Abstract
Introduction: The role of fat-bone interactions in the pathogenesis of osteoporosis in chronic obstructive pulmonary disease (COPD) is poorly understood. We investigated adipose tissue (AT) expressions of leptin and osteoprotegerin (OPG) and their relationships to osteoporosis in COPD.
Methods: In 39 patients with stable COPD, bone mineral density (BMD) and body composition was assessed by DEXA. Serum leptin and β-crosslaps were determined by electrochemiluminiscence immunoassays. Subcutaneous AT samples were analyzed using real-time PCR.
Results: Twenty-one patients without, and 18 with osteoporosis were enrolled (35 men; age 62.2±7.3 years). Compared to patients without osteoporosis, those with the disease had lower serum levels and AT expressions of leptin, and increased serum β-crosslaps (p=0.028, p=0.034, p=0.022, resp.). Log AT leptin was inversely related to serum β-crosslaps (p=0.015), and directly to leptin (p<0.001) and the total, femoral, and lumbar BMD and T-score (p<0.02 for all). AT OPG expression was related to all variables of bone density except for lumbar BMD (p<0.05 for all). Log AT leptin and OPG expressions predicted femoral T-score independently of age, gender and pulmonary function (p<0.001, R 2adj=0.383; p=0.008, R 2adj=0.301, resp.). Introducing body or fat mass index into these models eliminated independent predictive value of leptin and OPG expressions.
Conclusion: Our results suggest that adipose tissue leptin and OPG expressions are related to osteoporosis in patients with COPD, and appear to act as mediators between fat mass and BMD.
Support: APVV-0122-06, VEGA-1/0227/11 and VVGS 36/10-11.
- © 2011 ERS