Effects of dexamethasone, celecoxib, and methotrexate on the histology and metabolism of bone tissue in healthy Sprague Dawley rats

Parthenolide ameliorates glucocorticoid-induced inhibition of osteogenic differentiation and osteoporosis by activating ERK signaling pathway

BACKGROUND

Parthenolide (PTL) is a natural sesquiterpene lactone that possesses significant effects on stimulating osteoblast differentiation. The present study focused on the potential of PTL in the treatment of glucocorticoid-induced osteoporosis (GIOP).

METHODS

MC3T3-E1 cells were treated with dexamethasone (DEX; 10 µM) or/and PTL (5, 10, and 20 µM). The changes in osteogenic differentiation were analyzed by conducting ALP and Alizarin Red staining and assessing the levels of osteogenic markers (Runx2, Osx, and OPN). PTL (3 and 10 mg/kg/day) was injected into rat models of GIOP induced by DEX. Bone formation was analyzed by assessing the levels of bone turnover markers (ALP, TRAP, OCN, and CTx) in the serum and osteoblast differentiation markers (BMP2 and Runx2) in the femurs. The pathological changes of the femurs were determined by H&E staining. Bone mass and osteoblast numbers in the femurs were measured. Western blotting evaluated ERK phosphorylation in vitro and in vivo.

RESULTS

PTL promoted osteogenic differentiation and enhanced the levels of Runx2, Osx, OPN, and ERK phosphorylation in DEX-treated MC3T3-E1 cells. ERK inhibitor U0126 reversed the promoting effect of PTL on osteogenesis in DEX-treated MC3T3-E1 cells. After the administration of PTL in rat models of GIOP, the levels of ALP, TRAP, OCN, and CTx in the serum and the levels of BMP2, Runx2, and ERK phosphorylation in the femurs were restored. PTL increased trabecular bone number, reduced trabecular separation, and increased the number of osteoblasts in GIOP rat model.

CONCLUSION

Overall, PTL alleviates osteoporosis by promoting osteogenic differentiation via activation of ERK signaling.

Antiosteoporosis and Bone Protective Effect of Phyllanthin Against Glucocorticoid-induced Osteoporosis in Rats via Alteration of HO-1/Nrf2 and RANK/RANKL/OPG Pathway

BACKGROUND

Osteoporosis is a condition where bones weaken due to a loss in density and quality, making them fragile and more susceptible to fractures, even from minor stress or injury. In this experimental study, we scrutinized the antiosteoporosis effect of phyllanthin against glycocorticoid (GIOP) induced osteoporosis in rats.

METHODS

SD rats were used in this study and subcutaneous administration of DEX (3 mg/kg) was used for the induction of osteoporosis and rats were treated with phyllanthin and alendronate for 12 weeks. The body weight, femur mass, length, hormones, nutrients, antioxidant, cytokines and bone parameters were estimated. The mRNA expression of HO-1, Nrf2, RANK, RANKL and OPG were estimated.

RESULTS

Phyllanthin treatment significantly (p < 0.001) improved the body weight, femur mass and femur length. Phyllanthin significantly (p < 0.001) altered the level of hormones estrodiol, PTH; nutrients such as calcium, phosphorus, magnesium; Bone mineral content (BMC) and bone mineral density (BMD); Bone formation marker like ALP, TRAP, osteocalcin, β-CTX, BGP, cathepsin K, DPD; Bone parameters viz., Tb.N, BV/TV, Tb.sp, BS/BV, Tb.Th; Bone structure analysis includes maximum load, energy, stiffness, maximum stress, young's modules; oxidative stress parameters such as TBARS, CAT, GPx, GSH, GR; cytokines such as TNF-α, IL-1β, IL-6, IL-10 and antioxidant marker such as HO-1 and Nrf2. Phyllanthin significantly (P < 0.001) altered the mRNA expression of HO-1, Nrf2, RANK, RANKL and OPG.

CONCLUSION

On the basis of result, we can say that phyllanthin exhibited the antiosteoporosis effect against glucocorticoid-induced osteoporosis in rats via alteration of HO-1/Nrf2 and RANK/RANKL/OPG pathway.

One-carbon metabolism supports S-adenosylmethionine and m6A methylation to control the osteogenesis of bone marrow stem cells and bone formation

The skeleton is a metabolically active organ undergoing continuous remodeling initiated by bone marrow stem cells (BMSCs). Recent research has demonstrated that BMSCs adapt the metabolic pathways to drive the osteogenic differentiation and bone formation, but the mechanism involved remains largely elusive. Here, using a comprehensive targeted metabolome and transcriptome profiling, we revealed that one-carbon metabolism was promoted following osteogenic induction of BMSCs. Methotrexate (MTX), an inhibitor of one-carbon metabolism that blocks S-adenosylmethionine (SAM) generation, led to decreased N6-methyladenosine (m6A) methylation level and inhibited osteogenic capacity. Increasing intracellular SAM generation through betaine addition rescued the suppressed m6A content and osteogenesis in MTX-treated cells. Using S-adenosylhomocysteine (SAH) to inhibit the m6A level, the osteogenic activity of BMSCs was consequently impeded. We also demonstrated that the pro-osteogenic effect of m6A methylation mediated by one-carbon metabolism could be attributed to HIF-1α and glycolysis pathway. This was supported by the findings that dimethyloxalyl glycine rescued the osteogenic potential in MTX-treated and SAH-treated cells by upregulating HIF-1α and key glycolytic enzymes expression. Importantly, betaine supplementation attenuated MTX-induced m6A methylation decrease and bone loss via promoting the abundance of SAM in rat. Collectively, these results revealed that one-carbon metabolite SAM was a potential promoter in BMSC osteogenesis via the augmentation of m6A methylation, and the cross talk between metabolic reprogramming, epigenetic modification, and transcriptional regulation of BMSCs might provide strategies for bone regeneration.

Identification of candidate genes and chemicals associated with osteonecrosis of femoral head by multiomics studies and chemical-gene interaction analysis

Objectives

In-depth understanding of osteonecrosis of femoral head (ONFH) has revealed that degeneration of the hip cartilage plays a crucial role in ONFH progression. However, the underlying molecular mechanisms and susceptibility to environmental factors in hip cartilage that contribute to ONFH progression remain elusive.

