Stimulation of human monocyte-derived-macrophages (MDM) with interferon gamma induces the L-tryptophan degrading enzyme indoleamine 2,3-dioxygenase (IDO). It has been well documented that the growth of some intra-cellular parasites such as Chlamydia and Toxoplasma in human fibroblasts and glioblastoma cells is inhibited by IDO mediated L-tryptophan depletion. We have recently shown that IDO induction in cord blood MDM is also responsible for the growth inhibition of extra-cellular group B streptococci and thus for the first time shown an anti-bacterial effect of IDO activation. In view of this immunological function we sought to investigate the regulation, and in particular the downregulation of IDO by the immune system. We describe here the effect of cytokines on IDO activation and in particular the inhibitory function of IL-10, TGF beta and IL-4.
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http://dx.doi.org/10.1007/978-1-4615-4709-9_66 | DOI Listing |
J Biol Chem
January 2025
Department of Chemistry, The University of Texas at San Antonio, Texas 78249, United States. Electronic address:
MarE, a heme-dependent enzyme, catalyzes a unique 2-oxindole-forming monooxygenation reaction from tryptophan metabolites. To elucidate its enzyme-substrate interaction mode, we present the first X-ray crystal structures of MarE in complex with its prime substrate, (2S,3S)-β-methyl-L-tryptophan and cyanide at 1.89 Å resolution as well as a truncated yet catalytically active version in complex with the substrate at 2.
View Article and Find Full Text PDFMol Neurobiol
January 2025
Cellular and Molecular Neurobiology and Drug Targeting Laboratory, Department of Zoology, Indira Gandhi National Tribal University, Amarkantak-484 887, MP, India.
Depression is one of the most disabling mental disorders worldwide and characterized by symptoms including worthlessness, anhedonia, sleep, and appetite disturbances. Recently, studies have suggested that tryptophan (Trp) metabolism plays a key role in depressed mood through serotonin and kynurenine pathway involving enzyme tryptophan 5-monooxygenase (TPH) and indoleamine-2,3-dioxygenase (IDO) respectively. Moreover, during neuroinflammation, IDO is activated by proinflammatory cytokines and affects neurogenesis, cognition, disturbed hypothalamic-pituitary-adrenal (HPA) axis, and gut homeostasis by altering the gut bacteria and its metabolites like Trp derivatives.
View Article and Find Full Text PDFCancer Biol Ther
December 2025
Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA.
Adaptive immune resistance in cancer describes the various mechanisms by which tumors adapt to evade anti-tumor immune responses. IFN-γ induction of programmed death-ligand 1 (PD-L1) was the first defined and validated adaptive immune resistance mechanism. The endoplasmic reticulum (ER) is central to adaptive immune resistance as immune modulatory secreted and integral membrane proteins are dependent on ER.
View Article and Find Full Text PDFJ Biomol Struct Dyn
January 2025
Department of Biotechnology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
Tryptophan catabolism is a central pathway in many cancers, serving to sustain an immunosuppressive microenvironment. The key enzymes involved in this tryptophan metabolism such as indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO) are reported as promising novel targets in cancer immunotherapy. IDO1 and TDO overexpression in TNBC cells promote resistance to cell death, proliferation, invasion, and metastasis.
View Article and Find Full Text PDFStem Cell Res Ther
January 2025
Gonçalo Moniz Institute, Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Brazil.
Background: Despite many years of investigation into mesenchymal stem cells (MSCs) and their potential for treating inflammatory conditions such as COVID-19, clinical outcomes remain variable due to factors like donor variability, different tissue sources, and diversity within MSC populations. Variations in MSCs' secretory and proliferation profiles, and their proteomic and transcriptional characteristics significantly influence their therapeutic potency, highlighting the need for enhanced characterization methods to better predict their efficacy. This study aimed to evaluate the biological characteristics of MSCs from different tissue origins, selecting the most promising line for further validation in a K18-hACE2 mouse model of SARS-CoV-2 infection.
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