Exercise, Weight Loss, and Effects on Inflammation

Effects of total and regional fat loss on plasma CRP and IL-6 in overweight and obese, older adults with knee osteoarthritis

OBJECTIVE

To describe associations between total and regional body fat mass loss and reduction of systemic levels of inflammation (C-reactive protein (CRP) and interleukin-6 (IL-6)) in obese, older adults with osteoarthritis (OA), undergoing intentional weight loss.

DESIGN

Data come from a single-blind, 18-month, randomized controlled trial in adults (age: 65.6 ± 6.2; Body mass index (BMI): 33.6 ± 3.7) with knee OA. Participants were randomized to diet-induced weight loss plus exercise (D + E; n = 150), diet-induced weight loss-only (D; n = 149), or exercise-only (E; n = 151). Total body and region-specific (abdomen and thigh) fat mass were measured at baseline and 18 months. High-sensitivity CRP and IL-6 were measured at baseline, six and 18 months. Intervention effects were assessed using mixed models and associations between inflammation and adiposity were compared using logistic and mixed linear regression models.

RESULTS

Intentional total body fat mass reduction was associated with significant reductions in log-adjusted CRP (β = 0.06 (95% CI = 0.04, 0.08) mg/L) and IL-6 (β = 0.02 (95% CI = 0.01, 0.04) pg/mL). Loss of abdominal fat volume was also associated with reduced inflammation, independent of total body fat mass; although models containing measures of total adiposity yielded the best fit. The odds of achieving clinically desirable levels of CRP (<3.0 mg/L) and IL-6 (<2.5 pg/mL) were 3.8 (95% CI = 1.6, 8.9) and 2.2 (95% CI = 1.1, 4.6), respectively, with 5% total weight and fat mass loss.

CONCLUSIONS

Achievement of clinically desirable levels of CRP and IL-6 more than double with intentional 5% loss of total body weight and fat mass. Global, rather than regional, measures of adiposity are better predictors of change in inflammatory burden.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00381290.

Pro-inflammatory cytokines as predictors of antidepressant effects of exercise in major depressive disorder

Exercise is an efficacious treatment for major depressive disorder (MDD) and has independently been shown to have anti-inflammatory effects in non-depressed subjects. Patients with MDD have elevated inflammatory cytokines but it is not known if exercise affects inflammation in MDD patients and whether these changes are clinically relevant. In the TReatment with Exercise Augmentation for Depression (TREAD) study, participants who were partial responders to a selective serotonin reuptake inhibitor were randomized to receive one of two doses of exercise: 16 kilocalories per kilogram of body weight per week (KKW), or 4 KKW for 12 weeks. Blood samples were collected before initiation and again at the end of the 12-week exercise intervention. Serum was analyzed using a multiplexed ELISA for interferon-γ (IFN-γ), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Higher baseline levels of TNF-α were associated with greater decrease in depression symptoms over the 12-week exercise period (P<0.0001). In addition, a significant positive correlation between change in IL-1β and change in depression symptom scores was observed (P=0.04). There were no significant changes in mean level of any cytokine following the 12-week intervention, and no significant relationship between exercise dose and change in mean cytokine level. Results suggest that high TNF-α may differentially predict better outcomes with exercise treatment as opposed to antidepressant medications for which high TNF-α is linked to poor response. Our results also confirm findings from studies of antidepressant medications that tie decreasing IL-1β to positive depression treatment outcomes.

Independent and combined effects of physical activity and weight loss on inflammatory biomarkers in overweight and obese older adults

OBJECTIVES

To determine the independent effect of long-term physical activity (PA) and the combined effects of long-term PA and weight loss (WL) on inflammation in overweight and obese older adults.

DESIGN

Eighteen-month randomized, controlled trial.

SETTING

The community infrastructure of cooperative extension centers.

PARTICIPANTS

Overweight and obese (body mass index >28.0 kg/m(2) ) community-dwelling men and women aged 60 to 79 at risk for cardiovascular disease (CVD).

INTERVENTION

Physical activity + weight loss (PA + WL) (n = 98), PA only (n = 97), or successful aging (SA) health education (n = 93) intervention.

MEASUREMENTS

Biomarkers of inflammation (adiponectin, leptin, high-sensitivity interleukin (hsIL)-6, IL-6sR, IL-8, and soluble tumor necrosis factor receptor 1) were measured at baseline and 6 and 18 months.

RESULTS

After adjustment for baseline biomarker, wave, sex, and visit, leptin and hsIL-6 showed a significant intervention effect. Specifically, leptin was significantly lower in the PA + WL group (21.3 ng/mL, 95% confidence interval (CI) = 19.7-22.9 ng/mL) than in the PA (29.3 ng/mL, 95% CI = 26.9-31.8 ng/mL) or SA (30.3 ng/mL, 95% CI = 27.9-32.8 ng/mL) group (both P < .001), and hsIL-6 was significantly lower in the PA + WL group (2.1 pg/mL, 95% CI = 1.9-2.3 pg/mL) than in the PA (2.5 pg/mL, 95% CI = 2.3-2.7 pg/mL) or SA (2.4 pg/mL, 95% CI = 2.2-2.6 pg/mL) group (P = .02).

CONCLUSION

Addition of dietary-induced WL to PA reduced leptin and hsIL-6 more than PA alone and more than a SA intervention in older adults at risk for CVD. Results suggest that WL, rather than increased PA, is the lifestyle factor primarily responsible for improvement in the inflammatory profile.