TNF-α promotes osteoclastogenesis through JNK signaling-dependent induction of Semaphorin3D expression in estrogen-deficiency induced osteoporosis

Estrogen deficiency-mediated osteoimmunity in postmenopausal osteoporosis

Postmenopausal osteoporosis (PMO) is a common disease associated with aging, and estrogen deficiency is considered to be the main cause of PMO. Recently, however, osteoimmunology has been revealed to be closely related to PMO. On the one hand, estrogen deficiency directly affects the activity of bone cells (osteoblasts, osteoclasts, osteocytes). On the other hand, estrogen deficiency-mediated osteoimmunity also plays a crucial role in bone loss in PMO. In this review, we systematically describe the progress of the mechanisms of bone loss in PMO, estrogen deficiency-mediated osteoimmunity, the differences between PMO patients and postmenopausal populations without osteoporosis, and estrogen deficiency-mediated immune cells (T cells, B cells, macrophages, neutrophils, dendritic cells, and mast cells) activity. The comprehensive summary of this paper provides a clear knowledge context for future research on the mechanism of PMO bone loss.

Tumour necrosis factor α regulates the miR-27a-3p-Sfrp1 axis in a mouse model of osteoporosis

Osteoporosis is a metabolic bone disease that involves gradual loss of bone density and mass, thus resulting in increased fragility and risk of fracture. Inflammatory cytokines, such as tumour necrosis factor α (TNF-α), inhibit osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), and several microRNAs are implicated in osteoporosis development. This study aimed to explore the correlation between TNF-α treatment and miR-27a-3p expression in BMSC osteogenesis and further understand their roles in osteoporosis. An osteoporosis animal model was established using ovariectomized (OVX) mice. Compared with Sham mice, the OVX mice had a significantly elevated level of serum TNF-α and decreased level of bone miR-27a-3p, and in vitro TNF-α treatment inhibited miR-27a-3p expression in BMSCs. In addition, miR-27a-3p promoted osteogenic differentiation of mouse BMSCs in vitro, as evidenced by alkaline phosphatase staining and Alizarin Red-S staining, as well as enhanced expression of the osteogenic markers Runx2 and Osterix. Subsequent bioinformatics analysis combined with experimental validation identified secreted frizzled-related protein 1 (Sfrp1) as a downstream target of miR-27a-3p. Sfrp1 overexpression significantly inhibited the osteogenic differentiation of BMSCs in vitro and additional TNF-α treatment augmented this inhibition. Moreover, Sfrp1 overexpression abrogated the promotive effect of miR-27a-3p on the osteogenic differentiation of BMSCs. Furthermore, the miR-27a-3p-Sfrp1 axis was found to exert its regulatory function in BMSC osteogenic differentiation via regulating Wnt3a-β-catenin signalling. In summary, this study revealed that TNF-α regulated a novel miR-27a-3p-Sfrp1 axis in osteogenic differentiation of BMSCs. The data provide new insights into the development of novel therapeutic strategies for osteoporosis.

Prevention and Co-Management of Breast Cancer-Related Osteoporosis Using Resveratrol

Breast cancer (BC) is currently one of the most common cancers in women worldwide with a rising tendency. Epigenetics, generally inherited variations in gene expression that occur independently of changes in DNA sequence, and their disruption could be one of the main causes of BC due to inflammatory processes often associated with different lifestyle habits. In particular, hormone therapies are often indicated for hormone-positive BC, which accounts for more than 50-80% of all BC subtypes. Although the cure rate in the early stage is more than 70%, serious negative side effects such as secondary osteoporosis (OP) due to induced estrogen deficiency and chemotherapy are increasingly reported. Approaches to the management of secondary OP in BC patients comprise adjunctive therapy with bisphosphonates, non-steroidal anti-inflammatory drugs (NSAIDs), and cortisone, which partially reduce bone resorption and musculoskeletal pain but which are not capable of stimulating the necessary intrinsic bone regeneration. Therefore, there is a great therapeutic need for novel multitarget treatment strategies for BC which hold back the risk of secondary OP. In this review, resveratrol, a multitargeting polyphenol that has been discussed as a phytoestrogen with anti-inflammatory and anti-tumor effects at the epigenetic level, is presented as a potential adjunct to both support BC therapy and prevent osteoporotic risks by positively promoting intrinsic regeneration. In this context, resveratrol is also known for its unique role as an epigenetic modifier in the regulation of essential signaling processes-both due to its catabolic effect on BC and its anabolic effect on bone tissue.

