Research Progress of Ferroptosis Regulatory Network and Bone Remodeling in Osteoporosis

Bioinformatics-Based Analysis of Ferroptosis-Related Biomarkers and the Prediction of Drugs Affecting the Adipogenic Differentiation of MSCs

Background: The imbalance between the osteogenic and adipogenic differentiation of mesenchymal stem cells (MSCs) is a key factor in the progression of osteoporosis; therefore, it is crucial to study the regulatory mechanisms that maintain this balance. Ferroptosis is a form of regulated cell death caused by the accumulation of lipid peroxides and is closely associated with various diseases. Changes in intracellular oxidative stress levels can affect the lineage allocation of MSCs. However, it remains unclear whether the disruption of intracellular oxidative stress levels caused by ferroptosis can influence the osteogenic-adipogenic differentiation balance of MSCs, and the mechanism underlying this influence in osteoporosis has not been fully elucidated. This study is the first to demonstrate through in vitro cell experiments that inhibiting ferroptosis can decrease the adipogenic differentiation of MSCs. Methods and Results: Through bioinformatics analysis, differentially expressed genes (DEGs) associated with the adipogenic differentiation of MSCs were identified from the GEO database. We then intersected these differentially expressed genes with a ferroptosis-related gene dataset and identified 118 ferroptosis-related differentially expressed genes (FRDEGs). Additionally, we explored the functional roles of FRDEGs through GO and KEGG analyses and found that these genes significantly impacted intracellular oxidative stress. Furthermore, we identified 10 key FRDEGs via protein-protein interaction (PPI) analysis. The diagnostic performance of these genes was evaluated by plotting receiver operating characteristic (ROC) curves, and the reliability of the diagmodel was validated using data from osteoporosis patients. We then constructed a mouse osteoporosis model and validated the mRNA expression levels of key FRDEGs via qRT-PCR, which revealed significant differences in expression in the osteoporosis group. Finally, molecular docking technology was used to identify two small molecules from the DrugBank database that are able to negatively regulate MSC adipogenic differentiation by inhibiting ferroptosis. Conclusions: The identified FRDEGs and small molecules offer novel diagnostic markers and therapeutic candidates for osteoporosis.

Novel insights into the role of ferroptosis in temporomandibular joint osteoarthritis and knee osteoarthritis

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by pain, limited movement, and joint stiffness, significantly impacting the quality of life and imposing substantial economic burdens. This review paper delves into the novel insights of ferroptosis, an iron-dependent form of cell death associated with lipid peroxidation, in the context of temporomandibular joint osteoarthritis (TMJ OA) and knee osteoarthritis (KOA). We explore the pathogenic characteristics of OA, including synovitis, chondrocyte death, and extracellular matrix (ECM) degradation, and discuss the limitations of current therapeutic interventions. Emerging evidence suggests a significant relationship between ferroptosis and OA, with iron accumulation and lipid peroxidation observed in osteoarthritic cartilage. This review highlights the role of ferroptosis in chondrocyte malfunction and apoptosis, inflammation, and extracellular matrix breakdown, which are central to OA pathogenesis. We also discuss potential therapeutic targets, such as Transient Receptor Potential Vanilloid 1 (TRPV1), Glutathione Peroxidase 4 (GPX4), and Nuclear Factor Erythroid 2-Related Factor 2 (NRF2), which modulate ferroptosis and OA progression. The paper consolidates studies on ferroptosis in OA, offering a comprehensive understanding of its role and the development of innovative therapies targeting this cell death mechanism to improve treatment outcomes for OA patients.

Argatroban and Menadione exert protective effects in ultraviolet-irradiated skin inflammation: A transcriptomic analysis based on identification of iron overload related biomarkers

Ultraviolet light (UV) can cause serious damage to human skin. The inflammatory reaction arising from repeated UV exposure leads to severe skin lesions and even promotes photo-carcinogenesis. Iron overload is featured by excessive iron intake and deposition and will promote inflammatory response inside cells. However, the core molecules involved in UV radiation induced iron overload and related anti-inflammatory strategies remain unclear. Signature genes involved in UV-irradiated skin were filtered through integrated datasets from the Gene Expression Omnibus (GEO) database. Subsequently, immune cell infiltration analysis was carried out to examine the relationship between signature gene expression and immune cell abundance. Single cell RNA-seq matrix data implicated in UV-irradiated skin was then applied to assess the expression level of signature genes in different cell clusters and to find out the core cell type and the key signaling pathway involved in UV radiation. Finally, cytological and animal experiments were conducted to investigate the potential of signature genes as therapeutic targets. SAT1 and RBMS1 were screened and validated as signature genes of UV irradiation. Immune cell infiltration analysis demonstrated that SAT1 and RBMS1 expression were associated closely with immune cell abundance, and skin fibroblasts were identified as the central cell type to communicate with other cell clusters in UV-irradiated skin. Disturbance of SAT1 exerted observably more suppressive effects on the release of inflammatory cytokines than overexpression of RBMS1. Two small molecule drugs targeting SAT1, namely Argatroban and Menadione, were predicted. Moreover, their therapeutic potentials in the treatment of UV-irradiated skin injury were confirmed experimentally.

