Obesity potentially protects against systemic bone loss in patients with rheumatoid arthritis treated with tumour necrosis factor inhibitors

초록

Objective We aimed to investigate how systemic bone metabolism was affected after 1 year of treatment with tumour necrosis factor (TNF) inhibitors in rheumatoid arthritis (RA) patients. Methods A total of 29 seropositive RA patients not treated for osteoporosis were enrolled and TNF inhibitors were administered for a year. Bone mineral density (BMD) at the lumbar spine, femur neck, and total hip was measured at baseline and 12 months after anti-TNF treatment. Blood samples were collected at baseline and 6 and 12 months after anti-TNF treatment and osteoclasts were cultured on hone slices. Weight was the strongest factor influencing systemic bone loss. Patients were categorised into two groups: obese (body mass index (BM!) >= 25 kg/m(2)) and non-obese (BM! <25 kg/m(2)). Results All patients showed decreased BMD at all sites. The obese group showed relatively little change in BMD, although the non-obese group showed significant decreases in BMD at all sites after 1 year of treatment with TNF inhibitors. Resorption pits created by osteoclasts decreased at 6 months and increased at 12 months in the non-obese group, while the obese group presented with steadily decreasing sizes of resorption pits at all-time points. Levels of receptor activator of nuclear factor kappa B ligand were significantly decreased at 12 months compared to baseline in the obese group, while they were increased in the non-obese group. Conclusion One year of treatment with TNF inhibitors failed to halt systemic bone loss in RA patients, but obesity may have protective effects against bone loss.

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