Bisphosphonate treatment of postmenopausal osteoporosis is associated with a dose dependent increase in serum sclerostin

Correlation Between Bone Metabolism Indices and Osteoporotic Thoracolumbar Vertebrae Fracture in Postmenopausal Women

Background

This study aims to explore the correlation between bone metabolism indices and osteoporotic thoracolumbar vertebrae fracture (OTVF) in postmenopausal women.

Methods

A total of 447 female patients with postmenopause and underwent OTVF in our hospital were selected as group A. Three hundred eighty-seven out-patients without fractures were selected as group B. Bone metabolism index including the serum levels of total Serum procollagen type N-terminal propeptide (tPINP), the age-related type I cross linked C-telopeptide (β-CTX) and 25-hydroxyvitamin D (25-OHD) were collected and compared. The relation between bone metabolism indices and OTVF was analyzed.

Results

The mean tPINP in group A was 61.72 ± 28.43, which was notably higher than group B (P < 0.01). Meanwhile, greater β-CTX were higher founded in group A than group B (0.778 ± 0.316 vs 0.669 ± 0.303 μg/l). However, the 25-OHD in group A was significantly lower than that in group B (P < 0.05). Multivariate logistic regression analysis revealed that the serum level of tPINP (OR: 0.008, P = 0.011), the serum level of β-CTX (OR: 0.805, P = 0.002) and the serum level of 25-OHD (OR: -0.029, P = 0.003) were independently correlated with postmenopausal OTVF.

Conclusion

Bone metabolic markers play an important role in predicting OTVF. As a reflection of bone mass and bone strength, BMD is inadequate in predicting OTVF. High expression of bone metabolism indicators β-CTX, tPINP and relatively low expression of 25-OHD suggest an increased risk of OTVF. Early detection of postmenopausal bone metabolism abnormalities can be used for early intervention to reduce the incidence of OTVF.

Effects of Glucagon-Like Peptide-1 Receptor Agonist on Bone Mineral Density and Bone Turnover Markers: A Meta-Analysis

AIMS

Glucagon-like peptide-1 receptor agonist (GLP-1RA) may promote bone formation, but conversely, they could also weaken bones due to the reduction in mechanical load associated with weight loss. However, the clinical effects in humans have not been clearly demonstrated. This meta-analysis aimed to evaluate whether GLP-1RAs affect BMD and bone turnover markers.

MATERIAL AND METHODS

PubMed, Embase, and Scopus were searched on June 13, 2024. The eligibility criteria were: (1) human studies, (2) receiving a GLP-1RA for more than 4 weeks, (3) an untreated control group or a placebo group, (4) reporting of at least one BMD or bone turnover marker, and (5) an RCT design. The risk of bias was assessed using the Cochrane risk of bias 2 tool. Fixed- or random-effects meta-analysis was performed according to heterogeneity.

RESULTS

Seven studies were included in the meta-analysis. GLP-1RAs did not significantly change BMD in the femoral neck (mean difference [MD], 0.01 g/cm2; 95% CI, -0.01-0.04 g/cm2), in the total hip (MD, -0.01 g/cm2; 95% CI, -0.02-0.01 g/cm2), and in the lumbar spine (MD, 0 g/cm2; 95% CI, -0.02-0.02 g/cm2). C-terminal telopeptide of type 1 collagen (CTX), a bone resorption marker, significantly increased after GLP-1RA treatment (MD, 0.04 μg/L; 95% CI, 0.01-0.07 μg/L). GLP-1RAs did not significantly change bone formation markers such as procollagen type 1 N-terminal propeptide, bone-specific alkaline phosphatase, osteocalcin.

CONCLUSIONS

GLP-1RA did not affect BMD and bone formation markers. However, GLP-1RAs led to a significant increase in CTX.

Effects of percutaneous kyphoplasty combined with zoledronic acid injection on osteoporotic vertebral compression fracture and bone metabolism indices

BACKGROUND

Osteoporotic vertebral compression fracture (OVCF) is usually treated by percutaneous kyphoplasty (PKP) which has limitations. We aimed to evaluate the effects of PKP combined with zoledronic acid (ZOL) injection on OVCF and bone metabolism indices.

METHODS

A total of 600 OVCF patients admitted from June 2015 to June 2020 were randomly divided into group A (PKP alone), group B (PKP combined with ZOL 1 month later) and group C (PKP concurrently combined with ZOL) (N.=200). Before as well as 1 month (before ZOL treatment in group B) and 1 year after PKP, the pain degree, physical function and self-care ability in daily life were assessed, the height and kyphosis Cobb angle of vertebral body with compression fracture and bone mineral densities (BMDs) at different parts were measured, the clinical efficacy, adverse reactions and recurrence of vertebral fractures during 3 years of follow-up were observed, and the serum levels of BAP, BGP, β-CTx and TP1NP were detected.

RESULTS

Compared with groups A and B, group C had significantly reduced visual analogue scale (VAS) and Oswestry disability index (ODI) scores and raised activity of daily living (ADL) score 1 month after PKP (P<0.05). Groups A-C had successively lowered VAS and ODI scores and elevated ADL Score 1 year after PKP (P<0.05). Compared with before PKP, the height of vertebral body with compression fracture significantly increased, and the kyphosis Cobb angle decreased in the three groups 1 month and 1 year after PKP (P<0.05). In group A, the height was lower whereas the angle was larger 1 year after PKP than those 1 month after PKP (P<0.05). One month after PKP, the height was significantly higher and the angle was smaller in group C than those of groups A and B (P<0.05). One year after PKP, the height significantly increased and the angle decreased successively in groups A-C (P<0.05). BMDs at different parts were significantly higher in group C than those of groups A and B 1 month after PKP (P<0.05). One year after PKP, BMDs were highest in group C and lowest in group A (P<0.05). The overall response rate was significantly higher in group C than that in group A (P<0.05). The recurrence rate of fractures was significantly higher in group A than those of groups B and C (P<0.05). The BAP, BGP, β-CTx and TP1NP levels were significantly lower in group C than those of groups A and B 1 month after PKP (P<0.05), and declined successively in groups A-C 1 year after PKP (P<0.05).

CONCLUSIONS

PKP concurrently combined with ZOL exert the most significant therapeutic effects on OVCF, with the lowest recurrence rate of fractures. It relieves pain and improves the physical function and self-care ability in daily life probably by reducing bone metabolism indices, increasing BMD, and maintaining the height and kyphosis Cobb angle of recovered vertebral body.

The Current Strategy in Hormonal and Non-Hormonal Therapies in Menopause—A Comprehensive Review

Menopause is a natural stage of hormonal aging in women, accompanied by a series of symptoms that reduce the quality of life of a fully active person. As no therapy is entirely satisfactory, the race for a better option is in full swing. Our study objective is to investigate the most recent menopause studies on pharmacological resources, emerging therapies, and the particularities of hormonal replacement therapy (HRT). For this purpose, a comprehensive search was conducted in two main databases (PubMed and Web of Science) guided by the specific keywords “menopause” and “therapy” or “estrogen” or “progesterone” or “hormone replacement” during the last ten years period. Studies were eligible if they met certain criteria: randomized controlled trials (RCT) in adult women with menopause and hormonal or non-hormonal therapies. We selected 62 RCTs, which are focused on four main topics: (a) epidemiology of menopause-related symptoms, (b) hormonal replacement therapy (HRT) selective estrogen receptor modulators, (c) emerging therapies, and (d) menopause. HRT has proven a real health benefit for menopausal women; besides, complementary interventions must be considered. Further studies are needed on menopause and menopause-related therapies. The continuous updating of clinical experience will strengthen the therapeutic benefit and the decision to treat patients safely. This goal will fully access all therapeutic resources to address an unresolved health issue of active adult women.

Alendronate prolongs the reversal-resorption phase in human cortical bone remodeling

Despite their ability to reduce fracture-risk and increase Bone Mineral Density (BMD) in osteoporotic women, bisphosphonates are reported to reduce formation of new bone. Reduced bone formation has been suggested to lead to accumulation of microfractures and contribute to rare side effects in cortical bone such as atypical femur fractures. However, most studies are limited to trabecular bone. In this study, the cortical bone remodeling in human iliac bone specimens of 65 non-treated and 24 alendronate-treated osteoporotic women was investigated using a new histomorphometric classification of intracortical pores. The study showed that only 12.4 ± 11% of the cortical pore area reflected quiescent pores/osteons in alendronate-treated patients versus 8.5 ± 5% in placebo, highlighting that new cortical remodeling events remain to be activated. The percent and size of eroded pores (events in resorption-reversal phase) remained unchanged, but their contribution to total pore area was 1.4-fold higher in alendronate versus placebo treated patients (66 ± 22% vs 48 ± 22%, p < 0.001). On the other hand, the mixed eroded-formative pores (events with mixed resorption-reversal-formation phases) was 2-fold lower in alendronate versus placebo treated patients (19 ± 14% vs 39 ± 23% of total pore area, p < 0.001), and formative pores (event in formation phase) was 2.2-fold lower in alendronate versus placebo treated patients (2.1 ± 2.4% vs 4.6 ± 3.6%, p < 0.01), and their contribution to total pore area was 2.4-fold lower (1.3 ± 2.1% vs 3.1 ± 4.4%, p < 0.05). Importantly, these differences between alendronate and placebo treated patients were significant in patients after 3 years of treatment, not after 2 years of treatment. Collectively, the results support that cortical remodeling events activated during alendronate treatment has a prolonged reversal-resorption phase with a delayed transition to formation, becoming increasingly evident after 3-years of treatment. A potential contributor to atypical femur fractures associated with long-term bisphosphonate treatment.

