Search Results (236)

Evaluating the activity of indoleamine 2,3-dioxygenase (IDO), the rate-limiting enzyme in tryptophan (Trp) metabolism, is important because IDO is involved in immune tolerance and drives the production of Trp metabolites implicated in psychiatric disorders and cancer. This study aimed to design and develop a novel fluorescent l-Trp derivative to fluorometrically monitor Trp-catabolizing enzyme activity via IDO. To evaluate IDO activity in vivo, 7-N,N-dimethylamino-2,1,3-benzoxadiazole (DBD), a fluorophore, was covalently bound at the 5-position of the indole ring in Trp to produce 5-DBD-l-Trp. An in vivo microdialysis (MD) study was conducted using the kidneys of Sprague–Dawley rats. Specifically, 5.0 μM 5-DBD-l-Trp in phosphate-buffered Ringer’s solution was infused into the rats, and the MD sample was analyzed via high-performance liquid chromatography with fluorescence detection. In the MD sample, two fluorescence peaks other than 5-DBD-l-Trp were observed during the 5-DBD-l-Trp infusion, and the main metabolite peak was proposed to be 5-DBD-kynurenine, verified by liquid chromatography-tandem mass spectrometry. The intensity of the fluorescent peak was significantly attenuated by co-infusion with an IDO inhibitor, 1-methyl-d-Trp. These results suggest that 5-DBD-l-Trp may be metabolized by renal IDO and can be used to evaluate IDO activity in vivo. Full article

The cells in the central nervous system (CNS) can adapt to injury and inflammation through structural and functional changes, many of which are mediated by the kynurenine pathway (KP). Studies using glia–neuron co-cultures showed that the biflavonoid agathisflavone (FAB), purified from the leaves of Cenostigma pyramidale Tul., a plant native to the Brazilian caatinga, exerts strong neuroprotective effects. This study evaluated whether agathisflavone (1 µM) modulates these responses in human and murine astrocytes and microglia exposed to inflammatory activation with lipopolysaccharide (LPS, 1 µg/mL), excitotoxic activation of NMDA receptors with quinolinic acid (QUIN, 500 µM), or inhibition of the KP rate-limiting enzyme indoleamine 2,3-dioxygenase 1 (IDO1) with 1-methyl tryptophan (1-MT, 1.5 μM). Co-treatment with FAB increased astrocyte viability relative to LPS, QUIN, or 1-MT alone, by up to 35% (p < 0.05), while reducing GFAP overexpression and other features of reactive astrogliosis. FAB decreased the proportion of Iba-1⁺ microglia, indicating anti-inflammatory effects. When combined with QUIN or 1-MT, FAB reversed the elevation of iNOS (p < 0.0001) and reduced IL1β upregulation. FAB also modulated KP activity in a cell type-specific manner. In astrocytes, FAB with QUIN or with 1-MT increased IDO activity, whereas in microglia, FAB alone reduced it. In microglia, kynurenine-3-monooxygenase (KMO) expression was significantly increased under FAB+QUIN or FAB+1-MT (p < 0.0001). Finally, astrocyte-conditioned medium from FAB-treated cells increased the viability of neuron-like PC12 cells by up to 40%. Collectively, these findings show that FAB confers cytoprotective and anti-inflammatory actions on glial cells, modulates KP signalling in a context-dependent manner, and supports neuronal survival under neuroinflammatory conditions. Full article

