Cistanche deserticola polysaccharide attenuates osteoclastogenesis and bone resorption via inhibiting RANKL signaling and reactive oxygen species production

The potential, challenges, and prospects of polysaccharides from the genus Cistanche as therapeutic agents for aging-related diseases: A review

Cistanche has been utilized globally as both a food and medicinal ingredient for centuries. Modern pharmacological studies have demonstrated that polysaccharides, as the primary active components of Cistanche, exhibit diverse pharmacological activities, including immunomodulatory, antioxidant, anti-fatigue, and antitumor effects. As a result, these polysaccharides have emerged as focal points for research and application within the genus Cistanche, particularly in the context of age-related diseases. Furthermore, the diversity of methods used for extraction, isolation, and purification can significantly influence the content, purity, and subsequent structural characterization of genus Cistanche polysaccharides (CPS), thereby impacting their biological activities. Despite the significance of CPS, existing literature primarily summarizes polysaccharides from C. deserticola, lacking a comprehensive review of the entire genus. Given the critical role of CPS in biological research and drug discovery, this paper systematically reviews recent advancements in CPS research, encompassing extraction, isolation, purification methods, structural characterization, pharmacological activities, and potential mechanisms of action. The paper also explores the potential mechanisms of action of CPS in mitigating age-related degenerative changes. This review aims to provide a theoretical foundation for the advancing study of polysaccharides from the genus Cistanche and the development of functional foods targeting age-related health issues.

Buqi-Tongluo Decoction inhibits osteoclastogenesis and alleviates bone loss in ovariectomized rats by attenuating NFATc1, MAPK, NF-κB signaling

Osteoporosis is a prevalent skeletal condition characterized by reduced bone mass and strength, leading to increased fragility. Buqi-Tongluo (BQTL) decoction, a traditional Chinese medicine (TCM) prescription, has yet to be fully evaluated for its potential in treating bone diseases such as osteoporosis. To investigate the mechanism by which BQTL decoction inhibits osteoclast differentiation in vitro and validate these findings through in vivo experiments. We employed MTS assays to assess the potential proliferative or toxic effects of BQTL on bone marrow macrophages (BMMs) at various concentrations. TRAcP experiments were conducted to examine BQTL's impact on osteoclast differentiation. RT-PCR and Western blot analyses were utilized to evaluate the relative expression levels of osteoclast-specific genes and proteins under BQTL stimulation. Finally, in vivo experiments were performed using an osteoporosis model to further validate the in vitro findings. This study revealed that BQTL suppressed receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis and osteoclast resorption activity in vitro in a dose-dependent manner without observable cytotoxicity. The inhibitory effects of BQTL on osteoclast formation and function were attributed to the downregulation of NFATc1 and c-fos activity, primarily through attenuation of the MAPK, NF-κB, and Calcineurin signaling pathways. BQTL's inhibitory capacity was further examined in vivo using an ovariectomized (OVX) rat model, demonstrating a strong protective effect against bone loss. BQTL may serve as an effective therapeutic TCM for the treatment of postmenopausal osteoporosis and the alleviation of bone loss induced by estrogen deficiency and related conditions.

Naringenin can Inhibit the Pyroptosis of Osteoblasts by Activating the Nrf2/HO-1 Signaling Pathway and Alleviate the Differentiation Disorder of Osteoblasts Caused by Microgravity

Naringenin (4,5,7-trihydroxyflavone, NAR) is an effective active ingredient in Rhizoma Drynariae, which has many biological functions, encompassing anti-inflammatory and -oxidant functions. Prior research has shown that NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasomes possessed a significant contribution to osteoporosis. However, the NAR impact on bone loss caused by microgravity remains unclear. Classical microgravity simulation methods were used to induce simulated microgravity (SMG) in mice and cells. Microcomputed tomography, immunohistochemical examination, and hematoxylin and eosin staining were implemented to ascertain alterations in bone microstructure and morphology in mice subsequent to NAR gavage. Cellular investigations were implemented encompassing quantitative real-time polymerase chain reaction, Western blotting, and immunofluorescence labeling to investigate the molecular mechanism behind NAR resistance to microgravity-induced bone loss. Our research has shown that NAR can significantly enhance the SMG-stimulated alterations in bone microstructure and morphology in mice, mainly by increasing the trabecular thickness, bone volume fraction, and trabecular number while increasing the bone trabecula number. Cell experiments also showed that SMG caused the activation of inflammatory corpuscles of NLRP3 and induced pyroptosis simultaneously, which can be confirmed by the upregulation of protein and mRNA expression levels such as those of NLRP3, cleaved caspase-1, gasdermin D, and apoptosis-associated speck-like protein. The occurrence of pyroptosis further led to the disorder of osteogenic differentiation, which showed that the osteopontin, Runt-related transcription factor 2, bone morphogenetic protein 2, and alkaline phosphatase expression levels were decreased. The intervention of NAR can activate the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway, reverse this phenomenon via controlling the reactive oxygen species generation in cells and correcting mitochondrial malfunction, weaken the pyroptosis of osteoblasts (OBs), and promote osteogenic differentiation. In summary, NAR could hinder the pyroptosis of OBs caused by SMG and promote osteogenic differentiation via activating the Nrf2/HO-1 pathway. This provides a unique view for inhibiting bone loss under weightlessness and confirms the NAR capacity in treating microgravity-stimulated bone loss, giving new ideas and methods for future space medicine development.

Advance in Cistanche deserticola Y. C. Ma. polysaccharides: Isolation, structural characterization, bioactivities and application: A review

Cistanche deserticola Y. C. Ma (CD), is mainly distributed in the regions of China (Xinjiang, Inner Mongolia, Gansu), Mongolia, Iran and India. Cistanche deserticola polysaccharide (CDPs), as one of the main components and a crucial bioactive substance of CD, has a variety of pharmacological activities, including immunomodulatory, anti-aging, anti-oxidant, hepatoprotective, anti-osteoporotic, anti-inflammatory, intestinal flora regulatory effects. Many polysaccharides have been successfully obtained in the last three decades from CD. However, there is currently no comprehensive review available concerning CDPs. Considering the importance of CDPs for biological study and drug discovery, the present review aims to systematically summarize the recent major studies on extraction and purification methods of polysaccharides from CD, as well as the characterization of their chemical structure, biological activity, structure-activity relationship, and the application of CDPs in pharmaceutical field. Meanwhile, the shortcomings of CDPs research are further discussed in detail, and new valuable insights for future CDPs research as therapeutic agents and functional foods are proposed.

Network pharmacological study and in vitro studies validation-Molecular dynamics simulation of Cistanche deserticola in promoting periodontitis and bone remodeling

OBJECTIVE

Periodontitis is a chronic infectious disease, characterized by loss of alveolar bone and supporting tissues. Cistanche deserticola(Cd), a local medicinal herb in Xinjiang, possesses favorable biological characteristics and potential applications. Our aim is to investigate the remodeling properties of Cd extract and elucidate the specific mechanisms underlying its therapeutic effects on periodontitis, by employing a combination of basic experimental and network pharmacology approaches.

