Glucocorticoid-induced Osteoporosis Group Research Articles

Isopsoralen Improves Glucocorticoid-induced Osteoporosis by Regulating Purine Metabolism and Promoting cGMP/PKG Pathway-mediated Osteoblast Differentiation.

The effects of Isopsoralen (ISO) in promoting osteoblast differentiation and inhibiting osteoclast formation are well-established, but the mechanism underlying ISO's improvement of Glucocorticoid- Induced Osteoporosis (GIOP) by regulating metabolism remains unclear. This study aims to elucidate the mechanism of ISO treatment for GIOP through non-targeted metabolomics based on ISO's efficacy in GIOP. Initially, we established a GIOP female mouse model and assessed ISO's therapeutic effects using micro-CT detection, biomechanical testing, serum calcium (Ca), and phosphorus (P) level detection, along with histological analyses using hematoxylin and eosin (HE), Masson, and tartrate-resistant acidic phosphatase (TRAP) staining. Subsequently, non-targeted metabolomics was employed to investigate ISO's impact on serum metabolites in GIOP mice. RT-qPCR and Western blot analyses were conducted to measure the levels of enzymes associated with these metabolites. Building on the metabolomic results, we explored the effects of ISO on the cyclic Guanosine Monophosphate (cGMP)/Protein Kinase G (PKG) pathway and its role in mediating osteoblast differentiation. Our findings demonstrate that ISO intervention effectively enhances the bone microarchitecture and strength of GIOP mice. It mitigates pathological damage, such as structural damage in bone trabeculae, reduced collagen fibers, and increased osteoclasts, while improving serum Ca and P levels in GIOP mice. Non-- targeted metabolomics revealed purine metabolism as a common pathway between the Control and GIOP groups, as well as between the ISO high-dose (ISOH) group and the GIOP group. ISO intervention upregulated inosine and adenosine levels, downregulated guanosine monophosphate levels, increased Adenosine Deaminase (ADA) expression, and decreased cGMP-specific 3',5'-cyclic phosphodiesterase (PDE5) expression. Additionally, ISO intervention elevated serum cGMP levels, upregulated PKGI and PKGII expression in bone tissues, as well as the expression of Runt-related transcription factor 2 (Runx2) and Osterix, and increased serum Alkaline Phosphatase (ALP) activity. In summary, ISO was able to enhance the bone microstructure and bone strength of GIOP mice and improve their Ca, P, and ALP levels, which may be related to ISO's regulation of purine metabolism and promotion of osteoblast differentiation mediated by the cGMP/PKG pathway. This suggests that ISO is a potential drug for treating GIOP. However, further research is still needed to explore the specific targets and clinical applications of ISO.

Identification of circRNA Expression Profiles in BMSCs from Glucocorticoid-Induced Osteoporosis Model.

Background Circular RNAs (circRNAs) contribute to the regulation of many diseases. However, little is known about the role of circRNAs in the development of glucocorticoid-induced osteoporosis (GIOP). The present study is aimed at systematically characterizing the circRNA expression profiles in GIOP and predict the potential functions of the associated regulatory networks. Methods A small animal GIOP model was developed in Sprague-Dawley rats given daily intraperitoneal doses of the synthetic glucocorticoid dexamethasone. Micro-CT and bone histomorphometry were performed to characterize the bone loss. Alizarin red S (ARS) staining and alkaline phosphatase (ALP) activity were assessed to determine the osteogenic differentiation potential of BMSCs. RNA sequencing was performed to identify differentially expressed circRNAs in BMSCs between the GIOP and normal groups, which were validated by qRT-PCR. siRNA interference experiments were used to demonstrate their function. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the functions of differentially expressed circRNAs. The microRNA (miRNA) targets of the circRNAs and circRNA-miRNA interactions were predicted. Results Micro-CT and bone histomorphometry confirmed the rat GIOP model. Both ARS intensity and ALP activity were decreased in GIOP BMSCs. Seventeen circRNAs were identified by fold change = 2.0, p < 0.05, and false discovery rate < 0.05, of which 7 were upregulated and 10 were downregulated. The qRT-PCR results of the selected circRNAs were consistent with the RNA-seq results and showed that circARSB and circAKT3 were significantly upregulated, while circPTEN and circTRPM7 were downregulated in the GIOP group. Further functional experiments found that downregulation of circARSB and circPTEN expression resulted in a corresponding change in osteogenic differentiation, suggesting that circARSB negatively, while circPTEN positively, regulates BMSC osteogenic differentiation. Analysis of circRNA-targeted miRNAs predicted that miR-135a-5p was associated with circARSB and circAKT3, and miR-881-3p was associated with circPTEN and circTRPM7. Furthermore, the signalling pathways associated with these differentially expressed circRNAs were predicted. Conclusions The present study identified circARSB, circAKT3, circPTEN, and circTRPM7 as being associated with osteogenic differentiation during GIOP through a circRNA-targeted miRNA-mRNA axis, which might provide insight into the pathophysiological mechanism of GIOP.

