Receptor Activator Of Nuclear Factor-kappa Ligand Research Articles

Salivary levels of Osteoprotegerin and receptor activator of nuclear factor-kappa ligand during orthodontic tooth movement-A prospective pilot study.

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). 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. 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. 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.

Wedelolactone ameliorates synovial inflammation and cardiac complications in a murine model of collagen-induced arthritis by inhibiting NF-κB/NLRP3 inflammasome activation.

Rheumatoid arthritis (RA) is an autoimmune disorder associated with joint damage and attendant cardiovascular complications. Wedelolactone (Wed), derived from Eclipta alba, possesses anti-inflammatory activity. Whether Wed regulates RA inflammation and related heart damage remains unknown. A murine model of collagen-induced arthritis (CIA) was well-established by two subcutaneous injections of type II collagen (days 0 and 21). Wed was then administered via intraperitoneal injection every other day from day 28 to day 48. Joint swelling was monitored and paw thickness was calculated. Histopathological changes in synovial tissues or ankle cartilage were evaluated by hematoxylin and eosin (H&E) and Safranin O-Fast Green staining. The concentrations of inflammatory factors in serum and synovial tissues were detected by ELISA. The qRT-PCR, Western blotting, immunohistochemistry (IHC), and immunofluorescence (IF) were performed to assess receptor activator of nuclear factor kappa ligand (RANKL), matrix metalloprotease (MMP)-3, NLRP3, caspase-1 (pro- and cleaved forms), p-p65, IκBα, p-IκBα, p65, αsmooth-actin 2 (ACTA2), collagen type I and E-cadherin expression. H&E and Masson staining were used to assess the pathological alterations in the heart. Treatment with Wed ameliorated ankle joint swelling and cartilage degradation. Wed decreased the infiltration of inflammatory cells, the release of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-18), and the expression of RANKL and MMP-3 in serum and synovial tissues of CIA mice. Moreover, Wed increased the expression of NLRP3 and cleaved-caspase-1 in the synovium, leading to IL-1β and IL-18 secretion. Nuclear factor-kappaB (NF-κB) activation in synovial tissues was suppressed by Wed, as manifested by reduced phosphorylation of p65 and IκBα and nuclear translocation of p65. Furthermore, Wed reduced in CIA mice heart weight/body weight ratio and dampened cardiac inflammation and fibrosis that was accompanied at the mRNA level by down-regulation of ACTA2 and collagen I and up-regulation of E-cadherin. These findings suggested that Wed attenuated synovial inflammation and joint damage in a mouse model of RA via inhibiting NF-κB/NLRP3 inflammasome activation, and ameliorated RA-induced cardiac complications.

Characteristics of Ang-(1-7)/Mas-Mediated Amelioration of Joint Inflammation and Cardiac Complications in Mice With Collagen-Induced Arthritis.

