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BACKGROUND: MiR-338-3p could inhibit osteoclast differentiation, and downregulation of receptor activator of nuclear factor-κB ligand level could promote bone formation. However, it is unclear whether miR-338-3p can affect the proliferation and apoptosis of alveolar bone osteoblasts by regulating the receptor activator of nuclear factor-κB ligand level. OBJECTIVE: To explore the effect and mechanism of miR-338-3p on proliferation and apoptosis of alveolar bone osteoblasts by targeting receptor activator of nuclear factor-κB ligand. METHODS: Human alveolar bone osteoblasts were isolated, transfected and treated with Wnt-C59 (Wnt/β-catenin pathway inhibitor), and divided into transfection control group, miR-338-3p group, miR-338-3p+control group, miR-338-3p+receptor activator of nuclear factor-κB ligand group and miR-338-3p+ Wnt-C59 group. The dual luciferase report experiment was used to verify the regulatory effect of miR-338-3p on receptor activator of nuclear factor-κB ligand. Cell counting kit-8 and 5-Ethynyl-2’-deoxyuridine staining were used to detect cell proliferation levels. Flow cytometry was used to detect cell cycle and apoptosis levels. RT-qPCR was used to detect miR-338-3p, receptor activator of nuclear factor-κB ligand, Wnt-3a, β-Catenin, glycogen synthase kinase-3β mRNA levels. Western blot was used to detect RANKL, proliferating cell nuclear antigen, Ki67, CyclinD1, B-cell lymphoma/leukemia-2, B-cell lymphoma-2 related X protein, Caspase3, Wnt-3a, β-catenin, glycogen synthase kinase-3β protein levels. RESULTS AND CONCLUSION: miR-338-3p could target the regulation of receptor activator of nuclear factor-κB ligand. After overexpression of miR-338-3p, cell survival rate, 5-Ethynyl-2’-deoxyuridine positive cell rate, proportion of S-phase cells were increased, and apoptosis rate was decreased. The mRNA and protein levels of miR-338-3p, proliferating cell nuclear antigen, Ki67, CyclinD1, B-cell lymphoma/leukemia-2, Wnt-3a, and β-catenin were increased, while the mRNA and protein levels of B-cell lymphoma-2 related X protein, Caspase3 protein, receptor activator of nuclear factor-κB ligand, and glycogen synthase kinase-3β were decreased (all P < 0.05). Overexpression of receptor activator of nuclear factor-κB ligand or Wnt-C59 could weaken the effects of overexpression of miR- 338-3p on cell proliferation and apoptosis (all P < 0.05). Overall, miR-338-3p promotes alveolar bone osteoblast proliferation and inhibits apoptosis by targeting receptor activator of nuclear factor-κB ligand, which may act through activation of the Wnt/β-catenin signaling pathway. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Modern Laboratory Medicine is the property of Journal of Modern Laboratory Medicine Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Although aromatase inhibitors significantly improve the clinical benefit of patients with hormone receptor-positive breast cancer, its associated adverse event - osteoporosis seriously affects the quality of life of patients. Huangqi Bushen Huoxue Decoction can effectively prevent the occurrence of aromatase inhibitor-induced osteoporosis, but its mechanism of action is unclear. OBJECTIVE: To investigate the effects of Huangqi Bushen Huoxue Decoction on osteoclast activity in a mouse model of osteoporosis induced by aromatase inhibitors and relevant mechanisms. METHODS: Sixty 8-week-old female C57BL/6J mice were randomly divided into sham operation group, model group, high-, medium- and low-dose Huangqi Bushen Huoxue Decoction, and positive control group, with 10 mice in each group. Bilateral ovaries were removed to establish postmenopausal animal models in all the groups except for the sham operation group. After 1 week of recovery, letrozole was injected subcutaneously to establish postmenopausal osteoporosis models via subcutaneous injection of letrozole (an aromatase inhibitor). The high-, medium- and low-dose Huangqi Bushen Huoxue Decoction groups were intragastrically given 19.24, 9.62 and 4.81 g/kg/d Huangqi Bushen Huoxue Decoction (once a day), respectively. The positive control group was given alendronate 5mg/kg once a week. After 3 months of administration, Micro-CT was used to detect tibial bone mineral density and bone microstructure. Hematoxylin-eosin staining and tartrate-resistant acid phosphatase staining of the femur were performed. Immunohistochemistry was used to detect the protein expression of receptor activator of nuclear factor-κB ligand and osteoprotectin in the femur. ELISA was used to detect the serum levels of carboxyterminal cross-linked telopeptides of type I collagen and tartrate-resistant acid phosphatase 5b. RESULTS AND CONCLUSION: (1) Compared with the sham operation group, the model group showed a significant decrease in bone mineral density, sparse and fractured trabecular morphology, and a significant increase in serum levels of carboxyterminal cross-linked telopeptides of type I collagen and tartrateresistant acid phosphatase 5b, indicating that the model of aromatase inhibitor-induced osteoporosis was successfully constructed. (2) Compared with the model group, the high-, medium-, and low-dose Huangqi Bushen Huoxue Decoction groups showed significant improvement in bone mineral density and bone microstructure, thickening and densification of trabecular morphology, significantly decreased serum levels of carboxyterminal cross-linked telopeptides of type I collagen and tartrate-resistant acid phosphatase 5b, a decrease in the number of osteoclasts and the expression of receptor activator of nuclear factorκB ligand proteins, and an increase in the expression of osteoprotegerin. To conclude, Huangqi Bushen Huoxue Decoction may regulate the receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factor-κB/osteoprotegerin signaling pathway, inhibit osteoclast activity, improve trabecular morphology and bone microstructure, and increase bone mineral density, thus preventing the occurrence and development of aromatase inhibitor-induced osteoporosis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Osteoprotegerin (OPG)/receptor activator of nuclear factor-κB (RANK)/receptor activator of nuclear factor-κB ligand (RANKL) are important cytokines for coupling osteoclast and osteoblast differentiation and activation, and are key factors for regulating bone metabolism, which affect the immune system, bone regeneration and remodeling, and are closely related to the physiological and pathological remodeling of the alveolar bone. OBJECTIVE: To analyze the effects of the OPG/RANK/RANKL signaling pathway on alveolar bone remodeling and the progress in its targeted therapy application in the dental field. METHODS: We searched relevant articles included in CNKI and PubMed databases with the keywords of “OPG, anti-RANKL antibody, RANKL, periodontitis, orthodontic tooth movement, implant, tooth eruption, periapical lesion, alveolar bone resorption” in Chinese and English, respectively. A total of 63 articles were finally included for review. RESULTS AND CONCLUSION: Anti-RANKL therapy can treat oral diseases by targeting the inhibition of osteoclast formation and alveolar bone absorption. Local and systemic anti-RANKL therapy can inhibit the progression of periodontitis, peri-implantitis and periapical lesions, and it also plays an important role in preventing orthodontic relapse, strengthening orthodontic anchorage and implant osseointegration. RANKL therapy can treat oral diseases by promoting osteoclast differentiation and alveolar bone absorption. RANKL treatment can accelerate orthodontic tooth movement, shorten the treatment cycle and reduce the incidence of orthodontic complications. Although there are limitations in anti-RANKL therapy, they can be avoided by rational applications, such as excluding local and systemic risk factors before treatment, regular oral maintenance and avoiding traumatic alveolar surgery as much as possible during treatment. [ABSTRACT FROM AUTHOR]

ABSTRACT: Introduction: Vitamin D's precise role in bone mineral density regulation remains elusive. Nevertheless, its deficiency is linked to increased bone turnover through the upregulation of RANK ligands by osteoblasts. This study aimed to (i) evaluate vitamin D status in young adults and (ii) assess the association between vitamin D deficiency and bone turnover markers receptor activator of nuclear factor-κB ligand (RANKL), RANK, and the osteoprotegerin (OPG) in determining bone mineral density. Materials and Methods: This cross-sectional study involved 474 participants from the East Khasi Hills district, Meghalaya. Vitamin D levels were measured using the UniCel DxI 800 system, while OPG, RANK, and RANKL were assessed through enzyme-linked immunosorbent assay (ELISA). Additionally, a whole-body dual X-ray absorptiometry (DEXA) scan determined bone mineral density. Vitamin D deficiency was categorised as <20 ng/ml, insufficiency as 20–29 ng/ml, and sufficiency as ≥30 ng/ml. Results: Findings indicated 54.6% vitamin D deficiency and 35.4% insufficiency in young adults. Osteoporosis affected 26%, and 67% exhibited osteopenia. A weak positive correlation was found between vitamin 25(OH) D and bone mineral density T score (r = 0.16, r2 = 0.02, P = 0.44). Additionally, moderately weak correlations were observed between serum vitamin D and OPG (r = –0.42, r2 = 0.18, P < 0.001) and between vitamin D and RANKL (r = –0.13, r2 = 0.01, P = 0.18). Conclusion: The study suggests that vitamin D deficiency diminishes bone mineral density by promoting RANKL-RANK osteoclastogenesis and upregulating OPG expression. As young adults form a significant workforce, creating awareness is crucial for maintaining optimal health. [ABSTRACT FROM AUTHOR]

Lipopolysaccharide (LPS) and Receptor Activator of Nuclear Factor-κB Ligand (RANKL) are the two important factors causing bone loss, which is an important pathogenesis for osteoporosis. However, the relationship between LPS and RANKL is not yet clear. LPS can be involved in the weakened osteoblast formation as an autophagy regulator, and osteoblasts and their precursors are the source cells for RANKL production. Our study aimed to explore the relationship between autophagy changes and RANKL production during LPS-regulated osteoblasts. Our results showed that LPS inhibited autophagy (LC3 conversion and autophagosome formation) and enhanced the protein and mRNA expression of RANKL in MC3T3-E1 osteoblast precursor line. Autophagy upregulation with Rapamycin over BECN1 overexpression rescued LPS-inhibited osteoblast formation and -promoted RANKL protein production in MC3T3-E1 cells. In vivo experiments supported that damaged bone mass, bone microstructure, osteoblastic activity (ALP and P1NP production by ELISA assays) and enhanced RANKL production by LPS administration were partially rescued by Rapamycin application. In conclusion, LPS can inhibit autophagy in osteoblast precursors, thereby inhibiting osteoblast formation and RANKL autophagic degradation.

