Nuclear factor-κB Ligand Research Articles

Differential role of M cells in enteroid infection by Mycobacterium avium subsp. paratuberculosis and Salmonella enterica serovar Typhimurium.

Infection of ruminants such as cattle with Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease, a disease characterized by chronic inflammation of the small intestine and diarrhoea. Infection with MAP is acquired via the faecal-to-oral route and the pathogen initially invades the epithelial lining of the small intestine. In this study we used an in vitro 3D mouse enteroid model to determine the influence of M cells in infection of the gut epithelia by MAP, in comparison with another bacterial intestinal pathogen of veterinary importance, Salmonella enterica serovar Typhimurium. The differentiation of M cells in the enteroid cultures was induced by stimulation with the cytokine receptor activator of nuclear factor-κB ligand (RANKL), and the effects on MAP and Salmonella uptake and intracellular survival were determined. The presence of M cells in the cultures correlated with increased uptake and intracellular survival of Salmonella, but had no effect on MAP. Interestingly neither pathogen was observed to preferentially accumulate within GP2-positive M cells.

Intratumoral injection of mRNA encoding survivin in combination with STAT3 inhibitor stattic enhances antitumor effects

Intratumoral delivery of mRNA encoding immunostimulatory molecules can initiate a robust, global antitumor response with little side effects by enhancing local antigen presentation in the tumor and the tumor draining lymph node. Neoantigen-based mRNA nanovaccine can inhibit melanoma growth in mice by intratumoral injection. Myeloid-derived suppressor cells (MDSCs) suppress antitumor immune responses by secreting immunosuppressive agents, such as reactive oxygen species (ROS). Suppression of STAT3 activity by stattic may reduce MDSC-mediated immunosuppression in the TME and promote the antitumor immune responses. In this study, in vitro transcribed mRNA encoding tumor antigen survivin was prepared and injected intratumorally in BALB/c mice bearing subcutaneous colon cancer tumors. In vivo studies demonstrated that intratumoral survivin mRNA therapy could induce antitumor T cell response and inhibit tumor growth of colon cancer. Depletion of CD8+ T cells could significantly inhibit survivin mRNA-induced antitumor effects. RT-qPCR and ELISA analysis indicated that survivin mRNA treatment led to increased expression of receptor activator nuclear factor-κB ligand (RANKL). In vitro experiment showed that MDSCs could be induced from mouse bone marrow cells by RANKL and RANKL-induced MDSCs could produce high level of ROS. STAT3 inhibitor stattic suppressed activation of STAT3 and NF-κB signals, thereby inhibiting expansion of RANKL-induced MDSCs. Combination therapy of survivin mRNA and stattic could significantly enhance antitumor T cell response, improve long-term survival and reduce immunosuppressive tumor microenvironment compared to each monotherapy. In addition, combined therapy resulted in a significantly reduced level of tumor cell proliferation and an obviously increased level of tumor cell apoptosis in CT26 colon cancer-bearing mice, which could be conducive to inhibit the tumor growth and lead to immune responses to released tumor-associated antigens. These studies explored intratumoral mRNA therapy and mRNA-based combined therapy to treat colon cancer and provide a new idea for cancer therapy.

Autophagy regulates bone loss via the RANKL/RANK/OPG axis in an experimental rat apical periodontitis model.

Autophagy is involved in human apical periodontitis (AP). However, it is not clear whether autophagy is protective or destructive in bone loss via the receptor activator of nuclear factor-κB ligand (RANKL)/RANK/osteoprotegerin (OPG) axis. This study aimed to investigate the involvement of autophagy via the RANKL/RANK/OPG axis during the development of AP in an experimental rat model. Twenty-four female Sprague-Dawley rats were divided into control, experimental AP (EAP) + saline, and EAP + 3-methyladenine (An autophagy inhibitor, 3-MA) groups. The control group did not receive any treatment. The EAP + saline group and the EAP + 3-MA group received intraperitoneal injections of saline and 3-MA, respectively, starting 1 week after the pulp was exposed. Specimens were collected for microcomputed tomography (micro-CT) scanning, histological processing, and immunostaining to examine the expression of light chain 3 beta (LC3B), RANK, RANKL, and OPG. Data were analysed using one-way analysis of variance (p < .05). Micro-CT showed greater bone loss in the EAP + 3-MA group than in the EAP + saline group, indicated by an elevated trabecular space (Tb.Sp) (p < .05). Inflammatory cell infiltration was observed in the EAP + saline and EAP + 3-MA groups. Compared with EAP + saline group, the EAP + 3-MA group showed weaker expression of LC3B (p < .01) and OPG (p < .05), more intense expression of RANK (p < .01) and RANKL (p < .01), and a higher RANKL/OPG ratio (p < .05). Autophagy may exert a protective effect against AP by regulating the RANKL/RANK/OPG axis, thereby inhibiting excessive bone loss.

