Recent advance of small-molecule drugs for clinical treatment of osteoporosis: A review

Qing'e Pills Ameliorates Osteoporosis by Regulating Gut Microbiota and Th17/Treg Balance in Ovariectomized Rats

Purpose

Bone metabolism disorders are strongly associated with T helper type 17/regulatory T (Th17/Treg) cell imbalance and inflammatory dysregulation. Qing'e pills (QEP) is a classical prescription for treating osteoporosis with both safety and clinical effectiveness. However, the mechanism of its immune action remains unclear.

Methods

QEP components were identified via HPLC. Anti-osteoporotic effects of QEP were assessed through biochemical, micro computed tomography, bone biomechanical and histopathological analyses. Th17/Treg balance and related inflammatory factors were analyzed using flow cytometric, biochemical, immunohistochemical, and quantitative real-time PCR assays. The effects of QEP on gut microbiota and endogenous metabolites were analyzed via 16S rRNA analysis, co-incubation experiments and untargeted metabolomics. Integrative correlations analysis was used to explore the relationships among gut-bone-Th17/Treg balance interactions.

Results

QEP improved bone mineral density and bone biomechanical properties and reduced bone conversion in ovariectomized rats. After treatment, QEP restored intestinal barrier integrity, and reduced serum LPS levels. QEP significantly decreased Th17-related inflammatory cytokines TNF-α, IL-17 levels, reduced the transcription of Th17-related genes RORγt and IL-17A and the percentage of CD4+IL-17A+ Th17 cells in the gut-bone axis, and concurrently restored the anti-inflammatory cytokines levels of TGF-β and IL-10, the expression of Foxp3 and the percentage of CD4+ CD25+ Foxp3+ Treg cells in the gut-bone axis. Notably, QEP improved the disorganization of gut microbiota composition and structure in ovariectomized rats. On genus level, QEP can significantly increase the relative abundance of Lactobacillus in vitro and in vivo. Furthermore, gut microbe-derived endogenous metabolites potentially mediating QEP's regulation of Th17/Treg balance in gut-bone axis and anti-osteoporotic effects.

Conclusion

QEP ameliorates osteoporosis by improving the intestinal flora disorders and immune status, and restoring the balance of Th17/Treg in the gut-bone axis, highlighting its clinical potential in the treatment of postmenopausal osteoporosis.

Re-engineering bone: pathogenesis, diagnosis and emerging therapies for osteoporosis

Osteoporosis, a multifaceted metabolic bone disease, is becoming increasingly prevalent and poses a significant burden on global healthcare systems. Given the limitations of traditional treatments such as pharmacotherapy, tissue engineering has emerged as a promising alternative for osteoporosis management. This review begins by exploring the pathogenesis of osteoporosis, with a focus on the abnormal metabolic, cellular, and molecular signalling microenvironments that drive the disease. We also examine commonly used clinical diagnostic techniques, discussing their strengths and limitations. Notably, this review evaluates various advanced tissue engineering strategies for osteoporosis treatment. Delivery systems, including injectable hydrogels and nanomaterials, are detailed alongside bone tissue engineering materials such as bioactive ceramics, bone cements, and polymers. Additionally, biologically active substances, including exosomes and cytokines, and emerging therapies that leverage small-molecule drugs are explored. Through a comprehensive analysis of the advantages and limitations of current biomaterials and therapeutic approaches, this review provides insights into future directions for tissue engineering-based solutions. By synthesizing current advancements, it aims to inspire innovative perspectives for the clinical management of osteoporosis.

