β-Adrenergic receptor antagonists and fracture risk: a meta-analysis of selectivity, gender, and site-specific effects

Evaluation of bone mineral density (BMD) and trabecular bone score (TBS) in pheochromocytoma and paraganglioma; a multi-centric case-control study from India

Pheochromocytoma and paraganglioma (PPGL) have been associated with low bone mineral density (BMD) due to excess sympathetic system stimulation. Our study revealed low BMD and TBS (trabecular bone score) in cases compared to matched controls. Plasma-free nor-metanephrine and hypertension duration found to be most consistent predictive factors.

PURPOSE

Pheochromocytoma and paraganglioma (PPGL) have been associated with low bone mineral density (BMD) and increased fracture risks. Sympathetic nervous system stimulation has been shown to increase bone resorption and decrease bone formation via β2 receptors. Chronic inflammation and increased cytokine production add to more bone loss. TBS (trabecular bone score) is an established surrogate marker for bone histomorphometry. BMD and TBS data in pheochromocytoma and PPGL are scarce. The aim was to assess the BMD and TBS in pheochromocytoma and PPGL and look for clinical and biochemical predictors.

METHODS

This case-control study had sample size of 58 (29 cases and controls each). BMI-, age-, and sex-matched controls were taken for comparison. Both cases and controls had undergone DXA scan and BMD {Z-scores and bone mineral concentration (BMC) in g/cm2} and TBS were analyzed. Detailed clinical histories and relevant biochemistry values were noted.

RESULTS

The mean age of our case population was 29.5 ± 9.4 years with a mean age of HTN onset at 26.86 ± 6.6 years. Lumbar spine BMC (0.86 ± 0.14 vs 0.96 ± 0.15; p = 0.036), femoral neck Z-score (- 1.23 ± 1.07 vs - 0.75 ± 0.97; p = 0.003), and whole body BMC (0.91 ± 0.14 vs 1.07 ± 0.11; p = 0.000) were significantly low in cases compared to controls. Similarly, TBS was significantly lower in cases compared to controls (1.306 ± 0.113 vs 1.376 ± 0.083; p = 0.001).

CONCLUSION

This study establishes both low bone mass and poor bone quality in an Indian pheochromocytoma and PPGL patient's cohort. Plasma-free nor-metanephrine and duration of hypertension were found to be most consistent predictive factors in multivariate regression analysis.

Impact of Pheochromocytoma or Paraganglioma on Bone Metabolism: A Systemic Review and Meta-analysis

INTRODUCTION

Preclinical and animal studies have suggested that excess catecholamines can lead to bone mineral loss. However, to date, no systematic review is available that has analyzed the impact of catecholamine excess in the context of pheochromocytoma/paraganglioma (PPGL) on bone metabolism. We conducted this meta-analysis to address this knowledge gap.

METHODS

Electronic databases were searched for studies evaluating bone metabolism, including assessments of bone mineral density (BMD), quantitative computed tomography (qCT), trabecular bone score (TBS), or bone turnover markers in patients with PPGL. These markers included those of bone resorption, such as tartrate-resistant acid phosphatase 5b (TRACP-5b) and cross-linked C-telopeptide of type I collagen (CTx), as well as markers of bone formation, such as bone-specific alkaline phosphatase (BS ALP).

RESULTS

Out of the initially screened 1614 articles, data from six studies published in four different patient cohorts with PPGL that met all criteria were analysed. Individuals with PPGL had significantly lower TBS [Mean Difference (MD) -0.04 (95% CI: -0.05--0.03); p < 0.00001; I2 = 0%], higher serum CTx [MD 0.13 ng/ml (95% CI: 0.08-0.17); p < 0.00001; I2 = 0%], and higher BS-ALP [MD 1.47 U/L (95% CI: 0.30-2.64); p = 0.01; I2 = 1%]. TBS at 4-7 months post-surgery was significantly higher compared to baseline [MD 0.05 (95% CI: 0.02-0.07); p < 0.0001]. A decrease in CTx has been documented post-surgery.

CONCLUSION

Bone health deterioration is a major concern in patients with PPGL. In addition to providing a definitive cure for catecholamine excess, monitoring and treating osteoporosis is essential for individuals with secondary osteoporosis due to PPGL. Long-term studies on bone health outcomes in PPGL are warranted.

Protective Effects of β-Blockers on Bone in Older Adults with Dementia

Increased β-adrenergic receptor activity has been hypothesized to cause bone loss in those with dementia. We investigated the effect of long-term β-blocker use on rate of bone loss in older adults with dementia. We used a linear mixed-effects model to estimate the relationship between long-term β-blocker use and rate of bone loss in participants from the Health Aging and Body Composition study. Records of 1198 participants were analyzed, 44.7% were men. Among the men, 25.2% had dementia and 20.2% were on β-blockers, while in the women, 22.5% had dementia and 16.6% received β-blockers. In the 135 men with dementia, 23 were taking β-blockers, while 15 of 149 women with dementia were using β-blockers. In men with dementia, β-blocker users had 0.00491 g/cm2 less bone mineral density (BMD) loss per year at the femoral neck (i.e., 0.63% less loss per year) than non-users (p < 0.05). No differences were detected in women with or without dementia and men without dementia. β-blockers may be protective by slowing down bone loss in older men with dementia.

Evidence in Humans for Bone as an Endocrine Organ Regulating Energy Metabolism

There is increasing evidence from animal models that bone, in addition to its traditional function of providing structural support for the organism, has a rich network of interactions with multiple other tissues. This perspective focuses on evidence from human studies demonstrating that bone is an endocrine organ regulating energy metabolism, with the specific examples being osteocalcin, lipocalin 2, RANKL, and sclerostin. Conversely, animal studies have also demonstrated that a key hormone regulating energy metabolism, leptin, regulates bone metabolism via the sympathetic nervous system. Studies in humans have established a role for the sympathetic nervous system in regulating bone turnover; indeed, the potential therapeutic benefit of targeting this pathway in humans to prevent postmenopausal bone loss is currently being evaluated.

The Association of Beta-Blocker Use and Bone Mineral Density Level in Hemodialysis Patients: A Cross-Sectional Study

Background and Objectives: Osteoporosis results in increasing morbidity and mortality in hemodialysis patients. The medication for treatment has been limited. There is evidence that beta-blockers could increase bone mineral density (BMD) and reduce the risk of fracture in non-dialysis patients, however, a study in hemodialysis patients has not been conducted. This study aims to determine the association between beta-blocker use and bone mineral density level in hemodialysis patients. Materials and Methods: We conducted a cross-sectional study in hemodialysis patients at Thammasat University Hospital from January 2018 to December 2020. A patient receiving a beta-blocker ≥ 20 weeks was defined as a beta-blocker user. The association between beta-blocker use and BMD levels was determined by univariate and multivariate linear regression analysis. Results: Of the 128 patients receiving hemodialysis, 71 were beta-blocker users and 57 were non-beta-blocker users (control group). The incidence of osteoporosis in hemodialysis patients was 50%. There was no significant difference in the median BMD between the control and the beta-blocker groups of the lumbar spine (0.93 vs. 0.91, p = 0.88), femoral neck (0.59 vs. 0.57, p = 0.21), total hip (0.73 vs. 0.70, p = 0.38), and 1/3 radius (0.68 vs. 0.64, p = 0.40). The univariate and multivariate linear regression analyses showed that the beta-blocker used was not associated with BMD. In the subgroup analysis, the beta-1 selective blocker used was associated with lower BMD of the femoral neck but not within the total spine, total hip, and 1/3 radius. The multivariate logistic regression showed that the factors of age ≥ 65 years (aOR 3.31 (1.25−8.80), p = 0.02), female sex (aOR 4.13 (1.68−10.14), p = 0.002), lower BMI (aOR 0.89 (0.81−0.98), p = 0.02), and ALP > 120 U/L (aOR 3.88 (1.33−11.32), p = 0.01) were independently associated with osteoporosis in hemodialysis patients. Conclusions: In hemodialysis patients, beta-blocker use was not associated with BMD levels, however a beta-1 selective blocker used was associated with lower BMD in the femoral neck.

