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Most US Food and Drug Administration (FDA)-approved treatments for osteoporosis target osteoclastic bone resorption. Only PTH derivatives improve bone formation, but they have drawbacks, and novel bone-anabolic agents are needed. Nitrates, which generate NO, improved BMD in estrogen-deficient rats and may improve bone formation markers and BMD in postmenopausal women. However, nitrates are limited by induction of oxidative stress and development of tolerance, and may increase cardiovascular mortality after long-term use. Here we studied nitrosyl-cobinamide (NO-Cbi), a novel, direct NO-releasing agent, in a mouse model of estrogen deficiency-induced osteoporosis. In murine primary osteoblasts, NO-Cbi increased intracellular cGMP, Wnt/β-catenin signaling, proliferation, and osteoblastic gene expression, and protected cells from apoptosis. Correspondingly, in intact and ovariectomized (OVX) female C57Bl/6 mice, NO-Cbi increased serum cGMP concentrations, bone formation, and osteoblastic gene expression, and in OVX mice, it prevented osteocyte apoptosis. NO-Cbi reduced osteoclasts in intact mice and prevented the known increase in osteoclasts in OVX mice, partially through a reduction in the RANKL/osteoprotegerin gene expression ratio, which regulates osteoclast differentiation, and partially through direct inhibition of osteoclast differentiation, observed in vitro in the presence of excess RANKL. The positive NO effects in osteoblasts were mediated by cGMP/protein kinase G (PKG), but some of the osteoclast-inhibitory effects appeared to be cGMP-independent. NO-Cbi increased trabecular bone mass in both intact and OVX mice, consistent with its in vitro effects on osteoblasts and osteoclasts. NO-Cbi is a novel direct NO-releasing agent that, in contrast to nitrates, does not generate oxygen radicals, and combines anabolic and antiresorptive effects in bone, making it an excellent candidate for treating osteoporosis. © 2016 American Society for Bone and Mineral Research.

BackgroundChronic kidney disease has emerged as a significant independent risk factor for cardiovascular disease. Cardiovascular calcification is an active process involving a complex interaction of inducers and inhibitors. High sensitivity cardiac troponin T assay detects troponin T with higher sensitivity and precision at an earlier point of time than the conventional assays, and is associated with poor outcomes. Serum osteoprotegerin is classed as an inhibitory factor for cardiovascular calcification. It is involved in the pathological processes of vascular damage and linked to the excess cardiovascular morbidity. The aim of the present study was to evaluate the extent of cardiovascular calcification and serum high sensitivity cardiac troponin T level, and their association with serum osteoprotegerin level in patients with chronic kidney disease stages 3–5.Methods90 chronic kidney disease patients were enrolled in this study, and they were divided into two groups: group (1) included 45 non-dialysis-dependent chronic kidney disease patients (stages 3–5) and group (2) included 45 chronic hemodialysis patients. Each group further subdivided according to the presence of cardiovascular calcification into subgroup A and B. Vascular calcifications were assessed by lateral lumbar, pelvis and hands X-ray radiographs. Valvular calcification was assessed by echocardiography. Serum cardiac troponin T was measured by high sensitivity assay and serum osteoprotegerin was measured by ELISA.ResultsCardiovascular calcification distribution was 22.2% in group (1) and 33.3% in group (2). Serum osteoprotegerin and troponin T in calcification groups (1A and 2A) were significantly higher than non-calcification groups (1B and 2B; P < 0.001). Osteoprotegerin correlated positively with high sensitivity cardiac troponin T (rs = 0.72, P < 0.001). cardiovascular calcification correlated positively with osteoprotegerin, troponin T, and phosphorus. osteoprotegerin and phosphorus were significant independent predictors of cardiovascular calcification at cut-off values ≥4.6 ng/L and ≥6.95 mg/dl, respectively (P < 0.001). Serum phosphorus and creatinine were independent predictors of osteoprotegerin (P < 0.001 and 0.048, respectively).ConclusionOsteoprotegerin is strongly associated with cardiovascular calcification and high sensitivity cardiac troponin T. In addition, there is a positive association between calcification and troponin T. This suggests a role for osteoprotegerin in the pathogenesis and risk stratification of cardiovascular calcification and myocardial injury in chronic kidney disease patients with a potential role as a therapeutic target.

Purpose: There is interest in establishing hypoglycemiant agents able to contain/revert the impact of diabetes mellitus on osseointegration. The purpose of this study was to assess the possible effect of metformin in reversing the negative effects of hyperglycemia on the healing of bone surrounding implants inserted in rats. Materials and Methods: Rats (10 per group) were assigned to one of the following groups: DM group: type 2 diabetic rats deprived of metformin (M) treatment; MDM group: type 2 diabetic rats under M treatment (40 mg/kg/day, starting on the 15th day after implant placement); control group: nondiabetic rats without M treatment. At 30 days after streptozotocin injection, titanium implants were placed in tibiae. Animals were euthanized 30 days after implant surgery. Bone-to-implant contact (BIC), bone area (BA), and the number of receptor activator of nuclear factor κB ligand (RANKL)- and osteoprotegerin (OPG)-stained cells were assessed in cortical and medullary areas. Results: The percentages of BIC and BA in the cortical bone were reduced in the DM and MDM groups compared with the control group (P < .05). The percentage of BA in the medullary region was reduced in the DM group compared with the control group (P < .05). The MDM group showed the greatest number of OPG-stained cells, while the DM group presented the greatest ratio of RANKL/OPG in the medullary area (P < .05). Conclusion: Metformin did not modulate the damaging effect of hyperglycemia on bone healing around implants at histometric levels, but increased the expression of OPG and decreased the RANKL/OPG ratio in the medullary area, yielding some molecular benefits in the osseointegration of implants under the hyperglycemic state. [ABSTRACT FROM AUTHOR]

Osteoporosis is a progressive multifactorial systemic disease of the skeletal system characterized by the damage of the microarchitectonics of the bone tissue, which leads to the occurrence of low-energy fractures and impairment of the quality of life of individuals. The risk factors for the development of osteoporosis include smoking, which inhibits calcium absorption in the intestine and not only contributes to the reduction of bone density but also acts as a predictor of bronchopulmonary pathology. The systemic inflammation that develops in patients with chronic obstructive pulmonary disease, associated with the production of interleukins (IL)-6, IL-1, IL-8, and tumor necrosis factor – α, stimulates osteoclast-mediated bone resorption and a low level of osteoprotegerin closes the circle. In clinical practice, the determination of markers of bone resorption is required. This is a tartrate-resistant acid phosphatase, the 5β fraction of which signals the end of the resorption process; these are hydroxypyridine crosslinks – pyridoline (PYD) and deoxypyridoline, that stabilize the bone collagen molecule. Genetic factors also play an important role in the development of osteoporosis. The presence of the GG genotype or the G allele of the 283 A> G polymorphism (Bsml) of the VDR gene is a predictor of osteoporosis of the lumbar vertebrae L1-L4. The substitution of cytosine for thymine (C> T) in exon 17 of the calcitonin gene (CALCR) at position 1340 leads to the substitution of the amino acid proline (CCG) for leucine (CTG) at position 463 of the receptor protein molecule and affects bone density. But the most phylogenetically ancient mechanism for regulating the development and maintenance of tissue homeostasis by controlling cell proliferation, differentiation, migration, and apoptosis is the Wnt signaling pathway (SP-Wnt). Alterations in Wnt signaling observed in cases of genetic mutations cause various diseases of the human skeleton. A systematic literature search was carried out using the Scopus, PubMed, Web of Science databases.

Abstract Background The objective of this scoping review was to systematically explore the current knowledge of cellular and molecular processes that drive and control trauma-associated root resorption, to identify research gaps and to provide a basis for improved prevention and therapy. Methods Four major bibliographic databases were searched according to the research question up to February 2021 and supplemented manually. Reports on physiologic, histologic, anatomic and clinical aspects of root resorption following dental trauma were included. Duplicates were removed, the collected material was screened by title/abstract and assessed for eligibility based on the full text. Relevant aspects were extracted, organized and summarized. Results 846 papers were identified as relevant for a qualitative summary. Consideration of pathophysiological mechanisms concerning trauma-related root resorption in the literature is sparse. Whereas some forms of resorption have been explored thoroughly, the etiology of others, particularly invasive cervical resorption, is still under debate, resulting in inadequate diagnostics and heterogeneous clinical recommendations. Effective therapies for progressive replacement resorptions have not been established. Whereas the discovery of the RANKL/RANK/OPG system is essential to our understanding of resorptive processes, many questions regarding the functional regulation of osteo-/odontoclasts remain unanswered. Conclusions This scoping review provides an overview of existing evidence, but also identifies knowledge gaps that need to be addressed by continued laboratory and clinical research.

