The role of the receptor activator of nuclear factor-kappaB ligand/osteoprotegerin cytokine system in primary hyperparathyroidism

CONTEXT: The mechanisms of action of PTH on bone in vivo remain incompletely understood. The objective of this investigation was to examine changes in serum levels of receptor activator of nuclear factor-kappaB ligand and osteoprotegerin (OPG) in primary hyperparathyroidism and their relationship to bone loss. PATIENTS AND METHODS: Twenty-nine patients with primary hyperparathyroidism had baseline circulating soluble receptor activator of nuclear factor-kappaB ligand (sRANKL) and OPG measured. The relationship to biochemical markers of bone turnover and changes in bone mineral density over 2 yr was examined. RESULTS: Baseline sRANKL levels were elevated (1.7+/-0.1 pmol/liter), whereas OPG remained in the normal range (5.6+/-0.4 pmol/liter). Circulating sRANKL did not correlate with PTH but did correlate with markers of bone resorption (urine deoxypyridinoline cross-links: r=0.51, P<0.01; serum N-telopeptide of type I collagen: r=0.37, P<0.05). Furthermore, sRANKL correlated with both IL-6 and IL-6 soluble receptor (IL-6sR) (r=0.47, P<0.05 and r=0.55, P<0.005, respectively). Serum sRANKL levels also correlated with bone loss at the total femur (r=-0.53, P<0.01). Lastly, a high value of sRANKL in combination with values of IL-6 and IL-6sR in the upper quartile (sRANKL>or=1.81 pg/ml, IL -6>or=11.8 pg/ml, and IL-6sR>or=45.6 ng/ml) defined a group of four women with significantly greater rates of bone loss at the total femur than the remaining patients (-2.7+/-1.7% vs. +0.5+/-0.3%; n=4 vs. n=19, P<0.05). CONCLUSION: Determination of circulating levels of sRANKL may be useful in identifying patients with mild primary hyperparathyroidism at greater risk for bone loss. The fact that circulating sRANKL did not correlate with PTH but did correlate with markers of bone resorption suggests that skeletal responsiveness to PTH may differ in this disease.     

Relationship between RANKL and neuroendocrine activation in elderly males with heart failure

The main cytokines regulating bone remodeling are the receptor activator of nuclear factor-κB ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG). Recent data have linked RANKL and OPG to cardiovascular disease as well. NT-pro-BNP and adiponectin are well-established biomarkers of heart failure reflecting neuroendocrine activation in this multi-complex disorder. The objective of this article was to investigate whether RANKL is associated with neuroendocrine activation in 75 elderly males with mild to moderate congestive heart failure (CHF) and left ventricular ejection fraction <40%. The control group consisted of 20 healthy male volunteers with matching age and body mass index (BMI). Serum RANKL (sRANKL), OPG, NT-pro-BNP, adiponectin, leptin, clinical, and echocardiography parameters were evaluated. In comparison to the control group, the CHF patients showed significantly increased sRANKL levels [126.8 (122.6) vs. 47.8 (44.4) pg/ml, P < 0.0001]. There was a significant relative risk of systolic CHF in elderly males associated with increased sRANKL above the calculated cut-off of 83 pg/ml [OR = 10.286 (95%CI 3.079-34.356), P < 0.0001; RR = 3.600 (95%CI = 1.482-8.747)]. In the CHF patients, the log-transformed values of sRANKL levels correlated positively with the log-transformed values of the serum NT-pro-BNP and adiponectin levels (P = 0.004, r = 0.326 and P = 0.037, r = 0. 241, respectively), while inversely correlated with the BMI and creatinine clearance (P = 0.015, r = -0.281 and P = 0.042, r = -0.236, respectively). In multivariate regression model, sRANKL was a significant determinant of NT-pro-BNP independent of age, BMI and creatinine clearance (P = 0.002, R (2) = 0.546). In conclusion, our study suggests that in elderly males with systolic heart failure sRANKL was significantly associated with parameters of neuroendocrine activation such as NT-pro-BNP and adiponectin. Further studies are needed to elucidate the potential role of sRANKL in the complex pathogenesis of heart failure.     

