Association of Serum Osteoprotegerin With Vascular Calcification, and Cardiovascular and Graft Outcomes in Kidney Transplant Patients: Results From the KNOW-KT

BACKGROUND

Vascular calcification and stiffness contribute to increased cardiovascular morbidity in patients with chronic kidney disease. This study investigated associations between serum osteoprotegerin (OPG) levels and vascular calcification or stiffness to assess cardiovascular and graft outcomes in kidney transplant patients.

METHODS

The KoreaN cohort study for Outcome in patients With Kidney Transplantation was a prospective multicenter cohort study. Serum OPG levels were measured at baseline and 3 y after transplantation in 1018 patients. Patients were classified into high and low OPG groups according to median serum OPG levels. The median follow-up duration was 93.5 mo.

RESULTS

The mean age was 45.8 ± 11.7 y and 62.9% were men. Patients with high OPG had significantly higher coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities than those with lower OPG; these parameters remained significant for 5 y after transplantation. The 3-y OPG levels were lower than baseline values ( P  < 0.001) and were positively correlated ( r  = 0.42, P  < 0.001). Multivariate Cox regression analysis showed that high OPG levels were significantly associated with posttransplant cardiovascular events ( P  = 0.008) and death-censored graft loss ( P  = 0.004). Similar findings regarding posttransplant cardiovascular events ( P  = 0.012) and death-censored graft loss ( P  = 0.037) were noted in patients with high OPG at the 3-y follow-up. Mediation analyses revealed that coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities could act as mediators between serum OPG levels and posttransplant cardiovascular events.

CONCLUSIONS

Serum OPG concentration is associated with vascular calcification and stiffness and could be a significant risk factor for cardiovascular outcomes and graft loss in patients undergoing kidney transplantation.

Circulating osteoprotegerin levels and cardiovascular outcomes in patients with pre-dialysis chronic kidney disease: results from the KNOW-CKD study

While the relationship between circulating osteoprotegerin (OPG) and cardiovascular events is well-established in the general population, its association with cardiovascular risks in chronic kidney disease (CKD) patients remains less robust. This study hypothesized that elevated circulating OPG levels might be associated with an increased risk of major adverse cardiac events (MACE) in CKD patients, a total of 2,109 patients with CKD stages 1 through pre-dialysis 5 from the KNOW-CKD cohort were categorized into quartiles based on serum OPG levels. The primary outcome of the study was 3-point MACE, defined as a composite of nonfatal myocardial infarction, nonfatal stroke, or cardiac death. The median follow-up duration was 7.9 years. The cumulative incidence of 3-point MACE significantly varied across serum OPG levels in Kaplan-Meier curve analysis (P < 0.001, log-rank test), with the highest incidence observed in the 4th quartile. Cox regression analysis indicated that, relative to the 1st quartile, the risk of 3-point MACE was significantly higher in the 3rd (adjusted hazard ratio 2.901, 95% confidence interval 1.009 to 8.341) and the 4th quartiles (adjusted hazard ratio 4.347, 95% confidence interval 1.410 to 13.395). In conclusion, elevated circulating OPG levels are associated with adverse cardiovascular outcomes in pre-dialysis CKD patients.

Plasma TNFRSF11B as a New Predictive Inflammatory Marker of Sepsis-ARDS with Endothelial Dysfunction

Inflammation plays an important role in the development of sepsis-acute respiratory distress syndrome (ARDS). Olink inflammation-related biomarker panels were used to analyze the levels of 92 inflammation-related proteins in plasma with sepsis-ARDS (n = 25) and healthy subjects (n = 25). There were significant differences in 64 inflammatory factors, including TNFRSF11B in sepsis-ARDS, which was significantly higher than that in controls. Functional analysis showed that TNFRSF11B was closely focused on signal transduction, immune response, and inflammatory response. The TNFRSF11B level in sepsis-ARDS plasma, LPS-induced mice, and LPS-stimulated HUVECs significantly increased. The highest plasma concentration of TNFRSF11B in patients with sepsis-ARDS was 10-20 ng/mL, and 10 ng/mL was selected to stimulate HUVECs. Western blot results demonstrated that the levels of syndecan-1, claudin-5, VE-cadherin, occludin, aquaporin-1, and caveolin-1 in TNFRSF11B-stimulated HUVECs decreased, whereas that of connexin-43 increased in TNFRSF11B-stimulated HUVECs. To the best of the authors' knowledge, this study was the first to reveal elevated TNFRSF11B in sepsis-ARDS associated with vascular endothelial dysfunction. In summary, TNFRSF11B may be a new potential predictive and diagnostic biomarker for vascular endothelium damage in sepsis-ARDS.

Bone mineral density in egyptian children with juvenile idiopathic arthritis: possible correlation to serum RANKL / osteoprotegerin (OPG) ratio and OPG gene polymorphisms

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) are at higher risk of decreased bone mineral density (BMD) compared with healthy children due to genetic, disease and medication-related causes. This study aims to investigate the possible effects of osteoprotegerin (OPG) gene polymorphisms and serum levels of osteoprotegerin (OPG) and receptor activator of nuclear factor κB-ligand (RANKL) and RANKL/OPG ratio on BMD in children with JIA.

METHODS

OPG gene rs2073617, rs3134069, serum RANKL, OPG and RANKL/OPG ratio were evaluated in 60 JIA children and 100 matched healthy controls. BMD was evaluated by lumbar dual energy X-ray absorptiometry (DEXA) according to which patients were classified in 2 groups (DEXA z-score above and below - 2). Composite disease activity was measured using the Juvenile Arthritis Disease Activity Score (JADAS) 27-joints. Articular damage was scored using the juvenile arthritis damage index (JADI).

RESULTS

Patients aged 12.05 ± 3.2 years, included 38 females and 31% had BMD z-score below-2. Systemic-onset JIA was the most frequent phenotype (38%). Genotypes and alleles frequencies of the 2 studied polymorphisms did not differ between patients and controls (p > 0.05 for all) while serum RANKL and RANKL/OPG ratio were significantly higher in patients compared to controls (p = < 0.001 and 0.03 respectively). Patients with BMD < -2 had significantly greater frequencies of rs2073617 TT genotype and T allele (p < 0.001), higher serum RANKL, RANKL/OPG ratio (p = 0.01, 0.002), female predominance (p = 0.02), higher articular and extra-articular damage index (p = 0.008,0.009) and more frequent steroid usage (p = 0.02) compared to patients with BMD z-score >-2. Multivariate analysis showed rs2073617 TT genotype, RANKL/OPG ratio, long disease duration (above 36 months) and use of steroid to be associated with decreased BMD (p = 0.03,0.04,0.01,0.01 respectively) in JIA children.

CONCLUSIONS

Egyptian children with JIA have decreased BMD. rs2073617 TT genotype and T allele, RANKL/OPG ratio are possible determinants of reduced BMD in JIA. Our results underline the importance of frequent monitoring of BMD in JIA children and trying to control disease activity to preserve long term bone health.

Soluble CD14 and Osteoprotegerin Associate with Ankle-Brachial Index as a Measure of Arterial Stiffness in Patients with Mild-to-Moderate Chronic Kidney Disease in a Five-Year Prospective Study

INTRODUCTION

Vascular lesions and arterial stiffness appear at early stages of chronic kidney disease (CKD) and follow an accelerated course with disease progression, contributing to high cardiovascular mortality. There are limited prospective data on mechanisms contributing to progression of arterial stiffness in mild-to-moderate CKD (stages 2-3).

METHODS

We applied an affinity proteomics approach to identify candidates of circulating biomarkers with potential impact on vascular lesions in CKD and selected soluble cluster of differentiation 14 (sCD14), angiogenin (ANG), and osteoprotegerin (OPG) for further analysis. We studied their association with ankle-brachial index (ABI) and carotid intima-media thickness, as measures of arteriosclerosis and atherosclerosis, respectively, in 48 patients with CKD stages 2-3, who were prospectively followed and intensively treated for 5 years, and 44 healthy controls.

RESULTS

Concentrations of sCD14 (p < 0.001), ANG (p < 0.001), and OPG (p < 0.05) were higher in patients with CKD 2-3 at baseline, and sCD14 (p < 0.001) and ANG (p < 0.001) remained elevated in CKD patients at follow-up. There were positive correlations between ABI and sCD14 levels (r = 0.36, p = 0.01) and between ABI and OPG (r = 0.31, p = 0.03) at 5 years. The changes in sCD14 during follow-up correlated to changes in ABI from baseline to 5 years (r = 0.41, p = 0.004).

CONCLUSION

Elevated levels of circulating sCD14 and OPG in patients with CKD 2-3 were significantly associated with ABI, a measure of arterial stiffness. An increase in sCD14 over time in CKD 2-3 patients was associated with a corresponding increase in ABI. Further studies are needed to examine if early intensive multifactorial medication to align with international treatment targets may influence cardiovascular outcomes.

Osteoprotegerin, Parathyroid Hormone and Vitamin D as Effective Factors on Serum-Urine Calcium Levels in Breast Cancer Patients

Breast cancer represents one of the most popular kinds of cancer worldwide. During the early stages of the disease, the level of Osteoprotegerin remained within normal limits, showing that the bone was not being damaged to get calcium due to an increase in parathyroid hormone. The current study aimed to assess a number of biochemical variables in a group of women with malignant breast cancer who had reached menopause (less than 45 years old). One hundred thirty women were randomly divided into three groups as follows. The first group (G1) is made up of women who have never had breast cancer or any other disease, and their number (40) corresponds to the same age range (below menopause) as the control group. The second group (G2) comprises women diagnosed with breast cancer at an early stage whose numbers were relatively low (45). The third group (G3) included women of the same age who received one or two doses of chemotherapy and whose total number was (45) over the same period. The variables studied include Vitamin D, Parathyroid Hormone, Osteoprotegerin, blood calcium, and urine calcium, all of that are thought to play a role in the progress of the disease. Vitamin D levels were extremely low in the second group (G2), while they were slightly higher in the third group (G3) but remained extremely low. The first group (G1) maintained parameters within acceptable limits. There was a significant difference between the two breast cancer groups (9.38 1.43) and (4.98 1.67) when compared to the control group (20.04 2.80). (G1). The two breast cancer groups (G2) and (G3) had higher parathyroid hormone levels than the control group (G1), and there was a significant difference between the two breast cancer groups (136.52 58.56) (G3) and (G2) (167.79 35.21) compared to the control group (68.52 20.44) (G1). There was no significant difference in Osteoprotegerin levels between the two breast cancer groups (313.38 109.02) (G3) and (315.0 123.98) (G2) compared to the control group (G1) (324.11 104.73). The three groups' blood calcium levels were all within normal ranges, and there was no statistically significant difference between them (9.21 0.45), (9.23 0.38), and (9.23 0.38) (G3) (9.28 0.43). (G1), but urine-calcium levels were lower in both groups of breast cancer patients compared to the control group, and there was a significant difference between the two breast cancer groups (63.96 15.66) (G3) and (68.42 14.05) (G2) compared to the control group (213.77 63.94) (G1). In breast cancer patients, vitamin D deficiency and high parathyroid hormone levels were discovered, suggesting that vitamin D may play a role in cancer prevention. Osteoprotegerin levels were within normal ranges early in the illness, although this may alter as the patient matures and the disease advances.

