Tumour necrosis factor-related apoptosis-inducing ligand and osteoprotegerin serum levels in psoriatic arthritis

OBJECTIVES: The degree of bone loss in patients with psoriatic arthritis (PsA) has not been well-defined. We tested the hypothesis, whether serum levels of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), a pro-apoptotic cytokine and osteoprotegerin (OPG), an anti-osteoclastic cytokine, are associated with changes in biochemical markers of bone turnover or bone mineral density (BMD) in patients with PsA. METHODS: In a cross-sectional study, we evaluated biochemical markers of bone turnover, BMD and serum levels of TRAIL and OPG in 116 patients with PsA (mean age: 52+/-13 yrs). RESULTS: In patients with PsA, osteopenia was present in one-third of women and men, while osteoporosis was more frequent in men (10.2%) than in women (1.75%). Serum levels of TRAIL were significantly higher in patients with PsA (66.1+/-45.3 pmol/l) compared with controls (50.0+/-20.1 pmol/l, P<0.01), whereas OPG serum levels were not different. There were no associations between TRAIL or OPG serum levels with BMD and biochemical markers of bone turnover. However, TRAIL serum levels were associated with C-reactive protein (CRP) levels (R = 0.201, P<0.05), whereas OPG serum levels were associated with the erythrocyte sedimentation rate (R=0.215, P<0.05). CONCLUSION: In summary, BMD is decreased in one-third of patients with PsA, and predominantly men with PsA suffer from osteoporosis. While TRAIL serum levels are increased in PsA and correlated with CRP levels, neither TRAIL nor OPG serum levels are correlated with BMD or markers of bone metabolism.