Histomorphometric analysis of glucocorticoid-induced osteoporosis

Bone Microarchitecture and Volumetric Mineral Density Assessed by HR-pQCT in Patients with 21- and 17α-Hydroxylase Deficiency

Due to disturbances in hormones and long-term glucocorticoid replacement therapy (GRT), congenital adrenocortical hyperplasia (CAH) patients are at risk of impaired bone structure and metabolism. This cross-sectional, case-control study aims to investigate for the first time bone microarchitecture features in 21-hydroxylase deficiency (21OHD; N = 38) and 17α-hydroxylase deficiency (17OHD; N = 16) patients using high-resolution peripheral quantitative computed tomography (HR-pQCT) by matching the same sex and similar age [21OHD vs. control: 29.5 (24.0-34.3) vs. 29.6 (25.9-35.2) years; 17OHD vs. controls: 29.0 (21.5-35.0) vs. 29.7 (24.6-35.3) years] with healthy controls (1:3). All patients underwent HR-pQCT scans of the nondominant radius and tibia, and had received GRT. Compared with corresponding controls, 17OHD cases had higher height (P < 0.001), weight (P = 0.013) and similar body mass index (BMI), while 21OHD had lower height (P < 0.001), similar weight and higher BMI (P < 0.001). 17OHD and 21OHD patients demonstrated various significant bone differences in most HR-pQCT indices, suggesting abnormalities in bone microarchitectures from healthy people. Further correlation analyses revealed that some characteristics, such as height and hormones, may contribute to the bone differences in HR-pQCT indices between two diseases. However, treatment dosage and time were not correlated, indicating that the current glucocorticoid doses may be within safety limits for bone impairment. Overall, our study for the first time revealed changes of bone microarchitecture in CAH patients and their potential relations with clinical characteristics. Further longitudinal researches are required to confirm these findings.

Altered type I collagen networking in osteoporotic human femoral head revealed by histomorphometric and Fourier transform infrared imaging correlated analyses

Bone homeostasis is the equilibrium between organic and inorganic components of the extracellular matrix (ECM) and cells. Alteration of this balance has consequences on bone mass and architecture, resulting in conditions such as osteoporosis (OP). Given ECM protein mutual regulation and their effects on bone structure and mineralization, further insight into their expression is crucial to understanding bone biology under normal and pathological conditions. This study focused on Type I Collagen, which is mainly responsible for structural properties and mineralization of bone, and selected proteins implicated in matrix composition, mineral deposition, and cell-matrix interaction such as Decorin, Osteocalcin, Osteopontin, Bone Sialoprotein 2, Osteonectin and Transforming Growth Factor beta. We developed a novel multidisciplinary approach in order to assess bone matrix in healthy and OP conditions more comprehensively by exploiting the Fourier Transform Infrared Imaging (FTIRI) technique combined with histomorphometry, Sirius Red staining, immunohistochemistry, and Western Blotting. This innovatory procedure allowed for the analysis of superimposed tissue sections and revealed that the alterations in OP bone tissue architecture were associated with warped Type I Collagen structure and deposition but not with changes in the total protein amount. The detected changes in the expression and/or cooperative or antagonist role of Decorin, Osteocalcin, Osteopontin, and Bone Sialoprotein-2 indicate the deep impact of these NCPs on collagen features of OP bone. Overall, our strategy may represent a starting point for designing targeted clinical strategies aimed at bone mass preservation and sustain the FTIRI translational capability as upcoming support for traditional diagnostic methods.

Bone Health in Children with Rheumatic Disorders: Focus on Molecular Mechanisms, Diagnosis, and Management

Bone is an extremely dynamic and adaptive tissue, whose metabolism and homeostasis is influenced by many different hormonal, mechanical, nutritional, immunological and pharmacological stimuli. Genetic factors significantly affect bone health, through their influence on bone cells function, cartilage quality, calcium and vitamin D homeostasis, sex hormone metabolism and pubertal timing. In addition, optimal nutrition and physical activity contribute to bone mass acquisition in the growing age. All these factors influence the attainment of peak bone mass, a critical determinant of bone health and fracture risk in adulthood. Secondary osteoporosis is an important issue of clinical care in children with acute and chronic diseases. Systemic autoimmune disorders, like juvenile idiopathic arthritis, can affect the skeletal system, causing reduced bone mineral density and high risk of fragility fractures during childhood. In these patients, multiple factors contribute to reduce bone strength, including systemic inflammation with elevated cytokines, reduced physical activity, malabsorption and nutritional deficiency, inadequate daily calcium and vitamin D intake, use of glucocorticoids, poor growth and pubertal delay. In juvenile arthritis, osteoporosis is more prominent at the femoral neck and radius compared to the lumbar spine. Nevertheless, vertebral fractures are an important, often asymptomatic manifestation, especially in glucocorticoid-treated patients. A standardized diagnostic approach to the musculoskeletal system, including prophylaxis, therapy and follow up, is therefore mandatory in at risk children. Here we discuss the molecular mechanisms involved in skeletal homeostasis and the influence of inflammation and chronic disease on bone metabolism.

The use of oral glucocorticoids and the risk of major osteoporotic fracture in patients with myasthenia gravis

Oral glucocorticoids may increase major osteoporotic fracture risk (MOF) in myasthenia gravis patients. To assess this risk, we performed a case-control study including all Danish patients with a MOF between 1995 and 2011. We also pooled our data with data from another study. We found no increased risk. Osteoporosis prevention remains advisable.

PURPOSE/INTRODUCTION

The prolonged use of high doses of oral glucocorticoids (GCs), a common treatment in patients with myasthenia gravis (MG), may increase major osteoporotic fracture (MOF) risk. Previous epidemiological studies did not exclusively focus on patients with MG or had relatively few GC-exposed MG patients. Aims were to evaluate the risk of MOF in MG patients using oral GCs in a large study population and to perform a pooled analysis with data from previous work.

METHODS

A population-based case-control study (1995-2011) was conducted using the Danish National Health Service. Cases had sustained a MOF, and controls had not. All were aged ≥ 18 years. Multivariate conditional logistic regression estimated odds ratios (ORs) among MG patients using oral GCs versus non-users. Adjustments were made for comorbidities and comedications. In the pooled analysis, results were pooled by the use of generic inverse variance methods, assuming a random-effects model.

RESULTS

We identified 376,858 cases and 376,858 controls. MOF risk was not elevated in MG patients currently using oral GCs compared to MG patients not on oral GCs (OR_adj.: 1.26 (95% CI 0.68-2.33)). The use of the highest cumulative dose of oral GCs (≥ 7 g) did not show an increased risk of MOF among MG patients (OR_adj.: 2.00 (95% CI 0.90-4.44)). Our pooled analysis also showed no association between oral GC use and MOF risk.

CONCLUSION

This study showed that oral GC use in patients with MG was not associated with increased risk of MOF in our case-control study and pooled analysis. Osteoporosis prevention in MG patients based on clinical guidelines remains advisable.

The Role of Piper sarmentosum Aqueous Extract as a Bone Protective Agent, a Histomorphometric Study

Glucocorticoids are one of the causes of secondary osteoporosis. The aqueous extract of Piper sarmentosum contains flavonoids that possess antioxidant effects. In this study, we determined the effects of aqueous Piper sarmentosum leaf extract on structural, dynamic and static histomorphometric changes from osteoporotic bones of rats induced with glucocorticoids. Thirty-two Sprague-Dawley rats were divided equally into four groups—Sham control group given vehicles (intramuscular (IM) olive oil and oral normal saline); AC: Adrenalectomised (Adrx) control group given IM dexamethasone (DEX) (120 μg/kg/day) and vehicle (oral normal saline); AP: Adrx group administered IM DEX (120 μg/kg/day) and aqueous Piper sarmentosum leaf extract (125 mg/kg/day) orally; and AG: Adrx group administered IM DEX (120 μg/kg/day) and oral glycyrrhizic acid (GCA) (120 mg/kg/day). Histomorphometric measurements showed that the bone volume, trabecular thickness, trabecular number, osteoid and osteoblast surfaces, double-labelled trabecular surface, mineralizing surface and bone formation rate of rats given aqueous Piper sarmentosum leaf extract were significantly increased (p < 0.05), whereas the trabecular separation and osteoclast surface were significantly reduced (p < 0.05). This study suggests that aqueous Piper sarmentosum leaf extract was able to prevent bone loss in prolonged glucocorticoid therapy. Thus, Piper sarmentosum has the potential to be used as an alternative medicine against osteoporosis and osteoporotic fractures in patients undergoing long-term glucocorticoid therapy.