Effects of periodontal and bisphosphonate treatment on the gingival crevicular levels of sclerostin and dickkopf-1 in postmenopausal osteoporosis with and without periodontitis

OBJECTIVE AND BACKGROUND

Both periodontitis and osteoporosis are associated with osteoclast-related bone resorption. Bone metabolism is regulated by wingless-type MMTV integration site family (WNT), and WNT/β-catenin signals are controlled by physiological antagonists including dickkopf-1 (DKK-1) and sclerostin (SOST). This study examined the effects of periodontal and bisphosphonate (BP) treatment on the gingival crevicular fluid (GCF) sclerostin (SOST) and dickkopf-related protein-1 (DKK-1) levels in osteoporotic and systemically healthy postmenopausal women with and without periodontitis.

MATERIALS AND METHODS

A total of 48 postmenopausal women were divided into 4 groups (n = 12) according to periodontal health and osteoporosis status, as follows: Group OP/P: subjects with both osteoporosis and periodontitis; Group P: systemically healthy subjects with periodontitis; Group OP: periodontally healthy subjects with osteoporosis; Group H: systemically and periodontally healthy controls. Clinical data and GCF SOST and DKK-1 levels of the participants were collected at baseline and at 6 and 12 months following the initiation of periodontal and/or BP treatment in the experimental groups. GCF SOST and DKK-1 data were obtained by ELISA.

RESULTS

Clinical improvements were observed in all experimental groups. GCF SOST and DKK1 baseline levels varied significantly between groups due to periodontal disease (p < .001). Following treatment, significant increases in SOST and DKK-1 concentrations and significant decreases in total amounts of SOST were observed in both periodontitis groups (OP/P, P). However, while total amounts of DKK-1 decreased in Group OP/P, in Group P, these amounts had significantly increased at 12 months post-treatment (p < .05). At both 6 and 12 months post-treatment, SOST and DDK1 total amounts in Groups OP/P, OP, and H were similar (p > .05), whereas significant differences were observed between Groups H and P, indicating a deviation from periodontal health in Group P (p < .01).

CONCLUSIONS

Significant changes in GCF SOST and DKK-1 levels were observed among women with osteoporosis who received both periodontal and BP treatment. A more detailed examination of how these treatment protocols can be combined may lead to new therapeutic approaches towards periodontal disease.

Serum biomarkers for bisphosphonate-related osteonecrosis of the jaw: a prospective clinical study

In this prospective study, serum levels of 12 possible biomarkers were compared between osteonecrosis of the jaw (ONJ) and control groups, before and after dentoalveolar surgery. The results suggest that patients with abnormal serum levels of specific biomarkers should be monitored closely for the prevention and early diagnosis of ONJ.

INTRODUCTION

Bisphosphonate-related osteonecrosis of the jaw (ONJ) is an adverse effect of long-term bisphosphonate therapy. This study aimed to identify bone biomarkers for ONJ risk assessment and diagnosis.

METHODS

This prospective study included patients with histories of bisphosphonate therapy without current ONJ who were in need of dentoalveolar surgery of the jaw area. Serum levels of 12 possible bone markers, selected based on their involvement in ONJ pathogenesis, were compared between ONJ and control groups before dentoalveolar surgery (T0), at 8 postoperative weeks (T1), and at 4 months after diagnosis(T2).

RESULTS

Seventy-six patients who met the inclusion criteria were included in the study; 33 were assigned to the ONJ group, and 43 patients without ONJ signs or symptoms after dentoalveolar surgery were assigned to the control group. In the ONJ group, at both T0 and T1, the mean tartrate-resistant acid phosphatase isoform 5b (TRACP 5b) levels were significantly lower and the mean Dickkopf-related protein 1 (DKK1) levels were significantly higher than the corresponding values for the control group. Linear mixed model analysis revealed significant group effects over time for serum TRACP 5b and DKK1 after adjusting for demographic, pharmacological, and diagnostic variables. Lower serum levels of TRACP 5b under a specified cut-off value (≤ 2.899 U/L) at T0 indicated a 20.40-fold increased risk of ONJ development.

CONCLUSION

Patients with abnormally low serum levels of TRACP 5b and high serum levels of DKK1 should be monitored closely before and after dentoalveolar surgery for the prevention and early diagnosis of ONJ.

Low sclerostin levels after long-term remission of acromegaly

PURPOSE

Bone health is compromised in acromegaly resulting in vertebral fractures (VFs), regardless of biochemical remission. Sclerostin is a negative inhibitor of bone formation and is associated with increased fracture risk in the general population. Therefore, we compared sclerostin concentrations between well-controlled acromegaly patients and healthy controls, and assessed its relationship with bone mineral density (BMD), and VFs in acromegaly.

METHODS

Seventy-nine patients (mean age 58.9 ± 11.4 years, 49% women) with controlled acromegaly, and 91 healthy controls (mean age 51.1 ± 16.9 years, 59% women) were included. Plasma sclerostin levels (pg/mL) in patients were measured with an ELISA assay, whereas in controls, serum levels were converted to plasma levels by multiplication with 3.6. In patients, VFs were radiographically assessed, and BMD was assessed using dual X-ray absorptiometry.

RESULTS

Median sclerostin concentration in controlled acromegaly patients was significantly lower than in healthy controls (104.5 pg/mL (range 45.7-234.7 pg/mL) vs 140.0 pg/mL (range 44.8-401.6 pg/mL), p < 0.001). Plasma sclerostin levels were not related to age, current growth hormone (GH) or insulin-like factor-1 (IGF-1) levels, gonadal state, treatment modality, remission duration, or BMD, VF presence, severity or progression.

CONCLUSION

Patients with long-term controlled acromegaly have lower plasma sclerostin levels than healthy controls, as a reflection of decreased osteocyte activity. Further longitudinal studies are needed to establish the course of sclerostin during different phases of disease and its exact effects in acromegalic osteopathy.

Relationship Between Changes in Serum Levels of Intact Parathyroid Hormone and Sclerostin After a Single Dose of Zoledronic Acid: Results of a Phase 1 Pharmacokinetic Study

Although changes in serum sclerostin levels at 12 months after infusion of zoledronic acid have been reported, the changes in sclerostin levels at earlier time points are poorly understood. We reanalyzed the study data of a previous phase 1 pharmacokinetic study and investigated the correlation between changes in sclerostin levels and relevant factors in calcium metabolism. A total of 24 Japanese female subjects with primary postmenopausal osteoporosis were administered a single 4- or 5-mg dose of zoledronic acid. Serum and urine samples were collected on days 15, 29, 90, 180, and 365 after administration. Serum levels of calcium, phosphate, intact parathyroid hormone (iPTH), and sclerostin were measured. Levels of serum sclerostin were unchanged from baseline on days 15 and 29, but increased significantly on day 90, subsequently decreased significantly on day 180, and returned to baseline levels on day 365. A significant negative correlation was observed between changes in iPTH levels at early time points and sclerostin levels at later time points. This suggests that sclerostin was negatively regulated by iPTH, and the decrease in sclerostin may indicate the start of bone formation during later time points after zoledronic acid injection.

Glucocorticoid therapy suppresses Wnt signaling by reducing the ratio of serum Wnt3a to Wnt inhibitors, sFRP-1 and Wif-1

OBJECTIVE

Our previous study suggested that suppression of Wnt/β-catenin signaling by increasing serum Wnt co-receptor inhibitors, sclerostin and Dickkopf-1, impairs bone formation in the first week after starting glucocorticoid therapy. The objective of this study was to investigate the involvement of the Wnt/β-catenin signaling pathway and its clinical significance in the subsequent suppression of bone formation.

METHODS

A total of 53 patients with systemic autoimmune diseases who received initial glucocorticoid therapy with prednisolone (30-60 mg daily) were prospectively enrolled. We measured serum levels of Wnt3a and Wnt inhibitors, secreted Frizzled-related protein 1 (sFRP-1) and Wnt inhibitory factor 1 (Wif-1), before starting glucocorticoid therapy and every week for 4 weeks after its initiation.

RESULTS

Serum levels of sFRP-1 and Wif-1 slightly decreased compared with before glucocorticoid therapy from the second week. The serum Wnt3a level decreased from the first week. The ratios of Wnt3a to sFRP-1 and that of Wnt3a to Wif-1 both decreased from the first week onward.

CONCLUSION

The reduction of the ratio of Wnt3a to Wnt inhibitors, sFRP-1 and Wif-1, suppresses Wnt signaling, which may result in impaired bone formation. Taken together with our previous studies, glucocorticoids may suppress Wnt signaling by inhibiting co-receptors of the Wnt/β-catenin signaling pathway in the early phase of glucocorticoid therapy and inhibiting its ligand in the subsequent weeks, which together impair bone formation. Key Points • The decrease in Wnt pathway-related molecules by glucocorticoids impairs bone formation. • Glucocorticoids inhibit co-receptors of Wnt signaling in the early phase of therapy. • Glucocorticoids inhibit ligands of Wnt signaling in the subsequent phase of therapy.

Osteoporosis in Inflammatory Arthritides: New Perspective on Pathogenesis and Treatment

Osteoporosis is a skeletal disorder characterized by impaired bone strength and increased risk of fragility fracture and is among the most relevant comorbidities of rheumatic diseases. The purpose of the present review is to discuss the pathogenesis of local and systemic bone involvement in inflammatory arthritides, especially Rheumatoid Arthritis, Psoriatic Arthritis, and Spondyloarthritides, as well as the effect of anti-rheumatic treatments and anti-osteoporotic medication on bone health and fracture incidence, including recent data on novel therapeutic perspective.