Pathophysiology of bone remodelling cycle: Role of immune system and lipids

Osteoporosis is the most common skeletal disease worldwide, characterized by low bone mineral density, resulting in weaker bones, and an increased risk of fragility fractures. The maintenance of bone mass relies on the precise balance between bone synthesis and resorption. The close relationship between the immune and skeletal systems, called "osteoimmunology", was coined to identify these overlapping "scientific worlds", and its function resides in the evaluation of the mutual effects of the skeletal and immune systems at the molecular and cellular levels, in both physiological and pathological states. Lipids play an essential role in skeletal metabolism and bone health. Indeed, bone marrow and its skeletal components demand a dramatic amount of daily energy to control hematopoietic turnover, acquire and maintain bone mass, and actively being involved in whole-body metabolism. Statins, the main therapeutic agents in lowering plasma cholesterol levels, are able to promote osteoblastogenesis and inhibit osteoclastogenesis. This review is meant to provide an updated overview of the pathophysiology of bone remodelling cycle, focusing on the interplay between bone, immune system and lipids. Novel therapeutic strategies for the management of osteoporosis are also discussed.

Injectable Hydrogel Technologies for Bone Disease Treatment

Injectable hydrogels represent a highly promising approach for localized drug delivery systems (DDSs) in the management of bone-related conditions such as osteoporosis, osteonecrosis, osteoarthritis, osteomyelitis, and osteosarcoma. Their appeal lies in their biocompatibility, adjustable mechanical properties, and capacity to respond to external stimuli, including pH, temperature, light, redox potential, ionic strength, and enzymatic activity. These features enable enhanced targeted delivery of bioactive agents. This mini-review evaluates the synthesis of injectable hydrogels as well as recent advancements for treating a range of bone disorders, focusing on their mechanisms as localized and sustained DDSs for delivering drugs, nanoparticles, growth factors, and cells (e.g., stem cells). Moreover, it highlights their clinical studies for bone disease treatment. Additionally, it emphasizes the potential synergy between injectable hydrogels and hydrogel-based point-of-care technologies, which are anticipated to play a pivotal role in the future of bone disease therapies. Injectable hydrogels have the potential to transform bone disease treatment by facilitating precise, sustained, and minimally invasive therapeutic delivery. Nevertheless, significant challenges, including long-term biocompatibility, scalability, reproducibility, and precise regulation of drug release kinetics, must be addressed to unlock their clinical potential fully. Addressing these challenges will not only advance bone disease therapy but also open new avenues in regenerative medicine and personalized healthcare.

The absence of IRG1 exacerbates bone loss in a mouse model of ovariectomy-induced osteoporosis by increasing osteoclastogenesis through the potentiation of NLRP3 inflammasome activation

The immune-responsive gene 1 (IRG1) protein plays a role in various pathological processes by connecting cellular metabolism to a range of cellular activities through the production of itaconate. Recent studies have highlighted the significance of IRG1 and itaconate in bone metabolism and homeostasis. However, the precise role of IRG1 in osteoporosis remains inadequately documented. This study aimed to determine the role of IRG1 in osteoporosis through the utilization of IRG1 knockout (KO) mice and a model of ovariectomy (OVX)-induced osteoporosis. The expression of IRG1 was found to be higher in the bone tissues of postmenopausal osteoporotic mice induced by OVX in comparison to sham control mice. When compared to wild type (WT) mice, OVX-induced bone loss was significantly worse in IRG1 KO mice, and this was accompanied by an increase in osteoclastogenesis and bone resorption. However, the loss of bone and the process of osteoclastogenesis and bone resorption were effectively reversed when the IRG1 KO mice were replenished with itaconate. The osteoclastogenesis induced by receptor activator of nuclear factor kappa-Β ligand (RANKL) in bone marrow-derived macrophages (BMMs) was found to be enhanced by IRG1 deficiency, which could be reversed through the replenishment of itaconate. Further investigation revealed that IRG1 deficiency potentiated the activation of NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. The inhibition of NLRP3 inflammasome using a targeted inhibitor significantly ameliorated RANKL-induced osteoclastogenesis in IRG1 KO BMMs. Overall, this study highlights the significance of IRG1 in regulating osteoclastogenesis and proposes it as a potential target for osteoporosis treatment.

