Clinical study on the serum peroxisome proliferater-activated receptor γ levels in patients with rheumatoid arthritis associated with osteoporosis

Objective To investigate the value of serum levels of peroxisome proliferater-activated receptor (PPAR)γ in patients with rheumatoid arthritis (RA) and to explore the associations between serum PPARγwith disease activity of RA and RA-associated osteoporosis (OP). Methods One hundred and one cases of hospitalized patients with RA were enrolled. A total of 88 normal subjects during the same period were recruited as the control group. Levels of serum PPARγ were detected by enzyme linked immunosorbent assay (ELISA). Bone mineral density (BMD) was measured by dual energy X-ray absortiometry. All the clinical and laboratory indexes of RA patients were recorded in detail. T-test (or t'-test) was used for comparison of measurement data between the two groups, non-parametric test was applied for skewed distribution data. Comparison of incidence was analyzed with χ2 test, correlation analysis was represented ascorrelation coefficient (r). Results Binary logistic regression analysis was used for multivariate regression analysis. Serum levels of PPARγ (3.38/4.00 ng/ml) in RA patients were higher than thosein normal subjects (2.63/1.76) ng/ml (Z=3.204, P=0.001). The positive rate of serum levels of PPARγ in RA was 35.6% (36/101), while the positive rate in the controls was (2.3%, 2/88, χ2=32.602, P 0.05). Serum levels of PPARγ in RA with negative RF or negative anti-CCP were higher than thosetin the RA group with positive RF or positive anti-CCP(P<0.05). Serum levels of PPARγ in RA were negatively correlated with serum RF, anti-CCP, hemoglobin (P<0.05-0.001), and positively correlated with erythrocyte sedimentation rate, platelet, BMD at sites of femur neck andWard (P<0.05-0.001). Results of binary logistic regression analysis showed that levels of serum PPARγ were protective factors in RA for OP at femurneck [OR=0.577, P=0.005, 95%CI (0.394-0.846)], and total hip [OR=0.754, P=0.033, 95%CI (0.581-0.978)]. Conclusion Serum levels of PPARγ in patients with RA are significantly increased, and negatively correlate with autoantibodies. Serum levels of PPARγ are protective factors for OP in RA. Key words: Arthritis, rheumatoid; Peroxisome proliferater-activated receptor; Osteoporosis