Contribution of ferroptosis and GPX4's dual functions to osteoarthritis progression

RNA methylation: A new perspective in osteoarthritis research

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by cartilage degradation, osteophyte formation, and joint dysfunction, significantly impairing the quality of life in the elderly population. Recently, RNA modifications, as a dynamic and reversible epigenetic modification, have emerged as critical players in the onset and progression of OA. This review systematically summarizes the major types of RNA modifications involved in OA, including N6-methyladenosine (m6A), 5-methylcytosine (m5C), and 7-methylguanosine (m7G), and explores their roles in regulating chondrocyte autophagy, inflammatory responses, and key signaling pathways. with a primary focus on RNA methylation. Special emphasis is placed on the dynamic regulatory functions of key methyltransferases (e.g., METTL3, FTO, WTAP) and their potential contributions to OA pathogenesis. Furthermore, we address current research hotspots and controversies in the field, proposing future research directions, such as leveraging single-cell sequencing to decipher dynamic RNA modification changes during OA progression and uncovering the cooperative networks among various RNA modifications. Advancing our understanding of the biological roles and mechanisms of RNA modifications holds promise for innovative strategies in the early diagnosis, disease stratification, and targeted therapy of OA.

The key role of Piezo1 channels in ferroptosis after spinal cord injury and the therapeutic potential of Piezo1 inhibitors

BACKGROUND

Ferroptosis has been confirmed to be one of the key mechanisms of neuronal injury and dysfunction after spinal cord injury (SCI). Mechanical stresses such as deformation, compression, and stretching not only directly cause physical damage to spinal cord tissue at the moment of SCI, but also promote the development of ferroptosis through various pathways. However, the mechanism of ferroptosis after SCI remains unclear, which hinders the development of therapeutic methods.

OBJECTIVE

This article aims to review the key mechanisms by which mechanical stress affects ferroptosis after SCI, including its impact on the structure and function of the endoplasmic reticulum (ER) and mitochondria, its role in triggering inflammatory responses, and its activation of mechanosensitive channels. Special emphasis is placed on the role of Piezo1 channels, which are key factors in cell mechanosensation and ion homeostasis regulation. The review explores how Piezo1 channels are upregulated by mechanical stress after SCI and participate in the ferroptosis process by mediating ion flow and other mechanisms.

CONCLUSIONS

Inhibiting Piezo1 channels may be a potential therapeutic strategy for SCI. This review summarizes the therapeutic potential of Piezo1 inhibitors by sorting out existing studies, hoping to provide a theoretical basis for effective therapeutic strategies targeting ferroptosis after SCI.

Pathophysiology of the Effects of Oxidative Stress on the Skeletal System

Reactive oxygen species (ROS) are molecules that are generated primarily during energy production in cells. ROS are involved in critical biological functions such as signal transduction; when the production of ROS is imbalanced, excessive ROS causes oxidative stress, and subsequent cellular damage. Oxidative stress is linked to numerous pathological disorders in major organs including the skeletal system. In an aging society, understanding the role of ROS in skeletal health is critical to developing preventative and therapeutic interventions. Oxidative stress causes defects in cellular differentiation, apoptosis, mitochondrial dysfunction, and inflammation. The effects of oxidative stress on the skeletal system have been implicated in the development of osteoporosis, knee osteoarthritis, and osteonecrosis by inhibiting bone remodeling, increasing osteoclast activity, and decreasing osteoblast function. ROS are also involved in many signaling pathways that regulate immune defense, cell proliferation, and inflammation. This underscores the importance of maintaining a balance between ROS and antioxidants to prevent oxidative stress and related diseases. Targeting ROS and oxidative stress mechanisms may offer new treatments for diseases affecting the skeletal system and other organs, potentially improving health outcomes, and extending healthy lifespans. This review highlights the significant impact of oxidative stress on skeletal health and explores potential preventative and therapeutic strategies to mitigate the adverse effects of ROS.

Novel pH-responsive lipid nanoparticles deliver UA-mediated mitophagy and ferroptosis for osteoarthritis treatment

Synovial inflammation plays a crucial role in osteoarthritis (OA) development, leading to chronic inflammation and cartilage destruction. Although targeting synovitis can alleviate OA, clinical outcomes have been disappointing due to poor drug targeting and joint cavity heterogeneity. This study presents pH-responsive lipid nanoparticles (LNPs@UA), loaded with Urolithin A (UA), as a potential OA treatment. LNPs@UA showed uniform particle size, low zeta potential, and effective mitochondria-targeting and pH-responsive capabilities. In vitro, LNPs@UA reduced reactive oxygen species (ROS), pro-inflammatory factors (IL-1β, IL-6, TNF-α), and promoted M2 macrophage polarization. It improved mitochondrial structure, enhanced autophagy, and inhibited ferroptosis. In vivo, LNPs@UA alleviated OA progression in an ACLT-induced OA mouse model. Transcriptomic analysis revealed inhibition of NF-κB signaling and activation of repair pathways. These results suggest LNPs@UA could offer a promising therapeutic approach for OA.

Pantothenic acid alleviates osteoarthritis progression by inhibiting inflammatory response and ferroptosis through the SIRT1/Nrf2 signaling pathway

Osteoarthritis (OA) is a degenerative joint disease that is a major cause of deformity, swelling, pain and even loss of function in the knee joints of the elderly. Pantothenic acid (PA) plays a protective role in many organs due to its antioxidant and anti-inflammatory properties. Herein, we aimed to assess the protective role of PA on osteoarthritis and investigate the underlying molecular mechanism. The levels of inflammatory factors (IL-1β and TNF-α) in knee tissues were measured by ELISA. The Safranin O-Fast Green staining was used to assess the severity of OA and the H&E staining was used to assess the degree of synovitis. In vitro, the levels of iron, MDA, GSH were measured by the detection kits. Western blotting was used to assess the levels of signaling-related proteins. Our results showed that PA significantly attenuated the degree of cartilage degeneration in the MIA-induced osteoarthritis model. PA also reduced the expression of IL-1β, TNF-α, MMP1 and MMP3. In vitro, PA effectively reduced the concentrations of MMP1 and MMP3 in IL-1β-stimulated chondrocytes. PA decreased the levels of Fe2+ and MDA, while increasing GSH production and GPX4 and SLC7A11 expression in IL-1β-induced chondrocytes. Meanwhile, we found that PA was able to inhibit the phosphorylation level of p65, IκB protein in chondrocytes, which effectively blocked the NF-κB signaling pathway. Furthermore, PA also increased the level of SIRT1, Nrf2, and HO-1 protein expression. In addition, the inhibition of PA on IL-1β-induced MMPs production and ferroptosis were inhibited by the SIRT1 inhibitor EX-527. In conclusion, PA inhibited chondrocyte ferroptosis and cartilage destruction in osteoarthritis. The mechanism was through activating SIRT1/Nrf2 signaling pathway.

The effect of lactate dehydrogenase B and its mediated histone lactylation on chondrocyte ferroptosis during osteoarthritis

BACKGROUND

Histone lactylation is a novel epigenetic regulator that is reported to participate in gene expression. Ferroptosis is an oxidative form of cell death and chondrocyte ferroptosis crucially impacts the development of osteoarthritis (OA). The study aimed at investigating the effect of lactate dehydrogenase B (LDHB) and its mediated histone lactylation on chondrocyte ferroptosis during OA.

METHODS

Our study focused on the establishment of in vivo mouse model and in vitro interleukin-1β (IL-1β)-induced chondrocytes model and administrated LDHB knockdown (siLDHB). Histopathological assessment of cartilage was conducted via HE staining, while serum levels of cartilage oligomeric matrix protein (COMP) and crosslinked C-telopeptides of type II collagen (CTX-II) were quantified using ELISA to evaluate OA severity. The matrix degradation was further examined by expression of Collagen II and Aggrecan. Levels of total iron, ferrous iron (Fe2+), and lipid reactive oxygen species (ROS) were considered measurements of ferroptosis. Assessment of cell viability and proliferation relied on cell counting kit 8 (CCK-8) together with colony formation assay. Western blotting assay served for detecting the relative expression of proteins and protein lactylation. The epigenetic regulation of ACSL4 by LDHB was determined by chromatin immunoprecipitation (ChIP) and luciferase reporter gene assay.

