title: Expression of the Kynurenine Pathway in Human Peripheral Blood Mononuclear Cells: Implications for Inflammatory and Neurodegenerative Disease.
abstract: The kynurenine pathway is a fundamental mechanism of immunosuppression and peripheral tolerance. It is increasingly recognized as playing a major role in the pathogenesis of a wide variety of inflammatory, neurodegenerative and malignant disorders. However, the temporal dynamics of kynurenine pathway activation and metabolite production in human immune cells is currently unknown. Here we report the novel use of flow cytometry, combined with ultra high-performance liquid chromatography and gas chromatography-mass spectrometry, to sensitively quantify the intracellular expression of three key kynurenine pathway enzymes and the main kynurenine pathway metabolites in a time-course study. This is the first study to show that up-regulation of indoleamine 2,3-dioxygenase (IDO-1), kynurenine 3-monoxygenase (KMO) and quinolinate phosphoribosyltransferase (QPRT) is lacking in lymphocytes treated with interferon gamma. In contrast, peripheral monocytes showed a significant elevation of kynurenine pathway enzymes and metabolites when treated with interferon gamma. Expression of IDO-1, KMO and QPRT correlated significantly with activation of the kynurenine pathway (kynurenine:tryptophan ratio), quinolinic acid concentration and production of the monocyte derived, pro-inflammatory immune response marker: neopterin. Our results also describe an original and sensitive methodological approach to quantify kynurenine pathway enzyme expression in cells. This has revealed further insights into the potential role of these enzymes in disease processes.
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia; St Vincent's Clinical School, Faculty of Medicine, UNSW, Sydney, Australia.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Jones
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia.
authors.forename: Nunzio F
authors.initials: NF
authors.lastname: Franco
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia.
authors.forename: Bianca
authors.initials: B
authors.lastname: Varney
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia.
authors.forename: Gayathri
authors.initials: G
authors.lastname: Sundaram
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia; St Vincent's Clinical School, Faculty of Medicine, UNSW, Sydney, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Brown
authors.affiliation: Neuroinflammation group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
authors.forename: Josien
authors.initials: J
authors.lastname: de Bie
authors.affiliation: Neuroinflammation group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
authors.forename: Chai K
authors.initials: CK
authors.lastname: Lim
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia; Neuroinflammation group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
authors.forename: Gilles J
authors.initials: GJ
authors.lastname: Guillemin
authors.affiliation: Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia; St Vincent's Clinical School, Faculty of Medicine, UNSW, Sydney, Australia; Department of Neurology, St Vincent's Hospital, Sydney, Australia.
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Brew
mesh_terms: D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000096:biosynthesis*; D007737:Kynurenine / Q000378:metabolism*; D050601:Kynurenine 3-Monooxygenase / Q000096:biosynthesis*; D007963:Leukocytes, Mononuclear / Q000378:metabolism* / Q000473:pathology; D008297:Male; D019636:Neurodegenerative Diseases / Q000378:metabolism* / Q000473:pathology; D015854:Up-Regulation
chemical_list: C576710:IDO1 protein, human; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007737:Kynurenine; D050601:Kynurenine 3-Monooxygenase