METHODS

Firstly, UHPLC-QTOF-MS analysis was conducted on Cd extract to identify its main components, with several compounds were identified by standard. Subsequently, in vitro studies were performed using the Cd extract on MC3T3-E1 cells. Cell proliferation viability was assessed using CCK-8 and apoptosis assays, while ALP and ARS staining and quantitative experiments, qRT-PCR, and Western blot assays were employed to evaluate the osteogenic differentiation capability. Network pharmacology analysis was then carried out using the identified compounds to establish a database of Cd components and targets, along with a database of periodontitis. The intersection of these databases revealed the network relationship between Cd components-mapped genes-signaling pathways. KEGG/GO pathway analysis of the targets was performed to filter potential enriched pathways. PPI/CytoHubba protein interaction network analysis was utilized to identify hub genes. Molecular docking and molecular dynamics simulations were employed to analyze the docking and interaction between core gene and Cd components.

RESULTS

We detected 38 major components in the Cd extract, with Echinacoside, Acteoside, Tubuloside A, and Cistanoside A undergoing standard substance verification. In vitro studies indicated that the Cd, at concentrations below 100 μg/ mL, did not affect cell proliferation and inhibited apoptosis. Osteogenesis assays demonstrated that Cd at concentrations of 1 μg/ mL, 10 μg/ mL, and 100 μg/ mL significantly promoted the osteogenic differentiation ability of MC3T3-E1 cells. It also notably upregulated the mRNA and protein levels of Alp, Bmp2, Runx2, and Opn, and the optimal concentration was 10 μg/mL. Network pharmacology results revealed the network relationship between Cd's components, crossed targets and signaling pathways. Combined with KEGG/GO pathway analysis and PPI/CytoHubba protein interaction network analysis. The key pathway and hub genes of Cd regulating periodontitis are both related to hypoxia pathway and HIF-1α. Molecular docking results showed a strong binding affinity between Cd compounds and hub genes, and molecular dynamics simulation results indicated the stability of the complexes formed between HIF-1α and several Cd compounds.

CONCLUSION

Cistanche deserticola exhibits a notable capacity to promote bone regeneration, and its mechanism of action in regulating periodontitis is associated with the hypoxia signaling pathway. HIF-1α may serve as a potential core gene. Future research will focus on exploring the mechanism of Cd in intervene periodontitis and promoting bone remodeling in hypoxic environment.

Traditional Chinese medicine in osteoporosis: from pathogenesis to potential activity

Osteoporosis characterized by decreased bone density and mass, is a systemic bone disease with the destruction of microstructure and increase in fragility. Osteoporosis is attributed to multiple causes, including aging, inflammation, diabetes mellitus, and other factors induced by the adverse effects of medications. Without treatment, osteoporosis will further progress and bring great trouble to human life. Due to the various causes, the treatment of osteoporosis is mainly aimed at improving bone metabolism, inhibiting bone resorption, and promoting bone formation. Although the currently approved drugs can reduce the risk of fragility fractures in individuals, a single drug has limitations in terms of safety and effectiveness. By contrast, traditional Chinese medicine (TCM), a characteristic discipline in China, including syndrome differentiation, Chinese medicine prescription, and active ingredients, shows unique advantages in the treatment of osteoporosis and has received attention all over the world. Therefore, this review summarized the pathogenic factors, pathogenesis, therapy limitations, and advantages of TCM, aiming at providing new ideas for the prevention and treatment of OP.

Structure characterization of polysaccharides from Cistanche deserticola and their neuroprotective effects against oxidative stress in slow transit constipation mice

Oxidative stress-induced enteric neuropathy is an important factor in slow transit constipation (STC). Cistanche deserticola crude polysaccharides (CDCP) are natural antioxidants with various biological activities. We prepared CDCP through water-extract and alcohol-precipitation methods. The structural characteristics of CDCP were analyzed by infrared spectroscopy and methylation analysis. The results showed that CDCP was primarily composed of (1 → 4)-linked glucans with minor amounts of pectic polysaccharides. Different doses of CDCP (100, 200, and 400 mg/kg) were administered to loperamide-induced STC mice to explore the therapeutic effects of CDCP. Compared with the untreated group, CDCP treatment significantly improved constipation symptoms, relevant gut-regulating peptides levels, colonic pathological damage, and colonic myenteric nerons injury. CDCP enhanced the antioxidant capacity by decreasing Malondialdehyde (MDA) content, increasing Superoxide Dismutase (SOD) activity and Reduced Glutathione (GSH) content. CDCP significantly reduced oxidative stress-induced injury by preserving mitochondrial function in the colonic myenteric plexus. Furthermore, the neuroprotective effects of CDCP might be associated with the Nrf2/Keap1 pathway. Thus, our findings first revealed the potential of CDCP to protect the colonic myenteric plexus against oxidative stress-induced damage in STC, establishing CDCP as promising candidates for natural medicine in the clinical management of STC.

Beneficial effect and mechanism of natural resourced polysaccharides on regulating bone metabolism through intestinal flora: A review

Bone metabolism is an important biological process for maintaining bone health. Polysaccharides of natural origin exert beneficial effects on bone metabolism. Polysaccharide molecules often have difficulty passing through the intestinal cell membrane and are directly absorbed in the gastrointestinal tract. Therefore, polysaccharides may affect intestinal flora and play a role in disease treatment. We performed a comprehensive review of the relevant literature published from 2003 to 2023. We found that several polysaccharides from traditional Chinese medicines, including Astragalus, Achyranthes bidentata and Eucommia ulmoides, and the polysaccharides from several dietary fibers mainly composed of inulin, resistant starch, and dextran could enrich the intestinal microbiota group to regulate bone metabolism. The promotion of polysaccharide decomposition by regulating the Bacteroides phylum is particularly critical. Studies on the structure-activity relationship showed that molecular weight, glycosidic bonds, and monosaccharide composition may affect the ability of polysaccharides. The mechanism by which polysaccharides regulate intestinal flora to enhance bone metabolism may be related to the regulation of short-chain fatty acids, immunity, and hormones, involving some signaling pathways, such as TGF-β, Wnt/β-catenin, BMP/Smads, and RANKL. This paper provides a useful reference for the study of polysaccharides and suggests their potential application in the treatment of bone metabolic disorders.

