BACKGROUND: Obstructive sleep apnea-hypopnea syndrome (OSAHS) is associated with a higher prevalence of osteoporosis. However, the underlying mechanisms linking OSAHS with bone loss are still unclear. The aim of this study was to investigate the changes of receptor activator of nuclear factor-κB ligand (RANKL, an osteoclastogenesis-promoting factor) and osteoprotegerin (OPG, the decoy receptor for RANKL), oxidative stress and bone metabolism markers in OSAHS, in order to understand the potential mechanisms underlying bone loss in OSAHS patients. METHODS: Forty-eight male patients with OSAHS, confirmed by polysomnography (PSG) study, were enrolled. Twenty male subjects who were confirmed as not having OSAHS served as the controls. The subjects' bone mineral density (BMD) was assessed in lumbar spine and femoral neck using dual-energy X-ray absorptiometry (DXA). Blood samples were collected from all subjects for measurement of RANKL, OPG, the bone formation marker bone-specific alkaline phosphatase (BAP), the bone resorption marker tartrate-resistant acid phosphatase 5b (TRAP-5b), and total antioxidant capacity (TAOC). RESULTS: The BMD and the T-score of the femoral neck and the lumbar spine were significantly lower in OSAHS patients as compared to the control group (P < 0.05). The serum level of BAP was significantly decreased in the OSAHS group (15.62 ± 5.20 μg/L) as compared to the control group (18.83 ± 5.50 μg/L, t = -2.235, P < 0.05), while the levels of TRAP-5b did not differ between the two groups (t = -1.447, P > 0.05). The serum level of OPG and the OPG/RANKL ratio were lower in the OSAHS group compared to the control group (both P < 0.05). TAOC level was also decreased significantly in the OSAHS group (P < 0.05). Correlation analysis showed that the TAOC level was positively correlated with BAP in the OSAHS group (r = 0.248, P = 0.04), but there were no correlations between TAOC and the BMD or the T-scores. The correlations between the level of OPG (or the OPG/RANKL ratio) and BMD or TAOC did not reach significance. CONCLUSION In OSAHS patients, lower levels of TAOC were associated with decreased bone formation, suggesting a role of oxidative stress in bone loss, while the role of OPG/RANKL imbalance in bone metabolism in OSAHS needs further evaluation.
Absorptiometry, Photon ; Adolescent ; Adult ; Bone Density ; physiology ; Female ; Humans ; Male ; Middle Aged ; NF-kappa B ; blood ; Osteogenesis ; physiology ; Osteoporosis ; blood ; Osteoprotegerin ; blood ; Oxidative Stress ; physiology ; Polysomnography ; Sleep Apnea, Obstructive ; blood ; Young Adult

BACKGROUND: Osteoprotegerin (OPG) plays protective roles against the development of vascular calcification (VC) which greatly contributes to the increased cardiovascular events in patients with chronic kidney disease (CKD). The present study aimed to find the non-traditional, kidney-related cardiovascular risk factors correlated to serum OPG and the effect of serum OPG on the arterial stiffness measured by brachial ankle pulse wave velocity (baPWV) in patients with the pre-dialysis CKD. METHODS: We cross-sectionally analyzed the data from the patients in whom baPWV and the serum OPG were measured at the time of enrollment in a prospective pre-dialysis CKD cohort study in Korea. RESULTS: Along with traditional cardiovascular risk factors such as age, diabetes mellitus, pulse pressure, and baPWV, non-traditional, kidney-related factors such as albuminuria, plasma level of hemoglobin, total CO2 content, alkaline phosphatase, and corrected calcium were independent variables for serum OPG in multivariate linear regression. Reciprocally, the serum OPG was positively associated with baPWV in multivariate linear regression. The baPWV in the 3rd and 4th quartile groups of serum OPG were higher than that in the 1st quartile group after adjustments by age, sex and other significant factors for baPWV in linear mixed model. CONCLUSION: Non-traditional, kidney-related cardiovascular risk factors in addition to traditional cardiovascular risk factors were related to serum level of OPG in CKD. Serum OPG level was significantly related to baPWV. Our study suggests that kidney-related factors involved in CKD-specific pathways for VC play a role in the increased secretion of OPG into circulation in patients with CKD. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01630486
Albuminuria ; Alkaline Phosphatase ; Ankle ; Blood Pressure ; Calcium ; Cohort Studies ; Diabetes Mellitus ; Humans ; Korea ; Linear Models ; Osteoprotegerin* ; Plasma ; Prospective Studies ; Pulse Wave Analysis ; Renal Insufficiency, Chronic* ; Risk Factors* ; Vascular Calcification ; Vascular Stiffness*