Bone mineral density and vitamin D status in children with remission phase of steroid-sensitive nephrotic syndrome

Children with idiopathic nephrotic syndrome are primarily treated with glucocorticoids (GCs), but long-term GC use can lead to undesired side effects. We investigated the bone mineral density (BMD) and 25-hydroxyvitamin D (25-OH D) levels in children with the remission phase of steroid-sensitive nephrotic syndrome (SSNS). This study included 32 patients with SSNS who had not received GC treatment in the last 6 months and a control group of 20 healthy children. Serum levels of calcium, phosphate, alkaline phosphatase, 25-(OH)D, and parathyroid hormone (PTH) were measured. BMD was determined in the lumbar spinal region using dual-energy X-ray absorptiometry (DEXA). Serum 25-(OH)D levels were lower in the SSNS patients than in the healthy children (P <0.05), with 22 patients (68.8%) having Z-scores <-1. The Z-scores were positively correlated with 25-(OH)D levels (r = 0.424, P <0.05). PTH levels were higher in patients with osteoporosis than in patients with Z-scores ≥-1 (P <0.05). Bone mineral content and BMD were positively correlated with the age of diagnosis (P <0.01). Receiver-operating characteristic curve analysis showed that the cutoff value of 25-(OH)D levels for predicting low BMD was 14.67 ng/mL with a sensitivity of 90% and a specificity of 64%. The area under the curve (AUC ± standard error) was 0.868 ± 0.064 (95% confidence interval: 0.742-0.994, P = 0.001). Decreased 25-(OH)D levels and the negative effects of long-term GC treatment on BMD persist in SSNS remission phase. Levels of 25-(OH)D <14.67 ng/mL could predict abnormal DEXA scans in children with SSNS remission phase.

Trabecular Bone Score Is More Sensitive to Asthma Severity and Glucocorticoid Treatment Than Bone Mineral Density in Asthmatics

PURPOSE

In asthmatic patients, treatment with corticosteroids, in addition to conventional risk factors for osteoporosis, may lead to bone loss. Trabecular bone score (TBS) is an indirect new parameter of bone quality. This study aimed to evaluate TBS in asthmatics in comparison to propensity score-matched controls and to investigate correlations between TBS and cumulative systemic and inhaled corticosteroid doses 1 year prior to bone mineral density (BMD) measurement in patients with asthma.

METHODS

In total, 627 patients with asthma and the same number of non-asthmatic controls matched for sex and age were included in this retrospective cohort study. TBS was calculated in the lumbar region, based on 2 dimensional projections of dual-energy X-ray absorptiometry.

RESULTS

Patients with severe asthma exhibited lower vertebral TBS values (1.32 ± 0.1) than those with non-severe asthma (1.36 ± 0.1, P = 0.001), with non-active asthma (1.38 ± 0.1, P < 0.001), and without asthma (1.39 ± 0.1, P < 0.001). No significant differences in BMD were noted among the study groups. TBS was significantly correlated with cumulative systemic and inhaled corticosteroid doses as well as asthma duration, lung function and airway hyper-responsiveness. A generalized linear model revealed that age, severe asthma, and frequency of oral corticosteroid burst were significant predictors for TBS levels.

CONCLUSIONS

TBS can be used as an early indicator of altered bone quality stemming from glucocorticoid therapy or, possibly, more severe asthma.

3T chemical shift-encoded MRI: Detection of altered proximal femur marrow adipose tissue composition in glucocorticoid users and validation with magnetic resonance spectroscopy

BACKGROUND

Osteoporosis (OP) results in weak bone and can ultimately lead to fracture. Drugs such as glucocorticoids can also induce OP (glucocorticoid-induced osteoporosis [GIO]). Bone marrow adipose tissue composition and quantity may play a role in OP pathophysiology, but has not been thoroughly studied in GIO compared to primary OP.

PURPOSE/HYPOTHESIS

Chemical shift-encoded (CSE) MRI allows detection of subregional differences in bone marrow adipose tissue composition and quantity in the proximal femur of GIO compared to OP subjects and has high agreement with the reference standard of magnetic resonance spectroscopy (MRS).

STUDY TYPE

Prospective.

SUBJECTS

In all, 18 OP and 13 GIO subjects.

FIELDS STRENGTH

3T.

SEQUENCE

Multiple gradient-echo, stimulated echo acquisition mode (STEAM).

ASSESSMENT

Subjects underwent CSE-MRI in the proximal femurs, and for each parametric map regions of interest (ROIs) were assessed in the femoral head (fHEAD), femoral neck (fNECK), Ward's triangle (fTRIANGLE), and the greater trochanter (GTROCH). In addition, we compared CSE-MRI against the reference standard of MRS performed in the femoral neck and Ward's triangle.

STATISTICAL TESTS

Differences between OP/GIO were investigated using the Mann-Whitney nonparametric test. Bland-Altman methodology was used to assess measurement agreement between CSE-MRI and MRS.

RESULTS

GIO compared with OP subjects demonstrated: decreased monounsaturated fat fraction (MUFA) (-2.1%, P < 0.05) in fHEAD; decreased MUFA (-3.8%, P < 0.05), increased saturated fat fraction (SFA) (5.5%, P < 0.05), and decreased T 2 * (-3.8 msec, P < 0.05) in fNECK; decreased proton density fat fraction (PDFF) (-15.1%, P < 0.05), MUFA (-9.8%, P < 0.05), polyunsaturated fat fraction (PUFA) (-1.8%, P < 0.01), increased SFA (11.6%, P < 0.05), and decreased T 2 * (-5.4 msec, P < 0.05) in fTRIANGLE; and decreased T 2 * (-1.5 msec, P < 0.05) in GTROCH. There was high measurement agreement between MRI and MRS using the Bland-Altman test.

DATA CONCLUSION

3T CSE-MRI may allow reliable assessment of subregional bone marrow adipose tissue (bMAT) quantity and composition in the proximal femur in a clinically reasonable scan time. Glucocorticoids may alter the lipid profile of bMAT and potentially result in reduced bone quality.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:490-496.

The CRH-Transgenic Cushingoid Mouse Is a Model of Glucocorticoid-Induced Osteoporosis

Glucocorticoids (GCs) have unparalleled anti‐inflammatory and immunosuppressive properties, which accounts for their widespread prescription and use. Unfortunately, a limitation to GC therapy is a wide range of negative side effects including Cushing's syndrome, a disease characterized by metabolic abnormalities including muscle wasting and osteoporosis. GC‐induced osteoporosis occurs in 30% to 50% of patients on GC therapy and thus, represents an important area of study. Herein, we characterize the molecular and physiologic effects of GC‐induced osteoporosis using the Cushing's mouse model, the corticotropin releasing hormone (CRH) transgenic mouse (CRH‐Tg). The humeri, femurs, and tibias from wild‐type (WT) and CRH‐Tg male mice, aged 13 to 14 weeks old were subjected to multiple bone tests including, micro–computed tomography (μCT), static and dynamic histomorphometry, strength testing, and gene expression analyses. The CRH‐Tg mice had a 38% decrease in cortical bone area, a 35% decrease in cortical thickness, a 16% decrease in trabecular thickness, a sixfold increase in bone adiposity, a 27% reduction in osteoid width, a 75% increase in bone‐resorbing osteoclast number/bone surface, a 34% decrease in bone formation rate, and a 40% decrease in bone strength compared to WT mice. At the gene expression level, CRH‐Tg bone showed significantly increased osteoclast markers and decreased osteoblast markers, whereas CRH‐Tg muscle had increased muscle atrophy gene markers compared to WT mice. Overall, the CRH‐Tg mouse model aged to 14 weeks recapitulated many features of osteoporosis in Cushing's syndrome and thus, represents a useful model to study GC‐induced osteoporosis and interventions that target the effects of GCs on the skeleton. © 2017 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Protecting Bone Health in Pediatric Rheumatic Diseases: Pharmacological Considerations

Bone health in children with rheumatic conditions may be compromised due to several factors related to the inflammatory disease state, delayed puberty, altered life style, including decreased physical activities, sun avoidance, suboptimal calcium and vitamin D intake, and medical treatments, mainly glucocorticoids and possibly some disease-modifying anti-rheumatic drugs. Low bone density or even fragility fractures could be asymptomatic; therefore, children with diseases of high inflammatory load, such as systemic onset juvenile idiopathic arthritis, juvenile dermatomyositis, systemic lupus erythematosus, and those requiring chronic glucocorticoids may benefit from routine screening of bone health. Most commonly used assessment tools are laboratory testing including serum 25-OH-vitamin D measurement and bone mineral density measurement by a variety of methods, dual-energy X-ray absorptiometry as the most widely used. Early disease control, use of steroid-sparing medications such as disease-modifying anti-rheumatic drugs and biologics, supplemental vitamin D and calcium, and promotion of weight-bearing physical activities can help optimize bone health. Additional treatment options for osteoporosis such as bisphosphonates are still controversial in children with chronic rheumatic diseases, especially those with decreased bone density without fragility fractures. This article reviews common risk factors leading to compromised bone health in children with chronic rheumatic diseases and discusses the general approach to prevention and treatment of bone fragility.

