Glucocorticoid-induced osteoporosis: an update on current pharmacotherapy and future directions

Glucocorticoid-induced osteoporosis: an overview with focus on its prevention and management

The widespread use of glucocorticoids (GCs) contributes to the effective management of several diseases and conditions. However, it comes at a price in the case of the bones causing glucocorticoid-induced osteoporosis (GIOP), the most common cause of secondary osteoporosis and fractures. Several scientific societies have issued comprehensive guidelines on the optimal management of patients receiving GCs with the aim of providing answers to three fundamental questions, namely, whom to treat, when to treat, and how to treat. Both common ground and different approaches exist among them. General preventive measures should start along with GC initiation, and the duration of GC therapy should be limited to the minimal effective range. A pre-existing fracture, age, gender, menopausal status, dose, and duration of GC treatment are key factors in the decision to initiate antiosteoporotic medication. Oral bisphosphonates are typically regarded as the first-line treatment choice for GIOP partly due to their cost-effectiveness. Denosumab is another valid option, but an "exit strategy" should be considered before its initiation due to the risk of rebound-associated vertebral fractures upon its discontinuation. Since impaired bone formation represents the main mechanism by which GCs negatively affect skeletal health, osteoanabolic therapies appear to be pathophysiologically the more appropriate and appealing option, although cost considerations currently limit their use to selected severe cases. Regardless of the agent selected to mitigate the impact of GCs on the skeleton, what is most crucial is that the treating physician correctly stratifies the risk and intervenes at the right time.

Bone remodeling serum markers in children with systemic lupus erythematosus

INDRODUCTION

SLE is an autoimmune multisystem disease. Glucocorticoid is an irreplaceable medication for SLE. Glucocorticoid and inflammatory mediators impact bone remodeling by OPG/RANKL/RANK signal system, which could lead to osteoporosis. Our aim is to detect the expression of RANKL/OPG in children with SLE, and to preliminarily explore the changes of bone remodeling serum markers in children with SLE.

METHODS

Serum RANKL and OPG of 40 children with SLE and healthy children were detected by ELISA, while 25(OH)VitD₃ was detected routinely. Clinical data of children with SLE were recorded, including gender, age, height, weight, BMI, SLEDAI, duration of the disease, cumulative dose of glucocorticoid, and correlation analysis was conducted with RANKL, OPG and 25(OH)VitD₃.

RESULTS

Serum RANKL concentrations in SLE group were significantly higher than health group (9.82 ± 7.20 vs. 6.80 ± 4.35 pg/ml and 0.081 ± 0.072 vs. 0.042 ± 0.034, P < 0.05) respectively, and the concentrations of OPG and 25(OH)VitD₃ in serum were significantly lower than health group (156.34 ± 57.33 vs. 189.16 ± 68.70 pg/ml and 43.66 ± 31.27 vs. 59.04 ± 21.56 mmol/L, P < 0.05). Serum RANKL in children with SLE was positively correlated with the duration of SLE, cumulative dose of GC(r = 0.593, 0.727, P < 0.05). And it was negatively correlated with serum OPG and 25(OH)VitD₃ (r = -0.601, -0.469, P < 0.05). In addition, serum OPG and 25(OH)VitD₃ concentrations were inversely correlated with cumulative dose of GC (r = -0.66, -0.508, P < 0.05).

CONCLUSION

Low levels of vitamin D₃ and bone metabolic abnormalities still persist in children with SLE even if the disease is in remission, while serum RANKL level was elevated, OPG expression was reduced. In the case of disease remission, GC is involved in the occurrence and development of abnormal bone remodeling through RANKL/OPG.

The efficiency and safety of alendronate versus teriparatide for treatment glucocorticoid-induced osteoporosis: A meta-analysis and systematic review of randomized controlled trials

Background

Glucocorticoid-induced osteoporosis (GIOP) is the most common secondary osteoporosis, alendronate (ALE) and teriparatide (TPTD) are widely used in the treatment of GIOP. However, which of these two drugs has a better curative effect needs the support of evidence-based medicine.

Methods

We searched PubMed, Embase, Cochrane Library, Web of Science, and Google Scholar for randomized controlled trials of ALE and TPTD in the treatment of glucocorticoid-induced osteoporosis until February 2022. These patients included in the study took glucocorticoid doses greater than 7.5 mg/d for more than 3 months before treatment with ALE and TPTD. The risk ratio (RR) and its 95% confidence interval (CI) are used as the influence index of discontinuous data, and the standardized mean difference (SMD) and its 95% CI are used as the influence index of continuous data.

Results

A total of 4102 patients were enrolled in all 5 studies that met the admission criteria. We found that compared with ALE, TPTD could reduce the rate of new vertebral fracture (RR = 0.13, 95% CI: 0.05–0.34, P<0.00001). TPTD increased LS bone mineral density (BMD) (0.53, 95% CI 0.42–0.64, P<0.00001), TH BMD (0.17, 95% CI 0.05–0.28, P = 0.004) and FN BMD (0.17, 95% CI 0.05–0.29, P = 0.006) compared to ALE. However, there was no significant difference in the incidence of non-vertebral fracture and adverse events between the two groups.

Conclusions

Compared with ALE, TPTD is an effective drug to reduce vertebral fracture risk in patients with GIOP. Furthermore, long-term use of TPTD can increase the bone mineral density of LS, FN, and TH.

Inhibition of Cdk5 Ameliorates Skeletal Bone Loss in Glucocorticoid-Treated Mice

Glucocorticoids (GCs) are widely used to treat inflammatory diseases. However, their long-term use leads to glucocorticoid-induced osteoporosis, increasing morbidity and mortality. Both anabolic and anti-resorptive drugs are used to counteract GC-induced bone loss, however, they are expensive and/or have major side effects. Therefore, identifying new targets for cost-effective, small-molecule inhibitors is essential. We recently identified cyclin-dependent kinase 5 (Cdk5) as a suppressor of osteoblast differentiation and showed that its inhibition with roscovitine promoted osteoblastogenesis, thus improving the skeletal bone mass and fracture healing. Here, we assessed whether Cdk5 knockdown or inhibition could also reverse the GC-mediated suppression of osteoblast differentiation, bone loss, and fracture healing. We first demonstrated that Cdk5 silencing abolished the dexamethasone (Dex)-induced downregulation of alkaline phosphatase (Alp) activity, osteoblast-specific marker gene expression (Runx2, Sp7, Alpl, and Bglap), and mineralization. Similarly, Cdk5 inhibition rescued Dex-induced suppression of Alp activity. We further demonstrated that Cdk5 inhibition reversed prednisolone (Pred)-induced bone loss in mice, due to reduced osteoclastogenesis rather than improved osteoblastogenesis. Moreover, we revealed that Cdk5 inhibition failed to improve Pred-mediated impaired fracture healing. Taken together, we demonstrated that Cdk5 inhibition with roscovitine ameliorated GC-mediated bone loss but did not reverse GC-induced compromised fracture healing in mice.

