The relationship between maximal exercise-induced increases in serum IL-6, MPO and MMP-9 concentrations

Abstract

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-α (TNF-α), 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± 0.4kg/m 2] performed an incremental bicycle test until exhaustion, when maximal oxygen consumption was recorded. Venous blood samples were collected 30min before and 2min after exercise. There was an increase in the count of leucocytes (8.7±1.8 versus 5.7±1.3×10 9 cells per l) and IL-6 (1.24±0.17 versus 0.69±0.13pg/ml), MPO (72±7 versus 50±4ng/ml) and MPP-9 (139±9 versus 110±6ng/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.