No changes observed in Circulating Tumor Necrosis Factor‐alpha or receptors following Prolonged Exercise in a Cold Environment

Abstract

Tumor Necrosis Factor‐alpha (TNF‐α) is a pro‐inflammatory cytokine that is known to increase during exercise in the heat, however, has not been examined in a cold environment.OBJECTIVEThe purpose of this study was to examine the circulating concentration of TNF‐α and the corresponding expression of TNF‐receptor 1 and 2 (TNFr1 and TNFr2) on classical monocytes following aerobic exercise in a cold environment.METHODSSeven recreationally active men (25.0 ± 3.2 yrs; 1.82 ± 0.06 m; 85.3 ± 7.6 kg; 4.04 ± 0.40 L·min−1) completed three experimental visits: a VO2max test, and cycling in 5°C (LT) and 23°C (MT) in a counterbalanced fashion. Cycling consisted of 60 minutes at 60% of their previously determined VO2max (TC60), and a time to exhaustion trial at 90% of their VO2max (TTE). Rectal core temperature was monitored and recorded continuously, while blood samples were taken prior to exercise (PRE), at TC60, TTE and after one hour of recovery (REC). Samples were analyzed for circulating TNF‐α via ELISA, while a subset of participants (n=4) were assessed for TNFr1 and TNFr2 expression on classical monocytes (CD14++/CD16−) via flow cytometry. Non‐normally distributed data were LN transformed, and area under the curve (AUC) was calculated via the trapezoidal method. Data were analyzed using a within‐subjects repeated measures ANOVA, and a paired samples t‐test. Data are presented as mean ± SD.RESULTSNo significant interaction (F = 0.811, p = 0.504, η2p = 0.119) nor main effects of time (F = 0.670, p = 0.581, η2p = 0.100) or trial (F = 4.093, p = 0.090, η2p = 0.406) were observed for circulating TNF‐α concentration. Additionally, no significant difference was observed between trials for TNF‐α AUC (p = 0.083). No significant interaction (F = 0.811, p = 0.519, η2p = 0.213), nor main effects of time (F = 1.144, p = 0.383, η2p = 0.276) or trial (F = 0.303, p = 0.621, η2p = 0.092) were observed for TNFr1. No significant difference was observed between trials for TNFr1 AUC (p = 0.117). No significant interaction (F = 0.196, p = 0.896, η2p = 0.061), nor main effects of time (F = 0.974, p = 0.447, η2p = 0.245) or trial (F = 0.320, p = 0.611, η2p = 0.096) were observed for TNFr2. Additionally, no differences were observed between trials for TNFr2 AUC (p= 0.236).CONCLUSIONSNeither 60 minutes of moderate intensity exercise, nor exercise to exhaustion at a high intensity were sufficient to induce a response in circulating TNF‐α, nor classical monocyte expression of TNFr1 or TNFr2. Furthermore, exercise in the cold does not appear to modify this response.Support or Funding InformationThis study was partially funded by the Kent State University Research Council.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.