Protective effect of beta blockers in postmenopausal women: influence on fractures, bone density, micro and macroarchitecture

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.

β2-adrenoceptors kick osteoarthritis - Time to rethink prevention and therapy

Although, during the past decades, substantial advances emerged in identifying major local and systemic factors contributing to initiation and progression of osteoarthritis (OA), some neuroendocrine mechanisms are still not understood or even neglected when thinking about novel therapeutic options. One of which is the sympathetic nervous system that exhibits various OA-promoting effects in different tissues of the joint. Interestingly, the β2-adrenoceptor (AR) mediates the majority of these effects as demonstrated by several in vitro, in vivo as well as in clinical studies. This review article does not only summarize studies of the past two decades demonstrating that the β2-AR plays an OA-promoting role in different tissues of the joint but also aims to encourage the reader to think about next-level research to discover novel and innovative preventive and/or therapeutic strategies targeting the β2-AR in OA.

Deteriorated bone microarchitecture caused by sympathetic overstimulation in pheochromocytoma and paraganglioma

PURPOSE

Despite the potentially destructive effect of sympathetic activity on bone metabolism, its impact on bone microarchitecture, a key determinant of bone quality, has not been thoroughly investigated. This study aims to evaluate the impact of sympathetic activity on bone microarchitecture and bone strength in patients with pheochromocytoma and paraganglioma (PPGL).

METHODS

A cross-sectional study was conducted in 38 PPGL patients (15 males and 23 females). Bone turnover markers serum procollagen type 1 N-terminal propeptide (P1NP) and β-carboxy-terminal crosslinked telopeptide of type 1 collagen (β-CTX) were measured. 24-h urinary adrenaline (24hUE) and 24-h urinary norepinephrine levels (24hUNE) were measured to indicate sympathetic activity. High-resolution peripheral quantitative computed tomography (HR-pQCT) was conducted to evaluate bone microarchitecture in PPGL patients and 76 age-, sex-matched healthy controls (30 males and 46 females). Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry (DXA) simultaneously.

RESULTS

PPGL patients had a higher level of β-CTX. HR-pQCT assessment revealed that PPGL patients had notably thinner and more sparse trabecular bone (decreased trabecular number and thickness with increased trabecular separation), significantly decreased volume BMD (vBMD), and bone strength at both the radius and tibia compared with healthy controls. The deterioration of Tt.vBMD, Tb.Sp, and Tb.1/N.SD was more pronounced in postmenopausal patients compared with the premenopausal subjects. Moreover, subjects in the highest 24hUNE quartile (Q4) showed markedly lower Tb.N and higher Tb.Sp and Tb.1/N.SD at the tibia than those in the lowest quartile (Q1). Age-related bone loss was also exacerbated in PPGL patients to a certain extent.

CONCLUSIONS

PPGL patients had significantly deteriorated bone microarchitecture and strength, especially in the trabecular bone, with an increased bone resorption rate. Our findings provide clinical evidence that sympathetic overstimulation may serve as a secondary cause of osteoporosis, especially in subjects with increased sympathetic activity.

Autonomic neural regulation in mediating the brain-bone axis: mechanisms and implications for regeneration under psychological stress

Efficient regeneration of bone defects caused by disease or significant trauma is a major challenge in current medicine, which is particularly difficult yet significant under the emerging psychological stress in the modern society. Notably, the brain-bone axis has been proposed as a prominent new concept in recent years, among which autonomic nerves act as an essential and emerging skeletal pathophysiological factor related to psychological stress. Studies have established that sympathetic cues lead to impairment of bone homeostasis mainly through acting on mesenchymal stem cells (MSCs) and their derivatives with also affecting the hematopoietic stem cell (HSC)-lineage osteoclasts, and the autonomic neural regulation of stem cell lineages in bone is increasingly recognized to contribute to the bone degenerative disease, osteoporosis. This review summarizes the distribution characteristics of autonomic nerves in bone, introduces the regulatory effects and mechanisms of autonomic nerves on MSC and HSC lineages, and expounds the crucial role of autonomic neural regulation on bone physiology and pathology, which acts as a bridge between the brain and the bone. With the translational perspective, we further highlight the autonomic neural basis of psychological stress-induced bone loss and a series of pharmaceutical therapeutic strategies and implications toward bone regeneration. The summary of research progress in this field will add knowledge to the current landscape of inter-organ crosstalk and provide a medicinal basis for the achievement of clinical bone regeneration in the future.

Three-dimensional visualization of neural networks inside bone by Osteo-DISCO protocol and alteration of bone remodeling by surgical nerve ablation

Bone is one of the largest organ systems in humans and is considered to regulate whole-body homeostasis in cooperation with other organs. We have previously reported that a sympathetic or sensory nervous system inside bone regulates bone homeostasis. However, the detailed regulatory mechanism, including the distribution of nerves inside bone, remains unknown. Although a two-dimensional histological analysis has been widely used to evaluate the structure of nerves or blood vessels, the actual structure is more complex, suggesting that it should be evaluated three-dimensionally. Here, we established a novel bone tissue clearing technique (Osteo-DISCO) for murine bones which enabled us to visualize the detailed distribution of nerves or blood vessels inside bone. Interestingly, we found that there is a specific nerve entry site in each long bone and that surgical ablation of the specific nerve fibers entering bone tissue led to decreased bone formation and impaired bone regeneration. Furthermore, we revealed that the administration of calcitonin gene-related peptide (CGRP), which is primarily released from sensory nerves, suppressed the bone loss caused by surgical nerve ablation. An in vitro study also indicated that CGRP directly promotes osteoblast activity, suggesting that sensory nerves inside bone can regulate osteogenesis via the secretion of CGRP.

