Study on the effects of Zhuanggu Guanjie Pill, a modern Chinese medicine formula, on the activities and mRNA expression of seven CYP isozymes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Zhuanggu Guanjie Pill (ZGGJP), a modern Chinese medicine formula, is composed of 12 herbs and has been used to treat osteoporosis in China for almost 30 years. However, no in vivo study of the influences of ZGGJP on the cytochrome P450 (CYP) activities have been reported.

AIM OF THE STUDY

The aim of this study was to evaluate the effects of ZGGJP on the activities and the mRNA expression of CYP enzymes (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A) and their corresponding nuclear receptor levels in rats.

MATERIALS AND METHODS

After 7 days oral treatment of ZGGJP at low- and high-dose, cocktail solution was given to rats. Blood samples were collected at series of time points. The plasma concentrations of probe drugs and their corresponding metabolites were determined by UPLC-MS/MS. The influence of ZGGJP on the activities of seven CYPs were evaluated the metabolic ratios (Cmax and AUC0-t) for metabolites/probe drugs. In addition, the effects of ZGGJP on the mRNA expression of CYPs and their corresponding nuclear receptors in rat liver were evaluated by real-time PCR.

RESULTS

ZGGJP showed significant inductive effects on CYP1A2 and CYP2B6 of both male and female rats. The influence of ZGGJP on CYP2C9 and CYP3A showed gender difference. ZGGJP could induce the activities of CYP2C9 and CYP3A in female rats, but have no influence on the activities in male rats. ZGGJP had no effects on CYP2D6, CYP2C19 and CYP2E1. The mRNA expression results of CYPs were in accordance with the pharmacokinetic results. The mRNA expression levels of constitutive androstane receptor (CAR) and vitamin D receptor (VDR) were increased significantly in female rats at high dosage, but no significant changes were observed in male rats.

CONCLUSION

ZGGJP had inductive effects on CYP1A2 and CYP2B6 in both male and female rats. The results showed that ZGGJP could induce the activities of CYP2C9 and CYP3A in female rats, but had no effect in male rats. This may suggest that the influence of ZGGJP on CYP2C9 and CYP3A exhibit gender difference. The inductive effects of ZGGJP on the activities of CYPs, exhibiting gender difference, may be regulated by CAR and VDR. Therefore, co-administration of ZGGJP with other drugs, especially using CYP2C9 and CYP3A substrates in females, may need dose adjustment to avoid herb-drug interaction.

Elevated plasma osteoprotegerin levels are associated with venous thrombosis and bleeding in patients with polycythemia vera

Patients with polycythemia vera (PV) have an increased risk for the development of thrombohemorrhagic complications. The pathogenesis of these complications is still unclear.An important role in vascular disease has recently been attributed to osteoprotegerin (OPG). It has been shown that various tissues of the cardiovascular system produce OPG, and there is growing evidence of an association between elevated serum OPG levels and cardiovascular morbidity.We evaluated if OPG was associated with an increased risk of venous thrombosis or bleeding complications in a cohort of 114 PV patients.The analysis consisted of a retrospective and a prospective part. In the retrospective univariate analysis,a one unit change in OPG caused the odds of venous thrombosis to increase by 40% (p=0.005) and the odds of bleeding to increase by 52% (p=0.001). Multivariate analysis only slightly attenuated the association to 33% (p=0.03) and 37% (p=0.013) for venous thrombosis and bleeding, respectively. OPG was also related to the development of the combined outcome of venous thrombosis and bleeding in the prospective analysis (log-rank-test: p=0.017).This is the first report that links the occurrence of venous thrombosis or bleeding to elevated OPG levels.

Resveratrol Increases Hepatic SHBG Expression through Human Constitutive Androstane Receptor: a new Contribution to the French Paradox

Sex hormone-binding globulin (SHBG) carries sex steroids in blood regulating their bioavailability. Red wine consumption increases plasma SHBG levels, and we have discovered that resveratrol, a polyphenol enriched in red wine, acts specifically through the human constitutive androstane receptor (CAR), a drug/xenobiotic detoxification gene regulator, to increase hepatic SHBG production. Chromatin immunoprecipitation and luciferase reporter gene assays show that human CAR binds to a typical direct repeat 1 nuclear hormone receptor-binding element in the human SHBG proximal promoter. Resveratrol also increased hepatic SHBG production in humanized SHBG/CAR transgenic mice. Moreover, SHBG expression correlated significantly with CAR mRNA levels in human liver biopsies. We conclude that the beneficial effects of red wine on the metabolic syndrome and it associated co-morbidities, including cardiovascular disease and type 2 diabetes, may be mediated in part by resveratrol acting via CAR to increase plasma SHBG levels.

DNA hypomethylation of a transcription factor binding site within the promoter of a gout risk gene NRBP1 upregulates its expression by inhibition of TFAP2A binding

BACKGROUND

Genome-wide association studies (GWASs) have identified dozens of loci associated with gout, but for most cases, the risk genes and the underlying molecular mechanisms contributing to these associations are unknown. This study sought to understand the molecular mechanism of a common genetic variant, rs780093, in the development of gout, both in vitro and in vivo.

RESULTS

Nuclear receptor binding protein 1 (NRBP1), as a gout risk gene, and its regulatory region, 72 bp upstream of the transcription start site, designated as B1, were identified through integrative analyses of genome-wide genotype and DNA methylation data. We observed elevated NRBP1 expression in human peripheral blood mononuclear cells (PBMCs) from gout patients. In vitro luciferase reporter and protein pulldown assay results showed that DNA methylation could increase the binding of the transcription factor TFAP2A to B1, leading to suppressed gene expression. There results were further confirmed by in vivo bisulfite pyrosequencing showing that hypomethylation on B1 is associated with increased NRBP1 expression in gout patients.

CONCLUSIONS

Hypomethylation at the promoter region of NRBP1 reduces the binding of TFAP2A and thus leads to elevated NRBP1 expression, which might contribute to the development of gout.

Farnesoid X Receptor and Liver X Receptor Ligands Initiate Formation of Coated Platelets

OBJECTIVES

The liver X receptors (LXRs) and farnesoid X receptor (FXR) have been identified in human platelets. Ligands of these receptors have been shown to have nongenomic inhibitory effects on platelet activation by platelet agonists. This, however, seems contradictory with the platelet hyper-reactivity that is associated with several pathological conditions that are associated with increased circulating levels of molecules that are LXR and FXR ligands, such as hyperlipidemia, type 2 diabetes mellitus, and obesity.

APPROACH AND RESULTS

We, therefore, investigated whether ligands for the LXR and FXR receptors were capable of priming platelets to the activated state without stimulation by platelet agonists. Treatment of platelets with ligands for LXR and FXR converted platelets to the procoagulant state, with increases in phosphatidylserine exposure, platelet swelling, reduced membrane integrity, depolarization of the mitochondrial membrane, and microparticle release observed. Additionally, platelets also displayed features associated with coated platelets such as P-selectin exposure, fibrinogen binding, fibrin generation that is supported by increased serine protease activity, and inhibition of integrin αIIbβ3. LXR and FXR ligand-induced formation of coated platelets was found to be dependent on both reactive oxygen species and intracellular calcium mobilization, and for FXR ligands, this process was found to be dependent on cyclophilin D.

CONCLUSIONS

We conclude that treatment with LXR and FXR ligands initiates coated platelet formation, which is thought to support coagulation but results in desensitization to platelet stimuli through inhibition of αIIbβ3 consistent with their ability to inhibit platelet function and stable thrombus formation in vivo.

Exposure to endocrine disrupters and nuclear receptor gene expression in infertile and fertile women from different Italian areas

Within the PREVIENI project, infertile and fertile women were enrolled from metropolitan, urban and rural Italian areas. Blood/serum levels of several endocrine disrupters (EDs) (perfluorooctane sulfonate, PFOS; perfluorooctanoic acid, PFOA; di-2-ethylhexyl-phthalate, DEHP; mono-(2-ethylhexyl)-phthalate, MEHP; bisphenol A, BPA) were evaluated concurrently with nuclear receptors (NRs) gene expression levels (ERa, ERb, AR, AhR, PPARg, PXR) in peripheral blood mononuclear cells (PBMCs). Infertile women from the metropolitan area displayed significantly higher levels of: BPA compared to fertile women (14.9 vs. 0.5 ng/mL serum); BPA and MEHP compared to infertile women from urban and rural areas; enhanced expression levels of NRs, except PPARg. Infertile women from urban and rural areas had PFOA levels significantly higher than those from metropolitan areas. Our study indicates the relevance of the living environment when investigating the exposure to EDs and the modulation of the NR panel in PBMC as a suitable biomarker of the effect, to assess the EDs impact on reproductive health.

Intima-media thickness of the carotid arteries is related to serum osteoprotegerin levels in healthy postmenopausal women

Osteoprotegerin (OPG) regulates bone mass by inhibiting osteoclast differentiation and activation, and also plays a role in vascular calcification. The objective of this study was to evaluate the relationship between serum OPG levels, and carotid artery intima-media thickness (IMT) and carotid plaque formation in healthy postmenopausal women. We recruited 68 healthy postmenopausal women for the study. Carotid plaque presence and IMT were evaluated by high resolution B-mode ultrasound. IMT was positively correlated with presence of plaque, age, menopause age and OPG, and inversely correlated with Apolipoprotein A1 (Apo A1). Serum OPG level was positively correlated with IMT (r = 0.366; p < 0.003) and age (r = 0.324; p < 0.008), and negatively correlated with Apo A1 (r = -0.481; p < 0.0001). We did not observe any significant relation between plaque occurrence and levels of serum OPG. In regression analysis OPG (p < 0.02) and menopause age (p < 0.05) were independent risk factors for IMT, and age (p < 0.05) and IMT (p < 0.05) were independent risk factors for plaque formation. Although the role of OPG in the vascular biology is poorly understood, our results suggest that elevated levels of serum OPG is associated with IMT and may play a role in the pathogenesis of atherosclerotic disease.

Prognostic value of CRM1 in pancreas cancer

PURPOSE

Pancreatic cancer is a highly aggressive malignant tumour with poor prognosis. The median survival is only 6 months. This study investigated the prognostic value of nuclear export protein chromosomal region maintenance/exportin 1/Xpo1 (CRM1) expression in pancreas cancer.

