Vitamin D hormone inhibits osteoclastogenesis in vivo by decreasing the pool of osteoclast precursors in bone marrow

Vitamin D inhibits bone loss in mice with thyrotoxicosis by activating the OPG/RANKL and Wnt/β-catenin signaling pathways

OBJECTIVE

Vitamin D and thyroid hormones have crucial roles in bone metabolism. This study aims to explore the effects of vitamin D on bone metabolism in mice with thyrotoxicosis and its mechanisms.

METHODS

12-week-old mice were randomly divided into 6 groups (6 mice/group), the control (CON) group, vitamin D (VD) group, low-dose LT4 (Low LT4) group, low-dose LT4+VD (Low LT4+VD) group, high-dose LT4 (High LT4) group, high-dose LT4+VD (High LT4+VD) group, LT4 was provided every day and vitamin D3 every other day for 12 weeks. Thyroid function, 25-hydroxy vitamin D, type I collagen carboxy-terminal peptide (CTX), and type I procollagen amino-terminal peptide were determined. In addition, microcomputed tomography, bone histology and histomorphometry, a three-point bending test, and the mRNA expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL) and β-catenin in bone were conducted.

RESULTS

The BMD of lumbar vertebrae and femur decreased and the bone microstructure was destroyed significantly in thyrotoxicosis mice. Addition of vitamin D improved the BMD and bone microstructure only in the low LT4+VD group. Mice with thyrotoxicosis had a significantly higher level of CTX (P<0.05), which was decreased by treatment with vitamin D (P<0.05). The eroded surface per bone surface (Er. S/BS) of the cancellous bone and elongated surface/endocortical perimeter (Er. S/E Pm) of the cortical bone significantly increased in the Low LT4 and High LT4 groups (P<0.05). Treatment with vitamin D significantly decreased the Er. S/BS and Er. S/E Pm. But, treatment with vitamin D did not significantly improve the toughness and rigidity of bones. The ratio of OPG to RANKL and mRNA expression of β-catenin in the Low LT4+VD group were higher than that in the Low LT4 group (P<0.05).

CONCLUSION

In mice with thyrotoxicosis, treatment with vitamin D can inhibit bone resorption and improve the BMD and trabecular bone architecture by increasing the ratio of OPG to RANKL and upregulating the expression of Wnt/β-catenin.

Potential impact of the steroid hormone, vitamin D, on the vasculature

The role of vitamin D in the cardiovascular system is complex because it regulates expression of genes involved in diverse metabolic processes. Although referred to as a vitamin, it is more accurately considered a steroid hormone, because it is produced endogenously in the presence of ultraviolet light. It occurs as a series of sequentially activated forms, here referred to as vitamin D-hormones. A little-known phenomenon, based on pre-clinical data, is that its biodistribution and potential effects on vascular disease likely depend on whether it is derived from diet or sunlight. Diet-derived vitamin D-hormones are carried in the blood, at least in part, in chylomicrons and lipoprotein particles, including low-density lipoprotein. Since low-density lipoprotein is known to accumulate in the artery wall and atherosclerotic plaque, diet-derived vitamin D-hormones may also collect there, and possibly promote the osteochondrogenic mineralization associated with plaque. Also, little known is the fact that the body stores vitamin D-hormones in adipose tissue with a half-life on the order of months, raising doubts about whether the use of the term "daily requirement" is appropriate. Cardiovascular effects of vitamin D-hormones are controversial, and risk appears to increase with both low and high blood levels. Since low serum vitamin D-hormone concentration is reportedly associated with increased cardiovascular and orthopedic risk, oral supplementation is widely used, often together with calcium supplements. However, meta-analyses show that oral vitamin D-hormone supplementation does not protect against cardiovascular events, findings that are also supported by a randomized controlled trial. These considerations suggest that prevalent recommendations for vitamin D-hormone supplementation for the purpose of cardiovascular protection should be carefully reconsidered.

The Crossroads between Infection and Bone Loss

Bone homeostasis, based on a tight balance between bone formation and bone degradation, is affected by infection. On one hand, some invading pathogens are capable of directly colonizing the bone, leading to its destruction. On the other hand, immune mediators produced in response to infection may dysregulate the deposition of mineral matrix by osteoblasts and/or the resorption of bone by osteoclasts. Therefore, bone loss pathologies may develop in response to infection, and their detection and treatment are challenging. Possible biomarkers of impaired bone metabolism during chronic infection need to be identified to improve the diagnosis and management of infection-associated osteopenia. Further understanding of the impact of infections on bone metabolism is imperative for the early detection, prevention, and/or reversion of bone loss. Here, we review the mechanisms responsible for bone loss as a direct and/or indirect consequence of infection.

The Vitamin D Receptor in Osteoblast-Lineage Cells Is Essential for the Proresorptive Activity of 1α,25(OH)2D3 In Vivo

We previously reported that daily administration of a pharmacological dose of eldecalcitol, an analog of 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3], increased bone mass by suppressing bone resorption. These antiresorptive effects were found to be mediated by the vitamin D receptor (VDR) in osteoblast-lineage cells. Using osteoblast-lineage-specific VDR conditional knockout (Ob-VDR-cKO) mice, we examined whether proresorptive activity induced by the high-dose 1α,25(OH)2D3 was also mediated by VDR in osteoblast-lineage cells. Administration of 1α,25(OH)2D3 (5 μg/kg body weight/day) to wild-type mice for 4 days increased the number of osteoclasts in bone and serum concentrations of C-terminal crosslinked telopeptide of type I collagen (CTX-I, a bone resorption marker). The stimulation of bone resorption was concomitant with the increase in serum calcium (Ca) and fibroblast growth factor 23 (FGF23) levels, and decrease in body weight. This suggests that a toxic dose of 1α,25(OH)2D3 can induce bone resorption and hypercalcemia. In contrast, pretreatment of wild-type mice with neutralizing anti-receptor activator of NF-κB ligand (RANKL) antibody inhibited the 1α,25(OH)2D3-induced increase of osteoclast numbers in bone, and increase of CTX-I, Ca, and FGF23 levels in serum. The pretreatment with anti-RANKL antibody also inhibited the 1α,25(OH)2D3-induced decrease in body weight. Consistent with observations in mice conditioned with anti-RANKL antibody, the high-dose administration of 1α,25(OH)2D3 to Ob-VDR-cKO mice failed to significantly increase bone osteoclast numbers, serum CTX-I, Ca, or FGF23 levels, and failed to reduce the body weight. Taken together, this study demonstrated that the proresorptive, hypercalcemic, and toxic actions of high-dose 1α,25(OH)2D3 are mediated by VDR in osteoblast-lineage cells.

Effect of Vitamins D and E on the Proliferation, Viability, and Differentiation of Human Dental Pulp Stem Cells: An In Vitro Study

Introduction

The aim of the present study was to determine the effects of vitamins D and E on the proliferation, morphology, and differentiation of human dental pulp stem cells (hDPSCs).

Methods

In this in vitro experimental study, hDPSCs were isolated, characterized, and treated with vitamins D and E, individually and in combination, utilizing different doses and treatment periods. Changes in morphology and cell proliferation were evaluated using light microscopy and the resazurin assay, respectively. Osteoblast differentiation was evaluated with alizarin red S staining and expression of RUNX2, Osterix, and Osteocalcin genes using real-time RT-PCR.

Results

Compared with untreated cells, the number of cells significantly reduced following treatment with vitamin D (49%), vitamin E (35%), and vitamins D + E (61%) after 144 h. Compared with cell cultures treated with individual vitamins, cells treated with vitamins D + E demonstrated decreased cell confluence, with more extensive and flatter cytoplasm that initiated the formation of a significantly large number of calcified nodules after 7 days of treatment. After 14 days, treatment with vitamins D, E, and D + E increased the transcription of RUNX2, Osterix, and Osteocalcin genes.

Conclusions

Vitamins D and E induced osteoblastic differentiation of hDPSCs, as evidenced by the decrease in cell proliferation, morphological changes, and the formation of calcified nodules, increasing the expression of differentiation genes. Concurrent treatment with vitamins D + E induces a synergistic effect in differentiation toward an osteoblastic lineage.

Low energy irradiation of narrow-range UV-LED prevents osteosarcopenia associated with vitamin D deficiency in senescence-accelerated mouse prone 6

Deficiency of vitamin D is an important cause of osteosarcopenia. The purpose of this study is to examine the effects of low energy narrow-range UV-LED on osteosarcopenia in animal models of senescence-accelerated mouse prone 6 (SAMP6). Preliminary experiments specified the minimum irradiance intensity and dose efficacy for vitamin D production (316 nm, 0.16 mW/cm², 1,000 J/m²). we set a total of 4 groups (n = 8 per group); vitamin D-repletion without UV irradiation (Vit.D+UV-), vitamin D-repletion with UV irradiation (Vit.D+UV +), vitamin D-deficiency without UV irradiation, (Vit.D-UV-), and vitamin D-deficiency with UV irradiation (Vit.D-UV +). Serum levels of 25(OH)D at 28 and 36 weeks of age were increased in Vit.D-UV+ group as compared with Vit.D-UV- group. Trabecular bone mineral density on micro-CT was higher in Vit.D-UV+ group than in Vit.D-UV- group at 36 weeks of age. In the histological assay, fewer osteoclasts were observed in Vit.D-UV+ group than in Vit.D-UV- group. Grip strength and muscle mass were higher in Vit.D-UV+ group than in Vit.D-UV- group at 36 weeks of age. Signs of severe damage induced by UV irradiation was not found in skin histology. Low energy narrow-range UV irradiation may improve osteosarcopenia associated with vitamin D deficiency in SAMP6.

Effects of ultraviolet irradiation with a LED device on bone metabolism associated with vitamin D deficiency in senescence-accelerated mouse P6

Aims

This study investigated effects of narrow-range ultraviolet irradiation (UVR) by a new UV–LED device on vitamin D supply and changes of bone in senescence-accelerated mouse P6 (SAMP6) with vitamin D deficiency.

