Serum sclerostin levels in men with idiopathic osteoporosis

Serum sclerostin levels in osteoporotic fracture patients

PURPOSE

Sclerostin inhibits bone formation and stimulates bone resorption. Previous studies found a positive association between bone density and serum sclerostin, but literature on sclerostin levels in osteoporotic fracture patients is scarce. The aim of the present study was to compare the serum sclerostin levels in osteoporotic and non-osteoporotic fracture patients and to assess the correlation of the sclerostin levels with bone mineral density and vitamin D status.

METHODS

In this cross-sectional study, we included patients over 50 years, with an extremity fracture after low-energy trauma treated between 2012 and 2018, with biobank samples and available bone density measurements by Dual X-ray Absorption. Osteoporosis was diagnosed according the World Health Organisation criteria. Vitamin D deficiency was defined as a 25(OH)D concentration < 30 nmol/L. After defrosting biobank samples, serum sclerostin was measured using the human SOST (sclerostin) enzyme-linked immunosorbent assay kit. We prespecified a subgroup analysis including only female patients.

RESULTS

179 patients were included of whom 139(78%) were female. In 46 patients (25.7%), osteoporosis was diagnosed. Bone mineral density was positively associated with sclerostin levels (r = 0.17, p = 0.026) and patients with osteoporosis had a significantly lower serum sclerostin compared to non-osteoporotic fracture patients (mean 41.9 pmol/L vs 48.1 pmol/L; p = 0.03). This difference remained significant after correction for potential confounders. Similar results were found in the subgroup of female patients. No association between serum sclerostin and vitamin D deficiency was found.

CONCLUSION

Osteoporotic fracture patients had lower levels of sclerostin than non-osteoporotic fracture patients. Future research should focus on the use of sclerostin as biomarker for osteoporosis in fracture patients.

The relationship between circulating hormone levels, bone turnover markers and skeletal development in healthy boys differs according to maturation stage

INTRODUCTION

This study investigates peri-pubertal changes in bone turnover markers, Wnt-signalling markers, insulin-like growth factor-1 (IGF-1) and sex steroid levels, and how they reflect skeletal development in peri-pubertal boys.

MATERIALS AND METHODS

Population-based study in 118 peri-pubertal boys from the NINIOS cohort (age range at baseline 5.1-17.3 years) with repeated measurements at baseline and after two years. Serum levels of the classical bone turnover markers (BTM) procollagen type 1 N-terminal propeptide and carboxy-terminal collagen crosslinks, as well as sex-hormone binding globulin, IGF-1, osteoprotegerin, sclerostin and dickkopf-1 were measured using immunoassays. Sex steroids (estradiol, testosterone, and androstenedione) were measured using mass spectrometry and free fractions calculated. Dual energy x-ray absorptiometry was used for bone measurements at the lumbar spine and whole body. Volumetric bone parameters and bone geometry at the proximal and distal radius were assessed by peripheral QCT. Pubertal development was categorized based on Tanner staging.

RESULTS

During puberty, sex steroid and IGF-1-levels along with most parameters of bone mass and bone size increased every next Tanner stage. In contrast, classical bone turnover markers and sclerostin peaked around mid-puberty, with subsequent declines towards adult values in late puberty. Especially classical BTM and sex steroid levels showed consistent associations with areal and volumetric bone parameters and bone geometry. However, observed associations differed markedly according to pubertal stage and skeletal site.

CONCLUSION

Serum levels of sex steroids, IGF-1 and bone metabolism markers reflect skeletal development in peri-pubertal boys. However, skeletal development during puberty is nonlinear, and the relations between skeletal indices and hormonal parameters are nonlinear as well, and dependent on the respective maturation stage and skeletal site.

Dilemmas in the Management of Osteoporosis in Younger Adults

Osteoporosis in premenopausal women and men younger than 50 years is challenging to diagnose and treat. There are many barriers to optimal management of osteoporosis in younger adults, further enhanced by a limited research focus on this cohort. Herein we describe dilemmas commonly encountered in diagnosis, investigation, and management of osteoporosis in younger adults. We also provide a suggested framework, based on the limited available evidence and supported by clinical experience, for the diagnosis, assessment, and management of osteoporosis in this cohort. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Bone turnover markers as determinants of bone density and fracture in men with distal forearm fractures: the pathogenesis examined in the Mr F study

The pathogenesis for low-trauma wrist fractures in men is not fully understood. This study found that these men had evidence of significantly higher bone turnover compared with control subjects. Bone turnover markers were negative predictors of bone mineral density and were a predictor of fracture.