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of nuclear factor kB ligand (RANKL), and is implicated in the pathogenesis of atherosclerosis. The aim of the present study was to examine the hypothesis that serum OPG concentrations are increased in patients with stable coronary artery disease (CAD) at different serum levels of soluble RANKL (sRANKL). The study used a case-control design in which consecutively hospitalized individuals were recruited. Fasting blood samples were taken upon admission for serum testing. Participants with previously diagnosed CAD that was asymptomatic or had controlled symptoms constituted the stable CAD group, whereas patients with negative coronary computed tomography angiography results constituted the control non-CAD group. Exclusion criteria included recent acute coronary syndrome, severe heart failure, CAD-complicating autoimmune, blood or thyroid diseases, cancer, elevated temperature with or without infection, severe liver or kidney dysfunction, abnormal calcium metabolism, recent surgery and trauma history. A total of 118 individuals were included in the study. Smoothed plots generated using the recursive method and multivariate models showed that the incidence of stable CAD increased with serum OPG level up to the turning point of 18 pg/ml. This trend was observed at both high [odds ratio (OR), 1.61; 95% confidence interval (CI), 1.04-2.50; P=0.032) and low sRANKL concentrations (OR, 1.52; 95% CI, 1.06-2.17; P=0.022) after adjustment for cardiovascular risk factors. In conclusion, serum OPG levels ≤18 pg/ml are positively associated with stable CAD, regardless of sRANKL levels. In addition, at the same serum OPG level, higher sRANKL levels are associated with a greater incidence of stable CAD compared with lower sRANKL levels. This study identified the relationship between OPG, sRANKL, and stable CAD, and established the reference range for future clinical use. [ABSTRACT FROM AUTHOR]

Gallein is known as an inhibitor of Gβγ subunits, but roles of gallein in bone metabolism have not been reported. Fibroblast growth factor 2 (FGF-2) increases angiogenesis and promotes bone regeneration during the early stages of fracture healing. Osteoprotegerin (OPG) secreted by osteoblasts, binds to the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) as a decoy receptor and prevents RANKL from binding to RANK, resulting in the suppression of bone resorption. Our previous report demonstrated that FGF-2 activates the phosphorylation of p38 mitogen-activated protein kinase (MAPK), stress-activated protein kinase/c-Jun N-terminal kinase (JNK), and p44/p42 MAPK in osteoblast-like MC3T3-E1 cells. Additionally, FGF-2-activated phosphorylation of p38 MAPK and JNK but not p44/p42 MAPK is positively involved in OPG synthesis in these cells. This work aimed to investigate the effects of gallein on the FGF-2-elicited OPG synthesis in osteoblast-like MC3T3-E1 cells and the mechanism. Our findings demonstrated that gallein significantly increased the FGF-2-elicited OPG synthesis in MC3T3-E1 cells. By contrast, fluorescein, gallein-like compound that does not bind Gβγ, did not affect the FGF-2-elicited OPG synthesis. Gallein significantly enhanced the FGF-2-induced OPG mRNA expression levels. Gallein did not affect the FGF-2-activated phosphorylation of p38 MAPK and p44/p42 MAPK, but significantly increased the FGF-2-activated phosphorylation of JNK, while fluorescein did not affect JNK phosphorylation. SP600125, a specific JNK inhibitor, strongly inhibited gallein-induced enhancement of FGF-2-induced OPG synthesis and mRNA expression levels. Our results indicated that gallein increases the FGF-2-induced OPG synthesis due to the JNK activation in the osteoblast. • FGF-2 up-regulates OPG release in osteoblasts. • The effect of gallein on the FGF-2-elicited OPG release was assessed. • Osteoblasts were treated with FGF-2, gallein or fluorescein, and JNK inhibitor. • Gallein but not fluorescein increases the FGF-2-elicited OPG release. • Gallein may provide new insights for promoting bone regeneration. [ABSTRACT FROM AUTHOR]

Periodontal disease is a common infectious disease that can lead to the loss of teeth. Hower how to effectively suppress the inflammation with medication is unclear. The aim of the present study was to investigate the anti-inflammatory effect of Oroxylin A in periodontitis and its potential role through heme oxygenase-1 (HO-1). Primary rat gingival fibroblasts (RGFs) were cultured using the tissue block method and identified by immunofluorescence. Following lipopolysaccharide (LPS) stimulation of RGFs, Oroxylin A was administered at 50, 100, 200 or 400 µg/ml. Reverse transcription-quantitative PCR was used to assess mRNA expression of cyclooxygenase (COX)-2, TNF-α, RANKL and osteoprotegerin (OPG). Western blotting was used to detect protein expression levels of COX −2, TNF-α, RANKL and OPG. Following HO-1 knockdown, the same treatment was performed. The expression of COX-2 in rat gingival tissue was observed by immunohistochemistry. One-way analysis of variance and Student's t test were used for statistical analysis. Oroxylin A downregulated mRNA expression of COX-2, TNF-α, RANKL and OPG in LPS-induced RGFs. With increase of Oroxylin A dose, the expression of HO-1 was gradually upregulated. When HO-1 was knocked down, Oroxylin A did not downregulate the expression of COX-2, TNF-α, RANKL and OPG in LPS-induced RGFs. Immunohistochemical results showed that expression of COX-2 was downregulated by Oroxylin A, and the expression of TNF-α, RANKL and OPG were also downregulated. Oroxylin A decreased expression of inflammatory cytokines in LPS-induced RGFs and had a good inhibitory effect on periodontitis in rats. [ABSTRACT FROM AUTHOR]

[Display omitted] • We report a novel gold-silver-platinum (AuNP-AgNP-PtNP) trimetallic nanozyme with peroxidase-mimicking activity. • Trimetallic nanozyme-based electrochemical-colourimetric dual-mode platform was developed for osteoprotegerin. • The immunosensor was based on the antibody-conjugated nanozyme interaction with proteins. • The LOD was reported to be 1.81 pg/mL using electrochemical mode and 1.87 pg/mL using colourimetric detection mode. In this study, we report a novel gold-silver-platinum nanocomposite (AuNP-AgNP-PtNP), which displayed excellent peroxidase-mimicking activity because of the synergistic effect involving three metals. The nanozyme allowed the development of a sensitive and specific dual-mode immunodetection system to detect protein using electrochemical and colourimetric assays. The developed ultrasensitive dual-mode immunosensor was based on the anti-osteoprotegerin antibody-linked nanozyme interaction with recombinant osteoprotegerin (rOPG) protein coated over a microtiter plate. Based on the excellent electrocatalytic activity of the trimetallic nanozyme towards reducing hydrogen peroxide (H 2 O 2), the trimetallic nanozyme could be employed towards electrochemical immunodetection of the rOPG proteins. The proposed dual-mode biosensor allowed enhanced sensitive determination of rOPG proteins with a wide linear range of 0.1 fg/mL to 10 ng/mL for electrochemical detection and 1 fg/mL to 100 ng/mL for colourimetrically detecting rOPG proteins. Moreover, the dual-mode sensor could detect rOPG proteins with a LOD of 1.81 pg/mL using the electrochemical mode and 1.87 pg/mL using the colourimetric detection mode. Moreover, the study demonstrates outstanding selectivity, sensitivity, and specificity, yielding robust recoveries in human serum samples. [ABSTRACT FROM AUTHOR]

Objective To explore the relationship between osteoprotegerin (OPG),receptor activator of NF-κB (RANK),receptor activator of NF-κB ligand (RANKL),hematological indexes and osteonecrosis of the femoral head (ONFH),so as to provide basis for clinical efficacy evaluation. Methods A total of 84 patients with ONFH treated in Zhengzhou Traditional Chinese Hospital of Orthopedics from July to December 2019 were selected as the ONFH group. The patients were divided into the young group (18-<40 year, n= 32),middle-aged group (40~<60 year, n=47) and old group (≥60 year, n=5) according to their ages. According to different causes, the patients were divided into the hormone group (n=14),alcohol group (n=44), idiopathic group (n=21) and trauma group (n=5).According to different traditional Chinese medicine syndrome types, the patients were divided into the liver and kidney deficiency group (n=36) and damp-heat accumulation group (n=48).A total of 81 healthy subjects in the same period were selected as the control group The early morning fasting elbow venous blood of the ONFH group and control group was collected for the enzyme- linked immunosorbent assay (ELISA) and blood examination. The correlation between OPG,RANK, RANKL, hematological indexes and ONFH, traditional Chinese medicine syndrome types was analyzed. Results Compared with those of the control group, the level of OPG in the ONFH group was significantly lower, while the RANK level, RANKL level and RANKL/OPG ratio of the ONFH group were significantly higher, and the levels of the total cholesterol, triglyceride, low density lipoprotein (LDL) and apolipoprotein B (Apo B) significantly increased, while the apolipoprotein A and high-density lipoprotein significantly decreased. The differences were statistically significant (P <0.05).The RANKL/OPG ratio in the middle-aged group of the ONFH group was significantly higher than that in the older group, and the LDL, Apo B and activated partial thromboplastin time (APTT) in the young and middle-aged groups were significantly lower than those in the older group, and the differences were statistically significant (P <0.05).Patients in the alcohol group of the ONFH group had significantly higher RANK, RANKL, and OPG levels than those in the trauma group, and significantly higher RANK levels than those in the hormone group, the APTT, prothrombin time (PT),fibrinogen (FIB) and thrombin time (TT) of patients in the hormone group the alcohol group and the special hair group were significantly higher than in the trauma group, and the differences were all statistically significant (P <0.05).The RANKL levels of patients in the Damp-Heat group were significantly higher than those in the Liver and kidney deficiency syndrome, with statistically significant differences (P <0.05).The differences were not statistically significant when comparing the hematological indexes of patients in the liver and kidney deficiency syndrome (P >0.05) rothrombin timei brinogenthrombin time. Conclusion OPG, RANKL,RANK and blood coagulation mechanisms were affected by hormone and alcohol in the ONFH patients, but not by liver and kidney deficiency syndrome and damp-heat accumulation syndrome [ABSTRACT FROM AUTHOR]