From death to birth: how osteocyte death promotes osteoclast formation

Bone remodeling is a dynamic and continuous process involving three components: bone formation mediated by osteoblasts, bone resorption mediated by osteoclasts, and bone formation-resorption balancing regulated by osteocytes. Excessive osteocyte death is found in various bone diseases, such as postmenopausal osteoporosis (PMOP), and osteoclasts are found increased and activated at osteocyte death sites. Currently, apart from apoptosis and necrosis as previously established, more forms of cell death are reported, including necroptosis, ferroptosis and pyroptosis. These forms of cell death play important role in the development of inflammatory diseases and bone diseases. Increasing studies have revealed that various forms of osteocyte death promote osteoclast formation via different mechanism, including actively secreting pro-inflammatory and pro-osteoclastogenic cytokines, such as tumor necrosis factor alpha (TNF-α) and receptor activator of nuclear factor-kappa B ligand (RANKL), or passively releasing pro-inflammatory damage associated molecule patterns (DAMPs), such as high mobility group box 1 (HMGB1). This review summarizes the established and potential mechanisms by which various forms of osteocyte death regulate osteoclast formation, aiming to provide better understanding of bone disease development and therapeutic target.

BMP9 alleviates iron accumulation-induced osteoporosis via the USP10/FOXO1/GPX4 axis

INTRODUCTION

Ferroptosis induced by iron accumulation can disrupt the physiological functions of bone marrow mesenchymal stem cells (BMSCs). BMP9 is an effective osteogenic factor. However, the role of BMP9 and its molecular mechanisms in osteoporosis induced by iron accumulation remain unclear.

OBJECTIVES

This study aims to explore the role and mechanism of BMP9 in alleviating iron accumulation induced osteoporosis.

METHODS

Clinical samples were collected to analyze the relationship between iron accumulation and osteoporosis. The effect of BMP9 on lipid peroxidation levels in BMSCs under iron accumulation conditions was assessed using C11-BODIPY staining, MitoSOX staining, MDA and SOD activity measurement. The osteogenic capacity of BMP9 in BMSCs under iron accumulation conditions was evaluated by measuring ALP activity and calcium nodule formation. The mechanisms of BMP9 in regulating BMSCs under iron accumulation conditions were explored through experiments including cycloheximide treatment, RT-PCR, Western blot, GST pull-down, ChIP, and CO-IP.

RESULTS

It was observed in human samples that serum ferritin levels were negatively correlated with the bone mineral density of the lumbar spine and femoral neck. Meanwhile, ferroptosis is considered a key factor affecting bone health. Further research indicated that BMP9 could inhibit ferroptosis in cells and animal models with iron accumulation, while also improving oxidative stress and osteogenic capacity. In-depth investigation of its mechanism reveals that BMP9 promotes the expression of USP10, which removes the K48-linked ubiquitin chains on FOXO1, inhibiting its excessive ubiquitination in the cytoplasm. This stabilization allows FOXO1 to accumulate in the cytoplasm and eventually re-enter the nucleus. This process activated the expression of the key inhibitor of cell death, GPX4, enhancing the cell's antioxidant response, reducing ferroptosis-induced damage to BMSCs, and promoting their osteogenic differentiation.

CONCLUSION

This study reveals that BMP9 inhibits ferroptosis through the USP10/FOXO1/GPX4 axis, providing a new therapeutic strategy for osteoporosis caused by iron accumulation.

The GPR30-Mediated BMP-6/HEP/FPN Signaling Pathway Inhibits Ferroptosis in Bone Marrow Mesenchymal Stem Cells to Alleviate Osteoporosis

