Immunological factors, bone and lean tissue status in patients with rheumatoid arthritis

Osteoporosis (OP) and sarcopenia are common complications of rheumatoid arthritis (RA). The bone and muscle tissue status may be related to the activity of various immunological factors. Aim of the study was to investigate the association between immunological factors and the bone and lean tissue status in women with RA. Material and methods. The study included 163 postmenopausal women with confirmed RA (age 61.0 [52.0; 66.0] years, median [lower quartile; upper quartile]). A clinical and laboratory examination was performed including dual-energy X-ray absorptiometry to assess bone mineral density (BMD) and lean mass. The levels of C-reactive protein, rheumatoid factor, antibodies to cyclic citrullinated peptide, myostatin, follistatin, IL-6, IL-6 receptors, insulin-like growth factor 1, adiponectin, leptin, fibroblast growth factor 23, tumor necrosis factor SF12 and sclerostin in blood serum were determined. Results. Persons with OP had higher level of sclerostin compared to those without it ( р < 0.001). In sarcopenic patients IL 6, rIL 6, and sclerostin contents were lower ( p = 0.038, p = 0.040, and p = 0.003, respectively), and insulin-like growth factor 1 concentration was higher ( p = 0.014) than in those without sarcopenia. Multivariate linear regression revealed an independent positive association of sclerostin level with lumbar spine and femoral neck BMD (β = 0.28, p = 0.017 and β = 0.25, p = 0.028, respectively) and a negative association of adiponectin level with total and appendicular lean mass (β = –0.21, p = 0.045 and β = –0.25, p = 0.036, respectively) and appendicular lean mass index (β = –.30, p = 0.041). Conclusions. In women with RA, BMD correlates with sclerostin level, and muscle mass – with adiponectin content. The effect of various cytokines on BMD and lean mass in patients with RA requires further study.