Exercise Improves Insulin Sensitivity in the Absence of Changes in Cytokines

Abstract

Purpose. The benefits of aerobic exercise training on insulin sensitivity in subjects with the metabolic syndrome (MetS) are, at least in part, associated with changes in cytokines. Recent studies identified novel cytokines (e.g. fractalkine, omentin and osteopontin) that are strongly involved in glucose homeostasis and therefore potentially contribute in the exercise-induced changes in insulin sensitivity. Therefore, we aim to examine changes in skeletal muscle RNA expression and plasma levels of novel cytokines after exercise training, and correlate these changes to the exercise-induced changes in insulin sensitivity. Methods. Women with the metabolic syndrome (MetS, n=11) and healthy women (n=10) participated in a 6-month aerobic exercise training intervention (3/week, 45min per session at 65%-85% of individual heart rate reserve). Before and after training, we examined insulin sensitivity (M-value during hyperinsulinemic euglycaemic clamp), circulating blood levels of cytokines (venous blood sample; leptin, adiponectin, omentin, fraktalkin, osteopontin). Skeletal muscle RNA-expression of these cytokines (muscle biopsy) was examined in two subgroups (MetS n=6; healthy women n=6). Results. At baseline, plasma levels of omentin (85.8±26.2ng/ml) and adiponectin (5.0±1.7μg/ml) levels were significantly higher in controls compared to MetS (51.1±27.1; 3.6±1.1 respectively), and leptin levels were lower in controls (18.7±11.5ng/ml vs 53.0±23.5).M-value was significantly higher in controls (8.1±1.9mg/kg/min) than in MetS (4.0±1.7).Exercise training significantly improved M-values in both groups (P<0.01). Exercise training did not alter plasma and skeletal muscle RNA-expression levels of cytokines, whilst no correlation was observed between changes in cytokine level/RNA-expression and M-values (P>0.05). Conclusion. Whilst exercise training successfully improves insulin sensitivity in MetS andhealthy women, we found no change in plasma and mRNA expression levels of novel cytokines.

Influence of a Concurrent Exercise Training Intervention during Pregnancy on Maternal and Arterial and Venous Cord Serum Cytokines: The GESTAFIT Project

“…When focusing on the changes in maternal serum cytokines from baseline to 34th week and delivery, exercise showed a non-significant but clinically meaningful [43] association with greater IL-8 and IL-10, and lower IFN-γ and TNF-α levels in maternal serum at the 34th week; and with lower maternal IL-1β and higher maternal IL-10 at delivery.Fractalkine (CX3CL1) is a chemokine with an important role in the fetal-placental vasculature development [44] and microglial cell migration-activation [45]. When considering its role as a myokine [14], previous studies have suggested that physical exercise is not related to either fractalkine mRNA nor to protein concentrations in the general population, which is in agreement with our results [14,16,46]. However, these findings cannot be directly compared as there are no previous similar studies on fractalkine in pregnant women.Besides its pro-inflammatory role [1,3], muscle-derived IL-8 (CXCL8) can also act as an angiogenic factor during early and late gestation [15].…”

Improvements in fitness are not obligatory for exercise training-induced improvements in CV risk factors

“…, ; Verheggen et al. ) involving a total of 166 subjects with a priori increased cardiovascular risk.…”

“…Smokers were also excluded. In total, we collected data from 10 endurance training studies (Walsh et al 1985Maiorana et al 2001Maiorana et al , 2002Thijssen et al 2006;Oudegeest-Sander et al 2013;Scholten et al 2014;Schreuder et al 2014Schreuder et al , 2015Verheggen et al 2016b) involving a total of 166 subjects with a priori increased cardiovascular risk.…”

Circulating Omentin-1, Insulin Resistance and Lipid Profile Responses Following 8-weeks Aerobic Training Intervention Among Smokers Vs. Non-smokers

“…Recent evidence have implicated that the possible role of omentin-1 in the pathophysiology of obesity and insulin resistance [8]. The omentin-1 circulating levels are inversely related to insulin resistance and are decreased in obesity, as well as type 2diabetes [9]. Ansari et al [10] newly reported decrease in omentin-1 serum level among smokers as a metabolic risk factor and as a major prognostic agent of lung cancer in these individuals.…”

“…Exercise training is an important non-pharmacological strategy to improve insulin sensitivity via several metabolic/physiological changes [9]. Since, regular exercise training diminishes the risk factors for metabolic diseases such as obesity, type 2diabetes, and cardiovascular disease [12], may modify circulating omentin-1 level.…”