryptophan metabolism and kynurenine (KYN) level and consequent promoting the KYN–AHR feedback loop. IP treatment decreased the time to disease relapse and increased the BCP-ALL cell count in an orthotopic xenograft mouse model. Additionally, in 50 clinical BCP-ALL samples, AHR and IDO were co-expressed in a disease-specific manner at mRNA and protein levels, while their mRNA levels showed a significant correlation with disease-free survival duration. These results indicated that PAH/IP exposure promotes BCP-ALL disease progression. [ABSTRACT FROM AUTHOR]

Context. Melatonin influences female reproduction, but expression of the melatonin system has not been characterised in the ovine uterus. Aims. We aimed to determine whether synthesising enzymes (arylalkylamine N-acetyltransferase (AANAT) and N-acetylserotonin-O-methyltransferase (ASMT)), melatonin receptors 1 and 2 (MT1 and MT2), and catabolising enzymes (myeloperoxidase (MPO) and indoleamine 2,3-dioxygenase 1 and 2 (IDO1 and 2)), are expressed in the ovine uterus, and if they are influenced by the oestrous cycle (Experiment 1) or by undernutrition (Experiment 2). Methods. In Experiment 1, gene and protein expression was determined in sheep endometrium samples collected on days 0 (oestrus), 5, 10 and 14 of the oestrous cycle. In Experiment 2, we studied uterine samples from ewesfed either 1.5 or 0.5 times their maintenance requirements. Key results. We have demonstrated the expression of AANAT and ASMT in the endometrium of sheep. AANAT and ASMT transcripts, and AANAT protein were more elevated at day 10, then decreased to day 14. A similar pattern was observed for MT2, IDO1, and MPO mRNA, which suggests that the endometrial melatonin system might be influenced by ovarian steroid hormones. Undernutrition increased AANAT mRNA expression, but seemed to decrease its protein expression, and increased MT2 and IDO2 transcripts, whereas ASMT expression was unaffected. Conclusions. The melatonin system is expressed in the ovine uterus and is affected by oestrous cycle and undernutrition. Implications. The results help explain the adverse effects of undernutrition on reproduction in sheep, and the success of exogenous melatonin treatments in improving reproductive outcomes. [ABSTRACT FROM AUTHOR]

Simple Summary: The unique properties of invariant natural killer T (iNKT) cells make them an attractive candidate for cancer-adoptive immunotherapy. However, despite their potential, clinical studies have not consistently shown successful outcomes. This lack of efficacy is likely attributed to the immunosuppressive nature of the tumor microenvironment. In this study, we investigated the role of melanoma cell lines in suppressing iNKT cell functions, even in the presence of their specific antigen. Additionally, we aimed to identify the key factors responsible for this immunosuppressive effect. Understanding the primary contributors to the failure of iNKT cell-based therapy is crucial for developing new treatment strategies. Invariant natural killer T (iNKT) cells are a distinct group of immune cells known for their immunoregulatory and cytotoxic activities, which are crucial in immune surveillance against tumors. They have been extensively investigated as a potential target for adoptive cell immunotherapy. Despite the initial promise of iNKT cell-based immunotherapy as a treatment for melanoma patients, its effective utilization has unfortunately yielded inconsistent outcomes. The primary cause of this failure is the immunosuppressive tumor microenvironment (TME). In this study, we specifically directed our attention towards melanoma cells, as their roles within the TME remain partially understood and require further elucidation. Methods: We conducted co-culture experiments involving melanoma cell lines and iNKT cells. Results: We demonstrated that melanoma cell lines had a significant impact on the proliferation and functions of iNKT cells. Our findings revealed that co-culture with melanoma cell lines led to a significant impairment in the expression of the NKG2D receptor and cytolytic granules in iNKT cells. Moreover, we observed a strong impairment of their cytotoxic capability induced by the presence of melanoma cells. Furthermore, through the use of selective inhibitors targeting IDO1 and COX-2, we successfully demonstrated that the melanoma cell line's ability to impair iNKT cell activation and functions was attributed to the up-regulation of IDO1 expression and PGE2 production. [ABSTRACT FROM AUTHOR]