Main methods

We used female SAMP6 mice as a senile osteoporotic model. We set a total of 3 groups (n = 4 per group); D-UVR+ group (vitamin D deficient–dietary and UVR), D- (vitamin D deficient–dietary), and D+ groups (vitamin D contained–dietary). Mice in the D-UVR + group were UV–irradiated (305nm) with 1 kJ/m² twice a week for 12 weeks from 20 to 32 weeks of age. Serum 25(OH)D, 1,25(OH)₂D, and micro–computed tomography (CT) were assessed over time. Mechanical test, and histological assay were performed for femurs removed at 32 weeks of age.

Key findings

UVR increased both serum 25(OH)D and 1,25(OH)₂D levels at 4 and 8 weeks–UVR in the D-UVR+ group compared with that in the D- group (P < 0.05, respectively). Relative levels of trabecular bone mineral density in micro–CT were higher in the D-UVR+ group than in the D- group at 8 weeks–UVR (P = 0.048). The ultimate load was significantly higher in the D-UVR+ group than in the D- group (P = 0.036). In histological assay, fewer osteoclasts and less immature bone (/mature bone) could be observed in the D-UVR+ group than in the D- group, significantly.

Significance

UVR may have possibility to improve bone metabolism associated with vitamin D deficiency in SAMP6 mice.

Calcitriol Analogues Decrease Lung Metastasis but Impair Bone Metabolism in Aged Ovariectomized Mice Bearing 4T1 Mammary Gland Tumours

Calcitriol and its analogues are considered drugs supporting the anticancer treatment of breast cancer and preventing the osteoporosis that results from the development of cancer or from chemotherapy or hormone therapy. Following the orthotopic implantation of 4T1 mammary carcinoma cells into aged ovariectomized (OVX) mice, we evaluated the effects of calcitriol and its two analogues, PRI-2191 and PRI-2205, on metastatic spread and bone homeostasis. Calcitriol and its analogues temporarily inhibited the formation of metastases in the lungs. Unexpectedly, only mice treated with calcitriol analogues showed a deterioration of bone-related parameters, such as bone column density, marrow column density and the CaPO₄ coefficient. These findings correlated with an increased number of active osteoclasts differentiated from bone marrow-derived macrophages in mice treated with the analogues. Interestingly, in the tumours from mice treated with PRI-2191 and PRI-2205, the expression of Tnfsf11 (RANKL) was increased. On the other hand, osteopontin (OPN) levels in plasma and tumour tissue, as well as TRAC5b levels in tumours, were diminished by calcitriol and its analogues. Despite a similar action of both analogues towards bone metabolism, their impact on vitamin D metabolism differed. In particular, PRI-2191 and calcitriol, not PRI-2205 treatment significantly diminished the levels of both 25(OH)D₃ and 24,25(OH)₂D₃. In conclusion, though there is evident antimetastatic activity in old OVX mice, signs of increased bone metabolism and deterioration of bone mineralization during therapy with calcitriol analogues were observed.

Responses of primary osteoblasts and osteoclasts from hemizygous β-globin knockout thalassemic mice with elevated plasma glucose to 1,25-dihydroxyvitamin D3

β-thalassemia is often associated with hyperglycemia, osteoporosis and increased fracture risk. However, the underlying mechanisms of the thalassemia-associated bone loss remain unclear. It might result from abnormal activities of osteoblasts and osteoclasts, and perhaps prolonged exposure to high extracellular glucose. Herein, we determined the rate of duodenal calcium transport in hemizygous β-globin knockout thalassemic (BKO) mice. Their bones were collected for primary osteoblast and osteoclast culture. We found that BKO mice had lower calcium absorption than their wild-type (WT) littermates. Osteoblasts from BKO mice showed aberrant expression of osteoblast-specific genes, e.g., Runx2, alkaline phosphatase and osteocalcin, which could be partially restored by 1,25(OH)₂D₃ treatment. However, the mRNA expression levels of RANK, calcitonin receptor (Calcr), c-Fos, NFATc1, cathepsin K and DMT1 were similar in both BKO and WT groups. Exposure to high extracellular glucose modestly but significantly affected the expression of osteoclast-specific markers in WT osteoclasts with no significant effect on osteoblast-specific genes in WT osteoblasts. Thus, high glucose alone was unable to convert WT bone cells to BKO-like bone cells. In conclusion, the impaired calcium absorption and mutation-related aberrant bone cell function rather than exposure to high blood glucose were likely to be the principal causes of thalassemic bone loss.

Eldecalcitol, an active vitamin D analog, effectively prevents cyclophosphamide-induced osteoporosis in rats

Cyclophosphamide (CTX) as an alkylating agent is used for treating a range of tumor types and allergic diseases. However, high-dose application may induce rapid bone loss and increase the risk of osteoporotic fractures. Eldecalcitol (ED-71), a clinically approved active vitamin D analog, has been approved for osteoporosis treatment. It potently inhibited bone resorption while maintaining osteoblastic function in estrogen-deficient and high-turnover osteoporosis in model rats. The aim of the present study was to clarify the treatment effect of ED-71 on bone loss in a well-established rat model of osteoporosis with CTX administration. After 15 days of CTX treatment, ED-71 was administered, while estradiol valerate (E2V) was used as a positive control. At 2 and 4 weeks after ED-71 or E2V administration, rats were sacrificed and fixed. The tibiae were extracted for histochemical analysis using hematoxylin and eosin staining and immunohistochemistry. When compared with the untreated control group, the CTX group displayed clear osteoporotic features, including a decreased number of bone trabeculae and increased trabecular separation. ED-71 and E2V successfully rescued CTX-induced bone loss. The ED-71 group displayed denser and increasingly mature trabecular bone than the E2V group. Furthermore, ED-71 administration led to significant suppression of tartrate-resistant acid phosphatase (TRAP), cathepsin K (CK), matrix metalloproteinase 9 (MMP9), alkaline phosphatase (ALP) and Osteopontin (OPN), which was less pronounced than in E2V administration but was similar to the values exhibited in the normal control group. These results indicated that ED-71 had a moderate and increased effect on bone turnover compared with E2V. Therefore, the present study suggests that ED-71 is a potential inhibitor of CTX-induced osteoporosis, successfully rescuing bone loss without excessively suppressing bone turnover, and may be a suitable treatment for preventing bone loss in patients receiving CTX.

Calcitriol treatment in patients with low vitamin D levels

The aim of the the study is to compare the effects of cholecalciferol and calcitriol on bone mineral metabolism in women with vitamin D deficiency. Calcitriol was associated with a significant increase in bone mineral density at the lumbar spine in patients with low vitamin D levels.

PURPOSE/INTRODUCTION

Active vitamin D analogs may have larger impact in decreasing bone loss and fracture rate compared to cholecalciferol in osteoporosis. However, their effects in the treatment of vitamin D deficiency compared to cholecalciferol are not clear. The aim of the present study is to compare the effects of cholecalciferol and calcitriol on bone mineral metabolism and bone mineral density in pre- and postmenopausal women with vitamin D deficiency.

METHODS

This was a 6-month prospective, open-label, controlled clinical trial. Eligible 120 participants were pre- and postmenopausal women diagnosed with vitamin D deficiency. Forty-three subjects (group 1) received 1000 IU of cholecalciferol and 1 g of calcium daily. The other 77 subjects (group 2) received 0.5 μg calcitriol in addition to 400 IU of cholecalciferol and 1 g of calcium daily.

RESULTS

Oral vitamin D supplementation did not increase bone mineral density after 6 months of intervention in group 1. On the other hand, bone mineral density at the lumbar spine increased from 0.809 ± 0.172 to 0.848 ± 0.161 g/cm² in group 2 patients (p < 0.017 vs baseline).

CONCLUSIONS

Oral daily calcitriol was associated with a significant increase in bone mineral density at the lumbar spine in patients with low vitamin D, elevated PTH, and osteoporosis.

Pharmacologic Calcitriol Inhibits Osteoclast Lineage Commitment via the BMP-Smad1 and IκB-NF-κB Pathways

Vitamin D is involved in a range of physiological processes and its active form and analogs have been used to treat diseases such as osteoporosis. Yet how vitamin D executes its function remains unsolved. Here we show that the active form of vitamin D calcitriol increases the peak bone mass in mice by inhibiting osteoclastogenesis and bone resorption. Although calcitriol modestly promoted osteoclast maturation, it strongly inhibited osteoclast lineage commitment from its progenitor monocyte by increasing Smad1 transcription via the vitamin D receptor and enhancing BMP-Smad1 activation, which in turn led to increased IκBα expression and decreased NF-κB activation and NFATc1 expression, with IκBα being a Smad1 target gene. Inhibition of BMP type I receptor or ablation of Bmpr1a in monocytes alleviated the inhibitory effects of calcitriol on osteoclast commitment, bone resorption, and bone mass augmentation. These findings uncover crosstalk between the BMP-Smad1 and RANKL-NF-κB pathways during osteoclastogenesis that underlies the action of active vitamin D on bone health. © 2017 American Society for Bone and Mineral Research.

Plasmodium products persist in the bone marrow and promote chronic bone loss

Although malaria is a life-threatening disease with severe complications, most people develop partial immunity and suffer from mild symptoms. However, incomplete recovery from infection causes chronic illness, and little is known of the potential outcomes of this chronicity. We found that malaria causes bone loss and growth retardation as a result of chronic bone inflammation induced by Plasmodium products. Acute malaria infection severely suppresses bone homeostasis, but sustained accumulation of Plasmodium products in the bone marrow niche induces MyD88-dependent inflammatory responses in osteoclast and osteoblast precursors, leading to increased RANKL expression and overstimulation of osteoclastogenesis, favoring bone resorption. Infection with a mutant parasite with impaired hemoglobin digestion that produces little hemozoin, a major Plasmodium by-product, did not cause bone loss. Supplementation of alfacalcidol, a vitamin D3 analog, could prevent the bone loss. These results highlight the risk of bone loss in malaria-infected patients and the potential benefits of coupling bone therapy with antimalarial treatment.