Sclerostin and Vascular Pathophysiology

There is cumulating evidence for a contribution of Wnt signaling pathways in multiple processes involved in atherosclerosis and vascular aging. Wnt signaling plays a role in endothelial dysfunction, in the proliferation and migration of vascular smooth muscle cells (VSMCs) and intimal thickening. Moreover, it interferes with inflammation processes, monocyte adhesion and migration, as well as with foam cell formation and vascular calcification progression. Sclerostin is a negative regulator of the canonical Wnt signaling pathway and, accordingly, the consequence of increased sclerostin availability can be disruption of the Wnt signalling cascade. Sclerostin is becoming a marker for clinical and subclinical vascular diseases and several lines of evidence illustrate its role in the pathophysiology of the vascular system. Sclerostin levels increase with aging and persist higher in some diseases (e.g., diabetes, chronic kidney disease) that are known to precipitate atherosclerosis and enhance cardiovascular risk. Current knowledge on the association between sclerostin and vascular diseases is summarized in this review.

Zoledronate Slows Weight Loss and Maintains Fat Mass in Osteopenic Older Women: Secondary Analysis of a Randomized Controlled Trial

Studies in mice have suggested that osteocalcin plays an important role in glucose and fat metabolism. Since anti-resorptive drugs reduce circulating levels of osteocalcin they might be associated with increased fat mass and an increased risk of diabetes. Positive changes in body weight have been found in trials of alendronate and denosumab, but no significant effect in a previous trial of zoledronate. Whether those weight differences were in fat or lean mass is unknown. There were no effects of anti-resorptive treatments on fasting glucose concentrations or incidence of diabetes in those three studies. We have used our recent trial comparing zoledronate and placebo over 6 years in 2000 older osteopenic women to re-examine these questions. Both treatment groups lost body weight during the study (placebo 1.65 kg, zoledronate 1.05 kg), and this was significantly greater in the placebo group (P = 0.01). Both groups lost lean mass, and this loss was marginally (0.17 kg) but significantly (P = 0.02) greater in those receiving zoledronate. The placebo group had a mean loss of fat mass of 0.63 kg but there was no change in fat mass in the zoledronate group (between-groups comparison, P = 0.007). In the placebo group, there were 20 new diagnoses of diabetes, and in the zoledronate group, 19 (P = 0.87). Zoledronate prevented age-related loss of fat mass in these late postmenopausal women. The present study is the first to document a significant effect of zoledronate treatment on body weight, confirming results previously found with alendronate and denosumab. It also demonstrates that this is principally an effect to maintain fat mass rather than influencing lean mass, raising an important physiological question as to how anti-resorptive drugs have this effect on intermediary metabolism. It is possible that this anti-catabolic action contributes to the beneficial effects of anti-resorptive drugs on bone and longevity.

Changes in Dkk-1, sclerostin, and RANKL serum levels following discontinuation of long-term denosumab treatment in postmenopausal women

PURPOSE

The positive effects of denosumab (DMAb) on bone mineral density (BMD) are quickly reversible after its discontinuation. We investigated whether this rebound was associated with dysregulation of the Wnt canonical pathway and/or by the increase in the receptor-activator of nuclear factor-kappa B ligand (RANKL) serum levels.

METHODS

The study included patients (n = 15) with postmenopausal osteoporosis to whom DMAb was administered for 78 months and then discontinued. We collected BMD data at baseline/month 0 (M0), M60, M84 (6 months after last DMAb administration, coinciding when the next DMAb dose would typically be due), and after 3 and 12 months of follow-up (FU-M3 and FU-M12, respectively). Serum C-terminal telopeptide of type 1 collagen (CTX-I), Dickkopf-1 (Dkk-1), and sclerostin were measured at M0, M60, M84, FU-M3, and FU-M12. Serum N-terminal propeptide of type 1 procollagen (PINP) and RANKL were dosed at M60, M84, FU-M3, and FU-12.

RESULTS

We found a significant decrease in the T-score at all sites at FU-M12, when compared to M84 (-0.51 ± 0.91 at the lumbar spine; -0.72 ± 0.33 at the total hip; and -0.42 ± 0.27 at the femoral neck, p < 0.05). After DMAb discontinuation (M84 vs FU M12) CTX-I, PINP increased already at FU-M3 (+0.921 ± 0.482 ng/mL, +126.60 ± 30.36 ng/mL, respectively, p < 0.01), RANKL increased at FU-M12 (+0.041 ± 0.062 ng/mL, p < 0.05), while Dkk-1 and sclerostin decreased at FU-M12 (-10.90 ± 11.80 and - 13.00 ± 10.52 pmol/L, respectively, p < 0.01). No changes in BMD or any of the markers were found between M60 and M84.

CONCLUSIONS

RANKL serum levels progressively increased after discontinuation of long-term DMAb while Dkk-1 and sclerostin serum levels decreased. The increase in RANKL serum levels supports the hypothesis of a sudden loss of inhibition of the resting osteoclast line after DMAb clearance, with a hyperactivation of these cells. Our results suggest that the changes in serum Wnt inhibitors after DMAb suspension might represent a mere feedback response to the increased bone turnover.

Retention of osteocytic micromorphology by sclerostin antibody in a concurrent ovariectomy and functional disuse model

Prolonged mechanical unloading in bedridden patients and concurrent hormonal dysregulation represents the cause of one of the severest forms of osteoporosis, a condition for which there are very few efficacious interventions available to date. Sclerostin, a Wnt antagonist, acts as a negative regulator of bone formation. Sclerostin antibody (Scl-Ab)-mediated blockade of sclerostin can dramatically enhance bone formation and reduce bone resorption. This study was designed to investigate the therapeutic effect of the Scl-Ab on severe bone loss induced by concurrent mechanical unloading and estrogen deficiency in a hindlimb-suspended and ovariectomized rat model, and to study the cellular mechanisms underlying severe osteoporosis and Scl-Ab action. Unloading and ovariectomy resulted in severe loss of trabecular and cortical bone mass and strength; Scl-Ab can significantly counteract the deterioration of bone in unloaded and/or ovariectomized rats, with noticeably increased cortical bone formation. Scanning electron microscopy analysis revealed that unloading and ovariectomy lead to multiple morphological and structural abnormalities of osteocytes in cortical bone and the abnormalities were abolished by Scl-Ab administration. This study extends our previous conclusion that Scl-Ab represents a promising therapeutic approach for severe bone loss that occurs after being exposed to estrogen deficiency and prolonged mechanical unloading.

Is vitamin D deficiency a risk factor for osteonecrosis of the jaw in patients with cancer? A matched case-control study

PURPOSE

A previous case-control histomorphometric study showed higher odds of osteomalacia in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Vitamin D deficiency causes osteomalacia and may therefore be involved in the pathogenesis of BRONJ. The present case-control study aimed at testing such hypothesis.

MATERIALS AND METHODS

BRONJ+ and BRONJ- patients treated with bisphosphonates were matched by sex (same) and age (within 5 years). Serum 25-hydroxy-vitamin D (25-OH-D), parathyroid hormone, bone alkaline phosphatase, total procollagen type 1 amino-terminal propeptide, carboxy-terminal collagen crosslinks, Dickkopf WNT signaling pathway inhibitor 1 and sclerostin were measured.

RESULTS

The main outcome was vitamin D deficiency defined as 25-OH-D < 50 nmol/l. A total of 51 BRONJ+ and 73 BRONJ- patients were studied. The frequency (95% CI) of vitamin D deficiency was 59% (45%-72%) in BRONJ+ and 62% (48%-75%) in BRONJ- patients. This amounts to a difference of -3% (-22%-16%, p = 0.77) for BRONJ+ patients. Serum 25-hydroxy-vitamin D and parathyroid hormone were similar in BRONJ+ and BRONJ- patients. Among the bone metabolism markers, only sclerostin differed between the two groups, being higher in BRONJ+ patients.

CONCLUSION

The present matched case-control study suggests that vitamin D deficiency is not a risk factor for BRONJ.

Role of Osteocytes in Myeloma Bone Disease: Anti-sclerostin Antibody as New Therapeutic Strategy

Osteocytes are terminally differentiated cells of the osteoblast lineage. They are involved in the regulation of bone remodeling by increasing osteoclast formation or decreasing bone formation by the secretion of the osteoblast inhibitor sclerostin. Monoclonal antibody anti-sclerostin, Romosozumab, has been developed and tested in clinical trials in patients with osteoporosis. In the last years, the role of osteocytes in the development of osteolytic bone lesions that occurs in multiple myeloma, have been underlined. Myeloma cells increase osteocyte death through the up-regulation of both apoptosis and autophagy that, in turn, triggers osteoclast formation, and activity. When compared to healthy controls, myeloma patients with bone disease have higher osteocyte cell death, but the treatment with proteasome inhibitor bortezomib has been shown to maintain osteocyte viability. In preclinical mouse models of multiple myeloma, treatment with blocking anti-sclerostin antibody increased osteoblast numbers and bone formation rate reducing osteolytic bone lesions. Moreover, the combination of anti-sclerostin antibody and the osteoclast inhibitor zoledronic acid increased bone mass and fracture resistance synergistically. However, anti-sclerostin antibody did not affect tumor burden in vivo or the efficacy of anti-myeloma drugs in vitro. Nevertheless, the combination therapy of anti-sclerostin antibody and the proteasome inhibitor carfilzomib, displayed potent anti-myeloma activity as well as positive effects on bone disease in vivo. In conclusion, all these data suggest that osteocytes are involved in myeloma bone disease and may be considered a novel target for the use of antibody-mediated anti-sclerostin therapy also in multiple myeloma patients.

Effects of Single Vitamin D₃ Injection (200,000 Units) on Serum Fibroblast Growth Factor 23 and Sclerostin Levels in Subjects with Vitamin D Deficiency

BACKGROUND

Vitamin D deficiency remains common in all age groups and affects skeletal and non-skeletal health. Fibroblast growth factor 23 is a bone-derived hormone that regulates phosphate and 1,25-dihydroxyvitamin D homeostasis as a counter regulatory factor. 1,25-Dihydroxyvitamin D stimulates fibroblast growth factor 23 synthesis in bone, while fibroblast growth factor 23 suppresses 1,25-dihydroxyvitamin D production in the kidney. The aim of this study was to evaluate the effects of vitamin D₃ intramuscular injection therapy on serum fibroblast growth factor 23 concentrations, and several other parameters associated with bone metabolism such as sclerostin, dickkopf-1, and parathyroid hormone.