METHODS

CRM1 expression was detected, by Western blot, in pancreatic tissue from 69 cancer patients and 10 normal subjects.

RESULTS

CRM1 showed increased expression in pancreatic cancer tissue (P = 0.007). The high expression of CRM1 was associated with increased serum levels of CEA (P = 0.002) and CA19-9 (P = 0.005). There was an association between CRM1 expression and tumour size (P = 0.01), lymphadenopathy (P = 0.004) and liver metastasis (P = 0.003). High CRM1 expression was not correlated with the other clinicopathological parameters. High CRM1 expression was a prognostic indicator for progression-free survival (PFS) (P = 0.006) as well as overall survival (OS) (P = 0.001). Expression of CRM1 was an independent prognostic parameter for poorer PFS and OS (95% CI, 1.27-5.39).

CONCLUSIONS

CRM1 expression demonstrated prognostic value in pancreatic cancer. Prospective studies are required to determine the prognostic role of high expression of CRM1 in pancreatic cancer.

Osteoprotegerin and Bone Mineral Density in Hemodiafiltration Patients

A newly identified cytokine, osteoprotegerin (OPG) appears to be involved in the regulation of bone remodeling. In vitro studies suggest that OPG, a soluble member of the TNF receptor family of proteins, inhibits osteoclastogenesis by interrupting the intercellular signaling between osteoblastic stromal cells and osteoclast progenitors. As patients with chronic renal failure (CRF) often have renal osteodystrophy (ROD), we investigated the role of osteoprotegerin (OPG) in ROD, and investigated whether there was any relationship between serum OPG, intact parathyroid (PTH) (iPTH), vitamin D, and trabecular bone. Serum OPG combined with iPTH might be a useful tool in the noninvasive diagnosis of ROD, at least in cases in which the range of PTH values compromises reliable diagnosis. Thirty-six patients on maintenance hemodiafiltration (HDF) and a control group of 36 age and sex matched healthy subjects with no known metabolic bone disease were studied. The following assays were made on serum: iPTH, osteocalcin (BGP), bone alkaline phosphatase, 25(OH)-cholecalciferol, calcium, phosphate, OPG, IGF-1, estradiol, and free testosterone. Serum Ca++, P, B-ALP, BGP, IGF-1, iPTH, and OPG levels were significantly higher in HDF patients than in controls, while DXA measurements and quantitative ultrasound (QUS) parameters were significantly lower. On grouping patients according to their mean OPG levels, we observed significantly lower serum IGF-1, vitamin D3 concentrations, and lumbar spine and hip bone mineral density in the high OPG groups. No correlation was found between OPG and bone turnover markers, whereas a negative correlation was found between serum OPG and IGF-1 levels (r=-0.64, p=0.032). Serum iPTH concentrations were positively correlated with bone alkaline phosphatase (B-ALP) (r=0.69, p=0.038) and BGP (r=0.92, p<0.001). The findings made suggest that an increase in OPG levels may be a compensatory response to elevated bone loss. The low bone mineral density (BMD) levels found in the high OPG group might have been due to the significant decrease in serum IGF-1 and vitamin D3 observed. In conclusion, the findings made in the present study demonstrate that increased OPG in hemodiafiltration patients is only partly due to decreased renal clearance. As it may partly reflect a compensatory response to increased bone loss, this parameter might be helpful in the identification of patients with a marked reduction in trabecular BMD.

Nuclear receptors in human immune cells: Expression and correlations

Nuclear receptors (NR) are key modulators of gene transcription. Their activity is ligand induced and modulates a large variety of tissue-specific cellular functions. However, for many NR little is known about their role in cells of the immune system. In this study, expression patterns and distribution of 24 NR were investigated in human peripheral blood mononuclear cells. We provide the first evidence of the expression of the 12 receptors CAR, CoupTFalpha, CoupTFbeta, FXR, GCNF, HNF4alpha, PPARbeta/delta, PXR, RevErbbeta, TR2, TR4 and TLX in highly purified CD4, CD8, CD19, CD14 cells. The expression profile of RevErbalpha and LXRalpha previously observed in B cell and macrophages, respectively, has been extended to CD4, CD8 and CD14 cells. Except for RARbeta, which was absence in any of the cells tested, our results suggest an almost ubiquitous expression of the NR in the different cell lineages of the immune system. The expression of CAR, CoupTFalpha, FXR was also confirmed at a protein level and despite conspicuous mRNA levels of HNF4alpha, only low levels of this receptor were detectable in the nuclear fraction of PBMCs. Expression of the latter receptors was mostly only a fraction (4-20%) of their expression in the thyroid gland, the adrenal gland, the lung or subcutaneous adipose tissue. The Spearman rank order correlation test was performed to examine the correlation in expression between individual nuclear receptor pairs in the four cell types for several donors. Distinct correlation patterns were observed between receptor pairs in the individual cell types. In CD4 T cells four NR, GCNF, PPARgamma, PPARalpha7 and RevErbbeta are perfectly correlated with each other (P> or =0.0167). In the other cell types correlations between NR pairs were more diverse, but also statistically highly significant. Interestingly, the relative expression level of a number of receptor pairs ranked identical or similar in at least three (CoupTFalpha and PPARbeta/delta, CoupTFbeta and HNF4alpha as well as RORbeta and PXR) or four cell types (CoupTFalpha and CoupTFbeta, PPARgamma and RevErbbeta). Despite the variability of NR expression in immune cells, these results suggest that some of the NR may be co-regulated in human immune cells.

Lumbar bone mineral density as the major factor determining increased prevalence of vertebral fractures in monoclonal gammopathy of undetermined significance

The possible relationships between biochemical measurements and both densitometric and radiographic indexes of skeletal fragility were evaluated in 65 postmenopausal women with monoclonal gammopathy of undetermined significance (MGUS). There was a significantly higher prevalence of vertebral fractures in the MGUS group compared with a control population (P < or = 0.001). The MGUS patients were then grouped according to the presence or absence of at least one mild vertebral fracture. Patients with fractures (Fx, n=34) were older (62.8 +/- 6.1 years), with long-standing disease (8.8 +/- 7.1 years) when compared with those without fractures (NFx, n=31; 59.7 +/- 5.0 years, P < or = 0.05 and 5.8 +/- 4.1 years, P < or = 0.05). The receptor activator of nuclear factor kappa-B ligand/osteoprotegerin ratio was higher in Fx compared with NFx (0.092 +/- 0.018 vs. 0.082 +/- 0.020; P < or = 0.05). Lumbar spine (0.811 +/- 0.14 vs. 0.956 +/- 0.12 g/cm2), femoral neck (0.660 +/- 0.09 vs. 0.747 +/- 0.10 g/cm2) and total bone mineral density (BMD) (0.788 +/- 0.11 vs. 0.884 +/- 0.11 g/cm2) were lower (all P < or = 0.001) in FxMGUS compared with Nfx patients. Receiver operating characteristic curves identified lumbar BMD as the variable that best predicted vertebral fractures (area under the curve 0.817; 95% confidence interval, 0.713-0.921). This study provides an indication for the measurement of BMD in MGUS patients, as a means of predicting vertebral fractures, especially in those that are asymptomatic. Patients with prevalent fractures should undergo pharmacological treatment to prevent further fractures.

The bisphosphonate olpadronate inhibits skeletal prostate cancer progression in a green fluorescent protein nude mouse model

PURPOSE

Metastatic bone disease is one of the major causes of morbidity and mortality in prostate cancer patients. Bisphosphonates are currently used to inhibit bone resorption and reduce tumor-induced skeletal complications. More effective bisphosphonates would enhance their clinical value.

EXPERIMENTAL DESIGN

We tested several bisphosphonates in a green fluorescent protein (GFP)-expressing human prostate cancer nude mouse model. The in vivo effects of four bisphosphonates, including pamidronate, etidronic acid, and olpadronate, on bone tumor burden in mice intratibially inoculated with PC-3-GFP human prostate cancer cells were visualized by whole-body fluorescence imaging and X-ray.

RESULTS

The PC-3-GFP cells produced extensive bone lesions when injected into the tibia of immunocompromised mice. The skeletal progression of the PC-3-GFP cell growth was monitored by GFP fluorescence and the bone destruction was evaluated by X-ray. We showed that 3,3-dimethylaminopropane-1-hydroxy-1,1-diphosphonic acid (olpadronate) was the most effective bisphosphonate treatment in reducing tumor burden as assessed by GFP imaging and radiography. The GFP tumor area and X-ray score significantly correlated. Reduced tumor growth in the bone was accompanied by reduced serum calcium, parathyroid hormone-related protein, and osteoprotegerin.

CONCLUSIONS

The serum calcium, parathyroid hormone-related protein, and osteoprotegerin levels were significantly correlated with GFP area and X-ray scores. Treatment with olpadronate reduced tumor growth in the bone measured by GFP and X-ray imaging procedures. Imaging of GFP expression enables monitoring of tumor growth in the bone and the GFP results complement the X-ray assessment of bone disease. The data in this report suggest that olpadronate has potential as an effective inhibitor of the skeletal progression of clinical prostate cancer.

Osteoporosis in hemodialysis patients revisited by bone histomorphometry: a new insight into an old problem

Osteoporosis in hemodialysis patients is associated with high morbidity and mortality and, although extensively studied by noninvasive methods, has never been assessed through bone biopsy. The aim of this study was to use histomorphometry to evaluate osteoporosis and identify factors related to its development in hemodialysis patients. We conducted a cross-sectional study involving 98 patients (35 women and 63 men; mean age: 48.4 +/- 13 years) on hemodialysis for 36.9 +/- 24.7 months. Patients were submitted to transiliac bone biopsy with double tetracycline labeling. The bone metabolism factors ionized calcium, phosphorus, bone alkaline phosphatase, deoxypyridinoline, intact parathyroid hormone, and 25(OH) vitamin D were evaluated, as were the bone remodeling cytokines osteoprotegerin (OPG), soluble receptor-activator of NF-kappabeta ligand (sRANKL) and tumor necrosis factor-alpha (TNF)alpha. Osteoporosis was defined as trabecular bone volume (BV/TV) greater than 1 s.d. below normal (men <17.4%; women <14.7%). Forty-five patients (46%) presented osteoporosis, which was correlated with white race. We found BV/TV to correlate with age, OPG/sRANKL ratio, TNFalpha levels, and length of amenorrhea. In multiple regression analysis adjusted for sex and age, length of amenorrhea, white race, and OPG/sRANKL ratio were independent determinants of BV/TV. Histomorphometric analysis demonstrated that osteoporotic patients presented normal eroded surface and low bone formation rate (BFR/BS). Osteoporosis is prevalent in hemodialysis patients. Low BFR/BS could be involved in its development, even when bone resorption is normal. Cytokines may also play a role as may traditional risk factors such as advanced age, hypogonadism, and white race.