RESULTS

OA mice presented remarkably elevated protein level of LDHB and H3K18 lactylation in the cartilage versus the sham group. Knockdown of LDHB downregulated the levels of COMP and CTX-II, as well as alleviated chondrocyte ferroptosis in vitro and in vivo. Results from ChIP and luciferase reporter gene assay demonstrated direct histone lactylation of ACSL promoter, and knockdown of LDHB and treatment with LDH inhibitor reduced histone lactylation and expression of ACSL4. ACSL4 overexpression could reverse the impact of LDHB depletion on chondrocyte proliferation and ferroptosis.

CONCLUSION

LDHB promotes ACSL4 by histone lactylation to induce chondrocyte ferroptosis, which further contributes to OA development. The findings in the study assist in understanding the modulating mechanism of LDHB-mediated lactylation against chondrocyte ferroptosis in OA progression.

Chondrocyte-targeted α-Solanine through HIF-1α regulating glycolysis to reduce the ferroptosis of chondrocyte in osteoarthritis

α-Solanine, a glycoalkaloid (GA) extracted from the stems of the potato plant, exhibits bioactivity and medicinal potential that necessitate further investigation. The impact and underlying mechanisms of α-Solanine on osteoarthritis (OA) remain to be elucidated. To achieve enhanced therapeutic outcomes, we have designed and synthesized a UIO-66-NH2@α-Solanine@PEI charged particle (USP) that amplifies the therapeutic effects of α-Solanine, demonstrating superior efficacy. Our approach involved the synthesis of a novel drug delivery system, the USP, to augment the therapeutic potential of α-Solanine in the treatment of OA. An OA rat model was established, and USP treatment was administered. The therapeutic effects were verified through histochemical staining and micro-CT. In vitro, α-Solanine significantly suppressed the expression of proteins related to glycolysis and notably inhibited ferroptosis. RNA sequencing revealed hypoxia-inducible factor-1α (HIF-1α) as a potential pathway mediating the effects of α-Solanine, and it was found that the co-addition of cycloheximide (CHX) led to a shortened decay time of HIF-1α. In vivo, rats with OA demonstrated significant inhibition of glycolysis and ferroptosis following treatment with USP, along with improvements in OA characteristics. These findings suggest that α-Solanine can inhibit the intense glycolysis associated with OA via the HIF-1α pathway and alleviate ferroptosis in chondrocytes. Treatment with USP demonstrated superior efficacy in the management of OA, providing a new therapeutic strategy for the disease.

Decreased serum and local GPX4 and SLC7A11 expression correlates with disease severity in non-traumatic osteonecrosis of the femoral head

BACKGROUND

Ferroptosis is implicated in various musculoskeletal conditions, including non-traumatic osteonecrosis of the femoral head (NT-ONFH).

OBJECTIVE

The objective of this study was to explore the levels of two crucial proteins associated with ferroptosis, namely Glutathione peroxidase 4 (GPX4) and Solute Carrier Family 7 Member 11 (SLC7A11), in both serum and femoral head samples, and to correlate their expression levels with the clinical severity of NT-ONFH.

METHODS

The study included 136 NT-ONFH patients and an equal number of healthy controls. In addition, 68 subjects suffering from femoral neck fractures (FNF) were included in the study. The serum concentrations of GPX4 and SLC7A11 were quantified using the enzyme-linked immunosorbent assay. The GPX4 and SLC7A11 levels among tissue samples were identified through immunohistochemical staining, western blot analysis, and quantitative real-time polymerase chain reaction (qRT-PCR). The radiographic severity of the condition was evaluated utilizing the Association Research Circulation Osseous (ARCO) classification system, while the symptomatic severity was assessed utilizing the Visual Analogue Scale (VAS) alongside the Harris Hip Score (HHS).

RESULTS

Patients diagnosed with NT-ONFH had considerably reduced serum concentrations of GPX4 and SLC7A11 in comparison to individuals in the healthy control group. Negative correlations of serum GPX4 and SLC7A11 levels with the ARCO stages were observed. A total of 73 ONFH and 68 FNF patients underwent total hip replacement. The mRNA and protein levels of GPX4 and SLC7A11 were lower in the necrotic areas compared to the non-necrotic areas and FNF femoral head tissues. Subsequent Receiver operating characteristic (ROC) curve analysis suggested that the decreased levels of both serum and local GPX4 and SLC7A11 could serve as potential biomarkers for the progression of ONFH. Furthermore, serum and local GPX4 and SLC7A11 levels were found to be negatively linked to the VAS score but positively related to the HHS score.

CONCLUSION

The levels of GPX4 and SLC7A11, both in serum and at the local site, were inversely correlated with the progression of NT-ONFH. Targeting ferroptosis and its associated proteins through potential therapeutic interventions could be a viable strategy to mitigate the severity of NT-ONFH.

GPX4 degradation contributes to heat stress-induced liver injury via chaperone-mediated autophagy

Heat stress (HS) is a significant health concern that adversely affects both human and animal health, particularly impacting liver function due to its central metabolic role. This study investigated the mechanisms underlying HS-induced liver injury, focusing on the role of ferroptosis, an iron-dependent form of cell death characterized by lipid peroxidation and cellular iron accumulation. Using mouse and cellular HS models, the results demonstrated that HS induced liver injury through ferroptosis, as evidenced by increased levels of malondialdehyde (MDA), oxidized glutathione (GSSG), and iron, alongside decreased glutathione (GSH) and glutathione peroxidase 4 (GPX4) expression. The ferroptosis inhibitor Ferrostatin-1 (Fer-1) effectively mitigated HS-induced liver damage, reducing oxidative stress and restoring GPX4 levels. Furthermore, HS promoted the lysosomal degradation of GPX4 via the chaperone-mediated autophagy (CMA) pathway, which was regulated by heat shock cognate protein 70 (HSC70) and lysosome-associated membrane protein 2A (LAMP2A). Knockdown of LAMP2A in hepatocytes significantly suppressed HS-induced GPX4 degradation, confirming the critical role of CMA in this process. Inhibition of CMA using Apoptozole, an HSC70 inhibitor, or Bafilomycin A1 (Baf-A1), a lysosomal inhibitor, further attenuated HS-induced ferroptosis and liver injury. These findings highlight the critical role of CMA-mediated GPX4 degradation in HS-induced ferroptosis and liver injury, providing potential therapeutic targets for mitigating HS-related liver damage.

TNF-α inhibits Epstein Barr virus reactivation through the GPX4 mediated glutathione pathway

Epstein-Barr virus (EBV) is a carcinogenic γ-herpesvirus that remains latent in more than 95% of adults. The virus can undergo lytic activation when immune function is suppressed or when stimulated by drugs or pathogens. EBV reactivation poses a significant threat to human health and is closely associated with various cancers, such as Burkitt's lymphoma and nasopharyngeal carcinoma. Inhibiting EBV reactivation is a current clinical challenge. Tumour necrosis factor-α (TNF-α), an important cytokine, has different effects on various viruses. It also exerts varying effects on the same virus depending on the type of infected cell. This study aimed to investigate the impact of TNF-α on EBV reactivation and its underlying mechanisms. Our experimental research revealed that TNF-α significantly inhibits EBV reactivation and that this inhibitory effect is mediated primarily through its receptor TNFR1. Furthermore, TNF-α affects the expression of the GPX4 protein and regulates the potential ferroptosis state of cells. Using transmission electron microscopy and other methods, we observed typical characteristics of ferroptosis, such as changes in mitochondrial morphology and Fe2 + accumulation. Additionally, we established stable GPX4-knockdown cell lines, which demonstrated the crucial role of GPX4 in the process of TNF-α-mediated inhibition of EBV reactivation. Overall, TNF-α acts on the TNFR1 receptor, thereby affecting the GPX4 protein and the ferroptosis pathway to achieve its inhibitory effect on EBV reactivation. These findings provide new insights into the mechanisms of EBV reactivation and may offer new perspectives for the early treatment of EBV-related diseases.

