Glucocorticoid-induced osteoporosis: from basic mechanisms to clinical aspects

Navigating Post-Traumatic Osteoporosis: A Comprehensive Review of Epidemiology, Pathophysiology, Diagnosis, Treatment, and Future Directions

Post-traumatic osteoporosis (PTO) presents a significant challenge in clinical practice, characterized by demineralization and decreased skeletal integrity following severe traumatic injuries. This literature review manuscript addresses the knowledge gaps surrounding PTO, encompassing its epidemiology, pathophysiology, risk factors, diagnosis, treatment, prognosis, and future directions. This review emphasizes the complexity of the etiology of PTO, highlighting the dysregulation of biomineralization processes, inflammatory cytokine involvement, hormonal imbalances, glucocorticoid effects, vitamin D deficiency, and disuse osteoporosis. Moreover, it underscores the importance of multidisciplinary approaches for risk mitigation and advocates for improved diagnostic strategies to differentiate PTO from other musculoskeletal pathologies. This manuscript discusses various treatment modalities, including pharmacotherapy, dietary management, and physical rehabilitation, while also acknowledging the limited evidence on their long-term effectiveness and outcomes in PTO patients. Future directions in research are outlined, emphasizing the need for a deeper understanding of the molecular mechanisms underlying PTO and the evaluation of treatment strategies' efficacy. Overall, this review provides a comprehensive overview of PTO and highlights avenues for future investigation to enhance clinical management and patient outcomes.

IDO activation, inflammation and musculoskeletal disease

The IDO/kynurenine pathway is now established as a major regulator of immune system function. The initial enzyme, indoleamine 2,3-dioxygenase (IDO1) is induced by IFNγ, while tryptophan-2,3-dioxygenase (TDO) is induced by corticosteroids. The pathway is therefore positioned to mediate the effects of systemic inflammation or stress-induced steroids on tissue function and its expression increases with age. Disorders of the musculoskeletal system are a common feature of ageing and many of these conditions are characterized by an inflammatory state. In inflammatory arthritis and related disorders, kynurenine protects against the development of disease, while inhibition or deletion of IDO1 increases its severity. The long-term regulation of autoimmune disorders may be influenced by the epigenetic modulation of kynurenine pathway genes, with recent data suggesting that methylation of IDO may be involved. Osteoporosis is also associated with abnormalities of the kynurenine pathway, reflected in an inversion of the ratio between blood levels of the metabolites anthranilic acid and 3-hydroxy-anthranilic acid. This review discusses evidence to date on the role of the IDO/kynurenine pathway and the highly prevalent age-related disorders of osteoporosis and rheumatoid arthritis and identifies key areas that require further research.

Increased EZH2 and decreased osteoblastogenesis during local irradiation-induced bone loss in rats

Radiation therapy is commonly used to treat cancer patients but exhibits adverse effects, including insufficiency fractures and bone loss. Epigenetic regulation plays an important role in osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Here, we reported local bone changes after single-dose exposure to ¹³⁷C_S irradiation in rats. Femur bone mineral density (BMD) and trabecular bone volume in the tibia were significantly decreased at 12 weeks after irradiation. Micro-CT results showed that tBMD, Tb.h and Tb.N were also significantly reduced at 12 weeks after irradiation exposure. ALP-positive OB.S/BS was decreased by 42.3% at 2 weeks after irradiation and was decreased by 50.8% at 12 weeks after exposure. In contrast to the decreased expression of Runx2 and BMP2, we found EZH2 expression was significantly increased at 2 weeks after single-dose ¹³⁷C_S irradiation in BMSCs. Together, our results demonstrated that single-dose ¹³⁷C_S irradiation induces BMD loss and the deterioration of bone microarchitecture in the rat skeleton. Furthermore, EZH2 expression increased and osteoblastogenesis decreased after irradiation. The underlying mechanisms warrant further investigation.