OBJECTIVETo investigate the correlation of serum osteoprotegerin (OPG) with the progression of nonalcoholic fatty liver disease (NAFLD) and the noninvasive prediction and diagnosis of nonalcoholic steatohepatitis (NASH).

METHODSA total of 136 patients with NAFLD were enrolled, and their tissue samples for liver biopsy and serum samples obtained at 1 week after liver biopsy were collected; 83 healthy subjects without the symptoms of fatty liver disease proved by ultrasound examination were enrolled as controls. The physiological indicators including height, body weight, and waist circumference were measured, and body mass index was calculated. The biochemical parameters including alanine aminotransferase (ALT), aspartate aminotransferase (AST), AST/ALT, alkaline phosphatase, gamma-glutamyl transferase, total cholesterol, triglyceride (TG), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were measured. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine the serum level of OPG. The rank sum test, chi-square test, t-test, one-way analysis of variance, Spearman correlation analysis, least significant difference test, and receiver operating characteristic (ROC) curve were applied for statistical analysis of various data.

RESULTSSerum OPG level was correlated with AST and TG (P < 0.05), and was highly correlated with hepatocyte fatty degeneration, ballooning degeneration, intralobular inflammation, portal inflammation, and fibrosis degree (P < 0.01). With the increasing NAFLD activity score (NAS), serum OPG level decreased, and there was a highly negative correlation between them (r = -0.928, P < 0.01). Serum OPG level was significantly lower in NASH patients than non-NASH patients. The area under the ROC curve of serum OPG level was 0.963, and according to the Youden index, its optimal sensitivity and specificity were 96.1% and 97.4%, respectively, at an optimal cut-off value of 242.96 ng/L, which suggested a high diagnostic power.

CONCLUSIONIn NASH patients, serum OPG level decreases significantly. Serum OPG level can be used as an independent predictive factor to evaluate NASH and its severity, as well as a noninvasive diagnostic index for NASH.

Alanine Transaminase ; blood ; Alkaline Phosphatase ; blood ; Aspartate Aminotransferases ; blood ; Biopsy ; Body Mass Index ; Case-Control Studies ; Cholesterol ; blood ; Disease Progression ; Enzyme-Linked Immunosorbent Assay ; Fibrosis ; Humans ; Inflammation ; pathology ; Liver ; pathology ; Non-alcoholic Fatty Liver Disease ; blood ; diagnosis ; Osteoprotegerin ; blood ; ROC Curve ; Triglycerides ; blood ; gamma-Glutamyltransferase ; blood