Once-weekly teriparatide improves glucocorticoid-induced osteoporosis in patients with inadequate response to bisphosphonates

Background

Patients with glucocorticoid-induced osteoporosis (GIOP) are at very high risk of fracture, and patients with severe GIOP often experience fractures during treatment with bisphosphonates. Teriparatide (TPTD) is the only currently available anabolic agent expected to be effective for GIOP. Once-weekly TPTD decreased bone resorption marker with primary osteoporosis different from daily TPTD, but it has not yet been tested with GIOP.

Objectives

To evaluate the efficacy of once-weekly TPTD for patients with GIOP and inadequate response to bisphosphonates.

Methods

Patients with GIOP and collagen diseases treated with prednisolone for at least 6 months with inadequate responses to bisphosphonates were administered once-weekly TPTD. Bone density of the lumbar spine and femoral neck, measured as percent young adult mean (YAM); serum concentrations of cross-linked N-terminal telopeptides of type I collagen (NTx), bone alkaline phosphatase (BAP), and calcium; and FRAX were measured at baseline and 6, 12 and 18 months after starting TPTD.

Results

Of the 12 GIOP patients with collagen diseases enrolled, nine (seven females, two males; mean age 57.4 ± 11.1 years) completed treatment, including six with systemic lupus erythematosus, two with rheumatoid arthritis, and one with adult onset still disease. Only one new fracture event, a lumbar compression fracture, occurred during the study period, although seven patients experienced eight fracture events within 18 months before starting TPTD (p = 0.04). Lumbar spine YAM significantly improved at 18 months (p = 0.04), whereas femoral neck YAM did not (p = 0.477). Serum NTx, BAP, Ca, and FRAX were not significantly affected by TPTD treatment.

Conclusions

Once-weekly TPTD reduces fracture events and increases bone density of the lumbar spine of GIOP patients with inadequate response to bisphosphonates.

Multiscale alterations in bone matrix quality increased fragility in steroid induced osteoporosis

A serious adverse clinical effect of glucocorticoid steroid treatment is secondary osteoporosis, enhancing fracture risk in bone. This rapid increase in bone fracture risk is largely independent of bone loss (quantity), and must therefore arise from degradation of the quality of the bone matrix at the micro- and nanoscale. However, we lack an understanding of both the specific alterations in bone quality n steroid-induced osteoporosis as well as the mechanistic effects of these changes. Here we demonstrate alterations in the nanostructural parameters of the mineralized fibrillar collagen matrix, which affect bone quality, and develop a model linking these to increased fracture risk in glucocorticoid induced osteoporosis. Using a mouse model with an N-ethyl-N-nitrosourea (ENU)-induced corticotrophin releasing hormone promoter mutation (Crh(-120/+)) that developed hypercorticosteronaemia and osteoporosis, we utilized in situ mechanical testing with small angle X-ray diffraction, synchrotron micro-computed tomography and quantitative backscattered electron imaging to link altered nano- and microscale deformation mechanisms in the bone matrix to abnormal macroscopic mechanics. We measure the deformation of the mineralized collagen fibrils, and the nano-mechanical parameters including effective fibril modulus and fibril to tissue strain ratio. A significant reduction (51%) of fibril modulus was found in Crh(-120/+) mice. We also find a much larger fibril strain/tissue strain ratio in Crh(-120/+) mice (~1.5) compared to the wild-type mice (~0.5), indicative of a lowered mechanical competence at the nanoscale. Synchrotron microCT show a disruption of intracortical architecture, possibly linked to osteocytic osteolysis. These findings provide a clear quantitative demonstration of how bone quality changes increase macroscopic fragility in secondary osteoporosis.

Bone density and microarchitecture in endogenous hypercortisolism

OBJECTIVE

Osteoporosis is a serious and underestimated complication of endogenous hypercortisolism that results in an increased risk of fractures, even in patients with normal or slightly decreased bone mineral density (BMD). Alterations in bone microarchitecture, a very important component of bone quality, may explain bone fragility. The aim of this study was to investigate bone density and microarchitecture in a cohort of patients with endogenous Cushing's syndrome (CS).

DESIGN

Cross-sectional study.

PATIENTS

Thirty patients with endogenous active CS and fifty-one age-, sex- and body mass index-matched controls were included.

MEASUREMENTS

Participants were studied for areal BMD (dual-energy X-ray absorptiometry) of the lumbar spine (LS), femoral neck (FN), total femur (TF) and radius (33%), and for volumetric bone density (vBMD) and structure using high-resolution peripheral quantitative computed tomography (HR-pQCT) of the distal radius and distal tibia.

RESULTS

Patients with active CS exhibited lower areal BMD and Z-score values in the LS, FN and TF (P < 0·003 for all comparisons). At HR-pQCT, the patients with CS also had lower cortical area (P = 0·009 at the radius and P = 0·002 at the tibia), lower cortical thickness (P = 0·02 at the radius and P = 0·002 at the tibia), lower cortical density (P = 0·008 at the tibia) and lower total vBMD (P = 0·002 at the tibia). After the exclusion of hypogonadal individuals, the patients with CS maintained the same microarchitectural and densitometric alterations described above.

CONCLUSIONS

Endogenous hypercortisolism has deleterious effects on bone, especially on cortical bone microstructure. These effects seem to be a more important determinant of bone impairment than gonadal status.

Insights on accelerated skeletal repair in Cushing's disease

Cushing's disease with prolonged exposure to high circulating levels of glucocorticoids is associated with deterioration of the structural integrity of bone, resulting in increased skeletal fragility and fractures. The mechanism of bone repair following successful surgical treatment is poorly understood. A 34-year-old man presented with a tibial fracture and severely low BMD, elevated AM serum cortisol, ACTH, and 24 h urinary free cortisol, which did not suppress with 2 days of high dose dexamethasone. Following transphenoidal resection of a pituitary microadenoma, serum cortisol and ACTH normalized. A repeat DXA at 8 months post-resection showed no change in BMD, however the Trabecular Bone Score (TBS), which reported severe deterioration of trabecular bone architecture at diagnosis, improved to normal. At that time, teriparatide (TPTD) was given for 2 years, which resulted in a 53.9% increase in BMD with only a small improvement in TBS. In this patient, spontaneous recovery of trabecular bone architecture was reflected by the early correction in TBS. Subsequent TPTD treatment was associated with marked improvement in BMD, presumably due to enhanced mineralization. Complete skeletal repair was achieved by this two-step mechanism in a very short time following successful surgical treatment for Cushing's disease.

Risk factors for decreased bone mineral density in inflammatory bowel disease: A cross-sectional study

BACKGROUND & AIM

Although inflammatory bowel disease (IBD) patients are at risk for metabolic bone disease, studies analyzing this correlation have identified various risk factors, including disease phenotype, age, sex and steroid therapy. Furthermore, few studies have assessed risk factors for bone loss in Japanese IBD patients. This study analyzed risk factors for metabolic bone disease in Japanese IBD patients.

METHODS

This cross-sectional study assessed 388 patients with IBD aged 20-50 years, including 232 with ulcerative colitis (UC) and 156 with Crohn's disease (CD). Bone mineral density of the femoral neck, total femur and lumbar spine was quantified by dual-energy X-ray absorptiometry. The blood concentrations of bone metabolism markers were measured. History of smoking and bone fracture, and nutritional intake were assessed using questionnaires.

RESULTS

Of the 388 patients with IBD, 78 (20.1%; UC, 17.2%; CD, 24.4%) had osteopenia and 17 (4.4%; UC, 3.4%; CD, 5.8%) had osteoporosis, as assessed by T-score. Bone mineral density of the lumbar vertebrae was lower in males than in females. Multivariate regression analysis showed that risk factors for bone loss in UC patients were male sex, low body mass index (BMI), high steroid dose and disease location. Risk factors for bone loss in CD patients were male sex and low BMI.