Circulating osteoprotegerin and soluble RANK ligand in systemic sclerosis

OBJECTIVE: .Microvascular damage is an early pathogenetic event in systemic sclerosis (SSc). The receptor activator of nuclear factor-kappaB ligand (RANKL)/RANK/osteoprotegerin (OPG) system is involved in vascular biology. Our aim was to assess OPG and soluble RANKL (sRANKL) serum levels in patients with SSc and healthy controls. METHODS: Sixty patients with SSc (median age 58, range 31-72 yrs) and 60 healthy subjects matched for age, sex, and menopausal status were recruited. Serum OPG, sRANKL, soluble vascular cell adhesion molecule (sVCAM; marker of endothelial activation/injury), and bone turnover markers were measured. Bone mineral density in patients was assessed and cardiovascular/coronary risk was estimated. RESULTS: OPG was similar in the 2 groups, while sRANKL and sRANKL/OPG ratio was higher in patients (p = 0.01 for both). sVCAM was markedly higher in patients (p < 0.001). OPG levels correlated positively with age in both patients (Spearman R = 0.50, p < 0.001) and controls (R = 0.56, p < 0.001). In patients, OPG was lower in men and higher in those with active ulcers or calcinosis. sRANKL levels were higher in patients treated with platelet aggregation inhibitors, and correlated negatively with densitometric measures. 25-hydroxyvitamin D levels were significantly lower in patients (p < 0.001). In patients, OPG levels correlated positively with cardiovascular and coronary risk (R = 0.28, p = 0.05 and R = 0.34, p < 0.01, respectively) and were higher in patients with hypertension and left ventricular hypertrophy. sVCAM levels correlated positively with cardiovascular and coronary risk (R = 0.27, p = 0.06, and R = 0.38, p < 0.01, respectively). CONCLUSION: Higher sRANKL levels and sRANKL/OPG ratio in patients with SSc are likely to be a consequence of altered bone microenvironment. We show a dissociation between the well established marker of endothelial activation/injury, sVCAM, and the alleged marker of vascular damage, OPG, in patients with SSc. Further studies are needed to better ascertain the relationships of the RANKL/RANK/OPG system with the progression of macro- and microvascular damage.     

Effects of oral contraceptives on circulating osteoprotegerin and soluble RANK ligand serum levels in healthy young women

OBJECTIVE: Osteoprotegerin (OPG) represents a secreted cytokine which regulates bone mass by blocking receptor activator of nuclear factor-kappaB ligand (RANKL), the principal regulator of osteoclast function. In vitro, OPG production is upregulated by oestrogens in osteoblastic lineage cells, a mechanism that has been discussed as a protective paracrine mechanism of oestrogens on the skeleton. To define the effects of oestrogens on the RANKL/OPG system in vivo, we evaluated OPG and both free and total soluble RANKL (sRANKL) serum levels in healthy young women with or without oral contraceptives. DESIGN AND PATIENTS: Serum levels of OPG and sRANKL were prospectively assessed in a cohort of healthy young women with (n = 30) or without (n = 25) combined oestrogen-progestin-based oral contraceptives. MEASUREMENTS: OPG, total and free sRANKL serum levels were determined by enzyme-linked immunosorbent assays (ELISA). RESULTS: In women using oral contraceptives, OPG serum levels were significantly higher (2.71 +/- 1.42 pmol/l) compared to nonusers (1.35 +/- 1.02 pmol/l; P = 0.0003), whereas free (P = 0.55) and total (P = 0.24) sRANKL serum levels did not differ between both groups. This resulted in an increased OPG/free sRANKL ratio (P = 0.02) in women on oral contraceptives. During the ovarian cycle, OPG (P = 0.22) and free sRANKL (P = 0.99) serum levels remained unchanged in women without oral contraceptives (n = 19), while total sRANKL levels were higher in the follicular than in the luteal phase (P = 0.02). CONCLUSIONS: Intake of oral contraceptives is associated with increased OPG serum levels, but not sRANKL levels, resulting in a higher OPG/sRANKL ratio. This may contribute to the positive effects of oral contraceptives on the skeleton.     

Effects of the phytoestrogen genistein on the circulating soluble receptor activator of nuclear factor kappaB ligand-osteoprotegerin system in early postmenopausal women

We investigated the serum levels of both receptor activator of nuclear factor kappaB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG) in postmenopausal healthy women after a 1-yr therapy with genistein, (n = 30; 54 mg/d), hormone replacement therapy (n = 30; 1 mg/d 17beta-estradiol combined with norethisterone acetate) and placebo (n = 30). By comparison with placebo, the soluble RANKL (sRANKL)/OPG ratio was lower in the genistein group (-69 +/- 7%; P < 0.01 vs. placebo 81 +/- 24%) and in hormone replacement therapy-treated women (-11 +/- 2%; P < 0.01 vs. placebo). A positive correlation (r = 0.63; P < 0.01) was found between 1-yr percentage change in sRANKL/OPG ratio and 1-yr change in urinary deoxypyridinoline, a bone resorption marker. A negative correlation was observed between 1-yr percentage change in sRANKL/OPG ratio and 1-yr change in femoral neck bone mineral density (r = -0.7; P < 0.01). Our findings suggest that the sRANKL-OPG system may mediate the beneficial effects of genistein on bone remodeling in postmenopausal women.     