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.

Neuro-immune-endocrine mechanisms with poor adherence to aromatase inhibitor therapy in breast cancer

As the most commonly used endocrine therapy regimen for patients with hormone receptor-positive (HR+) breast cancer (BC) at present, aromatase inhibitors (AIs) reduce the risk of localized and distant recurrence, contralateral BC and secondary cancer, and prolong disease-free survival. Clinical data show that poor adherence during AI treatment is mainly attributed to muscle and joint pain, fatigue, anxiety, depression and sleep disturbances during treatment. The rapid decline of estrogen caused by AIs in a short period of time enhances sympathetic activity, activates T cells in the body, produces inflammatory factors such as tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and interleukin (IL)-17A, and promotes the occurrence of inflammation and bone loss. This article reviewed the mechanism of poor dependence on AIs in BC patients from the neuro-immuno-endocrine (NIE) perspective and provided clues for clinical intervention against poor adherence.

Targeted inhibition of osteoclastogenesis reveals the pathogenesis and therapeutics of bone loss under sympathetic neurostress

Sympathetic cues via the adrenergic signaling critically regulate bone homeostasis and contribute to neurostress-induced bone loss, but the mechanisms and therapeutics remain incompletely elucidated. Here, we reveal an osteoclastogenesis-centered functionally important osteopenic pathogenesis under sympatho-adrenergic activation with characterized microRNA response and efficient therapeutics. We discovered that osteoclastic miR-21 was tightly regulated by sympatho-adrenergic cues downstream the β2-adrenergic receptor (β₂AR) signaling, critically modulated osteoclastogenesis in vivo by inhibiting programmed cell death 4 (Pdcd4), and mediated detrimental effects of both isoproterenol (ISO) and chronic variable stress (CVS) on bone. Intriguingly, without affecting osteoblastic bone formation, bone protection against ISO and CVS was sufficiently achieved by a (D-Asp₈)-lipid nanoparticle-mediated targeted inhibition of osteoclastic miR-21 or by clinically relevant drugs to suppress osteoclastogenesis. Collectively, these results unravel a previously underdetermined molecular and functional paradigm that osteoclastogenesis crucially contributes to sympatho-adrenergic regulation of bone and establish multiple targeted therapeutic strategies to counteract osteopenias under stresses.

Do antihypertensive medications effect the mandibular cortical bone thickness? A study using cone beam computed tomography images

OBJECTIVE

The aim of this study was to measure the association between antihypertensive medication use and mandibular cortical thickness.

STUDY DESIGN

This retrospective cross-sectional study was comprised of a study sample of 169 patients aged 40 to 69. Cone beam computed tomography scans were examined. The buccal cortical thickness of the mandibular ramus was measured. Participants were separated into the control or study group based on use of antihypertensive medications. The predictor variable was the use of antihypertensive medications. The primary outcome variable was cortical thickness of the mandible. Age was identified as a covariate affecting the outcome variable. The data was analyzed with a one-way analysis of covariance (ANCOVA) to remove the effect of age on the outcome variable. The groups were subdivided based on the sex of the patient.

RESULTS

The study sample was composed of 169 patients with a mean age of 52.1, and 54% were female. There were 67 patients in the antihypertensive group (39.6%). A mean difference of 0.21 mm was found (P = .0010, 95% CI 0.09, 0.34 mm). The difference persisted after adjusting for age with one-way ANCOVA testing (P < .001).

CONCLUSIONS

This study suggests that there may be an association between antihypertensive use and mandibular cortical thickness. Age may be an effect modifier with the effect increasing in older patients.

Sympathetic Neurostress Drives Osteoblastic Exosomal MiR-21 Transfer to Disrupt Bone Homeostasis and Promote Osteopenia

Innervation and extracellular vesicle secretion co-exist in the local tissue microenvironment for message transfer, but whether they are interconnected to regulate organ homeostasis remains unknown. Sympatho-adrenergic activation is implicated in stress-induced depression and leads to bone loss, but the mechanisms and therapeutics are incompletely elucidated. Here, it is revealed that sympathetic neurostress through the β_1/2 -adrenergic receptor (β1/2-AR) signaling triggers the transcription response of a microRNA, miR-21, in osteoblasts, which is transferred to osteoclast progenitors via exosomes for dictating osteoclastogenesis. After confirming that miR-21 deficiency retards the β1/2-AR agonist isoproterenol (ISO)-induced osteopenia, it is shown that the pharmacological inhibition of exosome release by two clinically-relevant drugs, dimethyl amiloride and omeprazole, suppresses osteoblastic miR-21 transfer and ameliorates bone loss under both ISO and chronic variable stress (CVS)-induced depression conditions. A targeted delivery approach to specifically silence osteoblastic miR-21 is further applied, which is effective in rescuing the bone remodeling balance and ameliorating ISO- and CVS-induced osteopenias. These results decipher a previously unrecognized paradigm that neural cues drive exosomal microRNA communication to regulate organ homeostasis and help to establish feasible strategies to counteract bone loss under psychological stresses.

Pharmacogenomic Effects of β-Blocker Use on Femoral Neck Bone Mineral Density

CONTEXT

Recent studies have shown that β-blocker (BB) users have a decreased risk of fracture and higher bone mineral density (BMD) compared to nonusers, likely due to the suppression of adrenergic signaling in osteoblasts, leading to increased BMD. There is also variability in the effect size of BB use on BMD in humans, which may be due to pharmacogenomic effects.