Dysregulated iron metabolism-induced ferroptosis is considered a key pathological mechanism in the development of osteoporosis (OP). G protein-coupled receptor 30 (GPR30, also known as Gper1) is an estrogen-binding receptor that has shown therapeutic benefits in patients with certain degenerative diseases. Moreover, several studies have demonstrated the anti-ferroptotic effects of estrogen receptor activation. However, its role in the prevention and treatment of OP remains unclear, and there are currently no reports on the anti-ferroptotic function of GPR30 in OP. Therefore, this study aimed to investigate the ferroptosis-related effects and mechanisms of GPR30 in the context of OP. In vivo and in vitro experiments were conducted using wild-type (WT) C57BL/6 female mice and GPR30-knockout (GPR30-KO) C57BL/6J female mice. The microarchitecture of the distal femur was assessed using micro-computed tomography (micro-CT), and histomorphological changes were analyzed via hematoxylin and eosin (H&E) staining. Bone marrow mesenchymal stem cells (BMSCs) were isolated and cultured to establish an iron overload model using ferric ammonium citrate (FAC). Interventions included GPR30 overexpression via transfection and BMP-6 inhibition using LDN-214117. Cell viability was evaluated with the CCK-8 assay, while osteogenic differentiation and mineralization levels were assessed using ALP and Alizarin Red S (ARS) staining. Iron accumulation was detected via Prussian blue staining, oxidative stress levels were evaluated using ROS staining, and mitochondrial membrane potential changes were analyzed using JC-1 staining. Transmission electron microscopy (TEM) was employed to observe mitochondrial ultrastructural changes. Additionally, key gene and protein expression levels were measured using immunofluorescence and Western blotting. The micro-CT analysis revealed significant bone microarchitecture deterioration and bone loss in the GPR30-KO mouse model. At the cellular level, GPR30 overexpression markedly reduced iron accumulation and oxidative stress in BMSCs, restored the mitochondrial membrane potential, and improved the mitochondrial ultrastructure. Furthermore, GPR30 enhanced osteogenic differentiation in BMSCs by promoting the activation of the BMP-6/HEP/FPN signaling pathway, leading to increased expression of osteogenic markers. The protective effects of GPR30 were reversed by the BMP-6 inhibitor LDN-214117, indicating that BMP-6 is a critical mediator in GPR30-regulated iron metabolism and ferroptosis inhibition. GPR30 inhibits ferroptosis in BMSCs and enhances osteogenic differentiation by activating the BMP-6/HEP/FPN signaling pathway. This provides new insights and potential therapeutic targets for the treatment of osteoporosis OP.

Natural Products in the Prevention of Degenerative Bone and Joint Diseases: Mechanisms Based on the Regulation of Ferroptosis

Degenerative bone and joint diseases (DBJDs), characterized by osteoporosis, osteoarthritis, and chronic inflammation of surrounding soft tissues, are systemic conditions primarily affecting the skeletal system. Ferroptosis, a programmed cell death pathway distinct from apoptosis, autophagy, and necroptosis. Accumulating evidence suggests that ferroptosis is intricately linked to the pathogenesis of DBJDs, and targeting its regulation could be beneficial in managing these conditions. Natural products, known for their anti-inflammatory and antioxidant properties, have shown unique advantages in preventing DBJDs, potentially through modulating ferroptosis. This article provides an overview of the latest research on ferroptosis, with a focus on its role in the pathogenesis of DBJDs and the therapeutic potential of natural products targeting this cell death pathway, offering novel insights for the prevention and treatment of DBJDs.

[Ferroptosis-related genes in osteoporosis: a bioinformatics analysis and in vitro study]

OBJECTIVES

To explore ferroptosis-related genes in osteoporosis through bioinformatic analysis and in vitro study.

METHODS

Osteoporosis-related genes were identified from dataset GSE35958 in the Gene Expression Omnibus database; and the ferroptosis-related genes were identified from the FerrDb database. These were intersected with the differentially expressed genes in GSE35958 to obtain ferroptosis-related genes in osteoporosis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed for the differentially expressed genes. And Spearman correlation and protein-protein interaction network analysis were performed. Then, the hub genes of ferroptosis in osteoporosis were screened by Degree, MNC, EPC, MCC and DMNC in Cytoscape software CytoHubba plugin; and analyzed with receiver operating characteristic (ROC) curves. The bone marrow mesenchymal stem cells from osteoporosis patients (osteoporosis group) and non-osteoporosis patients (control group) were subjected to quantitative reverse transcription polymerase chain reaction to detect the messenger RNA expression of ferroptosis hub genes in both groups.

RESULTS

A total of 32 differentially expressed genes related to ferroptosis in osteoporosis were identified, including 26 up-regulated genes and 6 down-regulated genes. GO enrichment analysis showed that the identified genes were mainly involved in intercellular adhesion, lipid metabolism and cytokine response. KEGG enrichment analysis showed that the genes were mainly involved in signaling pathways of adhesive plaques, MAPK, PI3K-Akt, and Wnt. Spearman correlation analysis showed correlation among differentially expressed genes. Six hub genes for ferroptosis in osteoporosis were obtained, namely MAPK3, CDKN1A, MAP1LC3A, TNF, RELA, and TGF-β1. ROC curve analysis showed that these hub genes had good diagnostic performance in osteoporosis and may become potential biomarkers of osteoporosis. In vitro experiments confirmed significant differences in these hub genes between the control group and the osteoporosis group (all P<0.05).

CONCLUSIONS

This study has identified six ferroptosis-related hub genes in osteoporosis, which may be used as novel biomarkers for the early diagnosis and treatment of osteoporosis.