Copper silicate nanoparticle-mediated delivery of astragaloside-IV for osteoarthritis treatment by remodeling the articular cartilage microenvironment

With the increasing global aging population, osteoarthritis (OA) has emerged as a major public health concern. OA pathogenesis is characterized by a complex interplay among inflammatory cytokines, reactive oxygen species, and extracellular matrix components, leading to cartilage degradation. Astragaloside-IV (AS-IV), a natural antioxidant, has shown promise in alleviating OA symptoms but is limited by poor bioavailability and ineffective cartilage drug delivery. To address these challenges, we aimed to develop a drug delivery system using copper silicate nanoparticles modified with polyethylene glycol and loaded with AS-IV (referred to as CSP@AS-IV). This system uses mesoporous silica nanoparticles with a hybrid metal framework to enhance drug release and efficacy. CSP@AS-IV degrades in the acidic OA microenvironment, releasing copper ions (Cu2+) and AS-IV, which synergistically exert antioxidant, antibacterial, anti-inflammatory, and chondroprotective effects. Both in vitro and in vivo rat model experiments demonstrated that CSP@AS-IV significantly alleviated joint inflammation, downregulated inflammatory marker expression, and promoted cartilage repair. These findings underscore that CSP@AS-IV offers considerable clinical potential for enhancing OA treatment outcomes.

Mediating Role of the ANGPTL3/TFPI Protein Ratio in Regulating T-Cell Surface Glycoprotein CD5 Levels on Knee Osteoarthritis (KOA): A Mendelian Randomization Study

This study utilized Mendelian randomization (MR) to investigate the impact of inflammatory proteins on knee osteoarthritis (KOA), measured using the ratio of protein levels (rQTLs). The primary objective was to identify potential intervention targets to mitigate KOA progression. Data from 2821 rQTLs, 91 inflammatory proteins, and KOA-related genetic variations were obtained through genome-wide association studies (GWAS). Bidirectional MR identified rQTLs with unidirectional causal relationships with KOA. Further analyses included false discovery rate (FDR) correction, colocalization, and mediation analysis. Two inflammatory proteins were found to be associated with KOA: T-cell surface glycoprotein CD5 [OR (95% CI) = 0.867 (0.760-0.990), PIVW = 0.035] and C-X-C motif chemokine 9 [OR (95% CI) = 1.150 (1.001-1.320), PIVW = 0.048]. Variations in their levels influenced rQTLs, producing differential effects on KOA. Specifically, rQTL-ANGPTL3/TFPI (human recombinant angiopoietin-like protein 3/Tissue factor pathway inhibitor) was identified as a mediator in the effect of T-cell surface glycoprotein CD5 levels on KOA. T-cell surface glycoprotein CD5 levels were negatively correlated with rQTL-ANGPTL3/TFPI (β1 = -0.084), while rQTL-ANGPTL3/TFPI was positively correlated with KOA (β2 = 0.159). These findings align with the total effect, where T-cell surface glycoprotein CD5 levels were negatively associated with KOA (β = -0.143). Thus, rQTL-ANGPTL3/TFPI may serve as a reliable mediator in the pathway through which T-cell surface glycoprotein CD5 levels affect KOA. This mediator may not only represent a potential therapeutic target but also serve as a biomarker for assessing KOA treatment efficacy, offering a novel direction for KOA diagnosis and management.

Electroacupuncture Inhibits Ferroptosis by Modulating Iron Metabolism and Oxidative Stress to Alleviate Cerebral Ischemia-Reperfusion Injury

Ischemic stroke (IS) is one of the leading causes of mortality and long-term disability worldwide. Electroacupuncture (EA) is commonly used in the treatment of IS, meaning that may reduce cerebral ischemia-reperfusion injury (CIRI). The middle cerebral artery occlusion/reperfusion (MCAO/R) rat models were created by the modified Zea Longa suture method. EA treatment was performed for 7 consecutive days at the acupoints Neiguan (PC6), Shuigou (GV26), and Sanyinjiao (SP6). The neurological function was assessed using the Zausinger six-point neurological deficiency score. The cerebral infarct volume was detected by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Hematoxylin and eosin (HE) staining was employed to observe the pathological changes in brain tissues. Prussian blue staining was employed to investigate iron deposition within the brain tissues. Transmission electron microscopy (TEM) was utilized to examine the morphological characteristics of mitochondria. Simultaneously, flow cytometry was utilized to detect the fluorescence intensity of reactive oxygen species (ROS). Assay kits were employed to measure the levels of Fe2+ and glutathione (GSH). Additionally, western blot (WB) and real-time quantitative polymerase chain reaction (RT-qPCR) assays were performed to evaluate the expression levels of proteins associated with ferroptosis. Compared with the MCAO/R group, both the MCAO/R + EA and MCAO/R + DFO groups exhibited significant improvements in neurological function following cerebral ischemia-reperfusion (CIR), attenuated the pathological brain tissue injury, and reduced the cerebral infarct volume and iron deposition in brain tissue. Furthermore, both the MCAO/R + EA and MCAO/R + DFO groups displayed a marked reduction in mitochondrial injury. There was a substantial decrease in Fe2+ and ROS levels, accompanied by a notable increase in GSH level and glutathione peroxidase 4 (GPX4) activity. Compared with the MCAO/R group, the levels of ferroportin1 (FPN1) protein and mRNA expression were significantly increased in the MCAO/R + EA and MCAO/R + DFO groups, and the expression levels of transferrin (TF), transferrin receptor 1 (TFR1), divalent metal transporter 1 (DMT1) protein and mRNA, as well as ferritin (FER) protein, were significantly decreased. EA inhibits ferroptosis by modulating iron metabolism and oxidative stress to alleviate CIRI, exerting neuroprotective effects.

Cytoglobin augments ferroptosis through autophagic degradation of ferritin in colorectal cancer cells

Autophagy has gained importance in the context of ferroptosis. Nevertheless, a deeper understanding of the regulatory mechanism governing autophagy-dependent ferroptosis is necessary. Cytoglobin (CYGB), a member of the globin family, exhibits antifibrotic effects, regulates cellular reactive oxygen species, and stimulates tumor inhibition. Herein, we present further insights into the role of CYGB in ferroptosis regulation. Our investigation confirmed that CYGB impedes cell proliferation and migration. Furthermore, a significant association between CYGB and the lysosomal pathway was suggested based on the RNA sequencing data analysis. Elevated lysosomal signal and colocalization of CYGB with lysosome-associated membrane glycoprotein 1 (LAMP1) were observed. Moreover, upregulated autophagy and augmented ferroptosis induced by RSL3 were confirmed in CYGB-overexpression cells with an obviously increased colocalization of nuclear receptor coactivator 4 (NCOA4) and LC3B. The autophagy inhibitor bafilomycin or chloroquine alleviated autophagy-dependent degradation of ferritin protein under RSL3 treated condition. Additionally, a colocalization of CYGB with the transferrin receptor (TFR) was confirmed. Our results demonstrate an important functional pathway by which CYGB regulates ferroptosis through TFR-binding and autophagic degradation of ferritin, and provide a potential pathway for the treatment of colorectal cancer.

Sirt1 overexpression inhibits chondrocyte ferroptosis via Ftl deacetylation to suppress the development of osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a chronic degenerative joint disorder characterized by an imbalance in chondrocyte metabolism. Ferroptosis has been implicated in the pathogenesis of OA. The role of Sirt1, a deacetylase, in mediating deacetylation during ferroptosis in OA chondrocytes remains underexplored. This study aimed to elucidate the mechanisms by which Sirt1 influences chondrocyte ferroptosis in the development of OA.