INTRODUCTION

Men with distal forearm fractures have reduced bone density, an increased risk of osteoporosis and of further fractures. The aim of this study was to investigate whether or not men with distal forearm fractures had evidence of altered bone turnover activity.

METHODS

Fifty eight men with low-trauma distal forearm fracture and 58 age-matched healthy control subjects were recruited. All subjects underwent a DXA scan of the forearm, both hips, and lumbar spine, biochemical investigations, and health questionnaires. Measurements of beta crosslaps (βCTX), procollagen type I N-terminal propeptide (PINP), sclerostin, Dickkopf-1 (Dkk1), and fibroblast growth factor 23 (FGF 23) were made.

RESULTS

Men with fracture had significantly higher PINP than controls at 39.2 ng/ml (SD 19.5) versus 33.4 ng/ml (SD13.1) (p<0.001). They also had significantly higher βCTX at 0.45 ng/ml (SD 0.21) versus 0.37 ng/ml (SD 0.17) (p= 0.037). Fracture subjects had significantly lower aBMD and PINP was a negative predictor of aBMD at the total hip and βCTX a negative predictor of forearm aBMD. Sclerostin was a positive predictor of aBMD at the lumbar spine and hip sites. Sex hormone binding globulin (SHBG) at 37nmol/L (SD 15.0) was lower in fracture cohort compared to 47.9 nmol/L (SD 19.2) (p=0.001) in control. Multiple regression revealed that the best model for prediction of fracture included SHBG, P1NP, and ultra-distal forearm aBMD. The likelihood of distal forearm fracture was decreased by 5.1% for each nmol/L increase in SHBH and by 1.4% for every mg/cm² increase in ultra-distal forearm aBMD, but increased by 6.1 % for every ng/ml increase in P1NP. Men in the highest quartile of PINP had a significantly greater likelihood of distal forearm fracture than those in the lowest quartile.

CONCLUSION

The fracture group had significantly higher PINP and βCTX compared with the control group, and these markers were negative predictors of aBMD at the total hip and forearm sites, respectively. Sclerostin was a positive predictor of the variance of spinal and hip aBMD. Likelihood of forearm fracture was best predicted by a combination of SHBG, PINP, and ultra-distal forearm aBMD. Findings of such cross-sectional data should be treated with caution, as longitudinal studies would be required to confirm or refute them.

High Circulating Sclerostin Level as Osteoporosis Risk Factor in Male Geriatric Population at Sanglah Hospital Bali

BACKGROUND: Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility. The development of biomolecular world found Wnt/β-catenin signaling pathway may plays an important role in bone mass regulation. Osteoporosis in geriatric population remains one of global health problems and typically thought of as a disease impacting women, but recently increasing attention is being paid to osteoporosis in males. Osteoporosis in male accounts for higher morbidity and mortality compare to woman population. The association between sclerostin serum and risk for osteoporosis in male geriatric will be described as follows. METHODS: This study is a case–control study with a total 54 samples of male geriatrics, divided into 27 non- osteoporosis subjects and 27 osteoporosis subjects (age ≥60 years old). Diagnosis of osteoporosis was defined according to the WHO criteria based on bone mineral density. All participants were scanned on a GE lunar prodigy bone densitometer. Sclerostin serum level was measured using enzyme-linked immunosorbent assay (ELISA). RESULTS: The average age from total 54 samples in case group was 69.81 ± 6.5 years old and control 69.41 ± 5.97 years old. Cutoff value based on receiver operating characteristic curve for sclerostin serum level was 302.5 pg/mL where the sensitivity and specificity for developing osteoporosis in male geriatrics were 59.3% and 81.5%, respectively. Male geriatrics with sclerostin serum ≥302.5 pg/mL is 6.4 times more likely to developed osteoporosis than those with sclerostin serum <302.5 pg/mL (OR = 6.4; p = 0.0020; CI 95% = 1.856–22.068). Multivariate logistic regression analysis after controlling other variables such as bone mass index, age, smoking status, alcohol consumption, physical activity, sun exposure, and type II diabetes mellitus showed that high sclerostin level was an independent susceptibility factors for osteoporosis in male geriatrics population (p = 0.001). CONCLUSIONS: This study showed that high circulating sclerostin serum (≥302.5 pg/mL) was risk factor for developing osteoporosis in male geriatrics.

