Elucidating anti-sclerostin mechanism of baicalein using LRP6-Sclersotin complex of canonical Wnt/ß-catenin signaling pathway.

Flavonoids are polyphenolic compounds produced by plants as secondary metabolites that are known to exhibit wide range of pharmaceutical properties. Flavonoids from different medicinal plants have been used in traditional medicine to treat several musculoskeletal disorders for centuries. Of the numerous flavonoids, baicalein from Oroxylum indicum has a well-documented protective effect in skeletal health. However, studies into its influence on the canonical Wnt/ß-catenin signaling pathway for musculoskeletal disorders remain limited. With the results of our previous study, the current research investigated the molecular mechanism of baicalein to inhibit the interaction between LRP6 and sclerostin to activate the canonical Wnt/ß-catenin signaling pathway. Molecular docking revealed that baicalein docks between LRP6 and sclerostin with a binding energy of -8.4 kcal/mol and interacts with key binding residues of both the proteins. The molecular dynamics simulations predicted the stability of baicalein through 100 ns with more conformational changes observed in sclerostin than LRP6 especially in and around the PNAIG motif of loop-2 region, hinting at a possible inhibitory effect of baicalein over sclerostin. The findings of this research could pave the way for novel drug design approaches while promoting the use of natural flavonoids as potential therapeutics for musculoskeletal disorders.Communicated by Ramaswamy H. Sarma.

Moxibustion as an adjunctive treatment for rheumatoid arthritis and its effects on the serum levels of SOST and ß-catenin. / è‰¾ç¸è¾ åŠ©æ²»ç–—ç±»é£Žæ¹¿å ³èŠ‚ç‚ŽåŠå¯¹æ‚£è€ è¡€æ¸ SOST、ß-catenin含量的影响.

OBJECTIVES: To observe the clinical efficacy of moxibustion as an adjunctive treatment for rheumatoid arthritis (RA) based on conventional medication and its effects on serum sclerostin (SOST) and ß-catenin levels, exploring the potential mechanisms by which moxibustion may protect joint bones in RA patients. METHODS: Seventy-six RA patients were randomly divided into an observation group (38 cases, 3 cases dropped out) and a control group (38 cases, 4 cases were eliminated, 2 cases dropped out). The patients in the control group were treated with conventional oral medication; based on the treatment of the control group, the patients in the observation group were treated with moxibustion. The direct moxibustion was applied at Zusanli (ST 36) on both sides and ashi points around small joints, and indirect moxibustion was applied at Shenshu (BL 23) on both sides and ashi points around large joints. The treatment was given three times a week for a total of 5 weeks. The count of pain and swollen joint, morning stiffness score, disease activity score of 28 joints (DAS28), visual analogue scale (VAS) score, health assessment questionnaire (HAQ) score, and serum levels of SOST, ß-catenin, and tumor necrosis factor-α (TNF-α) were evaluated before and after treatment in the two groups. RESULTS: Compared those before treatment, after treatment, both groups showed a reduction in pain and swollen joint count (P<0.01, P<0.05), morning stiffness, DAS28, VAS, and HAQ scores (P<0.01, P<0.05), with the observation group having lower scores than the control group (P<0.01). Serum levels of SOST, ß-catenin, and TNF-α after treatment in the observation group were lower than those in both before treatment and the control group (P<0.01, P<0.05). There was a positive correlation between the difference in serum ß-catenin levels before and after treatment and the difference in serum SOST (r=0.578, P<0.001) and TNF-α (r=0.403, P<0.05) levels in the observation group. CONCLUSIONS: In addition to medication, moxibustion as an adjunctive treatment could significantly alleviate joint pain and reduce disease activity in RA patients, suggesting a potential role in joint protection. This mechanism may be related to the inhibition of the inflammatory factor TNF-α, regulation of ß-catenin levels, and reduction in the production of the endogenous negative regulator protein SOST within the Wnt/ß-catenin signaling pathway.

Biologics: Teriparatide and Newer Anabolics.