We have previously demonstrated that auxiliary metformin therapy promotes healing of apical periodontitis. Here we aimed to investigate the effects of metformin on osteoblast differentiation and osteoclast formation in cultured cells and rat apical periodontitis. Murine pre-osteoblasts MC3T3-E1 and macrophages RAW264.7 were cultured under hypoxia (2% oxygen) or normoxia (21% oxygen) and stimulated with receptor activator of nuclear factor-κB ligand (RANKL) when indicated. Metformin was added to the cultures to evaluate its anti-hypoxic effects. Expressions of osteoblast differentiation regulator runt-related transcription factor 2 (RUNX2), RANKL, and osteoclast marker tartrate-resistant acid phosphatase (TRAP) were assessed by Western blot. Apical periodontitis was induced in mandibular first molars of 10 Sprague-Dawley rats. Root canal therapy with or without metformin supplement was performed. Periapical bone resorption was measured by micro-computed tomography. Immunohistochemistry was used to examine RUNX2, RANKL, and TRAP expressions. Hypoxia suppressed RUNX2 expression and enhanced RANKL synthesis in pre-osteoblasts. TRAP production increased in macrophages after hypoxia and/or RANKL stimulation. Metformin reversed hypoxia-induced RUNX2 suppression and RANKL synthesis in pre-osteoblasts. Metformin also inhibited hypoxia and RANKL-enhanced TRAP synthesis in macrophages. Intracanal metformin diminished bone loss in rat apical periodontitis. Comparing with vehicle control, cells lining bone surfaces in metformin-treated lesions had significantly stronger expression of RUNX2 and decreased synthesis of RANKL and TRAP. Alleviation of bone resorption by intracanal metformin was associated with enhanced osteoblast differentiation and diminished osteoclast formation in rat apical periodontitis. Our results endorsed the role of metformin as an effective medicament for inflammatory bone diseases. [ABSTRACT FROM AUTHOR]

Postmenopausal osteoporosis is a critical issue for female health worldwide. This current study was designed to evaluate the role of nanopowder eggshell (NPES) in healthy and ovariectomy-induced osteoporosis rats. Fifty-six female rats were divided into healthy rats (35) and ovariectomized rats (21). The healthy rats were subdivided into five groups (G1–G5) and received one of the following treatments: saline, 20 or 40 mg/kg of calcium carbonate, and 20 or 40 mg/kg of NPES. The 21 ovariectomized rats were divided into three groups (G6–G8) and received either saline, 40 mg/kg of calcium carbonate, or 40 mg/kg of NPES. Biochemical and histopathological assessments of bone formation and resorption were performed. Biomarkers of bone formation (calcium and osteocalcin (OCN)) and calcium content in left femur ashes were significantly higher in healthy rats given 40-mg/kg NPES than in healthy control rats and healthy rats given 40-mg/kg calcium carbonate. The ovariectomized groups had significantly lower levels of vitamin D3, OCN, and osteoprotegerin (OPG) than the healthy control. Alanine transaminase (ALT), alkaline phosphatase (ALP), and receptor activator of nuclear factor-κB ligand (RANKL) were significantly increased in the ovariectomized group than in the healthy control group. Treatment with NPES and calcium carbonate reduced liver enzymes in ovariectomized rats. NPES treatment significantly increased Vit D3, OCN, OPG, and bone ash mineral content (calcium, magnesium, zinc, and phosphorus) in ovariectomized rats. NPES also increased femur cortical thickness, osteoblast number, and collagen fiber. The current study suggests that NPES can modulate bone turnover biomarkers and increase bone trace elements. Moreover, NPES alleviates bone resorption in ovariectomy-induced osteoporosis. [ABSTRACT FROM AUTHOR]

Introduction: Multiple myeloma (MM) is a malignancy of plasma cells with characteristic bone disease. Despite recent great strides achieved in MM treatment owing to the implementation of new anti-MM agents, MM is still incurable and bone destruction remains a serious unmet issue in patients with MM. Approach: In this review, we will summarize and discuss the mechanisms of the formation of bone disease in MM and the available preclinical and clinical evidence on the treatment for MM bone disease. Conclusions: MM cells produce a variety of cytokines to stimulate receptor activator of nuclear factor-κB ligand-mediated osteoclastogenesis and suppress osteoblastic differentiation from bone marrow stromal cells, leading to extensive bone destruction with rapid loss of bone. MM cells alter the microenvironment through bone destruction where they colonize, which in turn favors tumor growth and survival, thereby forming a vicious cycle between tumor progression and bone destruction. Denosumab or zoledronic acid is currently recommended to be administered at the start of treatment in newly diagnosed patients with MM with bone disease. Proteasome inhibitors and the anti-CD38 monoclonal antibody daratumumab have been demonstrated to exert bone-modifying activity in responders. Besides their anti-tumor activity, the effects of new anti-MM agents on bone metabolism should be more precisely analyzed in patients with MM. Because prognosis in patients with MM has been significantly improved owing to the implementation of new agents, the therapeutic impact of bone-modifying agents should be re-estimated in the era of these new agents. [ABSTRACT FROM AUTHOR]

Abstract Indroduction SLE is an autoimmune multisystem disease. Glucocorticoid is an irreplaceable medication for SLE. Glucocorticoid and inflammatory mediators impact bone remodeling by OPG/RANKL/RANK signal system, which could lead to osteoporosis. Our aim is to detect the expression of RANKL/OPG in children with SLE, and to preliminarily explore the changes of bone remodeling serum markers in children with SLE. Methods Serum RANKL and OPG of 40 children with SLE and healthy children were detected by ELISA, while 25(OH)VitD3 was detected routinely. Clinical data of children with SLE were recorded, including gender, age, height, weight, BMI, SLEDAI, duration of the disease, cumulative dose of glucocorticoid, and correlation analysis was conducted with RANKL, OPG and 25(OH)VitD3. Results Serum RANKL concentrations in SLE group were significantly higher than health group (9.82 ± 7.20 vs. 6.80 ± 4.35 pg/ml and 0.081 ± 0.072 vs. 0.042 ± 0.034, P

Objective: To observe the effects of peptidylarginine deiminase 2 (PAD2) inhibitor AFM-30a on silicotic mice and its possible mechanisms. Methods: In May 2022, 40 SPF male C57BL/6J mice were randomly divided into control group, AFM-30a group, silicosis model group and AFM-30a treatment group, with 10 mice in each group. Silicosis model group and AFM-30a treatment group were perfused with silicon dioxide (SiO(2)) suspension (10 mg/piece, 50 μl), and the other groups were perfused with an equal amount of sodium chloride solution. After 2 weeks, AFM-30a group and AFM-30a treatment group were intraperitoneally injected AFM-30a (20 mg/kg, 100 μl) daily, and mice of other groups were injected with equal amounts of sodium chloride solution for 4 weeks. Mouse RAW264.7 monocytes/macrophages were cultured in vitro and divided into blank control group, AFM-30a group (5 μmol/L), SiO(2) group (200 μg/ml), and SiO(2)+AFM-30a group (200 μg/ml SiO(2) induction for 12 h, followed by 5 μmol/L AFM-30a treatment for 12 h). As well as blank control group, vimentin (Vim) group (2 μg/ml), citrullinated vimentin (Cit-Vim) group (2 μg/ml), and Cit-Vim+TLR4-C34 group (10 μmol/L TLR4-C34 treatment for 1 h, followed by 2 μg/ml Cit-Vim induction for 24 h). Hematoxylin Eosin (HE) and Masson staining were used to observe the pathological morphology of lung. The lung fieldclarity and lung texture of each group was observed by micro-CT. The number of positive cells was detected by tartrate resistant acid phosphatase (TRAP) staining. The localization and expression levels of PAD2, Cit-Vim, toll-like receptor 4 (TLR4) signaling and receptor activator of nuclear factor-κB ligand (RANKL) signaling proteins were measured by Immunofluorescence staining and Western blotting in vitro and in vivo. The experimental data were all presented as Mean±SD. A completely random design of one-way analysis of variance was used among the groups. The pduo comparison was performed using LSD test for homogeneity of variance and Tamhane's test for inconsistency. Results: Compared with the control group, the silicosis model group showed the formation of silicon nodules accompanied by collagen deposition, the silicosis model group showed thickened, and several high-density shadows of varying sizes in the lung field, and the number of TRAP positive cells in silicosis model group were increased significantly, the expression levels of PAD2, Cit-Vim, TLR4 and RANKL signal-related proteins were also significantly increased in silicosis groupmodel ( P <0.05). Compared with the silicosis model group, the AFM-30a treatment group reduced deposition of collagen in lung, and the number of TRAP positive cells was decreased in AFM-30a treatment group. The expression levels of PAD2, Cit-Vim, TLR4 and RANKL signaling related proteins were significantly decreased in AFM-30a treatment group ( P <0.05). In vitro, compared with the blank control group, the number of TRAP positive cells and the expression levels of PAD2, Cit-Vim, TLR4 and RANKL signaling related proteins in the SiO(2) group were significantly increased ( P <0.05). Compared with the SiO(2) group, the number of TRAP positive cells and the expression levels of PAD2, Cit-Vim, TLR4 and RANKL signaling related proteins in the SiO(2)+AFM-30a group were significantly decreased ( P <0.05). Compared with the blank control group, the expression levels of TLR4 and RANKL signaling related proteins in the Cit-Vim group were significantly increased ( P <0.05). Compared with the Cit-Vim group, the expression levels of TLR4 and RANKL signaling related proteins in the Cit-Vim+TLR4-C34 group were significantly decreased ( P <0.05) . Conclusion: PAD2 inhibitor AFM-30a may play an antagonisticrole in silicotic fibrosis in mice by potentialregulating TLR4 and RANKL signaling pathways.

