Endurance run increases circulating IL-6 and IL-1ra but downregulates ex vivo TNF-α and IL-1β production

We investigated whether a 6-h endurance run changes cytokine plasma concentrations and lipopolysaccharides (LPS) stimulated ex vivo production of cytokines in a whole blood culture of 19 well-trained athletes. The average distance covered was 65.1 ± 8.64 (SD) km. At the end of the exercise, the mean plasma concentration of interleukin-1-receptor agonist (IL-1ra), which was 188 pg/ml 24 h before finish, increased to 886 pg/ml (P < 0.0005). The mean plasma interleukin-6 concentration increased from 18.5 ± 4.2 to 71.5 ± 33.3 pg/ml (P < 0.0001). The increase of neutrophils correlated with the increase of IL-1ra concentrations (r = 0.58, P < 0.005). We could not detect an effect of exercise on plasma concentrations of interleukin-1β (IL-1β) or tumor necrosis factor-α (TNF-α). The ex vivo LPS-stimulated production of IL-1β in athletes 24 h before the run was significantly higher than in sedentary controls. Exercise induced a decrease of LPS-stimulated production of IL-1β and TNF-α, whereas production of IL-1ra was unchanged. These results show that prolonged exercise elicits a selective downregulation of the proinflammatory cytokine production and upregulation of the cytokines IL- 1ra and interleukin-6.