Anthocyanins from a new hybrid sweet potato peel cultivated in Northern Thailand mitigate LPS-induced inflammation and RANKL-induced osteoporosis by regulating ROS-mediated pathways

Maejo 341 Sweet potato (MSP) is a new purple sweet potato variety cultivated in Northern Thailand, but its health benefits are unknown. This study aimed to investigate its antioxidant, anti-inflammatory, and anti-osteoporotic activities, as well as its anthocyanin content. The peel and flesh of MSP were extracted with ethanol and water. Compared with the flesh extracts, the peel extracts presented greater antioxidant capacity and were rich in phenolics, flavonoids, and anthocyanins, namely, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, pelargonidin-3-O-glucoside, cyanidin, and peonidin. The peel extracts suppressed lipopolysaccharide-induced inflammation by inhibiting the secretion of proinflammatory cytokines and enzymes, including TNF-α, IL-1β, IL-6, COX-2, and iNOS, as well as reducing nitric oxide and matrix metalloproteinase-9 secretion. The extracts inhibited the RANKL-induced NF-κB and MAPK pathways and downregulated osteoclastogenic marker expression. Under LPS and RANKL treatment, the peel extracts notably reduced reactive oxygen species production while increasing antioxidant gene expression. Furthermore, they increased osteoblast viability and slightly raise alkaline phosphatase activity. These findings suggest that MSP peel could be used as a functional food to alleviate oxidative stress and inflammation-related osteoporosis.

Biomaterial Cues for Regulation of Osteoclast Differentiation and Function in Bone Regeneration

Tissue regeneration involves dynamic dialogue between and among different cells and their surrounding matrices. Bone regeneration is specifically governed by reciprocity between osteoblasts and osteoclasts within the bone microenvironment. Osteoclast-directed resorption and osteoblast-directed formation of bone are essential to bone remodeling, and the crosstalk between these cells is vital to curating a sequence of events that culminate in the creation of bone tissue. Among bone biomaterial strategies, many have investigated the use of different material cues to direct the development and activity of osteoblasts. However, less attention has been given to exploring features that similarly target osteoclast formation and activity, with even fewer strategies demonstrating or integrating biomaterial-directed modulation of osteoblast-osteoclast coupling. This review aims to describe various biomaterial cues demonstrated to influence osteoclastogenesis and osteoclast function, emphasizing those that enhance a material construct's ability to achieve bone healing and regeneration. Additionally discussed are approaches that influence the communication between osteoclasts and osteoblasts, particularly in a manner that takes advantage of their coupling. Deepening our understanding of how biomaterial cues may dictate osteoclast differentiation, function, and influence on the microenvironment may enable the realization of bone-replacement interventions with enhanced integrative and regenerative capacities.

Gut-bone axis perturbation: Mechanisms and interventions via gut microbiota as a primary driver of osteoporosis

A growing number of studies have highlighted the significance of human gut microbiota (GM) as a potential target for osteoporosis. In this review, we discuss the effect of GM to bone metabolism focusing on two aspects: the local alterations of the human gut permeability that modify how the GM interact with the gut-bone axis (e.g., intestinal leakage, nutrient absorption), and the alterations of the GM itself (e.g., changes in microbiota metabolites, immune secretion, hormones) that modify the events of the gut-bone axis. We then classify these changes as possible therapeutic targets of bone metabolism and highlight some associated promising microbiome-based therapies. We also extend our discussions into combinatorial treatments that incorporate conservative treatments, such as exercise. We anticipate our review can provide an overview of the current pathophysiological and therapeutic paradigms of the gut-bone axis, as well as the prospects of ongoing clinical trials for readers to gain further insights into better microbiome-based treatments to osteoporosis and other bone-degenerative diseases. The translational potential of this article: This paper reviewed the potential links between gut microbiota and osteoporosis, as well as the prospective therapeutic avenues targeting gut microbiota for osteoporosis management, presenting a thorough and comprehensive literature review.