Purpose: Strategies for Indolamine-2,3-dioxygenase 1 (IDO1) inhibition in cancer immunotherapy once produced encouraging results, but failed in clinical trials. Recent evidence indicates that immune cells in the tumour microenvironment, especially macrophages, contribute to immune dysregulation and therefore might play a critical role in drug resistance. Methods: In this study, we investigated the significance of IDO1 expressing immune cells in primary tumours and corresponding lymph node metastases (LNMs) in oral squamous cell carcinoma (OSCC) by immunohistochemistry. The link between IDO1 and macrophages was investigated by flow cytometry in tumour tissue, healthy adjacent tissue and peripheral blood mononuclear cells (PBMCs). IDO1 activity (measured as Kynurenine/Tryptophan ratio) was assessed by ELISAs. Results: High IDO1 expression in tumour-infiltrating immune cells was significantly correlated with advanced stages [Spearman's rank correlation (SRC), p = 0.027] and reduced progression-free survival (multivariate Cox regression, p = 0.034). IDO1 was significantly higher expressed in PBMCs of patients in advanced stages than in healthy controls (ANOVA, p < 0.05) and IDO1+ macrophages were more abundant in intratumoural areas than peritumoural (t test, p < 0.001). IDO1 expression in PBMCs was significantly correlated with IDO1 activity in serum (SRC, p < 0.05). IDO1 activity was significantly higher in patients with LNMs (t test, p < 0.01). Conclusion: All in all, IDO1 expressing immune cells, especially macrophages, are more abundant in advanced stages of OSCC and are associated with reduced progression-free survival. Further investigations are needed to explore their role in local and systemic immune response. The IDO1 activity might be a suitable biomarker of metastasis in OSCC patients. [ABSTRACT FROM AUTHOR]

The kynurenine pathway of tryptophan degradation contributes to the differentiation of T lymphocytes, thereby influencing immune system activity, tolerance, and inflammation. The rate-limiting enzyme of the kynurenine pathway in immune cells, indoleamine 2,3-dioxygenase (IDO), has been considered to be a therapeutic target in cancer although clinical trials of IDO inhibitors have largely failed. The aryl hydrocarbon receptor (AHR) is thought to be the principal receptor through which kynurenine signals, although kynurenic acid is also a ligand for G protein-coupled receptor 35. Indoles, generated by commensal microbes, also serve as AHR agonists and therefore are likely to influence immune homeostasis as well as anticancer immunity. Lymphocytes maturing in the thymus (T cells) are key factors in adaptive immunity and the regulation of inflammation. The kynurenine pathway of tryptophan metabolism includes several enzymes and compounds that can modulate T cell function, but manipulating these pharmacologically has not achieved the expected therapeutic activity for the treatment of autoimmune disorders and cancer. With increasing knowledge of other pathways interacting with kynurenines, the expansion of screening methods, and the application of virtual techniques to understanding enzyme structures and mechanisms, details of interactions between kynurenines and other pathways are being revealed. This review surveys some of these alternative approaches to influence T cell function indirectly via the kynurenine pathway and summarizes the most recent work on the development of compounds acting directly on the kynurenine pathway. [ABSTRACT FROM AUTHOR]

Indoleamine-2,3 dioxygenase is a rate-limiting enzyme in the tryptophan catabolism in kynurenine pathways that has an immunosuppressive effect and supports cancer cells to evade the immune system in different cancer types. Diverse cytokines and pathways upregulate the production of indoleamine-2,3 dioxygenase enzymes in the tumor microenvironment and cause more production and activity of this enzyme. Ultimately, this situation results in anti-tumor immune suppression which is in favor of tumor growth. Several inhibitors such as 1-methyl-tryptophan have been introduced for indoleamine-2,3 dioxygenase enzyme and some of them are widely utilized in pre-clinical and clinical trials. Importantly at the molecular level, indoleamine-2,3 dioxygenase is positioned in a series of intricate signaling and molecular networks. Here, the main objective is to provide a focused view of indoleamine-2,3 dioxygenase enhancer pathways and propose further studies to cover the gap in available information on the function of indoleamine-2,3 dioxygenase enzyme in the tumor microenvironment. [ABSTRACT FROM AUTHOR]

The obligate intracellular protozoan parasite Toxoplasma gondii can infect any nucleated cell from a warm-blooded host. However, its interaction with host macrophages plays a critical role in shaping the immune response during infection. Therefore, assessing Toxoplasma-macrophage interactions at a cellular level is important. In this chapter, we describe assays that can be used to characterize Toxoplasma-macrophage interactions. These assays can also be used to evaluate other host-pathogen interactions. We describe multiplex approaches for measuring arginase activity, indoleamine 2,3 dioxygenase activity, cell death, and parasite growth during Toxoplasma-macrophage interactions. These assays can be used to compare how different Toxoplasma strains differ in their interaction with macrophages, and we describe how to properly assess Toxoplasma strain differences in Toxoplasma-macrophage interactions.

