RELATIONSHIP OF LEPTIN TO PHYSICAL FUNCTION AND INFLAMMATORY BIOMARKERS IN OLDER OBESE ADULTS WITH KNEE OSTEOARTHRITIS

Leptin may be involved in the inflammatory process as significant associations have been observed between leptin and inflammatory biomarkers. Both osteoarthritis (OA) and obesity are recognized as inflammatory conditions, and declines in physical function and onset of frailty in older adults are associated with chronic inflammation. PURPOSE To examine the associations between leptin, physical function, and inflammatory biomarkers in older overweight and obese adults with knee OA. METHODS Older (> 60 yrs; mean = 68.6 yrs) overweight and obese (mean Body Mass Index = 34.3 kg/m2) adults with radiographic evidence of knee osteoarthritis (n = 309) completed a 6 min walk test and self-reported physical function questionnaire (Western Ontario MacMaster University OA Index-WOMAC). Blood was drawn in the morning after a 12-hr fast at baseline for analysis of leptin and inflammatory biomarkers (CRP, IL-6, IL-6 soluble receptor, TNFα, and TNFα soluble receptors, TNFαsR1 & TNFαsR2). A linear model (reported as β) was used to assess the relationship between plasma leptin with both physical function and inflammatory biomarkers adjusted for age, gender, and BMI. RESULTS There was an association between p-leptin and WOMAC function (β = 0.114;p = 0.039) and stiffness (β = 0.152;p = 0.039) subscales, but not with 6 min walk distance. There were strong positive Spearman correlations between p-leptin and CRP (r = 0.16;p < 0.01), TNFαsR1 (r = 0.27;p < 0.01), and TNFαsR2 (r = 0.23;p < 0.01). CONCLUSION These results indicate that higher leptin concentrations are related to impairments in self-reported measures of physical function and some inflammatory biomarkers, independent of age, gender and BMI, in older adults with knee OA. Supported by Claude D. Pepper Older Americans Grant 5P60AG10484-00 and General Clinical Research Center Grant M01-RR07122.