Decreased Bone Resorption Research Articles

Evaluation of Osteogenic Phenotype in Postmenopausal Women receiving Anabolic and Antiresorptive Osteoporosis Therapies.

Ageing of the general population has led to a significant increase in the prevalence of osteoporosis over the past decades. While there are effective pharmacological agents that increase bone formation, decrease bone resorption and decrease fracture risk, they do not uniformly cure osteoporosis. This has prompted investigations to examine whether combination therapy with these agents can result in an additive benefit. Since concomitant therapy with denosumab and teriparatide has shown promise in this respect, investigations were undertaken to explore whether the changes in osteogenic phenotype could provide insight into the cellular and molecular mechanism of this effect. Investigations were performed in postmenopausal women receiving denosumab, teriparatide or both for 3 months. Histomorphometric parameters were the primary outcome, while exploratory studies examined RNA expression in bone biopsies as well as in sorted and cultured bone marrow stromal cells. Osteogenic colony forming units of bone marrow stromal cells were also evaluated. The studies demonstrated that combination therapy results in an increase in osteoprogenitors, evidenced by an increase in osteoblastic colony forming units. This was associated with an increased in bone marrow stromal cell expression of LGR6 (Leucine Rich Repeat Containing G Protein-Coupled Receptor 6), a stem cell marker and activator of the canonical Wnt signaling pathway. These data suggest that enhancement of canonical Wnt signaling contributes to the increase in osteoprogenitors and consequently an increase in bone density in postmenopausal women receiving combination therapy for osteoporosis.

12466 Dual Bone Defect In Patients With Charge Syndrome

Abstract Disclosure: N. Reyes: None. R.J. Santen: None. S.M. Jan De Beur: None. R. Balasubramanian: None. Chromodomain Helicase DNA-binding protein 7 (Chd7) is an ATP-dependent chromatin modifier that mediates nucleosome remodeling. Chd7 mutations result in CHARGE syndrome characterized by coloboma, heart defects, choanal atresia, growth/developmental delay, ear abnormalities, and hypogonadotropic hypogonadism/Kallmann syndrome (IHH/KS). Testosterone has direct and indirect effects (through estrogen), to increase bone formation and decrease bone resorption. Untreated hypogonadism is associated with decreased bone density and fractures. Reports of fractures and low bone density in CHARGE syndrome patients have been attributed to sex hormone deficiency associated with hypogonadism. However, recent data from a Chd7 mouse knockout model suggests an intrinsic Chd7-related bone defect. In wild-type mice, Chd7 promotes osteogenic differentiation of mesenchymal stem cells. Chd7 deficient mice show markedly reduced osteoblasts. Thus, we propose, a dual bone defect in CHARGE syndrome resulting from impaired osteogenesis from CHD7 and sex steroid deficiency; and increased bone resorption due to lack of sex steroids. Here we present two individuals with CHARGE syndrome with markedly low bone density and literature review supporting the dual bone defect concept. Case 1 is a 30 yo male with a pathogenic CHD7 mutation, multiple congenital anomalies of CHARGE syndrome and hypogonadotropic hypogonadism. He had multiple fractures in his teen age years and a bone density Z score of -5.2 at the lumbar spine and -3.3 at the left femoral neck. Because he did not tolerate androgen therapy, a single infusion of zoledronic acid was administered with no further fractures for eight years following infusion. Case 2 is a male evaluated for IHH/KS and ultimately diagnosed with CHARGE Syndrome based on a pathogenic CHD7 mutation. Despite 7 years of testosterone therapy with full virilization, his bone density remained low at Z-score of -1.9 at the spine and -2.6 at the total hip. Results: Both patients had low bone density, one while untreated and the other after full virilization with exogenous androgens. This raises the question whether the bone defects were related to the CHD7 mutation, to androgen deficiency or both. To answer this question, a literature search examined bone density data in untreated patients with CHARGE syndrome versus IHH/KS. We found substantially lower bone density in untreated CHARGE patients Z score -3.46±0.36 (SEM) (n=13) versus IHH/KS -2.16 ±1.0 (n=4). Furthermore, the bone density was also lower in treated CHARGE patients -2.46±0.28 (n=6) versus IHH/KS -0.94±0.26 (n=140). Conclusion: These data, taken together, provide direct human evidence to support the concept that the CHD7-related CHARGE syndrome patients have a defect in both osteogenesis as well as an effect of sex steroid deficiency on bone. Presentation: 6/3/2024

Osteogenic effect of alogliptin in chemical-induced bone loss: a tri-modal in silico, in vitro, and in vivo analysis.

