A Matrine Derivative M54 Suppresses Osteoclastogenesis and Prevents Ovariectomy-Induced Bone Loss by Targeting Ribosomal Protein S5

Matrine alleviates hypoxia-induced inflammation and pulmonary vascular remodelling via RPS5/NF-κB signalling pathway

Hypoxia-induced vasoconstriction and vascular remodelling are the main pathological features of hypoxic pulmonary arterial hypertension (HPAH), and inflammation is participated in the occurrence of pulmonary vascular remodelling (PVR). Matrine is an alkaloid with the effects of anti-inflammation, antifibrosis and antitumour. But, few studies have explored the role of matrine in regulating PVR, and the related mechanisms are still unknown. In this study, we found that hypoxia-induced pulmonary artery smooth muscle cells (PASMCs) proliferation and inhibited its apoptosis, reduced the expression of ribosomal protein s5 and activated the nuclear factor kappa-B (NF-κB) signalling. Matrine, sildenafil and NF-κB inhibitor Bay 11-7082 could reverse these changes and impel the cell cycle in phase S retardation, and reduced the expression of p50, p65, proliferating cell nuclear antigen (PCNA), Bcl-2. In addition, matrine could lower right ventricular systolic pressure and mean pulmonary artery pressure of rats, α-smooth muscle actin and PCNA expression in pulmonary artery media, the levels of tumor necrosis factor-α and interleuki-1β, thus improved hypoxia-induced PVR. This study indicated that matrine could alleviate inflammation and improve PVR through reversing the imbalance of proliferation and apoptosis of PASMCs, thus it had a therapeutic effect on HPAH.

Research Progress of Natural Matrine Compounds and Synthetic Matrine Derivatives

Matrine is a quinoline alkaloid extracted and separated from the dried root, fruit, and other parts of the plant Sophora flavescens using an organic solvent. Matrine exhibits a variety of biological activities and is widely used in pharmacy, agronomy, and other fields. Due to its low bioavailability, poor chemical stability, and toxicity to the central nervous system, a large number of researchers have searched for matrine derivatives with higher biological activity and safety by modifying its structure. In this review article, the research progress of matrine derivatives obtained using two methods (extraction from Sophora flavescens and structural modifications) from 2018 to 2022 in terms of pharmacological activity, mechanism of action, and structure-activity relationship are presented. The modification of matrine over the past five years has been mainly on the D-ring. Many new matrine alkaloids have been extracted from natural products, some of which have good pharmacological activity, which broadens the strategy for matrine structural modification in the future.

Matrine Exerts Pharmacological Effects Through Multiple Signaling Pathways: A Comprehensive Review

As The main effective monomer of the traditional Chinese medicine Sophora flavescens Ait, matrine has a broad scope of pharmacological activities such as anti-tumor, anti-inflammatory, analgesic, anti-fibrotic, anti-viral, anti-arrhythmia, and improving immune function. These actions explain its therapeutic effects in various types of tumors, cardiopathy, encephalomyelitis, allergic asthma, rheumatoid arthritis (RA), osteoporosis, and central nervous system (CNS) inflammation. Evidence has shown that the mechanism responsible for the pharmacological actions of matrine may be via the activation or inhibition of certain key molecules in several cellular signaling pathways including the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), transforming growth factor-β/mothers against decapentaplegic homolog (TGF-β/Smad), nuclear factor kappa B (NF-κB), Wnt (wingless/ integration 1)/β-catenin, mitogen-activated protein kinases (MAPKs), and Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways. This review comprehensively summarizes recent studies on the pharmacological mechanisms of matrine to provide a theoretical basis for molecular targeted therapies and further development and utilization of matrine.

The Advances on Bioactivities, Mechanisms of Action, and Structural Optimizations of Matrine and Its Derivatives

Matrine, a tetracyclo-quinolizidine alkaloid, is isolated from the industrial crop plant Sophora flavescens. Due to a wide range of pharmacological and agricultural properties, the research on the phytochemistry, pharmacology, toxicology and mechanisms of action of matrine and its derivatives has received much attention. On the other hand, to improve their biological activities, the study on structural optimizations and structure-activity relationships of matrine and its derivatives has also attached more and more importance. In this review article, the update advances on bioactivities, mechanisms of action, structural modifications and structure-activity relationships of matrine and its derivatives from 2017 to 2020 are presented. We hope that this review will provide a reference for the development and application of matrine and its derivatives as drugs or pesticides in the future.