Role of OPG/RANKL/RANK/TLR4 signaling pathway in sepsis-associated acute kidney injury

BackgroundSepsis-associated acute kidney injury (SA-AKI) has high mortality rates. The osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of nuclear factor-κB (RANK)/Toll-like receptor 4 (TLR4) pathway and its potential role in SA-AKI pathogenesis remain to be fully understood. Herein, we addressed this issue using mouse models.MethodsAn SA-AKI mouse model was established using the cecal ligation and puncture method (CLP). Mice were grouped into sham, CLP model, CLP + recombinant RANKL, and CLP + anti-RANKL groups. Serum creatinine (Scr) and blood urea nitrogen (BUN) levels were measured to assess kidney function. ELISA was used to detect serum IL-1β, TNF-α, and IL-6 levels. Real-time quantitative PCR and Western blot were used to detect the mRNA and protein expression levels of OPG, RANKL, RANK, and TLR4 in kidney tissues. HE staining was performed to evaluate the pathological changes.ResultsThe CLP model group showed higher levels of Scr and BUN, indicating impaired kidney function in SA-AKI, compared to the sham group. Treatment with recombinant RANKL in the CLP + recombinant RANKL group reduced Scr and BUN levels, while anti-RANKL treatment in the CLP + anti-RANKL group elevated their levels. Moreover, the CLP model group had significantly increased IL-1β, TNF-α, and IL-6 than the sham group, indicating elevated inflammation in SA-AKI. The CLP + recombinant RANKL group demonstrated decreased cytokine levels, whereas the CLP + anti-RANKL group showed an increase. Additionally, the histopathological evaluation revealed distinct kidney tissue damage in the CLP model group. Recombinant RANKL treatment reduced this damage, while anti-RANKL treatment exacerbated it. Mechanically, the mRNA and protein expression of RANKL were significantly decreased, while those of OPG, RANK, and TLR4 were significantly increased in the CLP model group and the CLP + anti-RANKL group. Interestingly, treatment with recombinant RANKL reversed these changes, as evidenced by significantly increased RANKL but decreased OPG, RANK, and TLR4.ConclusionThe OPG/RANKL/RANK/TLR4 pathway is involved in SA-AKI pathogenesis. Recombinant RANKL treatment attenuates the inflammatory response and kidney tissue damage in SA-AKI, possibly via regulating this pathway. This pathway shows promise as a therapeutic target for SA-AKI.

IL-6 Inhibitor Tocilizumab Reduces Bone Resorption Around Implants with Bacterial Infection During Osseointegration: A Pilot Study in Rabbits.