METHODS

A total of 34 subjects with vitamin D deficiency (defined by serum 25-hydroxyvitamin D levels below 20 ng/mL) were randomly assigned to either the vitamin D injection group (200,000 units) or placebo treatment group. Serum calcium, phosphate, urine calcium/creatinine, serum 25-hydroxyvitamin D, fibroblast growth factor 23, sclerostin, parathyroid hormone, and dickkopf-1 levels were serially measured after treatment.

RESULTS

Comparing the vitamin D injection group with the placebo group, no significant changes were observed in serum fibroblast growth factor 23, parathyroid hormone, or dickkopf-1 levels. Serum sclerostin concentrations transiently increased at week 4 in the vitamin D group. However, these elevated levels declined later and there were no statistically significant differences as compared with baseline levels.

CONCLUSION

Serum fibroblast factor 23, sclerostin, parathyroid hormone, and dickkopf-1 levels were not affected significantly by single intramuscular injection of vitamin D₃.

Bone Formation Is Coupled to Resorption Via Suppression of Sclerostin Expression by Osteoclasts

Bone formation is coupled to bone resorption throughout life. However, the coupling mechanisms are not fully elucidated. Using Tnfrsf11b-deficient (OPG^-/- ) mice, in which bone formation is clearly coupled to bone resorption, we found here that osteoclasts suppress the expression of sclerostin, a Wnt antagonist, thereby promoting bone formation. Wnt/β-catenin signals were higher in OPG^-/- and RANKL-transgenic mice with a low level of sclerostin. Conditioned medium from osteoclast cultures (Ocl-CM) suppressed sclerostin expression in UMR106 cells and osteocyte cultures. In vitro experiments revealed that osteoclasts secreted leukemia inhibitory factor (LIF) and inhibited sclerostin expression. Anti-RANKL antibodies, antiresorptive agents, suppressed LIF expression and increased sclerostin expression, thereby reducing bone formation in OPG^-/- mice. Taken together, osteoclast-derived LIF regulates bone turnover through sclerostin expression. Thus, LIF represents a target for improving the prolonged suppression of bone turnover by antiresorptive agents. © 2017 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Treatment of OPG-deficient mice with WP9QY, a RANKL-binding peptide, recovers alveolar bone loss by suppressing osteoclastogenesis and enhancing osteoblastogenesis

Osteoblasts express two key molecules for osteoclast differentiation, receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG), a soluble decoy receptor for RANKL. RANKL induces osteoclastogenesis, while OPG inhibits it by blocking the binding of RANKL to RANK, a cellular receptor of RANKL. OPG-deficient (OPG^–/–) mice exhibit severe alveolar bone loss with enhanced bone resorption. WP9QY (W9) peptide binds to RANKL and blocks RANKL-induced osteoclastogenesis. W9 is also reported to stimulate bone formation in vivo. Here, we show that treatment with W9 restores alveolar bone loss in OPG^–/–mice by suppressing osteoclastogenesis and enhancing osteoblastogenesis. Administration of W9 or risedronate, a bisphosphonate, to OPG^–/–mice significantly decreased the osteoclast number in the alveolar bone. Interestingly, treatment with W9, but not risedronate, enhanced Wnt/β-catenin signaling and induced alveolar bone formation in OPG^–/–mice. Expression of sclerostin, an inhibitor of Wnt/β-catenin signaling, was significantly lower in tibiae of OPG^–/–mice than in wild-type mice. Treatment with risedronate recovered sclerostin expression in OPG^–/–mice, while W9 treatment further suppressed sclerostin expression. Histomorphometric analysis confirmed that bone formation-related parameters in OPG^–/–mice, such as osteoblast number, osteoblast surface and osteoid surface, were increased by W9 administration but not by risedronate administration. These results suggest that treatment of OPG^–/–mice with W9 suppressed osteoclastogenesis by inhibiting RANKL signaling and enhanced osteoblastogenesis by attenuating sclerostin expression in the alveolar bone. Taken together, W9 may be a useful drug to prevent alveolar bone loss in periodontitis.

Glucocorticoid therapy causes contradictory changes of serum Wnt signaling-related molecules in systemic autoimmune diseases

The objective of this study was to investigate the clinical significance of the Wnt/β-catenin signaling pathway in glucocorticoid-induced osteoporosis. A total of 91 patients with systemic autoimmune diseases who received initial glucocorticoid therapy with prednisolone (30-60 mg daily) were prospectively enrolled. We measured serum levels of N-terminal peptide of type I procollagen (P1NP), bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase isoform 5b (TRACP-5b), N-telopeptide cross-linked type I collagen (NTX), sclerostin, Dickkopf-1 (Dkk-1), and Wnt3a before starting glucocorticoid therapy and every week for 4 weeks after its initiation. The effects of dexamethasone on expression of mRNA and protein of sclerostin and Dkk-1 by cultured normal human osteoblasts (NHOst) were evaluated by RT-PCR and ELISA, respectively. Serum levels of sclerostin and Dkk-1 increased significantly by 1 week of glucocorticoid therapy and then decreased from the second week onward. Serum Wnt3a tended to decrease and serum P1NP showed a significant decrease. However, TRACP-5b was significantly elevated from the first week of treatment onwards. In vitro study, dexamethasone increased Dkk-1 mRNA expression in cultured NHOst, but sclerostin mRNA was not detected. Dexamethasone also increased Dkk-1 protein production by osteoblasts, whereas sclerostin protein was not detected. Bone formation might be impaired at least in the first week of the initiation of glucocorticoid therapy by increase of the serum Wnt signaling inhibitors; however, their reductions in the subsequent weeks were contradictory to the maintained suppression of the bone formation markers after glucocorticoid therapy for patients with systemic autoimmune diseases.

The relationship between postmenopausal women's sclerostin levels and their bone density, age, body mass index, hormonal status, and smoking and consumption of coffee and dairy products

PURPOSE

To investigate the relationship between postmenopausal women's sclerostin levels and bone density and the factors that may affect this relationship.

MATERIALS AND METHODS

135 postmenopausal patients' ages, BMIs, hormonal statuses, BMD values, and smoking, and consumption of coffee and dairy products were compared with their sclerostin levels.

RESULTS

No statistical relationship was found between sclerostin level and age in the group with osteoporosis (p = 0.204, r = -0.305). There was a positive, high-level relationship between sclerostin levels and BMI in the osteoporosis group and it was found to be statistically significant (p < 0.001, r = 0.786). No statistical relationship was found between sclerostin level and age in the non-osteoporosis group with (p = 0.496, r = -0.88). There was a positive, moderate relationship between sclerostin levels and BMI in the non-osteoporosis group and it was found to be statistically significant (p < 0.001, r = 0.505). No statistically significant relationship could be found between sclerostin levels and vitamin D (p = 0.723), PTH (p = 0.112), FSH (p = 0.795), E₂ (p = 0.627), TSH (p = 0.517), T₃ (p = 0.788), and T₄ (p = 0.664) blood levels. No significant difference was found among the groups formed by smoking, consumption of coffee and milk, and dairy products, either (p = 0.405; p = 0.626; p = 0.234, respectively). It was monitored that sclerostin's negative effect observed on BMD scores was independent from age; however, it had a positive correlation with BMI.

CONCLUSION

As blood sclerostin levels increase, bone mineral density decreases. This negative effect of sclerostin on bone density increases as BMI increases, too. Effects of sclerostin levels on bone density are independent from age, and they are not affect by levels of vitamin D: PTH, FSH, E₂ and thyroid hormones, and daily activities, such as smoking and consumption of coffee and milk and dairy products, either.

Teriparatide and denosumab combination therapy and skeletal metabolism

Several therapies are available for osteoporis. Understanding the bone turnover changes and their mutual realtionship gives an overall view and might lead to a target therapy INTRODUCTION: The aim of this study is to compare the changes in bone turnover markers in patients treated with either denosumab alone, teriparatide (TPTD) alone, or in a third therapeutic scheme, when TPTD was added to patients previously treated with denosumab.

METHODS

Fifty-nine women over 65 years old with severe postmenopausal osteoporosis (evidence of at least two moderate-severe vertebral fractures) were enrolled in the study. Serum samples were collected every 3 months. They were assayed for intact N-propeptide of type I collagen (P1NP), C-terminal telopeptide of type I collagen (CTX), intact parathyroid hormone (PTH), 25 hydroxy-vitamin D (25 OHD), Sclerostin (SOST), and Dickkopf-related protein 1 (DKK1). Bone mass density was assessed by dual-energy X-ray absorptiometry at the lumbar spine and at the total hip.

RESULTS

In the groups treated only with TPTD or with denosumab, bone turnover markers increased and decreased, respectively. In TPTD group, a later significant increase in DKK1 was observed, while in denosumab group, a progressive increase in SOST was associated with a progressive significant decrease in DKK1. In the group treated first with denosumab and in which TPTD was added 3 months later, both CTX and P1NP increased 3 months after the beginning of TPTD. The strong effect of denosumab on bone turnover seems to be reversed by TPTD treatment.

CONCLUSIONS

In this study, we showed that TPTD is able to express its biological activity even when bone turnover is fully suppressed by denosumab treatment. The combination therapy is associated with significant increases in both DKK1 and SOST.

