Bisphosphonates and glucocorticoids: Effects on bone quality

Efficacy of denosumab on bisphosphonate-treated osteoporosis and osteopenia in systemic rheumatic disease patients receiving glucocorticoids

INTRODUCTION

Evidence on second-line agents for osteoporosis and osteopenia associated with glucocorticoid use after first-line bisphosphonate therapy is limited. We, therefore, examine the efficacy of denosumab on bisphosphonate-treated osteoporosis and osteopenia in Japanese systemic rheumatic disease (SRD) patients receiving glucocorticoids.

MATERIALS AND METHODS

Glucocorticoid-treated SRD patients with a pre-existing fragility fracture, either lumbar spine (LS) or femoral neck (FN) bone mineral density (BMD) T-score of ≤ -2.5 or of ≤ -1.5 without a significant increase in BMD in the past year despite oral bisphosphonate therapy were enrolled in this study. They were randomized to switch to 60 mg subcutaneous denosumab every six months (switching group) or to continue the bisphosphonate (continuing group). The primary endpoint was the percent change from baseline in BMD at the LS and FN at week 52.

RESULTS

Of the 39 subjects, 19 were assigned to the switching group and 20 to the continuing group. The switching group showed significant increases in LS BMD (5.7% vs. 1.1%, p = 0.002) and FN BMD (4.2% vs. -0.3%, p = 0.008) at week 52 than the continuing group, with a significant decrease in serum tartrate-resistant acid phosphatase 5b (-28.1% vs. 7.0%, p < 0.001) and improved patient satisfaction.

CONCLUSION

Switching to denosumab demonstrated greater efficacy than continuing bisphosphonates in increasing BMD, inhibiting osteoclast activation, and enhancing patient satisfaction in Japanese bisphosphonate-treated osteoporosis and osteopenia patients with concomitant SRD receiving glucocorticoids.

Extract and fraction of Cassia occidentalis L. (a synonym of Senna occidentalis) have osteogenic effect and prevent glucocorticoid-induced osteopenia

ETHNOPHARMACOLOGICAL RELEVANCE

Cassia occidentalis L., a synonym of Senna occidentalis (belongs to Caesalpiniaceae family) is an annual plant. Pursuing a lead from a folk practice prevalent since the late nineteenth century in Andhra Pradesh, a Southern state of India, of use of Cassia occidentalis leaf and stem for treating patients with fracture and bone diseases, we have not only confirmed its fracture healing activity but also demonstrated efficacy in preventing glucocorticoid-induced osteoporosis (GIO), the commonest form of medication-induced bone loss caused chiefly due to impairment of bone formation.

AIM OF THE STUDY

In the present work, the effects of extract and fraction of leaf and stem of Cassia occidentalis was investigated in fracture healing and GIO models of rat. The study also aimed to identify osteogenic compounds from this plant.

MATERIALS AND METHODS

Ethanolic extracts from leaf and stem of Cassia occidentalis were prepared and their efficacy tested in rat femur osteotomy (fracture healing) model. Subsequently, a butanolic fraction was prepared and osteogenic efficacy compared with the ethanolic extract, and upon finding the former to be more potent, its osteogenic effect was studied in details in GIO model. Chemical finger-printing and isolation of ten pure compounds were done to assess their osteogenic effect in rat primary osteoblast cultures.

RESULTS

Ethanolic extract of stem was more effective than the leaf extract in enhancing bone regeneration at the site of osteotomy. Further, butanolic fraction of the ethanolic extract of stem was more effective than the later in bone regeneration at the femur osteotomy site and in preventing bone loss in GIO model. The mechanism of skeletal preservation involved stimulation of new bone formation and inhibition of bone resorption. As many as six osteogenic compounds were isolated out of which apigenin-6C-glucopyranoside was most effective in vitro.

CONCLUSION

Our study found that a standardized extract of an ethanolic extract and its butanolic fraction from the stem of Cassia occidentalis has osteogenic as well as anti-resorptive effects, resulting in the protection against glucocorticoid-induced bone loss. Our results contribute towards validation of the traditional use of Cassia occidentalis in fracture healing and also suggest its beneficial use in GIO for which clinical trials are warranted.

