Buzi F, Maccarinelli G, Guaragni B, Ruggeri F, Radetti G, Meini A, Mazzolari E, Cocchi D
Department of Paediatrics, University of Brescia, Brescia, Italy.
Clin Endocrinol (Oxf). 2004 Jan;60(1):87-91. doi: 10.1111/j.1365-2265.2004.01951.x.
Osteoprotegerin (OPG) is a secreted member of the TNF receptor superfamily. OPG is made by osteoblastic cells and is expressed in a wide variety of cell and tissue types. It acts as a decoy receptor by binding the receptor activator of nuclear factors kB (RANKL) and preventing RANKL-induced osteoclast formation and differentiation. Numerous cytokines and hormones (TGF-beta, PTH, vitamin D, glucocorticoids and oestrogens) exert their effects on osteoclastogenesis by regulating the production of OPG.
In the present study we compared serum OPG and RANKL concentrations in a group of normal children (1-14 years old) with those of pair-aged children affected by different diseases [Turner's syndrome (TS), early/precocious puberty (PP) and rheumatoid arthritis (RA)]. OPG and RANKL concentrations were measured by an enzyme immunoassay method using a commercial kit.
Mean (+/- SD) OPG level in normal children was 4.05 +/- 1.63 pmol/l with no difference between males and females. OPG values in children 1-4 years old (5.87 +/- 2.22 pmol/l) were significantly higher than in children 4-14 years old (3.55 +/- 0.97 pmol/l). OPG levels in children with RA were significantly higher than in controls (6.33 +/- 2.57 pmol/l vs. 4.05 +/- 1.63 pmol/l, P < 0.01); patients with TS or PP had OPG levels superimposable to those of controls (2.61 +/- 0.67 pmol/l and 3.99 +/- 0.85 pmol/l, respectively), but in TS OPG levels were significantly lower than in age-matched females. Mean RANKL concentration in normal subjects was 0.81 +/- 1.55 pmol/l; there was a slight decline in RANKL levels with age. RANKL concentrations in subjects with TS, PP, RA and controls did not differ significantly, and did not differ from those published in adult normal subjects.
It appears from our data that OPG serum levels in healthy children aged > 4 years are similar to those present in young adult men, with higher levels in the first 4 years of life. Although the meaning of the alterations of OPG levels observed in pathological conditions is still obscure, they appear potentially interesting in view of a key role played by this protein in bone homeostasis.
骨保护素（OPG）是肿瘤坏死因子受体超家族的一个分泌成员。OPG由成骨细胞产生，在多种细胞和组织类型中表达。它通过结合核因子κB受体激活剂（RANKL）发挥诱饵受体的作用，阻止RANKL诱导的破骨细胞形成和分化。许多细胞因子和激素（转化生长因子-β、甲状旁腺激素、维生素D、糖皮质激素和雌激素）通过调节OPG的产生对破骨细胞生成发挥作用。
在本研究中，我们比较了一组正常儿童（1至14岁）与患有不同疾病（特纳综合征（TS）、性早熟（PP）和类风湿关节炎（RA））的配对年龄儿童的血清OPG和RANKL浓度。使用商业试剂盒通过酶免疫测定法测量OPG和RANKL浓度。
正常儿童的平均（±标准差）OPG水平为4.05±1.63 pmol/l，男性和女性之间无差异。1至4岁儿童的OPG值（5.87±2.22 pmol/l）显著高于4至14岁儿童（3.55±0.97 pmol/l）。RA患儿的OPG水平显著高于对照组（6.33±2.57 pmol/l对4.05±1.63 pmol/l，P<0.01）；TS或PP患者的OPG水平与对照组相当（分别为2.61±0.67 pmol/l和3.99±0.85 pmol/l），但TS患者的OPG水平显著低于年龄匹配的女性。正常受试者的平均RANKL浓度为0.81±