Associations of Bone Mineral Density with RANKL and Osteoprotegerin in Arab Postmenopausal Women: A Cross-Sectional Study

Background and objective: There is limited information as to the association of several key bone markers with bone mineral density (BMD) in understudied ethnic groups. This study investigated the relationship between circulating levels of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-Β ligand (RANKL) with BMD in Arab postmenopausal women. Materials and methods: In this cross-sectional study, a total of 617 Saudi postmenopausal women from the Osteoporosis Registry of the Chair for Biomarkers of Chronic Diseases were included. Anthropometric data, BMD, and biochemical data were retrieved from the registry. Participants were stratified into three groups based on T-score; n = 169 with osteoporosis, n = 282 with osteopenia, and n = 166 normal. Analysis of bone markers including RANKL, OPG, osteocalcin, and N-terminal telopeptide (NTx) was completed using commercially available bioassays. Results: The results suggested that OPG was significantly and positively correlated with age in the osteoporosis group (r = 0.29, p < 0.05), while it was inversely correlated with BMD femoral neck left (r = −0.56, p < 0.001) and BMD femoral neck right (r = −0.37, p < 0.05) in the same group. Moreover, RANKL showed a significant inverse correlation with NTx in the osteopenia group (r = −0.37, p < 0.05). Furthermore, the RANKL/OPG ratio had a positive and significant correlation with BMI (r = 0.34, p < 0.05), BMD femoral neck left (r = 0.36, p < 0.05) and BMD femoral neck right (r = 0.35, p < 0.05) in the osteopenia group. By contrast, it showed a significant inverse correlation with waist to hip ratio in the osteoporosis group (r = −0.38, p < 0.05). Multiple regression analysis showed that OPG contributes to BMD variations in the osteopenia group (p = 0.03). Conclusions: In conclusion, changes in circulating levels of RANKL and OPG might be a protective mechanism contrary to the increased bone loss in postmenopausal women.

Patients With Cirrhosis Have Elevated Bone Turnover but Normal Hepatic Production of Osteoprotegerin

CONTEXT

Severe osteodystrophy is common in patients with liver dysfunction. Markers of bone metabolism may help in early diagnosis of osteodystrophy and in understanding underlying pathophysiological mechanisms.

OBJECTIVE

To elucidate changes in bone metabolism associated with cirrhosis and to determine the route of elimination for the markers.

METHODS

Case-control study at a public university hospital. Fifty-nine patients with cirrhosis (47 alcoholic and 12 nonalcoholic cirrhosis) and 20 controls were included. Participants underwent catheterization of the femoral artery, and the hepatic, renal, and femoral veins with collection of blood from all 4 sites. Regional arteriovenous differences in concentrations of bone metabolism markers were determined: procollagen of type I collagen propeptide (PINP), C-terminal cross-linking telopeptide of type I collagen (CTX), osteocalcin, tartrate-resistant acid phosphatase isoform 5b (TRAcP5b), osteoprotegerin (OPG), and sclerostin and correlated with degree of disease (Child-Pugh classification).

RESULTS

PINP concentration was higher (median: 87.9 µg/L) in patients with cirrhosis than in controls (52.6 µg/L) (P = .001), while hepatic extraction was lower (4.3% vs 14.5%) (P < .001). Both CTX and TRAcP5b were higher in patients with cirrhosis (340 ng/L and 3.20 U/L) than in controls (215 ng/L and 1.60 U/L) (P < .001 and P < .0001). Hepatic sclerostin extraction was lower in patients with cirrhosis (14.6%) than in controls (28.7%) (P < .0001). In both groups OPG showed a hepatic release rate (production) of 6%.

CONCLUSION

Patients with cirrhosis have increased bone resorption, but unaltered bone formation. Sclerostin is eliminated through the liver while OPG is produced in the liver. Bone markers may prove useful in evaluating bone turnover in patients with cirrhosis.

The Short-Term Effect of Prunes in Improving Bone in Men

Osteoporosis is a major health concern in aging populations, where 54% of the U.S. population aged 50 and older have low bone mineral density (BMD). Increases in inflammation and oxidative stress play a major role in the development of osteoporosis. Men are at a greater risk of mortality due to osteoporosis-related fractures. Our earlier findings in rodent male and female models of osteoporosis, as well as postmenopausal women strongly suggest the efficacy of prunes (dried plum) in reducing inflammation and preventing/reversing bone loss. The objective of this study was to examine the effects of two doses of prunes, daily, on biomarkers of inflammation and bone metabolism in men with some degree of bone loss (BMD; t-score between −0.1 and −2.5 SD), for three months. Thirty-five men between the ages of 55 and 80 years were randomized into one of three groups: 100 g prunes, 50 g prunes, or control. Consumption of 100 g prunes led to a significant decrease in serum osteocalcin (p < 0.001). Consumption of 50 g prunes led to significant decreases in serum osteoprotegerin (OPG) (p = 0.003) and serum osteocalcin (p = 0.040), and an increase in the OPG:RANKL ratio (p = 0.041). Regular consumption of either 100 g or 50 g prunes for three months may positively affect bone turnover.

Serum concentrations of osteoprotegerin, brain-derived nerve factor, angiotensin II, and endothelin-1 in aging dogs

Background

Gerontology is a major research topic in veterinary medicine; however, there are few reports on changes in biomarker levels in aged dogs.

Aim

The purpose of this preliminary study was to evaluate the differences in serum biomarker levels between young (less than 36 months) and old (over 108 months) companion dogs.

Methods

We measured the serum concentrations of brain-derived neurotrophic factor (BDNF), osteoprotegerin (OPG), angiotensin II (ANGII), and endothelin-1 (ET-1) in both groups (young: n = 16, 19.8 ± 9.3 months old; old: n = 16, 155.8 ± 22.8 months old).

Results

Although the concentrations of BDNF did not differ between the two groups, the OPG, ANGII, and ET-1 levels were significantly higher in the old companion dogs than in the young dogs (p < 0.05).

Conclusion

OPG, ANGII, and ET-1 concentrations may increase in dogs during aging.

Decreased level of soluble receptor activator of nuclear factor-κβ ligand (sRANKL) in overweight and obese children

INTRODUCTION

Childhood obesity contributes to the development of cardiovascular diseases. The molecular pathway - receptor activator of nuclear factor-κβ ligand (RANKL), its receptor RANK and osteoprotegerin (OPG) - takes part not only in bone metabolism but is also involved in the atherosclerosis process. RANKL stimulates osteogenic differentiation and calcification of vascular smooth cells. The associations between the OPG-sRANKL system and various cardiovascular risk factors were displayed. We aimed to evaluate the relationships between serum sRANKL (soluble RANKL) levels and the OPG/sRANKL ratio with cardiometabolic risk factors in overweight and obese children.

MATERIAL AND METHODS

The study included 70 children with overweight and obesity (mean age 13.0 ± 2.8) and 35 age-matched normal weight, healthy peers as a control group. In all patients, anthropometric measurements and laboratory tests were performed. Additionally, an oral glucose tolerance test (OGTT) was made only in overweight and obese children. Atherogenic and insulin resistance indices were calculated.

RESULTS

Overweight and obese children had lower sRANKL levels compared to the control group (median 276.95 vs 325.90, p=0.011), and consequently a higher OPG/sRANKL ratio (0.02 vs 0.01, p = 0.013). The studied children in the lowest quartile of sRANKL levels had higher body weight, Body Mass Index, waist circumference and increased glucose and insulin levels 60 minutes after OGTT and higher uric acid values compared to children in the highest quartile. In multivariable linear regression analysis sRANKL negatively correlated only with uric acid (β = - 0.508, p = 0.041). No association was found for the OPG/sRANKL ratio.

CONCLUSION

Excess fat mass seems to alter the OPG/RANKL ratio mainly by reducing serum sRANKL levels. The correlation between sRANKL and uric acid may suggest a contribution of the OPG-sRANKL system in the cardiometabolic process, but that observation should be confirmed in future studies.

Changes in Serum Dickkopf-1, RANK Ligand, Osteoprotegerin, and Bone Mineral Density after Allogeneic Hematopoietic Stem Cell Transplantation Treatment

BACKGROUND

Dickkopf-1 (DKK1) regulates bone formation by inhibiting canonical Wnt/β-catenin pathway signaling, and indirectly enhances osteoclastic activity by altering the expression ratio of receptor activator of nuclear factor-κB ligand (RANKL) relative to osteoprotegerin (OPG). However, it is difficult to explain continued bone loss after allogeneic stem cell transplantation (allo-SCT) in terms of changes in only RANKL and OPG. Few studies have evaluated changes in DKK1 after allo-SCT.

METHODS

We prospectively enrolled 36 patients with hematologic malignancies who were scheduled for allo-SCT treatment. Serum DKK1, OPG, and RANKL levels were measured before (baseline), and at 1, 4, 12, 24, and 48 weeks after allo-SCT treatment. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry before (baseline) and 24 and 48 weeks after allo-SCT treatment.

RESULTS

After allo-SCT treatment, the DKK1 level decreased rapidly, returned to baseline during the first 4 weeks, and remained elevated for 48 weeks (P<0.0001 for changes observed over time). The serum RANKL/OPG ratio peaked at 4 weeks and then declined (P<0.001 for changes observed over time). BMD decreased relative to the baseline at all timepoints during the study period, and the lumbar spine in female patients had the largest decline (-11.3%±1.6% relative to the baseline at 48 weeks, P<0.05).