The effect of bisphosphonate treatment on osteoclast precursor cells in postmenopausal osteoporosis: The TRIO study

Bisphosphonates are used to treat bone disease characterised by increased bone resorption by inhibiting the activity of mature osteoclasts, resulting in decreased bone turnover. Bisphosphonates may also reduce the population of osteoclast precursor cells. Our aims were to investigate the effect of bisphosphonates on i) osteoclast precursor cells and ii) circulating cytokine and cytokine receptor in postmenopausal women with osteoporosis compared with healthy premenopausal women. Participants were 62 postmenopausal women (mean age 66) from a 48-week parallel group trial of bisphosphonates. They received ibandronate 150mg/month (n=22), alendronate 70mg/week (n=19) or risedronate 35mg/week (n=21). Fasting blood was collected at baseline, weeks 1 and 48. At baseline, blood was also collected from 25 healthy premenopausal women (mean age 37) to constitute a control group. Peripheral blood mononuclear cells were extracted and stained for CD14, M-CSFR, CD11b and TNFRII receptors. Flow cytometry was used to identify cells expressing CD14⁺ and M-CSFR⁺ or CD11b⁺ or TNFRII⁺. RANKL and OPG were measured to evaluate potential mediation of the bisphosphonate effect. After 48weeks of treatment, there was a decrease in the percentage of cells expressing M-CSFR and CD11b receptors by 53% and 49% respectively (p<0.01). Cells expressing M-CSFR and CD11b were decreased with ibandronate and risedronate after 48weeks to the lower part of the premenopausal reference interval. These effects were not significantly different between each of the treatment groups. There was no significant effect on RANKL and OPG throughout the study period. Bisphosphonates inhibit bone resorption in the short-term by direct action on mature osteoclasts. There is also a later effect mediated in part by a reduction in the population of circulating osteoclast precursors.

Inhibitory effect of 1,25-dihydroxyvitamin D3 on Porphyromonas gingivalis-induced inflammation and bone resorption in vivo

OBJECTIVE

To investigate whether intragastric administration of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) could inhibit the bone resorption and inflammation in a mouse calvarial model infected by Porphyromonas gingivalis (P. gingivalis).

DESIGN

Live P. gingivalis ATCC 33277 was injected once daily for 6days into the subcutaneous tissue overlying the calvaria in mice. At the same time, 1,25(OH)₂D₃ (50μg/kg per day) was administered by gavage for 9days, starting 3d before the infection. Mice were killed under ether anesthesia 8h after the last injection of P. gingivalis. Micro-computed tomography scanning was used to evaluate calvarial bone loss. Tartrate-resistant acid phosphatase was used to detect osteoclast activity. Real-time PCR was used to assess the mRNA expressions of OPG, RANKL, c-Fos, NFATc1, CTSK and TRAP in calvarial bone and IL-6, IL-10, IL-1β, IL-12p40 and TNF-α in soft tissue. The levels of serum IL-6, IL-10 were determined by ELISA.

RESULTS

1,25(OH)₂D₃ treatment apparently attenuated bone resorption in P. gingivalis-induced mouse calvarial model and markedly reduced the number of osteoclasts. The expression levels of RANKL and osteoclast-related genes such as c-Fos, NFATc1, CTSK and TRAP were also decreased by 1,25(OH)₂D₃. Besides, 1,25(OH)₂D₃ inhibited the expression of pro-inflammatory cytokines IL-6, IL-12p40 and TNF-α and enormously elevated the expression of anti-inflammatory cytokine IL-10.

CONCLUSION

1,25(OH)₂D₃ may decrease bone resorption in vivo via suppressing the expression of osteoclast-related genes and its anti-inflammatory properties.

Short-range ultraviolet irradiation with LED device effectively increases serum levels of 25(OH)D

Impairment of the activities of daily living (ADL) by osteoporosis is an important concern in developed countries with a super-aging population. Vitamin D, which is a crucial molecule in bone metabolism and mainly produced endogenously with ultraviolet (UV) light exposure, is known to be insufficient in the elderly population. We used an UV Light-Emitting Diode (UV-LED) instrument generating a narrow-range wavelength to analyze the efficacy of endogenous vitamin D production. The primary purpose of this study was to examine the effects of UV irradiation at various narrow-range wavelengths using UV-LED on vitamin D supplementation. The second one was to clarify the short-term effects of UV irradiation on bone morphology in mice. Vitamin D-starved C57BL/6 female mice (n=7 per group) were UV-irradiated (268nm, 282nm, 290nm, 305nm, and 316nm) with 1kJ/m² twice a week for 4weeks. UV irradiation using UV-LED had significant effects on increasing serum 25(OH)D levels in all wavelength groups (P<0.001, all groups) as compared to a control group. Among irradiated groups, wavelength of 316nm had a less marked effect on 25(OH)D production compared with other wavelengths at 1week of UV irradiation (P<0.05). Levels of 1,25(OH)₂D were significantly increased after 4weeks irradiation with UV-B or UV-C irradiation (P<0.05). mRNA levels of vitamin D 25-hydroxylase were increased with UV-B or UV-C irradiation (268nm-305nm), significantly. Micro-CT examination revealed that short-term (4weeks) UV-irradiation did not induce morphological change of mice in any group. This study provides essential information that narrow-range UV irradiation with LED can increase the endogenous production of vitamin D, and mRNA levels of the responsible enzyme. Although bone morphology was not altered by short-term UV irradiation in this study, an increase of serum vitamin D might improve bone morphology with long-term irradiation.

Effects of macroporous, strontium loaded xerogel-scaffolds on new bone formation in critical-size metaphyseal fracture defects in ovariectomized rats

New bone formation was studied in a metaphyseal fracture-defect in ovariectomized rats stimulated by a plain and a strontium-enriched macroporous silica/collagen scaffold (ScB30 and ScB30Sr20) and a compact silica/collagen xerogel (B30). 45 female Sprague-Dawley rats were randomly assigned to three different treatment groups: (1) ScB30 (n=15), (2) ScB30Sr20 (n=15), and (3) B30 (n=15). 12 weeks after bilateral ovariectomy and multi-deficient diet, a 4 mm wedge-shaped fracture-defect was created at the metaphyseal area of the left femur. A 7-hole T-shaped plate at the lateral aspect of the femur stabilized the bone and the defect was filled with ScB30, ScB30Sr20 or B30 subsequently. After six weeks, histomorphometrical analysis revealed a statistically significant higher bone volume/tissue volume ratio in the ScB30Sr20 group compared to ScB30 (p=0.043) and B30 (p=0.0001) indicating an improved formation of new bone by the strontium-enriched macroporous silica/collagen scaffold. Furthermore, immunohistochemical results showed increased expression of BMP2 and OPG and a decreased RANKL expression in the ScB30Sr20 group. This was further confirmed with the gene expression analysis where an increase in prominent bone formation markers (ALP, OCN, Runx2, Col1a1 and Col10a1) was seen. No material remnants were found in the scaffold group indicating an almost complete degradation process of the biomaterials. This is confirmed by ToF-SIMS analysis that did not detect any strontium in the ScB30Sr20 group neither in the defect nor in the surrounding tissue. Taken together, this study shows the stimulating effects of strontium through increased bone formation by up regulation of osteoanabolic markers. This work also indicates the importance of material porosity, geometry and biodegradability in bone healing.

The Breast Cancer to Bone (B2B) Metastases Research Program: a multi-disciplinary investigation of bone metastases from breast cancer

Background

Bone is the most common site of breast cancer distant metastasis, affecting 50–70 % of patients who develop metastatic disease. Despite decades of informative research, the effective prevention, prediction and treatment of these lesions remains elusive. The Breast Cancer to Bone (B2B) Metastases Research Program consists of a prospective cohort of incident breast cancer patients and four sub-projects that are investigating priority areas in breast cancer bone metastases. These include the impact of lifestyle factors and inflammation on risk of bone metastases, the gene expression features of the primary tumour, the potential role for metabolomics in early detection of bone metastatic disease and the signalling pathways that drive the metastatic lesions in the bone.

Methods/Design

The B2B Research Program is enrolling a prospective cohort of 600 newly diagnosed, incident, stage I-IIIc breast cancer survivors in Alberta, Canada over a five year period. At baseline, pre-treatment/surgery blood samples are collected and detailed epidemiologic data is collected by in-person interview and self-administered questionnaires. Additional self-administered questionnaires and blood samples are completed at specified follow-up intervals (24, 48 and 72 months). Vital status is obtained prior to each follow-up through record linkages with the Alberta Cancer Registry. Recurrences are identified through medical chart abstractions. Each of the four projects applies specific methods and analyses to assess the impact of serum vitamin D and cytokine concentrations, tumour transcript and protein expression, serum metabolomic profiles and in vitro cell signalling on breast cancer bone metastases.

Discussion

The B2B Research Program will address key issues in breast cancer bone metastases including the association between lifestyle factors (particularly a comprehensive assessment of vitamin D status) inflammation and bone metastases, the significance or primary tumour gene expression in tissue tropism, the potential of metabolomic profiles for risk assessment and early detection and the signalling pathways controlling the metastatic tumour microenvironment. There is substantial synergy between the four projects and it is hoped that this integrated program of research will advance our understanding of key aspects of bone metastases from breast cancer to improve the prevention, prediction, detection, and treatment of these lesions.