OBJECTIVE

To investigate potential single-nucleotide variations (SNVs) associated with the effect of BB use on femoral neck BMD, we performed a cross-sectional analysis using clinical data, dual-energy x-ray absorptiometry, and genetic data from the Framingham Heart Study's (FHS) Offspring Cohort. We then sought to validate our top 4 genetic findings using data from the Rotterdam Study, the BPROOF Study, the Malta Osteoporosis Fracture Study (MOFS), and the Hertfordshire Cohort Study.

METHODS

We used sex-stratified linear mixed models to determine SNVs that had a significant interaction effect with BB use on femoral neck (FN) BMD across 11 gene regions. We also evaluated the association of our top SNVs from the FHS with microRNA (miRNA) expression in blood and identified potential miRNA-mediated mechanisms by which these SNVs may affect FN BMD.

RESULTS

One variation (rs11124190 in HDAC4) was validated in females using data from the Rotterdam Study, while another (rs12414657 in ADRB1) was validated in females using data from the MOFS. We performed an exploratory meta-analysis of all 5 studies for these variations, which further validated our findings.

CONCLUSION

This analysis provides a starting point for investigating the pharmacogenomic effects of BB use on BMD measures.

Evaluation of the Effects of ß-Adrenergic Receptor-Propranolol on Osseointegration of the Titanium Implants

ABSTRACT

This study aimed to investigate the effects of systemic propranol on the osseointegration of titanium implants. After the surgical insertion of titanium implants into the metaphyseal part of the tibial bone, the rats were randomly divided into 2 equal groups: the control (CNT) (n = 10) and propranol group (P) (n = 10); CNT: Rats received no further treatment during the 4 week experimental period after surgery. Rats received 10 mg/kg propranol in every day during the 4 week experimental period in PRP group after the surgical insertion of the implants. After the experimental period, the rats were euthanized, blood serum were collected to biochemical analysis and the implants and surrounding bone tissues were used for the histopathologic analysis. To analysis of the data between tests and controls student T test was used. There were no significant differences in the biochemical parameters (alcaline phosphatase, calcium, phosphor) of the groups (P > 0.05). Bone implant connection (BIC) ratios was detected higher in test animals compared with the controls (P < 0.05). Systemic propranolol may increases titanium implant osseointegration.

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.

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).

Stress-Related Amygdala Metabolic Activity Is Associated With Low Bone Mineral Density in Postmenopausal Women: A Pilot 18F-FDG PET/CT Study

BACKGROUND

Psychological stress is associated with postmenopausal osteoporosis. However, the underlying mechanism of stress-related brain neural activity with osteoporosis is not fully elucidated. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is an established method to evaluate the metabolic activity of brain amygdala, a region involved in stress. We aimed to evaluate the relationship between metabolic activity of amygdala (AmygA) and osteoporosis in postmenopausal women.

MATERIALS AND METHODS

A total of 115 postmenopausal women who underwent ¹⁸F-FDG PET/CT and dual-energy X-ray absorptiometry for routine health screening were enrolled in this study. AmygA was defined as the maximum standardized uptake value (SUVmax) of amygdala divided by the mean SUV of temporal lobe. The levels of psychological stress were measured using the Psychosocial Well-being Index-Short Form (PWI-SF).

RESULTS

The participants with osteoporosis exhibited significantly higher AmygA than without osteoporosis (0.81 ± 0.16 vs. 0.61 ± 0.13, p < 0.001). The AmygA value of 0.69 was suggested as an optimal cut-off value to identify participant with osteoporosis (sensitivity; 79.1%, specificity; 83.3%, area under the curve; 0.841, p < 0.001). Furthermore, AmygA showed significant association with osteoporosis in postmenopausal woman by multivariate analysis. Psychological stress scale (PWI-SF) was well correlated with AmygA and AmygA was highest in high stress risk-, intermediate in moderate stress risk-, and lowest in healthy group.

CONCLUSIONS

AmygA measured by ¹⁸F-FDG PET/CT is associated with osteoporosis in postmenopausal women. Our results provide the possibility that stress-related neurobiological activity involving amygdala is linked with postmenopausal osteoporosis.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.

Association of Beta Blocker Use With Bone Mineral Density in the Framingham Osteoporosis Study: A Cross-Sectional Study

Some, but not all, prior observational studies have shown that beta blocker (BB) use is associated with lower fracture risk and higher bone mineral density (BMD). Rodent studies show the mechanism to involve the reduction in the effects of beta‐adrenergic signaling on bone remodeling. Because previous studies did not have detailed information on dose, duration, and beta‐1 selectivity, we examined these in a cross‐sectional analysis of the association between BB use and hip and spine BMD using DXA with the Offspring Cohort of the Framingham Heart Study. The sample size was n = 1520, and 397 individuals used BBs. We used propensity score modeling to balance a comprehensive set of covariates using inverse probability of treatment weighting (IPTW) to minimize bias due to treatment indication. We found significant differences in BMD between BB users and non‐users for three of four BMD measurements (femoral neck: 3.1%, 95% CI, 1.1% to 5.0%; total femur: 2.9%, 95% CI, 0.9% to 4.9%; femoral trochanter: 2.4%, 95% CI, −0.1% to 5.0%; and lumbar spine: 2.7%, 95% CI, 0.2% to 5.0%). Results were found to be similar between sexes although the magnitude of association was larger for women. Similar differences were estimated for beta‐1 selective and nonselective BBs compared with no BB use. We modeled dose in categories (no BB use, low‐dose, high‐dose) and as a continuous variable and found an increasing dose response that levels off at higher doses. Finally, associations were similar for short‐term versus long‐term (≤4 years versus >4 years) use. In summary, this large comprehensive study shows that BB use is associated with higher BMD in a dose‐related manner regardless of beta‐1 specificity and duration of use, which supports the conduct of a randomized clinical trial of BBs for achieving improvements in BMD for individuals at risk of bone loss with aging. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Noninvasive transdermal delivery of liposomes by weak electric current