Background and Objectives: Pituitary adenomas are common intracranial tumors lacking specific non-invasive biomarkers. This study aimed to determine whether key metabolites and enzymes of the kynurenine pathway—including indoleamine 2,3-dioxygenase (IDO), kynurenine (KYN), kynurenic acid (KYNA), kynurenine aminotransferase (KAT), quinolinic acid, and picolinic acid—can serve as diagnostic biomarkers distinguishing patients with pituitary adenomas from healthy controls. Materials and Methods: We conducted a single-center, cross-sectional, case–control study with 50 patients with pituitary adenomas and 35 healthy controls. Serum levels of IDO, KYN, KYNA, KAT, quinolinic acid, and picolinic acid were measured via enzyme-linked immunosorbent assay (ELISA). Statistical analyses included group comparisons (t-test/Mann–Whitney U), multivariate logistic regression to identify independent predictors, receiver operating characteristic (ROC) curve analysis to evaluate diagnostic performance (area under the curve, AUC), and partial least squares discriminant analysis (PLS-DA) for multivariate metabolic profiling. Results: Serum kynurenine, kynurenic acid, 3-hydroxykynurenine, picolinic acid, IDO and kynureninase were significantly higher in the pituitary adenoma group than in healthy controls (p < 0.001), while tryptophan, kynurenine aminotransferase, anthranilic acid and quinolinic acid showed no significant differences. ROC analysis demonstrated excellent diagnostic accuracy, with KAT (AUC = 0.923) and KYNA (AUC = 0.901) showing the highest discrimination. Multivariate logistic regression identified IDO, KYN, and KYNA as independent predictors of pituitary adenoma (p < 0.05). PLS-DA of the combined metabolite data also demonstrated clear separation between patients and controls, confirming distinct metabolic profiles between the groups. Conclusions: Kynurenine pathway metabolites and enzymes show strong potential as non-invasive biomarkers for pituitary adenomas. In particular, elevated KAT and KYNA levels demonstrated high diagnostic performance. These findings suggest that a panel of kynurenine pathway metabolites could aid in the early, non-invasive detection of pituitary adenomas. Full article

Rosacea is a chronic inflammatory skin disorder of multifactorial pathogenesis, in which dysregulated innate immunity, neurovascular dysfunction, oxidative stress, and microbiome imbalance are central contributors. Recent molecular studies have revealed altered cytokine expression (e.g., IL-1β, IL-6, IL-36 family), aberrant activation of signaling pathways (STAT3, NF-κB, MAPKs), and enhanced expression of innate immune receptors such as TLR2,b TLR4, and TLR7, all of which promote chronic inflammation, angiogenesis, and barrier dysfunction. This systematic review was performed according to PRISMA guidelines. A total of 1425 records were retrieved from PubMed, Scopus, and Web of Science, and 14 studies met the inclusion criteria. The included studies comprised both clinical cohorts and translational experimental investigations using human samples. Reported findings consistently confirmed systemic and tissue-specific inflammatory activity, with elevated circulating monocytes, indoleamine 2,3-dioxygenase, and inflammatory indices, as well as tissue expression of STAT3, NF-κB, MAPKs, and cathelicidin fragments. Oxidative stress markers (TOS, OSI, AOPP, MMP-9) and hypoxia-related molecules (HIF-1α) were significantly increased in patients, correlating with disease severity and vascular manifestations. Taken together, these results highlight that rosacea involves both cutaneous and systemic molecular alterations. The evidence identifies multiple biomarkers with diagnostic potential and provides mechanistic insights into immune, vascular, and metabolic dysregulation. Future research should aim to validate these findings in larger cohorts, establish standardized biomarker panels, and explore novel therapeutic strategies targeting key molecular pathways. Full article

Sexual dimorphism influences immune responses, cancer progression, and therapeutic outcomes, yet its metabolic underpinnings remain underexplored. Metabolomics enables the comprehensive profiling of biochemical pathways that shape sex-based differences in immune function and immunotherapy efficacy. Meta-analytic data indicate that men achieve a larger overall survival benefit from immune checkpoint inhibitors than women (pooled hazard ratio 0.72, 95% CI 0.65–0.79 vs. 0.86, 95% CI 0.79–0.93), while women may experience higher major pathologic response rates in neoadjuvant settings. At the biomarker level, elevated kynurenine-to-tryptophan ratios—reflecting indoleamine 2,3-dioxygenase activity—and distinct lipidomic signatures associate with reduced immunotherapy efficacy and may vary by sex. Sex-specific differences in microbiome-derived metabolites, including short-chain fatty acids, further modulate systemic immunity and treatment response. Ongoing clinical investigations combine hormone modulation with immune checkpoint blockade and increasingly integrate metabolomic profiling to identify predictors of benefit and toxicity. This review will synthesize meta-analytic and mechanistic evidence on sex differences in immunotherapy outcomes, highlight metabolomic biomarkers linked to response, and summarize ongoing clinical trials that incorporate metabolomics to guide sex-aware precision oncology. Understanding sex-specific metabolic pathways can refine patient stratification and optimize immunotherapeutic strategies. Full article