[Expression and function of the histamine receptors in dermal and articular tissues]

Histamine was first identified in 1910 as a physiologically active amine. It is now recognized for its multiple regulatory activities in the digestive, neuronal, and immune systems, and new roles are still being elucidated. Histamine exerts its effects through four distinct receptor subtypes. The histamine H4 receptor was identified in 2000 and is the most recently identified of the four histamine receptors. It is expressed primarily in immune cells and is involved in physiologic functions related to inflammation and allergy. Recently, the H4 receptor was highlighted as a promising therapeutic target in atopic dermatitis, asthma, and chronic arthritis. In fact, some H4 receptor antagonists have reached clinical trials for the treatment of asthma, atopic dermatitis, and allergic rhinitis. Based on an initial assessment of its distribution, the H4 receptor has been referred to as the histamine receptor of the hematopoietic system. However, the H4 receptor has also been implicated in the regulation of other non-hematopoietic systems. Here, I review the expression and function of the identified histamine receptors, including the H4 receptor with a focus on articular and dermal tissues. In articular tissue, H4 receptor expression has been detected in synovial cells. Chondrocytes, a major cell source for cartilage tissue engineering, also express the H4 receptor. In skin, the H4 receptor is expressed in both the epidermis and dermis, with stronger receptor expression in the epidermis. Further understanding of the functions of H4 receptors in non-hematopoietic cells might lead to novel treatments for diseases with unmet medical needs.

Physiological functions of vitamin D: what we have learned from global and conditional VDR knockout mouse studies

The physiological role of vitamin D depends on calcium supply and calcium balance. When the calcium balance is normal, the major target of vitamin D is intestine. Vitamin D stimulates mainly active intestinal calcium transport mechanism. During a negative calcium balance, bone effects of vitamin D become dominant. Thus, the role of vitamin D in maintaining normocalcemia appears to have priority over skeletal integrity in these situations.

In vivo deletion of CAR resulted in high bone mass phenotypes in male mice

Constitutive androstane receptor (CAR) was originally identified as xenobiotic sensor that regulates the expression of cytochrome P450 genes. However, recent studies suggest that this nuclear receptor is also involved in the regulation of energy metabolism including glucose and lipid homeostasis. This study investigated the role of CAR in the regulation of bone mass in vivo using CAR(-/-) mice. Endogenous mRNA expression of CAR was observed in both primary osteoblasts and osteoclast precursors. CAR(-/-) mice have exhibited significant increase in whole body bone mineral density (BMD) by 9.5% (P < 0.01) and 5.5% (P < 0.05) at 10 and 15 weeks of age, respectively, compared with WT mice in males. Microcomputed tomography analysis of proximal tibia demonstrated a significant increase in trabecular bone volume (62.7%), trabecular number (54.1%) in male CAR(-/-) mice compared with WT mice. However, primary culture of calvarial cells exhibited no significant changes in osteogenic differentiation potential between CAR(-/-) and WT. In addition, the number of tartrate-resistant acid-phosphatase positive osteoclasts in the femur and serum level of CTx was not different between CAR(-/-) and WT mice. The higher BMD and microstructural parameters were not observed in female mice. Interestingly, serum level of testosterone in male CAR(-/-) mice was 2.5-fold higher compared with WT mice and the mRNA expressions of Cyp2b9 and 2b10 in the liver, which regulate testosterone metabolism, were significantly down-regulated in male CAR(-/-) mice. Furthermore, the difference in BMD between CAR(-/-) and WT mice disappeared at 8 weeks after performing orchiectomy. CAR(-/-) mice also exhibited significant increase in serum 1,25(OH)2 D3 levels but Cyp 27B1 which converts 25(OH)D3 to 1,25(OH)2 D3 was significantly down-regulated compared to WT mice. These results suggest that in vivo deletion of CAR resulted in higher bone mass, which appears to be a result from reduced metabolism of testosterone due to down-regulation of Cyp2b.

Differences of bone healing in metaphyseal defect fractures between osteoporotic and physiological bone in rats

Discrepancies in bone healing between osteoporotic and non-osteoporotic bone remain uncertain. The focus of the current work is to evaluate potential healing discrepancies in a metaphyseal defect model in rat femora. Female Sprague-Dawley rats were either ovariectomized (OVX, n=14) and combined with a calcium-, phosphorus- and vitamin D3-, soy- and phytoestrogen-free diet or received SHAM operation with standard diet rat (SHAM, n=14). Three months post-ovariectomy, DEXA measurement showed a reduction of bone mineral density reflecting an osteoporotic bone status in OVX rats. Rats then underwent a 3 mm wedge-shaped osteotomy at the distal metaphyseal area of the left femur stabilized with a T-shaped mini-plate and allowed to heal for 6 weeks. Biomechanical competence by means of a non-destructive three-point bending test showed significant lower flexural rigidity in the OVX rats at 3 mm lever span compared to SHAM animals (p=0.048) but no differences at 10 mm lever span. Microcomputer tomography (μCT) showed bridging cortices and consolidation of the defect in both groups, however, no measurable differences were found in either total ossified tissue or vascular volume fraction. Furthermore, histology showed healing discrepancies that were characterized by cartilaginous remnant and more unmineralized tissue presence in the OVX rats compared to more mature consolidation appearance in the SHAM group. In summary, bone defect healing in metaphyseal bone slightly differs between osteoporotic and non-osteoporotic bone in the current 3 mm defect model in both 3mm lever span biomechanical testing and histology.

Differential roles of MAPK kinases MKK3 and MKK6 in osteoclastogenesis and bone loss

Bone mass is maintained by osteoclasts that resorb bone and osteoblasts that promote matrix deposition and mineralization. Bone homeostasis is altered in chronic inflammation as well as in post-menopausal loss of estrogen, which favors osteoclast activity that leads to osteoporosis. The MAPK p38α is a key regulator of bone loss and p38 inhibitors preserve bone mass by inhibiting osteoclastogenesis. p38 function is regulated by two upstream MAPK kinases, namely MKK3 and MKK6. The goal of this study was to assess the effect of MKK3- or MKK6-deficiency on osteoclastogenesis in vitro and on bone loss in ovariectomy-induced osteoporosis in mice. We demonstrated that MKK3 but not MKK6, regulates osteoclast differentiation from bone marrow cells in vitro. Expression of NFATc1, a master transcription factor in osteoclastogenesis, is decreased in cells lacking MKK3 but not MKK6. Expression of osteoclast-specific genes Cathepsin K, osteoclast-associated receptor and MMP9, was inhibited in MKK3−/− cells. The effect of MKK-deficiency on ovariectomy-induced bone loss was then evaluated in female WT, MKK3−/− and MKK6−/− mice by micro-CT analysis. Bone loss was partially inhibited in MKK3−/− as well as MKK6−/− mice, despite normal osteoclastogenesis in MKK6−/− cells. This correlated with the lower osteoclast numbers in the MKK-deficient ovariectomized mice. These studies suggest that MKK3 and MKK6 differentially regulate bone loss due to estrogen withdrawal. MKK3 directly mediates osteoclastogenesis while MKK6 likely contributes to pro-inflammatory cytokine production that promotes osteoclast formation.

Effects of multi-deficiencies-diet on bone parameters of peripheral bone in ovariectomized mature rat

Many postmenopausal women have vitamin D and calcium deficiency. Therefore, vitamin D and calcium supplementation is recommended for all patients with osteopenia and osteoporosis. We used an experimental rat model to test the hypothesis that induction of osteoporosis is more efficiently achieved in peripheral bone through combining ovariectomy with a unique multi-deficiencies diet (vitamin D depletion and deficient calcium, vitamin K and phosphorus). 14-week-old Sprague-Dawley rats served as controls to examine the initial bone status. 11 rats were bilaterally ovariectomized (OVX) and fed with multi-deficiencies diet. Three months later the treated group and the Sham group (n = 8) were euthanized. Bone biomechanical competence of the diaphyseal bone was examined on both, tibia and femur. Image analysis was performed on tibia via µCT, and on femur via histological analysis. Lower torsional stiffness indicated inferior mechanical competence of the tibia in 3 month OVX+Diet. Proximal metaphyseal region of the tibia showed a diminished bone tissue portion to total tissue in the µCT despite the increased total area as evaluated in both µCT and histology. Cortical bone showed higher porosity and smaller cross sectional thickness of the tibial diaphysis in the OVX+Diet rats. A lower ALP positive area and elevated serum level of RANKL exhibited the unbalanced cellular interaction in bone remodeling in the OVX+Diet rat after 3 month of treatment. Interestingly, more adipose tissue area in bone marrow indicated an effect of bone loss similar to that observed in osteoporotic patients. Nonetheless, the presence of osteoid and elevated serum level of PTH, BGP and Opn suggest the development of osteomalacia rather than an osteoporosis. As the treatment and fracture management of both osteoporotic and osteomalacia patients are clinically overlapping, this study provides a preclinical animal model to be utilized in local supplementation of minerals, drugs and growth factors in future fracture healing studies.

Suppressive effects of the leaf of Terminalia catappa L. on osteoclast differentiation in vitro and bone weight loss in vivo

Oral administration of Terminalia catappa extract (TCE; 1,000 mg/kg) for 5 wk suppressed bone weight loss and trabecular bone loss in ovariectomized mice. An in vitro experiment showed that TCE (1.3-20 µg/mL) did not increase alkaline phosphatase activity, which would indicate osteoclast formation, in osteoblast-like 3T3-L1 cells. On the other hand, TCE (12.5 µg/mL) markedly decreased the number of tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells, which would indicate osteoclast formation, in a co-culture system (bone marrow cells/osteoblastic UAMS-32 cells). A detailed analysis of the stages of osteoclast differentiation revealed that TCE mainly suppressed the differentiation of bone marrow mononuclear cells into osteoclast progenitor cells in the presence of M-CSF and TGF-β. An additional experiment using fractionated TCE revealed that the water-soluble fraction suppressed the bone weight loss in OVX-mice and osteoclast differentiation in vitro. Therefore, the suppressive effects of TCE on bone weight loss in mice might be due to the suppressive effects of highly polar components on the early stage of osteoclast differentiation.

1,25Dihydroxy vitamin D(3) improves titanium implant osseointegration in osteoporotic rats

OBJECTIVE

This study aimed to investigate the effects of 1,25(OH)(2)D(3) on implant osseointegration in osteoporotic rats.