To evaluate the effect of interleukin-6 (IL-6) inhibitor (tocilizumab) on bacterial infection-associated bone resorption around implants during osseointegration in rabbits. At total of 24 male, 9-monthold New Zealand white rabbits were included, and their two mandibular anterior teeth were extracted. Three months after extraction, 24 one-piece Dentium implants (Ø 2.5 mm, intraosseous length of 12 mm) were inserted in the anterior mandible, and the rabbits were divided into four groups (n = 6 per group). Different treatment methods were used in each group: blank control group (BC); only silk ligation (negative control [NC]); silk ligation and injection with minocycline hydrochloride ointment (positive control [PC]); and silk ligation and injection with tocilizumab at 8 mg/kg via the auricle vein (experimental [EP]). Eight weeks later, the animals were sacrificed, and samples were collected and then analyzed using microcomputed tomography (microCT) scanning, immunohistochemical analysis, and histologic analysis. From the microCT measurement, the ratio of the bone volume to the total volume (BV/TV) in the EP group was 67.00% ± 2.72%, which was higher than that in the other three groups (58.85% ± 2.43% in the BC group, 55.72% ± 2.48% in the PC group, and 36.52% ± 3.02% in the NC group). From immunohistochemical analysis, the expression of IL-6 was found to be higher in the NC group than in the BC, PC, and EP groups, but there was no statistical difference between these three groups. Furthermore, the RANKL (receptor activator of nuclear factor-κB ligand) expression was the lowest in the EP group, followed by the BC group, the PC group, and the NC group, which had the highest expression; there was no difference between the NC and PC groups. Upon histologic analysis, significant new bone was found on the implant surfaces in the EP group, sparse and less new bone could be seen in the BC and PC groups, and the most serious bone resorption occurred in the NC group. Tocilizumab, an inhibitor of IL-6, has a certain effect in preventing bone loss around implants caused by bacterial infection during the osseointegration period.

Flavonoid gossypetin protects alveolar bone and limits inflammation in ligature-induced periodontitis in mice.

Bacterial-induced inflammation instigates the destruction of hard and soft tissues surrounding teeth in periodontitis. In severe cases, the increased number and activity of osteoclasts induces the resorption of alveolar bones, ultimately leading to tooth loss. Because of their diverse chemical structures and bioactivities, natural compounds are often suggested to treat a wide variety of diseases, including inflammatory disorders. In the present study, we demonstrated an inhibitory effect of gossypetin, a hexahydroxy flavone, on osteoclast differentiation and bone resorption using in vitro culture of osteoclasts from mouse bone marrow macrophage (BMM) precursors and in vivo model of ligature-induced periodontitis in mice. Gossypetin significantly reduced the differentiation of osteoclasts from mouse BMM precursors in the presence of the receptor activator of nuclear factor κB ligand (RANKL). In vitro, gossypetin inhibited critical signaling events downstream of RANKL including the auto-amplification of nuclear factor of activated T-cells, cytoplasmic 1, Ca2+ oscillations, and the generation of reactive oxygen species. In a mouse ligature-induced periodontitis model, the administration of gossypetin significantly reduced osteoclastogenesis and alveolar bone resorption. Furthermore, gossypetin prevented the ligature-induced increase in macrophages and T cells and reduced the production of tumor necrosis factor-α and interleukin-6. Taken together, these results show anti-osteoclastogenic and anti-inflammatory effects of gossypetin, suggesting the potential use of this natural compound in periodontitis.

Combined application of mesenchymal stem cells and different glucocorticoid dosing alleviates osteoporosis in SLE murine models.

Bone mesenchymal stem cells (BMSCs) have been tentatively applied in the treatment of glucocorticoid-induced osteoporosis (GIOP) and systemic lupus erythematosus (SLE). However, the effects of BMSCs on osteoporosis within the context of glucocorticoid (GC) application in SLE remain unclear. Our aim was to explore the roles of BMSCs and different doses of GC interventions on osteoporosis in SLE murine models. MRL/MpJ-Faslpr mice were divided into eight groups with BMSC treatment and different dose of GC intervention. Three-dimensional imaging analysis and hematoxylin and eosin (H&E) staining were performed to observe morphological changes. The concentrations of osteoprotegerin (OPG) and receptor activator of nuclear factor κB ligand (RANKL) in serum were measured by enzyme-linked immunosorbent assay (ELISA). The subpopulation of B cells and T cells in bone marrows and spleens were analyzed by flow cytometry. Serum cytokines and chemokines were assessed using Luminex magnetic bead technology. BMSCs ameliorated osteoporosis in murine SLE models by enhancing bone mass, improving bone structure, and promoting bone formation through increased bone mineral content and optimization of trabecular morphology. BMSC and GC treatments reduced the number of B cells in bone marrows, but the effect was not significant in spleens. BMSCs significantly promoted the expression of IL-10 while reducing IL-18. Moreover, BMSCs exert immunomodulatory effects by reducing Th17 expression and rectifying the Th17/Treg imbalance. BMSCs effectively alleviate osteoporosis induced by SLE itself, as well as osteoporosis resulting from SLE combined with various doses of GC therapy. The therapeutic effects of BMSCs appear to be mediated by their influence on bone marrow B cells, T cell subsets, and associated cytokines. High-dose GC treatment exerts a potent anti-inflammatory effect but may hinder the immunotherapeutic potential of BMSCs. Our research may offer valuable guidance to clinicians regarding the use of BMSC treatment in SLE and provide insights into the judicious use of GCs in clinical practice.