Integrative bioinformatics and experimental analysis of curcumin's role in regulating ferroptosis to combat osteoporosis

This study utilized bioinformatics and data mining techniques to explore the molecular mechanism of curcumin in treating osteoporosis (OP) through the lens of ferroptosis, thereby identifying novel therapeutic targets. The datasets GSE35958, GSE35956, GSE7429, and GSE7158 were obtained from the Gene Expression Omnibus (GEO) database. GSE35958 and GSE35956 were employed as training sets for data integration, while GSE7429 and GSE7158 served as independent validation sets. Through retrieval from the FerrDb database, iron death-related genes (FRGs) were identified, and the differentially expressed genes (DEGs) were intersected to obtain differentially expressed FRGs (DEFRGs). Subsequently, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted, followed by the construction of a Protein-Protein Interaction (PPI) network to identify Hub genes. The DGIdb database was utilized to predict candidate drugs associated with the Hub genes, and molecular docking and in vitro experiments confirmed that curcumin targets the Hub genes EGFR and PTGS2.Through in vitro testing of curcumin on BMSC cells, researchers examined cell vitality, iron death, osteogenic differentiation, mineralization, and the impact on EGFR and PTGS2 levels. The analysis yielded 2212 DEGs, 484 FRGs, with 45 FDEGs at the intersection. GO analysis revealed involvement in regulating mitochondrial proteins, amino acid transport across plasma membranes, and protein ubiquitination. KEGG pathway analysis indicated associations with iron death, FoxO signaling, mTOR signaling, cell aging, osteoclast differentiation, and GSH metabolism. Utilizing the MCC algorithm, five Hub genes were identified: MAPK3, PTGS2, TGFB1, CYBB, and EGFR, showing diagnostic potential for iron death. Curcumin displayed affinity for EGFR and PTGS2, mitigating iron-induced effects on BMSCs such as increased reactive oxygen species, Fe3+ levels, and decreased mitochondrial membrane potential. Furthermore, curcumin reversed these effects, suggesting EGFR and PTGS2 as targets for curcumin to inhibit BMSC ferroptosis and potentially delay osteoporosis development. Maintaining iron homeostasis and targeting BMSC ferroptosis could offer therapeutic avenues for iron overload-induced osteoporosis.

Irisin in degenerative musculoskeletal diseases: Functions in system and potential in therapy

Degenerative musculoskeletal diseases are a class of diseases related to the gradual structural and functional deterioration of muscles, joints, and bones, including osteoarthritis (OA), osteoporosis (OP), sarcopenia (SP), and intervertebral disc degeneration (IDD). As the proportion of aging people around the world increases, degenerative musculoskeletal diseases not only have a multifaceted impact on patients, but also impose a huge burden on the medical industry in various countries. Therefore, it is crucial to find key regulatory factors and potential therapeutic targets. Recent studies have shown that irisin plays an important role in degenerative musculoskeletal diseases, suggesting that it may become a key molecule in the prevention and treatment of degenerative diseases of the musculoskeletal system. Therefore, this review provides a comprehensive description of the release and basic functions of irisin, and summarizes the role of irisin in OA, OP, SP, and IDD from a cellular and tissue perspective, providing comprehensive basis for clinical application. In addition, we summarized the many roles of irisin as a key information molecule in bone-muscle-adipose crosstalk and a regulatory molecule involved in inflammation, senescence, and cell death, and proposed the interesting possibility of irisin in degenerative musculoskeletal diseases.

Ferroptosis and its implications in bone-related diseases

Ferroptosis, a recently recognized form of regulated cell death (RCD) characterized by iron-dependent lipid peroxide accumulation, has emerged as a noteworthy regulator in various bone-related diseases, including osteoporosis (OP), osteoarthritis (OA), and osteosarcoma (OS). OS primarily afflicts the elderly, rendering them susceptible to fractures due to increased bone fragility. OA represents the most prevalent arthritis in the world, often observed in the aging population. OS predominantly manifests during adolescence, exhibiting an aggressive nature and bearing a significantly unfavorable prognosis. In this review article, we present an overview of the characteristics and mechanism of ferroptosis and its involvement in bone-related diseases, with a particular focus on OP, OA, and OS. Furthermore, we summarize chemical compounds or biological factors that impact bone-related diseases by regulating ferroptosis. Through an in-depth exploration of ferroptosis based on current research findings, this review provides promising insights for potential therapeutic approaches to effectively manage and mitigate the impact of these bone-related pathological conditions.

Synergistic anti-osteoporosis effects of Anemarrhena asphodeloides bunge-Phellodendron chinense C.K. Schneid herb pair via ferroptosis suppression in ovariectomized mice

Introduction

Ferroptosis plays a crucial role in the progression of postmenopausal osteoporosis. Anemarrhena asphodeloides Bunge/Phellodendron chinense C.K. Schneid (AA/PC) is the core herb pair in traditional Chinese medicines formulae for postmenopausal osteoporosis treatment. However, the synergistic effects, and mechanisms, of AA/PC on alleviating ferroptosis and postmenopausal osteoporosis remain unclear.

Methods

The goal herein was to analyze the effective ingredients and molecular mechanisms of AA/PC in the treatment of osteoporosis through serum pharmacochemistry, network pharmacology, metabolomics analysis, and pharmacodynamics evaluation. A bilateral ovariectomized (OVX) mouse model was established.