强直性脊柱炎外周血破骨细胞前体细胞活性的研究

目的 研究强直性脊柱炎(AS)患者外周血破骨细胞前体细胞(OCP)的数量及其与血清核因子(NF)-κB受体活化因子配体(RANKL)和骨保护素(OPG)浓度以及与病情活动性的相关性.方法 采用RANKL和巨噬细胞集落刺激因子(M-CSF)体外诱导8例As患者和5名健康对照的外周血培养破骨细胞(OC).应用组织化学染色法对OC中抗酒石酸酸性磷酸酶(TRAP)染色.计数染色阳性胞核≥3个的细胞.骨吸收实验考察OC的功能.运用酶联免疫吸附试验(ELISA)法检测23例As患者和17名健康对照血清RANKL和OPG水平.对AS疾病活动性进行评估包括Bath强直性脊柱炎疾病活动指数(BASDAI)、红细胞沉降率(ESR)、C反应蛋白(CRP).对AS患者OCP数量与血清RANKUOPG比值及与病情活动性进行相关分析.统计分析采用t检验t'检验、Spearman相关分析.结果 ①As组外周血生成OC数量显著高于健康对照组(10.9±3.4与6.2±1.3,P<0.05);②AS组血清RANKL浓度、OPG浓度、RANKL/OPG比值显著高于健康对照组[(5.4±3.8)pg/ml与(1.6±0.8)pg/ml,(157±49)pg,ml与(105±20)pg/ml,0.037±0.026与0.016±0.008,P均<0.01)];③外周血生成OC数量与RANKL、RANKL/OPG比值呈正相关(r=0.692, P=0.009;r=0.813,P=0.001);④AS患者血清OPG浓度与BASDAI呈负相关(r=-0.444,P=0.044),血清RANKL浓度与BASDAI呈正相关(r=0.543,P=0.011),RANKL/OPG比值与BASI)AI呈正相关(r=0.672,R=0.001).结论 ①As患者外周血OCP数量显著增高,与关节骨质破坏程度密切相关可能是造成关节骨质破坏的机制;②AS患者OC活性增高的机制可能是炎症引起RANKL产量增多,RANKUOPG比值升高所致.     

Serum osteoprotegerin is increased in Crohn's disease: a population-based case control study

BACKGROUND: There is a potential interface between osteoporosis and the chronic inflammation of inflammatory bowel disease (IBD), and the osteoprotegerin (OPG)/receptor for activated nuclear factor-kappaB (RANK)/RANK ligand (RANKL) signaling pathway may be an important mediator, although data are limited. METHODS: We conducted a population-based case-control seroassay study to look for alterations in serum OPG and soluble RANKL (sRANKL). The study population included IBD patients who were 18 to 50 years old with Crohn's disease (CD; n = 287) or ulcerative colitis (UC; n = 166), age-matched healthy controls (n = 368), and nonaffected siblings of IBD patients (n = 146). Serum OPG and sRANKL were measured by enzyme-linked immunoassay. Sex-specific reference ranges were derived from the healthy controls. RESULTS: Analysis of variance (ANOVA) confirmed significant group differences in women for mean serum OPG (P = 0.018). CD women had higher values of OPG than UC women (P = 0.028) or healthy controls (P = 0.045), whereas the other groups were similar. OPG levels were above the reference range in 13/173 (8%) of CD women, exceeding the expected proportion (P = 0.032). In contrast, no differences in OPG were seen in men between controls, CD, or UC. Estrogen use in women (P = 0.000002) and corticosteroid use in men (P = 0.026) were associated with higher OPG levels. In multivariate analysis, CD diagnosis (P = 0.031) and estrogen use (P = 0.000002) were independently associated with higher OPG levels. No group differences were seen in mean serum sRANKL measurements. CONCLUSIONS: An OPG:sRANKL imbalance with OPG exceeding sRANKL should inhibit osteoclastogenesis and promote bone formation. CD is associated with increased fracture risk, and possibly, the paradoxically higher OPG is a counterregulatory response to factors such as inflammatory cytokines, promoting high bone turnover. Alternatively, elevated OPG in CD may reflect T-cell activation.     