Codonopsis pilosula polysaccharides promote osteogenic differentiation and inhibit lipogenic differentiation of rat bone marrow stem cells by activating β-catenin

Aberrant bone marrow mesenchymal stem cell (BMSC) lineage differentiation leads to osteoporosis. Codonopsis pilosula polysaccharides (CPPs) have been widely used in traditional Chinese medicines, due to their multiple pharmacological actions. However, little is known regarding their effects on BMSC differentiation. This study aimed to identify the effects and mechanisms of CPPs on osteogenic and adipogenic differentiation in rat BMSCs. An osteoporosis model was established in Sprague-Dawley (SD) rats through bilateral ovariectomy (OVX), and be applied to observe the effect of CPPs on osteoporosis in vivo. The ability of CPPs to affect rBMSC proliferation was determined using the CCK-8 assay, and the osteogenic differentiation of rBMSCs measured by ALP and Alizarin Red S staining. The adipogenic differentiation of rBMSCs was measured by Oil Red O staining. The mRNA and protein levels related to osteogenesis and adipogenic differentiation of rBMSCs were measured using qRT-PCR and western blotting, respectively. Cellular immunofluorescence was used to detect cytokine expression and localisation in rBMSCs. We observed that CPPs ameliorated bone loss in OVX rats. CPPs considerably enhanced osteogenic differentiation by increasing ALP activity and the prevalence of mineralised nodules and promoting the mRNA and protein expression of osteogenic differentiation markers (RUNX2, COL I, ALP, and OPN). Furthermore, it inhibited the accumulation of lipid vesicles in the cytoplasm and the mRNA and protein expression levels of adipogenic differentiation markers (PPARγ and C/EBPα) in a concentration-dependent manner. Meanwhile, CPPs notably increased the mRNA and protein expression of β-catenin, the core protein of the Wnt/β-catenin signaling pathway, in a concentration-dependent manner. Adding DKK1, a mature inhibitor of the Wnt/β-catenin signaling pathway, partially suppressed CPP-stimulated β-catenin activation, and reversed the acceleration of osteogenic differentiation and the inhibition of lipogenic differentiation. Our observations demonstrated CPPs ameliorate bone loss in OVX rats in vivo, and favour osteogenic differentiation while inhibit adipogenic differentiation of rBMSCs in vitro. The findings suggested that CPPs could serve as functional foods for bone health, and have great potential for the prevention and treatment of osteoporosis.

Glycobiology in osteoclast differentiation and function

Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.

Efficacy assessment of methylcellulose-based thermoresponsive hydrogels loaded with gallium acetylacetonate in osteoclastic bone resorption

Homeostatic imbalance involving progressive stimulation of osteoclast (OC) differentiation and function will lead to an increased risk of fragility fractures. In this regard, we investigated gallium acetylacetonate (GaAcAc) as a possible treatment for osteoclastic bone resorption. Further, the extent to which suitable delivery systems can enhance the therapeutic potential of GaAcAc was evaluated. GaAcAc solution (10-50 µg/mL) suppressed OC differentiation using murine monocytic RAW 264.7 or hematopoietic stem cells. Methylcellulose-based hydrogels were fabricated and characterized based on biocompatibility with bone cells, GaAcAc loading, and thermoresponsive behavior using storage (G') and loss (G″) moduli parameters. Compared to GaAcAc solution, hydrogels loaded with GaAcAc (GaMH) were more effective in suppressing OC differentiation and function. The number and extent of bone resorption pits from ex vivo studies were markedly reduced with GaMH treatment. Mechanistic assessment of GaMH efficacy showed superiority, compared to GaAcAc solution, in downregulating the expression of key markers involved in mediating OC differentiation (such as NFAT2, cFos, TRAF6, and TRAP) as well as in bone resorption by OCs (cathepsin K or CTSK). Additional studies (in vitro and in vivo) suggested that the performance of GaMH could be ascribed to controlled release of GaAcAc and the ability to achieve prolonged bio-retention after injection in BALB/c mice, which plausibly maximized the therapeutic impact of GaAcAc. Overall, the work demonstrated, for the first time, the therapeutic efficacy of GaAcAc and the therapeutic potential of GaMH delivery systems in osteoclastic bone resorption.

Oxidative stress: A common pathological state in a high-risk population for osteoporosis

Osteoporosis is becoming a major concern in the field of public health. The process of bone loss is insidious and does not directly induce obvious symptoms. Complications indicate an irreversible decrease in bone mass. The high-risk populations of osteoporosis, including postmenopausal women, elderly men, diabetic patients and obese individuals need regular bone mineral density testing and appropriate preventive treatment. However, the primary changes in these populations are different, increasing the difficulty of effective treatment of osteoporosis. Determining the core pathogenesis of osteoporosis helps improve the efficiency and efficacy of treatment among these populations. Oxidative stress is a common pathological state secondary to estrogen deficiency, aging, hyperglycemia and hyperlipemia. In this review, we divided oxidative stress into the direct effect of reactive oxygen species (ROS) and the reduction of antioxidant enzyme activity to discuss their roles in the development of osteoporosis. ROS initiated mitochondrial apoptotic signaling and suppressed osteogenic marker expression to weaken osteogenesis. MAPK and NF-κB signaling pathways mediated the positive effect of ROS on osteoclast differentiation. Antioxidant enzymes not only eliminate the negative effects of ROS, but also directly participate in the regulation of bone metabolism. Additionally, we also described the roles of proinflammatory factors and HIF-1α under the pathophysiological changes of inflammation and hypoxia, which provided a supplement of oxidative stress-induced osteoporosis. In conclusion, our review showed that oxidative stress was a common pathological state in a high-risk population for osteoporosis. Targeted oxidative stress treatment would greatly optimize the therapeutic schedule of various osteoporosis treatments.

Structural characterization and anti-osteoporosis effects of polysaccharide purified from Eucommia ulmoides Oliver cortex based on its modulation on bone metabolism

EuOCP3, with a molecular weight of 38.1 kDa, is an acidic polysaccharide purified from Eucommia ulmoides Oliver cortex. Herein, we determined that the main backbone of EuOCP3 was predominantly composed of →4)-α-GalpA-(1 → 4)-α-GalpA-(1→, →4)-α-GalpA-(1 → 5)-α-Araf-(1→, →4)-α-GalpA-(1 → 2)-α-Rhap-(1→, and →4)-α-GalpA-(1 → 5)-α-Araf-(1 → 2)-α-Rhap-(1 → repeating blocks, which were connected by →2,3,5)-α-Araf-(1→. The side chains, substituted at C-2 and C-5 of →2,3,5)-α-Araf-(1→, contained T-β-Araf→ and T-β-Araf → 4)-α-GalpA-(1 → residues. In dexamethasone (Dex)-induced osteoporosis (OP) mice, EuOCP3 treatment restored cortical bone thickness, increased mineralized bone area, enhanced the number of osteoblasts, and decreased the number of osteoclasts on the surface of cortical bone. Combining analysis of gut microflora, serum metabolite profiles, and biological detection results, we demonstrated that EuOCP3 regulated the abundance of specific species within the gut microflora, such as g_Dorea and g_Prevotella, and ameliorated oxidative stress. In turn, enhancement of osteogenic function and restoration of bone metabolism via the extracellular signal-regulated kinase (ERK)/c-Jun N-terminal kinase (JNK)/nuclear factor erythroid-2 related factor 2 (Nrf2) signaling pathway was indicated. The current findings contribute to understanding the potential of EuOCP3 in anti-OP treatment.