Glucocorticoid-Induced Osteoporosis

Osteoporosis is among the most devastating side effects of glucocorticoid (GC) therapy for the management of inflammatory and auto-immune diseases. Evidence from both humans and mice indicate deleterious skeletal effects within weeks of pharmacological GC administration, both related and unrelated to a decrease in bone mineral density (BMD). Osteoclast numbers and bone resorption are also rapidly increased, and together with osteoblast inactivation and decreased bone formation, these changes lead the fastest loss in BMD during the initial disease phase. Bone resorption then decreases to sub-physiological levels, but persistent and severe inhibition of bone formation leads to further bone loss and progressively increased fracture risk, up to an order of magnitude higher than that observed in untreated individuals. Bone forming osteoblasts are thus considered the main culprits in GC-induced osteoporosis (GIO). Accordingly, we focus this review primarily on deleterious effects on osteoblasts: inhibition of cell replication and function and acceleration of apoptosis. Mediating these adverse effects, GCs target pivotal regulatory mechanisms that govern osteoblast growth, differentiation and survival. Specifically, GCs inhibit growth factor pathways, including Insulin Growth Factors, Growth Hormone, Hepatocyte Growth/Scatter Factor and IL6-type cytokines. They also inhibit downstream kinases, including PI3-kinase and the MAP kinase ERK, the latter attributable in part to direct transcriptional stimulation of MAP kinase phosphatase 1. Most importantly, however, GCs inhibit the Wnt signaling pathway, which plays a pivotal role in osteoblast replication, function and survival. They transcriptionally stimulate expression of Wnt inhibitors of both the Dkk and Sfrp families, and they induce reactive oxygen species (ROS), which result in loss of ß-catenin to ROS-activated FoxO transcription factors. Identification of dissociated GCs, which would suppress the immune system without causing osteoporosis, is proving more challenging than initially thought, and GIO is currently managed by co-treatment with bisphosphonates or PTH. These drugs, however, are not ideally suited for GIO. Future therapeutic approaches may aim at GC targets such as those mentioned above, or newly identified targets including the Notch pathway, the AP-1/Il11 axis and the osteoblast master regulator RUNX2.

Comparison of the effects of acute exercise after overnight fasting and breakfast on energy substrate and hormone levels in obese men

[Purpose] We compared the effects of acute aerobic exercise following overnight fasting and breakfast on energy substrate and hormone levels in obese male college students. [Subjects and Methods] This crossover study recruited 10 obese male college students with a body mass index >25 kg/m² or >20% body fat. One week post-recruitment, the subjects exercised in the morning after an overnight fast. At 2 weeks, they exercised post-breakfast. Energy substrate (glucose, free fatty acid) and metabolic hormone (insulin, growth hormone, and cortisol) levels were measured immediately before and after exercise and at 60 min post-exercise. [Results] We observed interaction effects between the measurement time and exercise treatment for glucose; significant differences between measurement times and between exercise treatments for free fatty acids; interaction effects between the measurement time and exercise treatment for insulin and significant differences in the measurement time; significance differences between measurement times and between exercise treatments for growth hormone; and significant differences between measurement times and between exercise treatments for cortisol. [Conclusion] Morning exercise following an overnight fast can be more effective in reducing body fat than post-prandial exercise. However, increased cortisol levels following exercise after overnight fasting may negatively affect long-term weight loss in obese men.

Osteoporosis in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a lifestyle-related chronic inflammatory pulmonary disease associated with significant morbidity and mortality worldwide. COPD is associated with various comorbidities found in all stages of COPD. The comorbidities have significant impact in terms of morbidity, mortality, and economic burden in COPD. Management of comorbidities should be incorporated into the comprehensive management of COPD as this will also have an effect on the outcome in COPD patients. Various comorbidities reported in COPD include cardiovascular disease, skeletal muscle dysfunction, anemia, metabolic syndrome, and osteoporosis. Osteoporosis is a significant comorbidity in COPD patients. Various risk factors, such as tobacco smoking, systemic inflammation, vitamin D deficiency, and the use of oral or inhaled corticosteroids (ICSs) are responsible for its occurrence in patients with COPD. This review will focus on the prevalence, pathogenesis, risk factors, diagnosis, and treatment of osteoporosis in COPD patients.