OPG inhibits gene expression of RANK and CAII in mouse osteoclast-like cell

This study was designed to determine the effects of the osteoprotegerin (OPG) on the mRNA expression of carbonic anhydrase II (CAII) and the receptor activator of NF-??B (RANK) in mouse osteoclast-like cells. Marrow cells were harvested from femora and tibiae of mouse and cultured in 6-well chamber slides. After 1?day of incubation, the marrow cells were exposed to M-CSF (25?ng/ml), RANKL (50?ng/ml), and different concentrations of OPG (50, 75, and 100?ng/ml, respectively) for 3?days. Osteoclast-like cells were confirmed by both tartrate-resistant acid phosphatase (TRAP) stain and bone resorption assay. The expression of RANK and CAIImRNA was determined with real-time fluorescent quantitative polymerase chain reaction. The numbers of multinucleated, TRAP-positive osteoclast-like cells, and resorption pits formed were observed. Compared with the M-CSF?+?RANKL group, RANKmRNA expression was statistically decreased in the M-CSF and M-CSF?+?RANKL?+?OPG (100?ng/ml) groups (P?=?0.004, P?=?0.024, respectively); Compared with the M-CSF, M-CSF?+?RANKL, and M-CSF?+?RANKL?+?OPG (100?ng/ml) group, CAIImRNA expression in the M-CSF?+?RANKL?+?OPG (75?ng/ml) groups was statistically decreased (P?=?0.001, P?=?0.008, and P?=?0.036, respectively). These data suggest that OPG could regulate the expression of RANK and CA II mRNA in the marrow culture system.     

Increased osteoprotegerin levels in Cushing's syndrome are associated with an adverse cardiovascular risk profile

CONTEXT: Patients with Cushing's syndrome (CS) have a mortality rate four times higher than age- and sex-matched subjects, mainly due to cardiovascular events. Serum osteoprotegerin (OPG) levels are increased in patients with cardiovascular disease and/or excess bone resorption. OBJECTIVE: The aim of the study was to assess serum OPG and soluble receptor activator of nuclear factor-kappaB ligand (sRANKL) levels in CS and their possible relationship with coronary risk profile. DESIGN AND SETTING: We conducted a cross-sectional study at a tertiary referral center. PATIENTS: We studied 48 adult patients with CS and 48 age- and sex-matched controls. Twenty-six patients had pituitary-dependent CS; five patients had CS caused by ectopic ACTH secretion; and 17 patients had adrenal-dependent CS, accounted for by cortisol-secreting adenoma (n = 9), ACTH-independent macronodular bilateral adrenal hyperplasia (n = 4), or World Health Organization stage II cortisol-secreting carcinoma (n = 4). Patients underwent assessment of the absolute coronary risk and measurement of bone mineral density by dual-energy x-ray absorptiometry. Serum OPG and total sRANKL were measured by ELISA. RESULTS: Serum OPG (but not sRANKL) levels were significantly higher in CS patients than in controls (P < 0.01). In patients, serum OPG showed a positive correlation with age (r = 0.36; P = 0.01). OPG levels were higher in patients with the metabolic syndrome [median, 1262 (range, 199-2306) pg/ml vs. 867 (412-2479) pg/ml; P = 0.03], and showed a positive correlation with the absolute coronary risk (r = 0.36; P = 0.01). Serum OPG levels were higher in patients with pituitary-dependent CS in comparison with adrenal-dependent CS. CONCLUSIONS: In patients with CS, serum OPG levels are increased and appear to be associated with coronary risk.     