Bone mass loss in chronic heart failure is associated with sympathetic nerve activation

PURPOSE

Chronic heart failure causes osteoporosis, but the mechanism remains unclear. The sympathetic nerve plays an important role in both bone metabolism and cardiovascular function.

METHODS

Thirty-six adult male SD rats were randomly divided into the following four groups: sham surgery (Sham) group, guanethidine (GD) group, abdominal transverse aorta coarctation-induced heart failure + normal saline (TAC) group, and TAC + guanethidine (TAC + GD) group. Normal saline (0.9 % NaCl) or guanethidine (40 mg/kg/ml) was intraperitoneally injected daily for 5 weeks. Then, DXA, micro-CT, ELISA and RT-PCR analyses were performed 12 weeks after treatment.

RESULTS

The bone loss in rats subjected to TAC-induced chronic heart failure and chemical sympathectomy with guanethidine was increased. Serum norepinephrine levels were increased in rats with TAC-induced heart failure but were decreased in TAC-induced heart failure rats treated with guanethidine. The expression of α2A adrenergic receptor, α2C adrenergic receptor, osteoprotegerin (OPG), and osteocalcin in the tibia decreased in the TAC-induced heart failure group, and the expression of β1 adrenergic receptor, β2 adrenergic receptor, receptor activator of nuclear factor-κ B ligand (RANKL), and RANKL/OPG in the tibia increased in the heart failure group. In addition, these changes in gene expression levels were rescued by chemical sympathectomy with guanethidine.

CONCLUSIONS

TAC-induced chronic heart failure is associated with bone mass loss, and the sympathetic nerve plays a significant role in heart failure-related bone mass loss.

MINI ABSTRACT

The present study supports the hypothesis that heart failure is related to bone loss, and the excessive activation of sympathetic nerves participates in this pathophysiological process. The present study suggests a potential pathological mechanism of osteoporosis associated with heart failure and new perspectives for developing strategies for heart failure-related bone loss.

Heart Failure is Associated with Early Medical and Surgery-Related Complications Following Total Hip Arthroplasty: A Propensity-Scored Analysis

INTRODUCTION

There is a paucity of literature that examines how heart failure (HF) impacts surgery-related complications following total hip arthroplasty (THA). We hypothesized that patients who had HF will be at increased risk of early medical- and surgery-related complications following THA.

METHODS

Patients who had HF and underwent primary THA between 2010 and 2019 were identified using a large national insurance database. Ninety-day incidence of various medical complications, surgery-related complications, and hospital utilizations were evaluated for patients who did and did not have HF, as well as subgroup analyses were performed on patients who were prescribed mortality-benefitting medications for HF 1 year prior to THA. Propensity score matching resulted in 34,000 HF patients who underwent primary THA and 340,000 matching patients.

RESULTS

The HF cohort was associated with a higher 90-day incidence of pulmonary embolism (PE), deep vein thrombosis (DVT), transfusion, pneumonia, cerebrovascular accident (CVA), myocardial infarction (MI), sepsis, acute post hemorrhagic anemia, acute renal failure (ARF), and urinary tract infection (UTI), as well as 1-year risk of revision THA, periprosthetic joint infection (PJI), aseptic loosening, and dislocation compared to controls. The HF cohort was associated with a higher 90-day incidence of emergency department visits, readmissions, lengths of stay (LOS), and 1-year costs of care. The medication cohort was at decreased risk of PE, DVT, CVA, return to ED, readmission and MI within 90 days of surgery, and 1-year risk of revision THA and aseptic loosening.

DISCUSSION

These findings may help to better risk-stratify patients who have HF and are scheduled to undergo THA, as well as call for additional surveillance of these patients in the immediate and early postoperative period. This study also helps surgeons and internists understand how chronic medications used to treat HF can impact medical- and surgery-related outcomes following THA.

Antihypertensive Drugs and Risk of Bone Fractures

Antihypertensive drugs are among the most documented regimens worldwide with an overall survival and cardioprotective benefit. However, there is evidence that they cause symptoms of orthostatic hypotension (i.e., dizziness and syncope) placing patients at risk for falls and fall-related injuries such as bone fractures. Moreover, it seems that they might impact bone metabolism and architecture impairing bone health. The aim of this review was to summarize the accumulative literature exploring any potential association between several antihypertensive medications including diuretics, renin-angiotensin-aldosterone system inhibitors, beta-blockers and calcium channel blockers and the risk of fractures.

The crosstalk between bone remodeling and energy metabolism: A translational perspective

Genetics in model organisms has progressively broken down walls that previously separated different disciplines of biology. One example of this holistic evolution is the recognition of the complex relationship that exists between the control of bone mass (bone remodeling) and energy metabolism in mammals. Numerous hormones orchestrate this crosstalk. In particular, the study of the leptin-mediated regulation of bone mass has not only revealed the existence of a central control of bone mass but has also led to the realization that sympathetic innervation is a major regulator of bone remodeling. This happened at a time when the use of drugs aiming at treating osteoporosis, the most frequent bone disease, has dwindled. This review will highlight the main aspects of the leptin-mediated regulation of bone mass and how this led to the realization that β-blockers, which block the effects of the sympathetic nervous system, may be a viable option to prevent osteoporosis.

Propranolol Promotes Bone Formation and Limits Resorption Through Novel Mechanisms During Anabolic Parathyroid Hormone Treatment in Female C57BL/6J Mice

Although the nonselective β-blocker, propranolol, improves bone density with parathyroid hormone (PTH) treatment in mice, the mechanism of this effect is unclear. To address this, we used a combination of in vitro and in vivo approaches to address how propranolol influences bone remodeling in the context of PTH treatment. In female C57BL/6J mice, intermittent PTH and propranolol administration had complementary effects in the trabecular bone of the distal femur and fifth lumbar vertebra (L5 ), with combination treatment achieving microarchitectural parameters beyond that of PTH alone. Combined treatment improved the serum bone formation marker, procollagen type 1 N propeptide (P1NP), but did not impact other histomorphometric parameters relating to osteoblast function at the L5 . In vitro, propranolol amplified the acute, PTH-induced, intracellular calcium signal in osteoblast-like cells. The most striking finding, however, was suppression of PTH-induced bone resorption. Despite this, PTH-induced receptor activator of nuclear factor κ-B ligand (RANKL) mRNA and protein levels were unaltered by propranolol, which led us to hypothesize that propranolol could act directly on osteoclasts. Using in situ methods, we found Adrb2 expression in osteoclasts in vivo, suggesting β-blockers may directly impact osteoclasts. Consistent with this, we found propranolol directly suppresses osteoclast differentiation in vitro. Taken together, this work suggests a strong anti-osteoclastic effect of nonselective β-blockers in vivo, indicating that combining propranolol with PTH could be beneficial to patients with extremely low bone density. © 2022 American Society for Bone and Mineral Research (ASBMR).

Antihypertensive drugs demonstrate varying levels of hip fracture risk: A systematic review and meta-analysis

OBJECTIVE

By aggregating the literature, we evaluated the association between use of specific antihypertensive drugs and the risk of hip fractures compared with nonuse.