The landscape of osteoporosis management has evolved significantly over the years, witnessing a paradigm shift from conventional therapies to the emergence of biologic agents. This chapter delves into the intricate mechanisms, potential applications, and future directions of biologic interventions in osteoporosis care. Biologic agents, with their targeted approach to bone health, have revolutionized the field by offering precision-driven strategies that address the underlying mechanisms of bone fragility. This chapter explores the mechanisms of action of various biologics, including Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL) inhibitors, monoclonal antibodies targeting sclerostin, parathyroid hormone (PTH) analogues, and cathepsin K inhibitors. It discusses their potential benefits, limitations, and safety considerations, while shedding light on the promise of combination therapies that merge biologic agents with traditional approaches. Furthermore, the chapter delves into the potential applications of biologic agents in specific patient populations, the role of biomarkers in predicting treatment responses, and the influence of emerging biological targets. It also explores the advancements in novel targets and drug delivery systems that aim to enhance treatment convenience and effectiveness. By tailoring treatments based on patient characteristics and exploring novel therapeutic targets, the chapter envisions a future of precision medicine in osteoporosis care. As research continues to evolve, the chapter anticipates a transformative impact on bone health outcomes, fracture prevention, and overall quality of life for individuals at risk of osteoporosis-related fractures. Through comprehensive insights into the mechanisms, applications, and future directions of biologic agents, this chapter offers a holistic perspective on the evolving landscape of osteoporosis management.

Effect of a 3-month L-carnitine supplementation and resistance training program on circulating markers and bone mineral density in postmenopausal women: a randomized controlled trial.

BACKGROUND: Higher circulating levels of trimethylamine N-oxide (TMAO), which is a metabolite that can be produced by the gut microbiota from L-carnitine (LC), have been associated with bone mineral density (BMD). Because LC supplementation can improve bone density and microstructural properties in animal models, this study aimed to examine the effects of 12 weeks of LC supplementation on BMD and selected blood markers involved in bone metabolism of postmenopausal women participating in a resistance training (RT) program. METHODS: Twenty-seven postmenopausal women, who had not been treated for osteoporosis, with a total T-score above - 3.0 and no diet differences completed 12 weeks of RT. The participants' diets were supplemented with either 1 g of LC-L-tartrate and 3 g of leucine per day (LC group) or 4 g of leucine per day as a placebo (PLA group), in a double-blind fashion. RESULTS: After the intervention in the LC group, plasma total carnitine and serum decorin levels were higher than the corresponding preintervention values (p = 0.040 and p = 0.042, respectively). Moreover, plasma TMAO and serum SPARC levels were higher in the LC group than the corresponding postintervention values in the PLA group (p < 0.001 and p = 0.030, respectively). No changes in the BMD were observed after 3 months of the intervention. CONCLUSIONS: Twelve weeks of LC supplementation during RT program increased plasma TMAO levels and appeared to affect signaling molecules, as indicated by the increase in the resting SPARC and decorin levels, with no significant modification in the BMD. TRIAL REGISTRATION: Retrospectively registered at the ClinicalTrials.gov (NCT05120011).

Identification of potential sclerostin inhibiting flavonoids from Oroxylum indicum: an insilico approach.

Flavonoids are secondary metabolites that are widely found in various medicinal plants. They are known for their medicinal benefits and have been extensively used in healthcare industries and in the management of age-related diseases. This paper focuses on flavonoids from Oroxylum indicum, a significant medicinal tree in the practice of traditional Indian medicine. O. indicum has been utilized in a variety of polyherbal formulations for the management of musculoskeletal disorders, however the mechanism of action of its bioactive flavonoids remains unknown. The present study aimed to identify the flavonoids of O. indicum with the potential to target sclerostin, an antagonist of canonical Wnt signaling pathway for the treatment of bone-related disorders. Molecular docking, coarse-grained and molecular dynamics simulations were performed to screen the major flavonoids and investigate their interaction with sclerostin. Flavonoids with highest binding affinity and interacting with at least one of the amino acids of the PNAIG motif residues were selected from docking studies and subjected to further drug likeness and ADMET screening. Further screening from coarse-grained and molecular dynamic simulations results showed that baicalein, compared to other screened flavonoids, stably binds with the important residues of the LRP6 binding site of sclerostin, resulting in pronounced structural changes in the protein. These findings suggest that baicalein from O. indicum can potentially inhibit sclerostin and can elicit skeletal protective effects, providing an insight for further in vitro and in vivo studies.Communicated by Ramaswamy H. Sarma.