Methods

We conducted a multiomics study and chemical-gene interaction analysis of hip cartilage in ONFH. The differentially expressed genes (DEGs) involved in ONFH progression were identified in paired hip cartilage samples from 36 patients by combining genome-wide DNA methylation profiling, gene expression profiling, and quantitative proteomics. Gene functional enrichment and pathway analyses were performed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Functional links between proteins were discovered through protein-protein interaction (PPI) networks. The ONFH-associated chemicals were identified by integrating the DEGs with the chemical-gene interaction sets in the Comparative Toxicogenomics Database (CTD). Finally, the DEGs, including MMP13 and CHI3L1, were validated via quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC).

Results

Twenty-two DEGs were identified across all three omics levels in ONFH cartilage, 16 of which were upregulated and six of which were downregulated. The collagen-containing extracellular matrix (ECM), ECM structural constituents, response to amino acids, the relaxin signaling pathway, and protein digestion and absorption were found to be primarily involved in cartilage degeneration in ONFH. Moreover, ten major ONFH-associated chemicals were identified, including, benzo(a)pyrene, valproic acid, and bisphenol A.

Conclusion

Overall, our study identified several candidate genes, pathways, and chemicals associated with cartilage degeneration in ONFH, providing novel clues into the etiology and biological processes of ONFH progression.

Impact of Perioperative Dexamethasone Administration on Infection and Implant Osseointegration in a Preclinical Model of Orthopedic Device-Related Infection

Glucocorticoids may be given prior to major orthopedic surgery to decrease postoperative nausea, vomiting, and pain. Additionally, many orthopedic patients may be on chronic glucocorticoid therapy. The aim of our study was to investigate whether glucocorticoid administration influences Orthopedic-Device-Related Infection (ODRI) in a rat model. Screws colonized with Staphylococcus epidermidis were implanted in the tibia of skeletally mature female Wistar rats. The treated groups received either a single shot of dexamethasone in a short-term risk study, or a daily dose of dexamethasone in a longer-term interference study. In both phases, bone changes in the vicinity of the implant were monitored with microCT. There were no statistically significant differences in bacteriological outcome with or without dexamethasone. In the interference study, new bone formation was statistically higher in the dexamethasone-treated group (p = 0.0005) as revealed by CT and histopathological analysis, although with relatively low direct osseointegration of the implant. In conclusion, dexamethasone does not increase the risk of developing periprosthetic osteolysis or infection in a pre-clinical model of ODRI. Long-term administration of dexamethasone seemed to offer a benefit in terms of new bone formation around the implant, but with low osseointegration.

Rodents as an animal model for studying tooth extraction-related medication-related osteonecrosis of the jaw: assessment of outcomes

OBJECTIVE

To assess the outcomes of several rodent animal models for studying tooth extraction-related medication-related osteonecrosis of the jaw (MRONJ).

DESIGN

After a search of the databases, 2004 articles were located, and 118 corroborated the inclusion factors (in vivo studies in rodents evaluating tooth extraction as a risk factor for the development of MRONJ).

RESULTS

Numerous studies attempting to establish an optimal protocol to induce MRONJ were found. Zoledronic acid (ZA) was the most used drug, followed by alendronate (ALN). Even when ZA did not lead to the development of MRONJ, its effect compromised the homeostasis of the bone and soft tissue. The association of other risk factors (dexamethasone, diabetes, and tooth-related inflammatory dental disease) besides tooth extraction also played a role in the development of MRONJ. In addition, studies demonstrated a relationship between cumulative dose and MRONJ.

CONCLUSIONS

Both ZA and ALN can lead to MRONJ in rodents when equivalent human doses (in osteoporosis or cancer treatment) are used. Local oral risk factors and tooth-related inflammatory dental disease increase the incidence of MRONJ in a tooth extraction-related rodent model.

Analysis of bone metabolic alterations linked with osteoporosis progression in type 2 diabetic db/db mice

Type 2 diabetes (T2D) is a common chronic disease, characterized by persistent hyperglycemia and insulin resistance. This disorder is associated with decreased bone quality and an elevated risk of bone fractures. However, evidence on the relationship between systemic metabolic change and the development of type 2 diabetic osteoporosis (T2DOP) remains elusive. Herein, we investigate the changes of bone metabolites with bone loss in db/db mice (an animal model of T2DOP exhibited bone loss with age progression), and explore the potential metabolic mechanism underlying type 2 diabetes and osteoporosis. C57BKS male mice were distributed in four groups, consisting six mice in each group: 8w m/m, 24w m/m, 8w db/db and 24w db/db. Bone morphometric and biomechanical parameters of db/db mice were analyzed by micro-CT and materials tester, it was found that 24w db/db mice showed severe bone loss and decreased bone tissue hardness compared with misty/misty littermates. The tibia of misty/misty mice (8 weeks, 24 weeks) and db/db mice (8 weeks, 24 weeks) were screened for differential metabolites by UPLC-Orbitrap MS. Ninety-eight metabolites were identified (35 and 63 metabolites are associated with early staged and late staged, respectively), consisting of amino acids, fatty acyls, and nucleotides. Notably, fatty acyls (such as 18-HEPE, 16(17)-EpDPE, arachidonic acid) and glycerophospholipids (such as phosphocholines (PC) (O-10:1(9E)/0:0), PC (O-16:1(9E)/0:0) [U] and phosphatidylethanolamines (PE) (P-16:0/0:0)) were significantly increased, and metabolites of amino acid pathway (such as l-glutamine, proline, phenylalanine) showed a downregulation trend. Dysregulation of lipid and glutathione pathways is the major contributor to progression of T2DOP in C57BKS mice.

Metformin attenuates diabetes-induced osteopenia in rats is associated with down-regulation of the RAGE-JAK2-STAT1 signal axis

Background

Osteopenia and fragile fractures are diabetes-associated complications. Many hypoglycemic drugs have effects on bone metabolism. Metformin, as is a prescribed medication for type 2 diabetes mellitus (T2DM), had been reported to have osteoprotective effects beyond its hypoglycemic effect, however the potential mechanism behind these effects remains unclear. In this study, we aimed to investigate the comprehensive effects of metformin on bone metabolism in T2DM rat model and elucidate the potential mechanism.