Osteoporosis in the at-risk asthmatic

The effect of inhaled glucocorticosteroids (ICS) on bone metabolism and subsequent osteoporosis is controversial. Explanations for this controversy include various study designs, duration of use, outcome measures, and population demographics of research studies with intranasal or inhalational ICS. Patients with poorly controlled asthma are at greatest risk of osteoporosis because they are commonly treated with intermittent or continuous systemic corticosteroids (SCS) or high-dose ICS. A 45-year-old Caucasian woman presents with moderate-to-severe asthma with frequent albuterol use and nighttime awakenings at least once weekly. She is on fluticasone/salmeterol 500/50 μg one inhalation twice daily and montelukast 10 mg/day. She requires prednisone 15 mg three times per day for 5 days up to three times a year. Is this patient at greater risk of osteopenia, characterized by a T-score between -1.0 and -2.5, and subsequent osteoporosis and an increased risk of fractures? If she has osteopenia, should she be treated with a bisphosphonate? The risk of osteoporosis and fracture increases significantly with frequent administration of SCS, and patients on such medications should undergo preventative measures and treatment. This study discuses factors that contribute to an increased risk of osteoporosis/osteopenia in patients with asthma and suggests recommendations based on the current literature.

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.

In vitro and in vivo inhibition of glucocorticoid-induced osteoporosis by the hexane extract of Poncirus trifoliata

This study was performed to discover a novel herbal therapeutic for effective glucocorticoid-induced osteoporosis (GIO) treatment and further to clarify its molecular mechanism of action. Ethanol or methanol extracts of 68 edible Korean native plants were screened to find effective natural plant sources for the treatment of GIO, and Poncirus trifoliata (L.) (Rutaceae, PT) was selected as a final candidate because of its high inhibitory activity plus its novelty. The hexane extract of PT (PT-H) inhibited apoptotic cell death in dexamethasone-induced osteoblastic cell lines, C3H10T1/2 and MC3T3-E1. In vivo mouse results indicated that PT-H not only had an inhibitory effect on the bone loss caused by glucocorticoid, but also promoted bone formation. The molecular mechanisms behind the effect of PT-H on GIO were further clarified by screening of differentially expressed genes (DEGs) between dexamethasone (Dex)-induced osteoblastic cells with or without PT-H treatment. Finally, it was found that the expression level of AnxA6 in Dex-induced osteoblastic cells and prednisolone (PD)-treated GIO-model mice was significantly decreased by PT-H treatment. These findings suggest that PT-H has a strong in vitro and in vivo inhibitory effect on GIO, and decreased expression of AnxA6 may play a key role in this inhibition.

Premature loss of bone remodeling compartment canopies is associated with deficient bone formation: a study of healthy individuals and patients with Cushing's syndrome

A remarkable property of bone remodeling is that osteoblasts form bone matrix exactly where and when osteoclasts have removed it. The bone remodeling compartment (BRC) canopies that cover bone surfaces undergoing remodeling were proposed to be critical players in this mechanism. Here, we provide support to this hypothesis by analyzing the changes in prevalence of BRC canopies during the progress of the remodeling cycle in a cohort of healthy individuals and in patients with endogenous Cushing's syndrome (CS), and by relating these changes in prevalence with the extent of bone forming surfaces. Both cohorts showed almost 100% canopy coverage above resorbing osteoclasts, and only about 76% above bone forming surfaces. This indicates that BRC canopies are invariably associated with the early stage of the remodeling cycle, but may disappear later. Interestingly, in control and two-thirds of the CS patients, a significant decline in canopy coverage occurred only once bone formation was initiated, but in the remaining third of the CS patients the prevalence of canopies already decreased before bone formation. This canopy loss before initiation of bone formation coincided with significantly less bone-forming surface compared with canopy loss at a later stage. These observations support a model where bone restitution is compromised in the absence of BRC canopies, and apparently does not start when the BRC canopy is lost before initiation of the bone formation step. This model is discussed in the context of possible biological roles of BRC canopies. It suggests that BRC canopies could be privileged targets for treating patients suffering from a negative bone formation-resorption balance.

Assessment and management of low bone density in inflammatory bowel disease and performance of professional society guidelines

BACKGROUND

Inflammatory bowel disease (IBD) patients have increased prevalence of osteoporosis, leading to guideline recommendations for bone mineral density (BMD) testing. The study aim was to identify predictors of BMD testing and treatment and assess guideline effectiveness to identify IBD patients with osteoporosis.