Cytokines: The links between bone and the immune system

Osteoporosis results from an imbalance in a highly balanced physiological process called bone remodeling, in which osteoclast-mediated bone resorption and osteoblast-mediated bone formation play important roles. Osteoimmunology is a newly discovered interdisciplinary research field that focuses on the relationship between bone and the immune system. Specifically, bone and the immune system interact through cytokines, immune cells secrete cytokines, and cytokines finely regulate bone metabolism by mediating the differentiation and activity of osteoclasts and osteoblasts. Therefore, understanding the influence of cytokines on bone metabolism is conducive for the development of novel targeted drugs against immune-related bone diseases. This review summarizes the pathophysiological functions of various common cytokines in bone and discusses the potential clinical value of multiple cytokines in immune-mediated bone diseases.

Peripheral CD4+ /CD8+ T cell composition distinct from healthy individuals is shared by ankylosing spondylitis and rheumatoid arthritis

OBJECTIVE

Ankylosing spondylitis (AS) and rheumatoid arthritis (RA) are chronic inflammatory joint diseases, linking to the alterations of immune cells. We attempted to assess whether the alterations in the composition of CD4+ /CD8+ T cells are different between AS and RA and identify the characteristic cells between male and female patients.

METHODS

The proportions of CD3+ or double positive T cells, 6 CD4+ T subsets and 9 CD8+ T cell subsets were detected by flow cytometry and compared in 30 healthy individuals, 42 AS patients and 45 RA patients. The differentially altered cells were individually analyzed for associations with disease activity parameters. In addition, their proportions were compared between different genders in the 3 groups.

RESULTS

The proportions of CD4+ T cells, naive CD4+ T cells and central memory CD4+ T cells were lower in AS patients (P = 0.001, P = 0.002 and P = 0.007, respectively) and RA patients (P = 0.032, P < 0.001 and P = 0.016, respectively), but the proportion of effector memory ones was higher when compared with healthy populations (both P < 0.001), as were the decrease of naive/central memory CD8+ T cells in AS (P = 0.003 and P = 0.016, respectively) and RA (P < 0.001 and P = 0.006, respectively), and the increased tendency of terminally differentiated CD8+ T cells. However, these above-mentioned cells, regulatory T (Treg) cells and CD8+ T cells with different CD127 expressions between AS and RA were similar in proportion. Furthermore, naive CD4+ T cells were positively associated with C-reactive protein (CRP) in AS, whereas CD4+ T cells and terminally differentiated CD8+ T of RA patients were associated with CRP in RA. The gender-related alterations predominantly displayed the overexpressions of Treg cells and naive CD8+ T cells in female patients with AS and RA, respectively.

CONCLUSIONS

AS patients and RA patients have some similar peripheral CD4+ /CD8+ T cell subsets but are distinct from healthy individuals, which may contribute to disease severity. Females are respectively characterized by the up-regulation of Treg cells and naive CD8+ T cells in AS patients and RA patients. The study offers an in-depth understanding of the role of T cell subsets in the similarities of the disorders and helps us to monitor disease changes and may offer a theoretical basis of developing novel therapies against common targets.