Objective The expression of osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) in human periodontal ligament cells (HPDLCs) was investigated by cell culture under continuous static pressure. Methods HPDLCs were primarily cultured by tissue explant method and divided into three groups: group A (13-18 years old), group B (19-29 years old), and group C (30-44 years old). CCK-8 was used to detect the proliferation of HPDLCs. The senescence of HPDLCs was detected by senescence-associated β-galactosidase staining. Cells in the three groups were respectively given 0, 1.5, 3, 6, 12, 24, 48, and 72 h of continuous static pressure in vitro. The expression of OPG and RANKL in the supernatant was detected by enzyme-linked immunosorbent assay. Results After continuous static pressure in vitro for stimulation, the expression of OPG and RANKL changed. The expression of OPG increased with time and age (P<0.01). The expression of RANKL increased with time and decreased with age (P<0.01). The ratio of OPG/RANKL initially decreased, increased with time, and then continued to rise with age (P<0.01). Conclusion Aging could increase the expression of OPG and the ratio of OPG/RANKL and decrease the expression of RANKL in HPDLCs under continuous static pressure in vitro. [ABSTRACT FROM AUTHOR]

BACKGROUND: Interleukin-1 is an important pro-inflammatory cytokine that has been documented in the regulation of bone inflammation and bone remodeling. A previous study has demonstrated that interleukin-1α can induce apoptosis while inhibiting osteoblast differentiation in MC3T3-E1 cells. OBJECTIVE: To investigate the role and mechanism of interleukin-1α on osteoclast activation and bone loss in mice. METHODS: (1) Cell test: RAW264.7 cells were either treated with interleukin-1α alone or with receptor activator of nuclear factor-κB ligand (RANKL) for 1 and 4 days. Cell viability was tested by cell counting kit-8 assay. The number of multinuclear osteoclasts was detected by tartrate resistant acid phosphatase assay. The mRNA and protein levels of osteoclast-specific genes and genes related to nuclear factor-κB pathway and Wnt/β-catenin pathway were tested by real-time fluorescence quantitative PCR, immunofluorescence staining or western blot. Bone marrow-derived macrophages were either treated with interleukin-1α alone or with RANKL and macrophage colony-stimulating factor for 7 days. The number of multinuclear osteoclasts was detected by tartrate resistant acid phosphatase assay. The protein levels of osteoclast-specific genes were tested by western blot. (2) Animal test: Twenty-four male C57BL/6J mice (6-8 weeks old) were assigned into two groups at random: control group and test group. Mice were subsequently treated with interleukin-1α solution or PBS by intraperitoneal injection twice a week for 5 weeks. Bone tissues from the femurs were performed with micro-computed tomography analysis and hematoxylin-eosin staining, tartrate resistant acid phosphatase, and immunofluorescence analysis. RESULTS AND CONCLUSION: Cell test: Interleukin-1α alone significantly increased RAW264.7 cell proliferation, but stimulated cell differentiation into osteoclasts in combination with RANKL (P < 0.05). Interleukin-1α significantly increased the expression of osteoclast-related markers and the number of tartrate resistant acid phosphatasepositive multinuclear cells in RAW264.7 cells and bone marrow-derived macrophages in the existence of RANKL or RANKL+macrophage colony-stimulating factor (both P < 0.05). Interleukin-1α was found to significantly enhance the nuclear factor-κB and Wnt/beta-catenin signaling in RAW264.7 cells (P < 0.05). Blocking of nuclear factor-κB or Wnt3 signaling not only reversed the activation of nuclear factor-κB and Wnt3 signaling but also weakened the enhanced expression of osteoclast-specific genes induced by interleukin-1α in RAW264.7 cells (P < 0.05). Animal test: interleukin1α induced bone loss in mice while also upregulating the expression of osteoclast-specific markers, RANK, TRAF6 and p65, and Wnt3 in vivo (P < 0.05). The findings indicate that interleukin-1α can induce osteoclast activation and bone loss by promoting the nuclear factor-κB and Wnt signaling pathways. [ABSTRACT FROM AUTHOR]

Indroduction: SLE is an autoimmune multisystem disease. Glucocorticoid is an irreplaceable medication for SLE. Glucocorticoid and inflammatory mediators impact bone remodeling by OPG/RANKL/RANK signal system, which could lead to osteoporosis. Our aim is to detect the expression of RANKL/OPG in children with SLE, and to preliminarily explore the changes of bone remodeling serum markers in children with SLE. Methods: Serum RANKL and OPG of 40 children with SLE and healthy children were detected by ELISA, while 25(OH)VitD3 was detected routinely. Clinical data of children with SLE were recorded, including gender, age, height, weight, BMI, SLEDAI, duration of the disease, cumulative dose of glucocorticoid, and correlation analysis was conducted with RANKL, OPG and 25(OH)VitD3. Results: Serum RANKL concentrations in SLE group were significantly higher than health group (9.82 ± 7.20 vs. 6.80 ± 4.35 pg/ml and 0.081 ± 0.072 vs. 0.042 ± 0.034, P < 0.05) respectively, and the concentrations of OPG and 25(OH)VitD3 in serum were significantly lower than health group (156.34 ± 57.33 vs. 189.16 ± 68.70 pg/ml and 43.66 ± 31.27 vs. 59.04 ± 21.56 mmol/L, P < 0.05). Serum RANKL in children with SLE was positively correlated with the duration of SLE, cumulative dose of GC(r = 0.593, 0.727, P < 0.05). And it was negatively correlated with serum OPG and 25(OH)VitD3 (r = -0.601, -0.469, P < 0.05). In addition, serum OPG and 25(OH)VitD3 concentrations were inversely correlated with cumulative dose of GC (r = -0.66, -0.508, P < 0.05). Conclusion: Low levels of vitamin D3 and bone metabolic abnormalities still persist in children with SLE even if the disease is in remission, while serum RANKL level was elevated, OPG expression was reduced. In the case of disease remission, GC is involved in the occurrence and development of abnormal bone remodeling through RANKL/OPG. [ABSTRACT FROM AUTHOR]