Diagnostic and Prognostic Validity of Serum Bone Turnover Markers in Metastatic Renal Cell Carcinoma

PURPOSE

We assessed the diagnostic accuracy of bone markers in the serum of patients with renal cell carcinoma to detect bone metastases and evaluate the prognostic potential concerning renal cell carcinoma caused mortality.

MATERIALS AND METHODS

The bone formation markers total and bone specific alkaline phosphatase, the bone resorption markers cross-linked N-terminal and tartrate-resistant acid phosphatase isoenzyme 5b, and the osteoclastogenesis markers osteoprotegerin and ligand of the receptor activator of nuclear factor-kappaB, were measured in the serum of 72 patients with renal cell carcinoma, including 28 with pN0M0, 8 with pN1M0 and 36 with M1, and in 32 female and 36 male controls by enzyme-linked immunosorbent assay techniques. Data were evaluated by receiver operating characteristics and survival analysis.

RESULTS

Bone specific alkaline phosphatase, tartrate-resistant acid phosphatase isoenzyme 5b and ligand of the receptor activator of nuclear factor-kappaB did not significantly differ between patients with renal cell carcinoma and controls. Compared with controls tartrate-resistant acid phosphatase isoenzyme 5b, cross-linked N-terminal and osteoprotegerin showed increased concentrations in patients with nonbone metastases but not in those with bone metastases. No bone turnover marker led to differentiation between patients with nonbone and bone metastases. Increased osteoprotegerin above the upper 95% cutoff limit, tumor stage and distant metastatic spread were associated with renal cell carcinoma related survival on Kaplan-Meier analyses. A multivariate Cox proportional hazards regression model revealed that these 3 variables were independent prognostic factors for cancer related death.

CONCLUSIONS

Bone turnover markers are hardly useful to diagnose bone metastases in patients with renal cell carcinoma. However, osteoprotegerin together with clinicopathological characteristics may be helpful as prognosticator of cancer specific death.

Bone mineral density, bone turnover, and osteoprotegerin in depressed women with and without borderline personality disorder

OBJECTIVE

Low bone mineral density has repeatedly been reported in patients with major depressive disorder (MDD), and MDD has been discussed as a risk factor for the development of osteoporosis. MDD in young adults often occurs in the context of borderline personality disorder (BPD), and both MDD and BPD have been associated with a dysregulation of the hypothalamic-pituitary-adrenal system and subsequent hypercortisolemia. To date, it is unclear whether comorbid BPD in depressed patients modulates the extent of bone mass reduction. Therefore, we examined bone density, markers of bone turnover, and proinflammatory cytokines in depressed patients with and without BPD. Patients with BPD alone and healthy women served as comparison groups.

METHOD

Twenty-four patients with MDD and 23 patients with comorbid MDD and BPD were included. Sixteen patients with BPD and 20 healthy women of similar body mass index served as the comparison group. BMD was assessed by means of dual-energy x-ray absorptiometry. Markers of bone turnover, endocrine and immune parameters were determined. For data analysis, the group of depressed patients without comorbid BPD was divided according to age into two groups (younger depressed patients with a mean age of 30 years and older patients with a mean age of 42.9 years).

RESULTS

BMD at the lumbar spine was significantly reduced in a) depressed women with comorbid BPD (mean age, 28.6 years) and in b) older depressed patients without BPD (mean age, 42.9 years). Osteocalcin, a marker of osteoblastic activity, and crosslaps, a marker of bone loss, were significantly different between the study groups. Tumor necrosis factor-alpha was increased in depressed patients when compared with healthy women. Furthermore, TNF-alpha was positively correlated with serum crosslaps, a marker for osteoclastic activity.

CONCLUSION

Depression is associated with reduced bone mass, in particular in patients with comorbid BPD. Possible factors contributing to BMD reduction include endocrine and immune alterations associated with either MDD or BPD. We conclude from our data that a history of MDD with and without comorbid BPD should be considered as a risk factor in clinical assessment instruments for the identification of persons prone to osteoporosis.

Receptor Activator of NF-κB Ligand and Osteoprotegerin Regulate Proinflammatory Cytokine Production in Mice

Receptor activator of NF-kappaB ligand (RANKL) is a membrane-bound or soluble cytokine essential for osteoclast differentiation, whereas the decoy receptor osteoprotegerin (OPG) masks RANKL activity. In mouse serum, both soluble RANKL and OPG are detectable. We observed that mice injected with LPS showed significantly down-regulated serum RANKL levels, whereas serum OPG levels were up-regulated. However, the roles of RANKL and OPG in innate immunity remain obscure. We found that RANKL pretreatment suppressed production of proinflammatory cytokines in macrophages in response to stimulation by bacteria and their components. Furthermore, such RANKL-induced tolerance in macrophages was inhibited by GM-CSF treatment, which blocks RANKL signaling. RANKL-induced tolerance occurred in the absence of c-Fos, which is essential for osteoclast differentiation. In mice lacking OPG, LPS-induced production of proinflammatory cytokines was reduced, whereas in mice lacking RANKL, it was increased, and lethality following LPS injection was also elevated, suggesting that constitutive activities of RANKL suppress cytokine responsiveness to LPS in vivo. Strikingly, prior administration of RANKL protected mice from LPS-induced death. These data reveal prophylactic potential of RANKL in acute inflammatory diseases.

High serum values of soluble CD154, IL-2 receptor, RANKL and osteoprotegerin in Langerhans cell histiocytosis

BACKGROUND

To determine useful biochemical markers in Langerhans cell histiocytosis (LCH), we analyzed the serum levels of soluble CD154 (sCD154), IL2 receptor (sIL2-R), receptor activator of NF-kappaB ligand (sRANKL), and osteoprotegerin (OPG).

PROCEDURE

Our study included 46 newly diagnosed LCH patients (single-system multi-site (SM type): n = 20, and multi-system multi-site (MM type): n = 26) who were treated with the JLSG-02 protocol between 2002 and 2004. The median age of the patients was 3.8 years old (range 0-18). sCD154, sIL2-R, sRANKL, and OPG were measured by ELISA at diagnosis (n = 46) and after 6-weeks of induction therapy (n = 14).

RESULTS

The values of sCD154, sIL-2R, sRANKL, and OPG, and the sRANKL/OPG ratio in sera were significantly higher in patients with LCH compared with controls (1.83 +/- 1.38 vs. 0.22 +/- 0.16 ng/ml, P < 0.001; 1,600 +/- 1,060 vs. 420 +/- 160 pg/ml, P < 0.001; 1.72 +/- 1.20 vs. 1.04 +/- 1.09 pmol/L, P = 0.019; 6.34 +/- 2.94 vs. 3.71 +/- 2.03 pmol/L, P < 0.001; and 0.40 +/- 0.45 vs. 0.16 +/- 0.17, P = 0.023, respectively). Serum levels of sIL-2R were significantly elevated in the MM type compared with the SM type (2,050 +/- 1,060 vs. 870 +/- 340 pg/ml, P < 0.001). Serum OPG levels were also significantly elevated in the MM type compared with the SM type (7.58 +/- 2.72 vs. 5.13 +/- 2.69 pmol/L, P = 0.008) and negatively correlated with the number of bone lesions (r = -0.56, P = 0.007). In contrast, the sRANKL/OPG ratios were significantly higher in the SM type than the MM type (0.57 +/- 0.54 vs. 0.19 +/- 0.14, P = 0.002) and positively correlated with the number of bone lesions (r = 0.34, P = 0.040). In patients who responded to the induction therapy, serum levels of sIL-2R, sRANKL, and OPG, and the sRANKL/OPG ratio decreased significantly after the therapy (1,170 +/- 600 vs. 730 +/- 290 pg/ml, P = 0.029; 2.19 +/- 1.06 vs. 1.24 +/- 0.66 pmol/L, P < 0.001; 6.13 +/- 2.40 vs. 4.72 +/- 2.03 pmol/L, P = 0.040; and 0.57 +/- 0.52 vs. 0.41 +/- 0.37, P = 0.02, respectively). In the three patients who did not respond to the induction therapy, the serum levels of sCD154 increased significantly after the therapy (1.3 +/- 1.1 vs. 2.7 +/- 1.2, P = 0.004).

CONCLUSIONS

Serum levels of sIL-2R and sCD154 could be useful as indicators of inflammation and sRANKL/OPG ratios as markers of osteolytic activity in LCH patients.

Cholesterol-sensing receptors, liver X receptor alpha and beta, have novel and distinct roles in osteoclast differentiation and activation

The liver X receptor (alpha,beta) is responsible for regulating cholesterol homeostasis in cells. However, our studies using the LXRalpha-/-, LXRbeta-/-, and LXRalpha-/-beta-/- mice show that both LXRalpha and beta are also important for bone turnover, mainly by regulating osteoclast differentiation/activity.

INTRODUCTION

The liver X receptors (alpha,beta) are primarily responsible for regulating cholesterol homeostasis within cells and the whole body. However, as recent studies show that the role for this receptor is expanding, we studied whether the LXRs could be implicated in bone homeostasis and development.

MATERIALS AND METHODS

pQCT was performed on both male and female LXRalpha-/-, LXRbeta-/-, LXRalpha-/-beta-/-, and WT mice at 4 months and 1 year of age. Four-month-old female mice were additionally analyzed with reference to qPCR, immunohistochemistry, histomorphometry, transmission electron microscopy, and serum bone turnover markers.