Effect of androgen deprivation therapy on serum levels of sclerostin, Dickkopf-1, and osteoprotegerin: a cross-sectional and longitudinal analysis

Androgen deprivation therapy (ADT) for men with prostate cancer (PCa) results in accelerated bone loss and increased risk of bone fracture. The aim of the present study was to evaluate serum bone markers—sclerostin, Dickkopf-1 (DKK-1) and osteoprotegerin (OPG), in a cohort of 88 PCa patients without known bone metastases, managed with and without ADT, and to analyse their relationship with bone mineral density (BMD) and sex steroids. The cross-sectional analysis between acute-, chronic- and former-ADT groups and PCa controls showed that sclerostin and OPG levels significantly differed between them (p = 0.029 and p = 0.032). Groups contributing to these significant changes were recorded. There were no significant differences in serum DKK-1 levels across the four groups (p = 0.683). In the longitudinal analysis, significant % decreases within groups were seen for DKK-1 [chronic-ADT (− 10.06%, p = 0.0057), former-ADT (− 12.77%, p = 0.0239), and in PCa controls group (− 16.73, p = 0.0022); and OPG levels in chronic ADT (− 8.28%, p = 0.003) and PCa controls group (− 12.82%, p = 0.017)]. However, % changes in sclerostin, DKK-1, and OPG did not differ significantly over 6-months across the evaluated groups. Sclerostin levels showed significant positive correlations with BMD at baseline in the ADT group, while in PCa controls this correlation existed at both baseline and 6-month time points. Sclerostin correlated negatively with testosterone in former ADT users and in PCa controls. Possible prognostic features denoted by parallel increases in sclerostin and BMD are discussed.

Osteocyte TSC1 promotes sclerostin secretion to restrain osteogenesis in mice

Osteocytes secrete the glycoprotein sclerostin to inhibit bone formation by osteoblasts, but how sclerostin production is regulated in osteocytes remains unclear. Here, we show that tuberous sclerosis complex 1 (TSC1) in osteocytes promotes sclerostin secretion through inhibition of mechanistic target of rapamycin complex 1 (mTORC1) and downregulation of Sirt1. We generated mice with DMP1-Cre-directed Tsc1 gene deletion (Tsc1 CKO) to constitutively activate mTORC1 in osteocytes. Although osteocyte TSC1 disruption increased RANKL expression and osteoclast formation, it markedly reduced sclerostin production in bone, resulting in severe osteosclerosis with enhanced bone formation in mice. Knockdown of TSC1 activated mTORC1 and decreased sclerostin, while rapamycin inhibited mTORC1 and increased sclerostin mRNA and protein expression levels in MLO-Y4 osteocyte-like cells. Furthermore, mechanical loading activated mTORC1 and prevented sclerostin expression in osteocytes. Mechanistically, TSC1 promotes sclerostin production and prevents osteogenesis through inhibition of mTORC1 and downregulation of Sirt1, a repressor of the sclerostin gene Sost. Our findings reveal a role of TSC1/mTORC1 signalling in the regulation of osteocyte sclerostin secretion and bone formation in response to mechanical loading in vitro. Targeting TSC1 represents a potential strategy to increase osteogenesis and prevent bone loss-related diseases.

Relationship Between Osteoporosis and Serum Sclerostin Levels in Kidney Transplant Recipients

OBJECTIVES

Sclerostin, a peptide secreted primarily by osteocytes, suppresses osteoblast maturation, thus reducing bone formation. Here, we evaluated the relationship between sclerostin levels and osteoporosis in kidney transplant recipients.