BACKGROUND: Previous studies have confirmed that lipopolysaccharide could up-regulated the expression of interleukin-6, an inflammation-related cytokine, in mouse MLO-Y4 osteocytes, and interleukin-6 could further up-regulate the expression of receptor activator of nuclear factor κB ligand (RANKL), a factor related to osteoclastogenesis, in osteoblasts. PI3K/AKT signaling pathway is an important regulatory pathway in bone metabolism. Verifying whether this signaling pathway is involved in the production of inflammatory factors induced by lipopolysaccharides is greatly beneficial to studying the mechanism of bone resorption that is caused by bacterial inflammation. OBJECTIVE: To verify whether PI3K/AKT signaling pathway is involved in the expression of interleukin-6 and RANKL in mouse MLO-Y4 osteocytes stimulated by lipopolysaccharides. METHODS: MLO-Y4 osteoblasts were stimulated with 0 or 100 µg/L lipopolysaccharides for 1, 2, 4, 6, and 8 hours. Then the mRNA expressions of interleukin-6 and RANKL were detected by real-time quantitative polymerase chain reaction, and the protein expression of RANKL and p-AKT were detected by western blot. MLO-Y4 osteocytes in logarithmic growth was divided into seven groups: no treatment group (control group), 100 µg/L lipopolysaccharide group, 1 µmol/L PI3K inhibitor+100 µg/L lipopolysaccharide group, 2.5 µmol/L PI3K inhibitor+100 µg/L lipopolysaccharide group, 5 µmol/L PI3K inhibitor+100 µg/L lipopolysaccharide group, 10 µmol/L PI3K inhibitor+100 µg/L lipopolysaccharide group, 20 µmol/L PI3K inhibitor+100 µg/L lipopolysaccharide group. Real-time quantitative polymerase chain reaction was used to detect the mRNA expression of interleukin 6 and RANKL. MLO-Y4 osteocytes were divided into four groups: no treatment group (control group), 100 µg/L lipopolysaccharide group, dimethyl sulfoxide+100 µg/L lipopolysaccharide group, and 10 µmol/L PI3K inhibitor+100 µg/L lipopolysaccharide group. Real-time quantitative polymerase chain reaction was used to detect the mRNA expression of RANKL, and western blot was used to detect the protein expression of RANKL and p-AKT. RESULTS AND CONCLUSION: After lipopolysaccharide stimulation, the mRNA expression of interleukin-6 and RANKL in osteocytes was increased first and then decreased; however, the mRNA expression levels were higher than those in the control group at each time point (P < 0.05). After lipopolysaccharide stimulation, the protein expression of RANKL and p-AKT in osteocytes was significantly higher than that in the control group (P < 0.05) at each time point, although the protein expression in lipopolysaccharide groups was increased first and then decreased. PI3K inhibitor of 1-10 µmol/L could decrease the mRNA expression of interleukin 6 and RANKL in lipopolysaccharide-induced osteocytes in a concentration-dependent manner, while 20 and 10 µmol/L PI3K inhibitor showed similar effects. Both dimethyl sulfoxide and PI3K inhibitors could inhibit the increase in the protein and mRNA expression of RANKL and the protein expression of p-AKT in osteocytes induced by lipopolysaccharide. Furthermore, PI3K inhibitor showed the better inhibitory effect. These results indicate that lipopolysaccharide stimulates the expression of interleukin-6 and RANKL in mouse MLO-Y4 osteocytes through the PI3K/AKT signaling pathway. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China Medical University is the property of Journal of China Medical University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective To investigate the effect of gentiopicroside (GENT) on bone resorption in osteoporosis (OP) rats based on mitogen-activated protein kinase (MAPK) signaling pathway. Methods Seventy-eight female SD rats were randomly divided into sham operation group (Sham group), model group (OP group), estradiol group (E2 group, 0.05 mg·kg-1), gentiopicroside low- (GENT LD, 30 mg·kg-1), medium- (GENT MD, 60 mg·kg-1), and high-dose group (GENT HD groups, 120 mg·kg-1). Except in Sham group, OP model was reproduced with bilateral ovariectomy. ELISA was used to detect the serum levels of bone metabolism indexes (CBF-α1,CTX-Ⅰ, PINP, OC, and E2), and inflammatory indexes (IL-6, TNF-α, and IL-1 β). Three-point bending test was used to evaluate the mechanical strength of the right femur. Micro CT was used to scan the right femur of rats to observe the changes of bone microstructure of the distal femur. HE staining was used to observe the changes of bone histomorphology. TRAP staining was use to analyze the number of osteoclasts on bone surface (N.Oc/BS). Western blotting was used to detect the expression of RANKL, JNK, ERK1/2, p38 MAPK, and their phosphorylated proteins. Results Compared to those in Sham group, the serum E2, bone metabolism related markers, maximum loading and fracture deflection of the femur, BMD, bone trabecular microstructure parameters BV/TV, Tb.N, and Tb.Th decreased significantly in OP group (P<0.05). Inflammatory factors, Tb.Sp, N.Oc/BS, the expression of RANKL, p-JNK/JNK, p-ERK1/2/ERK1/2, and p-p38/p38 in the bone tissue increased significantly (P<0.05). The thickness of cortical bone and the number of trabeculae reduced significantly. The trabeculae were broken and arranged loosely. After the treatment with GENT, the serum levels of E2 and bone metabolism related markers, maximum loading and fracture deflection of the femur, BMD, bone trabecular microstructure parameters BV/TV, Tb.N, and Tb.Th in E2 group and GENT MD, GENT HD groups increased significantly (P<0.05). Inflammatory factors, Tb.Sp, N.Oc/BS, the expression of RANKL, p-JNK/JNK, p-ERK1/2/ERK1/2, and p-p38/p38 in the bone tissue decreased significantly (P<0.05). The new bone trabeculae can be seen with relatively complete morphology. Conclusion GENT improves the bone microstructure of OP rats and has a protective effect from OP. Its mechanism may be related to the inhibition of the activation of MAPK signaling pathway, the formation of osteoclasts, and the reduction of bone resorption. [ABSTRACT FROM AUTHOR]

Osteoporosis is a bone related disease that is characterised by bone loss that further increases the susceptibility to bone fractures and bone frailty due to disturbances in the micro-architecture of bone tissue. Fisetin (flavonoids) exhibited anti-inflammatory and antioxidative stress effects against various diseases. In this protocol, we make an effort to comfort the anti-osteoporosis effect of fisetin against ovariectomy (OVX) induced osteoporosis. A docking study of fisetin and alendronate on the estrogen (α and β) and vitamin D receptors was carried out. SaOS-2 (osteoblast like human) cells were used for the estimation of cell proliferation. The OVX induced OVX model was used and three doses of fisetin and alendronate was given to rats till 16 weeks. The hormone levels, bone turnover markers and biochemical parameters were estimated. Fisetin was docked into estrogen (α and β) and vitamin D receptors, resulting in stable complexes with lower binding scores. Fisetin significantly (p < 0.001) exhibited the induction of cell proliferation against the SaOS-2 cells. OVX induced osteoporosis rats exhibited a suppression of body weight and uterus index, after the Fisetin treatment. Fisetin treatment significantly (p < 0.001) improved the level of bone mineral content (BMC), bone mineral density (BMD) and biochemical parameters such as energy, maximum load, stiffness, young modules, maximum stress and reduced the level of 1,25(OH)2D3 and E2. Fisetin treatment significantly (p < 0.001) declined the level of phosphorus (P), calcium (Ca) and boosted the level of VitD. Fisetin treatment significantly (p < 0.001) reduced the malonaldehyde (MDA) level and enhanced the glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) level in the bone, intestine and hepatic tissue. Fisetin treatment suppressed the cytokines, RANKL/OPG ratio, receptor activator of nuclear factor-κB ligand (RANKL) and improved the level of osteoprotegerin (OPG). The findings suggest that fisetin could be a beneficial phytoconstituent for the treatment and prevention of postmenopausal osteoporotic complications. [ABSTRACT FROM AUTHOR]

Osteoclasts are crucial cellular components of bone and are the cause of various bone problems like osteoporosis. Various biological activities such as anti-tumorous, anti-inflammatory, antibacterial, and immunomodulatory function are influenced by Sclareol, as a natural diterpene compound. However, studies on the effect and mechanism of Sclareol on osteoporosis are rare. In the current research, the influence of Sclareol on osteoclastogenesis and osteoblastogenesis was targeted to be discovered in ovariectomy (OVX)-induced animal models and in vitro. The expression levels of osteoclast-related genes such as c-Fos, NFATc1, and CTSK were detected by RT-qPCR and western blotting to understand the inhibition of Sclareol on the creation of osteoclast. The influence of Sclareol on osteoblastogenesis and the expression of osteoblastogenic markers were also examined. Sclareol inhibited the osteoclastogenesis caused by receptor activator of nuclear factor-κB ligand (RANKL) which promoted osteoblastogenesis through upregulating the expression of cysteine-rich protein 61 (CYR61/CCN1), which is a matricellular protein of the CCN family. The p-ERK and p-P38 protein expression levels were considerably downregulated by Sclareol. Furthermore, CCN1 overexpression partially mimicked the inhibitory effect of Sclareol, while the opposite results were obtained after CCN1 silencing. Additionally, Sclareol protected against loss of bones in an osteoporosis mouse model generated by OVX. The acquired results indicated that Sclareol represses RANKL-induced osteoclastogenesis and promotes osteoblastogenesis via promoting the expression of CCN1 by constraining the mitogen-activated protein kinase (MAPK) pathway. Our findings proposed that for the avoidance and treatment of osteoclast-linked disorders, Sclareol is a potentially effective drug. [ABSTRACT FROM AUTHOR]

Jing Xiong,1 Jieyu Tian,2 Lu Zhou,1 Yanqing Le,1 Yongchang Sun1 1Department of Respiratory and Critical Care Medicine, Peking University Third Hospital, Beijing, 100191, People’s Republic of China; 2Hematology Oncology Center, Beijing Children’s Hospital, Capital Medical University, Beijing 100045, People’s Republic of ChinaCorrespondence: Yongchang SunDepartment of Respiratory and Critical Care Medicine, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing 100191, People’s Republic of ChinaTel +86 156 1196 3697Email suny@bjmu.edu.cnBackground and Purpose: Chronic obstructive pulmonary disease (COPD) is a common chronic inflammatory disease, which is associated with various comorbidities including osteoporosis. Interleukin(IL)-17 has been reported to play important roles in the pathogenesis of COPD and also associated with bone destruction in inflammatory diseases. However, the role of IL-17A in COPD-related osteoporosis is yet unknown. The purpose of our study was to investigate the potential contribution of IL-17A in COPD-related bone loss.Materials and Methods: We examined the bone mass and bone microarchitecture in wild-type and IL-17A-/- mice exposed to long-term cigarette smoke (CS). Osteoclast activities and the expression of receptor activator of nuclear factor-κB ligand (RANKL) in bone tissues were assessed, and the blood levels of inflammatory cytokines were measured.Results: Less bone loss as well as attenuated emphysema were shown in IL-17A-/- mice compared with wild-type mice. CS-exposed IL-17A-/- mice had decreased TRAP+ osteoclast numbers and lower RANKL expression compared with CS-exposed wild-type mice. Inflammatory cytokines including IL-6 and IL-1β in circulation were decreased in IL-17A-/- mice exposed to CS compared with wild-type mice.Conclusion: This study indicates that IL-17A is involved in CS-induced bone loss and may be a common link between COPD and osteoporosis.Keywords: chronic obstructive pulmonary disease, osteoporosis, interleukin 17, receptor activator of nuclear factor-κB ligand

Background: Oral breathing can cause morphological changes in the oral and maxillofacial regions. Aims: To investigate whether oral breathing affected structural changes in bone tissues. Study Design: Animal experimentation. Methods: A total of 48 8-day-old male Sprague−Dawley rats were divided into two groups: a breathing group and a sham (control) group. All Sprague−Dawley rats were killed at 7 weeks after unilateral nostril obstruction modeling. Then, structural changes in bone tissues were detected by micro-computed tomography, and the expression levels of receptor activator of nuclear factor-κB, osteoprotegerin, and receptor activator of nuclear factor-κB ligand in the signal pathway of bone metabolism within the local alveolar bone and serum of rats were detected by reverse transcription-quantitative polymerase chain reaction and Western blotting. Results: The results showed that receptor activator of nuclear factor-κB ligand and receptor activator of nuclear factor-κB levels in bone tissues and serum in the oral breathing group were higher than those in the control group [Maxillary alveolar bone: receptor activator of nuclear factor-κB ligand (pRNA=0.009, pprotein=0.008), receptor activator of nuclear factor-κB (pRNA=0.008, pprotein=0.009); Mandibular alveolar bone: receptor activator of nuclear factor-κB ligand (pRNA=0.047, pprotein=0.042), receptor activator of nuclear factor-κB (pRNA=0.041, pprotein=0.007); Serum: receptor activator of nuclear factor-κB ligand (pRNA

Abstract Background Osteoclasts are key determinant cellular components implicated in the development and progression of disorders driven by bone damage. Herein, we studied the upshot of T007, an antagonist of peroxisome proliferator-activated receptor-gamma (PPARγ), on osteoclastogenesis using cell and animal models. Results The in vitro assays revealed that T007 hindered the osteoclastogenesis caused by the treatment with the receptor activator of nuclear factor-κB ligand (RANKL) through inhibiting the levels of PPARγ in cells. The PPARγ siRNA partially reproduced the inhibitory action of T007. The opposite findings were produced after PPARγ overexpression. Furthermore, T007 prevented from bone loss in a mouse model of osteoporosis induced by ovariectomy (OVX). These findings implied that T007 is a potential efficient drug for the prophylaxis and cure of osteoclast-related disorders. Conclusions Taken together, our findings demonstrated that T007 impedes osteoclastogenesis and will be useful for the therapy of bone related diseases, essentially osteoporosis.