Effects and mechanisms of natural plant active compounds for the treatment of osteoclast-mediated bone destructive diseases

Bone-destructive diseases, caused by overdifferentiation of osteoclasts, reduce bone mass and quality, and disrupt bone microstructure, thereby causes osteoporosis, Paget's disease, osteolytic bone metastases, and rheumatoid arthritis. Osteoclasts, the only multinucleated cells with bone resorption function, are derived from haematopoietic progenitors of the monocyte/macrophage lineage. The regulation of osteoclast differentiation is considered an effective target for the treatment of bone-destructive diseases. Natural plant-derived products have received increasing attention in recent years due to their good safety profile, the preference of natural compounds over synthetic drugs, and their potential therapeutic and preventive activity against osteoclast-mediated bone-destructive diseases. In this study, we reviewed the research progress of the potential antiosteoclast active compounds extracted from medicinal plants and their molecular mechanisms. Active compounds from natural plants that inhibit osteoclast differentiation and functions include flavonoids, terpenoids, quinones, glucosides, polyphenols, alkaloids, coumarins, lignans, and limonoids. They inhibit bone destruction by downregulating the expression of osteoclast-specific marker genes (CTSK, MMP-9, TRAP, OSCAR, DC-STAMP, V-ATPase d2, and integrin av3) and transcription factors (c-Fos, NFATc1, and c-Src), prevent the effects of local factors (ROS, LPS, and NO), and suppress the activation of various signalling pathways (MAPK, NF-κB, Akt, and Ca²⁺). Therefore, osteoclast-targeting natural products are of great value in the prevention and treatment of bone destructive diseases.

Therapeutic Effect of Matrine on Collagen-Induced Arthritis Rats and Its Regulatory Effect on RANKL and OPG Expression

Objective

To investigate the effect of matrine on rats with collagen-induced arthritis (CIA) and its regulatory effect on receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) expression.

Methods

Wistar rats (n = 6) and CIA rats (n = 30) were randomly divided into six groups: healthy, CIA control, low/medium/high matrine (25, 50, or 100 mg/kg, once per day for six weeks), and methotrexate (MTX) (2 mg/kg, once per week for six weeks). The degree of joint damage was evaluated by X-ray and HE staining. Bone marrow suppression was assessed by routine blood analysis. In addition, the levels of serum RANKL and OPG in the rats were measured by ELISA.

Results

The level of joint swelling and degree of joint damage assessed by ankle swelling measurements, AI score, X-ray, and HE staining were alleviated in the CIA rats treated with MTX or different doses of matrine. Furthermore, no obvious inhibitory effect was observed on the bone marrow of the CIA rats, regardless of the dose of matrine or treatment with 2 mg/kg MTX (P > 0.05). The levels of OPG in serum and the ratio of OPG/RANKL were higher, and RANKL expression was lower in the low/medium/high matrine group compared with that of the CIA control group. The serum levels of OPG and OPG/RANKL ratio increased with the matrine dose, while the opposite was observed for RANKL expression.

Conclusion

Matrine treatment was associated with a lower degree of bone destruction, increased OPG expression and OPG/RANKL ratio, and decreased RANKL expression in CIA rats. Thus, matrine may represent a novel drug candidate for the treatment of RA.

Identification of key genes and pathways involved in abdominal aortic aneurysm initiation and progression

OBJECTIVE

The study aimed to assess the gene expression profile of biopsies obtained from the neck of human abdominal aortic aneurysm (AAA) and the main site of AAA dilatation and to investigate the molecular mechanism underlying the development of AAA.

METHODS

The microarray profile of GSE47472 and GSE57691 were obtained from the Gene Expression Omnibus (GEO) database. The GSE47472 was a microarray dataset of tissues from the aortic neck of AAA patients versus normal controls. The GSE57691 was a microarray dataset including the tissues from main site of AAA dilatation versus normal controls. Differentially expressed genes (DEGs) were chosen using the R package and annotated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomics (KEGG). The hub genes were identified in the protein-protein interaction (PPI) network.

RESULTS

342 upregulated DEGs and 949 downregulated DEGs were obtained from GSE47472. The upregulated DEGs were mainly enriched in biological regulation (ontology: BP), the membrane (ontology: CC), and protein binding (ontology: MF), and the downregulated genes were mainly enriched in biological regulation (ontology: BP), the membrane (ontology: CC), and protein blinding (ontology: MF). In the KEGG enrichment analysis, the DEGs mainly involved glycosaminoglycan degradation, vasopressin-regulated water reabsorption, and pyruvate metabolism. The hub genes in GSE47472 mainly include VAMP8, PTPRC, DYNLL1, RPL38, RPS4X, HNRNPA1, PRMT1, TGOLN2, PA2G4, and CUL2. From GSE57691, 248 upregulated DEGs and 1120 downregulated DEGs were selected. The upregulated DEGs of GSE57691 were mainly enriched in biological regulation (ontology: BP), the membrane (ontology: CC), and protein binding (ontology: MF), and the downregulated genes were mainly enriched in metabolic process (ontology: BP), the membrane (ontology: CC), and protein blinding (ontology: MF). In the KEGG enrichment analysis, the DEGs mainly involved the mitochondrial respiratory, respiratory chain complex, and respiratory chain. RPS15A, RPS5, RPL23, RPL27A, RPS24, RPL35A, RPS4X, RPL7, RPS25, and RPL21 were identified as the hub genes.

CONCLUSION

At the early stage of AAA, the current study indicated the importance of glycosaminoglycan degradation and anaerobic metabolism. We also identified several hub genes closely related to AAA (VAMP8, PTPRC, DYNLL1, etc.). At the progression of the AAA, the dysfunctional mitochondria played a critical role in AAA formation and the RPS15A, RPS5, RPL23, etc., were identified as the hub genes.

