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Background: This study aimed to investigate the effect of erbium, chromium doped:yttrium,scandium,gallium,garnet (Er,Cr:YSGG) laser application combined with non‐surgical mechanical debridement (MD) on clinical parameters and peri‐implant crevicular fluid receptor activator of nuclear factor‐kappa B ligand (RANKL) and osteoprotegerin (OPG) levels in the treatment of peri‐implantitis. Methods: A total of 49 patients who underwent non‐surgical treatment of peri‐implantitis were randomly divided into two groups. The control group (n = 26) received MD alone, while the laser group (n = 23) received MD+Er,Cr:YSGG. The clinical parameters (bleeding on probing [BoP], gingival index [GI], plaque index [PI], probing depth [PD]), marginal bone loss (MBL), and biochemical parameters (RANKL and OPG) were measured at baseline (T0) and 6 months after treatment (T1). Results: There was a statistically significant decrease in all the clinical parameters in both groups at T1 compared to T0 (p < 0.05). The BoP, PD, MBL, and RANKL reductions were significantly higher in the laser group than in the control group (p = 0.046, p = 0.014, p = 0.047, p = 0.045, respectively). The OPG levels significantly increased at T1 in the laser group (p = 0.01). The OPG/RANKL ratio increased significantly in both groups at T1, which favored the laser group (p = 0.034). Conclusions: Although both treatment methods were influential in treating peri‐implantitis, the laser group (MD+Er,Cr:YSGG) yielded more favorable results by reducing clinical inflammation and improving biochemical parameters. Based on these findings, Er,Cr:YSGG laser may be a beneficial adjunctive treatment in this patient group. [ABSTRACT FROM AUTHOR]

Background and Aim: Bone as an endocrine organ regulates metabolic processes independently of mineral metabolism through the production/release of proteins collectively named 'osteokines'. Relevant connections were reported between the insulin/glucose system, calcification of the atherosclerotic plaque, and several osteokines. We aimed to test the hypothesis that the osteokine network could be involved in beta‐cell function, insulin sensitivity, and vascular damage in a cohort of people with newly diagnosed type 2 diabetes (T2D). Subjects and Methods: In 794 drug‐naive, GADA‐negative, newly‐diagnosed T2D patients (mean ± SD age: 59 ± 9.8 years; BMI: 29.3 ± 5.3 kg/m2; HbA1c: 6.6 ± 1.3%) we assessed: plasma concentration of osteocalcin (OCN), osteopontin (OPN), RANKL, and its putative decoy receptor osteoprotegerin (OPG); insulin sensitivity (SI) by hyperinsulinemic euglycemic clamp; beta cell function (BCF), estimated by OGTT minimal modelling and expressed as derivative (DC) and proportional (PC) control. Echo‐doppler of carotid and lower limb arteries were also performed in 708 and 701 subjects, respectively. Results: OCN, RANKL and OPG were significantly associated with PC (p < 0.02); OCN was positively related to DC (p = 0.018). OPG was associated with lower IS (p < 0.001). Finally, the higher RANKL levels, the greater was the severity of atherosclerosis in common carotid artery (p < 0.001). Increased OPG and OPN concentrations were related to subclinical atherosclerosis in peripheral arteries of lower limbs (p = 0.023 and p = 0.047, respectively). Conclusion: These data suggest that, in patients with newly diagnosed T2D, the osteokine network crosstalks with the glucose/insulin system and may play a role in modulating the atherosclerotic process. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of photobiomodulation therapy (PBMT) using 660 and 808 nm diode lasers (individual and in combination) on periodontal ligament mesenchymal stem cells (PDLSCs) in the presence of zoledronic acid (ZA). PDLSCs were cultured for 48 h in DMEM complete medium containing 5 μM ZA. PBMT was done three times with a 24‐h interval in groups 1 (660 nm, 5 J/cm2), 2 (880 nm, 3 J/cm2), and 3 (660 + 808 nm) either in normal or ZA‐treated culture medium. Control groups did not receive PBMT. Twenty‐four hours post‐irradiation, cell proliferation and expression of RANKL and OPG were assessed using MTT and real‐time PCR tests, respectively. The results showed a significant decrease in cell viability in ZA‐treated cells (p < 0.001). Additionally, ZA induced the expression of OPG (p = 0.03) while reducing RANKL (p < 0.001). Cell proliferation was significantly increased in 808 and 660 + 808 nm groups. Moreover, all PBMT groups could significantly increase and decrease the RANKL and OPG, respectively, in the presence of ZA (all p < 0.001). A combination of 660 + 808 nm showed the highest effects on both genes. In conclusion, it seems that PBMT can modulate the effects of ZA by inducing PDLSC proliferation and increasing RANKL‐to‐OPG gene expression ratio. [ABSTRACT FROM AUTHOR]

Osteoporosis is a common condition worldwide, affecting millions of people. Women are more commonly affected than men, and the risk increases with age. Inflammatory reaction plays a crucial role in the expansion of osteoporosis. Osteoporosis is characterized by a gradual decline in bone density and bone tissue quality, which increases fragility and raises the risk of fractures. We scrutinized the anti‐osteoporosis effect of hydroxysafflor yellow A (HYA) against glucocorticoid‐induced osteoporosis (GIOP) in rats. In‐silico study was carried out on EGFR receptor (PDBID: 1m17), Estrogen Alpha (PDB id: 2IOG), MTOR (PDB id: 4FA6), RANKL (PDB id: 1S55), and VEGFR2 (PDB id: 1YWN) protein. For this investigation, Sprague‐Dawley (SD) rats were used, and they received an oral dose of HYA (5, 10, and 20 mg/kg, b.w.) along with a subcutaneous injection of dexamethasone (0.1 mg/kg/day) to induce osteoporosis. The biomechanical, bone parameters, antioxidant, cytokines, inflammatory, nutrients, hormones, and urine parameters were estimated. HYA treatment significantly suppressed the body weight and altered the organ weight. HYA treatment remarkably suppressed the level of alkaline phosphatase, acid phosphatase, and improved the level of bone mineral density (total, proximal, mild, and dis). HYA treatment restored the level of calcium (Ca), phosphorus (P), estradiol (E2), and parathyroid hormone near to the normal level. HYA treatment remarkably altered the level of biomechanical parameters, antioxidant, cytokines, urine, and inflammatory parameters. HYA treatment altered the level of osteoprotegerin (OPG), receptor activator of nuclear factor kappa beta (RANKL) and RANKL/OPG ratio. The result clearly showed the anti‐osteoporosis effect of HYA against GIOP‐induced osteoporosis in rats via alteration of antioxidant, cytokines, inflammatory, and bone protective parameters. [ABSTRACT FROM AUTHOR]

Despite their diverse physiologies and roles, the heart, skeletal muscles, and smooth muscles all derive from a common embryonic source as bones. Moreover, bone tissue, skeletal and smooth muscles, and the heart share conserved signaling pathways. The maintenance of skeletal health is precisely regulated by osteocytes, osteoblasts, and osteoclasts through coordinated secretion of bone‐derived factors known as osteokines. Increasing evidence suggests the involvement of osteokines in regulating atherosclerotic vascular disease. Therefore, this review aims to examine the evidence for the role of osteokines in atherosclerosis development and progression comprehensively. Specifically discussed are extensively studied osteokines in atherosclerosis such as osteocalcin, osteopontin, osteoprotegerin, and fibroblast growth factor 23. Additionally, we highlighted the effects of exercise on modulating these key regulators derived from bone tissue metabolism. We believe that gaining an enhanced understanding of how osteocalcin contributes to the process of atherosclerosis will enable us to develop targeted and comprehensive therapeutic strategies against diseases associated with its progression. Significance Statement: Bone is now recognized as an endocrine organ, with numerous studies demonstrating its direct effects on blood vessels and cells, as well as indirect impacts on the process of atherosclerosis. We believe that osteokines hold significant research potential in this area, and understanding their role in atherosclerosis and uncovering underlying mechanisms could lead to new therapeutic targets and improved treatment outcomes. In this review, we summarize four well‐established mechanisms through which osteokines contribute to atherosclerosis, providing valuable insights for future researchers. [ABSTRACT FROM AUTHOR]

Background: Osteoprotegerin (OPG) is a secretory glycoprotein known for its involvement in bone metabolism and immune regulation. Research has extended OPG's significance in cardiovascular diseases (CVDs). Elevated OPG levels have been associated with increased cardiovascular risks, prompting interest in its role as a potential biomarker. Main Body: This study summarizes several studies that investigated the relationship between OPG levels and the incidence of CVD. The studies indicate that higher plasma levels of OPG are associated with an increased incidence of all‐cause death, cardiovascular death, and heart failure, even after adjusting for clinical confounders. Moreover, the findings suggest that OPG has the potential to serve as a predictive biomarker for adverse cardiovascular events in the patient population studied. The findings suggest that OPG could aid in risk stratification, allowing clinicians to identify high‐risk patients who might benefit from intensified preventive measures or tailored therapeutic interventions. Therefore, early identification of individuals at risk for adverse cardiovascular events could lead to improved patient outcomes and reduced disease burden. Conclusions: OPG's role in bone health and immune regulation has expanded to potential use as a biomarker for adverse cardiovascular events in stable coronary artery disease (CAD) patients. Despite limitations, its association with cardiovascular risks highlights its importance in risk assessment and personalized interventions. [ABSTRACT FROM AUTHOR]