Dexamethasone induces osteoblast apoptosis through ROS-PI3K/AKT/GSK3β signaling pathway

BACKGROUND

Osteoblasts play important roles in the process of osteogenesis and prevention of osteonecrosis. Dexamethasone (Dex), a type of glucocorticoids (GCs), induces apoptosis of osteoblasts and leads to the occurrence of non-traumatic osteonecrosis. This study aimed to explore the effects of phosphatidylinositol 3-kinase/Protein kinase 3 (PI3K/AKT) and glycogen synthase kinase 3β (GSK3β) on Dex-induced osteoblasts apoptosis.

METHODS

Viabilities, proliferation, and apoptosis of primary osteoblasts and pre-osteoblast MC3T3-E1 cells after Dex treatment were detected using cell counting kit-8 (CCK-8) assay, 5-bromo-2'-deoxyuridine (BrdU) incorporation assay, FITC-Annexin V/PI staining and western blotting, respectively. 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) staining was performed to measure the intracellular reactive oxygen species (ROS) levels after Dex treatment. N-acetyl-l-cysteine (NAC) was used as ROS scavenger in this research. The expressions of PI3K/AKT and GSK3β in osteoblasts and MC3T3-E1 cells after Dex treatment were analyzed using western blotting and qRT-PCR, respectively. Then the effects of GSK3β knockdown on Dex-induced apoptosis of osteoblasts were explored. Alkaline phosphatase (ALP) activity assay was used to detect the role of Dex in regulating ALP activity.

RESULTS

Dex remarkably inhibited proliferation and induced apoptosis of osteoblasts and MC3T3-E1 cells. Dex potentially attenuated the osteoblast differentiation. The intracellular ROS levels were significantly increased after Dex treatment. Dex suppressed the activation of PI3K/AKT pathway in osteoblasts and MC3T3-E1 cells by down-regulating the expressions of p-PI3K and p-AKT. The expressions of GSK3β in osteoblasts and MC3T3-E1 cells were obviously up-regulated after Dex treatment. Knockdown of GSK3β alleviated Dex-induced osteoblast and MC3T3-E1 cell apoptosis by decreasing the expressions of Bax, cleaved-caspase 3, cleaved-caspase 9 and increasing the expression of Bcl-2.

CONCLUSION

Our research verified that Dex induced osteoblasts apoptosis by ROS-PI3K/AKT/GSK3β signaling pathway.

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.

Patient satisfaction and efficacy of switching from weekly bisphosphonates to monthly minodronate for treatment and prevention of glucocorticoid-induced osteoporosis in Japanese patients with systemic rheumatic diseases: a randomized, clinical trial

The randomized, clinical trial demonstrated that switching to monthly minodronate from weekly alendronate and risedronate provides greater increases in patients' satisfaction and bone mineral density and more substantial decreases in a bone resorption marker than continuing weekly alendronate and risedronate in patients with systemic rheumatic diseases on glucocorticoid therapy.

PURPOSE

Osteoporosis and associated fractures are major concerns for patients with systemic rheumatic diseases on long-term glucocorticoid therapy. Bisphosphonates increase bone mineral density (BMD) and reduce the frequency of vertebral fractures, but they are associated with poor adherence. The effects of monthly oral minodronate on patients' satisfaction, BMD, and bone turnover markers were investigated in patients with systemic rheumatic diseases on glucocorticoids and weekly oral alendronate or risedronate.

METHODS

Study patients with systemic rheumatic diseases on oral glucocorticoids and weekly alendronate 35 mg or risedronate 17.5 mg were randomly assigned either to switch to minodronate 50 mg every 4 weeks or to continue the currently taking weekly bisphosphonate for 52 weeks after a 24-week run-in period.Patients were stratified by hospital site, sex, and menopausal status in women at enrollment. The primary endpoint was the difference between the proportions of patients who responded very satisfactory or satisfactory for the current bisphosphonate therapy at weeks 48 and 76 between the two groups. Secondary endpoints included percentage changes in lumbar spine BMD and bone turnover markers from the time of starting allocated treatment.

RESULTS

Monthly minodronate was superior to weekly alendronate or risedronate for patients' satisfaction, the increase of lumbar spine BMD, and suppression of serum tartrate-resistant acid phosphatase 5b at week 76.

CONCLUSIONS

Monthly minodronate is more acceptable and may be more effective than weekly alendronate or risedronate for prevention and treatment of bone loss in patients with systemic rheumatic diseases on glucocorticoid therapy.

Analysis of quality improvement efforts in preventing glucocorticoid-induced osteoporosis

OBJECTIVE

To report and analyze quality improvement (QI) efforts that are aimed at increasing adherence to preventive guidelines for glucocorticoid-induced osteoporosis (GIOP).