RANKL from bone marrow adipose lineage cells promotes osteoclast formation and bone loss

Receptor activator of NF-κB ligand (RANKL) is essential for osteoclast formation and bone remodeling. Nevertheless, the cellular source of RANKL for osteoclastogenesis has not been fully uncovered. Different from peripheral adipose tissue, bone marrow (BM) adipose lineage cells originate from bone marrow mesenchymal stromal cells (BMSCs). Here, we demonstrate that adiponectin promoter-driven Cre expression (Adipoq^Cre ) can target bone marrow adipose lineage cells. We cross the Adipoq^Cre mice with rankl^fl/fl mice to conditionally delete RANKL from BM adipose lineage cells. Conditional deletion of RANKL increases cancellous bone mass of long bones in mice by reducing the formation of trabecular osteoclasts and inhibiting bone resorption but does not affect cortical bone thickness or resorption of calcified cartilage. Adipoq^Cre ; rankl^fl/fl mice exhibit resistance to estrogen deficiency and rosiglitazone (ROS)-induced trabecular bone loss but show bone loss induced by unloading. BM adipose lineage cells therefore represent an essential source of RANKL for the formation of trabecula osteoclasts and resorption of cancellous bone during remodeling under physiological and pathological conditions. Targeting bone marrow adiposity is a promising way of preventing pathological bone loss.

Rotundic acid reduces LPS-induced acute lung injury in vitro and in vivo through regulating TLR4 dimer

Acute lung injury (ALI) is a serious clinical disease. Rotundic acid (RA), a natural ingredient isolated from Ilex rotunda Thunb, exhibits multiple pharmacological activities. However, RA's therapeutic effect and mechanism on ALI remain to be elucidated. The present study aimed to further clarify its regulating effects on inflammation in vitro and in vivo. Our results indicated that RA significantly inhibited the overproduction of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). RA decreased ROS production and calcium influx. In addition, RA inhibited the activation of PI3K, MAPK, and NF-κB pathways and enhanced the activity of nuclear factor E2-related factor 2 (Nrf2) signaling. The cellular thermal shift assay and docking results indicated that RA bind to TLR4 to block TLR4 dimerization. Furthermore, RA pretreatment effectively inhibited ear edema induced by xylene and LPS-induced endotoxin death and had a protective effect on LPS-induced ALI. Our findings collectively indicated that RA has anti-inflammatory effects, which may serve as a potential therapeutic option for pulmonary inflammation.

Dencichine prevents ovariectomy-induced bone loss and inhibits osteoclastogenesis by inhibiting RANKL-associated NF-κB and MAPK signaling pathways

AIMS

To investigate the effect of dencichine on osteoclastogenesis in vivo and in vitro.

METHODS

RANKL-induced osteoclastogenesis were treated with different concentrations of dencichine. Pit forming assays were applied to evaluate the degree of bone resorption. Osteoclastogenic markers were detected by real-time quantitative PCR (RT-qPCR) and Western blot. Micro CT was conducted to investigate the effects of dencichine on osteoclastogenesis in ovariectomized (OVX) mice.

RESULTS

Dencichine suppressed osteoclastogenesis through the inhibition of phosphorylation of p65, p50 (NF-κB pathway), p38, ERK and JNK (MAPKs pathway) in vitro. Furthermore, dencichine inhibited the function of osteoclasts in a dose-dependent manner. In addition, the expression levels of the nuclear factor of activated T cells 1 (NFATc1) and osteoclastogenesis markers were decreased by dencichine, including MMP-9, Cathepsin K (CTSK), Tartrate-Resistant Acid Phosphatase (TRAP), C-FOS, dendritic cell specific transmembrane protein (DC-STAMP). In vivo data proved that dencichine alleviated ovariectomy-induced bone loss and osteoclastogenesis in mice.

CONCLUSION

Our results demonstrate that dencichine alleviates OVX-induced bone loss in mice and inhibits RANKL-mediated osteoclastogenesis via inhibition of NF-κB and MAPK pathways in vitro, suggesting that dencichine might serve as a promising candidate for treatment of bone loss diseases, including PMOP and rheumatoid arthritis.

Matrine attenuates pathological cardiac fibrosis via RPS5/p38 in mice

Pathological cardiac fibrosis is a common feature in multiple cardiovascular diseases that contributes to the occurrence of heart failure and life-threatening arrhythmias. Our previous study demonstrated that matrine could attenuate doxorubicin-induced oxidative stress and cardiomyocyte apoptosis. In this study, we investigated the effect of matrine on cardiac fibrosis. Mice received aortic banding (AB) operation or continuous injection of isoprenaline (ISO) to generate pathological cardiac fibrosis and then were exposed to matrine lavage (200 mg·kg-1·d-1) or an equal volume of vehicle as the control. We found that matrine lavage significantly attenuated AB or ISO-induced fibrotic remodeling and cardiac dysfunction. We also showed that matrine (200 μmol/L) significantly inhibited the proliferation, migration, collagen production, and phenotypic transdifferentiation of cardiac fibroblasts. Mechanistically, matrine suppressed p38 activation in vivo and in vitro, and overexpression of constitutively active p38 completely abolished the protective effects of matrine. We also demonstrated that ribosomal protein S5 (RPS5) upregulation was responsible for matrine-mediated inhibition on p38 and fibrogenesis. More importantly, matrine was capable of ameliorating preexisting cardiac fibrosis in mice. In conclusion, matrine treatment attenuates cardiac fibrosis by regulating RPS5/p38 signaling in mice, and it might be a promising therapeutic agent for treating pathological cardiac fibrosis.