Evidence is accumulating that osteal macrophages, in addition to bone‐resorbing osteoclasts and bone‐forming osteoblasts, participate vitally in bone remodeling process. Oncostatin M (OSM), an inflammatory cytokine belonging to interleukin‐6 superfamily, is recognized as an essential factor secreted by osteal macrophages to orchestrate bone remodeling. Osteoprotegerin (OPG) produced by osteoblasts regulates osteoclastogenesis. We have reported that bone morphogenetic protein‐4 (BMP‐4) stimulates OPG synthesis in MC3T3‐E1 osteoblast‐like cells, and that SMAD1/5/8(9), p38 mitogen‐activated protein kinase (MAPK), and p70 S6 kinase are involved in the OPG synthesis. The present study aims to investigate the effect of OSM on the synthesis of OPG stimulated by BMP‐4 in osteoblasts. OSM suppressed the release and the mRNA expression of OPG upregulated by BMP‐4 in MC3T3‐E1 cells. Neither the BMP‐4‐induced phosphorylation of SMAD1/5/9 nor that of p38 MAPK was affected by OSM. On the other hand, the phosphorylation of p70 S6 kinase stimulated by BMP‐4 was considerably suppressed by OSM. These results strongly suggest that OSM suppresses the BMP‐4‐stimulated OPG synthesis via inhibition of the p70 S6 kinase‐mediated pathway in osteoblast‐like cells. Significance Statement: Oncostatin M (OSM), a cytokine of the interleukin‐6 superfamily, modulates bone remodeling. Osteoprotegerin (OPG) secreted from osteoblasts regulates osteoclastogenesis. We previously showed that bone morphogenetic protein‐4 (BMP‐4) activates SMAD1/5/8(9), p38 mitogen‐activated protein kinase, and p70 S6 kinase, resulting in OPG synthesis in osteoblast‐like MC3T3‐E1 cells. In the present study, we investigated the effects of OSM on the BMP‐4‐induced synthesis of OPG in these cells. Our results strongly suggest that OSM suppresses OPG synthesis by inhibiting the p70 S6 kinase‐mediated pathway in osteoblasts. [ABSTRACT FROM AUTHOR]

Background: Bone tissue homeostasis relies on the coordinated activity of the bone‐forming osteoblasts and bone‐resorbing osteoclasts. Osteomesopyknosis is considered a distinctive rare sclerosing skeletal disorder of unelucidated pathophysiology and presumably autosomal dominant transmission. However, the causal genes are unknown. Methods: We present a case report encompassing clinical assessments, imaging studies, and whole‐exome sequencing analysis, complemented by functional in vitro experiments. Results: This new case of osteomesopyknosis was associated with a missense ALOX5 variant predicted to induce protein misfolding and proteasomal degradation. Transfection experiments demonstrated that the variant was associated with reduced protein levels restored by proteasomal inhibition with bortezomib. Likewise, gene expression analysis showed that the mutated gene was associated with a decreased RANKL/OPG ratio, which is a critical driver of osteoclast precursor differentiation. Conclusion: Our data indicate impaired bone resorption as the underlying mechanism of this rare osteosclerosis, implicating ALOX5 pathogenic variants as potential etiological factors. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to monitor changes in Osteoprotegerin (OPG) and receptor activator of nuclear factor‐kappa ligand (RANKL) levels in the saliva during orthodontic tooth movement (OTM). Materials and Methods: Nine healthy females (15–20 y of age) with four pre‐molar extractions and fixed appliance were included. In total, 134 stimulated and 134 unstimulated saliva samples were collected: at baseline and then every 6–8 weeks at follow‐up appointments during the whole orthodontic treatment. Twelve age‐matched females with no active orthodontic treatment served as a control group. Saliva samples were analysed by enzyme‐linked immunosorbent assay (Elisa). The mean levels of OPG and RANKL were calculated according to the different orthodontic treatment stages: alignment, space closure and finishing. A mixed model analysis was used to compare the means of treatment stages. Baseline OPG levels were compared with the control group using an independent t‐test. OPG levels were measured in stimulated saliva due to low levels in unstimulated saliva. Results: No significant difference was observed between baseline OPG values and the control group. OPG increased significantly at all treatment stages: alignment, space closure and finishing compared with baseline (P = 0.002, P = 0.039, P ≤ 0.001, respectively). The salivary levels of OPG increased gradually, except during space closure, reaching peak levels at finishing. RANKL was undetectable in stimulated and unstimulated saliva by sandwich Elisa during OTM. Conclusions: This novel approach shows the changes in the levels of OPG in OTM and indicates how and when to sample saliva during orthodontic treatment to analyse bone remodelling. [ABSTRACT FROM AUTHOR]

Background: Novel biomarkers of vascular disease in diabetes could help identify new mechanistic pathways. Osteocalcin, osteoprotegerin, and osteopontin are key molecules involved in bone and vascular calcification processes, both of which are compromised in diabetes. We aimed to evaluate possible associations of osteocalcin, osteoprotegerin, and osteopontin with cardiovascular disease (CVD) and diabetic retinopathy (DR) among people with type 2 diabetes (T2D). Materials and Methods: Osteocalcin, osteoprotegerin, and osteopontin concentrations were measured at enrolment in 848 participants with T2D from the Sapienza University Mortality and Morbidity Event Rate (SUMMER) Study (ClinicalTrials.gov: NCT02311244). Logistic regression models and propensity score matching were used to assess possible associations of osteocalcin, osteoprotegerin, and osteopontin with a history of CVD and with evidence of any grade of DR adjusting for confounders. Results: Previous CVD was reported in 139 (16.4%) participants, while 144 (17.0%) had DR. After adjusting for possible confounders, osteocalcin but not osteoprotegerin or osteopontin concentrations were associated with a history of CVD (Odds Ratio [OR] and 95% CI for one standard deviation (SD) increase in osteocalcin concentrations (natural log): 1.35 (1.06–1.72), p = 0.014). Associations with prevalent DR were seen for osteoprotegerin (OR for one SD increase in osteoprotegerin concentrations (natural log): 1.25 (1.01–1.55), p = 0.047) and osteopontin (OR for one SD increase in osteopontin concentrations (natural log): 1.25 (1.02–1.53), p = 0.022), but not osteocalcin. Conclusions: In T2D, higher serum osteocalcin concentrations are associated with macrovascular complications and higher osteoprotegerin and osteopontin concentrations with microvascular complications, suggesting that these osteokines might be involved in pathways directly related to vascular disease. [ABSTRACT FROM AUTHOR]

Background and Aims: Limitations of the conventional diagnostic techniques urged researchers to seek novel methods to predict, diagnose, and monitor periodontal disease. Use of the biomarkers available in oral fluids could be a revolutionary surrogate for the manual probing/diagnostic radiograph. Several salivary biomarkers have the potential to accurately discriminate periodontal health and disease. This study aimed to determine the diagnostic sensitivity and specificity of salivary interleukin (IL)‐17, receptor activator of nuclear factor‐κB ligand (RANKL), osteoprotegerin (OPG), RANKL/OPG for differentiating (1) periodontal health from disease and (2) stable and unstable periodontitis. Methods: Participants with periodontitis (n = 50) and gingivitis (n = 25), both diseases represented the cases, and subjects with healthy periodontium (n = 15) as a control were recruited for this study. Periodontitis cases were further equally subdivided into stable and unstable. Whole unstimulated salivary sample were collected from all participants. Periodontal parameters including bleeding on probing, probing pocket depth, clinical attachment loss, and number of missing teeth were recorded. The protein levels of salivary IL‐17, RANKL, and OPG were determined by using enzyme‐linked immunosorbent assays technique. Results: Salivary IL‐17, OPG, RANKL, and RANKL/OPG showed high sensitivity and specificity to differentiate periodontal health from gingivitis and periodontitis. Similar pattern was observed in discriminating stable and unstable periodontitis. Salivary IL‐17 and RANKL showed a good accuracy to differentiate gingivitis from periodontitis. However, OPG and RANKL/OPG did not exhibit enough sensitivity and specificity to differentiate the latter conditions. Conclusion: Salivary IL‐17, RANKL, OPG, and RANKL/OPG system are potential candidates for differentiating periodontal health and disease and discriminate stable and unstable periodontitis. [ABSTRACT FROM AUTHOR]

Hidradenitis suppurativa (HS) is a chronic inflammatory disease associated with an increased prevalence of subclinical atherosclerosis and cardiovascular risk. Angiopoietin‐2 (Ang‐2), asymmetric dimethylarginine (ADMA), and osteoprotegerin (OPG) are molecules related to endothelial dysfunction (ED) and atherosclerosis, but also to disease severity in patients with chronic inflammatory disorders. In this case–control study, we aimed to investigate serum Ang‐2, ADMA, and OPG levels in patients with HS, and to assess the potential relationship between these levels and disease severity. Seventy‐five patients with HS and 60 controls were assessed. Serum Ang‐2, ADMA, and OPG concentrations were determined in all participants. HS patients had significantly higher Ang‐2 and ADMA levels than controls after adjusting for confounders. Besides, Ang‐2 concentrations positively correlated with disease severity in the adjusted multivariable analysis. Nevertheless, serum OPG levels did not significantly differ between HS patients and controls. Our results indicate that serum Ang‐2 and ADMA levels are significantly increased in patients with HS. Furthermore, Ang‐2 might be a suitable marker of HS severity. [ABSTRACT FROM AUTHOR]

Ganoderma mushrooms have been used to treat rheumatoid arthritis (RA) in East Asia. Whether Ganoderic acid A (GAA), the natural product extracted from Ganoderma, could be utilized to alleviate osteoarthritis (OA) is investigated in this study. Destabilization of the medial meniscus (DMM) model was constructed to reveal the in vivo effect of GAA. We found that GAA could significantly alleviate the pathology of DMM, as confirmed by the diminished maximum histologic scores. On the contrary, GAA could down‐regulate the relative expression of osteoprotegerin (OPG) and up‐regulate the relative expression of nuclear factor kappa‐B ligand (RANKL) in DMM cartilage and human articular chondrocytes (HC‐A) cells with diminished matrix metallopeptidase 13 (MMP‐13) secretion in the synovial fluid. It was further demonstrated that the serum concentration of OPG was correlated with the severity of osteoarthritis. All these data reveal that GAA could improve OA by regulating the RANKL/OPG ratio to inhibit the secretion of MMP‐13. [ABSTRACT FROM AUTHOR]