MATERIALS AND METHODS

In vitro and in vivo models of OA were established using IL-1β-induced mouse chondrocytes and a destabilization of the medial meniscus (DMM) mouse model, respectively. Ferroptosis was evaluated through measurements of cell viability, lactate dehydrogenase (LDH) release, intracellular levels of Fe2+, glutathione (GSH), malondialdehyde (MDA), lipid reactive oxygen species (ROS), propidium iodide staining, and Western blot analysis. The underlying mechanisms were further investigated using quantitative real-time polymerase chain reaction, Western blotting, immunoprecipitation (IP), co-immunoprecipitation (Co-IP), and glutathione-S-transferase pulldown assays. In vivo validation was performed via Safranin O staining.

RESULTS

IL-1β induced ferroptosis and increased histone acetylation, effects that were partially reversed by Sirt1 overexpression. Mechanistically, Sirt1 overexpression upregulated ferritin light polypeptide (Ftl) expression by deacetylating Ftl at the K181 residue. Ftl knockdown inhibited the ferroptosis-enhancing effect of Sirt1 overexpression in chondrocytes. In vivo studies showed that Sirt1 overexpression mitigated the progression of OA and reduced ferroptosis in the DMM-induced OA mouse model.

CONCLUSION

Our findings confirm that Sirt1 overexpression promotes Ftl expression through deacetylation at the K181 site, thereby suppressing chondrocyte ferroptosis and attenuating the progression of OA. These results suggest a potential therapeutic target for OA treatment.

Exploring extracellular vesicles as novel therapeutic agents for intervertebral disc degeneration: delivery, applications, and mechanisms

Intervertebral disc degeneration is a multifactorial degenerative disease that poses a significant threat to the health of the elderly population. Current treatments primarily focus on physical therapy, medication, and surgery to alleviate symptoms associated with disc compression but do not address the progression of degeneration. Therefore, this review aimed to explore the potential of extracellular vesicle therapy as a novel preventive strategy to delay degeneration and enhance tissue repair in intervertebral discs. We cover the pathogenic mechanisms underlying intervertebral disc degeneration, including inflammation, apoptosis, pyroptosis, ferroptosis, autophagy dysregulation, and the roles of non-coding RNAs. Subsequently, we discussed the therapeutic potential of extracellular vesicles and their molecular components, such as proteins, RNAs, and lipids, in modulating these pathways to counter intervertebral disc degeneration. We provides a comprehensive review of the significant role of extracellular vesicle cargo in mediating repair mechanisms. It discusses the functional enhancement advantages exhibited by extracellular vesicles under current bioengineering modifications and drug loading. The challenges and future prospects of utilizing extracellular vesicle therapy to treat this degenerative condition are also summarized.

SETD7 drives diabetic endothelial dysfunction through FBXO45-mediated GPX4 ubiquitylation

BACKGROUND

Vasculopathy is the most prevalent complication of diabetes. Endothelial damage, a primary contributor to hyperglycemic vascular complications, impacts macro- and micro-vasculatures, causing functional impairment of multiple organs. SETD7 was initially identified as a transcriptional activator based on its ability to methylate histone 3 lysine 4. However, its function in the context of diabetic endothelial dysfunction remains poorly understood. This study aims to elucidate the involvement and underlying mechanisms of SETD7 in diabetic endothelial dysfunction.

METHODS

SETD7 knockout mice were generated to investigate the effects of SETD7 on Streptozotocin (STZ)-induced hyperglycemia and vascular endothelial injury. Endothelial-specific SETD7 interruption adeno-associated virus (AAV) system was utilized to investigate the effects of SETD7 on diabetic vascular endothelial injury in BKS-DB(Lepr) KO/KO (db/db) mice. In vitro manipulation of SETD7 activation or knockdown was conducted to assess its regulation on the lipid peroxidation, oxidative stress, and cell function of primary rat aortic endothelial cells (RAECs) under high glucose conditions.

RESULTS

Our study revealed that knockout and endothelial deficiency of SETD7 partially restored damaged vascular function and attenuated the inflammatory response caused by high glucose in both STZ-induced and db/db mice. Moreover, SETD7 activation aggravated oxidative stress injury and resulted in profound dysfunction through Glutathione Peroxidase 4 (GPX4)-mediated lipid peroxidation in RAECs. Mechanistically, SETD7 deficiency reduced p53 mono-methylation and blocked FBXO45 transcription, thereby inhibiting the protein degradation of GPX4 and subsequent lipid peroxidation as well as oxidative stress.

CONCLUSIONS

In summary, our study demonstrates that SETD7-p53-FBXO45-GPX4 is involved in high glucose-induced oxidative stress injury and exacerbated endothelial dysfunction, which offering great significance for mitigating hyperglycemia-induced endothelial damage.

Glutathion peroxidase 4 (GPX4) and Ribosomal Protein L40 (RPL40) participate in arsenic induced progression of renal cell carcinoma by regulating the NLRP3 mediated classic pyroptosis pathway

Epidemiological studies have demonstrated that long-term exposure to high‑arsenic water increases the risk of kidney cancer. Kidney dysfunction can lead to the accumulation of metabolic waste and chronic inflammation, with the latter being a significant factor in tumor development. Therefore, it is crucial to investigate how environmental arsenic exposure affects renal function and inflammation, as well as its potential influence on the progression of renal carcinoma. Additionally, pyroptosis plays an essential role in immune responses and the maintenance of cellular homeostasis. However, the role and mechanisms of pyroptosis in arsenic-induced kidney cancer progression remain unexplored. Our findings indicated that low-dose arsenic exposure reduces pyroptosis and promotes abnormal proliferation of renal tubular epithelial cells, while high-dose exposure enhances pyroptosis and damages renal tissue structure in mouse models. Mechanistically, in vitro studies confirmed that low-dose arsenic exposure promotes the progression of renal cell carcinoma by downregulating NLRP3 and inhibiting pyroptosis, whereas high-dose exposure has the opposite effect. Proteomics analysis identified GPX4 and RPL40 as key proteins mediating pyroptosis induced by low and high doses of arsenic, respectively. Furthermore, GPX4 and RPL40 were shown to regulate the malignant progression of renal cell carcinoma through their effects on NLRP3-mediated pyroptosis. This study reveals that arsenic exposure induces pyroptosis via NLRP3, leading to renal injury and influencing the malignant progression of renal cancer. Notably, GPX4 and RPL40 regulate this progression under low and high-dose arsenic exposure, respectively.

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.

CCL3 correlates with ferroptosis in intervertebral disc degeneration and its prognostic significance

Intervertebral disc degeneration (IVDD) is a prevalent and debilitating condition associated with low back pain (LBP). Despite its significant impact, effective diagnostic markers for early-stage IVDD remain elusive. Recent research has implicated ferroptosis, a newly recognized form of programmed cell death, in the pathogenesis of IVDD, particularly involving disturbances in iron homeostasis. Additionally, the CC Chemokine Ligand 3 (CCL3) has been linked to macrophage migration and the progression of IVDD, yet its precise diagnostic and prognostic utility remains uncertain. This study aims to elucidate the underlying mechanisms of ferroptosis and the involvement of CCL3 in IVDD, with the objective of establishing their diagnostic and prognostic significance. By uncovering these mechanisms, novel biomarkers and therapeutic targets for the diagnosis and prognosis of IVDD may be identified. Single-cell sequencing data were acquired from the TCGA database, and a range of bioinformatics methods were employed for comprehensive analysis. Furthermore, validation experiments were conducted using in vitro techniques, including the analysis of human tissue samples, co-culture assays with neutralizing antibodies, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting. Our findings suggest that CCL3 holds promise as a diagnostic and may was prognostic biomarker for IVDD. Validation experiments demonstrated that CCL3 functions via the pAMPK/AMPK pathway, thereby modulating apoptosis and impacting the progression of IVDD. Our study underscores the diagnostic and prognostic potential of CCL3 in patients with IVDD. Further investigations are warranted to explore therapeutic strategies targeting CCL3, ultimately enhancing the management of IVDD.