Modulation of bone remodeling by the gut microbiota: a new therapy for osteoporosis

The gut microbiota (GM) plays a crucial role in maintaining the overall health and well-being of the host. Recent studies have demonstrated that the GM may significantly influence bone metabolism and degenerative skeletal diseases, such as osteoporosis (OP). Interventions targeting GM modification, including probiotics or antibiotics, have been found to affect bone remodeling. This review provides a comprehensive summary of recent research on the role of GM in regulating bone remodeling and seeks to elucidate the regulatory mechanism from various perspectives, such as the interaction with the immune system, interplay with estrogen or parathyroid hormone (PTH), the impact of GM metabolites, and the effect of extracellular vesicles (EVs). Moreover, this review explores the potential of probiotics as a therapeutic approach for OP. The insights presented may contribute to the development of innovative GM-targeted therapies for OP.

Using network pharmacology and molecular docking verification to explore the mechanism of ursolic acid in the treatment of osteoporosis

Whether ursolic acid is an effective drug in treatment of osteoporosis (OP) and how it exhibit activity effect on OP is unclear. To investigated the potential molecular mechanism of ursolic acid in the treatment of OP and figured out its possible mechanism is necessary. The target genes of ursolic acid were screened by using the database of traditional chinese medicine systems pharmacology, PubMed database and UniProt database. OP-related target genes were searched by GeneCards database, and utilized online mapping tool to obtain common target genes of component-disease. String database was used to construct a protein-protein interaction (PPI) network of component-disease common target genes and perform topological analysis to screen core target genes. DAVID database was performed gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for component-disease shared target genes. Using the core target protein as the receptor and ursolic acid as the ligand, the molecular docking was performed using AutoDockVina 1.1.2 software. A total of 52 ursolic acid-related target genes and 4657 OP-related target genes were excavated, with a total of collective 43 target genes. The above-mentioned PPI network with shared target genes contains 43 nodes and 510 edges, with an average node degree value of 23.32. A total of 24 core target genes were obtained, mainly including tumor protein p53 (TP53), vascular endothelial growth factor A (VEGFA), interleukin-6 (IL6), tumor necrosis factor (TNF), caspase3 (CASP3), matrix metallo protein (MMP9), transcription factor AP-1 (JUN), activator of transcription 3 (STAT3), mitogen-activated protein kinase 8 (MAPK8), and prostaglandin endoperoxidase 2 (PTGS2), respectively. According to KEGG enrichment analysis, there are 126 treatment of OP signaling pathway were enriched. GO enrichment analysis revealed that 313 biological processes were identified. The molecular docking result showed that the binding energies were all lower than -5 kcal/mol, indicating strong binding activity to the protein by the 6 core target gene. The therapeutic effect of ursolic acid on OP may be achieved by regulating TP53, JUN, IL6, VEGFA, CASP3, and MAPK8 genes, respectively. It exhibits possible biological function in the treatment of OP mainly involve positive regulation of apoptotic process, response to drug, incytoplasm, cytosol, protein binding, identical protein binding. Its mechanism may related to multiple therapeutic targets and signaling pathways such as cancer pathway, hepatitis B, and TNF signaling pathway.