BACKGROUND/AIMS: Osteoprotegerin (OPG) and fetuin-A are vascular calcification regulators that may be related to high cardiovascular (CV) mortality in hemodialysis (HD) patients. We evaluated the relationship between OPG, fetuin-A, and pulse wave velocity (PWV), a marker of vascular stiffness, and determined whether OPG and fetuin-A were independent predictors of CV events in HD patients. METHODS: We conducted a prospective observational study in 97 HD patients. OPG and fetuin-A were measured at baseline and arterial stiffness was evaluated by PWV. All patients were stratified into tertiles according to serum OPG levels. RESULTS: A significant trend was observed across increasing serum OPG concentration tertiles for age, HD duration, systolic blood pressure, cholesterol, triglycerides, and PWV. Multiple linear regression analysis revealed that diabetes (beta = 0.430, p = 0.000) and OPG levels (beta = 0.308, p = 0.003) were independently associated with PWV. The frequency of new CV events was significantly higher in the upper OPG tertiles compared with those in the lower OPG tertiles. In Cox proportional hazards analysis, upper tertiles of OPG levels were significantly associated with CV events (hazard ratio = 4.536, p = 0.011). CONCLUSIONS: Serum OPG, but not fetuin-A, levels were closely associated with increased vascular stiffness, and higher OPG levels may be independent predictors of new CV events in HD patients.
Adult ; Aged ; Biological Markers/blood ; Cardiovascular Diseases/blood/diagnosis/*etiology/mortality/physiopathology ; Female ; Humans ; Kaplan-Meier Estimate ; Linear Models ; Male ; Middle Aged ; Multivariate Analysis ; Osteoprotegerin/*blood ; Predictive Value of Tests ; Prognosis ; Proportional Hazards Models ; Prospective Studies ; Pulse Wave Analysis ; *Renal Dialysis/adverse effects/mortality ; Renal Insufficiency, Chronic/complications/diagnosis/mortality/*therapy ; Risk Factors ; Up-Regulation ; *Vascular Stiffness ; alpha-2-HS-Glycoprotein/analysis

No abstract available.
Cardiovascular Diseases/*etiology ; Female ; Humans ; Male ; Osteoprotegerin/*blood ; *Renal Dialysis ; Renal Insufficiency, Chronic/*therapy ; *Vascular Stiffness

OBJECTIVETo observe the effect of Icariin (ICA) on serum receptor activator of NFkappaB-ligand (RANKL)/osteoprotegerin (OPG) production and bone destruction in type II collagen-induced arthritis (CIA) rats.

METHODSThe CIA rat model was established in all rats, except those in the normal group (n = 8) using bovine type II collagen and complete Freund's adjuvant. Totally 24 CIA rats with arthritis index (AI) > or = 6 were selected and divided into the model group, the methotrexate (MTX) group, and the ICA group according to the AI score, 8 in each group. Normal saline was given to rats in the normal group and the model group by gastrogavage. MTX at the weekly dose of 5 mg/kg was given to rats in the MTX group. ICA at the daily dose of 20 mg/kg was given to rats in the ICA group. All medication lasted for 4 weeks. The AI scores were recorded once a week. Histomorphologic changes of the ankle joint were observed by HE staining. The bone destruction and the osteoporosis of the foot phalanx were detected by X-ray. Serum levels of RANKL and OPG were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTSAfter 4-week intervention, when compared with the model group, AI score and Larsen score were significantly lower, the serum RANKL concentration and the RANKL/OPG ratio obviously decreased, while the serum OPG concentration obviously increased in the CIA group (P < 0.05, P < 0.01). In the MTX group, the aforesaid indices decreased, but without statistical difference (P > 0.05). Results of HE staining indicated that hyperplasia of joint synovium, infiltration of inflammatory cells, and the degree of articular cartilage destruction were obviously alleviated in the ICA group.

CONCLUSIONICA could alleviate or lessen the degree of articular cartilage destruction in CIA rats, and its mechanism might be associated with reducing serum levels of RANKL and elevating levels of OPG, thus further decreasing the ratio of RANKL/OPG.

Animals ; Arthritis, Experimental ; blood ; pathology ; Collagen Type II ; adverse effects ; Female ; Flavonoids ; pharmacology ; Osteoprotegerin ; blood ; RANK Ligand ; blood ; Rats ; Rats, Wistar

OBJECTIVETo study the effects of Zhengqing Fengtongning Tablet (ZFT) and methotrexate (MTX) on the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-kappaB ligand (RANKL), and interleukin 17 (IL-17) in collagen-induced arthritis (CIA) rats, thus addressing their bone protection.

