Expression of Renal Vitamin D and Phosphatonin-Related Genes in a Sheep Model of Osteoporosis

Osteoporosis is a significant public health issue around the world, with post-menopausal osteoporosis due to estrogen deficiency resulting in approximately ¾ of cases. In this study, 18 aged Merino ewes were ovariectomized, and 10 were controls. Three of the ovariectomized ewes were treated weekly with 400 mg of methylprednisolone for 5 months and three were treated weekly for 2 months, followed by a 3-month recovery period. At 2 months, five control animals and six ovariectomized animals were euthanized. At 5 months, all the remaining ewes were euthanized. Kidney samples were collected postmortem for qPCR analysis of NPT1, PTH1R, NPT2a, NPT2c, Klotho, FGFR1IIIc, VDR, CYP24A1, CYP27B1, TRPV5, TRPV6, CalD9k, CalD28k, PMCA and NCX1. Ovariectomized sheep had significantly greater VDR expression compared with other groups. Ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months showed significant differences in TRPV5, CYP24A1 and klotho gene expression compared to other groups. Differences in klotho expression were most marked after adjustment for repeated measures (p = 0.1). Klotho is known as the “anti-aging” hormone and is involved in calcium and phosphorus metabolism. Klotho may be involved in the recovery of bone mineral density in ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months. Further research on the role of klotho is recommended.

Serum Osteocalcin and Bone Mineral Density as Markers of Post-menopausal Osteoporosis: A Meta-analysis

Osteocalcin (OC) and bone mineral density (BMD) measurements determine the bone mass and microarchitecture of bone. Both are used for diagnosing osteoporosis and their role as a biomarker in postmenopausal osteoporosis (PMO) remains controversial. To determine the relationship between serum OC and PMO and compare BMD vs OC, a metaanalysis was carried forward with case-control studies. Studies reporting mean/median and standard deviation of osteocalcin in post-menopausal women with and without osteoporosis were included. From the same studies, BMD measurements in both groups were included. Fifteen studies were included with 1864 postmenopausal women. We found significant increase in serum OC (Standardized Mean Difference of 0.918 and SE of 0.476 (p=0.054), confidence interval (CI) (-0.015 to 1.852) and significant decrease in BMD values (SMD of -2.321 and SE of 0.345 (p= <0.001) (CI - 2.998 to -1.643)) in PMO. T score also significantly decreased in PMO (SMD <0 (-3.785). Heterogeneity was observed in all parameters analyzed for more than 90%. We concluded that in our metanalysis, there was a significant increase in serum osteocalcin levels with SMD> 0 and significantly low BMD/t score levels with SMD <0 in postmenopausal osteoporotic women as compared to healthy postmenopausal women. Osteocalcin gives the current status of bone remodeling and is not influenced by multiple factors whereas BMD measures the bone mass, yet techniques vary and are influenced by many factors. SMD < 0 alone cannot be used to detect osteoporosis or predict osteoporotic fractures. Increased osteocalcin and low BMD/T score after menopause together are good indicators to detect osteoporosis. This conjunction can economically burden the patient and thus our study concludes that SMD > 0 serum osteocalcin solely can be implemented as a promising marker for diagnosing osteoporosis.

Anti-osteoporotic effect of Terminalia arjuna (Roxb.) Wight & Arn. In bilateral ovariectomized induced post-menopausal osteoporosis in experimental rats

Objectives In ancient times Terminalia arjuna (Roxb.) Wight & Arn. (TA) was used for fast healing of fracture and to strengthen the bone. However, no scientific study has been done to validate its usefulness in the alleviation of osteoporosis. To investigate the efficacy of stem bark TA against post-menopausal osteoporosis using bilateral ovariectomized rat model. Methods Aqueous (TAA) and methanolic (TAM) extracts of TA was evaluated for its anti-osteoporotic activity. Sham control rats were allotted as Group I (Normal control); Group II animals acted as OVX control (Disease control); Group III OVX rats were treated with estrogen (Standard group – 2 mg/kg) Group IV and V OVX rats give treatment to TAA (250 and 500 mg/kg, p.o.), respectively. This treatment is continue for the four weeks and at the end, serum biochemical parameters such as serum calcium and alkaline phosphate were evaluated. Femoral bone parameters (Compression of vertebrae, femoral neck load testing, Three point bending of tibia, Femur length and weight), histology, body weight, and fifth lumbar vertebra breaking strength were also assessed after the sacrificing the animal. Results In OVX rats, atrophy of uterus and descent of BMD were suppressed by treatment with TAA and TAM. In addition, TAM 500 completely corrected the decreased serum concentration of Calcium, Phosphorus, ALP and TRAP observed in OVX rats. TAA and TAM both increased biomechanical strength significantly in comparison to the sham group. Histological results also revealed its protective action through elevation of bone formation. TAM significantly increase the uterine and femoral bone weight The TAM showed maximum anti-osteoporotic activity in in vivo study as compare to TAA. Conclusions The results, evaluated on the basis of biochemical, bone mineral density, biomechanical, and histopathological parameters, presented that TAA and TAM has a definite antiosteoporotic effect, like to estrogen, especially effective for inhibition bone fracture induced by estrogen deficiency.