Short communication: Dietary bovine milk–derived exosomes improve bone health in an osteoporosis-induced mouse model

Osteoporosis is a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue, with a consequent increase in bone fragility and fracture susceptibility. In an aged society with increased life expectancy, the incidence rate of osteoporosis is also rapidly increasing. Inadequate nutrition may negatively influence bone metabolism. Recently, many studies have investigated the functionality of milk-derived exosomes, which play important roles in cell-to-cell communication. However, there are few reports of how milk-derived exosomes influence osteoblast proliferation and differentiation. Here, we determined whether bovine colostrum-derived exosomes promote anti-osteoporosis in vitro and in vivo. Tartrate-resistant acid phosphatase-stained cells were significantly inhibited in Raw264.7 cells treated with exosomes, indicating reduced osteoclast differentiation. We induced osteoporosis in mice using glucocorticoid pellets after orally administering exosomes for 2 mo. Interestingly, the bone mineral density of exosome-fed mouse groups was significantly improved compared with the glucocorticoid-induced osteoporosis group without exosome treatment. In addition, Lactobacillus were decreased in the gut microbiota community of osteoporosis-induced mice, but the gut microbiota community composition was effectively restored by exosome intake. Taken together, we propose that exosomes isolated from bovine colostrum could be a potential candidate for osteoporosis prevention, bone remodeling improvement, and inhibition of bone resorption. To our knowledge, this is the first time that a protective effect of milk exosomes against osteoporosis has been demonstrated in vivo. Our results strongly suggest that bovine colostrum exosomes might be used as a prophylaxis to prevent the onset of osteoporosis. Indeed, our results offer promising alternative strategies in the nutritional management of age-related bone complications.

Formulation of transdermal nanoemulsion gel drug delivery system of lovastatin and its in vivo characterization in glucocorticoid induced osteoporosis rat model

Lovastatin possess bone formation capabilities but due to first pass effect could not provide significant results. Thus the aim of present investigation was to formulate a transdermal nanoemulsion (NE) gel drug delivery system to overcome its drawbacks and evaluate its potential on glucocorticoid induced osteoporosis (GIOP) in rats. NEs of size range 11–123 nm were prepared with labrafac PG, tween 80 and transcutol using pseudo-ternary phase diagrams. NEs were formulated into gel using carbopol 940 and evaluated for ex vivo permeation testing using rat abdominal skin. Finally, lovastatin NE gel preparations were tested against normal and GIOP induced rats. Femurs of rats were collected and tested for microarchitecture and biomechanical strength testing. Lovastatin NE gel preparations (LNG5 and LNG10) showed significant improvements in the microarchitecture of trabeculae near the growing plates and the strength of femurs as compared to the GIOP group. Bone resorption biomarkers (CTx and TrAcP) were reduced significantly while bone formation biomarkers (b-ALP, OC and PINP) were significantly improved in the LNG5 (p < 0.05) and LNG10 (p < 0.05) treated groups when compared to GIOP. The results suggested that LNG formulations showed promising results for improving bone microstructure and strength after osteoporosis induction.