METHODSThe CIA rat model was established by intradermally injecting type II collagen emulsion from the rats' back and tail. Totally 28 successfully modeled rats [with the arthritis index (AI) more than 2] were randomly divided into the model group, the Chinese medicine (CM) treatment group, the MTX group, and the ZFT + MTX treatment group, 7 rats in each group. Another 7 rats were recruited as the normal control group. Rats were administered from the 7th day of modeling. Rats in the MTX group were treated with MTX at 3.8 mg/kg once a week. Those in the CM group were treated with ZFT at the daily dose of 130 mg/kg, once a day. Those in the ZFT + MTX treatment group were treated with both MTX (at 3.8 mg/kg once a week) and ZFT (at the daily dose of 130 mg/kg, once a day). Those in the model group and the normal control group were administered with normal saline of the equal volume by gastrogavage. All the intervention lasted for 26 days. The destruction of joints in the four limbs were observed using X-ray. The AI was recorded. The expression levels of serum OPG, RANKL, and IL-17 were detected at the end of the experiment.

RESULTSDuring the whole process, all rats except those in the model group were in a good condition. On the 21st day of modeling the AI of all rats reached the peak, but it decreased after treatment. Compared with the model group, the AI decreased in the CM treatment group, the MTX group, and the ZFT + MTX treatment group with statistical difference (P < 0.05). Compared with the model group, the OPG increased and RANKL decreased in the MTX group; the OPG and OPG/RANKL increased in the CM treatment group; the OPG, RANKL, and OPG/RANKL increased, and IL-17 decreased in the ZFT + MTX treatment group, all showing statistical difference (P < 0.05). Compared with the MTX and the ZFT + MTX treatment group, OPG/RANKL increased and IL-17 decreased in the ZFT + MTX treatment group (both P < 0.05).

CONCLUSIONZFT + MTX could synergistically elevate peripheral OPG/RANKL and down-regulate IL-17 in CIA model rats.

Animals ; Arthritis, Experimental ; blood ; chemically induced ; drug therapy ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Female ; Interleukin-17 ; blood ; Methotrexate ; pharmacology ; therapeutic use ; Osteoprotegerin ; blood ; RANK Ligand ; blood ; Rats

OBJECTIVE: Angiopoietin-1 (Ang1) is a potent angiogenic factor that can increase synovial angiogenesis and also enhance osteoblast maturation and bone formation. However, its role in rheumatoid arthritis (RA) has not been well documented. Thus, we investigated roles of Ang1 in collagen-induced arthritis (CIA). METHODS: A recombinant adenovirus carrying the gene that encodes either cartilage oligomeric matrix protein (AdCOMP)-Ang1 (a modified form of Ang1) or LacZ (AdLacZ) was injected intravenously into CIA mice. Clinical, radiological, histopathological, and immunofluorescent analyses were performed. Serum levels of receptor activators of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) and expression of osteoblast maturation genes were analyzed. RESULTS: AdCOMP-Ang1-injected mice developed more severe inflammation than the AdLacZ-injected mice. However, there were no significant differences in cartilage damage and bone erosion. More PECAM-1-positive blood vessels were seen in the synovium of the AdCOMP-Ang1-injected mice than in those injected with AdLacZ. Interestingly, a lower number of TRAP-positive osteoclasts were observed in AdCOMP-Ang1-injected CIA mice than in the AdLacZ group when comparing sections obtained from joints showing similar synovial proliferation. The serum OPG/RANKL ratio and expression of osteoblast maturation genes, such as runt-related transcription factor 2, bone sialoprotein, type 1 collagen, osteopontin, and osterix, were significantly upregulated in the AdCOMP-Ang1 group. CONCLUSION: COMP-Ang1 facilitates arthritis onset and increases synovial inflammation, but enhances osteoblast maturation, which in turn inhibits osteoclastogenesis by increasing the OPG/RANKL ratio in CIA. Our results suggest that careful investigation is necessary to delineate the possible therapeutic use of COMP-Ang1 as an adjunctive agent, in combination with anti-inflammatory therapies, for the prevention of bone destruction in RA.
Adenoviridae ; Angiogenesis Inducing Agents ; Angiopoietin-1 ; Animals ; Arthritis ; Arthritis, Experimental ; Arthritis, Rheumatoid ; Blood Vessels ; Cartilage ; Collagen Type I ; Extracellular Matrix Proteins ; Glycoproteins ; Inflammation ; Integrin-Binding Sialoprotein ; Joints ; Lifting ; Mice ; Osteoblasts ; Osteoclasts ; Osteogenesis ; Osteopontin ; Osteoprotegerin ; Synovial Membrane ; Transcription Factors

OBJECTIVETo observe serum osteoprotegerin (OPG) level in children with nephrotic syndrome (NS) and changes in serum OPG level after glucocorticoid therapy, with the aim of studying the role of OPG in the bone metabolism of children with NS.