Abstract Background Anti‐PD‐1/PD‐L1 therapeutics have been widely used in the clinic in various tumors, including advanced esophageal cancer, showing remarkable treatment efficacy. Factors determining the response to anti‐PD‐1/PD‐L1 therapeutics are numerous, including the tumor microenvironment, such as CD8+ T cells and expression of PD‐1/PD‐L1. Our study aimed to explore the effect of chemoimmunotherapy on the expression of CD8+ T cells, TIM‐3, and FOXP3+ in tumor, paratumor tissues, and the expression of PD‐L1, IDO, in tumor, paratumor tissues, and lymph nodes, and analyze the correlation among these markers. Methods A total of 18 patients were allocated into two treatment groups: a treatment group and a concurrent control group. A total of 38 tissue samples, 114 slides (tumor, paratumor, and lymph node) were collected in the treatment group, and 37 tissue samples, 111 slides (tumor, paratumor, and lymph node) were collected in the concurrent control group. Results The expression of PD‐L1, CD8+, FOXP3+, TIM‐3, and IDO in tumors, paratumor tissues, but not lymph nodes, was significantly affected by chemoimmunotherapy. Compared with patients without chemoimmunotherapy, the expression of CD8+ T cells, IDO, and PD‐L1 was significantly decreased in tumor and paratumor tissues after chemoimmunotherapy, while FOXP3+ expression was significantly decreased only in tumor tissues, and TIM‐3 expression was significantly decreased only in paratumor tissues. Moreover, the correlation between these markers was also completely altered after chemoimmunotherapy. In addition, N staging was associated with high expression of CD8 in advanced esophageal squamous cell carcinoma in the concurrent control group. Conclusion This study provides new insight into the effects of CI treatment on isolated CD8+ T cell infiltration, PD‐L1, IDO, FOXP3+ and TIM‐3 expression as well as their cross‐talk in different tissues enabling a better understanding of the impact of CI treatment on the immune microenvironment.

Tuberculosis (TB) caused by the complex Mycobacterium tuberculosis (Mtb) is the main cause of death by a single bacterial agent. Last year, TB was the second leading infectious killer after SARS-CoV-2. Nevertheless, many biological and immunological aspects of TB are not completely elucidated, such as the complex process of immunoregulation mediated by regulatory T cells (Treg cells) and the enzymes indoleamine 2,3-dioxygenase (IDO) and heme oxygenase 1 (HO-1). In this study, the contribution of these immunoregulatory factors was compared in mice infected with Mtb strains with different levels of virulence. First Balb/c mice were infected by intratracheal route, with a high dose ofmild virulence reference strain H37Rv or with a highly virulent clinical isolate (strain 5186). In the lungs of infected mice, the kinetics of Treg cells during the infection were determined by cytofluorometry and the expression of IDO and HO-1 by RT-PCR and immunohistochemistry. Then, the contribution of immune-regulation mediated by Treg cells, IDO and HO-1, was evaluated by treating infected animals with specific cytotoxic monoclonal antibodies for Treg cells depletion anti-CD25 (PC61 clone) or by blocking IDO and HO-1 activity using specific inhibitors (1-methyl-D,L-tryptophan or zinc protoporphyrin-IX, respectively). Mice infected with the mild virulent strain showed a progressive increment of Treg cells, showing this highest number at the beginning of the late phase of the infection (28 days), the same trend was observed in the expression of both enzymes being macrophages the cells that showed the highest immunostaining. Animals infected with the highly virulent strain showed lower survival (34 days) and higher amounts of Treg cells, as well as higher expression of IDO and HO-1 one week before. In comparison with non-treated animals, mice infected with strain H37Rv with depletion of Treg cells or treated with the enzymes blockers during late infection showed a significant decrease of bacilli loads, higher expression of IFN-g and lower IL-4 but with a similar extension of inflammatory lung consolidation determined by automated morphometry. In contrast, the depletion of Treg cells in infected mice with the highly virulent strain 5186 produced diffuse alveolar damage that was similar to severe acute viral pneumonia, lesser survival and increase of bacillary loads, while blocking of both IDO and HO-1 produced high bacillary loads and extensive pneumonia with necrosis. Thus, it seems that Treg cells, IDO and HO-1 activities are detrimental during late pulmonary TB induced bymild virulence Mtb, probably because these factors decrease immune protection mediated by the Th1 response. In contrast, Treg cells, IDO and HO-1 are beneficial when the infection is produced by a highly virulent strain, by regulation of excessive inflammation that produced alveolar damage, pulmonary necrosis, acute respiratory insufficiency, and rapid death. [ABSTRACT FROM AUTHOR]