Mature primary human osteocytes in mini organotypic cultures secrete FGF23 and PTH1-34-regulated sclerostin.

Introduction: For decades, functional primary human osteocyte cultures have been crucially needed for understanding their role in bone anabolic processes and in endocrine phosphate regulation via the bone-kidney axis. Mature osteocyte proteins (sclerostin, DMP1, Phex and FGF23) play a key role in various systemic diseases and are targeted by successful bone anabolic drugs (anti-sclerostin antibody and teriparatide (PTH1-34)). However, cell lines available to study osteocytes produce very little sclerostin and low levels of mature osteocyte markers. We have developed a primary human 3D organotypic culture system that replicates the formation of mature osteocytes in bone. Methods: Primary human osteoblasts were seeded in a fibrinogen / thrombin gel around 3D-printed hanging posts. Following contraction of the gel around the posts, cells were cultured in osteogenic media and conditioned media was collected for analysis of secreted markers of osteocyte formation. Results: The organoids were viable for at least 6 months, allowing co-culture with different cell types and testing of bone anabolic drugs. Bulk RNAseq data displayed the developing marker trajectory of ossification and human primary osteocyte formation in vitro over an initial 8- week period. Vitamin D3 supplementation increased mineralization and sclerostin secretion, while hypoxia and PTH1-34 modulated sclerostin. Our culture system also secreted FGF23, enabling the future development of a bone-kidney-parathyroid-vascular multi-organoid or organ-on-a-chip system to study disease processes and drug effects using purely human cells. Discussion: This 3D organotypic culture system provides a stable, long-lived, and regulated population of mature human primary osteocytes for a variety of research applications.

Effects of E'Jiao on Skeletal Mineralisation, Osteocyte and WNT Signalling Inhibitors in Ovariectomised Rats.

E'Jiao is a traditional Chinese medicine derived from donkey skin. E'Jiao is reported to suppress elevated bone remodelling in ovariectomised rats but its mechanism of action is not known. To bridge this research gap, the current study aims to investigate the effects of E'Jiao on skeletal mineralisation, osteocyte and WNT signalling inhibitors in ovariectomised rats. Female Sprague-Dawley rats (3 months old) were ovariectomised and supplemented with E'Jiao at 0.26 g/kg, 0.53 g/kg and 1.06 g/kg, or 1% calcium carbonate (w/v) in drinking water. The rats were euthanised after two months of supplementation and their bones were collected for Fourier-transform infrared spectroscopy, histomorphometry and protein analysis. Neither ovariectomy nor treatment affected the skeletal mineral/matrix ratio, osteocyte number, empty lacunar number, and Dickkopf-1 and sclerostin protein levels (p > 0.05). Rats treated with calcium carbonate had a higher Dickkopf-1 level than baseline (p = 0.002) and E'Jiao at 0.53 g/kg (p = 0.002). In conclusion, E'Jiao has no significant effect on skeletal mineralisation, osteocyte and WNT signalling inhibitors in ovariectomised rats. The skeletal effect of E'Jiao might not be mediated through osteocytes.

Serum sclerostin in acute kidney injury patients.

