ONE YEAR TREATMENT OF SUBCUTANEOUS TNF ADMINISTRATION IS NOT ENOUGH TO REVERSE SYSTEMIC BONE RESORPTION

초록

Objectives We investigated systemic bone resorption before, 6 and 12 months after subcutaneous TNF administration in seropositive RA patients. Materials and Methods Twenty-five seropositive RA patients were enrolled. They had been refractory to antirheumatic drugs and anti TNF-α therapies including etanercept and adalimumab were administrated for a year. Weekly and biweekly administration of etanercept 50mg and adalimumab 40mg were given to 11 and 14 patients, respectively. Blood sampling was done at baseline, 6 months and 1 year after the treatment. Peripheral blood mononuclear cells were cultured and number of osteoclasts was counted. Bone turnover markers including c-terminal telopeptide (CTX), bone specific alkaline phosphatase (BSALP) were measured using enzyme linked immunosorbent assay. At Baseline and after one year of treatment, bone mineral densities (BMD) were measured at baseline and one year after treatment. In addition, RA disease activity such as DAS28 and serum level of IL-6 were assessed. Results After 1 year of subcutaneous TNF treatment, number of cultured osteoclasts from peripheral blood decreased (Table 1) while RA disease activity was improving with rapid decline of serum IL-6 (Table 2). However, bone resorption pit by osteoclasts did not respond to treatment and BMD on femur and total hip declined after one year of treatment.