Serum sclerostin levels in renal cell carcinoma patients with bone metastases

Sclerostin has been proposed as a potent inhibitor of bone formation. Sclerostin antibodies are under clinical development to treat osteoporosis and metastatic bone disease. Serum sclerostin level is elevated in multiple myeloma, an osteolytic malignancy, where it might serve as predictive marker for the use of sclerostin-directed antibodies. As renal cell carcinoma (RCC) patients often present with osteolytic metastases, we aimed to investigate serum sclerostin levels in RCC patients. Our study included 53 RCC patients (19 with bone metastases, 25 with visceral metastases and 9 with localized disease) and 53 age- and gender-matched non-osteoporotic controls. Frozen serum samples were subjected to sclerostin quantitative sandwich ELISA. The mean serum sclerostin levels of RCC patients and controls were 45.8 pmol/l and 45.1 pmol/l, respectively (p = 0.86). Analysis of variance showed no difference between the subgroups of RCC patients with regard to visceral or bone metastases or localized disease (p = 0.22). There was no significant association between eGFR (estimated glomerular filtration rate) and serum sclerostin levels in RCC patients (r = 0.05; p = 0.74) and controls (r = 0.06; p = 0.68). Our results indicate that serum sclerostin levels appear not to be a valuable biomarker to assess the occurrence of bone metastases in RCC patients.

Effects of salvianolate on bone metabolism in glucocorticoid-treated lupus-prone B6.MRL-Fas (lpr) /J mice

Aim

To investigate the bone-protective effects of salvianolate (Sal), a total polyphenol from Radix Salviae miltiorrhizae, on bone tissue in the spontaneous lupus-prone mouse model, B6.MRL-Fas^lpr/J, undergoing glucocorticoid (GC) treatment.

Methods

Fifteen-week-old female B6.MRL-Fas^lpr/J mice were administered either a daily dose of saline (lupus group), prednisone 6 mg/kg (GC group), Sal 60 mg/kg (Sal group); or GC plus Sal (GC + Sal group) for a duration of 12 weeks. Age-matched female C57BL/6J wild-type (WT) mice were used for control. Micro-computed tomography assessments, bone histomorphometry analysis, bone biomechanical test, immunohistochemistry and immunoblotting analysis for bone markers, and renal histology analysis were performed to support our research endeavor.

Results

Lupus mice developed a marked bone loss and deterioration of mechanical properties of bone due to an increase in bone resorption rather than suppression of bone formation. GC treatment strongly inhibited bone formation in lupus mice. Sal treatment significantly attenuated osteogenic inhibition, and also suppressed hyperactive bone resorption, which recovered the bone mass and mechanical properties of bone in both the untreated and GC-treated lupus mice.

Conclusion

The data support further preclinical investigation of Sal as a potential therapeutic strategy for the treatment of systemic lupus erythematosus-related bone loss.

Impaired bone remodeling in children with osteogenesis imperfecta treated and untreated with bisphosphonates: the role of DKK1, RANKL, and TNF-α

In this study, we investigated the bone cell activity in patients with osteogenesis imperfecta (OI) treated and untreated with neridronate. We demonstrated the key role of Dickkopf-1 (DKK1), receptor activator of nuclear factor-κB ligand (RANKL), and tumor necrosis factor alpha (TNF-α) in regulating bone cell of untreated and treated OI subjects. These cytokines could represent new pharmacological targets for OI.

INTRODUCTION

Bisphosphonates are widely used in the treatment of children with osteogenesis imperfecta (OI) with the objective of reducing the risk of fractures. Although bisphosphonates increase bone mineral density in OI subjects, the effects on fracture incidence are conflicting. The aim of this study was to investigate the mechanisms underlying bone cell activity in subjects with mild untreated forms of OI and in a group of subjects with severe OI treated with cycles of intravenous neridronate.

METHODS

Sclerostin, DKK1, TNF-α, RANKL, osteoprotegerin (OPG), and bone turnover markers were quantified in serum of 18 OI patients (12 females, mean age 8.86 ± 3.90), 8 of which were receiving cyclic intravenous neridronate, and 21 sex- and age-matched controls. The effects on osteoblastogenesis and OPG expression of media conditioned by the serum of OI patients and anti-DKK1 neutralizing antibody were evaluated. Osteoclastogenesis was assessed in cultures from patients and controls.

RESULTS

DKK1 and RANKL levels were significantly increased both in untreated and in treated OI subjects with respect to controls. The serum from patients with high DKK1 levels inhibited both osteoblast differentiation and OPG expression in vitro. High RANKL and low OPG messenger RNA (mRNA) levels were found in lymphomonocytes from patients. High amounts of TNF-α were expressed by monocytes, and an elevated percentage of circulating CD11b-CD51/CD61+ osteoclast precursors was observed in patients.

CONCLUSIONS

Our study demonstrated the key role of DKK1, RANKL, and TNF-α in regulating bone cell activity of subjects with OI untreated and treated with bisphosphonates. These cytokines could represent new pharmacological targets for OI patients.

Strong relationship between vitamin D status and bone mineral density in anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is associated with impaired bone health and low bone mineral density (BMD) as a consequence of an inadequate peak bone mass in adolescence and bone loss in young adulthood. The vitamin D status with its implications for bone health in patients affected by AN has only been examined previously in small studies.

OBJECTIVE

To evaluate the prevalence of vitamin D deficiency and test the hypothesis that patients with AN and vitamin D deficiency might have worse bone metabolism and lower bone density as compared with AN with adequate vitamin D repletion.

DESIGN

We analysed the vitamin D status and bone metabolism in a large cohort (n=89) of untreated patients affected by AN, with amenorrhoea.

RESULTS

Vitamin D deficiency is widespread in untreated patients with AN: 16.9% had 25OH vitamin D levels below 12 ng/ml, 36% below 20 ng/ml and 58.4% below 30 ng/ml. PTH values were higher and BMD at both femoral sites were lower in patients with vitamin D<20 ng/ml. Progressively higher values of BMD were observed by 4 ranks of 25 OH vitamin D values (severe deficiency: <12 ng/ml, deficiency: ≥12 ng/ml and <20 ng/ml, insufficiency: ≥20 and <30 ng/ml and normal: ≥30 ng/ml). In patients with severe vitamin D deficiency BMD at the hip were significantly lower than that measured in groups with values over 20 ng/ml (p<0.001 for trend). The level of significance did not change for values adjusted for BMI or body weight.

CONCLUSION

We found a strong relationship between vitamin D status and hip BMD values with additional benefits for those with 25OHD levels above 20 ng/ml. Our results support the design of a randomized placebo-controlled clinical trial on the effect of vitamin D on BMD in patients with AN. The second point, whether 25OHD should be above 20 or 30 ng/ml remains a discussion point.

Circulating sclerostin and estradiol levels are associated with inadequate response to bisphosphonates in postmenopausal women with osteoporosis

INTRODUCTION

The biological mechanisms associated with an inadequate response to treatment with bisphosphonates are not well known. This study investigates the association between circulating levels of sclerostin and estradiol with an inadequate clinical outcome to bisphosphonate therapy in women with postmenopausal osteoporosis.

METHODS

This case-control study is based on 120 Spanish women with postmenopausal osteoporosis being treated with oral bisphosphonates. Patients were classified as adequate responders (ARs, n=66, mean age 68.2±8 years) without incident fractures during 5 years of treatment, or inadequate responders (IRs, n=54, mean age 67±9 years), with incident fractures between 1 and 5 years of treatment. Bone mineral density (DXA), structural analysis of the proximal femur and structural/fractal analysis of the distal radius were assessed. Sclerostin concentrations were measured by ELISA and 17β-estradiol levels by radioimmunoassay based on ultrasensitive methods.

RESULTS

In the ARs group, sclerostin serum levels were significantly lower (p=0.02) and estradiol concentrations significantly higher (p=0.023) than in the IRs group. A logistic regression analysis was performed, including as independent variables in the original model femoral fracture load, 25 hydroxyvitamin D, previus history of fragility fracture, sclerostin and estradiol. Only previous history of fragility fracture (OR 14.04, 95% CI 2.38-82.79, p=0.004) and sclerostin levels (OR 1.11, 95% CI 1.02-1.20, p=0.011), both adjusted by estradiol levels remained associated with IRs. Also, sclerostin concentrations were associated with the index of resistance to compression (IRC) in the fractal analysis of the distal radius, a parameter on bone microstructure.

CONCLUSIONS

Sclerostin and estradiol levels are associated with the response to bisphosphonate therapy in women with postmenopausal osteoporosis.

Estrogen alone or in combination with parathyroid hormone can decrease vertebral MEF2 and sclerostin expression and increase vertebral bone mass in ovariectomized rats

The study is about the regulatory effects of estrogen and parathyroid hormone (PTH) on sclerostin, a protein that inhibits the Wnt/β-catenin pathway. The results indicate that estrogen may down-regulate sclerostin expression and that estrogen displays synergistic action with PTH. These results provide a new perspective on the relationship between estrogen and bone.

PURPOSE

To investigate whether estrogen can down-regulate SOST and MEF2 (myocyte enhancer factor 2) expression and whether co-treatment with estrogen and PTH has a stronger effect on suppressing SOST than PTH applied alone in ovariectomized rats.

METHODS

Forty-three-month-old virgin female Sprague-Dawley (SD) rats were ovariectomized and divided into four groups (n = 10). Another ten age-matched rats received sham operations as controls. After allowing 8 weeks for the development of vertebral osteopenia, the rats were administered the drug intervention. For this intervention, the estrogen group was subcutaneously injected with 17β-estradiol at 25 μg/kg body weight, the PTH group was injected with 80 μg/kg synthetic human PTH (1-34), and the co-treatment group was concurrently treated with PTH and estrogen at the above dosage. The OVX group and sham group were treated with vehicle. The drug treatment was conducted for 12 weeks. After the lumbar spine bone mineral density (BMD) was measured, the rats were sacrificed, and the lumbar spine and blood were collected for qPCR, Western blot, immunohistochemistry and other tests.