METHODS

We performed a PubMed literature search for full-length articles in English between 1966 and 2013, describing approaches for improving the quality of GIOP care. We reviewed articles using a structured approach and abstracted information on the patient population, study design, QI intervention, and primary outcome measures. A descriptive analysis was then performed.

RESULTS

Literature search identified 661 articles; 38 were screened by abstract, 10 were identified for full review, and 7 were included. Two non-randomized, uncontrolled studies of system changes showed significant improvements in GIOP prevention: one increased concomitant prescriptions of glucocorticoids and calcium (37-49%, p < 0.0001) and vitamin D (38-53%, p < 0.0001) using a computerized order entry system; another used a dedicated clinical team to increase vitamin D levels from 19.5 to 29.4 (p = 0.001) and improve GIOP-related habits. Five articles described education-based interventions, including 3 randomized controlled trials (RCTs). Two non-significant RCTs focused on physicians, but one directed towards pharmacists and patients did increase calcium supplementation in the intervention vs. control arm (55.7% vs. 31.6%, p < 0.05). Two other non-randomized educational interventions did not show benefits. Comparison of articles was limited by the heterogeneity of the intervention methods and outcome measures used.

CONCLUSION

None of the interventions produced robust changes, with overall adherence to GIOP guidelines remaining low. System-based interventions appeared more effective than education-based interventions, but a diverse array of factors likely needs to be addressed, requiring more randomized controlled trials and greater standardization of outcome measures.

Glucocorticoids: bad or safe for the bones?

Until recently, patients with rheumatoid arthritis (RA) were treated with monotherapy using conventional drugs such as sulfasalazine, antimalarials, intramuscular gold and methotrexate, which often leads to persistent arthritis, loss of functional capacity and decreased quality of life. The use of high-dose glucocorticoids (GCs) and active RA are both associated with generalised bone loss and fractures, while GCs have a strong immunosuppressive effect. With the introduction of very effective tumour-necrosis factor-blockers and other biologics, clinical remission is a realistic target in around half of the early patients with RA; the same appears true for the use of methotrexate with chronic low dose or initially high-dose GCs. With the use of a treat-to-target strategy focusing on clinical remission or low disease activity in early patients with RA, the negative effects of systemic inflammation on bone can be inhibited and local bone loss (in the joints), and generalised bone loss at the spine and hips, can be limited or prevented. Whether this also leads to a reduction in vertebral and non-vertebral fractures remains to be demonstrated. Another issue is, in other systemic rheumatic diseases in which treatment options are smaller and less effective than in RA, local and systemic bone loss may still occur.

Established and forthcoming drugs for the treatment of osteoporosis

PURPOSE OF REVIEW

The aim of treatment in patients at high risk for fractures is to reduce the risk of a first or a subsequent fracture. New data are available on the antifracture effects and side-effects of antiresorptive and osteoanabolic drugs, and new emerging therapies with new modes of action are on the horizon.

RECENT FINDINGS

Calcium and vitamin D intake should be sufficient, but not too high. Vertebral, nonvertebral (including hip fracture) prevention with antiresorptive drugs such as bisphosphonates (alendronate, risedronate and zoledronic acid) and denosumab exceeds the risk of rare side-effects such as atypical femur fracture and osteonecrosis of the jaw. Teriparatide is an osteoanabolic drug that improves quality of life in severe osteoporosis. Strontium ranelate decreases dynamic parameters of bone formation during the first year of treatment, and could increase the risk of cardiovascular events in high-risk patients. Initiation of and adherence to fracture prevention drugs are still low. New potential developments in antiresorptive drugs include odanacatib, a selective inhibitor of cathepsin K, and, in osteoanabolic drugs, monoclonal antibodies against sclerostin.

SUMMARY

These recent data indicate that fracture prevention with antiresorptives and teriparatide is effective with a reasonable safety profile. Odanacatib and antisclerostin are promising new drugs with new mechanisms of action, as they are able to disconnect the normal coupling between bone resorption and bone formation.

Can bone loss in rheumatoid arthritis be prevented?

