Osteoprotegerin and bone mineral density in patients with chronic obstructive pulmonary disease

Abstract

Aim: to study a relationship between the serum level of osteoprotegerin (OPG), the markers of bone metabolism, tumor necrosis factor-α (TNF-α), and bone mineral density (BMD) in patients with chronic obstructive pulmonary disease (COPD). Subjects and methods. Fifty-five patients aged 44 to 58 years who had COPD were examined. BMD in the lumbar spine (LII-LIV) and left femoral neck (FN) was estimated by dual-energy X-ray absorptiometry (DXA) on Lunar Prodigy Densitometer (USA). The serum levels of OPG, BCrossLaps (BCL), and TNF-α were measured. A control group comprised 25 healthy non-smoking gender- and age-matched volunteers. Results. Osteopenic syndrome (T-test < -1SD) was recorded in 43 (78%) of the 55 examined patients with COPD. In 29 (52%) of them, T-test was lower in two zones towards osteoporosis in 14 (25%) towards osteopenia. In patients with COPD, TNF-α concentrations were significantly higher than that in the control group. At the same time, TNF-α levels correlated positively with the bone resorption marker BCL (r = 0.52; p = 0.042) and negatively with OPG (r = 0.56; p = 0.003). A direct correlation was established between serum OPG concentrations and BMD in both LII-LIV and FN (r = 0.56; p < 0.01 and r = 0.47; p < 0.05, respectively) Conclusion. The patients with COPD were found to have lower BMD, elevated TNF-α concentrations, an increased bone resorption marker, and lower serum OPG levels. The associations between the levels of OPG, TNF-α, and BMD suggest that these markers are implicated in the pathogenesis of osteopenic syndrome in COPD.

Keywords

• osteoporosis
• osteoprotegerin
• chronic obstructive pulmonary disease
• tumor necrosis factor-α