BACKGROUND: Surgical reduction and internal fixation are used as the main treatments for severe displacement of condylar fracture. If a bone fragment is disintegrated due to the peeling of the external pterygoid muscle, complications such as delayed healing of condylar fracture block may occur after surgery. Therefore, how to promote bone healing after free reduction of condylar fracture is of concern to clinicians in maxillofacial surgery. OBJECTIVE: To study the effect of intermittent administration of parathyroid hormone on bone healing after free reduction of condylar fracture in rabbits. METHODS: Forty-eight New Zealand rabbits were randomly divided into experimental group and control group, 24 rabbits in each group. An experimental model of free reduction and fixation of mandibular condylar fracture was established in rabbits. The experimental group and control group were respectively subcutaneously injected with 20 μg/kg parathyroid hormone and 1 mL of normal saline on the next day after surgery, respectively. The animals were sacrificed 1, 2, 3 and 4 weeks after surgery. Bone samples at the surgical site were taken for bone healing observation. The expression of osteoprotegerin and receptor activator of nuclear factor kappa B ligand (RANKL) in the fracture area was detected by immunohistochemical staining and real-time fluorescence quantitative PCR. RESULTS AND CONCLUSION: There were more osteoblasts and new callus formed faster in the fracture area with a higher density in the experimental group. In the first 4 weeks after surgery, the number of osteoclasts in the experimental group was less than that in the control group (P < 0.05). The mean absorbance value and mRNA expression level of osteoprotegerin were higher in the experimental group than the control group within 4 weeks after surgery. The mean absorbance value and mRNA expression level of RANKL were lower in the experimental group than the control group within 4 weeks after surgery (P < 0.05). All these findings indicate that the application of parathyroid hormone on the second day after free reduction of mandibular condylar fracture could up-regulate osteoprotegerin and inhibit RANKL expression in the fracture area at the early postoperative stage, thereby promoting the formation of new bone in the fracture area. [ABSTRACT FROM AUTHOR]

Background: Bone-related proteins (such as sclerostin and osteoprotegerin [OPG]) are involved in the development of atherosclerosis. However, the relationship between bone-related proteins and acute myocardial infarction (AMI) has not been extensively evaluated. The purpose of this study was to assess the association of serum sclerostin and OPG with the presence, severity and prognosis in patients with AMI.Methods: This study prospectively enrolled 152 patients attacked by acute chest pain. Serum sclerostin and OPG were detected within the first 24 h after AMI diagnosis by ELISA kits. The AMI predictive efficacy of sclerostin and OPG were analyzed by receiver operating characteristics (ROC) curve. Univariable and multivariable linear regression analyses were performed to determine the association between bone-related proteins and scores indicating the severity of coronary artery occlusion. Moreover, prognostic values were assessed by Kaplan-Meier curves and Cox regression analysis.Results: There were 92 patients in AMI group, 60 in non-AMI group. Serum levels of sclerostin and OPG were significantly higher in AMI group than in non-AMI group (all p < 0.001), which showed predictive value for the presence of AMI (all p < 0.001). The area under the ROC curve values of sclerostin and OPG were 0.744 and 0.897, respectively. A multivariable linear regression analysis demonstrated that Ln-transformed sclerostin (β = 0.288, p = 0.009) and Ln-transformed OPG (Ln-OPG: β = 0.295, p = 0.019) levels were associated with GENISINI score, independently of conventional clinical parameters. In addition, Ln-OPG levels were still positively associated with GRACE score after adjustments (β = 0.320, p = 0.001). During a 1-year follow-up, patients above the median of sclerostin levels had higher incidence of major adverse cardiac events (MACE) than those below the median (p = 0.028). It was also observed that the MACE rates were higher in patients above the median of OPG levels, though no statistic importance (p = 0.060). After adjusting conventional risk factors by multivariate Cox regression, Ln-OPG was associated with incident MACE (hazard ratio = 2.188 [95% confidence intervals 1.102-4.344], p = 0.025).Conclusions: Bone-related proteins could exert a potential role in early risk stratification and prognosis assessment in patients with AMI. [ABSTRACT FROM AUTHOR]

Traditional Chinese medicine recommends kidney-tonifying treatment for osteoporosis. Zuogui pill is one such treatment composed of eight well characterized Chinese medicinal herbs (Radix rehmanniae preparata, Fructus lycii, Rhizoma dioscoreae, F. corni, Semen cuscutae, Colla cornus cervi, C. carapacis et Plastri testudinis, and R. achyranthis bidentatae). The aim of the study is to evaluate the effects of the Zuogui pill on osteoporosis in ovariectomized rats and to identify the signaling pathways that mediate its action on the bones. A total of 46 6-month-old female Sprague-Dawley rats were divided into four groups: sham-operated control, bilaterally ovariectomized, ovariectomized rats receiving diethylstilbestrol (the positive control group), and ovariectomized rats receiving the Zuogui pill. By the end of 8-week treatments, the following parameters were assessed: (a) bone mineral density and trabecular histomorphology, (b) the expression levels of receptor activator of nuclear factor kappa B ligand and osteoprotegerin in rat tibial osteoblasts and (c) bone marrow stromal cells. The Zuogui pill treatment elevated the trabecular bone area and trabecular thickness and reduced the trabecular spacing in rats with ovariectomy-induced osteoporosis. Compared to the ovariectomized group, the Zuogui pill treatment significantly increased the levels of bone mineral density and osteoprotegerin and suppressed the level of receptor activator of the nuclear factor kappa B ligand. These data led us to conclude that the Zuogui pill regulates bone metabolism and improves osteoporosis symptoms possibly through the osteoprotegerin/receptor activator of the nuclear factor kappa B ligand/receptor activator of the nuclear factor kappa B signaling pathway. [ABSTRACT FROM AUTHOR]

Chronic renal failure patients on dialysis are at a high risk of death due to vascular calcification. This study aimed at investigating the effect of omega-3 fatty acids on the vascular calcification biomarkers fetuin-A and osteoprotegerin (OPG) in patients with chronic renal failure who are undergoing hemodialysis. This prospective, open-label, controlled, parallel study included 60 hemodialysis patients who were randomized to receive either omega-3 fatty acids capsule along with their standard care of treatment (omega-3 group) or their standard care of treatment only (control group). Serum levels of fetuin-A, OPG, calcium, phosphorus, hemoglobin, parathyroid hormone, blood urea nitrogen (BUN), albumin, serum creatinine (SCr), and serum triglycerides (TG) were measured at baseline and after six months of intervention and follow-up of both groups. Significantly increased levels of fetuin-A and OPG (p < 0.001) were observed in the omega-3 group six months after the intervention compared with the control group. Levels of TG, albumin, SCr, BUN, phosphorous, calcium, hemoglobin, and parathyroid hormone were not significantly different in the omega-3 group compared with the control group after six months of intervention. Our study concluded that omega-3 may have a clinically beneficial effect in decreasing cardiovascular events by increasing the levels of the protective vascular calcification inhibitors fetuin-A and osteoprotegerin in chronic renal failure patients who are undergoing hemodialysis. [ABSTRACT FROM AUTHOR]

