The Relationship Between Maximal Exercise-Induced Increases in Serum IL-6, MPO and MMP-9 Concentrations

The aim of this study was to test the hypothesis that exercise would induce inflammatory response characterized by increased pro-inflammatory cytokines interleukin-6 (IL-6) and tumour necrosis factor-a (TNF-a), adhesion molecule, matrix metalloprotease-9 (MMP-9) and myeloperoxidase (MPO) levels. Additional aim was to elucidate the possible source of maximal exercise-induced increase in MMP-9 concentration. To examine our hypothesis, 26 professional male ice hockey players [age 25 +/- 1 (mean +/- SEM) years; BMI 25.8 +/- 0.4 kg/m2] performed an incremental bicycle test until exhaustion, when maximal oxygen consumption was recorded. Venous blood samples were collected 30 min before and 2 min after exercise. There was an increase in the count of leucocytes (8.7 +/- 1.8 versus 5.7 +/- 1.3 x 10(9) cells per l) and IL-6 (1.24 +/- 0.17 versus 0.69 +/- 0.13 pg/ml), MPO (72 +/- 7 versus 50 +/- 4 ng/ml) and MPP-9 (139 +/- 9 versus 110 +/- 6 ng/ml) concentrations (P < 0.05) comparing post- and pre-exercise levels. Maximal exercise-induced increase in MPO correlated with the increases in IL-6 (P < 0.05, R = 0.54) and MMP-9 (P < 0.01, R = 0.62) concentrations. Furthermore, increase in IL-6 correlated with the increase in MMP-9 concentrations (P < 0.05, R = 0.60). Maximal exercise induces an inflammatory response characterized by leucocytosis and increased IL-6, MPO and MMP-9 concentrations. Correlations between increased MPO (marker of neutrophils degranulation) and both increased IL-6 and MMP-9 concentrations may suggest that neutrophils could be the main source of these inflammatory biomarkers during maximal exercise. Furthermore, correlation between increases in serum IL-6 and MMP-9 concentrations may suggest that IL-6 could exert modulatory effects on MMP-9 release during maximal exercise.