To investigate the effects of Alogliptin in chemical-induced post-menopausal osteoporosis. The binding affinity of alogliptin with osteogenic proteins was analysed in silico. The effect of alogliptin on osteogenic proteins and mineralization of osteoblastic cells was evaluated in UMR-106 cells. Further, in vivo anti-osteoporotic activity of alogliptin was evaluated in postmenopausal osteoporosis. Various bone turnover markers were assayed in serum. This followed the analysis of microarchitecture of bone, histology, and immunohistochemistry (IHC) of bone tissue. Docking scores showed that alogliptin has binding affinity for bone alkaline phosphatase (BALP), osteocalcin, and bone morphogenic protein (BMP-2). Alogliptin also enhanced mineralization of osteoblast cells, evidenced with increased ALP, osteocalcin, and BMP-2. Animal studies revealed significant elevation of bone formation markers, bone ALP, osteocalcin and BMP-2, and decreased bone resorption markers, receptor activator of NF-κβ (RANKL), cathepsin K (CTSK), tartrate resistant acid phosphatase (TRAcP5b) in VCD-induced post-menopausal osteoporosis. Micro computed tomography (μCT) analysis and histology of femur bone and lumbar vertebrae demonstrated decrease in trabecular separation and improved bone density. IHC of femur showed reduced DPP4 enzyme. Alogliptin increased mineralization in osteoblast cells. It had beneficial effects also altered bone turnover markers, repaired the trabecular microstructure, improved bone mineral density, and exhibited bone forming capacity targeting DPP-4 enzyme in postmenopausal osteoporosis.

Effectiveness of Short-Term Use Denosumab and Risedronate Using β-Crosslaps and Histopathology as a Parameter in Osteoporotic Rat Model

Osteoporosis is a condition of decreased bone mass density. Pharmacological management uses drugs that decrease bone resorption or increase bone formation. The most commonly used drugs are bisphosphonates. Risedronate is one of these bisphosphonates. It inhibits osteoclasts, resulting in osteoclast apoptosis. Denosumab is a human monoclonal antibody that inhibits receptor activator kappa-B ligand, inhibiting osteoclast activation. Both drugs are widely used. Research on the efficacy of these two mechanisms has yet to obtain conclusive results. β-cross-laps is a parameter that can be used to evaluate the effectiveness of therapy through monitoring the bone resorption process. This experimental study used female rats >9 weeks old and was conducted at the Pharmacology and Therapeutic Laboratory, Universitas Padjadjaran Bandung, Indonesia, from June to September 2021. This study utilized a simple random sampling to allocate 24 experimental animals into three groups: control, risedronate, and denosumab. β-Crosslaps expression values before ovariectomy, post ovariectomy before receiving medication, and post ovariectomy and receiving medication was recorded and statistically analyzed using the SPSS version 24.0. The analysis of 24 samples revealed a statistically significant decrease in the median value of β-Crosslaps after ovariectomy in the denosumab group (p=0.036) when compared to the control group, whereas the decrease in the risedronate group was not significant (p=0.687). Administration of denosumab in rat models is more effective in reducing bone resorption compared to risedronate.

The crucial role of beta-catenin in the osteoprotective effect of semaglutide in an ovariectomized rat model of osteoporosis.

Postmenopausal osteoporosis is a common chronic medical illness resulting from an imbalance between bone resorption and bone formation along with microarchitecture degeneration attributed to estrogen deficiency and often accompanied by other medical conditions such as weight gain, depression, and insomnia. Semaglutide (SEM) is a recently introduced GLP-1 receptor agonist (GLP-1RA) for the treatment of obesity and type 2 diabetes mellitus by mitigating insulin resistance. It has been discovered that the beneficial effects of GLP-1 are associated with alterations in lipolysis, adipogenesis, and anti-inflammatory processes. GLP-1 analogs transmit signals directly to adipose tissue. Mesenchymal stem cells (MSCs) are multidisciplinary cells that originate from bone marrow, migrate to injury sites, and promote bone regeneration. MSCs can differentiate into osteoblasts, adipose cells, and cartilage cells. Our aim is to investigate the role of semaglutide on bone formation and the Wnt signaling pathway. Osteoporosis was induced in female rats by ovariectomy, and the ovariectomized rats were treated with alendronate as standard treatment with a dose of 3mg/kg orally and semaglutide with two doses (150 mcg/kg and 300 mcg/kg) S.C. for 10 successive weeks. Semaglutide ameliorates bone detrimental changes induced by ovariectomy. It improves bone microarchitecture and preserves bone mineral content. Semaglutide ameliorates ovariectomy-induced osteoporosis and increases the expression of β-catenin, leading to increased bone formation and halted receptor activator of nuclear factor kappa-Β ligand (RANKL's) activation. Semaglutide can be used as a potential prophylactic and therapeutic drug against osteoporosis, possibly by activating Wnt signaling and decreasing bone resorption.