Noninvasive transdermal drug delivery (NTDD) offers an exciting new method of administration relative to conventional routes, but is associated with some challenges. Liposomes are capable of encapsulating transdermally-unfavorable drugs. However, the horny layer of skin is a significant barrier that limits efficient transdermal delivery of liposomes. Iontophoresis using weak electric current (WEC) represents a NTDD technology. WEC treatment of liposomes applied to the skin surface improves transdermal penetration of encapsulated drugs by cooperative effects. In this review, we provide an overview of the application of WEC/liposomes for transdermal delivery of macromolecules and low molecular weight drugs. We compare the transdermal delivery and therapeutic efficiency of the combined system with conventional routes of administration and their individual use. We discuss a novel perspective on the mechanism of WEC-mediated transdermal delivery of liposomes, which suggests that WEC activates the intracellular signaling pathway for transdermal permeation and induces unique endocytosis in skin cells.

Association between Hypertension, Antihypertensive Drugs, and Osteoporosis in Postmenopausal Syrian Women: A Cross-Sectional Study

BACKGROUND

Osteoporosis and hypertension are frequent and often coexisting diseases among the elderly. Recent studies suggested that both diseases may share the same etiopathology. Moreover, the treatment of hypertension can affect the bone mineral density and worsen osteoporosis. The aim of this cross-sectional study was to assess the prevalence of low bone mass and osteoporosis in postmenopausal Syrian women and investigate their relationship with hypertension and antihypertensive drugs.

METHODS

813 postmenopausal women were involved in this cross-sectional study, aged between 40 and 96 yrs. Their menopause duration ranged between 1 and 43 yrs. Bone mineral density was measured using a dual-energy X-ray absorptiometry at the total lumbar spine (L1-L4) and left hip. T-score values were used to determine the diagnosis of osteoporosis. The existence of HTN was defined as blood pressure ≥130/85 mmHg or a history of hypertension medication.

RESULTS

Using the world health organization criteria, 24% had osteoporosis and 45.2% had low bone mass. The incidence of osteoporosis and low bone mass significantly increased with age and menopause duration and decreased with BMI. Prevalence of hypertension was almost equal among the women who had or did not have osteoporosis. However, hypertensive women who used thiazides or beta blockers had higher values of total lumbar BMD compared with the women who did not.

CONCLUSION

Hypertension in postmenopausal Syrian women aged over 40 was not found to be associated with osteoporosis. However, the mean total lumbar BMD of the hypertensive women who took thiazide diuretics or beta blocker was found to be increased significantly comparing to the women who did not take either.

The Central Regulation of Bone Mass: Genetic Evidence and Molecular Bases

The alternation of resorption of preexisting bone by the osteoclasts followed by de novo bone formation by osteoblasts is called bone modeling during childhood and bone remodeling during adulthood. A central question raised by this physiological process that is fundamental to longitudinal growth during childhood and adolescence and that is attacked at the other end of life in the context of osteoporosis is to know how it is regulated. This question was rejuvenated in the late 1990s and early 2000s years when the application of mouse genetics made it feasible to test whether there were new endocrine determinants of bone (re)modeling. Addressing this question, taking into account fundamental cell biology features of bone led to the hypothesis that there should be a coordinated control of bone growth/mass, energy metabolism, and reproduction. Testing genetically and molecularly, this hypothesis revealed that, in vivo, the adipocyte-derived hormone leptin is a powerful inhibitor of bone mass accrual following its signaling in the brain. This chapter details the molecular bases and biological relevance of this regulation of bone mass accrual by leptin.

Modified SCORE tool for prediction of bone mineral density in Egyptian elderly women. Comparison of seven osteoporosis screening tools

We aimed to compare the performance of seven risk screening tools for detecting elderly Egyptian women with osteoporosis and to modify the tool with the best performance to increase the efficiency of referral for bone mineral density (BMD) testing. There are few studies about the epidemiology of osteoporosis in Egypt, in addition, there was no study done before to evaluate the performance of these seven screening tools in a large sample size. This aims to help clinicians restrict the use of DXA scan for those patients defined as "high risk" for osteoporosis which can substantially reduce the cost for the community and the patients, especially in developing countries. We conducted a cross-sectional study on 681 elderly women for measurement of BMD using DXA scans. The performance of the Simple Calculated Osteoporosis Risk Estimation (SCORE) was superior to other indices with the highest sensitivity and specificity. The newly modified SCORE tool at cutoff point ≥1 is a simple easy tool and shows good sensitivity (up to 94%) and acceptable specificity (up to 46.7%) in detecting osteoporosis in elderly women with fewer items and easier calculation.

Effect of Dipeptidyl Peptidase-4 Inhibitors on the Risk of Bone Fractures in a Korean Population

BACKGROUND

There have been equivocal results in studies of the effects of dipeptidyl peptidase-4 inhibitors (DPP-4i) on fractures. In this study, we analyzed the effect of DPP-4i on bone fracture risk in a Korean population.

METHODS

We extracted subjects (n = 11,164) aged 50 years or older from the National Health Insurance Service-National Sample Cohort 2.0 from 2009 to 2014. Our control group included subjects without diabetes (n = 5,582), and our treatment groups with diabetes included DPP-4i users (n = 1,410) and DPP-4i non-users (n = 4,172). The primary endpoint was the incidence of a composite outcome consisting of osteoporosis diagnosis, osteoporotic fractures, vertebral fractures, non-vertebral fractures, and femoral fractures. The secondary endpoint was the incidence of each individual component of the composite outcome. Survival analysis was performed with adjustment for age, gender, diabetes complications severity index, Charlson comorbidity index, hypertension medication, and dyslipidemia treatment.