Rosavin suppresses osteoclastogenesis in vivo and in vitro by blocking the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways

Background

Bone homeostasis is mediated by osteoblast-related bone formation and osteoclast-related resorption. The imbalance of bone homeostasis due to excessive osteoclastogenesis or reduced osteogenesis can result in various disorders, such as postmenopausal osteoporosis (PMOP). The receptor activator of nuclear factor-κB ligand (RANKL)-induced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) pathways are essential in osteoclastogenesis. In this study, we aimed to investigate the effects of rosavin, an alkylbenzene diglycoside compound from the traditional Chinese medicine Rhodiola Rosea L, on RANKL-induced osteoclastogenesis in vitro and in vivo.

Methods

The effects of rosavin on osteoclastogenesis were assessed by TRAP staining of bone marrow monocyte cells (BMMCs) and RAW 264.7 cells. The effects of rosavin on osteogenesis were determined using alkaline phosphatase (ALP) and alizarin red staining, as well as real-time quantitative reverse transcription polymerase chain reaction. Actin ring formation and bone formation experiments were performed to evaluate osteoclast function. Western blotting was carried out to determine the expression of osteoclastogenesis-related genes, and the activation of the NF-κB and MAPK pathways was evaluated by performing western blotting and immunofluorescence staining. Ovariectomized mice were used to explore the effect of rosavin on bone loss.

Results

Rosavin could inhibit osteoclastogenesis, suppress the function of osteoclasts, and decrease the expression of osteoclast differentiation-related genes, including tartrate-resistant acid phosphatase (TRAP), cathepsin K, matrix metalloproteinase-9 (MMP-9), calcitonin receptor (CTR), TNF receptor-associated factor 6 (TRAF-6), receptor activator of nuclear factor-κB (RANK), and colony-stimulating factor-1 receptor (c-fms). Rosavin inhibited RANKL-induced phosphorylation of p65 and inhibitory subunit of NF-κB alpha (IκBα), and suppressed p65 nuclear translocation. Rosavin was also found to inhibit the phosphorylation of extracellular-signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). Furthermore, rosavin promoted osteogenesis in bone marrow mesenchymal stem cells (BMSCs). In vivo experiments showed that treatment with rosavin could alleviate ovariectomy-induced osteoporosis in mice.

Conclusions

Our results indicated that rosavin suppressed RANKL-induced osteoclastogenesis in vivo and in vitro by blocking the NF-κB and MAPK pathways. Rosavin treatment is a potential therapy for the clinical treatment of osteoclastogenesis-related disorders.

Hyaluronic acid-based hydrogels with tobacco mosaic virus containing cell adhesive peptide induce bone repair in normal and osteoporotic rats

Tobacco mosaic virus (TMV) has been studied as a multi-functional agent for bone tissue engineering. An osteo-inductive effect of wild-type TMV has been reported, as it can significantly enhance the bone differentiation potential of bone marrow stromal cells both on a two-dimensional substrate and in a three-dimensional (3D) hydrogel system. A TMV mutant (TMV-RGD1) was created which featured the adhesion peptide arginyl-glycyl-aspartic acid (RGD), the most common peptide motif responsible for cell adhesion to the extracellular matrix, on the surface of the virus particle to enhance the bio-functionality of the scaffold material. We hypothesised that the incorporation of either wild-type TMV or TMV-RGD1 in the 3D hydrogel scaffold would induce bone healing in critical size defects of the cranial segmental bone. We have previously tested the virus-functionalised scaffolds, in vitro, with a hyaluronic acid-based system as an in-situ hydrogel platform for 3D cell encapsulation, culture, and differentiation. The results of these experiments suggested the potential of the virus-functionalised hydrogel to promote in vitro stem cell differentiation. The hydrogel-forming system we employed was shown to be safe and biocompatible in vivo. Here, we further explored the physiological responses regarding bone regeneration of a calvarial defect in both normal and osteoporotic ovariectomized rat models. Our results, based on histological analysis in both animal models, suggested that both wild-type TMV and TMV-RGD1 functionalised hydrogels could accelerate bone regeneration, without systemic toxicity, evaluated by blood counts. New bone formation was intensified by the incorporation of the RGD-mutant viral particles. This finding increased the potential for use of the rod-shaped plant virus as a platform for the addition of powerful biofunctionality for tissue engineering applications. This study was approved by the Ethics Committee on Animal Use of the Zhenjiang Affiliated First People's Hospital affiliated to Jiangsu University.