Menopause increases the osteoporosis risk, to which phytoestrogen intake can be beneficial. This study hypothesized that mulberry vinegar had a preventive effect on osteoporosis by decreasing osteoclastic activity. The hypothesis was tested in ovariectomized (OVX) rats and RANKL-differentiated osteoclast cells. OVX rats were given 0(OVX-CON), 0.5(OVX-MVL), 1(OVX-MVM), and 2(OVX-MVH) fermented mulberry vinegar (MV) mL/kg body weight (BW) daily for 12 weeks. Sham-operated rats had no MV supplementation (Normal-CON). The osteoporosis-related biomarkers were measured, and Micro-CT determined the bone mass of the femur. RANKL-differentiated Raw 264.7 cells were treated with MV (0–100 μg/mL). The cell viability, osteoporosis-related mRNA expression, and protein contents were measured. MV contained Acetobacter pasteurianus (7.31 log CFU/mL), citric acid (106 mg/mL), lactic acid (19.2 mg/mL), acetic acid (15.0 mg/mL), and rutin (0.36 mg/mL). OVX-MVM elevated the serum 17β-estradiol concentration similar to the Normal-CON group, but it did not prevent the decrease in uterine weight. OVX-MVM prevented the increase in osteoclastic-related parameters, including cathepsin K(CtsK), receptor activator of NF-κB ligand (RANKL), and tartrate-resistant acid phosphatase (TRAP) in the circulation. OVX-MVH also lowered C-telopeptide of type Ⅰ collagen as much as the Normal-CON group (p < 0.05). By contrast, OVX-MVH increased the serum osteoprotegerin concentration, an inhibitor of osteoclasts, better than the Normal-CON group (p < 0.05). These changes were integrated to alter the bone mineral density (BMD) in Micro-CT analysis: OVX-MVM and OVX-MVH prevented BMD decrease after OVX as much as the Normal-CON. In RANKL-differentiated osteoclast cells, the MV treatment for 24 and 48 h decreased RANKL-induced differentiation in osteoclast cells dose-dependently up to 100 µg/mL. Its decrease was related to inhibiting the TRAP activity and reducing TRAP-positive multinucleated cells during the five-day administration of RANKL. MV treatments also decreased mRNA expression of osteoclast-related genes (TRAP, Ctsk, OSCAR, and NFATc1). MV suppressed the protein contents of NFATc1 and c-FOS-related osteoclast. In conclusion, MV intake (1 mg/kg bw) protected against BMD loss mainly by inhibiting the osteoclastic activity (RANKL/RANK/TRAP) in OVX rats. MV may develop as a functional food for anti-osteoporosis in menopausal women. [ABSTRACT FROM AUTHOR]

Background. Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor, is a tumor necrosis factor receptor superfamily component. There is an established relationship between OPG and cardiovascular disease. We hypothesized that plasma OPG levels are associated with functional outcomes in acute ischemic stroke patients who have undergone endovascular thrombectomy (EVT). Methods. From April 2014 through December 2020, a total of 360 acute ischemic stroke patients who underwent EVT were prospectively included in this retrospective observational study. Plasma OPG was measured after fasting for 12 postoperative hours after EVT. A modified Rankin Scale (mRS) was used to assess functional outcomes 3 months after index stroke occurrence. Univariate and multivariate binary logistic regression and ordinal logistic regression analyses were performed to investigate the association of plasma OPG levels with poor functional outcomes. Results. Overall, 145 (40.2%) patients had poor (mRS > 2) outcomes. The mean ± standard deviation plasma OPG level was 200.2 ± 74.4 pg/mL. Multivariate analysis after adjusting for sex, body mass index, and variables with p < 0:1 in the preceding univariate analysis revealed high plasma OPG levels were independently associated with poor functional outcomes (highest tertile vs. lowest tertile of OPG; odds ratios (OR) 2.121, 95% confidence interval (CI) [1.089-4.191], p D 0:037 in binary logistic regression, OR 2.102, 95% CI [1.301-3.412], pD0:002 in ordinal logistic regression analysis). Conclusions. This study demonstrated that higher plasma OPG levels were associated with poor functional outcomes in acute ischemic stroke patients who underwent EVT. [ABSTRACT FROM AUTHOR]

Aim: The association between end-stage renal disease and cardiovascular mortality may be influenced through vascular alterations, in particular atherosclerosis and vascular calcification. The study goal was to assess the impact of each type of arterial intimal calcifications (AIC) and arterial medial calcifications (AMC), of osteoprotegerin (OPG), mineral metabolism markers and other features on all-cause and cardiovascular mortality in chronic hemodialysis patients. Methods: Ultrasound was performed in 87 patients on the carotid and femoral arteries, and the severity of AIC and AMC was assessed calculating a score according to the extension of calcification. We analyzed the link between AIC, AMC, OPG, mineral markers and mortality after 6 years of follow-up. Results: The cutoff value for OPG determined using ROC was 4.9 pmol/l for all-cause and cardiovascular mortality. Patients with higher serum OPG levels presented higher mortality rates. Our study revealed that AIC, high OPG, low ankle-arm index, presence of diabetes, smoking status, and lack of arteriovenous fistula are associated with all-cause and cardiovascular mortality in univariate regression analysis. Multivariate analysis identified AIC scoring based on the segmentation method as an independent predictor of all-cause and cardiovascular mortality, along with increased OPG levels. AMC scoring was not a predictor of mortality. Conclusions: Identifying and scoring AIC on ultrasound and measuring OPG levels, as a basis of the HD patient assessment may become valuable tools in clinical work, as these have an impact on death toll. [ABSTRACT FROM AUTHOR]

BACKGROUND: The anti-osteoporotic mechanism of salvianolic acid B is different from traditional anti-bone resorption drugs. It has a multi-target pharmacological effect, which has not yet been fully elucidated. OBJECTIVE: To study the effect of salvianolic acid B on bone density of femur and lumbar vertebra in rats with osteoporosis, and to explore its anti-osteoporotic mechanism. METHODS: Totally 36 SPF SD rats aged 6 months were randomly divided into three groups: sham operation group, osteoporosis group, and salvianolic acid B group. Bilateral ovaries were removed and the osteoporosis model was replicated in the osteoporosis group and salvianolic acid B group. In the sham operation group, intact ovaries were kept and part of adipose tissue was removed. At 4 weeks after surgery, 50% salvianolic acid B 25 mg/kg was given by gavage for 6 days per week for 12 consecutive weeks in the salvianolic acid B group. In the other two groups, the same amount of normal saline was given for the same time. At 16 weeks postoperatively, all the rats were sacrificed after anesthesia. The bone density of the right posterior femur and lumbar vertebra was scanned by dual-energy X-ray absorptiometry. The levels of osteoprotegerin and receptor activator of nuclear factor-kB ligand in serum were detected by enzyme-linked immunosorbent assay. The protocols were approved by the Animal Management Committee of Bengbu Medical College (approval No. [2021]255). RESULTS AND CONCLUSION: (1) The bone mineral density of femur in the osteoporosis group was lower than that in the sham group (P < 0.05). The femoral bone mineral density of salvianolic acid B group was significantly higher than that of osteoporosis group (P > 0.05). The bone mineral density of lumbar vertebrae in osteoporosis group was not significantly different from that in sham operation group (P > 0.05). The lumbar vertebrae bone density of salvianic acid B group was higher than that of osteoporosis group, but the difference was not significant (P > 0.05). (2) Osteoprotegerin level of osteoporosis group was lower than that of sham operation group (P < 0.05). Osteoprotegerin level of salvianolic acid B group was higher than that of osteoporosis group, but the difference was not significant (P > 0.05). The level of receptor activator of nuclear factor-kB ligand of osteoporosis group was significantly higher than that of sham operation group (P < 0.05). The level of receptor activator of nuclear factor-kB ligand of salvianolic acid B group was lower than that of osteoporosis group, but the difference was not significant (P > 0.05). (3) These findings suggest that in the early stage of postmenopausal osteoporosis, bone mineral density of femur decreased significantly, but there was no significant change in bone mineral density of the lumbar spine. At present, it is not believed that salvianolic acid B alone can effectively treat osteoporosis in the short term. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to assess bone mineral density (BMD) and trabecular bone score (TBS) in 61 patients from the acromegaly group (AG) with regard to the activity of the disease in comparison to 42 patients—control group (CG). We also analyzed selected bone markers and their association with BMD and TBS. Materials and Methods: Lumbar spine and femoral neck BMD measurements were performed. TBS values were obtained. Serum concentrations of selected bone markers, including osteoprotegerin (OPG), were measured. Results: We revealed a difference in TBS values between the AG and CG as well as between the TCA (treatment-controlled acromegaly) vs. CG and TCA+CA (cured acromegaly) vs. CG. We did not observe any statistically significant difference in BMD. OPG had a lower concentration in the CG compared to the AG. TBS correlated negatively with OPG in the AG (r = −0.31, p = 0.01) and in the TCA+ CA group (r = −0.3, p = 0.01). Conclusions: The acromegalic patients have altered bone microstructure as indicated by the decreased TBS regardless of the activity of the disease and BMD. OPG could be a marker of the destruction of the bone microstructure, but further studies are needed. [ABSTRACT FROM AUTHOR]

Women with multiple sclerosis (MS) can safely become pregnant and give birth, with no side effects or impediments. Pregnancy is generally accepted as a period of well-being in which relapses have a softer evolution, particularly in the third trimester. Herein, we hypothesized that the placenta, via its "secretome", could contribute to the recognized beneficial effects of pregnancy on MS activity. We focused on a well-known receptor/ligand/decoy receptor system, such as the one composed by the receptor activator of nuclear factor-kB (RANK), its ligand (RANKL), and the decoy receptor osteoprotegerin (OPG), which have never been investigated in an integrated way in MS, pregnancy, and placenta. We reported that pregnancy at the term of gestation influences the balance between circulating RANKL and its endogenous inhibitor OPG in MS women. We demonstrated that the placenta at term is an invaluable source of homodimeric OPG. By functional studies on astrocytes, we showed that placental OPG suppresses the mRNA expression of the CCL20, a chemokine responsible for Th17 cell recruitment. We propose placental OPG as a crucial molecule for the recognized beneficial effect of late pregnancy on MS and its potential utility for the development of new and more effective therapeutic approaches. [ABSTRACT FROM AUTHOR]