STUDY DESIGN AND SETTING

We systematically searched the Pubmed, Embase, and Cochrane databases from inception of each database until July 30, 2020 to identify articles including patients 18 years of age or older reporting on the association between antihypertensive drugs and the risk of hip fracture. Antihypertensive drugs were restricted to thiazides; beta-blockers; calcium-channel blockers; angiotensin-converting enzyme (ACE) inhibitors; and angiotensin receptor blockers. Nonusers encompass all patients that are not using the specific antihypertensive drug that has been reported. Unadjusted odds ratios with 95% confidence intervals (CIs) of the association between antihypertensive drug use and hip fractures were reported. Meta-analysis was performed when a minimum of five studies were identified for each antihypertensive drug class. Quality assessment was done using ROBINS-I tool. The GRADE approach was used to evaluate the certainty of the evidence.

RESULTS

Of 962 citations, 22 observational studies were included; 9 studies had a cohort design and 13 studies were case-control studies. No randomized controlled trials were identified. We found very low certainty of evidence that both thiazides (pooled odds ratio: 0.85, 95% CI 0.73 to 0.99, p = 0.04) as well as beta-blockers (pooled odds ratio: 0.88, 95% CI 0.79 to 0.98, p = 0.02) were associated with a reduced hip fracture risk as compared to specific nonuse. One study, reporting on angiotensin receptor blockers, also suggested a protective effect for hip fractures, whereas we found conflicting findings in four studies for calcium-channel blockers and in two studies for ACE inhibitors.

CONCLUSION

Among 22 observational studies, we found very low certainty of evidence that, compared to specific nonuse of antihypertensive drugs, use of thiazides, beta-blockers, and angiotensin receptor blockers were associated with a reduced protective hip fracture risk, while conflicting findings for calcium-channel blockers and ACE inhibitors were found. Given the low quality of included studies, further research -randomized controlled trials- are needed to definitively assess the causal relationship between specific antihypertensive drug classes and (relatively infrequent) hip fractures.

Elevated blood pressure, antihypertensive medications and bone health in the population: revisiting old hypotheses and exploring future research directions

Blood pressure and bone metabolism appear to share commonalities in their physiologic regulation. Specific antihypertensive drug classes may also influence bone mineral density. However, current evidence from existing observational studies and randomised trials is insufficient to establish causal associations for blood pressure and use of blood pressure-lowering drugs with bone health outcomes, particularly with the risks of osteoporosis and fractures. The availability and access to relevant large-scale biomedical data sources as well as developments in study designs and analytical approaches provide opportunities to examine the nature of the association between blood pressure and bone health more reliably and in greater detail than has ever been possible. It is unlikely that a single source of data or study design can provide a definitive answer. However, with appropriate considerations of the strengths and limitations of the different data sources and analytical techniques, we should be able to advance our understanding of the role of raised blood pressure and its drug treatment on the risks of low bone mineral density and fractures. As elevated blood pressure is highly prevalent and blood pressure-lowering drugs are widely prescribed, even small effects of these exposures on bone health outcomes could be important at a population level.

Regulation of bone metabolism mediated by β-adrenergic receptor and its clinical application

Recent studies have confirmed that β-adrenergic receptors (β-ARs) are expressed on the surface of osteoblasts and osteoclasts, and that the sympathetic nervous system can regulate bone metabolism by activating them. β-AR blockers (BBs) are commonly used in the treatment of cardiovascular diseases in the elderly. It is important to investigate whether BBs have a beneficial effect on bone metabolism in the treatment of cardiovascular diseases, so as to expand their clinical application. This article reviews the effects of BB on bone metabolism and the progress of clinical research.

Pharmacologic Interventions for Fracture Risk Reduction in the Oldest Old: What Is the Evidence?

With an increasingly older population, the proportion of patients 85 years or older seeking interventions to protect their musculoskeletal health is growing. Osteoporosis in the geriatric population presents unique diagnostic and therapeutic challenges. Multimorbidity, frailty, falls, polypharmacy, and other neurobehavioral factors influence our approach to fracture prevention in this population. The vast majority of the evidence from clinical trials establish pharmacologic fracture efficacy in postmenopausal women. The evidence is scarce for the oldest old men and women, a population also at risk for adverse events and mortality. Most studies show continued efficacy of pharmacologic interventions in this age group, although they are largely limited by small sample sizes. We herein review the available evidence of pharmacologic interventions for fracture risk reduction in this population and explore the emerging senotherapeutic interventions in the pipeline. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effect of Multimorbidity on Fragility Fractures in Community-Dwelling Older Adults: Shimane CoHRE Study

Fragility fractures (FFxs), which are a common musculoskeletal injury in older adults, is associated with an increased frequency of falls. Both FFxs and falls may result from drugs, habits, and co-occurring diseases. We aimed to evaluate the effects of various diseases on the risk of FFx. This retrospective study included 1420 individuals aged ≥60 years. We evaluated the history of clinical FFx and diseases using a detailed questionnaire and a health examination. The risk of comorbidities was assessed using the Age-Adjusted Charlson Comorbidity (AAC) Index. We performed binary logistic regression analysis to determine the risk of FFx and falls after adjusting for covariates. In elderly men, the incidence of FFx positively correlated with rheumatoid arthritis and parent's hip fracture. For elderly women, the incidence of FFx positively correlated with rheumatoid arthritis and antihypertensive drugs but was inversely associated with dyslipidemia and antilipidemic drugs. The FFX risk of older adults with an AAC Index ≥6 was higher than those with an AAC Index of 1-3. In addition, the AAC Index and falls were independently and strongly associated with a higher risk of FFx. Taken together, multimorbidity increases the risk of clinical FFx independent of falls in the community-dwelling elderly population.

Mechanisms Supporting the Use of Beta-Blockers for the Management of Breast Cancer Bone Metastasis

Simple Summary

Bone represents the most common site of metastasis for breast cancer and the establishment and growth of metastatic cancer cells within the skeleton significantly reduces the quality of life of patients and their survival. The interplay between sympathetic nerves and bone cells, and its influence on the process of breast cancer bone metastasis is increasingly being recognized. Several mechanisms, all dependent on β-adrenergic receptor signaling in stromal bone cells, were shown to promote the establishment of disseminated cancer cells into the skeleton. This review provides a summary of these mechanisms in support of the therapeutic potential of β-blockers for the early management of breast cancer metastasis.

Abstract

The skeleton is heavily innervated by sympathetic nerves and represents a common site for breast cancer metastases, the latter being the main cause of morbidity and mortality in breast cancer patients. Progression and recurrence of breast cancer, as well as decreased overall survival in breast cancer patients, are associated with chronic stress, a condition known to stimulate sympathetic nerve outflow. Preclinical studies have demonstrated that sympathetic stimulation of β-adrenergic receptors in osteoblasts increases bone vascular density, adhesion of metastatic cancer cells to blood vessels, and their colonization of the bone microenvironment, whereas β-blockade prevented these events in mice with high endogenous sympathetic activity. These findings in preclinical models, along with clinical data from breast cancer patients receiving β-blockers, support the pathophysiological role of excess sympathetic nervous system activity in the formation of bone metastases, and the potential of commonly used, safe, and low-cost β-blockers as adjuvant therapy to improve the prognosis of bone metastases.