RESULTS

The incidence of the composite outcome per 1,000 person-years was 0.089 in DPP-4i users, 0.099 in DPP-4i non-users, and 0.095 in controls. There was no significant difference in fracture risk between DPP-4i users and DPP-4i non-users or controls after the adjustments (P > 0.05). The incidences of osteoporosis diagnosis, osteoporotic fractures, vertebral fractures, non-vertebral fractures, and femoral fractures were not significantly different between DPP-4i users and non-users. The results of subgroup analyses by gender and age were consistent.

CONCLUSION

DPP-4i had no significant effect on the risk of fractures in a Korean population.

The effects of intraperitoneal metoprolol administration on healing of bone defects in rat tibia: a pilot study

OBJECTIVES

Metoprolol is a cardioselective competitive beta-1 adrenergic receptor antagonist with antihypertensive properties, devoid of intrinsic sympathomimetic activity. Various studies have suggested the effect of beta-blockers on bone remodeling. We aimed to investigate whether metoprolol affects bone remodeling by altering anti-inflammatory and pro-inflammatory cytokines.

MATERIALS AND METHODS

Surgical defects of 3 mm diameter were created in tibiae of 72 Sprague-Dawley rats. Rats were randomly assigned to a control group without metoprolol treatment (n = 36), and a test group treated with 0.1 mg/kg/day metoprolol (n = 36). Six rats from each group were sacrificed at days 0, 1, 3, 5, 7, and 14. The percentages of cells, which showed positive immunohistochemical staining for IL-1β, IL-6, IL-10, and RANKL, were assessed in the defect area. Differences in percentages of stained cells within each of the test and control groups over various time intervals were tested using one-way ANOVA test. A P value of < 0.05 was considered statistically significant.

RESULTS

No significant differences in IL-1β, IL-10, IL-6, and RANKL expressions were found between test and control groups at the same interval. Significant reduction was observed at different time intervals in the same group (P < 0.05).

CONCLUSION

Metoprolol did not reduce bone-active cytokine: IL-1β, IL-6, and RANKL. It also did not elevate IL-10 expression levels. Thus, it does not appear to decrease osteoclastogenesis.

CLINICAL RELEVANCE

Results from this animal model help us understand any effect of metoprolol on bone healing by potential contribution to different real-world clinical research.

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.

Atherosclerosis and Osteoporosis. Common Targets for the Effects of Cardiovascular and Anti-osteoporotic Drugs (Part I). The Effect of Cardiovascular Drugs on Bone Strength

Daily use of antihypertensive and lipid-lowering drugs in clinical practice dictates the need for knowledge of their pleiotropic effects. The article presents the results of studies of the effect of cardiovascular drugs, such as statins, beta-blockers, ACE inhibitors, diuretics, calcium antagonists and nitrates on bone mineral density and fractures associated with osteoporosis. The mechanisms of action of drugs on bone mass, markers of bone metabolism, the frequency of fractures in osteoporosis are discussed. Most studies show that the use of cardiac drugs along with a positive effect on the vascular wall, slow bone resorption and increase bone mass. Knowledge of the additional effect on bone metabolism of drugs used in cardiovascular diseases allows to choose an adequate therapy and improve the prognosis of both diseases.

Impacts of Psychological Stress on Osteoporosis: Clinical Implications and Treatment Interactions

The significant biochemical and physiological effects of psychological stress are beginning to be recognized as exacerbating common diseases, including osteoporosis. This review discusses the current evidence for psychological stress-associated mental health disorders as risk factors for osteoporosis, the mechanisms that may link these conditions, and potential implications for treatment. Traditional, alternative, and adjunctive therapies are discussed. This review is not intended to provide therapeutic recommendations, but, rather, the goal of this review is to delineate potential interactions of psychological stress and osteoporosis and to highlight potential multi-system implications of pharmacological interventions. Review of the current literature identifies several potentially overlapping mechanistic pathways that may be of interest (e.g., glucocorticoid signaling, insulin-like growth factor signaling, serotonin signaling) for further basic and clinical research. Current literature also supports the potential for cross-effects of therapeutics for osteoporosis and mental health disorders. While studies examining a direct link between osteoporosis and chronic psychological stress are limited, the studies reviewed herein suggest that a multi-factorial, personalized approach should be considered for improved patient outcomes in populations experiencing psychological stress, particularly those at high-risk for development of osteoporosis.

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.

Higher sympathetic activity as a risk factor for skeletal deterioration in pheochromocytoma

Despite the potential biological importance of sympathetic activity in human bone metabolism, its effects on bone microarchitecture, a key determinant of bone quality, has not been thoroughly studied. In the present study, we investigated the lumbar spine trabecular bone score (TBS) as an indicator of skeletal deterioration in pheochromocytoma. Among 620 consecutive patients with newly diagnosed adrenal incidentaloma, 29 with histologically confirmed pheochromocytoma (a catecholamine-secreting neuroendocrine tumor) and 266 with nonfunctional adrenal incidentaloma were defined as cases and controls, respectively. After adjustment for confounders, subjects with pheochromocytoma had 2.9% lower lumbar spine TBS than those without pheochromocytoma (P = 0.038). Moreover, urinary normetanephrine level, but not urinary metanephrine level, was inversely correlated with lumbar spine TBS (P = 0.009). Subjects in the highest urinary normetanephrine quartile showed markedly lower lumbar spine TBS than those in the lowest quartile (P = 0.018), in a dose-response manner across increasing urinary normetanephrine quartile categories (P for trend = 0.021). Consistent with the results of previous studies, subjects with pheochromocytoma had significantly lower bone mass at the lumbar spine and higher serum level of C-terminal telopeptide of type I collagen than controls (P = 0.013 and 0.002, respectively). These findings provide clinical evidence that catecholamine excess and the resultant sympathetic overstimulation in pheochromocytoma may contribute to bone fragility, especially in the trabecular bone, through a weak microarchitecture in addition to a lower bone mass and increased bone resorption, and support the possibility of pheochromocytoma as a secondary cause of osteoporosis.