ObjectivesRheumatoid arthritis (RA) is a disabling disease with a high incidence that is regularly accompanied by cardiovascular complications. Several studies have suggested that renin–angiotensin–aldosterone system (RAAS) is closely associated with RA. The aim of this study was to investigate the mechanisms underlying Angiotensin-(1–7) [Ang-(1–7)] and its Mas receptor agonist (AVE0991) on joint inflammation and cardiac complications in a collagen-induced arthritis (CIA) model.MethodsCollagen type II was injected into DBA/1 mice to construct an arthritis model. CIA mice were treated with Ang-(1–7) (2.0 mg/kg intraperitoneally) and AVE0991 (3.0 mg/kg intraperitoneally). The serum levels of inflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1 β, IL-6, and C-reactive protein (CRP)] were determined by ELISA. The mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-κB) signaling pathways in joint tissues and the transforming growth factor (TGF)-β/Smad pathway and levels of α-Smooth muscle action (SMA) and β-myosin heavy chain (MHC) protein expression in cardiac tissues were assessed by western blots. The levels of TGF-β/Smad pathway, α-SMA, and β-MHC RNA in cardiac tissues were analyzed by real time-PCR. The levels of receptor activator of nuclear factor kappa ligand (RANKL) and promoting matrix metalloproteinase (MMP)-3 expression in the ankle joints were detected by immunohistochemistry and real time-PCR.ResultsAng-(1–7) and AVE0991 reduced the levels of inflammatory cytokines and inhibited the MAPKs and NF-κB signaling pathways in ankle joint tissues, reduced RANKL and MMP3 expression, and ameliorated local joint inflammation and bone destruction compared with the control group. In addition, Ang-(1–7) and AVE0991 attenuated the TGF-β/Smad signaling pathway, reduced the levels of α-SMA and β-MHC expression, and diminished inflammatory cell infiltration into the myocardial interstitium and myocardial interstitial fibrosis in the hearts of CIA mice.ConclusionsAng-(1–7) alleviated joint damage caused by inflammation likely through the attenuation of NF-κB and MAPK pathways and ameliorated inflammation-induced cardiac fibrosis and activation of the TGF-β/Smad pathway. Moreover, Ang-(1–7) was likely mediated through the Mas receptor. This study provides theoretical evidence for exploring novel clinical therapeutic approaches for RA and its cardiac complications.

An Overview of the Molecular Mechanisms Contributing to Musculoskeletal Disorders in Chronic Liver Disease: Osteoporosis, Sarcopenia, and Osteoporotic Sarcopenia.

The prevalence of osteoporosis and sarcopenia is significantly higher in patients with liver disease than in those without liver disease and osteoporosis and sarcopenia negatively influence morbidity and mortality in liver disease, yet these musculoskeletal disorders are frequently overlooked in clinical practice for patients with chronic liver disease. The objective of this review is to provide a comprehensive understanding of the molecular mechanisms of musculoskeletal disorders accompanying the pathogenesis of liver disease. The increased bone resorption through the receptor activator of nuclear factor kappa (RANK)-RANK ligand (RANKL)-osteoprotegerin (OPG) system and upregulation of inflammatory cytokines and decreased bone formation through increased bilirubin and sclerostin and lower insulin-like growth factor-1 are important mechanisms for osteoporosis in patients with liver disease. Sarcopenia is associated with insulin resistance and obesity in non-alcoholic fatty liver disease, whereas hyperammonemia, low amount of branched chain amino acids, and hypogonadism contributes to sarcopenia in liver cirrhosis. The bidirectional crosstalk between muscle and bone through myostatin, irisin, β-aminoisobutyric acid (BAIBA), osteocalcin, as well as the activation of the RANK and the Wnt/β-catenin pathways are associated with osteosarcopenia. The increased understandings for these musculoskeletal disorders would be contributes to the development of effective therapies targeting the pathophysiological mechanism involved.

Mg-Al and Zn-Al Layered Double Hydroxides Promote Dynamic Expression of Marker Genes in Osteogenic Differentiation by Modulating Mitogen-Activated Protein Kinases.

The effect of LDH samples comprised of chloride anions intercalated between positive layers of magnesium/aluminum (Mg-Al LDH) or zinc/aluminum (Zn-Al LDH) chemical composition on pre-osteoblast performance is investigated. Non-cytotoxic concentrations of both LDHs modulated pre-osteoblast adhesion by triggering cytoskeleton rearrangement dependent on recruiting of Cofilin, which is modulated by the inhibition of the Protein Phosphatase 2A (PP2A), culminating in osteoblast differentiation with a significant increase of osteogenic marker genes. The alkaline phosphatase (ALP) and bone sialoprotein (BSP) are significantly up-modulated by both LDHs; however, Mg-Al LDH nanomaterial promoted even more significance than both experimental controls, while the phosphorylations of mitogen-activated protein kinase (MAPKs)- extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) significantly increased. MAPK signaling is necessary to activate Runt-related transcription factor 2 (RUNX2) gene. Concomitantly, it is also investigated whether challenged osteoblasts are able to modulate osteoclastogenesis by investigating both osteoprotegerin (OPG) and Receptor activator of nuclear factor kappa-ligand (RANKL) in this model; a dynamic reprogramming of both these genes is found, suggesting LDHs in modulating osteoclastogenesis. These results suggest that LDHs interfere in bone remodeling, and they can be considered as nanomaterials in graft-based bone healing or drug-delivery materials for bone disorders.