CONCLUSION

Among Japanese patients with IBD, male sex and low BMI were associated with increased risk for metabolic bone disease. In addition, Steroid therapy shouldn't be indiscriminate in UC patients. These findings may help identify patients at particularly high risk of metabolic bone disease and may help implement appropriate therapies in a timely manner and improve long-term quality of life.

Protective effects of necrostatin-1 on glucocorticoid-induced osteoporosis in rats

The inhibition of bone formation has been suggested to play a central role in the pathogenesis of glucocorticoid-induced osteoporosis (GIOP). Recently, many studies suggested that there may be another mechanism involved in GIOP besides apoptosis. The aim of this study was to investigate the protective effect of Necrostatin-1 on GIOP rats. Forty male Sprague-Dawley rats were randomly divided into four groups (n=10): controls; GIOP rats; GIOP rats pretreated with alendronate; and GIOP rats pretreated with Necrostatin-1. Their bone mineral density (BMD) and body weight were measured at the beginning and at the end of the experiment. TUNEL assay, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to observe the change of cellular morphology induced by Nec-1. The biochemical analysis and histomorphometric analysis were used to evaluate the change of bone formation by Nec-1. RIP-1, RIP-3 and caspase-8 expression were evaluated by immunohistochemistry. We found more TUNEL positive osteocytes and larger lacunae volume in GIOP rats compared with the control group. However, most of the osteocytes displayed a necrotic morphology and mitochondria lesions under TEM. In contrast to alendronate, Necrostatin-1 significantly elevated the level of bone formation markers, while it had no effect on bone resorption markers. Necrostatin-1 also markedly ameliorated trabecular bone. In addition, Necrostatin-1 significantly weaken the immunoreactivity of RIP-1 in GIOP rats while had no effect on RIP-3 and caspase-8. These data suggest, for the first time, that Necrostatin-1 accelerate bone formation of glucocorticoid-induced osteoporosis in rats.

From histology to micro-CT: Measuring and modeling resorption cavities and their relation to bone competence

The process of bone remodelling plays an essential role in the emergence and maintenance of bone geometry and its internal structure. Osteoclasts are one of the three main bone cell types that play a crucial role in the bone remodelling cycle. At the microstructural level, osteoclasts create bone deficits by eroding resorption cavities. Understanding how these cavities impair the mechanical quality of the bone is not only relevant in quantifying the impact of resorption cavities in healthy bone and normal aging, but maybe even more so in quantifying their role in metabolic bone diseases. Metabolic bone diseases and their treatment are both known to affect the bone remodelling cycle; hence, the bone mechanical competence can and will be affected. However, the current knowledge of the precise dimensions of these cavities and their effect on bone competence is rather limited. This is not surprising considering the difficulties in deriving three-dimensional (3D) properties from two-dimensional (2D) histological sections. The measurement difficulties are reflected in the evaluation of how resorption cavities affect bone competence. Although detailed 3D models are generally being used to quantify the mechanical impact of the cavities, the representation of the cavities themselves has basically been limited to simplified shapes and averaged cavity properties. Qualitatively, these models indicate that cavity size and location are important, and that the effect of cavities is larger than can be expected from simple bone loss. In summary, the dimensions of osteoclast resorption cavities were until recently estimated from 2D measures; hence, a careful interpretation of resorption cavity dimensions is necessary. More effort needs to go into correctly quantifying resorption cavities using modern 3D imaging techniques like micro-computed tomography (micro-CT) and synchrotron radiation CT. Osteoclast resorption cavities affect bone competence. The structure-function relationships have been analysed using computational models that, on one hand, provide rather detailed information on trabecular bone structure, but on the other incorporate rather crude assumptions on cavity dimensions. The use of high-resolution representations and parametric descriptions could be potential routes to improve the quantitative fidelity of these models.

Bone disease in newly diagnosed lupus nephritis patients

Introduction

Bone loss in Lupus Nephritis (LN) patients is common and multifactorial. The aim of this study was to evaluate the bone status of newly diagnosed LN patients and their correlation with inflammatory factors involved in LN physiopathology.

Methods

We studied 15 pre-menopausal patients with ≤2 months of diagnosed SLE and LN. Patients with prior kidney or bone disease were excluded. In addition to biochemical evaluation (including 25-hydroxyvitamin D₃ [25(OH)D] and Monocyte Chemotactic Protein (MCP1) dosage), we performed bone biopsies followed by osteoblast culture, histomorphometric and immunohistochemistry analysis.

Results

LN patients presented a mean age of 29.5±10 years, a proteinuria of 4.7±2.9 g/day and an estimated glomerular filtration rate (GFR) of 37(31–87) ml/min/1,73 m². They were on glucocorticoid therapy for 34±12 days. All patients presented vitamin D insufficiency (9.9±4.4 ng/ml, range 4–20). Urinary MCP1 correlated negatively with 25(OH)D (r = −0.53, p = 0.003) and positively with serum deoxypyridinoline (r = 0.53, p = 0.004). Osteoblasts isolated from LN bone biopsies presented a significantly higher expression of MCP-1 when compared to controls (32.0.±9.1 vs. 22.9±5.3 mean fluorescence intensities, p = 0.01). LN patients presented a significantly reduced osteoid volume, osteoid thickness, osteoid surface, mineralization surface and bone formation rate, associated with an increased eroded surface and osteoclast surface. Patient’s bone specimens demonstrated a reduced immunostaining for osteoprotegerin (0.61±0.82 vs. 1.08±0.50%, p = 0.003), and an increased expression of Receptor Activator of NF-κB ligand (RANKL) (1.76±0.92 vs. 0.41±0.28%, p<0.001) when compared to controls.

Discussion

Newly diagnosed LN patients presented a significant disturbance in bone metabolism, characterized by an impaired bone formation and mineralization, associated with an increase in resorption parameters. Glucocorticoid use, vitamin D insufficiency and inflammation might be involved in the physiopathology of bone metabolism disturbance.

Skeletal findings in the first 12 months following initiation of glucocorticoid therapy for pediatric nephrotic syndrome

Incident vertebral fractures and lumbar spine bone mineral density (BMD) were assessed in the 12 months following glucocorticoid initiation in 65 children with nephrotic syndrome. The incidence of vertebral fractures was low at 12 months (6 %) and most patients demonstrated recovery in BMD Z-scores by this time point.

INTRODUCTION

Vertebral fracture (VF) incidence following glucocorticoid (GC) initiation has not been previously reported in pediatric nephrotic syndrome.

METHODS

VF was assessed on radiographs (Genant method); lumbar spine bone mineral density (LS BMD) was evaluated by dual-energy X-ray absorptiometry.

RESULTS

Sixty-five children were followed to 12 months post-GC initiation (median age, 5.4 years; range, 2.3-17.9). Three of 54 children with radiographs (6 %; 95 % confidence interval (CI), 2-15 %) had incident VF at 1 year. The mean LS BMD Z-score was below the healthy average at baseline (mean ± standard deviation (SD), -0.5 ± 1.1; p = 0.001) and at 3 months (-0.6 ± 1.1; p < 0.001), but not at 6 months (-0.3 ± 1.3; p = 0.066) or 12 months (-0.3 ± 1.2; p = 0.066). Mixed effect modeling showed a significant increase in LS BMD Z-scores between 3 and 12 months (0.22 SD; 95 % CI, 0.08 to 0.36; p = 0.003). A subgroup (N = 16; 25 %) had LS BMD Z-scores that were ≤-1.0 at 12 months. In these children, each additional 1,000 mg/m(2) of GC received in the first 3 months was associated with a decrease in LS BMD Z-score by 0.39 at 12 months (95 % CI, -0.71 to -0.07; p = 0.017).

CONCLUSIONS

The incidence of VF at 1 year was low and LS BMD Z-scores improved by 12 months in the majority. Twenty-five percent of children had LS BMD Z-scores ≤-1.0 at 12 months. In these children, LS BMD Z-scores were inversely associated with early GC exposure, despite similar GC exposure compared to the rest of the cohort.

Impairment of rat tooth eruption in pups born to mothers exposed to chronic stress during pregnancy

OBJECTIVE

Tooth eruption is a multifactorial process in which bone tissue plays a prevailing role. In this study we evaluated the bone overlying the developing tooth germ and the degree of tooth eruption of the first mandibular molar in pups born to mothers subjected to constant light during pregnancy.