Low temperature decreases bone mass in mice: Implications for humans

OBJECTIVES

Humans exhibit significant ecogeographic variation in bone size and shape. However, it is unclear how significantly environmental temperature influences cortical and trabecular bone, making it difficult to recognize adaptation versus acclimatization in past populations. There is some evidence that cold-induced bone loss results from sympathetic nervous system activation and can be reduced by nonshivering thermogenesis (NST) via uncoupling protein (UCP1) in brown adipose tissue (BAT). Here we test two hypotheses: (1) low temperature induces impaired cortical and trabecular bone acquisition and (2) UCP1, a marker of NST in BAT, increases in proportion to degree of low-temperature exposure.

METHODS

We housed wildtype C57BL/6J male mice in pairs at 26 °C (thermoneutrality), 22 °C (standard), and 20 °C (cool) from 3 weeks to 6 or 12 weeks of age with access to food and water ad libitum (N = 8/group).

RESULTS

Cool housed mice ate more but had lower body fat at 20 °C versus 26 °C. Mice at 20 °C had markedly lower distal femur trabecular bone volume fraction, thickness, and connectivity density and lower midshaft femur cortical bone area fraction versus mice at 26 °C (p < .05 for all). UCP1 expression in BAT was inversely related to temperature.

DISCUSSION

These results support the hypothesis that low temperature was detrimental to bone mass acquisition. Nonshivering thermogenesis in brown adipose tissue increased in proportion to low-temperature exposure but was insufficient to prevent bone loss. These data show that chronic exposure to low temperature impairs bone architecture, suggesting climate may contribute to phenotypic variation in humans and other hominins.

The Time Point-Specific Effect of Beta-Adrenergic Blockade in Attenuating High Fat Diet-Induced Obesity and Bone Loss

We aimed to clarify the key factor determining the effect of beta blocker attenuating high fat diet- induced obesity and bone loss. Six-week-old C57BL/6 male mice were assigned to groups reflecting different relative onset of obesity and beta blocker administration, different diet (control vs. high fat), and treatment (vehicle vs. beta blocker: propranolol). Mice in Group 1 were fed a control diet (CON) or high fat diet (HIGH) with vehicle or propranolol for 12 weeks. Mice in Group 2 were fed a CON or HIGH without pharmaceutical treatment for the first 12 weeks, followed by another 12 weeks of treatment with vehicle or propranolol. Mice in Group 3 were fed a CON without pharmaceutical treatment for the first 12 weeks, followed by stratification into diet-based subgroups and another 12 weeks of treatment with vehicle or propranolol. Propranolol attenuated the HIGH-induced increase in body weight/fat mass in Group 1 mice and in Group 3 mice, but not in Group 2 mice. Propranolol mitigated HIGH-induced reduction in femoral trabecular bone mineral density and bone architecture deterioration in Group 1 mice but not in Group 2 mice. HIGH feeding in Group 3 did not compromise skeletal integrity. Taken together, propranolol attenuates HIGH-induced body weight increases while weight gain is in progress but not once obesity has already been established. HIGH feeding during the growth period results in compromised bone mass/architecture; which can be attenuated by propranolol administration during the growth period, but not by propranolol administration after obesity has already been established.

Immune System Dysregulation During Spaceflight: Potential Countermeasures for Deep Space Exploration Missions

Recent studies have established that dysregulation of the human immune system and the reactivation of latent herpesviruses persists for the duration of a 6-month orbital spaceflight. It appears certain aspects of adaptive immunity are dysregulated during flight, yet some aspects of innate immunity are heightened. Interaction between adaptive and innate immunity also seems to be altered. Some crews experience persistent hypersensitivity reactions during flight. This phenomenon may, in synergy with extended duration and galactic radiation exposure, increase specific crew clinical risks during deep space exploration missions. The clinical challenge is based upon both the frequency of these phenomena in multiple crewmembers during low earth orbit missions and the inability to predict which specific individual crewmembers will experience these changes. Thus, a general countermeasure approach that offers the broadest possible coverage is needed. The vehicles, architecture, and mission profiles to enable such voyages are now under development. These include deployment and use of a cis-Lunar station (mid 2020s) with possible Moon surface operations, to be followed by multiple Mars flyby missions, and eventual human Mars surface exploration. Current ISS studies will continue to characterize physiological dysregulation associated with prolonged orbital spaceflight. However, sufficient information exists to begin consideration of both the need for, and nature of, specific immune countermeasures to ensure astronaut health. This article will review relevant in-place operational countermeasures onboard ISS and discuss a myriad of potential immune countermeasures for exploration missions. Discussion points include nutritional supplementation and functional foods, exercise and immunity, pharmacological options, the relationship between bone and immune countermeasures, and vaccination to mitigate herpes (and possibly other) virus risks. As the immune system has sentinel connectivity within every other physiological system, translational effects must be considered for all potential immune countermeasures. Finally, we shall discuss immune countermeasures in the context of their individualized implementation or precision medicine, based on crewmember specific immunological biases.