Pharmacology and mechanisms of apigenin in preventing osteoporosis

Osteoporosis (OP) stands as the most prevalent systemic skeletal condition associated with aging. The current clinical management of OP predominantly depends on anti-resorptive and anabolic agents. Nevertheless, prolonged use of some of these medications has been observed to reduce efficacy and elevate adverse effects. Given the necessity for sustained or even lifelong treatment of OP, the identification of drugs that are not only effective but also safe and cost-efficient is of utmost significance. As disease treatment paradigms continue to evolve and recent advancements in OP research come to light, certain plant-derived compounds have emerged, presenting notable benefits in the management of OP. This review primarily explores the pharmacological properties of apigenin and elucidates its therapeutic mechanisms in the context of OP. The insights provided herein aspire to offer a foundation for the judicious use of apigenin in forthcoming research, particularly within the scope of OP.

Efficacy of combination therapy of vitamin D and bisphosphonates in the treatment of postmenopausal osteoporosis: a systematic review and meta-analysis

Objective

There is currently no consensus on whether the combination therapy of Vitamin D (VitD) and bisphosphonates offers superior efficacy compared to monotherapy in the treatment of postmenopausal osteoporosis. The aim of this study is to conduct a meta-analysis of recent relevant research to synthesize the available evidence and further investigate whether the combined use of VitD and bisphosphonates is superior to monotherapy in treating osteoporosis in postmenopausal women.

Methods and results

We systematically searched PubMed, EMBASE, the Cochrane Library, and Web of Science for randomized controlled trials (RCTs) comparing the effects of monotherapy with VitD or bisphosphonates versus their combination therapy in the treatment of postmenopausal osteoporosis, up to 1 February 2024. The articles were independently screened and relevant data were extracted by two investigators. The changes in mean values and percentage changes for bone resorption markers, bone formation markers, bone mineral density, and bone mineral metabolism markers were expressed using the standardized mean difference (SMD) and 95% confidence intervals (CI). Heterogeneity was quantitatively described using the I2 test. Subsequently, sensitivity analyses were performed for data with significant heterogeneity. Subgroup analyses were conducted based on the type of monotherapy used, and potential publication bias was assessed. The analysis revealed that the combination of VitD and bisphosphonates demonstrated a more pronounced effect in increasing alkaline phosphatase (ALP), 25-hydroxyvitamin D (25-OH-VD), and serum calcium (sCa) levels, as well as in decreasing levels of serum bone-specific alkaline phosphatase (sBALP), serum C-terminal telopeptide of type I collagen (sCTX), and urinary N-telopeptide of type I collagen (UriNTX) compared to the monotherapy group. However, the combination of VitD and bisphosphonates did not show a significant advantage over monotherapy in terms of improving osteocalcin levels. The differences in the mean changes in osteocalcin, UriNTX, and sCa, as well as the percentage changes in parathyroid hormone (PTH) were not statistically significant (p > 0.05).

Conclusion

The meta-analysis suggests that compared to monotherapy, the combination therapy of VitD and bisphosphonates exhibits a more favorable effect on bone mineral density and bone calcium metabolism-related markers in the treatment of postmenopausal osteoporosis.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/PROSPERO.

Estrogen and estrogen receptors mediate the mechanobiology of bone disease and repair

It is well understood that the balance of bone formation and resorption is dependent on both mechanical and biochemical factors. In addition to cell-secreted cytokines and growth factors, sex hormones like estrogen are critical to maintaining bone health. Although the direct osteoprotective function of estrogen and estrogen receptors (ERs) has been reported extensively, evidence that estrogen signaling also has a role in mediating the effects of mechanical loading on maintenance of bone mass and healing of bone injuries has more recently emerged. Recent studies have underscored the role of estrogen and ERs in many pathways of bone mechanosensation and mechanotransduction. Estrogen and ERs have been shown to augment integrin-based mechanotransduction as well as canonical Wnt/b-catenin, RhoA/ROCK, and YAP/TAZ pathways. Estrogen and ERs also influence the mechanosensitivity of not only osteocytes but also osteoblasts, osteoclasts, and marrow stromal cells. The current review will highlight these roles of estrogen and ERs in cellular mechanisms underlying bone mechanobiology and discuss their implications for management of osteoporosis and bone fractures. A greater understanding of the mechanisms behind interactions between estrogen and mechanical loading may be crucial to addressing the shortcomings of current hormonal and pharmaceutical therapies. A combined therapy approach including high-impact exercise therapy may mitigate adverse side effects and allow an effective long-term solution for the prevention, treatment, and management of bone fragility in at-risk populations. Furthermore, future implications to novel local delivery mechanisms of hormonal therapy for osteoporosis treatment, as well as the effects on bone health of applications of sex hormone therapy outside of bone disease, will be discussed.

