Osteoprotegerin plasma concentrations correlate with severity of peripheral artery disease

Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor family, is involved in the process of bone turnover and also in the pathogenesis of osteoporosis and premature calcification of the vascular system. In the present study on patients with peripheral artery disease (PAD), we correlated plasma OPG concentrations with severity of disease and the presence of cardiovascular risk factors.

Sixty-seven consecutive inpatients (26 females; mean age 70 years (S.D.: 12), undergoing percutaneous transluminal angioplasty (PTA) because of advanced symptomatic PAD of the lower extremities were studied. Severity grade of disease (clinical stage after "Fontaine", functional measurements in terms of the ankle brachial index (ABI) and "Bollinger score" of angiographies), biochemical parameters and a detailed cardiovascular risk profile were documented. Fasting plasma concentrations of OPG were measured by a commercial sandwich enzyme immunoassay.

The mean plasma concentrations of OPG were 5.3 pmol/l (S.D.: 3.3). Plasma OPG concentrations in subjects with PAD, clinical stages III-IV (n=15) were 7.9 pmol/l (S.D.: 5.3) and were significantly higher than in patients without ischemic ulcerations (n=52; 4.6 pmol/l; S.D.: 2.0; p<0.01). The mean value of Bollinger score was 29.1 (S.D.: 19.8). OPG was positively correlated with Bollinger score of disease (r=0.31; p<0.02), age (r=0.58; p<0.01) and creatinine-values (r=0.32; p<0.01) and negatively correlated with ABI (r=-0.39; p<0.03).

In patients with PAD, plasma OPG concentrations were significantly higher in subjects with ischemic ulcerations than in those without and were positively correlated with higher severity grade of disease, age and creatinine-values. Further studies are required to analyze the role of OPG as a diagnostic marker for severity of atherosclerotic disease and to assess a possible therapeutic potential as "vasculoprotegerin".