BACKGROUND: Many of the mineral metabolite abnormalities encountered in chronic kidney disease (CKD) patients were found also associated with acute kidney injury (AKI). In the last decade, sclerostin was found to intimately affect bone mineral metabolism in CKD patients. Nothing is known about sclerostin in AKI. OBJECTIVE: We looked for serum level of sclerostin in AKI patients in comparison to normal control subjects and if there is an impact on metabolic derangement, endothelial function or clinical outcome. CASES AND METHODS: This is a cross sectional case control observational study of 219 AKI cases (group I) beside 219 age matched normal control subjects (group II). All cases of group I were in the intensive care because of sepsis; 86 had acute on CKD (group Ib), while 133 had de novo AKI (group Ia). All studied subjects underwent estimation of serum sclerostin, parathyroid hormone (PTH), 25 hydroxy vitamin D (25 OH vit D), fibroblast growth factor 23 (FGF23), C-reactive protein (CRP), interleukin 6 (IL6), Homeostatic Model Assessment for Insulin Resistance (Homa IR), beside the routine CBC, kidney and liver function tests, serum calcium, and phosphorus, and flow mediated vasodilation of brachial artery (FMD). Follow-up of group I cases was done till they recovered or passed away. RESULTS: Serum sclerostin, PTH, FGF23, phosphorus, CRP, IL6, HOMA IR, creatinine, urea, uric acid, ALT, AST and white blood cell count (WBC) were significantly higher while serum calcium, 25 OH vit D, hemoglobin, platelet count and FMD were significantly lower in group I compared to group II (P<0.001 in all). On the other hand, there was no significant difference in serum sclerostin, PTH, FGfF23, 25 OH vit D, CRP, IL6, Homa IR and FMD between group Ia and Ib. Survivors were younger in age (median 55.5 vs. 60 years, P<0.04), had lower AST (30.5 vs. 58 units, P<0.001), had higher platelet count (206 vs 162×109/L, P<0.001), otherwise, there was no significant difference in any of the other parameters between survivors and patients that were lost. Serum sclerostin had strong correlation with FGF23 in group I (r=0.99, P<0.001) and group II (r=1, P<0.001). Homa IR had positive correlation with serum sclerostin (r=0.148, P=0.014) and serum FGF23 (r=0.142, P=0.018) in group I. CONCLUSION: Sclerostin is intimately related to FGF23. Sclerostin level increases in AKI patients. Both sclerostin and FGF23 might increase insulin resistance but have no impact on FMD. Neither sclerostin nor FGF23 interfere with AKI outcome.

The comparison of effects of balneotherapy, water-based and land-based exercises on disease activity, symptoms, sleep quality, quality of life and serum sclerostin level in patients with ankylosing spondylitis: A prospective, randomized study.

Objectives: This study aims to compare the effects of balneotherapy, water-based exercise (WBE), and land-based exercise (LBE) on disease activity, symptoms, sleep quality, quality of life, and serum sclerostin level (SSL) in patients with ankylosing spondylitis (AS). Patients and methods: Between January 2019 and January 2020, a total of 60 patients (35 males, 25 females; mean age: 40.9±11.2 years; range, 18 to 55 years) who were diagnosed with AS were randomly divided into the balneotherapy (n=20), WBE (n=20), and LBE (n=20) groups (20 sessions of treatment in groups of five to six patients). The patients were evaluated before treatment and at 4 and 12 weeks using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Ankylosing Spondylitis Disease Activity Score-C-reactive protein (ASDAS-CRP), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Ankylosing Spondylitis Quality of Life (ASQoL) Scale, Fatigue Severity Scale (FSS), and Pittsburg Sleep Quality Index (PSQI), and SSL were measured. Results: Statistically significant improvements in the BASDAI, BASFI, MASES, BASMI, ASQoL, FSS, and ASDAS-CRP scores were observed in all groups at 4 and 12 weeks of follow-up (p<0.05). A significant improvement in sleep latency was seen in the balneotherapy and WBE groups. Changes in SSL were not statistically significant in any group (p>0.05). Conclusion: Balneotherapy, WBE, and LBE are effective in the treatment of AS, and the beneficial effects may last for at least 12 weeks.

The Gestational Effects of Maternal Bone Marker Molecules on Fetal Growth, Metabolism and Long-Term Metabolic Health: A Systematic Review.

Fetal exposure in adverse environmental factors during intrauterine life can lead to various biological adjustments, affecting not only in utero development of the conceptus, but also its later metabolic and endocrine wellbeing. During human gestation, maternal bone turnover increases, as reflected by molecules involved in bone metabolism, such as vitamin D, osteocalcin, sclerostin, sRANKL, and osteoprotegerin; however, recent studies support their emerging role in endocrine functions and glucose homeostasis regulation. Herein, we sought to systematically review current knowledge on the effects of aforementioned maternal bone biomarkers during pregnancy on fetal intrauterine growth and metabolism, neonatal anthropometric measures at birth, as well as on future endocrine and metabolic wellbeing of the offspring. A growing body of literature converges on the view that maternal bone turnover is likely implicated in fetal growth, and at least to some extent, in neonatal and childhood body composition and metabolic wellbeing. Maternal sclerostin and sRANKL are positively linked with fetal abdominal circumference and subcutaneous fat deposition, contributing to greater birthweights. Vitamin D deficiency correlates with lower birthweights, while research is still needed on intrauterine fetal metabolism, as well as on vitamin D dosing supplementation during pregnancy, to diminish the risks of low birthweight or SGA neonates in high-risk populations.