Neurogenic Obesity and Skeletal Pathology in Spinal Cord Injury

Spinal cord injury (SCI) results in dramatic changes in body composition, with lean mass decreasing and fat mass increasing in specific regions that have important cardiometabolic implications. Accordingly, the recent Consortium for Spinal Cord Medicine (CSCM) released clinical practice guidelines for cardiometabolic disease (CMD) in SCI recommending the use of compartmental modeling of body composition to determine obesity in adults with SCI. This recommendation is guided by the fact that fat depots impact metabolic health differently, and in SCI adiposity increases around the viscera, skeletal muscle, and bone marrow. The contribution of skeletal muscle atrophy to decreased lean mass is self-evident, but the profound loss of bone is often less appreciated due to methodological considerations. General-population protocols for dual-energy x-ray absorptiometry (DXA) disregard assessment of the sites of greatest bone loss in SCI, but the International Society for Clinical Densitometry (ISCD) recently released an official position on the use of DXA to diagnose skeletal pathology in SCI. In this review, we discuss the recent guidelines regarding the evaluation and monitoring of obesity and bone loss in SCI. Then we consider the possible interactions of obesity and bone, including emerging evidence suggesting the possible influence of metabolic, autonomic, and endocrine function on bone health in SCI.

Role of deteriorated bone quality in the development of osteoporosis in pheochromocytoma and paraganglioma

CONTEXT

Pheochromocytoma (PHEO) and paraganglioma (PGL) (PHEO and PGL: PPGLs), catecholamine-producing tumors, represent an emerging cause of secondary osteoporosis. However, despite decreased bone mineral density (BMD), vertebral fracture (VF) is not associated with BMD in PPGLs.

OBJECTIVE

To evaluate whether deteriorated bone quality is involved in the development of osteoporosis in PPGLs.

PARTICIPANTS

Trabecular bone score (TBS), used to assess trabecular bone quality, was examined in 56 patients with PPGLs and 52 with non-functional adrenal tumors (AT). Radiograph of the spine was carried out in 35 patients with PPGLs, and TBS was analyzed in 18 patients with PPGLs at follow-up.

MAIN OUTCOME MEASURE

TBS and BMD at the lumbar spine in patients with PPGLs with and without VF.

RESULTS

PPGLs had a lower TBS (n = 56, 1.338 [1.294-1.420]) than non-functional AT (n = 52, 1.394 [1.342-1.444]; p = 0.033). Among those with PPGLs, patients with VF (n = 14, 1.314 [1.289-1.346]) had a lower TBS than those without VF (n = 21, 1.383 [1.324-1.426]; p = 0.046), despite no significant difference in BMD at the lumbar spine between the two groups (p = 0.501). An optimal cut-off level of TBS for diagnosing VF in PPGLs was 1.323, and its area under the curve was 0.702. The severity of catecholamine excess and maximal size of tumor were associated with decreased TBS in PPGLs patients (p = 0.016 and p = 0.020, respectively). Surgical resection of PPGLs improved TBS at follow-up, with 2.5% increase (p = 0.007).

CONCLUSIONS

This study provides evidence for the importance of deteriorated bone quality rather than decreased bone mass in the development of VF in PPGLs.

miRNA Mechanisms Underlying the Association of Beta Blocker Use and Bone Mineral Density

Osteoporosis is a debilitating and costly disease that causes fractures in 33% of women and 20% of men over the age of 50 years. Recent studies have shown that beta blocker (BB) users have higher bone mineral density (BMD) and decreased risk of fracture compared with non-users. The mechanism underlying this association is thought to be due to suppression of adrenergic signaling in osteoblasts, which leads to increased BMD in rodent models; however, the mechanism in humans is unknown. Also, several miRNAs are associated with adrenergic signaling and BMD in separate studies. To investigate potential miRNA mechanisms, we performed a cross-sectional analysis using clinical data, dual-energy X-ray absorptiometry (DXA) scans, and miRNA and mRNA profiling of whole blood from the Framingham Study's Offspring Cohort. We found nine miRNAs associated with BB use and increased BMD. In parallel network analyses, we discovered a subnetwork associated with BMD and BB use containing two of these nine miRNAs, miR-19a-3p and miR-186-5p. To strengthen this finding, we showed that these two miRNAs had significantly higher expression in individuals without incident fracture compared with those with fracture in an external data set. We also noted a similar trend in association between these miRNA and Z-score as calculated from heel ultrasound measures in two external cohorts (SOS-Hip and SHIP-TREND). Because miR-19a directly targets the ADRB1 mRNA transcript, we propose BB use may downregulate ADRB1 expression in osteoblasts through increased miR-19a-3p expression. We used enrichment analysis of miRNA targets to find potential indirect effects through insulin and parathyroid hormone signaling. This analysis provides a starting point for delineating the role of miRNA on the association between BB use and BMD. © 2020 American Society for Bone and Mineral Research (ASBMR).

Antihypertensive drug classes and the risk of hip fracture: results from the Swedish primary care cardiovascular database

OBJECTIVE

Hypertension and fractures related to osteoporosis are major public health problems that often coexist. This study examined the associations between exposure to different antihypertensive drug classes and the risk of hip fracture in hypertensive patients.

METHOD

We included 59 246 individuals, 50 years and older, diagnosed with hypertension during 2001-2008 in the Swedish Primary Care Cardiovascular Database. Patients were followed from 1 January 2006 (or the date of diagnosis of hypertension) until they had their first hip fracture, died, or reached the end of the study on 31 December 2012. Cox proportional hazards models were used to calculate the risk of hip fracture across types of antihypertensive medications, adjusted for age, sex, comorbidity, medications, and socioeconomic factors.

RESULTS

In total, 2593 hip fractures occurred. Compared to nonusers, current use of bendroflumethiazide or hydrochlorothiazide was associated with a reduced risk of hip fracture (hazard ratio 0.86; 95% CI 0.75-0.98 and hazard ratio 0.84; 95% CI 0.74-0.96, respectively), as was use of fixed drug combinations containing a thiazide (hazard ratio 0.69; 95% CI 0.57-0.83). Current use of loop diuretics was associated with an increased risk of hip fracture (hazard ratio 1.23; 95% CI 1.11-1.35). No significant associations were found between the risk of hip fracture and current exposure to beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aldosterone-receptor blockers or calcium channel blockers.

CONCLUSION

In this large observational study of hypertensive patients, the risk of hip fracture differed across users of different antihypertensive drugs, results that could have practical implications when choosing antihypertensive drug therapy.

Autonomic nervous system control of multiple myeloma

The autonomic nervous system (ANS), which consists of antagonistic sympathetic (adrenergic) and parasympathetic (cholinergic) arms, has emerged as an important regulator of neoplastic development, yet little is known about its role in multiple myeloma (MM). Clinical findings that anti-adrenergic β-blocker intake reduces risk of disease-specific death and overall mortality in patients with MM have indicated that adrenergic input may worsen myeloma outcome. However, preclinical studies using β-adrenergic receptor agonists or antagonists produced controversial results as to whether sympathetic pathways promote or inhibit myeloma. Retrospective outcome data demonstrating that high message levels of cholinergic receptor genes predict inferior survival in the Multiple Myeloma Research Foundation CoMMpass trial suggest that parasympathetic input may drive myeloma progression in a subset of patients. Here we review the ill-defined role of the ANS in MM, put myeloma in the context of other cancers, and discuss knowledge gaps that may afford exciting research opportunities going forward.

Evaluation of the effects of β1-selective beta-blockers on bone mineral density and fracture risk in postmenopausal women

Background/aim

β1-selective beta-blockers (BBs) are sympatholytic agents, and discerning their effects on bone health would be of great importance. This study aimed to investigate the influence of β1-selective BBs on bone mineral density (BMD) and fracture risk.