Diabetic osteoporosis is secondary osteoporosis and a serious complication of diabetes with a high incidence rate and poor prognosis. The specific mechanism of diabetic osteoporosis is unclear, and prevention and treatment options are limited. Recently, melatonin has been found to prevent and treat diabetic osteoporosis. Herein, we investigated the mechanism whereby melatonin inhibits osteoclastogenesis and identified a new target for osteoporosis treatment. We established an in vitro osteoblast–osteoclast co‐culture system as a diabetic osteoporosis model. Osteoclastogenesis was determined using tartrate‐resistant acid phosphatase staining and cathepsin K expression. Real‐time PCR was used to ascertain expression of microRNA mir‐882, targeting Rev‐Erbα. Western blotting was performed to detect the expression of Rev‐Erbα, receptor activator of NF‐kB ligand (RANKL), and osteoprotegerin (OPG), and ELISA was utilized to analyse the secreted form of RANKL. High glucose promoted osteoclastogenesis and elevated the RANKL/OPG ratio in osteoblasts, while melatonin reversed these effects. High glucose inhibited Rev‐Erbα expression, while melatonin promoted its expression. Conversely, high glucose promoted mir‐882 expression, while melatonin inhibited it. We infer that melatonin inhibits RANKL expression in osteoblasts via the mir‐882/Rev‐Erbα axis, thus inhibiting osteoclastogenesis. Our findings provide insights into diabetic osteoporosis and identify a new therapeutic target for osteoporosis. [ABSTRACT FROM AUTHOR]

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]

Pathogenesis of the beginning and progression of nonalcoholic fatty liver disease (NAFLD) has not been clarified exactly. The osteoprotegerin (OPG)/receptor activator of NF‐κB ligand (RANKL) axis seems to play an imperative function in the onset and progression of this disease. The goal of the present study was to investigate the peripheral blood mononuclear cell (PBMC) expression and plasma levels of RANKL and OPG cytokines in NAFLD patients and compare them with healthy group. Plasma levels of OPG and RANKL were determined with ELISA kits in 57 men with NAFLD and 25 healthy men as controls. Biochemical and anthropometric parameters tests were also evaluated in the study groups. RANKL and OPG mRNA contents were evaluated by quantitative RT‐PCR. OPG contents were markedly decreased in NAFLD patients as compared with healthy patients [1.43 (1.05–5.45)] versus [2.94 (1.76–4.73)] ng/mL; P = 0.007). The levels of RANKL were significantly reduced in NAFLD patients [74.00 (56.26–203.52) ng/mL] than in healthy patients [119.37 (83.71–150.13) ng/mL]; (P = 0.03). Also, OPG and RANKL gene expression were significantly decreased in NAFLD patients in comparison with the control group (P < 0.05). Moreover, receiver operating characteristic curve indicated that OPG may have a good capability to discriminate between NAFLD patients and normal individuals. A positive correlation was observed between OPG and RANKL in plasma sample (r = 0.495) (P = 0.000). Decreased plasma levels and gene expression of RANKL and OPG cytokines in NAFLD patients indicate that there is a relationship between these cytokines and the pathology of NAFLD disease. Confirmation of this association as well as the mechanism and role of these cytokines in NAFLD require further studies. [ABSTRACT FROM AUTHOR]

Background: Glucose and lipid abnormalities, oxidative stress (OXS) and reduced brain‐derived neurotrophic factor (BDNF) are involved in cognitive dysfunction in diabetes. Glucagon like peptide 1 (GLP1) receptors modulate glucose and lipid metabolism, cognitive function and serum osteocalcin. On the other hand, osteocalcin modulates cognitive function and glucose and lipid metabolism. This study investigated whether the GLP 1 agonist liraglutide improves cognitive function via modulation of serum osteocalcin and glucose and lipid metabolism. Methods: Effects of 4 weeks liraglutide treatment (100 µg/Kg/d and 300 µg/Kg/d) on changes in cognitive function and bone homeostasis, induced by high fat diet/low‐dose streptozotocin (HFD‐STZ), were determined in rats. Cognitive function was assessed using Morris water maze (MWM) test. Serum and bone biochemical parameters were determined. Results: Liraglutide dose‐dependently improved cognitive function in diabetic rats (reduced escape latency, and increased time spent in target quadrant in MWM test, compared to diabetic control). Glucose and lipid abnormalities and the associated changes in serum BDNF and oxidative stress makers were improved. Serum BDNF and glutathione were significantly increased, whereas malondialdehyde level was reduced. Serum osteocalcin was significantly increased and correlated with improvement in cognitive dysfunction. Serum and bone receptor activator of nuclear factor κB ligand (RANKL)/osteoprotegerin ratios were significantly reduced by liraglutide treatment. Conclusion: Improvement of cognitive dysfunction by liraglutide involves modulation of glucose and lipid metabolism and serum osteocalcin. GLP1 agonists may provide an alternative metabolic approach for cognitive dysfunction in diabetes. [ABSTRACT FROM AUTHOR]

However, the clinical phenotypes in AD with high serum RANKL or RANKL/OPG ratio might represent the characteristics of severe AD, since those AD subgroups showed high severity. The differences of serum RANKL levels (A, C) and RANKL/OPG ratio (B, D) were analyzed between the adults' subgroups: healthy controls, AD (EASI < 16), and AD (EASI >= 16). Serum receptor activator of nuclear factor kappa- ligand/osteoprotegerin ratio correlates with severity and suggests fracture's risk in older women with atopic dermatitis. [Extracted from the article]

Osteoporosis is one of the most common skeletal disorders caused by the imbalance between bone formation and resorption, resulting in quantitative loss of bone tissue. Since stem cell‐derived extracellular vesicles (EVs) are growing attention as novel cell‐free therapeutics that have advantages over parental stem cells, the therapeutic effects of EVs from adipose tissue‐derived stem cells (ASC‐EVs) on osteoporosis pathogenesis were investigated. ASC‐EVs were isolated by a multi‐filtration system based on the tangential flow filtration (TFF) system and characterized using transmission electron microscopy, dynamic light scattering, zeta potential, flow cytometry, cytokine arrays, and enzyme‐linked immunosorbent assay. EVs are rich in growth factors and cytokines related to bone metabolism and mesenchymal stem cell (MSC) migration. In particular, osteoprotegerin (OPG), a natural inhibitor of receptor activator of nuclear factor‐κB ligand (RANKL), was highly enriched in ASC‐EVs. We found that the intravenous administration of ASC‐EVs attenuated bone loss in osteoporosis mice. Also, ASC‐EVs significantly inhibited osteoclast differentiation of macrophages and promoted the migration of bone marrow‐derived MSCs (BM‐MSCs). However, OPG‐depleted ASC‐EVs did not show anti‐osteoclastogenesis effects, demonstrating that OPG is critical for the therapeutic effects of ASC‐EVs. Additionally, small RNA sequencing data were analysed to identify miRNA candidates related to anti‐osteoporosis effects. miR‐21‐5p in ASC‐EVs inhibited osteoclast differentiation through Acvr2a down‐regulation. Also, let‐7b‐5p in ASC‐EVs significantly reduced the expression of genes related to osteoclastogenesis. Finally, ASC‐EVs reached the bone tissue after they were injected intravenously, and they remained longer. OPG, miR‐21‐5p, and let‐7b‐5p in ASC‐EVs inhibit osteoclast differentiation and reduce gene expression related to bone resorption, suggesting that ASC‐EVs are highly promising as cell‐free therapeutic agents for osteoporosis treatment. [ABSTRACT FROM AUTHOR]

Anti‐RANKL (receptor activator of nuclear factor kappa‐B ligand) agents function by blocking the differentiation of osteoclasts, thereby proving useful in the clinical management of postmenopausal osteoporosis. The effects of such agents on osseointegration is less well understood. The purpose of the current study was to investigate whether osteoprotegerin (OPG), an osteoclast inhibitor, enhances the known anabolic effects of mechanical loading (VEH) and intermittent PTH (iPTH) using a well‐established rabbit model of osseointegration. In the first set of experiments, OPG was administered either alone or combined with iPTH to study its effects on measured bone mass. The second set of experiments was conducted using a higher dosage of OPG (10 mg/kg) to explore its early impact at the cellular and molecular levels. All subjects had mechanical load applied to the implant on one extremity, and no load applied on the contralateral side. In the first set of experiments, OPG alone decreased peri‐implant bone mass compared to the mechanical loading group, whereas OPG + iPTH increased peri‐implant bone mass compared to the OPG group. In the second set of experiments, high‐dose OPG significantly decreased osteoclast number (−74.3%) at 1 week. However, this effect was not sustained as osteoclast number returned to baseline by 2 weeks. These results suggest that systemic administration of OPG does not enhance osseointegration, but rather has a detrimental effect. [ABSTRACT FROM AUTHOR]

Periodontal ligament fibroblasts (PdLFs) are an elongated cell type in the periodontium with matrix and bone regulatory functions which become abnormal in periodontal disease (PD). Here we found that the normally elongated and oriented PdLF nucleus becomes rounded and loses orientation in a mouse model of PD. Using in vitro micropatterning of cultured primary PdLF cell shape, we show that PdLF elongation correlates with nuclear elongation and the presence of thicker, contractile F‐actin fibers. The rounded nuclei in mouse PD models in vivo are, therefore, indicative of reduced actomyosin tension. Inhibiting actomyosin contractility by inhibiting myosin light chain kinase, Rho kinase or myosin ATPase activity, in cultured PdLFs each consistently reduced messenger RNA levels of bone regulatory protein osteoprotegerin (OPG). Infection of cultured PdLFs with two different types of periodontal bacteria (Porphyromonas gingivalis and Fusobacterium nucleatum) failed to recapitulate the observed nuclear rounding in vivo, upregulated nonmuscle myosin II phosphorylation and downregulated OPG. Collectively, our results add support to the hypothesis that PdLF contractility becomes decreased and contributes to disease progression in PD. [ABSTRACT FROM AUTHOR]

