Role of receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin and macrophage protein 1-alpha (MIP-1a) in monoclonal gammopathy of undetermined significance (MGUS)

The aim of this study was to evaluate the role of markers of bone remodelling, and osteoclast activation/function in patients with monoclonal gammopathy of undetermined significance (MGUS). We have measured serum levels of soluble RANKL (sRANKL), osteoprotegerin (OPG), macrophage inflammatory protein-1alpha (MIP-1alpha), markers of bone resorption [N-telopeptide of collagen type-I (NTX), and tartrate-resistant acid phosphatase isoform-5b (TRACP-5b)] and bone formation [bone-alkaline phosphatase (bALP)] in 40 MGUS patients. These parameters were compared with those of 42 newly diagnosed myeloma patients, and 45 healthy, gender- and age-matched controls. MGUS patients had elevated levels of NTX, sRANKL, and sRANKL/OPG ratio compared with controls (P < 0.0001). Furthermore, TRACP-5b, MIP-1alpha and NTX were decreased in patients with MGUS compared with myeloma patients (P < 0.001), while OPG and bALP were increased (P < 0.001). Serum levels of MIP-1alpha, as well as TRACP-5b, and sRANKL/OPG ratio were reduced, while bALP was increased in MGUS patients, even when compared with myeloma patients who had stage I/II disease. These results demonstrate that increased osteoclastogenesis leading to increased bone resorption is present in MGUS but seems to be compensated for by normal bone formation, which is absent in MM. Furthermore MIP-1alpha, bALP, and sRANKL/OPG may be useful tools for distinguishing between cases of MGUS and early myeloma.     

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.     

强直性脊柱炎继发骨质疏松及相关因素分析

目的 测定强直性脊柱炎(AS)患者骨密度(BMD)、血清骨保护素(OPG)、可溶性核因子κB受体活化因子配体(sRANKL)等骨代谢指标及外周血T细胞表面RANKL表达情况,研究RANKI/RANK/OPG系统在AS骨代谢中的作用.方法 双能X线吸收法(DEXA)测定AS患者BMD;酶联免疫吸附试验(ELISA)法检测血清OPG、sRANKL、抗酒石酸酸性磷酸酶异构体5b(TRACP-5b)、骨特异性碱性磷酸酶(BALP)水平;分析BMD、上述骨代谢指标及临床指标间相关性;流式细胞术(FC)检测外周血CD4+/RANKL+及CD8+/RANKL+细胞表达率;分析它们与红细胞沉降率(ESR)、C反应蛋白(CRP)相关性.计量资料采用成组设计的t检验,计数资料采用x2检验,相关性采用直线相关分析.结果 ①AS患者骨量减少、骨质疏松(OP)发生率分别为47%、37%.②AS组血清sRANKL、TRACP-5b水平及sRANKL/OPG比值均高于对照组(P<0.05);2组血清OPG、BALP水平差异无统计学意义.③AS组血清sRANKL水平与OPG呈正相关,两者均与TRACP-5b呈正相关(P<0.01.④AS组外周血CD4+/RANKL+细胞表达率高于对照组(P<0.05).结论 AS存在较高的骨量丢失率,其骨代谢特点以骨吸收增强为主,RANKL/RANK/OPG系统在其中起着重要作用,该系统失衡可能是AS骨量丢失机制之一;CD4+T细胞可能通过上调RANKL表达参与AS破骨细胞分化成熟及骨吸收机制.     

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.     

Serum levels of OPG, RANKL and RANKL/OPG ratio in newly-diagnosed patients with multiple myeloma. Clinical correlations

Serum levels of OPG and RANKL and their clinical correlations were analyzed in 66 newly-diagnosed patients with multiple myeloma (MM). RANKL and RANKL /OPG ratio were significantly increased in advanced clinical stages and high grade myeloma bone disease (MBD), while OPG showed a tendency to decrease. Renal failure modified the expression of OPG. RANKL and RANKL/OPG ratios are informative markers for myeloma tumor burden and MBD.     