Synthesis and Antiosteoporotic Characterization of Diselenyl Maleimides: Discovery of a Potent Agent for the Treatment of Osteoporosis by Targeting RANKL

To discover new osteoclast-targeting antiosteoporosis agents, we identified forty-six diselenyl maleimides, which were efficiently prepared using a novel, simple, and metal-free method at room temperature in a short reaction time. Among them, 3k showed the most marked inhibition of osteoclast differentiation with an IC50 value of 0.36 ± 0.03 μM. Moreover, 3k significantly suppressed RANKL-induced osteoclast formation, bone resorption, and osteoclast-specific genes expression in vitro. Mechanistic studies revealed that 3k remarkably blocked the RANKL-induced mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways. In ovariectomized mice, intragastric administration of 3k significantly alleviated bone loss, exhibiting an effect similar to that of alendronate. Surface plasmon resonance assay and microscale thermophoresis assay results suggested that RANKL might be a potential molecular target for 3k. Collectively, the findings presented above provided a novel candidate for further development of bone antiresorptive drugs that target RANKL.

Inhibition of Mettl3 ameliorates osteoblastic senescence by mitigating m6A modifications on Slc1a5 via Igf2bp2-dependent mechanisms

Age-related osteoporosis is characterized by a marked decrease in the number of osteoblasts, which has been partly attributed to the senescence of cells of the osteoblastic lineage. Epigenetic studies have provided new insights into the mechanisms of current osteoporosis treatments and bone repair pathophysiology. N6-methyladenosine (m6A) is a novel transcript modification that plays a major role in cellular senescence and is essential for skeletal development and internal environmental stability. Bioinformatics analysis revealed that the expression of the m6A reading protein Igf2bp2 was significantly higher in osteoporosis patients. However, the role of Igf2bp2 in osteoblast senescence has not been elucidated. In this study, we found that Igf2bp2 levels are increased in ageing osteoblasts induced by multiple repetition and H2O2. Increasing Igf2bp2 expression promotes osteoblast senescence by increasing the stability of Slc1a5 mRNA and inhibiting cell cycle progression. Additionally, Mettl3 was identified as Slc1a5 m6A-methylated protein with increased m6A modification. The knockdown of Mettl3 in osteoblasts inhibits the reduction of senescence, whereas the overexpression of Mettl3 promotes the senescence of osteoblasts. We found that administering Cpd-564, a specific inhibitor of Mettl3, induced increased bone mass and decreased bone marrow fat accumulation in aged rats. Notably, in an OVX rat model, Igf2bp2 small interfering RNA delivery also induced an increase in bone mass and decreased fat accumulation in the bone marrow. In conclusion, our study demonstrated that the Mettl3/Igf2bp2-Slc1a5 axis plays a key role in the promotion of osteoblast senescence and age-related bone loss.

Mechanism of action of Sambucus williamsii Hance var. miquelii in the treatment of osteoporosis analyzed by UHPLC-HRMS/MS combined network pharmacology and experimental validation