Development of 3-mercaptopropyltrimethoxysilane (MPTS)-modified bone marrow mononuclear cell membrane chromatography for screening anti-osteoporosis components from Scutellariae Radix

Osteoporosis is a bone metabolic disease caused by the imbalance between osteoblasts and osteoclasts due to excess osteoclastogenesis, manifesting in the decrease of bone density and bone strength. Scutellariae Radix shows good anti-osteoporosis activity, but the effective component is still unclear. Cell membrane chromatography (CMC) is a biological affinity chromatography with membrane immobilized on a silica carrier as the stationary phase. It can realize a dynamical simulation of interactions between drugs and receptors on cell membrane, which is suitable for screening active compounds from complex systems. In this study, the components of Scutellariae Radix with potential anti-osteoporosis activity through inhibiting the differentiation from bone marrow mononuclear cells (BMMCs) to osteoclast were screened by a BMMC/CMC analytical system. Firstly, a new 3-mercaptopropyltrimethoxysilane (MPTS)-modified BMMC/CMC stationary phase was developed to realize covalent binding with cell membrane fractions. By investigating the retention time (t_R) of the positive drug, the life span of the MPTS-modified CMC columns was significantly improved from 3 to 12 days. Secondly, 6 components of Scutellariae Radix were screened to show affinity to membrane receptors on BMMCs by a two-dimensional BMMC/CMC–TOFMS analytical system. Among them, tectochrysin demonstrated the best anti-osteoporosis effect in vitro, which has never been reported. We found that tectochrysin could inhibit the differentiation of BMMCs into osteoclasts induced by receptor activator of nuclear factor-κΒ ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in a concentration-dependent manner in vitro. In vivo, it significantly reduced the loss of bone trabeculae in ovariectomized mice, and decreased the level of C-terminal cross-linking telopeptides of type 1 collagen (CTX-1), tartrate-resistant acid phosphatase 5b (TRAP-5b), interleukin 6 (IL-6) in serum. In conclusion, tectochrysin serves as a potential candidate in the treatment of osteoporosis. The proposed two-dimensional MPTS-modified BMMC/CMC-TOFMS analytical system shows the advantages of long-life span and fast recognition ability, which is very suitable for infrequent cell lines.

Matrine enhances osteogenic differentiation of bone marrow-derived mesenchymal stem cells and promotes bone regeneration in rapid maxillary expansion

OBJECTIVE

The aim of this study was to evaluate the influence of matrine on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) as well as on bone metabolism in a rat rapid maxillary expansion (RME) model.

METHODS

In in vitro experiments, rat BMSCs were adopted and cell proliferation of BMSCs was measured. Meanwhile, the osteogenic differentiation of BMSCs was detected by alkaline phosphatase (ALP) activity assay, Alizarin red S staining and gene expression. In vivo bone regeneration was analyzed in a rat RME model. Eighteen rats were divided into 3 groups: one group without any treatment, one group receiving only RME, and a group with RME and matrine treatment. After 2 weeks, new bone formation was detected by Micro-CT and histology. Immunohistochemical staining was used to evaluate ALP and BMP2 expression.

RESULTS

Overall, we found that matrine upregulated cell proliferation dose-dependently. Also, ALP activity and mineralized matrix generation were enhanced. Moreover, the osteoblast-related gene expression (ALP, bone sialoprotein and osteocalcin) by BMSCs was also promoted. Micro-CT revealed that matrine significantly promoted in vivo bone formation after 2 weeks. Concomitantly, histological examination of haematoxylin-eosin, safranin-O and toluidine blue staining confirmed these findings. In addition, the levels of ALP and BMP2 in the palatal suture tissues of rats with matrine treatment were the highest among three groups.

CONCLUSION

This work suggests that matrine regulates osteogenesis and enhances bone regeneration. Matrine treatment may be beneficial in improving the stability of maxillary expansion.

Neobavaisoflavone inhibits osteoclastogenesis through blocking RANKL signalling-mediated TRAF6 and c-Src recruitment and NF-κB, MAPK and Akt pathways

Psoralea corylifolia (P corylifolia) has been popularly applied in traditional Chinese medicine decoction for treating osteoporosis and promoting fracture healing since centuries ago. However, the bioactive natural components remain unknown. In this study, applying comprehensive two-dimensional cell membrane chromatographic/C18 column/time-of-flight mass spectrometry (2D CMC/C18 column/TOFMS) system, neobavaisoflavone (NBIF), for the first time, was identified for the bioaffinity with RAW 264.7 cells membranes from the extracts of P corylifolia. Here, we revealed that NBIF inhibited RANKL-mediated osteoclastogenesis in bone marrow monocytes (BMMCs) and RAW264.7 cells dose dependently at the early stage. Moreover, NBIF inhibited osteoclasts function demonstrated by actin ring formation assay and pit-formation assay. With regard to the underlying molecular mechanism, co-immunoprecipitation showed that both the interactions of RANK with TRAF6 and with c-Src were disrupted. In addition, NBIF inhibited the phosphorylation of P50, P65, IκB in NF-κB pathway, ERK, JNK, P38 in MAPKs pathway, AKT in Akt pathway, accompanied with a blockade of calcium oscillation and inactivation of nuclear translocation of nuclear factor of activated T cells cytoplasmic 1 (NFATc1). In vivo, NBIF inhibited osteoclastogenesis, promoted osteogenesis and ameliorated bone loss in ovariectomized mice. In summary, P corylifolia-derived NBIF inhibited RANKL-mediated osteoclastogenesis by suppressing the recruitment of TRAF6 and c-Src to RANK, inactivating NF-κB, MAPKs, and Akt signalling pathways and inhibiting calcium oscillation and NFATc1 translocation. NBIF might serve as a promising candidate for the treatment of osteoclast-associated osteopenic diseases.