Materials and methods

This study included postmenopausal women who used β1-selective BBs (BB group) and control group. Sociodemographic characteristics, BMD and previous fragility fractures were recorded. Additionally, the 10-year probability of a major osteoporotic and hip fracture was calculated using the fracture risk assessment tool (FRAX).

Results

A total of 60 participants were included in the study. L1-4 and L2-4 BMD values were significantly higher in BB group than control group (P = 0.015 and P = 0.025, respectively). Moreover, T-scores of lumbar and femur total were significantly higher in the BB group. Two patients in BB and 6 patients in control group had previous fragility fracture. No statistically significant intergroup difference was noted regarding FRAX.

Conclusion

Based on our results, β1-selective BB usage was associated with higher BMD at the lumbar region in postmenopausal women.

Pheochromocytoma and paraganglioma: An emerging cause of secondary osteoporosis

CONTEXT

Pheochromocytoma (PHEO) and paraganglioma (PGL) (PHEO and PGL: PPGLs) are catecholamine-producing neuroendocrine tumors, which are known to be associated with low bone mineral density (BMD). However, it remains unknown whether PPGLs are associated with high prevalence of osteoporotic fracture and if so, whether their surgical resection improves BMD has been addressed.

OBJECTIVE

To evaluate the risk of vertebral fracture (VF) in PPGLs and the improvement of BMD after surgery.

DESIGN AND SETTINGS

A retrospective cross-sectional study in a single referral center.

PARTICIPANTS

This study included the following patients: 1) 49 patients with PPGLs and 61 patients with non-functional AT who were examined radiograph of the spine, 2) 23 patients with PPGLs who were examined BMD at follow-up.

INTERVENTION

1) The prevalence of VF was evaluated between PPGLs and non-functional AT. 2) In PPGLs, BMD was evaluated at baseline and after surgery.

RESULTS

PPGLs had a higher prevalence of VF (43% [21/49]) than non-functional AT (16% [10/61]; p = 0.002). PPGLs were associated with VF after adjusting for age and sex (odds ratio, 4.47; 95% confidence interval, 1.76-11.3; p = 0.001). In PPGLs, BMD at the lumber spine was improved (before: 0.855 ± 0.198 g/cm², after: 0.888 ± 0.169 g/cm², mean of the difference: 0.032 g/cm², p = 0.026), with 3.8% increase.

CONCLUSION

This study demonstrates that PPGLs was associated with VF and that their surgical resection contributes to the improvement of BMD in the trabecular bone. These observations support the notion that PPGLs are an emerging cause of secondary osteoporosis.

Suppression of tooth movement-induced sclerostin expression using β-adrenergic receptor blockers

OBJECTIVE

Regulation of bone metabolism by the sympathetic nervous system has recently been clarified. Tooth movement is increased by increased bone metabolic turnover due to sympathetic activation. This study aimed to compare the effects of the β-adrenergic receptor (β-AR) blockers atenolol (β1-AR blocker), butoxamine (β2-AR blocker) and propranolol (non-selective β-AR blocker) on tooth movement in spontaneously hypertensive rats (SHR) with sympathicotonia.

MATERIALS AND METHODS

Spontaneously hypertensive rats were divided into the following four groups: an SHR control group and groups treated with 0.1 mg/kg atenolol, 1 mg/kg butoxamine or 1 mg/kg propranolol (n = 6 rats/group). Atenolol, butoxamine or propranolol was administered daily to each treatment group, and orthodontic force was applied using a closed-coil spring. Finally, immunohistochemical analysis was performed for receptor activator of nuclear factor kappa-B ligand (RANKL) and sclerostin (SOST).

RESULTS

Atenolol, butoxamine and propranolol inhibited tooth movement and increased maxillary alveolar bone volume. Histological analysis revealed that these β-AR blockers decreased osteoclast activity on the compression side. Furthermore, immunohistochemical analysis revealed that atenolol, butoxamine and propranolol decreased the number of RANKL- and SOST-positive osteocytes on the compression side.

CONCLUSIONS

β-AR blockers decreased tooth movement and downregulated SOST in osteocytes, accompanied by increasing alveolar bone resorption.

The Role of Nerves in Skeletal Development, Adaptation, and Aging

The skeleton is well-innervated, but only recently have the functions of this complex network in bone started to become known. Although our knowledge of skeletal sensory and sympathetic innervation is incomplete, including the specific locations and subtypes of nerves in bone, we are now able to reconcile early studies utilizing denervation models with recent work dissecting the molecular signaling between bone and nerve. In total, sensory innervation functions in bone much as it does elsewhere in the body-to sense and respond to stimuli, including mechanical loading. Similarly, sympathetic nerves regulate autonomic functions related to bone, including homeostatic remodeling and vascular tone. However, more study is required to translate our current knowledge of bone-nerve crosstalk to novel therapeutic strategies that can be effectively utilized to combat skeletal diseases, disorders of low bone mass, and age-related decreases in bone quality.

Evaluation of bone health in patients with adrenal tumors

PURPOSE OF REVIEW

Adrenal tumors occur in 5% of population with higher prevalence in elderly. Patients with adrenal tumors present with overt hormonal excess in up to 15% of cases, and mild autonomous cortisol secretion in 30-40% of cases. Overt Cushing syndrome, mild autonomous cortisol secretion, pheochromocytoma, and primary aldosteronism have been associated with higher cardiovascular morbidity and mortality. Increasing experimental and clinical evidence also suggests that adrenal hormone excess is detrimental to bone health. This review aims to discuss the effect of cortisol, aldosterone, and catecholamine excess on bone metabolism, secondary osteoporosis, and fragility fractures.

RECENT FINDINGS

Several studies have reported that patients with hormonally active adrenal tumors demonstrate increased prevalence of fragility fractures incongruous to bone density scan findings. The utility of dual absorptiometry X-ray (DXA) in diagnosing secondary osteoporosis is unclear in patients with cortisol, aldosterone, and catecholamine excess. Trabecular bone score and bone turn over markers could serve as potential diagnostic tools in assessment of severity of bone disease in patients with hormonally active adrenal tumors.

SUMMARY

Adrenalectomy is the mainstay of therapy in patients with overt hormone production. Appropriate case detection strategies to identify patients at risk of fragility fractures are needed in patients not treated with adrenalectomy, such as bilateral primary aldosteronism and mild autonomous cortisol secretion.

Impact of the Autonomic Nervous System on the Skeleton

It is from the discovery of leptin and the central nervous system as a regulator of bone remodeling that the presence of autonomic nerves within the skeleton transitioned from a mere histological observation to the mechanism whereby neurons of the central nervous system communicate with cells of the bone microenvironment and regulate bone homeostasis. This shift in paradigm sparked new preclinical and clinical investigations aimed at defining the contribution of sympathetic, parasympathetic, and sensory nerves to the process of bone development, bone mass accrual, bone remodeling, and cancer metastasis. The aim of this article is to review the data that led to the current understanding of the interactions between the autonomic and skeletal systems and to present a critical appraisal of the literature, bringing forth a schema that can put into physiological and clinical context the main genetic and pharmacological observations pointing to the existence of an autonomic control of skeletal homeostasis. The different types of nerves found in the skeleton, their functional interactions with bone cells, their impact on bone development, bone mass accrual and remodeling, and the possible clinical or pathophysiological relevance of these findings are discussed.