CONCLUSION

Serum DKK1 levels rapidly decreased at 1 week and then continued to increase for 48 weeks; bone mass decreased for 48 weeks following engraftment in patients treated with allo-SCT, suggesting that DKK1-mediated inhibition of osteoblast differentiation plays a role in bone loss in patients undergoing allo-SCT.

Serum osteoprotegerin levels, endothelial function and carotid intima-media thickness in type 2 diabetic patients

OBJECTIVES

Osteoprotegerin (OPG), a well-known protein that inhibits osteoclast formation and activity, might also be a potential marker for identifying patients with high cardiovascular risk. This study aimed to compare OPG levels, FMD, and CIMT measurements in subjects with vs. without diabetes and investigate the association of serum osteoprotegerin level with the early atherosclerotic markers, endothelial function, and carotid intima-media thickness (CIMT) in patients with type 2 diabetes mellitus (DM2).

METHODS

Forty-nine patients with DM2 (F/M: 26/23, 49.3 ± 10.0 years) and 45 healthy volunteers (F/M: 26/19, 48.3 ± 7.5 years) were included in this cross-sectional study. Serum OPG levels were measured by solid-phase enzyme-linked immunosorbent assay (ELISA). Fasting plasma glucose (FPG) and HbA1c levels were measured. CIMT was measured by B-mode ultrasound, and endothelial function was evaluated via flow-mediated dilation (FMD) of the brachial artery with Doppler ultrasonography.

RESULTS

Serum OPG levels were significantly higher in patients with DM2 (617.0 ± 111.0 pg/mL) compared to controls (481.0 ± 96.0 pg/mL, p < 0.001). While CIMT in diabetic patients (0.65 + 0.13 mm) was higher than controls (0.54 ± 0.10 mm, p = 0.009), FMD measurement was lower in DM2 group (4.2% ± 3.1 mm vs. 7.6% ± 4.1 mm, p = 0.01). Univariate analysis showed that OPG was associated with the presence of diabetes (OR: 6.999, p = 0.001, R²: 15.1%) and hypertension (OR = 6.925, p = 0.001, R²: 13.2%). There was no relationship between OPG levels and CIMT or FMD.

CONCLUSION

Osteoprotegerin and CIMT levels were increased, and FMD measurements were decreased in patients with DM2. No association between CIMT, FMD, and OPG measurements was observed. The presence of DM and hypertension were associated with circulating OPG levels.

Serum Osteoprotegerin Is an Independent Marker of Metabolic Complications in Non-DialysisDependent Chronic Kidney Disease Patients

BACKGROUND

Osteoprotegerin (OPG) belongs to the tumour necrosis factor superfamily and is known to accelerate endothelial dysfunction and vascular calcification. OPG concentrations are elevated in patients with chronic kidney disease. The aim of this study was to investigate the association between OPG levels and frequent complications of chronic kidney disease (CKD) such as anaemia, protein energy wasting (PEW), inflammation, overhydration, hyperglycaemia and hypertension.

METHODS

One hundred non-dialysis-dependent men with CKD stage 3-5 were included in the study. Bioimpedance spectroscopy (BIS) was used to measure overhydration, fat amount and lean body mass. We also measured the serum concentrations of haemoglobin, albumin, total cholesterol, C-reactive protein (CRP), fibrinogen and glycated haemoglobin (HgbA1c), as well as blood pressure.

RESULTS

We observed a significant, positive correlation between OPG and age, serum creatinine, CRP, fibrinogen, HgbA1c concentrations, systolic blood pressure and overhydration. Negative correlations were observed between OPG and glomerular filtration rate (eGFR), serum albumin concentrations and serum haemoglobin level. Logistic regression models revealed that OPG is an independent marker of metabolic complications such as anaemia, PEW, inflammation and poor renal prognosis (including overhydration, uncontrolled diabetes and hypertension) in the studied population.

CONCLUSION

Our results suggest that OPG can be an independent marker of PEW, inflammation and vascular metabolic disturbances in patients with chronic kidney disease.

Lumbar spine bone mineral density and trabecular bone score-adjusted FRAX, but not FRAX without bone mineral density, identify subclinical carotid atherosclerosis

PURPOSE

Osteoporosis and atherosclerosis share common risk factors. Aim of this study was to test if FRAX (which is an algorithm that can identify subjects at risk of fracture), without or with BMD values, also adjusted for trabecular bone score (TBS) was able to identify subclinical atherosclerosis, evaluated by measurement of carotid intima media thickness (cIMT ≥ 0.9 mm) as compared to DXA values.

METHODS

Ninety postmenopausal women underwent DXA measurement and cIMT evaluation. For each patient, the FRAX algorithm for major osteoporotic fracture (M) and for hip fracture (H) without BMD was computed, together with FRAX with BMD and TBS-adjusted FRAX. Serum levels of osteoprotegerin, sRANKL, and interleukin-6 were also measured.

RESULTS

There were no differences in anthropometric parameters and cardiovascular risk factors between subjects with cIMT ≥ 0.9 mm (35% of subjects, group A) compared to those with cIMT < 0.9 mm (group B). The prevalence of osteoporosis and FRAX BMD, TBS-adjusted FRAX both for M and H were higher in group A compared to group B. The best ROC curves to identify subjects with a cIMT ≥ 0.9 mm were: lumbar spine T-score, with a threshold of - 2.5 SD (area under the curve, AUC 0.64; p = 0.02) with a sensibility of 50% and a specificity of 76%; TBS-adjusted FRAX H with a sensibility of 50% and a specificity of 72% (AUC 0.64; p = 0.01 with a threshold of 3%). Interleukin-6 positively correlated with FRAX BMD H and M.

CONCLUSIONS

FRAX without BMD does not identify subclinical carotid atherosclerosis, while lumbar spine T-score and TBS-adjusted FRAX H similarly detected it with higher specificity for T-score.

Sclerostin and bone remodeling biomarkers responses to whole-body cryotherapy (- 110 °C) in healthy young men with different physical fitness levels

We investigated the effects of single and repeated exposures to whole-body cryotherapy on biomarkers of bone remodeling and osteo-immune crosstalk: sclerostin, osteocalcin (OC), C-terminal cross-linked telopeptide of type I collagen (CTx-I), osteoprotegerin (OPG) and free soluble receptor activator for nuclear factor κ B ligand (sRANKL). The study included 22 healthy males, grouped in high physical fitness level (HPhL) and low physical fitness level (LPhL), all undergone 10 consecutive sessions in a cryogenic chamber (- 110 °C). We observed a significant time-effect on sclerostin (p < 0.05), OC (p < 0.01), CTx-I (p < 0.001), OC/CTx-I (p < 0.05), and significant differences in sRANKL between the groups (p < 0.05) after the 1st cryostimulation; a significant time-effect on OC (p < 0.001) and OC/CTx-I (p < 0.001) after the 10th cryostimulation, and a significant time-effect on CTx-I (p < 0.001) and OC/CTx-I (p < 0.01) after 10 sessions of WBC. In conclusion, in young men, the first exposure to extreme cold induced significant changes in serum sclerostin. The changes in sRANKL, between groups, suggest that fitness level may modify the body's response to cold. The effects of the first stimulus and the whole session are not identical, probably due to the physiological development of habituation to cold.

The Relationship between Serum and Gene Expression Levels of RANK, RANKL and Osteoprotegerin Inflammatory Pathway with Unstable Angina: A Case-control Study

 Osteoprotegerin (OPG), receptor activator of nuclear factor-kappa B (RANK) and receptor activator of nuclear factor-kappa B ligand (RANKL), the members of the tumor necrosis factor (TNF) family, have multiple effects on bone metabolism, endocrine functions and, as an inflammatory pathway, in the immune system. This study tried to determine the association of the OPG/RANKL/RANK axis with the severity of unstable angina (UA) as an inflammatory condition. Our study involved 50 patients with UA and 50 healthy people. Serum and peripheral blood mononuclear cells were isolated from all participants. Serum levels and gene expression of OPG, RANKL, and RANK in mononuclear cells were measured by enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR), respectively. For each patient with UA, the thrombolysis in myocardial infarction (TIMI) and the global registry of acute coronary events (GRACE) scores were determined to evaluate the severity of the disease. Then we analyzed the relation of OPG, RANKL, and RANK levels with TIMI and GRACE scores in patients with UA. Discriminate analysis was used to predict the combinational models of such factors on the prediction of UA. Serum levels of OPG and RANKL (p<0.001) and gene expression of RANKL (p<0.001) were significantly more in patients than those in healthy ones. No relation was seen between the OPG/RANKL/RANK axis and the severity of UA according to TIMI and GRACE scores. Our study shows that serum level, as well as gene expression of OPG/RANKL/RANK axis neither, predicts the occurrence of UA nor shows any relationship with its severity.

Association of bone biomarkers with advanced atherosclerotic disease in people with overweight/obesity

BACKGROUND

A growing body of evidence suggests a potential link between bone metabolism and cardiovascular disease. Aim of this study was to investigate the relationship between levels of circulating bone turnover biomarkers and advanced atherosclerosis.

METHODS

Klotho (KL), sclerostin (SOST), osteopontin (OPN) and osteoprotegerin (OPG) were measured in patients undergoing elective coronary angiography and carotid Doppler ultrasound. The primary outcome was the difference in bone biomarkers levels between participants with and without advanced atherosclerosis, defined as the presence of a critical coronary (≥70%) and/or carotid (≥50%) stenosis.

RESULTS

A total of 80 subjects (32.5% females) with a mean age of 68 ± 10 years were included. Advanced atherosclerosis was detected in 55 (68.8%) patients. Subjects with advanced atherosclerosis showed higher serum levels of OPG (p = 0.0015) and SOST (p = 0.017) and similar levels of KL (p = 0.62) and OPN (p = 0.06) compared to patients without. After adjustment for age and sex, only elevated levels of OPG remained significantly associated with advanced atherosclerosis (p = 0.011).

CONCLUSIONS

Higher serum levels of OPG are independently associated with advanced atherosclerosis confirming a common bond between bone metabolism and vascular disease. Further investigations on the role of selected bone biomarkers in the pathogenesis of cardiovascular disease are needed.