Sambucus williamsii Hance var. miquelii(SWH) is a precious wild Chinese herb whose fruit, rhizome, leaves and root bark can be used as medicine. Sambucus Linn has pharmacological effects such as anti-osteoporosis, promoting fracture healing, anti-viral and anti-inflammatory. In this study, the main chemical components of the alcoholic extracts from SWH were rapidly identified by ultra-high performance liquid chromatography-quadrupole orbit trap high-resolution mass spectrometry (UHPLC- HRMS MS), and a total of 42 compounds were characterized from the alcoholic extracts of SWH. The results of network pharmacological validation showed that kaempferol, quercetin, luteolin, isorhamnetin and morroniside were the main active components, and KEGG enrichment demonstrated that SWH mainly affected the signaling pathways such as PI3K-Akt, TNF and FoxO by modulating the related targets such as AKT1, PIK3R1, EGFR, RELA SRC and PTGS2. The molecular docking results showed binding solid activity between the main active components of SWH and the targets. The network pharmacology was validated by establishing an animal model of osteoporosis (OP) in rats by gavage administration of vitamin A acid. The results of the pharmacological experiments showed that SWH could improve the degree of bone loss in the femur of osteoporotic rats, increase the number of trabeculae and decrease trabeculae porosity, up-regulate the Ca and P content in the serum of OP rats, down-regulate the scope of ALP and BGP in the serum, and promote the calcification of the bone matrix, and then exert the anti-OP efficacy. In this study, network pharmacology and pharmacological experiments verified the pharmacological mechanism of SWH in anti-OP rats. This provides a theoretical basis for the research and development of anti-OP drugs and a reference for the application of other traditional Chinese medicines in treating OP diseases.

Attenuating bone loss in osteoporosis: the potential of corylin (CL) as a therapeutic agent

The global prevalence of osteoporosis is being exacerbated by the increasing number of aging societies and longer life expectancies. In response, numerous drugs have been developed in recent years to mitigate bone resorption and enhance bone density. Nonetheless, the efficacy and safety of these pharmaceutical interventions remain constrained. Corylin (CL), a naturally occurring compound derived from the anti-osteoporosis plant Psoralea corylifolia L., has exhibited promising potential in impeding osteoclast differentiation. This study aims to evaluate the effect and molecular mechanisms of CL regulating osteoclast differentiation in vitro and its potential as a therapeutic agent for osteoporosis treatment in vivo. Our investigation revealed that CL effectively inhibits osteoclast formation and their bone resorption capacity by downregulating the transcription factors NFATc1 and c-fos, consequently resulting in the downregulation of genes associated with bone resorption. Furthermore, it has been observed that CL can effectively mitigate the migration and fusion of pre-osteoclast, while also attenuating the activation of mitochondrial mass and function. The results obtained from an in vivo study have demonstrated that CL is capable of attenuating the bone loss induced by ovariectomy (OVX). Based on these significant findings, it is proposed that CL exhibits considerable potential as a novel drug strategy for inhibiting osteoclast differentiation, thereby offering a promising approach for the treatment of osteoporosis.

Exosomal circFAM63Bsuppresses bone regeneration of postmenopausal osteoporosis via regulating miR-578/HMGA2 axis

Postmenopausal osteoporosis (PMOP) affects hundreds of millions of elderly women worldwide. The imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption is the key factor in the progression of PMOP. Recently, exosomal circular RNAs have been considered as critical regulators in physiological and pathological progress. However, their roles in PMOP still require further exploration. Herein, we identified that the expression of exosomal circFAM63B significantly increased in PMOP patients and is closely related to bone density. We further demonstrated that circFAM63B inhibits osteogenic differentiation of bone marrow stromal cells and bone formation in ovariectomy mice by using a combination of in vitro and in vivo experiment strategies. Mechanistically, circFAM63B promotes HMGA2 expression by inhibiting miR-578, thereby suppressing bone repair. Our study proved that exosomal circFAM63B suppresses the bone regeneration of PMOP by regulating the miR-578/HMGA2 axis, which may provide new insights into the pathogenesis and development of PMOP. Knocking down exosomal circFAM63B could be regarded as a new strategy for the treatment of PMOP.