RESULTS

At the mRNA level, LXRbeta was more highly expressed than LXRalpha in both whole long bones and differentiating osteoblast-like MC3T3-E1 and osteoclast-like RAW 264.7 cells. Four-month-old female LXRalpha-/- mice had a significant increase in BMD because of an increase in all cortical parameters. No difference was seen regarding trabecular BMD. Quantitative histomorphometry showed that these mice had significantly more endosteal osteoclasts in the cortical bone; however, these cells appeared less active than normal cells as suggested by a significant reduction in serum levels of cross-linked carboxyterminal telopeptides of type I collagen (CTX) and a reduction in bone TRACP activity. Conversely, the female LXRbeta-/- mice exhibited no change in BMD, presumably because a significant decline in the number of the trabecular osteoclasts was compensated for by an increase in the expression of the osteoclast markers cathepsin K and TRACP. These mice also had a significant decrease in serum CTX, suggesting decreased bone resorption; however, in addition presented with an increase in the expression of osteoblast associated genes, bone formation markers, and serum leptin levels.

CONCLUSIONS

Our findings show that both LXRs influence cellular function within the bone, with LXRalpha having an impact on osteoclast activity, primarily in cortical bone, whereas LXRbeta modulates trabecular bone turnover.

The ratio of circulating osteoprotegerin to RANKL in early rheumatoid arthritis predicts later joint destruction

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease that may result in debilitating joint deformities with destruction of bone and cartilage. Inflammation is still considered the pivotal inducer of both components of joint damage. Results of recent animal studies suggested a prominent contribution of osteoclastic bone resorption that could be dissociated from inflammation. RANKL and its natural decoy receptor, osteoprotegerin (OPG), play key roles in osteoclast activation. In a group of patients with early RA not treated with disease-modifying drugs, we tested the hypothesis that osteoclast activation, reflected by the serum OPG:RANKL ratio at baseline, is negatively associated with progression of bone damage, independent of inflammation.

METHODS

OPG and RANKL levels, together with a parameter of inflammation (first-year time-averaged erythrocyte sedimentation rate [tESR]), were measured in 92 patients with newly diagnosed early active RA who were participants in a randomized study. The tESR and the OPG:RANKL ratio were evaluated for the ability to predict 5-year radiographic progression of joint damage.

RESULTS

The first-year tESR and the OPG:RANKL ratio, as measured at baseline, independently predicted 5-year radiographic progression of joint damage (both P < or = 0.001). Progression of radiographic damage was greatest in patients with a high tESR and a low OPG:RANKL ratio and was lowest in patients with a low tESR and a high OPG:RANKL ratio.

CONCLUSION

This study in patients with early untreated RA is the first to confirm the findings in animal models of arthritis, that radiographic progression of the bone component of joint destruction is dependent on both inflammation (tESR) and osteoclast activation (the OPG:RANKL ratio).

Osteoprotegerin inactivation accelerates advanced atherosclerotic lesion progression and calcification in older ApoE-/- mice

OBJECTIVE

Osteoprotegerin (OPG), a member of the tumor necrosis factor (TNF) superfamily of proteins, plays an important role in bone remodeling and is expressed in both mouse and human atherosclerotic lesions. The current study was designed to assess whether OPG plays a role in the progression and calcification of advanced atherosclerotic lesions in apoE(-/-) mice.

METHODS AND RESULTS

Atherosclerotic lesion area and composition and aortic calcium content were examined in mice deficient in both OPG and apolipoprotein E (OPG(-/-).apoE(-/-) mice) at 20, 40, and 60 weeks of age. Littermate OPG(+/+).apoE(-/-) mice were used as controls. The average cross-sectional area of lesions in the innominate arteries was increased in OPG(-/-).apoE(-/-) mice at 40 and 60 weeks of age. The increase in lesion area was coupled with a reduced cellularity and an increase in connective tissue including laminated layers of elastin. Sixty-week-old OPG(-/-).apoE(-/-) mice also had an increase in the area of calcification of the lesions. There were no differences in markers of plaque stability. In vitro, OPG induced matrix metalloproteinase-9 (MMP-9) activity in macrophages and smooth muscle cells and acted as a survival factor for serum-deprived smooth muscle cells.

CONCLUSIONS

OPG inhibits advanced plaque progression by preventing an increase in lesion size and lesion calcification. OPG may act as a survival factor and may modulate MMP9 production in vascular cells.

The relationship between plasma osteoprotegerin and endothelium-dependent arterial dilation in type 2 diabetes

Osteoprotegerin is a recently identified inhibitor of bone resorption. Recent studies indicate that osteoprotegerin also acts as an important regulatory molecule in the vasculature. The purpose of this study was to investigate the relationship between plasma osteoprotegerin levels and endothelium-dependent arterial dilation in type 2 diabetic patients. The study subjects included 40 newly diagnosed type 2 diabetic patients and 46 healthy subjects. All patients were given insulin therapy for 6 months. Plasma osteoprotegerin concentration was measured in duplicate by a sandwich enzyme-linked immunosorbent assay method, and high-resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia, and after sublingual glyceryltrinitrate. The plasma osteoprotegerin level in patients before treatment was 3.36 +/- 0.32 ng/l, which was significantly higher than that in control subjects (2.38 +/- 0.25 ng/l, P < 0.001). After 6 months of treatment, osteoprotegerin levels decreased markedly (2.83 +/- 0.34 ng/l, P < 0.001). Flow-mediated endothelium-dependent arterial dilation in patients before treatment was 3.21 +/- 0.52%, which was significantly lower than that in control subjects (4.46 +/- 0.56%, P < 0.01), and it improved markedly after 6 months of treatment (4.03 +/- 0.49%, P < 0.01). In multivariate analysis, osteoprotegerin was significantly associated with endothelium-dependent arterial dilation, fasting blood glucose (FBG), HbA(1c) (A1C), and ultrasensitive C-reactive protein (CRP) at baseline (P < 0.01). The absolute changes in osteoprotegerin showed significant correlation with changes in endothelium-dependent arterial dilation, FBG, A1C, and CRP in diabetic patients during the course of treatment (P < 0.01). This study shows that plasma osteoprotegerin levels are elevated in newly diagnosed diabetic patients and are significantly associated with endothelial function.

Serum levels of osteoprotegerin and receptor activator of nuclear factor-kappaB ligand as markers of periprosthetic osteolysis

BACKGROUND

Previous studies have suggested that the balance between receptor activator of nuclear factor-kappaB ligand (RANKL) and its decoy-receptor osteoprotegerin (OPG) in local tissue seems to play a crucial role in the loosening of the total hip replacement. The aim of this study was to evaluate whether the circulating levels of OPG and RANKL, as well as their ratio, could be different in patients with aseptic loosening compared with patients with stable implants.

METHODS

One hundred and twenty-eight subjects were recruited. They included thirty-nine patients with osteoarthritis who had not yet undergone total hip arthroplasty, thirty-three patients who had undergone total hip arthroplasty and had clinically and radiographically stable implants, thirty-six patients with aseptic loosening of total hip arthroplasty components, and twenty healthy volunteers. Serum levels of OPG and RANKL were measured with use of an immunoenzymatic method, and in each individual the OPG-to-RANKL ratio was calculated.

RESULTS

In every group, a significant correlation was detected between OPG concentration and age (r = 0.58, p < 0.0001), especially in individuals older than fifty years, while gender and underlying disease were not found to influence serum levels of the tested parameters. In comparison with the levels in healthy donors and patients with a stable total hip replacement, the serum levels of OPG were increased in the patients who had not yet had an arthroplasty, those with aseptic loosening of a total hip replacement, and those with a cemented total hip replacement. Moreover, the OPG serum level provided good diagnostic accuracy in detecting the implant failure. A correlation was found between the sum of the osteolytic areas seen radiographically around the femoral stem and the RANKL level (r = 0.38, p = 0.02) and the OPG-to-RANKL ratio (r = -0.29, p = 0.04).

CONCLUSIONS

An increase in OPG levels may reflect a protective mechanism of the skeleton to compensate for the osteolytic activity that occurs in severe osteoarthritis and in aseptic loosening. Prospective studies are needed to determine whether serum OPG levels could be used as markers for monitoring the stability of the implant, as well as for predicting aseptic loosening.

LEVEL OF EVIDENCE

Diagnostic study, Level III. See Instructions to Authors for a complete description of levels of evidence.

[Bone and bone related biochemical examinations. Bone and collagen related metabolites. Measurement and clinical role of OPG]

Osteoprotegerin (OPG) has been identified as a novel cytokine that specifically inhibits osteoclastogenesis. OPG acts as a soluble decoy receptor that inhibits the binding of receptor activator of NF-kappaB ligand (RANKL) to its receptor RANK and thus inhibits the proliferation and activation of osteoclasts. Human serum OPG can now be easily measured using a sandwich-type ELISA kit, and the roles of OPG in various diseases have been revealed by clinical studies. These clinical studies have demonstrated that OPG plays an important role in not only metabolic bone diseases but also other diseases such as coronary artery disease, vascular calcification, chronic renal failure and malignancy. Furthermore, OPG may be a useful and novel marker related to the progression or mechanisms of these diseases.

Osteoprotegerin and bone mass in squamous cell head and neck cancer patients

Osteoprotegerin (OPG) is considered one of the main regulators of bone remodeling. Various patterns of serum OPG levels have been described in different types of tumors. We undertook this study to determine serum OPG levels in patients with squamous cell head and neck cancer (SCHNC), analyzing their relationship with other metabolic bone parameters and bone mineral density (BMD), as well as the possible influence of chemotherapy. Forty male patients with localized SCHNC were studied, and their results were compared with those of 40 healthy male controls. The type of treatment followed by each patient was noted. Age, weight, height, and lifestyle habits were recorded; and OPG, Ca(2+), intact parathyroid hormone (iPTH), 25-Hydroxyvitamin D (25OHD) and 1,25-Dihydroxyvitamin D (1,25(OH)(2)D), bone alkaline phosphatase, osteocalcin, and serum C-terminal cross-links telopeptide of type I collagen (ICTP) were determined. Dual-energy X-ray absorptiometry BMD at the lumbar spine, femoral neck, and hip was also measured. Serum OPG was higher in patients than in controls (91.7 +/- 25.8 vs. 77.2 +/- 26.3, P = 0.02). ICTP (a bone resorption marker) was 37% higher in patients (P = 0.007). Bone mass was lower in patients at the lumbar spine, femoral neck, and total hip. Lumbar spine Z-score showed a significant progressive decrease in controls, stage I-III patients, and stage IV patients. Logistic regression analysis showed a significant association between the disease and serum OPG levels, the odds ratio per standard deviation increase of this being 1.9 (95% confidence interval 1.1-3.8, P = 0.04) after adjusting for bone mass and ICTP serum levels, as well as for alcohol and smoking history. Adjustment for alcohol intake and tobacco use did not cancel out BMD differences between patients and controls. Patients with SCHNC show increased OPG serum levels, increased bone resorption, and decreased bone mass. The OPG rise appears to be unrelated to the BMD decrease, and the BMD decrease seems to be, at least in part, independent of smoking and drinking habits. No differences in either OPG or BMD were seen between patients with and without chemotherapy. Further studies are needed to clarify the mechanisms responsible for OPG and BMD changes in SCHNC.