Notopterol mitigates osteoarthritis progression and relieves pain in mice by inhibiting PI3K/Akt/GPX4-mediated ferroptosis

Ferroptosis-induced lipid peroxidation in chondrocytes exacerbates intra-articular inflammation, oxidative stress, and articular cartilage degradation, accelerating osteoarthritis (OA) progression. Effective anti-inflammatory and antioxidant interventions can alleviate both joint pain and cartilage damage. This study aims to elucidate the therapeutic effects of Notopterol (NP), a bioactive compound extracted from the rhizome of Notopterygium incisum, a traditional Chinese medicine known for its potent anti-inflammatory and antioxidant properties, in treating OA. An in vivo mouse model of OA was established through medial meniscus destabilization (DMM). Intra-articular injections of NP over a 4-week treatment period significantly alleviated pain and gait abnormalities, reduced subchondral osteosclerosis, and attenuated cartilage degradation compared to the untreated DMM group. In vitro, chondrocytes treated with IL-1β to simulate OA conditions exhibited increased viability following NP pretreatment, with concurrent reductions in apoptosis, reactive oxygen species (ROS) accumulation, and chondrocyte catabolic dysfunction, along with enhanced extracellular matrix (ECM) synthesis. Mechanistically, NP exerts its anti-OA effects by inhibiting PI3K/Akt phosphorylation, suppressing ferroptosis, and improving antioxidant defense via upregulation of glutathione (GSH) and glutathione peroxidase 4 (GPX4), thereby preventing lipid peroxidation. In conclusion, NP modulates the PI3K/Akt/GPX4 axis to protect against lipid peroxidation, inhibit ferroptosis, and preserve cartilage integrity, thus delaying OA progression.

β-Diketone Functionalized Microspheres Chelate Reactive Iron via Metal Coordination for Cartilage Repair

Excessive intracellular iron accumulation can induce mitochondrial dysfunction, leading to chondrocyte ferroptosis, a key contributor to cartilage damage in osteoarthritis (OA). Here, micelle-microfluidic hydrogel microspheres, featuring keto-enol-thiol bridged nano-sized secondary structures that disintegrate within the intracellular peroxidative environment to reveal β-diketone groups with metal chelation capabilities, are utilized for the in situ removal of reactive iron, thereby facilitating cartilage repair through the restoration of mitochondrial homeostasis. The relevant experiments demonstrate that the microspheres reduce iron influx by downregulating transferrin receptor (TfR1) expression and decrease mitochondrial iron uptake by upregulating mitochondrial outer membrane iron-sulfur cluster protein (CISD1), thus restoring intracellular mitochondrial iron homeostasis. Furthermore, the antioxidant properties of the ketone-thioether segments synergistically mitigate chondrocyte phospholipid peroxidation via Nrf2/SLC7A11/GPX4 axis, inhibiting ferroptosis and slowing OA progression. In summary, this system that in situ sustainably chelates reactive iron via metal coordination exhibits great potential in the minimally invasive treatment of OA and other ferroptosis-mediated diseases.

A review of pharmacological mechanisms, challenges and prospects of macromolecular glycopeptides

Macromolecular glycopeptides are natural products derived from various sources, distinguished by their structural diversity, multifaceted biological activities, and low toxicity. These compounds exhibit a wide range of biological functions, such as immunomodulation, antitumor effects, anti-inflammatory properties, antioxidant activity, and more. However, limited understanding of natural glycopeptides has hindered their development and practical application. To promote their advancement and utilization, it is crucial to thoroughly investigate the pharmacological mechanisms of glycopeptides and address the challenges in natural glycopeptide research. This review uniquely focuses on the primary biological activities and potential molecular mechanisms of glycopeptides as reported in recent literature. Moreover, we emphasize the current challenges in glycopeptide research, including extraction and isolation difficulties, purification challenges, structural analysis complexities, elucidation of structure-activity relationships, characterization of biosynthetic pathways, and ensuring bioavailability and stability. The future prospects for glycopeptide research are also explored. We argue that ongoing research into glycopeptides will significantly contribute to drug development and provide more effective therapeutic options and disease treatment alternatives for human health.

Targeting GPX4 alleviates ferroptosis and retards abdominal aortic aneurysm formation

Abdominal aortic aneurysm (AAA) is a potentially fatal cardiovascular disease, closely related to inflammation and loss of vascular smooth muscle cells (VSMCs). Ferroptosis is an iron-dependent cell death associated with peroxidation of lipids. However, the direct role of glutathione peroxidase 4 (GPX4) itself determined ferroptosis in the course of AAA pathogenesis remains unknown. Here, we reported that ferroptosis was triggered in human AAA, elastase- and angiotensin II (Ang II)-induced mouse AAA, and Ang II-incubated VSMCs. Inhibition of ferroptosis via global genetic overexpression of GPX4, a critical anti-ferroptosis molecule, markedly prevented both vascular remodeling and inflammatory response. Mechanistically, GPX4 changed the migration and activation of macrophages/monocytes in AAA tissues in mice. Experiments in vitro demonstrated that overexpression of GPX4 prevented the JAK1/STAT3 signaling activation in VSMCs induced by IL-6, production of pro-inflammatory macrophages. Finally, the role of ferroptosis was confirmed on an Ang II-induced mice AAA model. These results emphasized the significance of ferroptosis in AAA, and provided novel insights that therapy focusing on GPX4 might be a promising strategy for treatment of AAA in the clinic.

Cordycepin ameliorates morphine tolerance by inhibiting spinal cord ferroptosis and inflammation via targeting SIRT1

Morphine tolerance caused by long-term use of morphine is a major medical problem. Neuroinflammation plays an important role in morphine tolerance, and currently no drugs have been found for clinical use to alleviate neuroinflammation during morphine tolerance. Cordycepin is the main active component of fungus cordycepin militaris, has been demonstrated to have anti-oxidative stress and anti-inflammatory properties in various diseases. In this study, we established a rat model of morphine tolerance, examined the effect of cordycepin on the development of morphine tolerance, and evaluated its potential regulatory mechanisms. We found that cordycepin treatment ameliorated the development of morphine tolerance, improved mitochondrial damage associated with ferroptosis, by reducing the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and Fe2+, increasing superoxide dismutase (SOD) and glutathione (GSH) levels, and decreasing the secretion of pro-inflammatory factors (IL-1β, IL-6, and TNF-α). Besides, cordycepin upregulated the expression of SIRT1, SLC7A11 and GPX4. Further research found that the above effects of cordycepin on morphine-tolerant rats were abolished by SIRT1 selective inhibitor EX-527. Thus, these findings indicated that cordycepin could ameliorate the development of morphine tolerance by inhibiting spinal cord ferroptosis and inflammation via targeting SIRT1. Collectively, these results demonstrated the protective effects of cordycepin and highlighted its therapeutic potential as a drug component for morphine tolerance treatment and prevention.

Cutting edge: ferroptosis in metabolic dysfunction-associated steatotic liver disease (MASLD) pathogenesis and therapy

Ferroptosis denotes a distinct form of controlled cell death marked by substantial iron buildup and significant lipid peroxidation, playing a crucial role in several disease processes linked to cell death. Given the liver's essential functions in iron and lipid metabolism and its vulnerability to oxidative damage, more research has investigated the correlation between ferroptosis and numerous hepatic diseases, including metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD). NAFLD has arisen as a worldwide public health concern due to elevated morbidity and high death rates. The pathogenesis of MASLD remains incompletely elucidated. Recent data suggests that ferroptosis is crucial in the pathophysiology of MASLD; nevertheless, the specific processes by which ferroptosis influences MASLD remain unclear. The present review summarizes the molecular processes of ferroptosis and its intricate regulatory networks, outlines the differing impacts of ferroptosis at different stages of MASLD, and examines possible approaches targeting ferroptosis for the therapy of MASLD, suggesting a novel approach for its management.