Results and Discussion

Micron-scale computed tomography analysis showed that AA/PC increased bone mineral density in OVX mice. The effects of AA/PC were better than AA or PC alone on inhibiting the bone resorption marker nuclear factor of activated T-cells 1. Furthermore, five absorbable compounds were detected in serum: mangiferin, magnoflorine, berberine, timosaponin BIII, and timosaponin AIII. Network pharmacology showed these compounds had close relationship with seven ferroptosis targets. Importantly, compared with AA or PC alone, the AA/PC herb pair exerted better effects on regulating crucial ferroptosis pathways, including the system xc-/glutathione/glutathione peroxidase 4, transferrin receptor/ferritin, and acyl-CoA synthetase long chain family member 4/polyunsaturated fatty acids signaling pathways. These results indicate that AA/PC exerts synergistic effects on regulating glutathione synthesis, iron homeostasis, and lipid metabolism in ferroptosis. This work lays the foundation for further development and use of AA/PC herb pair for preventing and treating postmenopausal osteoporosis.

Ferroptosis: Regulatory mechanisms and potential targets for bone metabolism: A review

Bone homeostasis is a homeostasis process constructed by osteoblast bone formation and osteoclast bone resorption. Bone homeostasis imbalance and dysfunction are the basis for the development of various orthopedic diseases such as osteoporosis, osteoarthritis, and steroid-induced avascular necrosis of femoral head. Previous studies have demonstrated that ferroptosis can induce lipid peroxidation through the generation of reactive oxygen species, activate a number of signaling pathways, and participate in the regulation of osteoblast bone formation and osteoclast bone resorption, resulting in bone homeostasis imbalance, which is an important factor in the pathogenesis of many orthopedic diseases, but the mechanism of ferroptosis is still unknown. In recent years, it has been found that, in addition to iron metabolism and intracellular antioxidant system imbalance, organelle dysfunction is also a key factor affecting ferroptosis. This paper takes this as the starting point, reviews the latest literature reports at home and abroad, elaborates the pathogenesis and regulatory pathways of ferroptosis and the relationship between ferroptosis and various organelles, and summarizes the mechanism by which ferroptosis mediates bone homeostasis imbalance, with the aim of providing new directions for the research related to ferroptosis and new ideas for the prevention and treatment of bone and joint diseases.

Botulinum toxin A attenuates osteoarthritis development via inhibiting chondrocyte ferroptosis through SLC7Al1/GPX4 axis

Osteoarthritis (OA) is a prevalent joint degenerative disease, resulting in a significant societal burden. However, there is currently a lack of effective treatment option available. Previous studies have suggested that Botulinum toxin A (BONT/A), a macromolecular protein extracted from Clostridium Botulinum, may improve the pain and joint function in OA patients, but the mechanism remains elusive. This study was to investigate the impact and potential mechanism of BONT/A on OA in vivo and in vitro experiment. LPS increased the levels of ROS, Fe2+and Fe3+, as well as decreased GSH levels, the ratio of GSH / GSSH and mitochondrial membrane potential. It also enhanced the degeneration of extracellular matrix (ECM) and altered the ferroptosis-related protein expression in chondrocytes. BONT/A rescued LPS-induced decrease in collagen type II (Collagen II) expression and increase in matrix metalloproteinase 13 (MMP13), mitigated LPS-induced cytotoxicity in chondrocytes, abolished the accumulation of ROS and iron, upregulated GSH and the ratio of GSH/ GSSH, improved mitochondrial function, and promoted SLC7A11/GPX4 anti-ferroptosis system activation. Additionally, intra-articular injection of BONT/A inhibited the degradation of cartilage in OA model rats. This chondroprotective effect of BONT/A was reversed by erastin (a classical ferroptosis agonist) and enhanced by liproxstatin-1 (a classic ferroptosis inhibitor). Our research confirms that BONT/A alleviates the OA development by inhibiting the ferroptosis of chondrocytes, which revealed to be a potential therapeutic mechanism for BONT/A treating the OA.

Quercetin in Osteoporosis Treatment: A Comprehensive Review of Its Mechanisms and Therapeutic Potential

PURPOSE OF REVIEW

This review aims to provide a theoretical basis and insights for quercetin's clinical application in the prevention and treatment of osteoporosis (OP), analyzing its roles in bone formation promotion, bone resorption inhibition, anti-inflammation, antioxidant effects, and potential mechanisms.

RECENT FINDINGS

OP, a prevalent bone disorder, is marked by reduced bone mineral density and impaired bone architecture, elevating the risk of fractures in patients. The primary approach to OP management is pharmacotherapy, with quercetin, a phytochemical compound, emerging as a focus of recent interest. This natural flavonoid exerts regulatory effects on bone marrow mesenchymal stem cells, osteoblasts, and osteoclasts and promotes bone health and metabolic equilibrium via anti-inflammatory and antioxidative pathways. Although quercetin has demonstrated significant potential in regulating bone metabolism, there is a need for further high-quality clinical studies focused on medicinal quercetin.