Leprosy is a chronic infectious disease that targets the peripheral nervous system, leading to peripheral neuropathy. Mycobacterium leprae primarily infects Schwann cells, adipocytes, and macrophages, altering their metabolism and gene expression. This study investigates the metabolic interaction between M. leprae and Schwann cells, with a focus on indoleamine 2,3-dioxygenase (IDO), a key enzyme in tryptophan catabolism via the kynurenine pathway. We found that M. leprae induces IDO expression in Schwann cells, suggesting a role in immune modulation and neuropathy. Inhibition of IDO with 1-methyl-L-tryptophan (1-MT) reduced Schwann cell viability and metabolic activity in response to M. leprae. After 24 h of infection, M. leprae impaired mitochondrial membrane potential, although no significant changes in autophagy or mitochondrial ultrastructure were observed by electron microscopy. Interestingly, IDO1 inhibition upregulated the expression of antioxidant genes, including GPX4, NFE2L2, and HMOX1. In conclusion, these findings highlight a central role for IDO in shaping the metabolic and immunological response of Schwann cells to M. leprae infection. IDO induction contributes to immune regulation and cellular stress, while its inhibition disrupts cell viability and promotes antioxidant gene expression. These results position IDO as a potential therapeutic target for modulating host–pathogen interactions and mitigating nerve damage in leprosy. Full article

Minocycline (MINO), a classic antibiotic, may have psychotropic activity related to the modulation of the tryptophan-kynurenine pathway. In this study, we investigated the effects of MINO on (1) memory and anxiety behaviors, (2) the modulation of brain levels of amyloid precursor protein (APP) and 2,3-indoleamine dioxygenase (IDO1) levels, and (3) peripheral inflammatory markers in a streptozotocin (STZ)-induced rat model of sporadic Alzheimer’s disease (sAD). After repeated treatment with a dose of 35 mg/kg MINO for seven consecutive days, male Wistar rats with sAD showed (1) improvements in early (29 days after injection, probe test) reference memory (decreased latency to reach the platform, increased time in the critical quadrant of the Morris water maze) and anxiety disorders (increased time in the open arms of the elevated plus maze; increased exploration and entrances in the center of the white–light illuminated open field) 45–46 and 90–91 days after STZ injection; (2) reduced APP and IDO1 levels in the hippocampus and prefrontal cortex; and (3) induction of anti-inflammatory response in blood (increased TCD4⁺ lymphocyte number and interleukin-10 production). This suggests that MINO, due to its anti-inflammatory action, improves memory and anxiety behavior related to sAD, indicating its neuroprotective and psychotropic properties. Full article

Background: The liver’s role as a metabolic gatekeeper positions it uniquely to influence systemic metabolic homeostasis and potentially modulate leukemogenesis through hepato-hematopoietic crosstalk. Recent observations of rare hematological malignancies following mRNA vaccination warrant mechanistic investigation. Hypothesis: We propose that mRNA vaccines, through their preferential hepatic tropism via lipid nanoparticles (LNPs), may transiently dysregulate hepatic metabolism in susceptible individuals, creating metabolic perturbations that amplify pre-existing leukemogenic vulnerabilities through five interconnected mechanisms: (1) competitive folate sequestration for vaccine-induced lymphoproliferation, potentially starving bone marrow precursors of essential one-carbon units; (2) hepatic lipid processing overload from LNP accumulation, exacerbating phospholipid dysregulation in pre-leukemic clones; (3) cytokine-mediated upregulation of hepatic indoleamine 2,3-dioxygenase (IDO), accelerating tryptophan catabolism and creating an immunosuppressive milieu favoring leukemic escape; (4) inflammatory induction of hepcidin, sequestering hepatic iron while triggering compensatory intestinal iron hyperabsorption and potential bone marrow iron overload; and (5) increased hepatic NADPH demand for antioxidant defense and lipid metabolism, diverting reducing equivalents from bone marrow stromal support. Implications: This hypothesis suggests that transient hepatic metabolic perturbations may create a permissive milieu for leukemogenesis in metabolically vulnerable individuals. The proposed mechanisms generate testable predictions and identify potential therapeutic targets, including folate supplementation, IDO inhibition, and iron chelation in high-risk cohorts. Full article