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.

Betulinic Acid Protects From Bone Loss in Ovariectomized Mice and Suppresses RANKL-Associated Osteoclastogenesis by Inhibiting the MAPK and NFATc1 Pathways

Osteoclasts with elevated bone resorption are commonly present in postmenopausal osteoporosis, and other osteolytic pathologies. Therefore, suppressing osteoclast generation and function has been the main focus of osteoporosis treatment. Betulinic acid (BA) represents a triterpenoid mainly purified from the bark of Betulaceae. BA shows multiple biological activities, including antitumor and anti-HIV properties, but its effect on osteolytic conditions is unknown. Here, BA suppressed receptor activator of nuclear factor‐κB ligand (RANKL)‐associated osteoclastogenesis and bone resorptive function, as assessed by tartrate‐resistant acid phosphatase (TRAP) staining, fibrous actin ring generation, and hydroxyapatite resorption assays. Mechanistically, BA downregulated the expression of osteoclastic-specific genes. Western blot analysis revealed that BA significantly interrupted ERK, JNK and p38 MAPK activation as well as intracellular reactive oxygen species (ROS) production, thus altering c-Fos and NFATc1 activation. Corroborating the above findings in cell-based assays, BA prevented ovariectomy-associated bone loss in an animal model. In conclusion, these findings suggest that BA can inhibit osteoclast generation and function as well as the RANKL signaling pathway, and might be used for treating osteoclast-related osteoporosis.

Triptolide prevents bone loss via suppressing osteoclastogenesis through inhibiting PI3K-AKT-NFATc1 pathway

Bone loss (osteopenia) is a common complication in human solid tumour. In addition, after surgical treatment of gynaecological tumour, osteoporosis often occurs due to the withdrawal of oestrogen. The major characteristic of osteoporosis is the low bone mass with micro-architectural deteriorated bone tissue. And the main cause is the overactivation of osteoclastogenesis, which is one of the most important therapeutic targets. Inflammation could induce the interaction of RANKL/RANK, which is the promoter of osteoclastogenesis. Triptolide is derived from the traditional Chinese herb lei gong teng, presented multiple biological effects, including anti-cancer, anti-inflammation and immunosuppression. We hypothesized that triptolide could inhibits osteoclastogenesis by suppressing inflammation activation. In this study, we confirmed that triptolide could suppress RANKL-induced osteoclastogenesis in bone marrow mononuclear cells (BMMCs) and RAW264.7 cells and inhibited the osteoclast bone resorption functions. PI3K-AKT-NFATc1 pathway is one of the most important downstream pathways of RANKL-induced osteogenesis. The experiments in vitro indicated that triptolide suppresses the activation of PI3K-AKT-NFATc1 pathway and the target point located at the upstream of AKT because both NFATc1 overexpression and AKT phosphorylation could ameliorate the triptolide suppression effects. The expression of MDM2 was elevated, which demonstrated the MDM-p53-induced cell death might contribute to the osteoclastogenesis suppression. Ovariectomy-induced bone loss and inflammation activation were also found to be ameliorated in the experiments in vivo. In summary, the new effect of anti-cancer drug triptolide was demonstrated to be anti-osteoclastogenesis, and we demonstrated triptolide might be a promising therapy for bone loss caused by tumour.

Guaiacol suppresses osteoclastogenesis by blocking interactions of RANK with TRAF6 and C-Src and inhibiting NF-κB, MAPK and AKT pathways

Angelica sinensis (AS; Dang Gui), a traditional Chinese herb, has for centuries been used for the treatment of bone diseases, including osteoporosis and osteonecrosis. However, the effective ingredient and underlying mechanisms remain elusive. Here, we identified guaiacol as the active component of AS by two‐dimensional cell membrane chromatography/C18 column/time‐of‐flight mass spectrometry (2D CMC/C18 column/TOFMS). Guaiacol suppressed osteoclastogenesis and osteoclast function in bone marrow monocytes (BMMCs) and RAW264.7 cells in vitro in a dose‐dependent manner. Co‐immunoprecipitation indicated that guaiacol blocked RANK‐TRAF6 association and RANK‐C‐Src association. Moreover, guaiacol prevented phosphorylation of p65, p50, IκB (NF‐κB pathway), ERK, JNK, c‐fos, p38 (MAPK pathway) and Akt (AKT pathway), and reduced the expression levels of Cathepsin K, CTR, MMP‐9 and TRAP. Guaiacol also suppressed the expression of nuclear factor of activated T‐cells cytoplasmic 1(NFATc1) and the RANKL‐induced Ca²⁺ oscillation. In vivo, it ameliorated ovariectomy‐induced bone loss by suppressing excessive osteoclastogenesis. Taken together, our findings suggest that guaiacol inhibits RANKL‐induced osteoclastogenesis by blocking the interactions of RANK with TRAF6 and C‐Src, and by suppressing the NF‐κB, MAPK and AKT signalling pathways. Therefore, this compound shows therapeutic potential for osteoclastogenesis‐related bone diseases, including postmenopausal osteoporosis.