Immunomodulation of Multiple Myeloma Bone Disease

Multiple myeloma (MM) is a clonal malignancy of terminally differentiated plasma cells. Myeloma patients often have extensive skeletal complications, including bone pain, osteolytic lesions and pathological fractures, which represent the major cause of morbidity and possible mortality. Osteolysis is due to the uncoupling of bone cell activity, caused by osteoclast activation and osteoblast inhibition. Osteoclast biology is dominantly regulated by the RANK/RANKL/OPG axis. A disruption of RANKL/OPG ratio, due to the prevalence of RANKL and/or inactivation of OPG, has been reported in MM bone disease by different mechanisms involving either malignant plasma cells and/or other cells of immune system. Despite the major involvement of RANKL in MM is well documented, a dysregulated production of other cytokines either with pro- or anti-osteoclastogenic activity can also contribute to the development of osteolytic lesions by acting directly on bone cells or altering RANKL/OPG axis. This review focuses on molecules produced by cells of immune system able to induce bone destruction in MM bone disease.     

Circulating osteoprotegerin and receptor activator for nuclear factor kappaB ligand: clinical utility in metabolic bone disease assessment

CONTEXT: The discovery of the receptor activator for nuclear factor kappaB (RANK) ligand (RANKL)/RANK signaling pathway has marked a major advance in our understanding of the mechanisms controlling osteoclastogenesis. RANKL, expressed by preosteoblasts and stromal cells, binds to RANK, expressed by cells of the osteoclast lineage, inducing a signaling cascade leading to the differentiation and fusion of osteoclast precursor cells and stimulating the activity of the mature osteoclast. The effects of RANKL are counteracted by osteoprotegerin (OPG), a soluble neutralizing decoy receptor. EVIDENCE: This paper reviews the literature surrounding the use of circulating OPG and soluble RANKL (sRANKL) measurements and assesses their potential as markers of bone disease. Original clinical and basic research articles and reviews were identified using a Pubmed search strategy (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) and cover the time period up until January 2005. Search terms osteoprotegerin, OPG, RANK, RANKL, and RANK ligand were used alone and in combination with bone, osteoporosis, and disease. EVIDENCE SYNTHESIS: Assays for detecting OPG and sRANKL in the circulation in humans have been developed, and differences in the circulating concentrations of OPG and sRANKL have been observed in different disease states. There are, however, some inconsistencies in study outcome. These may relate to differences in study design, methodology, and other unknown factors influencing the variability of these measurements. CONCLUSIONS: The clinical utility of serum OPG and sRANKL measurements as markers of disease activity requires additional investigation. In particular, rigorous testing of assays and identification of the sources of measurement variability are required.     

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.     

Elevated serum levels of soluble receptor activator of nuclear factors-kappaB ligand (sRANKL) and reduced bone mineral density in patients with ankylosing spondylitis (AS)

OBJECTIVE: To assess bone mineral density (BMD), serum levels of soluble receptor activator of nuclear factors-kappaB ligand (sRANKL) and osteoprotegerin (OPG) in patients with ankylosing spondylitis (AS), and to determine their relationships with disease activities. METHODS: Serum levels of sRANKL and OPG in AS were measured by sandwich enzyme-linked immunosorbent assay. The disease activities were determined using Bath Ankylosing Spondylitis Disease Activity Score Index, Bath Ankylosing Spondylitis Functional Index , Bath Ankylosing Spondylitis Metrology Index and Bath Ankylosing Spondylitis Patient Global Score. BMD of femur and lumbar spine was measured by dual energy X-ray absorptiometry. Radiological grading was determined by New York criteria for sacroiliitis and modified Stoke Ankylosing Spondylitis Spine Score. RESULTS: Osteoporosis and osteopaenia of femoral neck were found in 33 and 41% of patients, respectively. BMD of femoral neck showed negative correlation with disease activity indexes, erythrocyte sedimentation rate and C-reactive protein. The serum sRANKL levels and the ratio of sRANKL to OPG were significantly higher in patients with AS than those of controls. The sRANKL/OPG ratio tended to increase in patients with reduced BMD and radiological findings of active inflammation. CONCLUSION: About 74% of AS patients have reduced BMD and this change reflects disease activity. Serum sRANKL levels and sRANKL/OPG ratios are up-regulated in patients with AS and have relationship with BMD and radiological changes. These results suggest that the imbalance between RANKL and OPG might be involved in the pathogenesis and clinical courses of osteoporosis in AS.     