Heart Rate and Bone Mineral Density in Older Women with Hypertension: Results from the Korea National Health and Nutritional Examination Survey

OBJECTIVES

To determine whether high heart rate is associated with low bone mineral density (BMD) in older women with hypertension.

DESIGN

Retrospective cohort study.

SETTING

Population-based study conducted in Korea (Korea National Health and Nutritional Examination Survey 2009-10).

PARTICIPANTS

Postmenopausal women aged 60 and older with hypertension (N=981) divided into 2 groups according to resting heart rate, with a cut-off value of 80 bpm, which has been found to be associated with osteoporosis.

MEASUREMENTS

BMD profiles and clinical and laboratory data were collected. Osteoporosis was defined as a T-score of -2.5 or less, according to World Health Organization criteria.

RESULTS

BMD was significantly lower in participants with a high heart rate, even after adjustment for age, diabetes mellitus, white blood cell count, and fasting glucose and triglyceride levels. The prevalence of osteoporosis was also significantly higher in those participants. In multivariate logistic regression analysis, the group with high heart rate was 1.7 times as likely (95% confidence interval=1.2-2.3) to have osteoporosis as those with a lower heart rate, independent of age, body mass index, comorbidities, and laboratory findings.

CONCLUSION

High heart rate is independently associated with lower BMD in older women with hypertension; proactive surveillance of BMD could be helpful when managing older women with hypertension and a high heart rate.

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.

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.

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.

Liposomal Encapsulation for Systemic Delivery of Propranolol via Transdermal Iontophoresis Improves Bone Microarchitecture in Ovariectomized Rats

The stimulatory effects of liposomal propranolol (PRP) on proliferation and differentiation of human osteoblastic cells suggested that the prepared liposomes-encapsulated PRP exerts anabolic effects on bone in vivo. Iontophoresis provides merits such as sustained release of drugs and circumvention of first pass metabolism. This study further investigated and evaluated the anti-osteoporotic effects of liposomal PRP in ovariectomized (OVX) rats via iontophoresis. Rats subjected to OVX were administered with pure or liposomal PRP via iontophoresis or subcutaneous injection twice a week for 12 weeks. Changes in the microarchitecture at the proximal tibia and the fourth lumbar spine were assessed between pure or liposomal PRP treated and non-treated groups using micro-computed tomography. Administration of liposomal PRP at low dose (0.05 mg/kg) via iontophoresis over 2-fold elevated ratio between bone volume and total tissue volume (BV/TV) in proximal tibia to 9.0% whereas treatment with liposomal PRP at low and high (0.5 mg/kg) doses via subcutaneous injection resulted in smaller increases in BV/TV. Significant improvement of BV/TV and bone mineral density (BMD) was also found in the fourth lumbar spine when low-dose liposomal PRP was iontophoretically administered. Iontophoretic low-dose liposomal PRP also elevated trabecular numbers in tibia and trabecular thickness in spine. Enhancement of bone microarchitecture volumes has highlighted that liposomal formulation with transdermal iontophoresis is promising for PRP treatment at the lower dose and with longer duration than its clinical therapeutic range and duration to exhibit optimal effects against bone loss in vivo.

Bone pain mechanism in osteoporosis: a narrative review

Bone pain in elderly people dramatically affects their quality of life, with osteoporosis being the leading cause of skeletal related events. Peripheral and central mechanisms are involved in the pathogenesis of the nervous system sensitization. Osteoporosis in the elderly has been associated with increased density of bone sensory nerve fibers and their pathological modifications, together with an over-expression of nociceptors sensitized by the lowering pH due to the osteoclastic activity. The activation of N-methyl-D-aspartate (NMDA) receptors and the microglia, as a response to a range of pathological conditions, represent the leading cause of central sensitization. Unfortunately, osteoporosis is named the "silent thief" because it manifests with painful manifestation only when a fracture occurs. In the management of patients suffering from bone pain, both the nociceptive and the neuropathic component of chronic pain should be considered in the selection of the analgesic treatment.

Effects of fenoterol on the skeletal system depend on the androgen level

BACKGROUND

The role of sympathetic nervous system in the osseous tissue remodeling is not clear enough.

METHODS

The effects of fenoterol, a selective β₂-adrenomimetic drug, on the skeletal system of normal and androgen deficient (orchidectomized) rats were studied in vivo. Osteoclastogenesis and mRNA expression in osteoblasts were investigated in vitro in mouse cell cultures.

RESULTS

Fenoterol administered to animals with physiological androgen level unfavorably affected the skeletal system, damaging the bone microarchitecture. Androgen deficiency induced osteoporotic changes, and fenoterol protected the osseous tissue from consequences of androgen deficiency. The results of in vitro studies correlated with the in vivo observations. A significantly increased number of osteoclasts in bone marrow cell cultures to which testosterone and fenoterol were added simultaneously was demonstrated. In cultures without the addition of testosterone, fenoterol significantly inhibited osteoclastogenesis in comparison with control cultures.

CONCLUSIONS

The results indicate the favorable action of fenoterol in conditions of testosterone deficiency, and its destructive influence upon the skeleton in the presence of androgens. The results confirm the key role of sympathetic nervous system in the regulation of bone remodeling.