Methods

Goto-Kakizaki spontaneous T2DM rats with significant hyperglycemia were treated with/without metformin for 20 weeks. Glucose tolerance was tested and all rats were weighed every two weeks. The osteoprotective effects of metformin in diabetic rats were determined by quantifying serum bone biomarkers, μ-CT imaging, histological staining, bone histomorphometry, and biomechanical properties analyses. Potential targets of metformin in the treatment of T2DM and osteoporosis were predicted using network pharmacology. The effects of metformin on mesenchymal stem cells (C3H10) cultured in high glucose medium were evaluated by CCK-8 assay, alkaline phosphatase (ALP) staining, qPCR and western blotting.

Results

This study demonstrated that metformin significantly attenuated osteopenia, decreased serum glucose and glycated serum protein (GSP) levels, improved bone microarchitecture, and biomechanical properties in GK rats with T2DM. Metformin significantly increased biomarkers of bone formation, and significantly decreased muscle ubiquitin C (Ubc) expression. Network pharmacology analysis found that signal transducer and activator of transcription1 (STAT1) would be a potential target of metformin for regulating bone metabolism. Metformin increased C3H10 ​cell viability in vitro, alleviated ALP inhibition caused by hyperglycemia, increased the osteogenic gene expression of runt-related transcription factor 2 (RUNX2), collagen type I alpha 1 (Col1a1), osteocalcin (OCN), and ALP, while suppressing RAGE and STAT1 expression. Metformin also increased the protein expression of Osterix and decreased that of RAGE, p-JAK2, and p-STAT1.

Conclusions

Our results demonstrate that metformin attenuated osteopenia and improved bone microarchitecture in GK rats with T2DM and significantly promoted stem cell osteogenic differentiation under high glucose condition. The effects of metformin on bone metabolism are closely associated with the suppression of RAGE-JAK2-STAT1 signaling axis.

The translational potential of this article

Our research provides experiment evidence and potential mechanistic rationale for the use of metformin as an effective candidate for diabetes-induced osteopenia treatment.

Animal Model for Glucocorticoid Induced Osteoporosis: A Systematic Review from 2011 to 2021

Clinical and experimental data have shown that prolonged exposure to GCs leads to bone loss and increases fracture risk. Special attention has been given to existing emerging drugs that can prevent and treat glucocorticoid-induced osteoporosis GIOP. However, there is no consensus about the most relevant animal model treatments on GIOP. In this systematic review, we aimed to examine animal models of GIOP centering on study design, drug dose, timing and size of the experimental groups, allocation concealment, and outcome measures. The present review was written according to the PRISMA 2020 statement. Literature searches were performed in the PubMed electronic database via Mesh with the publication date set between April, 2011, and February 2021. A total of 284 full-text articles were screened and 53 were analyzed. The most common animal species used to model GIOP were rats (66%) and mice (32%). In mice studies, males (58%) were preferred and genetically modified animals accounted for 28%. Our work calls for a standardization of the establishment of the GIOP animal model with better precision for model selection. A described reporting design, conduction, and selection of outcome measures are recommended.

Tooth hop variability in human and nonhuman bone: Effect on the estimation of saw blade TPI

Forensic research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to estimate teeth-per-inch (TPI) of a saw used in postmortem dismemberment cases. However, error rates for TPI estimation are still under development and knowledge of how bone tissue affects TH measurements remains unclear. The purpose of this research was to investigate the effects of tissue variability through the use of different taxa on the accuracy and precision of TH measurements in the bone to estimate TPI of the blade. A total of 1766 TH measurements were analyzed from human, pig, and deer long bones cut by two 7 TPI saw blades of different tooth type. Fifty distance-between-teeth measurements before and after sawing were collected directly from each blade for comparison to bone-measured TH to assess potential effects of tooth wear on TH variability. ANOVA and F tests were used to compare mean TH and variance, respectively, by saw-species (i.e., crosscut-deer, rip-deer) and species groups (i.e., all deer, all pig), with significance determined at the p < 0.05 level. TH measurements were converted to usable TPI ranges, which would typically be presented in a forensic report. It is concluded that significant differences in TH (mm) do not necessarily reflect significant differences in associated TPI ranges of suspect blades. Forensic reports should report mean TPI ± 1.5-2.5 TPI while providing a sample size indicating number of TH measured rather than just number of cuts or cut surfaces examined.

Effects of Long-Term Methotrexate, Infliximab, and Tocilizumab Administration on Bone Microarchitecture and Tendon Morphology in Healthy Wistar Rats

Objective

Rheumatic diseases are associated with bone loss, both systemic and periarticular, and tendon abnormalities. The aim of this study is to examine the effect of three antiarthritic drugs, methotrexate, an anti-folate metabolite; infliximab, a Tumor Necrosis Factor-alpha (TNF-α) inhibitor; and tocilizumab, an antibody against Interleukin-6 (IL-6) receptor, on bone microarchitecture and tendon morphology in the absence of an inflammatory state.

Materials and methods

Thirty-five, 8- to 9-week-old, male, Wistar rats were randomly allocated into five groups: negative control (CTRL), vehicle (VEH), methotrexate (MTX), infliximab (INFX), and tocilizumab (TCZ). After 8 weeks of antiarthritic drug intraperitoneal administration, animals were euthanized and rat tibiae and patellar tendons were histologically examined.

Results

All sections exhibited normal bone microarchitecture. Histological scores in all groups corresponded to normal bone mineral density. No no apparent differences in tenocyte morphology and architecture of collagen fibers were observed.

Conclusions

The results of this study indicate that long-term administration of methotrexate, infliximab, and tocilizumab had no effect on bone microarchitecture and tendon morphology in rats in the absence of an inflammatory condition.

Musculoskeletal Manifestations in Sjogren's Syndrome: An Orthopedic Point of View

Sjogren's syndrome (SS) is a frequent entity with a broad symptomatology spectrum, mainly affecting the salivary and lachrymal glands. The disease also affects the musculoskeletal system targeting bones, specific joints, muscles, and the peripheral nerve system. Disease related clinical manifestations canhave an accumulative impact, as the syndrome is commonly associated with other rheumatic diseases. A literature review was performed with the aim to assess the in-depth association of Sjogren's syndrome and its treatment agents with the musculoskeletal system and further investigate its potential relevance with common orthopedic postoperative complications.