METHODS

Records of all IBD patients at seven medical facilities were reviewed for clinical data and BMD testing from January 1996 through October 2006.

RESULTS

A total of 2035 patients had 317 bone density tests performed. Osteopenia was found in 48% of patients, osteoporosis in 26%. Among patients meeting guideline criteria for BMD testing and ≥1 year of follow-up, 23.3% underwent testing. The strongest predictors of testing were menopause (adjusted hazard ratio [AHR] 3.02) and receiving care at a tertiary center (AHR 2.56). Testing rates were low in patients with age ≥60 years, ulcerative colitis, and a history of inpatient IBD treatment. Osteoporotic patients received calcium/vitamin D and bisphosphonates in 59% and 75% of cases, respectively. Osteoporotic males had a 37% rate of hypogonadism. Guideline criteria do not distinguish patients with osteoporosis. The criteria had a sensitivity, specificity, positive predictive value, and negative predictive value of 84%, 23%, 27%, and 81% for osteoporosis in the tested population, respectively.

CONCLUSIONS

Osteoporosis is highly prevalent in the IBD population, but BMD testing and osteoporosis treatments are underutilized. Male hypogonadism is common in osteoporotic IBD patients. Guidelines do not identify IBD patients with osteoporosis.

Rapid loss of bone mass and strength in mice after abdominal irradiation

Localized irradiation is a common treatment modality for malignancies in the pelvic-abdominal cavity. We report here on the changes in bone mass and strength in mice 7-14 days after abdominal irradiation. Male C57BL/6 mice of 10-12 weeks of age were given a single-dose (0, 5, 10, 15 or 20 Gy) or fractionated (3 Gy × 2 per day × 7.5 days) X rays to the abdomen and monitored daily for up to 14 days. A decrease in the serum bone formation marker and ex vivo osteoblast differentiation was detected 7 days after a single dose of radiation, with little change in the serum bone resorption marker and ex vivo osteoclast formation. A single dose of radiation elicited a loss of bone mineral density (BMD) within 14 days of irradiation. The BMD loss was up to 4.1% in the whole skeleton, 7.3% in tibia, and 7.7% in the femur. Fractionated abdominal irradiation induced similar extents of BMD loss 10 days after the last fraction: 6.2% in the whole skeleton, 5.1% in tibia, and 13.8% in the femur. The loss of BMD was dependent on radiation dose and was more profound in the trabecula-rich regions of the long bones. Moreover, BMD loss in the total skeleton and the femurs progressed with time. Peak load and stiffness in the mid-shaft tibia from irradiated mice were 11.2-14.2% and 11.5-25.0% lower, respectively, than sham controls tested 7 days after a single-dose abdominal irradiation. Our data demonstrate that abdominal irradiation induces a rapid loss of BMD in the mouse skeleton. These effects are bone type- and region-specific but are independent of radiation fractionation. The radiation-induced abscopal damage to the skeleton is manifested by the deterioration of biomechanical properties of the affected bone.

Management of glucocorticoid-induced osteoporosis: prevalence, and emerging treatment options

An excess amount of glucocorticoids represents the primary and most frequent etiological factor influencing secondary osteoporosis. Patients receiving glucocorticoids, but also those with the endogenous form of hypercorticism, are at high risk for the loss of bone density, with the subsequent occurrence of pathological fractures. In this review, we summarize the currently available methods of prevention and the treatment of glucocorticoid-induced osteoporosis. We also include a proposal for both a prophylactic and therapeutic approach that takes into account the risk factors typical for long-term users of glucocorticoids.

The effects of hormonal contraceptives on bone turnover markers and bone health

Sex hormones are important regulators of bone metabolism. As hormonal contraceptives contain either oestrogens or progestins, or a combination thereof, it is conceivable that these widely used agents have an effect on bone metabolism and bone health. The main users of hormonal contraceptives, adolescent girls and young women, are still building bone and accruing bone mass and may therefore be particularly susceptible to the effects of hormonal contraceptives on bone. Despite these concerns, the effects of hormonal contraceptives on bone health are still poorly understood. As biochemical markers of bone turnover have been proven useful tools in the assessment and monitoring of bone metabolism, we reviewed the effects of combined and gestagen-only hormonal contraceptives on bone turnover markers and related effects on bone mineral density and fracture risk in premenopausal women, as documented in the literature until January 2009.