Interleukin-6, tumor necrosis factor-alpha and receptor activator of nuclear factor kappa ligand are elevated in hypertrophic gastric mucosa of pachydermoperiostosis

Pachydermoperiostosis (PDP) is a rare inherited multisystem disease characterized with digital clubbing, pachydermia and periostosis. Variants in either HPGD or SLCO2A1 that interrupt the prostaglandin E2 (PGE2) pathway have been shown to be involved in PDP. Here, in addition to six confirmed variants in HPGD or SLCO2A1, we identified four novel SLCO2A1 variants in eight PDP patients from seven Chinese Han families. In addition, gastric mucosa hyperplasia was observed in all affected individuals and interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFα) and receptor activator of nuclear factor kappa ligand (RANKL) expression were elevated in hypertrophic gastric mucosa. Two of eight patients who had severe arthralgia were treated with celecoxib. After three months, their arthralgia was partly relieved and IL-6, TNFα and RANKL expression were decreased in accordance with their relieved hypertrophic gastric mucosa. Our study broadens the variation spectrum of SLCO2A1 and suggests that the gastric mucosa hyperplasia might be a common characteristic of PDP. Moreover, celecoxib would be a considerable choice for PDP patients. We also revealed that IL-6, TNFα and RANKL may play important roles in the molecular mechanisms of gastric mucosa hyperplasia in PDP for the first time.

Biochemical markers of bone metabolism during early orthodontic tooth movement with aligners.

To evaluate the expression of receptor activator of nuclear factor-kappa ligand (RANKL), osteoprotegerin (OPG), osteopontin (OPN), interleukin 1β (IL-1β), and transforming growth factor ß1 (TGF-ß1) in the gingival crevicular fluid (GCF) of teeth subjected to orthodontic forces released by aligners. A total of 10 healthy, adult patients were selected to participate in this split-mouth study. The treatment plan was designed to obtain only one movement with the first aligner: distalization of a second molar. GCF samples were obtained from pressure and tension sites of the test tooth and from the mesiobuccal and distobuccal sites of the control tooth. The GCF sample volumes were measured using a Periotron 8000. Levels of TGF-β, IL-1β, RANKL, OPG, and OPN were measured by enzyme-linked immunosorbent assay. IL-1β showed a significant increase at the pressure sites after 1 week and 3 weeks with respect to baseline (P < .05) compared with control sites. The kinetics of TGF-1β and OPN were characterized by a significant increase at the tension sites of the test teeth (P < .05) after 3 weeks from the application of orthodontic force. The RANKL level was significantly increased at pressure and tension sites after 1 hour and after 1 week from the application of the orthodontic forces (P = .023 and P = .043, respectively). An increased concentration of bone modeling and remodeling mediators at the pressure sites (IL-1β, RANKL) and tension sites (TGF-1β, OPN) was observed. These scenarios are compatible with previous in vivo and in vitro studies investigating the biological effects of orthodontic tooth movement.