Whether T cells promote bone loss following immobilization after spinal cord injury (SCI) remains undetermined. Therefore, wild‐type (WT) and T cell–deficient (Tcrb−/−) male mice underwent sham or contusion SCI to cause hindlimb paralysis. Femurs were isolated and distal and midshaft regions were evaluated by microcomputed tomography scanning. Bone marrow (BM) levels of bone turnover markers, as well as receptor activator of nuclear factor‐kappa B ligand (RANKL) and osteoprotegerin (OPG), were measured by ELISA. At 2 weeks post‐SCI, immobilization resulted in marked reduction in trabecular fractional bone volume (55%), thickness (40%), connectivity, and cortical thickness only in the Tcrb−/− animals (interaction with P < 0.05). BM analysis revealed lower bone formation (procollagen type 1 intact N‐terminal propeptide), higher bone resorption (tartrate‐resistant acid phosphatase‐5b), and a higher RANKL/OPG ratio in the Tcrb−/− SCI animals. At 5 weeks post‐SCI, while both WT and Tcrb−/− paralyzed animals showed deterioration of all indices of bone structure, they were more severe in Tcrb−/− animals. In summary, unlike other skeletal disorders, loss of αβ T cells compromises, rather than preserves, skeletal integrity under conditions of immobilization. [ABSTRACT FROM AUTHOR]

Osteoclasts (OCs) differentiate from the monocyte/macrophage lineage, critically regulate bone resorption and remodelling in both homeostasis and pathology. Various immune and non‐immune cells help initiating activation of myeloid cells for differentiation, whereas hyper‐activation leads to pathogenesis, and mechanisms are yet to be completely understood. Herein, we show the efficacy of dental pulp–derived stem cells (DPSCs) in limiting RAW 264.7 cell differentiation and underlying molecular mechanism, which has the potential for future therapeutic application in bone‐related disorders. We found that DPSCs inhibit induced OC differentiation of RAW 264.7 cells when co‐cultured in a contact‐free system. DPSCs reduced expression of key OC markers, such as NFATc1, cathepsin K, TRAP, RANK and MMP‐9 assessed by quantitative RT‐PCR, Western blotting and immunofluorescence detection methods. Furthermore, quantitative RT‐PCR analysis revealed that DPSCs mediated M2 polarization of RAW 264.7 cells. To define molecular mechanisms, we found that osteoprotegerin (OPG), an OC inhibitory factor, was up‐regulated in RAW 264.7 cells in the presence of DPSCs. Moreover, DPSCs also constitutively secrete OPG that contributed in limiting OC differentiation. Finally, the addition of recombinant OPG inhibited OC differentiation in a dose‐dependent manner by reducing the expression of OC differentiation markers, NFATc1, cathepsin K, TRAP, RANK and MMP9 in RAW 264.7 cells. RNAKL and M‐CSF phosphorylate AKT and activate PI3K‐AKT signalling pathway during osteoclast differentiation. We further confirmed that OPG‐mediated inhibition of the downstream activation of PI3K‐AKT signalling pathway was similar to the DPSC co‐culture–mediated inhibition of OC differentiation. This study provides novel evidence of DPSC‐mediated inhibition of osteoclastogenesis mechanisms. [ABSTRACT FROM AUTHOR]

Studies have shown that long non‐coding RNA (lncRNA) MEG3 plays a key role in osteoporosis (OP), but its regulatory mechanism is somewhat incompletely clear. Here, we intend to probe into the mechanism of MEG3 on OP development by modulating microRNA‐214 (miR‐214) and thioredoxin‐interacting protein (TXNIP). Rat models of OP were established. MEG3, miR‐214 and TXNIP mRNA expression in rat femoral tissues were detected, along with TXNIP, OPG and RANKL protein expression. BMD, BV/TV, Tb.N and Tb.Th in tissue samples were measured. Ca, P and ALP contents in rat serum were also determined. Primary osteoblasts were isolated and cultured. Viability, COL‐I, COL‐II and COL‐Χ mRNA expression, PCNA, cyclin D1, OCN, RUNX2 and osteolix protein expresion, ALP content and activity, and mineralized nodule area of rat osteoblasts were further detected. Dual‐luciferase reporter gene and RNA‐pull down assays verified the targeting relationship between MEG3, miR‐214 and TXNIP. MEG3 and TXNIP were up‐regulated while miR‐214 was down‐regulated in femoral tissues of OP rats. MEG3 silencing and miR‐214 overexpression increased BMD, BV/TV, Tb.N, Tb.Th, trabecular bone area, collagen area and OPG expression, and down‐regulated RANKL of femoral tissues in OP rats. MEG3 silencing and miR‐214 overexpression elevated Ca and P and reduced ALP in OP rat serum, elevated osteoblast viability, differentiation ability, COL‐I and COL‐Χ expression and ALP activity, and reduced COL‐II expression of osteoblasts. MEG3 specifically bound to miR‐214 to regulate TXNIP. MEG3 silencing and miR‐214 overexpression promote proliferation and differentiation of osteoblasts in OP by down‐regulating TXNIP, which further improves OP. [ABSTRACT FROM AUTHOR]

Osteoclastogenesis requires the involvement of transcription factors and degrading enzymes, and is regulated by upstream and downstream signalling. However, c‐Fos how regulates osteoclastogenesis through autophagy remain unclear. This study aimed to explore the role of c‐Fos during osteoprotegerin (OPG)‐mediated suppression of osteoclastogenesis. We found that the number of osteoclasts and the expression of c‐Fos, MMP‐9, CAⅡ, Src and p62 were decreased after treated with OPG, including attenuation the PI3K/Akt and the TAK1/S6 signalling pathways, but the expression of Beclin1 and LC3Ⅱ were increased. Knockdown of Beclin1 could reverse the expression of c‐Fos and MMP‐9 by activating the PI3K/Akt signalling pathway, but inhibiting the autophagy and the TAK1/S6 signalling pathway. In addition, inhibition of autophagy using the PI3K inhibitor LY294002 did not rescues OPG‐mediated suppression of osteoclastogenesis, but caused reduction of the expression of c‐Fos and CAⅡ by attenuating the autophagy, as well as the PI3K/Akt and the TAK1/S6 signalling pathways. Furthermore, continuous activation of c‐Fos could reverse OPG‐mediated suppression of osteoclastogenesis by activating the autophagy and the PI3K/Akt and the TAK1/S6 signalling pathways. Thus, overexpression of c‐Fos could reverse OPG‐mediated suppression of osteoclastogenesis via activation of Beclin1‐induced autophagy, indicating c‐Fos might serve as a new candidate for bone‐related basic studies. [ABSTRACT FROM AUTHOR]

Aim: In this study, we investigated the osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-kappa Β ligand (sRANKL) serum levels in association with thyroid function in children with subclinical hypothyroidism.Methods: In 143 children and adolescents with subclinical hypothyroidism and 343 with normal thyroid function, age, height, weight and pubertal status were recorded and TSH, free thyroxine (FT4), anti-thyroid antibodies, OPG and sRANKL were measured in serum. Multiple linear regression was used for the statistical analysis with P < .05.Results: Children with subclinical hypothyroidism had higher TSH and lower FT4 serum levels than the control group (P < .05). Both groups had similar BMI Z-score, OPG and sRANKL serum levels. After multiple regression analysis, in children with subclinical hypothyroidism, OPG was negatively associated with FT4 (P < .05) whilst no association was observed between OPG and sRANKL, as well as between FT4 serum levels and RANKL.Conclusion: Osteoprotegerin levels in children with subclinical hypothyroidism do not differ from those of euthyroid children. However, there is a negative association between FT4 and OPG levels observed only in the SH group. Considering the link between vascular dysfunction and alterations in osteoprotegerin levels, further research is needed to establish the role of childhood subclinical hypothyroidism in the long-term cardiovascular risk. [ABSTRACT FROM AUTHOR]

Runt‐related transcription factor 2 (Runx2) has been shown to regulate osteoblast differentiation by directly or indirectly regulating numerous osteoblast‐related genes. However, our understanding of the transcriptional mechanisms of RUNX2 is mainly restricted to its transactivation, while the mechanism underlying its inhibitory effect during osteoblast differentiation remains largely unknown. Here, we incorporated the anti‐RUNX2 chromatin immunoprecipitation (ChIP) sequencing in MC3T3‐E1 cells and RNA‐sequencing of parietal bone from Runx2 heterozygous mutant mice, to identify the putative genes negatively regulated by RUNX2. We identified HtrA serine peptidase 1 (Htra1) as a target gene and found ten candidate Htra1 enhancers potentially regulated by RUNX2, among which seven were verified by dual‐luciferase assays. Furthermore, we investigated the motifs in the vicinity of RUNX2‐binding sites and identified early growth response 1 (EGR1) as a potential partner transcription factor (TF) potentially regulating Htra1 expression, which was subsequently confirmed by Re‐ChIP assays. RUNX2 and EGR1 co‐repressed Htra1 and increased the expression levels of other osteoblast marker genes, such as osterix, osteocalcin, and osteoprotegerin at the messenger RNA and protein level. Moreover, Alizarin red staining combined with alkaline phosphatase (ALP) staining showed decreased calcified nodules and ALP activity in the siRUNX2+siEGR1 group compared with siRUNX2 group. Our findings revealed the detailed mechanism of the inhibitory function of RUNX2 towards its downstream genes, along with its partner TFs, to promote osteoblast differentiation. [ABSTRACT FROM AUTHOR]

