Osteoprotegerin (OPG) and Matrix Gla protein (MGP) in rheumatoid arthritis patients: Relation to disease activity

Imbalanced Matrix Gla protein (MGP) and Osteoprotegerin (OPG) levels occur in inflammatory diseases. The aim of the present study was to evaluate serum MGP and OPG levels in Rheumatoid Arthritis (RA) patients and study their relation to the disease activity. Forty-five female RA patients and 45 age and sex-matched healthy controls were included in this study. Disease activity score 28-C-reactive protein (DAS28-CRP) was used for the assessment of disease activity. High-sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), MGP and OPG were measured in patients and controls. The associations of MGP and OPG with DAS28-CRP and the other laboratory and clinical variables were analyzed. RA patients had significantly higher serum OPG levels (408.3 ± 520.9 pg/ml) and hs-CRP (2.8 ± 1.9 mg/l) than the control (92.5 ± 86.3 pg/ml and 0.9 ± 1.5 mg/l respectively) (p < 0.001 each). There was no significant difference in MGP levels between the patients and control (p = 0.3). The correlation of OPG and MGP with DAS28-CRP in the patients was insignificant (p = 0.4 and p = 0.8 respectively). Age positively correlated with OPG (r = 0.32, p = 0.02), but not with MGP concentration (r = 0.05, p = 0.64) in the RA patients. The significant elevation of the OPG level in RA patients may through light on its possible role in the pathogenesis of this disease and could be considered as a future therapeutic target. The significant correlation with age suggests that OPG may be an important mediator especially in elderly RA cases.