Cedrol alleviates postmenopausal osteoporosis in rats through inhibiting the activation of the NF-κB signaling pathway.

Pharmacological studies have shown that Cedrol (CE) exhibits extensive biological activities, including anti-inflammatory and analgesic. Moreover, it can inhibit the NF-κB pathway and the expression of various associated proteins. This study aimed to investigate the role of CE in postmenopausal osteoporosis. The results showed that intragastric administration of CE (10 and 20mg/kg) significantly improved the bone microstructure damage and increased bone mineral density, trabecular bone volume, and bone trabecular thickness in ovariectomized (OVX) rats (p < 0.05). CE treatment additionally made a well-organized arrangement of bone trabeculae and improved its thickness and density. Compared with the OVX group, the levels of tartrate-resistant acid phosphatase from 5b and C-terminal telopeptide of type I collagen were significantly reduced by 42.75% and 49.27% in the OVX + CE rats (p < 0.05). TRAP staining visually showed that the number of osteoclasts in the femur tissue of CE-treated rats was less than that of the OVX group. The expressions of nuclear factor of activated T-cells, cytoplasmic 1, acid phosphatase 5, and cathepsin K in OVX + CE rats were significantly decreased by 51.61%, 46.07%, and 50.34% compared to the OVX group (p < 0.01). In addition, CE intervention effectively reduced the phosphorylation levels of P65 and IκBα and inhibited the NF-κB signaling pathway. Meanwhile, CE diminished the number of multinucleated osteoclasts induced by receptor activator for nuclear factor-κB ligand and hindered cell fusion as well as nuclear translocation of osteoclast precursor cells P65. In conclusion, CE inhibits osteoclastogenesis by suppressing the activation of the NF-κB signaling pathway, thereby alleviating postmenopausal osteoporosis.

#1948 Transcriptome analysis of the effect of roxadustat on osteoclasts

Abstract Background and Aims In recent years, hypoxia-inducing factor prolyl hydroxylase inhibitors (HIF-PHIs) have been widely used in the treatment of renal anemia, bringing a revolutionary breakthrough in the treatment of anemia in CKD patients. However, HIF-PHIs acts on a variety of cells and regulates the expression of multiple target genes. Some studies have reported that HIF-PHIs plays an important role in regulating bone metabolism and promoting the differentiation and calcification of osteoblasts, but its influence on osteoclasts remains controversial. This study intends to explore the effect of roxadustat, a representative drug of HIF-PHIs, on osteoclasts. Method Bone marrow mononuclear cells (BMMCs) from 6-8 weeks old male C57BL/6 wild mice were extracted and induced to differentiate into osteoclasts using macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL). Meanwhile, lipopolysaccharide (LPS) was used to simulate the inflammatory environment in CKD patients. According to the experimental group, different concentrations of roxadustat (0 μM, 2.5 μM, 5 μM, 10μM) were added simultaneously. When osteoclast induction reached day 6, mRNA was extracted for transcriptome sequencing and bioinformatics analysis. Results As shown in Table 1, different concentrations of roxadustat were given to primary bone marrow monocytes under both conditions, and there were 3 biological replicates for each sample. The reproducibility scatter plot showed that the data in each group had good repeatability (Fig. 1), and the heat map for basic difference analysis of each sample was shown in Fig. 2. The trend analysis results of the two groups were shown in Fig. 3. BMMCs group and LPS stimulated group showed two upward trends, respectively. KEGG enrichment analysis of these two upward trends showed that HIF-1, MAPK, PI3K-Akt, NF-κB and osteoclast differentiation pathways were significantly enriched in both groups. It is suggested that roxadustat can promote osteoclast differentiation and increase inflammatory response with the increase of roxadustat concentration. The enrichment analysis of the two groups showed that there was no significant enrichment pathway. Conclusion We explored the differentiation of osteoclasts under normal conditions and osteoclast differentiation under simulated inflammation in CKD patients respectively. Transcriptomic analysis results showed that HIF-1, MAPK, PI3K-Akt, NF-κB and osteoclast differentiation pathways were significantly enriched with the increase of roxadustat concentration. It is suggested that the use of roxadustat may promote bone destruction and increase the risk of inflammatory response.