Women with a pathogenic germline mutation in the BRCA1 gene face a very high lifetime risk of developing breast cancer, estimated at 72% by age 80. Prophylactic bilateral mastectomy is the only effective way to lower their risk; however, most women with a mutation opt for intensive screening with annual MRI and mammography. Given that the BRCA1 gene was identified over 20 years ago, there is a need to identify a novel non-surgical approach to hereditary breast cancer prevention. Here, we provide a review of the emerging preclinical and epidemiologic evidence implicating the dysregulation of progesterone-mediated receptor activator of nuclear factor κB (RANK) signaling in the pathogenesis of BRCA1-associated breast cancer. Experimental studies have demonstrated that RANK inhibition suppresses Brca1-mammary tumorigenesis, suggesting a potential target for prevention. Data from studies conducted among women with a BRCA1 mutation further support this pathway in BRCA1-associated breast cancer development. Progesterone-containing (but not estrogen-alone) hormone replacement therapy is associated with an increased risk of breast cancer in women with a BRCA1 mutation. Furthermore, BRCA1 mutation carriers have significantly lower levels of circulating osteoprotegerin (OPG), the decoy receptor for RANK-ligand (RANKL) and thus endogenous inhibitor of RANK signaling. OPG levels may be associated with the risk of disease, suggesting a role of this protein as a potential biomarker of breast cancer risk. This may improve upon current risk prediction models, stratifying women at the highest risk of developing the disease, and further identify those who may be targets for anti-RANKL chemoprevention. Collectively, the evidence supports therapeutic inhibition of the RANK pathway for the primary prevention of BRCA1-associated breast cancer, which may generate unique prevention strategies (without prophylactic surgery) and enhance quality of life. [ABSTRACT FROM AUTHOR]

Introduction: Osteoarthritis (OA) is a whole-joint disease characterized by a low-grade inflammation that is involved in both cartilage degradation and subchondral bone remodeling. Since subchondral bone has a cholinergic innervation and that acetylcholine (Ach) might have an anti-inflammatory effect through the α7 nicotinic Ach receptor (α7nAchR), we aimed (i) to determine the expression of non-neuronal cholinergic system and nicotinic receptor subunits by murine and human osteoblasts, (ii) to address the role of α7nAchR in osteoblastic response to inflammation, and (iii) to study the role of α7nAchR in a spontaneous aging OA model. Methods: Primary cultures of WT and α7nAchR knock-out mice (Chrna7-/-) murine osteoblasts and of subchondral bone human OA osteoblasts were performed. The expressions of the non-neuronal cholinergic system and of the nAchR subunits were assessed by PCR. In vitro , IL1β-stimulated WT, Chrna7-/-, and human osteoblasts were pretreated with nicotine. At 24 h, expressions of interleukin-6 (IL6) and metalloproteinase-3 and -13 (MMP), RANK-ligand (RANKL), and osteoprotegerin (OPG) were quantified by qPCR and ELISA. Spontaneous aging OA was evaluated and compared between male WT and Chrna7-/- mice of 9 and 12 months. Results: Murine WT osteoblasts express the main components of the cholinergic system and α7 subunit composing α7nAchR. Nicotine partially prevented the IL1β-induced expression and production of IL6, MMP3, and RANKL in WT osteoblasts. The effect for IL6 and MMP was mediated by α7nAchR since nicotine had no effect on Chrna7-/- osteoblasts while the RANKL decrease persisted. Chrna7-/- mice displayed significantly higher cartilage lesions than their WT counterparts at 9 and 12 months, without difference in subchondral bone remodeling. Human OA osteoblasts also expressed the non-neuronal cholinergic system and α7 subunit as well as CHRFAM7A, the dominant negative duplicate of Chrna7. Nicotine pretreatment did not significantly reduce IL6 and MMP3 production in IL-1β-stimulated human osteoarthritic osteoblasts (n = 4), possibly due to CHRFAM7A. Conclusion: Cholinergic system counteracts murine osteoblastic response to IL-1β through α7nAchR. Since α7nAchR deletion may limit cartilage degradation during murine age-related OA, enhancing cholinergic system could be a new therapeutic target in OA but may depend on CHRFAM7A expression. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare vascular calcification (VC), serum osteoprotegerin (OPG) levels, and other biochemical markers to determine their value as available predictors of all-cause and cardiovascular (CV) mortality in patients on peritoneal dialysis (PD). A total of 197 patients were recruited from seven dialysis centers in Mexico City. VC was assessed with multi-slice computed tomography, measured using the calcification score (CaSc). OPG, albumin, calcium, hsC-reactive protein, phosphorous, osteocalcin, total alkaline phosphatase, and intact parathormone were also analyzed. Follow-up and mortality analyses were assessed using the Cox regression model. The mean age was 43.9 ± 12.9 years, 64% were males, and 53% were diabetics. The median OPG was 11.28 (IQR: 7.6–17.4 pmol/L), and 42% of cases had cardiovascular calcifications. The median VC was 424 (IQR:101–886). During follow-up (23 ± 7 months), there were 34 deaths, and 44% were cardiovascular in origin. In multivariable analysis, OPG was a significant predictor for all-cause (HR 1.08; p < 0.002) and CV mortality (HR 1.09; p < 0.013), and performed better than VC (HR 1.00; p < 0.62 for all-cause mortality and HR 1.00; p < 0.16 for CV mortality). For each mg/dL of albumin-corrected calcium, there was an increased risk for CV mortality, and each g/dL of albumin decreased the risk factor for all-cause mortality. OPG levels above 14.37 and 13.57 pmol/L showed the highest predictive value for all-cause and CV mortality in incident PD patients and performed better than VC. [ABSTRACT FROM AUTHOR]

Background. The problem of cardiovascular morbidity and mortality remains an urgent issue of modern medicine, and arterial stiffness is its independent predictor. Lively discussions about the correct approach to the prevention and treatment of comorbid conditions – increased vascular stiffness as an influential factor of the cardiovascular events and decreased bone mineral density (osteoporosis), primarily arise against the background of the need and safety of calcium and vitamin D supplements. The purpose was to search for literature data as for possible common pathogenetic links in the progression of arterial stiffness and the development of osteoporosis in order to assess the safety of the use of drugs to prevent osteoporotic fractures. Results. Analysis of literature sourses had showed that possible osteogenic factors affecting arterial stiffness may be: secondary hyperparathyroidism, disbalance of the RANK/RANKL/OPG system, inhibition of vitamin K-dependent matrix proteins (Gla-protein), osteopontin, etc. Conclusions. Today, there are many hypotheses confirming the possible influence of osteogenic factors on vascular stiffness and arterial calcification. Therefore, the search for sensitive markers and the development of screening protocols for the patients with risk factors for both osteoporosis and vascular changes are extremely relevant. A special issue is the possibility of using monotherapy for these comorbid pathologies, which can safely and efficiently influence the prevention of complications – both low-energy osteoporotic fractures and cardiovascular catastrophes. This will be the focus of our further research. [ABSTRACT FROM AUTHOR]

Metabolic bone disorders are one of the most frequent extra-intestinal manifestations in patients with inflammatory bowel diseases (IBD) that might result in an increase of skeletal fragility and risk of fracture. These disorders are a consequence of bone–gut crosstalk alterations, particularly due to inflammation, which involves the RANK-RANKL-Osteoprotegerin (OPG) pathway. This cross-sectional study investigates the role of serum OPG on bone health in IBD patients. In all patients, we carried out BMD measurements at the lumbar spine and femoral neck by the dual-energy X-ray absorptiometry (DXA), and evaluation of serum OPG, 25(OH)D, and PTH. We also divided all IBD patients into two groups: group 1 consisted of premenopausal women and men younger than 50 years old, while group 2 included postmenopausal women and men aged more than 50 years old. We enrolled 36 UC patients (51%), 34 CD patients (49%), and 70 healthy controls. IBD group mean age was 44 ± 17.3 years old, with a mean disease duration of 6 years. IBD patients had a mean value of OPG of 48.1 ± 26.64 pg/mL, while mean OPG in the control group was 61.35 ± 47.19 pg/mL (p < 0.05). In group 1, there was a correlation between BMD Z-scores at the lumbar spine and femoral neck and mean OPG levels in UC subjects (r = 0.47 and r = −0.21, respectively; p < 0.05), and only between Z-score at the lumbar spine and OPG level in the CD group (r = 0.83, p < 0.05). For the patients of group 2, we report a statistically significant correlation between T-score measured at the lumbar site in both UC and CD patients (r = −0.79 and r = 0.77, respectively; p < 0.05). In our study, we demonstrated serum OPG levels to be significantly decreased in IBD subjects compared to healthy age-matched individuals. However, according to our data, it seems that the measurement of serum OPG levels is not useful to better define metabolic bone disorders in IBD patients. [ABSTRACT FROM AUTHOR]