Association between Osteoprotegerin and Charcot Neuroarthropathy: a systematic review

AIMS

Osteoprotegerin (OPG) has been associated with Charcot Neuroarthropathy (CN); however, three studied OPG polymorphisms (1181C > G, 245A > C and 950 T > C) have yielded conflicting results. Therefore, this meta-analysis was conducted to determine the difference in serum OPG concentrations between healthy controls and diabetics with and without CN and the effect OPG polymorphisms have on CN development.

METHODS

PubMed, LILAC, SCOPUS, and EBSCO databases and retrieved publications' bibliographies were searched for studies that examined for OPG and CN. Depending on the heterogeneity, fixed or random effects were used to calculate the pooled odds ratio (OR) or standard difference in means (SDM) with 95% confidence intervals (95%CI) for 5 genetic models (heterozygous, homozygous, dominant, recessive, and allelic) and serum concentrations, respectively.

RESULTS

Seven publications (12 studies) demonstrated that serum OPG concentrations were more elevated in subjects with CN (SDM = 0.719, 95%CI = 0.555-0.883, p < 0.001). When CN was compared to healthy controls or diabetics, the difference was more prominent for healthy controls (SDM = 1.043, 95%CI = 0.676-1.409, p < 0.001) than diabetics (SDM = 0.639, 95%CI = 0.456-0.821, p < 0.001) and the SDM difference was significant (p = 0.013). Using 6 publications (9 studies), neither the 1181C > G or the 950 T > C polymorphisms showed any significant associations for any genetic model. For the 245A > C polymorphism, only the homozygous genetic model showed a significant association between the polymorphism and CN (OR = 2.850, 95%CI: 1.051-7.729, p = 0.040).

CONCLUSIONS

Here, we determined a potential correlation between the CN and serum OPG concentrations and that only the CC genotype of the 245A > C polymorphism showed an increased risk of developing CN.

Serum levels of osteoprotegerin, RANK-L & vitamin D in different stages of osteoarthritis of the knee

BACKGROUND & OBJECTIVES

Osteoarthritis (OA) is the 11^th leading cause of disability in the modern world, but till date, there have been no effective markers for monitoring the progression of OA. The three proteins RANK/RANK-Ligand and Osteoprotegerin (OPG) have been found to be the key regulators of bone metabolism. Interaction of RANK-Ligand with its receptor RANK triggers differentiation of osteoclasts leading to bone resorption. OPG on the other hand is protective as it is expressed by osteoblasts and bind RANKL with higher affinity preventing its interaction with RANK. The levels of these serum proteins are regulated by vitamin D and parathyroid hormones. Therefore, the present study, aimed to study the association of serum RANKL, OPG and vitamin D with disease severity in patients with knee OA.

METHODS

It was a cross-sectional study where 80 (43 women and 37 men) newly diagnosed subjects with OA knee were recruited. They were classified into four grades based on K-L grading and into two groups as early (grade 1+grade 2) and advanced (grade 3 + grade 4) based on the disease progression.

RESULTS

On comparing the biochemical parameters among the four grades decreasing vitamin D levels were seen with increasing severity of knee OA; an increasing trend of RANKL with increase in the severity of OA was seen; OPG was found to be elevated more in the early stages of OA. We also observed a strong association of RANKL/OPG ratio with disease severity.

INTERPRETATION & CONCLUSIONS

Overall the results suggest that OPG may be considered as an early marker of the diseases.

Plasma circulating miR-23~27~24 clusters correlate with the immunometabolic derangement and predict C-peptide loss in children with type 1 diabetes

AIMS/HYPOTHESIS

We aimed to analyse the association between plasma circulating microRNAs (miRNAs) and the immunometabolic profile in children with type 1 diabetes and to identify a composite signature of miRNAs/immunometabolic factors able to predict type 1 diabetes progression.

METHODS

Plasma samples were obtained from children at diagnosis of type 1 diabetes (n = 88) and at 12 (n = 32) and 24 (n = 30) months after disease onset and from healthy control children with similar sex and age distribution (n = 47). We quantified 60 robustly expressed plasma circulating miRNAs by quantitative RT-PCR and nine plasma immunometabolic factors with a recognised role at the interface of metabolic and immune alterations in type 1 diabetes. Based on fasting C-peptide loss over time, children with type 1 diabetes were stratified into the following groups: those who had lost >90% of C-peptide compared with diagnosis level; those who had lost <10% of C-peptide; those showing an intermediate C-peptide loss. To evaluate the modulation of plasma circulating miRNAs during the course of type 1 diabetes, logistic regression models were implemented and the correlation between miRNAs and immunometabolic factors was also assessed. Results were then validated in an independent cohort of children with recent-onset type 1 diabetes (n = 18). The prognostic value of the identified plasma signature was tested by a neural network-based model.

RESULTS

Plasma circulating miR-23~27~24 clusters (miR-23a-3p, miR-23b-3p, miR-24-3p, miR-27a-3p and miR-27b-3p) were upmodulated upon type 1 diabetes progression, showed positive correlation with osteoprotegerin (OPG) and were negatively correlated with soluble CD40 ligand, resistin, myeloperoxidase and soluble TNF receptor in children with type 1 diabetes but not in healthy children. The combination of plasma circulating miR-23a-3p, miR-23b-3p, miR-24-3p, miR-27b-3p and OPG, quantified at disease onset, showed a significant capability to predict the decline in insulin secretion 12 months after disease diagnosis in two independent cohorts of children with type 1 diabetes.

CONCLUSIONS/INTERPRETATIONS

We have pinpointed a novel miR-23a-3p/miR-23b-3p/miR-24-3p/miR-27b-3p/OPG plasma signature that may be developed into a novel blood-based method to better stratify patients with type 1 diabetes and predict C-peptide loss.

The role of serum osteoprotegerin level in diagnosis of disease and determining cardiovascular risk of polycystic ovary syndrome

Objective: Although animal studies claim that osteoprotegerin (OPG) is preventive on this system, there are conflicting results in human studies. The aim of this study was to investigate the role of OPG in the diagnosis and determination of cardivovascular risk in patients with polycystic ovary syndrome (PCOS), which is a multisystem effective disease.Method: The study was performed on 28 premenopausal healthy female volunteers and 57 newly diagnosed PCOS patients in 2017. Anamnesis was obtained, body mass indexes were calculated, laboratory tests required for diagnosis and differential diagnosis of PCOS and suprapubic ovarian ultrasonography were performed, serum OPG level was studied by enzyme-linked immunosorbent assay.Results: OPG levels were similar in PCOS and control groups and there was no significant difference (49.392 ± 10.973 pg/ml vs 49.567 ± 13.57 pg/ml, p = .815). Correlation analysis showed a positive correlation between OPG and total testosterone levels in the PCOS group (r = 0.277, p = .045). No significant relationship with cardiovascular and metabolic parameters was detected.Conclusion: No difference was found between PCOS patients and control groups in terms of OPG levels. Therefore, it is thought that OPG level cannot be used in the diagnosis of the disease. There was no significant relationship between cardiometabolic parameters.

Serum osteoprotegerin level is positively associated with peripheral artery disease in patients with peritoneal dialysis

Osteoprotegerin (OPG) is a potential biomarker of cardiovascular disease complications and severity. Peripheral arterial disease (PAD) is associated with an increased risk of death in patients on peritoneal dialysis (PD). Therefore, this study aimed to evaluate the relationship between serum OPG levels and PAD by measuring the ankle-brachial index (ABI) of patients on PD. A commercial enzyme-linked immunosorbent assay kit was used to measure OPG values. Left or right ABI values of <0.9 were categorized as the low ABI group. Among 70 patients on PD, 13 (18.6%) were categorized in the low ABI group. Patients in the low ABI group had higher prevalence of diabetes mellitus (p = .044) and higher serum C-reactive protein (CRP) (p < .001) and OPG levels (p < .001) but lower creatinine (p = .013) and peritoneal Kt/V (p = .048) levels than those in the normal ABI group. Results of multivariable logistic regression analysis revealed that OPG [adjusted odds ratio (aOR) 1.027, 95% confidence interval (CI) 1.010-1.045, p = .002] and CRP (aOR 1.102, 95% CI 1.006-1.207, p = .037) levels were independent predictors of PAD in patients on PD. OPG can also be used to predict PAD development with the area under the receiver operating characteristic curve of 0.823 (95% CI: 0.714-0.904, p < .001) in patients on PD. Therefore, serum OPG and CRP levels can be considered as risk factors for PAD development in patients on PD.

Osteocalcin and osteoprotegerin levels and their relationship with adipokines and proinflammatory cytokines in children with nonalcoholic fatty liver disease

OBJECTIVES

To investigate the relationship between osteocalcin and osteoprotegerin as bone markers and inflammatory biomarkers such as adiponectin, leptin, tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) in children with nonalcoholic fatty liver disease (NAFLD).

METHODS

This study included 40 obese children with NAFLD as the patient group and 40 healthy obese children of matched age, sex and BMI as the control group. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), fasting blood glucose, fasting insulin, Homeostatic model assessment method of insulin resistance (HOMA-IR), lipid profile, osteocalcin, osteoprotegerin, adiponectin, leptin, TNF-α, and IL-6 were measured in all participants.

RESULTS

Children with NAFLD had a significant decrease in osteocalcin, osteoprotegerin and adiponectin level with a significant increase in TNF-α and IL-6 levels. We also found a significant positive correlation between osteocalcin level and adiponectin levels but a significant negative correlation of osteocalcin with each of leptin and TNF-α. However, there was a significant negative correlation between osteoprotegerin levels and both TNF-α and IL-6 levels. Moreover, adiponectin and TNF-α were significant predictors for osteocalcin, and IL-6 was a significant predictor for osteoprotegerin.

CONCLUSION

Adiponectin, leptin, TNF-α, and IL-6 have potential association with the changes of osteocalcin and osteoprotegerin levels in children with NAFLD.