Breast cancer and osteoporosis are common diseases that affect the survival and quality of life in postmenopausal women. Women with breast cancer are more likely to develop osteoporosis than women without breast cancer due to certain factors that can affect both diseases simultaneously. For instance, estrogen and the receptor activator of nuclear factor-κB ligand (RANKL) play important roles in the occurrence and development of these two diseases. Moreover, chemotherapy and hormone therapy administered to breast cancer patients also increase the incidence of osteoporosis, and in recent years, neuropeptide Y (NPY) has also been found to impact breast cancer and osteoporosis.Y1 and Y5 receptors are highly expressed in breast cancer, and Y1 and Y2 receptors affect osteogenic response, thus potentially highlighting a potential new direction for treatment strategies. In this paper, the relationship between breast cancer and osteoporosis, the influence of NPY on both diseases, and the recent progress in the research and treatment of these diseases are reviewed.

Breast cancer and osteoporosis are common diseases that affect the survival and quality of life in postmenopausal women. Women with breast cancer are more likely to develop osteoporosis than women without breast cancer due to certain factors that can affect both diseases simultaneously. For instance, estrogen and the receptor activator of nuclear factor-κB ligand (RANKL) play important roles in the occurrence and development of these two diseases. Moreover, chemotherapy and hormone therapy administered to breast cancer patients also increase the incidence of osteoporosis, and in recent years, neuropeptide Y (NPY) has also been found to impact breast cancer and osteoporosis.Y1 and Y5 receptors are highly expressed in breast cancer, and Y1 and Y2 receptors affect osteogenic response, thus potentially highlighting a potential new direction for treatment strategies. In this paper, the relationship between breast cancer and osteoporosis, the influence of NPY on both diseases, and the recent progress in the research and treatment of these diseases are reviewed. [ABSTRACT FROM AUTHOR]

IL-17 is critical in lung lymphoid neogenesis in COPD, but the cellular and molecular mechanisms remain to be elucidated. Receptor activator of nuclear factor-κB ligand (RANKL) functions in lymphoid follicle formation in other organs, whether it is involved in IL-17A–dependent lymphoid neogenesis in COPD is unknown. To elucidate the expression and functional role of IL-17A/RANKL pathway in COPD. We first quantified and localized RANKL, its receptor RANK and IL-17A in lungs of patients with COPD, smokers and non-smokers. Next, IL-17A−/− and wild-type (WT) mice were exposed to air or cigarette smoke (CS) for 24 weeks, and lung lymphoid follicles and RANKL-RANK expression were measured. Lastly, we studied the in vitro biological function of RANKL pertaining to lymphoid neogenesis. We found that the expressions of RANKL-RANK and IL-17A, together with lymphoid follicles, were increased in lung tissues from patients with COPD. In WT mice exposed to CS, RANKL-RANK expressions were prominent in lung lymphoid follicles, which were absent in IL-17A−/− mice exposed to CS. In the lymphoid follicles, RANKL+ cells were identified mostly as B cells and RANK was localized in dendritic cells (DCs). In vitro IL-17A increased the expressions of RANKL in B cells and RANK in DCs, which in turn responded to RANKL stimulation by upregulation of CXCL13. Altogether, these results suggest that B lymphocyte RANKL pathway is involved in IL-17A–dependent lymphoid neogenesis in COPD.

Osteoclasts with elevated bone resorption are commonly present in postmenopausal osteoporosis, and other osteolytic pathologies. Therefore, suppressing osteoclast generation and function has been the main focus of osteoporosis treatment. Betulinic acid (BA) represents a triterpenoid mainly purified from the bark of Betulaceae. BA shows multiple biological activities, including antitumor and anti-HIV properties, but its effect on osteolytic conditions is unknown. Here, BA suppressed receptor activator of nuclear factor‐κB ligand (RANKL)‐associated osteoclastogenesis and bone resorptive function, as assessed by tartrate‐resistant acid phosphatase (TRAP) staining, fibrous actin ring generation, and hydroxyapatite resorption assays. Mechanistically, BA downregulated the expression of osteoclastic-specific genes. Western blot analysis revealed that BA significantly interrupted ERK, JNK and p38 MAPK activation as well as intracellular reactive oxygen species (ROS) production, thus altering c-Fos and NFATc1 activation. Corroborating the above findings in cell-based assays, BA prevented ovariectomy-associated bone loss in an animal model. In conclusion, these findings suggest that BA can inhibit osteoclast generation and function as well as the RANKL signaling pathway, and might be used for treating osteoclast-related osteoporosis.

Lu Zhou,1 Yanqing Le,1 Jieyu Tian,2 Xia Yang,2 Rong Jin,3 Xiaoyan Gai,1 Yongchang Sun1 1Department of Respiratory Medicine, Peking University Third Hospital, Beijing, China; 2Department of Respiratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China; 3Department of Immunology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China Background and purpose: Cigarette smoke (CS) induces alveolar destruction through overproduction of proteinases including matrix metalloproteinase (MMP)-9 by alveolar macrophages (AMs). Receptor activator of nuclear factor-κB ligand (RANKL) functions in immune regulation and cytokine secretion; whether it is involved in CS-induced MMP-9 expression is unknown. The purpose of our study was to investigate the expression and functional role of RANKL pathway in MMP-9 production pertaining to the pathogenesis of COPD. Materials and methods: We first localized RANKL and its receptor RANK in the lungs of mice exposed to long-term CS exposure. Next, we studied RANKL and RANK expression under CS extract (CSE) stimulation in vitro. Lastly, we studied the in vitro biological function of RANKL in CS-induced production of MMP-9. Results: Both RANKL and RANK were highly expressed in AMs in CS-exposed mice, but not in the control mice. In vitro, CSE increased the expressions of RANKL and RANK in macrophages. AMs responded to CSE and RANKL stimulation by overexpressing MMP-9, and CSE-induced MMP-9 expression was partly blocked by using monoclonal anti-RANKL antibody. Conclusion: RANKL/RANK pathway mediates CS-induced MMP-9 expression in AMs, suggesting a novel mechanism for CS-associated emphysema. Keywords: COPD, receptor activator of nuclear factor-κB ligand, RANK, alveolar macrophages, MMP-9

In ultra-rare bone diseases, information on growth during childhood is sparse. Juvenile Paget disease (JPD) is an ultra-rare disease, characterized by loss of function of osteoprotegerin (OPG). OPG inhibits osteoclast activation via the receptor activator of nuclear factor-κB (RANK) pathway. In JPD, overactive osteoclasts result in inflammatory-like bone disease due to grossly elevated bone resorption. Knowledge on the natural history of JPD, including final height and growth, is limited. Most affected children receive long-term antiresorptive treatment, mostly with bisphosphonates, to contain bone resorption, which may affect growth. In this study, we report the follow-up of height, growth velocity, and skeletal maturation in a 16-year-old female patient with JPD. The patient was treated with cyclic doses of pamidronate starting at 2.5 years of age and with 2 doses of denosumab at the age of 8 years, when pamidronate was paused. In the following years, a sustainable decline in a height z-score and a stunted pubertal growth spurt; despite appropriate maturation of the epiphyseal plates of the left hand, the proximal right humerus and both femora were observed. Whether this reflects the growth pattern in JPD or might be associated to the antiresorptive treatments is unclear, since there is very limited information available on the effect of bisphosphonates and denosumab on growth and the growth plate in pediatric patients. Studies are needed to understand the natural history of an ultra-rare bone disease and to assess the effects of antiresorptive treatment on the growing skeleton. [ABSTRACT FROM AUTHOR]

IL-17 is critical in lung lymphoid neogenesis in COPD, but the cellular and molecular mechanisms remain to be elucidated. Receptor activator of nuclear factor-κB ligand (RANKL) functions in lymphoid follicle formation in other organs, whether it is involved in IL-17A–dependent lymphoid neogenesis in COPD is unknown. To elucidate the expression and functional role of IL-17A/RANKL pathway in COPD. We first quantified and localized RANKL, its receptor RANK and IL-17A in lungs of patients with COPD, smokers and non-smokers. Next, IL-17A−/− and wild-type (WT) mice were exposed to air or cigarette smoke (CS) for 24 weeks, and lung lymphoid follicles and RANKL-RANK expression were measured. Lastly, we studied the in vitro biological function of RANKL pertaining to lymphoid neogenesis. We found that the expressions of RANKL-RANK and IL-17A, together with lymphoid follicles, were increased in lung tissues from patients with COPD. In WT mice exposed to CS, RANKL-RANK expressions were prominent in lung lymphoid follicles, which were absent in IL-17A−/− mice exposed to CS. In the lymphoid follicles, RANKL+ cells were identified mostly as B cells and RANK was localized in dendritic cells (DCs). In vitro IL-17A increased the expressions of RANKL in B cells and RANK in DCs, which in turn responded to RANKL stimulation by upregulation of CXCL13. Altogether, these results suggest that B lymphocyte RANKL pathway is involved in IL-17A–dependent lymphoid neogenesis in COPD. [ABSTRACT FROM AUTHOR]