Background: Osteoprotegerin (OPG) was first found as being an inhibitor of bone resorption; however, research on OPG in type 2 diabetes mellitus patients and its relationship to albuminuria in Diabetic Kidney Disease (DKD) has been insufficient. Objectives: Study the association between serum osteoprotegerin and diabetic kidney disease in type 2 diabetic patients. Patients and methods: The study recruited 45 participants who all had diabetes. Group 1 comprised 15 type 2 diabetic patients with albuminuria that ranged from normal to mildly elevated. The second group consisted of 15 type 2 diabetic patients with mildly elevated albuminuria. Group 3 consisted of 15 type 2 diabetic patients with an extremely high albuminuria level. In all participants, the following was carried out: history taking; clinical examination, including height and weight; ophthalmoscopy; kidney ultrasound; and evaluation of fasting blood glucose; glycosylated hemoglobin; lipid profile; serum creatinine and urea; urinary ACR; and serum osteoprotegerin levels. Results: Our study showed statistically positive correlation between osteoprotegerin and degree of albuminuria in type 2 diabetic patients. We found that the best cutoff of serum OPG was =1.652 in prediction of severely increased albuminuria. Conclusion: A biomarker known as OPG may be effective in identifying diabetics with type 2 who are at high risk of developing severe albuminuria. [ABSTRACT FROM AUTHOR]

The RANKL-GLYC study aims to explore the impact of the rapid correction of chronic hyperglycemia on the receptor activator of nuclear factor-kappa B ligand (RANKL) and its antagonist osteoprotegerin (OPG). RANKL and OPG are considered the main factors in the pathophysiology of Charcot neuroarthropathy, a devastating complication of the joints that remains poorly understood. The study began recruiting patients in September 2021 and ends in June 2022; the final study results are scheduled for January 2023. [ABSTRACT FROM AUTHOR]

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Osteocytes sense the microenvironmental stimuli, including mechanical stress, and regulate bone resorption by osteoclasts and bone formation by osteoblasts. Diabetes and cancer metastasis to bone raise l -lactic acid in the bone tissue, causing acidification. Here, we investigated the effects of l -lactic acid and extracellular acidification on the function of mouse Ocy454 osteocytes. L- and d -lactic acid with low chiral selectivity and acidification of the medium raised the production of sclerostin and osteoprotegerin by Ocy454 cells. The mRNA expression of their genes increased after either treatment of L- and d -lactic acid or acidification of the medium. Furthermore, the conditioned medium of Ocy454 cells cultured in an acidic environment suppressed the induction of alkaline phosphatase activity in MC3T3-E1 cells, which was recovered by the anti-sclerostin antibody. While it is reported that HDAC5 inhibits the transcription of the sclerostin gene, extracellular acidification reduced the nuclear localization of HDAC5 in Ocy454 cells. While calmodulin kinase II (CaMKII) is known to phosphorylate and induce extranuclear translocation of HDAC5, KN-62, an inhibitor of CaMKII lowered the expression of the sclerostin gene in Ocy454 cells. Collectively, extracellular acidification is a microenvironmental factor that modulates osteocyte functions. • L- and d -lactic acid enhanced sclerostin and osteoprotegerin production by osteocytes. • Acidification promoted sclerostin and osteoprotegerin production by osteocytes. • Acidification reduced the nuclear HDAC5 in osteocytes. • Acidification raised intracellular calcium levels in osteocytes. • Inhibition of calmodulin kinase II suppressed the effect of acidification on sclerostin production. [ABSTRACT FROM AUTHOR]

Background/aim: Increased bone turnover is a hallmark of hyperthyroidism. The underlying factors of how thyroid hormones affect bone cells are still under the spotlight. Previous studies indicated serum osteoprotegerin (OPG), receptor activator of NF-kB ligand (RANKL), and interleukin-6 (IL-6) as mediators of the effect of thyroid hormones on bone metabolism. Ultimately, the present research aimed to examine the association of IL-6 with OPG and RANKL in patients with hyperthyroidism. Materials and methods: We carried out this study with 39 newly diagnosed and untreated Graves' patients and 43 healthy controls. In addition to routine tests, we measured serum OPG, RANKL, and IL-6 levels. Results: Mean age and sex distribution were similar in both groups. The hyperthyroid group had significantly higher OPG (p = 0.002) and IL-6 (p < 0.001) levels, but RANKL levels were significantly lower in this group (p < 0.001). We found OPG not to correlate with free T4 and T3, while it had a moderate and negative correlation with thyrotropin (TSH) (r = -0.372, p = 0.001). IL-6 had no correlation with OPG but positively correlated with free T4 (r = 0.445, p < 0.001) and free T3 (r = 0.326, p = 0.035). It also negatively correlated with RANKL (r = -0.247, p = 0.033). Conclusion: Maintaining skeletal development and integrity is partially regulated by a normal balance of thyroid hormones. We concluded that increases in serum OPG and IL-6 levels accompanied hyperthyroidism. However, excessive levels of the hormones might cause drops in serum RANKL levels. Our results suggested that OPG, RANKL, and IL-6 might be involved in the cross-talking among immunity, thyroid function, and bone metabolism in the case of hyperthyroidism. [ABSTRACT FROM AUTHOR]

Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor or tumor necrosis factor receptor superfamily member 11B, is well known as a modulator of bone remodeling. The contribution of OPG to cardiovascular disease (CVD) has been suggested, but its molecular mechanism is complex and remains unclear. In the present study, Alves-Lopes et al. (Clin. Sci. (Lond.) (2021) 135(20): https://doi.org/10.1042/CS20210643) reported the critical role of syndecan-1 (SDC-1, also known as CD138), a surface protein part of the endothelial glycocalyx, in OPG-induced vascular dysfunction. The authors found that in endothelial cells (ECs), through SDC-1, OPG increased eNOS Thr495 phosphorylation, thereby inhibiting eNOS activity. Furthermore, the OPG--SDC-1 interaction increased reactive oxygen species (ROS) production through NOX1/4 activation. Both the reduced eNOS activity and induced ROS production inhibited NO production and impaired EC function. In vascular smooth muscle cells (VSMCs), the OPG--SDC-1 interaction increased ROS production through NOX1/4 activation, subsequently increased MLC phosphorylation-mediated Rho kinase-MYPT1 regulation, leading to increased vascular contraction. Ultilizing wire myography and mechanistic studies, the authors nicely provide the evidence that SDC-1 plays a crucial role in OPG-induced vascular dysfunction. As we mentioned above, the molecular mechanism and roles of OPG in cardiovascular system are complex and somewhat confusing. In this commentary, we briefly summarize the OPG-mediated signaling pathways in cardiovascular system. [ABSTRACT FROM AUTHOR]

Abstract Introduction Osthole has a potential therapeutic application for anti-osteoporosis. The present study verified whether osthole downregulates osteoclastogenesis via targeting OPG. Methods In vivo, 12-month-old male mice were utilized to evaluate the effect of osthole on bone mass. In vitro, bone marrow stem cells (BMSCs) were isolated and extracted from 3-month-old OPG−/− mice and the littermates of OPG+/+ mice. Calvaria osteoblasts were extracted from 3-day-old C57BL/6J mice or 3-day-old OPG−/− mice and the littermates of OPG+/+ mice. Results Osthole significantly increased the gene and protein levels of OPG in primary BMSCs in a dose-dependent manner. The deletion of the OPG gene did not affect β-catenin expression. The deletion of the β-catenin gene inhibited OPG expression in BMSCs, indicating that osthole stimulates the expression of OPG via activation of β-catenin signaling. Conclusion Osthole attenuates osteoclast formation by stimulating the activation of β-catenin-OPG signaling and could be a potential drug for the senile osteoporosis.

Context Guizhi-Shaoyao-Zhimu decoction (GSZD) is commonly used to treat rheumatoid arthritis (RA), but its mechanism is unclear. Objective To investigate the effect of GSZD on bone erosion in type II collagen (CII)-induced arthritis (CIA) in rats and to identify the underlying mechanism. Materials and methods The CIA model was prepared in male Wistar rats by two subcutaneous injections of CII, 1 mg/mL. Fifty CIA rats were randomized equally into the control group given saline daily, the positive group given saline daily and methotrexate 0.75 mg/kg once a week, and three GSZD-treated groups gavaged daily with 800, 1600 and 3200 mg/kg of GSZD for 21 days. GSZD effects were assessed by paw volume, arthritic severity index and histopathology. Cytokine levels were determined by ELISA. The effects of GSZD on RAW264.7 cells were evaluated by receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption assay. Expression of IκB-α and p65 was measured by Western blotting. Major components of GSZD were identified by HPLC. Results Arthritis index score, paw volume and bone destruction score showed that GSZD improved inflammatory symptoms and reduced joint tissue erosion (p

A potential complication in critically ill patients is the formation of bone in soft tissues, termed heterotopic ossification. The exact pathogenetic mechanisms are still undetermined. Bone morphogenetic proteins induce bone formation, while signalling through the receptor activator of nuclear factor kappa-Β (RANK) and its ligand (RANKL), regulates osteoclast formation, activation, and survival in normal bone modelling and remodelling. Osteoprotegerin protects bone from excessive bone loss by blocking RANKL from binding to RANK.