Differentially expressed genes and miRNAs in female osteoporosis patients

Osteoporosis is characterized by lowing bone mineral density. This study aimed to investigate the genes, miRNAs, pathways, and miRNA-gene interaction pairs involved in the pathogenesis of female osteoporosis. The differentially expressed genes (DEGs, GSE62402), differentially expressed miRNAs (DEmiRNAs, GSE63446), and differentially methylated genes (GSE62588) between females with low- and high-hip bone mineral density were identified. Genes common to DEGs, differentially methylated genes, DEmiRNAs' targets, and osteoporosis-related genes were retained and used to construct the miRNA-mRNA-pathway regulatory network. The expression of hub nodes was validated in microarray datasets (genes in GSE56116 and miRNAs in GSE93883). Thirty-four DEmiRNAs and 179 DEGs with opposite expression-methylation profiles were identified. Functional enrichment analysis showed that DEGs were associated with pathways including "hsa00380:Tryptophan metabolism," "hsa04670:Leukocyte transendothelial migration," "hsa04630:Jak-STAT signaling pathway," and "hsa04062:Chemokine signaling pathway." The miRNA-mRNA-pathway network included 10 DEGs, 9 miRNAs, and 4 osteoporosis-related pathways. The miRNA-gene-pathway axes including hsa-miR-27b-5p/3p-IFNAR1-hsa04630, hsa-miR-30a-5p/3p-IFNAR1-hsa04630, hsa-miR-30a-5p/3p-ALDH2-hsa00380, and hsa-miR-194-5p/3p-NCF2-hsa04670 were included in the network. Microarray validation showed that IFNAR1, NCF2, and ALDH2 were upregulated, and hsa-miR-30a-3p/5p, hsa-miR-194-3p/5p, hsa-miR-27b-3p/5p, and hsa-miR-34a-3p were downregulated in osteoporotic samples compared with control. Axes including hsa-miR-27b/30a-IFNAR1-Jak-STAT signaling pathway, hsa-miR-30a-ALDH2-Tryptophan metabolism, and hsa-miR-194-NCF2-Leukocyte transendothelial migration were involved in osteoporosis pathogenesis.

Elevated lncRNA MIAT in peripheral blood mononuclear cells contributes to post-menopausal osteoporosis

Inflammatory cytokines contribute to the development of osteoporosis with sophisticated mechanisms. Globally alteration of long-chain non-coding RNA was screened in osteoporosis, while we still know little about their functional role in the inflammatory cytokine secretion. In this study, we collected the peripheral blood mononuclear cells (PBMCs) from post-menopausal osteoporosis patients to measure lncRNA MIAT (lncMIAT) expression levels, and explored the molecular mechanism of lncMIAT induced inflammatory cytokine secretion. We identified increased lncMIAT expression in the PBMCs of post-menopausal osteoporosis patients, which was an important predictive biomarker for the diagnosis. LncMIAT expression in PBMCs was positively correlated with the inflammatory cytokine secretion. Mechanism study indicated that lncMIAT increased the expression levels of p38MAPK by crosstalk with miR-216a in PBMCs. The lncMIAT/miR-216a/p38MAPK signaling contributed predominantly to the increased inflammatory cytokine secretion in the PBMCs from postmenopausal osteoporosis. In conclusion, we identified that increased lncMIAT in PBMCs induced inflammatory cytokine secretion, which contributed to the development of post-menopausal osteoporosis. lncMIAT/miR-216a axis was critical for the regulation of AMPK/p38MAPK signaling, which may be a promising therapeutic target for osteoporosis treatment by inflammatory cytokine inhibition.

Systems pharmacology dissection of action mechanisms for herbs in osteoporosis treatment

Objective

Osteoporosis has become the biggest cause of non-fatal health issue. Currently, the limitations of traditional anti-osteoporosis drugs such as long-term ill-effects and drug resistance, have raised concerns toward complementary and alternative therapies, particularly herbal medicines and their natural active compounds. Thus, this study aimed to provide an integrative analysis of active chemicals, drug targets and interacting pathways of the herbs for osteoporosis treatment.

Methods

Here, we introduced a systematic pharmacology model, combining the absorption, distribution, metabolism, and excretion (ADME) screening model, drug targeting and network pharmacology, to probe into the therapeutic mechanisms of herbs in osteoporosis.

Results

We obtained 86 natural compounds with favorable pharmacokinetic profiles and their 58 targets from seven osteoporosis-related herbs. Network analysis revealed that they probably synergistically work through multiple mechanisms, such as suppressing inflammatory response, maintaining bone metabolism or improving organism immunity, to benefit patients with osteoporosis. Furthermore, experimental results showed that all the five compounds (calycosin, asperosaponin VI, hederagenin, betulinic acid and luteolin) enhanced osteoblast proliferation and differentiation in vitro, which corroborated the validity of this system pharmacology approach. Notably, gentisin and aureusidin among the identified compounds were first predicted to be associated with osteoporosis.