Unraveling the brain-joint axis: genetic, transcriptomic, and cohort insights from neuroticism to osteoarthritis

The causal relationships between neuroticism and osteoarthritis (OA) were inconclusive in observational studies. We conducted bidirectional two-sample Mendelian randomization (MR) and transcriptome-wide association studies to determine the associations and the underlying transcriptomic basis. The summary-level genome-wide association study data for any site OA, knee OA, erosive hand OA, and hip OA were mainly derived from UK Biobank, and neuroticism was derived from CTGlab. We then utilized weighted regression and propensity score matching (PSM) models to investigate the relationship between neuroticism and OA in 11,948 participants of European ancestry from the National Health and Nutrition Examination Survey from 2005 to 2018. Bidirectional two-sample MR studies revealed that feelings of being fed-up, a sense of miserableness, mood swings, and a higher neuroticism score were all linked to an increased risk of OA. These factors were specifically associated with OA at various sites, including the knee. Conversely, there was no evidence to suggest that OA had any influence on traits related to neuroticism. In a comprehensive analysis that accounted for variables such as age, sex, blood lipids, blood glucose, body weight, smoking, alcohol consumption, and physical activity, it was determined that mental fluctuation significantly increased the incidence of self-reported OA (OR 1.37, 95% CI 1.20-1.58, P < 0.001) based on weighted regression. Further confirmation was provided by PSM analysis, which showed that mental fluctuation was associated with a higher incidence of self-reported OA (OR 1.28, 95% CI 1.08-1.52, P = 0.004). Moreover, differentially expressed genes were enriched in several biological processes, including the cell cycle, lipid metabolism, RNA processing, and immuno-inflammatory responses. The results revealed significant genetic and population-based associations, as well as underlying mechanisms, between neuroticism and osteoarthritis, supporting the concept of a brain-joint axis.

Resveratrol alleviates testicular toxicity induced by anti-PD-1 through regulating the NRF2-SLC7A11-GPX4 pathway

Background

Fertility preservation is a critical concern for reproductive-age cancer survivors, as conventional cytotoxic therapies can cause irreversible damage to the reproductive system, potentially depriving them of the ability to have children in the future. Immune checkpoint inhibitors (ICIs), including anti-programmed cell death protein 1 (anti-PD-1), have become a standard therapeutic approach for various malignancies. However, the impact of ICIs on reproductive function and fertility is not well understood and remains a largely unexplored domain. Resveratrol (RSV), a plant-derived compound, has shown potential as an nuclear factor erythroid 2-related factor 2 (NRF2) agonist to counteract reproductive toxicity induced by various diseases, drugs, and environmental toxins.

Methods

Male C57BL6/J mice with B16 melanoma were assigned into four groups. RSV and ICI/RSV groups received RSV (40 mg/kg) orally every other day for one month, while controls received the vehicle. ICI and ICI/RSV groups were injected with anti-PD-1 antibody (10 mg/kg) weekly, and controls received IgG2b kappa antibody. Parameters like body and testicular weight, sperm concentration, and western blot for ferroptosis markers were measured. Furthermore, oxidative stress biomarkers, lipid oxidation factors, and gonadal hormone levels were quantified using commercial kits.

Results

Anti-PD-1 therapy caused male reproductive dysfunction, as evidenced by reduced sperm concentration, altered gonadal hormone levels, and disruption of blood-testis barrier (BTB) integrity. Furthermore, ferroptosis was a key mechanism in anti-PD-1-induced testicular dysfunction, characterized by disrupted iron homeostasis, elevated lipid peroxidation, and suppression of the system Xc-/glutathione peroxidase 4 (GPX4) axis. Additionally, anti-PD-1 therapy diminished antioxidant defenses by inhibiting the NRF2 pathway, thereby increasing the susceptibility to ferroptosis. Crucially, RSV treatment ameliorated anti-PD-1-induced reproductive dysfunction. This was achieved by reducing T cell infiltration, lowering interferon-gamma levels, activating the NRF2 pathway, and maintaining iron and lipid homeostasis.

Conclusions

Our study demonstrates that anti-PD-1 triggers oxidative stress and ferroptosis in the testis, causing male reproductive dysfunction. RSV may offer protection against testicular toxicity associated with anti-PD-1, particularly through its antioxidant and anti-ferroptosis properties.

Paeonol ameliorates ferroptosis and inflammation in chondrocytes through AMPK/Nrf2/GPX4 pathway

Introduction

Chondrocyte ferroptosis is an important component of the pathogenesis of osteoarthritis. Paeonol, the main pharmacologically active ingredient of the Paeonia suffruticosa Andrews, is a natural radical scavenger with potent biological activities, including antioxidant, anti-inflammatory, and cartilage protection effects. However, the molecular mechanisms underlying its role in regulating chondrocytes ferroptosis remain unclear.

Methods

To investigate the effect of paeonol on ferroptosis and inflammation of chondrocytes through interleukin-1β (IL-1β), the proliferation activity, lipid peroxidation level, endogenous antioxidant capacity, and mitochondrial membrane potential of chondrocytes were evaluated in detail. Intracellular ferrous ion concentration was detected by FerroOrange fluorescent probe staining. Western blotting and immunofluorescence staining were used to detect biomarker proteins of ferroptosis, inflammation, and AMPK/Nrf2/GPX4 signaling pathway proteins.

Results

The results showed that paeonol significantly depressed IL-1β-induced ferroptosis and inflammation in chondrocytes. Specifically, paeonol protects cell viability, reduces lipid peroxidation damage, maintains mitochondrial function, and inhibits pro-ferroptosis and pro-inflammation biomarker proteins. In addition, the anti-inflammatory ability of paeonol was partially inhibited after the addition of ferroptosis agonist erastin, suggesting that paeonol protects against inflammatory injury in part by inhibiting ferroptosis. Further studies showed that paeonol activated AMPK phosphorylation and promoted Nrf2 nuclear translocation and Keap1 degradation. Finally, the AMPK-Nrf2-GPX4 signaling pathway was confirmed to be the underlying mechanism of paeonol against ferroptosis by the simultaneous use of the AMPK agonist and Nrf2 inhibitor.

Conclusion

These results indicate that paeonol significantly inhibits IL-1β-induced ferroptosis and inflammation in chondrocytes, and the underlying mechanism of paeonol against ferroptosis is partly through the AMPK/Nrf2/GPX4 axis.

Nanodrugs Targeting Key Factors of Ferroptosis Regulation for Enhanced Treatment of Osteoarthritis

Osteoarthritis (OA) is a globally prevalent degenerative joint disease. Recent studies highlight the role of ferroptosis in OA progression. Targeting ferroptosis regulation presents a promising therapeutic strategy for OA; however, current research primarily focuses on single targets associated with ferroptosis. In this study, a reactive oxygen species (ROS)-responsive nanoparticle is developed by linking deferasirox (DEF) and pterostilbene (PTE) with thioketal and incorporating cerium ions (Ce), creating Ce@D&P nanoparticles (NPs), which offer multitarget regulation of ferroptosis. The characteristics of Ce@D&P NPs are evaluated and their therapeutic effects on IL-1β-stimulated chondrocytes are verified. Results show that Ce@D&P NPs reduce ROS levels, mitigate inflammation, chelate iron to inhibit ferroptosis, and balance extracellular matrix (ECM) metabolism in chondrocytes. Mechanistically, transcriptomics and metabolomics analyses suggest that Ce@D&P NPs exerted their effects by regulating oxidative stress and lipid metabolism in chondrocytes. To better treat destabilization of the medial meniscus (DMM)-induced OA in mice, Ce@D&P NPs via intra-articular injection are delivered. The results show that Ce@D&P NPs alleviate cartilage matrix damage and slow OA progression. Overall, the findings indicate that Ce@D&P NPs represent a promising multitarget drug delivery system, and Ce@D&P NPs may be an effective strategy for OA treatment.