Osteolytic diseases are typified by over‐enhanced formation and resorbing function of osteoclasts and have a major impact on human health. Inhibition of osteoclastic differentiation and function is a key strategy for clinical therapy of osteolytic conditions. Maackiain is a natural compound extracted from Sophora flavescens, which has been applied to anti‐allergic and anti‐tumour treatments. The present results showed that Maackiain could restrain receptor activator of nuclear factor‐κB ligand (RANKL)‐stimulated osteoclast formation and hydroxyapatite resorption dose‐dependently, and interrupt the structures of F‐actin belts in the mature osteoclasts. It also repressed the expressions of osteoclast‐specific genes and proteins. Furthermore, Maackiain could inhibit RANKL‐stimulated NF‐κB and calcium signalling pathways, and dampen Nuclear factor of activated T cell cytoplasmic 1 activity, protein expression and translocation into the nucleus. These results revealed that Maackiain may have a potential therapeutic effect on osteoclast‐related disorders. [ABSTRACT FROM AUTHOR]

Osteoclasts with elevated bone resorption are commonly present in postmenopausal osteoporosis, and other osteolytic pathologies. Therefore, suppressing osteoclast generation and function has been the main focus of osteoporosis treatment. Betulinic acid (BA) represents a triterpenoid mainly purified from the bark of Betulaceae. BA shows multiple biological activities, including antitumor and anti-HIV properties, but its effect on osteolytic conditions is unknown. Here, BA suppressed receptor activator of nuclear factor‐κB ligand (RANKL)‐associated osteoclastogenesis and bone resorptive function, as assessed by tartrate‐resistant acid phosphatase (TRAP) staining, fibrous actin ring generation, and hydroxyapatite resorption assays. Mechanistically, BA downregulated the expression of osteoclastic-specific genes. Western blot analysis revealed that BA significantly interrupted ERK, JNK and p38 MAPK activation as well as intracellular reactive oxygen species (ROS) production, thus altering c-Fos and NFATc1 activation. Corroborating the above findings in cell-based assays, BA prevented ovariectomy-associated bone loss in an animal model. In conclusion, these findings suggest that BA can inhibit osteoclast generation and function as well as the RANKL signaling pathway, and might be used for treating osteoclast-related osteoporosis. [ABSTRACT FROM AUTHOR]

Summary: There is still a lack of evidence that minodronate or denosumab prevents bone loss due to androgen deprivation therapy (ADT) in non-Western patients. This study showed that both drugs significantly improved lumbar spine and total hip bone mineral density in Asian men with prostate cancer who received ADT. Introduction: To evaluate whether monthly oral minodronate or semiannual subcutaneous injection of denosumab improves bone mineral density (BMD) in Asian men with prostate cancer (PCa) receiving ADT. Methods: A multicenter, open-label, randomized, controlled study including patients with hormone-sensitive PCa without bone metastasis receiving ADT was performed. Patients were randomized (1:1:1) to minodronate, denosumab, or no agent control groups. The primary end point was the mean percentage change in BMD at the lumbar spine at 12 months. Secondary end points were the mean percentage change in BMD at the femoral neck and total hip and changes in bone turnover markers. Statistical comparison was performed using analysis of covariance. Results: Of the 147 subjects enrolled in this study, 102 were randomly assigned into the minodronate (n = 36), denosumab (n = 36), and control (n = 30) groups. The percentage change in BMD at the lumbar spine was significantly improved in the minodronate (2.5%, p < 0.05) and denosumab groups (4.0%, p < 0.01) compared with that in the control group (− 0.1%). Denosumab increased BMD at the femoral neck and total hip at 12 months, whereas minodronate only increased BMD at the total hip compared with controls (all p < 0.05). The percentage change in bone turnover markers at 12 months was significantly lower in the minodronate and denosumab groups compared with that in the control group (both p < 0.01). Conclusion: Minodronate or denosumab can be used for preventing bone loss related to ADT in Asian patients with PCa. [ABSTRACT FROM AUTHOR]

Although the role of cathepsin C (Cat C) in inflammation is gradually being elucidated, its function in periapical periodontitis, which is one of the most common infectious diseases worldwide, has not been studied. This study evaluated a surgically-induced model of periapical periodontitis in cathepsin C (Cat C) knock-down (KD) mice, which was constructed with a tetracycline operator, to evaluate the role of Cat C in the pathogenesis and progression of periapical periodontitis. Our results showed, for the first time, that there was a statistically significant increase in the expression of Cat C as periapical periodontitis progressed; this increase started from 1 week after surgery and reached a peak at 3 weeks after surgery, before gradually decreasing. The volume of periapical bone resorption in Cat C KD mice was significantly smaller than that in wild-type mice at 3 and 4 weeks after surgery (P <0.05). Inflammatory cell infiltration into the apical tissues of wild-type mice was also significantly higher than that of Cat C KD mice. The expression of receptor activator of nuclear factor-κB ligand (RANKL) in wild-type mice was also higher than that in Cat C KD mice. The difference in the number of osteoclasts in the apical area between the two groups was statistically significant after 2 weeks. Correlation analysis showed that there was a significant correlation between Cat C and RANKL expression (r = 0.835). Therefore, our data indicated that Cat C promoted the apical inflammation and bone destruction in mice. [ABSTRACT FROM AUTHOR]

Mannan-binding lectin (MBL) is a vital element in the host innate immune system, which is primarily produced by the liver and secreted into the circulation. Low serum level of MBL is reported to be associated with an increased risk of arthritis. However, the underlying mechanism by which MBL contributes to the pathogenesis of arthritis is poorly understood. In this study, we investigated the precise role of MBL on the course of experimental murine adjuvant-induced arthritis (AIA). MBL-deficient (MBL−/−) AIA mice showed significantly increased inflammatory responses compared with wild-type C57BL/6 AIA mice, including exacerbated cartilage damage, enhanced histopathological features and high level of tartrate-resistant acid phosphatase (TRAP)-positive cells. MBL protein markedly inhibited the osteoclast formation from human blood monocytes induced by receptor activator of nuclear factor-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in vitro. Mechanistic studies established that MBL inhibited osteoclast differentiation via down-regulation of p38 signaling pathway and subsequent nuclear translocation of c-fos as well as activation of nuclear factor of activated T-cells c1 (NFATc1) pathway. Importantly, we have provided the evidence that concentrations of MBL correlated negatively with the serum levels of amino-terminal propeptide of type I procollagen (PINP) and C-terminal telopeptide of type I collagen (β-CTX), serum markers of bone turnover, in patients with arthritis. Our study revealed an unexpected function of MBL in osteoclastogenesis, thus providing new insight into inflammatory arthritis and other bone-related diseases in patients with MBL deficiency.

The balance between the osteoblasts and the osteoclasts is important for the maintenance of the skeleton of the human body. The osteoclasts absorb bone after differentiated into polymorphonuclear cells by the fusion of monocytes/macrophages. We have found that 6,7,4'-Trihydroxyflavone (THF), a compound from the heartwood of Dalbergia Odorifera inhibits receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation, actin ring formation, and bone resorption in RAW 264.7 cells and bone marrow macrophage. THF significantly inhibited the c-Jun-N-terminal kinase signaling pathway without affecting extracellular signal-regulated kinase, p38, and AKT signaling. Moreover, THF inhibited the expression of c-Fos, nuclear factor-activated T cells cytoplasm 1, cathepsin K, and c-src by RANKL. We used a lipopolysaccharide (LPS)-induced bone loss model in mice. Consequently, bone volume per tissue volume, trabecular number's reduction was recovered in THF-treated mice, and trabecular separation's augmentation was also attenuated by THF administration. In summary, THF inhibits RANKL-induced osteoclast differentiation by MAPK signaling pathway and inhibits bone resorption by destroying the actin ring in mature osteoclasts. THF also prevented LPS-induced bone loss in a mice model. Thus, THF may be useful in the treatment of bone diseases associated with excessive osteoclast differentiation and bone resorption. [ABSTRACT FROM AUTHOR]

Copyright of West China Journal of Stomatology is the property of Sichuan University, West China College of Stomatology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mannan-binding lectin (MBL) is a vital element in the host innate immune system, which is primarily produced by the liver and secreted into the circulation. Low serum level of MBL is reported to be associated with an increased risk of arthritis. However, the underlying mechanism by which MBL contributes to the pathogenesis of arthritis is poorly understood. In this study, we investigated the precise role of MBL on the course of experimental murine adjuvant-induced arthritis (AIA). MBL-deficient (MBL−/−) AIA mice showed significantly increased inflammatory responses compared with wild-type C57BL/6 AIA mice, including exacerbated cartilage damage, enhanced histopathological features and high level of tartrate-resistant acid phosphatase (TRAP)-positive cells. MBL protein markedly inhibited the osteoclast formation from human blood monocytes induced by receptor activator of nuclear factor-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in vitro. Mechanistic studies established that MBL inhibited osteoclast differentiation via down-regulation of p38 signaling pathway and subsequent nuclear translocation of c-fos as well as activation of nuclear factor of activated T-cells c1 (NFATc1) pathway. Importantly, we have provided the evidence that concentrations of MBL correlated negatively with the serum levels of amino-terminal propeptide of type I procollagen (PINP) and C-terminal telopeptide of type I collagen (β-CTX), serum markers of bone turnover, in patients with arthritis. Our study revealed an unexpected function of MBL in osteoclastogenesis, thus providing new insight into inflammatory arthritis and other bone-related diseases in patients with MBL deficiency. [ABSTRACT FROM AUTHOR]