Hydroxychloroquine and a low antiresorptive activity bisphosphonate conjugate prevent and reverse ovariectomy-induced bone loss in mice through dual antiresorptive and anabolic effects

Osteoporosis remains incurable. The most widely used antiresorptive agents, bisphosphonates (BPs), also inhibit bone formation, while the anabolic agent, teriparatide, does not inhibit bone resorption, and thus they have limited efficacy in preventing osteoporotic fractures and cause some side effects. Thus, there is an unmet need to develop dual antiresorptive and anabolic agents to prevent and treat osteoporosis. Hydroxychloroquine (HCQ), which is used to treat rheumatoid arthritis, prevents the lysosomal degradation of TNF receptor-associated factor 3 (TRAF3), an NF-κB adaptor protein that limits bone resorption and maintains bone formation. We attempted to covalently link HCQ to a hydroxyalklyl BP (HABP) with anticipated low antiresorptive activity, to target delivery of HCQ to bone to test if this targeting increases its efficacy to prevent TRAF3 degradation in the bone microenvironment and thus reduce bone resorption and increase bone formation, while reducing its systemic side effects. Unexpectedly, HABP-HCQ was found to exist as a salt in aqueous solution, composed of a protonated HCQ cation and a deprotonated HABP anion. Nevertheless, it inhibited osteoclastogenesis, stimulated osteoblast differentiation, and increased TRAF3 protein levels in vitro. HABP-HCQ significantly inhibited both osteoclast formation and bone marrow fibrosis in mice given multiple daily PTH injections. In contrast, HCQ inhibited marrow fibrosis, but not osteoclast formation, while the HABP alone inhibited osteoclast formation, but not fibrosis, in the mice. HABP-HCQ, but not HCQ, prevented trabecular bone loss following ovariectomy in mice and, importantly, increased bone volume in ovariectomized mice with established bone loss because HABP-HCQ increased bone formation and decreased bone resorption parameters simultaneously. In contrast, HCQ increased bone formation, but did not decrease bone resorption parameters, while HABP also restored the bone lost in ovariectomized mice, but it inhibited parameters of both bone resorption and formation. Our findings suggest that the combination of HABP and HCQ could have dual antiresorptive and anabolic effects to prevent and treat osteoporosis.

Reconstruction of remodeling units reveals positive effects after 2 and 12months of romosozumab treatment.

Romosozumab treatment results in a transient early increase in bone formation and sustained decrease in bone resorption. Histomorphometric analyses revealed that the primary bone-forming effect of romosozumab is a transient early stimulation of modeling-based bone formation on cancellous and endocortical surfaces. Furthermore, preclinical studies have demonstrated that romosozumab may affect changes in the remodeling unit, resulting in positive bone balance. To further investigate the effects of romosozumab on bone balance, mo 12 (M12) and mo 2 (M2) (to analyze early effects) unpaired bone biopsies from the FRAME clinical trial were analyzed using remodeling site reconstruction to assess whether positive changes in bone balance on cancellous/endocortical surfaces may contribute to the progressive improvement in bone mass/structure and reduced fracture risk in osteoporotic women at high fracture risk. At M12, bone balance was higher with romosozumab vs placebo on cancellous (+6.1 vs +1.5μm; P =.012) and endocortical (+5.2 vs -1.7μm; P =.02) surfaces; higher bone balance was due to lower final erosion depth (40.7 vs 43.7μm; P =.05) on cancellous surfaces and higher completed wall thickness (50.8 vs 47.5μm; P =.037) on endocortical surfaces. At M2, the final erosion depth was lower on the endocortical surfaces (42.7 vs 50.7μm; P =.021) and was slightly lower on the cancellous surfaces (38.5 vs 44.6μm; P =.11) with romosozumab vs placebo. Sector analysis of early endocortical formative sites revealed higher osteoid thickness (29.9 vs 19.2μm; P = .005) and mineralized wall thickness (18.3 vs 11.9μm; P =.004) with romosozumab vs placebo. These evolving bone packets may reflect the early stimulation of bone formation that contributes to the increase in completed wall thickness at M12. These data suggest that romosozumab induces a positive bone balance due to its effects on bone resorption and formation at the level of the remodeling unit, contributing to the positive effects on bone mass, structure, and fracture risk.

Evaluation of romosozumab's effects on bone marrow adiposity in postmenopausal osteoporotic women: results from the FRAME bone biopsy sub-study.