MMP-8, TRAP-5, and OPG Levels in GCF Diagnostic Potential to Discriminate between Healthy Patients', Mild and Severe Periodontitis Sites

Biomarkers represent promising aids in periodontitis, host-mediate diseases of the tooth-supporting tissues. We assessed the diagnostic potential of matrix metalloproteinase-8 (MMP-8), tartrate-resistant acid phosphatase-5 (TRAP-5), and osteoprotegerin (OPG) to discriminate between healthy patients’, mild and severe periodontitis sites. Thirty-one otherwise healthy volunteers with and without periodontal disease were enrolled at the Faculty of Dentistry, University of Chile. Periodontal parameters were examined and gingival crevicular fluid was sampled from mild periodontitis sites (M; n = 42), severe periodontitis sites (S; n = 59), and healthy volunteer sites (H; n = 30). TRAP-5 and OPG were determined by commercial multiplex assay and MMP-8 by the immunofluorometric (IFMA) method. STATA software was used. All biomarkers showed a good discrimination performance. MMP-8 had the overall best performance in regression models and Receiver Operating Characteristic (ROC) curves, with high discrimination of healthy from periodontitis sites (area under the curve (AUC) = 0.901). OPG showed a very high diagnostic precision (AUC ≥ 0.95) to identify severe periodontitis sites (S versus H + M), while TRAP-5 identified both healthy and severe sites. As conclusions, MMP-8, TRAP-5, and OPG present a high precision potential in the identification of periodontal disease destruction, with MMP-8 as the most accurate diagnostic biomarker.

Association of a single nucleotide polymorphism of RANK gene with blood pressure in Spanish women

In addition to governing key functions in bone metabolism and the immune system, the RANK/RANKL/OPG system plays a role in the vascular system, particularly in vascular calcification and atherosclerosis.Given that these 2 phenotypes are considered a major cause of high blood pressure (BP), in this study we analyzed the association of SNPs in RANK and OPG genes with blood pressure. An observational study was conducted of 2 SNPs in the RANK gene (rs884205 and rs78326403) and 1 in the OPG gene (rs4876869) with systolic (SBP) and diastolic blood pressure (DBP) in a cohort of 695 women.Data analysis revealed a statistically significant association between the SNP rs884205 and BP pressure (SBP and DBP). Analyzing this relationship by the dominant inheritance model for this SNP (allele risk: A), women of the AA/AC genotype showed higher BP than women of the CC genotype, both for SBP (P = .001) and for DBP (P = .003), and these associations both surpassed the Bonferroni threshold for multiple comparisons. Multivariate regression analysis including known predictors of BP as independent variables was performed to evaluate the strength of this association, which in the case of the SNP rs884205 of the RANK gene remained statistically significant after adjustment for both SBP (P = .0006) and DBP (P = .005), demonstrating the key role of this SNP in BP.We report a robust association between the SNP rs884205 in RANK gene and BP in women, and this SNP is validated as a candidate in cardiovascular risk studies.

Comparative study of the effects of osteoprotegerin and testosterone on bone quality in male orchidectomised rats

Aim: The aim of this work is to compare the effects of osteoprotegerin (OPG) and testosterone on bone quality in a model of orchidectomised (ORX) rats.Methods: Three-month-old ORX or SHAM operated groups (n = 15 each group) were used. The SHAM and ORX groups received saline. There were two ORX groups, receiving OPG-Fc (10 mg/kg twice weekly) (ORX + OPG-Fc) or testosterone cypionate (1.7 mg/kg/weekly) for 8 weeks. After sacrifice, bone analysis by femoral and lumbar dual-energy X-ray absorptiometry and micro-computed tomography in femora were performed. Histological sections of vertebrae were dyed with hematoxylin-eosin or safranin. Serum osteocalcin (BGP), total alkaline phosphatase (ALP), and C-terminal telopeptide of type I collagen (CTX) were analyzed.Results: ORX resulted in femoral and vertebral bone loss and in microarchitectural deterioration. Treatment with OPG-Fc and testosterone recovered lumbar (L) and femoral (F) bone mineral densitometry bone mineral density (BMD) to SHAM levels. Femoral BMD was significantly higher after treatment with OPG-Fc than after testosterone treatment due to the presence of osteopetrotic changes in the metaphyseal region of long bones. Serum levels of ALP and CTX increased, while OPG levels were unchanged in ORX rats. Treatment with OPG-Fc decreased the levels of BGP, ALP, and CTX. Treatment with testosterone maintained biochemical markers of bone turnover at levels similar to or higher than those of ORX rats.

Bazedoxifene effects on osteoprotegerin, insulin-like growth factor, tumor necrosis factor and bone mineral density

To observe the clinical effect of estrogenic drugs (Bazedoxifene) on bone targeting in the treatment of osteoporosis and explore its mechanism.

METHODS

112 patients with postmenopausal osteoporosis who received Bazedoxifene drugs in our hospital from January to December 2018 were collected as a study group, and 56 patients treated with calcium alone were collected as a control group. the risk of adverse events such as bone mineral density, osteoprotegerin (OPG), insulin-like growth factor (IGF), tumor necrosis factor (TNF-α), and fracture after treatment were analyzed before and after treatment.

RESULTS

There was no significant difference in the mean lumbar positive position (L2-4) and right femoral neck bone density and OPG, IGF, TNF-α level between the two groups before treatment (P&gt;0.05). The total effective rate of clinical treatment in the study group was 88.39%, the control group was 23.21%, the difference between the two groups was statistically significant (P˂0.05). After treatment, the mean lumbar positive position (L2-4) and the right femoral neck bone density and OPG, IGF in the study group were higher than those in the control group, lower than those in the control group (P&lt;0.05). the occurrence of adverse events such as fracture, spinal deformation and fatigue in the study group after 12 months of treatment was significantly lower than that in the control group (P&lt;0.05), but there was no significant difference in the occurrence of hot flashes and venous thromboembolism between the two groups (P&gt;0.05).

CONCLUSION

Bazedoxifene is an effective drug for the treatment of postmenopausal osteoporosis. It can not only prevent the rapid loss of bone mass, effectively relieve the symptoms of menopause, but also improve bone density and reduce the risk of fracture.

Associations of Bone Turnover Markers with Cognitive Function in Patients Undergoing Hemodialysis

BACKGROUND

Patients undergoing hemodialysis experience a greater risk of cognitive impairment than the general population, but limited data elucidates the biomarkers on this. We evaluated the association of bone turnover markers on cognitive function among 251 prevalent hemodialysis enrollees in a cross-sectional study.

METHODS

251 hemodialysis patients (median age = 57.8, 55% men) and 37 control subjects (mean age = 61.2, 56% men) without a prior stroke or dementia diagnosis were enrolled. Serum concentrations of 8 bone markers were analyzed as the association of cognitive function (Montreal Cognitive Assessment (MoCA) and Cognitive Abilities Screening Instrument (CASI)) using linear regression analysis.

RESULTS

A lower cognitive function was noted in hemodialysis patients compared to control subjects. The receptor activator of nuclear factor kappa-B ligand (RANKL) was the only bone marker found to be associated with cognitive function (MoCA and CASI tests) in hemodialysis patients without a prior stroke or dementia diagnosis. In stepwise multiple linear regression analysis, the association remained significant in MoCA (β = 1.14, 95% CI 0.17 to 2.11) and CASI (β = 3.06, 95% CI 0.24 to 5.88). Short-term memory (β = 0.52, 95% CI 0.01 to 1.02), mental manipulation (β = 0.51, 95% CI 0.05 to 0.96), and abstract thinking (β = 0.57, 95% CI 0.06 to 1.09) were the significant subdomains in the CASI score related to RANKL.

CONCLUSIONS

Serum RANKL levels were potentially associated with better cognitive function in hemodialysis patients. Further large-scale and prospective studies are needed to confirm our findings.

Biomarkers of vascular disease in diabetes: the adipose-immune system cross talk

Experimental and clinical studies aimed at investigating the mechanism(s) underlying vascular complications of diabetes indicate that a great number of molecules are involved in the pathogenesis of these complications. Most of these molecules are inflammatory mediators or markers generated by immune or adipose tissue. Some of them, i.e. resistin and sortilin, have been shown to be involved in the cross talk between adipocytes and inflammatory cells. This interaction is an attractive area of research, particularly in type 2 diabetes and obesity. Other proteins, such as adiponectin and visfatin, appear to be more promising as possible vascular markers. In addition, some molecules involved in calcium/phosphorus metabolism, such as klotho and FGF23, have an involvement in the pathogenesis of diabetic vasculopathy, which appears to be dependent on the degree of vascular impairment. Inflammatory markers are a promising tool for treatment decisions while measuring plasma levels of adipokines, sortilin, Klotho and FGF23 in adequately sized longitudinal studies is expected to allow a more precise characterization of diabetic vascular disease and the optimal use of personalized treatment strategies.

Plasma osteoprotegerin as a biomarker of poor glycaemic control that predicts progression of albuminuria in type 2 diabetes mellitus: A 3-year longitudinal cohort study

AIMS

Poor glycaemic control elevates the risk for vascular complications. Biomarkers for predicting susceptibility to glycaemic worsening are lacking. This 3-year prospective analysis assessed the utility of several circulating diabetes-related biomarkers for predicting loss of glycaemic control, and their contribution to albuminuria progression in type 2 diabetes mellitus (T2DM).

METHODS

T2DM subjects with adequately-controlled diabetes (HbA1c < 8%) at initial recruitment were analysed (N = 859). Baseline plasma levels of osteoprotegerin (OPG), C-reactive protein (CRP), adiponectin, intercellular-cell adhesion molecule-1, and vascular-cell adhesion molecule-1 were quantified using immunoassay. Definitions for development of uncontrolled diabetes and albuminuria progression were HbA1c ≥ 8.0% and increase in albuminuria category at follow-up, respectively.

RESULTS

At follow-up, 185 subjects developed uncontrolled diabetes. Higher baseline CRP and OPG levels were observed in the high-risk individuals, and predicted increased risk for developing uncontrolled diabetes. OPG, but not CRP, was associated with albuminuria progression after multivariable adjustment. The relationship was attenuated following adjustment for development of uncontrolled diabetes, which emerged as a significant associate. Mediation analysis revealed that loss of glycaemic control explained 64.5% of the relationship between OPG and albuminuria progression.

CONCLUSIONS

OPG outperformed other diabetes-related biomarkers to be a potentially useful biomarker for predicting loss of glycaemic control and its associated albuminuria deterioration.