A review focusing on the benefits of plant-derived polysaccharides for osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by progressive cartilage degeneration, which imposes a heavy physical and financial burden on the middle-aged and elderly population. As the pathogenesis of OA has not been fully elucidated, it is of great importance to develop targeted therapeutic or preventive medications. Traditional therapeutic drugs, such as non-steroidal anti-inflammatory drugs, steroids and opioids, have significant side effects, making the exploration for safe and effective alternative therapeutic drugs urgent. In recent years, many studies have reported the role of plant-derived polysaccharides in anti-inflammation, anti-oxidation, regulation of chondrocyte metabolism and proliferation, and cartilage protection, and have demonstrated their great potential in the treatment of OA. Therefore, by focusing on studies related to the intervention of plant-derived polysaccharides in OA, including in vivo and in vitro experiments, this review aimed to classify and summarize the existing research findings according to different mechanisms of action. In addition, reports on plant-derived polysaccharides as nanoparticles were also explored. Then, candidate monomers and theoretical bases were provided for the further development and application of novel drugs in the treatment of OA.

Cistanche Deserticola for Regulation of Bone Metabolism: Therapeutic Potential and Molecular Mechanisms on Postmenopausal Osteoporosis

Osteoporosis is a generalized disease of bone that leads to a loss of bone density and bone mass, destruction of bone microstructure, increased brittleness and therefore fracture. At present, the main treatment of Western medicine is drug therapy such as bisphosphonates, calcitriol, vitamin D, etc. However, long-term use of these drugs may bring some adverse reactions. Chinese herbal medicine Cistanche deserticola could regulate bone metabolism by promoting osteoblast activity and inhibiting osteoclast activity with low toxicity and adverse reactions. Therefore, Cistanche deserticola has attracted increasing attention for its efficacy in the prevention and treatment of osteoporosis in recent years. Here we present a literature review of the molecular pathways involved in osteoporosis and the effects of Cistanche deserticola on bone metabolism. Our objective is to clarify the mechanism of Cistanche deserticola in the treatment of osteoporosis.

Isoliensinine Suppresses Osteoclast Formation Through NF-κB Signaling Pathways and Relieves Ovariectomy-Induced Bone Loss

Osteoporosis is among the major contributors of pathologic fracture in postmenopausal women, which is caused by the bone metabolic disorder owing to the over-activation of osteoclasts. Inhibition of osteoclast differentiation and maturation has become a mainstream research interest in the prevention of osteoporosis. Isoliensinine (Iso) is a dibenzyl isoquinoline alkaloid with antioxidant, anti-inflammatory, and anti-cancer activities. However, whether it can be used as a potential treatment for osteoporosis remains undiscovered. Here, we investigated whether Iso might suppress the differentiation of osteoclasts in vitro and in vivo to play an anti-osteoporosis role. Our results showed that Iso inhibits the formation of mature multinuclear osteoclasts induced by RANKL, the bone resorption, and the osteoclast-specific genes expression by blocking the nuclear translocation of NF-κB p65, and the effect was in a dosage-dependent way. Furthermore, we investigated the therapeutic effect of Iso on osteoporosis in ovariectomized (OVX) mice. We found that Iso attenuated bone loss in the OVX mice and significantly promoted BS, Conn. DN, Tb.Th, TB.N, and BV/TV Index. All in all, Iso showed a prominent effect of osteoclast inhibition, with great promise for treating osteoporosis.

Structural characterization of a mannoglucan polysaccharide from Dendrobium huoshanense and evaluation of its osteogenesis promotion activities

Dendrobium huoshanense, a valuable traditional Chinese herb, is widely used to prolong life in China. Our study aims to characterize the structure and osteogenesis-promotion effects of a heteropolysaccharide component isolated from Dendrobium huoshanense (DHPW1). The structure of DHPW1 was characterized using gas chromatography-mass spectrometry and nuclear magnetic resonance, while its osteogenic activity was evaluated using MG-63 cells and zebrafish skulls. The results showed that the molecular weight of DHPW1 was 230 kDa and it was mainly composed of mannose and glucose. In addition, the DHPW1 backbone consisted of (1 → 4)-linked-β-D-Mannopyranosyl and (1 → 4)-linked-β-d-Glucopyranosyl. Furthermore, DHPW1 significantly increased ALP activity and mineralized nodule formation in MG-63 cells. DHPW1 in zebrafish skull models significantly enhanced the relative fluorescence intensity of bone mass and increased the degree of bone mineralization. These results suggested that the DHPW1 component in D. huoshanense has potential to promote osteogenesis.

Genkwanin Prevents Lipopolysaccharide-Induced Inflammatory Bone Destruction and Ovariectomy-Induced Bone Loss

Objectives

The first objective of this study was to probe the effects of genkwanin (GKA) on osteoclast. The second goal of this study was to study whether GKA can protect lipopolysaccharide (LPS) and ovariectomized (OVX) induced bone loss.

Materials and Methods

Various concentrations of GKA (1 and 10 mg/kg) were injected into mice. Different concentrations of GKA (1 and 5 μM) were used to detect the effects of GKA on osteoclast and osteoblast.

Key Findings

GKA attenuated the osteoclast differentiation promoted by RANKL and expression of marker genes containing c-fos, ctsk as well as bone resorption related gene Trap and to the suppression of MAPK signaling pathway. In addition, GKA induced BMMs cell apoptosis in vitro. Moreover, GKA prevented LPS-induced and ovariectomized-induced bone loss in mice.

Conclusion

Our research revealed that GKA had a potential to be an effective therapeutic agent for osteoclast-mediated osteoporosis.

Traditional Chinese Medicine as a Promising Strategy for the Treatment of Alzheimer's Disease Complicated With Osteoporosis

Alzheimer’s disease (AD) and osteoporosis (OP) are progressive degenerative diseases caused by multiple factors, placing a huge burden on the world. Much evidence indicates that OP is a common complication in AD patients. In addition, there is also evidence to show that patients with OP have a higher risk of AD than those without OP. This suggests that the association between the two diseases may be due to a pathophysiological link rather than one disease causing the other. Several in vitro and in vivo studies have also proved their common pathogenesis. Based on the theory of traditional Chinese medicine, some classic and specific natural Chinese medicines are widely used to effectively treat AD and OP. Current evidence also shows that these treatments can ameliorate both brain damage and bone metabolism disorder and further alleviate AD complicated with OP. These valuable therapies might provide effective and safe alternatives to major pharmacological strategies.

