title: Relationship between an increased serum kynurenine/tryptophan ratio and atherosclerotic parameters in hemodialysis patients.
abstract: Essential amino acid tryptophan (Trp) is mainly catabolized by indoleamine 2,3-dioxygenase, which leads to the formation of kynurenine (Kyn). In this study, we reexamined whether an increased indoleamine 2,3-dioxygenase activity, as estimated by the Kyn/Trp ratio (μM/mM), is associated with atherosclerotic parameters in hemodialysis (HD) patients. Serum Trp and Kyn were measured in 243 HD patients by liquid chromatography/electrospray ionization tandem mass spectrometry. We measured carotid artery intima-medial thickness, brachial-ankle pulse wave velocity, ankle-brachial pressure index, and the cardio-ankle vascular index. Log-transformed Kyn/Trp ratio was significantly correlated with log-transformed time on HD (ρ=0.28, P<0.01), log-transformed highly sensitive C-reactive protein (ρ=0.20, P<0.01), and peripheral total lymphocyte count (ρ=-0.13, P<0.05). A significant association was found between log-transformed Kyn/Trp ratio and mean carotid artery intima-medial thickness (ρ=0.18, P<0.01). Mean carotid artery intima-medial thickness was significantly higher in the lowest quartile of Kyn/Trp ratio (<165) (0.62±0.12 mm) when compared with the highest quartile (≥304) (0.68±0.15 mm) (P<0.01). Ankle-brachial pressure index was lower in the second quartile (1.01±0.20), the third quartile (1.01±0.19), and the fourth quartile (1.03±0.15) compared with that in the first quartile (1.09±0.13) (P<0.05). It follows from these findings that the Kyn/Trp ratio increases with time on HD, and is associated with advanced atherosclerotic changes in chronic HD patients.
authors.affiliation: Division of Blood Purification, Department of Internal Medicine, Hamamatsu University School of Medicine, Shizuoka, Japan. a.kato@hama-med.ac.jp
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kato
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Takafumi
authors.initials: T
authors.lastname: Suda
authors.forename: Masako
authors.initials: M
authors.lastname: Suzuki
authors.forename: Michio
authors.initials: M
authors.lastname: Fujie
authors.forename: Takako
authors.initials: T
authors.lastname: Takita
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Furuhashi
authors.forename: Yukitaka
authors.initials: Y
authors.lastname: Maruyama
authors.forename: Kingo
authors.initials: K
authors.lastname: Chida
authors.forename: Akira
authors.initials: A
authors.lastname: Hishida
mesh_terms: D000328:Adult; D000368:Aged; D055109:Ankle Brachial Index; D050197:Atherosclerosis / Q000097:blood* / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D002339:Carotid Arteries / Q000473:pathology; D005260:Female; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000628:therapy; D007737:Kynurenine / Q000097:blood*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000009:adverse effects*; D013997:Time Factors; D014364:Tryptophan / Q000097:blood*; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000473:pathology; D055815:Young Adult
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007737:Kynurenine; D014364:Tryptophan