Roles of EvpP in Edwardsiella piscicida-Macrophage Interactions

Edwardsiella piscicida is found to be an important facultative intracellular pathogen with a broad host range. These organisms can replicate and survive within host macrophages to escape from the subversion of the immune defense. E. piscicida-macrophage interaction is very important in determining the outcome of edwardsiellasis. As an effector protein of E. piscicida T6SS, EvpP has been determined to be a very important virulence factor for E. piscicida, although its precise role in E. piscicida-macrophage interactions is not yet clear. In this study, the roles of EvpP in E. piscicida-macrophage interactions were characterized. Here, we constructed the deletion mutants of evpP (ΔevpP) and complementation (ΔevpP-C) by the allelic exchange method. Compared to wild type strain (WT), ΔevpP was found to be attenuated for growth within macrophages. In line with this observation, we found its survival capacity was lower than WT under oxidative and acid stress in vitro, which simulate conditions encountered in host macrophages. Attenuation of ΔevpP also correlated with enhanced activation of macrophages, as reflected by augmented NO production in ΔevpP-treated macrophages. Moreover, compared to WT, ΔevpP induced markedly increased apoptosis of macrophages, characterized by increased Annexin V binding and the activation of cleaved caspase-3. These findings provided strong evidence that EvpP is involved in the process of E. piscicida-macrophage interactions and is required for its survival and replication in macrophages. Thus, we propose that EvpP might be an important factor that controlling the fate of E. piscicida inside macrophages. To further exploring the underlying mechanism of EvpP action, the cDNA library was constructed from E. piscicida-infected macrophages and a yeast two-hybrid screen was performed to search for cellular proteins interacting with EvpP. Ribosomal protein S5 (RPS5) was identified as a target of EvpP. Furthermore, the interaction was validated with co-immunoprecipitation assay. This result implies that the observed effect of EvpP on macrophages might be related to RPS5-mediated regulation, contributing to a better understanding of the mechanisms of EvpP involved in E. piscicida-macrophage interactions.

l-tetrahydropalmatine suppresses osteoclastogenesis in vivo and in vitro via blocking RANK-TRAF6 interactions and inhibiting NF-κB and MAPK pathways

Bone homeostasis is delicately orchestrated by osteoblasts and osteoclasts. Various pathological bone loss situations result from the overactivated osteoclastogenesis. Receptor activator of nuclear factor κB ligand (RANKL)-activated NF-κB and MAPK pathways is vital for osteoclastogenesis. Here, we for the first time explored the effects of l-tetrahydropalmatine (l-THP), an active alkaloid derived from corydalis, on the formation and function of osteoclasts in vitro and in vivo. In RAW264.7 cells and bone marrow monocytes cells (BMMCs), l-THP inhibited osteoclastic differentiation at the early stage, down-regulated transcription level of osteoclastogenesis-related genes and impaired osteoclasts functions. Mechanically, Western blot showed that l-THP inhibited the phosphorylation of P50, P65, IκB, ERK, JNK and P38, and the electrophoretic mobility shift assay (EMSA) revealed that DNA binding activity of NF-κB was suppressed, ultimately inhibiting the expression of nuclear factor of activated T cells (NFATc1). Besides, Co-immunoprecipitation indicated that l-THP blocked the interactions of RANK and TNF receptor associated factor 6 (TRAF6) at an upstream site. In vivo, l-THP significantly inhibited ovariectomy-induced bone loss and osteoclastogenesis in mice. Collectively, our study demonstrated that l-THP suppressed osteoclastogenesis by blocking RANK-TRAF6 interactions and inhibiting NF-κB and MAPK pathways. l-THP is a promising agent for treating osteoclastogenesis-related diseases such as post-menopausal osteoporosis.