STUDY DESIGN

Twelve weeks after bilateral ovariectomy, each rat had 2 titanium screws implanted in the proximal tibiae. All animals were then randomly divided into 2 groups: control (10 rats) and 1,25(OH)(2)D(3) (10 rats). 1,25(OH)(2)D(3) was administered through oral gavage at 0.1 μg/kg/d, and control animals were given vehicle. Eight weeks later, tibiae with screws were harvested for μCT, histologic, and biomechanical analysis.

RESULTS

Compared with control, 1,25(OH)(2)D(3) increased percent bone volume by 96.0%, percent osseointegration by 94.4%, mean trabecular number by 112.5%, mean trabecular thickness by 51.8%, trabecular connective density by 38.0%, and decreased trabecular separation by 39.3% in μCT analysis. The 1,25(OH)(2)D(3) increased bone area density by 1.2-fold and bone-to-implant contact by 1.5-fold in histomorphometry, and increased the maximal push-out force by 2.0-fold in biomechanical test.

CONCLUSIONS

The 1,25(OH)(2)D(3) improves implant osseointegration in osteoporotic rats.

Combination therapy with eldecalcitol and alendronate has therapeutic advantages over monotherapy by improving bone strength

Eldecalcitol (ED-71), a 2β-hydroxypropyloxy derivative of 1α,25(OH)(2)D(3), inhibits bone resorption more potently than does alfacalcidol while maintaining osteoblastic function in an estrogen-deficient, high-turnover osteoporosis rat model. Alendronate (ALN) has been reported to increase bone mass by suppressing bone resorption mainly by inducing apoptosis of osteoclasts. The aim of this study was to clarify the combination effect of ED-71 and ALN on bone loss in ovariectomized rats. Wistar-Imamichi rats (32weeks old) were ovariectomized and randomly assigned to 10 groups (n=9-11); 11 rats were sham-operated. Rats were orally administered either vehicle alone, ALN (0.05, 0.2mg/kg), ED-71 (0.015, 0.03μg/kg), or a combination of ALN and ED-71. The treatment started 2weeks after surgery and continued for 12weeks. ED-71 significantly increased calcium and phosphorus in serum and urine; however, the mean values were within the normal range. Bone mineral density (BMD) and maximum load in both the lumbar spine and femur significantly increased with ED-71 monotherapy, and showed a tendency to increase with ALN monotherapy. Compared with ALN monotherapy, the combination of ALN and ED-71 significantly increased BMD and maximum load in both the lumbar spine and femur, suggesting that the combination therapy is more beneficial than ALN monotherapy in this protocol. The combination treatment had an additive suppressive effect on eroded surface and osteoclast number, with the suppressive effect more potent than either ALN or ED-71 monotherapy. Moreover, the combination therapy partially counteracted the suppressive effects of ALN on bone formation and on the histomorphometric indices of osteoblast number and activity. Interestingly, ALN had no effect on the anabolic action of ED-71. In conclusion, the combination therapy of ALN and ED-71 has therapeutic advantages over ALN monotherapy in terms of improving bone mechanical strength without excessive suppression of bone turnover.

Women with insufficient 25-hydroxyvitamin D without secondary hyperparathyroidism have altered bone turnover and greater incidence of vertebral fractures

BACKGROUND

The connection of 25-hydroxyvitamin D [25(OH)D] with bone metabolism is reported to occur indirectly through parathyroid hormone (PTH) activity. However, we hypothesized that 25(OH)D insufficiency raises the risk of bone fracture independent of PTH, since 25(OH)D insufficiency is not always accompanied by hyperparathyroidism. The aim of this study was to show a direct association between 25(OH)D, bone turnover markers, and fractures that was independent of PTH.

METHODS

We measured serum 25(OH)D in a group of 330 postmenopausal osteoporotic women who did not have secondary hyperparathyroidism. We analyzed the effects of 25(OH)D insufficiency [25(OH)D < 20 ng/mL] on the expression of several bone markers, including serum bone alkaline phosphatase (BAP), osteocalcin (OC), urinary N-terminal telopeptide of type-I collagen and free deoxypyridinoline (DPD), and inorganic phosphorus (IP), as well as on the prevalence of vertebral fractures.

RESULTS

OC/BAP ratios and IP levels were significantly lower and DPD was significantly higher in 25(OH)D insufficient patients. These effects were independent of age, PTH, and estimated glomerular filtration rate (eGFR). 25(OH)D insufficiency, a low OC/BAP ratio, and low IP were related to the presence of prior vertebral fractures independent of PTH, bone mineral density (BMD), and eGFR.

CONCLUSIONS

We propose that 25(OH)D insufficiency is associated with a low OC/BAP ratio and high DPD in postmenopausal osteoporosis patients without hyperparathyroidism. This pathological condition is associated with an increased incidence of prior vertebral fractures independent of PTH, BMD, and eGFR.

Eldecalcitol, a second-generation vitamin D analog, drives bone minimodeling and reduces osteoclastic number in trabecular bone of ovariectomized rats

To elucidate the histological events that follow administration of eldecalcitol, a second-generation of vitamin D analog currently awaiting approval as a drug for treatment of osteoporosis, we employed the ovariectomy (OVX) rat model. OVX rats received vehicle or 30ng/kg of eldecalcitol, and sham-operated animals received vehicle only. Rats were sacrificed after 12weeks and had their femora and tibiae removed and processed for histochemical and histomorphometrical analyses. When compared with OVX group, osteoclastic number and bone resorption parameters were significantly reduced in eldecalcitol-treated rats, accompanied by decreased bone formation parameters. The preosteoblastic layer, with which osteoclastic precursors interact for mutual differentiation, was poorly developed in the eldecalcitol group, indicating less cell-to-cell contact between preosteoblasts and osteoclast precursors. Interestingly, eldecalcitol did promote a type of focal bone formation that is independent of bone resorption, a process known as bone minimodeling. While the number of ED-1-positive macrophages was higher in the bone marrow of treated rats, though osteoclastic number was deceased. Taken together, our findings suggest that eldecalcitol stimulates preosteoblastic differentiation rather than their proliferation, which in turn may prevent or diminish cell-to-cell contact between preosteoblasts and osteoclastic precursors, and therefore, lead to lower osteoclast numbers and decreased bone resorption.

Overcoming resistance to bisphosphonates through the administration of alfacalcidol: results of a 1-year, open follow-up study

This study intended to determine whether the replacement of vitamin D3 with alfacalcidol results in any bone mineral density (BMD) increase in 76 patients unresponsive to the combination of alendronate and conventional vitamin D3 treatment. In these patients the conventional vitamin D3 had been replaced with alfacalcidol (0.5 μg/day), and then the patients were followed up for a year. After treatment for 1 year, Wilcoxon test revealed a small but statistically significant (P < 0.001) increase in the BMD values of the forearm and lumbar vertebrae, in the serum calcium and urinary calcium/creatinine ratio in first-voided morning urine. However, the serum alkaline phosphatase activity, phosphorus, parathormone, osteocalcin levels and the urinary d-pyr/creatinine ratio decreased significantly (P < 0.001). As suggested by our results, combination therapy with alendronate and alfacalcidol increases bone density and improves the biochemical markers of bone turnover, without any substantial increase in the incidence of adverse effects.

Synergistic effects of green tea polyphenols and alphacalcidol on chronic inflammation-induced bone loss in female rats

Studies suggest that green tea polyphenols (GTP) or alphacalcidol is promising agent for preventing bone loss. Findings that GTP supplementation plus alphacalcidol administration increased bone mass via a decrease of oxidative stress and inflammation suggest a significant role of GTP plus alphacalcidol in bone health of patients with chronic inflammation.

INTRODUCTION

Studies have suggested that green tea polyphenols (GTP) or alphacalcidol are promising dietary supplements for preventing bone loss in women. However, the mechanism(s) related to the possible osteo-protective role of GTP plus D(3) in chronic inflammation-induced bone loss is not well understood.

METHODS

This study evaluated bioavailability, efficacy, and related mechanisms of GTP in combination with alphacalcidol in conserving bone loss in rats with chronic inflammation. A 12-week study of 2 (no GTP vs. 0.5% GTP in drinking water) × 2 (no alphacalcidol vs. 0.05 μg/kg alphacalcidol, 5×/week) factorial design in lipopolysaccharide-administered female rats was performed. In addition, a group receiving placebo administration was used to compare with a group receiving lipopolysaccharide administration only to evaluate the effect of lipopolysaccharide.

RESULTS

Lipopolysaccharide administration resulted in lower values for bone mass, but higher values for serum tartrate-resistant acid phosphatase (TRAP), urinary 8-hydroxy-2'-deoxyguanosine, and mRNA expression of tumor necrosis factor-α and cyclooxygenase-2 in spleen. GTP supplementation increased urinary epigallocatechin and epicatechin concentrations. Both GTP supplementation and alphacalcidol administration resulted in a significant increase in bone mass, but a significant decrease in serum TRAP levels, urinary 8-hydroxydeoxyguanosine levels, and mRNA expression of tumor necrosis factor-α and cyclooxygenase-2 in spleen. A synergistic effect of GTP and alphacalcidol was observed in these parameters. Neither GTP nor alphacalcidol affected femoral bone area or serum osteocalcin.

CONCLUSION

We conclude that a bone-protective role of GTP plus alphacalcidol during chronic inflammation bone loss may be due to a reduction of oxidative stress damage and inflammation.