RESULTS

Estrogen can down-regulate MEF2 and sclerostin expression, and co-treatment with estrogen and PTH has a stronger effect on suppressing MEF2 and SOST mRNA than PTH alone. The co-treatment group displayed slightly higher bone mass and biomechanical properties than the PTH group, but the differences were not significant.

CONCLUSIONS

Estrogen appears to be a regulator of sclerostin, and the effect may involve suppressing MEF2s. Combined treatment with PTH and estrogen is not more beneficial for vertebral bone mass and strength than treatment with PTH alone in ovariectomized rats.

Distinct effect of zoledronate and clodronate on circulating levels of DKK1 and sclerostin in women with postmenopausal osteoporosis

The coupling of bone formation to bone resorption during treatment of postmenopausal osteoporosis with antiresorbers might be related to changes in Wnt/b-catenin signaling. We compared the effects of two bisphosphonate treatments on two Wnt-inhibitors Sclerostin (SOST) and Dickkopf-related protein 1 (DKK1). The study population included 74 women with postmenopausal osteoporosis participating simultaneously in two multicenter, placebo controlled trials. The patients were randomized to: intramuscular clodronate 100mg/week (CLO) (N=36), and yearly intravenous therapy with 5mg zoledronate (ZOL) (N=18) and placebo (N=20). Bone turnover markers (intact N-propeptide of type I collagen [P1NP], C-terminal telopeptide of type I collagen [CTX]) remained unchanged in the placebo group while they significantly decreased during treatment with the two bisphosphonates, versus both placebo and baseline. In CLO treated patients serum DKK1 remained stable over the entire period of observation while serum SOST levels increased significantly after 12months of treatment both versus placebo group (p<0,005), baseline (p<0,001) and ZOL treated group. In the ZOL group, DKK1 levels increased significantly within one month and for the following 6months and it fell back to baseline values at 12months. The second ZOL infusion was again associated with an increase in DKK1 a month later, although to a lesser extent. In conclusion, in this study we have found that the treatment of postmenopausal osteoporosis with intermittent yearly ZOL is associated with transient and declining increases in DKK1 while continuous treatment with CLO, results in a late increase in serum SOST. These preliminary results and further ad hoc studies might contribute to shed light on our understanding of the bone coupling effects taking place during treatment of osteoporosis with different anti-resorbers or with different treatment regimens.

Temporal changes in systemic and local expression of bone turnover markers during six months of sclerostin antibody administration to ovariectomized rats

Sclerostin (Scl) is an osteocyte protein that decreases bone formation, and its inhibition by neutralizing antibodies (Scl-Ab) increases bone formation, mass and strength. We investigated the effects of Scl-Ab in mature ovariectomized (OVX) rats with a mechanistic focus on longer-term responses of osteoclasts, osteoblasts and osteocytes. Four-month-old Sprague-Dawley rats had OVX or sham surgery. Two months later, sham controls received sc vehicle while OVX rats received vehicle (OVX-Veh) or Scl-Ab (25mg/kg) once weekly for 6 or 26weeks followed by necropsy (n=12/group). Terminal blood was collected for biochemistry, non-adherent marrow cells were harvested from femurs for ex vivo osteoclast formation assays, and vertebrae and tibiae were collected for dynamic histomorphometry and mRNA analyses. Scl-Ab treatment led to progressively thicker but fewer trabeculae in the vertebra, leading to increased trabecular bone volume and reduced trabecular surfaces. Scl-Ab also increased cortical bone volume in the tibia, via early periosteal expansion and progressive endocortical contraction. Scl-Ab significantly reduced parameters of bone resorption at week 6 relative to OVX-Veh controls, including reduced serum TRACP-5b, reduced capacity of marrow cells to form osteoclasts ex vivo, and >80% reductions in vertebral trabecular and tibial endocortical eroded surfaces. At week 26, serum TRACP-5b and ex vivo osteoclast formation were no longer reduced in the Scl-Ab group, but eroded surfaces remained >80% lower than in OVX-Veh controls without evidence for altered skeletal mRNA expression of opg or rankl. Scl-Ab significantly increased parameters of bone formation at week 6 relative to OVX-Veh controls, including increases in serum P1NP and osteocalcin, and increased trabecular, endocortical and periosteal bone formation rates (BFRs). At week 26, surface-referent trabecular BFR remained significantly increased in the Scl-Ab group versus OVX-Veh controls, but after adjusting for a reduced extent of trabecular surfaces, overall (referent-independent) trabecular BFR was no longer significantly elevated. Similarly, serum P1NP and osteocalcin were no longer significantly increased in the Scl-Ab group at week 26. Tibial endocortical and periosteal BFR were increased at week 6 in the Scl-Ab group versus OVX-Veh controls, while at week 26 only endocortical BFR remained increased. The Scl-Ab group exhibited significant increments in skeletal mRNA expression of several osteocyte genes, with sost showing the greatest induction in both the tibia and vertebra. We propose that Scl-Ab administration, and/or the gains in bone volume that result, may have increased osteocytic expression of Scl as a possible means of regulating gains in bone mass.

New developments in biological markers of bone metabolism in osteoporosis

Over the last 15 years several biological markers of bone turnover have been developed with increased specificity and sensitivity. In osteoporosis clinical studies, the IOF and IFCC organizations have recently recommended the measurements of serum type I collagen N-propeptide (PINP) and the crosslinked C-terminal telopeptide (serum CTX) as markers of bone formation and bone resorption, respectively. However these markers have some limitations including a lack of specificity for bone tissue, their inability to reflect osteocyte activity or periosteal apposition. In addition they do not allow the investigation of bone tissue quality an important determinant of skeletal fragility. To address these limitations, new developments in markers of bone metabolism have been recently achieved. These include assays for periostin, a matricellular protein preferentially localized in the periosteal tissue, sphingosine 1-phosphate, a lipid mediator which acts mainly on osteoclastogenesis and the osteocyte factors such as sclerostin and FGF-23. Recent studies have shown an association between the circulating levels of these biological markers and fracture risk in postmenopausal women or elderly men, although data require confirmation in additional prospective studies. Finally, recent studies suggest that the measurements of circulating microRNAs may represent a novel class of early biological markers in osteoporosis. It is foreseen that with the use of genomics and proteomics, new markers will be developed to ultimately improve the management of patients with osteoporosis.

Higher circulating parathormone is associated with smaller and weaker bones in obese children

Obese children have disadvantageous bone geometry, bone of low quality, and reduced strength at non-weight-bearing skeletal sites. The aim of our study was to investigate the role of parathormone (PTH) and the Wnt/β-catenin signaling pathway and its inhibitors, sclerostin and Dickkopf-1 (DKK1), as negative modulators of fat mass on bone. This was a cross-sectional observational study performed in 44 (26 males and 18 females) obese subjects, aged 11.41 ± 2.61 years. Thirty-seven normal-weight, healthy children (22 males and 15 females) of the same chronological age served as controls for the biochemical parameters and bone markers, while the data on bone geometry were evaluated according to our normative data obtained previously in a group of 325 control children. Digitalized X-rays were evaluated at the level of the second metacarpal bone for the determination of bone geometry: total cross-sectional area (TCSA), cortical area (CA), medullary area (MA), and bone strength (bending breaking resistance index [BBRI]). Serum bone markers (intact procollagen-1N-terminal propeptide [P1NP] and serum carboxy-terminal telopeptide of collagen-1 [CTX]), sclerostin, DKK1, PTH, 25-hydroxyvitamin D and were also measured. Data for TCSA, CA, MA, and BBRI are expressed as a standard deviation score in order to normalize them for age and sex. TCSA (mean ± SD, -2.92 ± 2.71), CA (-0.60 ± 0.82), MA (-0.45 ± 1.14), and BBRI (-2.65 ± 2.31) were all significantly smaller than in controls (p < 0.01). Serum PTH (36.27 ± 23.89 vs. 19.33 ± 11.37 pg/mL) and CTX (1.55 ± 0.44 vs. 1.34 ± 0.46 ng/mL) were significantly increased (p < 0.05) in the obese children compared to controls, while sclerostin was significantly decreased (24.67 ± 10.06 vs. 30.42 ± 11.01 pmol/L, p < 0.05). P1NP was also significantly increased (p < 0.01). PTH was negatively correlated with TCSA, CA, and BBRI. Bone turnover is higher in obese children than in controls, and this is associated with smaller and apparently weaker bones. Higher PTH and lower sclerostin levels may be responsible for these findings.

Bisphosphonates and bone quality

Bisphosphonates (BPs) are bone-avid compounds used as first-line medications for the prevention and treatment of osteoporosis. They are also used in other skeletal pathologies such as Paget's and metastatic bone disease. They effectively reduce osteoclast viability and also activity in the resorptive phase of bone remodelling and help preserve bone micro-architecture, both major determinants of bone strength and ultimately of the susceptibility to fractures. The chemically distinctive structure of each BP used in the clinic determines their unique affinity, distribution/penetration throughout the bone and their individual effects on bone geometry, micro-architecture and composition or what we call 'bone quality'. BPs have no clinically significant anabolic effects. This review will touch upon some of the components of bone quality that could be affected by the administration of BPs.

Circulating sclerostin in children and young adults with heritable bone disorders

CONTEXT

Sclerostin is an inhibitor of bone formation and is an important determinant of bone mass. The role of sclerostin in heritable metabolic bone disorders has not been studied in detail.

OBJECTIVE

We evaluated serum sclerostin levels in patients with X-linked hypophosphatemic rickets (XLH) and osteogenesis imperfecta (OI) and analyzed the relationship of circulating sclerostin concentrations with lumbar spine areal bone mineral density (LS-aBMD).