Liraglutide increases bone formation and inhibits bone resorption in rats with glucocorticoid-induced osteoporosis.

This study aimed to investigate the effects of liraglutide on bone metabolism markers in rat models with glucocorticoid-induced osteoporosis (GIOP), including the effects on bone mass, bone tissue microstructure, bone biomechanics, and bone turnover markers. Thirty male Sprague-Dawley rats aged 8weeks were randomly divided into three groups: the control group (n = 10) was intramuscularly injected with an equal volume of 0.9% sodium chloride, the dexamethasone group (n = 10) was intramuscularly injected with dexamethasone at 1mg/kg (twice a week) to induce GIOP, the dexamethasone plus liraglutide group (n = 10) was subcutaneously injected with liraglutide at 200μg/kg daily, simultaneously. The bilateral femurs and the fifth lumbar vertebrae were collected after 12weeks to perform micro-computed tomography and bone biomechanical examinations. Also, tartrate-resistant acid phosphatase (TRACP), cross-linked carboxy-terminal telopeptide of type I collagen (CTX-I), alkaline phosphatase (ALP), and osteocalcin (OC) were tested. The bone mineral density (BMD), bone microstructure, and bone biomechanical markers reduced significantly in the dexamethasone group compared with the control group. The bone resorption indicators (TRACP and CTX-I) increased, while the bone formation indicators (ALP and OC) decreased. After liraglutide treatment, BMD, bone microstructure, and bone biomechanical markers improved significantly. Moreover, TRACP and CTX-I decreased significantly, while ALP and OC increased compared with the dexamethasone group. Liraglutide improved BMD, bone microstructure, and bone strength and reversed GIOP, primarily through the reduction of bone resorption and promotion of bone formation.

Thursday, September 27, 2018 2:05 PM–3:05 PM Section on Biologics and Basic Research Abstract Presentations: 129. Plastrum testudinis treating glucocorticoid-induce osteoporosis by down-regulating TNFR2