MATERIALS AND METHODS

This cross-sectional study included 78 kidney transplantrecipients > 18 years old and at least 6 months posttransplant. In our center, unrelated living-donor kidney transplants are not performed. Patients with parathyroid adenoma or parathyroidectomy history were excluded. Lumbar and femoral neck bone mineral densities andT and Z scores were obtained by dual-energy X-ray absorptiometry; results were used to divide patients into osteoporotic and nonosteoporotic groups. Serum sclerostin was measured by enzyme-linked immunosorbent assay.

RESULTS

: Of total patients, 43% had osteoporosis, mean age was 40.8 years, and 70% were male. Groups had similar ages, male-female distribution, time posttransplant, cumulative corticosteroid dose, estimated glomerular filtration rates, and 25-hydroxyvitamin D2 levels (P > .05). The osteoporotic group had lower sclerostin (405.9 ± 234.9 vs 521.7 ± 233.5 ng/dL; P = .035) and higherintact parathyroid hormone levels (110.9 ± 68.0 vs 84.8 ± 41.4 pg/mL; P = .04) than the nonosteoporotic group. Sclerostin levels were not correlated with cumulative corticosteroid dose, intact parathyroid hormone, bone mineral density, and T scores at any site but were weakly negatively correlated with age (P = .04, r = -0.25). In multiple regression analyses, only intact parathyroid hormone had negative effects on lumbar bone mineral density (P = .02) andT scores (P = .036). Serum sclerostin levels, age, and cumulative corticosteroid dose did not affect lumbar or hip bone mineral density and T scores (P > .05).

CONCLUSIONS

Sclerostin levels were low in our osteoporotic patients;therefore, sclerostin may not be a contributing factor to osteoporosis development. Because sclerostin is an osteocyte-derived peptide, its serum levels only reflect total osteocyte number and bone mass.

MANAGEMENT OF ENDOCRINE DISEASE: Novel anabolic treatments for osteoporosis

Skeletal anabolic agents enhance bone formation, which is determined by the number and function of osteoblasts. Signals that influence the differentiation and function of cells of the osteoblast lineage play a role in the mechanism of action of anabolic agents in the skeleton. Wnts induce the differentiation of mesenchymal stem cells toward osteoblasts, and insulin-like growth factor I (IGF-I) enhances the function of mature osteoblasts. The activity of Wnt and IGF-I is controlled by proteins that bind to the growth factor or to its receptors. Sclerostin is a Wnt antagonist that binds to Wnt co-receptors and prevents Wnt signal activation. Teriparatide, a 1-34 amino terminal fragment of parathyroid hormone (PTH), and abaloparatide, a modified 1-34 amino terminal fragment of PTH-related peptide (PTHrp), induce IGF-I, increase bone mineral density (BMD), reduce the incidence of vertebral and non-vertebral fractures and are approved for the treatment of postmenopausal osteoporosis. Romosozumab, a humanized anti-sclerostin antibody, increases bone formation, decreases bone resorption, increases BMD and reduces the incidence of vertebral fractures. An increased incidence of cardiovascular events has been associated with romosozumab, which is yet to be approved for the treatment of osteoporosis. In conclusion, cell and molecular studies have formed the foundation for the development of new anabolic therapies for osteoporosis with proven efficacy on the incidence of new fractures.

Circulating microRNA Signatures in Patients With Idiopathic and Postmenopausal Osteoporosis and Fragility Fractures

CONTEXT

Established bone turnover markers do not reflect fracture risk in idiopathic male and premenopausal osteoporosis and the role of microRNAs (miRNAs) in these patients is currently unclear. miRNAs are a class of small non-coding RNAs that regulate gene expression and bone tissue homeostasis. They are considered a new class of endocrine regulators with promising potential as biomarkers.

OBJECTIVE

Evaluation of circulating miRNA signatures in male and female subjects with idiopathic and postmenopausal osteoporotic low-traumatic fractures.

DESIGN, SETTING, AND PATIENTS

This was a case-control study of cross-sectional design of 36 patients with prevalent low-traumatic fractures and 39 control subjects Main Outcome Measures: One hundred eighty-seven miRNAs were quantified in serum by qPCR, compared between groups and correlated with established bone turnover markers.