Abstract Background The osteoclast bone resorption is critical in aseptic loosening after joint replacement. The balance between activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) is considered to play a central role in osteoclast maturation. Fibroblasts from the periprosthetic membrane express RANKL and promote osteoclast formation. Studies have demonstrated that naringin inhibited osteoclastogenesis and wear particle-induced osteolysis. In this study, the naringin-induced OPG/RANKL effects and its underlying mechanism were studied in fibroblasts from periprosthetic membrane. Methods Fibroblasts were isolated from the periprosthetic membrane during hip arthroplasty for revision due to aseptic loosening. Fibroblasts were cultured and treated with or without naringin and DKK-1 (the classical inhibitor of Wnt/β-catenin signaling pathway). OPG and RANKL mRNA and protein levels, gene expression of β-catenin, and cyclin D1, which participate in the Wnt signaling pathway, were examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Results The mRNA and protein levels of OPG were enhanced by naringin in a dose-dependent manner compared to that of the non-treated control. In contrast, naringin did not affect the expression of RANKL. Importantly, DKK-1 attenuated OPG expression in fibroblasts under naringin treatment. Moreover, naringin stimulated the gene expression of β-catenin and cyclin D1 in fibroblasts, and the effect could be inhibited by DKK-1. Conclusion The results indicated that naringin enhanced OPG expression through Wnt/β-catenin signaling pathway in fibroblasts from periprosthetic membrane, which may be useful to inhibit periprosthetic osteolysis during aseptic loosening after total joint arthroplasty.

In recent years, it has been proven that the formation of OA can occur against the background of impaired bone metabolism. Bone remodeling is considered as a continuous complex process aimed at eliminating microdamages and updating the bone matrix. A key link in the regulation of this process is the system RANK / RANKL / OPG (osteoprotegerin), which provides a balance of activity of osteoblasts and osteoclasts. It blocks the interaction between RANK and RANKL by intercepting the RANKL ligand, which inhibits osteoclast development and reduces bone resorption. Thus, these properties of OPG can be considered as one of the pathogenetic factors in patients with dystrophic joint lesions. Objective: to investigate the content and role of osteoprotegerin in young patients with osteoarthritis, which occurs against the background of changes in body weight. Materials and methods. The study involved 75 young patients (mean age - 30.92 ± 0.546 years) with overweight or obesity, who in the previous stages of the study was diagnosed with osteoarthritis (main group). The comparison group was represented by 50 patients with osteoarthritis and normal body weight. The age of patients was 30.95 ± 0.545 years; as in the previous group, men predominated - 64% and 36% respectively. Benchmarks of osteoprotegerin were obtained in a study of 37 relatively healthy individuals of the same age and sex. The level of osteoprotegerin was determined by enzyme-linked immunosorbent assay using the FineTest EH0247 reagent kit, China. The outcomes were processed by the methods of variation statistics using the computer program STATISTICA.Results and discussion. When determining the content of OPG in the serum of patients of the main group was found to increase to 124.03 pg / ml, against control - 65.64 pg / ml. In the group of patients with isolated OA, this value was 92.29 pg / ml. Meaning that, in OA, running on the background of altered BMI, the content of OPG is likely to increase, both in relation to the norm and the results of the comparison group (p

PurposeThis study aimed to assess bone mineral density (BMD) and trabecular bone score (TBS) in 61 patients from the acromegaly group (AG) with regard to the activity of the disease in comparison to 42 patients—control group (CG). We also analyzed selected bone markers and their association with BMD and TBS.Materials and MethodsLumbar spine and femoral neck BMD measurements were performed. TBS values were obtained. Serum concentrations of selected bone markers, including osteoprotegerin (OPG), were measured.ResultsWe revealed a difference in TBS values between the AG and CG as well as between the TCA (treatment-controlled acromegaly) vs. CG and TCA+CA (cured acromegaly) vs. CG. We did not observe any statistically significant difference in BMD. OPG had a lower concentration in the CG compared to the AG. TBS correlated negatively with OPG in the AG (r = −0.31, p = 0.01) and in the TCA+ CA group (r = −0.3, p = 0.01).ConclusionsThe acromegalic patients have altered bone microstructure as indicated by the decreased TBS regardless of the activity of the disease and BMD. OPG could be a marker of the destruction of the bone microstructure, but further studies are needed.

Purpose of Review: This review aims to consolidate recent observations regarding extra-osseous roles of the RANK-RANKL-OPG axis, primarily within skeletal muscle., Recent Findings: Preclinical efforts to decipher a common signalling pathway that links the synchronous decline in bone and muscle health in ageing and disease disclosed a potential role of the RANK-RANKL-OPG axis in skeletal muscle. Evidence suggests RANKL inhibition benefits skeletal muscle function, mass, fibre-type switching, calcium homeostasis and reduces fall incidence. However, there still exists ambiguity regarding the exact mechanistic actions and subsequent functional improvements. Other potential RANK-RANKL-OPG extra-osseous roles include regulation of neural-inflammation and glucose metabolism. Growing evidence suggests the RANK-RANKL-OPG axis may play a regulatory role in extra-osseous tissues, especially in skeletal muscle. Targeting RANKL may be a novel therapy in ameliorating loss of muscle mass and function. More research is warranted to determine the causality of the RANK-RANKL-OPG axis in extra-osseous tissues, especially those affected by aging., (© 2024. The Author(s).)

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are capable of differentiating into osteoblasts, chondrocytes, and adipocytes. Skewed differentiation of BM-MSCs contributes to the pathogenesis of osteoporosis. Yet how BM-MSC lineage commitment is regulated remains unclear. We show that ablation of p38α in Prx1+ BM-MSCs produced osteoporotic phenotypes, growth plate defects, and increased bone marrow fat, secondary to biased BM-MSC differentiation from osteoblast/chondrocyte to adipocyte and increased osteoclastogenesis and bone resorption. p38α regulates BM-MSC osteogenic commitment through TAK1-NF-κB signaling and osteoclastogenesis through osteoprotegerin (OPG) production by BM-MSCs. Estrogen activates p38α to maintain OPG expression in BM-MSCs to preserve the bone. Ablation of p38α in BM-MSCs positive for Dermo1, a later BM-MSC marker, only affected osteogenic differentiation. Thus, p38α mitogen-activated protein kinase (MAPK) in Prx1+ BM-MSCs acts to preserve the bone by promoting osteogenic lineage commitment and sustaining OPG production. This study thus unravels previously unidentified roles for p38α MAPK in skeletal development and bone remodeling.

Postmenopausal osteoporosis (PO) is a major public health issue which affects a large fraction of elderly women. Emerging in vitro evidence suggests a central role of oxidative stress (OxS) in postmenopausal osteoporosis (PO) development. Contrariwise, the human studies on this topic are still scarce and inconclusive. In the attempt to address this issue, we sought to determine if OxS, as assessed by 8-hydroxy-2-deoxyguanosine (8-OHdG), may influence the level of receptor activator of nuclear factor-κb ligand (RANKL)/osteoprotegerin (OPG) ratio (a central regulator of bone metabolism) in a sample (n = 124), including postmenopausal women with osteoporosis, osteopenia and normal bone mass density (BMD). The most striking result that emerged in our study was the independent and positive (beta = 0.449, p = 0.004, and R(2) = 0.185) association between the OxS marker and RANKL/OPG ratio which was found in osteopenic but not in the other 2 sample groups. If confirmed by longitudinal studies, our findings would suggest that OxS is implicated in the derangement of bone homeostasis which precedes PO development. In line with these considerations, antioxidant treatment of postmenopausal women with moderately low BMD might contribute to preventing PO and related complications.

BackgroundWe tested minocycline as an anti-proteinuric adjunct to renin-angiotensin-aldosterone system inhibitors (RAASi) in diabetic nephropathy (DN) and measured urinary biomarkers to evaluate minocycline's biological effects.MethodsDesignProspective, single center, randomized, placebo-controlled, intention-to-treat pilot trial. Inclusion. Type 2 diabetes/DN; Baseline creatinine clearance >30 mL/min; proteinuria ≥1.0 g/day; Age ≥30 years; BP

ContextAbnormalities in the osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL) axis have been observed in HIV-infected persons and have been implicated in cardiovascular disease (CVD) pathogenesis in the general population.ObjectiveTo determine associations of serum OPG and RANKL concentrations with HIV infection and subclinical atherosclerosis.DesignCross-sectional study nested within the Multicenter AIDS Cohort Study.SettingFour US academic medical centers.ParticipantsThere were 578 HIV-infected and 344 HIV-uninfected men.Main outcome measuresCoronary artery calcium (CAC) was measured by noncontrast cardiac computed tomography, and coronary stenosis and plaque characteristics (composition, presence, and extent) were measured by coronary computed tomography angiography. All statistical models were adjusted for traditional CVD risk factors.ResultsOPG concentrations were higher, and RANKL concentrations were lower among HIV-infected men compared with HIV-uninfected men (P < 0.0001 each). Among HIV-infected men, higher OPG concentrations were associated with the presence of CAC, mixed plaque, and coronary stenosis >50%, but not with plaque extent. In contrast, among HIV-uninfected men, higher OPG concentrations were associated with the extent of both CAC and calcified plaque, but not with their presence. RANKL concentrations were not associated with plaque presence or the extent among HIV-infected men, but among HIV-uninfected men, lower RANKL concentrations were associated with greater extent of CAC and total plaque.ConclusionsOPG and RANKL are dysregulated in HIV-infected men, and their relationship to the presence and extent of subclinical atherosclerosis varies by HIV status. The role of these biomarkers in CVD pathogenesis and risk prediction may be different in HIV-infected men.