Protective actions of green tea polyphenols and alfacalcidol on bone microstructure in female rats with chronic inflammation

This study investigated the effects of green tea polyphenols (GTP) and alfacalcidol on bone microstructure and strength along with possible mechanisms in rats with chronic inflammation. A 12-week study using a 2 (no GTP vs. 0.5%, w/v GTP in drinking water)×2 (no alfacalcidol vs. 0.05 μg/kg alfacalcidol orally, 5×/week) factorial design was employed in lipopolysaccharide (LPS)-administered female rats. A group receiving placebo administration was used to compare with a group receiving LPS administration only to evaluate the effect of LPS. Changes in tibial and femoral microarchitecture and strength of femur were evaluated. Difference in expression of tumor necrosis factor-α (TNF-α) in proximal tibia using immunohistochemistry was examined. Compared to the placebo group, the LPS-administered-only group had significantly lower femoral mass, trabecular volume, thickness and number in proximal tibia and femur, and lower periosteal bone formation rate in tibial shafts but had significantly higher trabecular separation and osteoclast number in proximal tibia and eroded surface in endocortical tibial shafts. Both GTP and alfacalcidol reversed these LPS-induced detrimental changes in femur, proximal tibia and endocortical tibial shaft. Both GTP and alfacalcidol also significantly improved femoral strength, while significantly suppressed TNF-α expression in proximal tibia. There were significant interactions in femoral mass and strength, trabecular separation, osteoclast number and TNF-α expression in proximal tibia. A combination of both showed to sustain bone microarchitecture and strength. We conclude that a protective impact of GTP and alfacalcidol in bone microarchitecture during chronic inflammation may be due to a suppression of TNF-α.

Vitamin D deficiency promotes growth of MCF-7 human breast cancer in a rodent model of osteosclerotic bone metastasis

INTRODUCTION

Breast cancer metastases to bone are common in advanced stage disease. We have recently demonstrated that vitamin D deficiency enhances breast cancer growth in an osteolytic mouse model of breast cancer metastasis. In this study, we examined the effects of vitamin D deficiency on tumor growth in an osteosclerotic model of intra-skeletal breast cancer in mice.

METHODS

The effects of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] on proliferation and apoptosis of MCF-7 breast cancer cells, and changes in the expression of genes within the vitamin D metabolic pathway (VDR, 1α- and 24-hydroxylase) were examined in vitro. MCF-7 breast cancer cells were injected intra-tibially into vitamin D deficient and vitamin D sufficient mice co-treated with and without osteoprotegerin (OPG). The development of tumor-related lesions was monitored via serial X-ray analysis. Tumor burden and indices of proliferation and apoptosis were determined by histology along with markers of bone turnover and serum intact PTH levels.

RESULTS

In vitro, MCF-7 cells expressed critical genes for vitamin D signalling and metabolism. Treatment with 1,25(OH)(2)D(3) inhibited cell growth and proliferation, and increased apoptosis. In vivo, osteosclerotic lesions developed faster and were larger at endpoint in the tibiae of vitamin D deficient mice compared to vitamin D sufficient mice (1.49±0.08 mm(2) versus 1.68±0.15 mm(2), P<0.05). Tumor area was increased by 55.8% in vitamin D deficient mice (0.81±0.13 mm(2) versus 0.52±0.11 mm(2) in vitamin D sufficient mice). OPG treatment inhibited bone turnover and caused an increase in PTH levels, while tumor burden was reduced by 90.4% in vitamin D sufficient mice and by 92.6% in vitamin D deficient mice. Tumor mitotic activity was increased in the tibiae of vitamin D deficient mice and apoptosis was decreased, consistent with faster growth.

CONCLUSION

Vitamin D deficiency enhances both the growth of tumors and the tumor-induced osteosclerotic changes in the tibiae of mice following intratibial implantation of MCF-7 cells. Enhancement of tumor growth appears dependent on increased bone resorption rather than increased bone formation induced by these tumors.

Differential effects of growth hormone and alpha calcidol on trabecular and cortical bones in hypophysectomized rats

Growth hormone (GH) deficiency in children causes severe growth retardation, vitamin D deficiency, and osteopenia. We investigated whether alfacalcidol (1OHD) alone or in combination with GH can improve bone formation. Forty hypophysectomized female rats (HX) at the age of 8 wk were divided into HX, HX + 1OHD (oral 0.25 microg/kg daily), HX+GH (0.666 mg/0.2 mL SC daily) and HX+GH + 1OHD groups for a 4-wk study. Results showed that GH increased body weight, bone area, bone mineral content (BMC), and bone mineral density (BMD), whereas 1OHD only increased BMC and BMD. In cortical bone, GH increased both periosteal and endocortical bone formation resulting in a significant increase in cortical size and area in percentage, whereas 1OHD suppressed endocortical erosion surface per bone surface (ES/BS) without a significant effect on bone formation rate per bone surface (BFR/BS). In trabecular bone, GH mitigated the bone loss by increasing BFR/BS, whereas the 1OHD effect was by suppression of trabecular bone turnover in the HX rats. The combination of GH and 1OHD had no additive effect on increasing trabecular bone mass. In conclusion, GH activates new bone formation and increases bone turnover whereas 1OHD suppresses bone turnover. The combination intervention does not seem to provide any additive benefit.

Clinical significance of 1-year treatment with raloxifene on bone and lipid metabolism in Japanese postmenopausal women with osteoporosis

It has been well established that raloxifene (RLX) has beneficial effects on bone primarily in Caucasian women. However, to date, there is a dearth of data for Japanese postmenopausal women. In this study, we prospectively evaluated the effects of RLX on bone and lipid metabolism in fifty Japanese postmenopausal patients with untreated osteoporosis. We measured bone mineral density (BMD) by dual-energy X-ray absorptiometry at 7 sites including the lumbar spine, femoral neck, and distal radius. BMD was significantly increased at the lumbar spine both at 6 months and at 12 months compared with at baseline (p<0.01 for both), although the possibility could not be completely excluded that this increase may be partly explained by an apparent increase induced by degenerative changes in lumbar vertebrae since we had no control subjects to compare and be more certain of the findings in this study. Both bone-specific alkaline phosphatase (BAP) and serum N-terminal telopeptide of type I collagen (NTx) significantly decreased both at 6 months (p<0.01 for both) and at 12 months (p<0.01 for both) compared with at baseline, but not below the lower limit of the reference value. Total cholesterol and low-density lipoprotein cholesterol were significantly improved while triglycerides and high-density lipoprotein cholesterol were unaltered. Although longer and larger studies with fracture endpoints are needed to draw definite conclusions, our findings suggest the favorable effects of RLX on bone and lipid metabolism in Japanese postmenopausal women with osteoporosis as in Caucasian women.

Improving the outcome of established therapies for osteoporosis by adding the active D-hormone analog alfacalcidol

While in other chronic diseases combined treatment regimens are the rule there is a lack of reported experience or study data on combining different specific drugs to treat osteoporosis. Significant differences in the mode of action (MOA) of the substances to be combined may be important for achieving optimal therapeutic results. Recognising that today bisphosphonates are the leading therapy for osteoporosis we suggest that the active D-hormone analog alfacalcidol with its completely different mechanisms of action could be an interesting combination to improve the therapeutic outcome of the pure antiresoptive action of bisphosphonates. Alfacalcidol is activated by the enzyme 25-hydroxylase in the liver for systemic and in osteoblasts for local D-hormone actions. It possesses a unique pattern of pleiotropic effects on, e.g. gut, bone, pararthyroids, muscle and brain. Alfacalcidol is superior to plain vitamin D (cholecalciferol) because the final kidney activation of the latter is regulated by a negative feedback mechanism. In vitamin D replete patients or patients with impaired kidney function no increased D-hormone action at the target tissues can be achieved. Animal studies and several trials in humans with alendronate plus calcitriol or alfacalcidol proved that the combination induced significantly higher increases of bone mineral density (BMD) than the respective mono-therapies. The results of the 2-year AAC-trial from our group indicate that the combination alendronate and alfacalcidol is also superior in terms of falls, fractures and back pain. From the review of the literature and the own new results we conclude that this combined therapeutic regimen is a very promising option for treating established osteoporosis and propose a differentiated use of alfacalcidol alone or the combination with alendronate in different stages and clinical situations of osteoporosis.

New 19-nor-(20S)-1alpha,25-dihydroxyvitamin D3 analogs strongly stimulate osteoclast formation both in vivo and in vitro

2-Methylene-19-nor-(20S)-1alpha,25-dihydroxyvitamin D3 (2MD), an analog of 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], has been shown to strongly induce bone formation both in vitro and in vivo. We have synthesized four substituents at carbon 2 of 2MD (2MD analogs), four stereoisomers at carbon 20 of the respective 2MD analogs (2MD analog-C20 isomers) and four 2MD analogs with an oxygen atom at carbon 22 (2MD-22-oxa analogs) and examined their ability to stimulate osteoclastogenesis and induce hypercalcemia. 2MD analogs were 100 times as potent as 1alpha,25(OH)2D3 in stimulating the formation of osteoclasts in vitro and in inducing the expression of receptor activator of NF-kappaB ligand (RANKL) and 25-hydroxyvitamin D3-24 hydroxylase mRNAs in osteoblasts. The osteoclast-inducing activities of 2MD analog-C20 isomers and 2MD 22-oxa analogs were much weaker than those of 2MD analogs. In addition, the activity of a 2MD analog in inducing dentine resorption was much stronger than that of 1alpha,25(OH)2D3 in the pit formation assay. Affinities to the vitamin D receptor and transcriptional activities of these compounds did not always correlate with their osteoclastogenic activities. Osteoprotegerin-deficient (OPG-/-) mice provide a suitable model for investigating in vivo effects of 2MD analogs because they exhibit extremely high concentrations of serum RANKL. The same amounts of 2MD analogs and 1alpha,25(OH)2D3 were administered daily to OPG-/- mice for 2 days. The elevation in serum concentrations of RANKL and calcium was much greater in 2MD analog-treated OPG-/- mice than in 1alpha,25(OH)2D3-treated ones. A 2MD analog was much more potent than 1alpha,25(OH)2D3 in causing hypercalcemia and in increasing soluble RANKL with enhanced osteoclastogenesis even in wild-type mice. In contrast, the administration of the 2MD analog to c-fos-deficient mice failed to induce osteoclastogenesis and hypercalcemia. These results suggest that new substituents at carbon 2 of 2MD strongly stimulate osteoclast formation in vitro and in vivo, and that osteoclastic bone resorption is indispensable for their hypercalcemic action of 2MD analogs in vivo.