Cortical bone is an extraneuronal site of norepinephrine uptake in adult mice

The sympathetic nervous system is a major efferent pathway through which the central nervous system controls the function of peripheral organs. Genetic and pharmacologic evidence in mice indicated that stimulation of the β2 adrenergic receptor (β2AR) in osteoblasts promotes bone loss, leading to the paradigm that high sympathetic nervous activity is deleterious to bone mass. However, considerably less data exist to understand the putative impact of endogenous norepinephrine (NE), released by sympathetic nerves, on bone homeostasis. In this study, we investigated the in vivo expression and activity of the norepinephrine transporter (NET), a membrane pump known to actively uptake NE from the extracellular space in presynaptic neurons. Consistent with previously published in vitro data showing NET uptake activity in differentiated osteoblasts, we were able to detect active NET-specific NE uptake in the mouse cortical bone compartment in vivo. This uptake was the highest in young mice and accordingly with an age-related reduction in NET uptake, NE bone content increased whereas Net RNA and protein expression decreased with age. Histologically, NET expression in adult mouse bones was detected in osteocytes via immunofluorescence. Lastly, taking advantage of tissue-specific fluorescent reporter mice, we used CLARITY imaging and light sheet microscopy to visualize the 3D distribution of sympathetic fibers in whole mount preparations of bone tissues. These analyses allowed us to detect tyrosine hydroxylase (TH)-positive sympathetic nerve fibers penetrating the cortical bone, where NET+ osteocytes reside. Together, these in vitro results support the existence of an age-dependent extraneuronal and osteocytic function of NET with potential to buffer the bone catabolic action of endogenous NE released by sympathetic nerves in vivo.

β-Blockers and bone health

Bone metabolism is controlled by endocrine, paracrine, and inflammatory signals that continuously operate in health and disease. While these signals are critical for skeletal adaptation during development, longitudinal growth, and repair, disturbances such as sex hormone deficiency or chronic inflammation have unambiguously been linked to bone loss and skeletal fragility across species. In the current issue of the JCI, Khosla et al. evaluated the role of sympathetic outflow and present evidence to support the idea that the sympathetic nervous system regulates bone metabolism in humans, primarily via the β1-adrenergic receptor.

Sympathetic β1-adrenergic signaling contributes to regulation of human bone metabolism

BACKGROUND

Evidence from rodent studies indicates that the sympathetic nervous system (SNS) regulates bone metabolism, principally via β2-adrenergic receptors (β2-ARs). Given the conflicting human data, we used multiple approaches to evaluate the role of the SNS in regulating human bone metabolism.

METHODS

Bone biopsies were obtained from 19 young and 19 elderly women for assessment of ADRB1, ADRB2, and ADRB3 mRNA expression. We examined the relationship of β-blocker use to bone microarchitecture by high-resolution peripheral quantitative CT in a population sample of 248 subjects. A total of 155 postmenopausal women were randomized to 1 of 5 treatment groups for 20 weeks: placebo; propranolol, 20 mg b.i.d.; propranolol, 40 mg b.i.d.; atenolol, 50 mg/day; or nebivolol, 5 mg/day. We took advantage of the β1-AR selectivity gradient of these drugs (propranolol [nonselective] << atenolol [relatively β1-AR selective] < nebivolol [highly β1-AR selective]) to define the β-AR selectivity for SNS effects on bone.

RESULTS

ADRB1 and ADRB2, but not ADRB3, were expressed in human bone; patients treated clinically with β1-AR-selective blockers had better bone microarchitecture than did nonusers, and relative to placebo, atenolol and nebivolol, but not propranolol, reduced the bone resorption marker serum C-telopeptide of type I collagen (by 19.5% and 20.6%, respectively; P < 0.01) and increased bone mineral density of the ultradistal radius (by 3.6% and 2.9%; P < 0.01 and P < 0.05, respectively).

CONCLUSIONS

These 3 independent lines of evidence strongly support a role for adrenergic signaling in the regulation of bone metabolism in humans, principally via β1-ARs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02467400.

FUNDING

This research was supported by the NIH (AG004875 and AR027065) and a Mayo Clinic Clinical and Translational Science Award (CTSA) (UL1 TR002377).

Bone Health in Adrenal Disorders

Secondary osteoporosis resulting from specific clinical disorders may be potentially reversible, and thus continuous efforts to find and adequately treat the secondary causes of skeletal fragility are critical to ameliorate fracture risk and to avoid unnecessary treatment with anti-osteoporotic drugs. Among the hyperfunctional adrenal masses, Cushing's syndrome, pheochromocytoma, and primary aldosteronism are receiving particularly great attention due to their high morbidity and mortality mainly by increasing cardiovascular risk. Interestingly, there is accumulating experimental and clinical evidence that adrenal hormones may have direct detrimental effects on bone metabolism as well. Thus, the present review discusses the possibility of adrenal disorders, especially focusing on pheochromocytoma and primary aldosteronism, as secondary causes of osteoporosis.

Osteogenic actions of metoprolol in an ovariectomized rat model of menopause

OBJECTIVE

Osteoporosis and hypertension are age-related chronic diseases with increased morbidity rates among postmenopausal women. Clinical epidemiological investigations have demonstrated that hypertensive patients treated with β1-selective β-blockers have a higher bone mineral density (BMD) and lower fracture risk. Nevertheless, no fundamental studies have examined the relationships between β1-selective β-blockers and these effects. The present study explored the effects and mechanisms of metoprolol in the in vitro treatment of osteoblasts and the in vivo treatment of ovariectomy-induced osteoporosis in rats.

METHODS

Primary osteoblasts were obtained by digestion of the cranial bones of 24-hour-old Sprague-Dawley rats. After metoprolol treatment, cell proliferation and differentiation capacities were assessed at the corresponding time points. In addition, 3-month-old female Sprague-Dawley rats (200-220 g) were divided into a sham-operated group (n = 8) and three ovariectomized (OVX) (bilateral removal of ovaries) groups as follows: vehicle (OVX; n = 8), low-dose metoprolol (L-M, oral, 120 mg/kg/d; n = 8), and high-dose metoprolol (H-M, oral, 240 mg/kg/d; n = 8). After 12 weeks of metoprolol treatment, BMD, microarchitecture, and biomechanical properties were evaluated.

RESULTS

The results indicated that the treatments with 0.01 to 0.1 μM metoprolol increased osteoblast proliferation, alkaline phosphatase activity, and calcium mineralization, and promoted the expression of osteogenic genes. The in vivo study indicated that administration of metoprolol to OVX rats resulted in maintenance of the BMDs of the L4 vertebrae. Moreover, amelioration of trabecular microarchitecture deterioration and preservation of bone biomechanical properties were detected in the trabecular bones of the OVX rats.

CONCLUSIONS

Our findings indicate that metoprolol prevents estrogen deficiency-induced bone loss by increasing the number and enhancing the biological functions of osteoblasts, implying its potential use as an alternative treatment for postmenopausal osteoporosis in hypertensive patients.

Chronic psychosocial stress disturbs long-bone growth in adolescent mice

Although a strong association between psychiatric and somatic disorders is generally accepted, little is known regarding the interrelationship between mental and skeletal health. Although depressive disorders have been shown to be strongly associated with osteoporosis and increased fracture risk, evidence from post-traumatic stress disorder (PTSD) patients is less consistent. Therefore, the present study investigated the influence of chronic psychosocial stress on bone using a well-established murine model for PTSD. C57BL/6N mice (7 weeks old) were subjected to chronic subordinate colony housing (CSC) for 19 days, whereas control mice were singly housed. Anxiety-related behavior was assessed in the open-field/novel-object test, after which the mice were euthanized to assess endocrine and bone parameters. CSC mice exhibited increased anxiety-related behavior in the open-field/novel-object test, increased adrenal and decreased thymus weights, and unaffected plasma morning corticosterone. Microcomputed tomography and histomorphometrical analyses revealed significantly reduced tibia and femur lengths, increased growth-plate thickness and reduced mineral deposition at the growth plate, suggesting disturbed endochondral ossification during long-bone growth. This was associated with reduced Runx2 expression in hypertrophic chondrocytes in the growth plate. Trabecular thicknesses and bone mineral density were significantly increased in CSC compared to singly housed mice. Tyrosine hydroxylase expression was increased in bone marrow cells located at the growth plates of CSC mice, implying that local adrenergic signaling might be involved in the effects of CSC on the skeletal phenotype. In conclusion, chronic psychosocial stress negatively impacts endochondral ossification in the growth plate, affecting both longitudinal and appositional bone growth in adolescent mice.

