Inflammatory biomarkers and physical function in older, obese adults with knee pain and self-reported osteoarthritis after intensive weight-loss therapy

OBJECTIVES: To describe the relationships between proinflammatory biomarkers and self-reported and performance-based physical function and to examine the effect of weight loss on these markers of inflammation. DESIGN: Randomized, longitudinal, clinical study comparing subjects eating an energy-restricted diet and participating in exercise training with a control group. SETTING: Community-base participants for the Physical Activity, Inflamation and Body Composition Trial. PARTICIPANTS: Eighty-seven obese (body mass index (BMI) >30.0 kg/m(2)) adults aged 60 and older with knee pain and self-report of osteoarthritis. MEASUREMENTS: Inflammatory biomarkers (interleukin 6 (IL-6), tumor necrosis factor alpha (TNF alpha), C-reactive protein, and soluble receptors for TNF alpha (sTNFR1 and sTNFR2)) and self-reported (Western Ontario and McMaster University Osteoarthritis Index questionnaire) and performance-based (6-minute walk distance and stair climb time) measures of physical function at baseline and 6 months. RESULTS: Mean (standard error of the mean) weight loss was 8.7% (0.8%) in the intervention group, compared with 0.0% (0.7%) in the control group. sTNFR1 was significantly less in the intervention group than in the control group at 6 months. sTNFR1 and sTNFR2 predicted stair climb time at baseline. Change across the 6-month intervention for sTNFR2 was an independent predictor for change in 6-minute walk distance. CONCLUSION: These results indicate that an intensive weight-loss intervention in older obese adults with knee pain can help improve inflammatory biomarkers and that changes in these concentrations showed associations with physical function.