Conclusion

Herbs and their natural compounds, being characterized as the classical combination therapies, might be engaged in multiple mechanisms to coordinately improve the osteoporosis symptoms. This work may contribute to offer novel strategies and clues for the therapy and drug discovery of osteoporosis and other complex diseases.

The Pathophysiology of Osteoporosis after Spinal Cord Injury

Spinal cord injury (SCI) affects approximately 300,000 people in the United States. Most individuals who sustain severe SCI also develop subsequent osteoporosis. However, beyond immobilization-related lack of long bone loading, multiple mechanisms of SCI-related bone density loss are incompletely understood. Recent findings suggest neuronal impairment and disability may lead to an upregulation of receptor activator of nuclear factor-κB ligand (RANKL), which promotes bone resorption. Disruption of Wnt signaling and dysregulation of RANKL may also contribute to the pathogenesis of SCI-related osteoporosis. Estrogenic effects may protect bones from resorption by decreasing the upregulation of RANKL. This review will discuss the current proposed physiological and cellular mechanisms explaining osteoporosis associated with SCI. In addition, we will discuss emerging pharmacological and physiological treatment strategies, including the promising effects of estrogen on cellular protection.

Effects of CD4+ T lymphocytes from ovariectomized mice on bone marrow mesenchymal stem cell proliferation and osteogenic differentiation

The present study was designed to investigate the effects of T cells on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs). BMMSCs were co-cultured with CD4⁺ T cells that had been pretreated with anti-TNF-α or controls and were derived from ovariectomized (OVX) mice or sham control mice. MTT was used to assess the proliferative ability of BMMSCs and flow cytometry was used to analyze the BMMSC cell cycle. Following the induction of osteogenic differentiation in BMMSCs, calcium nodules were observed using alizarin red staining and alkaline phosphatase (ALP) staining. The expression levels of the osteogenesis-associated genes, runt related transcription factor 2 (Runx2) and osteocalcin (OCN) in BMMSCs were quantified using reverse transcription-quantitative PCR and western blotting. Osteogenesis-related signaling pathways, including ERK, JNK and p38 MAPK were also examined by western blotting. BMMSCs co-cultured with CD4⁺ T cells from OVX mice exhibited reduced proliferative ability compared with sham mice and the cell cycle was arrested at the G2/M phase. Additionally, BMMSCs co-cultured with CD4⁺ T cells from OVX mice presented with reduced levels of osteogenic differentiation and lower ALP activity, less calcium deposition and reduced expression of Runx2 and OCN compared with sham mice. The reduced levels of proliferation and osteogenic differentiation of BMMSCs induced by CD4⁺ T cells were not seen when the T cells were had been pretreated with anti-TNF-α. The results indicated that CD4⁺ T cells from OVX mice inhibited the proliferation and osteogenic differentiation of BMMSCs by producing high levels of TNF-α and may provide a novel insight into the dysfunction of BMMSCs caused by estrogen deficiency.

Osteoimmunology: The Regulatory Roles of T Lymphocytes in Osteoporosis

Immune imbalance caused bone loss. Osteoimmunology is emerging as a new interdisciplinary field to explore the shared molecules and interactions between the skeletal and immune systems. In particular, T lymphocytes (T cells) play pivotal roles in the regulation of bone health. However, the roles and mechanisms of T cells in the treatment of osteoporosis are not fully understood. The present review aims to summarize the essential regulatory roles of T cells in the pathophysiology of various cases of osteoporosis and the development of T cell therapy for osteoporosis from osteoimmunology perspective. As T cell-mediated immunomodulation inhibition reduced bone loss, there is an increasing interest in T cell therapy in an attempt to treat osteoporosis. In summary, the T cell therapy may be further pursued as an immunomodulatory strategy for the treatment of osteoporosis, which can provide a novel perspective for drug development in the future.