20～75岁妇女血清护骨素、核因子-κB受体活化子配体的变化与年龄、停经、骨生化指标和骨密度的关系

目的　研究血清护骨素 (OPG)和核因子 κB受体活化子配体 (RANKL)与年龄、停经、骨生化指标和骨密度的关系 ,了解影响血清OPG和RANKL的因素。方法　在 5 0 4例 2 0～ 75岁的绝经前和绝经后妇女中 ,以双能X线吸收仪测定腰椎和股骨各处骨密度。按WHO标准 ,将绝经后妇女分为骨量正常、骨量减少和骨质疏松 3组。测定血清骨钙素 (BGP)、尿Ⅰ型胶原交联N端肽 (NTx)、血清OPG和RANKL ,计算RANKL/OPG比值。结果　年龄与血清OPG正相关 (r =0 4 4 2 ,P <0 0 0 1) ,与血清RANKL负相关 (r=- 0 2 6 3,P <0 0 0 1)。绝经后妇女的血清OPG(10 7 6± 3 0 )ng/L明显高于绝经前妇女 (72 0± 1 8)ng/L ,而血清RANKL(4 7± 0 4 )ng/L显著低于绝经前妇女 (5 8± 0 3)ng/L。校正年龄、停经年限和体重指数后 ,血清OPG、RANKL与腰椎和股骨各处骨密度无相关性。血清OPG与尿NTx/肌酐正相关 ;血清RANKL与血清BGP负相关。血清OPG和RANKL在绝经后骨质疏松组、骨量减少组和正常骨量组间差异无显著性。多元逐步回归分析显示 ,年龄、停经年限和骨转换指标是决定血清OPG RANKL系统的独立因素。结论　随年龄而升高的血清OPG可能是人体对抗绝经后骨吸收加快的一个代偿性反应 ,随年龄而下降的血清RANKL可能有益于恢复绝经后妇女的骨     

Effect of hormone replacement therapy on nitric oxide bioactivity and monocyte chemoattractant protein-1 levels.

BACKGROUND: Vascular inflammation plays an important role in the pathogenesis of atherosclerosis. We investigated the effect of hormone replacement therapy (HRT) on vasomotor function and monocyte chemoattractant protein (MCP)-1 levels, an important serological marker of inflammation. METHODS: We administered micronized progesterone (MP) 200 mg for 10 days with conjugated equine estrogen (CEE) 0.625 mg for 25 days and remaining 5 days off cyclically during 2 months to 20 healthy postmenopausal women (PMW). We measured NO bioactivity and plasma levels of MCP-1 before and after HRT in 20 PMW. And we measured plasma levels of MCP-1 in each 20 subjects of premenopausal women, men <50, and men >50 years, respectively. RESULTS: MP combined with CEE significantly improved the percent flow-mediated dilator response to hyperemia relative to baseline measurements (P<0.001). PMW receiving HRT had lower levels of MCP-1 than those not receiving HRT (121+/-38 versus 146+/-44 pg/ml, P<0.001). In all comparisons, subjects with high estrogen status had significantly lower MCP-1 levels than subjects with low estrogen status (P<0.001 by ANOVA). Premenopausal women had lower levels of MCP-1 than men of a similar age (106+/-14 versus 164+/-40 pg/ml, P<0.001). PMW not receiving HRT had similar levels of MCP-1 compared with men of a similar age (146+/-44 versus 143+/-29 pg/ml, P=0.816). Premenopausal women had markedly lower levels of MCP-1 than PMW not receiving HRT (106+/-14 versus 146+/-44 pg/ml, P=0.001). PMW receiving HRT had similar levels of MCP-1 compared with premenopausal women (121+/-38 versus 106+/-14 pg/ml, P=0.323). CONCLUSION: These findings might provide at least a partial explanation for the protection against cardiovascular disease experienced by premenopausal women, and the loss of that protection following menopause.     

血液透析患者骨保护素细胞核因子кB受体活化因子配体与动脉僵硬度的关系

目的探讨血液透析患者颈-股脉搏波速度(CFPWV)和颈-桡脉搏波速度(CRPWV)的变化及与骨保护素(OPG)、细胞核因子кB受体活化因子配体(sRANKL)系统的关系。方法对北京大学人民医院血液净化中心2006年6—10月40例血液透析患者采用酶联免疫吸附法测定血清OPG、sRANKL,PWV测定仪测定外周动脉僵硬度,X线平片检测腹主动脉、股动脉及桡动脉部位血管钙化,计算血管钙化积分。结果 25例(64.1%)患者存在不同程度的血管钙化,中重度钙化者较轻度钙化者血清OPG高[(342.50±171.53)ng/L对(206.21±137.88)ng/L,P=0.025]、OPG/sRANKL比值高(454.65±455.63比135.31±136.81,P=0.035),sRANKL比较差异无统计学意义[(0.10±0.08)pmol/L对(0.12±0.08)pmol/L]。血液透析患者CRPWV及CFPWV均较对照组增高,差异有统计学意义[(9.48±1.80)m/s对(8.58±1.29)m/s,P=0.043]和[(13.42±3.26)m/s对(10.07±1.76)m/s,P<0.01]。血OPG较对照组高[(235.12±154.33)ng/L对(93.00±44.10)ng/L,P=0.01],sRANKL两组比较,差异无统计学意义[(0.12±0.08)pmol/L对(0.16±0.08)pmol/L]。相关分析发现CRPWV与舒张压、sRANKL呈正相关(r=0.389、0.349,P=0.025、0.040),控制年龄、血压因素后CRPWV仍然与sRANKL呈正相关(r=0.381,P=0.029)。多元线性回归分析显示血磷、sRANKL及钙磷乘积是CRPWV的独立影响因素,年龄是CFPWV的独立影响因素。结论血液透析患者外周动脉僵硬度增加,sRANKL独立于年龄和血压影响血液透析患者动脉僵硬度。     