Cistanche promotes the adipogenesis of 3T3-L1 preadipocytes

Cistanche deserticola Ma (cistanche) is a traditional herb with a wide range of therapeutic properties. However, no evidence of cistanche’s effect on adipogenesis has been found. The effect of cistanche that promotes the adipogenesis of 3T3-L1 preadipocytes was proved by using MTT spectrophotometry, Nile Red staining, Oil Red O staining and transcriptome sequencing technology. The mRNA level of key transcription factors for adipogenesis such as PPAR, AP2 and LPL were examined by RT-PCR. The results showed that the intracellular lipid content in cistanche treated cells were notably increased when compared with the non-treated cells. Between the differentiation and cistanche treated groups, the expression of adipogenesis related genes such as grow hormone releasing hormone (Ghrp), BCL2/adenovirus E1B interacting protein 3 (Bnip3) and Gastric inhibitory polypeptide receptor (Gipr) were significantly increased. Our findings also verified that cistanche promoted adipogenesis, which was accompanied by up-regulated level of Bnip3 and PPAR. This study could uncover new signaling pathways involved in adipogenesis regulation.

Benefits and mechanisms of polysaccharides from Chinese medicinal herbs for anti-osteoporosis therapy: A review

Osteoporosis is a systemic metabolic bone disease with an increasing incidence rate. Chinese medicinal herbs have a long history of treating bone diseases. Polysaccharides are an important category of phytochemicals in Chinese medicinal herbs, and their health benefits have increased the interest of the public. Numerous studies have indicated that polysaccharides exhibit anti-osteoporosis effects by balancing bone resorption and bone formation, but the detailed effects and mechanism have not been systematically summarized. We performed a comprehensive review of the literature to consolidate studies for the period 2000-2021 by conducting electronic searches on the PubMed, CNKI, VIP, and Wanfang databases. In total, polysaccharides from 19 kinds of Chinese medicinal herbs in 54 studies have shown bone homeostasis protective properties. In vivo and in vitro experiments have demonstrated that polysaccharides present properties in the treatment of postmenopausal osteoporosis, senile osteoporosis, and glucocorticoid-induced secondary osteoporosis, especially postmenopausal osteoporosis. Moreover, a number of signalling pathways, such as the Wnt/β-catenin signalling pathway, BMP/SMAD/RUNX2 signalling pathway, OPG/RANKL/RANK signalling pathway, apoptosis pathway, and transcription factors, are regulated by polysaccharides and participate in improving bone homeostasis. This review will provide a better understanding of the anti-osteoporotic effects of polysaccharides and the concomitant modulations of signalling pathways.

Hydroxytyrosol prevents periodontitis-induced bone loss by regulating mitochondrial function and mitogen-activated protein kinase signaling of bone cells

Reactive oxygen species (ROS) overproduction promotes the alveolar bone loss during the development of periodontitis. Mitochondria are the principal source of ROS. Hydroxytyrosol (HT), a natural phenolic compound present in olive oil, is well known for its antioxidant and mitochondrial-protective prosperities. Nonetheless, the impact of HT on periodontitis and its related mechanisms underlying bone cell behavior remains unknown. Osteoclasts differentiated from RAW264.7 model and oxidative stress (OS) induced pre-osteoblast MC3T3-E1 cell injury model were treated with and without HT. Cell viability, apoptosis, differentiation, mitochondrial function along with mitogen-activated protein kinase (MAPK) signaling pathway were investigated. Meanwhile, the effect and related mechanisms of HT on bone loss in mice with periodontitis were also detected. HT inhibited osteoclast differentiation and prevented OS induced pre-osteoblast cells injury via regulating mitochondrial function as well as ERK and JNK signaling pathways. Moreover, HT attenuated the alveolar bone loss, increased bone forming activity, inhibited the osteoclasts differentiation and decreased the level of OS in mice with periodontitis. Our findings, for the first time, revealed a novel function of HT in bone remodeling of periodontitis, and highlighted its therapeutical potential for the prevention/treatment of periodontitis.

Total glycosides and polysaccharides of Cistanche deserticola prevent osteoporosis by activating Wnt/β-catenin signaling pathway in SAMP6 mice

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Cistanche deserticola Y. C. Ma has effect of "tonifying kidney and strengthening bone". However, the specific active extracts of C. deserticola and mechanisms for treatment of osteoporotic are not clear.

AIM OF THE STUDY

We wanted to identify the effective component extracts of C. deserticola for the treatment of osteoporosis and the potential mechanisms.

MATERIALS AND METHODS

Our group researched the extracts of C. deserticola with anti-osteoporotic activity, including total glycosides (TGs), polysaccharides (PSs), and oligosaccharides (OSs) in senescence accelerated mouse prone 6 (SAMP6) mice. The Goldner's Trichrome, Van Gieson's (VG), Safranin O-Fast Green staining and Von Kossa staining were performed to investigate the bone structure formation and calcium deposits. Serum was collected for detecting biochemical markers. Bone micro-architecture was detected by micro-CT. Expressions of bone morphogenetic protein-2 (BMP-2), osteocalcin (OCN), osteoprotegerin (OPG), receptor activator of nuclear factor-κ B ligand (RANKL), p-glycogen synthetase kinase-3β (p-GSK-3β), and p-β-catenin were analyzed by western blotting and immunohistochemistry.

RESULTS

TGs and PSs ameliorated bone histopathological damages, promoted the formation of new bone, collagenous fiber, and chondrocytes, and accelerated the calcium deposits. Moreover, they remarkable altered the biomarkers of bone turnover and effectively ameliorated bone microarchitecture. The further mechanisms study showed that TGs and PSs significantly decreased the expressions of RANKL, p-β-catenin, as well as up-regulated the expression of BMP-2, OCN, OPG, and p-GSK-3β (Ser9).

CONCLUSION

The findings of this study suggest that TGs and PSs can promote osteoblastogenic bone formation and improve bone microstructure damage in SAMP6 mice, and their therapeutic effect on osteoporosis is via activating Wnt/β-catenin signaling pathway.

Cistanches Herba, from an endangered species to a big brand of Chinese medicine

Cistanches Herba (CH, Chinese name: Roucongrong), is a very precious, tonic Chinese medicine. Cistanche deserticola and Cistanche tubulosa are the two commonly used species and authenticated in Chinese Pharmacopoeia. Due to the parasitic nature of Cistanche plants, the wild source was once endangered and listed in the Appendix II of Convention on International Trade in Endangered Species of Wild Fauna and Flora. However, after continuously struggling in the past decades, CH has grown up to a big brand of Chinese medicine featured with the cultivation area as 1.26 million mu, the annual output as 6000 tons, and the related industrial output value as more than 20 billion China Yuan, attributing to large-scale cultivation and in-depth phytochemical and pharmacological investigations. Noteworthily, great achievements have reached concerning the research and development of relevant products, such as modern drugs, traditional Chinese medicine prescriptions, and dietary supplements. The current review summarizes the research progresses concerning the distribution and cultivation, phytochemistry, pharmacology, metabolism and product development of CH in the past decades, and the emerging challenges and developing prospects are discussed as well.