Autophagy plays a critical role in the maintenance of bone homeostasis. Osteoprotegerin (OPG) is an inhibitor of osteoclast‐mediated bone resorption. However, whether autophagy is involved in the antiosteoclastogenic effects of OPG remains unclear. The present study aimed to investigate the potential mechanism of autophagy during OPG‐induced bone resorption via inhibition of osteoclasts differentiated from bone marrow‐derived macrophages in BALB/c mice. The results showed that after treatment with receptor activator of nuclear factor‐κΒ ligand and macrophage colony‐stimulating factor for 3 days, TRAP+ osteoclasts formed, representing the resting state of autophagy. These osteoclasts were treated with OPG and underwent autophagy, as demonstrated by LC3‐II accumulation, acidic vesicular organelle formation, and the presence of autophagosomes. The levels of autophagy‐related proteins, LC3‐II increased and P62 decreased at 3 hr in OPG‐treated osteoclasts. The viability, differentiation, and bone resorption activity of osteoclasts declined after OPG treatment. Treatment with OPG and chloroquine, an autophagy inhibitor, attenuated OPG‐induced inhibition of osteoclastic bone resorption, whereas rapamycin (RAP), an autophagy inducer, enhanced OPG‐induced inhibition of differentiation, survival, and bone resorption activity of osteoclasts. Furthermore, OPG reduced the amount of phosphorylated(p) protein kinase B (AKT) and pmTOR and increased the level of pULK, in a dose‐dependant manner. LY294002, a phosphatidylinositol‐4,5‐bisphosphate 3‐kinase (PI3K)/AKT pathway inhibitor, attenuated the decline in pAKT, but enhanced the decline in pmTOR and the increase in pULK1 following OPG treatment. RAP enhanced the OPG‐induced increase in pULK1. The PI3K inhibitor 3‐methyladenine partly blocked OPG‐induced autophagy. Thus, the results revealed that OPG inhibits osteoclast bone resorption by inducing autophagy via the AKT/mTOR/ULK1 signaling pathway. [ABSTRACT FROM AUTHOR]

Background: The only polymorphism that could change the protein structure in vitamin D receptor (VDR) is the FokI polymorphism (rs2228570). The FF genotype has the strongest transcriptional activity of VDR and is correlated with higher susceptibility to periodontitis. To reveal the possible molecular mechanisms for the correlation preliminarily, the influence of VDR-FokI genotype on the expression of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) in human gingival fibroblasts (hGFs) and human periodontal ligament cells (hPDLCs) was investigated in this study.Methods: hGFs and hPDLCs from 15 donors (five FF, seven Ff, and three ff) were treated with 1,25OH2 D3 , with or without the specific knockdown of VDR using siRNA. The mRNA and protein expression of OPG and RANKL were detected using real-time PCR and enzyme-linked immunosorbent assay, respectively.Results: Both in hGFs and hPDLCs, 1,25OH2 D3 could significantly induce the mRNA and protein expression of RANKL, and FF genotype had significantly higher induction than the other genotypes, however, neither 1,25OH2 D3 nor VDR-FokI had significant influence on the OPG expression. As a result, the RANKL/OPG ratio was significantly elevated under 1,25OH2 D3 stimulation and FF genotype had the most remarkable elevation. When VDR was knocked down, all the differences among the three genotypes disappeared.Conclusion: The strongest transcriptional activity of FF genotype might contribute to the strongest enhancement of RANKL expression and RANKL/OPG ratio in hGFs and hPDLCs stimulated by 1,25OH2 D3 , which might help to reveal the mechanisms of the correlation between FF genotype and susceptibility to periodontitis. [ABSTRACT FROM AUTHOR]

This pilot study examined how exemestane (an aromatase inhibitor [AI]) affected osteoprotegerin (OPG) urine concentrations in postmenopausal women. Exemestane (25 mg, single dose) was given to 14 disease‐free women past menopause in this nonrandomized, open‐label study. Before dosing, urine specimens were gathered. Three days later, these women returned to provide urine specimens for pharmacokinetic (measurement of major parent drug and enzymatic product) and pharmacodynamic (profiling of OPG) analysis. Urine concentrations of the major parent drug (exemestane) and enzymatic product (17‐hydroexemestane) were quantified using liquid chromatography‐tandem mass spectrometry. An analyst software package was used for data processing. Following the manufacturer's guidelines, OPG urine concentrations were quantified using a human osteoprotegerin TNFRSF11b ELISA kit from Sigma‐Aldrich. A microplate reader helped to carry out OPG data analysis and processing. Our results highlight that OPG urine concentrations were decreased 3 days after drug dosage (mean predosage OPG concentration, 61.4 ± 24.1 pg/mL; vs mean postdosage OPG concentration, 45.7 ± 22.1 pg/mL; P =.02, Wilcoxon rank test). Among the 14 volunteers enrolled in the study, 4 subjects had an increase of less than 1‐fold, and the rest showed an average of a 2‐fold decrease in OPG concentration (range, 1.1‐5.4; standard deviation, 1.3) after exemestane administration. There was no association between fold decrease in OPG urine concentration and the pharmacokinetics of the major parent drug (exemestane) and its enzymatic product (17‐hydroexemestane). We concluded that one of the off‐target pharmacological effects of AIs (eg ,exemestane) may result in the reduction of osteoprotegerin. [ABSTRACT FROM AUTHOR]

Background and objectives: Strontium ranelate is a medication indicated for the treatment of osteoporosis that presents concomitant anti‐resorptive and osteoanabolic dual biological activity. However, the effects of strontium ranelate on alveolar bone have been poorly explored. Furthermore, to date, there are no data on the effects of this medication on alveolar bone loss (BL) during conditions of estrogen deficiency. Therefore, the aim of this study was to evaluate the effects of strontium ranelate on ligature‐induced periodontitis in estrogen‐deficient and estrogen‐sufficient rats. Methods: Ninety‐six rats were assigned to one of the following groups: sham‐surgery + water (estrogen‐sufficient; n = 24); ovariectomy + water (estrogen‐deficient; n = 24), sham‐surgery + strontium ranelate (ranelate/estrogen‐sufficient; n = 24) and; ovariectomy + strontium ranelate (ranelate/estrogen‐deficient; n = 24). The rats received strontium ranelate or water from the 14th day after ovariectomy until the end of the experiment. On the 21st day after ovariectomy, one first mandibular molar received a ligature, while the contralateral tooth was left unligated. Eight rats per group were killed at 10, 20, and 30 days after ligature placement. Bone loss (BL) and trabecular bone area (TBA) were analyzed in the furcation area of ligated and unligated teeth at all experimental times by histometry. Tartrate‐resistant acid phosphatase (TRAP) positive cells and immunohistochemical staining for osteocalcin (OCN), osteopontin (OPN), osteoprotegerin (OPG), and receptor activator of NF‐КB ligand (RANKL) were assessed in the ligated teeth at 30 days after ligature placement. Results: At 10 and 30 days, ligated teeth of the estrogen‐deficient group exhibited higher BL, when compared to all other groups (P <.05). At 10 days, TBAs were higher in the unligated teeth of strontium ranelate‐treated groups, when compared to those of untreated groups (P <.05). At 30 days, the ligated teeth of the estrogen‐deficient group exhibited lower TBA than the other groups (P <.05). There were no differences among groups regarding the number of TRAP‐stained cells (P <.05). The strontium ranelate‐treated groups exhibited lower expressions of OCN and RANKL than the untreated groups (P <.05). The estrogen‐sufficient group presented higher staining for OPG than both treated and untreated estrogen‐deficient groups (P <.05). Conclusions: Strontium ranelate prevented ligature‐induced BL in an estrogen‐deficiency condition and, to a certain extent, increased TBA in the presence and absence of periodontal collapse in states of estrogen deficiency and estrogen sufficiency. Furthermore, strontium ranelate also affected the expression of bone markers, appearing to have acted predominantly as an anti‐resorptive agent. [ABSTRACT FROM AUTHOR]

Aim: To investigate the effects of systemically administered melatonin on inflammation and alveolar bone resorption in rats with experimentally induced periapical lesions. Methodology: Thirty adult Sprague Dawley rats were divided equally into negative, positive control and melatonin groups. The pulp chambers of their mandibular first molars were exposed to the oral environment to induce experimental periapical lesions in the positive control and melatonin groups. The melatonin group received daily intraperitoneal injections of melatonin at a dose of 10 mg kg−1. After 21 days, the animals were euthanized; the hemi‐mandible parts were prepared for radiological, histopathological, immunohistochemical (IL‐1β, RANK, RANKL, OPG and tartrate‐resistant acid phosphatase (TRAP) and Brown–Brenn (bacteria) evaluations. Data were analysed by Kruskal–Wallis (for non‐parametric data) and one‐way anova tests (for parametric data) (P < 0.05). Results: The area of radiographic periapical bone loss was significantly smaller in rats that were given daily intraperitoneal injections of melatonin (P < 0.01). The histopathological scores of the melatonin group were significantly lower than those of positive control group (P < 0.01). Histomorphometrically, the area of periapical bone loss in the melatonin group was significantly smaller than the positive control group (P < 0.01). The expression of IL1‐β, RANK and RANKL was significantly higher in the positive control group, whereas OPG was significantly higher in the melatonin group (P < 0.01). The number of osteoclasts was significantly greater in the positive control group by TRAP staining analyses (P < 0.01). The scores for bacteria localization using Brown–Brenn staining in the melatonin group was significantly lower than that of the positive control group (P < 0.01). Conclusions: Melatonin demonstrated antiresorptive effects on bone associated with experimentally induced periapical lesions in rats via its anti‐inflammatory activity. Further studies are necessary to evaluate its possible effects on the healing of periapical lesions. [ABSTRACT FROM AUTHOR]