BACKGROUND CONTEXT Glucocorticoid-induced osteoporosis (GIOP) is a systemic bone diseaseinduced by glucocorticoid (GC). The incidence of GIOP continues to rise with the widely use of GC, and GIOP has been identified as the most common type of secondary osteoporosis. Emerging evidence has demonstrated that bone fragility induced by GIOP is much more serious than that induced by postmenopausal osteoporosis, and GIOP has higher disability rate and mortality. Excessive or prolonged GC treatment has been considered to play a major role in inhibiting bone formation. However, the underlying mechanism of GIOP has not been confirmed. Thus, it is still an important and urgent project to find out how to research the mechanism and treat GIOP. PURPOSE To explore the effect of Plastrum Testudinis treating glucocorticoid-induce osteoporosis in Wnt/β-catenin pathway by down-regulating TNFR2.To explore the effect of Plastrum Testudinis treating glucocorticoid-induce osteoporosis in Wnt/β-catenin pathway by down-regulating TNFR2. STUDY DESIGN/SETTING Animal experiment:thirty 4-month-old SD rats were randomly divided into three groups: blank group, model group and Plastrum Testudinis group. The model group and the Plastrum Testudinis group were subcutaneously injected with dexamethasone, and were successfully gavaged with 0.9% sodium chloride solution and Plastrum Testudinis respectively. The lumbar spine (L1-6) were taken after 12 weeks. PATIENT SAMPLE No patients. Thirty 4-month-old SD rats were used in this study. OUTCOME MEASURES The mRNA expression of TNFR2, β-cantenin and GSK3β in the lumbar vertebra were detected by qPCR. The protein expressions of TNFR2, p-β-cantenin and p-GSK3β were detected by Western blot. Cell expeiment:CCK8 was used to detect the proliferation of BMSCs at different concentrations for 1,3,5,7 and 14 days. Osteogenesis was induced by selecting the best concentration. ALP and alizarin red staining were used to detect the effect of PTE on osteogenic differentiation of BMSCs. The expression of TNFR2, Β-cantenin, GSK3β mRNA expression, TNFR2, p-β-cantenin, p-GSK3β protein expression of turtle plate were detected by Werstern blot. METHODS Animal experiment: Thirty 4-month-old SD rats were randomly divided into three groups: blank group, model group and Plastrum Testudinis group. The model group and the Plastrum Testudinis group were subcutaneously injected with dexamethasone, and were successfully gavaged with 0.9% sodium chloride solution and Plastrum Testudinis respectively. The lumbar spine (L1-6) were taken after 12 weeks. The mRNA expression of TNFR2, β-cantenin and GSK3β in the lumbar vertebra were detected by qPCR. The protein expressions of TNFR2, p-β-cantenin and p-GSK3β were detected by Western blot. Cell expeiment:CCK8 was used to detect the proliferation of BMSCs at different concentrations for 1,3,5,7,14 days. Osteogenesis was induced by selecting the best concentration. ALP and alizarin red staining were used to detect the effect of PTE on osteogenic differentiation of BMSCs. The expression of TNFR2, Β-cantenin, GSK3β mRNA expression, TNFR2, p-β-cantenin, p-GSK3β protein expression of turtle plate were detected by Werstern blot. RESULTS Compared with the blank group, the level of β-catenin in the GIOP group was significantly decreased (P CONCLUSIONS Plastrum Testudinis can promote the proliferation, osteogenic differentiation and mineralization of BMSCs. It can effectively resist GIOP. The Plastrum Testudinis may resist the GIOP through down-regulating the Wnt /β-catenin pathway by inhibiting TNFR2. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

BACKGROUND CONTEXT Alendronate (ALN) is a key therapeutic used to treat glucocorticoid-induced osteoporosis (GIOP), but may induce severe side effects. We showed earlier that plastrum testudinis extracts (PTE) prevented and treated GIOP in vivo. However, clinically, PTE is seldom used alone. PURPOSE We reveal the synergistic effect of ALN and PTE can treat GIOP of the rat spine and define the mechanism. METHODS Sprague-Dawley rats were randomly assigned to four groups: a vehicle group, a GIOP group, an ALN group, and an ALN+PTE group. Each group was further divided into two experimental phases, including dexamethasone (DXM) intervention and withdrawal. Bone mass, microarchitecture, biomechanics, bone-turnover markers and histomorphology were evaluated. The mRNA and protein expression levels of CTSK and Runx2 were detemined. RESULTS We found that ALN+PTE improved bone quantity and quality, bone strength, bone turnover; and mitigated histological damage during glucocorticoid intervention and withdrawal.The therapeutic effect was better than that afforded by ALN alone. ALN+PTE reduced CTSK protein expression, promoted Runx2 mRNA and protein expression to varying extents, and more strongly inhibited bone resorption than did ALN alone. CONCLUSIONS The synergistic effect mediated by ALN+PTE reversed GIOP during DXM intervention and withdrawal via affecting CTSK and Runx2 expression at mRNA and protein levels.

Icariin ameliorates dexamethasone‑induced bone deterioration in an experimental mouse model via activation of microRNA‑186 inhibition of cathepsin K.