How activity of inflammatory bowel disease influences bone loss

Bone loss is a common problem for individuals with inflammatory bowel disease (IBD). The aim of our study was to assess bone mineral density (BMD) in patients with IBD and to investigate the role of corticosteroid (CS) use and duration and activity of disease on BMD. Ninety-two patients (56 men and 36 women) with IBD, of whom 32 had ulcerative colitis (UC) and 60 had Crohn's disease (CD), underwent clinical assessment. Lumbar and femoral neck BMDs were measured by dual-energy X-ray absorptiometry. Osteopenia was observed in 14 patients (43%) with UC and in 24 patients (40%) with CD (p=0.187). Four patients (12%) with UC and 7 patients (11%) with CD had osteoporosis (p=0.308). Femoral BMD decreased in patients with long duration of CS use and correlated inversely with disease activity. Multiple regression analysis of BMD showed that statistically significant risk factors were duration of active disease and body mass index as well. Based on our results, it is necessary to take into account the risk of decreased BMD in patients with IBD. It is most important to achieve disease remission as soon as possible in addition to nutritional support.

Major depression is a risk factor for low bone mineral density: a meta-analysis

BACKGROUND

The role of depression as a risk factor for low bone mineral density (BMD) and osteoporosis is not fully acknowledged, mainly because the relevant literature is inconsistent and because information on the mechanisms mediating brain-to-bone signals is rather scanty.

METHODS

Searching databases and reviewing citations in relevant articles, we identified 23 studies that quantitatively address the relationship between depression and skeletal status, comparing 2327 depressed with 21,141 nondepressed individuals. We subjected these studies to meta-analysis, assessing the association between depression and BMD as well as between depression and bone turnover markers.

RESULTS

Overall, depressed individuals displayed lower BMD than nondepressed subjects, with a composite weighted mean effect size (d) of -.23 (95% confidence interval: -.33 to -.13; p < .001). The association between depression and BMD was similar in the spine, hip, and forearm. It was stronger in women (d = -.24) than men (d = -.12) and in premenopausal (d = -.31) than postmenopausal (d = -.12) women. Only women individually diagnosed for major depression by a psychiatrist with DSM criteria displayed significantly low BMD (d = -.36); women diagnosed by self-rating questionnaires did not (d = -.06). Depressed subjects had increased urinary levels of bone resorption markers (d = .52).

CONCLUSIONS

The present findings portray depression as a significant risk factor for low BMD. Premenopausal women who are psychiatrically diagnosed with major depression are particularly at high-risk for depression-associated low BMD. Hence, periodic BMD measurements and antiosteoporotic prophylactic and curative measures are strongly advocated for these patients.

Once-weekly oral alendronate 70 mg in patients with glucocorticoid-induced bone loss: a 12-month randomized, placebo-controlled clinical trial

OBJECTIVE

Glucocorticoid-induced osteoporosis is the most common iatrogenic form of osteoporosis. We evaluated the efficacy and safety of once-weekly bisphosphonate therapy for prevention and treatment of bone loss in patients on glucocorticoid therapy.

METHODS

We conducted a 12-month, multicenter, randomized, double-blind, placebo-controlled trial with 114 and 59 patients in the treatment and placebo arms, respectively. Participants were stratified according to the duration of prior oral glucocorticoid therapy at randomization. Participants received alendronate 70 mg once weekly (ALN OW) or placebo; all received supplemental daily calcium (1000 mg) and 400 IU vitamin D. Clinical evaluations were performed at baseline, 3, 6, 9, and 12 months.

RESULTS

At 12 months, there was a significant mean percentage increase from baseline in the ALN OW group for lumbar spine (2.45%), trochanter (1.27%), total hip (0.75%), and total body (1.70%) bone mineral density (BMD). Comparing ALN OW versus placebo at 12 months, a significant treatment difference for the mean percentage change from baseline was observed for lumbar spine (treatment difference of 2.92%; p </= 0.001), trochanter (treatment difference 1.66%; p = 0.007), and total hip (treatment difference 1.19; p = 0.008) BMD. Biochemical markers of bone remodeling also showed significant mean percentage decreases from baseline.