10-Year Fracture Risk in Postmenopausal Women with Osteopenia and Osteoporosis in South Korea

BACKGROUND

In South Korea, women aged 66 years are eligible for complimentary bone mineral density (BMD) screening via the National Screening Program for Transitional Ages. We aimed to evaluate the 10-year fracture risk in women receiving BMD screening between January 2008 and December 2015.

METHODS

BMD was classified as normal (T-score ≥-1.0 standard deviation [SD]), osteopenia (T-score <-1.0 SD and >-2.5 SD), and osteoporosis (T score ≤-2.5 SD) from dual-energy X-ray absorptiometry. Follow-up continued from the screening date until a diagnosis for clinical fragility fracture (including sites of the vertebrae, hip, pelvis, clavicle, humerus, forearm, wrist, lower leg, and ankle), censored at the earliest date of trauma, death, or December 2017; fracture was ascertained using diagnostic codes from the National Health Insurance Service database. A multivariable Cox proportional hazard model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of fracture in women with osteopenia or osteoporosis relative to women with normal BMD.

RESULTS

Among the 271,197 women screened, 44.0% had osteopenia and 35.2% had osteoporosis. The 10 year cumulative incidence of fragility fractures was 31.1%, 37.5%, and 44.3% in women with normal BMD, osteopenia, and osteoporosis, respectively. Fracture risk was higher in women with osteopenia (HR, 1.31; 95% CI, 1.28 to 1.34) and osteoporosis (HR, 1.68; 95% CI, 1.64 to 1.72) than in women with normal BMD.

CONCLUSION

Women with osteopenia and women with osteoporosis, identified by the national BMD screening program, demonstrated a substantially elevated risk of fracture.

Does treatment with bisphosphonates protect against fractures in real life? The HUNT study, Norway

Bisphosphonates reduce fractures in randomized controlled trials (RCT); however, there is less information from real life. In our population including 14,990 women and 13,239 men, use of bisphosphonates reduced risk of fractures in hip and forearm in women. The magnitude of the effect was comparable to results from RCT.

INTRODUCTION

The objective was to examine if treatment with bisphosphonates (BPs) was associated with reduced risk of fractures in the hip and forearm in women and men in the general population.

METHODS

In a cohort study based on data from the third wave of the population-based HUNT Study (HUNT3), the fracture registry in Nord-Trøndelag, and the Norwegian Prescription Database, 14,990 women and 13,239 men 50-85 years were followed from the date of participating in HUNT3 (2006-2008) until the date of first fracture in the hip or forearm, death, or end of study (31 December 2012). Hazard ratios with 95% confidence intervals for hip and forearm fracture according to use of BPs were estimated using Cox proportional hazards models with time-dependent exposure. Adjustment for individual FRAX® fracture risk assessment scores was included.

RESULTS

BPs, predominantly alendronate, were used by 9.4% of the women and 1.5% of the men. During a median of 5.2 years of follow-up, 265 women and 133 men had a hip fracture, and 662 women and 127 men had a forearm fracture. Compared with non-users of BPs, the hazard ratios with 95% confidence interval for a fracture among users of BPs adjusted for age and FRAX® were 0.67 (0.52-0.86) for women and 1.13 (0.50-2.57) for men. Among users of glucocorticoids, the corresponding figures were 0.35 (0.19-0.66) and 1.16 (0.33-4.09), respectively.

CONCLUSIONS

Use of BPs was associated with reduced risk of fractures in hip and forearm in women, and the magnitude of effect is comparable to results from RCTs.

Sports and Metabolic Bone Disease

Physical activity (PA) increases bone mass and bone strength through different mechanisms and also reduces the risk of falls in the elderly, through proprioception and balance training. The benefits seen in adolescence continue into adulthood. Exercise delays and attenuates the effects of osteoporosis, and particular sports activities may be recommended to improve bone mineral density (BMD) of the spine or regional BMD, improve balance, and prevent falls. Stress injuries related to exercise are more common in osteopenic and osteoporotic individuals.Sports activity may in some cases be detrimental for bone health, with nutrition restriction a frequent cause for negative effects of the practice of PA on bone. The examples are the so-called female athlete triad of menstrual dysfunction resulting in reduced estrogen levels, low energy due to malnutrition, and decreased BMD. A similar triad is described in male athletes. This review analyzes the effects of sport on bone metabolism and in particular its relationship with metabolic bone disease.

Glucocorticoids in rheumatoid arthritis: the silent companion in the therapeutic strategy

INTRODUCTION

Glucocorticoids (GCs) are key actors in RA management, despite the increasing number of available drugs. In fact, due to their efficacy and safety, the combination therapy between GCs and conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) is still recommended in the early phase of RA treatment, because improving the long-term results.

AREAS COVERED

In this paper, we reviewed the role of GCs in RA management, focusing on mechanisms of action as well as the benefit/risk ratio of GCs and newer therapeutic formulations. Furthermore, we analyzed GCs DMARDs proprieties on disease activity and their long-term effects on radiographic damage. We designed a narrative review aimed to provide an overview concerning GCs in RA management.

EXPERT OPINION

A large amount of evidence supports the use of GCs in RA, especially in the earliest phases of the disease. Besides GCs symptomatic effects due to their strong anti-inflammatory effects, data from several randomized clinical trials have shown a substantial benefit of low-dose GCs in inhibiting the radiographic damage, thus highlighting GCs DMARDs properties. Besides their recognized role in the treatment of early RA, systematic monitoring of adverse events should be recommended to minimize GCs toxicity.