Exosomes of stem cells: a potential frontier in the treatment of osteoarthritis

The aging population has led to a global issue of osteoarthritis (OA), which not only impacts the quality of life for patients but also poses a significant economic burden on society. While biotherapy offers hope for OA treatment, currently available treatments are unable to delay or prevent the onset or progression of OA. Recent studies have shown that as nanoscale bioactive substances that mediate cell communication, exosomes from stem cell sources have led to some breakthroughs in the treatment of OA and have important clinical significance. This paper summarizes the mechanism and function of stem cell exosomes in delaying OA and looks forward to the development prospects and challenges of exosomes.

Interplay between lipid dysregulation and ferroptosis in chondrocytes and the targeted therapy effect of metformin on osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a devastating whole-joint disease affecting a large population worldwide; the role of lipid dysregulation in OA and mechanisms underlying targeted therapy effect of lipid-lowering metformin on OA remains poorly defined.

OBJECTIVES

To investigate the effects of lipid dysregulation on OA progression and to explore lipid dysregulation-targeting OA treatment of metformin.

METHODS

RNA-Seq data, biochemical, and histochemical assays in human and murine OA cartilage as well as primary chondrocytes were utilized to determine lipid dysregulation. Effects of metformin, a potent lipid-lowering medication, on ACSL4 expression and chondrocyte metabolism were determined. Further molecular experiments, including RT-qPCR, western blotting, flow cytometry, and immunofluorescence staining, were performed to investigate underlying mechanisms. Mice with intra-articular injection of metformin were utilized to determine the effects on ACLT-induced OA progression.

RESULTS

ACSL4 and 4-HNE expressions were elevated in human and ACLT-induced mouse OA cartilage and IL-1β-treated chondrocytes (P < 0.05). Ferrostatin-1 largely rescued IL-1β-induced MDA, lipid peroxidation, and ferroptotic mitochondrial morphology (P < 0.05). Metformin decreased the levels of OA-related genes (P < 0.05) and increased the levels of p-AMPK and p-ACC in IL-1β-treated chondrocytes. Intra-articular injection of metformin alleviated ACLT-induced OA lesions in mice, and reverted the percentage of chondrocytes positive for MMP13, Col2a1, ACSL4 and 4-HNE in ACLT mice (P < 0.05). Ferroptotic chondrocytes promoted the recruitment and chemotaxis of RAW264.7 cells via CCL2, which was blocked by metformin in vitro (P < 0.05).

CONCLUSION

We establish a critical role of polyunsaturated fatty acids metabolic process in OA cartilage degradation and define metformin as a potential OA treatment. Metformin reshapes lipid availability and ameliorates chondrocyte ferroptosis sensitivity via the AMPK/ACC pathway. In the future, gene-edited animals and extensive omics technologies will be utilized to reveal detailed lipids' involvement in cartilage lesions.

Ferroptosis in Osteoarthritis: Towards Novel Therapeutic Strategy

Osteoarthritis (OA) is a chronic, degenerative joint disease primarily characterised by damage to the articular cartilage, synovitis and persistent pain, and has become one of the most common diseases worldwide. In OA cartilage, various forms of cell death have been identified, including apoptosis, necroptosis and autophagic cell death. Ever-growing observations indicate that ferroptosis, a newly-discovered iron-dependent form of regulated cell death, is detrimental to OA occurrence and progression. In this review, we first analyse the pathogenetic mechanisms of OA by which iron overload, inflammatory response and mechanical stress contribute to ferroptosis. We then discuss how ferroptosis exacerbates OA progression, focusing on its impact on chondrocyte viability, synoviocyte populations and extracellular matrix integrity. Finally, we highlight several potential therapeutic strategies targeting ferroptosis that could be explored for the treatment of OA.

JP4-039 protects chondrocytes from ferroptosis to attenuate osteoarthritis progression by promoting Pink1/Parkin-dependent mitophagy

Background

Osteoarthritis (OA) is the most common degenerative joint disease, and its main pathological mechanism is articular cartilage degeneration. The purpose of this study was to investigate the role of mitophagy in the pathogenesis of chondrocyte ferroptosis in OA.

Methods

The expressions of ferroptosis related proteins (GPX4, FTH1, COX2) and ubiquitin-dependent mitophagy related proteins (PARKIN, PINK1) in the intact and injured areas of OA cartilage were analyzed. Nitro oxide JP4-039, a mitochondrial targeting antioxidant, has bifunctional role of targeting mitochondria. Then we evaluated the potential protective effect of JP4-039 in OA using the destabilization of medial meniscus (DMM)-induced OA model, as well as tert-butyl hydrogen peroxide (TBHP)-treated primary mouse chondrocytes and human cartilage explants.

Results

The concentrations of iron and lipid peroxidation and the expression of ferroptosis drivers in the damaged areas of human OA cartilages were significantly higher than those in the intact cartilage. Pink1/Parkin-dependent mitophagy decreased in the injured area of human OA cartilage and was negatively correlated with ferroptosis. Then, the toxicity and effectiveness of JP4-039 are tested to determine its working concentration. Next, at the molecular biological level, we found that JP4-039 showed the effect of anti-chondrocyte ferroptosis. Moreover, it was verified on DMM-induced OA model mice, that JP4-039 could delay the progression of OA. Finally, JP4-039 was re-verified in vivo and in vitro to inhibit chondrocyte ferroptosis and delay the progression of OA by promoting Pink1/Parkin-dependent mitophagy.

Conclusion

JP4-039 inhibits ferroptosis of chondrocytes by promoting Pink1/Parkin-dependent mitophagy and delays OA progression.

Quercetin attenuates the symptoms of osteoarthritis in vitro and in vivo by suppressing ferroptosis via activation of AMPK/Nrf2/Gpx4 signaling

Osteoarthritis (OA) is a common joint disorder involving the cartilage and other joint tissues. Quercetin (QCT) serves a protective role in the development of OA. However, to the best of our knowledge, the regulatory mechanisms of QCT in the progression of OA have not yet been fully elucidated. In order to mimic a model of OA in vitro, IL‑1β was used to stimulate chondrocytes. Furthermore, an in vivo animal model of OA was induced by anterior cruciate ligament transection (ACLT). 5‑Ethynyl‑2'‑deoxyuridine assays, TUNEL assays, ELISAs, western blotting and immunohistochemical assays were conducted to assess the chondroprotective properties of QCT in the development of OA. The results revealed that 100 µM QCT significantly promoted the proliferation, reduced the apoptosis and inflammation, and inhibited the extracellular matrix (ECM) degradation in IL‑1β‑stimulated chondrocytes. Additionally, QCT attenuated the IL‑1β‑induced ferroptosis of chondrocytes, as demonstrated by the reduced lipid reactive oxygen species and Fe2+ levels. Conversely, the inhibitory effects of QCT on the apoptosis and inflammatory responses were reversed by the activation of ferroptosis by erastin in IL‑1β‑stimulated chondrocytes. Furthermore, QCT significantly elevated the level of phosphorylated (p‑)5' AMP‑activated protein kinase (AMPK) and the levels of two negative regulators of ferroptosis [nuclear factor erythroid 2‑related factor 2 (Nrf2) and glutathione peroxidase 4 (Gpx4)] in IL‑1β‑stimulated chondrocytes. The AMPK inhibitor compound C notably reversed the promoting effects of QCT on phosphorylated‑AMPK, Nrf2 and Gpx4 expression in IL‑1β‑stimulated chondrocytes. Additionally, QCT markedly ameliorated the destruction and degradation of articular cartilage, and elevated the p‑AMPK, Nrf2 and Gpx4 levels in the mouse model of ACLT‑induced OA. Overall, the present study demonstrated that QCT inhibited the development of OA by suppressing ferroptosis via the activation of the AMPK/Nrf2/Gpx4 signaling pathway. These findings provide novel insights into the regulatory mechanisms of QCT for the treatment of patients with OA.