The Coumarin Derivative 5'-Hydroxy Auraptene Suppresses Osteoclast Differentiation via Inhibiting MAPK and c-Fos/NFATc1 Pathways

The phytochemical substances, coumarin derivatives, have demonstrated antiresorptive bone effects by suppressing osteoclast differentiation in vitro and in vivo. Recently, we have identified 5′-hydroxy auraptene (5′-HA), a coumarin derivative isolated from Lotus lalambensis Schweinf, as a novel stimulator for osteoblast differentiation. In this study, we investigated the effect of 5′-HA on osteoclast differentiation of mouse bone marrow (BM) cells. The effect of 5′-HA on BM cell proliferation and osteoclast differentiation was determined by measuring cell viability and tartrate-resistant acid phosphatase (TRAP) enzyme activity, quantification of TRAP⁺ multinucleated cells (TRAP⁺MNCs), and quantitative real-time PCR (qPCR) of osteoclastic gene expression. Regulation of NF-κB, c-Fos/NFATc1, and MAPK signaling pathways by 5′-HA during osteoclastogenesis was measured by the NF-κB reporter assay and Western blot analysis. 5′-HA significantly suppresses the receptor activator of NF-κB ligand (RANKL) induced osteoclast differentiation of BM cells in a dose-dependent manner. Consistently, treatment of BM cells with 5′-HA significantly inhibited RANKL-induced activation of NF-κB and c-Fos/NFATc1 pathways in a dose-dependent manner. Furthermore, RANKL-induced phosphorylation of ERK1/2, p-38, and JNK was significantly inhibited by 5′-HA in BM cells. In conclusion, we identified 5′-HA as a novel coumarin derivative that suppresses RANKL-induced osteoclastogenesis via inhibiting c-Fos/NFATc1 and MAPK signaling pathways.

Overview of Molecular Mechanisms Involved in Herbal Compounds for Inhibiting Osteoclastogenesis from Macrophage Linage RAW264.7

Differentiation from RAW264.7 cells to osteoclasts rely on many signaling pathways, such as NF-κB, MAPK, Akt and others. However, the specific underlying mechanisms are not clear. Recently, much works have focused on the inhibitory effects of plant derived compounds in the differentiation from RAW264.7 to osteoclasts. However, the specific mechanisms remain unclear. In this paper, we summarize a lot of plant derived compounds which exert blocking effect on the progression of differentiation via signaling pathways.

18β-Glycyrrhetinic Acid Inhibits Osteoclastogenesis In Vivo and In Vitro by Blocking RANKL-Mediated RANK-TRAF6 Interactions and NF-κB and MAPK Signaling Pathways

Bone metabolism is determined by a delicate balance between bone resorption by osteoclasts and bone formation by osteoblasts. The imbalance due to over-activated osteoclasts plays an important role in various diseases. Activation of NF-κB and MAPK signaling pathways by receptor activator of nuclear factor -κB ligand (RANKL) is vital for osteoclastogenesis. Here, we for the first time explored the effects of 18β-glycyrrhetinic acid (18β-GA), a pentacyclic triterpenoid found in the Glycyrrhiza glabra L roots, on RANKL-induced osteoclastogenesis, osteoclast functions and signaling pathways in vitro and in vivo. In bone marrow monocytes (BMMs) and RAW264.7 cells, 18β-GA inhibited osteoclastogenesis, decreased expression of TRAP, cathepsin K, CTR and MMP-9, blocked actin ring formation and compromised osteoclasts functions in a dose-dependent manner at an early stage with minimal effects on osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). For underlying molecular mechanisms, 18β-GA inhibited RANKL-induced phosphorylation of p65, p50, and IκB, blocked p65 nuclear translocation and decreased the DNA-binding activity of NF-κB. Besides, 18β-GA inhibited the activation of the MAPK pathways. Co-immunoprecipitation showed that 18β-GA treatment blocked RANK-TRAF6 association at an upstream site. In vivo, 18β-GA treatment inhibited ovariectomy-induced osteoclastogenesis and reduced bone loss in mice. Overall, our results demonstrated that 18β-GA inhibited RANKL-induced osteoclastogenesis by inhibiting RANK expression in preosteoclasts and blocking the binding of RANK and TRAF6 which lead to the inhibition of NF-κB and MAPK signaling pathways. 18β-GA is a promising novel candidate in the treatment of osteoclast-related diseases such as postmenopausal osteoporosis.

Tanshinone IIA attenuates osteoclastogenesis in ovariectomized mice by inactivating NF-kB and Akt signaling pathways

Osteoporosis is a common disease associated with age and menopausal status. Postmenopausal osteoporosis is the most common type of primary osteoporosis and is accompanied by increased risk of osteoporotic fracture. Natural and herbal compounds have long been used to prevent and treat many human diseases. Here, we demonstrated that tanshinone IIA prevented ovariectomy-induced bone loss in an in vivo mouse model that closely mimics osteoporosis. In addition, we found that tanshinone IIA inhibited the receptor activator of nuclear factor NF-κB ligand (RANKL)-induced osteoclast differentiation and osteoclastogenesis in vitro. Tanshinone IIA treatment also abrogated RANKL-induced activation of the NF-κB pathway, PI3-kinase/Akt signaling, and the mitogen-activated protein kinase (MAPK) pathways, including nuclear translocation of NF-κB p65 and phosphorylation of IκB, extracellular signal-regulated kinase (ERK), p38, and Akt. Inactivation of these pathways resulted in deceased expression of osteoclastogenesis-related markers. These results suggest that tanshinone IIA, a natural drug, has the potential to treat and prevent bone loss diseases, including postmenopausal osteoporosis.