Romosozumab, a humanized monoclonal antibody that binds and inhibits sclerostin, produces a marked increase in bone formation with a concomitant decreased bone resorption. This transient rise in bone formation in the first 2 months of treatment is mainly due to an increased modeling-based bone formation. This requires the recruitment and differentiation of osteoblasts, one possibility being a preferential switch in commitment of precursors to osteoblasts over adipocytes. The purpose of this study was to analyze the marrow adiposity in transiliac bone biopsies at months 2 or 12 from the FRAME biopsy sub-study in patients receiving romosozumab or placebo. The total adipocyte area, number, and density were measured on the total cancellous bone area. The size and shape at the individual adipocyte level were assessed including the mean adipocyte area, perimeter, min and max diameters, and aspect ratio. No significant difference in total adipocyte area, number, or density between placebo and romosozumab groups was observed at months 2 and 12, and no difference was observed between 2 and 12months. After 2 or 12months, romosozumab did not modify the size or shape of the adipocytes. No relationship between the adipocyte parameters and the dynamic parameters of bone formation could be evidenced. In conclusion, based on the analysis of a small number of biopsies, no effect of romosozumab on bone marrow adiposity of iliac crest was identified after 2 and 12months suggesting that the modeling-based formation observed at month 2 was not due to a preferential commitment of the precursor to osteoblast over adipocyte cell lines but may result from a reactivation of bone lining cells and from a progenitor pool independent of the marrow adipocyte population.

Effects of Chitosan as a Novel Obturation Material for Pulpectomized Teeth on Periapical Inflammation, Periodontal Ligament Widening, and Hard Tissue Resorption: A Preliminary Exploratory Study on Dogs.

Objectives: This preliminary animal study was conducted to assess the effects of chitosan as a novel obturation material for pulpectomized teeth on periapical inflammation, periodontal ligament (PDL) widening, and hard tissue resorption. Materials and Methods: Forty premolar root canals in two mature dogs were obturated with zinc oxide eugenol (ZOE) and an experimental 3% chitosan paste (n=20 in each group). The teeth were then restored with amalgam. After 28 days, the dogs were sacrificed, and histopathological assessment was performed. The amount of resorbed obturation material, degree of inflammatory response, degree of PDL widening, and the number of bone/cementum/dentin resorption defects were recorded under ×40 and ×200 magnifications. Data were analyzed using the Mann-Whitney U test, one-sample Wilcoxon signed-rank test, and Fisher's exact test (α=0.05). Results: Bone, cementum, and dentin resorption were seen in 6, 10, and 1 chitosan-obturated canals and 14, 15, and 0 ZOE-obturated canals, respectively. Only the bone resorption defects were significantly fewer in the chitosan group (P=0.026). Mild, moderate, and severe inflammation were observed in 17, 3, and 0 chitosan-obturated canals, and 7, 9, and 4 ZOE-filled canals, respectively (P=0.004). Mild, moderate, and severe PDL widening were seen around 15, 5, and 0 chitosan-filled canals and 7, 12, and 1 ZOE-filled canals, respectively (P=0.025). Conclusion: The 3% chitosan was superior to ZOE in terms of causing less inflammation and PDL widening. It also decreased bone resorption and acted similar to ZOE in terms of dentin and cementum resorption.

Toll-like receptor 4 deficiency affects the balance of osteoclastogenesis and osteoblastogenesis in periodontitis

Toll-like receptor 4 (TLR4) acts as a double-edged sword in the occurrence and development of periodontitis. While the activation of TLR4 in macrophages aids in clearing local pathogens, it can also disrupt innate immune responses, upsetting microecological balance and accelerating the destruction of periodontal bone tissues. To date, the effects of TLR4 on osteogenesis and osteoclastogenesis in periodontitis have not been comprehensively studied.In this study, we investigated the development of periodontitis in the Tlr4−/− mice by ligating their second molars with silk threads. Compared to wild-type (WT) mice, Tlr4−/− mice demonstrated increased resistance to periodontitis-associated bone destruction, as evidenced by decreased bone resorption and enhanced bone regeneration. Mechanistically, the deletion of Tlr4 not only inhibited osteoclast formation by reducing the expression of NFATc1, CTSK and TRAP, but also enhanced osteogenic abilities through increased expression of OCN, OPN and RUNX2. In conclusion, TLR4 tips the balance of osteoclastogenesis and osteogenesis, thereby promoting periodontal bone destruction in periodontitis.