Fibrosis is characterized by the progressive alteration of the tissue structure due to the excessive production of extracellular matrix (ECM). The signaling system encompassing Receptor Activator of Nuclear factor NF‐κB Ligand (RANKL)/RANK/Osteoprotegerin (OPG) was discovered to play an important role in the regulation of ECM formation and degradation in bone tissue. However, whether and how this signaling pathway plays a role in liver or pulmonary ECM degradation is unclear up to now. Interestingly, increased decoy receptor OPG levels are found in fibrotic tissues. We hypothesize that RANKL can stimulate RANK on macrophages and initiate the process of ECM degradation. This process may be inhibited by highly expressed OPG in fibrotic conditions. In this case, RANKL mutants that can bind to RANK without binding to OPG might become promising therapeutic candidates. In this study, we built a structure‐based library containing 44 RANKL mutants and found that the Q236 residue of RANKL is important for OPG binding. We show that RANKL_Q236D can activate RAW cells to initiate the process of ECM degradation and is able to escape from the obstruction by exogenous OPG. We propose that the generation of RANKL mutants with reduced affinity for OPG is a promising strategy for the exploration of new therapeutics against fibrosis. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the relationship between inflammation‐related T‐helper cell polarization and the receptor activator for nuclear factor‐κB ligand (RANKL)/osteoprotegerin (OPG) ratio, which is associated with bone resorption or remodeling of chronic periodontitis patients. Gingival crevicular fluid (GCF) and gingival tissues were obtained from periodontally healthy individuals (PH group) and chronic periodontitis patients (CP group). The GCF levels of IFN‐γ, IL‐4, IL‐17, and IL‐10 linked to T‐helper cell polarization toward the Th1, Th2, Th17, and Treg phenotypes, respectively, were determined by ELISA. The expression levels of these cytokines and the polarized T‐helper cells in gingival tissues were assessed through immunohistochemical and immunofluorescence assays. In addition, the RANKL and OPG expression levels in gingival tissues were detected by immunohistochemical assays, and linear regression analysis was used to identify the potential relationship between T‐helper cell polarization and the RANKL/OPG ratio. In total, 22 individuals and 35 patients were enrolled in the present study. In both GCF and gingival tissues, increased levels of IL‐17 and the decreased levels of IL‐4 and IL‐10 were observed in the CP group. When polarized T‐helper cells were identified in gingival tissues, more Th1 and Th17 cells were found in the CP group, whereas more Th2 and Treg cells were found in the PH group. Although there was no significant difference in OPG expression between the two groups, the RANKL/OPG ratio in the CP group was higher than that in the PH group. The linear regression analysis showed that the presence of more Th1 and Th17 cells correlated with a higher RANKL/OPG ratio, whereas the presence of more Th2 cells correlated with a lower RANKL/OPG ratio. Th1 and Th17 cells are positively correlated and Th2 cells are negatively correlated with the RANKL/OPG ratio. Our data suggest that T‐helper cell polarization is closely linked to the RANKL/OPG ratio in gingival tissues from chronic periodontitis patients. [ABSTRACT FROM AUTHOR]

It has been demonstrated in animal studies that prenatal administration of β‐hydroxy‐β‐methylbutyrate (HMB, metabolite of leucine) influences general growth and mechanical endurance of long bones in newborn offspring in sex‐dependent manner. The present experiment was conducted to evaluate the effect of HMB treatment of pregnant sows on bone development in offspring at weaning. From 70th day until the 90th day of gestation, sows received either a basal diet (n = 12) or the same diet supplemented with HMB (n = 12) at the dose of 0.2 g/kg of body weight/day. Femora obtained from six males and females in each group weaned at the age of 35 days were examined. Maternal HMB treatment significantly enhanced body weight and changed bone morphology increasing femur mechanical strength in both sexes. Maternal HMB supplementation also elevated bone micro‐ and macroelement concentrations and enhanced content of proteoglycans in articular cartilage. Based on the obtained results, it can be concluded that maternal HMB supplementation in the mid‐gestation period significantly accelerated bone development in both sexes by upregulation of a multifactorial system including leptin and osteoprotegerin. However, the sex (irrespective of the HMB treatment) was the factor which influenced the collagen structure in cartilages and trabecular bone, as demonstrated both by the Picrosirius red staining and performed analysis of thermal stability of collagenous tissues. The structural differences in collagen between males and females were presumably related to a different collagen maturity. No studies conducted so far provided a detailed morphological analysis of bone, articular cartilage, growth plate and the activities of the somatotropic and pituitary–gonadal axes, as well as leptin/osteoprotegerin system in weaned offspring prenatally treated with HMB. This study showed also the relationship between the maternal HMB treatment and bone osteometric and mechanical traits, hormones, and growth and bone turnover markers such as leptin, osteoprotegerin and insulin‐like growth factor‐1. [ABSTRACT FROM AUTHOR]

Background: RANKL and RANK play an important role in jaw resorption during the development of the ameloblastomas. Therefore, the aim of this study was to explore the effect of 99 Tc-MDP on OPG/RANKL/RANK system on RAW264.7 and MC3T3-E1 cell lines in vitro and provide the theoretical basis for the clinical treatment of the jaw ameloblastoma.Methods: Different concentrations of 99 Tc-MDP were used to treat RAW264.7 and MC3T3-E1 cell lines. The cell proliferative inhibition rate was analyzed by CCK-8. Cell apoptosis and cell cycle were detected by flow cytometry. Western blot was used to detect the expression of OPG, RANKL, and RANK.Results: Treatment of RAW264.7 cell lines with different concentrations of 99 Tc-MDP had inhibitory effects and decreased the expression of RANK protein. The cell proliferation of 99 Tc-MDP on MC3T3-E1 cell lines was stronger at 48 hours than at 24 hours except for 100 μg/mL concentration group. Compared with the concentration of 0.01 μg/mL, the treatment of MC3T3-E1 cells with 100 μg/mL 99 Tc-MDP showed that the cell proliferative effect decreased at 24 hours and 48 hours (P < 0.05). After treatment with 0.01 μg/mL 99 Tc-MDP, the expression of OPG in MC3T3-E1 cells was significantly increased (P < 0.05). Compared with 0.01 μg/mL, the expression of RANKL was decreased after treatment with 100 μg/mL 99 Tc-MDP (P < 0.05).Conclusion: 99 Tc-MDP can induce apoptosis of RAW264.7 cells and inhibit the expression of RANK protein. The effect of 0.01 μg/mL of low concentration of 99 Tc-MDP can promote the proliferation of MC3T3-E1 cells and increase the expression of OPG and RANKL protein. 99 Tc-MDP may have adjuvant therapeutic effects on the treatment of jaw ameloblastoma. [ABSTRACT FROM AUTHOR]

Peri‐implant osteolysis is commonly diagnosed after substantial bone loss has occurred, making revision surgery more challenging. The goal of the current study was to identify urinary biomarkers that differentiate total hip replacement patients who eventually develop osteolysis from patients who do not. We used a repository of 24‐h urine samples collected prior to surgery and annually thereafter in 26 patients, 16 who developed osteolysis, and 10 who did not. We examined the markers at radiographic diagnosis, annually for 6 years preceding diagnosis, at the first post‐operative sampling point, and pre‐operatively. Patients in the osteolysis and non‐osteolysis groups were matched according to time post‐surgery and did not differ in the male:female ratio or age at surgery. Seven candidate biomarkers were measured, including free deoxypyridinoline (DPD), cross‐linked N‐telopeptides (NTX), interleukin‐6 (IL‐6), interleukin‐8 (IL‐8), osteoprotegerin (OPG), α‐crosslaps (α‐CTX), and β‐crosslaps (β‐CTX). As an individual biomarker, DPD demonstrated the highest ability to predict osteolysis, with an area under the curve (AUC) in Receiver Operating Characteristic (ROC) analyses of 0.844 at 6 years prior to diagnosis. A panel of α‐CTX and IL‐6 was able to identify at‐risk patients with an AUC of 0.941 or greater at all post‐operative time points and an AUC of 1.000 pre‐operatively. The results demonstrate the potential of using non‐invasive biomarkers to identify patients at risk for peri‐implant osteolysis long before the emergence of radiographic signs. Further, the high accuracy of the pre‐operative biomarker levels demonstrates the potential importance of pre‐existing, patient‐specific factors driving subsequent osteolysis. Study Design © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2754–2761, 2018. [ABSTRACT FROM AUTHOR]