RESULTS

Significant differences in serum levels of circulating miRNAs were identified in all three subgroups (46 in premenopausal, 52 in postmenopausal, 55 in male). A set of 19 miRNAs was consistently regulated in all three subgroups. Eight miRNAs [miR-152-3p, miR-30e-5p, miR-140-5p, miR-324-3p, miR-19b-3p, miR-335-5p, miR-19a-3p, miR-550a-3p] were excellent discriminators of patients with low-traumatic fractures, regardless of age and sex, with area under the curve values > 0.9. The 11 remaining miRNAs showed area under the curve values between 0.81 and 0.89. Correlation analysis identified significant correlations between miR-29b-3p and P1NP, and miR-365-5p and iPTH, TRAP5b, P1NP and Osteocalcin, as well as BMD_L1-L4 and miR-19b-3p, miR-324-3p, miR-532-5p, and miR-93-5p.

CONCLUSIONS

Specific serum miRNA profiles are strongly related to bone pathologies. Therefore miRNAs might be directly linked to bone tissue homeostasis. In particular, miR-29b-3p has previously been reported as regulator of osteogenic differentiation and could serve as a novel marker of bone turnover in osteoporotic patients as a member of a miRNA signature.

The potential use of antisclerostin therapy in chronic kidney disease-mineral and bone disorder

PURPOSE OF REVIEW

Sclerostin is a regulator of the osteoanabolic canonical Wnt signaling pathway, and thus helps to govern rates of bone formation. The Wnt pathway is also recognized as playing an important role in the pathophysiology of the chronic kidney disease-mineral and bone disorder (CKD-MBD). It also may serve as an interface between bone and the vascular system. Pharmacological inhibition of sclerostin has shown promise as an osteoanabolic approach to the treatment of osteoporosis. Inhibition of sclerostin is a potentially useful but unproven strategy in the management of CKD-MBD.

RECENT FINDINGS

Clinical trials with humanized monoclonal sclerostin antibodies (Scl-Ab) have shown a rapid initial increase in bone formation and a marked increase in bone mineral density. Although clinical data, to this point, in CKD are not available, animal models of low bone turnover CKD show that Scl-Ab improves trabecular bone volume and mineralization without affecting biochemical indices.

SUMMARY

Targeted clinical trials are needed to evaluate the potential effectiveness of Scl-Ab in CKD. Based upon the available data, there is potential not only for this new therapeutic class to improve skeletal health but perhaps also to have substantial cardiovascular benefits in CKD.

Regulation of Sclerostin Production in Human Male Osteocytes by Androgens: Experimental and Clinical Evidence

In this study we aimed to elucidate a possible role of T in the regulation of sclerostin, a glycoprotein secreted by osteocytes known to regulate bone mass. To this end, we evaluated the effect of T stimulation on sclerostin production and gene expression in human cultured osteocytes. In addition, we evaluated serum sclerostin levels in a cohort of 20 hypogonadal male patients, compared with 20 age-matched eugonadal controls. Stimulation with DHT decreased sclerostin expression in cultured osteocytes in a time- and dose-dependent manner. Confirming a direct androgen receptor-mediated effect on sclerostin production, flutamide coincubation and silencing of androgen receptor gene in osteocytes abolished the DHT effects. In addition, hypogonadal patients showed higher serum sclerostin levels with respect to controls (145.87 ± 50.83 pg/mL vs 84.02 ± 32.15 pg/mL; P < .001) and in both probands and controls, serum T levels were negatively correlated with sclerostin (R = -0.664, P = 0.007, and R = -0.447, P = .045, respectively). Finally, multiple stepwise regression analysis showed that T represented the only independent predictor of sclerostin levels. In conclusion, by showing a direct correlation between T and sclerostin, both in vivo and in vitro, this study adds further support to the emerging clinical and experimental studies focusing on sclerostin as a therapeutic target for osteoporosis treatment.

The WNT system: background and its role in bone

WNTs are extracellular proteins that activate different cell surface receptors linked to canonical and noncanonical WNT signalling pathways. The Wnt genes were originally discovered as important for embryonic development of fruit flies and malignant transformation of mouse mammary cancers. More recently, WNTs have been implicated in a wide spectrum of biological phenomena and diseases. During the last decade, several lines of clinical and preclinical evidence have indicated that WNT signalling is critical for trabecular and cortical bone mass, and this pathway is currently an attractive target for drug development. Based on detailed knowledge of the different WNT signalling pathways, it appears that it might be possible to develop drugs that specifically target cortical and trabecular bone. Neutralization of a bone-specific WNT inhibitor is now being evaluated as a promising anabolic treatment for patients with osteoporosis. Here, we provide the historical background to the discoveries of WNTs, describe the different WNT signalling pathways and summarize the current understanding of how these proteins regulate bone mass by affecting bone formation and resorption.