Osteoporosis is a condition in which bone mineral density is reduced due to altered bone microstructure, which results in increased skeletal fragility and incidence of various types of fractures. Adipokines such as chemerin, vaspin, omentin-1 and osteoprotegerin are involved in bone remodeling. The current study was designed to determine the changes in circulating chemerin, vaspin, omentin-1, and osteoprotegerin levels after treatment with oral ibandronate 150 mg in postmenopausal osteoporotic females. The present study enrolled 107 postmenopausal osteoporotic females from a tertiary care hospital in Faisalabad, Pakistan, based on stringent inclusion and exclusion criteria. Sixty-six healthy postmenopausal, non-osteoporotic females with no systemic illness were chosen from the general population. The assessment of bone mineral density (BMD) was done using a DEXA scan. Serum levels of chemerin, vaspin, omentin-1 and osteoprotegerin were estimated using commercially available enzyme-linked immunosorbent assay kits. The collected data were analyzed with the Statistical Package for Social Sciences (SPSS) version 24. Following 6 months of ibandronate treatment, there was a significant decrease of 24.24% (p <.033) in serum chemerin levels, as well as a significant increase in serum vaspin levels 343.32% (p <.001) and osteoprotegerin levels 19.57% (p <.001), with no significant change in omentin-1 levels. Thus, an increase in serum chemerin levels and a decrease in serum vaspin and osteoprotegerin levels could be implicated in osteoporosis. [ABSTRACT FROM AUTHOR]

Incretins including glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), which are secreted from the small intestine after oral food ingestion, are currently well-known to stimulate insulin secretion from pancreatic β-cells and used for the treatment of type 2 diabetes mellitus. We have previously reported that prostaglandin F2α (PGF2α) stimulates the synthesis of interleukin-6 (IL-6) and osteoprotegerin in osteoblast-like MC3T3-E1 cells, and that IL-6 and osteoprotegerin release are mediated through the p44/p42 mitogen-activated protein (MAP) kinase, p38 MAP kinase or stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) pathways. In the present study, we investigated the effects of incretins including GLP-1 and GIP, on the PGF2α-induced synthesis of IL-6 and osteoprotegerin and examined the detailed mechanism in osteoblast-like MC3T3-E1 cells. We found that GIP and GLP-1 significantly stimulated the PGF2α-induced synthesis of IL-6 in osteoblast-like MC3T3-E1 cells. In addition, GIP and GLP-1 significantly enhanced the PGF2α-induced mRNA expression levels of IL-6. On the other hand, GIP and GLP-1 markedly stimulated the PGF2α-induced synthesis of osteoprotegerin. However, the phosphorylation of p44/p42 MAP kinase, p38 MAP kinase, or JNK induced by PGF2α was not affected by GIP or GLP-1. Therefore, these results strongly suggest that incretins enhance the PGF2α-induced synthesis of IL-6 and osteoprotegerin in osteoblast-like MC3T3-E1 cells. However, these syntheses are not mediated through p44/p42 MAP kinase, p38 MAP kinase, or JNK pathways. [ABSTRACT FROM AUTHOR]

Background: Inflammatory bowel disease (IBD) is a condition in which the gastrointestinal system becomes inflamed for no apparent reason. Its incidence increased during the last few decades. As a result, it's critical to understand how to validate a clinical diagnosis and monitor any progress using a simple procedure. Osteoprotegerin (OPG), which interacts with RANKL, regulates RANK/RANKL signaling. OPG is a decoy receptor for soluble receptor activator of nuclear factor-B ligand (sRANKL), which stimulates nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and the healing trefoil factor 3 (TFF3), which could be employed as in the diagnosis and follow-up of IBD patients, biomarkers are used. Objectives: The aim of the current work was to evaluate the role of RANKL (sRANKL), OPG, NF-κB, and TFF3 in in the diagnosis of active IBD. Subjects and methods: Thirty-five newly diagnosed untreated IBD patients and thirty-five healthy controls were included in this study. Patients were then given particular treatment either in the form of cortisone, mesalamin, immunotherapy or infliximab and immunotherapy for 3 months and attend for second visit. OPG, sRANKL, NF-κB and TFF3 levels were estimated by ELISA method using commercial kits in patients before and after treatment and healthy control. Results: Patients with IBD had significantly increased levels of OPG, sRANKL, NF-B, and TFF3 than healthy controls (P =0.0001). After 3 months of treatment, patients' levels of NF-B and TFF3 were significantly lower (p = 0.0001 and 0.03, respectively). Conclusion: The biomarkers OPG, sRANKL, NF-κB, and TFF3 show promise in the diagnosis of active IBD. The decrease in NF-κB and TFF3 following treatment suggests that be used as biomarkers to track disease activity and treatment effectiveness. [ABSTRACT FROM AUTHOR]

Background/Aims: Osteoprotegerin (OPG) is a profibrotic mediator produced by myofibroblasts under influence of transforming growth factor β (TGFβ). Its expression in experimental models of liver fibrosis correlates well with disease severity and treatment responses. The regulation of OPG in liver tissue is largely unknown and we therefore set out to elucidate which growth factors/interleukins associated with fibrosis induce OPG and through which pathways. Methods: Precision-cut liver slices of wild type and STAT6-deficient mice and 3T3 fibroblasts were used to investigate the effects of TGFβ, interleukin (IL) 13 (IL13), IL1β, and platelet-derived growth factor BB (PDGF-BB) on expression of OPG. OPG protein was measure by ELISA, whereas OPG mRNA and expression of other relevant genes was measured by qPCR. Results: In addition to TGFβ, only IL13 and not PDGF-BB or IL1β could induce OPG expression in 3T3 fibroblasts and liver slices. This IL13-dependent induction was not shown in liver slices of STAT6-deficient mice and when wild type slices were cotreated with TGFβ receptor 1 kinase inhibitor galunisertib, STAT6 inhibitor AS1517499, or AP1 inhibitor T5224. This suggests that the OPG-inducing effect of IL13 is mediated through IL13 receptor α1-activation and subsequent STAT6-dependent upregulation of IL13 receptor α2, which in turn activates AP1 and induces production of TGFβ and subsequent production of OPG. Conclusion: We have shown that IL13 induces OPG release by liver tissue through a TGFβ-dependent pathway involving both the α1 and the α2 receptor of IL13 and transcription factors STAT6 and AP1. OPG may therefore be a novel target for the treatment liver fibrosis as it is mechanistically linked to two important regulators of fibrosis in liver, namely IL13 and TGFβ1. [ABSTRACT FROM AUTHOR]

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Recent evidence indicates that the abnormal differentiation of bone marrow‐derived mesenchymal stem cells (BMSCs) plays a pivotal role in the pathogenesis of osteoporosis. LncRNA SNHG1 has been found to be associated with the differentiation ability of BMSCs. In this study, we aimed to elucidate the role of lncRNA SNHG1 and its associated pathway on the differentiation of BMSCs in osteoporosis. Mice that underwent bilateral ovariectomy (OVX) were used as models of osteoporosis. Induced osteogenic or adipogenic differentiation was performed in mouse BMSCs. Compared to sham animals, lncRNA SNHG1 expression was upregulated in OVX mice. Also, the in vitro expression of SNHG1 was increased in adipogenic BMSCs but decreased in osteogenic BMSCs. Moreover, overexpression of SNHG1 enhanced the adipogenic capacity of BMSCs but inhibited their osteogenic capacity as determined by oil red O, alizarin red, and alkaline phosphatase staining, while silencing of SNHG1 led to the opposite results. LncRNA SNHG1 interacting with the RNA‐binding polypyrimidine tract‐binding protein 1 (PTBP1) promoted osteoprotegerin (Opg) methylation and suppressed Opg expression via mediating DNA methyltransferase (DNMT) 1. Furthermore, Opg was showed to regulate BMSC differentiation. Knockdown of SNHG1 decreased the expressions of adipogenic related genes but increased that of osteogenic related genes. However, the knockdown of Opg partially reversed those effects. In summary, lncRNA SNHG1 upregulated the expression of DNMT1 via interacting with PTBP1, resulting in Opg hypermethylation and decreased Opg expression, which in turn enhanced BMSC adipogenic differentiation and contributed to osteoporosis. [ABSTRACT FROM AUTHOR]