Background/Aims: Evidence suggests that IL-6 affects bone mass by modulating osteocyte communication towards osteoclasts. However, the mechanism by which IL-6 enhances osteocyte-mediated osteoclastogenesis is unclear. We aimed to investigate the inflammatory factors in serum after orthodontic surgery and their relationship between osteocytes and osteoclasts. Methods: Serum was obtained from 10 orthognathic surgery patients, and inflammatory factors were detected by ELISA. We treated the osteocyte-like cell line MLO-Y4 with recombinant mouse IL-6 and IL-6 receptor (IL-6R), and used quantitative RT-PCR and Western blotting to explore Receptor activator of nuclear factor-κB ligand (RANKL) expression at both the mRNA and protein level. MLO-Y4 cells were co-cultured with osteoclast precursor cells, and the formation of osteoclasts was detected by tartrate-resistant acid phosphatase (TRAP) staining. To explore the role of JAK2 in the osteocyte-mediated osteoclastogenesis, AG490, a JAK2 inhibitor, was used to inhibit the JAK2-STAT3 pathway in osteocytes. Results: In our study, we found that IL-6 and RANKL were stimulated in serum 3-7 days after orthognathic surgery. Therefore, IL-6 and IL-6 receptor enhanced the expression of RANKL at both the mRNA and protein level in MLO-Y4. Furthermore, when MLO-Y4 cells were co-cultured with osteoclast precursor cells, it significantly stimulated osteoclastogenesis. Our study indicated that osteocytes could promote osteoclastic differentiation and the formation of TRAP-positive multinucleated cells after stimulation with IL-6 and IL-6R. Our results also indicated that treatment with IL-6 and IL-6R increased RANKL mRNA expression and the RANKL/OPG expression ratio. Meanwhile, the phosphorylation of Janus kinase 2 (JAK2) and Signal transducer and activator of transcription (STAT3) also correlated with RANKL levels. Furthermore, we investigated the effects of a specific JAK2 inhibitor, AG490, on the expression of RANKL in osteocyte-like MLO-Y4 cells and osteocyte-mediated osteoclastogenesis. The results showed that AG490 inhibited (p)-JAK2 and RANKL expression. Osteoclastic differentiation was decreased after pretreatment in MLO-Y4 with mouse IL-6/IL-6R and AG490; therefore, we concluded that IL-6 increased osteocyte-mediated osteoclastic differentiation by activating JAK2 and RANKL. Conclusion: The effects of IL-6/il-6R and AG490 on osteocyte-mediated osteoclastogenesis contribute to our understanding of the role of inflammatory factors in the interaction between osteocytes and osteoclast precursors. IL-6 and RANKL are key factors for bone remodelling after the orthodontic surgery, and their roles in bone remodelling may be fundamental mechanisms accelerating tooth movement by orthodontic surgery.

Osteoblast differentiation is important for the development of bone and the maintenance of bone density. Propionibacterium freudenreichii is a probiotic with an anti-inflammatory property. The aim of this study was to investigate the enhancement effect of P. freudenreichii MJ2 (MJ2) isolated from raw milk on osteoblast differentiation, mineralization, and its signaling pathway. For in vitro and in vivo experiments, human fetal osteoblastic cell line hFOB 1.19 and an ovariectomized rat model were used, respectively. Expression levels of genes and proteins related to osteoblast differentiation and mineralization were measured by real-time polymerase chain reaction (qPCR) and Western blotting, respectively. Alizarin red S staining was performed to measure osteoblast mineralization. Heat-killed MJ2 (hkMJ2)-treated cells showed significantly increased osteoblast differentiation via an increase in the osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL) ratio and significantly increased osteoblast mineralization by stimulating the expression of bone morphogenetic protein 2 and runt-related transcription factor 2. Additionally, oral administration of live or heat-killed MJ2 to ovariectomized rats inhibited osteoporosis-induced bone loss. Specifically, surface proteins isolated from MJ2 promoted osteoblast differentiation and mineralization. In conclusion, MJ2 enhanced osteoblast differentiation and mineralization through the OPG/RANKL signaling pathway and the effective component of MJ2 might be its surface proteins.

This aim of this study was to assess the molecular mechanism of osteoporosis in schizophrenia patients with risperidone use. Here, we investigated the effects of risperidone on cellular proliferation and apoptosis of a preosteoblast cell line, MC3T3-E1. Cell viability and apoptotic rate of MC3T3-E1 were detected by cell counting kit-8 and flow cytometry at a serial dose of risperidone and at different time points, respectively. Bone transformation relevant gene serum osteocalcin (BGP), collagen 1, tumor necrosis factor-α (TNF-α), osteoprotegerin (OPG), and receptor activator of nuclear factor-κB ligand (RANKL) mRNA levels were determined by real-time PCR (qPCR). Their protein expression patterns were evaluated using western blot. The results revealed that risperidone dramatically inhibited MC3T3-E1 cell proliferation in a dose-dependent manner. It also significantly induced MC3T3-E1 cell apoptosis. TNF-α gene and protein levels were greatly enhanced after risperidone treatment. In contrast, BGP, collagen 1, OPG, and RANKL gene and protein levels were markedly downregulated. Our study indicated that risperidone suppressed MC3T3-E1 cell proliferation and induced apoptosis. It also regulated BGP gene and protein expression.

Background: Osteoporosis is a common complication of chronic obstructive pulmonary disease (COPD). Recent clinical and biological researches have increasingly delineated the biomolecular pathways of bone metabolism regulation in COPD. We extended this work by examining the specific association and potential contribution of the osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL) axis to the pathogenesis of osteoporosis in advanced COPD. The aim of this study was to assess the relationships of serum OPG, RANKL, and tumor necrosis factor-alpha (TNF-μ) with bone turnover in men with very severe COPD. Methods: Pulmonary function, T-score at the lumbar spine (LS) and femoral neck (FN), serum OPG, RANKL, soluble receptor of tumor necrosis factor-alpha-I and II (sTNFR-I, sTNFR-II), osteocalcin (OC), and β-CrossLaps (βCL) levels were measured in 45 men with very severe stage COPD and 36 male non-COPD volunteers. COPD patients and healthy controls were compared using an independent t-test and Mann–Whitney U-test. The Pearson coefficient was used to assess the relationships between variables. Results: OPG and OC were lower in male COPD patients than in control subjects whereas RANKL, serum βCL, TNF-μ, and its receptors were higher. OPG directly correlated with forced expiratory volume in 1 s (FEV1) % predicted (r = 0.46, P < 0.005), OC (r = 0.34, P < 0.05), LS (r = 0.56, P < 0.001), and FN T-score (r = 0.47, P < 0.01). In contrast, serum RANKL inversely associated with LS and FN T-score (r = −0.62, P < 0.001 and r = −0.48, P < 0.001) but directly correlated with βCL (r = 0.48, P < 0.001). In addition, OPG was inversely correlated with RANKL (r = −0.39, P < 0.01), TNF-μ (r = −0.56, P < 0.001), and sTNFR-I (r = −0.40, P < 0.01). Conclusion: Our results suggest that serum OPG and RANKL levels are inversely associated with bone loss in men with advanced stage COPD.

Receptor activator of nuclear factor-κB ligand (RANKL) had been confirmed contributing to the development and progression of AF by regulating atrial structural remodeling. But the involved genetic mechanism is unknown. We intended to explore the association between the polymorphism RANKL −1816C>G (rs7984870) and susceptibility and prognosis of lone AF. RANKL rs7984870 was genotyped in a case-control study of 828 patients and 834 controls in Chinese population. The CG and/or CC genotypes had an increased lone AF risk [adjusted odds ratio (OR) 1.20 for CG, OR 2.16 for CC, and OR 1.55 for CG/CC], compared with the GG genotype. Moreover, patients carrying CG/CC genotypes showed a higher possibility of AF recurrence after catheter ablation, compared with patients carrying GG genotype. In a genotype-phenotype correlation analysis using 24 normal left atrial appendage samples, increasing gradients of atrial RANKL expression levels positively correlated with atrial collagen volume fraction were identified in samples with CC, CG and GG genotypes. The in vitro luciferase assays also showed a higher luciferase activity of the −1816 C/C allele than that of the −1816 G/G allele. These results suggested that RANKL rs7984870 is involved in the etiology of lone AF and thus may be a marker for genetic susceptibility to lone AF and predicting prognosis after catheter ablation in Chinese populations. Therefore, we provide new information about treatment strategies and our understanding of RANKL in AF. [ABSTRACT FROM AUTHOR]

Adiponectin (APN) has been shown to play a key role in regulating bone mineral density (BMD). Nevertheless, the effects of APN on receptor activator of NF-κB ligand (RANKL)-induced osteoclast formation and mechanism of regulation are not entirely clear. The study, therefore, aimed to evaluate the effect of APN on osteoclastogenesis. Our results showed that APN inhibits osteoclastogenesis and resorption function in vitro by suppressing nuclear factor-κB (NF-κB) and p38 signaling pathways, which is essential for osteoclast formation. Moreover, APN blocked the formation of F-actin rings and attenuated osteoclast-mediated bone resorptive function. Therefore, we concluded that APN may provide a potential treatment for osteoclast-related diseases, such as osteoporosis. [ABSTRACT FROM AUTHOR]