SETTING

The study was conducted in the metabolic bone clinic of a pediatric orthopedic hospital.

PATIENTS

Participants were 128 individuals, including 30 patients with XLH, 76 patients with OI types I, III, and IV, and 22 healthy subjects.

MAIN OUTCOME MEASURES

Sclerostin was quantified in serum samples.

RESULTS

Patients with XLH had higher circulating sclerostin concentrations (mean [SD]: 30.2 [16.7] pmol/L) than healthy control subjects (21.4 [9.2] ng/mL) (P = .02), as well as relatively high LS-aBMD Z-scores (+1.1 [1.7]). In the XLH cohort, serum sclerostin levels were positively associated with the LS-aBMD Z-score (r = 0.56; P < .002) and with alkaline phosphatase (r = 0.45; P = .01). In patients with OI, sclerostin serum levels were similar to those of healthy control subjects despite low LS-aBMD.

CONCLUSIONS

The elevated sclerostin serum levels in XLH and the normal concentrations in OI suggest that the bone mass abnormalities in these disorders are not caused by primary sclerostin dysregulation.

Effects of intravenous zoledronate and ibandronate on carotid intima-media thickness, lipids and FGF-23 in postmenopausal osteoporotic women

OBJECTIVE

Osteoporosis and atherosclerosis are interconnected entities and share also some pathophysiological mechanisms. Moreover, recent literature data have supported the hypothesis that bisphosphonates (BPs) may have some antiatherogenic actions. This study aimed to evaluate the effects of one year with zoledronate or ibandronate given intravenously on lipid profile and on carotid artery intima-media thickness (CA-IMT).

METHODS

Sixty postmenopausal osteoporotic women (mean age: 66.6±7.8years) were randomly assigned to 1-year treatment with zoledronate 5mg i.v. annually or ibandronate 3mg i.v. every 3 months. In all patients at baseline and after 12months we measured CA-IMT, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), 25-hydroxyvitamin D (25OHD), bone alkaline phosphatase (B-ALP), type I collagen β carboxy telopeptide (βCTX), osteocalcin (OC), fibroblast growth factor 23 (FGF-23) and sclerostin.

RESULTS

The osteoporotic women treated with zoledronate showed a greater reduction in CA-IMT than those treated with ibandronate. HDL-C and HDL-C/LDL-C ratio showed a significant (p<0.01) increase in the 2 groups, whereas, LDL-C showed a reduction in the two groups which, however, reached statistical significance (p<0.05) only in the zoledronate group. FGF-23 serum levels showed a similar and significant decrease in both the women treated with zoledronate and in those treated with ibandronate. At the end of the study period sclerostin serum levels showed a higher increase in the patients treated with zoledronate than in those treated with ibandronate.

CONCLUSION

In osteoporotic women both zoledronate and ibandronate given intravenously resulted in an increase in HDL-C/LDL-C ratio and a reduction of CA-IMT which was significant only for zoledronate. Further prospective studies are needed to clarify whether the change in FGF-23 and sclerostin levels is a marker or a potential mechanism of the action of BPs at a vascular level.

Role of sclerostin and dickkopf-1 in the dramatic alteration in bone mass acquisition in adolescents and young women with recent anorexia nervosa

BACKGROUND

The nutritional deprivation of adolescent girls with anorexia nervosa (AN) reduces bone mass acquisition. A better understanding of this process would improve the medical treatment of bone alteration and its long-term consequences.

OBJECTIVE

The first aim was to model the bone mass acquisition in young women with AN. The second aim was to identify the clinical and biological factors associated with bone demineralization and investigate the potential role of sclerostin and dickkopf-1 protein (DKK-1).

POPULATION AND METHODS

Ninety-eight AN patients (mean age 18.2 ± 2.6 years) and 63 age-matched controls were enrolled in this study. Areal bone mineral density (aBMD) was determined by dual-energy x-ray absorptiometry. Calciotropic hormones, bone turnover markers, sclerostin, DKK-1, and growth factors were concomitantly evaluated.

RESULTS

The aBMD was significantly reduced at all bone sites in AN patients vs controls (range, -3.3% at the radius to -12.1% for total proximal femur). Bone formation markers IGF-1 and DKK-1 were significantly decreased in AN patients, whereas PTH, sclerostin, and the bone resorption markers were increased. In patients, the AN duration, amenorrhea, weight, body mass index, fat mass, and fat-free soft tissue were negatively correlated with aBMD, whereas the age of AN onset was positively correlated. Multiple regression analysis revealed that the duration of amenorrhea was the independent factor most negatively associated with aBMD at all bone sites except the radius.

CONCLUSION

This case-control study demonstrated a dramatic reduction in aBMD, reinforced for the first time by our models, and indicates the need for early, systematic, and adapted bone mass monitoring. Moreover, appropriate treatment should be started early in patients with AN. Increased secretion of sclerostin suggests that it may be a target for pharmacological action.

The role of Wnt signaling and sclerostin in the pathogenesis of glucocorticoid-induced osteoporosis

Bone formation is suppressed in glucocorticoid-induced osteoporosis. One of the mechanisms by which glucocorticoids depress bone formation is through their effects on the Wnt/β-catenin signaling pathway, a critical regulator of osteoblastogenesis. Thus, Wnt signaling induces the differentiation of osteoblast precursors toward mature osteoblasts and prevents osteoblast and osteocyte apoptosis. Glucocorticoids increase the expression of Wnt signaling antagonists (sclerostin and Dkk-1) in experimental studies in rodents and cell cultures. However, the scarce data of their effects in humans are somewhat contradictory, probably due to the dose and duration of treatment as well as the characteristics of the patients. A progressive decrease in Dkk-1 serum levels and an increase in circulating sclerostin levels at long-term follow-up have recently been reported in patients treated with high doses of glucocorticoids. This review describes the most recent data on the effects of glucocorticoids on the Wnt signaling pathway, especially on their antagonists, sclerostin and Dkk-1.

Serum sclerostin levels are decreased in adult patients with different types of osteogenesis imperfecta

CONTEXT

There are no specific biochemical bone markers available for osteogenesis imperfecta (OI), and the role of sclerostin as a key regulator of bone formation in OI is unknown.

OBJECTIVES

We aimed to evaluate the role of sclerostin and its association with bone turnover markers as well as body composition parameters in adult patients with different types of OI.

DESIGN, SETTING, AND PARTICIPANTS

This was a case-control study in 27 adult patients and 50 healthy age- and gender-matched controls.

MAIN OUTCOME MEASURES

Serum sclerostin levels and bone turnover markers including serum osteocalcin, amino terminal propeptide of type I procollagen, and CrossLaps as well as body composition parameters were determined in mild OI stage I (OI-I) and moderate-severe OI stages III-IV (OI-III-IV), according to Sillence classification. Data were compared with healthy controls.

RESULTS

Sclerostin levels were significantly lower in OI-I (19.9 ± 10.9 pmol/L; P < .001) and OI-III-IV (13.3 ± 10.0 pmol/L; P < .001) compared with healthy adults (45.3 ± 14.9 pmol/L), even after adjustment for age, sex, bone mineral content, and body mass index. CrossLaps and PTH were significantly lower in OI-I (0.197 ± 0.15 ng/L; P = .007 and 33.7 ± 19.1 pg/L; P = .033, respectively) and OI-III-IV (0.221 ± 0.18 ng/L; P = .039, and 27.9 ± 14.7 pg/L; P = .001, respectively) than in healthy controls (0.322 ± 0.15 ng/L and 45.0 ± 16.6 pg/L). Amino-terminal propeptide of type I procollagen was below the reference range for OI-I and OI-III-IV. Patients with OI were shorter and lighter and had a decreased bone mineral content (P < .001) but similar fat distribution and lean body mass, compared with controls. Serum sclerostin levels were not related to any bone marker except osteocalcin, the number of prevalent fractures, or body composition readings.

CONCLUSION

Decreased sclerostin levels in OI might reflect a down-regulation or negative feedback mechanism to prevent further bone loss.

Changes in Dickkopf-1 (DKK1) and Sclerostin following a Loading Dose of Vitamin D 2 (300,000 IU)

Background. Vitamin D is important for bone health, although high loading doses have been associated with an increase in fracture risk. The mechanisms remain uncertain. Aim. We hypothesize that supraphysiological concentrations of 1,25 (OH)2 vitamin D may inhibit formation by increasing the production of Wnt inhibitors: sclerostin and DKK1. Subjects and Methods. We measured serum sclerostin and DKK1 in 34 patients (21 F, 13 M) aged mean (SD) 61.3 (15.6) years with vitamin D deficiency/insufficiency treated with a loading dose of vitamin D2 (300,000 IU) intramuscularly. Blood samples were taken at baseline and serially up to 3 months. Results. Serum 1,25 (OH)2 vitamin D increased markedly at 3 months (mean (SD) baseline 116 (63), 3 months : 229 (142) pmol/L, P < 0.001). There was a significant correlation between sclerostin and DKK1 at baseline (r = 0.504, P = 0.002) and at 3 months (r = 0.42, P = 0.013). A significant inverse correlation was observed between sclerostin and eGFR at 3 months (r = -0.494, P = 0.007). Sclerostin increased significantly at 3 months (P = 0.033). In a multilinear regression analysis with % change in sclerostin and DKK1 as dependent variable, a positive significant association was observed with % change in 1,25 (OH)2 vitamin D (P = 0.038), independent of changes in PTH and following correction for confounders such as age, gender, BMI, BMD and eGFR. Conclusions. Supraphysiological concentration in 1,25 (OH)2 vitamin D achieved following a loading dose of vitamin D increases sclerostin and may inhibit Wnt signalling. This may have detrimental effects on bone.