Regulatory Effect of Parathyroid Hormone on sRANKL-Osteoprotegerin in Hemodialysis Patients With Renal Bone Disease

Abstract: Receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin are newly identified molecules that contribute to the modulation of bone remodeling. RANKL activates osteoclast function by binding to RANK in either a soluble or membrane-bound form, whereas osteoprotegerin (OPG) neutralizes its effects. The aim of this study is the evaluation of soluble RANKL (sRANKL)-OPG in cohorts of hemodialysis patients and the establishment of possible correlations between their serum levels and those of other biochemical markers. We measured intact parathyroid hormone (iPTH), osteocalcin (OC), OPG, alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP) and sRANKL in 104 hemodialysis patients. The patients were studied as a whole and in two subgroups according to their bone turnover state. In patients with low serum levels of bone turnover markers (intact parathyroid hormone [iPTH] < 100 pg/mL, ALP < 100 U/L, TRAP < 4U/L; 33 patients), the following correlations were found: (i) positive correlations of iPTH with RANKL (r = 0.394, P = 0.023) and RANKL/OPG ratio (r = 0.49, P = 0.004); (ii) a negative correlation between iPTH and OPG (r = −0.365, P = 0.037). The subgroup of patients with normal or high serum levels of bone turnover markers (iPTH ≥ 150 pg/mL, ALP ≥ 100U/L, OC ≥ 40 ng/mL; 19 patients) exhibited the following significant correlations: (i) a positive correlation between OPG and iPTH serum level (r = 0.649, P = 0.003); and (ii) a negative correlation between RANKL/OPG ratio and iPTH (r = −0.464, P = 0.045). In conclusion, the observation that PTH favors RANKL and inhibits OPG production was only demonstrated in the serum of hemodialysis patients in a low turnover state. The positive correlation between serum OPG and iPTH in normal or high turnover rates implies a homeostatic mechanism to limit bone resorption, probably associated with skeletal resistance to PTH.     

特发性肺动脉高压患者血清骨保护素及其受体的变化及临床意义

目的探讨特发性肺动脉高压（idiopathic pulmonary arterial hypertension,IPAH）患者肺动脉压力和血清骨保护素（osteoprotegerin,OPG）及其受体（核因子-κβ受体活化因子配体,RANKL）水平的关系及临床意义。方法纳入IPAH患者28例,同期纳入性别和年龄匹配的健康体检者28例作为对照组。采用酶联免疫吸附法（ELISA）检测所有入组人员血清OPG/RANKL水平、N末端脑钠肽前体（NT-proBNP）水平;对IPAH组患者采用右心漂浮导管测定肺动脉压力的水平,并对肺动脉压和OPG/RANKL水平进行相关性分析。结果与正常对照组相比,IPAH患者血清中OPG、RANKL和NT-proBNP水平均更高[OPG：（190.91±43.39）pg/mL vs.（122.59±41.20）pg/mL;RANKL：（194.05±50.31）pg/mL vs.（117.73±39.89）pg/mL;NT-proBNP：（1894.78±591.97）pg/mL vs.（224.18±60.11）pg/mL],差异均有统计学意义（P＜0.05）。直线相关分析显示血清中OPG/RANKL水平和肺动脉压力呈正相关,相关系数分别为r=0.525（P＜0.05）和r=0.419（P＜0.05）。结论骨保护素及其受体轴（OPG/RANKL）可能参与肺动脉高压的形成,且与肺动脉压力有一定的相关性。     

The RANKL/OPG system is activated in inflammatory bowel disease and relates to the state of bone loss