Expression of circulating Mir-139-5p is associated with Postmenopausal Osteoporosis in Indian women

Background: Osteoporosis in post-menopausal women is known to progress periodically and is highly associated with inflammation. MicroRNAs regulate inflammatory process, which may therefore control bone metabolism. Deregulation of miRNAs associated with inflammation may lead to development and progression of osteoporosis. We selected four miRNAs known to be involved in inflammation to test their association with post-menopausal osteoporosis. Methods: We quantified four circulating miRNAs, hsa-miR-139-5p, hsa-miR-342-3p, hsa-miR-146a and hsa-miR-24-3p in plasma samples of 25 post-menopausal osteoporosis and 25 post-menopausal healthy subjects. Related biochemical tests were done using Cobas e411 and ELISA. Results: Upon quantification of circulating miRNAs, we observed that hsa-miR-139-5p was expressed higher in post-menopausal osteoporotic samples (p=0.01). The expression of hsa-miR-24-3p was seen lower in osteoporotic samples though not highly significant (p=0.2). Conclusion: Differential expression of hsa-miR-139-5p and hsa-miR-24-3p was seen in osteoporosis subjects. These miRNA could be significantly involved in development and progression of osteoporosis. Further studies are required to highlight miRNAs’ involvement in regulating bone metabolism, which could be manipulated to use them as marker or therapeutic strategies to alleviate osteoporosis.

Relation between Circulating Vitamin k2 level and Osteoporosis in Post-Menopausal Women

Objective We aimed to measure the serum level of vitamin k2 in postmenopausal osteoporotic patients to determine its role in the disease. Patients and Methods Our study was designed as a cross sectional study, with 15 postmenopausal osteoporotic patients (with reduced bone mineral density BMD), aged between 54-58 years old compared to 15 healthy controls (with normal BMD at all of lumbar spine, femoral neck and hip) matched in age with the patients. All participants were subjected to full medical history taking, physical examination and functional assessment of the activity of daily livings (ADL). Biochemical assays of thyroid stimulating hormone, parathyroid hormone, total calcium, phosphorus, alkaline phosphatase (ALP), 25-hydroxyvitamin D (25 (OH) D), erythrocyte sedimentation rate, Kidney and liver function tests and serum levels of vitamin k2 were performed. Results The patients showed highly significantly lower vitamin k2 levels (P &lt; 0.05) and non-significant correlations between vitamin k2 and the activity of daily living (ADL) nor the other laboratory assessment parameters (P &gt; 0.05) among the patient’s group. Conclusion Vitamin K deficiency is highly prevalent in the majority of our patients and should be considered an associating factor in the etiology of postmenopausal osteoporosis. Vitamin k2 deficiency could result in a decrease in the bone mineral density in postmenopausal women, so vitamin k2 levels should be checked in post-menopausal osteoporosis and any deficiency must be treated and corrected to improve the bone mineral density.

Vitamin D Receptor Gene Variants Susceptible to Osteoporosis in Arab Post-Menopausal Women

Post-menopausal osteoporosis (PMO) is a multifactorial bone disorder in elderly women. Various vitamin D receptor (VDR) gene variants have been studied and associated with osteoporosis in other populations, but not in a homogenous Arab ethnic group. Herein, the current study explores the association between VDR polymorphisms and susceptibility to osteoporosis in Saudi postmenopausal women. In total, 600 Saudi postmenopausal women (N = 300 osteoporosis; N = 300 control) were genotyped for VDR gene variants (rs7975232, rs1544410, rs731236) using TaqMan® SNP genotyping assays. Bone mineral density (BMD) for the lumbar spine and femur was assessed using dual-energy X-ray absorptiometry (DEXA). The heterozygous frequency distributions AC of rs7975232, CT of rs1544410, and AG of rs731236 were significantly higher in the osteoporosis group than controls (p < 0.05). Heterozygous AC of rs7975232 (1.6; 95% CI 1.1–2.3; p < 0.023), CT of rs1544410 (1.6; 95% CI 1.1–2.4; p < 0.022), and AG of rs731236 (1.6; 95% CI 1.1–2.4; p < 0.024) were significantly associated with increased risk of osteoporosis, independent of age and BMI. In conclusion, VDR gene variants rs7975232, rs1544410, rs731236 had a significant effect on BMD and were associated with osteoporosis risk in Saudi postmenopausal women.