A missense mutation sheds light on a novel structure-function relationship of RANKL

The tumor necrosis factor (TNF)-like core domain of receptor activator of nuclear factor-κB ligand (RANKL) is a functional domain critical for osteoclast differentiation. One of the missense mutations identified in patients with osteoclast-poor autosomal recessive osteopetrosis (ARO) is located in residue methionine 199 that is replaced with lysine (M199K) amid the TNF-like core domain. However, the structure-function relationship of this mutation is not clear. Sequence-based alignment revealed that the fragment containing human M199 is highly conserved and equivalent to M200 in rat. Using site-directed mutagenesis, we generated three recombinant RANKL mutants M200K/A/E (M200s) by replacing the methionine 200 with lysine (M200K), alanine (M200A), and glutamic acid (M200E), representative of distinct physical properties. TRAcP staining and bone pit assay showed that M200s failed to support osteoclast formation and bone resorption, accompanied by impaired osteoclast-related signal transduction. However, no antagonistic effect was found in M200s against wild-type rat RANKL. Analysis of the crystal structure of RANKL predicted that this methionine residue is located within the hydrophobic core of the protein, thus, likely to be crucial for protein folding and stability. Consistently, differential scanning fluorimetry analysis suggested that M200s were less stable. Western blot analysis analyses further revealed impaired RANKL trimerization by M200s. Furthermore, receptor-ligand binding assay displayed interrupted interaction of M200s to its intrinsic receptors. Collectively, our studies revealed the molecular basis of human M199-induced ARO and elucidated the indispensable role of rodent residue M200 (equivalent to human M199) for the RANKL function.

Cistanche deserticola polysaccharide induces melanogenesis in melanocytes and reduces oxidative stress via activating NRF2/HO-1 pathway

As a main part of pigmentation disorders, skin depigmentation diseases such as vitiligo and achromic naevus are very common and get more attention now. The pathogenesis of depigmentation includes melanocyte dysfunction and loss, which are possibly caused by heredity, autoimmunity and oxidative stress. Among them, oxidative stress plays a key role; however, few clinical treatments can deal with oxidative stress. As reported, Cistanche deserticola polysaccharide (CDP) is an effective antioxidant; based on that, we evaluated its role in melanocyte and further revealed the mechanisms. In this study, we found that CDP could promote melanogenesis in human epidermal melanocytes (HEMs) and mouse melanoma B16F10 cells, it also induced pigmentation in zebrafish. Furthermore, CDP could activate mitogen‐activated protein kinase (MAPK) signal pathway, then up‐regulated the expression of microphthalmia‐associated transcription factor (MITF) and downstream genes TYR, TRP1, TRP2 and RAB27A. Otherwise, we found that CDP could attenuate H₂O₂‐induced cytotoxicity and apoptosis in melanocytes. Further evidence revealed that CDP could enhance NRF2/HO‐1 antioxidant pathway and scavenge intracellular ROS. In summary, CDP can promote melanogenesis and prevent melanocytes from oxidative stress injury, suggesting that CDP helps maintain the normal status of melanocytes. Thus, CDP may be a novel drug for the treatment of depigmentation diseases.

C-phycocyanin attenuates RANKL-induced osteoclastogenesis and bone resorption in vitro through inhibiting ROS levels, NFATc1 and NF-κB activation

Excessive bone loss occurs in inflammatory disorders such as periodontitis and osteoporosis. The underlying mechanism is related to the differentiation of macrophages into multinucleated giant osteoclasts and their bone resorptive activity. C-Phycocyanin (C-PC) is a phycobiliprotein extracted from the blue-green algae, which has been shown to have various pharmacological effects. The role of C-PC on bone metabolism needs revelation. In this study, we determined the effectiveness of C-PC as an inhibitor of osteoclast differentiation, activity, and survival in vitro. We found that C-PC strongly inhibited the differentiation of macrophages to TRAP-positive osteoclasts, distinctive osteoclast specific podosomal organization, and dentine matrix resorption without any cytotoxicity. Also, it suppressed the expression of osteoclast specific markers, such as cathepsin K and integrin β3 at mRNA and protein levels. RANKL mediated signaling utilizes reactive oxygen species (ROS) for the differentiation of osteoclasts. C-PC attenuated RANKL stimulated ROS. Mechanistic studies indicate that C-PC has the potential to reduce osteoclast formation via blocking the degradation of cytosolic IκB-α and hence, the activation of downstream markers such as c-Fos and NFATc1. However, it does not have any effect on osteoblast-mediated bone formation in vitro. Collectively, our data suggest that C-PC may be utilized as a therapeutic agent that can target bone loss mediated by excessive osteoclastic bone resorption without affecting osteoblastic activity in bone.

Vinpocetine inhibits RANKL-induced osteoclastogenesis and attenuates ovariectomy-induced bone loss

Osteoporosis is a result of impaired bone formation and/or excessive bone resorption. Osteoclasts are the only cells in the body that have a bone resorption function. Inhibiting osteoclast activity and differentiation is a way to treat osteoporosis. The current pharmacological treatment for osteoporosis has many shortcomings, and more effective treatments are needed. Vinpocetine (Vinp), a derivative of the alkaloid vincamine, has been used to treat cerebrovascular disorders and cognitive impairment for a long time. Vinp inhibits mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB)-dependent inflammatory responses and oxidative damage in which osteoclasts are often involved. However, the effects of Vinp on the regulation of osteoclast activity remain unknown. In this study, we found that Vinp significantly inhibited receptor activator of NF-κB ligand (RANKL)-induced osteoclast and F-actin formation and decreased osteoclastic bone resorption in vitro. Vinp also suppressed the expression of osteoclast-specific genes, including NFATc1, c-Fos, tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-9 (MMP-9), and cathepsin K (CTSK) at both the mRNA and protein levels. Vinp reduced activation of NF-κB, MAPK, and AKT signaling during osteoclastogenesis and prevented the production of reactive oxygen species with increased nuclear factor erythroid 2-related factor 2, heme oxygenase 1, and NAD(P)H:quinone acceptor oxidoreductase 1 expression. Animal experiments consistently demonstrated that Vinp treatment significantly attenuated ovariectomy-induced bone loss with a decrease in the osteoclast number and decreases in serum levels of RANKL, TRAP, interleukin-1β, and tumor necrosis factor-alpha, as well as increased serum levels of osteoprotegerin. Taken together, our findings reveal that Vinp may be a potential pharmacological choice for preventing and treating osteoporosis.