Effects of the ferroptosis inducer erastin on osteogenic differentiation and biological pathways of primary osteoblasts

BACKGROUND

Periodontitis is a chronic destructive inflammatory disease exacerbated by osteoblast dysfunction. Ferroptosis has emerged as a significant factor that could contribute to the pathological changes observed in periodontitis. However, the impact of ferroptosis on osteogenic differentiation and gene expression patterns of primary osteoblasts remain elusive.

METHODS

In this study, osteoblasts were osteogenically induced for specific durations with and without the ferroptosis inducer erastin. Subsequently, cell proliferation, ferroptosis-related molecules, and osteogenic differentiation capacity were assessed. Furthermore, the differences in transcriptome expression following erastin treatment were analyzed by RNA sequencing.

RESULTS

The results demonstrated that erastin treatment induced ferroptosis, resulting in suppressed cell proliferation and impaired osteogenic differentiation. Transcriptomic analysis revealed significant alterations in processes such as hydrogen peroxide catabolism, response to lipid peroxidation, and metal iron binding, as well as BMP receptor activity and collagen type XI trimer.

CONCLUSION

The ferroptosis inducer erastin inhibited osteoblast proliferation and differentiation. Our study provides novel insights into the effect of ferroptosis on osteogenesis, suggesting that targeting ferroptosis may present a promising approach in the treatment of periodontitis.

Ferroptosis in Osteocytes as a Target for Protection Against Postmenopausal Osteoporosis

Ferroptosis is a necrotic form of iron-dependent regulatory cell death. Estrogen withdrawal can interfere with iron metabolism, which is responsible for the pathogenesis of postmenopausal osteoporosis (PMOP). Here, it is demonstrated that estrogen withdrawal induces iron accumulation in the skeleton and the ferroptosis of osteocytes, leading to reduced bone mineral density. Furthermore, the facilitatory effect of ferroptosis of osteocytes is verified in the occurrence and development of postmenopausal osteoporosis is associated with over activated osteoclastogenesis using a direct osteocyte/osteoclast coculture system and glutathione peroxidase 4 (GPX4) knockout ovariectomized mice. In addition, the nuclear factor erythroid derived 2-related factor-2 (Nrf2) signaling pathway is confirmed to be a crucial factor in the ferroptosis of osteocytic cells. Nrf2 regulates the expression of nuclear factor kappa-B ligand (RANKL) by regulating the DNA methylation level of the RANKL promoter mediated by DNA methyltransferase 3a (Dnmt3a), which is as an important mechanism in osteocytic ferroptosis-mediated osteoclastogenesis. Taken together, this data suggests that osteocytic ferroptosis is involved in PMOP and can be targeted to tune bone homeostasis.

New Emerging Aspect of Herbal Extracts for the Treatment of Osteoporosis: Overview

As the global population ages, osteoporosis is becoming a more common silent disease. Osteoporosis is characterized by decreased bone quality and strength, which increases the risk of fragility fractures in the elderly. According to estimates, 50% of women eventually suffer from an osteoporotic fracture. Due to increasing disability, more frequent hospital hospitalizations, and most critically, fragility fractures have been linked to a reduced quality of life. Osteoporotic fractures have been linked to an increased mortality risk; and must be considered in awareness as a serious health concern. There are anti-osteoporotic medications available that improve bone quality. Considering the availability of various treatment options, still there are a lot of underserved needs in the treatment of fractures and osteoporosis. For example, the application of natural products and herbal resources for fracture healing, because of the androgen-like and antioxidant characteristics of the plants, they can play a crucial for accelerating the repair of bone fractures. In this article, we'll discuss the herbal remedies that are essential for treating osteoporosis (bone disease).

New insight of the pathogenesis in osteoarthritis: the intricate interplay of ferroptosis and autophagy mediated by mitophagy/chaperone-mediated autophagy

Ferroptosis, characterized by iron accumulation and lipid peroxidation, is a form of iron-driven cell death. Mitophagy is a type of selective autophagy, where degradation of damaged mitochondria is the key mechanism for maintaining mitochondrial homeostasis. Additionally, Chaperone-mediated autophagy (CMA) is a biological process that transports individual cytoplasmic proteins to lysosomes for degradation through companion molecules such as heat shock proteins. Research has demonstrated the involvement of ferroptosis, mitophagy, and CMA in the pathological progression of Osteoarthritis (OA). Furthermore, research has indicated a significant correlation between alterations in the expression of reactive oxygen species (ROS), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and hypoxia-inducible factors (HIFs) and the occurrence of OA, particularly in relation to ferroptosis and mitophagy. In light of these findings, our study aims to assess the regulatory functions of ferroptosis and mitophagy/CMA in the pathogenesis of OA. Additionally, we propose a mechanism of crosstalk between ferroptosis and mitophagy, while also examining potential pharmacological interventions for targeted therapy in OA. Ultimately, our research endeavors to offer novel insights and directions for the prevention and treatment of OA.