Rheumatoid arthritis (RA) is a systemic inflammatory disease that can lead to local joint deformations (bone erosions and joint space narrowing) and to extra-articular phenomena, including generalized osteoporosis. In addition, in patients with RA, the risk of vertebral and nonvertebral fractures is doubled. High disease activity (inflammation), immobility, and glucocorticoid use are common factors that substantially increase fracture risk in these patients, on top of the background fracture risk based on classical risk factors such as high age, low body mass, and female gender. New insights on the links between the immune system and the bone system, the field of osteoimmunology, have shown that local and generalized bone loss share common pathways. The receptor activator of nuclear factor κB ligand/osteoprotegerin pathway (RANKl/OPG) is one of the most important pathways, as it is (strongly) upregulated by inflammation. In modern treatment of RA with biologics, for example, TNFα-blocking agents and combination therapy of conventional disease-modifying antirheumatic drugs (DMARDs), clinical remission is a realistic treatment goal. As a consequence, in recent studies, it has been documented that both local and generalized bone loss is absent or minimal in those patients who are in clinical remission.

Once-monthly oral ibandronate provides significant improvement in bone mineral density in postmenopausal women treated with glucocorticoids for inflammatory rheumatic diseases: a 12-month, randomized, double-blind, placebo-controlled trial

OBJECTIVES

To study the efficacy and safety of once-monthly oral ibandronate in the prevention of glucocorticoid (GC)-induced osteoporosis (GIOP) in postmenopausal women with inflammatory rheumatic diseases.

METHOD

A randomized, double-blind, placebo-controlled, parallel-group study of 140 postmenopausal women was conducted. At baseline, the mean lumbar spine (LS) (L1-L4) bone mineral density (BMD) was normal or osteopaenic (T-score ≥ -2.0) and the patients were receiving treatment with 5-15 mg/day of prednisone equivalent. Patients were randomized 1:1 to receive either monthly oral ibandronate 150 mg or placebo for 12 months. All patients received vitamin D and calcium supplements. The primary endpoint was the relative change in mean LS BMD from baseline to 12 months.

RESULTS

Mean LS BMD increased significantly by 2.6% and 3.2% from baseline to 6 and 12 months with ibandronate compared to 0.3% and -0.1% with placebo, respectively (p < 0.001). Comparable significant mean increases were also found in trochanter, femoral neck and total hip BMDs at 12 months. Reductions in the serum levels of bone turnover markers C-terminal telopeptide of type I collagen (sCTX), N-terminal propeptide of type I procollagen (P1NP), and tartrate-resistant acid phosphatase (TRACP) were significantly more marked in the ibandronate group than in the placebo group at 1, 6, and 12 months. Adverse events (AEs) were reported at a similar frequency in both groups. A higher proportion of serious AEs (SAEs) were reported in the ibandronate group without emergence of any single SAE.

CONCLUSIONS

Once-monthly oral ibandronate provides a significant increase in LS and total hip BMD with an acceptable safety profile in postmenopausal women treated with low-dose GCs for inflammatory rheumatic diseases.

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

INTRODUCTION

Glucocorticoid-induced osteoporosis (GIOP) is one of the most devastating side-effects of glucocorticoid (GC) use, as it is associated with an increased fracture risk. The importance of GIOP as a health problem is underlined by the frequent use of GC treatment in patients with various chronic diseases and by the high rates of osteoporosis found in these patient groups.

AREAS COVERED

Recent studies on bone metabolism and the influence of GCs have contributed to a better understanding of the pathogenesis of GIOP. Furthermore, new intervention trials have reported beneficial effects of antiresorptive and anabolic agents on GIOP. This article reviews the epidemiology and pathophysiology of osteoporosis and fractures in GC-treated patients and discusses current pharmacotherapy and possible future treatment options.

EXPERT OPINION

Several guidelines for the management of GIOP have been published, using different criteria for bone mineral density (BMD) thresholds and for GC dosages above which anti-osteoporotic therapy should be started. Although alendronate and risedronate are currently first choice, the anabolic agent teriparatide seems to be superior and might be considered as a potential first-line therapy for patients with low BMD on long-term GC treatment. Adherence to anti-osteoporotic drugs is limited, particularly in GIOP patients, due to several factors.

Post-genomics of bone metabolic dysfunctions and neoplasias

Post-genomic research on osteoblastic and osteoclastic cells, in contrast to that on many other cell types, has only been undertaken recently. Nevertheless, important information has been gained from these investigations on the mechanisms involved in osteoblast differentiation and on markers relevant for tissue regeneration and therapeutic validation of drugs, hormones and growth factors. These protein indicators may also have a diagnostic and prognostic value for bone dysfunctions and tumors. Some reviews have already focused on the application of transcriptomics and/or proteomics for exploring skeletal biology and related disorders. The main goal of the present review is to systematically summarize the most relevant post-genomic studies on various metabolic bone diseases (osteoporosis, Paget's disease and osteonecrosis), neoplasias (osteosarcoma) and metabolic conditions that indirectly affect bone tissue, such as alkaptonuria.