Unusual Association between Increased Bone Resorption and Presence of Paroxysmal Nocturnal Hemoglobinuria Phenotype in Multiple Myeloma

Paroxysmal nocturnal hemoglobinuria (PNH) clones deficient in glycosylphosphatidylinositol-anchored molecules, including CD55 and CD59, have been previously described in patients with multiple myeloma (MM). The aim of this study was to investigate the possible association between existence of the PNH phenotype and myeloma bone disease. Forty-three patients with newly diagnosed MM were the subjects of the study. Radiographic evaluation of the skeleton was performed in all patients at diagnosis. The following biochemical markers were measured: bone resorption markers (tartrate-resistant acid phosphatase isoform 5b [TRACP-5b]and N-terminal cross-linking telopeptide of type-I collagen [NTX]), bone formation markers (bone alkaline phosphatase [bALP] and osteocalcin [OC]), osteoprotegerin (OPG), soluble receptor activator of nuclear factor KB ligand (sRANKL), and interleukin 6 (IL-6). Detection of CD55- and/or CD59-deficient red cell populations was performed after diagnosis. Patients with MM had elevated mean baseline NTX, TRACP-5b, sRANKL, and IL-6 levels compared with controls, whereas the mean values of bALP, OC, and OPG were significantly decreased. Four patients had no osteolytic lesions, whereas 8 patients had 1 to 3 lytic lesions, and 31 patients had more than 3 lytic lesions and/or pathologic fractures in the skeletal survey. CD55- and/or CD59-deficient red cell populations were observed in 56% of patients with MM. There was a strong correlation between the presence of PNH-like erythrocytes and increased bone resorption, as measured by NTX, TRACP-5b, and sRANKL/OPG ratio (P < .03, P < .02, and P < .02, respectively). There was also a significant correlation between PNH phenotype and severe bone disease (P < .02). These results suggest that there is a possible link between PNH phenotype and increased osteoclastic activity in MM owing to a potential effect of myeloma microenvironment on a preexisting PNH clone. Further studies are required for clarifying this phenomenon and investigating possible mechanisms of this unusual association.     

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.     

Circulating RANKL/OPG in polymyalgia rheumatica

OBJECTIVE: To evaluate whether RANKL/OPG balance is modified in PMR patients, either in the active phase of the disease or during corticosteroid treatment. METHODS: Circulating levels of RANKL and OPG were assayed by enzyme-linked immunosorbent assay in PMR patients with active untreated disease and in patients treated by corticosteroids over a 12-month follow-up period. RESULTS: We found no statistically significant differences in circulating levels of OPG between PMR patients either in the active phase of the disease or during all follow-up period compared to normal controls. On the other hand, systemic production of sRANKL is increased and is not modulated by corticosteroid treatment. CONCLUSION: In PMR increased levels of sRANKL may be related to bone osteoporosis. Further investigations are necessary to evaluate the relationship between the RANK/RANKL/OPG system and bone turnover in PMR patients.     

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.     

Serum sRANKL/OPG predict recurrence after radiofrequency catheter ablation of lone atrial fibrillation

Background

Radiofrequency catheter ablation (RFCA) is a widely accepted strategy for eliminating atrial fibrillation (AF). A considerable recurrence rate has partly been ascribed to atrial remodeling. Osteoprotegerin (OPG)/receptor activator of nuclear factor-κB (RANK)/RANK ligand (RANKL) axis may contribute to the development and progression of AF by regulating atrial structural remodeling. This study aimed to determine the relationship between serum soluble RANKL (sRANKL)/OPG and the risk of recurrent arrhythmia after ablation of lone AF.

Methods

We enrolled 527 lone AF patients undergoing first-time RFCA with complete follow-up data. Pre-ablation venous blood samples were obtained for measurement of serum sRANKL and OPG.