Circulating osteoprotegerin is correlated with lipid profile, insulin sensitivity, adiponectin and sex steroids in an ageing male population

OBJECTIVE

The relationship between osteoprotegerin (OPG) and lipid profile, insulin sensitivity, adipocytokines and sex steroids has been poorly studied and subject to controversy. The purpose of this study was to look at the correlates of OPG in an elderly male population.

DESIGN

One hundred and fifty-one nondiabetic, elderly Lebanese men (age range 50-83) were recruited in this cross-sectional study based on voluntary enrolment.

MEASUREMENTS

In all the subjects, serum OPG levels were measured and related to clinical parameters (age, waist, body mass index (BMI), systolic and diastolic blood pressure), as well as to metabolic and hormonal parameters. The following fasting laboratory measurements were performed: plasma glucose and insulin levels, total cholesterol, triglycerides and HDL cholesterol, adiponectin, leptin, as well as sex steroids (testosterone, SHBG, free androgen index, ooestradiol, DHEAS), GH and IGF-1. QUICKI index was calculated as a measure of insulin sensitivity.

RESULTS

OPG levels were significantly correlated with age (r = 0.28, P < 0.0001) but not with BMI, waist, systolic or diastolic blood pressure. There was a trend towards higher OPG levels in subjects without, compared to subjects with the metabolic syndrome (3.58 +/- 1.28 vs. 3.26 +/- 1.04 pmol/l, P = 0.09). OPG was negatively correlated with fasting glucose and triglyceride levels (r = -0.18, P = 0.031 and r = -0.19, P = 0.02, respectively) and positively correlated with the QUICKI index (r = 0.17, P = 0.033), HDL cholesterol (r = 0.21, P = 0.009) and adiponectin levels (r = 0.27, P = 0.001). No significant correlations were reported with total or LDL cholesterol levels and with leptin levels. After adjustment for age, OPG is still correlated with triglycerides (r = -0.19, P = 0.02), glucose (r = -0.21, P = 0.011) and adiponectin (r = 0.19, P = 0.02). Finally, OPG was positively associated with SHBG (r = 0.31, P < 0.001) and negatively associated with free androgen index (r =-0.346, P < 0.001); both correlations persisted after adjustment for age (r = 0.21, P = 0.009 and r = -0.23, P = 0.005, respectively). No significant correlation was found between OPG and oestradiol levels while a weak negative correlation was demonstrated with DHEAS (r = -0.18, P = 0.025). Also, no significant correlation was found between OPG and GH or IGF-1 values. In a multiple regression analysis with a stepwise model, the main determinants of OPG were free androgen index and adiponectin (P < 0.0001 and P = 0.015, respectively).

CONCLUSION

Our results show that circulating OPG levels are favourably associated with some components of the metabolic syndrome. Also, for the first time, an association between OPG and adiponectin is described. Finally, the negative correlation we found between OPG and free androgen index may suggest a potential role of OPG in the increase in cardiovascular disease related to ageing and sex steroid deficiency.

The relationship between four single nucleotide polymorphisms in the promoter region of the osteoprotegerin gene and aortic calcification or coronary artery disease in Koreans

OBJECTIVE

Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of the NF-kappaB ligand (RANKL). OPG has been shown to be an important inhibitor of osteoclastogenesis and arterial calcification in animal models. OPG has been proposed as a link molecule between osteoporosis and arterial calcification, but the relationship between the OPG gene and the cardiovascular system in human populations is unclear. Thus, the aim of this study was to investigate the relationship between OPG gene polymorphisms and aortic calcification or coronary artery disease in Koreans.

DESIGN AND PATIENTS

Genotyping of four polymorphisms, A163G, G209A, T245G and T950C, in the promoter region of the OPG gene was performed in 251 healthy Korean women (mean age 51.3 +/- 6.9 years) and in a second study population consisting of 100 patients who underwent coronary angiography (mean age 57.0 +/- 11.9 years), by allelic discrimination using the 5' nuclease polymerase chain reaction assay. Cardiovascular risk factors and serum OPG levels were measured and aortic calcification in thoracic and abdominal aorta was examined by simple radiological methods.

RESULTS

In the first study population, the prevalence of aortic calcification increased significantly as the subjects grew older. The frequencies of mutant alleles were significantly higher in the subjects with aortic calcification compared with those without aortic calcification in G209A and T950C polymorphisms, although these significances were lost after adjustment for age. No significant relationship was found between OPG gene polymorphisms and serum OPG levels or cardiovascular risk factors. In the second study group, there were no associations between OPG promoter genotypes and aortic calcification, serum OPG levels, or coronary artery disease.

CONCLUSIONS

We observed that the four polymorphisms in the promoter region of the OPG gene were not associated with aortic calcification or coronary artery disease in Koreans. Further studies are needed to clarify this relationship.

Altered osteoprotegerin/RANKL ratio and low bone mineral density in celiac patients on long-term treatment with gluten-free diet

Skeletal demineralization and mineral metabolism derangement are well-recognized features of untreated celiac disease (CD). Although treatment with a gluten-free diet appears to prevent bone loss while correcting skeletal demineralization in childhood, there is evidence that bone mineral density does not return to normal in celiacs diagnosed in adulthood. Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor family, and ligand of receptor activator of NFkB (RANKL) are involved in the process of bone turnover and have been implicated in the pathogenesis of osteoporosis and other metabolic bone diseases. We measured OPG, RANKL, bone mineral density (BMD), and biochemical markers of bone turnover in 32 adult female premenopausal celiac patients on a gluten-free diet, and thirty age-matched healthy women. We correlated the OPG/RANKL ratio with the severity of bone loss. Celiac patients had a mean BMD lower than controls in lumbar spine and in the femoral neck. Serum levels of bone alkaline phosphatase (BAP, marker of bone formation), and urinary excretion of telopeptides of type I collagen (a marker of bone resorption) were significantly higher than in controls. Serum OPG and RANKL levels were significantly higher in CD patients than in controls, while the OPG/RANKL ratio was significantly lower in CD patients than in controls and was positively correlated with BMD at the spine. The role of elevated OPG in CD patients is unclear, but it might represent a compensatory mechanism against other factors that promote bone damage. Further studies are required to assess a possible therapeutic potential of osteoprotegerin in optimally treated celiacs with persistent osteopenia.

Serum levels of osteoprotegerin and osteoprotegerin polymorphisms in Gaucher disease

Bone involvement in Gaucher disease causes disability and reduced quality of life; loss of function and pain are important indications for enzyme replacement therapy. The purpose of this study was to ascertain whether osteoprotegerin (OPG), which decreases osteoclast activity, is indicative of incipient bone involvement by comparing OPG serum levels to Gaucher disease severity (SSI) and bone mineral density (BMD), and to correlate bone and disease markers to OPG polymorphisms: OPG1-2(A163G), OPG3-4(T129C) and OPG5-6(C1217T). Of 554 patients, 173 Ashkenazi Jewish patients with non-neuronopathic Gaucher disease were enrolled and 32 healthy Ashkenazi Jews served as controls. Serum OPG levels were detected by enzyme-linked immunosorbent assay and BMD was obtained by dual X-ray absorptiometry. OPG polymorphisms were determined in 63 randomly chosen patients. Serum OPG values for patients were not greater than in controls, but showed a statistically significant trend to increase with age (P = 0.057). No correlation existed between OPG levels and BMD or with genotype or other disease markers. A significant correlation was noted between OPG5-6 genotype and SSI. A significant difference was found between the allele distributions of each OPG polymorphism when compared with Caucasians and Ashkenazi Jews. OPG levels probably do not predict BMD in Gaucher disease and hence are not indicative of osteoporosis in Gaucher disease.

Serum osteoprotegerin in young survivors of myocardial infarction

Osteoprotegerin (OPG) is a member of the tumour necrosis factor superfamily and is involved in the regulation of bone metabolism and vascular calcification. Increased serum OPG levels have been reported in patients with stable angina pectoris and survivors of myocardial infarction with heart failure. The purpose of the present study was to determine serum OPG levels in young survivors of acute myocardial infarction (MI), and the relationship between OPG, homocysteine, sCD40L and coagulation factors in blood. Fifty-eight patients with verified MI, 40-60 years of age, were recruited 1-4 years after the acute event into an age- and sex- matched case control study with controls recruited from the general population. Serum OPG levels were similar in cases (2.41 ng/ml, 2.11-2.77 ng/ml) (mean, 95% CI) and controls (2.43 ng/ml, 2.11-2.79 ng/ml) (p = 0.92). Significant correlation between OPG and homocysteine was found in patients (r = 0.30, p = 0.02) and controls (r = 0.35, p = 0.007). A significant negative correlation was found between OPG and sCD40L in patients (r = -0.51, p < 0.001), but not in controls (r = 0.001, p = 0.96). No associations were found between serum OPG and markers of coagulation activation. The present study shows that serum OPG level was not increased in young survivors of uncomplicated myocardial infarction. Serum OPG levels were not associated with thrombin generation assessed by thrombin-antithrombin complexes (TAT), but a positive association between serum OPG and homocysteine was found.