Corilagin suppresses RANKL-induced osteoclastogenesis and inhibits oestrogen deficiency-induced bone loss via the NF-κB and PI3K/AKT signalling pathways

Over‐activated osteoclastogenesis, which is initiated by inflammation, has been implicated in osteoporosis. Corilagin, a natural compound extracted from various medicinal herbaceous plants, such as Cinnamomum cassia, has antioxidant and anti‐inflammatory activities. We found that Corilagin suppressed osteoclast differentiation in a dose‐dependent manner, significantly decreased osteoclast‐related gene expression and impaired bone resorption by osteoclasts. Moreover, phosphorylation of members of the nuclear factor‐kappaB (NF‐κB) and PI3K/AKT signalling pathways was reduced by Corilagin. In a murine model of osteoporosis, Corilagin inhibited osteoclast functions in vivo and restored oestrogen deficiency‐induced bone loss. In conclusion, our findings suggested that Corilagin inhibited osteoclastogenesis by down‐regulating the NF‐κB and PI3K/AKT signalling pathways, thus showing its potential possibility for the treatment of osteoporosis.

Integrated network pharmacology and zebrafish model to investigate dual-effects components of Cistanche tubulosa for treating both Osteoporosis and Alzheimer's Disease

ETHNOPHARMACOLOGICAL RELEVANCE

Osteoporosis (OP) and Alzheimer's disease (AD) are common geriatric concurrent diseases, and many studies indicate the connection of their pathogenesis. Cistanche tubulosa (Schenk) Wight (CT) is a widely used traditional Chinese medicine and has been extensively applied to treat OP and AD, respectively. However, the active ingredients for both concurrent diseases simultaneously and underlying mechanisms are limited.

AIM OF STUDY

This work aimed at establishing an effective and reliable network screening method to find dual-effects compounds in CT that can protect AD and OP concurrently. And it will provide new perspectives of the link between OP and AD on molecular mechanisms.

MATERIAL AND METHODS

The dual-effects of CT were systematically analyzed with integrating multiple databases and extensive analysis at a network pharmacology level. Classified drug-target interaction network was constructed to reveal differences in effects between different types of compounds. To prove the effectiveness of this network, some compounds were selected to verify in Pre-induced OP model and AlCl₃-induced AD model of zebrafish according to the topological parameters.

RESULTS

22 dual-effects active ingredients in CT were initially screened out via network pharmacology with a closely connection with 81 OP and AD-related targets. Classified network analysis found the better bioactivities of phenylethanoid glycosides and flavonoids. The dual-effects of four selected compounds demonstrated that the network is reasonable and effective, suggesting the dual-effects of the remaining 18 compounds. Moreover, we identified 9 putative targets and two pathways that were significantly related to OP and AD.

CONCLUSIONS

We successfully identified 22 dual-effects active components in CT. This systematic screening strategy provided a new protocol to objectively discover multi-effects compounds of traditional Chinese medicine, and even a macroscopic perspective that will improve our understanding of the link between OP and AD on molecular mechanisms.

The relationship between bone marrow adipose tissue and bone metabolism in postmenopausal osteoporosis

Postmenopausal osteoporosis (PMOP) is a prevalent skeletal disorder associated with menopause-related estrogen withdrawal. PMOP is characterized by low bone mass, deterioration of the skeletal microarchitecture, and subsequent increased susceptibility to fragility fractures, thus contributing to disability and mortality. Accumulating evidence indicates that abnormal expansion of marrow adipose tissue (MAT) plays a crucial role in the onset and progression of PMOP, in part because both bone marrow adipocytes and osteoblasts share a common ancestor lineage. The cohabitation of MAT adipocytes, mesenchymal stromal cells, hematopoietic cells, osteoblasts and osteoclasts in the bone marrow creates a microenvironment that permits adipocytes to act directly on other cell types in the marrow. Furthermore, MAT, which is recognized as an endocrine organ, regulates bone remodeling through the secretion of adipokines and cytokines. Although an enhanced MAT volume is linked to low bone mass and fractures in PMOP, the detailed interactions between MAT and bone metabolism remain largely unknown. In this review, we examine the possible mechanisms of MAT expansion under estrogen withdrawal and further summarize emerging findings regarding the pathological roles of MAT in bone remodeling. We also discuss the current therapies targeting MAT in osteoporosis. A comprehensive understanding of the relationship between MAT expansion and bone metabolism in estrogen deficiency conditions will provide new insights into potential therapeutic targets for PMOP.

