Bone-sparing effects of tocilizumab in rheumatoid arthritis: a monocentric observational study

Bone loss is a common feature in several autoimmune and chronic inflammatory diseases, such as rheumatoid arthritis (RA). Indeed, the high levels of pro-inflammatory cytokines seem to enhance bone resorption and to diminish bone formation, thus producing an uncoupling between osteoclast and osteoblast function and favoring the onset of juxtarticular as well as systemic osteoporosis. Many papers underline the high prevalence of osteoporosis in RA, as well as the negative correlation between interleukin 6 (IL-6) serum levels and bone mineral density (BMD). The aim of this study was to assess the effectiveness of one-year treatment with tocilizumab (TCZ), the first approved IL-6 receptor inhibitor, in reducing bone loss in RA.

We enrolled 18 patients fulfilling 2010 ACR and EULAR criteria for RA from our arthritis outpatient clinic, assessing clinical and biochemical parameters during a 12-month period. The patients received TCZ 8 mg/kg i.v. every 4 weeks and underwent dual energy X-ray absorptiometry (DXA) for the measurement of bone mineral density (BMD) at baseline and at the end of study. Serum levels of C-reactive protein (CRP), erythrocytes sedimentation rate (ESR), IL-6, serum CrossLaps, osteoprotegerin (OPG), receptor activator of nuclear factor κβ ligand (RANK-L) and dickkopf-1 (DKK-1) were measured at baseline, at 6 months and 1 year.

No significant difference in IL-6, RANK-L, DKK-1, OPG and serum CrossLaps levels between baseline, 6 months and 1 year were found. A significant increase of lumbar spine BMD was evidenced after 1 year of TCZ treatment. No difference in total body and femoral neck BMD was documented the end of the study.

This study suggest the bone-sparing effect of TCZ in RA affected individuals.