Methotrexate osteopathy: five cases and systematic literature review

INTRODUCTION

Methotrexate (MTX)-related osteopathy is rare, defined by the triad of pain, osteoporosis, and "atypical fractures" when it was first described in the 1970s in children treated with high doses MTX for acute leukemia. Since then, several cases have been reported in patients treated with low-dose MTX for inflammatory diseases.

METHODS

A systematic research of cases of MTX-related osteopathy was performed in records of Rheumatology Department of Rennes University Hospital. Data collection focused on demographic data, corticosteroid doses, MTX doses and intake method, cumulative doses, year of diagnosis, fracture location, bone densitometry value, and osteoporosis treatment if necessary. A literature review was also conducted to identify other cases in literature and try to understand the pathophysiological mechanisms of this rare entity.

RESULTS

We report 5 cases identified between 2011 and 2019, which represents the largest cohort described excluding oncology cases. Fracture locations were atypical for osteoporotic fractures. All patients improved in the following months with MTX withdrawal. All patients except one were treated with antiresorptives (bisphosphonates, denosumab). Two patients, treated with bisphosphonates, had a recurrence of fracture, once again of atypical location. Twenty-five cases were collected in literature with similar clinical presentation. The cellular studies that investigated the bone toxicity of MTX mainly showed a decrease in the number of osteoblasts, osteocytes, and chondrocytes in the growth plate and an increase in the number and activity of osteoclasts. In vitro, consequences of mechanical stimulation on human trabecular bone cells in the presence of MTX showed an alteration in mechano-transduction, with membrane hyperpolarization, acting on the integrin pathway. In contrast with our report, the cases described in the literature were not consistently associated with a decrease in bone mineral density (BMD).

CONCLUSION

MTX osteopathy while rare must be known by the rheumatologist, especially when using this treatment for inflammatory conditions. The mechanisms are still poorly understood, raising the question of a possible remnant effect of MTX on osteo-forming bone cells, potentially dose-dependent. Methotrexate (MTX) osteopathy, described as a clinical triad, pain, osteoporosis, and atypical stress fractures, while rare, must be known by the rheumatologist. Our cohort of 5 cases represent the largest series of the literature. Pathophysiological studies raised the question of a dose-dependent remnant effect of MTX on osteo-forming bone cells.

The Role of Piper sarmentosum Aqueous Extract as a Bone Protective Agent, a Histomorphometric Study

Glucocorticoids are one of the causes of secondary osteoporosis. The aqueous extract of Piper sarmentosum contains flavonoids that possess antioxidant effects. In this study, we determined the effects of aqueous Piper sarmentosum leaf extract on structural, dynamic and static histomorphometric changes from osteoporotic bones of rats induced with glucocorticoids. Thirty-two Sprague-Dawley rats were divided equally into four groups—Sham control group given vehicles (intramuscular (IM) olive oil and oral normal saline); AC: Adrenalectomised (Adrx) control group given IM dexamethasone (DEX) (120 μg/kg/day) and vehicle (oral normal saline); AP: Adrx group administered IM DEX (120 μg/kg/day) and aqueous Piper sarmentosum leaf extract (125 mg/kg/day) orally; and AG: Adrx group administered IM DEX (120 μg/kg/day) and oral glycyrrhizic acid (GCA) (120 mg/kg/day). Histomorphometric measurements showed that the bone volume, trabecular thickness, trabecular number, osteoid and osteoblast surfaces, double-labelled trabecular surface, mineralizing surface and bone formation rate of rats given aqueous Piper sarmentosum leaf extract were significantly increased (p < 0.05), whereas the trabecular separation and osteoclast surface were significantly reduced (p < 0.05). This study suggests that aqueous Piper sarmentosum leaf extract was able to prevent bone loss in prolonged glucocorticoid therapy. Thus, Piper sarmentosum has the potential to be used as an alternative medicine against osteoporosis and osteoporotic fractures in patients undergoing long-term glucocorticoid therapy.

Etoricoxib decreases subchondral bone mass and attenuates biomechanical properties at the early stage of osteoarthritis in a mouse model

Etoricoxib, a selective Cyclooxygenase-2 (COX-2) inhibitor, is commonly used in osteoarthritis (OA) for pain relief, however, little is known about the effects on subchondral bone. In the current study, OA was induced via destabilization of the medial meniscus (DMM) in C57BL/6 mice. Two days after surgery, mice were treated with different concentrations of Etoricoxib. Four weeks after treatment, micro computed tomography (Micro-CT) analysis, histological analysis, atomic force microscopy (AFM) analysis, and scanning electron microscopy (SEM) were performed to evaluate OA progression. We demonstrated that Etoricoxib inhibited osteophyte formation in the subchondral bone. However, it also reduced the bone volume fraction (BV/TV), lowered trabecular thickness (Tb.Th), and more microfractures and pores were observed in the subchondral bone. Moreover, Etoricoxib reduced the elastic modulus of subchondral bone. Exposure to Etoricoxib further increased the empty/total osteocyte ratio of the subchondral bone. Etoricoxib did not show significant improvement in articular cartilage destruction and synovial inflammation in early OA. Together, our observations suggested that although Etoricoxib can relieve OA-induced pain and inhibit osteophyte formation in the subchondral bone, it can also change the microstructures and biomechanical properties of subchondral bone, promote subchondral bone loss, and reduce subchondral bone quality in early OA mice.

Dexamethasone: chondroprotective corticosteroid or catabolic killer?

While glucocorticoids have been used for over 50 years to treat rheumatoid and osteoarthritis pain, the prescription of glucocorticoids remains controversial because of potentially harmful side effects at the molecular, cellular and tissue levels. One member of the glucocorticoid family, dexamethasone (DEX) has recently been demonstrated to rescue cartilage matrix loss and chondrocyte viability in animal studies and cartilage explant models of tissue injury and post-traumatic osteoarthritis, suggesting the possibility of DEX as a disease-modifying drug if used appropriately. However, the literature on the effects of DEX on cartilage reveals conflicting results on the drug's safety, depending on the dose and duration of DEX exposure as well as the model system used. Overall, DEX has been shown to protect against arthritis-related changes in cartilage structure and function, including matrix loss, inflammation and cartilage viability. These beneficial effects are not always observed in model systems using initially healthy cartilage or isolated chondrocytes, where many studies have reported significant increases in chondrocyte apoptosis. It is crucially important to understand under what conditions DEX may be beneficial or harmful to cartilage and other joint tissues and to determine potential for safe use of this glucocorticoid in the clinic as a disease-modifying drug.

