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Research Paper|Volume 12, Issue 21|pp 22253—22265

The association of circulating kynurenine, a tryptophan metabolite, with frailty in older adults

Il-Young Jang1, Jin Hoon Park2, Jeoung Hee Kim2, Seungjoo Lee2, Eunju Lee1, Jin Young Lee3, So Jeong Park3, Da Ae Kim3, Mark W. Hamrick4, Beom-Jun Kim5
  • 1Division of Geriatrics, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
  • 2Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
  • 3Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
  • 4Department of Cell Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
  • 5Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
* Equal contribution
Received: May 30, 2020Accepted: September 5, 2020Published: November 13, 2020
https://doi.org/10.18632/aging.104179

Copyright © 2020 Jang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Despite the accumulating evidence from in vitro and animal experiments supporting the role of kynurenine (a tryptophan metabolite) in a number of degenerative age-related changes, the relationship between kynurenine and frailty in older adults is not well understood. We collected blood samples from 73 participants who underwent a comprehensive geriatric assessment, measuring kynurenine levels using liquid chromatography-tandem mass spectrometry. We assessed the phenotypic frailty and the deficit accumulation frailty index using widely validated approaches proposed by Fried et al. and Rockwood et al., respectively. After adjusting for sex, age, and body mass index, the frail participants presented 52.9% and 34.3% higher serum kynurenine levels than those with robustness and prefrailty, respectively (P = 0.005 and 0.014, respectively). Serum kynurenine levels were positively associated with the frailty index, time to complete 5 chair stands, and patient health questionnaire-2 score and inversely associated with grip strength and gait speed (P = 0.042 to <0.001). Furthermore, the odds ratio per increase in serum kynurenine level for phenotypic frailty was approximately 2.62 (95% confidence interval = 1.22–5.65, P = 0.014). These data provide clinical evidence that circulating kynurenine might be a potential biomarker for assessing the risk of frailty in humans.