Abstract
ObjectiveCirculating endothelial progenitor cells (EPCs) correlate negatively with obesity. Previous studies have shown that exercise significantly restores circulating EPC levels in obese people; however, the underlying mechanisms have not been elucidated. Recently, irisin has been reported to have a critical role in the regulation of EPCs. This exercise-induced myokine has been demonstrated to play a therapeutic role in obesity. In this study, we hypothesized that the increase in circulating irisin may form a link with increasing EPC levels in obese people after exercise.MethodsSeventeen obese adults completed an 8-week program of combined exercise and dietary intervention. Clinical characteristics, blood biochemistry, and circulating irisin levels of subjects were measured before and after eight weeks of training. EPC levels were evaluated via flow cytometry, and EPC migratory and adhesive functions were also determined.ResultsCirculating irisin levels significantly increased following the 8-week training program (P < 0.05). We furthermore observed an improvement in EPC numbers (P < 0.05), and EPC migratory and adhesive functions (P < 0.001 and P < 0.05, respectively) after the intervention. Additionally, we detected a positive correlation between changes in irisin and changes in EPC number (r = 0.52, P < 0.05).DiscussionFor the first time, a positive correlation between increasing irisin levels and increasing EPC levels has been reported after an 8-week program, consisting of exercise and dietary intervention. This result suggests a novel effect of irisin on the regulation of EPC mobilization, which might contribute to improvement of endothelial function in obese people.
Highlights
Vascular endothelial function is essential for the appropriate maintenance of cardiovascular health in humans (Ribeiro et al, 2010; Yang et al, 2007)
This study showed that circulating irisin levels had significantly increased in obese subjects after an 8-week program consisting of exercise and dietary intervention
These findings suggest that irisin may be involved in the regulation of endothelial progenitor cells (EPCs) mobilization due to lifestyle modifications that include exercise and diet
Summary
Vascular endothelial function is essential for the appropriate maintenance of cardiovascular health in humans (Ribeiro et al, 2010; Yang et al, 2007). Further studies revealed evidence in support for a decrease in both number and function of EPCs in obese participants (Heida et al, 2010; MacEneaney et al, 2009; Tobler et al, 2010) Both exercise and relevant dietary changes have independently been recognized as effective approaches to improve endothelial function (Brook, 2006; Sasaki et al, 2002; Sawyer et al, 2016; Woo et al, 2004). In subjects with the metabolic syndrome, a 12-week moderate-to-high-intensity endurance training combined with a hypocaloric Mediterranean diet produced a more pronounced increase in EPC levels than a diet-only program (Fernandez et al, 2012) This indicates that it would be an advantageous strategy to improve EPC mobilization by combining exercise and dietary intervention. In the present study, we investigated the effect of an 8-week intervention program of a combination of exercise and dietary restriction on circulating irisin concentrations, and their relationship with the change in EPC levels in an obese population. We hypothesized that the increase in circulating irisin was correlated with a corresponding increase in EPC levels in obese subjects after eight weeks of exercise and dietary intervention
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