MiR-291a-3p regulates the BMSCs differentiation via targeting DKK1 in dexamethasone-induced osteoporosis

Osteoporosis is a skeleton disease affecting 55% of people over age 60, and the number is still increasing due to an ageing population. One method to prevent osteoporosis is to increase the formation of new bone while preventing the resorption of older bone. Thus, osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) is of great importance in improving the treatment of osteoporosis. On the other hand, glucocorticoids (GCs) are widely used to treat the chronic inflammatory disorders, but long-term exposure to GCs can induce osteoporosis. In present study, we treated BMSCs with dexamethasone (DEX) to simulate GC-induced osteoporosis. MTT assay, ALP activity, and Alizarin Red were used to evaluate the role miRNA-291a-3p in the DEX-induced osteogenic differentiation suppression. Further, we used qPCR and western blot to investigate the mechanisms of miRNA-291a-3p affecting BMSCs differentiation. The results showed that miRNA-291a-3p could improve the cell viability, osteogenic differentiation, and ALP activity, which are suppressed by DEX in BMSCs. Furthermore, we found that the osteogenesis genes Runx2, DMP1, and ALP were upregulated whereas the lipogenic genes C/EBPα and PPARγ were downregulated when miRNA-291a-3p mimics were transfected. Additionally, we demonstrated that miRNA-291a-3p promoted BMSCs' osteogenic differentiation by directly suppressing DKK1 mRNA and protein expression and subsequently activating Wnt/β-catenin signaling pathway. Our study suggests that miR-291a-3p plays an important role in preventing osteoporosis and may serve as a potential miRNA osteoporosis biomarker.

Effects of Therapeutic Doses of Celecoxib on Several Physiological Parameters of Cultured Human Osteoblasts

Non-steroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase-2 (COX-2)-selective NSAIDs, are associated with adverse effects on bone tissue. These drugs are frequently the treatment of choice but are the least studied with respect to their repercussion on bone. The objective of this study was to determine the effects of celecoxib on cultured human osteoblasts. Human osteoblasts obtained by primary culture from bone samples were treated with celecoxib at doses of 0.75, 2, or 5μM for 24 h. The MTT technique was used to determine the effect on proliferation; flow cytometry to establish the effect on cell cycle, cell viability, and antigenic profile; and real-time polymerase chain reaction to measure the effect on gene expressions of the differentiation markers RUNX2, alkaline phosphatase (ALP), osteocalcin (OSC), and osterix (OSX). Therapeutic doses of celecoxib had no effect on osteoblast cell growth or antigen expression but had a negative impact on the gene expression of RUNX2 and OSC, although there was no significant change in the expression of ALP and OSX. Celecoxib at therapeutic doses has no apparent adverse effects on cultured human osteoblasts and only inhibits the expression of some differentiation markers. These characteristics may place this drug in a preferential position among NSAIDs used for analgesic and anti-inflammatory therapy during bone tissue repair.

1,25-Dihydroxy vitamin D3 treatment attenuates osteopenia, and improves bone muscle quality in Goto-Kakizaki type 2 diabetes model rats

PURPOSE

Osteopenia and skeletal fragility are considered to be the complications associated with type 2 diabetes mellitus (T2DM). The relationship between glucose metabolism, skeletal quality, and vitamin D have not been completely understood. We aimed to demonstrate a comprehensive bone quality profile in a T2DM model subject and to investigate whether 1, 25-dihydroxy vitamin D3 could prevent osteopenia and skeletal fragility in the diabetes model rats.

METHODS

Daily calcitriol (a 1, 25-dihydroxy vitamin D3 formulation, 0.045 μg/kg/day) treatment was administered to 21-week-old male Goto-Kakizaki (GK) rats (a genetic non-obese and non-insulin-dependent spontaneous diabetes rat model) for 20 weeks and the results were compared with those in untreated GK rats, and wild-type animals.

RESULTS

Micro-computed tomography, histomorphometry, and bone mineral density analysis demonstrated that T2DM induced significant osteopenia, and impairment of bone microarchitecture and biomechanical properties in GK rats. T2DM also significantly decreased bone formation and increased bone resorption parameters in three regions of the skeleton (proximal tibia, mid-shaft of the tibia, and lumbar vertebrae), and increased carboxy-terminal type I collagen crosslinks, tartrate-resistant acid phosphatase, muscle ubiquitin C, and bone thioredoxin interacting protein (TXNIP) expression. Calcitriol treatment significantly alleviated bone loss, and improved bone microarchitecture and biomechanical properties and also decreased serum glucose and glycated serum protein levels. Biomarkers of bone formation were significantly increased, while muscle ubiquitin C and bone TXNIP expression were significantly decreased following calcitriol treatment.

CONCLUSIONS

These results suggest that 1,25-dihydroxy vitamin D3 treatment effectively attenuates osteopenia, and improves bone and muscle quality in GK type 2 diabetes model rats.

Sargassum integerrimum inhibits oestrogen deficiency and hyperlipidaemia-induced bone loss by upregulating nuclear factor (erythroid-derived 2)-like 2 in female rats

Ethnopharmacological relevance

Oestrogen deficiency, high incidences of hyperlipidaemia (HLP) and accelerated bone loss frequently occur in postmenopausal women. There is an urgent need to develop functional foods or specific drugs to protect against bone loss induced by oestrogen deficiency with HLP.

Aim of the study

In this study, we investigated the potential inhibitory effects of Sargassum integerrimum (SI) on bone loss in an ovariectomized rat model with HLP.

Materials and methods

The rats were treated for 12 weeks, and then, bone mineral density, bone biomechanical, bone microstructure, bone morphology, biomarkers of HLP oxidative stress and side effects were determined. Immunohistochemical staining and Western blot were performed to evaluate related protein expression.

