12-week combined strength and endurance exercise attenuates CD8+ T-cell differentiation and affects the kynurenine pathway in the elderly: a randomized controlled trial

Abstract

AbstractBackgroundAge-related accumulation of highly differentiated CD8+effector memory re-expressing CD45RA (EMRA) T-cells and disruption of the kynurenine (KYN) pathway are associated with chronic inflammation and the development of insulin resistance.In this study the aim was to investigate the effects of 12-week combined strength and endurance exercise on CD8+T-cell differentiation and KYN pathway metabolites. Ninety-six elderly subjects (f/m, aged 50—70) were randomized to a control (CON) or exercise (EX) group. The EX group completed combined strength and endurance training twice weekly for one hour each time at an intensity of 60% of the one-repetition maximum for strength exercises and a perceived exertion of 15/20 for endurance exercises. The EX group was also randomly subdivided into two groups with or without a concomitant balanced diet intervention in order to examine additional effects besides exercise alone. Before and after the intervention phase, the proportions of CD8+T-cell subsets and levels of KYN pathway metabolites in peripheral blood were determined.ResultsThe CD8+EMRA T-cell subsets increased in the CON group but remained almost unchanged in the EX group (p = .02). Plasma levels of kynurenic acid (KA) increased in the EX group and decreased in the CON group (p = .03). Concomitant nutritional intervention resulted in lower levels of quinolinic acid (QA) compared with exercise alone (p = .03). Overall, there was a slight increase in the QA/KA ratio in the CON group, whereas it decreased in the EX group (p > .05).ConclusionsCombined strength and endurance training seems to be a suitable approach to attenuate CD8+T-cell differentiation in the elderly and to redirect the KYN pathway towards KA. The clinical relevance of these effects needs further investigation.