CONCLUSION

Over 12 months ALN OW significantly increased lumbar spine, trochanter, total hip, and total body BMD compared with baseline among patients taking glucocorticoid therapy. A significant treatment difference versus placebo was observed at 12 months for the mean percentage change from baseline for lumbar spine, trochanter, and total hip.

An efficient and economic high-throughput cell screening model targeting the glucocorticoid receptor

AIM

To discover compounds or proteins that can efficiently bind the glucocorticoid receptor (GR) and trigger the transcription of target genes, resulting in clinical improvement of diseases such as rheumatoid arthritis, asthma, inflammatory bowel disease, a high-throughput drug screening cell model using green fluorescent protein 4 (GFP4) as a marker expressed in response to GR activation has been established and evaluated.

METHODS

Eight repeats of the glucocorticoid response element (GRE) were cloned into the Peak12SxSynGFP4 vector, and the resulting recombinant plasmid Peak12GRE8 x SxSynGFP4 was stably transfected into the 293E cells. The stable and sensitive cell line 293E/GRE8 x /GFP4 was selected by dexamethasone (DEX) using fluorescent microscopy and fluorescence-activated cell sorting. DEX induction and phorbol myristate acetate (PMA) inhibition of the green fluorescence intensity of the cell line were tested.

RESULTS

The expression of GFP4 in the cell line was under the control of GRE, up-regulated by DEX treatment and down-regulated by phorbol myristate acetate (PMA). The up-regulation of the GFP4 expression was DEX concentration-dependent, with an EC(50) at approximately 5 x 10(- 8) M. The down-regulation of the GFP4 expression was phorbol myristate acetate (PMA) concentration-dependent, with an IC(50) at approximately 3 x 10(- 6) gl - 1. The expression of GFP4 was effectively activated when cells were treated with triamcinolone acetonide.

CONCLUSION

This drug screening cell line can be used for GR-targeted high-throughput drug screening for the treatment of inflammatory diseases.

Serum fasting cortisol in relation to bone, and the role of genetic variations in the glucocorticoid receptor

OBJECTIVE

To examine the relationship between endogenous cortisol and bone, and the role of genetic variations in the glucocorticoid receptor (GR).

DESIGN AND PATIENTS

The Longitudinal Ageing Study Amsterdam (LASA), a population-based cohort study in older men and women.

MEASUREMENTS

Serum fasting cortisol was assessed by competitive immunoassay (n = 1214); bone mineral density (BMD) by dual X-ray absorptiometry (DXA) (n = 502); broadband ultrasound attenuation (BUA) by ultrasound (n = 1209); fractures by self-report (n = 1211); and GR gene polymorphisms (ER22/23EK, N363S, 9beta, BclI) were genotyped by Taqman (n = 858).

RESULTS

Higher serum fasting cortisol was significantly associated with lower BMD at all sites and BUA at the heel in women, although most relationships were attenuated by age and body mass index (BMI). The effect on femoral neck BMD remained statistically significant in the fully adjusted model (r = -0.135, P = 0.04). No significant associations in men were found. Female 9beta G-allele carriers had 50.2 nmol/l lower cortisol and 1.2 lower free cortisol levels than AA homozygotes [P = 0.01 for (free) cortisol]. Furthermore, female BclI GG homozygotes had 54.8 nmol/l higher cortisol levels than C-carriers (P = 0.03). In the total population, BclI GG homozygotes had 0.05 g/cm(2) lower trochanteric region BMD (P = 0.03). For the other GR gene polymorphisms, no significant associations were found.

CONCLUSIONS

Higher cortisol levels are associated with lower femoral neck BMD in elderly women. The G allele of the 9beta polymorphism was associated with lower serum cortisol levels in women. Female BclI GG homozygotes had higher serum cortisol levels, and BclI GG homozygotes had lower trochanteric region BMD in the total population.

