Concurrent high-intensity aerobic and resistance exercise modulates systemic release of alarmins (HMGB1, S100A8/A9, HSP70) and inflammatory biomarkers in healthy young men: a pilot study

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background: </jats:bold>Intense exercise is a systemic stressor associated with the release of “danger” molecules – alarmins, by damaged or dying cells into systemic circulation to evoke a sterile inflammatory response. Compared with research in clinical diseases, physiological responses of alarmins to exercise and training are not well studied. Short-term responses to exercise and training using a panel of alarmins – HMGB1, S100A8/A9, HSP70 and sRAGE may reveal unique aspects of stress responses to strenuous exercise with important ramifications when prescribing exercise to generally healthy adults. <jats:bold>Methods: </jats:bold>A 3-week, high-intensity training program was performed by healthy young men (N = 7). Concurrent aerobic and resistance exercises were performed on 3 consecutive days each week. Blood and saliva were collected before (<jats:italic>Pre</jats:italic>), immediately after (<jats:italic>Post</jats:italic>), and 30 min (<jats:italic>30 min</jats:italic>) after exercise each week, and 24 h after the final exercise session in week 3 (<jats:italic>24 h</jats:italic>). <jats:bold>Results: </jats:bold>Plasma HMGB1, S100A8/A9 and HSP70 increased from <jats:italic>Pre</jats:italic> to <jats:italic>Post </jats:italic>(P < 0.05)<jats:italic>,</jats:italic> although at different timepoints during the study, and displayed different kinetics from IL-10, IL-8 and IFN-γ, suggesting unique mechanisms involved in modulating their release and clearance. CD14<jats:sup>+</jats:sup>CD16<jats:sup>-</jats:sup> monocytes increased from <jats:italic>Pre </jats:italic>to <jats:italic>Post </jats:italic>across 3 weeks; CD14<jats:sup>+</jats:sup>CD16<jats:sup>+</jats:sup> monocytes increased from <jats:italic>Pre </jats:italic>to <jats:italic>Post </jats:italic>in<jats:italic> </jats:italic>week 2 and 3 (P < 0.05).<jats:italic> </jats:italic>ΔHMGB1 and ΔHSP70 correlated positively with ΔMCP-1 during 3 weeks of training, while ΔHMGB1 correlated positively with CD14<jats:sup>+</jats:sup>CD16<jats:sup>- </jats:sup>monocytes, suggesting higher alarmin release after strenuous exercise may involve increase in circulating monocytes. <jats:bold>Conclusions: </jats:bold>Perturbations in systemic alarmins are novel biological signatures for assessing the inflammatory milieu of healthy adults during high-intensity exercise.</jats:p>