Anti-Osteoporotic Activity of an Edible Traditional Chinese Medicine Cistanche deserticola on Bone Metabolism of Ovariectomized Rats Through RANKL/RANK/TRAF6-Mediated Signaling Pathways

Given the limitations of existing therapeutic agents for treatment of postmenopausal osteoporosis, there still remains a need for more options with both efficacy and less adverse effects. Cistanche deserticola Y. C. Ma is known as a popular tonic herb traditionally used to treatment deficiency of kidney energy including muscle weakness in minority area of Asian counties. Based on the theory of “kidney dominate bone,” an ovariectomized (OVX) rat model of postmenopausal osteoporosis was used to evaluate the therapeutic effect of C. deserticola extract (CDE) on bone loss. Forty eight female Sprague-Dawley rats, aged about 12 weeks, were randomly assigned into six groups including sham group orally administrated with 0.5% carboxymethyl cellulose sodium (CMC-Na) (sham), positive group treated with 1 mg/kg of estradiol valerate (EV), low, moderate, and high dosage groups orally administrated with 200, 400, and 800 mg/kg/day of CDE, respectively. After 3 months of continuous intervention, CDE exhibited significant anti-osteoporotic activity evidenced by the enhanced total bone mineral density, ameliorated bone microarchitecture; increased alkaline phosphatase activity; decreased deoxypyridinoline, cathepsin K, tartrate-resistant acid phosphatase, and malondialdehyde levels; whereas the body, uterus, and vagina weights in OVX rats were not influenced by CDE intervention. In addition, a seemed contradictory phenomenon on levels of calcium and phosphorus between OVX and sham rats were observed and elucidated. Mechanistically, CDE significantly down-regulated the levels of TRAF6, RANKL, RANK, NF-κB, IKKβ, NFAT2, and up-regulated the phosphatidylinositol 3-kinase (PI3K), AKT, osteoprotegerin, and c-Fos expressions, which implied CDE could suppress RANKL/RANK-induced activation of downstream NF-κB and PI3K/AKT pathways, and ultimately, preventing activity of the key osteoclastogenic proteins NFAT2 and c-Fos. All of the data suggested CDE possessed potential anti-osteoporotic activity and this effect was, at least in part, involved in modulation of RANKL/RANK/TRAF6-mediated NF-κB and PI3K/AKT signaling as well as c-Fos and NFAT2 levels. Therefore, CDE may represent a useful promising remedy candidate for treatment of postmenopausal osteoporosis.

Therapeutic Anabolic and Anticatabolic Benefits of Natural Chinese Medicines for the Treatment of Osteoporosis

Osteoporosis is a bone disease characterized by increasing osseous fragility and fracture due to the reduced bone mass and microstructural degradation. Primary pharmacological strategies for the treatment of osteoporosis, hormone replacement treatment (HRT), and alendronate therapies may produce adverse side-effects and may not be recommended for long-term usage. Some classic and bone-specific natural Chinese medicine are very popularly used to treat osteoporosis and bone fracture effectively in clinical with their potential value in bone growth and development, but with few adverse side-effects. Current evidence suggests that the treatments appear to improve bone metabolism and attenuate the osteoporotic imbalance between bone formation and bone resorption at a cellular level by promoting osteoblast activity and inhibiting the effects of osteoclasts. The valuable therapies might, therefore, provide an effective and safer alternative to primary pharmacological strategies. Therefore, the purpose of this article is to comprehensively review these classic and bone-specific drugs in natural Chinese medicines for the treatment of osteoporosis that had been deeply and definitely studied and reported with both bone formation and antiresorption effects, including Gynochthodes officinalis (F.C.How) Razafim. & B.Bremer (syn. Morinda officinalis F.C.How), Curculigo orchioides Gaertn., Psoralea corylifolia (L.) Medik Eucommia ulmoides Oliv., Dipsacus inermis Wall. (syn. Dipsacus asperoides C.Y.Cheng & T.M.Ai), Cibotium barometz (L.) J. Sm., Velvet Antler, Cistanche deserticola Ma, Cuscuta chinensis Lam., Cnidium monnieri (L.) Cusson, Epimedium brevicornum Maxim, Pueraria montana (Lour.) Merr. and Salvia miltiorrhiza Bunge., thus providing evidence for the potential use of alternative Chinese medicine therapies to effectively treat osteoporosis.

Diosmetin inhibits osteoclast formation and differentiation and prevents LPS-induced osteolysis in mice

Osteolytic bone diseases are closely linked to the over-activation of osteoclasts and enhancement of bone resorption. It has become a major health issue in orthopedic practice worldwide. Inhibition of osteoclasts is proposed to be the main treatment for osteolytic disorders. Diosmetin (DIO) is a natural flavonoid with properties of antioxidant, anti-infection, and antishock. The effect of DIO on osteoclast differentiation is poorly understood. In this study project, we found that DIO could inhibit osteoclastic formation induced by receptor activator of nuclear factor kappa-B ligand (RANKL) in a dose-dependent manner. The expression of the osteoclast differentiation marker genes, cathepsin K, nuclear factor of activated T-cells 1 (NFATc1), Acp5, Ctr, Atp6v0d2, and Mmp9 were also decreased by the treatment of DIO. In addition, DIO attenuated the formation of actin ring and the ability of bone resorption. Further, the western blotting showed that DIO inhibits the phosphorylation of the mitogen-activated protein kinases signaling pathway induced by RANKL, accompanied by the downregulation of NFATc1 and c-Fos expression. We also found that DIO could reduce the accumulation of reactive oxygen species (ROS) induced by RANKL. In vivo, the study revealed that DIO can significantly reduce LPS-induced osteolysis in mice. Collectively, our study shows that DIO can inhibit osteoclast formation and activation, and could serve as a potential therapeutic drug for osteolytic bone diseases.

Beneficial Effects of Total Phenylethanoid Glycoside Fraction Isolated from Cistanche deserticola on Bone Microstructure in Ovariectomized Rats

The present study was designed to estimate the antiosteoporotic activity of total phenylethanoid glycoside fraction isolated from C. deserticola (CDP) on rats induced by ovariectomy (OVX) as well as the related mechanisms. After 3 months of oral administration, the decreased bone mineral density, serum Ca, and P in OVX rats were recovered and the deteriorated trabecular bone microarchitecture was partly improved by CDP (60, 120, and 240 mg/kg) intervention, the activities of bone resorption markers were downregulated, and the bioactive of the bone formation index was upregulated; meanwhile, the content of MDA was declined, and GSH was increased by CDP treatment. Compositionally, 8 phenylethanoid glycoside compounds were identified in CDP, with the total contents quantified as 50.3% by using the HPLC method. Mechanistically, CDP declined the levels of TRAF6, RANKL, and RANK, thus suppressing RANKL/RANK/TRAF6-induced activation of downstream NF-κB and PI3K/AKT signaling pathways and ultimately preventing activities of the key osteoclastogenic proteins of NFAT2 and c-Fos. All of the above data implied that CDP exhibited beneficial effects on bone microstructure in ovariectomized rats, and these effects may be related to the NF-κB and PI3K/AKT signaling pathways which were triggered by the binding of RANKL, RANK, and TRAF6.