The Relationship Between Plasma Osteoprotegerin Levels and Coronary Artery Calcification in Uncomplicated Type 2 Diabetic Subjects

OBJECTIVES

This study sought to prospectively evaluate the relationship between plasma osteoprotegerin (OPG), inflammatory biomarkers (high-sensitivity C-reactive protein [hs-CRP], interleukin-6 [IL-6], coronary artery calcification (CAC), and cardiovascular events in patients with type 2 diabetes.

BACKGROUND

Arterial calcification is a prominent feature of atherosclerosis and is associated with an increased risk of cardiovascular events. Osteoprotegerin is a cytokine that has recently been implicated in the regulation of vascular calcification.

METHODS

A total of 510 type 2 diabetic patients (53 +/- 8 years; 61% male) free of symptoms of cardiovascular disease were evaluated by CAC imaging. Risk factors, hs-CRP, IL-6, and OPG levels were measured. Patients were followed up for cardiovascular events (cardiac death, myocardial infarction, acute coronary syndrome, late revascularization, and nonhemorrhagic stroke).

RESULTS

Significant CAC (>10 Agatston units) was seen in 236 patients (46.3%); OPG was significantly elevated in patients with increased CAC. In multivariable analyses, OPG retained a strong association with elevated CAC scores after adjustment for age, gender, and other risk factors (odds ratio = 2.84, 95% confidence interval 2.2 to 3.67; p < 0.01). Sixteen cardiovascular events occurred during a mean follow-up of 18 +/- 5 months. The waist-to-hip ratio, United Kingdom Prospective Diabetes Study (UKPDS) risk score, OPG level, and CAC score were significant predictors of time to cardiovascular events in a univariate Cox proportional hazards model. In the multivariate model, the CAC score was the only independent predictor of adverse events. Levels of hs-CRP and IL-6 were related to neither the extent of CAC nor short-term events.

CONCLUSIONS

A high proportion of asymptomatic diabetic patients have significant subclinical atherosclerosis. Of the biomarkers studied, only OPG predicted both subclinical disease and near-term cardiovascular events. Therefore, measurement of OPG merits further investigation as a simple test for identifying high-risk type 2 diabetic patients.

Evaluation of bone mineral density, bone metabolism, osteoprotegerin and receptor activator of the NFkappaB ligand serum levels during treatment with infliximab in patients with rheumatoid arthritis

OBJECTIVES

To examine whether treatment with anti-tumour necrosis factor (TNF) alpha prevents loss of bone mineral density (BMD) at the spine and hip (generalised) and in the hands (local) of patients with rheumatoid arthritis, and to study the changes in markers of bone metabolism, including receptor activator of the NFkappaB ligand (RANKL) and osteoprotegerin (OPG), during anti-TNF treatment.

PATIENTS AND METHODS

102 patients with active rheumatoid arthritis, who were treated with infliximab during 1 year, were included in this open cohort study. The BMD of the spine and hip (dual x ray absorptiometry) and hands dual x ray radiogrammetry was measured before the start of treatment and after 1 year. Changes in osteocalcin formation, beta-isomerised carboxy terminal telopeptide of type 1 collagen (beta-CTx, resorption), RANKL and OPG were determined at 0, 14, 30 and 46 weeks.

RESULTS

The BMD of the spine and hip was unchanged during treatment with infliximab, whereas BMD of the hand decreased significantly by 0.8% (p<0.01). The BMD of the hip in patients with a good European League Against Rheumatism response showed a favourable change compared with patients not achieving such a response. Serum beta-CTx and RANKL were both considerably decreased compared with baseline at all time points. The decrease in beta-CTx was associated with the decrease in Disease Activity Score of 28 joints and C reactive protein during the 0-14 weeks interval.

CONCLUSION

In patients with rheumatoid arthritis treated with infliximab, spine and hip bone loss is arrested, whereas metacarpal cortical hand bone loss is not stopped. The outcome of the study also supports a relationship between clinical response, in terms of reduced inflammatory activity, and changes in bone loss of the spine, hip and hands.

Are activated T cells regulators of bone metabolism in children with Crohn disease?

OBJECTIVES

To test the hypothesis that circulating activated T cells may release cytokines that decrease bone turnover in children with Crohn disease.

STUDY DESIGN

Newly diagnosed Crohn disease and healthy controls of similar age were compared for bone age, bone mineral content and density, markers of bone remodeling, and serum concentration and in vitro T-cell production of receptor activator of nuclear factor kappaB ligand (RANKL), interferon (INF)-gamma, and osteoprotegerin (OPG).

RESULTS

Newly diagnosed children with Crohn disease (n=23) had similar bone mineral density (BMD) z-scores and body mass index as the controls (n=40). Biochemical markers of bone remodeling indicated a state of low bone turnover in the Crohn disease patients compared with controls. Serum OPG (pmol/L; mean+/-SD, median) was higher (4.24+/-1.74, 3.98 vs 3.38+/-0.83, 3.41; P<.05), and serum RANKL (pmol/L) was lower in the Crohn disease patients (0.50+/-0.86, 0.28 vs 1.02+/-1.63, 0.49; P<.01), consistent with decreased bone resorption. Activated T cells from Crohn disease patients produced a higher concentration of INF-gamma (ng/microg protein) than those from controls (20.03+/-26.39, 8.70 vs 9.76+/-14.10, 6.17; P<.05).

CONCLUSIONS

The newly diagnosed children with Crohn disease exhibited reduced bone remodeling, possibly due to T-cell INF-gamma and OPG.

Increased serum osteoprotegerin values in long-lived subjects: different effects of inflammation and bone metabolism

AIM

To evaluate serum osteoprotegerin (OPG) concentrations in relation to age-dependent changes in serum markers of bone metabolism and systemic inflammation.

METHODS

Two-hundred and eighty-three healthy subjects were evaluated for plasma estimated creatinine clearance (Cr-clearance), C-reactive protein (CRP), bone alkaline phosphatase, C-telopeptides of type-1 collagen (CrossLaps), nuclear factor-kappaB ligand (RANKL) and OPG concentrations.

RESULTS

In adult subjects (82 cases aged between 27 and 64 years) serum OPG concentrations were significantly and independently correlated with RANKL and Cr-clearance (R(2): 0.29), but not with CRP and biochemical markers of bone metabolism. In old subjects who were between 65 and 84 years of age (52 cases) serum OPG concentrations were significantly higher as compared with the adult subjects and correlated independently and significantly with serum RANKL, Cr-clearance and CrossLaps values (R(2): 0.63). The highest OPG values were found in the long-lived subjects (149 cases with ages between 85 and 110 years) who also showed increased serum CrossLaps and CRP concentrations as compared with the younger subjects. However, in the long-lived subjects serum OPG concentrations were significantly and independently correlated with Cr-clearance and CRP (R(2): 0.45) but not with CrossLaps values.

CONCLUSIONS

These data would suggest that different factors might be responsible for the age-dependent enhancement of OPG production. Bone metabolism would seem to be the most important factor influencing serum OPG concentrations in old subjects under 85 years of age, whereas in long-lived subjects the circulating values of this cytokine seem to be mainly correlated with serum CRP which could be a marker of inflammation and cardiovascular risk.

Factors other than glucocorticoids are involved in the osteoblast activity decrease caused by tissue injury

OBJECTIVE

Serum osteocalcin is a marker of bone formation. The concentration of osteocalcin is decreased with tissue injury. As glucocorticoids are known both to be increased in this situation and to diminish serum osteocalcin, we have hypothesized that they could be involved in this decrease.

DESIGN AND PATIENTS

We compared osteocalcin levels in two groups of patients undergoing abdominal surgery, one receiving thiopental, and the other etomidate, a glucocorticoid synthesis blocker. For comparative reasons, another protein decreased by glucocorticoids (osteoprotegerin) was measured in patients anaesthetized with thiopental.

MEASUREMENTS

Serum osteocalcin, cortisol and albumin were determined before and over the 24 h following surgery. Serum concentration of osteoprotegerin (OPG) and receptor activator of the nuclear factor kappaB ligand (RANKL) were also determined before and 24 h after surgery in a third group of nine patients who received thiopental for anaesthetic induction.

RESULTS

Cortisol levels were increased in the thiopental group, whereas, as expected, were decreased in etomidate patients. However, serum osteocalcin concentration decreased in a similar way in both groups. Serum OPG and RANKL levels were within the normal range at baseline and did not significantly change after surgery.

CONCLUSIONS

The decrease in serum osteocalcin induced by tissue injury is independent of the increase in cortisol secretion triggered by the latter. In addition, another pharmacologically proven effect of cortisol on bone metabolism, OPG inhibition, could not be demonstrated in the first 24 h following surgery, in spite of the physiological increase in endogenous cortisol secretion taking place in this period.

Serum osteoprotegerin and RANKL levels in chronic alcoholic liver disease

OBJECTIVES

Osteoprotegerin (OPG) is a decoy receptor that binds RANK-ligand (RANKL) and prevents osteoclast activation. Oestrogens, androgens, corticosteroids, parathyroid hormone (PTH), vitamin D, and several cytokines exert their effects on bone modulating the OPG/RANKL system. Since these substances become altered in chronic alcoholic liver disease, we investigated the OPG/RANKL system in alcoholic liver disease, its relation with bone mineral density (BMD) and with several hormones and cytokines.

METHODS

Serum OPG, RANKL, C-terminal cross-linking telopeptide of type 1 collagen, osteocalcin, insulin-like growth factor 1 (IGF-1), 1,25 dihydroxyvitamin D, IL-6, tumour necrosis factor (TNF)-alpha, PTH, estradiol, free testosterone and corticosterone were measured in 77 male alcoholic patients, 25 of them cirrhotics. All these patients underwent assessment of BMD at lumbar spine and left hip by a Hologic QDR-2000 (Waltham, MA) bone densitometer. Nineteen non-drinkers male sanitary workers of similar age served as controls.