BACKGROUND AND AIMS: A substantial proportion of patients with inflammatory bowel disease (IBD) develops osteopenia and osteoporosis in the course of disease. Recent data from a mouse model of colitis suggest that the receptor activator of nuclear factor kappa B (RANKL)/osteoprotegerin (OPG) system may be responsible for bone loss. METHODS: We investigated the activation state of the RANKL/OPG system and its association with bone loss in human IBD. Plasma levels of OPG and RANKL were correlated with bone mineral density and current IBD therapy. Colonic secretion of OPG and RANKL and cell types responsible for such secretion were determined. RESULTS: OPG plasma levels were elevated 2.4-fold in Crohn's disease (CD) and 1.9-fold in ulcerative colitis (UC) whereas soluble RANKL (sRANKL) levels were not significantly different in IBD patients compared with healthy controls. High levels of OPG were released from colonic explant cultures (CEC) derived from inflamed IBD specimens, and colonic macrophages and dendritic cells costained for OPG. sRANKL levels from CEC were low both in IBD patients and healthy controls. Interestingly, increased expression of RANKL was mainly confined to cells in the lamina muscularis. A significant negative correlation was found between OPG plasma levels and femoral neck/lumbar spine bone mineral density. CONCLUSIONS: We have demonstrated that IBD is associated with alterations in the RANKL/OPG system. Applying results from a murine model of colitis associated bone loss, the constellation of OPG and sRANKL regulation observed in our study raises the possibility that RANKL/OPG may contribute to the development of bone loss in IBD.     

Soluble Receptor Activator of Nuclear Factor-κB Ligand (sRANKL)/Osteoprotegerin Balance in Ageing and Age-Associated Diseases

Recently, novel members of the TNF/TNF receptor superfamily, receptor activator of nuclear factor- kappa B ligand (RANKL), its receptor RANK, and the decoy receptor osteoprotegerin (OPG), have been identified as paracrine mediators of both the immune system and bone functions. The balance of RANK/RANK-L and OPG is critical for osteoclastogenesis modulation and physiological bone remodeling. In order to evaluate whether RANKL/OPG balance is modified by ageing, we analyzed, by imunoassay, systemic levels of OPG and sRANKL in healthy elderly subjects (age range from 70 to over 90 years) and in patients affected by two age-related diseases, osteoarthritis (OA) and polymyalgia rheumatica (PMR), characterized by bone metabolism alteration and involvement of the immune system. We demonstrated that (a) plasma concentrations of OPG increased significantly with age; (b) conversely, sRANKL significantly declined in the group of subjects aged between 81 and 90 years, being similar to the young controls in the other age groups; (c) in OA and PMR, circulating OPG did not differ from plasma levels found in age-matched control groups, while sRANKL concentration was significantly increased compared to controls. Hence, in ageing, the sRANKL/OPG system appears to be modified, with prominent changes in circulating OPG levels; in OA and PMR, the sRANKL/OPG balance alteration was shown to be mainly due to the increase of plasma sRANKL concentration.     

The RANKL/OPG system and bone mineral density in patients with chronic liver disease

BACKGROUND/AIMS: Osteopenia and osteoporosis are common complications of chronic liver disease (CLD). Receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) regulate osteoclastogenesis and bone remodelling, and are involved in several inflammatory diseases. This study investigated the activation state of the RANKL/OPG system and its association with bone loss in CLD. METHODS: Serum levels of OPG and sRANKL were determined in 193 patients with CLD and 56 age- and gender-matched healthy controls. Cellular sources of OPG and RANKL were determined immunohistochemically. Dual-energy x-ray absorptiometry was performed to determine bone mineral density (BMD) of lumbar spine and femoral neck. RESULTS: sRANKL serum levels were significantly elevated in non-cirrhotic, but not cirrhotic patients compared to healthy controls. OPG serum levels were elevated 1.6-fold in non-cirrhotic and 2.8-fold in cirrhotic CLD patients. RANKL+ cells were mainly confined to portal fields, while OPG was broadly expressed. In the cirrhotic subgroup (87 patients) we observed a significantly higher OPG/sRANKL ratio in patients with osteopenia or osteoporosis of the lumbar spine and femoral neck region (T-score < -1) compared to those with normal BMD (T-score > or = -1). CONCLUSIONS: CLD is associated with alterations in RANKL/OPG serum levels, which could modulate bone loss in CLD.     

Does osteoprotegerin or receptor activator of nuclear factor-kappaB ligand mediate the association between bone and coronary artery calcification?