Sclerostin: recent advances and clinical implications

PURPOSE OF REVIEW

Discovery of the Wnt signaling pathway and understanding the central role of osteocyte in skeletal homeostasis have been the major advances in skeletal biology over the past decade. Sclerostin, secreted mainly (but not exclusively) by osteocytes, has emerged as a key player in skeletal homeostasis. This review highlights the most relevant recent advances.

RECENT FINDINGS

Sclerostin by inhibiting Wnt signaling pathway decreases bone formation and osteoblast differentiation and promotes osteoblast apoptosis. Ability to measure serum sclerostin levels better clarified the role of sclerostin in various physiologic and pathologic states. Early clinical trials with antibodies to sclerostin have produced robust increases in bone mineral density, and fracture prevention trials are underway.

SUMMARY

Since the discovery of Wnt signaling pathway and sclerostin's association with high bone mass, there has been a remarkable progress. Clinical trials with fracture endpoints, already underway, should expand osteoanabolic therapeutic horizon in the very near future. Measurement of sclerostin levels in a number of conditions has advanced our knowledge about pathophysiology of skeletal and nonskeletal disorders in an altogether new light.

Sex steroid actions in male bone

Sex steroids are chief regulators of gender differences in the skeleton, and male gender is one of the strongest protective factors against osteoporotic fractures. This advantage in bone strength relies mainly on greater cortical bone expansion during pubertal peak bone mass acquisition and superior skeletal maintenance during aging. During both these phases, estrogens acting via estrogen receptor-α in osteoblast lineage cells are crucial for male cortical and trabecular bone, as evident from conditional genetic mouse models, epidemiological studies, rare genetic conditions, genome-wide meta-analyses, and recent interventional trials. Genetic mouse models have also demonstrated a direct role for androgens independent of aromatization on trabecular bone via the androgen receptor in osteoblasts and osteocytes, although the target cell for their key effects on periosteal bone formation remains elusive. Low serum estradiol predicts incident fractures, but the highest risk occurs in men with additionally low T and high SHBG. Still, the possible clinical utility of serum sex steroids for fracture prediction is unknown. It is likely that sex steroid actions on male bone metabolism rely also on extraskeletal mechanisms and cross talk with other signaling pathways. We propose that estrogens influence fracture risk in aging men via direct effects on bone, whereas androgens exert an additional antifracture effect mainly via extraskeletal parameters such as muscle mass and propensity to fall. Given the demographic trends of increased longevity and consequent rise of osteoporosis, an increased understanding of how sex steroids influence male bone health remains a high research priority.

A review of osteocyte function and the emerging importance of sclerostin

➤ Osteocytes, derived from osteoblasts, reside within bone and communicate extensively with other bone cell populations to regulate bone metabolism. The mature osteocyte expresses the protein sclerostin, a negative regulator of bone mass.➤ In normal physiologic states, the protein sclerostin acts on osteoblasts at the surface of bone and is differentially expressed in response to mechanical loading, inflammatory molecules such as prostaglandin E2, and hormones such as parathyroid hormone and estrogen.➤ Pathologically, sclerostin dysregulation has been observed in osteoporosis-related fractures, failure of implant osseous integration, metastatic bone disease, and select genetic diseases of bone mass.➤ An antibody that targets sclerostin, decreasing endogenous levels of sclerostin while increasing bone mineral density, is currently in phase-III clinical trials.➤ The osteocyte has emerged as a versatile, indispensable bone cell. Its location within bone, extensive dendritic network, and close communication with systemic circulation and other bone cells produce many opportunities to treat a variety of orthopaedic conditions.

