title: Direct measurement of cell-free DNA from serially collected capillary plasma during incremental exercise.
abstract: To investigate the kinetics of cell-free DNA (cfDNA) due to exercise, we established a direct real-time PCR for the quantification of cfDNA from unpurified capillary plasma by amplification of a 90- and a 222-bp multilocus L1PA2 sequence. Twenty-six male athletes performed an incremental treadmill test. For cfDNA measurement, capillary samples were collected serially from the fingertip preexercise, during, and several times postexercise. Venous blood was drawn before and immediately after exercise to compare capillary and venous cfDNA values. To elucidate the strongest association of cfDNA accumulations with either cardiorespiratory or metabolic function during exercise, capillary cfDNA values were correlated with standard measures like heart rate, oxygen consumption, or lactate concentrations. The venous cfDNA concentrations were significantly higher compared with the capillary plasma, but in both fractions cfDNA increased 9.8-fold and the values correlated significantly (r = 0.796). During incremental treadmill running, the capillary cfDNA concentrations increased nearly parallel to the lactate values. The values correlated best with heart rate and energy expenditure, followed by oxygen consumption, Borg values, and lactate levels (0.710 ≤ r ≥ 0.808). With this article, we present a sensitive procedure for the direct quantification of cfDNA in unpurified capillary plasma instead of purified venous plasma. Further studies should investigate the differences between capillary and venous cfDNA that might mirror different physiological mechanisms. Enhanced cardiorespiratory function during exercise might lead to the accumulation of cfDNA via the release of stress hormones that already increase at intensities below the anaerobic threshold. Furthermore, cfDNA might be released by neutrophil extracellular traps.
authors.affiliation: Department of Sports Medicine, Rehabilitation and Prevention, Johannes Gutenberg-University Mainz, Mainz, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Breitbach
authors.affiliation: Department of Sports Medicine, Rehabilitation and Prevention, Johannes Gutenberg-University Mainz, Mainz, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Sterzing
authors.affiliation: Department of Sports Medicine, Rehabilitation and Prevention, Johannes Gutenberg-University Mainz, Mainz, Germany.
authors.forename: Carlos
authors.initials: C
authors.lastname: Magallanes
authors.affiliation: Department of Sports Medicine, Rehabilitation and Prevention, Johannes Gutenberg-University Mainz, Mainz, Germany.
authors.forename: Suzan
authors.initials: S
authors.lastname: Tug
authors.affiliation: Department of Sports Medicine, Rehabilitation and Prevention, Johannes Gutenberg-University Mainz, Mainz, Germany simonpe@uni-mainz.de.
authors.forename: Perikles
authors.initials: P
authors.lastname: Simon
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D002196:Capillaries / Q000378:metabolism*; D002319:Cardiovascular System / Q000378:metabolism; D002474:Cell-Free System / Q000378:metabolism*; D004247:DNA / Q000097:blood*; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000378:metabolism; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012420:Running / Q000502:physiology; D055815:Young Adult
chemical_list: D007773:Lactates; D004247:DNA
keywords: capillary blood; cell-free DNA; direct quantitative real-time PCR; incremental treadmill test; plasma DNA