Osteoprotegerin in diabetic osteopathy

AIM

The aim of this study is to evaluate the relationship between OPG and the degree of glycaemic control in a population of elderly subjects.

METHODS AND RESULTS

Data presented included 172 elderly subjects, of whom 107 were hospitalized for a hip fracture and 65 were non fractured outpatients. All participants received a multidimensional geriatric evaluation and underwent blood sampling. HbA1c, OPG, CTX and OC were measured and DXA scans were performed. Carotid intima-media thickness (IMT) was measured in all outpatients. Diabetic patients had more comorbidities, higher mean values of lumbar spine and femoral neck BMD and T-score, lower circulating levels of OC and CTX, and higher circulating levels of OPG compared to non-diabetic subjects. OPG was directly correlated with HbA1c. This association was most evident in non-fractured elderly subjects. Moreover, diabetic patients with IMT>1.5 mm had greater mean values of OPG than non-diabetic subjects with high IMT and than elderly subjects with IMT < 1.5 mm, with and without T2DM.

CONCLUSIONS

Diabetic patients have reduced circulating levels of OC and CTX, and elevated serum levels of OPG, suggesting a state of low bone turnover. Reduced bone turnover causes an increase of BMD and could lead to a poor bone quality. OPG and HbA1c were directly correlated and OPG mean values were higher in diabetic patients with poor glucose control. Diabetic osteopathy could be considered a late complication of T2DM, directly related with the degree of glucose control and the duration of the disease.

IDH2 deficiency increases bone mass with reduced osteoclastogenesis by limiting RANKL expression in osteoblasts

Mitochondria are not only responsible for cellular energy production but are also involved in signaling, cellular differentiation, cell death, and aging. Mitochondrial NADP⁺-dependent isocitrate dehydrogenase (IDH2) catalyzes the decarboxylation of isocitrate to α-ketoglutarate, accompanied by NADPH production. IDH2 plays a central role in mitochondrial function in multiple cell types and various organs, including the heart, kidneys, and brain. However, the function of IDH2 in bone tissue is yet to be elucidated. Here, we report that disruption of IDH2 in mice results in high bone mass due to decreased osteoclast number and resorption activity. Although IDH2 played no cell-intrinsic role in osteoclasts, IDH2-deficient animals showed decreased serum markers of osteoclast activity and bone resorption. Bone marrow stromal cells/osteoblasts from Idh2 knockout mice were defective in promoting osteoclastogenesis due to a reduced expression of a key osteoclastogenic factor, receptor activator of nuclear factor-κB ligand (RANKL), in osteoblasts in vivo and in vitro through the attenuation of ATF4-NFATc1 signaling. Our findings suggest that IDH2 is a novel regulator of osteoblast-to-osteoclast communication and bone metabolism, acting via the ATF4-NFATc1-RANKL signaling axis in osteoblasts, and they provide a rationale for further study of IDH2 as a potential therapeutic target for the prevention of bone loss.

Smoking and other determinants of bone turnover

The balance between bone resorption and formation may be assessed by measurement of bone turnover markers (BTMs), like carboxyl-terminal cross-linked telopeptide of type 1 collagen (CTX-1) and procollagen type 1 amino-terminal propeptide (P1NP). Smoking has been shown to influence bone turnover and to reduce bone mass density (BMD), the exact mechanism for this is, however, not settled. In this post-hoc study including 406 subjects (mean age 51.9 years), we aimed to study the impact of smoking on bone turnover. Moreover, we wanted to assess the inter-correlation between substances regulating bone metabolism and BTMs, as well as tracking over time. BMD measurements and serum analyses of CTX-1, P1NP, osteoprotegerin (OPG), receptor activator of nuclear factor ĸB ligand (RANKL), Dickkopf-1 (DKK1), sclerostin, tumor necrosis factor-α (TNF-α), and leptin were performed. Repeated serum measurements were made in 195 subjects after four months. Adjustments were made for sex, age, body mass index (BMI), smoking status, insulin resistance, serum calcium, parathyroid hormone, 25-hydroxyvitamin D and creatinine. Smokers had higher levels of DKK1 and OPG, and lower levels of RANKL, as reflected in lower BTMs and BMD compared to non-smokers. There were strong and predominantly positive inter-correlations between BTMs and the other substances, and there was a high degree of tracking with Spearman’s rho from 0.72 to 0.92 (P < 0.001) between measurements four months apart. In conclusion, smokers exhibited higher levels of DKK1 and OPG and a lower bone turnover than did non-smokers. The strong inter-correlations between the serum parameters illustrate the coupling between bone resorption and formation and crosstalk between cells.

Evaluating RANKL and OPG levels in patients with Duchenne muscular dystrophy

RANKL-OPG should be explored in DMD patients to potentially provide targeted therapy. We quantified RANKL and OPG levels in DMD patients compared with controls. RANKL, OPG, and RANKL:OPG significantly declined with age in DMD patients suggesting some bone turnover markers are difficult to assess or use as therapeutic indicators.

INTRODUCTION

Osteoporosis in Duchenne muscular dystrophy (DMD) is multi-factorial in nature with high prevalence of fractures. RANKL-OPG should be explored to potentially provide targeted therapy for these patients. We quantified RANKL, OPG, and RANKL:OPG levels in DMD patients compared with controls and analyzed the influence of age, glucocorticoid use, ambulatory status, bone density, and fracture history.

METHODS

DMD patients were enrolled at CHLA. Controls were recruited from general pediatric clinic and in collaboration with samples from a previously completed study. Free soluble RANKL and OPG levels were quantified using a sandwich ELISA.

RESULTS

Fifty DMD patients and 50 controls were enrolled. DMD patients had a significant decline in RANKL, OPG, and RANKL:OPG with age (p = < 0.0001, p = 0.026, and p = 0.002, respectively) while healthy controls showed no significant change. RANKL trended lower in patients on glucocorticoids (p = 0.05), attributed to the significantly older age in the treatment group. RANKL and RANKL:OPG levels were significantly lower in the non-ambulatory group compared with the ambulatory group (p = 0.010 and 0.036 respectively), again likely due to their older age. There was no correlation of RANKL, OPG, or RANKL:OPG with DXA Z-score or presence of vertebral fractures.

CONCLUSION

There was significant decline in RANKL, OPG, and RANKL:OPG with age in DMD patients compared with controls, potentially due to disease severity or worsening osteoblastic function. This suggests some bone turnover markers may be difficult to assess or use as therapeutic indicators in DMD patients. Larger studies are needed to evaluate the role of RANKL-OPG in DMD patients to provide better targeted therapy.

Reproductive and Lifestyle Factors and Circulating sRANKL and OPG Concentrations in Women: Results from the EPIC Cohort

BACKGROUND

Except for a documented increase in osteoprotegerin (OPG) concentrations with older age, data on determinants of soluble Receptor Activator of Nuclear Factor κB (sRANKL) and OPG concentrations in women are limited. We evaluated reproductive and lifestyle factors as potential sources of variation in circulating sRANKL and OPG concentrations in pre- and postmenopausal women.

METHODS

This study includes 2,016 controls [n = 1,552 (76%) postmenopausal, n = 757 (38%) using postmenopausal hormone therapy (PMH)] from a breast cancer case-control study nested in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Serum sRANKL was measured using an ELISA and serum OPG using an electrochemiluminescent assay. Generalized linear models were used to evaluate associations between these analytes and reproductive and lifestyle factors.

RESULTS

Older age at blood collection was associated with lower sRANKL concentrations in postmenopausal women (P trend ≤ 0.03) and higher OPG concentrations in all women (P trend ≤ 0.01). Longer duration of oral contraceptive use among premenopausal women and postmenopausal PMH users was associated with higher OPG (P trend ≤ 0.04). In postmenopausal non-PMH users, sRANKL concentrations were lower with longer duration of oral contraceptive use and current (vs. never) smoking (P ≤ 0.01). sRANKL concentrations were higher among women with higher BMI (P trend ≤ 0.01). The evaluated factors accounted for 12% of the variation in sRANKL concentrations and 21% of the variation in OPG concentrations.

CONCLUSIONS

Circulating sRANKL and OPG concentrations are minimally impacted by hormone-related factors in pre- and postmenopausal women.

IMPACT

This study suggests circulating concentrations of sRANKL and OPG are unlikely to be strongly modified by hormone-related reproductive and lifestyle factors.

Calcification biomarkers and vascular dysfunction in obesity and type 2 diabetes: influence of oral hypoglycemic agents

Vascular aging in obesity and type 2 diabetes (T2D) is associated with progressive vascular calcification, an independent predictor of morbidity and mortality. Pathways for vascular calcification modulate bone matrix deposition, thus regulating calcium deposits. We investigated the association between biomarkers of vascular calcification and vasodilator function in obesity or T2D, and whether antidiabetic therapies favorably impact those markers. Circulating levels of proteins involved in vascular calcification, such as osteopontin (OPN), osteoprotegerin (OPG), regulated on activation, normal T cell expressed and secreted (RANTES), and fetuin-A were measured in lean subjects, individuals with metabolically healthy obesity (MHO), and patients with metabolically unhealthy obesity (MUO) or T2D. Vasodilator function was assessed by infusion of ACh and sodium nitroprusside (SNP). Circulating levels of OPN were higher in the MUO/T2D group than in lean subjects (P < 0.05); OPG and RANTES were higher in MUO/T2D group than in the other groups (both P < 0.001); fetuin-A was not different between groups (P > 0.05); vasodilator responses to either ACh or SNP were impaired in both MUO/T2D and MHO compared with lean subjects (all P < 0.001). In patients with T2D who were enrolled in the intervention trial, antidiabetic treatment with glyburide, metformin, or pioglitazone resulted in a significant reduction of circulating OPG (P = 0.001), without changes in the other biomarkers and vasodilator responses (all P > 0.05). In conclusion, obese patients with MUO/T2D have elevated circulating OPN, OPG, and RANTES; in these patients, antidiabetic treatment reduces only circulating OPG. Further study is needed to better understand the mechanisms of vascular calcifications in obesity and diabetes.

Quantifying RANKL and OPG levels in healthy children: A large cross-sectional analysis

BACKGROUND

There have been new advances in understanding bone remodeling on a molecular level including the RANKL-OPG pathway, leading to advancements in targeted therapeutic intervention. There is however limited data in pediatrics with little known on normative values in healthy children. This is the largest cohort to quantify RANKL, OPG, and RANKL: OPG levels in healthy children as well as study the influence of age, gender, Tanner stage, and BMI in this population.