Effect of High-Dose Glucocorticoids on Markers of Inflammation and Bone Metabolism in Patients with Primary Glomerular Disease.

BACKGROUND: Glucocorticoids are one of the most commonly used drugs for treatment of inflammatory and autoimmune diseases. Sirtuin-1 (SIRT-1) belongs to the family of proteins involved in protection against inflammation and oxidative stress. A role of SIRT-1 in regulation of bone metabolism during high-dose steroid therapy is unknown. OBJECTIVES: The study assessed influence of high doses of intravenous corticosteroids on plasma inflammation and bone markers in patients with primary glomerular disease. METHODS: The study included 40 patients (25 M, 15 F; mean age 53.1 ± 14 years) with chronic kidney disease (mean estimated glomerular filtration rate, 58.9 ± 31.3 mL/min). The main inclusion criterion was clinical and histopathological diagnosis of primary glomerular disease and urine protein excretion >2.0 g/24 h. The patients received intravenous pulses of methylprednisolone 20-30 mg/kg/day for three consecutive days followed by oral prednisone 0.8-1.0 mg/kg/day. The blood was taken before administration of methylprednisolone to assess plasma SIRT-1, sclerostin, calcium, phosphate, and parathormone; and first-morning urine sample was taken for measurement of calcium, phosphate, and albumin to creatinine ratio. The same laboratory tests were repeated after 4, 7, and 30 days during steroid therapy. RESULTS: Plasma SIRT-1 increased significantly during steroid administration. Plasma sclerostin did not change significantly. There was a significant linear negative correlation between changes in SIRT-1 levels and sclerostin throughout the study. In a multiple regression model, changes of plasma sclerostin induced by steroid therapy explained the largest part of variance of respective changes of plasma SIRT-1. CONCLUSIONS: Plasma SIRT-1 increase during high-dose corticosteroid therapy is negatively related to the change of plasma sclerostin that may suggest a protective role of SIRT-1 against the negative effects of steroid therapy on bone.

Muscle and Bone Impairment in Infantile Nephropathic Cystinosis: New Concepts.

Cystinosis Metabolic Bone Disease (CMBD) has emerged during the last decade as a well-recognized, long-term complication in patients suffering from infantile nephropathic cystinosis (INC), resulting in significant morbidity and impaired quality of life in teenagers and adults with INC. Its underlying pathophysiology is complex and multifactorial, associating complementary, albeit distinct entities, in addition to ordinary mineral and bone disorders observed in other types of chronic kidney disease. Amongst these long-term consequences are renal Fanconi syndrome, hypophosphatemic rickets, malnutrition, hormonal abnormalities, muscular impairment, and intrinsic cellular bone defects in bone cells, due to CTNS mutations. Recent research data in the field have demonstrated abnormal mineral regulation, intrinsic bone defects, cysteamine toxicity, muscle wasting and, likely interleukin-1-driven inflammation in the setting of CMBD. Here we summarize these new pathophysiological deregulations and discuss the crucial interplay between bone and muscle in INC. In future, vitamin D and/or biotherapies targeting the IL1ß pathway may improve muscle wasting and subsequently CMBD, but this remains to be proven.

IMPACT OF GRAVES' DISEASE AND ANTITHYROID DRUG THERAPY ON BONE MINERAL DENSITY - PATHOPHYSIOLOGICAL MECHANISMS AND CLINICAL RELEVANCE.