DESIGN

Pregnant rats were divided into two groups: mothers chronically exposed to a 12:12 light/light cycle (LL) from day 10 to 20 of pregnancy and controls (C) maintained on a 12:12 h light/dark cycle. Pups from each group were euthanized at the age 3 or 15 days. Buccolingually oriented sections of mandibles were stained with haematoxylin-eosin or for histochemical detection of tartrate resistant acid phosphatase (TRAP). The histomorphometric parameters evaluated were bone volume, number of osteoclasts, TRAP+ bone surface, number of TRAP+ and TRAP- osteoclasts per mm(2) and degree of tooth eruption (mm).

RESULTS

It was found an increase in bone volume (LL: 58.14±4.24 vs. C: 32.31±2.16; p<0.01) and a decrease in the number of osteoclasts (LL: 3.5±0.65 vs. C: 8.03±1.31; p<0.01) and TRAP+ cells (LL: 0.84±0.53 vs. C: 8.59±1.26; p<0.01) in 3-day-old pups born to LL-exposed mothers. These observations are consistent with the decrease in the degree of tooth eruption observed in 15-day-old experimental pups (LL: -0.605±0.05 vs. C: -0.342±0.02; p<0.0001).

CONCLUSION

Our results suggest that chronic constant light applied as a pre-natal stressor impairs the resorptive capacity of osteoclasts involved in the formation of the eruption pathway and consequently the degree of tooth eruption.

Glucocorticoid-induced changes in the geometry of osteoclast resorption cavities affect trabecular bone stiffness

Bone fracture risk can increase through bone microstructural changes observed in bone pathologies, such as glucocorticoid-induced osteoporosis. Resorption cavities present one of these microstructural aspects. We recently found that glucocorticoids (GCs) affect the shape of the resorption cavities. Specifically, we found that in the presence of GC osteoclasts (OCs) cultured on bone slices make more trenchlike cavities, compared to rather round cavities in the absence of GCs, while the total eroded surface remained constant. For this study, we hypothesized that trenchlike cavities affect bone strength differently compared to round cavities. To test this hypothesis, we cultured OCs on bone slices in the presence and absence of GC and quantified their dimensions. These data were used to model the effects of OC resorption cavities on bone mechanical properties using a validated beam-shell finite element model of trabecular bone. We demonstrated that a change in the geometry of resorption cavities is sufficient to affect bone competence. After correcting for the increased EV/BV with GCs, the difference to the control condition was no longer significant, indicating that the GC-induced increase in EV/BV, which is closely related to the shape of the cavities, highly determines the stiffness effect. The lumbar spine was the anatomic site most affected by the GC-induced changes on the shape of the cavities. These findings might explain the clinical observation that the prevalence of vertebral fractures during GC treatment increases more than hip, forearm and other nonvertebral fractures.

A model for the change of cancellous bone volume and structure over time

A model is presented for characterizing the process by which cancellous bone changes in volume and structure over time. The model comprises simulations of local changes resulting from individual remodelling events, known as bone multicellular units (BMU), and an ordinary differential equation for connecting the number of remodelling events to real time. The model is validated on micro-CT scans of tibiae of normal rats, estrogen deprived rats and estrogen deprived rats treated with bisphosphonates. The model explains the asymptotic trends seen in changes of bone volume over time resulting from estrogen deprivation as well as trends seen subsequent to treatment. The model demonstrates that both bone volume and structure changes can be explained in terms of resetting remodelling parameters. The model also shows that either current understanding of the effects of bisphosphonates is not correct or that the simplest description of remodelling does not suffice to explain both the change in bone volume and structure of rats treated with bisphosphonates.

Effect of renal function on skeletal health in primary hyperparathyroidism

CONTEXT

Current guidelines recommend parathyroidectomy in patients with primary hyperparathyroidism (PHPT) who have an estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m(2). It is unclear, however, whether values below this threshold of renal impairment affect bone and mineral metabolism in PHPT.

OBJECTIVE

The purpose of this study was to assess the effect of renal function on skeletal health in PHPT.

DESIGN

This is a retrospective analysis of PHPT patients with (eGFR < 60 ml/min per 1.73 m(2)) and without chronic kidney disease (CKD) from our previously described PHPT cohort recruited from 1984 to 1991.

SETTING

The study was conducted in a university hospital metabolic bone unit.

PARTICIPANTS

One hundred thirty-eight women and men with PHPT were studied.

OUTCOME MEASURES

We assessed bone mineral density (BMD) by dual-energy x-ray absorptiometry; quantitative histomorphometric indices from transiliac bone biopsies; and biochemical markers of mineral metabolism.

RESULTS

Although there was no difference in serum or urinary calcium or PTH level, calcitriol levels were lower and phosphate levels higher in patients with CKD. BMD adjusted for weight did not differ at any site between groups. Histomorphometric analysis (n = 30 of 138) revealed a 45% greater eroded surface in those with CKD (P = 0.02). Eroded surface negatively correlated with eGFR (r = -0.46, P = 0.02) and phosphate (r = -0.48, P = 0.02) and positively correlated with serum calcium level (r = 0.51, P = 0.009) but not with PTH, alkaline phosphatase, vitamin D metabolites, or urinary calcium excretion.

CONCLUSION

Although cardinal biochemical indices (such as calcium and PTH) and BMD do not differ in PHPT patients with an eGFR below 60 ml/min per 1.73 m(2), these patients have higher phosphate and histomorphometric evidence of altered bone remodeling compared with those without CKD.

Volumetric bone mineral density and bone structure in childhood chronic kidney disease

Chronic kidney disease (CKD) is associated with increased fracture risk and skeletal deformities. The impact of CKD on volumetric bone mineral density (vBMD) and cortical dimensions during growth is unknown. Tibia quantitative computed tomographic scans were obtained in 156 children with CKD [69 stages 2 to 3, 51 stages 4 to 5, and 36 stage 5D (dialysis)] and 831 healthy participants aged 5 to 21 years. Sex-, race-, and age- or tibia length-specific Z-scores were generated for trabecular BMD (TrabBMD), cortical BMD (CortBMD), cortical area (CortArea) and endosteal circumference (EndoC). Greater CKD severity was associated with a higher TrabBMD Z-score in younger participants (p < .001) compared with healthy children; this association was attenuated in older participants (interaction p < .001). Mean CortArea Z-score was lower (p < .01) in CKD 4-5 [-0.49, 95% confidence interval (CI) -0.80, -0.18)] and CKD 5D (-0.49, 95% CI -0.83, -0.15) compared with healthy children. Among CKD participants, parathyroid hormone (PTH) levels were positively associated with TrabBMD Z-score (p < .01), and this association was significantly attenuated in older participants (interaction p < .05). Higher levels of PTH and biomarkers of bone formation (bone-specific alkaline phosphatase) and resorption (serum C-terminal telopeptide of type 1 collagen) were associated with lower CortBMD and CortArea Z-scores and greater EndoC Z-score (r = 0.18-0.36, all p ≤ .02). CortBMD Z-score was significantly lower in CKD participants with PTH levels above versus below the upper limit of the Kidney Disease Outcome Quality Initiative (KDOQI) CKD stage-specific target range: -0.46 ± 1.29 versus 0.12 ± 1.14 (p < .01). In summary, childhood CKD and secondary hyperparathyroidism were associated with significant reductions in cortical area and CortBMD and greater TrabBMD in younger children. Future studies are needed to establish the fracture implications of these alterations and to determine if cortical and trabecular abnormalities are reversible.

Skeletal health of children and adolescents with inflammatory bowel disease

Current evidence points to suboptimal bone health in children and adolescents with inflammatory bowel disease (IBD) when compared with their healthy peers. This compromise is evident from diagnosis. The clinical consequences and long-term outcome of this finding are still unknown. The mechanism of suboptimal bone health in children and adolescents with IBD lays mainly in reduced bone formation, but also reduced bone resorption, processes necessary for bone growth. Factors contributing to this derangement are inflammation, delayed growth and puberty, lean mass deficits, and use of glucocorticoids. We recognize that evidence is sparse on the topic of bone health in children and adolescents with IBD. In this clinical guideline, based on current evidence, we provide recommendations on screening and monitoring bone health in children and adolescents with IBD, including modalities to achieve this and their limitations; monitoring of parameters of growth, pubertal development, and reasons for concern; evaluation of vitamin D status and vitamin D and calcium intake; exercise; and nutritional support. We also report on the current evidence of the effect of biologics on bone health in children and adolescents with IBD, as well as the role of bone active medications such as bisphosphonates. Finally, we summarize the existing numerous gaps in knowledge and potential subjects for future research endeavors.