Geniposide Alleviates Glucocorticoid-Induced Inhibition of Osteogenic Differentiation in MC3T3-E1 Cells by ERK Pathway

Glucocorticoid (GC) therapy is the leading cause of secondary osteoporosis and the therapeutic and preventative drugs for GC-induced osteoporosis are limited. In this study, we investigated the protective effects of geniposide on dexamethasone (DEX)-induced osteogenic inhibition in MC3T3-E1 cells. The results showed that there was no obvious toxicity on MC3T3-E1 cells when geniposide was used at the doses ranging from 1 to 75 μM. In DEX-treated MC3T3-E1 cells, geniposide promoted the alkaline phosphatase (ALP) activity and the mineralization. In addition, geniposide also significantly increased the mRNA and protein expression of osteopontin (OPN), Runt-related transcription factor 2 (Runx2), and Osterix (Osx) in DEX-treated MC3T3-E1 cells. Furthermore, geniposide activated ERK pathway in DEX-treated MC3T3-E1 cells. The ERK activation inhibitor U0126 and glucagon-like peptide-1 (GLP-1) receptor antagonist exendin 9-39 abolished the geniposide-induced activation of ERK and inhibited the protective effect of geniposide. Taken together, our study revealed that geniposide alleviated GC-induced osteogenic suppression in MC3T3-E1 cells. The effect of geniposide was at least partially associated with activating ERK signaling pathway via GLP-1 receptor. Geniposide might be a potential therapeutic agent for GC-induced osteoporosis.

Sost Haploinsufficiency Provokes Peracute Lethal Cardiac Tamponade without Rescuing the Osteopenia in a Mouse Model of Excess Glucocorticoids

Glucocorticoid-induced secondary osteoporosis is the most predictable side effect of this anti-inflammatory. One of the main mechanisms by which glucocorticoids achieve such deleterious outcome in bone is by antagonizing Wnt/β-catenin signaling. Sclerostin, encoded by Sost gene, is the main negative regulator of the proformative and antiresorptive role of the Wnt signaling pathway in the skeleton. It was hypothesized that the partial inactivation of sclerostin function by genetic manipulation will rescue the osteopenia induced by high endogenous glucocorticoid levels. Sost-deficient mice were crossed with an established mouse model of excess glucocorticoids, and the effects on bone mass and structure were evaluated. Sost haploinsufficiency did not rescue the low bone mass induced by high glucocorticoids. Intriguingly, the critical manifestation of Sost deficiency combined with glucocorticoid excess was sporadic, sudden, unprovoked, and nonconvulsive death. Detailed histopathologic analysis in a wide range of tissues identified peracute hemopericardium and cardiac tamponade to be the cause. These preclinical studies reveal outcomes with direct relevance to ongoing clinical trials that explore the use of antisclerostin antibodies as a treatment for osteoporosis. They particularly highlight a potential for increased cardiovascular risk and may inform improved stratification of patients who might otherwise benefit from antisclerostin antibody treatment.

Anti-osteoporosis drug use: too little, too much, or just right? The HUNT study, Norway

Use of anti-osteoporotic drugs (AODs) was examined in a Norwegian population 50-85 years. Among them with Fracture Risk Assessment Tool (FRAX) score for major osteoporotic fracture ≥ 20, 25% of the women and 17% of the men received AODs. The strongest predictors for AODs were high age in women and use of glucocorticoids among men.

INTRODUCTION

To examine the use of anti-osteoporotic drugs (AODs) and to identify predictors for prescriptions.

METHODS

Data were obtained from the Nord-Trøndelag Health Study (HUNT3) performed in 2006-2008 and the Norwegian Prescription Database, including 15,075 women and 13,386 men aged 50-85 years. Bone mineral density (BMD) in the femoral neck was measured in a subgroup of 4538 women and 2322 men. High fracture risk was defined as a FRAX score for major osteoporotic fracture (MOF) ≥ 20%; in the subgroup with BMD, high risk was in addition defined as FRAX_MOF ≥ 20% or T-score ≤ - 2.5. Hazard ratios (HRs) for predictors of incident use of AODs within 2 years after HUNT3 were estimated by Cox' proportional hazards model.

RESULTS

Among individuals with FRAX MOF ≥ 20%, 25% of the women and 17% of the men were treated with AODs. Among those with FRAX MOF < 20%, 3% and 1% were treated, respectively. In the subgroup with BMD measurement, 24% of the women and 16% of the men at high risk of fractures were treated, compared to 3 and 1% in women and men not fulfilling the criteria. In women, high age was the strongest predictor for treatment (HR 3.84: 95% confidence interval 2.81-5.24), followed by use of glucocorticoids (GCs) (2.68:1.84-3.89). In men, predictors were use of GCs (5.28: 2.70-10.35) followed by multimorbidity (3.16:1.31-7.63). In the subgroup with BMD, T-score ≤ - 2.5 was the strongest predictor (women 3.98:2.67-5.89; men 13.31:6.17-28.74).

CONCLUSIONS

This study suggests an undertreatment of AODs in individuals at high risk of fracture.

Proficiencies of Zingiber officinale against spine curve and vertebral damage induced by corticosteroid therapy associated with gonadal hormone deficiency in a rat model of osteoporosis

This study was assessed to examine whether Zingiber officinale (ZO) can prevent spine disorder and trabecular microarchitecture disruption in osteoporotic murin model. Three groups of male rats were selected: Controls (CTRL), combined model of osteoporosis (CMO), in which rats were orchidectomized and treated with cortisol, and CMO treated with ZO (CMO + ZO). One month after the surgical procedures, the rats were sacrificed. Lumbar curve of the spine has been evaluated using the kyphotic method. The spines were submitted to histological and histomorphometric analysis and mineral (calcium and phosphorus) metabolism assessment. Compared to CTRL, the mean kyphotic angle (KA) was significantly higher in CMO rats. The spinal deconditioning associated decreased bone trabecular volume and a disrupted microarchitecture. A disorder was observed in the serum and bone levels of calcium and phosphorus in the combined severe osteopenia model. An increase in the level of TRAcP associated with an increase in osteoclast number and activity has been reported. These disturbances were reduced following the use of ZO in the CMO + ZO group. Finally, ginger might be an alternative therapeutic candidate for the treatment of severe osteopenia induced vertebral damage and spine curve disruption.