METHODSForty-four children with idiopathic NS were randomly selected as the study group, including 24 newly diagnosed, untreated patients and 20 who had relapsed during the process of glucocorticoid reduction (cumulative dose of glucocorticoid 28327±5879 mg/m2). Twenty-three age- and sex-matched healthy children served as the control group. Serum osteoprotegerin (OPG) level was measured using ELISA. Serum N-terminal midfragment of osteocalcin (N-MID osteocalcin) was determined using electrochemical luminescence immunoassays (ECLIA).

RESULTSSerum levels of OPG (211±55 ng/L) and N-MID osteocalcin (46±14 ng/mL) in the untreated NS group were reduced compared with 470±57 ng/L (OPG) and 73±9 ng/ml (N-MID osteocalcin) in the control group (P<0.05). Serum levels of OPG (176±42 ng/L) and N-MID osteocalcin (29±10 ng/mL) in the NS relapsed group were lower than in the untreated NS and control groups (P<0.05).

CONCLUSIONSBone metabolism disorders are found in children with NS. High-doses of glucocorticoid therapy can aggravate these disorders. Serum OPG levels in children with NS may be affected by both the renal disease itself and steroid therapy, suggesting that OPG is expected to become a new biochemical indicator for predicting changes to the bone metabolism of children with NS.

Child ; Glucocorticoids ; pharmacology ; Humans ; Nephrotic Syndrome ; blood ; drug therapy ; Osteocalcin ; blood ; Osteoprotegerin ; blood

OBJECTIVES: To investigate the relationship between single nucleotide polymorphism (SNP)s in Wnt antagonist genes, and production of osteoprotegerin (OPG) and soluble receptor activator of NF-kappaB ligand (sRANKL) by whole blood cells after hormone therapy (HT) in postmenopausal Korean women. MATERIALS AND METHODS: The Dkk1 c.318A>G, Dkk2 c.437G>A, Dkk3 c.1003A>G polymorphisms and sFRP3 c.970C>G, sFRP4 c.958C>A, and c.1019G>A polymorphisms, and sFRP5 c.20G>C polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), direct sequencing, and Taqman assay in 75 postmenopausal Korean women receiving estrogen-progestogen therapy. The production of OPG and sRANKL by lipopolysaccharide-stimulated whole blood cells (WBC) before and after HT of 6 months were also measured. RESULTS: Changes in the production of OPG and sRANKL by lipopolysaccharide-stimulated WBC, and in ratios of sRANKL(x1,000)/OPG after HT of 6 months were not different according to SNPs in Wnt signal pathway genes except Dkk1 c.318A>G SNP. The AA genotype of Dkk1 c.318A>G SNP showed significantly higher changes (p<0.05) in ratios of sRANKL(x1,000)/OPG compared to other genotypes. There were no significant differences in changes in the production of OPG and sRANKL, and in ratios of sRANKL(x1,000)/OPG among combined genotypes of sFRP4 c.958C>A, and c.1019G>A polymorphisms after HT. CONCLUSIONS: Dkk1 c.318A>G SNP are related with changes in ratios of sRANKL(x1,000)/OPG in terms of the production of OPG and sRANKL by lipopolysaccharide-stimulated whole blood cells after HT.
Blood Cells ; Female ; Genotype ; Humans ; NF-kappa B ; Osteoprotegerin ; Polymorphism, Single Nucleotide ; Receptor Activator of Nuclear Factor-kappa B ; Signal Transduction