Abstract: We studied the correlations between circulating osteoprotegerin (OPG) level and radial artery calcification (RAC) assessed histologically and carotid artery intima‐media thickness (CCA‐IMT). Moreover, we studied the relationship between OPG levels and all‐cause and cardiovascular (CV) mortality during a 5‐year observation period. The study comprised 59 CKD patients (36 hemodialyzed (HD), 23 predialysis). The biochemical parameters included: creatinine, calcium, phosphate, intact parathormone, C‐reactive protein, interleukin‐6, tumor necrosis factor receptor II (TNFRII), transforming growth factor‐β, hepatocyte growth factor, fibroblast growth factor 23, osteonectin (ON), osteopontin, osteoprotegerin, and osteocalcin. CCA‐IMT and the presence of atherosclerotic plaques was assessed by ultrasound. Fragments of radial artery obtained during creation of HD access were prepared for microscopy and stained for calcifications with alizarin red. RAC was detected in 34 patients (58%). In multiple regression adjusted for dialysis status, TNFRII, ON and Framingham risk score (FRS) were identified as the independent predictors of OPG. Serum OPG above the median value of 7.55 pmol/L significantly predicted the presence of RAC in simple logistic regression (OR 5.33; 95%CI 1.39–20.4; P = 0.012) and in multiple logistic regression adjusted for FRS, dialysis status and CCA‐IMT values (OR 6.56; 95%CI 1.06–40.6; P = 0.036). OPG levels above the median were associated with higher CCA‐IMT values (1.02 ± 0.10 vs. 0.86 ± 0.13; P < 0.001) and predicted the presence of atherosclerotic plaques in carotid artery (OR 14.4; 95%CI 2.84–72.9; P < 0.001), independently of FRS, dialysis status and RAC. In this study, elevated serum OPG levels correlated with higher CCA‐IMT, the presence of atherosclerotic plaques and the severity of the RAC independently of each other. During follow‐up, 25 patients (42%) died, including 21 due to CV causes. In multiple Cox regression, OPG above the median predicted overall survival independently of dialysis status, Framingham risk score, CCA‐IMT above the median value, and the presence of atherosclerotic plaques in CCA, but not independently of RAC. We postulate that circulating OPG may play a dual role as a marker for both medial arterial calcification and atherosclerosis, hence it seems to be a valuable tool for assessing CV risk in patients with CKD. OPG might be an early indicator of all‐cause mortality in CKD patients with advanced medial arterial calcification. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To investigate whether apical periodontitis lesions infected by Epstein–Barr virus (EBV) exhibit higher levels of oxidative stress biomarkers [8‐hydroxydeoxyguanosine (8‐OHdG) and oxidized glutathione (GSSG)] and bone resorption regulators [receptor activator of nuclear factor (NF‐κB) ligand (RANKL) and osteoprotegerin (OPG)] compared to EBV‐negative periapical lesions and healthy pulp tissues. Methodology: The experimental group consisted of 30 EBV‐positive and 30 EBV‐negative periapical lesions collected in conjunction with apicoectomy. The pulp tissues of 20 impacted third molars were used as healthy controls. The qualitative and quantitative analysis of EBV was performed by nested and real‐time polymerase chain reaction (PCR), respectively. The levels of RANKL and OPG were analysed by reverse transcriptase real‐time PCR. The levels of 8‐OHdG and GSSG were determined by enzyme‐linked immunosorbent assay (ELISA). Mann–Whitney U‐test and Spearman's correlation were used for statistical analysis. Results: The levels of RANKL, OPG, 8‐OHdG and GSSG were significantly higher in apical periodontitis lesions compared to healthy pulp controls (P = 0.001, P < 0.001, P < 0.001 and P < 0.05, respectively). RANKL and OPG mRNA expression was significantly higher in EBV‐positive compared to EBV‐negative periapical lesions (P < 0.05). There was no significant correlation between EBV copy numbers and levels of RANKL, OPG, 8OH‐dG and GSSG in apical periodontitis. Conclusion: Levels of bone resorption regulators and oxidative stress biomarkers were increased in apical periodontitis compared to healthy pulp tissues. EBV‐positive periapical lesions exhibited higher levels of RANKL and OPG compared to EBV‐negative periapical lesions. EBV may contribute to progression of apical periodontitis via enhanced production of bone resorption regulators. [ABSTRACT FROM AUTHOR]

ABSTRACT: Osteoporosis is a disease characterized by low bone mass and progressive destruction of bone microstructure, resulting in increasing the risk of fracture. Icariin (ICA) as a phytoestrogen shows osteogenic effects, and the mechanical stimulation has been demonstrated the improving effect on osteoporosis. The objective of this study was to investigate the effect of ICA in combination with constrained dynamic loading (CDL) stimulation on osteoporosis in ovariectomized (OVX) mice. The serum hormone levels, bone turnover markers, trabecular architecture, ulnar biomechanical properties, and the expression of osteoblast‐related gene (alkaline phosphatase, ALP; osteocalcin, OCN; bone morphogenetic protein‐2, BMP‐2; Collagen I (α1), COL1; osteoprotegerin, OPG) and osteoclast‐related genes (receptor activators of NF‐κB ligand, RANKL; tartrate‐resistant acid phosphatase, TRAP) were analyzed. The results showed that ICA + CDL treatment could increase the osteocalcin (20.85%), estradiol levels (20.61%) and decrease the TRAP activity (26.27%) significantly than CDL treatment. The combined treatment attenuated bone loss and biomechanical decrease more than single use of CDL treatment. ICA + CDL treatment significantly up‐regulated the level of osteoblast‐related gene expression and down‐regulated the osteoclast‐related genes expression; moreover, the combined treatment increased the ratio of OPG/RANKL significantly compared to ICA (72.83%) or CDL (65.63%) treatment alone. The present study demonstrates that icariin in combination with constrained dynamic loading treatment may have a therapeutic advantage over constrained dynamic loading treatment alone for the treatment of osteoporosis, which would provide new evidence for the clinical treatment of osteoporosis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1415–1424, 2018. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is an emerging global health epidemic. Foundations for new therapies are arising from understanding interactions between body systems. Bonederived factors that reduce RANKL (receptor activator of NF-kappa B ligand) signaling in the liver may prevent insulin resistance and the onset of type 2 diabetes. Here we demonstrate that deletion of the epigenetic regulator, Hdac3, in Osx1-expressing osteoprogenitors prevents insulin resistance induced by high fat diet by increasing serum and skeletal gene expression levels of osteoprotegerin (Opg), a natural inhibitor of RANKL signaling. Removal of one Opg allele in mice lacking Hdac3 in Osx1+ osteoprogenitors increases the insulin resistance of the Hdac3-deficient mice on a high fat diet. Thus, Hdac3-depletion in osteoblasts increases expression of Opg, subsequently preserving insulin sensitivity. The Hdac inhibitor vorinostat also increased Opg transcription and histone acetylation of the Opg locus. These results define a new mechanism by which bone regulates systemic insulin sensitivity. [ABSTRACT FROM AUTHOR]

Abstract: Background: Arterial stiffness and vascular calcification significantly contribute to coronary atherosclerosis progression. The prognostic value of increased arterial stiffness and vascular calcification in subjects with stable coronary artery disease (CAD) after percutaneous coronary intervention(PCI) is currently under question. Materials and Methods: We randomly enrolled 262 patients with stable CAD 1 month after successful PCI. Carotid‐femoral pulse wave velocity (PWV) was measured as a well‐established index of central aortic stiffness. Osteoprotegerin (OPG) plasma levels were measured as a biomarker of vascular calcification. Patients were followed up prospectively up to 52 months. The primary endpoint was the composite of death from cardiovascular causes, myocardial infarction, stroke or hospitalization for cardiovascular causes. Results: During the follow‐up period, 48 patients presented the primary composite endpoint. Subjects who presented the primary endpoint, compared to subjects free of cardiovascular events, had significantly increased PWV (9.45 ± 2.19 m/s vs 8.73 ± 2.07 m/s, P = .04) and OPG levels (4.21 ± 2.19 pmol/L vs 3.18 ± 1.74 pmol/L, P = .003). Survival analysis indicated that PWV predicted adverse cardiac events MACE (Hazard ratio = 1.29 95%CI: 1.07‐1.57, P = .008) independently from confounders such as age, sex, smoking habits, ejection fraction, extent of coronary artery disease, hypertension and diabetes mellitus. Interestingly, for every increase in pulse wave velocity by 1 m/s, there is an anticipated increase in the risk of major adverse cardiovascular event (MACE) by 29%. Conclusions: These findings extend the current knowledge concerning the role of arterial stiffness as powerful biomarkers in cardiovascular disease. Measurement of PWV might have a role in ascertaining prognosis and managing treatment in patients with stable CAD after PCI. [ABSTRACT FROM AUTHOR]

Aim: Haemophilia A and B are associated with reduced bone mineral density (BMD). The aim of this study was to assess circulating sclerostin and dickkopf‐1 (Dkk‐1), (inhibitors of osteoblastic differentiation), as well as the receptor activator of nuclear factor kB ligand (RANKL)/osteoprotegerin (OPG) system (the major regulator of osteoclastogenesis), in patients with haemophilia (PWH), their possible correlations with clinical risk factors and the effect of ibandronate on these markers. Methods: Eighty‐nine male PWH (mean age 45.9 ± 15.3 years) and 30 age‐matched healthy male controls participated. BMD was assessed by DXA. Sclerostin, Dkk‐1, RANKL and OPG were measured in serum of patients, controls, as well as in ten patients receiving oral ibandronate (150 mg/mo), at baseline and after 12 months. Results: Patients with haemophilia had lower circulating sclerostin (median ± IQR: 47.4 ± 26.93 vs 250 ± 250 pmol/L, P < .001), Dkk‐1 (21.24 ± 17.18 vs 26.16 ± 15.32pg/mL, P = .04) and higher levels of RANKL (0.23 ± 0.03 vs 0.04 ± 0.03 pmol/L, P = .001), RANKL/OPG ratio (0.063 ± 0.25 vs 0.005 ± 0.11, P = .001) compared with controls. Patients with low BMD had higher OPG concentrations compared to those with normal BMD. Sclerostin and RANKL/OPG correlated positively with BMD. Patients with severe haemophilia had lower sclerostin concentrations compared with those with mild or moderate disease. The degree of arthropathy negatively correlated with sclerostin and Dkk‐1 levels. PWH who received ibandronate showed a decrease in serum Dkk‐1 without any significant effect on sclerostin and RANKL/OPG. Conclusions: Patients with haemophilia present increased osteoclastic activity coupled with compensatory increased osteoblastic activity. Ibandronate did not affect RANKL/OPG ratio, but it decreased Dkk‐1. [ABSTRACT FROM AUTHOR]

Currently, there are no medications available to treat aseptic loosening of orthopedic implants. Using osteoprotegerin fusion protein (OPG-Fc), we previously blocked instability-induced osteoclast differentiation and peri-prosthetic osteolysis. Wnt/β-catenin signaling, which regulates OPG secretion from osteoblasts, also modulates the bone tissue response to mechanical loading. We hypothesized that activating Wnt/β-catenin signaling by inhibiting glycogen synthase kinase-3β (GSK-3β) would reduce instability-induced bone loss through regulation of both osteoblast and osteoclast differentiation. We examined effects of GSK-3β inhibition on regulation of RANKL and OPG in a rat model of mechanical instability-induced peri-implant osteolysis. The rats were treated daily with a GSK-3β inhibitor, AR28 (20 mg/kg bw), for up to 5 days. Bone tissue and blood serum were assessed by qRT-PCR, immunohistochemistry, and ELISA on days 3 and 5, and by micro-CT on day 5. After 3 days of treatment with AR28, mRNA levels of β-catenin, Runx2, Osterix, Col1α1, and ALP were increased leading to higher osteoblast numbers compared to vehicle-treated animals. BMP-2 and Wnt16 mRNA levels were downregulated by mechanical instability and this was rescued by GSK-3β inhibition. Osteoclast numbers were decreased significantly after 3 days of GSK-3β inhibition, which correlated with enhanced OPG mRNA expression. This was accompanied by decreased serum levels of TRAP5b on days 3 and 5. Treatment with AR28 upregulated osteoblast differentiation, while osteoclastogenesis was blunted, leading to increased bone mass by day 5. These data suggest that GSK-3β inactivation suppresses osteolysis through regulating both osteoblast and osteoclast differentiation in a rat model of instability-induced osteolysis. [ABSTRACT FROM AUTHOR]