Real-world effects, safety, and predictors of the effectiveness of romosozumab in primary and secondary osteoporosis: An observational study

Romosozumab is an anti-sclerostin antibody that increases bone formation and decreases bone resorption. It became available for patients at high risk of osteoporotic fractures in Japan in 2019. The aim of this study was to clarify the clinical effects, safety, and predictors of the effectiveness of 12 months of romosozumab therapy. The study had an observational pre-post design and included 460 patients. Romosozumab was administered at a dose of 210 mg subcutaneously every 4 weeks for 12 months. The incidence of new fractures, safety, and changes in bone mineral density (BMD) and bone turnover markers were recorded. New fractures occurred in 11 cases (3.0 %). Nine patients (2.0 %) experienced cardiovascular events, which were fatal in 3 (0.65 %). Percent changes in BMD at the spine and total hip at 12 months from baseline were +7.7 % and +1.8 %, respectively. Romosozumab had better effects in patients with good renal function, low spine BMD, and high TRACP-5b at baseline and low TRACP-5b or high P1NP after 1 month of treatment. The percent change in spine BMD at 12 months was significantly lower in patients transitioning from denosumab than in those not previously treated with other anti-osteoporosis agents. Romosozumab is considered to be relatively safe in patients with primary osteoporosis compared to those with secondary osteoporosis. Romosozumab resulted in larger increases in spine BMD in patients with primary osteoporosis who were not previously treated with other anti-osteoporosis therapies and those with low spine BMD at the start of treatment.

#2223 Glycosylated hemoglobin levels and bone phenotype in patients with end-stage kidney disease

Abstract Background and Aims Diabetes mellitus is common as both cause and comorbidity of patients with chronic kidney disease (CKD). Both diabetes and CKD are states of increased fracture risk compared to healthy controls, with multiple potential contributing mechanisms. In type 2 diabetes, hyperglycemia contributes to the accumulation of advanced glycation end-products and osteocyte dysfunction, and it may play a pathogenic role in bone fragility. In this study, we wanted to examine the association between glycemic status and bone phenotype in patients with end-stage kidney disease (ESKD). Method This is a cross-sectional cohort study of 626 patients with CKD G5-5D referred for kidney transplantation between April 2006 and December 2013. Patients with type 1 diabetes were excluded. Patients were divided into quartiles based on HbA1c. Laboratory parameters of bone mineral metabolism (including biointact parathyroid hormone (PTH), fibroblast growth factor-23 (FGF23), and sclerostin), and bone turnover markers (bone alkaline phosphatase (BALP), trimeric pro-collagen type 1 N-terminal pro-peptide (intact P1NP), and tartrate-resistant acid phosphatase 5b (TRAP5b)) were measured. Bone mineral density (BMD) assessed by dual-energy X-ray absorptiometry (DEXA) (n = 537), bone histomorphometry (n = 180), and bone trabecular score (TBS) (n = 192) were available for subsets of patients. Results The median HbA1c were 4.8% in Q1, 5.1% in Q2, 5.4% in Q3, and 5.9% in Q4. Age and BMI differed across quartiles, with the highest age and BMI in Q4. Differences in bone turnover markers were found, with decreasing bone formation (BALP and intact P1NP) and decreasing bone resorption (TRAP5b) with ascending quartiles (Fig. 1). No differences across quartiles were found for FGF23, or circulating levels of sclerostin; however a weak, positive correlation between HbA1c and sclerostin was noted (rho = 0.08, p = 0.047). Overall, BMD at lumbar spine, femoral neck, and total hip increased across quartiles, the highest values in Q4 (Table 1). There were no differen in bone histomorphometry or TBS based on glycemic status. Conclusion Chronic hyperglycemia associates with suppressed bone turnover and higher BMD in patients with ESKD, even in non-diabetics. Potential mechanisms linking glucose metabolism to bone quantity and quality requires further investigation.

Mechanical protein polycystin-1 directly regulates osteoclastogenesis and bone resorption

Mechanical loading is required for bone homeostasis, but the underlying mechanism is still unclear. Our previous studies revealed that the mechanical protein polycystin-1 (PC1, encoded by Pkd1) is critical for bone formation. However, the role of PC1 in bone resorption is unknown. Here, we found that PC1 directly regulates osteoclastogenesis and bone resorption. The conditional deletion of Pkd1 in the osteoclast lineage resulted in a reduced number of osteoclasts, decreased bone resorption, and increased bone mass. A cohort study of 32,500 patients further revealed that autosomal dominant polycystic kidney disease, which is mainly caused by loss-of-function mutation of the PKD1 gene, is associated with a lower risk of hip fracture than those with other chronic kidney diseases. Moreover, mice with osteoclast-specific knockout of Pkd1 showed complete resistance to unloading-induced bone loss. A mechanistic study revealed that PC1 facilitated TAZ nuclear translocation via the C-terminal tail-TAZ complex and that conditional deletion of Taz in the osteoclast lineage resulted in reduced osteoclastogenesis and increased bone mass. Pharmacological regulation of the PC1-TAZ axis alleviated unloading- and estrogen deficiency- induced bone loss. Thus, the PC1-TAZ axis may be a potential therapeutic target for osteoclast-related osteoporosis.

Influence of Silicon Supplementation on Growth, Immunity, Antioxidant, Hormonal Profile and Bone Health Biomarkers in Pre-ruminant Crossbred Calves.