WNT16 overexpression partly protects against glucocorticoid-induced bone loss

Therapeutic use of glucocorticoids (GCs) is a major cause of secondary osteoporosis, but the molecular mechanisms responsible for the deleterious effects of GCs in bone are only partially understood. WNT16 is a crucial physiological regulator of bone mass and fracture susceptibility, and we hypothesize that disturbed WNT16 activity might be involved in the deleterious effects of GC in bone. Twelve-week-old female Obl-Wnt16 mice (WNT16 expression driven by the rat procollagen type I α1 promoter) and wild-type (WT) littermates were treated with prednisolone (7.6 mg·kg^-1·day^-1) or vehicle for 4 wk. We first observed that GC treatment decreased the Wnt16 mRNA levels in bone of female mice (-56.4 ± 6.1% compared with vehicle, P < 0.001). We next evaluated if WNT16 overexpression protects against GC-induced bone loss. Dual-energy X-ray absorptiometry analyses revealed that GC treatment decreased total body bone mineral density in WT mice (-3.9 ± 1.2%, P = 0.028) but not in Obl-Wnt16 mice (+1.3 ± 1.4%, nonsignificant). Microcomputed tomography analyses showed that GC treatment decreased trabecular bone volume fraction (BV/TV) of the femur in WT mice ( P = 0.019) but not in Obl-Wnt16 mice. Serum levels of the bone formation marker procollagen type I N-terminal propeptide were substantially reduced by GC treatment in WT mice (-50.3 ± 7.0%, P = 0.008) but not in Obl-Wnt16 mice (-3.8 ± 21.2%, nonsignificant). However, the cortical bone thickness in femur was reduced by GC treatment in both WT mice and Obl-Wnt16 mice. In conclusion, GC treatment decreases Wnt16 mRNA levels in bone and WNT16 overexpression partly protects against GC-induced bone loss.

Glucocorticoids, Inflammation and Bone

The current review on glucocorticoids (GCs), inflammation and bone is focused on three aspects: (1) the mutual effects between GCs, inflammation and bone in inflammatory rheumatic diseases, (2) current views on fracture risk assessment in patients using GCs and (3) non-pharmacological and pharmacological treatment to prevent fractures in GC-using patients with inflammatory rheumatic diseases. The use of GCs results in increased risk for fractures due to both direct and indirect negative effects of GCs on bone mass, and on bone and muscle strength. However, also the underlying inflammatory rheumatic disease is associated with the increased bone loss and fracture risk due to the chronic inflammation itself, and due to disability/immobility caused by active disease or joint destruction. The rapid and strong anti-inflammatory effect of GCs in patients with rheumatoid arthritis seems to balance the negative effects of GCs on bone in the early, active phase of the disease. Recently, an update of the American College of Rheumatology guidelines for prevention and treatment of GC-induced osteoporosis was published with renewed recommendations. To prevent fractures, general measures, including treatment of the underlying inflammatory disease adequately (even with GCs when indicated), a healthy lifestyle, including adequate calcium and vitamin D supplementation, and regular weight bearing exercises are important. In rheumatic patients with high fracture risk using GCs, especially when the cumulative dose is high and/or the underlying inflammatory disease is active, treatment with anti-osteoporotic drugs, usually an oral bisphosphonate, is indicated.

Dexamethasone-induced production of reactive oxygen species promotes apoptosis via endoplasmic reticulum stress and autophagy in MC3T3-E1 cells

Apoptosis of osteoblasts, triggered by prolonged or excessive use of glucocorticoids (GCs), has been identified as a dominant contributor to the development of osteoporosis and osteonecrosis. However, the molecular mechanisms underlying GC‑induced apoptosis are multifaceted and remain to be fully elucidated. The present study aimed to explore the correlation between dexamethasone (DEX)‑induced reactive oxygen species (ROS), autophagy and apoptosis in MC3T3‑E1 osteoblast‑like cells. Cell viability was assessed using a Cell Counting Kit‑8 assay, and flow cytometry was performed to assess cellular apoptosis, cell cycle and ROS production. Immunofluorescence and western blot analysis were respectively used to detect autophagic vacuoles and the expression of proteins, including cyclin D kinase (CDK)2, poly[ADP ribose] polymerase, caspase‑3, activating transcription factor (ATF)4, CCAAT/enhancer‑binding protein homologous protein (CHOP), Beclin1, microtubule‑associated proteins 1A/1B light chain (LC)3B and P62. It was revealed that DEX not only reduced cell viability, but also promoted apoptosis via the activation of endoplasmic reticulum (ER) stress. In addition, DEX induced cell cycle arrest at G0/G1 phase via inhibition of the expression of CDK2, and the production of ROS was activated. Of note, the DEX‑mediated changes in viability and apoptosis were attenuated in MC3T3‑E1 cells after treatment with 3‑methyladenine, which is an autophagy inhibitor. Treatment with the antioxidant N‑acetylcysteine abolished the effect of DEX on the proliferation, apoptosis, ER stress and autophagy of MC3T3‑E1 cells. In conclusion, the present results indicated that DEX promoted the production of ROS, which enhanced apoptosis through activation of autophagy and ER stress in MC3T3-E1 cells.

Adenosine Receptor Stimulation Improves Glucocorticoid-Induced Osteoporosis in a Rat Model

Glucocorticoid-induced osteoporosis (GIO) is a secondary cause of bone loss. Bisphosphonates approved for GIO, might induce jaw osteonecrosis; thus additional therapeutics are required. Adenosine receptor agonists are positive regulators of bone remodeling, thus the efficacy of adenosine receptor stimulation for treating GIO was tested. In a preventive study GIO was induced in Sprague-Dawley rats by methylprednisolone (MP) for 60 days. Animals were randomly assigned to receive polydeoxyribonucleotide (PDRN), an adenosine A2 receptor agonist, or PDRN and DMPX (3,7-dimethyl-1-propargylxanthine, an A₂ antagonist), or vehicle (0.9% NaCl). Another set of animals was used for a treatment study, following the 60 days of MP-induction rats were randomized to receive (for additional 60 days) PDRN, or PDRN and DMPX (an adenosine A2 receptor antagonist), or zoledronate (as control for gold standard treatment), or vehicle. Control animals were administered with vehicle for either 60 or 120 days. Femurs were analyzed after treatments for histology, imaging, and breaking strength analysis. MP treatment induced severe bone loss, the concomitant use of PDRN prevented the developing of osteoporosis. In rats treated for 120 days, PDRN restored bone architecture and bone strength; increased b-ALP, osteocalcin, osteoprotegerin and stimulated the Wnt canonical and non-canonical pathway. Zoledronate reduced bone resorption and ameliorated the histological features, without significant effects on bone formation. Our results suggest that adenosine receptor stimulation might be useful for preventing and treating GIO.