Effects of leptin on femoral fracture in rats

In this study, our objective was to evaluate effects of leptin on fracture healing in rats. Seventy two male Sprague-Dawley (SD) rats were randomized into 3 groups. Standardized femoral fractures were created in all the rats. Group A was treated with 1 mL normal saline (NS), group B with 0.3 μg/kg leptin in 1 mL NS, and group C with 0.5 μg/kg leptin in 1 mL NS for 2 weeks intraperitoneally. Each group was divided into three subgroups including 8 rats for evaluation at 2, 4 and 8 weeks. Radiological evaluation showed that callus formation of group B and C was all significantly higher than group A at 8 weeks (P=0.04 and P=0.013, respectively). There was no statistically significant difference in fracture healing between group B and group C at 8 weeks (P=0.197). Histological evaluation revealed fracture healing of group B and C was better than group A at 4 weeks (P=0.01 and P=0.002, respectively) and 8 weeks (P=0.008 and P=0.003, respectively). Micro-computed tomography (Micro-CT) analysis demonstrated that greater amounts of bony callus and evidence of bone fusion were observed in group B and C at 4 weeks (P=0.02 and P=0.04, respectively) and 8 weeks (P=0.005 and P=0.001, respectively) compared to group A. Group C also had better fracture healing than group B at 8 weeks (P=0.01). In conclusion, leptin has a positive effect on rat femoral fracture healing.

Bone mineral density changes among women initiating blood pressure lowering drugs: a SWAN cohort study

SUMMARY

We examined the effect of blood pressure lowering drugs on BMD using data from the Study of Women's Health Across the Nation. Thiazide users had a slower decline in BMD compared to nonusers, while decline among ACE inhibitor and beta blocker users were similar to rates in nonusers.

INTRODUCTION

Several blood pressure lowering drugs may affect bone mineral density (BMD), leading to altered fracture risk. We examined the effect of blood pressure lowering drugs on BMD using data from the Study of Women's Health Across the Nation.

METHODS

We conducted a propensity score matched cohort study. Women were initiators of ACE inhibitors (ACEi), beta-blockers (BB), or thiazide diuretics (THZD). Their annualized BMD changes during the 14 years of observation were compared with nonusers.

RESULTS

Among the 2312 eligible women, we found 69 ACEi, 71 BB, and 74 THZD users who were matched by a propensity score with the same number of nonusers. THZD users had a slower annual percent decline in BMD compared to nonusers at the femoral neck (FN) (-0.28% vs -0.88%; p = 0.008) and the spine (-0.74% vs -1.0%; p = 0.34), albeit not statistically significant. Annual percent changes in BMD among ACEi and BB users were similar to rates in nonusers. In comparison with BB, THZD use was associated with a trend toward less annualized BMD loss at the spine (-0.35% vs -0.60%; p = 0.08) and a similar trend at the FN (-0.39% vs -0.64%; p = 0.08); in comparisons with ACEi, THZD was also associated with less loss at the FN (-0.48% vs -0.82%; p = 0.02), but not at the spine (-0.40% vs -0.56%; p = 0.23).

CONCLUSIONS

Neither ACEi nor BB was associated with improvements in BMD. THZD use was associated with less annualized loss of BMD compared with nonusers, as well as compared with ACEi and BB.

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.

Serum leptin, bone mineral density and the healing of long bone fractures in men with spinal cord injury

Previously reported fracture rates in patients with spinal cord injury range from 1% to 20%. However, the exact role of spinal cord injury in bone metabolism has not yet been clarified. In order to investigate the effects of serum leptin and bone mineral density on the healing of long bone fractures in men with spinal cord injury, 15 male SCI patients and 15 matched controls were involved in our study. The outcome indicated that at 4 and 8 weeks after bone fracture, callus production in patients with spinal cord injury was lower than that in controls. Besides, bone mineral density was significantly reduced at 2, 4 and 8 weeks. In addition, it was found that at each time point, patients with spinal cord injury had significantly higher serum leptin levels than controls and no association was found between serum leptin level and bone mineral density of lumbar vertebrae. Moreover, bone mineral density was positively correlated with bone formation in both of the groups. These findings suggest that in early phases i.e. week 4 and 8, fracture healing was impaired in patients with spinal cord injury and that various factors participated in the complicated healing process, such as hormonal and mechanical factors.

Lipid metabolism disorders and bone dysfunction--interrelated and mutually regulated (review)

The association between lipid and bone metabolism has become an increasing focus of interest in recent years, and accumulating evidence has shown that atherosclerosis (AS) and osteoporosis (OP), a disorder of bone metabolism, frequently co-exist. Fat and bone are known to share a common progenitor cell: Multipotent mesenchymal stem cells (MSC) in the bone marrow (BM), which are able to differentiate into various cell phenotypes, including osteoblasts, adipocytes and chondrocytes. Laboratory-based and clinical trials have shown that increasing adipocytes are accompanied by a decrease in bone mineral density (BMD) and bone mass. Statins, lipid-lowering drugs used to treat hyperlipidemia, also provide benefit in the treatment of OP. There is thus evidence that the metabolism of lipids is correlated with that of bone, and that the two are mutually regulated. The present review primarily focuses on the potential association between lipid metabolism disturbance and OP, based on biological metabolism, pathophysiological processes, results from clinical and experimental animal studies, processes involved in the differentiation of adipocytes and osteoblasts, as well as pharmacological treatments of these diseases.

Endocrinology of bone/brain crosstalk

Bone metabolism is regulated by the action of two skeletal cells: osteoblasts and osteoclasts. This process is controlled by many genetic, hormonal and lifestyle factors, but today more and more studies have allowed us to identify a neuronal regulation system termed 'bone-brain crosstalk', which highlights a direct relationship between bone tissue and the nervous system. The first documentation of an anatomic relationship between nerves and bone was made via a wood cut by Charles Estienne in Paris in 1545. His diagram demonstrated nerves entering and leaving the bones of a skeleton. Later, several studies were conducted on bone innervation and, as of today, many observations on the regulation of bone remodeling by neurons and neuropeptides that reside in the CNS have created a new research field, that is, neuroskeletal research.