Graves' disease is an autoimmune disease characterized by excessive thyroid hormone production. One of the consequences of that state can be a decrease in bone mineral density (BMD). Graves' disease is often treated with antithyroid drugs (ATD) as first line therapy, which can lead to disease remission. Moreover, recent data show that improvement in BMD can be expected. However, vitamin D deficiency can coexist along with Graves' disease, which is also involved in the process of bone remodeling. It is still not known whether lower values of vitamin D can contribute to onset of Graves' disease and if its supplementation might be helpful in therapy for hyperthyroidism. In the past couple of decades, osteopenia and osteoporosis have become a major health burden not only in post-menopausal women but also as a result of other diseases, leading to extensive research into various pathophysiological mechanisms responsible for bone remodeling. The Wnt (wingless integrated) signaling pathway is a very important factor in bone homeostasis, especially the canonical pathway. Present data indicate that stimulation of the Wnt pathway leads to bone mass increase and, in contrast, its inhibition leads to bone mass decrease. Hence, inhibitors of the canonical Wnt pathway became the focus of interest, in particular sclerostin and dickkopf 1 (DKK1). Hyperthyroidism and osteopenia/osteoporosis are quite common today and can coexist together or as separate entities. In this article, we aimed to give an overview of possible associations and potential mutual pathophysiological mechanisms.

Metabolism of Subchondral Bone Tissue in Posttraumatic Osteoarthrosis in Rats.

In rats with modeled posttraumatic knee osteoarthrosis, negative changes in subchondral bone metabolism were revealed: a tendency to an increase in osteocalcin concentration, a decrease in sclerostin and osteoprotegerin levels, and a significant increase in FGF-23 concentration accompanied by a slight elevation of inorganic phosphorous and significant increase in total calcium levels in comparison with the corresponding parameters in intact controls. These findings demonstrate crucial importance of structural integrity of the subchondral bone, because its protection improves the results of reconstructive therapy for local cartilage defects.

Hyperbaric Oxygen Therapy Does Not Have a Negative Impact on Bone Signaling Pathways in Humans.

INTRODUCTION: Oxygen is emerging as an important factor in the local regulation of bone remodeling. Some preclinical data suggest that hyperoxia may have deleterious effects on bone cells. However, its clinical relevance is unclear. Hence, we studied the effect of hyperbaric oxygen therapy (HBOT) on serum biomarkers reflecting the status of the Wnt and receptor activator of NF-κB ligand (RANKL) pathways, two core pathways for bone homeostasis. MATERIALS AND METHODS: This was a prospective study of 20 patients undergoing HBOT (mean age 58 yrs., range 35-82 yrs.) because of complications of radiotherapy or chronic anal fissure. Patients were subjected to HBOT (100% oxygen; 2.4 atmospheres absolute for 90 min). The average number of HBOT sessions was 20 ± 5 (range 8-31). Serum hypoxia-inducible factor 1-α (HIF1-α), osteoprotegerin (OPG), RANKL, and the Wnt inhibitors sclerostin and dickkopf-1 (DKK1) were measured at baseline and after HBOT by using specific immunoassays. RESULTS: HIF-1α in eight patients with measurable serum levels increased from 0.084 (0.098) ng/mL at baseline to 0.146 (0.130) ng/mL after HBOT (p = 0.028). However, HBOT did not induce any significant changes in the serum levels of OPG, RANKL, sclerostin or DKK1. This was independent of the patients' diagnosis, either neoplasia or benign. CONCLUSION: Despite the potential concerns about hyperoxia, we found no evidence that HBOT has any detrimental effect on bone homeostasis.

Self-emulsified annatto tocotrienol improves bone histomorphometric parameters in a rat model of oestrogen deficiency through suppression of skeletal sclerostin level and RANKL/OPG ratio.