E-selectin-targeted Sialic Acid-PEG-dexamethasone Micelles for Enhanced Anti-Inflammatory Efficacy for Acute Kidney Injury

The effective treatment for acute kidney injury (AKI) is currently limited, and care is primarily supportive. Sialic acid (SA) is main component of Sialyl Lewisx antigen on the mammalian cell surface, which participates in E-selectin binding. Therefore, dexamethasone(DXM)-loaded E-selectin-targeting sialic acid-polyethylene glycol-dexamethasone (SA-PEG-DXM/DXM) conjugate micelles are designed for ameliorating AKI. The conjugates are synthesized via the esterification reaction between PEG and SA or DXM, and can spontaneously form micelles in an aqueous solution with a 65.6 µg/mL critical micelle concentration. Free DXM is incorporated into the micelles with 6.28 ± 0.21% drug loading content. In vitro DXM release from SA-PEG-DXM/DXM micelles can be prolonged to 48h. Much more SA-PEG-DXM micelles can be internalized by lipopolysaccharide (LPS)-activated human umbilical vein endothelial cells (HUVECs) in comparison to PEG-DXM micelles due to specific interaction between SA and E-selectin expressed on HUVECs, and consequently more SA-PEG-DXM micelles are accumulated in the kidney of AKI murine model. Furthermore, SA in SA-PEG-DXM conjugates can significantly ameliorate LPS-induced production of pro-inflammatory cytokines via suppressing LPS-activated Beclin-1/Atg5-Atg12-mediated autophagy to attenuate toxicity. Compared with free DXM and PEG-DXM/DXM micelles, SA-PEG-DXM/DXM micelles show better therapeutical effects, as reflected by the improved renal function, histopathological changes, pro-inflammatory cytokines, oxidative stress and expression of apoptotic related proteins.

Bone loss at the distal femur and proximal tibia in persons with spinal cord injury: imaging approaches, risk of fracture, and potential treatment options

Persons with spinal cord injury (SCI) undergo immediate unloading of the skeleton and, as a result, have severe bone loss below the level of lesion associated with increased risk of long-bone fractures. The pattern of bone loss in individuals with SCI differs from other forms of secondary osteoporosis because the skeleton above the level of lesion remains unaffected, while marked bone loss occurs in the regions of neurological impairment. Striking demineralization of the trabecular epiphyses of the distal femur (supracondylar) and proximal tibia occurs, with the knee region being highly vulnerable to fracture because many accidents occur while sitting in a wheelchair, making the knee region the first point of contact to any applied force. To quantify bone mineral density (BMD) at the knee, dual energy x-ray absorptiometry (DXA) and/or computed tomography (CT) bone densitometry are routinely employed in the clinical and research settings. A detailed review of imaging methods to acquire and quantify BMD at the distal femur and proximal tibia has not been performed to date but, if available, would serve as a reference for clinicians and researchers. This article will discuss the risk of fracture at the knee in persons with SCI, imaging methods to acquire and quantify BMD at the distal femur and proximal tibia, and treatment options available for prophylaxis against or reversal of osteoporosis in individuals with SCI.

MR spectroscopy for assessing the effects of oxytocin on marrow adipogenesis induced by glucocorticoid in rabbits

BACKGROUND

Previous studies suggest that oxytocin (OT) negatively modulates adipogenesis while promoting osteogenesis in vitro. Because of its effects on marrow stromal cells, OT might have potential utility in therapy for glucocorticoid-induced osteoporosis (GIO).

PURPOSE

To explore the effects of OT on marrow adipogenesis in a rabbit model of GIO.

MATERIAL AND METHODS

Thirty-six-month-old female New Zealand rabbits were randomly assigned to the control, GIO, and GIO + OT groups. Magnetic resonance (MR) spectroscopy and multi-detector computed tomography (MDCT) were performed to detect marrow fat content (MFC) and bone mineral density (BMD) at baseline, and 1, 2, and 3 months. After 3 months of treatment, marrow adipocytes were quantitatively evaluated by histopathology.

RESULTS

In the GIO group, MFC substantially increased from 34.1% to 43.2% at month 1, and it was maintained until month 3 (by 59.2%, all P <0.01). MFC values in the GIO group were significantly different from the control and OT-treated groups over time. Early OT treatment reversed marrow adiposity to levels of the controls. BMD values were significantly lower in the GIO group at months 2 and 3 compared to the controls; however, partial recovery of vertebral BMD (87.1% of baseline) and femoral BMD (89.3% of baseline) in the OT-treated group were observed. The mean diameter and density of adipocyte and percentage of adipocyte area increased by 30.0%, 70.1%, and 88.9%, respectively (all P <0.05) in the GIO group, but remained unchanged in the OT-treated group.

CONCLUSION

Early OT treatment was sufficient to eliminate glucocorticoid-induced marrow adiposity.

High Prevalence of Low Bone Mineral Density and Substantial Bone Loss over 4 Years Among HIV-Infected Persons in the Era of Modern Antiretroviral Therapy

HIV-infected persons are living longer on combination antiretroviral therapy (cART) but experiencing more comorbidities including low bone mineral density (BMD). Using data from the Study to Understand the Natural History of HIV and AIDS in the Era of Effective Therapy (SUN Study), we determined the prevalence of low BMD (T-score below one standard deviation of the reference mean) and compared it with matched controls from the National Health and Nutrition Examination Survey (NHANES). We also assessed 4-year longitudinal BMD changes among participants virologically suppressed on cART. Of 653 participants included in this analysis (77% male, 29% black, median age 41 years, median CD4(+) cell count 464 cells/mm(3), 89% with HIV RNA <400 copies/ml), 51% and 10% had baseline osteopenia and osteoporosis, respectively. Low BMD at the femoral neck was significantly more prevalent than for the NHANES controls (47% versus 29%, p<0.001). Lower body mass index, nonwhite race, longer tenofovir exposure, older age, being unemployed or retired, and lower apolipoprotein E were independently associated with baseline osteoporosis. Among 170 participants virologically suppressed on cART and with longitudinal BMD data, 31% experienced substantial bone loss (≥5% BMD decline from baseline) over 4 years. Female sex, current smoking, and longer stavudine use were more common among participants who had substantial bone loss, although these variables failed to reach statistical significance. Low BMD was highly prevalent among HIV-infected persons. One-third of participants experienced substantial bone loss despite cART, suggesting the need for monitoring and potential clinical interventions.