Effect of liver dysfunction on circulating sclerostin

Sclerostin is a Wnt inhibitor produced specifically by osteocytes. It decreases bone formation by repressing osteoblast differentiation and proliferation. Whether circulating sclerostin level is affected by liver function is not currently clear. The aim of the study was to evaluate this relationship. Our cross-sectional study included 47 patients with liver cirrhosis and 50 healthy controls. Serum sclerostin level was analyzed by ELISA. Serum sclerostin levels were significantly higher in patients with cirrhosis than in controls (50.8 ± 38.2 vs. 35.1 ± 8.8 pmol/L, p = 0.008). After further adjustment for age, sex, body mass index, serum creatinine, and presence of diabetes, cirrhosis patients had higher sclerostin than controls. Subgroup analysis found that patients with Child-Pugh class B or C had higher sclerostin levels than patients with class A or controls after adjusting for multiple confounding factors. Multiple regression analysis showed that gender (p = 0.022), presence of diabetes (p < 0.001), albumin (p = 0.010), and serum creatinine (p = 0.037) were independent factors for circulating sclerostin level. Circulating sclerostin was higher in patients with advanced liver cirrhosis than in healthy controls or patients with early liver cirrhosis. The elevated sclerostin levels clearly correlated with markers of liver dysfunction such as albumin. The relationship between circulating sclerostin and liver function indicates a possible role of the liver in sclerostin metabolism.

Osteoporosis in men

Osteoporosis in men causes significant morbidity and mortality. Bone health declines gradually, often insidiously; and in light of the advancing aging population poses a serious public health issue that is not well recognized. Studies of the past decade have expanded our understanding of the events within, as well as the regulation of, bone remodeling and provided better insight into the physiology and pathophysiology specific to the adult male skeleton. The clinical measurement of bone mineral density using dual-energy X-ray absorptiometry remains the gold standard for diagnosis of osteoporosis in males; and fracture risk assessment is now recognized as a preferred approach to guide treatment decisions. Utilizing surrogate end-points such as increasing bone mineral density and decreasing concentrations of bone resorption markers, clinical trials have demonstrated efficacy in pharmacological treatment of osteoporosis in the adult male. Unfortunately, few studies have evaluated the anti-fracture benefits in this population. Measurement of bone turnover markers may be an additional tool to monitor therapeutic responsiveness in addition to the measurement of bone mineral density.

Sclerostin serum levels in prostate cancer patients and their relationship with sex steroids

The role of sclerostin on bone metabolism and its relation to sex steroids in patients with prostate cancer (PC) is not well known. We found that sclerostin levels are significantly increased in PC patients, particularly in those with androgen deprivation therapy (ADT), and there is an inverse relationship between sclerostin levels and testosterone.

INTRODUCTION

Recent studies have evaluated sclerostin levels in bone diseases as osteoporosis. However, there are few data in PC patients, particularly in patients with hypogonadism related to ADT. The aim of the present study was to compare serum sclerostin levels in ADT/non-ADT-treated PC patients and healthy controls and to evaluate their relationship with sex steroids and bone metabolism.

METHODS

We performed a cross-sectional study involving 81 subjects: 25 ADT-treated PC patients, 34 PC patients without ADT treatment, and 22 healthy controls. We measured serum sclerostin levels, bone turnover markers, bone mineral density (BMD) in all individuals, and sex steroids levels in PC patients.

RESULTS

Serum sclerostin levels were significantly higher in PC patients compared to those in control subjects. ADT-treated patients had significantly higher sclerostin levels than PC patients without ADT treatment: ADT 64.52 ± 27.21 pmol/L, non-ADT 48.24 ± 15.93 pmol/L, healthy controls 38.48 ± 9.19 pmol/L, p < 0.05. In PC patients, we found a negative relationship between serum sclerostin levels and androgens after age adjustment (total testosterone: r = -0.309, p = 0.029; bioavailable testosterone: r = -0.280, p = 0.049; free testosterone: r = -0.299, p = 0.035). We did not observe any relationship between sclerostin levels and bone turnover markers or BMD in any group.

CONCLUSIONS

Circulating sclerostin levels are significantly increased in patients with PC and particularly in those receiving ADT. The inverse relationship between serum sclerostin and testosterone in these patients suggests that androgens are key regulators of bone metabolism in this population.