Effectiveness of teriparatide in postmenopausal women with osteoporosis and glucocorticoid use: 3-year results from the EFOS study

OBJECTIVE

To describe clinical fracture rates, back pain, and health-related quality of life (HRQOL) in postmenopausal women with osteoporosis who are receiving glucocorticoids (GC), during a 36-month study of teriparatide treatment for up to 18 months, with an additional 18-month followup period when patients were receiving other osteoporosis medications.

METHODS

A prospective, multinational, observational study. Data for clinical fractures, back pain (by visual analog scale; VAS) and HRQOL (by EQ-5D) were collected over 36 months. Fracture data were summarized in 6-month segments and analyzed using logistic regression with repeated measures. Changes from baseline in back pain VAS and EQ-VAS were analyzed.

RESULTS

Of 1581 enrolled women with followup data, 294 (18.6%) had antecedents of GC use. Of these, 49 (16.7%) patients sustained a total of 69 fractures during the 36-month study period. Adjusted odds of fracture were significantly decreased during the last year of followup compared with the first 6 months of teriparatide treatment: an 81% decrease in the 24 to < 30-month period (p < 0.05), and an 89% decrease in the 30 to < 36-month period (p < 0.05). There were significant reductions in back pain and improvements in HRQOL in both groups of GC users and nonusers.

CONCLUSION

Postmenopausal women with severe osteoporosis receiving GC, who were treated with teriparatide for up to 18 months, showed a reduced incidence of clinical fractures during the third year while receiving sequential osteoporosis treatments compared with the first 6 months, together with reduced back pain and improved HRQOL. Our results should be interpreted in the context of an uncontrolled observational study in a routine clinical setting.

Suppression of bone turnover by B-cell depletion in patients with rheumatoid arthritis

The role of B cells in inflammatory bone formation and resorption is controversial. We investigated this in patients with rheumatoid arthritis (RA) treated with rituximab, a B-cell depleting antibody. We found a significant suppression in bone turnover, possibly a direct effect or as a consequence of a reduction in inflammation and disease activity.

INTRODUCTION

RA is the most prevalent inflammatory joint disease, in which B cells play an important role. However, the role of B cells in bone turnover is controversial and RA subjects treated with rituximab, a B-cell depleting monoclonal antibody, provide an ideal model for determining the role of B cells in inflammatory bone resorption.

METHODS

Serum from 46 RA patients, collected pre- and post-rituximab therapy, was analysed for biomarkers of bone turnover (procollagen type I amino-terminal propeptide [P1NP], osteocalcin, β-isomerised carboxy-terminal telopeptide of type 1 collagen [βCTX] and osteoprotegerin [OPG]).

RESULTS

A significant decrease in bone resorption was observed 6 months after rituximab (median change βCTX -50 ng/L, 95%CI -136, -8 p < 0.001, this equates to -37%; 95%CI -6, -49), mirrored by a reduction in disease activity. Similarly, there was a significant increase in P1NP, a marker of bone formation (median change P1NP 5.0 μg/L, 95%CI -1.0, 11.2, p = 0.02; 13%; 95%CI -3, 39), but no significant change in osteocalcin or OPG levels. The percentage change from baseline of βCTX in a subgroup of patients (not on prednisolone or bisphosphonate) was significantly correlated with the percentage reduction in DAS28 score (r (s) = 0.570, p = 0.014).

CONCLUSIONS

In conclusion, we have found that B-cell depletion increases bone formation and decreases bone resorption in RA patients; this may be a direct effect on osteoblasts and osteoclasts, respectively, and be at least partially explained by the decreased inflammation and disease activity.

Advances in glucocorticoid-induced osteoporosis

Glucocorticoid-induced osteoporosis (GIOP) is one of the most important side effects of glucocorticoid use, as it leads to an increased risk of fractures. Recently, many published studies have focused on the cellular and molecular mechanisms of bone metabolism, the pathophysiology of GIOP, and the intervention options to prevent GIOP. In this review, recent advances in GIOP are summarized, particularly recent progress in our understanding of the mechanisms of GIOP resulting in improved insight that might result in the development of new treatment options in the near future.