When bone resorption, aided by the activity of osteoclasts, exceeds bone formation induced by osteoblasts, bone metabolism loses equilibration, which results in the development of bone diseases, including osteoporosis. Pulsed electromagnetic fields (PEMFs) are known to be involved in various biological processes, including cell proliferation, differentiation and apoptosis. However, the exact mechanism of action of osteoclasts remains poorly understood. In the present study, the effects of PEMFs on osteoclast differentiation and associated signaling pathways were systematically investigated in RAW264.7 macrophages. RAW264.7 cells were induced by receptor activator of nuclear factor-κB ligand (RANKL) to obtain osteoclasts in vitro. The results of the present study demonstrated that PEMF exposure decreased osteoclast formation, limited tartrate-resistant acid phosphatase activity, contracted bone resorption area and inhibited osteoclastic specific gene and protein expression. Furthermore, western blot analysis indicated that PEMFs distinctly abolished the upregulation of phosphorylated-protein kinase B (Akt), -mammalian target of rapamycin (mTOR) and -ribosome S6 protein kinase (p70S6K) induced by RANKL, which was consistent with the effects of pharmacological inhibitor perifosine and rapamycin. Therefore, the present study suggested that PEMFs reduced osteoclast formation from RAW264.7 macrophages via inhibition of the Akt/mTOR signaling pathway. These findings provided novel insight into the mechanisms through which PEMFs suppress osteoclast differentiation. [ABSTRACT FROM AUTHOR]

Dishevelled (Dvl)-2 represents one of the cytoplasmic proteins, which serves as a pivotal hub in signaling intermediates through a number of different signaling pathways associated with the Wnt family. The aim of the present study was to investigate the roles and mechanisms of Dvl-2 on synovial fibroblasts (SFBs) in osteoarthritis (OA). A Cell Counting kit-8 (CCK-8) assay was used to determine cell viability. An alkaline phosphatase (ALP) test kit was used to measure the activity of ALP. Western blot and reverse transcription-quantitative polymerase chain reaction analysis were used to evaluate the protein and mRNA expression, respectively. The results suggest that depletion of Dvl-2 significantly decreased the expression of osteoprotegerin (OPG) and ALP (P<0.05) and significantly increased the expression of receptor activator of nuclear factor-κB ligand (RANKL), ALP, osteonectin (ON), osteocalcin (OCN) and osterix (P<0.05). In addition, the depletion of Dvl-2 also significantly inhibited the expression of runt-related transcription factor 2 (Runx-2) and β-catenin in SFBs (P<0.05). The effect of Dvl-2 over-expression was opposite to the effect of Dvl-2 silencing. The inactivation of Wnt3a reversed the effect of Dvl-2 silencing. In conclusion, the results indicate that Dvl-2 regulated osteogenic differentiation of SFBs in OA. [ABSTRACT FROM AUTHOR]

Receptor activator of nuclear factor‑κB ligand (RANKL), a member of the tumor necrosis factor receptor‑ligand family, is a crucial factor involved in osteoclast differentiation. Crocin, a pharmacologically active component of Crocus sativus L., has been reported to attenuate ovariectomy‑induced osteoporosis in rats. However, the molecular mechanism underlying the effect of crocin on osteoclast formation remains to be determined. The present study aimed to investigate the effect of crocin on RANKL‑induced osteoclastogenesis and its underlying molecular mechanism. Results demonstrated that crocin decreased osteoclastogenesis in bone marrow‑derived macrophages (BMMs). In addition, the expression levels of osteoclast marker proteins were downregulated by crocin. Mechanistically, crocin inhibited RANKL‑induced activation of nuclear factor‑κB (NF‑κB) by suppressing inhibitor of κBα degradation and preventing NF‑κB p65 subunit nuclear translocation, and by activating c‑Jun N‑terminal kinase (JNK) in BMMs. In summary, the results of the present study suggested that crocin downregulates osteoclast differentiation via inhibition of JNK and NF‑κB signaling pathways. Thus, crocin may be a potential therapeutic agent for the treatment of osteoclast‑associated diseases, including osteoporosis. [ABSTRACT FROM AUTHOR]

Prostate cancer (PCa) is one of the most prevalent diagnosed malignancies globally. Previous studies have demonstrated that prostaglandin E2 (PGE2) is closely associated with the tumorigenesis and progression of PCa. However, the underlying molecular mechanisms remain unclear and require further investigation. Matrix metalloproteinases (MMPs), receptor activator of nuclear factor‑κB ligand (RANKL) and runt‑related transcription factor 2 (RUNX2), which are involved in cell growth and bone metastasis, are frequently activated or overexpressed in various types of cancer, including PCa. The present study was designed to investigate the associations between PGE2 and the PGE2 receptor EP4, and MMPs, RANKL and RUNX2 in PCa, and to define their roles in PCa cell proliferation and invasion in addition to understanding the molecular mechanisms. The results of western blotting and reverse transcription‑quantitative polymerase chain reaction demonstrated that the protein and the mRNA expression levels of MMP‑2, MMP‑9, RANKL and RUNX2 in PC‑3 cells were significantly upregulated by treatment with PGE2, respectively, and knockdown of these proteins blocked PGE2‑induced cell proliferation and invasion in PC‑3 cells, as determined by Cell Counting Kit‑8 and Matrigel invasion assays, respectively. The effect of PGE2 on the protein and mRNA expression levels was primarily regulated via the EP4 receptor. EP4 receptor signaling activates the cyclic (c)AMP‑protein kinase A (PKA) signaling pathway, and forskolin, an activator of adenylate cyclase (AC), exhibited similar effects to an EP4 receptor agonist on the protein expression, while SQ22536, an inhibitor of AC, inhibited the protein expression. These results confirmed that the AC/cAMP pathway may be involved in EP4 receptor‑mediated upregulation of protein expression. By using a specific inhibitor of PKA, it was also demonstrated that cAMP/PKA was also involved in the EP4 receptor‑mediated upregulation of protein expression. In addition to the signaling pathway involving PKA, the EP4 receptor also exerts activities through activation of Akt kinase. The results in the present study confirmed the hypothesis that EP4 receptor‑mediated protein expression in PCa cells that were pretreated with a specific inhibitor of phosphatidylinositol 3‑kinase (PI3K) was significantly inhibited. In conclusion, the results of the present study indicate that PGE2 significantly upregulated the mRNA and protein expression levels of the MMP‑2, MMP‑9, RANKL and RUNX2, and the EP4 receptor was involved in the cell proliferation and invasion of PCa via the cAMP‑PKA/PI3K‑Akt signaling pathway. These results may provide novel insight into potential therapeutic strategies for the prevention and treatment of PCa. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the effects of strontium ranelate (SR), an anti‑osteoporotic drug, on osteolysis in an experimental mouse model of aseptic loosening. A total of 45 female C57BL/6J mice each received implantation of one titanium alloy pin into the tibia, followed by intraarticular injection of titanium particles. One week following surgery, mice were randomly divided into three groups: Control group (no additional treatment), SR625 group (treated with SR at a dose of 625 mg/kg/day), and SR1800 group (treated with SR at a dose of 1,800 mg/kg/day). SR was administered via oral gavage once every day for 12 weeks. Micro‑computed tomography scanning and hematoxylin/ eosin staining were used to assess osteolysis around the prosthesis. Immunohistochemistry and reverse transcription‑quantitative polymerase chain reaction analysis were used to measure the expression of receptor activator of nuclear factor‑κB ligand (RANKL) and osteoprotegerin (OPG). Compared with the control, the SR625 and SR1800 groups exhibited a significantly increased pulling force of the titanium alloy pin. Bone volume and the bone surface/volume ratio in the periprosthetic tissue were significantly increased in the SR‑treated groups. Significant differences were observed between the SR1800 group and control group with respect to trabecular thickness and trabecular number. Mechanistically, SR downregulated the expression of RANKL and upregulated the expression of OPG in the periprosthetic tissue. In addition, SR was observed to inhibit wear particle‑associated osteolysis in a dose‑dependent manner. In conclusion, the present data illustrated that SR inhibited titanium particle‑induced osteolysis in vivo. [ABSTRACT FROM AUTHOR]

Puerarin, an isoflavone-C-glucoside extracted from the root of Pueraria Labata (Willd.) Ohwi, is one of the most important crude herbs used in Chinese medicine for various medicinal purposes. Accumulating evidence has indicated that puerarin suppresses bone resorption and promotes bone formation. However, the molecular mechanism involved in puerarin-associated bone formation is unclear. The present study aimed to investigate the molecular mechanism of puerarin-induced osteoblast proliferation and differentiation. The study showed that puerarin treatment differentially affected cell proliferation in a time-dependent manner. Notably, at a concentration of 20 µM, puerarin significantly promoted cell proliferation in comparison with the control (P<0.01). Furthermore, puerarin promoted MC3T3-E1 cell differentiation at an appropriate concentration. In addition, miR-106b was significantly upregulated in MC3T3-E1 cells following treatment with 20 µM puerarin (P<0.01), and a known target for miR-106b, receptor activator of nuclear factor-κB ligand (RANKL) was demonstrated using the luciferase reporter assay. Furthermore, inhibition of miR-106b significantly reversed the promotion of cell differentiation induced by puerarin in MC3T3-E1 cells (P<0.01). In conclusion, the present study demonstrated that puerarin exerts its role in MC3T3-E1 osteogenesis through miR-106b by targeting RANKL. The findings suggest that puerarin may be considered a promising anti-osteoporotic agent for the treatment of osteoporosis. [ABSTRACT FROM AUTHOR]