Induction of IL-6 and MMP-8 in human periodontal fibroblasts by static tensile strain

Mechanical loading is a potential activator of inflammation and able to stimulate factors for periodontal and alveolar bone destruction. Aim of this study was to investigate the inflammatory response and synthesis of proteinases by human periodontal ligament fibroblast (HPdLF) dependent on different strengths of static tensile strain (STS). HPdLFs were loaded with different STS strengths (1, 5, and 10 %) in vitro. Gene expressions of cyclooxygenase (COX)-2 and interleukin (IL)-6 were analyzed by quantitative real-time polymerase chain reaction. Production of IL-6, prostaglandin E2 (PGE2), matrix metalloproteinase (MMP)-8, and tissue inhibitors of matrix metalloproteinase (TIMP)-1 were measured by enzyme-linked immunosorbent assay. Receptor activator of nuclear factor-kappa ligand (RANKL) synthesis was detected by immunocytochemical staining. Ten percent STS led to an increased gene expression of IL-6 and COX-2 (34.4-fold) in HPdLF, and 1 and 5 % STS slightly reduced the gene expression of IL-6. Synthesis of IL-6 was significantly reduced by 1 % STS and stimulated by 10 % STS. Ten percent STS significantly induced PGE2 production. RANKL was not detectable at any strength of STS. MMP-8 synthesis showed significantly higher values only at 10 % STS, but TIMP-1 was stimulated by 5 and 10 % STS, resulting into highest TIMP-1/MMP-8 ratio at 5 % STS. High-strength STS is a potent inducer of periodontal inflammation and MMP-8, whereas low-strength STS shows an anti-inflammatory effect. Moderate-strength STS causes the highest TIMP-1/MMP-8 ratio, leading to appropriate conditions for reformation of the extracellular matrix. Furthermore, this study points out that the strength of force plays a pivotal role to achieve orthodontic tooth movement without inducing periodontal inflammation and to activate extracellular matrix regeneration.

Coronary artery calcification and cardiovascular risk: the role of RANKL/OPG signalling

Coronary artery disease (CAD) represents the most relevant cause of death and morbidity in the adult population of developed and developing countries. During the last decades, a strong research effort has been performed to identify more selective markers and better assess the cardiovascular risk in both primary and secondary prevention. This review updates current knowledge regarding the pathophysiological relevance as possible markers of coronary calcification of the receptor activator of nuclear factor-kappa ligand (RANKL)/osteoprotegerin (OPG) system. Furthermore, the potential clinical use of both RANKL/OPG and coronary calcium score (CAC) to assess cardiovascular vulnerability has been discussed. Emerging evidence indicates that atherosclerotic plaque calcification is positively correlated with vulnerability. Several inflammatory mediators have been shown to modulate arterial calcification, thus increasing the risk of plaque rupture. Among these factors, RANKL/OPG axis might be of particular interest as a promising biomarker of plaque vulnerability in subjects with diffuse coronary calcification. Together with clinical parameters of coronary calcification (such as CAC), circulating RANKL/OPG levels could contribute to better assess and predict cardiac events.

RANK/RANKL/OPG during orthodontic tooth movement

Orthodontic tooth movement is induced by mechanical stimuli and facilitated by remodeling of the periodontal ligament (PDL) and alveolar bone. A precondition for these remodeling activities, and ultimately for tooth displacement, is the occurrence of an inflammatory process. This review covers current knowledge regarding the role of the receptor activator of nuclear factor-kappa (RANK), receptor activator of nuclear factor-kappa ligand (RANKL), and osteoprotegerin (OPG) in periodontal tissue reactions, in response to orthodontic forces. It has been found that concentrations of RANKL in GCF increased during orthodontic tooth movement, and the ratio of concentration of RANKL to that of OPG in the GCF was significantly higher than in control sites. In vivo studies have shown the presence of RANKL and RANK in periodontal tissues during experimental tooth movement of rat molars, and that PDL cells under mechanical stress may induce osteoclastogenesis through upregulation of RANKL expression during orthodontic tooth movement. Considering the importance of RANK, RANKL, and OPG in physiologic osteoclast formation, it is reasonable to propose that the RANKL/RANK/OPG system plays an important role in orthodontic tooth movement.