The Impact of Antihypertensive Medications on Bone Mineral Density and Fracture Risk

PURPOSE OF REVIEW

This review summarizes the impact of thiazide diuretics on fracture risk in older hypertensive individuals.

RECENT FINDINGS

We performed a post hoc evaluation of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial, a randomized, prospective, double blind hypertension study comparing a thiazide-like diuretic, a calcium channel blocker (CCB), and an angiotensin converting enzyme inhibitor (ACEi). We examined the risk of hip and pelvic fractures during the in-trial period (n = 22,180 participants; mean 4.9-year follow-up) and during the post-trial period using national data bases (n = 16,622 participants) (mean total follow-up 7.8 years). During the trial, participants randomized to the thiazide diuretic versus the CCB or the ACEi had a lower risk of fracture on adjusted analyses (HR 0.79 [95% CI, 0.63, 0.98], p = 0.04). Risk of fracture was significantly lower in participants randomized to the diuretic as compared to those randomized to the ACEi (HR 0.75 [95% CI, 0.58, 0.98]; p = 0.04), but not significantly different compared to the CCB (HR 0.87 [95% CI, 0.71, 1.09]; p = 0.17). Over the entire trial and post-trial period of follow-up, the cumulative incidence of fractures was non-significantly lower in participants assigned to the diuretic vs assignment to the ACEi or the CCB (HR 0.87 [0.74-1.03], p = 0.10) and versus each medication separately. These findings establish a benefit for thiazide diuretic treatment for the prevention of fractures versus other commonly used antihypertensive medications using prospective, randomized data. The effects of the thiazide diuretic on bone appear to be long lasting.

Association between renin-angiotensin-aldosterone system blockade and future osteoporotic fracture risk in hypertensive population: A population-based cohort study in Taiwan

Tissue renin-angiotensin-aldosterone system (RAAS) activation in sites of osteoporosis had been demonstrated in animal studies; however, the possibility of RAAS blockade to prevent future osteoporotic fracture had rarely been verified in clinical studies. We Used the Taiwan Longitudinal Health insurance database 2000 to 2008, the cohort study comprised patients age over 40 with a recorded new diagnosis of hypertension between January 1, 2000 to December 31, 2008, in addition, patients who had diagnosis of osteoporosis before the date of cohort enter were excluded. After the definite diagnosis of hypertension, each patient was followed until osteoporotic fracture happened or the end of 2008. The occurrence of osteoporotic fracture was evaluated in patients who either were or without taking RAAS blockade agents. Cox proportional hazard regressions were used to evaluate the osteoporotic fracture incidence after adjusting for known confounding factors. In total, 57,132 hypertensive patients comprised the study cohort. Our study results showed that the incidence of osteoporosis fracture in the whole cohort was significantly higher in the RAAS blockade non-user group than the user group. This phenomenon was observed in both sex and all age categories. Sensitivity analysis further showed the concordant lower osteoporosis fracture risk in patients with various RAAS blockers usage durations; the risk of osteoporosis fracture was the lowest in those drug use >365 days when compared with the non-user cohort. In conclusion, our study result demonstrated the lower future osteoporotic fracture risk in hypertensive subjects who received long term RAAS blocker treatment.

Lower Bone Mass and Higher Bone Resorption in Pheochromocytoma: Importance of Sympathetic Activity on Human Bone

CONTEXT

Despite the apparent biological importance of sympathetic activity on bone metabolism in rodents, its role in humans remains questionable.

OBJECTIVE

To clarify the link between the sympathetic nervous system and the skeleton in humans.

DESIGN, SETTING, AND PATIENTS

Among 620 consecutive subjects with newly diagnosed adrenal incidentaloma, 31 patients with histologically confirmed pheochromocytoma (a catecholamine-secreting neuroendocrine tumor) and 280 patients with nonfunctional adrenal incidentaloma were defined as cases and controls, respectively.

RESULTS

After adjustment for confounders, subjects with pheochromocytoma had 7.2% lower bone mass at the lumbar spine and 33.5% higher serum C-terminal telopeptide of type 1 collagen (CTX) than those without pheochromocytoma (P = 0.016 and 0.001, respectively), whereas there were no statistical differences between groups in bone mineral density (BMD) at the femur neck and total hip and in serum bone-specific alkaline phosphatase (BSALP) level. The odds ratio (OR) for lower BMD at the lumbar spine in the presence of pheochromocytoma was 3.31 (95% confidence interval, 1.23 to 8.56). However, the ORs for lower BMD at the femur neck and total hip did not differ according to the presence of pheochromocytoma. Serum CTX level decreased by 35.2% after adrenalectomy in patients with pheochromocytoma, whereas serum BSALP level did not change significantly.

CONCLUSIONS

This study provides clinical evidence showing that sympathetic overstimulation in pheochromocytoma can contribute to adverse effects on human bone through the increase of bone loss (especially in trabecular bone), as well as bone resorption.

Repurposing of approved cardiovascular drugs

Research and development of new drugs requires both long time and high costs, whereas safety and tolerability profiles make the success rate of approval very low. Drug repurposing, applying known drugs and compounds to new indications, has been noted recently as a cost-effective and time-unconsuming way in developing new drugs, because they have already been proven safe in humans. In this review, we discuss drug repurposing of approved cardiovascular drugs, such as aspirin, beta-blockers, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, cardiac glycosides and statins. Regarding anti-tumor activities of these agents, a number of experimental studies have demonstrated promising pleiotropic properties, whereas all clinical trials have not shown expected results. In pathological conditions other than cancer, repurposing of cardiovascular drugs is also expanding. Numerous experimental studies have reported possibilities of drug repurposing in this field and some of them have been tried for new indications ('bench to bedside'), while unexpected results of clinical studies have given hints for drug repurposing and some unknown mechanisms of action have been demonstrated by experimental studies ('bedside to bench'). The future perspective of experimental and clinical studies using cardiovascular drugs are also discussed.

Clonidine increases bone resorption in humans

SUMMARY

Inhibition of sympathetic signaling to bone reduces bone resorption in rodents. In contrast, we show that pharmacological reduction of the sympathetic tone increases bone resorption in humans in vivo. This effect does not appear to be mediated via a direct pharmacological effect on the osteoclast.

INTRODUCTION

Inhibition of sympathetic signaling to bone reduces bone resorption in rodents. It is uncertain whether a similar role for the sympathetic nervous system exists in humans. The sympathetic tone can be reduced by clonidine, which acts via alpha-2-adrenergic receptors in the brainstem. Our objective was to determine the effect of clonidine on bone turnover in humans.

METHODS

The acute effect of a single oral dose of 0.3 mg clonidine on serum bone turnover markers (C-terminal cross-linking telopeptides of collagen type I (CTx), a marker for bone resorption, and procollagen type 1 N propeptide (P1NP), a marker for bone formation) was determined in a randomized crossover design in 12 healthy volunteers, aged 18-70 years. In addition, we assessed the effect of clonidine on the number of tartrate-resistant acid phosphatase-positive multinucleated cells (TRAcP(+) MNCs) and bone resorption.