Roles of Mitogen-Activated Protein Kinases in Osteoclast Biology

Bone undergoes continuous remodeling, which is homeostatically regulated by concerted communication between bone-forming osteoblasts and bone-degrading osteoclasts. Multinucleated giant osteoclasts are the only specialized cells that degrade or resorb the organic and inorganic bone components. They secrete proteases (e.g., cathepsin K) that degrade the organic collagenous matrix and establish localized acidosis at the bone-resorbing site through proton-pumping to facilitate the dissolution of inorganic mineral. Osteoporosis, the most common bone disease, is caused by excessive bone resorption, highlighting the crucial role of osteoclasts in intact bone remodeling. Signaling mediated by mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, has been recognized to be critical for normal osteoclast differentiation and activation. Various exogenous (e.g., toll-like receptor agonists) and endogenous (e.g., growth factors and inflammatory cytokines) stimuli contribute to determining whether MAPKs positively or negatively regulate osteoclast adhesion, migration, fusion and survival, and osteoclastic bone resorption. In this review, we delineate the unique roles of MAPKs in osteoclast metabolism and provide an overview of the upstream regulators that activate or inhibit MAPKs and their downstream targets. Furthermore, we discuss the current knowledge about the differential kinetics of ERK, JNK, and p38, and the crosstalk between MAPKs in osteoclast metabolism.

Monotropein attenuates ovariectomy and LPS-induced bone loss in mice and decreases inflammatory impairment on osteoblast through blocking activation of NF-κB pathway

Estrogen deficiency and inflammation are known to play important roles in bone metabolism and occurrence of osteoporosis. Monotropein as an iridoid glycoside is reported to decrease estrogen deficiency-induced bone loss and inhibit inflammatory response in LPS-induced RAW 264.7 macrophages. However, the effect of monotropein on bone loss in chronic inflammatory conditions remains unclear. It was found in the present study that monotropein significantly inhibited bone mass reduction and improved bone micro-architectures by enhancing bone formation and blocking increased secretion of inflammatory cytokines in osteoporotic mice induced by combined ovariectomy and LPS. Our in vitro experiment further demonstrated that monotropein was able to increase the proliferation and activity of alkaline phosphatase (ALP), bone matrix mineralization and the expression of bone matrix protein osteopontin (OPN) in osteoblastic MC3T3-E1 cells injured by LPS. In addition, monotropein significantly decreased the production of IL-6 and IL-1β, inhibited the nuclear translocation of p65 and NF-κB P50, and down-regulated the phosphorylation of NF-κB p65 and IKK, indicating that monotropein could attenuate inflammatory impairment to MC3T3-E1 cells by suppressing the activation of NF-κB pathway. All these results suggest that monotropein may prove to be a promising candidate for the prevention and treatment of inflammatory bone loss.

Effects of interleukin-7/interleukin-7 receptor on RANKL-mediated osteoclast differentiation and ovariectomy-induced bone loss by regulating c-Fos/c-Jun pathway