Background and Objective The aim of this study was to analyze the differences in inflammatory and catabolic mediators expressed in peri-implantitis compared to periodontitis lesions after non-surgical therapy. Peri-implantitis is associated with a faster rate of bone loss when compared with periodontitis, and peri-implant non-surgical therapy is ineffective to cure peri-implantitis. This may be due to persistent inflammation in peri-implantitis tissues after initial mechanical treatment. Material and Methods Eleven patients with peri-implantitis and 10 with severe chronic periodontitis received non-surgical therapy. They were included at re-evaluation (8 weeks) if they presented pocket depth ≥6 mm with bleeding on probing, and the indication for open flap debridement surgery. Connective tissues were harvested during surgery from diseased sites. Healthy gingiva were harvested during third molar extraction in a third group of healthy patients (n=10). Explants were incubated for 24 hours in media culture and the release of cytokines, chemokines, growth factors, osteoprotegerin, receptor activator of nuclear factor kappa-B ligand ( RANKL), matrix metalloproteinase and tissue inhibitors of matrix metalloproteinase ( TIMP) in the conditioned media was analyzed by an exploratory multiplex immunoassay. When difference was found in the conditioned media, an immunohistochemistry was performed to compare expression in the tissues. Results Connective tissues from non-stabilized peri-implantitis exhibited a distinct cytokine profile compared to periodontitis lesions that did not respond to initial therapy. Indeed, TIMP-2 was significantly increased in media from peri-implantitis ( P≤.05). In addition, the in situ expression of TIMP-2, interleukin-10 and RANKL was also significantly increased in peri-implantitis tissues ( P≤.05). However, the ratio of RANKL/ osteoprotegerin-positive cells did not vary ( P≥.05). Conclusion This study suggests that peri-implantitis and periodontitis connective tissues exhibit differences in response to non-surgical treatment, which may contribute to a different pattern of disease evolution. [ABSTRACT FROM AUTHOR]

Objective To evaluate the effects of metformin on bone healing around titanium implants inserted in non-diabetic rats. Methods Twenty Wistar rats were randomly assigned to one of the following groups: control group ( n = 10): rats without metformin treatment; MT group ( n = 10): rats treated with metformin (40 mg/kg/day by gavage). At thirty days after implant placement, animals were euthanized. Histometric measurements of bone-to-implant contact ( BIC) and bone area ( BA), in addition to immunohistochemical analysis of the number of cells stained for RANKL and OPG, were assessed in the cortical and medullary areas around implants. Results The percentages of BIC and BA in the cortical bone were significantly lower in the MT group than in the control group ( P < 0.05). Furthermore, the medullary bone around the implants inserted in the metformin-treated animals exhibited an increased number of RANKL-stained cells than that around the implants inserted in the control animals ( P < 0.05). Conclusions Metformin negatively affected osseointegration by reducing the percentages of BIC and BA and increasing the expression of RANKL around titanium implants inserted in non-diabetic rats. [ABSTRACT FROM AUTHOR]

Background: Chronic periapical lesions (CPLs) are common lesions of the oral cavity and are the result of caries, tooth fracture, iatrogenic causes, or factors causing contamination and pulp necrosis. Inflammatory cells participate in the expansion of CPLs by releasing factors that stimulate or inhibit osteolytic activity. The objective of this study was to investigate the participation of RANKL, TNF-α, cathepsin K, IL-33, and OPG in the development of radicular cysts (RCs) and periapical granulomas (PGs).Methods: Paraffin-embedded sections of 30 RCs and 22 PGs were submitted to immunohistochemistry.Results: Immunoexpression of the proteins studied was observed in the epithelium and capsule of RCs, as well as in connective tissue of PGs. The expression of the osteoclastogenic factors studied differed significantly in RCs and PGs (P < .001), with lower expression of OPG in RCs. In PGs, the lowest expression was observed for cathepsin K. Comparison of the 2 lesions showed a similar participation of RANKL and IL33, while a significant difference was observed for OPG (P < .001), TNF-α (P = .002), and cathepsin K (P = .016). No association of the expression of the proteins with lesions size was observed.Conclusions: This study demonstrated the participation of RANKL, TNF-α, IL-33, cathepsin K, and OPG in the development of RCs and PGs, with emphasis on the highest immunoreactivity of cathepsin in RCs and TNF-α and OPG in PGs. OPG possibly determines the slower growth of PGs compared to RCs. [ABSTRACT FROM AUTHOR]

Objectives The study aimed to determine the levels of soluble receptor activator of nuclear factor-кB ligand (sRANKL) and osteoprotegerin (OPG) as well as their relative calculated ratio in peri-implant crevicular fluid (PICF) obtained around two different types of implant-abutment connection on short implants following a 12-month monitoring period. Moreover, the levels of a number of oral bacterial species were investigated in the corresponding submucosal biofilm samples. Materials and methods Thirty short implants were randomly placed in posterior maxillary edentulous sites using a split-mouth design in 15 periodontally healthy subjects. Tapered interference fit (TIF) and taper-integrated screwed-in (TIS) types of implant-abutment connections were selected for investigation. PICF and submucosal biofilm samples were collected 1 month after surgery and repeated 12 months after prosthetic loading. Clinical parameters, including probing depth, dichotomous presence of bleeding on probing, and plaque index, were recorded and digital periapical radiographs were taken at each time point. sRANKL and OPG levels in PICF were analyzed using an enzyme-linked immunosorbent assay. Total bacterial levels, as well as levels of Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Prevotella intermedia, and Streptococcus oralis, were analyzed in the corresponding submucosal biofilm samples using quantitative real-time polymerase chain reaction. Results The total amount of sRANKL in TIF implants was 2.64-fold lower than that in TIS implants at baseline ( P < 0.001), whereas similar levels were found after 12 months ( P > 0.05). Accordingly, OPG and RANKL/OPG ratio were similar between the groups at each time point ( P > 0.05). Microbiological results were similar in both groups at each time point ( P > 0.05). Conclusion The results of this longitudinal study suggested that sRANKL and OPG in PICF, as well as microbiological parameters in submucosal biofilms, were similar between TIF and TIS implants, after a 12-month monitoring period, despite early differences in the former. Therefore, the type of implant-abutment connection does not appear to influence longitudinally the levels of osteoimmunological and microbiological markers in the peri-implant tissues of short implants. [ABSTRACT FROM AUTHOR]

Aim To evaluate the effects of photodynamic therapy ( PDT) in the nonsurgical treatment of chronic periodontitis. Materials and methods A randomized, single-blind, controlled, parallel-group clinical trial was performed. Sixty patients were enrolled: 20 healthy controls and 40 patients with periodontitis. The 40 patients were randomized for scaling and root planing ( SRP) or SRP + PDT. Periodontal (plaque index, probing depth, clinical recession, clinical attachment level, bleeding on probing and gingival crevicular fluid volume, corresponding to 381 versus 428 critical sites), microbiological ( Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia and Campylobacter rectus presence, 18 versus 19 samples) and biochemical (interleukin ( IL)-1β, IL-6 and tumour necrosis factor ( TNF)-α, receptor activator of nuclear factor-kappaB ligand ( RANK-L) and osteoprotegerin ( OPG) levels, 18 versus 19 samples) parameters were recorded. Results Within each group, significant improvements were found for clinical parameters, though without significant differences between groups. RANK-L was significantly decreased at week 13 in the SRP + PDT group compared with the SRP group. SRP + PDT, but not SRP alone, significantly reduced the abundance of A. actinomycetemcomitans. Conclusions Except for a significant decrease in the pathogenic burden of A. actinomycetemcomitans, coadjuvant PDT resulted in no additional improvement compared with SRP alone in patients diagnosed with moderate-to-advanced chronic periodontitis. [ABSTRACT FROM AUTHOR]

Tannerella forsythia is a major periodontal pathogen, and T. forsythia GroEL is a molecular chaperone homologous to human heat-shock protein 60. Interleukin-17 (IL-17) has been implicated in the pathogenesis of periodontitis and several systemic diseases. This study investigated the potential of T. forsythia GroEL to induce inflammatory bone resorption and examined the cooperative effect of IL-17 and T. forsythia GroEL on inflammatory responses. Human gingival fibroblasts (HGFs) and periodontal ligament (PDL) fibroblasts were stimulated with T. forsythia GroEL and/or IL-17. Gene expression of IL-6, IL-8, and cyclooxygenase-2 (COX-2) and concentrations of IL-6, IL-8, and prostaglandin E2 (PGE2 ) were measured by real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. After stimulation of MG63 cells with T. forsythia GroEL and/or IL-17, gene expression of osteoprotegerin (OPG) was examined. After subcutaneous injection of T. forsythia GroEL and/or IL-17 above the calvaria of BALB/c mice, calvarial bone resorption was assessed by micro-computed tomography and histological examination. Tannerella forsythia GroEL induced IL-6 and IL-8 production in HGFs and PDL cells, and IL-17 further promoted IL-6 and IL-8 production. Both T. forsythia GroEL and IL-17 synergistically increased PGE2 production and inhibited OPG gene expression. Calvarial bone resorption was induced by T. forsythia GroEL injection, and simultaneous injection of T. forsythia GroEL and IL-17 further increased bone resorption. These results suggest that T. forsythia GroEL is a novel virulence factor that can contribute to inflammatory bone resorption caused by T. forsythia and synergizes with IL-17 to exacerbate inflammation and bone resorption. [ABSTRACT FROM AUTHOR]