The present study aimed to investigate bone deterioration in glucocorticoid-induced osteoporosis (GIOP) mice, and the anti-osteoporosis effect and underlying molecular mechanism of icariin. Dexamethasone (DSM) treatment was demonstrated to facilitate the induction of hypercalciuria in GIOP mice. Icariin treatment reversed the dexamethasone (DXM)-induced disequilibrium of calcium homeostasis and bone resorption, and increased serum alkaline phosphatase, tartrate resistant acid phosphatase, osteocalcin and deoxypyridinoline. Haematoxylin and eosin staining revealed an increase in disconnections and separation in the trabecular bone network of the tibial proximal metaphysis, in the GIOP group. Icariin treatment reversed the DXM-induced trabecular deleterious effects, and stimulated bone remodeling in GIOP mice. Furthermore, the results demonstrated that the mRNA and protein expression of cathepsin K were significantly increased in GIOP mice, compared with the control group. Icariin treatment may suppress the expression of cathepsin K in the tibia of GIOP mice. The levels of microRNA (miR)-186 were markedly reduced in the tibia of GIOP mice compared with control group; however, this was inhibited by icariin treatment. Bioinformatics analysis demonstrated that miR-186 regulates cathepsin K via binding to the upstream 3′-untranslated region. Furthermore, transfection with miR-186 mimics resulted in inhibition of cathepsin K expression, whereas miR-186 inhibitors facilitated cathepsin K expression in osteoclasts. In conclusion, the present study demonstrated the protective effects of icariin against bone deteriorations in the experimental GIOP mice, and the underlying mechanism was mediated, at least partially, via activation of miR-186-mediated suppression of cathepsin K. These results provide evidence to support the use of icariin as a therapeutic approach in the management of glucocorticoid-induced bone loss, and the disequilibrium of calcium homeostasis.

Promotion effect of extracts from plastrum testudinis on alendronate against glucocorticoid-induced osteoporosis in rat spine

Alendronate (ALN) is a key therapeutic used to treat glucocorticoid-induced osteoporosis (GIOP), but may induce severe side effects. We showed earlier that plastrum testudinis extracts (PTE) prevented and treated GIOP in vivo. However, clinically, PTE is seldom used alone. Herein, we reveal the synergistic effect of ALN and PTE can treat GIOP of the rat spine and define the mechanism. Sprague-Dawley rats were randomly assigned to four groups: a vehicle group, a GIOP group, an ALN group, and an ALN+PTE group. Each group was further divided into two experimental phases, including dexamethasone (DXM) intervention and withdrawal. Bone mass, microarchitecture, biomechanics, bone-turnover markers, and histomorphology were evaluated. The mRNA and protein expression levels of CTSK and Runx2 were detemined. We found that ALN+PTE improved bone quantity and quality, bone strength, bone turnover; and mitigated histological damage during glucocorticoid intervention and withdrawal. The therapeutic effect was better than that afforded by ALN alone. ALN+PTE reduced CTSK protein expression, promoted Runx2 mRNA and protein expression to varying extents, and more strongly inhibited bone resorption than did ALN alone. Overall, the synergistic effect mediated by ALN+PTE reversed GIOP during DXM intervention and withdrawal via affecting CTSK and Runx2 expression at mRNA and protein levels.

Effects of 1,25-dihydroxyvitamin D3 on the local bone renin-angiotensin system in a murine model of glucocorticoid-induced osteoporosis.

Active vitamin D is closely related to the circulating renin-angiotensin system (RAS) in experimental animal models and humans; however, corresponding local bone data remain limited. The present study examined whether 1,25-dihydroxyvitamin D3 supplementation altered local bone RAS elements in a murine model of glucocorticoid-induced osteoporosis (GIOP). A total of 36 8-week-old mice were randomized into three equal-sized groups: The sham, GIOP and 1,25-dihydroxyvitamin D3 treatment groups. After 12 weeks, the cancellous bone microstructure of the third lumbar vertebra and left femur from the mice from each group were examined using micro-computed tomography. To access the impact of glucocorticoid use, the effect of 1,25-dihydroxyvitamin D3 on cancellous bone microstructure, the expression of bone turnover markers, circulation and expression of the main RAS components was assessed. Results demonstrated that bone volume fraction, trabecular number and trabecular thickness of the treatment and sham groups were significantly higher than the GIOP group (P<0.05). Furthermore, the structure model index, trabecular separation and bone surface to bone volume ratio of the sham and treatment groups were significantly reduced compared with the GIOP group (P<0.05). All assessed parameters exhibited no significant differences between the treatment and sham groups. mRNA expression levels of local bone angiotensin type 1 and 2 receptors and receptor activator of nuclear factor-κB ligand were significantly lower in the treatment group than in the GIOP group (P<0.05); however, there were no significant differences in circulating protein levels between the groups (P>0.05). In conclusion, 1,25-dihydroxyvitamin D3 may modulate bone metabolism by downregulating the local bone RAS in mice with GIOP.