Unlike previous studies which generally seem to focus more on Hausa metaphorical expressions, this study investigates a wide range of uses of ίdὸ 'eye' in its constructional metonymy patterns in the language by exploring corpus data that contain over 300 eye-related expressions. We observe that some constructional metonymies maintain a set of fixed words and syntax in activating conceptual shifts and producing eye metonymies while others have semi-fixed patterns and produce the same metonymies. Lexical items like tsόkάlế, kὰn, ὰ, dὰ, and bὰsίrὰ among others are constant constituents in the constructional metonymies in which they appear. In the metonymic chaining, the basic mapping of eye metonymies occurs via the part for part relation under E-metonymies and the sub- for supercategory relation under C-metonymies. We also observe that E→E→C coding has the highest chained metonymic structure in the creation of the eye metonymies. Both attributive and predicative colligates motivate metonymic senses in the language. Finally, our analysis reveals that the eye is metonymically conceptualized and semantically extended to various target domains and produces metonymic conceptualizations that make the eye stand for vision, desire, envy, control, attention, perception, person, meeting, brain, intelligence, and so on. [ABSTRACT FROM AUTHOR]

Here, we investigate the role of RelB in the regulation of genes which were identified to be induced in an aryl hydrocarbon receptor (AhR)-dependent manner and critically involved in regulation of immune responses. We analyzed the expression of genes of the AhR gene battery, cytokines, and immune regulatory enzymes in bone marrow-derived macrophages (BMM) and thymus of B6 wildtype (wt) mice and RelB knockout (RelB-/-) mice after treatment with various AhR ligands. The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced expression of indoleamine 2,3-dioxygenase 1 (IDO1) and IDO2 was significantly repressed in thymus of RelB-/- mice but not in BMM derived from RelB-/- mice. Interestingly, the induced and basal expression of the cytokines interleukin (IL)-17A, IL-22, and CCL20 required the functional expression of RelB. The RelB-dependent expression of CCL20 was induced by the AhR ligands TCDD and 6-formylindolo[3,2-b]carbazole (FICZ), whereas indole-3-carbinol (I3C) suppressed CCL20 in lipopolysaccharide (LPS)-activated wt BMM. The LPS-induced expression of IL-6 and IL-10 was enhanced by TCDD and FICZ, whereas I3C significantly suppressed these cytokines in BMM. The exposure to FICZ led to higher increases of IL-17A and IL-22 mRNA compared to the effect of TCDD or I3C in thymus of wt mice. On the other hand, TCDD was the strongest inducer of CYP1A1, AhR Repressor (AhRR), and IDO2. In summary, these findings provide evidence for the important role of RelB in the transcriptional regulation of cytokines and enzymes induced by AhR ligands.