Ferroptosis of macrophages facilitates bone loss in apical periodontitis via NRF2/FSP1/ROS pathway

Apical periodontitis (AP) is an infectious disease that causes periapical tissue inflammation and bone destruction. Ferroptosis, a novel type of regulated cell death, is closely associated with inflammatory diseases and the regulation of bone homeostasis. However, the exact involvement of ferroptosis in the bone loss of AP is not fully understood. In this study, human periapical tissues were collected, and a mouse model was established to investigate the role of ferroptosis in AP. Colocalization staining revealed that ferroptosis in macrophages contributes to the inflammatory bone loss associated with AP. A cell model was constructed using RAW 264.7 cells stimulated with LPS to further explore the mechanism underlying ferroptosis in macrophages upon inflammatory conditions, which exhibited ferroptotic characteristics. Moreover, downregulation of NRF2 was observed in ferroptotic macrophages, while overexpression of NRF2 upregulated the level of FSP1, leading to a reduction in reactive oxygen species (ROS) in macrophages. Additionally, ferroptotic macrophages released TNF-α, which activated the p38 MAPK signaling pathway and further increased ROS accumulation in macrophages. In vitro co-culture experiments demonstrated that the osteogenic ability of mouse bone marrow stromal cells (BMSCs) was suppressed with the stimulation of TNF-α from ferroptotic macrophages. These findings suggest that the TNF-α autocrine-paracrine loop in ferroptotic macrophages can inhibit osteogenesis in BMSCs through the NRF2/FSP1/ROS signaling pathway, leading to bone loss in AP. This study highlights the potential therapeutic value of targeting ferroptosis in the treatment of inflammatory bone diseases.

Dietary iron intake and its impact on osteopenia/osteoporosis

BACKGROUND

Osteoporosis is a prevalent condition characterized by low bone density and increased risk of fractures, resulting in a significant healthcare burden. Previous research has suggested that serum ferritin levels may be related to the risk of developing osteoporosis. The aim of this study was to investigate the relationship between dietary iron intake and the development of osteoporosis.

METHODS

Using data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2018, a total of 11,690 adults aged over 20 were evaluated. Bone mineral density (BMD) measurements of the femoral neck and lumbar spine were used to assess osteoporosis and osteopenia. Dietary iron intake was determined using food intake interviews and the Food and Nutrient Database for Dietary Studies. Logistic regression models were applied to investigate the association between dietary iron consumption and osteopenia and osteoporosis.

RESULTS

After adjusting for sociodemographic factors, compared with those who had the first quartile (Q1) of dietary iron intake, the odds ratio (OR) for osteopenia across the quartiles of dietary iron intake levels was 0.88 (95%CI: 0.79-0.98), 0.80 (95%CI: 0.72-0.89), and 0.74 (95%CI: 0.67-0.83) for Q2, Q3, and Q4, respectively. And the OR for osteoporosis across the quartiles of dietary iron intake levels was 1.00, 0.77 (95%CI: 0.50-1.19), 0.54 (95%CI: 0.34-0.89), and 0.83 (95%CI: 0.54-1.29) for Q1, Q2, Q3, and Q4, respectively. Notably, the observed association was significant among females but not males.

CONCLUSION

The risk of osteopenia/osteoporosis in females decreases with a moderate increase in dietary iron consumption. For females to preserve bone health, moderately increasing their dietary iron intake without overindulging should be seen as a key approach. Our study provides useful insights for developing dietary strategies to prevent and manage osteoporosis in vulnerable populations.

The Road from AKI to CKD: Molecular Mechanisms and Therapeutic Targets of Ferroptosis

Acute kidney injury (AKI) is a prevalent pathological condition that is characterized by a precipitous decline in renal function. In recent years, a growing body of studies have demonstrated that renal maladaptation following AKI results in chronic kidney disease (CKD). Therefore, targeting the transition of AKI to CKD displays excellent therapeutic potential. However, the mechanism of AKI to CKD is mediated by multifactor, and there is still a lack of effective treatments. Ferroptosis, a novel nonapoptotic form of cell death, is believed to have a role in the AKI to CKD progression. In this study, we retrospectively examined the history and characteristics of ferroptosis, summarized ferroptosis's research progress in AKI and CKD, and discussed how ferroptosis participates in regulating the pathological mechanism in the progression of AKI to CKD. Furthermore, we highlighted the limitations of present research and projected the future evolution of ferroptosis. We hope this work will provide clues for further studies of ferroptosis in AKI to CKD and contribute to the study of effective therapeutic targets to prevent the progression of kidney diseases.

