Abstract 551: Exercise Increases Serum Level of IL-8 in Obese Subjects Accompanied by Weight Loss, Especially Reduced Body Fat Mass
Background: IL-8 is a chemokine, which recruits endothelial progenitor cells (EPCs) and induces angiogenesis. It is secreted by various cells such as skeletal muscle cells, adipocytes and monocytes in response to ischemia. On the other hand, exercise induces local ischemia and facilitates angiogenesis to improve aerobic metabolism and physical capacity. In the present study, we examined whether exercise could increase serum level of IL-8 and compared this response in obese and non-obese subjects.
Methods and Results: Fifteen non-obese active healthy volunteers and sixteen obese, sedentary volunteers, all males in their twenties, participated in this study with informed consent. Body mass index (BMI, kg/m2) was 24.1±1.1 and 27.7±0.8, respectively. In addition, waist/hip ratio and body fat mass was measured. We measured serum levels of IL-8 and VEGF at rest using enzyme-linked immunoassay before and 5 weeks after daily strenuous exercise. Exercise was comprised of anaerobic exercise with 80% of maximal workload for 1 h and aerobic exercise with 80% of VO2max for 30 min. Before exercise, the levels of IL-8 (pg/mL) and VEGF (pg/mL) were 5.1±2.8 and 162.8±94.5, respectively in the non-obese and 8.9±4.3 and 73.4±44.1 in the obese. There was no significant difference between the two groups (p=0.19 for IL-8 and p=0.096 for VEGF). After 5-week exercise, the obese group showed marked weight loss and thus their mean BMI was 25.5±0.6 (p<0.001 vs. before exercise) whereas that of non-obese group was 23.8±1.0 (p=0.06 vs. before exercise). Waist/hip ratio and body fat mass were also significantly decreased in the obese group. The IL-8 level significantly increased in the obese group (12.6±4.1, p=0.001), in contrast to the non-obese group (7.0±2.2, p=0.23). The level of VEGF, however, showed no difference after exercise in either group.
Conclusion: IL-8 was significantly increased by exercise in obese individuals compared to non-obese individuals, whereas VEGF was not altered in either group after exercise. Therefore, IL-8 may be an important exercise-induced cytokine that promotes angiogenesis and thus improves tissue perfusion and metabolism, especially in obese individuals.