Tuberculosis (TB) caused by the complex Mycobacterium tuberculosis (Mtb) is the main cause of death by a single bacterial agent. Last year, TB was the second leading infectious killer after SARS-CoV-2. Nevertheless, many biological and immunological aspects of TB are not completely elucidated, such as the complex process of immunoregulation mediated by regulatory T cells (Treg cells) and the enzymes indoleamine 2,3-dioxygenase (IDO) and heme oxygenase 1 (HO-1). In this study, the contribution of these immunoregulatory factors was compared in mice infected with Mtb strains with different levels of virulence. First Balb/c mice were infected by intratracheal route, with a high dose of mild virulence reference strain H37Rv or with a highly virulent clinical isolate (strain 5186). In the lungs of infected mice, the kinetics of Treg cells during the infection were determined by cytofluorometry and the expression of IDO and HO-1 by RT-PCR and immunohistochemistry. Then, the contribution of immune-regulation mediated by Treg cells, IDO and HO-1, was evaluated by treating infected animals with specific cytotoxic monoclonal antibodies for Treg cells depletion anti-CD25 (PC61 clone) or by blocking IDO and HO-1 activity using specific inhibitors (1-methyl-D,L-tryptophan or zinc protoporphyrin-IX, respectively). Mice infected with the mild virulent strain showed a progressive increment of Treg cells, showing this highest number at the beginning of the late phase of the infection (28 days), the same trend was observed in the expression of both enzymes being macrophages the cells that showed the highest immunostaining. Animals infected with the highly virulent strain showed lower survival (34 days) and higher amounts of Treg cells, as well as higher expression of IDO and HO-1 one week before. In comparison with non-treated animals, mice infected with strain H37Rv with depletion of Treg cells or treated with the enzymes blockers during late infection showed a significant decrease of bacilli loads, higher expression of IFN-g and lower IL-4 but with a similar extension of inflammatory lung consolidation determined by automated morphometry. In contrast, the depletion of Treg cells in infected mice with the highly virulent strain 5186 produced diffuse alveolar damage that was similar to severe acute viral pneumonia, lesser survival and increase of bacillary loads, while blocking of both IDO and HO-1 produced high bacillary loads and extensive pneumonia with necrosis. Thus, it seems that Treg cells, IDO and HO-1 activities are detrimental during late pulmonary TB induced by mild virulence Mtb, probably because these factors decrease immune protection mediated by the Th1 response. In contrast, Treg cells, IDO and HO-1 are beneficial when the infection is produced by a highly virulent strain, by regulation of excessive inflammation that produced alveolar damage, pulmonary necrosis, acute respiratory insufficiency, and rapid death.

A higher prevalence of depression occurs in patients with lung cancer, while poor prognosis of lung cancer is often associated with depression. Excessive inflammatory response is one of the factors in the presumptive etiology of depression, and the inflammatory microenvironment also plays a key role in tumor genesis, which may indicate a common factor between the lung and the brain. Recently, a new hypothesis, called lung-brain axis, has been proposed because critical pulmonary disorders, such as acute lung injury and acute respiratory distress syndrome appear to be responsible for mood disorder and poor cognitive outcomes. Thus, lung cancer and depression might influence each other through the lung-brain axis. Findings throughout the literature suggest that activation of the interleukin (IL)-6 pathway can activate glial M1 and A1 phenotype activity, which triggers the activity of indoleamine 2,3-dioxygenase (IDO), thereby depleting tryptophan and reducing 5-hydroxytryptamine (5-HT) synthesis. The activation of IL-6 can also inhibit the expression of the 5-HT transporter through the IL-6-JAK/STAT signaling pathway. These changes are major neuropathological aspects of depression. The pathway, as mentioned above, can also promote lung cancer since increased IDO inhibits T lymphocyte proliferation and induces lymphocyte apoptosis. Therefore, the up-regulation of IDO caused by IL-6 may be the common cause for both the development of depression and lung cancer. The purpose of this review is to analyze the inflammatory mechanism and the role of the lung-brain axis in these two disease entities. The review aims to confirm the hypothesis of the lung-brain axis and promote our understanding of the interaction between the lung and the brain.

Renal cell carcinoma (RCC) is frequently infiltrated by immune cells, a process which is governed by chemokines. CD8+ T cells in the RCC tumor microenvironment (TME) may be exhausted which most likely influence therapy response and survival. The aim of this study was to evaluate chemokine-driven T cell recruitment, T cell exhaustion in the RCC TME, as well as metabolic processes leading to their functional anergy in RCC. Eight publicly available bulk RCC transcriptome collectives (n=1819) and a single cell RNAseq dataset (n=12) were analyzed. Immunodeconvolution, semi-supervised clustering, gene set variation analysis and Monte Carlo-based modeling of metabolic reaction activity were employed. Among 28 chemokine genes available, CXCL9/10/11/CXCR3, CXCL13/CXCR5 and XCL1/XCR1 mRNA expression were significantly increased in RCC compared to normal kidney tissue and also strongly associated with tumor-infiltrating effector memory and central memory CD8+ T cells in all investigated collectives. M1 TAMs, T cells, NK cells as well as tumor cells were identified as the major sources of these chemokines, whereas T cells, B cells and dendritic cells were found to predominantly express the cognate receptors. The cluster of RCCs characterized by high chemokine expression and high CD8+ T cell infiltration displayed a strong activation of IFN/JAK/STAT signaling with elevated expression of multiple T cell exhaustion-associated transcripts. Chemokinehigh RCCs were characterized by metabolic reprogramming, in particular by downregulated OXPHOS and increased IDO1-mediated tryptophan degradation. None of the investigated chemokine genes was significantly associated with survival or response to immunotherapy. We propose a chemokine network that mediates CD8+ T cell recruitment and identify T cell exhaustion, altered energy metabolism and high IDO1 activity as key mechanisms of their suppression. Concomitant targeting of exhaustion pathways and metabolism may pose an effective approach to RCC therapy. [ABSTRACT FROM AUTHOR]