Sclerostin is positively associated with bone mineral density in men and women and negatively associated with carotid calcified atherosclerotic plaque in men from the African American-Diabetes Heart Study

CONTEXT

Bone mineral density (BMD) and calcified atherosclerotic plaque (CP) demonstrate inverse relationships. Sclerostin, an endogenous regulator of the Wnt pathway and bone formation, has been associated with impaired osteoblast activation and may play a role in vascular calcification.

OBJECTIVE

Our objective was to assess the relationships between sclerostin, BMD, and CP.

DESIGN

Generalized linear models were fitted to test for associations between sclerostin, volumetric BMD (vBMD), and CP.

PARTICIPANTS

A targeted population of 450 unrelated African Americans (AAs) with type 2 diabetes (T2D) was 56% female with mean/SD/median age of 55.4/9.5/55.0 years and a diabetes duration of 10.3/8.2/8.0 years.

MAIN OUTCOME MEASURES

Plasma sclerostin, computed tomography-derived thoracic and lumbar vertebrae trabecular vBMD, coronary artery, carotid artery, and aortoiliac CP were measured.

RESULTS

Plasma sclerostin was 1119/401/1040 pg/mL, thoracic vBMD was 206.3/52.4/204.8 mg/cm3, lumbar vBMD was 180.7/47.0/179.0 mg/cm3, coronary artery CP score was 284/648/13, carotid artery CP score was 46/132/0, and aortoiliac CP score was 1613/2910/282. Sclerostin levels were higher in men than women (P<.0001). Before and after adjusting for age, sex, body mass index, blood pressure, smoking, hemoglobin A1c, and low-density lipoprotein-cholesterol, plasma sclerostin levels were positively associated with thoracic and lumbar vertebrae vBMD (P<.0001). Sex-stratified analyses verified significant relationships in both men and women (both P<.001). Sclerostin was not associated with CP except for an inverse relationship with carotid CP in men (fully adjusted model, P=.03).

CONCLUSIONS

In this cross-sectional study of AA men and women with T2D, circulating sclerostin was positively associated with vBMD in the spine in both sexes and inversely associated with carotid artery CP in men. Sclerostin may play a role in skeletal mineral metabolism in AA but fails to explain inverse relationships between BMD and CP.

Idiopathic osteoporosis in men

Over the last decade, the increasingly significant problem of osteoporosis in men has begun to receive much more attention than in the past. In particular, recent observations from large scale population studies in males led to an advance in the understanding of morphologic basis of growth, maintenance and loss of bone in men, as well as new insights about the pathophysiology and treatment of this disorder. While fracture risk consistently increases after age 65 in men (with up to 50 % of cases due to secondary etiologies), osteoporosis and fractures may also occur in young or middle aged males in the absence of an identifiable etiology. For this category (so called idiopathic osteoporosis), there are still major gaps in knowledge, particularly concerning the etiology and the clinical management. This article provides a summary of recent developments in the acquisition and maintenance of bone strength in men, as well as new insights about the pathogenesis, diagnosis, and treatment of idiopathic osteoporosis.

Wnt signalling in osteoporosis: mechanisms and novel therapeutic approaches

Osteoporosis is a skeletal disorder characterized by bone loss, which results in architectural deterioration of the skeleton, compromised bone strength and an increased risk of fragility fractures. Most current therapies for osteoporosis stabilize the skeleton by inhibiting bone resorption (antiresorptive agents), but the development of anabolic therapies that can increase bone formation and bone mass is of great interest. Wnt signalling induces differentiation of bone-forming cells (osteoblasts) and suppresses the development of bone-resorbing cells (osteoclasts). The Wnt pathway is controlled by antagonists that interact either directly with Wnt proteins or with Wnt co-receptors. The importance of Wnt signalling in bone formation is indicated by skeletal disorders such as sclerosteosis and van Buchem syndrome, which are caused by mutations in the gene encoding the Wnt antagonist sclerostin (SOST). Experiments in mice have shown that downregulation or neutralization of Wnt antagonists enhances bone formation. Phase II clinical trials show that 1-year treatment with antisclerostin antibodies increases bone formation, decreases bone resorption and leads to a substantial increase in BMD. Consequently, Wnt signalling can be targeted by the neutralization of its extracellular antagonists to obtain a skeletal anabolic response.