Superiority of a combined treatment of Alendronate and Alfacalcidol compared to the combination of Alendronate and plain vitamin D or Alfacalcidol alone in established postmenopausal or male osteoporosis (AAC-Trial)

A combined therapy with the strongly antiresorptive Alendronate and the pleiotropically acting D-hormone analogue Alfacalcidol may have additive effects on bone quality, falls and fracture risk in established osteoporosis. The aim of this study (Alfacalcidol Alendronate Combined-AAC) was to compare the efficacy and safety of a combined parallel therapy with Alendronate and Alfacalcidol to the treatment with either Alendronate in combination with plain vitamin D or Alfacalcidol alone in patients with established postmenopausal or male osteoporosis. Ninety patients were included as matched triplets to receive randomly either 1 microg Alfacalcidol daily + 500 mg calcium (group A, n = 30) or 70 mg Alendronate weekly + 1,000 mg calcium + 1,000 IU vitamin D daily (group B, n = 30) or 1 microg Alfacalcidol daily + 70 mg Alendronate weekly + 500 mg calcium daily (group C, n = 30). Patients were recruited in one centre and were followed up for 24 months. Analysis was intention-to-treat and the primary outcome was lumbar spine and total hip bone mineral density (measured observer blind). BMD was measured at the lumbar spine and at the proximal femur with dual energy X-ray absorptiometry (LUNAR Prodigy, GE, USA) at the beginning and after 12 and 24 months. During the 2-year-study we observed descriptively significant increases at the lumbar spine of 3.0% in group A compared to baseline, of 5.4% in group B and of 9.6% in group C, respectively. The superiority of the Alendronate + Alfacalcidol treatment group over Alfacalcidol alone and over Alendronate + vitamin D was of more than large rele-vance (both tests: MW > 0.71; CI-LB > 0.64; P < 0.001). We also observed median increases of the BMD at the total hip of 1.5% in group A, of 2.4% in group B and of 3.8% in group C, respectively. The superiority of group C over group A and over group B again was relevant and statistically significant in a descriptive sense. After 2 years there was a tendency towards higher rates of vertebral and non-vertebral fractures in group A and B as compared to C. Taking both fracture types together we observed 9, 10 and 2 "osteoporotic fractures" in groups A, B and C, respectively. The comparison of group C with pooled groups A and B and with each single group gave a relevantly lower fracture rate for the combination of Alendronate and Alfacalcidol. Furthermore a lower rate of falls was observed for the combination Alendronate plus Alfacalcidol versus Alendronate + vitamin D, but not versus Alfacalcidol alone. We found 80% of the patients in the Alendronate + Alfacalcidol group free from back pain at month 24, compared to 30% in the Alendronate + vitamin D and 43% in the Alfacalcidol monotherapy group. The superiority is relevant (both tests: MW > 0.64; CI-LB > 0.56; P < 0.003). Pain decrease also occurred more rapidly in the Alendronate + Alfacalcidol group than in the other groups. In general side effects in all groups were mild, and only four cases of moderate hypercalcuria in group A and one in group C were reported, but no case of hypercalcemia was documented. In conclusion, the combination therapy with Alendronate and Alfacalcidol exhibited superiority in terms of BMD, overall fractures, rate of falls and back pain over either Alendronate in combination with plain vitamin D or Alfacalcidol alone. The overall safety profiles of the three treatment regimens were found to be not different in this study.

Production of IL-7 is increased in ovariectomized mice, but not RANKL mRNA expression by osteoblasts/stromal cells in bone, and IL-7 enhances generation of osteoclast precursors in vitro

Osteoclastogenic cytokines produced by T and B lineage cells and interleukin (IL)-7-induced expansion of the pool size of osteoclast precursors have been suggested to play an important role in acceleration of osteoclastogenesis induced by estrogen deficiency. However, the contribution of increased RANKL produced by osteoblasts/stromal cells to increase osteoclastogenesis in a mouse model of estrogen-deficient osteoporosis and in vitro effects of IL-7 on osteoclast precursor generation remain controversial. Thus, we investigated the effect of ovariectomy (OVX) of mice on production of RANKL, osteoprotegerin (OPG), and IL-7 in bone and the effect of IL-7 on osteoclast precursor generation in vitro. OVX did not significantly stimulate mRNA expressions of RANKL and OPG in whole femurs. Because the epiphysis, but not the femoral shaft (diaphysis) or bone marrow, is the main site of osteoclastogenesis, it is important to specifically analyze mRNA expression by osteoblasts/stromal cells at these parts of the femur. Therefore, we isolated RNA from bone marrow cell-free epiphysis, diaphysis, and flushed-out bone marrow and examined mRNA expression. The results showed no significant changes of RANKL and OPG mRNA expression in any part of the femur. In addition, OVX did not significantly affect RANKL and OPG mRNA expression by the adherent stromal cells isolated from flushed-out bone marrow cells but did stimulate RANKL mRNA expression by B220(+) cells in the nonadherent cell fraction. On the other hand, OVX increased IL-7 mRNA expression in the femur as well as IL-7 concentrations in bone fluid. In cultures of unfractionated bone cells isolated by vigorous agitation of minced whole long bones to release the cells tightly attached to the bone surfaces, but not in cocultures of clonal osteoblasts/stromal cells and flushed-out bone marrow cells, IL-7 stimulated generations of osteoclasts as well as osteoclast precursors. These data suggest that increased RANKL production by osteoblasts/stromal cells is unlikely to play a central role in acceleration of osteoclastogenesis in estrogen deficiency of mice and that IL-7 stimulates osteoclast precursor generation, presumably through an action of IL-7 on the cells attached to bone rather than on cells contained in the bone marrow cell population.

1Alpha,25-dihydroxy-2beta(3-hydroxypropoxy)vitamin D3 (ED-71) suppressed callus remodeling but did not interfere with fracture healing in rat femora

INTRODUCTION

Because osteoporotic patients are prone to fractures, it must be considered whether or not patients undergoing drug therapies should discontinue treatment after sustaining a non-vertebral fracture. This study has tested the effect of novel active vitamin D3 analog, 1alpha,25-dihydroxy-2beta(3-hydroxypropoxy)vitamin D3 (ED-71), on the fracture healing comparing with a powerful anti-resorptive agent, alendronate, using a rat femoral fracture model.

MATERIALS AND METHODS

Female SD rats (n=201) allocated into 6 groups were treated with MCT-vehicle and ED-71 at 0.025 and 0.05 microg/kg/day (EDL and EDH groups), and with saline-vehicle and alendronate at 5 and 10 microg/kg/day (ALL and ALH groups). After 4 weeks of pretreatment, osteotomy of the femur was performed. Treatment was continued until sacrifice at 6 and 16 weeks post-fracture. Fracture callus was evaluated by soft X-ray radiography, pQCT, biomechanical testing and histomorphometry.

RESULTS

At 16 weeks post-fracture, new cortical shell appeared in 100% of Control (MCT and saline-vehicle), EDL and EHL, and in 67% and 56% of ALL and ALH, respectively. ED-71 treatment showed insignificantly large callus area only at 6 weeks, while alendronate treatment induced bigger callus at both 6 and 16 weeks post-fracture. The lamellar/callus area was decreased only at 6 weeks by ED-71 treatment, but both at 6 and 16 weeks by alendronate treatment. Osteoclast number in callus surface was decreased in both ED-71 and alendronate treatment groups at 6 weeks and in EDH, ALL and ALH at 16 weeks, indicating that ED-71 inhibits osteoclastic bone resorption, but its effect is less prominent than alendronate. Almost complete callus remodeling was observed in ED-71-treated groups at 16 weeks without any significant change in structural and material properties of fractured bone.

CONCLUSIONS

ED-71 suppression of callus remodeling by inhibiting osteoclastic bone resorption was mild and dose-dependent and did not interfere with natural fracture healing process at 16 weeks post-fracture.

Effects of Calcitriol on Type 5b Tartrate-Resistant Acid Phosphatase and Interleukin-6 in Secondary Hyperparathyroidism

BACKGROUND/AIMS

Secondary hyperparathyroidism (SHP) is characterized by high bone turnover and elevated serum bone remodeling markers. Elevation of serum interleukin-6 (IL-6) levels is also characteristic of end-stage renal disease. This study investigates the effects of intravenous calcitriol on serum bone resorptive markers, namely, type 5b tartrate-resistant acid phosphatase (TRACP5b) and IL-6 in patients with SHP.

METHODS

Intravenous calcitriol therapy was given for 16 weeks to 24 patients on maintenance hemodialysis with plasma intact parathyroid hormone (iPTH) levels >300 pg/ml. Blood was drawn at baseline and every 4 weeks for 16 weeks for determination of the levels of biochemical parameters, iPTH, IL-6 and bone remodeling markers, including bone-specific alkaline phosphatase (bAP) and TRACP5b.

RESULTS

Only 21 patients responded to the calcitriol therapy, with significant decrements in serum iPTH after 4 weeks of therapy and thereafter. After 16 weeks of calcitriol therapy, 21 patients had significant decrements in serum iPTH (707.9 +/- 317.8 vs. 205.0 +/- 63.1 pg/ml, p < 0.01). Prior to treatment, a significant correlation was found between increased levels of serum iPTH and IL-6 levels (r = 0.45, p < 0.05). After treatment, there was also a significant and parallel lowering of levels of serum iPTH, IL-6 (8.52 +/- 3.59 vs. 7.24 +/- 2.81 pg/ml, p < 0.01), bAP (54.68 +/- 36.17 vs. 24.55 +/- 13.84 U/l, p < 0.01) and TRACP5b (3.41 +/- 1.89 vs. 1.80 +/- 0.55 U/l, p < 0.01). Our results additionally showed significant positive correlationsbetween baseline levels of serum IL-6 and those of iPTH, bAP and TRACP5b. After 16 weeks of calcitriol treatment, the correlation between IL-6 and iPTH levels lost significance but levels of serum IL-6, bAP and TRACP5b remained significantly correlated.