The identification and characterization of tumor antigens are central objectives in developing anti-cancer immunotherapy. Traditionally, tumor-associated antigens (TAAs) are considered relatively restricted to tumor cells (i.e., overexpressed proteins in tumor cells), whereas tumor-specific antigens (TSAs) are considered unique to tumor cells. Recent studies have focused on identifying patient-specific neoantigens, which might be highly immunogenic because they are not expressed in normal tissues. The opposite strategy has emerged with the discovery of anti-regulatory T cells (anti-Tregs) that recognize and attack many cell types in the tumor microenvironment, such as regulatory immune cells, in addition to tumor cells. The term proposed in this review is "tumor microenvironment antigens" (TMAs) to describe the antigens that draw this attack. As therapeutic targets, TMAs offer several advantages that differentiate them from more traditional tumor antigens. Targeting TMAs leads not only to a direct attack on tumor cells but also to modulation of the tumor microenvironment, rendering it immunocompetent and tumor-hostile. Of note, in contrast to TAAs and TSAs, TMAs also are expressed in non-transformed cells with consistent human leukocyte antigen (HLA) expression. Inflammation often induces HLA expression in malignant cells, so that targeting TMAs could additionally affect tumors with no or very low levels of surface HLA expression. This review defines the characteristics, differences, and advantages of TMAs compared with traditional tumor antigens and discusses the use of these antigens in immune modulatory vaccines as an attractive approach to immunotherapy. Different TMAs are expressed by different cells and could be combined in anti-cancer immunotherapies to attack tumor cells directly and modulate local immune cells to create a tumor-hostile microenvironment and inhibit tumor angiogenesis. Immune modulatory vaccines offer an approach for combinatorial therapy with additional immunotherapy including checkpoint blockade, cellular therapy, or traditional cancer vaccines. These combinations would increase the number of patients who can benefit from such therapeutic measures, which all have optimal efficiency in inflamed tumors. [ABSTRACT FROM AUTHOR]

Objective We aimed to investigate the plasma levels of tryptophan (Trp) and its metabolites in patients with primary Sjögren's syndrome (pSS). Methods The study included 34 pSS patients and 42 healthy individuals, and serum Trp and kynurenine (Kyn) concentrations were measured by liquid chromatography with tandem mass spectrometry. Trp degradation was predicted using the ratio of Kyn and Trp concentrations (Kyn/Trp). Results In our study, the mean serum Trp concentration was found to be considerably lower in the pSS group than in the control group (P  = .001). The levels of Kyn (P  = .019) and the Kyn/Trp ratio (P  < .001) were significantly higher in the pSS group than in the control group. The Kyn/Trp ratio was negatively correlated with C-reactive protein (r = −0.369, P  = .032). Conclusion We found that Kyn pathway metabolism was altered in patients with pSS. This suggests that Trp metabolism may be closely linked to the disease pathogenesis of pSS. [ABSTRACT FROM AUTHOR]

Fatigue is a frequent symptom in hemodialysis (HD), and the indolamine-2,3-dioxygenase (IDO) metabolic trap has been hypothesized in the pathogenesis of fatigue. The association between IDO activity according to fatigue and its relationship with muscle mass and function in HD patients was verified. Chronic HD patients were considered, and fatigue was assessed. The plasma kynurenines and tryptophan ratio (Kyn/Trp), as surrogate of IDO activity, and interleukin (IL)-6 were measured. Muscularity was assessed by BIA and muscle strength by hand-grip dynamometer. 50 HD patients were enrolled, and fatigue was present in 24% of the cohort. Patients with fatigue showed higher Kyn/Trp (p = 0.005), were older (p = 0.007), and IL-6 levels resulted higher than in non-fatigue patients (p < 0.001). HD patients with fatigue showed lower intracellular water (surrogate of muscle mass) (p < 0.001), as well as lower hand grip strength (p = 0.02). The Kyn/Trp ratio positively correlated with IL-6 and ECW/ICW (p = 0.004 and p = 0.014). By logistic regression analysis, higher ICW/h2 was associated with lower odds of fatigue (OR, 0.10; 95% CI, 0.01 to 0.73). In conclusion, our cohort fatigue was associated with a higher Kyn/Trp ratio, indicating a modulation of IDO activity. The Kyn/Trp ratio correlated with IL-6, suggesting a potential role of IDO and inflammation in inducing fatigue and changes in muscularity. [ABSTRACT FROM AUTHOR]