The identification of nuclear receptors associated with hepatic steatosis to develop and extend adverse outcome pathways

The development of adverse outcome pathways (AOPs) is becoming a key component of twenty-first century toxicology. AOPs provide a conceptual framework that links the molecular initiating event to an adverse outcome through organized toxicological knowledge, bridging the gap from chemistry to toxicological effect. As nuclear receptors (NRs) play essential roles for many physiological processes within the body, they are used regularly as drug targets for therapies to treat many diseases including diabetes, cancer and neurodegenerative diseases. Due to the heightened development of NR ligands, there is increased need for the identification of related AOPs to facilitate their risk assessment. Many NR ligands have been linked specifically to steatosis. This article reviews and summarizes the role of NR and their importance with links between NR examined to identify plausible putative AOPs. The following NRs are shown to induce hepatic steatosis upon ligand binding: aryl hydrocarbon receptor, constitutive androstane receptor, oestrogen receptor, glucocorticoid receptor, farnesoid X receptor, liver X receptor, peroxisome proliferator-activated receptor, pregnane X receptor and the retinoic acid receptor. A preliminary, putative AOP was formed for NR binding linked to hepatic steatosis as the adverse outcome.

Poor bone health at the end of puberty in childhood cancer survivors

BACKGROUND

Although the survival rate following childhood cancer is >80%, late effects are a major concern. We aimed to determine the clinical factors affecting bone health after puberty in childhood cancer survivors at risk for low bone mineral density (BMD).

PROCEDURES

We performed dual-energy X-ray absorptiometry at the lumbar spine, femoral neck, and total hip regions for survivors with the following bone densitometry indications (BDIXs): brain or nasopharyngeal cancer, head or neck area radiotherapy, or corticosteroid treatment (N = 92). Additionally, we evaluated 16 survivors without these BDIXs but with other clinical factors that could affect bone health. We assessed the effects of these factors on BMD using univariate and logistic regression analyses. Moderate BMD deficit was defined as a Z-score of <-1.0 and ≥-2.0, and severe BMD deficit was defined as <-2.0.

RESULTS

Severe BMD deficits were found in 18 survivors (16.7%) and moderate BMD deficits were in 39 (36.1%) in at least one bone region. BMD deficits tended to increase as the number of BDIXs increased (P < 0.010). There were no severe BMD deficits in survivors without BDIXs. The duration since cancer treatment completion was correlated with higher BMD (P < 0.05). Endocrine dysfunction was a significant risk factor for decreased BMD in univariate and multivariate analyses (P < 0.05 for both).

CONCLUSIONS

Decreased BMD was prevalent in our study cohort. Endocrine dysfunction was found to be a significant risk factor, and it should be managed in survivors to ensure future bone health.

Use of anti-osteoporotic drugs in central Norway after a forearm fracture

Use of anti-osteoporotic drugs (AOD) the first year after a forearm fracture in central Norway was low in the period 2005-2012. Women with fractures used more AOD compared to the general population only in 2006, 2007, and 2011. Female gender, age ≥ 60 years, use of glucocorticosteroids, or ≥ 4 different drugs were associated with AOD use.

PURPOSE

The primary aim of this study was to examine time trends in prevalence and incidence of AOD use the first year after a forearm fracture from 2005-2012. Further, secondary aims were to investigate if gender, the number of drugs used before fracture, or use of glucocorticoids influenced the prescription of AOD, and to examine adherence to AOD.

METHODS

Data is from the fracture registry in Nord-Trøndelag and the Norwegian Prescription database, including women (N = 1434) and men (N = 513) 40-84 years with their first forearm fracture between 2005 and 2012. AOD were defined as bisphosphonates, teriparatide, denosumab, and raloxifene. Prevalence and incidence were calculated, and prevalent use among women with forearm fracture was compared with the population in Nord-Trøndelag and Norway. Age-adjusted Poisson regression analyses for time trends and odds ratio for treatment with AOD was estimated. Adherence was defined as medication possession ratio ≥ 80 %.

RESULTS

The first year after the fracture, 11.2 % of the women and 2.7 % of the men were prevalent users, while 5.1 % and 1.2 %, respectively, were incident users of AOD. Bisphosphonates comprised 98.8 %. AOD use among women with fractures was significantly higher compared to the general population in Nord-Trøndelag only in 2006, 2007, and 2011. There was a trend towards a decline in AOD use among women with fractures from 2005 to 2012 (coefficient -0.05, p = 0.15). Female gender, age ≥ 60 years, use of glucocorticosteroids, or ≥ 4 different drugs the last year before fracture were associated with AOD use. In women, 54.8 % were adherent during 3 years after fracture.

CONCLUSIONS

The use of AOD after a forearm fracture was low. An increased focus on osteoporosis in fracture patients is needed for secondary fracture prevention.

Bisphosphonates and glucocorticoid-induced osteoporosis: cons

During the use of glucocorticoids (GCs), both vertebral and nonvertebral fracture risk are increased, due to the direct and indirect negative effects of GCs on bone, muscles, and the activity of the underlying inflammatory diseases. Inhibition of bone formation and increased apoptosis of osteocytes play a consistent and crucial role in the pathogenesis of glucocorticoid-induced osteoporosis (GIO), while changes in bone resorption during GC-use are variable. To prevent fractures, important general measures include using the lowest possible dose of GCs, treating the underlying disease adequately, a healthy life style, adequate calcium and vitamin D supplementation, and regular exercise. Although it has been shown that bisphosphonates reduce vertebral fractures during the first 2 years of GC-treatment, there are no data on long-term use of bisphosphonates during GC-treatment. Of some concern in GIO, bisphosphonates reduce bone turnover, including bone formation, which is already downregulated by GCs. In contrast, the use of the anabolic agent teriparatide is more effective in reducing vertebral fractures than alendronate. In summary, bisphosphonates remain the first choice in the first two years of treatment in GC-treated patients with high fracture risk, but their long-term effects on bone quality and fracture risk reduction remain uncertain.

Management of glucocorticoid-induced osteoporosis: clinical data in relation to disease demographics, bone mineral density and fracture risk

INTRODUCTION

Glucocorticoid-induced osteoporosis (GIOP) is the most common type of secondary osteoporosis. Patient selection and the treatment choice remain to be controversial. None of the proposed management guidelines are widely accepted. We evaluate the available clinical data, the efficacy of current medication and we propose an overall algorithm for managing GIOP.

AREAS COVERED

This article provides a critical review of in vivo and clinical evidence regarding GIOP and developing evidence-based algorithm of treatment. Data base used includes MEDLINE® (1950 to May 2014).

EXPERT OPINION

Patient-specific treatment is the gold standard of care. Glucocorticoid (GC)-treated patients must comply with a healthy lifestyle and receive 1000 mg of calcium and at least 800 mg of Vitamin D daily. Bisphosphonate (BP) therapy is the current standard of care for prevention and treatment of GIOP. Most of bisphosphonates demonstrated benefit in lumbar bone mineral density (BMD) and some in hip BMD. Alendronate, risedronate and zoledronate showed vertebral anti-fracture efficacy in postmenopausal women and men. Scarce data however when compared head to head with BP efficacy. In post-menopausal women, early antiresorptive BP treatment appears to be efficient and safe. In premenopausal women and patients at high risk of fracture receiving long-term GC therapy however, teriparitide may be advised alternatively.