Results

The femur bone mineral density increased (P < 0.05), and the microscopic structures (ratio of bone volume to total volume [BV/TV], connectivity density [Conn.D], trabecular number [Tb.N] and trabecular thickness [Tb.Th]) of the bone trabecula and mechanical properties (maximum and breaking load [ML and BL, respectively]) improved after SI treatment (P < 0.05). Furthermore, the levels of HLP biomarkers (total cholesterol, triglyceride and low-density lipoprotein) were significantly decreased (P < 0.05), whereas the levels of antioxidant markers (superoxide dismutase and total antioxidant capacity) were increased (P < 0.05). Similar results were obtained with immunohistochemical staining, whereas the Western blot assay showed that SI stimulated the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in bone.

Conclusion

Our data indicate that rats exposed to SI treatment for 12 weeks did not exhibit noticeable side effects. In conclusion, SI suppressed bone loss induced by ovariectomized and the associated HLP in rats by activating Nrf2, which could be a promising treatment option for osteoporosis induced by oestrogen deficiency and HLP in postmenopausal women.

Translational scope statement

Our study verified that SI prevented bone loss in rats with oestrogen deficiency with HLP by upregulating nuclear factor (erythroid-derived 2)-like 2. Furthermore, no side effect was observed after the long-term administration of SI. Those results suggested SI could be developed as a functional food or drug for postmenopausal osteoporosis induced by oestrogen deficiency with HLP.

Quercetin rescued TNF-alpha-induced impairments in bone marrow-derived mesenchymal stem cell osteogenesis and improved osteoporosis in rats

To investigate the effect of quercetin on promoting the proliferation of bone marrow mesenchymal stem cells (BMSCs) and improving osteoporosis in rats. Rats were randomly divided into the sham, OVX and quercetin+OVX groups. In the sham and OVX groups, rats were given carboxymethyl cellulose sodium (CMC-Na). In the quercetin+OVX group, rats were given quercetin (50 mg/kg) once a day. Eight weeks after rats were treated, femurs were subjected to micro-CT scans, and bone biomechanical properties were analysed by the three-point flexural test. In addition, BMSCs were isolated and characterised by MTT, RT-PCR and Western blot analysis. In vivo, quercetin increased bone mineral density (BMD) and improved bone biomechanical properties in postmenopausal osteoporosis rat models. In vitro, TNF-α led to the activation of nuclear factor-kappa B (NF-κB) and the degradation of β-catenin, which were significantly inhibited by quercetin. Furthermore, quercetin promoted BMSC proliferation and osteogenic differentiation. In conclusion, quercetin improved in vitro models of osteoporosis and protected against TNF-α-induced impairments in BMSC osteogenesis.

Disease-modifying effects of COX-2 selective inhibitors and non-selective NSAIDs in osteoarthritis: a systematic review

Osteoarthritis (OA) is a potentially disabling disease whose progression is dependent on several risk factors. OA management usually involves the use of non-steroidal anti-inflammatory drugs (NSAIDs) that are the primary pharmacological treatments of choice. However, NSAIDs have often been associated with unwanted side effects. Cyclooxygenase (COX)-2 specific inhibitors, such as celecoxib, have been successfully used as an alternative in the past for OA treatment and have demonstrated fewer side effects. While abundant data are available for the clinical efficacy of drugs used for OA treatment, little is known about the disease-modifying effects of these agents. A previous review published by Zweers et al. (2010) assessed the available literature between 1990 and 2010 on the disease-modifying effects of celecoxib. In the present review, we aimed to update the existing evidence and identify evolving concepts relating to the disease-modifying effects of not just celecoxib, but also other NSAIDs. We conducted a review of the literature published from 2010 to 2016 dealing with the effects, especially disease-modifying effects, of NSAIDs on cartilage, synovium, and bone in OA patients. Our results show that celecoxib was the most commonly used drug in papers that presented data on disease-modifying effects of NSAIDs. Further, these effects appeared to be mediated through the regulation of prostaglandins, cytokines, and direct changes to tissues. Additional studies should be carried out to assess the disease-modifying properties of NSAIDs in greater detail.

Glucocorticoid-induced delayed fracture healing and impaired bone biomechanical properties in mice

Background

The objective of the study was to investigate the effects of glucocorticoid (GC) on the fracture healing process in a closed femur fracture mice model.

Materials and methods

Forty 12-week-old female CD-1 mice were randomly allocated into four groups: healthy control and mice with prednisone exposure (oral gavage), 6 mg/kg/day (GC-L), 9 mg/kg/day (GC-M) and 12 mg/kg/day (GC-H). Three weeks after the initiation of prednisone dosing, closed femur fractures were created on prednisone-exposed mice and the healthy control. Prednisone administration was continued for 9 weeks post-fracture, and X-ray imaging was performed weekly to monitor the fracture healing process until the mice were euthanized. Necropsy was performed after 9 weeks and the fractured femurs were isolated and processed at necropsy for micro-CT and biomechanical property analysis. Another 20 mice (control and GC-H, 10 mice/group) were used for histology and micro-CT analysis at early time point (2-week post fracture) with continued prednisone exposure.

Results

The results showed that oral administration of prednisone for 3 months in this strain of mice could inhibit endochondral ossification and delay the healing process, especially hard callus formation (woven bone) and bone remodeling during healing. It also could significantly decrease bone biomechanical properties.

Conclusion

Long-term GC administration leads to significantly delayed fracture healing and impaired bone biomechanical properties. This mouse model may be used to systematically study the cellular and molecular mechanisms underlying fracture healing with GC treatment background and may also be used to study the influence of different therapeutic interventions for bone fracture healing.