Protective Effect of Acteoside on Ovariectomy-Induced Bone Loss in Mice

Acteoside, an active phenylethanoid glycoside compound isolated from herbs of Cistanche, was chosen for the investigation of anti-osteoporotic effect on postmenopausal osteoporosis by using an ovariectomized (OVX) mice model. The results from in vivo experiments showed that after daily oral administration of acteoside (20, 40, and 80 mg/kg body weight/day) for 12 weeks, bone mineral density and bone biomechanical properties of OVX mice were greatly enhanced, with significant improvement in bone microarchitecture. Furthermore, biochemical parameters of bone resorption markers as well as bone formation index, including tartrate-resistant acid phosphatase, cathepsin K, deoxypyridinoline, alkaline phosphatase, and bone gla-protein, were ameliorated by acteoside treatment, whereas the body, uterus, and vagina wet weights were seemingly not impacted by acteoside administration. Acteoside significantly affected osteoclastogenesis by attenuating nuclear factor kappa B (NF-κB) and stimulating phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signal pathways through down-regulated levels of tumor-necrosis factor receptor-associated factor 6 (TRAF6), receptor activator of nuclear factor kappa B ligand (RANKL), RANK, NFKBIA, IκB kinase β, nuclear factor of activated T-cells c2 (NFAT2), and up-regulated expressions of PI3K, AKT, and c-Fos. Accordingly, the current research validated our hypothesis that acteoside possesses potent anti-osteoporotic properties and may be a promising agent for the prevention of osteoporosis in the future.

Chlorogenic acid promotes the Nrf2/HO-1 anti-oxidative pathway by activating p21Waf1/Cip1 to resist dexamethasone-induced apoptosis in osteoblastic cells

In a previous study, p21^Waf1/Cip1 (p21) promoted activation of the nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway, which has an important role in regulating apoptosis triggered by oxidative stress and inhibiting development of osteoporosis. Chlorogenic acid (CGA) has a strong protective effect on osteoporosis, closely related to activating the Nrf2/HO-1 pathway. However, whether CGA can resist apoptosis by regulating p21 and consequently promote activation of the Nrf2/HO-1 pathway needs further investigation. MC3T3-E1 cells were treated with dexamethasone (Dex), with or without CGA pre-treatment. Cell proliferation and cytotoxicity were measured using MTT assay and LDH release assay, respectively, and apoptosis assessed by flow cytometry. CGA significantly attenuated mitochondrial apoptosis and reversed down-regulation of p21 in osteoblastic MC3T3-E1 cells exposed to Dex. Additionally, CGA decreased Keap1 expression and promoted activation of the Nrf2/HO-1 pathway, quenching intracellular reactive oxygen species (ROS), hydrogen peroxide (H₂O₂) and mitochondrial superoxide overproduction boosted by Dex. Importantly, depletion of p21 by siRNA blocked activation of the Nrf2/HO-1 pathway, enhanced oxidative stress and increased apoptosis induced by CGA in MC3T3-E1 cells challenged with Dex. Therefore, CGA promoted the Nrf2/HO-1 anti-oxidative pathway by activating p21 to prevent Dex-induced mitochondrial apoptosis in osteoblastic cells. This pathway has potential as a therapeutic target for prevention and treatment of osteoporosis.

Pseurotin A Inhibits Osteoclastogenesis and Prevents Ovariectomized-Induced Bone Loss by Suppressing Reactive Oxygen Species

Rationale: Growing evidence indicates that intracellular reactive oxygen species (ROS) accumulation is a critical factor in the development of osteoporosis by triggering osteoclast formation and function. Pseurotin A (Pse) is a secondary metabolite isolated from Aspergillus fumigatus with antioxidant properties, recently shown to exhibit a wide range of potential therapeutic applications. However, its effects on osteoporosis remain unknown. This study aimed to explore whether Pse, by suppressing ROS level, is able to inhibit osteoclastogenesis and prevent the bone loss induced by estrogen-deficiency in ovariectomized (OVX) mice.

Methods: The effects of Pse on receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis and bone resorptive function were examined by tartrate resistant acid phosphatase (TRAcP) staining and hydroxyapatite resorption assay. 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) was used to detect intracellular ROS production in vitro. Western blot assay was used to identify proteins associated with ROS generation and scavenging as well as ROS-mediated signaling cascades including mitogen-activated protein kinases (MAPKs), NF-κB pathways, and nuclear factor of activated T cells 1 (NFATc1) signaling. The expression of osteoclast-specific genes was assessed by qPCR. The in vivo potential of Pse was determined using an OVX mouse model administered with Pse or vehicle for 6 weeks. In vivo ROS production was assessed by intravenous injection of dihydroethidium (DHE) into OVX mice 24h prior to killing. After sacrifice, the bone samples were analyzed using micro-CT and histomorphometry to determine bone volume, osteoclast activity, and ROS level ex vivo.

Results: Pse was demonstrated to inhibit osteoclastogenesis and bone resorptive function in vitro, as well as the downregulation of osteoclast-specific genes including Acp5 (encoding TRAcP), Ctsk (encoding cathepsin K), and Mmp9 (encoding matrix metalloproteinase 9). Mechanistically, Pse suppressed intracellular ROS level by inhibiting RANKL-induced ROS production and enhancing ROS scavenging enzymes, subsequently suppressing MAPK pathway (ERK, P38, and JNK) and NF-κB pathways, leading to the inhibition of NFATc1 signaling. Micro-CT and histological data indicated that OVX procedure resulted in a significant bone loss, with dramatically increased the number of osteoclasts on the bone surface as well as increased ROS level in the bone marrow microenvironment; whereas Pse supplementation was capable of effectively preventing these OVX-induced changes.

Conclusion: Pse was demonstrated for the first time as a novel alternative therapy for osteoclast-related bone diseases such as osteoporosis through suppressing ROS level.

Impacts of Psychological Stress on Osteoporosis: Clinical Implications and Treatment Interactions

The significant biochemical and physiological effects of psychological stress are beginning to be recognized as exacerbating common diseases, including osteoporosis. This review discusses the current evidence for psychological stress-associated mental health disorders as risk factors for osteoporosis, the mechanisms that may link these conditions, and potential implications for treatment. Traditional, alternative, and adjunctive therapies are discussed. This review is not intended to provide therapeutic recommendations, but, rather, the goal of this review is to delineate potential interactions of psychological stress and osteoporosis and to highlight potential multi-system implications of pharmacological interventions. Review of the current literature identifies several potentially overlapping mechanistic pathways that may be of interest (e.g., glucocorticoid signaling, insulin-like growth factor signaling, serotonin signaling) for further basic and clinical research. Current literature also supports the potential for cross-effects of therapeutics for osteoporosis and mental health disorders. While studies examining a direct link between osteoporosis and chronic psychological stress are limited, the studies reviewed herein suggest that a multi-factorial, personalized approach should be considered for improved patient outcomes in populations experiencing psychological stress, particularly those at high-risk for development of osteoporosis.