Mitogen-activated protein kinase phosphatase 1/dual specificity phosphatase 1 mediates glucocorticoid inhibition of osteoblast proliferation

Steroid-induced osteoporosis is a common side effect of long-term treatment with glucocorticoid (GC) drugs. GCs have multiple systemic effects that may influence bone metabolism but also directly affect osteoblasts by decreasing proliferation. This may be beneficial at low concentrations, enhancing differentiation. However, high-dose treatment produces a severe deficit in the proliferative osteoblastic compartment. We provide causal evidence that this effect of GC is mediated by induction of the dual-specificity MAPK phosphatase, MKP-1/DUSP1. Excessive MKP-1 production is both necessary and sufficient to account for the impaired osteoblastic response to mitogens. Overexpression of MKP-1 after either GC treatment or transfection ablates the mitogenic response in osteoblasts. Knockdown of MKP-1 using either immunodepletion of MKP-1 before in vitro dephosphorylation assay or short interference RNA transfection prevents inactivation of ERK by GCs. Neither c-jun N-terminal kinase nor p38 MAPK is activated by the mitogenic cocktail in 20% fetal calf serum, but their activation by a DNA-damaging agent (UV irradiation) was inhibited by either GC treatment or overexpression of MKP-1, indicating regulation of all three MAPKs by MKP-1 in osteoblasts. However, an inhibitor of the MAPK/ERK kinase-ERK pathway inhibited osteoblast proliferation whereas inhibitors of c-jun N-terminal kinase or p38 MAPK had no effect, suggesting that ERK is the MAPK that controls osteoblast proliferation. Regulation of ERK by MKP-1 provides a novel mechanism for control of osteoblast proliferation by GCs.

Prevention and treatment of osteoporosis in inflammatory bowel disease

The following are guidelines for evaluation and consideration for treatment of patients with inflammatory bone disease (IBD) after bone mineral density (BMD) measurements. The Crohn's & Colitis Foundation of America (CCFA) has indicated that its recommendations are intended to serve as reference points for clinical decision-making, not as rigid standards, limits, or rules. They should not be interpreted as quality standards.

Calcium and vitamin D in the prevention and treatment of osteoporosis - a clinical update

Combined calcium and vitamin D supplementation is an essential component of the management of osteoporosis, supported by a strong scientific rationale. The types of individuals who should receive calcium and vitamin D supplements are those: (i) patients with documented osteoporosis receiving antiresorptive or anabolic treatment; (ii) patients receiving glucocorticoids; and (iii) individuals with or at high risk of calcium and/or vitamin D insufficiencies, in particular older women and men. This article describes the evidence base that supports targeting these groups. Benefits are most apparent when 800 IU day(-1) vitamin D is complemented with a dose of 1000-1200 mg day(-1) elemental calcium. Compliance is also key to optimizing clinical efficacy.

Do corticosteroids damage the brain?

Corticosteroids are an essential component of the body's homeostatic system. In common with other such systems, this implies that corticosteroid levels in blood and, more importantly, in the tissues remain within an optimal range. It also implies that this range may vary according to circumstance. Lack of corticosteroids, such as untreated Addison's disease, can be fatal in humans. In this review, we are principally concerned with excess or disturbed patterns of circulating corticosteroids in the longer or shorter term, and the effects they have on the brain.

Glucocorticoid-induced osteoporosis: an update

Glucocorticoid-induced osteoporosis occurs in two phases: a rapid, early phase in which bone mineral density is reduced, possibly as a result of excessive bone resorption, and a slower, progressive phase in which bone mineral density declines because of impaired bone formation. Although the indirect effects of glucocorticoids on bone are evident, their direct effects on osteoblasts, osteoclasts and osteocytes are primarily operative in the pathogenesis of glucocorticoid-induced osteoporosis. The management of patients exposed to glucocorticoids includes general health measures, sufficient calcium and vitamin D, and reducing the therapeutic regimen to the minimal effective dose. The gold standard in the pharmacological treatment of glucocorticoid-induced osteoporosis in postmenopausal women involves the use of bisphosphonates, which should be started soon after beginning chronic glucocorticoid therapy. Anabolic and alternative therapeutic strategies are currently under investigation in glucocorticoid-induced osteoporosis.