Silicon (Si), a newer trace element, is believed to be important for healthy bone formation and to decrease bone resorption, improving the quality of bone by manipulating several hormones and enzymes. Therefore, the current investigation was conducted to determine the impact of Si supplementation on growth, immunity, antioxidant, hormonal profile and biomarkers of bone health in pre-ruminant crossbred calves. Twenty-four crossbred calves (5-7 days) were selected on the basis of their body weight (BW 31.65 ± 0.46 kg) and divided into 4 groups (n = 6) and fed as per ICAR (2013) feeding standards except that these were additionally supplemented with 0 (Si0), 50 (Si50), 100 (Si100) and 150 (Si150) mg of Si/kg dry matter (DM) in four respective groups for 90 days. Every month, peripheral blood samples were drawn (0, 30, 60 and 90 days post supplementing with Si) and analysed for antioxidant status, hormonal profile and bone health biomarkers. It is reported that dietary Si supplementation improved (P < 0.05) net body weight gain (kg), average daily gain (g) and average dry matter intake (kg), whereas feed intake (kg/100 kg BW), was not altered due to Si supplementation. Structural growth measurements were significantly higher (P < 0.05) in Si100 and Si150 groups as compared to Si50 and control groups. However, immune response (humoral as well as cell-mediated immunity), erythrocytic antioxidant enzymes (superoxide dismutase, SOD, glutathione peroxidase, GPx and catalase), plasma ferric reducing total antioxidant power (FRAP) activity and the plasma concentration of total immunoglobulins (TIg) remained unaffected by Si supplementation. Silicon increased (P < 0.05) the concentration of plasma growth hormone (GH), vitamin D3, bone alkaline phosphatase (BALP) and osteocalcin (OCN) in Si100 and Si150 groups, but the levels of calcitonin, parathyroid hormone (PTH) and hydroxyproline (HYP) remained similar among all the groups. As a result of the current investigation, it can be inferred that the inclusion of 100 and 150 mg of Si/kg DM was effective in improving the growth performance, growth hormone, vitamin D3 and bone health status in pre-ruminant calves. However, supplementation of 150 mg of Si/kg DM had no additional benefit; therefore 100 mg of Si/kg DM is the optimum level of Si supplementation in pre-ruminant calves.

The effect of Schizophyllan on the differentiation of osteoclasts and osteoblasts

Schizophyllan (SPG), a β-glucan from Schizophyllum commune, is recognized for its antioxidant, immunoregulatory, and anticancer activities. In this study, its effects on bone cells, particularly osteoclasts and osteoblasts, were examined. We demonstrated that SPG dose-dependently inhibited osteoclastogenesis and reduced gene expression associated with osteoclast differentiation. SPG also decreased bone resorption and F-actin ring formation. This inhibition could have been due to the downregulation of transcription factors c-Fos and nuclear factor of activated T cells 1 (NFATc1) via the MAPKs (JNK and p38), IκBα, and PGC1β/PPARγ pathways. In coculture, SPG lowered osteoclastogenic activity in calvaria-derived osteoblasts by reducing macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor–κB ligand (RANKL) expression. In addition, SPG slightly enhanced osteoblast differentiation, as evidenced by increased differentiation marker gene expression and alizarin red staining. It also exhibited antiresorptive effects in a lipopolysaccharide-induced calvarial bone loss model. These results indicated a dual role of SPG in bone cell regulation by suppressing osteoclastogenesis and promoting osteoblast differentiation. Thus, SPG could be a therapeutic agent for bone resorption-related diseases such as osteoporosis, rheumatoid arthritis, and periodontitis.

Abstract 2761: Activating RET mutations promotes osteoblastic bone metastasis by inhibiting osteoclastogenesis and stimulating osteoblast activity via regulation of osteoprotegerin