METHODS

Healthy subjects, 1-21 years of age, were recruited from general pediatric clinics affiliated with CHLA and in collaboration with samples stored from a previously completed study. Healthy children were defined as those with no chronic disease, daily medication, or fractures in the past six months. Free soluble RANKL and OPG levels were quantified using a sandwich ELISA.

RESULTS

Three hundred samples were collected with overall serum concentrations of RANKL, OPG and RANKL: OPG of 0.28 pmol/L, 3.56 pmol/L and 0.08 pmol/L, respectively. Serum RANKL and RANKL: OPG concentrations were significantly different by age (p = 0.0001 and 0.0027, respectively). There was an overall downward trend by age except in the 11-15-year age group where a slight increase was noted. RANKL concentrations were also significantly different between Tanner stages, with highest concentrations seen at Tanner 3 (p = 0.0481), and zBMI (p = 0.001). OPG was inversely correlated with zBMI, but not influenced by gender, age, or Tanner stage.

CONCLUSION

We showed significant difference in RANKL levels by age, Tanner stage, and zBMI. OPG was inversely correlated with zBMI. Insight into circulating levels of RANKL, OPG and RANKL: OPG in healthy children may be a potential tool to better understand disease states in pediatrics. Future studies are needed to evaluate the clinical significance of RANKL and OPG levels for diagnostic and therapeutic purposes in this population.

Circulating Osteoprotegerin Levels Independently Predict All-cause Mortality in Patients with Chronic Kidney Disease: a Meta-analysis

Background: Studies have shown inconsistent results regarding the association between circulating osteoprotegerin (OPG) levels and all-cause mortality in patients with chronic kidney disease (CKD). The aim of this meta-analysis is to investigate the association between circulating OPG levels and all-cause mortality in patients with CKD. Methods: The PubMed, EMBASE and Cochrane Library databases were searched for eligible studies investigating the association between circulating OPG levels and all-cause mortality in patients with CKD. Pooled hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were calculated using a random effects model. Results: In all, 13 studies that included 2,895 patients with CKD were included in this analysis. According to the meta-analysis, patients with the highest circulating OPG level had a significantly higher risk of all-cause mortality (7 studies; the adjusted HR, 1.88; 95% CI, 1.45 - 2.44) compared with patients with the lower circulating OPG level. An increase of 1 pmol/L in the circulating OPG level was associated with a 6% increased risk of all-cause mortality (7 studies; the adjusted HR, 1.06; 95% CI, 1.03-1.10). A subgroup analysis by dialysis methods suggested that an elevated circulating OPG level was independently associated with all-cause mortality in the HD only population. Conclusion: Elevated circulating OPG levels independently predict an increased risk of all-cause mortality in patients with CKD, especially in the HD only population.

Osteoprotegerin and RANKL serum concentrations in neonates of mothers with early-onset pre-eclampsia: comparison with neonates of normotensive mothers

BACKGROUND

Pre-eclampsia is a known risk factor for long-term cardiovascular complications. Osteoprotegerin (OPG) and the receptor activator of nuclear factor κB ligand (RANKL) have been implicated in the pathogenesis of cardiovascular disease. The OPG-RANKL axis function is also altered in pregnant women with pre-eclampsia, but there is lack of data regarding OPG and RANKL concentrations in their neonates.

AIMS

To examine the effects of early-onset pre-eclampsia on OPG and RANKL serum concentrations at birth, taking into account the influence of various perinatal factors.

STUDY DESIGN

OPG and RANKL serum concentrations were measured in 28 premature newborns of mothers with early onset pre-eclampsia, and in 28 preterm and 28 full-term neonates of normotensive mothers (control groups).

RESULTS

Neonates of pre-eclamptic mothers had higher OPG and lower RANKL levels compared to both control groups (Kruskal-Wallis P < 0.0001 and P = 0.014, respectively). Regression analysis showed that pre-eclampsia (P < 0.0001), birth weight z-score (P = 0.048) and antenatal steroid administration (P = 0.034) were significant determinants of OPG levels. Multivariable regression analysis also showed that pre-eclampsia was an independent predictor of increased diastolic and mean blood pressure in these neonates.

CONCLUSIONS

Early-onset pre-eclampsia affects OPG concentrations at birth and is an independent predictor of increased blood pressure in the offspring. Our findings suggest that altered OPG-RANKL axis function may be one of the mechanisms of cardiovascular 'programming' in fetuses exposed to pre-eclampsia.

The Role of Serum Expression Levels of Microrna-21 on Bone Mineral Density in Hypostrogenic Postmenopausal Women with Osteoporosis: Study on Level of RANKL, OPG, TGFβ-1, Sclerostin, RANKL/OPG Ratio, and Physical Activity

BACKGROUND

MiR-21 is known to play a role in osteoclast proliferation and differentiation, but the role of serum miR-21 expression in osteoporosis remains unclear. Previous research found that serum miR-21 expression was positively correlated with bone mineral density in postmenopausal osteoporosis patients, but other factors involved in postmenopausal osteoporosis still unknown. This study aimed to determine the role of serum miR-21 expression, concentration of RANKL, OPG, TGF-β1, sclerostin and serum calcium, RANKL/OPG ratio, and physical activity on bone mineral density of spine in hypoestrogenic postmenopausal women with osteoporosis (PMOP) compared with no osteoporosis (PMNOP), with point of interest on the expression of serum miR-21.

METHODS

this study was conducted by comparative cross-sectional design. The subjects were divided into 2 groups of PMOP and PMNOP. We used an absolute quantification real-time PCR method to determine serum miR-21 expressions level.

RESULTS

Median of serum miR-21 expression at the PMOP group was significantly higher compared to PMNOP group (p = 0.001). Serum miR-21 expression, RANKL, RANKL/OPG ratio, and physical activity were significantly correlated with BMD values in the PMOP group. Moderate physical activity was significantly negatively correlated with serum miR-21 expression. We also obtained a linear regression equation BMD = 1.373-0.085*Ln.miR-21-0.176*Log10.RANKL (R2 = 52.5%).

CONCLUSION

serum miR-21 expression in PMOP was higher compared with PMNOP. Serum miR-21 expression proved to have a negative effect on spinal BMD values in hypoestrogenic postmenopausal women with osteoporosis of 8.5%. Obtained equation of BMD = 1.373-0.085*Ln.miR-21-0.176*Log10.RANKL can explain the value of spinal BMD by 52.5%.

Impaired bone matrix glycoprotein pattern is associated with increased cardio-metabolic risk profile in patients with type 2 diabetes mellitus

PURPOSE

Osteopontin (OPN), osteoprotegerin (OPG) and osteocalcin (OC) are matrix glycoproteins which mediate bone mineralization; moreover, their effects on glucose/insulin homeostasis have recently been demonstrated. Higher circulating OPN and OPG levels have been associated with the presence of insulin resistance, atherosclerosis and coronary heart disease. No data are available on contextual changes of these markers in type 2 diabetes mellitus (T2DM). Therefore, aims of this study were to evaluate serum OPN, OPG and OC levels in T2DM patients and their clinical correlates.

METHODS

We recruited 83 consecutive T2DM patients referring to our diabetes outpatient clinics at Sapienza, University of Rome, and 71 non-diabetic sex and age-comparable subjects as a control group. Study population underwent metabolic characterization and carotid ultrasound for intima-media thickness measurement. Plasma OPN, OPG and OC were measured by MILLIPLEX Multiplex Assays Luminex.

RESULTS

T2DM patients had significantly higher circulating OPN and OPG levels than controls (14.3 ± 13.6 vs 10.6 ± 13.7 ng/ml p < 0.001, 0.70 ± 0.60 vs 0.54 ± 4.1 ng/ml, p = 0.02) while OC levels were similar in the two cohorts (6.35 ± 5.8 vs 7.80 ± 7.0 ng/ml, p = n.s). OPN and OPG positively correlated with greater systolic blood pressure (SBP) values, HOMA-IR and HOMA-β, and with the presence of dyslipidemia and carotid atherosclerosis. The association between greater OPN and OPG levels and SBP was independent from possible confounders (both p = 0.01).

CONCLUSIONS

Circulating OPN and OPG levels are increased in T2DM patients and identify a particularly unfavourable metabolic profile, mostly expressed by higher SBP. Bone peptides may represent novel markers of vascular stress and accelerated atherosclerosis in diabetes, constituting a possible tool for cardiovascular risk stratification in diabetes.

Beneficial effects of (R)-ketamine, but not its metabolite (2R,6R)-hydroxynorketamine, in the depression-like phenotype, inflammatory bone markers, and bone mineral density in a chronic social defeat stress model

Inflammatory bone markers may play a role in the antidepressant actions of (R)-ketamine in susceptible mice after chronic social defeat stress (CSDS). In this study, we compared the effects of (R)-ketamine and its final metabolite (2R,6R)-hydroxynorketamine (HNK) in depression-like phenotypes, inflammatory bone markers and bone mineral density (BMD) in CSDS susceptible mice. We measured plasma levels of inflammatory bone markers, which included osteoprotegerin (OPG), receptor activator of nuclear factor κB ligand (RANKL), and osteopontin after behavioral tests. (R)-ketamine, but not (2R,6R)-HNK, elicited rapid and sustained antidepressant effects in CSDS susceptible mice. Furthermore, (R)-ketamine, but not (2R,6R)-HNK, significantly improved the increased plasma levels of RANKL and decreased OPG/RANKL ratio in CSDS susceptible mice. Moreover, (R)-ketamine, but not (2R,6R)-HNK, significantly attenuated the decreased BMD in CSDS susceptible mice. These findings demonstrate that (R)-ketamine may have beneficial effects in depression-like phenotype and abnormalities in bone functions of CSDS susceptible mice. It is, therefore, likely that (R)-ketamine would be a potential therapeutic drug for abnormalities in bone metabolism in depressed patients.

Association of OPG-RANKL ratio with left ventricular hypertrophy and geometric remodeling in male overweight/obese youths

PURPOSE

Receptor activator of nuclear factor kappa B ligand/receptor activator of nuclear factor kappa B/osteoprotegerin (RANKL/RANK/OPG) axis has been hypothesized as a potential mediator of left ventricular hypertrophy (LVH). The aim of the study was to assess whether circulating concentrations of RANKL, RANK, and OPG were associated with early signs of morphological cardiac changes in overweight/obese youths.