Indoleamine 2,3-dioxygenase (IDO) activation by seizures elevates toxic tryptophan metabolites linked to seizure exacerbation. Brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) signaling, oxidative stress, and mitochondrial respiratory chain complex dysfunction contribute to temporal lobe epilepsy (TLE), but their regulatory links remain unclear. Male Kunming mice were grouped into Control, Control + 1-Methyl-DL-tryptophan (1-MT), TLE, and TLE + 1-MT. TLE was induced with 300 mg/kg pilocarpine. Two weeks after modeling, 1-MT (50 mg/kg) was administered twice daily for two weeks in 1-MT groups. Assessments included video monitoring to record seizure frequency and duration; Nissl and Fluoro-Jade B (FJB) staining to evaluate neuronal damage; real-time quantitative PCR (qRT-PCR) and Western blot to detect IDO, BDNF, and TrkB expression; assays for the following oxidative stress markers: malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT); and detection of mitochondrial complex I/IV activities. Results showed TLE mice had significantly increased IDO expression, BDNF/TrkB over-activation, elevated oxidative stress, impaired mitochondrial complex I/IV activities, severe neuronal damage, and increased seizure frequency/duration. 1-MT intervention reversed all these pathological changes, restoring levels to near-control status. This indicates IDO activation promotes TLE progression, which is associated with modulation of the BDNF/TrkB signaling pathway, exacerbation of oxidative stress, and impairment of mitochondrial complex I/IV activities—supporting IDO as a potential therapeutic target for TLE. Full article

Background: Radon, a naturally occurring radioactive gas, is increasingly recognized as a major risk factor for lung cancer (LC), especially among non-smokers. The objective of this study was to identify serum biomarkers for the early detection of LC in individuals at high risk due to prolonged residential radon exposure in Chiang Mai, Thailand, and to assess whether the use of single or combined biomarkers improves the sensitivity and specificity of detection. Methods: A total of 15 LC patients and 30 healthy controls (HC) were enrolled. The HC group was further stratified into two subgroups: low radon (LR, n = 15) and high radon (HR, n = 15) exposure. All participants were non-smokers or former smokers. Serum levels of cytokeratin 19 fragment (CYFRA 21-1), carcinoembryonic antigen (CEA), interleukin-6 (IL-6), interleukin-8 (IL-8), transforming growth factor-alpha (TGF-alpha), and indoleamine 2,3-dioxygenase-1 (IDO-1) were measured using the Milliplex^® Kit on a Luminex^® Multiplexing Instrument (MAGPIX^® System). Results: Serum CEA, IL-6 and IL-8 levels were significantly higher in LC patients compared to the HC group (p < 0.05). Among analyzed biomarkers, only IL-8 was significantly elevated in LC patients compared to the HR group (p = 0.04). Notably, CYFRA 21-1 was the only biomarker that significantly differed between LR and HR groups (p = 0.004). The diagnostic potential of these biomarkers was evaluated using receiver operating characteristic (ROC) analysis. Individually, IL-6 showed the highest discriminative ability for differentiating LC patients from both HC and HR groups, with high specificity but moderate sensitivity. Combining IL-6 and IL-8 improved specificity and increased the area under the ROC curve (AUC), though it did not enhance sensitivity for distinguishing LC from HC. For distinguishing LC from HR individuals, IL-6 and CYFRA 21-1 exhibited strong diagnostic performance. Their combination significantly improved diagnostic accuracy, yielding the highest AUC, sensitivity, and specificity. In contrast, CEA, IL-8, TGF-alpha, and IDO-1 demonstrated limited diagnostic utility. Conclusions: Based on the available literature, this is the first study to evaluate the combined use of IL-6 and CYFRA 21-1 as potential biomarkers for LC screening in individuals with high residential radon exposure. Our findings highlight their utility, particularly in combination, for improving diagnostic accuracy in this high-risk population. Full article