Abstract Bone metastases (BM) are a source of increased mortality and significant morbidity in patients with medullary thyroid cancer (MTC), with ~50% survival at five years post-diagnosis. MTC causes osteoblastic, osteolytic, or mixed lesions, yet the underlying mechanisms are unknown. The RET proto-oncogene encodes a transmembrane tyrosine kinase receptor and is the driver oncogene in ~60% of MTC cases where a germline or somatic activating mutation results in ligand-independent constitutive activation of the receptor. However, the role of RET mutations in the genesis of bone metastasis lesions is unknown. We show that activating RET mutations promotes an osteoblastic phenotype in mice implanted with patient-derived MTC cells by increasing bone formation and decreasing bone resorption. We found that the radiographic appearance of osteoblastic lesions differed between the types of RET mutations (C634W and M918T). MTC cells with RETC634W mutation showed a four-fold increase in bone mineral density, trabecular bone volume, number, and thickness with a decreased number of osteoblasts compared to the non-tumor-bearing femur. TRAP staining revealed that osteoclast numbers per long bone were reduced in the injected femur compared to the control. In contrast, the MTC-RETM918T mutation showed an increased cortical thickness and porosity with reduced medullary area and increased bone formation rate compared to the non-tumor bearing femur. MTC cells formed tumors with extensive mineralized tissue, composed of bone matrix surrounded by osteoblast-like cells and osteoid. The knockdown of RET in the MTC-RETM918T model significantly reduced cortical thickness and increased the number of osteoclasts per bone surface. We observed increased osteoprotegerin (OPG) expression in MTC-bearing femurs compared to controls, suggesting decreased bone resorption. The factors secreted by MTC cells, including OPG, inhibited osteoclast formation from primary bone marrow cells and Raw264 cells. In addition, RET knockdown by shRNA in MTC cells decreased OPG expression. Moreover, the MTC-conditioned media (CM) increased osteoblast differentiation and mineralization of the primary culture of pre-osteoblasts isolated from calvarial bone, long bones, and MC3T3 cells. The conditioned media of RET-depleted cells inhibits osteoblast differentiation and mineralization. The expression of alkaline phosphatase, osteocalcin, OPG, and osterix increased in pre-osteoblast incubated with MTC-CM. Compared to primary non-metastatic tumors, the OPG expression increases in tissues of sporadic MTC bone metastases harboring RETM918T mutation. These results suggest that MTC with RET-activating mutations induces osteoblastic bone metastasis due to decreased bone resorption and increased bone formation. Citation Format: Rozita Bagheri-Yarmand, Joseph L. Kidd, Gabriel M. Pagnotti, Trupti Trivedi, Leah Guerra, Xinhai Wan, Jian Song, Sue-Hwa Lin, Theresa A Guise. Activating RET mutations promotes osteoblastic bone metastasis by inhibiting osteoclastogenesis and stimulating osteoblast activity via regulation of osteoprotegerin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2761.

The novel cytotoxic polybisphosphonate osteodex decreases bone resorption by enhancing cell death of mature osteoclasts without affecting osteoclastogenesis of RANKL-stimulated mouse bone marrow macrophages

SummaryIt has previously been demonstrated that the polybisphosphonate osteodex (ODX) inhibits bone resorption in organ-cultured mouse calvarial bone. In this study, we further investigate the effects by ODX on osteoclast differentiation, formation, and function in several different bone organ and cell cultures. Zoledronic acid (ZOL) was used for comparison. In retinoid-stimulated mouse calvarial organ cultures, ODX and ZOL significantly reduced the numbers of periosteal osteoclasts without affecting Tnfsf11 or Tnfrsf11b mRNA expression. ODX and ZOL also drastically reduced the numbers of osteoclasts in cell cultures isolated from the calvarial bone and in vitamin D3–stimulated mouse crude bone marrow cell cultures. These data suggest that ODX can inhibit osteoclast formation by inhibiting the differentiation of osteoclast progenitor cells or by directly targeting mature osteoclasts. We therefore assessed if osteoclast formation in purified bone marrow macrophage cultures stimulated by RANKL was inhibited by ODX and ZOL and found that the initial formation of mature osteoclasts was not affected, but that the bisphosphonates enhanced cell death of mature osteoclasts. In agreement with these findings, ODX and ZOL did not affect the mRNA expression of the osteoclastic genes Acp5 and Ctsk and the osteoclastogenic transcription factor Nfatc1. When bone marrow macrophages were incubated on bone slices, ODX and ZOL inhibited RANKL-stimulated bone resorption. In conclusion, ODX does not inhibit osteoclast formation but inhibits osteoclastic bone resorption by decreasing osteoclast numbers through enhanced cell death of mature osteoclasts.

3D-modeling from hip DXA shows improved bone structure with romosozumab followed by denosumab or alendronate.