METHODS

We determined serum levels of RANKL, RANK and OPG by enzyme-linked immunosorbent assays in 188 overweight/obese children and adolescents. LV mass index (LVMI) and relative wall thickness (RWT) were estimated using M-mode echocardiography.

RESULTS

OPG and RANKL levels were higher among girls than among boys [1.73 (1.64-1.86) and 3.28 (1.90-6.37) pmol/L, respectively, vs. 1.69 (1.59-1.82) and 2.12 (1.52-3.80) pmol/L; p = 0.02 and p = 0.0001, respectively], but the OPG/RANKL ratio was lower [0.52 (0.26-0.88) vs 0.77 (0.44-1.11); p = 0.001]. In gender-specific multivariate linear regression, OPG/RANKL ratio was associated with LVMI and RWT in boys but not in girls. In multiple logistic regression, after adjustment for clinical variables, OPG/RANKL ratio was associated with concentric remodeling, eccentric and concentric LVH in boys but not in girls.

CONCLUSION

OPG/RANKL ratio is independently associated with LVH and patterns of LV structural remodeling in male overweight/obese children and adolescents.

Genistein and Silicon Synergistically Protects Against Ovariectomy-Induced Bone Loss Through Upregulating OPG/RANKL Ratio

We have reported that genistein (Gen) and silicon (Si) have synergistic effects on ovariectomy-induced bone loss in rat; however, the potential mechanisms behind this effect were not fully clarified yet. This study was performed to evaluate the bone protective mechanisms of concomitant intake of genistein and silicon in ovariectomized rat by OPG/RANKL axis. Three-month-old Sprague-Dawley female rats were subjected to ovariectomy (OVX) or sham surgery; after surgery, the OVX rats were randomly divided into five groups: OVX-Gen, OVX-Si, OVX-Gen-Si, OVX-E, and OVX. Genistein, silicon, and 17β-estradiol supplementation were started after ovariectomy and continued for 10 weeks. The results showed that genistein and silicon treatment increased the bone mineral density (BMD) of ovariectomized rats. In addition, the BMD of the tibia and femur were highest in the OVX-Gen-Si group compared with OVX-Gen and OVX-Si group (p < 0.05). After 10 weeks treatment with genistein and silicon, the bone structure of ovariectomized rats was recovered, there was no difference of bone histomorphometric parameters between OVX-Gen-Si, OVX-E, and SHAM group (p > 0.05), and there was no difference in the concentration of serum ALP, Ca, P, OPG, and RANKL between OVX-Gen-Si, SHAM, and OVX-E groups (p > 0.05). RT-PCR showed that genistein and silicon treatment could effectively increase the OPG mRNA expression and decreased the RANKL mRNA expression compared to that of the OVX group (p < 0.05), the OPG/RANKL mRNA ratios were significantly decreased in the OVX group (p < 0.05), and it was nearly to normal in the OVX-Gen-Si group. Immunohistochemical staining results showed that genistein and silicon supplementation could effectively increase the protein expression of OPG and decrease the protein expression of RANKL in bone tissues; there were no significant differences in OPG and RANKL positive expression areas between OVX-Gen-Si, SHAM, and OVX-E group (p > 0.05). The results above indicate that genistein and silicon supplementation can effectively reduce RANKL, increase OPG levels, and OPG/RANKL ratios in the serum and bone tissue of ovariectomized rats; this is the main mechanism by which genistein and silicon play a bone protective role in ovariectomized rats.

Inverse regulation of serum osteoprotegerin and tumor necrosis factor-related apoptosis-inducing ligand levels in patients with leg lesional vascular calcification: An observational study

We hypothesized that circulating osteoprotegerin (OPG) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) levels could be associated with vascular calcification, which is predominant in diabetes.The study included 71 Korean participants (36 with diabetes and 35 without diabetes), who were sub-grouped according to the results of the ankle-brachial index (ABI) and/or X-ray computed tomography scan (CT scan). Serum OPG and TRAIL levels were assayed using the respective enzyme-linked immunosorbent assay kits. Statistical significance was analyzed using Student's t test between the 2 groups or analysis of variance (ANOVA) among the 4 groups.Serum OPG was up-regulated in the participants with diabetes, with peripheral arterial disease (PAD), and/or with vascular calcification. TRAIL down-regulation was more strictly controlled than OPG up-regulation; it was significantly downregulated in the participants with PAD and vascular calcification, but not in the participants with diabetes. Serum OPG and TRAIL were regulated in the participants with femoral, popliteal, and peroneal artery calcification but not in the participants with aortic calcification.OPG up-regulation and TRAIL down-regulation were found to be associated with leg lesional vascular calcification; therefore, the average OPG/TRAIL ratio was significantly increased by 3.2-fold in the leg lesional vascular calcification group.

Osteoprotegerin increases parallel to insulin resistance in obese adolescents

Purpose/Aim of the Study: Osteoprotegerin (OPG) is an α tumor necrosis factor receptor superfamily glucoprotein that acts as a decoy receptor for the receptor activator of nuclear factor kappa B ligand (RANKL), exerting an antiresoptive bone effect. It was recently shown that OPG/RANKL axis is activated during vascular calcification, contributing to atherosclerotic lesions formation. Additionally, OPG levels are charachterized as an independent risk factor for overall vascular mortality in obese adults. We aimed to investigate OPG levels in children/adolescents with obesity and explore possible relations with obesity-related insulin resistance (IR).

MATERIAL AND METHODS

A total of 160 participants (85 obese) were enrolled. Participants with obesity underwent an oral glucose tolerance test. IR was evaluated according to the homeostasis model assessment-insulin resistance index. Serum OPG levels were determined.

RESULTS

OPG levels did not differ significantly between obese subjects and controls in the total sample (p = 0.133). However, in the adolescents' subgroup, serum OPG levels were significantly increased in obesity (p = 0.019). After stratifying participants according to their IR status, only subjects with both obesity and IR exhibited increased OPG levels compared to controls (p < 0.001). Factor analysis further associated OPG levels variation to insulin levels variation and to IR.

CONCLUSIONS

Obese individuals demonstrate increased serum OPG levels during puberty. Obesity per se is not the potent factor for this increase; indeed, IR accompanying obesity seems to exert a fundamental role in OPG upregulation.

The effect of colostrum intake on osteoprotegerin and bone metabolic markers in the blood of newborn calves during the first week of life

The aim of this study was to elucidate the bone metabolic status after taking colostrum in newborn calves. Fourteen neonatal calves were randomly allocated to two groups fed either unheated or heated (60°C, 30 min) colostrum three times on the first day (2 l every 10 hr; 6 l in total). Heat treatment on colostrum was to reduce the bone metabolic markers assumed as heat-sensitive. The concentrations of four bone metabolic markers (the enzymes from bone cells or the bone collagen fragments) and a bone protective protein, osteoprotegerin (OPG), were measured in the blood of calves during a week after the birth and in the colostrum. The colostral concentrations of four bone metabolic markers were reduced by heating. Then those circulatory markers peaked after colostrum intake in the calves fed unheated colostrum; whereas those fed heated colostrum did not show such changes. However, the plasma tartrate resistant acid phosphatase 5b (TRAP5b) activity was transiently increased after taking colostrum in both groups. Meanwhile, heating did not decrease colostral OPG and there was no significant rise in the serum OPG concentrations after the first colostrum intake in both groups. The study revealed that the blood concentrations of studied bone metabolic markers depended on those colostral values except for TRAP5b. Based on the plasma TRAP5b changes, accelerated formation of premature osteoclast cells may be induced by colostrum intake. Meanwhile, colostral OPG absorption is less likely to impact on its circulating levels.

Expression of bone-related proteins in vascular calcification and its serum correlations with coronary artery calcification score

Since vascular calcification is considered a process regulated similar to that of bone tissue mineralization, we investigated the participation of bone formation proteins. We analyzed the correlation of serum circulating bone markers, osteoprotegerin (OPG) and receptor activator of nuclear factor ĸB ligand (RANKL) in chronic kidney disease (CKD) patients, to coronary artery calcification score. We also considered the effect of inorganic phosphate on pro- and anti-calcifying tissue factors. We confirmed that circulating OPG is an independent calcium score predictor with its high serum concentration favoring high coronary artery calcification. In tissue samples of non-diseased human renal arteries, the expression of OPG and receptor activator of nuclear factor ĸB (RANK) was positive, while expression of RANKL was absent. In atherosclerotic specimens and arteries with medial calcification, the most upregulated was expression of bone morphogenetic proteins, BMP-2 and BMP-7, as well as expression of RANK and RANKL. In the diseased arteries, OPG expression was present only in areas where bone structures were formed. In atherosclerotic and medial calcification arteries, loss of alpha-smooth muscle actin (α-SMA) expression was observed. These data suggest a possible regulatory role of the examined proteins, especially OPG and RANKL, in vascular calcification, as well as their possible clinical significance as circulating predictors of vascular calcification.

[Diagnostic value of serum osteomarkers in moderate and severe periodontal disease]

The purpose of the study was to establish the diagnostic informative value of the concentration of osteomarkers in the serum to assess the severity of the osteodestructive component in chronic generalized periodontitis (HGP) prior to surgery and the prognosis of the effectiveness of surgical treatment of the disease. 187 patients with moderate and severe HGP who underwent bone and plastic insertion during the patch operations were examined. In the blood serum, the concentration of osteoprotegerin, ligand of the soluble activator of the kappa B nucleation factor (sRANKL) was initially determined and at 8 and 12 months after the operation, bone isoenzyme of alkaline phosphatase, osteocalcin, C-terminal telopeptides of degradation of mature type 1 collagen (β-CrossLaps). It was found that in assessing the severity of osteodestructive processes in the periodontium in HGP, the serum concentration of sRANKL and β-CrossLaps is informative. When the sRANKL content in the blood serum exceeds 0,48 pmol/l, and β-CrossLaps exceeds 0,795 ng/ml, it is possible to judge the high activity of osteoclasts, which is accompanied by a pronounced risk of irreversibility of the osteodestructive component and the lack of effectiveness of surgical treatment.