Metabolomics Based Profiling of Dexamethasone Side Effects in Rats

Dexamethasone (Dex) is a synthetic glucocorticoid that has anti-inflammatory and immunosuppressant effects and is used in several conditions such as asthma and severe allergy. Patients receiving Dex, either at a high dose or for a long time, might develop several side effects such as hyperglycemia, weight change, or osteoporosis due to its in vivo non-selectivity. Herein, we used liquid chromatography-tandem mass spectrometry-based comprehensive targeted metabolomic profiling as well as radiographic imaging techniques to study the side effects of Dex treatment in rats. The Dex-treated rats suffered from a ∼20% reduction in weight gain, hyperglycemia (145 mg/dL), changes in serum lipids, and reduction in total serum alkaline phosphatase (ALP) (∼600 IU/L). Also, compared to controls, Dex-treated rats showed a distinctive metabolomics profile. In particular, serum amino acids metabolism showed six-fold reduction in phenylalanine, lysine, and arginine levels and upregulation of tyrosine and hydroxyproline reflecting perturbations in gluconeogenesis and protein catabolism which together lead to weight loss and abnormal bone metabolism. Sorbitol level was markedly elevated secondary to hyperglycemia and reflecting activation of the polyol metabolism pathway causing a decrease in the availability of reducing molecules (glutathione, NADPH, NAD+). Overexpression of succinylacetone (4,6-dioxoheptanoic acid) suggests a novel inhibitory effect of Dex on hepatic fumarylacetoacetate hydrolase. The acylcarnitines, mainly the very long chain species (C12, C14:1, C18:1) were significantly increased after Dex treatment which reflects degradation of the adipose tissue. In conclusion, long-term Dex therapy in rats is associated with a distinctive metabolic profile which correlates with its side effects. Therefore, metabolomics based profiling may predict Dex treatment-related side effects and may offer possible novel therapeutic interventions.

Polygonum multiflorm alleviates glucocorticoid‑induced osteoporosis and Wnt signaling pathway

It is known that long-term excessive administration of glucocorticoid (GC) results in osteoporosis. The present study aimed to evaluate the protective effects of Polygonum multiflorm (PM) on the bone tissue of rats with GC-induced osteoporosis (GIO). A total of 90 6-month-old female Sprague Dawley rats (weight range, 190–210 g) were randomly divided into nine groups: Control (normal saline); prednisone (GC; 6 mg·kg⁻¹·d⁻¹; Model); GC plus PMR30 (the 30% ethanol eluent fraction of PM) (H) (400 mg·kg⁻¹·d⁻¹); GC plus PMR30 (M) (200 mg·kg⁻¹·d⁻¹); GC plus PMR30 (L) (100 mg·kg⁻¹·d⁻¹); GC plus PMRF (fat-soluble fraction of PM) (H) (400 mg·kg⁻¹·d⁻¹); GC plus PMRF (M) (200 mg·kg⁻¹·d⁻¹); GC plus PMRF (L) (100 mg·kg⁻¹·d⁻¹); GC plus calcitriol (CAL; 0.045 µg·kg⁻¹·d⁻¹; positive). Rats were administered intragastrically with prednisone and/or the aforementioned extracts for 120 days, and weighed once/week. The serum was collected for detection of biochemical markers. The left tibia was used for bone histomorphometry analysis. The right tibia was prepared for hematoxylin and eosin staining. The left femur was used to analyze the protein expression of dickkopf-1 (DKK1), WNT inhibitory factor 1 (WIF1) and secreted frizzled related protein 4 using western blotting. Long-term excessive treatment of prednisone inhibited the bone formation rate accompanied with a decrease in bone mass, growth plate, body weight, and the level of bone-specific alkaline phosphatase and hydroxyl-terminal propeptide of type I procollagen in the serum. Furthermore, a simultaneously increase in the level of tartrate resistant acid phosphatase-5b and cross-linked carboxy-terminal telopeptide of type I collagen in the serum, in addition to DKK1, and WIF1 protein expression, was observed. PMR30 (M and L) and PMRF (H) groups were able to reduce the negative effects of GC on the bones. PMR30 (M and L) and PMRF (H) dose demonstrated a protective effect of PM on bone tissue in GIO rats. The mechanism underlying the preventive effect of PM for the treatment of GIO may be associated with direct upregulation of the canonical Wnt/β-catenin signaling pathway.

Increased baseline RUNX2, caspase 3 and p21 gene expressions in the peripheral blood of disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis patients are associated with improved clinical response to methotrexate therapy

OBJECTIVE

To investigate the potential of the baseline gene expression in the whole blood of disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis (RA) patients for predicting the response to methotrexate (MTX) treatment.

METHODS

Twenty-six control subjects and 40 RA patients were examined. Clinical, immunological and radiographic parameters were assessed before and after 24 months of follow-up. The gene expressions in the whole blood were measured using real-time reverse transcription polymerase chain reaction. The protein concentrations in peripheral blood mononuclear cells were quantified using enzyme-linked immunosorbent assay. Receiver operating characteristic curve analyses were used to suggest thresholds that were associated with the prediction of the response.

RESULTS

Decreases in the disease activity at the end of the study were accompanied by significant increases in joint space narrowing score (JSN). Positive correlations between the expressions of the Unc-51-like kinase 1 (ULK1) and matrix metalloproteinase 9 (MMP-9) genes with the level of C-reactive protein and MMP-9 expression with Disease Activity Score of 28 joints (DAS28) and swollen joint count were noted at baseline. The baseline tumor necrosis factor (TNF)α gene expression was positively correlated with JSN at the end of the follow-up, whereas p21, caspase 3, and runt-related transcription factor (RUNX)2 were correlated with the ΔDAS28 values.

CONCLUSIONS

Our results suggest that the expressions of MMP-9 and ULK1 might be associated with disease activity. Increased baseline gene expressions of RUNX2, p21 and caspase 3 in the peripheral blood might predict better responses to MTX therapy.

miR-365 Ameliorates Dexamethasone-Induced Suppression of Osteogenesis in MC3T3-E1 Cells by Targeting HDAC4

Glucocorticoid administration is the leading cause of secondary osteoporosis. In this study, we tested the hypotheses that histone deacetylase 4 (HDAC4) is associated with glucocorticoid-induced bone loss and that HDAC4 dependent bone loss can be ameliorated by miRNA-365. Our previous studies showed that miR-365 mediates mechanical stimulation of chondrocyte proliferation and differentiation by targeting HDAC4. However, it is not clear whether miR-365 has an effect on glucocorticoid-induced osteoporosis. We have shown that, in MC3T3-E1 osteoblasts, dexamethasone (DEX) treatment decreased the expression of miR-365, which is accompanied by the decrease of cell viability in a dose-dependent manner. Transfection of miR-365 ameliorated DEX-induced inhibition of MC3T3-E1 cell viability and alkaline phosphatase activity, and attenuated the suppressive effect of DEX on runt-related transcription factor 2 (Runx2), osteopontin (OPN), and collagen 1a1 (Col1a1) osteogenic gene expression. In addition, miR-365 decreased the expression of HDAC4 mRNA and protein by direct targeting the 3′-untranslated regions (3′-UTR) of HDAC4 mRNA in osteoblasts. MiR-365 increased Runx2 expression and such stimulatory effect could be reversed by HDAC4 over-expression in osteoblasts. Collectively, our findings indicate that miR-365 ameliorates DEX-induced suppression of cell viability and osteogenesis by regulating the expression of HDAC4 in osteoblasts, suggesting miR-365 might be a novel therapeutic agent for treatment of glucocorticoid-induced osteoporosis.