Gallein increases the fibroblast growth factor 2-elicited osteoprotegerin synthesis in osteoblasts

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

MiRNA Is Involved in the Pathogenesis of Multiple Diseases by Targeting Osteoprotegerin

As a member of the tumor necrosis factor receptor family, osteoprotegerin (OPG) is highly expressed in adults in the lung, heart, kidney, liver, spleen, thymus, prostate, ovary, small intestines, thyroid gland, lymph nodes, trachea, adrenal gland, the testis, and bone marrow. Together with the receptor activator of nuclear factor-κB (RANK) and the receptor activator of nuclear factor-κB ligand (RANKL), it forms the RANK/RANKL/OPG pathway, which plays an important role in the molecular mechanism of the development of various diseases. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs performing regulatory functions in eukaryotes, with a size of about 20-25 nucleotides. miRNA genes are transcribed into primary transcripts by RNA polymerase, bind to RNA-induced silencing complexes, identify target mRNAs through complementary base pairing, with a single miRNA being capable of targeting hundreds of mRNAs, and influence the expression of many genes through pathways involved in functional interactions. In recent years, a large number of studies have been done to explore the mechanism of action of miRNA in diseases through miRNA isolation, miRNA quantification, miRNA spectrum analysis, miRNA target detection, in vitro and in vivo regulation of miRNA levels, and other technologies. It was found that miRNA can play a key role in the pathogenesis of osteoporosis, rheumatoid arthritis, and other diseases by targeting OPG. The purpose of this review is to explore the interaction between miRNA and OPG in various diseases, and to propose new ideas for studying the mechanism of action of OPG in diseases.

Characterization of a spontaneous osteopetrosis model using RANKL-dysfunctional mice

Tumor necrosis factor superfamily member 11 (TNFSF11), or receptor activator of nuclear factor-κB ligand (RANKL), is a crucial osteoclast-stimulating factor binding to RANK on osteoclast membranes. Mouse models are powerful tools for understanding the genetic mechanisms of related diseases. Here, we examined the utility of Tnfsf11 mutation in mice for understanding the mechanisms of bone remodeling and dysmorphology. The Tnfsf11gum mouse, discovered in 2011 at Jackson Laboratory, was used to study the genetic landscape associated with TNFSF11 inactivation in bone marrow tissues. Tnfsf11gum/+ and Tnfsf11+/+ mice were subjected to Micro-CT observation, ELISA analysis, histological evaluation, and massively-parallel mRNA sequencing (RNA-Seq) analysis. Tnfsf11gum/+ mice exhibited severe osteopetrotic changes in the bone marrow cavity, along with significantly lower serum RANKL levels and a reduced number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the bone marrow compared to those in Tnfsf11+/+ mice. However, tooth eruption between Tnfsf11gum/+ and Tnfsf11+/+ mice did not differ. Furthermore, genes involved in osteoblast proliferation and differentiation, including Gli1, Slc35b2, Lrrc17, and Junb were differentially expressed. Heterozygous mutation of TNFSF11 was also associated with a slightly increased expression of genes involved in osteoclast proliferation and differentiation, including Tcirg1, Junb, Anxa2, and Atp6ap1. Overall, we demonstrate that single gene mutations in Tnfsf11 cause bone resorption instability without significantly altering the genes related to osteoblast and osteoclast activity in the bone marrow cavity, thus establishing an optimal resource as an experimental animal model for bone resorption in bone biology research.