The kynurenine (KYN) metabolic pathway sits at the crossroads of immunity, metabolism, and neurobiology, yet its clinical translation remains fragmented. Emerging spatial omics, wearable chronobiology, and synthetic microbiota studies reveal that tryptophan (Trp) metabolism is regulated by distinct cellular “checkpoints” along the gut–brain axis, finely modulated by sex differences, circadian rhythms, and microbiome composition. However, current interventions tackle single levers in isolation, leaving a key gap in the precision control of Trp’s fate. To address this, we drew upon an extensive body of the primary literature and databases, mapping enzyme expression across tissues at single-cell resolution and linking these profiles to clinical trials investigating dual indoleamine 2,3-dioxygenase 1 (IDO1)/tryptophan 2,3-dioxygenase (TDO) inhibitors, engineered probiotics, and chrono-modulated dosing strategies. We then developed decision-tree algorithms that rank therapeutic combinations against biomarker feedback loops derived from real-time saliva, plasma, and stool metabolomics. This synthesis pinpoints microglial and endothelial KYN hotspots, quantifies sex-specific chronotherapeutic windows, and identifies engineered Bifidobacterium consortia and dual inhibitors as synergistic nodes capable of reducing immunosuppressive KYN while preserving neuroprotective kynurenic acid. Here, we highlight a framework that couples lifestyle levers, bio-engineered microbes, and adaptive pharmaco-regimens into closed-loop “smart protocols.” By charting these intersections, this study offers a roadmap for biomarker-guided, multidisciplinary interventions that could recalibrate KYN metabolic activity across cancer, mood, neurodegeneration, and metabolic disorders, appealing to clinicians, bioengineers, and systems biologists alike. Full article

Hyperlipidemia, oxidative stress, and excessive inflammatory cytokine production are risk factors for depression. The potential preventive effects of essential oils (EOs) such as cumin and fennel EOs on depression may stem from their hypolipidemic, antioxidant, and anti-inflammatory activities. This work aimed to investigate the effects of cumin and fennel EO nanocapsules in a mouse model of depression caused by a high-fat diet (HFD) and chronic mild stress (CMS) using both in silico and in vivo studies. The cumin and fennel EOs were extracted, analyzed by GC-MS, and encapsulated in nano-form using gum Arabic and maltodextrin as wall materials. The freeze-dried nanocapsules were evaluated in HFD/CMS-treated mice. Molecular docking was used to examine the significance of the oils’ compounds in blocking the active sites of hydroxymethylglutaryl-CoA (HMG-CoA) and indoleamine 2,3-dioxygenase (IDO). According to the molecular docking results, the interactions between EO components and HMG-CoA or IDO indicate that these EOs may have hypercholesterolemic and antidepressive effects. Cumin and fennel EO nanocapsules showed hypolipidemic, antioxidant, and anti-inflammatory effects in vivo. This was demonstrated by the down-regulation of oxidants (ROS, MDA, and NO) and inflammatory markers (TLR4, TNF-α, and IL-6) in the brain, changes in lipid profile parameters, and the up-regulation of antioxidant enzymes (SOD, CAT, and GSH). The in silico and in vivo outputs revealed the potential preventive impact of cumin and fennel EO nanocapsules against depression-like states in the mouse model through the prevention of dyslipidemia, neuroxidation, and neuroinflammation. More human studies are needed to fully understand the antidepressive effects of cumin and fennel EO nanocapsules. Full article