CONTEXT: Accumulating evidence indicates that vascular and bone mineralization may be related, although the exact mechanism remains unknown. OBJECTIVE: Our objective was to investigate whether an observed inverse association between bone mineral density (BMD) and coronary artery calcification (CAC) in postmenopausal women currently taking estrogen therapy is mediated by osteoprotegerin (OPG) or receptor activator of nuclear factor-kappaB ligand (RANKL). DESIGN: Participants were 92 postmenopausal women (aged 58-81 yr) taking estrogen therapy who had hip and spine BMD assessed by dual-energy x-ray absorptiometry and CAC measured by electron-beam computed tomography in 1998-2002 and serum RANKL and OPG levels measured in samples collected in 1997-1999. Total CAC score was dichotomized as none/minimal (10). RESULTS: OPG serum levels were higher in women who had some CAC compared with those who had none/minimal (126.8 +/- 1.08 vs. 102.9 +/- 1.07 pg/ml, respectively, P = 0.03); these differences became nonsignificant after adjustment for age and other risk factors (P = 0.51). A 1 sd increase in hip BMD was associated with significantly lower odds of having CAC > 10 (odds ratio = 0.52; 95% confidence interval = 0.29-0.93) independent of age, fat-free mass, high-density lipoprotein cholesterol, current smoking, and use of cholesterol-lowering medications. Other skeletal sites demonstrated a similar pattern. Addition of RANKL and/or OPG to the model had minimal effect on the magnitude or statistical significance of the BMD-CAC association. Additionally, a test of interaction indicated that RANKL and OPG are not significant effect modifiers. CONCLUSIONS: Serum OPG and RANKL do not account for the observed association between bone and coronary artery calcification among postmenopausal women using hormone therapy.     

The relationship between circulating osteoprotegerin levels and bone mineral metabolism in healthy women

OBJECTIVE: Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the RANK ligand. Moreover, OPG has been shown to be an important inhibitor of osteoclastogenesis in animal models. However, the relationship between circulating OPG levels and female bone status in human populations is unclear. In this study we undertook to investigate the relationship between circulating OPG levels and bone mineral metabolism in healthy women. PATIENTS AND MEASUREMENTS: Our subjects were 287 women aged 37-73 years (mean age 51.5 years). The serum concentrations of OPG were determined by enzyme-linked immunosorbent assay (ELISA). The biochemical markers of bone turnover and FSH were measured using standard methods. Bone mineral densities at the lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry. RESULTS: Postmenopausal women had a significantly higher mean value of serum OPG than premenopausal women (1358.5 +/- 32.5 pg/ml vs. 1228.8 +/- 33.3 pg/ml, P < 0.01). Serum OPG levels were positively correlated with age (r = 0.169, P < 0.01), as were urine deoxypyridinoline levels (r = 0.133, P < 0.05) and serum FSH levels (r = 0.187, P < 0.01) in a bivariate correlation analyses. In a multiple regression analysis, only urine calcium excretion was identified as a significant predictor for serum OPG levels. CONCLUSIONS: Circulating OPG levels were found to be associated with urine calcium excretion and menopause in healthy women. Our observations suggest that circulating OPG levels reflect an antiresorptive activity in bone, and they are related to endogenous oestrogen levels.     

Effect of cyclical intermittent etidronate therapy on circulating osteoprotegerin levels in patients with rheumatoid arthritis

OBJECTIVE: To evaluate the role of serum osteoprotegerin (OPG) as a biochemical marker for disease activity assessment and drug monitoring in patients with rheumatoid arthritis (RA) treated with cyclical etidronate. DESIGN: Forty patients (35 women and 5 men) with RA of <5 years duration were randomized to receive intermittent cyclical etidronate therapy in conjunction with anti-rheumatic therapy or anti-rheumatic therapy alone (without etidronate) in a 2-year, open-label protocol. METHODS: Radiographs of hands and feet and serum samples for the determination of OPG, amino terminal propeptide (PINP), cross-linked C-telopeptide (ICTP) and amino terminal telopeptid of type I collagen were obtained at baseline and at 24 months. RESULTS: Etidronate treatment had no effect on circulating OPG levels, although the significant decline in PINP and ICTP (P=0.001 and P=0.04 respectively) reflected the efficacy of the anti-resorptive therapy. At baseline and at study termination, serum OPG correlated significantly with age (r=0.45; P=0.003 and r=0.56; P=0.0002 respectively). OPG was not related to biochemical markers of bone metabolism, indices of disease activity or radiographic disease progression. At baseline, the mean serum OPG was higher in patients receiving 5-10 mg/day prednisone (82.8+/-4.0 pg/ml, n=16) compared with those receiving <5 mg/day or with no prednisone (69.7+/-4.7 pg/ml, n=23) (P=0.05). CONCLUSIONS: Our results suggested that serum OPG measurement, perhaps because of the complexity of the regulation of the OPG, may be difficult to utilize in the evaluation of anti-resorptive therapy. Moreover, low dose corticosteroid-associated osteoporosis is probably not mediated by inhibition of OPG.