RESULTS

Serum OPG levels were higher in patients (12.66 +/- 6.44 pmol/l) than in controls (6.59 +/- 1.58 pml/l, P < 0.005), especially in cirrhotics (15.97 +/- 7.03 pmol/l) vs non-cirrhotics (10.96 +/- 5.45 pmol/l, P < 0.001). Patients also showed higher telopeptide levels (0.60 +/- 0.36 vs 0.20 +/- 0.10 nmol/100 ml, P < 0.001), less IGF-1 [median = 192, interquartile range (IQR) = 46.7-175.99 ng/ml vs 150, IQR = 118.8-239.4 ng/ml, P < 0.001], vitamin D (25.5, IQR = 18.25-35 pg/ml vs 77.89, IQR = 57.48-98.53 pg/ml, P < 0.001) and osteocalcin (1.8, IQR = 1-3.6 ng/ml vs 6.04, IQR = 4.63-8.20 ng/ml, P < 0.001) than controls, but no differences in PTH and RANKL. Patients also showed lower Z-scores than controls at trochanter (-0.36 +/- 1.10 vs 0.26 +/- 0.87 in controls, P = 0.026), intertrochantereal area (-0.56 +/- 1.16 vs 0.46 +/- 1.01, P = 0.001), and total hip (-0.44 +/- 1.12 vs 0.42 +/- 1, P = 0.003). TNF-alpha levels were higher in patients (7.40, IQR = 4.30-17.80 pg/ml) than in controls (5.10, IQR = 4.40-8 pg/ml, P = 0.009), especially in cirrhotics (median = 13.90, IR = 6.10-21.10 pg/ml). OPG levels showed strong correlations with TNF-alpha (rho = 0.57, P < 0.001) and IL-6 (r = 0.62, P < 0.001), but not with BMD. Estradiol levels (31.83 +/- 13.11 pg/ml) were higher and free testosterone lower (13.62 +/- 11.96 pg/ml) in patients than in controls (20.36 +/- 3.08 and 18.19 +/- 4.68 pg/ml, respectively, P < 0.001 in both cases).

CONCLUSION

OPG is raised in alcoholics, especially in cirrhotics, showing no relationship with decreased BMD. Also, raised TNF and IL-6 were observed, and were strongly, directly related with OPG levels. Since TNF and IL-6 enhance bone resorption, their relation with OPG suggests a protective effect of raised OPG on bone loss.

Elevated serum levels of the decoy receptor osteoprotegerin in children with Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is characterized by an accumulation of dendritic Langerhans cells in granulomatous lesions in the bone, skin, and other sites in the body. The pathogenesis of the disease remains unknown. We measured serum levels of the decoy receptor osteoprotegerin (OPG), an important regulator of bone metabolism as well as immune responses, in 18 children with single system (SS) or multi-system (MS) forms of LCH and 20 pediatric controls. OPG levels were significantly increased in LCH patients at diagnosis when compared with controls, and pretreatment levels of OPG were elevated in MS compared with SS patients. Moreover, OPG levels in LCH patients were elevated in patients with involvement of risk organs (liver, lungs, hematopoietic system, or spleen) when compared with patients without risk organ involvement, indicative of an association between OPG values and disease severity. We also observed a positive correlation between serum levels of OPG and tumor necrosis factor (TNF)-alpha, a pro-inflammatory cytokine, at the time of onset of disease. These findings show, for the first time, that serum OPG levels are elevated in LCH patients, and suggest that OPG may play a role in the pathogenesis of this enigmatic disease.

Enhanced T-cell expression of RANK ligand in acute coronary syndrome: possible role in plaque destabilization

OBJECTIVE

Based on its role in inflammation and matrix degradation, we hypothesized a role for osteoprotegerin (OPG), RANK, and RANK ligand (RANKL) in coronary artery disease.

METHODS AND RESULTS

We examined the expression of various members of the OPG/RANKL/RANK axis in patients with stable and unstable angina and in the atherosclerotic lesions of apolipoprotein E-deficient (apoE(-/-)) mice. Our findings were: (1) Serum levels of OPG were raised in patients with unstable angina (n=40), but not in those with stable angina (n=40), comparing controls (n=20); (2) mRNA levels of RANKL were increased in T-cells in unstable angina patients accompanied by increased expression of RANK in monocytes; (3) strong immunostaining of OPG/RANKL/RANK was seen within thrombus material obtained at the site of plaque rupture during acute myocardial infarction; (4) OPG/RANKL/RANK was expressed in the atherosclerotic plaques of apoE(-/-) mice, with RANKL located specifically to the plaques; and (5) RANKL enhanced the release of monocyte chemoattractant peptide-1 in mononuclear cells from unstable angina patients, and promoted matrix metalloproteinase (MMP) activity in vascular smooth muscle cells.

CONCLUSIONS

We show enhanced expression of the OPG/RANKL/RANK system both in clinical and experimental atherosclerosis, with enhanced T-cell expression of RANKL as an important feature of unstable disease.

Plasma osteoprotegerin levels are associated with glycaemic status, systolic blood pressure, kidney function and cardiovascular morbidity in type 1 diabetic patients

OBJECTIVE

The bone-related peptide osteoprotegerin (OPG) has recently been found in increased amounts in the vasculature in diabetes. It is produced by vascular smooth muscle and endothelial cells, and may be implicated in the development of vascular calcifications. OPG is present in the circulation, where increased amounts have been observed in patients with diabetes. In this study, we examined whether plasma OPG is associated with the glycaemic and vascular status of patients with type 1 diabetes.

METHODS

Two gender-, age- and duration-comparable groups of type 1 diabetic patients either with (n = 199) or without (n = 192) signs of diabetic nephropathy were studied. Plasma OPG was determined by an ELISA.

RESULTS

The plasma OPG concentration was significantly higher in patients with nephropathy than those without (3.11 (2.49-3.99) vs 2.57 (2.19-3.21) (median (interquartiles), ng/ml), P < 0.001). Plasma OPG correlated with haemoglobin A1c (HbA1c), systolic blood pressure and age in both groups and, in addition, with kidney function in the nephropathic group. These correlations remained significant in multivariate models. In addition, we found that plasma OPG concentrations were increased among patients with cardiovascular diseases (CVD), both in the normoalbuminuric and the nephropathic groups. The differences between nephropathic and normoalbuminuric, as well as subgroups with and without CVD, could largely be ascribed to changes in HbA1c, age, systolic blood pressure and creatinine.

CONCLUSION

OPG is associated with glycaemic control and CVD in patients with type 1 diabetes, compatible with the hypothesis that OPG is associated with the development of diabetic vascular complications.

Initially elevated osteoprotegerin serum levels may predict a perioperative myocardial lesion in patients undergoing coronary artery bypass grafting

OBJECTIVE

We investigated whether osteoprotegerin (OPG), an important regulator in the genesis of arteriosclerosis and bone formation, is able to identify patients at risk for perioperative myocardial infarction measured as cardiac troponin I (cTNI) and signs of myocardial ischemia in the electrocardiogram after coronary artery bypass grafting (CABG).

DESIGN

Observational study.

SETTING

Post-surgical intensive care unit of a tertiary care center.

PATIENTS

Ninety-seven patients undergoing elective CABG.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

OPG and cTNI were measured before and 24 hrs after CABG. Additionally, cTNI was measured after 12 hrs. Electrocardiography was done before and immediately after CABG. OPG before CABG (OPGpre) measurements correlated with cTNI measurements after 12 hrs (cTNI12) (r = 0.56; p < .0001) and with cTNI measurements after 24 hrs (cTNI24) (r = 0.77; p < .0001). OPGpre measurements correlated with electrocardiographic findings after surgery (r = 0.65; p < .0001). There was a positive correlation between OPGpre value and the number of bypasses (r = 0.95; p < .0001). A strong correlation was found between OPGpre and homocysteine (r = 0.96; p < .0001). The median OPG presurgical level for the four patients with cardiac complications was found to be notably elevated (28.1 [26.6/31.0] pmol/L) in comparison with that for patients without complications (10.2 [3.7/16.9] pmol/L).

CONCLUSIONS

OPG appears to be a useful marker for estimating risk for perioperative myocardial infarction in patients undergoing CABG, as demonstrated by signs of ischemia on electrocardiography.

Plasma levels of receptor activator of nuclear factor-κB ligand and osteoprotegerin in patients with neuroblastoma

Earlier reports showed that the balance between receptor activator of nuclear factor-kappaB ligand (RANKL) and its decoy-receptor osteoprotegerin (OPG) plays an important role in the pathogenesis of metastatic osteolysis induced by neuroblastoma cells. In this study, we investigated whether circulating levels of OPG, RANKL and their ratio were associated to the presence of osteolytic lesions in advanced neuroblastoma, as well as whether they provided additional information on the severity and prognosis of the disease. Plasma levels of RANKL and OPG were measured in 54 newly diagnosed neuroblastomas; 27 of them showed metastatic disease (stage IV), including 19 bone dissemination. Thirty-five children who were admitted to the pediatric department for minor surgical problems served as control group. OPG was significantly lower in all patients compared with controls, while RANKL levels were significantly increased in advanced neuroblastoma. OPG-to-RANKL ratio decreased in stage-IV patients, and particularly in those who had bone metastases. The diagnostic accuracy of the OPG-to-RANKL ratio in discriminating the presence of osteolytic lesions was not confirmed statistically. OPG correlated significantly with other prognostic factors, namely, ferritin and neurone-specific enolase. In addition, an inverse relationship was found between OPG and event-free survival, and it was more significant in patients who had bone metastasis. This pilot study confirms that the production of OPG and RANKL is disregulated in neuroblastoma. Although the OPG-to-RANKL ratio does not have a predictive value in detecting bone metastasis, the measurement of the previously mentioned markers could be useful in decisions regarding the use of adjuvant therapies.

Serum markers of bone turnover in dialyzed patients grouped by level of intact parathyroid hormone

We evaluated serum markers of bone turnover (BT) in patients suspected to have low bone turnover (LBT) given their serum level of intact parathyroid hormone (iPTH). Studies were carried out in 30 dialyzed patients. In 9 patients, iPTH was below 100 pg/mL (LBT group), and in 21, it was above 100 pg/mL (non-LBT group). Other measured laboratory parameters included serum concentrations of cyclase inactivating parathyroid hormone (CAP), osteoprotegerin (OPG), OPG ligand (OPGL), inorganic phosphates, total calcium, creatinine, urea, serum alkaline phosphatase (ALP) activity, and blood pH. The LBT group showed significantly lower levels of iPTH (39.0 +/- 30.7 pg/mL), CAP (23.2 +/- 16.9 pg/mL), cyclase inactive parathyroid hormone (CIP: 15.8 +/- 15.0 pg/mL), and total ALP (83.9 +/- 26.2 IU/L) than did the non-LBT group (393 +/- 304 pg/mL, 268 +/- 216 pg/mL, 126 +/- 96 pg/mL, and 202 +/- 167 IU/L respectively). We observed no significant differences between the groups in the other examined parameters. When results were adjusted for sex, age, and dialysis modality and duration, differences remained significant only for iPTH and CIP. Our data indicate that a serum CIP concentration below 25 pg/mL has a significance similar to that of an iPTH concentration below 100 pg/mL in determining which dialyzed patients likely have LBT.