Menopause is the leading cause of osteoporosis for elderly women due to imbalanced bone remodelling in the absence of oestrogen. The ability of tocotrienol in reversing established bone loss due to oestrogen deficiency remains unclear despite the plenitude of evidence showcasing its preventive effects. This study aimed to investigate the effects of self-emulsified annatto tocotrienol (SEAT) on bone histomorphometry and remodelling in ovariectomised rats. Female Sprague Dawley rats (n=36) were randomly assigned into baseline, sham, ovariectomised (OVX) control, OVX-treated with annatto tocotrienol (AT) (60 mg/kg), SEAT (60 mg/kg) and raloxifene (1 mg/kg). Daily treatment given through oral gavage was started two months after castration. The rats were euthanised after eight weeks of treatment. Blood was collected for bone biomarkers. Femur and lumbar bones were collected for histomorphometry and remodelling markers. The results showed that AT and SEAT improved osteoblast numbers and trabecular mineralisation rate (p<0.05 vs untreated OVX). AT also decreased skeletal sclerostin expression in OVX rats (p<0.05 vs untreated OVX). Similar effects were observed in the raloxifene-treated group. Only SEAT significantly increased bone formation rate and reduced RANKL/OPG ratio (p<0.05 vs untreated OVX). However, no changes in osteoclast-related parameters were observed among the groups (p>0.05). In conclusion, SEAT exerts potential skeletal anabolic properties by increasing bone formation, suppressing sclerostin expression and reducing RANKL/OPG ratio in rats with oestrogen deficiency.

Deletion of the sodium/hydrogen exchanger 6 causes low bone volume in adult mice.

The sodium/hydrogen exchanger 6 (NHE6) localizes to recycling endosomes, where it mediates endosomal alkalinization through K+/H+ exchange. Mutations in the SLC9A6 gene encoding NHE6 cause severe X-linked mental retardation, epilepsy, autism and corticobasal degeneration in humans. Patients with SLC9A6 mutations exhibit skeletal malformations, and a previous study suggested a key role of NHE6 in osteoblast-mediated mineralization. The goal of this study was to explore the role of NHE6 in bone homeostasis. To this end, we studied the bone phenotype of NHE6 knock-out mice by microcomputed tomography, quantitative histomorphometry and complementary ex vivo and in vitro studies. We detected NHE6 transcript and protein in both differentiated osteoclasts and mineralizing osteoblasts. In vitro studies with osteoclasts and osteoblasts derived from NHE6 knock-out mice demonstrated normal osteoclast differentiation and osteoblast proliferation without an impairment in mineralization capacity. Microcomputed tomography and bone histomorphometry studies showed a significantly reduced bone volume and trabecular number as well as an increased trabecular space at lumbar vertebrae of 6 months old NHE6 knock-out mice. The bone degradation marker c-terminal telopeptides of type I collagen was unaltered in NHE6 knock-out mice. However, we observed a reduction of the bone formation marker procollagen type 1 N-terminal propeptide, and increased circulating sclerostin levels in NHE6 knock-out mice. Subsequent studies revealed a significant upregulation of sclerostin transcript expression in both primary calvarial cultures and femora derived from NHE6 knock-out mice. Thus, loss of NHE6 in mice causes an increase of sclerostin expression associated with reduced bone formation and low bone volume.

Prevalence of vertebral fractures and serum sclerostin levels in acromegaly.

OBJECTIVE: An increased prevalence of vertebral fractures (VFs) has been reported in previous studies. The aim of this study was to evaluate the association between bone mineral density (BMD), bone turnover markers, serum sclerostin levels, and vertebral fractures (VFs) in acromegaly patients. We also evaluated the effects of gonadal status, disease activity, treatment modality, age, sex, and body mass index (BMI) on skeletal endpoints. DESIGN: Case-control study. PATIENTS AND MEASUREMENTS: Seventy acromegaly patients (M/F:36/34, mean age 45.5 ± 11.9 years) and 70 controls (M/F:31/39; mean age 45.66 ± 11.9 years) were included. VFs, BMD, calcium metabolism, markers of bone turnover, and sclerostin levels were evaluated. BMD was measured by dual-energy X-ray absorptiometry (Hologic QDR 4500). Conventional lateral radiography of the spine was performed and the Genant method was used for the assessment of fractures of T4-L5 vertebrae. RESULTS: The prevalence of vertebral fractures was higher in acromegalic patients as compared with the control group (72.9 vs. 20%; p < 0.001). Serum phosphate (P) levels (3.46 ± 0.59 mg/dl vs. 3.11 ± 0.44 mg/dl; p < 0.001) and b-cross laps (CTx) levels (0.47 µg/l, range 0.04-2.38 vs. 0.28 µg/l, range 0.11-0.80; p < 0.001) were significantly higher in acromegaly patients than control subjects. Serum sclerostin levels were similar between either acromegaly patients and control subjects or acromegaly patients with VF and without VF. In the means of treatment modality, VFs were more frequent in patients treated with adjuvant gamma knife radiosurgery (GKS) (p = 0.07). In the binary logistic regression analysis, the age of the acromegaly patients, the presence of hypogonadism, and GKS treatment were the factors significantly correlated with the occurrence of spinal fractures. CONCLUSIONS: The prevalence of VFs in patients with acromegaly is higher than in control subjects. Since advanced age, the presence of hypogonadism and GKS treatment were the factors predicting VFs in acromegaly; radiological evaluations should be considered as an emerging tool especially in those patients. Although markers of bone turnover elevated in acromegaly, they were not useful for the prediction of fractures. Serum sclerostin levels showed no discrepancy between the two groups and further studies are required for assessment of sclerostin role in this form of secondary osteoporosis.