Skeletal muscle atrophy is a critical health issue affecting the quality of life of elderly individuals and patients with chronic diseases. These conditions induce dysregulation of glucocorticoid (GC) secretion. GCs play a critical role in maintaining homeostasis in the stress response and glucose metabolism. However, prolonged exposure to GC is directly linked to muscle atrophy, which is characterized by a reduction in muscle size and weight, particularly affecting fast-twitch muscle fibers. The GC-activated glucocorticoid receptor (GR) decreases protein synthesis and facilitates protein breakdown. Numerous antagonists have been developed to mitigate GC-induced muscle atrophy, including 11β-HSD1 inhibitors and myostatin and activin receptor blockers. However, the clinical trial results have fallen short of the expected efficacy. Recently, several emerging pathways and targets have been identified. For instance, GC-induced sirtuin 6 isoform (SIRT6) expression suppresses AKT/mTORC1 signaling. Lysine-specific demethylase 1 (LSD1) cooperates with the GR for the transcription of atrogenes. The kynurenine pathway and indoleamine 2,3-dioxygenase 1 (IDO-1) also play crucial roles in protein synthesis and energy production in skeletal muscle. Therefore, a deeper understanding of the complexities of GR transactivation and transrepression will provide new strategies for the discovery of novel drugs to overcome the detrimental effects of GCs on muscle tissues. Full article

Indoleamine 2,3-dioxygenase 1 (IDO-1) and interferon-gamma (IFN-γ) are proteins that play a significant role in inflammatory conditions and tumor development. The detection of IDO1 and IFN-γ is crucial for understanding their interplay in immune responses. This study introduced a novel method for the simultaneous quantitative determination of IDO-1 and IFN-γ in different biological samples/materials. The method is based on an optical biosensor, with surface plasmon resonance detection carried out by the imaging version of the sensor (SPRi). Biotinylated antibodies immobilized on the surfaces of the linker and carboxymethylated dextran served as the recognition elements for the developed biosensor. Relevant studies were conducted to optimize the activities of the biosensor by employing appropriate reagent concentrations. Validation was performed for each protein separately; low detection and quantification limits were obtained (for IDO-1 LOD = 0.27 ng/mL, LOQ = 0.81 ng/mL; for IFN-γ LOD = 1.76 pg/mL and LOQ = 5.29 pg/mL). The sensor operating ranges were 0.001–10 ng/mL for IDO-1 and 0.1–1000 pg/mL for IFN-γ. The constructed biosensor demonstrated its sensitivity and precision when the appropriate analytical parameters were determined, based on the proposed method. It can also selectively capture IDO-1 and IFN-γ from a large sample matrix. The biosensor efficiency was confirmed by the determination of IDO-1 and IFN-γ in simultaneous measurements of the plasma and urine samples of patients diagnosed with bladder cancer and the control group. The outcomes were compared to those obtained using a certified ELISA test, demonstrating convergence between the two methodologies. The preliminary findings demonstrate the biosensor’s efficacy and suitability for comprehensive analyses of the examined biological samples. Full article

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of immune cells that play a central role in regulating host immune responses during fungal infections. Their recruitment is mediated by pathogen recognition receptors, particularly Dectin-1 and CARD9 signaling, which promote the production of reactive oxygen species (ROS) and IL-1β. Once activated, MDSCs suppress T-cell and natural killer cell functions through immunosuppressive cytokines like IL-10 and TGF-β, as well as enzymes such as arginase-1 and indoleamine 2,3-dioxygenase 1 (IDO-1). This review explores the role of MDSCs in fungal infections caused by Candida spp., Paracoccidioides brasiliensis, Aspergillus spp., and Cryptococcus neoformans, emphasizing their impact on immune modulation and disease progression. The emerging evidence suggests that fungal bioactive compounds, such as polysaccharides, can influence MDSC activity and restore immune balance. Notably, therapies targeting MDSCs have demonstrated promise in both fungal infections. In particular, infections with P. brasiliensis and C. neoformans show improved T-cell responses following MDSC-targeted interventions. Additionally, polysaccharides from Grifola frondosa and exposure to Aspergillus sydowii affect MDSC behavior, supporting the potential of modulating these cells therapeutically. Together, these findings highlight the relevance of MDSCs in fungal pathogenesis and underscore their potential as targets for immunotherapeutic strategies in infectious diseases. Full article