Tetramethylpyrazine Protects Against Glucocorticoid-Induced Apoptosis by Promoting Autophagy in Mesenchymal Stem Cells and Improves Bone Mass in Glucocorticoid-Induced Osteoporosis Rats.

Glucocorticoid-induced osteoporosis (GIOP) is a widespread clinical complication due to the common use of glucocorticoids. Excess glucocorticoids induce apoptosis of bone marrow-derived mesenchymal stem cells (BMSCs), which have been shown to play an increasingly important role in the pathogenesis and therapy of osteoporosis. Tetramethylpyrazine (TMP), an extract from one of the most recognized herbs in traditional Chinese medicine (Chuanxiong), has been reported to have antiapoptotic properties. In this study, we tested whether TMP protects rat BMSCs following exposure to glucocorticoids in vitro and in vivo. We treated BMSCs with different concentrations of TMP (50, 100, or 200 μM) and exposed them to 10-6 M dexamethasone (Dex) for 48 h in vitro. Our data showed that TMP inhibited Dex-induced cytotoxicity and protected BMSCs from apoptosis. Interestingly, further results demonstrated that TMP prevented apoptosis in BMSCs by promoting autophagy in an AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway-dependent manner. In addition, calcein fluorescence double labeling and microcomputed tomography scanning indicated that 12 weeks of TMP administration augmented bone formation and protected trabecular bone mass in GIOP rats. We also discovered that first-passage BMSCs isolated from the TMP treatment group had a lower rate of apoptosis and a higher light chain 3 (LC3)-II/LC3-I ratio than the GIOP group. Our findings demonstrate for the first time that TMP can protect BMSCs from exposure to excess glucocorticoids by promoting autophagy through AMPK/mTOR pathway and might be an effective agent for the prevention and treatment of GIOP.

Histological Effect of Bisphosphonate, Vitamin D and Olive Oil on Glucocorticoid Induced Osteoporosis (GIO) in Albino Rat

Background: Previous studies demonstrated that the prevalence of osteoporosis was 4% in women aged 50 to 59 years compared to 44% in women aged 80 years and older. Osteoporosis may be primary or secondary. Glucocorticoid induced osteoporosis (GIO) is considered among the most common causes of secondary osteoporosis. The present study aimed to assess if vitamin D and olive oil could be useful in the treatment of GIO as bisphosphonate. Materials and Methods: Fifty adult female albino rats weighing 180-220 grams and aged 16-19 weeks were divided into five groups (each consists of ten rats): the control group, osteoporotic group, bisphosphonate group, vitamin D group and olive oil group. The first group served as a negative control group. The other four groups were injected subcutaneously by methyl-prednisolone (0.5 mg/kg/day - three times a week) for 60 days to induce osteoporosis (glucocorticoid induced osteoporosis “GIO”). One of the four groups served as a positive control group while other three groups were treated with oral bisphosphonate (0.84 mg/kg/day - five days a week), oral Vitamin D3 (0.1 ug/kg/day - five days a week) and oral Olive oil (0.1 ug/kg/day - five times a week) respectively for additional 60 days. At the end of the experiment, the right femur was removed from each rat and examined histologically after staining by hematoxylin and eosin stain as well as Masson's trichrome stain. The stained sections were photographed and analyzed to assess cortical bone thickness, osteocyte number and osteocyte lacunae. Results: By comparing the cortical thickness in all groups we detected a significant difference between bisphosphonate group and the control group, as well as between the GIO group and the control group. We also found a significant decrease in osteocyte number by comparing the GIO group to the control group. There was as a significant difference between vitamin D group and control group when we compared the number of osteocyte lacunae in all groups. Conclusion: GIO affects mainly the cortical bone thickness as well as the osteocyte number. Bisphosphonate is possibly the drug of choice in the treatment of osteoporosis especially by increasing the cortical bone thickness. Although olive oil acts also on increasing cortical bone thickness as well as bisphosphonates but it was less effective. On the other hand, vitamin D increases both; the cortical thickness and the osteocyte number moderately and may be used as a prophylactic agent against osteoporosis.