Background: A growing body of evidence suggests that inflammation and changes in glutamate neurotransmission are two pathophysiological mechanisms underlying depression. Electroacupuncture (EA) is a common therapeutic tool for the treatment of depression. However, the potential antidepressant mechanism of EA remains obscure. The change of the kynurenine pathway (KP) is the research priority of antidepressant mechanisms. This study will investigate the role of EA on lipopolysaccharide (LPS)-induced depression-like behavior and explore its possible mechanism of action. Methods: Lipopolysaccharide was used to induce depression-like behavior, and EA was given at Hegu (L14) and Taichong (LR3) acupoints in C57BL/6J mice. Depression-like behaviors were measured by behavioral tests, including tail suspension test (TST), sucrose preference test (SPT), force swim test (FST), and open field test (OFT). The levels of inflammatory cytokines IL1β, IL-6, and TNF-α, and KP enzyme IDO1 were measured by qPCR and enzyme-linked immunosorbent assay (ELISA), while high-performance liquid chromatography (HPLC) was performed to detect the content of prefrontal cortex and hippocampal as well as serum glutamate, tryptophan (TRP), kynurenic (KYN), and quinolinic acid (QA). Results: The results showed that (1) as evidenced by increased spontaneous locomotor activities, decreased immobility duration, and a stronger preference for sucrose in the sucrose preference test, EA reversed LPSchallenged depressive-like behavior. (2) EA at L14 and LR3 decreased the levels of inflammatory cytokines, inhibited IDO1, and regulated KP metabolisms, as well as lowered the concentration of glutamate. (3) EA may exert antidepression effects by acting on the kynurenine pathway. Conclusion: This study evaluated the effects of EA on depressionlike behaviors induced by lipopolysaccharide (LPS) and its regulation of inflammation and the glutamatergic system. Our results suggest that EA can ameliorate depression-like behaviors, lower the level of inflammation, and reduce the release of glutamate, possibly through the regulation of the kynurenine pathway in the brain. [ABSTRACT FROM AUTHOR]

Introduction: Three-dimensional (3D) clumps of mesenchymal stem cells (MSCs)/extracellular matrix (ECM) complexes, composed with cells and self-produced intact ECM, can be grafted into defect areas without artificial scaffold to induce successful bone regeneration. Moreover, C-MSCs pretreated with IFN-γ (C-MSCsγ) increased the immunomodulatory enzyme indoleamine 2,3-dioxygenase (IDO) expression and thereby inhibited T cell activity. Xenotransplantation of human C-MSCsγ suppressed host T cell immune rejection and induced bone regeneration in mice. Besides, we have also reported that C-MSCs retain the 3D structure and bone regenerative property even after cryopreservation. To develop the “off-the-shelf” cell preparation for bone regenerative therapy that is promptly provided when needed, we investigated whether C-MSCsγ can retain the immunosuppressive and osteogenic properties after cryopreservation. Methods: Confluent human MSCs that had formed on the cellular sheet were scratched using a micropipette tip and then torn off. The sheet was rolled to make a round clump of cells. The round cell clumps were incubated with a growth medium for 3 days, and then C-MSCs were obtained. To generate C-MSCsγ, after 2 days’ culture, C-MSCs were stimulated with 50 ng/ml of IFN-γ. Both C-MSCs and C-MSCsγ were cryopreserved for 2 days and then thawed to obtain Cryo-C-MSCs and Cryo-C-MSCsγ, respectively. The biological properties of those cell clumps were assessed in vitro. In addition, to test whether human Cryo-C-MSCsγ attenuates immune rejection to induce bone regeneration, a xenograft study using a rat calvarial defect was performed. Results: Both IFN-γ pretreatment and cryopreservation process did not affect the 3D structure and cell viability in all human cell clumps. Interestingly, Cryo-C-MSCsγ showed significantly increased IDO mRNA expression equivalent to C-MSCsγ. More importantly, xenotransplantation of human C-MSCsγ and Cryo-C-MSCsγ induced rat calvarial bone regeneration by suppressing rat T cells infiltration and the grafted human cells reduction in the grafted area. Finally, there were no human donor cells in the newly formed bone, implying that the bone reconstruction by C-MSCsγ and Cryo-C-MSCsγ can be due to indirect host osteogenesis. Conclusion: These findings implied that Cryo-C-MSCsγ can be a promising bone regenerative allograft therapy that can be certainly and promptly supplied on demand.