Shuxuetong injection simultaneously ameliorates dexamethasone-driven vascular calcification and osteoporosis.

Osteoporosis (OP) and vascular calcification (VC) share a number of common risk factors, pathophysiological mechanisms and etiology, which are known as bone-vascular axis. The present study aimed to investigate the effects of Shuxuetong (SXT) injection on VC and osteoporosis. A rat model of VC and osteoporosis was induced by dexamethasone (DEX; 1 mg/kg/day for 4 weeks, intramuscularly). Simultaneously, 0.6 ml/kg/day SXT was intraperitoneally injected. Compared with control rats, DEX induced significantly more VC and OP, as determined by increased calcium deposition and alkaline phosphatase activity in the aorta, disturbed structure, decreased levels of cortical bone thickness and trabecular bone area, and increased apoptosis in the bone. SXT injection ameliorated DEX-induced VC and osteoporosis; furthermore, the osteoblastic differentiation of vascular smooth muscle cells and the activation of endoplasmic reticulum stress in the DEX group was also prevented by SXT injection. Compared with control rats, protein expression levels of sclerostin, a crucial crosslink of the bone-vascular axis, were significantly increased in the aorta and bone of rats with DEX, which was also attenuated by SXT injection. Thus, the present study suggested that SXT injection could ameliorate both VC and OP, and may be mediated by the regulation of sclerostin. The present study may provide the basis a novel strategy for the prevention and treatment of VC and OP, which emerge as side-effects of glucocorticoids.

Vitamin D deficiency promotes large rupture-prone abdominal aortic aneurysms and cholecalciferol supplementation limits progression of aneurysms in a mouse model.

Vitamin D deficiency has been associated with human abdominal aortic aneurysm (AAA); however, its role in AAA pathogenesis is unclear. The aim of the present study was to investigate the effect of vitamin D deficiency on AAA development and examine if administering cholecalciferol (CCF) could limit growth of established AAA within the angiotensin-II (AngII) infused apolipoprotein E-deficient mouse model. Mice were rendered vitamin D deficiency through dietary restriction and during AngII infusion developed larger AAAs as assessed by ultrasound and ex vivo morphometry that ruptured more commonly (48% vs. 19%; P=0.028) than controls. Vitamin D deficiency was associated with increased aortic expression of osteopontin and matrix metalloproteinase-2 and -9 than controls. CCF administration to mice with established aortic aneurysms limited AAA growth as assessed by ultrasound (P<0.001) and ex vivo morphometry (P=0.036) and reduced rupture rate (8% vs. 46%; P=0.031). This effect was associated with up-regulation of circulating and aortic sclerostin. Incubation of human aortic smooth muscle cells with 1,25-dihyroxyvitamin D3 (the active metabolite of vitamin D) for 48 h induced up-regulation of sclerostin (P<0.001) and changed the expression of a range of other genes important in extracellular matrix remodeling. The present study suggests that vitamin D deficiency promotes development of large rupture-prone aortic aneurysms in an experimental model. CCF administration limited both growth and rupture of established aneurysms. These effects of vitamin D appeared to be mediated via changes in genes involved in extracellular matrix remodeling, particularly sclerostin.