Murine femur micro-computed tomography and biomechanical datasets for an ovariectomy-induced osteoporosis model

The development of new effective and safer therapies for osteoporosis, in addition to improved diagnostic and prevention strategies, represents a serious need in the scientific community. Micro-CT image-based analyses in association with biomechanical testing have become pivotal tools in identifying osteoporosis in animal models by assessment of bone microarchitecture and resistance, as well as bone strength. Here, we describe a dataset of micro-CT scans and reconstructions of 15 whole femurs and biomechanical tests on contralateral femurs from C57BL/6JOlaHsd ovariectomized (OVX), resembling human post-menopausal osteoporosis, and sham operated (sham) female mice. Data provided for each mouse include: the acquisition images (.tiff), the reconstructed images (.bmp) and an.xls file containing the maximum attenuations for each reconstructed image. Biomechanical data include an.xls file with the recorded load-displacement, a movie with the filmed test and an.xls file collecting all biomechanical results.

Combined Effects of Exercise and Denosumab Treatment on Local Failure in Post-menopausal Osteoporosis–Insights from Bone Remodelling Simulations Accounting for Mineralisation and Damage

Denosumab has been shown to increase bone mineral density (BMD) and reduce the fracture risk in patients with post-menopausal osteoporosis (PMO). Increase in BMD is linked with an increase in bone matrix mineralisation due to suppression of bone remodelling. However, denosumab anti-resorptive action also leads to an increase in fatigue microdamage, which may ultimately lead to an increased fracture risk. A novel mechanobiological model of bone remodelling was developed to investigate how these counter-acting mechanisms are affected both by exercise and long-term denosumab treatment. This model incorporates Frost's mechanostat feedback, a bone mineralisation algorithm and an evolution law for microdamage accumulation. Mechanical disuse and microdamage were assumed to stimulate RANKL production, which modulates activation frequency of basic multicellular units in bone remodelling. This mechanical feedback mechanism controls removal of excess bone mass and microdamage. Furthermore, a novel measure of bone local failure due to instantaneous overloading was developed. Numerical simulations indicate that trabecular bone volume fraction and bone matrix damage are determined by the respective bone turnover and homeostatic loading conditions. PMO patients treated with the currently WHO-approved dose of denosumab (60 mg administrated every 6 months) exhibit increased BMD, increased bone ash fraction and damage. In untreated patients, BMD will significantly decrease, as will ash fraction; while damage will increase. The model predicted that, depending on the time elapsed between the onset of PMO and the beginning of treatment, BMD slowly converges to the same steady-state value, while damage is low in patients treated soon after the onset of the disease and high in patients having PMO for a longer period. The simulations show that late treatment PMO patients have a significantly higher risk of local failure compared to patients that are treated soon after the onset of the disease. Furthermore, overloading resulted in an increase of BMD, but also in a faster increase of damage, which may consequently promote the risk of fracture, specially in late treatment scenarios. In case of mechanical disuse, the model predicted reduced BMD gains due to denosumab, while no significant change in damage occurred, thus leading to an increased risk of local failure compared to habitual loading.

Estrogen withdrawal alters cytoskeletal and primary ciliary dynamics resulting in increased Hedgehog and osteoclastogenic paracrine signalling in osteocytes

Estrogen deficiency during post-menopausal osteoporosis leads to osteoclastogenesis and bone loss. Increased pro-osteoclastogenic signalling (RANKL/OPG) by osteocytes occurs following estrogen withdrawal (EW) and is associated with impaired focal adhesions (FAs) and a disrupted actin cytoskeleton. RANKL production is mediated by Hedgehog signalling in osteocytes, a signalling pathway associated with the primary cilium, and the ciliary structure is tightly coupled to the cytoskeleton. Therefore, the objective of this study was to investigate the role of the cilium and associated signalling in EW-mediated osteoclastogenic signalling in osteocytes. We report that EW leads to an elongation of the cilium and increase in Hedgehog and osteoclastogenic signalling. Significant trends were identified linking cilia elongation with reductions in cell area and % FA area/cell area, indicating that cilia elongation is associated with disruption of FAs and actin contractility. To verify this, we inhibited FA assembly via αvβ3 antagonism and inhibited actin contractility and demonstrated an elongated cilia and increased expression of Hh markers and Rankl expression. Therefore, our results suggest that the EW conditions associated with osteoporosis lead to a disorganisation of αvβ3 integrins and reduced actin contractility, which were associated with an elongation of the cilium, activation of the Hh pathway and osteoclastogenic paracrine signalling.