Systemic Bone Metabolism and Inflammation in RA Patients Receiving TNF Inhibiting Therapy

초록

Background: Etanercept is soluble Tumor Necrosis Factor (TNF)-a receptor which is effective in suppressing inflammation in Rheumatoid Arthritis (RA). However bone metabolism is not yet known after etanercept therapy. Objective: Our aim is to assess bone metabolism along with inflammation in RA patients after etanercept treatment for 3 months and to compare bone turnover markers in RA patients with age, sex matched control group. Methods: Twenty-two patients (20 women and 2 men; age 47.05 11.87 years) with active RA were included. Etanercept was administered at standard dose, twice a week. Age and sex matched control group were recruited. Venous blood was drawn at baseline and after 12-14 weeks of etanercept use in RA patient. Bone metabolism was assessed using bone specific alkaline phosphatase (BSAP), osteoprotegerin (OPG), sclerostin for bone formation and receptor activator for nuclear factor ?B ligand (RANKL), serum c-telopeptide (CTX) for bone resorption. Serum level of inflammatory mediators including ESR, CRP, TNF- a and IL-6 were also determined. TNF RNA expression was measured by real time RT-PCR. Differences between two groups were examined by Wilkoxon signed ranks test. A p value of less than 0.05 was denoted statistically significant. Results: At baseline both serum sclerostin and CTX level was significantly lower in RA patients than in control group but sclerostin increased markedly after etanercept treatment while CTX rose marginally (Table 1). BSAP and OPG were least affected by etanercept. RANKL decreased mildly after treatment. Inflammatory mediators responded to the treatment as ESR, CRP and IL-6 all significantly decreased (Table 2). However, serum TNF- a increased to . 32 pg/mL in all RA patients after treatment and TNF RNA expression also showed concordant increase (2.04 1.38, p = 0.002). Conclusions: Our study showed significantly lower serum CTX and sclerostin level in RA patients than in control group which increased after etanercept t