RESULTS

CTx concentrations increased after clonidine treatment compared to the control condition (p = 0.035). P1NP concentrations were not affected by clonidine (p = 0.520). In vitro, clonidine had no effect on the number of TRAcP(+) MNCs (p = 0.513) or on bone resorption (p = 0.996).

CONCLUSIONS

We demonstrated that clonidine increases bone resorption in humans in vivo. This effect does not appear to be mediated via a direct effect on the osteoclast.

Risk of hip fracture among older people using antihypertensive drugs: a nationwide cohort study

Background

Many people with a high risk of hip fracture have coexisting cardiovascular diseases. We aimed to examine associations between exposure to antihypertensive drugs and the risk of hip fracture among older people.

Methods

We conducted a cohort study of the 906,422 people born before 1945 and living in Norway in 2005. We obtained information on all prescriptions of antihypertensive drugs dispensed (the Norwegian Prescription Database) in 2004–2010 and the dates of primary hip fractures (the Norwegian Hip Fracture Registry) in 2005–2010. We compared the incidence rates of hip fracture during the time people were exposed and unexposed to antihypertensive drugs by calculating the standardized incidence ratio (SIR).

Results

Altogether, 39,938 people experienced a primary hip fracture (4.4 %). The risk of hip fracture was decreased among people exposed to thiazides (SIR 0.7, 95 % confidence interval (CI) 0.6–0.7), beta-blockers (SIR 0.7, 95 % CI 0.7–0.8), calcium channel blockers (SIR 0.8, 95 % CI 0.8–0.8), angiotensin II receptor blockers (SIR 0.8, 95 % CI 0.7–0.8), ACE inhibitor/thiazide combination products (SIR 0.7, 95 % CI 0.6–0.7) and angiotensin II receptor blocker/thiazide combination products (SIR 0.6, 95 % CI 0.6–0.6). Use of loop diuretics and ACE inhibitors (plain products) was associated with increased fracture risk in people born after 1924, and with decreased risk in those born before 1925. The protective associations were stronger among exposed men than among exposed women for all drugs except loop diuretics. The SIRs decreased with increasing age among exposed people, except for thiazides and angiotensin II receptor blockers.

Conclusions

We found a reduced risk of hip fracture associated with overall use of most antihypertensive drugs, but an increased risk with loop diuretics and ACE inhibitors among people younger than 80 years and in new users of loop diuretics. This may have great impact at the population level, because the use of antihypertensive drugs is widespread in people at risk of hip fracture. Clinical studies are needed to further explore these associations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-015-0154-5) contains supplementary material, which is available to authorized users.

Association of polymorphisms in the beta-2 adrenergic receptor gene with fracture risk and bone mineral density

Signaling through the beta-2 adrenergic receptor (B2AR) on the osteoblast influences bone remodeling in rodents. In the B2AR gene, three polymorphisms influence receptor function. We show that these polymorphisms are not associated with fracture risk or bone mineral density in the UCP, Rotterdam Study, and GEFOS cohorts.

INTRODUCTION

Signaling through the beta-2 adrenergic receptor (B2AR) on the osteoblast influences bone remodeling in rodents. In the B2AR gene, three polymorphisms are known to influence receptor function in vitro and in vivo (rs1042713, rs1042714, and rs1800888). We examined the role of these polymorphisms in the B2AR gene on human bone metabolism.

METHODS

We performed nested case-control studies to determine the association of these polymorphisms with fracture risk in the Utrecht Cardiovascular Pharmacogenetics (UCP) cohort and in three cohorts of the Rotterdam Study. We also determined the association of these polymorphisms with bone mineral density (BMD) in the GEFOS Consortium. UCP contains drug-dispensing histories from community pharmacies linked to national registrations of hospital discharges in the Netherlands. The Rotterdam Study is a prospective cohort study investigating demographics and risk factors of chronic diseases. GEFOS is a large international collaboration studying the genetics of osteoporosis. Fractures were defined by ICD-9 codes 800-829 in the UCP cohort (158 cases and 2617 unmatched controls) and by regular X-ray examinations, general practitioner, and hospital records in the Rotterdam Study (2209 cases and 8559 unmatched controls). BMD was measured at the femoral neck and lumbar spine using dual-energy X-ray absorptiometry in GEFOS (N = 32,961).

RESULTS

Meta-analysis of the two nested case-control studies showed pooled odds ratios of 0.98 (0.91-1.05, p = 0.52), 1.04 (0.97-1.12, p = 0.28), and 1.16 (0.83-1.62, p = 0.38) for the associations between rs1042713, rs1042714, and rs1800888 per minor allele and fractures, respectively. There were no significant associations of the polymorphisms and BMD in GEFOS.

CONCLUSION

In conclusion, polymorphisms in the beta-2 adrenergic receptor gene are not associated with fracture risk or BMD.

Mechanisms of Normalisation of Bone Metabolism during Recovery from Hyperthyroidism: Potential Role for Sclerostin and Parathyroid Hormone

Sclerostin, a protein expressed by osteocytes, is a negative regulator of bone formation. The aim of the study was to investigate the relationship between parathyroid hormone (PTH) and markers of bone metabolism and changes of sclerostin concentrations before and after treatment of hyperthyroidism. Patients and Methods. The study involved 33 patients (26 women), age (mean ± SD) 48 ± 15 years, with hyperthyroidism. Serum sclerostin, PTH, calcium, and bone markers [osteocalcin (OC) and collagen type I cross-linked C-telopeptide I (CTX)] were measured at diagnosis of hyperthyroidism and after treatment with thiamazole. Results. After treatment of hyperthyroidism a significant decrease in free T3 (FT3) and free T4 (FT4) concentrations was accompanied by marked decrease of serum sclerostin (from 43.7 ± 29.3 to 28.1 ± 18.4 pmol/L; p < 0.001), OC (from 35.6 ± 22.0 to 27.0 ± 14.3 ng/mL; p < 0.001), and CTX (from 0.49 ± 0.35 to 0.35 ± 0.23 ng/dL; p < 0.005), accompanied by an increase of PTH (from 29.3 ± 14.9 to 39.8 ± 19.8; p < 0.001). During hyperthyroidism there was a positive correlation between sclerostin and CTX (r s = 0.41, p < 0.05) and between OC and thyroid hormones (with FT3  r s = 0.42, with FT4  r s = 0.45, p < 0.05). Conclusions. Successful treatment of hyperthyroidism results in a significant decrease in serum sclerostin and bone markers concentrations, accompanied by an increase of PTH.

Antihypertensive medications, bone mineral density, and fractures: a review of old cardiac drugs that provides new insights into osteoporosis

Osteoporosis is increasing in prevalence and importance as society's age, with the clinical consequence of fractures of the hip, spine, and upper extremity, leading to impaired quality of life, loss of function and independence, and increased morbidity and mortality. A major risk factor for osteoporosis is older age, and cardiovascular diseases also share this risk factor; therefore, osteoporosis and cardiovascular disease often coexist and share risk factors. Medications used for the treatment of cardiovascular diseases, in particular antihypertensive drugs, have been shown in a variety of studies of varying designs to modulate bone health in both a positive or negative manner. In this article, we reviewed the pharmacology, potential mechanisms, and possible effects on bone mineral density and fracture risk of commonly prescribed antihypertensive medications, including thiazide and non-thiazide diuretics, beta-blockers, calcium channel blockers, renin-angiotensin-aldosterone system agents, and nitrates.