Study of vertebral refractures after percutaneous vertebroplasty in patients with glucocorticoid-induced osteoporosis

Objective To analyze the refracture after percutaneous vertebroplasty (PVP) in patient with Glucocorticoid-induced osteoporosis (GIO), whether the rate of refracture of patients with GIO after PVP higher than patients with primary osteoporosis, whether the PVP are the optimum treatment for those patients with GIO. Methods A total of 34 fractured patients with GIO and 178 patients with primary osteoporosis were included our study. The association between initial fracture and refractures after PVP were evaluated. The mean number of refractures after initial PVP that developed within 1 year between GIO group and primary osteoporosis group were compared. Results Relative risk (RR) of refracture for the patients with GIO was 1.926 compared with the patients with primary osteoporosis within 1 year.21.9% of patients with primary osteoporosis refractured whereas 52.9% of patients with GIO refractured within 1 year of initial PVP. The patients who are in the GIO group have more chance to get refracture compared with the primary osteoporosis group within 1 year of initial PVP. Conclusion The patients with GIO were more likely to have refracture compared with patients with primary osteoporosis within 1 year of initial PVP. Therefore, whether the PVP are the optimum treatment for those patients with GIO is also a controversial issue. Key words: Glucocorticoid-induced osteoporosis; Percutaneous vertebroplasty; Refracture

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

Previous studies suggest that oxytocin (OT) negatively modulates adipogenesis while promoting osteogenesis invitro. Because of its effects on marrow stromal cells, OT might have potential utility in therapy for glucocorticoid-induced osteoporosis (GIO). To explore the effects of OT on marrow adipogenesis in a rabbit model of GIO. 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. 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. Early OT treatment was sufficient to eliminate glucocorticoid-induced marrow adiposity.

English

Osteoporosis is one of the major problems facing older people of both sexes. This study was undertaken to investigate the synergistic effects of combination of statins and bisphosphonates in a glucocorticoid-induced osteoporosis (GIO) model. Thirty rats were divided into five groups; control group (I), GIO group (II) (given oral prednisolone, pred 30 mg/kg, per 2 days for 6 weeks), group III (treated by pred + risedronate, risedr 1mg/kg), group IV (treated by pred + simvastatin, sim 10 mg/kg) and group V (treated by pred +sim + risedr). Histological study of the femoral neck bone as well as biochemical assessments of serum alkaline phosphatase (ALP), carboxy-terminal collagen crosslinks (CTX), osteoprotegrin (OPG), leptin, Ca and phosphate were performed. The significant decreases in the trabecular bone thickness, area (p < 0.001), and the significant increase in bone marrow fat cells area (p < 0.001) detected in pred group, were corrected to be nearly similar to control values in groups III, IV and V. Groups that received sim showed better remodeled smoother surfaces bone trabeculae compared with other groups. Combination of sim + risedr shows a significant decrease of bone specific ALP in comparison to pred group (p < 0.05). Also, there was significant decrease of CTX in all treated groups in comparison to pred group (p < 0.05). On other hand, significant improvements of osteoprotegrin levels were noted in all treated groups (p < 0.05), however, there were insignificant changes in leptin levels among groups. In conclusion, addition of statins to bisphosphonate has qualitative rather than quantitative positive effect in experimental osteoporosis which might shorten the duration of therapy and increase efficacy when combined together. Key words: Statins, bisphosphonates, glucocorticoids, osteoporosis.