CONCLUSIONS

Elevated levels of serum IL-6 and bone remodeling markers, namely, bAP and TRACP5b which are common features of SHP, are effectively suppressed by calcitriol therapy. This indicates that hyperparathyroidism not only accelerates bone remodeling but may also aggravate inflammation in patients on maintenance hemodialysis.

c-Fos protein as a target of anti-osteoclastogenic action of vitamin D, and synthesis of new analogs

Although active vitamin D drugs have been used for the treatment of osteoporosis, how the vitamin D receptor (VDR) regulates bone cell function remains largely unknown. Using osteoprotegerin-deficient mice, which exhibit severe osteoporosis due to excessive receptor activator of NF-kappaB ligand/receptor activator of NF-kappaB (RANKL/RANK) stimulation, we show herein that oral treatment of these mice with 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] inhibited bone resorption and prevented bone loss, suggesting that VDR counters RANKL/RANK signaling. In M-CSF-dependent osteoclast precursor cells isolated from mouse bone marrow, 1alpha,25(OH)2D3 potently and dose-dependently inhibited their differentiation into multinucleate osteoclasts induced by RANKL. Among signaling molecules downstream of RANK, 1alpha,25(OH)2D3 inhibited the induction of c-Fos protein after RANKL stimulation, and retroviral expression of c-Fos protein abrogated the suppressive effect of 1alpha,25(OH)2D3 on osteoclast development. By screening vitamin D analogs based on their c-Fos-suppressing activity, we identified a new analog, named DD281, that inhibited bone resorption and prevented bone loss in ovariectomized mice, more potently than 1alpha,25(OH)2D3, with similar levels of calcium absorption. Thus, c-Fos protein is an important target of the skeletal action of VDR-based drugs, and DD281 is a bone-selective analog that may be useful for the treatment of bone diseases with excessive osteoclastic activity.

Superiority of alfacalcidol compared to vitamin D plus calcium in lumbar bone mineral density in postmenopausal osteoporosis

In a randomized multicenter, double-blind, double-dummy, parallel group study a comparison of the efficacy and safety of 1 microg alfacalcidol to 880 IU vitamin D plus calcium carbonate (1 g calcium) once daily per os was performed on 148 postmenopausal osteoporotic Caucasian patients with normal vitamin D serum levels for 18 months. Bone mineral density (BMD) was measured at baseline, 12 and 18 months. Safety parameters were followed during the entire study period. Sixty-nine (90.8%) in the alfacalcidol group and 67 (93.1%) in the vitamin D group were included in the ITT analysis. Lumbar BMD in the alfacalcidol group increased by 0.017 g/cm2 (2.33%) and 0.021 g/cm2 (2.87%) from baseline (P<0.001) at 12 and 18 months, respectively, whereas in the vitamin D plus calcium group the increase was 0.005 g/cm2 (0.70%) from baseline (N.S.) at both 12 and 18 months. The higher changes from baseline in the alfacalcidol group, as compared to the changes in the vitamin D plus calcium group at both 12 and 18 months, were found to be statistically significant (P=0.018, 0.005). A small increase of mean femoral BMD was achieved in both groups (N.S.). Adverse events were similar in both groups. No significant differences were noted between the groups in serum calcium. In conclusion, alfacalcidol was found to be superior in significantly increasing lumbar BMD as compared to vitamin D plus calcium while safety characteristics were found to be similar in both treatments.

Ataxia telangiectasia mutated (Atm) knockout mice as a model of osteopenia due to impaired bone formation

ATM is a member of the PI-3 kinase protein family, encoded by the gene, ATM, responsible for ataxia telangiectasia (AT). AT is recognized as a genomic instability syndrome, sharing accelerated senescence symptoms in human and mouse. Here, we present evidence that the bone phenotype of Atm knockout (AtmKO) mice is similar to that observed in disuse and/or aging syndromes. A significant decrease in 3-dimensional bone volume fraction (BV/TV) of the fifth lumbar vertebra was observed in AtmKO mice by microCT, compared with heterozygous control mice at 10 weeks of age. Bone histomorphometry revealed that both BFR/BS and Oc.S/BS were significantly decreased in KO mice. To determine the cellular basis of this bone phenotype, we employed in vitro osteoclastogenesis and colony formation assays using bone marrow cells derived from KO and control mice. There was no difference in osteoclast formation in ex vivo cultures. CFU-F was markedly reduced in AtmKO-derived cultures compared with control mice, whereas differentiation of calvaria-derived osteoblasts did not differ between the genotypes. Furthermore, expression levels of IGF1R were significantly decreased, and p38 was aberrantly phosphorylated in marrow stromal cells from AtmKO mice. These results indicate that the pathogenesis of the osteopenic phenotype in AtmKO mice is similar to that of disuse and/or aging syndromes and is caused, at least in part, by a stem cell defect due to lack of IGF signaling.

1,25(OH)2D3 acts as a bone-forming agent in the hormone-independent senescence-accelerated mouse (SAM-P/6)

Recent studies suggest that vitamin D signaling regulates bone formation. However, the overall effect of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on bone turnover in vivo is still unclear. In this study, our aim was to examine the effect of 1,25(OH)2D3 on bone turnover in SAM-P/6, a hormone-independent mouse model of senile osteoporosis characterized by a decrease in bone formation. Male and female 4-mo-old SAM-P/6 mice were treated with 1,25(OH)2D3 (18 pmol/24 h) or vehicle for a period of 6 wk, and a group of age- and sex-matched nonosteoporotic animals was used as control. Bone mineral density (BMD) at the lumbar spine increased rapidly by >30 +/- 5% (P < 0.001) in 1,25(OH)2D3-treated SAM-P/6 animals, whereas BMD decreased significantly by 18 +/- 2% (P < 0.01) in vehicle-treated SAM-P/6 animals and remained stable in control animals during the same period. Static and dynamic bone histomorphometry indicated that 1,25(OH)2D3 significantly increased bone volume and other parameters of bone quality as well as subperiosteal bone formation rate compared with vehicle-treated SAM-P/6 mice. However, no effect on trabecular bone formation was observed. This was accompanied by a marked decrease in the number of osteoclasts and eroded surfaces. A significant increase in circulating bone formation markers and a decrease in bone resorption markers was also observed. Finally, bone marrow cells, obtained from 1,25(OH)2D3-treated animals and cultured in the absence of 1,25(OH)2D3, differentiated more intensely into osteoblasts compared with those derived from vehicle-treated mice cultured in the same conditions. Taken together, these findings demonstrate that 1,25(OH)2D3 acts simultaneously on bone formation and resorption to prevent the development of senile osteoporosis.

Effect of intermittent administration of 200 IU intranasal salmon calcitonin and low doses of 1α(OH) vitamin D3 on bone mineral density of the lumbar spine and hip region and biochemical bone markers in women with postmenopausal osteoporosis: a pilot study

A 1-year prospective, open, randomized, controlled trial was conducted as a pilot study to examine the effect of intermittent administration of 200 IU intranasal salmon calcitonin and 1alpha(OH) vitamin D3 [1alpha(OH)D3] on bone mineral density (BMD) of the lumbar spine and hip as well as on the markers of bone metabolism in women with postmenopausal osteoporosis. A total of 102 randomly recruited women received either 200 IU intranasal salmon calcitonin (Miacalcic nasal 200, Novartis, Basel, Switzerland) daily, 1 month on-1 month off, 0.25 mug 1alpha(OH)D3, and 500 mg elemental calcium continuously (n=57 women) or only 0.25 mug 1alpha(OH)D3 and 500 mg calcium (n=45 women) for a period of 1 year. BMD of the lumbar spine and hip plus biochemical markers reflecting calcium (Ca) metabolism and bone turnover [serum Ca, serum phosphorus, intact parathormone (iPTH), total and bone-specific alkaline phosphatase, osteocalcin levels, 24-h urinary Ca, morning fasting urinary Ca/creatinine, and Pyrilinks-D/creatinine ratio] were measured at the beginning of the study before treatment and after 6 and 12 months of treatment. Baseline characteristics of participants, including age, body mass index, lumbar and hip BMD, and biochemical markers were similar between the two groups. A total of 91 patients completed the study (50 in the salmon calcitonin nasal spray group and 41 in the other group). Lumbar BMD increased significantly in the salmon calcitonin group from baseline (3.0%, p=0.005) and in comparison to the non-calcitonin-treated group (p=0.009). The salmon calcitonin group also had a significant increase in femoral neck BMD compared with baseline values (3.1%, p=0.0005) and in comparison to the non-calcitonin-treated group (p=0.0005) in Ward's triangle BMD (2.9% from baseline values, p=0.009) and in comparison to the non-calcitonin-treated group (p=0.005) in trochanteric BMD (3.4% from baseline values, p=0.007) and in comparison to the non-calcitonin-treated group (P=0.01). Urinary Ca/creatinine and Pyrilinks-D/creatinine levels were significantly decreased from baseline in the salmon calcitonin-treated group (-6.1 and -6.3%, respectively, p=0.001). Bone-specific alkaline phosphatase levels were also significantly decreased from baseline in the salmon calcitonin-treated group (-3.6%, p=0.003). In the same group, a significant decrease in iPTH serum levels compared to baseline values (-2.5%, p=0.005) and in comparison to the non-calcitonin-treated group (p=0.005) was noted. In conclusion, in this pilot study, 1-year intermittent treatment with 200 IU intranasal salmon calcitonin and low doses of 1alpha(OH)D3 produced a significant effect on bone turnover and BMD in postmenopausal women with osteoporosis.