Circasemidian rather than circadian variation of circulating osteoprotegerin in clinical health

Osteoprotegerin (OPG) serves as a soluble decoy receptor for RANKL to inhibit osteoclast formation and activity. Hormones such as PTH and glucocorticoids have been reported to decrease OPG concentrations, while estrogens, transforming growth factor b, related bone morphogenic factor and thrombopoietin reportedly enhance the OPG production in the osteoblastic and bone stromal cells. Since bone turnover shows a prominent circadian rhythm in laboratory animals and humans, with bone resorption increasing at night, we investigated the time structure of circulating OPG concentrations in a group of nine healthy subjects (six women and three men; in the age range of 26-49 years). Blood samples for OPG determination were collected every 4 h for 24 h on the same day, starting at 08:00 in the morning. Data were analyzed by inferential statistical procedures, including the single and population-mean cosinor. A 12-h component was found to characterize serum OPG concentrations (P = 0.038) with peak concentrations around noon and midnight. No statistically significant circadian rhythm of OPG concentrations could be found by cosinor in our study population. The mean 24-h OPG concentration was higher in women than in men (mean +/- S.E.: 3.13 +/- 0.44 vs. 1.94 +/- 0.26 pmol/l, Student t = 2.325, P = 0.053). Since PTH concentrations also exhibit a bimodal pattern along the 24-h scale, PTH may be tested as a putative determinant of the observed changes in serum concentrations of osteoprotegerin.

Serum levels of osteoprotegerin and RANKL in patients with ST elevation acute myocardial infarction

OPG (osteoprotegerin) has been suggested to have an important role in atherogenesis and vascular calcification. In the present study, we have investigated serum OPG and RANKL (receptor activator of nuclear factor kappaB ligand) concentrations in patients with ST elevation AMI (acute myocardial infarction) and established CAD (coronary artery disease). OPG and RANKL were measured in 58 male patients hospitalized in the coronary care unit with ST elevation AMI, in 52 asymptomatic male patients with an established diagnosis of CAD and in 52 healthy male controls. These last two groups were matched with the AMI patients for age and body mass index. OPG was significantly (P<0.05) higher in patients with AMI at 1 h after AMI (8.04+/-4.86 pmol/l) than in both patients with established CAD (4.92+/-1.65 pmol/l) and healthy subjects (3.15+/-1.01 pmol/l). Subjects with established CAD had significantly (P<0.05) increased OPG levels compared with controls. RANKL levels in patients with established CAD (0.02+/-0.05 pmol/l) and with AMI (0.11+/-0.4 pmol/l) were significantly (P<0.05) lower compared with controls (0.32+/-0.35 pmol/l). In the AMI group, OPG decreased significantly (P<0.05) at 1 and 4 weeks after infarction (8.04+/-4.86 compared with 6.38+/-3.87 and 6.55+/-2.6 pmol/l respectively), but OPG levels, either at 1 h or 1-4 weeks after AMI, remained significantly (P<0.05) higher compared with established CAD (4.92+/-1.65 pmol/l) and controls (3.15+/-1.01 pmol/l). Our data show for the first time that OPG levels are increased in ST elevation AMI within 1 h of infarction. Whether the increase in OPG is a consequence or a causal factor of plaque destabilization deserves further investigation.

Prognostic value of serum markers for prostate cancer

The incidence of prostate cancer has increased dramatically during the last 10-15 years and it is now the commonest cancer in males in developed countries. The increase is mainly caused by the increasing use of opportunistic screening or case-finding based on the use of prostate-specific antigen (PSA) testing in serum. With this approach, prostate cancer is detected 5-10 years before giving rise to symptoms and on average 17 years before causing the death of the patient. While this has led to detection of prostate cancer at a potentially curable stage, it has also led to substantial overdiagnosis, i.e. detection of cancers that would not surface clinically in the absence of screening. A major challenge is thus to identify the cases that need to be treated while avoiding diagnosing patients who will not benefit from being diagnosed and who will only suffer from the stigma of being a cancer patient. It would be useful to have prognostic markers that could predict which patients need to be diagnosed and which do not. Ideally, it should be possible to measure these markers using non-invasive techniques, i.e. by means of serum or urine tests. As it is very useful for both early diagnosis and monitoring of prostate cancer, PSA is considered the most valuable marker available for any tumor. Although the prognostic value of PSA is limited, measurement of the proportion of free PSA has improved the identification of patients with aggressive disease. Furthermore, the rate of increase in serum PSA reflects tumor growth rate and prognosis but, due to substantial physiological variation in serum PSA, reliable estimation of the rate of PSA increase requires follow-up for at least 2 years. Algorithms based on the combined use of free and total PSA and prostate volume in logistic regression and neural networks can improve the diagnostic accuracy for prostate cancer, and assays for minor subfractions of PSA and other new markers may provide additional prognostic information. Markers of neuroendocrine differentiation are useful for the monitoring of androgen-independent disease and various bone markers are useful in patients with metastatic disease.

Alteration of plasma concentrations of OPG before and after levothyroxine replacement therapy in hypothyroid patients

OBJECTIVE

Osteoprotegerin (OPG) is a newly identified inhibitor of bone resorption. Recent studies indicate that OPG also acts as an important regulatory molecule in the vasculature. Hypothyroidism is associated with increased morbidity from cardiovascular disease. More recently, one study showed that plasma OPG increases significantly, and decreases markedly with levothyroxine (L-T4) replacement therapy in patients with overt hypothyroidism (oHT). The purpose of this study was to investigate the alteration of plasma OPG concentrations before and after L-T4 replacement therapy, and its association with endothelium-dependent arterial dilation in patients with oHT and subclinical hypothyroidism (sHT).

MATERIALS AND METHODS

The study subjects included 20 women with oHT, 20 women with sHT, and 20 healthy women. All patients were then given L-T4 therapy individually to maintain all serum free T3 (FT3), free T4 (FT4), and TSH near or within the respective normal ranges. Plasma OPG concentration was measured in duplicate by a sandwich ELISA method.

RESULTS

Plasma OPG levels in oHT and sHT patients before treatment were 3.13 +/- 0.27 and 2.95 +/- 0.24 ng/l, respectively, which were significantly higher than that in controls (2.42 +/- 0.26 ng/l) (p = 0.000). In multivariate analysis, OPG was significantly associated with TSH (r = 0.306, p < 0.05) and endothelium-dependent arterial dilation (r = -0.675, p < 0.01) at baseline. After normalization of thyroid function, OPG levels in both groups decreased markedly (2.53 +/- 0.28, 2.54 +/- 0.21 ng/l) (p = 0.000), and were very close to that in controls. The absolute changes in OPG showed significant positive correlation with the changes in TSH (p < 0.05) and negative correlation with the changes in endothelium-dependent arterial dilation (p < 0.01), and no significant correlation with other parameters in hypothyroid patients during the course of treatment.

CONCLUSION

The plasma OPG levels were significantly increased from hypothyroid patients, and were close to those of control subjects after normalization of thyroid function, indicating that OPG acts as an important regulatory molecule in the vasculature and, particularly, that it may be involved in the development of vascular dysfunction in hypothyroid patients.

The influence of Lys3Asn polymorphism in the osteoprotegerin gene on bone mineral density in Chinese postmenopausal women

The objective was to identify single nucleotide polymorphisms (SNPs) in exons of the osteoprotegerin gene and to analyze the relationship between the SNPs and bone mineral density in postmenopausal women. We used polymerase chain reaction (PCR) and direct sequencing methods to identify SNPs and genotypes in 205 postmenopausal women. BMD at the lumbar spine (L2-4) and femoral neck (FN) were measured by dual-energy X-ray absorptiometry (DEXA). Serum osteocalcin (OC), osteoprotegerin (OPG), receptor activator of nuclear factor kappaB ligand (RANKL) and urinary N-telopeptide of type I collagen (NTx) were also measured. In exon 1 of the OPG gene, we found the Lys3Asn SNP. In 205 postmenopausal women, the Asn-allele frequency was 26.0%, and the distribution of Lys3Asn genotypes was Lys-Lys 56.6%, Lys-Asn 34.6% and Asn-Asn 8.8%, respectively. BMD at the lumbar spine (L2-4) of the Asn-Asn genotype was significantly higher (9.5-12.6%) than Lys-Asn and Lys-Lys genotypes (P=0.012), with evidence for an allele dose effect (P=0.008). Results remained similar after adjustment for age and body mass index. The Lys3Asn polymorphism of the OPG gene alone accounted for 7.7% of the variance of the L2-4 BMD in a multiple regression model. Logistic regression analysis revealed that the OPG genotype Lys-Lys had a 2.7 times (95% CI: 0.83-9.11) greater risk for osteopenia/osteoporosis than the Asn-Asn genotype. The Lys3Asn polymorphism in the OPG gene is associated with L2-4 BMD in postmenopausal women. The Lys-allele is associated with lower BMD and an increased risk for osteoporosis.

Hepatitis C-associated osteosclerosis (HCAO): report of a new case with involvement of the OPG/RANKL system

We report a new case of hepatitis C-associated osteosclerosis (HCAO). The clinical presentation of the patient was an acquired deep severe bone pain with increased serum bone alkaline phosphatase activity (up to 12 times the upper limit of normal), and generalized bone sclerosis, temporally related to the hepatitis C-virus (HCV) infection. We documented in this patient an increase of circulating osteoprotegerin (OPG), and a concentration of circulating receptor activator for nuclear factor-kB ligand (RANKL) below the lower limit of the reference range. The observed abnormalities of the OPG/RANKL system may contribute to the maintenance of the positive balance of bone remodeling that characterizes patients with HCAO.