Antimicrobial and anti-inflammatory effects of BenTooth: A natural product blend of burdock root, persimmon leaf extracts, and quercetin on periodontal disease

Periodontal disease represents a condition that exhibits substantial global morbidity, and is characterized by the infection and inflammation of the periodontal tissue effectuated by bacterial pathogens. The present study aimed at evaluating the therapeutic efficacy of BenTooth, an edible natural product mixture comprising burdock root extract, persimmon leaf extract and quercetin, against periodontitis both in vitro and in vivo. BenTooth was examined for antimicrobial properties and its impact on cellular responses related to inflammation and bone resorption. Its effects were also assessed in a rat model of ligature-induced periodontitis. BenTooth demonstrated potent antimicrobial activity against P. gingivalis and S. mutans. In RAW264.7 cells, it notably diminished the expression of inducible nitric oxide synthase and cyclooxygenase-2, as well as reduced interleukin-6 and tumor necrosis factor-α levels triggered by P. gingivalis-derived lipopolysaccharide. Furthermore, BenTooth inhibited osteoclastogenesis mediated by the receptor activator of nuclear factor κB ligand. In the rat model, BenTooth consumption mitigated the ligature-induced expansion in distance between the cementoenamel junction and the alveolar bone crest and bolstered the bone volume fraction. These results present BenTooth as a potential therapeutic candidate for the prevention and remediation of periodontal diseases.

Denosumab Induces Neoplastic Stromal Cell Apoptosis Via p62 Downregulation Dependent on Autophagy Pathway in Giant Cell Tumour of Bone.

As the only humanized monoclonal antibody against receptor activator of nuclear factor-κB ligand (RANKL) for giant cell tumour of bone (GCTB) therapy, denosumab has limited antitumour effect on neoplastic stromal cells. Nevertheless, its mechanism of action has not yet been clarified. A previous study has revealed that p62 may play an important role in the antitumour activity of denosumab. The study aimed to investigate if the mechanism by which denosumab inhibits GCTB neoplastic stromal cells growth is via p62 modulation and other related mechanisms. p62 expression before and after denosumab therapy was analysed by RT‒qPCR, western blot, ELISA, and immunohistochemical assays. Two primary neoplastic stromal cells were isolated from fresh GCTB tumour tissue (L cell) and metastatic tissue (M cell). Cell proliferation, migration, apoptosis, and autophagy were investigated in p62 knockdown neoplastic stromal cells transfected by short hairpin RNA lentivirus in vitro. Tumor growth was evaluated in the chick chorioallantoic membrane model in vivo. p62 expression was found to be downregulated following denosumab therapy. The patients with a decrease in p62 expression had lower recurrence-free survival rates. The proliferation of M cells was not inhibited by denosumab therapy, but it was restored by p62 knockdown. Moreover, p62 knockdown inhibited tumour growth in vivo. Denosumab induced M cell apoptosis and arrested the cell cycle at the G1/G0 transition and these effects were also enhanced by p62 knockdown. Autophagic flux assays revealed p62 modulation to be dependent on autophagy following denosumab incubation. Denosumab induced neoplastic stromal cells apoptosis via p62 downregulation dependent on autophagy pathway. The combination of p62 and RANKL knockdown might be a better strategy than RANKL knockdown alone for GCTB targeted therapy.

The Effectiveness of Denosumab in Middle Eastern Patients With Giant Cell Tumor of the Bone: A Single-Center, Retrospective Study.

Giant cell tumor of the bone (GCTB) is an aggressive benign tumor, which constitutes 5% of all primary bone tumors. Denosumab, a receptor activator of nuclear factor κB ligand monoclonal antibody, inhibits osteoclast-induced bone destruction and has demonstrated promising results in patients with GCTB. However, the long-term efficacy of the drug has not been extensively studied, especially in the Middle East. In this study, we retrospectively analyzed the five-year progression-free survival (PFS) in patients with GCTB at a single Saudi center. PFS was defined as the time from diagnosis until disease progression, relapse, or death. Events were censored after five years from diagnosis. Sixty-two patients with GCTB were included in the study. The median age at diagnosis was 31.16 years, and 38 (61.3%) patients were female. Twenty-nine patients (46.8%) received denosumab during the study period. The median duration of denosumab treatment was 5.06 months, and the median number of cycles was 6. The median PFS was not reached, and the five-year PFS rate was 60.3%. Age, gender, body mass index, performance status at presentation, and tumor location had no impact on five-year PFS. Denosumab treatment prolonged PFS; however, this was not statistically significant compared to non-denosumab patients (P= 0.603). Denosumab does not seem to provide superior long-term outcomes compared to surgery alone. Although our findings are generally consistent with other studies in the literature, larger long-term studies are needed to confirm our findings.