Advanced imaging assessment of bone fragility in glucocorticoid-induced osteoporosis

Advanced bone imaging techniques provide structural information, beyond bone mineral density (BMD), and growing evidence indicates that BMD only partially explains bone strength and fracture resistance. Assessing glucocorticoid-induced osteoporosis (GIO) is important, especially the documentation of glucocorticoid (GC) impact on trabecular and cortical bone and on macro and microstructural features. Advanced methods for assessing macrostructure of bone include volumetric quantitative computed tomography (vQCT), high-resolution computed tomography (hrCT), and high-resolution magnetic resonance imaging (hrMRI). The methods for assessing bone microstructure include micro computed tomography (μCT) and micro magnetic resonance imaging (μMRI). Many advanced imaging techniques have been used in vitro and in vivo to examine structural effects of GIO in animals and in humans, and these applications are explored in this review. In human in vitro studies, investigators have used standard bone histomorphometry and μCT to compare trabecular microarchitecture and bone remodeling in postmenopausal women and in males with GIO, and have found that high-dose GC produces dramatic bone loss, accompanied by major reduction in trabecular connectivity and increases in trabecular perforations. In animal studies, investigators have used standard histomorphometry along with pQCT, vQCT, hrMRI or μCT to examine GIO in a variety of animal models including rats, minipigs and sheep. They generally have found excellent relationships between treatment-induced structural changes assessed by these advanced imaging techniques and changes in BMD and biomechanical properties. They also have examined various therapeutic interventions in animals and monitored their efficacy using quantitative imaging methods. In human in vivo studies, investigators have serially examined postmenopausal women and males with GIO in order to assess the extent of skeletal deterioration and to determine the best advanced measures of BMD and structure, with which to monitor disease activity and therapeutic response, and to predict fracture risk. They generally have found that bone density and structural measures obtained by pQCT, vQCT and hrMRI contributed substantially to understanding the skeletal effects of glucocorticoids and to predicting the risk of fracture in human GIO. These animal and human applications, illustrating advanced imaging in GIO, are still in early stages of development. However, as discussed in this review, the novelty and power of the imaging approaches are compelling, and their utility is promising.

Osteoclast activity and subtypes as a function of physiology and pathology--implications for future treatments of osteoporosis

Osteoclasts have traditionally been associated exclusively with catabolic functions that are a prerequisite for bone resorption. However, emerging data suggest that osteoclasts also carry out functions that are important for optimal bone formation and bone quality. Moreover, recent findings indicate that osteoclasts have different subtypes depending on their location, genotype, and possibly in response to drug intervention. The aim of the current review is to describe the subtypes of osteoclasts in four different settings: 1) physiological, in relation to turnover of different bone types; 2) pathological, as exemplified by monogenomic disorders; 3) pathological, as identified by different disorders; and 4) in drug-induced situations. The profiles of these subtypes strongly suggest that these osteoclasts belong to a heterogeneous cell population, namely, a diverse macrophage-associated cell type with bone catabolic and anabolic functions that are dependent on both local and systemic parameters. Further insight into these osteoclast subtypes may be important for understanding cell-cell communication in the bone microenvironment, treatment effects, and ultimately bone quality.

Histomorphometric analysis reveals reduced bone mass and bone formation in patients with quiescent Crohn's disease

BACKGROUND & AIMS

Crohn's disease (CD) is associated with an increased prevalence of osteoporosis, but the pathogenesis of this bone loss is only partly understood. We assessed bone structure and remodeling at the tissue level in patients with quiescent CD. We also investigated the roles of osteocyte density and apoptosis in CD-associated bone loss.

METHODS

The study included 23 patients with quiescent CD; this was a subgroup of patients from a large randomized, double-blind, placebo-controlled, multicenter trial. We obtained transiliac bone biopsy samples and performed histomorphometric analysis. Results were compared with data from age- and sex-matched healthy individuals (controls).

RESULTS

Trabecular bone volume was decreased among patients with CD compared with controls (18.90% vs 25.49%; P < .001). The low bone volume was characterized by decreased trabecular thickness (120.61 vs 151.42 μm; P < .01). Bone formation and resorption were reduced, as indicated by a decreased mineral apposition rate (0.671 vs 0.746 μm/day; P < .01) and a low osteoclast number and surface area compared with controls and published values, respectively. In trabecular bone of patients with CD, osteocyte density and apoptosis were normal. The percentage of empty lacunae among patients was higher than that of published values in controls.

CONCLUSIONS

In adult patients with quiescent CD, bone histomorphometric analysis revealed a reduction in bone mass that was characterized by trabecular thinning. The CD-associated bone loss was caused by reduced bone formation, possibly as a consequence of decreased osteocyte viability in the patients' past.

[Bone mineral density in patients with renal hyperparathyroidism undergoing surgery: relationship with bone parameters]

BACKGROUND AND OBJECTIVES

Hyperparathyroidism (HPT) in chronic kidney disease (CKD) may alter the composition and bone architecture, and cause fractures. The DEXA bone mineral density (BMD), used to predict fracture risk, measures the amount of calcium in bone. However, we do not know the relationship between BMD and bone composition.

PATIENT AND METHOD

Our study, conducted in two groups of renal patients with HPT who underwent parathyroidectomy (PTX): patients on hemodialysis (HD group) and patients with renal transplant (RT group). The aims were to quantify and value the differences among groups and by gender on bone mineral density, quantify and define differences between these two groups and a control group regarding the elemental composition of bone marrow biopsy obtained and static parameters of bone histomorphometry, and define a possible relationship between bone mineral density and bone elements versus histomorphometric parameters.

RESULTS

The BMD mean in femur was higher in TR group than in HD group. Linear correlation analysis performed between parameters versus BMD and bone histomorphometry elements, considering both TR and HD, only correlation between femur BMD (gr/cm2) and calcium (r=0.435, p=0.034, n=24) was observed.

CONCLUSION

Hyperparathyroidism patients undergoing renal transplant had better femoral BMD than those on hemodialysis; the trabecular volume was lower in kidney transplantation, while the volume of fibrosis was higher in hemodialysis patients; the elements in bone transplant and hemodialysis were in similar proportion, while the calcium content tended to be higher in renal transplant.

Bone formation markers in patients with glucocorticoid-induced osteoporosis treated with teriparatide or alendronate

Reduced osteoblast function is a primary defect in glucocorticoid-induced osteoporosis (GIO), and is reflected by decreased biochemical markers of bone formation, such as serum osteocalcin (OC) and procollagen type I N-terminal propeptide (PINP). This analysis compared the effects of teriparatide and alendronate on OC and PINP in patients with GIO. In a double-blind study, women (N=159) and men (N=38) with GIO were randomized to either teriparatide 20 mug/day by subcutaneous injection or to alendronate 10 mg/day orally. OC and PINP were measured in fasting-state serum samples obtained at baseline and at 1, 6, 18, and 36 months. Baseline bone formation markers were below the reference interval (low) in 33% of patients for OC and in 4% of patients for PINP. On teriparatide therapy, the median OC and PINP levels increased by 92% and 108%, respectively, and this resulted in only 12% and 1% of patients being low at 6 months. On alendronate therapy, the median OC and PINP levels decreased by 40% and 53%, respectively, and this resulted in 68% and 34% of patients being low at 6 months. We conclude that bone formation as determined by surrogate markers was increased in teriparatide-treated patients with GIO and decreased in alendronate-treated patients with GIO.

Long-term therapy in COPD: any evidence of adverse effect on bone?

Patients with COPD have high risk for osteoporosis and fractures. Hip and vertebral fractures might impair mobility, and vertebral fractures further reduce lung function. This review discusses the evidence of bone loss due to medical treatment opposed to disease severity and risk factors for COPD, and therapeutic options for the prevention and treatment of osteoporosis in these patients. A review of the English-language literature was conducted using the MEDLINE database until June 2009. Currently used bronchodilators probably lack adverse effect on bone. Oral corticosteroids (OCS) increase bone resorption and decrease bone formation in a dose response relationship, but the fracture risk is increased more than reflected by bone densitometry. Inhaled corticosteroids (ICS) have been associated with both increased bone loss and fracture risk. This might be a result of confounding by disease severity, but high doses of ICS have similar effects as equipotent doses of OCS. The life-style factors should be modified, use of regular OCS avoided and use of ICS restricted to those with evidenced effect and probably kept at moderate doses. The health care should actively reveal risk factors, include bone densitometry in fracture risk evaluation, and give adequate prevention and treatment for osteoporosis.

