Tumor Necrosis Factor-alpha, TNFR, And STNFR Relationships to Body Temperature

Abstract

PURPOSE: To examine the TNF-α, TNFR, and STNFR relationships to body temperature in response to in the heat. METHODS: 12 recreationally active men (24.4 ± 3.1 yrs; 181.0 ± 6.8 cm; 81.5 ± 8.0 kg; 47.2 ± 4.8 ml·kg−1·min−1) completed an exercise protocol under four conditions: 23°C/45%RH; 23°C/70%RH; 35°C/20%; and 35°C/45% RH. The protocol consisted of a 60-minute cycling trial at 60% VO2max, a 15-minute rest, and a time-to-exhaustion trial at 90% VO2max (TTE). Blood was collected before (T1) and after (T2) the 60-minute trial, and immediately after TTE (T3). Plasma concentrations of TNF-α, STNFR1, and STNFR2 were measured via ELISA. Surface expression of TNFR1 and TNFR2 on human classical (CD14++CD16–) monocytes was measured via flow cytometry (n=8). Participant’s rectal (Tre) and skin temperatures at 5 locations: Chest, Triceps, Forearm, Thigh and Calf were monitored continuously. Total skin temperature (Tsk) and whole body temperature (Twb) were calculated using weighted averages. The Area Under the Curve with respect to increase (AUCi) was then calculated for Tre, Tsk and Twb. Data were analyzed as Pearson Product Moment Correlations between AUCi for Tre, Tsk and Twb with TNF-α, TNFR, and STNFR. The time spent above specific critical temperatures for Tre (37.5, 38.0, 38.5 and 39.0°C) and Twb (35.0, 36.0, 37.0 and 38.0°C) were related to TNF-α, TNFR, and STNFR using stepwise linear regression. RESULTS: Tre was correlated with the change in STNFR1 from T1 to T3 (r= 0.307; p=0.048) and with the change in STNFR2 from T1 to T3 (r= 0.340; p=0.028). Tsk was correlated with both the change in STNFR1 from T1 to T2 (r= 0.321; p=0.038) and from T1 to T3 (r= 0.320; p=0.039); with the change in STNFR2 from T1 to T3 (r= 0.430; p=0.004); and with the change in TNF-α from T1 to T2 (r= 0.357; p=0.020). Time spent with a Tre above 38.5°C was related to the change in STNFR1 from both T1 to T2 (r= 0.837; p<0.001) and from T1 to T3 (r= 0.773; p<0.001); and to the change in TNF-α from T1 to T2 (r= 0.426; p=0.005) and from T1 to T3 (r= 0.415; p=0.006). CONCLUSION: Changes in circulating levels of TNF-α, STNFR1, and STNFR2 are influenced by rectal and whole body temperature. Classical monocyte expression of TNFR1 and TNFR2 do not appear to be influenced by rectal or whole body temperature. This investigation was partially funded by Kent State University Research Council.