Systemic glucocorticoids: important issues and practical guidelines for the dermatologist

BACKGROUND

The potent anti-inflammatory and immunosuppressive effects of systemic glucocorticoids have led to their wide use in the treatment of dermatologic diseases. However, glucocorticoids have been designated the "archetypal double-edged sword of medicine" as a result of their various potential adverse side effects. Dermatologists face major challenges in their usage and require knowledge of both the risks related to their usage and strategies with which to manage them.

OBJECTIVES

This brief review includes an evidence-based, strategic approach to the general risk management of systemic glucocorticoids with a focus on preventing glucocorticoid-induced osteoporosis (GIOP).

METHODS

We assess which classes of corticosteroid are most likely to provoke allergic cross-reactions and outline the mechanism for glucocorticoid resistance. We examine how glucocorticoids both help and impair normal physiology.

RESULTS

Five reactivity groups are defined, based on the structural and clinical characteristics of glucocorticoids. Tests for allergy reactions and mechanisms for glucocorticoid resistance are described. Guidelines for the prevention and treatment of GIOP are introduced.

CONCLUSION

Glucocorticoids play an important teleologic role in maintaining blood glucose levels adequate for brain function by inducing a catabolic state through the production of carbohydrates at the expense of proteins and fat stores. It is hoped that the various recommendations for the protection of patients treated with systemic glucocorticoids will provide physicians with practical guidelines for prescribing.

Intermittent administration of teriparatide enhances graft bone healing and accelerates spinal fusion in rats with glucocorticoid-induced osteoporosis

BACKGROUND CONTEXT

There has been no study regarding the effect of intermittent administration of teriparatide (TPTD [recombinant human parathyroid hormone (1-34)]) on spinal fusion in patients with glucocorticoid-induced osteoporosis (GIOP).

PURPOSE

To elucidate the effect of intermittent administration of TPTD on spinal fusion in rats with GIOP.

STUDY DESIGN

An experimental animal study of rats under continuous glucocorticoid (GC) exposure undergoing spinal fusion surgery and administration of TPTD or saline.

METHODS

Male 8-week-old rats (n=18) were administered 5 mg/kg methylprednisolone (MP) for 12 weeks. After 6 weeks of MP administration, the rats underwent posterolateral spinal fusion (L4-L5) with iliac crest autograft. Then, five times a week, they were given either saline or 40 μg/kg TPTD for 6 weeks. The following assessments were performed: time-course bone microstructural analysis of the fusion mass and adjacent vertebrae (L6), with in vivo microcomputed tomography (μCT); fusion assessment, with manual palpation testing and three-dimensional CT images; and bone histomorphometrical analysis of the fusion mass.

RESULTS

In the TPTD group, values for bone volume and other bone microstructural parameters at the fusion mass increased and peaked 4 weeks after surgery, and these values were significantly greater than those for the control (CNT) group at 4 and 6 weeks after surgery. Fusion assessment showed that fusion rate was higher in the TPTD group than in the CNT group (CNT group: 56%, TPTD group: 89%). Bone histomorphometry revealed that values for bone formation parameters were significantly higher in the TPTD group than in the CNT group.

CONCLUSIONS

Under continuous GC exposure in a rat model of spinal fusion, intermittent TPTD administration accelerated bone modeling and remodeling predominantly by stimulating bone formation at the fusion mass and increasing the fusion rate. Intermittent TPTD administration also improved bone microarchitecture of adjacent vertebrae.

Glucocorticoids in early rheumatoid arthritis: are the benefits of joint-sparing effects offset by the adverse effect of osteoporosis? the effects on bone in the utrecht study and the CAMERA-II study

This paper reviews the clinical effects on bone of 10 mg of prednisone daily in early rheumatoid arthritis, given for 2 years in the Utrecht Study and in the second CAMERA (Computer- Assisted Management in Early Rheumatoid Arthritis) Study, and addresses the question whether there were joint-sparing effects and whether these were offset by adverse effects, especially osteoporosis. We conclude that a 2-year adjunct treatment with 10 mg of prednisone daily increases the benefits of disease-modifying antirheumatic drug therapy and has joint-sparing properties, even if added to the tight control methotrexate-based strategy aiming for remission. Importantly, with good control of inflammation and adequate use of calcium, vitamin D and bisphosphonates - according to national or international guidelines - steroid-induced osteoporosis is rare over 2 years.

Denosumab improves bone mineral density and microarchitecture and reduces bone pain in women with osteoporosis with and without glucocorticoid treatment

Osteoporosis is a key health problem in postmenopausal women with high social and economic impact. Decreased bone mineral density (BMD) and deterioration of bone microarchitecture may occur also as a result of long-term glucocorticoid treatment (GCT) of autoimmune or inflammatory conditions. Denosumab specifically inhibits the binding of the receptor activator of nuclear factor-κB to its ligand, thus preventing osteoclast activation and bone resorption. The efficacy and safety of denosumab, administered subcutaneously as 60 mg, once every six months for 12 months, were evaluated in 60 patients with postmenopausal osteoporosis (PMO) divided into two groups. The GCT group included 30 patients receiving concomitant glucocorticoid therapy and the non-GCT group included 30 patients that did not receive GCT. In the non-GCT group, the 12-month treatment with denosumab resulted in BMD increase of 6.1% and 2.8% in lumbar spine and hip, respectively. T-score increased by 13.1% and 5.6% in both, the lumbar spine and hip. A slight rise in the Trabecular Bone Score (TBS) of 0.3% was observed. Bone pain was markedly reduced by 56.2%. In the GCT group, denosumab therapy increased BMD with 5.8% and 2.3% in lumbar spine and hip, respectively. T-score of lumbar spine and hip significantly increased by 14.0% and 4.4%, and the TBS rose by 5%. Bone pain was reduced by 53.6%. These data confirm the available knowledge on denosumab efficacy and safety in women with PMO and also provide new insights into its therapeutic potential in patients with osteoporosis related to a long-term corticosteroid treatment.

Study description and baseline characteristics of the population enrolled in a multinational observational study of extended teriparatide use (ExFOS)

OBJECTIVE

To better characterize patients who are currently being prescribed teriparatide in Europe, this article describes the study design and baseline characteristics of participants of the Extended Forsteo * Observational Study (ExFOS).