Isobavachin attenuates osteoclastogenesis and periodontitis-induced bone loss by inhibiting cellular iron accumulation and mitochondrial biogenesis

As bone-resorbing cells rich in mitochondria, osteoclasts require high iron uptake to promote mitochondrial biogenesis and maintain a high-energy metabolic state for active bone resorption. Given that abnormal osteoclast formation and activation leads to imbalanced bone remodeling and osteolytic bone loss, osteoclasts may be crucial targets for treating osteolytic diseases such as periodontitis. Isobavachin (IBA), a natural flavonoid compound, has been confirmed to be an inhibitor of receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs). However, its effects on periodontitis-induced bone loss and the potential mechanism of its anti-osteoclastogenesis effect remain unclear. Our study demonstrated that IBA suppressed RANKL-induced osteoclastogenesis in BMMs and RAW264.7 cells and inhibited osteoclast-mediated bone resorption in vitro. Transcriptomic analysis indicated that iron homeostasis and reactive oxygen species (ROS) metabolic process were enriched among the differentially expressed genes following IBA treatment. IBA exerted its anti-osteoclastogenesis effect by inhibiting iron accumulation in osteoclasts. Mechanistically, IBA attenuated iron accumulation in RANKL-induced osteoclasts by inhibiting the mitogen-activated protein kinase (MAPK) pathway to upregulate ferroportin1 (Fpn1) expression and promote Fpn1-mediated intracellular iron efflux. We also found that IBA inhibited mitochondrial biogenesis and function, and reduced RANKL-induced ROS generation in osteoclasts. Furthermore, IBA attenuated periodontitis-induced bone loss by reducing osteoclastogenesis in vivo. Overall, these results suggest that IBA may serve as a promising therapeutic strategy for bone diseases characterized by osteoclastic bone resorption.

Potato protein hydrolysate inhibits RANKL-induced osteoclast development by inhibiting osteoclastogenic genes via the NF-κB/MAPKs signaling pathways.

In recent times, there has been growing attention towards exploring the nutritional and functional aspects of potato protein, along with its diverse applications. In the present study, we examined the anti-osteoclast properties of potato protein hydrolysate (PP902) in vitro. Murine macrophages (RAW264.7) were differentiated into osteoclasts by receptor activator of nuclear factor-κB ligand (RANKL), and PP902 was examined for its inhibitory effect. Initially, treatment with PP902 was found to significantly prevent RANKL-induced morphological changes in macrophage cells, as determined by tartrate-resistant acid phosphatase (TRAP) staining analysis. This notion was further supported by F-actin analysis using a confocal microscope. Furthermore, PP902 treatment effectively and dose-dependently down-regulated the expression of RANKL-induced osteoclastogenic marker genes, including TRAP, CTR, RANK, NFATc1, OC-STAMP, and c-Fos. These inhibitory effects were associated with suppressing NF-κB transcriptional activation and subsequent reduced nuclear translocation. The decrease in NF-κB activity resulted from reduced activation of its upstream kinases, including I-κBα and IKKα. Moreover, PP902 significantly inhibited RANKL-induced p38MAPK and ERK1/2 activities. Nevertheless, PP902 treatment prevents RANKL-induced intracellular reactive oxygen species generation via increased HO-1 activity. The combined antioxidant and anti-inflammatory effects of PP902 resulted in significant suppression of osteoclastogenesis, suggesting its potential as an adjuvant therapy for osteoclast-related diseases.