Local renin-angiotensin system is associated with bone mineral density of glucocorticoid-induced osteoporosis patients.

The local renin-angiotensin system (RAS) is closely related to bone metabolism. However, it is unknown whether the local RAS is related to bone mineral density (BMD) in glucocorticoid-induced osteoporosis (GIOP). Here, we revealed that the two main characteristics of GIOP might inhibit bone formation and enhance bone resorption. The aim of this study is to assess the expression of the main RAS components in the trabecular bone of lumbar vertebrae in GIOP and analyze the relationship between the major RAS components and BMD. We collected 96 inpatient cases of lumbar disc herniation from patients who underwent dual-energy X-ray absorptiometry examinations followed by surgical treatment in our hospital. Patients were divided into the GIOP group (n = 48) and control group (n = 48). The circulating and local expression levels of the main RAS components were examined. The correlation between the main RAS components and BMD was then analyzed. The mRNA expression of local bone angiotensin type 1 and 2 receptors (AT1R and AT2R, respectively) and RANKL was higher in the GIOP group compared with the control group (p < 0.001), but there was no difference in the circulating protein levels between groups (p > 0.05). Multiple logistic regression analysis revealed that AT1R and AT2R expression and the RANKL/OPG ratio in local bone were negatively associated with BMD (p < 0.001, odds ratio (OR) 1.236, 95 % confidence interval (CI) 1.207-1.333; p < 0.001, OR 1.971, 95% CI 1.809-2.233; and p < 0.001, OR 1.676, 95% CI 1.546-1.845, respectively). This study provides evidence that the role of local RAS is related to BMD in GIOP patients, and suggests that local RAS might influence RANKL/OPG signaling to modulate bone metabolism.

Influence of glucocorticoids on the osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells

BackgroundGlucocorticoid has been used extensively in clinical applications, because of its several pharmacologic actions, which include immunosuppression, anti-inflammation, anti-shock, and relief of asthma. However, the long-term or high-dose application of glucocorticoid can induce adverse effects such as osteoporosis, which is known in this case as glucocorticoid-induced osteoporosis (GIOP). It is a secondary osteoporosis that results in easy fracturing, and even disability. Therefore it became a thorny issue.MethodsThe rat model of glucocorticoid-induced osteoporosis (GIOP) was replicated to isolate BMSCs. Rats were assigned into four groups: normal, normal induction, GIOP, and GIOP induction. The growth cycle was monitored by using flow cytometry. Osteogenic differentiation was compared by using alkaline phosphatase (ALP) staining with a modified calcium cobalt method. The quantitative detection of osteoprotegerin and the receptor activator of nuclear factor kappa-B ligand (RANKL) was conducted by using enzyme-linked immunoassay. Finally, renal Klotho mRNA expression was assessed by using RT-PCR.ResultsBMSC proliferation was reduced in GIOP rats. The ALP-positive expression of normal BMSCs to the osteogenic induction solution was stronger than that of BMSCs from GIOP rats (P < 0.01). Osteoprotegerin expression was significantly higher in the normal induction group than in the normal, GIOP (P < 0.01), and GIOP induction groups (P < 0.05). RANKL expression was significantly higher in the normal induction group than in the other groups (P < 0.01) and significantly higher in the normal group than in the GIOP and GIOP induction groups (P < 0.01). RT-PCR analysis showed that renal Klotho mRNA expression was significantly reduced in the GIOP group compared with the normal group (P < 0.01).ConclusionBMSC proliferation, osteogenic differentiation, and reactive activity to an osteogenic inductor were reduced in GIOP rats. Klotho mRNA expression decreased during GIOP induction.

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

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