RESEARCH DESIGN AND METHODS

ExFOS is a noninterventional, multicenter, prospective, observational study in men and women with osteoporosis treated with teriparatide during the course of normal clinical practice for up to 24 months and with a post-treatment follow-up of at least 18 months.

MAIN OUTCOME MEASURES

Baseline characteristics, including history of fracture and back pain, and health-related quality of life (HRQoL, assessed using the EuroQol-5 Dimension [EQ-5D]).

RESULTS

Of 1607 patients enrolled, 90.9% were women. At baseline, mean (standard deviation [SD]) age was 70.3 (9.8) years, and 85.8% of patients had a history of fracture (64.7% with ≥2 fragility fractures). Of those with historic fractures, 90.8% had vertebral fractures (67.8% had thoracic fractures). The mean (SD) of reported bone mineral density T-scores were -3.0 (1.2), -2.4 (1.0), and -2.5 (0.9) for lumbar spine, total hip (left), and femoral neck (left), respectively. Overall, 39.3% of patients had experienced ≥1 fall during the 12 months before enrollment. At baseline, 11.4% of patients were osteoporosis-treatment naïve and 15% were currently using glucocorticoids. The mean (SD) visual analog scale score for back pain during the last month was 50.7 (26.9), and 62.1% of patients experienced daily or almost daily back pain. The median EQ-5D health state value at baseline was 0.62 (first and third quartiles: 0.19, 0.74).

CONCLUSIONS

Baseline characteristics of the ExFOS study cohort indicate that patients prescribed teriparatide in Europe have severe osteoporosis with highly prevalent vertebral fractures, frequent and disabling back pain, and a poor HRQoL, despite previous pharmacotherapy for osteoporosis. Limitations include non-randomization, lack of a comparator group, and patient self-report for data on prior medication and fracture history.

Estimating prevalence of osteoporosis: examples from industrialized countries

In nine industrialized countries in North America, Europe, Japan, and Australia, country-specific osteoporosis prevalence (estimated from published data) at the total hip or hip/spine ranged from 9 to 38 % for women and 1 to 8 % for men. In these countries, osteoporosis affects up to 49 million individuals.

PURPOSE

Standardized country-specific prevalence estimates are scarce, limiting our ability to anticipate the potential global impact of osteoporosis. This study estimated the prevalence of osteoporosis in several industrialized countries (USA, Canada, five European countries, Australia, and Japan) using the World Health Organization (WHO) bone mineral density (BMD)-based definition of osteoporosis: BMD T-score assessed by dual-energy x-ray absorptiometry ≤-2.5.

METHODS

Osteoporosis prevalence was estimated for males and females aged 50 years and above using total hip BMD and then either total hip or spine BMD. We compiled published location-specific data, using the National Health and Nutrition Examination Survey (NHANES) III age and BMD reference groups, and adjusted for differences in disease definitions across sources. Relevant NHANES III ratios (e.g., male to female osteoporosis at the total hip) were applied where data were missing for countries outside the USA. Data were extrapolated from geographically similar countries as needed. Population counts for 2010 were used to estimate the number of individuals with osteoporosis in each country.

RESULTS

For females, osteoporosis prevalence ranged from 9 % (UK) to 15 % (France and Germany) based on total hip BMD and from 16 % (USA) to 38 % (Japan) when spine BMD data were included. For males, prevalence ranged from 1 % (UK) to 4 % (Japan) based on total hip BMD and from 3 % (Canada) to 8 % (France, Germany, Italy, and Spain) when spine BMD data were included.

CONCLUSIONS

Up to 49 million individuals met the WHO osteoporosis criteria in a number of industrialized countries in North America, Europe, Japan, and Australia.

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

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

The temporal characterization of marrow lipids and adipocytes in a rabbit model of glucocorticoid-induced osteoporosis

OBJECTIVE

To characterize the temporal changes in marrow lipids content and adipocytes in the development of glucocorticoid-induced osteoporosis (GIOP) in rabbits using MR spectroscopy.

SUBJECTS AND METHODS

Twenty 20-week-old female rabbits were randomized to a control group and a GIOP group equally. Marrow lipids fraction and bone mineral density at the left proximal femur and L3-L4 vertebrae were measured by MR spectroscopy and dual-energy X-ray absorptiometry at week 0, 4, 8, and 12. Marrow adipocytes were quantitatively evaluated by histopathology.

RESULTS

Marrow adiposity in the GIOP group showed a significant increase over time, with a variation of marrow lipids fraction (+35.9 %) at week 4 from baseline and it was maintained until week 12 (+75.2 %, p < 0.001 for all). The GIOP group demonstrated continuous deterioration of bone with significant difference between the two groups at week 8, followed by increased marrow fat with significant difference at week 4 (p < 0.05 for all). In comparison with the controls, marrow adipocyte density in the GIOP group increased by 57.1 % at week 8 and 35.4 % at week 12, respectively. A reduction (-13.3 %) in adipocyte mean diameter at week 8 (but an increase (+22.7 %) at week 12) were observed in the GIOP group compared with the control group (p < 0.05 for all). There was significant difference between two periods (p = 0.023) in adipocyte mean diameter in the GIOP group. The percentage area of marrow adipocytes in the GIOP group was 62.8 ± 8.7 % at week 8 and 79.2 ± 7.7 % at week 12, both of which were significantly higher than those of the controls (p < 0.05 for all).

CONCLUSIONS

Marrow adipogenesis is synchronized with bone loss in the development of GIOP, which was characterized by a significant increase in the number of small-sized marrow adipocytes in the relatively early stage and concomitant volume increase later on. MR spectroscopy appears to be the most powerful tool for detecting the sequential changes in marrow lipid content.

Glucocorticoid receptor signaling in health and disease

Glucocorticoids are steroid hormones regulated in a circadian and stress-associated manner to maintain various metabolic and homeostatic functions that are necessary for life. Synthetic glucocorticoids are widely prescribed drugs for many conditions including asthma, chronic obstructive pulmonary disease (COPD), and inflammatory disorders of the eye. Research in the past few years has begun to unravel the profound complexity of glucocorticoid signaling and has contributed remarkably to improved therapeutic strategies. Glucocorticoids signal through the glucocorticoid receptor (GR), a member of the superfamily of nuclear receptors, in both genomic and non-genomic ways in almost every tissue in the human body. In this review, we provide an update on glucocorticoid receptor signaling and highlight the role of GR signaling in physiological and pathophysiological conditions in the major organ systems in the human body.