PTH analogues and osteoporotic fractures

IMPORTANCE OF THE FIELD

At present there are two parathyroid hormone (PTH) analogues (PTH 1 - 34 and PTH 1 - 84) registered for the treatment of established osteoporosis in postmenopausal women (PTH 1 - 34 and PTH 1 - 84) and in men (PTH 1 - 34 only) who are at increased risk of having a fracture.

AREAS COVERED IN THIS REVIEW

The efficacy and safety of PTH 1 - 34 and PTH 1 - 84 in the management of osteoporosis is evaluated by reviewing published literature and presentations from scientific meetings through to 2010.

WHAT THE READER WILL GAIN

This review focuses on data on fracture risk reduction and safety endpoints of PTH analogues. The adverse reactions reported most are nausea, pain in the extremities, headache and dizziness.

TAKE HOME MESSAGE

Exogenous PTH analogues, given as daily subcutaneous injections, stimulate bone formation, increase bone mass and bone strength, and improve calcium balance. In postmenopausal women with osteoporosis, PTH analogues reduced the risk of vertebral (PTH 1 - 34 and PTH 1 - 84) and non-vertebral fractures (only PTH 1 - 34). In men and women with glucocorticosteroid-induced osteoporosis, PTH 1 - 34 reduced the risk of vertebral fractures. In general, PTH analogues are well tolerated with an acceptable safety profile: they can be used for the prevention and treatment of fractures in postmenopausal women with severe, established osteoporosis.

Prevention of glucocorticoid-induced osteoporosis

Glucocorticoid-induced osteoporosis is the most common cause of secondary osteoporosis. The role of the Wnt signaling pathway in bone formation and the ratio of receptor activator for NF-kappaB ligand versus osteoprotegerin in bone resorption are exciting new insights. The absolute fracture risk helps both clinicians and patients to interpret the results of bone density measurement, which may have a positive influence on adherence to therapy. The bisphosphonates alendronate and risedronate are the first-line treatment in the prevention of glucocorticoid-induced osteoporosis, because both increase the bone mineral density of the spine and hips and reduce the vertebral fracture rate. Treatment with the anabolic agent parathyroid hormone (1 - 34) strongly stimulates bone turnover, and seems to be superior to treatment with alendronate. It might be attractive for glucocorticoid-treated patients with new vertebral fractures during treatment with bisphosphonates, and/or with severe fracture risk.

Clinical relevance of diagnosing vertebral fractures by vertebral fracture assessment

Low bone mineral density and the presence of vertebral fractures are independent predictors for future vertebral and non-vertebral fractures. Combining the conventional measurement of bone mineral density of spine and hips with the morphometry of the thoracal and lumbar vertebrae on lateral images using dual energy x-ray absorptiometry scanners, a technique called vertebral fracture assessment, facilitates detection of vertebral fractures in those patients at older age and with clinical risk factors for osteoporosis. Particularly, the finding of one or more vertebral deformities in patients with osteopenia is clinically important, because this might prompt the start of anti-osteoporotic treatment.

Prevention of glucocorticoid-induced bone loss in mice by inhibition of RANKL

OBJECTIVE

RANKL has been implicated in the pathogenesis of glucocorticoid-induced osteoporosis. This study was undertaken to evaluate the efficacy of denosumab, a neutralizing monoclonal antibody against human RANKL (hRANKL), in a murine model of glucocorticoid-induced osteoporosis.

METHODS

Eight-month-old male homozygous hRANKL-knockin mice expressing a chimeric RANKL protein with a humanized exon 5 received 2.1 mg/kg of prednisolone or placebo daily over 4 weeks via subcutaneous slow-release pellets and were additionally treated with phosphate buffered saline or denosumab (10 mg/kg subcutaneously twice weekly). Two groups of wild-type mice were also treated with either prednisolone or vehicle.

RESULTS

The 4-week prednisolone treatment induced loss of vertebral and femoral volumetric bone mineral density in the hRANKL-knockin mice. Glucocorticoid-induced bone loss was associated with suppressed vertebral bone formation and increased bone resorption, as evidenced by increases in the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, TRAP-5b protein in bone extracts, serum levels of TRAP-5b, and urinary excretion of deoxypyridinoline. Denosumab prevented prednisolone-induced bone loss by a pronounced antiresorptive effect. Biomechanical compression tests of lumbar vertebrae revealed a detrimental effect of prednisolone on bone strength that was prevented by denosumab.

CONCLUSION

Our findings indicate that RANKL inhibition by denosumab prevents glucocorticoid-induced loss of bone mass and strength in hRANKL-knockin mice.