Design, Synthesis, and Biological Evaluation of β-Trifluoroethoxydimethyl Selenides as Potent Antiosteoporosis Agents

An efficient protocol for the synthesis of β-trifluoroethoxydimethyl selenides was achieved under mild reaction conditions, and 39 compounds were prepared. All compounds were evaluated for their abilities to inhibit RANKL-induced osteoclastogenesis, compound 4aa exhibited the most potent activity. Further investigations revealed that 4aa could inhibit F-actin ring generation, bone resorption, and osteoclast-specific gene expression in vitro. Western blot analyses demonstrated that compound 4aa abrogated the RANKL-induced mitogen-activated protein kinase and NF-kB-signaling pathways. In addition, 4aa also displayed a notable impact on the osteoblastogenesis of MC3T3-E1 preosteoblasts. In vivo experiments revealed that compound 4aa significantly ameliorated bone loss in an ovariectomized (OVX) mice model. Furthermore, the surface plasmon resonance experiment results revealed that 4aa probably bound to RANKL. Collectively, the above-mentioned findings suggested that compound 4aa as a potential RANKL inhibitor averted OVX-triggered osteoporosis by regulating the inhibition of osteoclast differentiation and stimulation of osteoblast differentiation.

Bone and Extracellular Signal-Related Kinase 5 (ERK5)

Bones are vital for anchoring muscles, tendons, and ligaments, serving as a fundamental element of the human skeletal structure. However, our understanding of bone development mechanisms and the maintenance of bone homeostasis is still limited. Extracellular signal-related kinase 5 (ERK5), a recently identified member of the mitogen-activated protein kinase (MAPK) family, plays a critical role in the pathogenesis and progression of various diseases, especially neoplasms. Recent studies have highlighted ERK5's significant role in both bone development and bone-associated pathologies. This review offers a detailed examination of the latest research on ERK5 in different tissues and diseases, with a particular focus on its implications for bone health. It also examines therapeutic strategies and future research avenues targeting ERK5.

Research Progress on the Mechanism of the SFRP-Mediated Wnt Signalling Pathway Involved in Bone Metabolism in Osteoporosis

Osteoporosis (OP) is a metabolic bone disease linked to an elevated fracture risk, primarily stemming from disruptions in bone metabolism. Present clinical treatments for OP merely alleviate symptoms. Hence, there exists a pressing need to identify novel targets for the clinical treatment of OP. Research indicates that the Wnt signalling pathway is modulated by serum-secreted frizzled-related protein 5 (SFRP5), potentially serving as a pivotal regulator in bone metabolism disorders. Moreover, studies confirm elevated SFRP5 expression in OP, with SFRP5 overexpression leading to the downregulation of Wnt and β-catenin proteins in the Wnt signalling pathway, as well as the expression of osteogenesis-related marker molecules such as RUNX2, ALP, and OPN. Conversely, the opposite has been reported when SFRP5 is knocked out, suggesting that SFRP5 may be a key factor involved in the regulation of bone metabolism via the Wnt signalling axis. However, the molecular mechanisms underlying the action of SFRP5-induced OP have yet to be comprehensively elucidated. This review focusses on the molecular structure and function of SFRP5 and the potential molecular mechanisms of the SFRP5-mediated Wnt signalling pathway involved in bone metabolism in OP, providing reasonable evidence for the targeted therapy of SFRP5 for the prevention and treatment of OP.

Metabolomics and pharmacodynamic analysis unveil the therapeutic role of icaritin on osteoporosis rats

Osteoporosis is a systemic metabolic bone disease characterized by a reduction in bone mass resulting from multifactorial causes. Icaritin (ICT), a flavonoid glycoside, exhibits a multitude of effects on bone tissue. To examine the influence of ICT on bone trabecular loss in vivo, ovariectomized (OVX) rats were utilized. The ability of ICT to mitigate bone trabecular loss and the underlying anti-osteoporotic pathways were assessed using ovariectomy-induced osteoporosis rats. Furthermore, we gain insights into the osteoprotective mechanisms of ICT on osteoporosis by conducting UPLC-Orbitrap-MS-based metabolomics of rat urine. The results of experiments demonstrated a significant attenuation of bone trabecular loss, as well as improvements in biochemical indices, biomechanical parameters, and microstructure in the ICT administered group compared to the OVX group. Moreover, metabolomics results suggested that the ICT treatment adjusted 33 different metabolites, which associated with the metabolism of amino acids, lipids, and energy. The findings suggest that the anti-osteoporosis effect of ICT may be related to the activation of PI3K/AKT signal and the inhibition of TLR4 pathway regulated by metabonomics. These results contribute to a better understanding of the therapeutic potential of ICT in the treatment of osteoporosis.