PCDH7 as the key gene related to the co-occurrence of sarcopenia and osteoporosis

Sarcopenia and osteoporosis, two degenerative diseases in older patients, have become severe health problems in aging societies. Muscles and bones, the most important components of the motor system, are derived from mesodermal and ectodermal mesenchymal stem cells. The adjacent anatomical relationship between them provides the basic conditions for mechanical and chemical signals, which may contribute to the co-occurrence of sarcopenia and osteoporosis. Identifying the potential common crosstalk genes between them may provide new insights for preventing and treating their development. In this study, DEG analysis, WGCNA, and machine learning algorithms were used to identify the key crosstalk genes of sarcopenia and osteoporosis; this was then validated using independent datasets and clinical samples. Finally, four crosstalk genes (ARHGEF10, PCDH7, CST6, and ROBO3) were identified, and mRNA expression and protein levels of PCDH7 in clinical samples from patients with sarcopenia, with osteoporosis, and with both sarcopenia and osteoporosis were found to be significantly higher than those from patients without sarcopenia or osteoporosis. PCDH7 seems to be a key gene related to the development of both sarcopenia and osteoporosis.

Iron metabolism and ferroptosis in diabetic bone loss: from mechanism to therapy

Osteoporosis, one of the most serious and common complications of diabetes, has affected the quality of life of a large number of people in recent years. Although there are many studies on the mechanism of diabetic osteoporosis, the information is still limited and there is no consensus. Recently, researchers have proven that osteoporosis induced by diabetes mellitus may be connected to an abnormal iron metabolism and ferroptosis inside cells under high glucose situations. However, there are no comprehensive reviews reported. Understanding these mechanisms has important implications for the development and treatment of diabetic osteoporosis. Therefore, this review elaborates on the changes in bones under high glucose conditions, the consequences of an elevated glucose microenvironment on the associated cells, the impact of high glucose conditions on the iron metabolism of the associated cells, and the signaling pathways of the cells that may contribute to diabetic bone loss in the presence of an abnormal iron metabolism. Lastly, we also elucidate and discuss the therapeutic targets of diabetic bone loss with relevant medications which provides some inspiration for its cure.

Hydrogen sulfide alleviates beryllium sulfate-induced ferroptosis and ferritinophagy in 16HBE cells

Beryllium sulfate (BeSO₄ ) can result to lung injuries, such as leading to lipid peroxidation and autophagy, and the treatment of beryllium disease has not been well improved. Ferroptosis is a regulated cell death process driven by iron-dependent and lipid peroxidation, while ferritinophagy is a process mediated by nuclear receptor coactivator 4 (NCOA4), combined with ferritin heavy chain 1 (FTH1) degradation and release Fe²⁺ , which regulated intracellular iron metabolism and ferroptosis. Hydrogen sulfide (H₂ S) has the effects of antioxidant, antiautophagy, and antiferroptosis. This study aimed to investigate the effect of H₂ S on BeSO₄ -induced ferroptosis and ferritinophagy in 16HBE cells and the underlying mechanism. In this study, BeSO₄ -induced 16HBE cell injury model was established based on cellular level and pretreated with deferoxamine (DFO, a ferroptosis inhibitor), sodium hydrosulfide (NaHS, a H₂ S donor), or NCOA4 siRNA and, subsequently, performed to detect the levels of lipid peroxidation and Fe²⁺ and the biomarkers of ferroptosis and ferritinophagy. More importantly, our research found that DFO, NaHS, or NCOA4 siRNA alleviated BeSO₄ -induced ferroptosis and ferritinophagy by decreasing the accumulation of Fe²⁺ and lipid peroxides. Furthermore, the relationship between ferroptosis, ferritinophagy, H₂ S, and beryllium disease is not well defined; therefore, our research is innovative. Overall, our results provided a new theoretical basis for the prevention and treatment of beryllium disease and suggested that the application of H₂ S, blocking ferroptosis, and ferritinophagy may be a potential therapeutic direction for the prevention and treatment of beryllium disease.

Current insights into the functional roles of ferroptosis in musculoskeletal diseases and therapeutic implications

Ferroptosis is a novel type of cell death associated with iron accumulation and excessive lipid peroxidation. Elucidating the underlying molecular mechanisms of ferroptosis is intensively related to the development and treatment of multiple diseases, including musculoskeletal disorders. Moreover, in vitro and in vivo studies have shown the importance of oxidative stress in musculoskeletal conditions such as osteoporosis, osteoarthritis, rheumatoid arthritis, and osteosarcoma. Ferroptosis-derived clinical management of musculoskeletal diseases offers tremendous and attractive opportunities. Notably, ferroptosis agonists have been proven to enhance the sensitivity of osteosarcoma cells to conventional therapeutic strategies. In this review, we have mainly focused on the implications of ferroptosis regulation in the pathophysiology and therapeutic response of musculoskeletal disorders. Understanding roles of ferroptosis for controlling musculoskeletal diseases might provide directions for ferroptosis-driven therapies, which could be promising for the development of novel therapeutic strategies.