Wear‐particle–induced osteoclast osteolysis: The role of particulates and mechanical strain

Periprosthetic osteolysis involves osteoclast activation by wear particulates and their exposure to mechanical perturbation through exposure to shear forces generated by periprosthetic fluid as well as interface micromotion. This study aimed to determine the interactions between wear particulates, mechanical stimulation, and osteoclasts. In static cultures, wear particulates increased osteoclast differentiation. Addition of neutralizing antibodies to RANKL (receptor activator of nuclear factor kappa ligand) inhibited the particle-induced increase in osteoclast numbers. Cyclic 5000 microstrains were applied with the use of a custom-built device to marrow-derived cultures to assess the effect on osteoclast differentiation. Mechanical strain application alone decreased osteoclast differentiation, which was further decreased by the addition of particles despite increases in the soluble RANKL to osteoprotegerin (OPG) ratio. Mechanical strain alone induced mature osteoclast apoptosis in a dose-dependent manner. In contrast, in the mature osteoclast model, the addition of nonmetal particulates protected the osteoclasts from becoming apoptopic. Titanium (Ti) and cobalt chromium (CoCr) particles, however, induced osteoclast apoptosis, whereas polyethylene (PE) and polymethylmethacrylate (PMMA) did not. Wear particulates and mechanical stimulation interact via an eicosanoid-dependent pathway to alter osteoclast function and survival. The addition of mechanical perturbation to a particle-laden system thus appears to enhance the potential for osteolytic activity by enhancing osteoclast survival.

Transforming growth factor-beta in osteolytic breast cancer bone metastases.

Breast cancers frequently metastasize to the skeleton and cause bone destruction. Tumor cells secrete factors that stimulate osteoclasts. The consequent osteolytic resorption releases active factors from the bone matrix, in particular transforming growth factor-beta (TGF-beta). The released factors then stimulate tumor cell signaling, which causes breast cancer cells to make increased amounts of osteolytic factors, such as parathyroid hormone-related protein (PTHrP), interleukin-11 (IL-11), and vascular endothelial growth factor (VEGF). Therefore, tumor cell-bone cell interactions cause a vicious cycle in which tumor cells stimulate bone cells to cause bone destruction. As a consequence, the local microenvironment is enriched with factors that fuel tumor growth in bone. Transforming growth factor-beta is of particular importance because it increases breast cancer production of PTHrP. Parathyroid hormone-related protein then stimulates osteoblasts to express RANK (receptor activator of nuclear factor kappa B) ligand, which in turns enhances osteoclast formation and activity. Breast cancer osteolytic metastasis can be interrupted at four points in the vicious cycle: by neutralizing PTHrP biologic activity, by blocking the TGF-beta signaling pathway in the tumor cells, by inhibiting PTHrP gene transcription, and by inhibiting bone resorption.

RANK (receptor activator of nuclear factor kappa B) and RANK ligand are expressed in giant cell tumors of bone.

In giant cell tumors of bone (GCTBs), the mesenchymal stromal cells are the neoplastic cells and induce recruitment and formation of osteoclasts (OCs). Studies on recently discovered members of the tumor necrosis factor receptor-ligand family have demonstrated a crucial role of RANKL (receptor activator of nuclear factor kappa B [RANK] ligand) expressed by osteoblast/stromal cells and of its receptor RANK expressed by OCs during OC differentiation and activation. OCs typically are present in large numbers in GCTBs, suggesting that these tumors may contain cells expressing factors that stimulate OC precursor recruitment and differentiation. We used immunohistochemical analysis to study RANKL and RANK expression in 5 GCTBs. Multinucleated cells and some mononuclear cells showed strong positive staining with anti-RANK antibodies; RANKL was present in a subset of mononuclear cells that did not express the hematopoietic lineage cell marker CD45, a feature that identified them as mesenchymal tumor cells. Our results suggest that RANKL expression may have a role in the pathogenesis of GCTBs and in the formation of the large OC population present in these tumors.