University of Brasilia Faculty of Health Sciences (UnB), Brasília, DF, Brazil.
J Bone Miner Metab. 2013 Jul;31(4):449-54. doi: 10.1007/s00774-013-0425-1. Epub 2013 Mar 21.
Recent evidence suggests that changes in plasma levels of osteopontin (OPN) may be a promising marker for early diagnosis of bone disorders. We hypothesized that a frequent OPN gene polymorphism may be useful for identifying very old individuals with alterations in plasma OPN levels and consequently at risk of abnormal bone density scores. Men and women (80 years or older) living in the Brazilian Federal District underwent assessments with dual energy X-ray absorptiometry for bone mineral density (BMD) of the femoral neck, femoral head and lumbosacral (L1 to S5) regions. Clinical inspection was performed to assess other physical traits and to exclude co-morbidities (cardiovascular, autoimmunity, infections or neoplastic diseases). Serum concentrations of OPN were determined with an enzyme-linked immunosorbent assay, whereas the A7385G polymorphism (rs1126772) was determined by direct sequencing of a polymerase chain reaction product. Among the two hundred and ten subjects enrolled, no differential scores for bone mineral density could be observed across genotypes, but a greater content of circulating OPN was found among carriers of the A allele (P ≤ 0.05) even after adjustments. Serum OPN levels were negatively correlated with femoral neck density (P = 0.050 for BMD; P = 0.032 for T scores) but not with scores of the other regions investigated. Analyses with the sample dichotomized to age and body mass revealed that this inverse relationship was noticeable only among those aged within the highest and weighing within the lowest intervals. Our findings indicate elevated circulating osteopontin levels in patients with decreased bone mineral density, consistent with a modest contribution of an OPN allelic variation to its expression. Assessing the clinical relevance of our findings demands forthcoming studies.
最近的证据表明，骨桥蛋白（OPN）的血浆水平变化可能是早期诊断骨疾病的有前途的标志物。我们假设，OPN 基因的常见多态性可能有助于识别血浆 OPN 水平改变的非常老的个体，并且因此处于异常骨密度评分的风险中。居住在巴西联邦区的男性和女性（80 岁或以上）接受了双能 X 射线吸收法（DXA）评估，以评估股骨颈、股骨头和腰椎（L1 到 S5）区域的骨矿物质密度（BMD）。进行了临床检查以评估其他身体特征并排除合并症（心血管、自身免疫、感染或肿瘤疾病）。使用酶联免疫吸附试验测定 OPN 血清浓度，而 A7385G 多态性（rs1126772）通过聚合酶链反应产物的直接测序确定。在纳入的 210 名受试者中，在各基因型之间未观察到骨矿物质密度的差异评分，但发现 A 等位基因携带者的循环 OPN 含量更高（P≤0.05），即使经过调整也是如此。血清 OPN 水平与股骨颈密度呈负相关（BMD 时 P=0.050；T 评分时 P=0.032），但与其他研究区域的评分无关。用年龄和体重分组的样本进行分析表明，这种反比关系仅在年龄最高和体重最低的人群中明显。我们的研究结果表明，骨密度降低的患者循环骨桥蛋白水平升高，与 OPN 等位基因变异对其表达的适度贡献一致。评估我们研究结果的临床相关性需要进行进一步的研究。