To explore the effects of IL-7/IL-7R on the RANKL-mediated osteoclast differentiation in vitro and OVX-induced bone loss in vivo. BMMs and RAW264.7 were transfected with IL-7, IL-7R siRNA, c-Fos siRNA, and c-jun siRNA and later stimulated by RANKL. TRAP and toluidine blue staining were used to observe osteoclast formation and bone resorption, respectively. HE and TRAP staining were used to detect trabecular bone microstructure and osteoclasts of mice, respectively. qRT-PCR and Western blot analysis were used to examine expression. IL-7 unregulated the expression of CTSK, NFATc1, MMP9, and the phosphorylation of p38 and Akt by activating the c-Fos/c-Jun pathway, which increased osteoclast numbers and bone resorption in RANKL-stimulated macrophages. While IL-7R siRNA and c-Fos siRNA decreased the expression, as well as and the phosphorylation of p38 and Akt.IL-7 decreased the BMD and OPG expression in OVX-induced mice and increased the TRAP positive cells, the mRNA expression of c-fos, c-jun, and RANKL, which was contradictory to IL-7R siRNA, and c-Fos siRNA. Furthermore, IL-7R siRNA and c-Fos siRNA caused thicker trabeculae, increased trabecular number, and decreased osteolysis in OVX mice. IL-7/IL-7R can promote RANKL-mediated osteoclast formation and bone resorption by activating the c-Fos/c-Jun pathway, as well as inducing bone loss in OVX mice.

Achyranthes bidentata polysaccharide suppresses osteoclastogenesis and bone resorption via inhibiting RANKL signaling

Osteoclasts are highly differentiated multinucleated giant cells that play fundamental roles in bone resorption and in the pathogenesis of osteolytic conditions, such as osteoporosis and cancer-induced bone loss. Achyranthes bidentata polysaccharide (ABP) is a hydrophilic compound with anti-oxidation and anti-aging characteristics. The impact of ABP on RANKL-induced osteoclast formation and bone resorption has not been assessed, hence, in this study we investigated the effect of ABP on osteoclast formation and resorption in murine bone marrow derived osteoclasts. We found that ABP was able to suppress RANKL-induced osteoclast differentiation and bone resorption activity at concentrations above 6.5 µM, while demonstrating no cytotoxicity at concentrations up to 10 µM. The actions of ABP were mediated through inhibition of RANKL-induced c-Fos and NFATc1 gene and protein expression. Furthermore, we found that ABP suppressed NFATc1 transcriptional activity, and the phosphorylation of MAPK pathways induced by RANKL. Collectively, ABP attenuates RANKL-mediated osteoclast activity and signaling, and might serve as a potential therapeutic candidate for preventing bone loss related diseases.

Re-evaluating osteoporosis and fracture risk in Crohn's disease patients in the era of TNF-alpha inhibitors

INTRODUCTION

Patients with Crohn's disease (CD) are at increased risk for osteoporosis and fractures as compared to the general population. Recently, various cytokines including tumor necrosis factor (TNF)-alpha are found to play a major role in bone health. In this study, we aimed to gain a better understanding of the risk factors for osteoporosis and vitamin D deficiency in the era of TNF-alpha inhibitors.

METHODS

We conducted a retrospective review of 464 consecutive patients with CD in our GI clinic between 2008 and 2015. Statistical analysis was performed using the student t-test and chi-square test.

RESULTS

CD patients treated with TNF-alpha inhibitors (TNF) and those who are anti-TNF naïve (NB) had similar rates of vitamin D deficiency, insufficiency and normal vitamin D-25-OH levels. Similarly, rates of osteoporosis (16% vs 18%), osteopenia (53% vs 57%) and normal bone density (31% vs 25%) were comparable between the TNF and NB groups respectively. However, Z-scores at the spine (-0.47 vs -0.05) were significantly lower in the TNF group (p = .03). Interestingly, rates of osteoporosis in the NB group were drastically different before and after age 60 (3.6% vs 30%) with no major difference in the TNF group (15% vs 18%). Bone density was positively correlated with BMI (Pearson's R = 0.39) and negatively correlated with age and smoking status (R= -0.25).

CONCLUSIONS

TNF group patients were diagnosed with osteoporosis from an earlier age compared to NB group but with a smaller increase in osteoporosis after menopause. Further prospective studies are necessary to further determine the role of anti-TNF medications in osteoporosis.