Results

During the follow-up period of 15 (3–64) months, AF recurred in 187 patients (35.5%). Recurrence was associated with an elevation of serum sRANKL level and sRANKL/OPG ratio. In multivariate survival regression, persistent AF, AF duration, left atrial diameter, amiodarone after ablation, particularly serum sRANKL level and sRANKL/OPG ratio independently predicted AF recurrence. According to ROC curve analysis, the best diagnostic values of serum sRANKL level and sRANKL/OPG ratio for predicting recurrence were 4.89 pmol/l and 0.76, respectively.

Conclusions

Baseline serum high sRANKL level and sRANKL/OPG ratio are associated with AF recurrence after primary ablation procedure in lone AF patients, and may be used in the prediction of AF recurrence in these patients.     

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.     

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.     

多发性骨髓瘤骨病患者骨代谢及调节因子水平及其意义

目的 研究多发性骨髓瘤(MM)患者血清Dickkopf-1(DKK-1)、可溶性核因子κB配体受体激活剂(sRANKL)、护骨素(OPG)和骨代谢因子[碱性磷酸酶(ALP)、抗酒石酸酸性磷酸酶(TRACP-5b)]水平及其与MM分期、溶骨性病变的关系,探讨骨代谢及调节因子DKK-1和sRANKL在MM骨病中的临床意义.方法 采用双抗体夹心ELISA检测30例初诊MM患者和20例健康人血清DKK-1、sRANKL、OPG、ALP、TRACP-5b等骨代谢因子及调节因子的水平.结果 MM患者血清DKK-1、sRANKL、OPG和TRACP水平均显著高于健康人,分别为42.96μg/L比5.33 μg/L,1.83pmol/L比0.79 pmol/L,1799.30 pmol/L比822.40 pmol/L,5.81 U/L比0.28 U/L,P值均＜0.05.国际分期系统(ISS)分期Ⅲ期患者血清DKK-1水平(46.33 μg/L)和sRANKL(2.26 pmol/L)水平显著高于Ⅰ/Ⅱ期患者(37.91μgL和1.19 pmol/L,P值均＜0.05).3处以上与1～3处溶骨病变患者相比,血清DKK-1、sRANKL和TRACP-5b水平显著升高(46.30μg/L比31.98μg/L,2.18 pmol/L比0.69 pmol/L,6.02 U/L比5.13 U/L,P值均＜0.05).结论 MM患者血清DKK-1、sRANKL、OPG和TRACP-5b水平均显著高于健康人;血清DKK-1、sRANKL水平与MM分期及溶骨病变程度相关.

Abstract：

Objective To detect serum concentrations of Dickkopf-1(DKK-1) and soluble receptor activator of nuclear factor-κB ligand (sRANKL) in patients with multiple myeloma (MM) and to investigate its clinical significance. Methods Serum DKK-1, sRANKL, osteoporotegerin(OPG) and tartrate-resistant acid phosphatase 5b (TRACP-5b) levels were quantified in 30 newly diagnosed MM patients and 20 healthy control subjects by using sandwich ELISA. Results The serum DKK-1, sRANKL,OPG and TRACP-5b levels were significantly higher than those in the healthy controls (42.96 μg/L vs 5.33 μg/L, 1.83 pmol/Lvs 0. 79 pmol/L, 1799. 30 pmol/L vs 822.40 pmol/L, 5.81 U/L vs 0. 28 U/L, respectively; all P＜0. 05). Serum levels of DKK-1 were positively correlated with sRANKL and TRACP-5b, respectively.Serum concentrations of DKK-1 and sRANKL were significantly elevated in stage Ⅲvs stages Ⅰ and Ⅱaccording to International Staging System (ISS) (46. 33 μg/L vs 37.91 μg/L, 2.26 pmol/L vs 1.19pmol/L, respectively, all P ＜0.05). Serum concentrations of DKK-1 , sRANKL and TRACP-5b were significantly higher in patients with more than 3 lytic bone lesions than those with only 1-3 lytic bone lesions (46. 30 μg/L vs 31.98 μg/L, 2. 18 pmol/L vs 0. 69 pmol/L, 6.02 U/L vs 5. 13 U/L, all P ＜ 0.05).Conclusions MM patients have increased serum DKK-1, sRANKL, OPG and TRACP-5b levels as compared with the healthy controls. Serum concentrations of DKK-1 and sRANKL have close relationship with MM stage and lytic bone disease.     

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.     

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.     

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.