Genistein aglycone reverses glucocorticoid-induced osteoporosis and increases bone breaking strength in rats: a comparative study with alendronate

BACKGROUND AND PURPOSE

Glucocorticoid-induced osteoporosis (GIO) is the leading cause of secondary osteoporosis. Clinical evidence suggests a role for genistein aglycone in the treatment of post-menopausal osteopenia although proof of efficacy in comparison with currently available treatments is still lacking. To clarify this issue, we investigated the effects of genistein on bone compared with alendronate in experimental GIO.

EXPERIMENTAL APPROACH

A total of 28 female Sprague-Dawley rats were used. GIO was induced by daily injections of methylprednisolone (MP; 30 mg x kg(-1) s.c.) for 60 days. Sham GIO animals (Sham-MP) were injected daily with the MP vehicle. At the end of the osteoporosis development period, MP rats were randomized to receive: vehicle (n= 7), genistein aglycone (5 mg x kg(-1) s.c.; n= 7) or alendronate (0.03 mg x kg(-1) s.c.; n= 7). Treatment lasted 60 days. Sham-MP animals were treated with vehicle for an additional 60 days. At the beginning and at the end of treatments, animals were examined for bone mineral density and bone mineral content. Bone-alkaline phosphatase and carboxy-terminal collagen cross links were determined; femurs were removed and tested for breaking strength and histology.

KEY RESULTS

Genistein aglycone showed a greater increase in bone mineral density, bone mineral content and in breaking strength than alendronate and significantly increased bone-alkaline phosphatase (bone formation marker), reduced carboxy-terminal collagen cross links (bone resorption marker), compared with alendronate. Both treatments improved bone histology and the histological score.

CONCLUSION AND IMPLICATIONS

The results strongly suggest that the genistein aglycone might be an alternative therapy for the management of secondary osteoporosis.

Effect of eicosapentaenoic acid on bone changes due to methylprednisolone in rats

The present study was conducted to investigate the effects of eicosapentaenoic acid on glucocorticoid-induced bone changes in rats, and to compare them with those of alendronate. Thirty six male Wistar rats, 2.5 months of age, were divided into six groups (n = 6 each) and treated with 0.9% NaCl (control), methylprednisolone 7 mg/kg, once a week subcutaneously, methylprednisolone + alendronate 20 microg/kg, twice a week subcutaneously and methylprednisolone + 80 or 160 or 320 mg/kg eicosapentaenoic acid, per day orally, for 6 weeks. At the end of the experiment, serum and urinary parameters of bone metabolism determined and bone histomorphometric analyses performed on cancellous bone of femoral epiphysis and metaphysis and cortical bone of tibial diaphysis. There were no significant differences in serum and urinary parameters among groups. Decrease of epiphyseal and metaphyseal trabecular width, epiphyseal bone area/tissue area and increase of epiphyseal trabecular separation observed in the methylprednisolone group compared to control. Alendronate restored all of these parameters except metaphyseal trabecular width, which increased significantly by eicosapentaenoic acid at the doses of 80 and 160 mg/kg. Effects of alendronate and 160 mg/kg eicosapentaenoic acid on bone area/tissue area, alendronate and eicosapentaenoic acid at the doses of 80 and 160 mg/kg on trabecular separation and alendronate and eicosapentaenoic acid at doses of 160 and 320 mg/kg on epiphyseal trabecular width were statistically similar. Methylprednisolone did not significantly change cortical bone parameters including cortical width and marrow area/cortical area. Eicosapentaenoic acid, especially, at the dose of 160 mg/kg exerts beneficial effects on methylprednisolone-induced bone changes in rats; these effects are similar or sometimes even better than alendronate.

Divergent effects of glucocorticoids on cortical and trabecular compartment BMD in childhood nephrotic syndrome

Glucocorticoid (GC) effects on skeletal development have not been established. The objective of this pQCT study was to assess volumetric BMD (vBMD) and cortical dimensions in childhood steroid-sensitive nephrotic syndrome (SSNS), a disorder with minimal independent deleterious skeletal effects. Tibia pQCT was used to assess trabecular and cortical vBMD, cortical dimensions, and muscle area in 55 SSNS (age, 5-19 yr) and >650 control participants. Race-, sex-, and age-, or tibia length-specific Z-scores were generated for pQCT outcomes. Bone biomarkers included bone-specific alkaline phosphatase and urinary deoxypyridinoline. SSNS participants had lower height Z-scores (p < 0.0001) compared with controls. In SSNS, Z-scores for cortical area were greater (+0.37; 95% CI = 0.09, 0.66; p = 0.01), for cortical vBMD were greater (+1.17; 95% CI = 0.89, 1.45; p < 0.0001), and for trabecular vBMD were lower (-0.60; 95% CI, = -0.89, -0.31; p < 0.0001) compared with controls. Muscle area (+0.34; 95% CI = 0.08, 0.61; p = 0.01) and fat area (+0.56; 95% CI = 0.27, 0.84; p < 0.001) Z-scores were greater in SSNS, and adjustment for muscle area eliminated the greater cortical area in SSNS. Bone formation and resorption biomarkers were significantly and inversely associated with cortical vBMD in SSNS and controls and were significantly lower in the 34 SSNS participants taking GCs at the time of the study compared with controls. In conclusion, GCs in SSNS were associated with significantly greater cortical vBMD and cortical area and lower trabecular vBMD, with evidence of low bone turnover. Lower bone biomarkers were associated with greater cortical vBMD. Studies are needed to determine the fracture implications of these varied effects.

Skeletal involvement in adult patients with endogenous hypercortisolism

Overt endogenous glucocorticoid excess is a well-recognized cause of bone loss and osteoporotic fractures. Cortisol excess inhibits bone formation, increases bone resorption, impairs calcium absorption from the gut, and affects the secretion of several hormones (in particular gonadotropins and GH), cytokines, and growth factors, influencing bone metabolism. The glucocorticoid excess mainly affects trabecular bone, leading to vertebral fractures in up to 70% of patients. Osteoporotic fractures may be the presenting symptom of an otherwise silent glucocorticoid excess and can precede the diagnosis of hypercortisolism by up to 2 yr. The removal of glucocorticoid excess leads to a recovery of bone mass which is, however, often incomplete and delayed, although it reduces the risk of osteoporotic fractures. Bisphosphonate therapy has been suggested to be useful in maintaining bone mass in these patients. Subclinical hypercortisolism, a condition of impaired hypothalamic- adrenal-axis homeostasis without the classical signs and symptoms of glucocorticoid excess, is a recently defined entity, which has been shown to be associated to increased bone resorption, bone loss, and high prevalence of vertebral fractures regardless of gonadal status. However, data about the effect of this subtle glucocorticoid excess on bone are still scarce and conflicting. Moreover, it is not yet known whether removing the cause of subclinical hypercortisolism leads to a recovery of bone mass and reduces the risk of osteoporotic fractures. Finally, recent data suggest that subclinical hypercortisolism is a common and underrated finding in patients with established osteoporosis. In summary, it is crucial to evaluate the risk of osteoporosis and fractures in patients with glucocorticoid excess; on the other hand, it also seems advisable to screen for glucocorticoid excess patients with osteoporotic fractures without known secondary causes of osteoporosis.

Medication-induced osteoporosis

Osteoporosis, a condition of low bone mass and microarchitectural deterioration, results in fractures with minimal trauma. Secondary osteoporosis is defined as bone loss resulting from either specific clinical disorders or medications. Some medications that can induce osteoporosis are discussed. Specifically, this article reviews the pathogenesis of glucocorticoid-induced bone loss and demonstrates the means to successfully manage the condition with a combination of calcium and vitamin D supplementation and, depending on the severity of the bone loss, bisphosphonates or parathyroid hormone. In addition, the pathophysiology of bone loss from aromatase inhibitors in women, gonadotropin-releasing hormone agonists in men, anticonvulsant medications, and proton pump inhibitors is outlined. Finally, this review offers suggestions on evaluation and management of bone health in individuals treated with these medications for prolonged times.

Clinical perspectives on bone quality in osteoporosis: effects of drug therapy

Treatment of primary osteoporosis has advanced dramatically during the past decade, with more therapeutic options being available now than at any other time. Anti-resorptive (anti-catabolic) drugs have been prominent in the treatment of osteoporosis for decades. However, over time, several clinical observations made during use of these agents have challenged the prevailing dogma about mechanisms of drug action, changes in bone density and fracture reduction during treatment. It has become clear that changes in bone density are only a small part of the explanation for the dramatic reduction of fractures with treatment. From this paradox developed the notion of 'bone quality'- an operational term describing a number of characteristics that enable bone to resist fracturing. This article reviews this concept from a clinical perspective. It discusses the historical paradoxes found in clinical practice that have led to this notion, identifies the major areas of bone physiology circumscribed by the concept and focuses on present therapies and their effects on bone quality.