Effects of the combined Herba Epimedii and Fructus Ligustri Lucidi on bone turnover and TGF-β1/Smads pathway in GIOP rats

ETHNOPHARMACOLOGICAL RELEVANCE

Kidney deficiency is the main pathogenesis of osteoporosis based on the theory of "kidney governing bones" in traditional Chinese medicine (TCM). Combined Herba Epimedii and Fructus Ligustri Lucidi, based on traditional Chinese formula Er-Zhi pills, were frequently used in TCM formulas that were prescribed for kidney tonifying and bone strengthening. However, it is unclear whether the combination of the two herbs may have a protective influence on glucocorticoid-induced osteoporosis (GIOP). The objective of this study was to evaluate the therapeutic effects and the underlying molecular mechanism of the decoction and the active fractions of the combined herbs in GIOP rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats were divided into seven groups, including the normal control (NC), GIOP model (MO), active fractions low (100mg/kg, LAF), active fractions high (200mg/kg, HAF), decoction low (3.5g/kg, LD), decoction high (7g/kg, HD) and Calcium with Vitamin D3 (0.2773g/kg, CaD)-treated group. The GIOP model was established by intramuscular injection of dexamethasone (1mg/kg) twice a week for 8 weeks. Different kinds of indicators were measured, including bone mineral density (BMD), bone biomechanical properties, serum bone alkaline phosphatase (b-ALP), serum bone γ-carboxyglutamic acid-containing protein (BGP), serum bone morphogenetic protein-2 (BMP-2), serum tartrate-resistant acid phosphatase (TRACP) and serum carboxy terminal cross linked telopeptide of typeⅠcollagen (ICTP), bone mineral content (BMC) and bone structured histomorphometry. The protein and mRNA expression of TGF-β1, Smad2, Smad3, Smad4 and Smad7 were detected by Western blotting (WB) and quantitative real time polymerase chain reaction (qRT-PCR), respectively.

RESULTS

Administration of combined Herba Epimedii and Fructus Ligustri Lucidi decoction and combined active fractions could significantly prevent GC-induced bone loss by increasing the contents of serum b-ALP, BGP and BMP-2 as the markers of bone formation, reducing the serum TRACP and ICTP contents to inhibit bone resorption and enhancing BMC. They could also attenuate biomechanical properties and BMD reduction, deterioration of trabecular architecture in MO rats. The mRNA and protein expressions of TGF-β1, smad2, smad3 and smad4 were up-regulated, and the mRNA and protein expression of Smad7 was down-regulated following combined Herba Epimedii and Fructus Ligustri Lucidi treatment.

CONCLUSION

Combination of Herba Epimedii and Fructus Ligustri Lucidi exhibited protective effects on promoting bone formation and precluding bone resorption. The underlying mechanism may be attributed to its regulations on TGF-β1/Smads pathway. The substance bases of the combined herbs on anti-osteoporosis were total flavonoids of Herba Epimedii, total iridoids and flavonoids of Fructus Ligustri Lucidi.

Effects of salvianolate on bone metabolism in glucocorticoid-treated lupus-prone B6.MRL-Fas (lpr) /J mice

Aim

To investigate the bone-protective effects of salvianolate (Sal), a total polyphenol from Radix Salviae miltiorrhizae, on bone tissue in the spontaneous lupus-prone mouse model, B6.MRL-Fas^lpr/J, undergoing glucocorticoid (GC) treatment.

Methods

Fifteen-week-old female B6.MRL-Fas^lpr/J mice were administered either a daily dose of saline (lupus group), prednisone 6 mg/kg (GC group), Sal 60 mg/kg (Sal group); or GC plus Sal (GC + Sal group) for a duration of 12 weeks. Age-matched female C57BL/6J wild-type (WT) mice were used for control. Micro-computed tomography assessments, bone histomorphometry analysis, bone biomechanical test, immunohistochemistry and immunoblotting analysis for bone markers, and renal histology analysis were performed to support our research endeavor.

Results

Lupus mice developed a marked bone loss and deterioration of mechanical properties of bone due to an increase in bone resorption rather than suppression of bone formation. GC treatment strongly inhibited bone formation in lupus mice. Sal treatment significantly attenuated osteogenic inhibition, and also suppressed hyperactive bone resorption, which recovered the bone mass and mechanical properties of bone in both the untreated and GC-treated lupus mice.

Conclusion

The data support further preclinical investigation of Sal as a potential therapeutic strategy for the treatment of systemic lupus erythematosus-related bone loss.

Effects of short-term glucocorticoid administration on bone mineral density, biomechanics and microstructure in rats’ femur

The effects of short-term use of oral glucocorticoid (GC) on the skeleton are not well defined. To address this gap, the influences of 7 days, 21 days of GC administration on femurs of intact rats were investigated. Forty 4-month-old female Sprague–Dawley rats were randomly divided into control group (Cont) and prednisone-treated group (Pre) and administered either distilled water or prednisone acetate at doses of 3.5 mg/kg/day for 0, 7 and 21 days, respectively. All the femurs were harvested for dual-energy X-ray absorptiometry scan, biomechanical testing and micro computed tomography scan. The whole body weight, femur bone mineral density (BMD), all three-point bending test parameters, microstructural parameters increased or improved significantly in Cont at day 21 when compared to day 0. The whole body weight, distal femur BMD, Young’s modulus, bending stiffness, density of tissue volume and trabecular thickness (Tb.Th) decreased, while structure model index and trabecular separation (Tb.Sp) increased significantly in Pre at day 21 when compared to age-matched control but had no significant differences between day 7 and day 21. Our data demonstrate that 7-day use of prednisone does not influence on rats’ femur, and 21-day use of prednisone slows in rate of whole body weight gain, decreases femur metaphysis BMD and bone stiffness which mainly due to the deteriorated bone microstructure.