[Aims] Flavonoid apigenin (API) has a wide range of biological functions, particularly anti-inflammation. Indoleamine 2,3-dioxygenase (IDO) and 2-Amino-3-carboxymuconate-6-semialdehyde decarboxylase (ACMSD) are important tryptophan metabolic enzymes that play pivotal roles in the production of toxic metabolite quinolinic acid. However, the relationship between inflammation and ACMSD remains unclear. The present study investigated the relationship between inflammation and tryptophan metabolic key enzymes. Similarly, the anti-inflammatory effect of API on important tryptophan metabolic enzymes was examined in lipopolysaccharide (LPS)-treated microglial cells.[Main methods] MG6 cells were exposed to LPS with or without API treatment for 24–48 h. IDO and ACMSD mRNA expression and production of inflammatory mediators were analyzed. Activation of inflammatory signaling pathways, such as mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB), was also examined to study the mechanism of API in the inflammatory state.[Key findings] LPS suppressed ACMSD expression and enhanced IDO expression. However, API elevated ACMSD mRNA expression and suppressed IDO mRNA expression in LPS-treated MG6 cells. Furthermore, API suppressed interleukin-6 and nitric oxide production, whereas overproduction of inflammatory mediators enhanced IDO expression and assisted tryptophan degradation. API also inhibited activation of extracellular signal-regulated kinase (Erk) and jun N-terminal kinase (JNK) MAPK, and degradation of IκBα.[Significance] These results indicate alteration of ACMSD expression under inflammatory conditions. Moreover, API recovers expression of tryptophan metabolic key enzymes, which may be mediated by inhibition of proinflammatory mediator production via inactivation of Erk, JNK MAPK, and NF-κB pathways in LPS-stimulated microglial cells.

Simple Summary: Inflammatory bowel disease (IBD) affects the colon and is divided in two main pathologies, ulcerative colitis and Crohn's disease. It is characterised by inflammation, which is managed by anti-inflammatory treatments, however, in the long term they lose effectiveness. Chronic inflammation/chronic colitis pre-disposes the person to increased risk of colorectal cancer (CRC). Checkpoint markers has revolutionised immunotherapeutic treatments especially in colorectal cancer. Here, we present different checkpoint inhibitors and their role in IBD and CRC. Inflammatory Bowel Disease (IBD) is a group of diseases that cause intestinal inflammation and lesions because of an abnormal immune response to host gut microflora. Corticosteroids, anti-inflammatories, and antibiotics are often used to reduce non-specific inflammation and relapse rates; however, such treatments are ineffective over time. Patients with chronic colitis are more susceptible to developing colorectal cancer, especially those with a longer duration of colitis. There is often a limit in using chemotherapy due to side effects, leading to reduced efficacy, leaving an urgent need to improve treatments and identify new therapeutic targets. Cancer immunotherapy has made significant advances in recent years and is mainly categorized as cancer vaccines, adoptive cellular immunotherapy, or immune checkpoint blockade therapies. Checkpoint markers are expressed on cancer cells to evade the immune system, and as a result checkpoint inhibitors have transformed cancer treatment in the last 5–10 years. Immune checkpoint inhibitors have produced long-lasting clinical responses in both single and combination therapies. Winnie mice are a viable model of spontaneous chronic colitis with immune responses like human IBD. Determining the expression levels of checkpoint markers in tissues from these mice will provide insights into disease initiation, progression, and cancer. Such information will lead to identification of novel checkpoint markers and the development of treatments with or without immune checkpoint inhibitors or vaccines to slow or stop disease progression. [ABSTRACT FROM AUTHOR]

Contemporary management literature considers play as an important and inevitable aspect of organizational life. Workplace play permeates work processes in different qualities, and this is also reflected in terms of working time. This study aims to explore the relationship between play and time in an organizational context, contrasting it with the quality of work. The authors sought to answers the question of how play and time co-organise the life of organizations and what connections can be discovered in the triad of work, time, and play. It can be concluded that play and time are inseparable concepts in organizations and that in work processes they can discover ever-deepening levels of (temporal) admission of play, based, in each case, on dominant beliefs about the quality of and relationship between play and work. [ABSTRACT FROM AUTHOR]