Ibandronate treatment reverses glucocorticoid-induced loss of bone mineral density and strength in minipigs

The Göttingen minipig is one of the few large animal models that show glucocorticoid (GC)-induced bone loss. We investigated whether GC-induced loss of bone mineral density (BMD) and bone strength in minipigs can be recovered by treatment with the bisphosphonate ibandronate (IBN). 40 primiparous sows were allocated to 4 groups when they were 30 months old: GC treatment for 8 months (GC8), for 15 months (GC15), GC treatment for 15 months plus IBN treatment for months 8-15 (GC&IBN), and a control group without GC treatment. Prednisolone was given at a daily oral dose of 1 mg/kg body weight for 8 weeks and thereafter 0.5 mg/kg body weight. IBN was administered intramuscularly and intermittently with an integral dose of 2.0 mg/kg body weight. BMD of the lumbar spine (L1-3) was assessed in vivo by Quantitative Computed Tomography (QCT) at months 0, 8, and 15. Blood and urine samples were obtained every 2-3 months. After sacrificing the animals lumbar vertebrae L4 were tested mechanically (Young's modulus and ultimate stress). Histomorphometry was performed on L2 and mineral content determined in ashed specimens of T12 and L4. In the GC&IBN group, the GC associated losses in BMD of -10.5%+/-1.9% (mean+/-standard error of the mean, p<0.001) during the first 8 months were more than recovered during the following 7 months of IBN treatment (+14.8%+/-1.2%, p<0.0001). This increase was significantly larger (p<0.0001) than the insignificant +2.1%+/-1.2% change in group GC15. At month 15, the difference between groups GC&IBN and GC15 was 22% (p<0.01) for BMD, 48% (p<0.05) for Young's modulus, and 31% (p<0.14) for ultimate stress; bone-specific alkaline phosphatase showed trends to lower values (p<0.2) while deoxypyridinoline was comparable. This minipig study demonstrates that GC-induced impairment of bone strength can be effectively and consistently treated by IBN. GC&IBN associated alterations in BMD and bone turnover markers can be monitored in vivo using QCT of the spine and by biochemical analyses, reflecting the changes in bone strength.

Evidence that calcineurin is required for the genesis of bone-resorbing osteoclasts

Here, we demonstrate that the Ca(2+)/calmodulin-sensitive phosphatase calcineurin is a necessary downstream mediator for osteoclast differentiation. Using quantitative PCR, we detected the calcineurin isoforms Aalpha, Abeta, Agamma (catalytic), and B1 (regulatory) in osteoclast precursor RAW-C3 cells. We found that, although the expression of these isoforms remained relatively unchanged during osteoclast differentiation, there was a profound increase in the expression of their primary substrate for calcineurin, nuclear factor of activated T cells (NFAT)c1. For gain-of-function studies, we incubated osteoclast precursors for 10 min with a calcineurin fusion protein (TAT-calcineurin Aalpha); this resulted in its receptorless influx into >90% of the precursor cells. A marked increase in the expression of the osteoclast differentiation markers tartrate-resistant acid phosphatase (TRAP) and integrin beta(3) followed. In addition, the expression of NFATc1, as well as the alternative substrate for calcineurin, IkappaBalpha, was significantly enhanced. Likewise, transfection with constitutively active NFAT resulted in an increased expression of both TRAP and integrin beta(3). In parallel loss-of-function studies, transfection with dominant-negative NFAT not only inhibited osteoclast formation but also reversed the induction of NFATc1, TRAP, and integrin beta(3) by TAT-calcineurin Aalpha. The expression of these markers was also inhibited by calcineurin Aalpha U1 small nuclear RNA, which significantly reduced calcineurin Aalpha mRNA and protein expression. Consistent with these observations, we observed a reduction in osteoclastogenesis in calcineurin Aalpha(-/-) cells and in osteoclast precursors treated with the calcineurin inhibitors cyclosporin A and FK506. Together, the gain- and loss-of-function experiments establish that calcineurin Aalpha is necessary for osteoclast formation from its precursor and that this occurs via an NFATc1-dependent mechanism.

The pathogenesis, epidemiology and management of glucocorticoid-induced osteoporosis

Oral glucocorticoids (GCs) are frequently used in the treatment of inflammatory conditions, such as rheumatoid arthritis or asthma. They have adverse skeletal effects, primarily through reductions in bone formation and osteocyte apoptosis. Several findings indicate that changes in the quality of bone may significantly contribute to the increased risk of fracture and that loss of BMD only partially explains the increased risk of fracture in oral GC users. Epidemiological studies have found that the increases in the risk of fracture in oral GC users are dose dependent and occur within three months of starting GC therapy. Daily doses of >2.5 mg prednisone equivalent have been associated with increases in the risk of fractures and randomised studies reported adverse skeletal effects with daily doses as low as 5 mg. After discontinuation of GC treatment, the risk of fracture may reduce towards baseline levels unless patients previously used high cumulative doses of oral GCs. Users of inhaled GCs have also an increased risk of fracture, especially at higher doses. But it is likely that this excess risk is related to the severity of the underlying respiratory disease, rather than to the inhaled GC therapy. It has been recommended that patients who start on oral GC therapy should receive calcium and vitamin D supplementation. Patients with a higher risk of fracture should also receive a bisphosphonate.

Microvascular adaptation to growth in rat humeral head

The aim of this work is to investigate the growth of the vasculature in the rat humeral head cartilage after the initial development of the secondary ossification centre until the adult organization. Rats aging from 5 weeks to 12 months were used. Histological observations on humeral heads were implemented with morphometrical analysis. Subsequently, vascular corrosion cast, that permits a three-dimensional observation of the vasculature, were prepared and observed by scanning electron microscopy. In young animals the epiphysis contains thin bone trabeculae and most of the epiphysis is occupied by bone marrow spaces. With age, the bone trabeculae progressively enlarge up to double their thickness. The percentage of bone tissue increases from 33.6 to 58.6% of the entire epiphysis, while the bone marrow spaces tend to increase very little in their mean dimension. Vascular corrosion casts show that the epiphyseal microcirculation is well distinguished from that of the diaphysis, and arises from the vessels present in the capsule and the periosteal networks. In young animals the only capillaries are bone marrow sinusoids and few subchondral capillaries. In adult animals small vessels run between the clusters of sinusoids forming the trabecular circulation. Capillary sprouts from sinusoids are always observed both in the young and adult animals. Thus, in adult rats different proper microcirculatory districts can be distinguished in the epiphysis: (a) the sinusoidal network, that supplies the hematopoiesis of the bone marrow and the adjacent osteogenic tissue; (b) the bone tissue microcirculation, limited to small vessels that supply the metabolism and the remodelling of the bone tissue. The reported microvascular organization and its adaptation to the epiphyseal growth represent the morphological basis for understanding the reciprocal interaction among the different tissues in developing and adult rat epiphysis.

Fracture risk with intermittent high-dose oral glucocorticoid therapy

OBJECTIVE

To evaluate the risk of fracture in patients receiving intermittent therapy with high-dose oral glucocorticoids (GCs).

METHODS

The study group comprised 191,752 patients from the UK General Practice Database who were 40 years of age and older and received therapy with GCs. The followup time period was divided into the categories of "current" and "no exposure." The daily dose and cumulative dose for each time period were determined. Relative risks were estimated using Cox proportional hazards models, adjusted for age, sex, body mass index, smoking, disease history, and drug history. Fractures of the radius/ulna, humerus, rib, femur/hip, pelvis, or vertebrae were included in the evaluation.

RESULTS

Patients who intermittently received high-dose GCs (daily dose > or =15 mg) and had no or little previous exposure to GCs (cumulative exposure < or =1 gm) had a small increased risk of osteoporotic (but not hip/femur) fracture; this risk increased substantially with increasing cumulative exposure. Among patients who received a daily dose > or =30 mg and whose cumulative exposure was >5 gm, the relative risk (RR) of osteoporotic fracture was 3.63 (95% confidence interval [95% CI] 2.54-5.20), the RR of fracture of the hip/femur was 3.13 (95% CI 1.49-6.59), and the RR of vertebral fracture was 14.42 (95% CI 8.29-25.08).

CONCLUSION

Intermittent use of high-dose oral GCs (daily dose > or =15 mg and cumulative exposure < or =1 gm) may result in a small increased risk of osteoporotic fracture. Conversely, patients who receive several courses of high-dose GCs (daily dose > or =15 mg and cumulative exposure >1 gm) have a substantially increased risk of fracture.