Low bone density and low serum levels of soluble RANK ligand are associated with severe arterial calcification in patients with Takayasu arteritis

Objective. Takayasu arteritis (TA) is a chronic inflammatory disorder affecting the aorta and its branches. Vascular calcification has been described in 29-54% of cases of TA, although its aetiology remains unknown. Recently the osteoprotegerin/RANKL/RANK system has emerged as an important contributing factor to atherogenesis and osteogenesis. Our aim is to investigate the association between vascular calcification, bone mineral density (BMD) and the osteoprotegerin/RANK/RANKL system in TA. Methods. Thirty pre-menopausal female TA patients and 30 age- and sex-matched controls were studied. BMD was measured by dual X-ray absorptiometry. Arterial calcification in TA patients was analysed by computed tomography in thoracic and abdominal sites. Serum levels of osteoprotegerin and soluble receptor activator of nuclear factor kappa B ligand (sRANKL) were quantified by enzyme-linked immunosorbent assay. Results. Patients with severe arterial calcification showed lower BMD values than controls in lumbar spine (0.965 +/- 0.055 vs 1.126 +/- 0.153 g/cm(2), P = 0.009) and total body (0.993 +/- 0.065 vs 1.085 +/- 0.082 g/cm(2), P = 0.019). In contrast, TA patients without calcification presented BMD values similar to controls (P>0.05). Interestingly, lower serum levels of sRANKL (1.89 +/- 2.35 vs 2.80 +/- 2.23 pg/ml, P = 0.031) and a longer disease duration (12.20 +/- 6.61 vs 3.56 +/- 5.33 yr, P = 0.004) were observed in TA patients with severe calcification compared with patients without calcification. Conclusions. Severe arterial calcification in TA is associated with low values of BMD and sRANKL, reinforcing the possible link between bone and vascular disease.