Romosozumab treatment in women with postmenopausal osteoporosis increases bone formation while decreasing bone resorption, resulting in large BMD gains to reduce fracture risk within 1yr. DXA-based 3D modeling of the hip was used to assess estimated changes in cortical and trabecular bone parameters and map the distribution of 3D changes in bone parameters over time in patients from 2 randomized controlled clinical trials: FRAME (romosozumab vs placebo followed by denosumab) and ARCH (romosozumab vs alendronate followed by alendronate). For each study, data from a subset of ~200 women per treatment group who had TH DXA scans at baseline and months 12 and 24 and had provided consent for future research were analyzed post hoc. 3D-SHAPER software v2.11 (3D-SHAPER Medical) was used to generate patient-specific 3D models from TH DXA scans. Percentage changes from baseline to months 12 and 24 in areal BMD (aBMD), integral volumetric BMD (vBMD), cortical thickness, cortical vBMD, cortical surface BMD (sBMD), and trabecular vBMD were evaluated. Data from 377 women from FRAME (placebo, 190; romosozumab, 187) and 368 women from ARCH (alendronate, 185; romosozumab, 183) with evaluable 3D assessments at baseline and months 12 and 24 were analyzed. At month 12, treatment with romosozumab vs placebo in FRAME and romosozumab vs alendronate in ARCH resulted in greater increases in aBMD, integral vBMD, cortical thickness, cortical vBMD, cortical sBMD, and trabecular vBMD (P < .05 for all). At month 24, cumulative gains in all parameters were greater in the romosozumab-to-denosumab vs placebo-to-denosumab sequence and romosozumab-to-alendronate vs alendronate-to-alendronate sequence (P < .05 for all). 3D-SHAPER analysis provides a novel technique for estimating changes in cortical and trabecular parameters from standard hip DXA images. These data add to the accumulating evidence that romosozumab improves hip bone density and structure, thereby contributing to the antifracture efficacy of the drug.

Rate of Residual Ridge Resorption in Complete Denture Wearers – A Narrative Review

The aim of the present narrative review was to gather the available information on overdentures in order to find an answer to the question, "Does overdenture affect residual ridge resorption?" The study also identifies the elements that affect the rate of residual ridge resorption in individuals who wear overdentures. Search strategy application, inclusion and exclusion criteria definition, and study selection for findings summarization were all part of the approach. Each author collected the literature from the database on their own, and the application of the exclusion criteria resulted in seven literatures. When taken as a whole, the studies show how complicated a combination of variables, such as prosthetic support type, implant presence, and length of edentulism, influence alterations in the bone of edentulous individuals. Compared to conventional complete dentures, implant-supported overdentures—especially those with several implants—seem to be associated with decreased bone resorption. All of the reviewed study findings highlight how important it is to utilise prosthetics, how occlusal pressures and implant use affect bone alterations in an individual's edentulous maxilla and mandible. The results deepen our knowledge of the challenges associated with caring for edentulous patients and emphasise the need for personalised treatment plans based on a range of patient-specific variables as well as ongoing investigation to better understand and treat residual ridge resorption in denture wearers.

Cementless reverse total shoulder arthroplasty implantation with humeral matchstick autograft augmentation: early radiographic outcomes

IntroductionHumeral-sided complications account for up to 21% of all revision Reverse Total Shoulder Arthroplasty (RTSA) surgeries.1 Stress shielding with large bulky stems can lead to proximal bone resorption per Wolff’s law, complicating further surgeries.14,28 Previously published studies suggest that lowering the metaphyseal implant fill ratio can lead to fewer adaptive radiographic changes and decreased bone resorption.25,26,29 Inspired by these studies, cementless primary RTSA implantation technique with humeral matchstick autografts was proposed to augment cementless humeral constructs, foster the use of a smaller size stem, and create primary stability of the humeral implant even in osteoporotic or in-between size medullary canals. In this study, retrospective review of this cementless RTSA technique with short term radiographic evaluation was performed. MethodsForty-six nonconsecutive patients underwent primary RTSA with a short-stem cementless prosthesis (Stryker Ascend Flex, Kalamazoo, MI, USA) augmented by matchstick bone grafting from January to July 2020. Patient demographics were recorded, and follow-up x-rays were retrospectively reviewed to assess metaphyseal fill ratios and incidence of stress shielding at minimum 1-year follow-up. Discrepancies between templated and final stem sizes were recorded, along with all intraoperative and postoperative complications. ResultsOf the 46 patients originally identified, there were 5 men and 41 women with a mean age of 71 years (SD ± 7, range 53-88). Mean templated stem size was 4 (SD ± 2, range 1-8), while mean final implant size was 2 (SD ± 1, Range 1-3). Mean fill ratios were 0.76 (SD ± 0.06, range 0.54-0.89) along the metaphysis and 0.67 (SD ± 0.09, range 0.49-0.83) along the diaphysis. There were no intraoperative humeral fractures from implantation. All patients were available for radiographic follow-up with a mean of 19 months (SD ± 8, range 12-40). There were three cases (7%) of proximal humeral stress shielding, with average fill ratios of 0.857 and 0.807 in the metaphysis and diaphysis, respectively. There were 3 patients (7%) who underwent revision surgeries for baseplate failure and periprosthetic humeral fracture. There were no cases of early humeral loosening. DiscussionMatchstick autograft humeral augmentation is a simple, promising surgical technique with low intraoperative complication rates and good short-term radiographic outcomes. When the implant fill ratio is successfully reduced, there is possible lower risk of humeral stress shielding. The authors believe this technique can help maximize implant stability in cementless shoulder arthroplasty and preserve humeral bone stock for future revision surgeries.