Unveiling the potential of Butylphthalide: inhibiting osteoclastogenesis and preventing bone loss

Osteoporosis, resulting from overactive osteoclasts and leading to elevated fracture risk, has emerged as a global public health concern due to the aging population. Therefore, inhibiting osteoclastogenesis and bone resorption function represents a crucial approach for preventing and treating osteoporosis. The purpose of this study was to examine the effects and molecular mechanisms of Butylphthalide (NBP) on the differentiation and function of osteoclasts induced by RANKL. Osteoclastogenesis was assessed through TRAP staining and bone slice assay. An animal model that underwent ovariectomy, simulating postmenopausal women's physiological characteristics, was established to investigate the impact of Butylphthalide on ovariectomy-induced bone loss. To delve deeper into the specific mechanisms, we employed Western blot, PCR, immunofluorescence, and immunohistochemical staining to detect the expression of proteins that are associated with the osteoclast signaling pathway. In this study, we found that Butylphthalide not only suppressed osteoclastogenesis and bone resorption in vitro but also significantly decreased TRAcP-positive osteoclasts and prevented bone loss in vivo. Further mechanistic experiments revealed that Butylphthalide reduces intracellular ROS in osteoclasts, inhibits the MAPK and NFATc1 signaling pathways, and downregulates the key genes and proteins of osteoclasts. This inhibits osteoclast formation and function. The reduction in ROS in osteoclasts is intricately linked to the activity of Butylphthalide-modulated antioxidant enzymes. Overall, NBP may offer a alternative treatment option with fewer side effects for skeletal diseases such as osteoporosis.

Lactobacillus plantarum attenuates glucocorticoid-induced osteoporosis by altering the composition of rat gut microbiota and serum metabolic profile

Introduction

Osteoporosis, one of the most common non-communicable human diseases worldwide, is one of the most prevalent disease of the adult skeleton. Glucocorticoid-induced osteoporosis(GIOP) is the foremost form of secondary osteoporosis, extensively researched due to its prevalence.Probiotics constitute a primary bioactive component within numerous foods, offering promise as a potential biological intervention for preventing and treating osteoporosis. This study aimed to evaluate the beneficial effects of the probiotic Lactobacillus plantarum on bone health and its underlying mechanisms in a rat model of glucocorticoid dexamethasone-induced osteoporosis, using the osteoporosis treatment drug alendronate as a reference.

Methods

We examined the bone microstructure (Micro-CT and HE staining) and analyzed the gut microbiome and serum metabolome in rats.

Results and discussion

The results revealed that L. plantarum treatment significantly restored parameters of bone microstructure, with elevated bone density, increased number and thickness of trabeculae, and decreased Tb.Sp. Gut microbiota sequencing results showed that probiotic treatment increased gut microbial diversity and the ratio of Firmicutes to Bacteroidota decreased. Beneficial bacteria abundance was significantly increased (Lachnospiraceae_NK4A136_group, Ruminococcus, UCG_005, Romboutsia, and Christensenellaceae_R_7_group), and harmful bacteria abundance was significantly decreased (Desulfovibrionaceae). According to the results of serum metabolomics, significant changes in serum metabolites occurred in different groups. These differential metabolites were predominantly enriched within the pathways of Pentose and Glucuronate Interconversions, as well as Propanoate Metabolism. Furthermore, treatment of L. plantarum significantly increased serum levels of Pyrazine and gamma-Glutamylcysteine, which were associated with inhibition of osteoclast formation and promoting osteoblast formation. Lactobacillus plantarum can protect rats from DEX-induced GIOP by mediating the "gut microbial-bone axis" promoting the production of beneficial bacteria and metabolites. Therefore L. plantarum is a potential candidate for the treatment of GIOP.