Impact of the arginine silicate inositol complex on bone metabolism in broiler chickens with tibial dyschondroplasia caused by manganese deficiency

ABSTRACT 1. Tibial dyschondroplasia (TD) is a skeletal disorder in broilers that has financial implications, necessitating dietary modifications to reduce the prevalence of this disease. This study explored how arginine silicate inositol complex (ASI) supplementation affected tibial growth plate (TGP) and overall bone health in broilers with manganese (Mn) deficiency-induced TD. 2. A total of 240 broiler chicks were divided into four groups, each consisting of 60 birds (15 replicates of four broilers each) as follows: i) Control, with 60 mg Mn per kg of diet; ii) ASI, with 60 mg Mn and 1 g ASI per kg of diet; iii) TD, with 22 mg Mn per kg of diet, and iv) TD+ASI, with 22 mg Mn and 1 g ASI per kg of diet. 3. It was found that ASI supplementation increased tibial bone length in Mn-deficient TD broilers (p = 0.007). There was no Mn x ASI interaction for other bone morphometry variables (p > 0.05). However, both tibial bone mineral content and density were affected by Mn and ASI (p < 0.05). With ASI supplementation, serum bone-specific alkaline phosphatase and osteocalcin levels were elevated in the TD+ASI group compared to the TD group (p < 0.001). In the TD group, osteoprotegerin (OPG) levels in the TGP decreased compared to the control groups (p < 0.001). 4. In contrast, ASI supplementation in the TD broilers counteracted the decrease in OPG compared to TD broilers without ASI supplementation (p < 0.001). The Mn level and ASI supplementation significantly influenced the OPG/receptor activator of the nuclear factor-κB ligand ratio (p < 0.001). 5. In conclusion, the results demonstrated that inclusion of ASI in broiler diets could enhance bone formation variables by controlling OPG levels in the TGP, potentially serving as an effective method to decrease the occurrence of TD.

Silk sericin-based functional food for osteoporosis prevention and therapy

The development of new functional foods that can potentially reduce the risk of diseases, such as osteoporosis, has received increasing attention in recent years. Here we demonstrated that silk sericin-based functional food (SSBF) exerted preventive and therapeutic effects against bone loss. Sericin isolated at 70 °C for 60 min from the cocoon of Bombyx mori stimulated osteoblast differentiation by increasing osteoblastic gene expression while inhibiting receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation in vitro. Micro-computed tomography analysis revealed that pre- and post-oral administration of SSBF increased bone mass in ovariectomized mouse model in vivo. Furthermore, dynamic bone histomorphometry analysis revealed that SSBF enhanced osteoblast activity and suppressed bone resorption by reducing the number of osteoclasts. These findings indicated the potential role of SSBF in preventing and being a therapeutic candidate for osteoporosis.

Napyradiomycin B4 Suppresses RANKL-Induced Osteoclastogenesis and Prevents Alveolar Bone Destruction in Experimental Periodontitis.

The unique structure and beneficial biological properties of marine natural products have drawn interest in drug development. Here, we examined the therapeutic potential of napyradiomycin B4 isolated from marine-derived Streptomyces species for osteoclast-related skeletal diseases. Bone marrow-derived macrophages were treated with napyradiomycin B4 in an osteoclast-inducing medium, and osteoclast formation, osteoclast-specific gene expression, and nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) localization were evaluated using tartrate-resistant acid phosphatase staining, real-time PCR, and immunostaining, respectively. Phosphorylation levels of signaling proteins were assessed by immunoblot analysis to understand the molecular action of napyradiomycin B4. The in vivo efficacy of napyradiomycin B4 was examined under experimental periodontitis, and alveolar bone destruction was evaluated by microcomputed tomography (micro-CT) and histological analyses. Among the eight napyradiomycin derivatives screened, napyradiomycin B4 considerably inhibited osteoclastogenesis. Napyradiomycin B4 significantly suppressed the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation and disrupted the expression of NFATc1 and its target genes. Mitogen-activated extracellular signal-regulated kinase (MEK) and extracellular signal-regulated kinase (ERK) phosphorylation levels were reduced by napyradiomycin B4 in response to RANKL. Under in vivo experimental periodontitis, napyradiomycin B4 significantly attenuated osteoclast formation and decreased the distance between the cementoenamel junction and alveolar bone crest. Our findings demonstrate the antiosteoclastogenic activity of napyradiomycin B4 by inhibiting the RANKL-induced MEK-ERK signaling pathway and its protective effect on alveolar bone destruction.