Teriparatide treatment in adult patients with osteogenesis imperfecta type I

Osteogenesis imperfecta (OI) is a hereditary disease characterized by low bone mass, increased bone fragility, short stature, and skeletal deformities. This study focuses on OI type I, the mildest form of the disease. Bisphosphonates represent the prevailing standard of care in patients with OI. Teriparatide (TPD) is a PTH analog with bone-anabolic actions which has been approved for osteoporosis treatment. Thirteen postmenopausal women with type I OI who had been on treatment with neridronate for at least 2 years and who incurred new vertebral fracture during treatment were treated with TPD for 18 months. Bone mineral density (BMD) increased significantly over 18 months up to 3.5 % at the lumbar spine (p = 0.001), while no significant changes were noted in hip BMD. Serum markers of bone formation and of bone resorption increased significantly during the treatment. The Wnt inhibitors serum dickkopf-1 (DKK1) and sclerostin were also measured. A nonsignificant increase was seen in serum sclerostin levels, while serum DKK1 rose gradually and significantly during TPD treatment. In patients affected by type I OI, TPD treatment is associated with a remarkable response in markers of bone formation. This suggests a normal osteoblastic response to TPD. However, the observed increases in BMD were somewhat lower than those in postmenopausal or senile osteoporosis treated with TPD for the same lag time. Our results open the possibility to develop TPD for the treatment of adult type I OI, but particularly for the lack of a control group, a properly designed controlled study is warranted.

Effect of glucocorticoid treatment on Wnt signalling antagonists (sclerostin and Dkk-1) and their relationship with bone turnover

The aim of this study was to analyse the effect of glucocorticoid therapy (GCCT) on Wnt signalling antagonists (sclerostin and Dkk-1) and their relationship with bone turnover. 25 patients (8 M/17 F, aged 48±19yrs) recently initiating GCCT (≥7.5mg/day, ≤6months) were prospectively included. Bone turnover markers (bone formation: P1NP, osteocalcin [OC], bone ALP; bone resorption: sCTx) and Wnt antagonists (serum sclerostin and Dkk-1) were assessed in all patients (short-term and 12months after initiating GCCT). Bone mineral density (BMD) was performed to assess osteoporosis. The results were compared with 60 healthy controls. At short-term patients on GCCT showed a significant decrease in bone formation markers versus controls (P1NP: 19±9 vs. 43±16ng/mL, p<0.001; OC: 7.4±2.4 vs. 18.4±5.2ng/mL, p=0.001) and in Dkk-1 levels (24.5±20.1 vs. 36.8±13.7pmol/L, p=0.008) with similar sclerostin values (41.8±21.8 vs. 42.1±13.9pmol/L, p=0.950). Sclerostin correlated positively with GCCT doses (r=0.449, p=0.024) and lumbar BMD (r=0.424, p=0.035), and negatively with bone ALP (r=-0.398, p=0.049). A progressive decrease in Dkk-1 levels was observed at 12months, (19.1±14.9, p=0.001), whereas sclerostin increased compared to controls (48.9±11.6, p=0.045). In conclusion, the effect of GCCT on the serum levels of the Wnt signalling parameters differs depending on the antagonist evaluated. Whereas sclerostin values increased and showed a relationship with the dose and bone AP, Dkk-1 levels decreased throughout the study suggesting a counter-regulatory mechanism of this factor thereby reducing the deleterious effect of GCCT in the bone.

Traditional and novel bone remodeling markers in premenopausal and postmenopausal women

CONTEXT

Bone turnover markers (BTMs) may identify changes in bone remodeling within a relatively short time interval before changes in bone mineral density can be detected. New markers such as osteoprotegerin, receptor activator of nuclear factor-κB ligand, and sclerostin have emerged, but there is little information about their potential use in clinical practice.

OBJECTIVES

The aim of this study was to analyze the ability of several BTMs to predict bone loss in pre- and postmenopausal women and to monitor the efficacy of treatment in osteoporotic women.

DESIGN, PATIENTS, AND SETTING

We performed an observational prospective study in pre- and postmenopausal ambulatory women (n = 72 and n = 152, respectively).

INTERVENTION

Postmenopausal women with osteoporosis (n = 18) were treated with risedronate and calcium. Women filled out a questionnaire and underwent bone mineral density measurement using dual-energy x-ray absorptiometry at the time of enrollment and after 1 year of follow-up. BTMs were measured at baseline, at 6 months, and after 1 year.

RESULTS

Increased levels of N-terminal propeptide of type 1 procollagen (P1NP) and β-type I collagen telopeptides (CTXs) were associated with low bone mineral density in the premenopausal (P = .02 and P = .04, respectively) and postmenopausal (P = .03 and P = .02) groups. The best analytical performance to diagnose osteoporosis was for β-CTX, osteocalcin, and P1NP, with areas under the curve of 0.70 (P = .005), 0.64 (P = .048), and 0.71 (P = .003). A significant decrease was found in P1NP, osteocalcin, tartrate-resistant acid phosphatase-5b, β-CTX, and bone alkaline phosphatase after 1 year of treatment (all P < .05).

CONCLUSIONS

Our data suggest that measurement of β-CTX and P1NP shows adequate analytical performance and could potentially be included in algorithms for the screening of osteoporosis. Furthermore, these two markers, along with osteocalcin and tartrate-resistant acid phosphatase-5b, are useful to monitor the response to risedronate.

Involvement of WNT/β-catenin signaling in the treatment of osteoporosis

Osteoblast differentiation is predominantly regulated by the WNT/β-catenin signaling (canonical WNT pathway), which, together with bone morphogenetic proteins, acts as the master regulator of osteogenesis. The recent characterization of the canonical WNT pathway in the regulation of bone modeling and remodeling provided important insights for our understanding of the pathophysiology of a number of conditions and of the mechanism of action of hormones or drugs with important effect on bone metabolism. This review is mainly focused on the growing therapeutic implications of these new findings. WNT/β-catenin signaling plays a key role in bone tissue by determining the differentiation of stem cells into mature osteoblasts rather than into chondrocytes and adipocytes. Its regulation is predominantly driven by the production of two WNT signaling antagonists: sclerostin (SOST) and Dickkopf-related protein 1 (DKK1). The most proximate regulator of SOST expression by osteocytes and its serum levels is bone mechanical load. SOST expression is increased with advancing age, by glucocorticoid treatment and during treatment with antiresorptive agents such as bisphosphonates and denosumab, while it is decreased by parathyroid hormone excess or administration of estrogens. Correlation between DKK1 serum levels and bone formation in various pathological conditions or during osteoporosis treatment has been reported. Inhibitors of the negative regulators of WNT/β-catenin signaling ("inhibiting the endogenous inhibitors") are potential candidates for the prevention and treatment of bone loss. Inactivating monoclonal antibodies against SOST appears to be the most attractive strategy because SOST is the only component of the WNT pathway expressed almost exclusively by osteocytes.

Combination therapy with risedronate and teriparatide in male osteoporosis

Most studies of combination therapy with teriparatide and a bisphosphonate have not shown greater efficacy over monotherapy. The bisphosphonate risedronate, has not been studied in this context. The purpose of this proof-of-concept study was to assess whether combination risedronate and teriparatide increases bone mineral density (BMD) more than monotherapy with either drug alone. This was a randomized, double-blinded study of risedronate (35 mg weekly plus placebo injection), teriparatide (20 μg subcutaneously daily plus placebo tablet), or both risedronate plus teriparatide (combination) for 18 months in 29 men with low BMD. The primary endpoint was percentage change in lumbar spine (LS) BMD at 18 months. Secondary outcomes included changes in bone markers and BMD at other sites and interim time-points. All therapies increased LS BMD as compared with baseline (p < 0.05), but there were no between-group differences at 18 months. Total hip (TH) BMD increased to a greater extent in the combination group (mean ± SEM, 3.86 ± 1.1 %) versus teriparatide (0.29 ± 0.95 %) or risedronate (0.82 ± 0.95 %; p < 0.05 for both). Femoral neck (FN) BMD also increased more in the combination group (8.45 ± 1.8 %) versus risedronate (0.50 ± 1.7 %; p = 0.002), but was not different from teriparatide alone. In the combination group, P1NP and CTX increased rapidly, mirroring the teriparatide-alone arm. There were no between-group differences in adverse events. Combination teriparatide and risedronate increased BMD at the LS, TH as well as the FN and provided greater BMD increases at the TH than monotherapy. The results suggest combination risedronate and teriparatide therapy holds promise as a treatment for osteoporosis.

Clinical utility of serum sclerostin measurements

Sclerostin is an osteocyte-secreted soluble antagonist of the Wnt/β-catenin signaling pathway requisite for osteoblast development and activity. Efforts over the past several years have focused on unraveling the role of sclerostin in both normal physiological and pathological conditions. Sclerostin levels are undetectable in the serum of patients with sclerosteosis. In normal individuals, serum sclerostin levels are higher in males and increase in both sexes across the adult lifespan. Some, but not other, studies have demonstrated that higher serum sclerostin levels are associated with increased fracture risk, particularly when paired with lower bone mineral density. Levels of circulating sclerostin are highly correlated with bone marrow sclerostin levels. Sclerostin levels are inversely related to parathyroid hormone levels. Clinical conditions in which serum sclerostin levels have been measured include ankylosing spondylitis, chronic kidney disease, diabetes, fractures, hypercortisolism, multiple myeloma and spinal cord injury. Even within clearly defined clinical conditions, however, consistent changes in serum sclerostin levels have not always been seen. This may reflect differences in currently available commercial assays or sample sources (serum versus plasma), and suggests further study is needed before sclerostin measurements are introduced into routine clinical practice. Until such issues are resolved, measurement of sclerostin levels appears to be most useful for understanding the mechanisms by which osteocytes regulate bone turnover through the integration of hormonal, physical and pharmacological stimuli, rather than to guide clinical-care decisions.