Chondrocyte Ferritinophagy as a Molecular Mechanism of Arthritis-A Narrative Review

Osteoarthritis (OA) is a prevalent joint disease affecting orthopedic patients. Its incidence is steadily increasing, causing great economic hardship for individuals and society as a whole. OA is connected with risk factors such as genetics, obesity, and joint diseases; yet, its pathophysiology is still largely understood. At present, several cell death pathways govern the initiation and advancement of OA. It has been discovered that the onset and progression of OA are strongly associated with pyroptosis, senescence, apoptosis, ferroptosis, and autophagy. Ferroptosis and autophagy have not been well studied in OA, and elucidating their molecular mechanisms in chondrocytes is important for the diagnosis of OA. For this reason, we aim was reviewed recent national and international developments and provided an initial understanding of the molecular pathways underlying autophagy and ferroptosis in OA. We determined the reference period to be the last five years by searching for the keywords "osteoarthritis, mechanical stress, Pizeo1, ferroptosis, autophagy, ferritin autophagy" in the three databases of PUBMED, Web of Science, Google Scholar. We then screened irrelevant literature by reading the abstracts. Ferroptosis is a type of programmed cell death that is dependent on reactive oxygen species and Fe2+. It is primarily caused by processes linked to amino acid metabolism, lipid peroxidation, and iron metabolism. Furthermore, Piezoelectric mechanically sensitive ion channel assembly 1 (PIEZO1), which is triggered by mechanical stress, has been revealed to be intimately associated with ferroptosis events. It was found that mechanical injury triggers changes in the intracellular environment of articular chondrocytes (e.g., elevated levels of oxidative stress and increased inflammation) through PIEZO1, ultimately leading to iron death in chondrocytes. Therefore, we believe that PIEZO1 is a key initiator protein of iron death in chondrocytes. Widely present in eukaryotic cells, autophagy is a lysosome-dependent, evolutionarily conserved catabolic process that carries misfolded proteins, damaged organelles, and other macromolecules to lysosomes for breakdown and recycling. Throughout OA, autophagy is activated to differing degrees, indicating that autophagy may play a role in the development of OA. According to recent research, autophagy is a major factor in the process that leads cells to ferroptosis. Despite the notion of ferritinophagy being put forth, not much research has been done to clarify the connection between ferroptosis and autophagy in OA.

Construction of a novel gene signature linked to ferroptosis in pediatric sepsis

Introduction

Pediatric sepsis is a complex and life-threatening condition characterized by organ failure due to an uncontrolled immune response to infection. Recent studies suggest that ferroptosis, a newly identified form of programmed cell death, may play a role in sepsis progression. However, the specific mechanisms of ferroptosis in pediatric sepsis remain unclear.

Methods

In this study, we analyzed microarray datasets from pediatric sepsis and healthy blood samples to identify ferroptosis-associated genes. A protein-protein interaction (PPI) network analysis and histological validation were performed to identify key genes. Additionally, immune infiltration analysis was conducted to explore the correlation between immune cells, immune checkpoint-related genes, and key genes. A competing endogenous RNA (ceRNA) network was constructed to investigate potential regulatory mechanisms involving long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and key ferroptosis-related genes.

Results

We identified 74 genes associated with ferroptosis in pediatric sepsis. Among them, five key genes (MAPK3, MAPK8, PPARG, PTEN, and STAT3) were confirmed through PPI network analysis and histological validation. Immune infiltration analysis revealed significant interactions between immune cells and key genes. The ceRNA network provided insights into the regulatory relationships between lncRNAs, miRNAs, and ferroptosis-related genes.

Discussion

These findings enhance our understanding of the role of ferroptosis in pediatric sepsis and highlight potential therapeutic targets for future research and clinical interventions.

Molecular Mechanisms of Immunoinflammatory Infiltration and Ferroptosis in Arthritis Revealed by a Combination of Bioinformatics and Single-Cell Analysis

Background

Osteoarthritis (OA) is a widespread chronic inflammatory disease in orthopedics, and its molecular mechanisms are still poorly understood.

Objective

The purpose of this work was to detect the immunological infiltration of OA and the manner of cell death utilizing bioinformatics and single-cell analysis in order to provide guidelines for clinical therapy and medicine.

Methods

Ferroptosis -associated genes were sourced from the ferroptosis Database, single-cell and bioinformatic expression profiles were chosen from the Gene Expression Comprehensive Database, and OA gene information was taken from GeneCards. To ascertain the categorization status of OA cells, single-cell analysis was conducted. Protein-protein interaction networks were established by SRING analysis, and functional enrichment was examined in the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases. The important proteins of immune-ferroptosis death in OA were elucidated through co-analysis. Last but not least, network pharmacology and molecular docking support the mechanism by which resveratrol controls Ferroptosis in OA.

Results

The development of OA was found to be tightly related to chondrocytes and immune cells, particularly T and macrophage cells, according to single-cell analysis profile. In patients with OA, immune infiltration also revealed a notable infiltration of T cells, B cells, NK cells, monocytes, and macrophages. The hub genes were shown to be enriched in immunological responses, chemokine-mediated signaling pathways, and inflammatory responses, according to enrichment analysis. The main signaling pathways included autophagy, ferroptosis, the HIF-1 signaling pathway, the PI3K-Akt signaling pathway, and the FoxO signaling pathway. Ferroptosis is a significant cell death mechanism that contributes to the advancement of osteoarthritis. Ferroptosis in chondrocytes is lessened by resveratrol regulation of GPX4, TFRC, and SLC7A11.

Conclusion

Various immune cell infiltrates, especially T cells and macrophages, play an important role in the progression of OA, and resveratrol ameliorates OA by modulating chondrocyte ferroptosis.

Exploration and verification of circulating diagnostic biomarkers in osteoarthritis based on machine learning

Background

Osteoarthritis (OA) is a prevalent chronic joint condition. This study sought to explore potential diagnostic biomarkers for OA and assess their relevance in clinical samples.

Methods

We searched the GEO database for peripheral blood leukocytes expression profiles of OA patients as a training set to conduct differentially expressed gene (DEG) analysis. Two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine-recursive feature elimination (SVM-RFE), were employed to identify candidate biomarkers for OA diagnosis. The performance was assessed using receiver operating characteristic (ROC) curves, and the areas under the curve (AUCs) with 95% confidence interval (CI) were calculated. Furthermore, we gathered clinical peripheral blood samples from healthy donors and OA patients (validation set) to validate our findings. Small interfering RNA and CCK8 proliferation assay were used for experimental verification.

Results

A total of 31 DEGs were discovered, and the machine learning screening found five DEGs that were considered to be candidate biomarkers. Notably, BIRC2 had a very good discriminatory effect among the five candidate biomarkers, with an AUC of 0.814 (95% CI: 0.697-0.915). In our validation set, results showed that the levels of BIRC2 and SEH1L were remarkably higher in healthy donors than OA patients, consistent with the results of the training set. SEH1L owned the largest AUC of 0.964 (95% CI: 0.855-1.000). BIRC2 also displayed a larger AUC of 0.836 (95% CI: 0.618-1.000) in the training set. Knockdown of these two genes could significantly suppress human chondrocyte proliferation.

Conclusion

Two novel biomarkers, SEH1L and BIRC2, were indicated to have the capacity to differentiate healthy people from OA patients at the peripheral level. Experiments have shown that knockdown of these two genes could inhibit human chondrocyte proliferation, as verified by cell proliferation assays.

Mechanisms and Therapeutic Potential of GPX4 in Pain Modulation

Pain, a complex symptom encompassing both sensory and emotional dimensions, constitutes a significant global public health issue. Oxidative stress is a pivotal factor in the complex pathophysiology of pain, with glutathione peroxidase 4 (GPX4) recognized as a crucial antioxidant enzyme involved in both antioxidant defense mechanisms and ferroptosis pathways. This review systematically explores GPX4's functions across various pain models, including neuropathic, inflammatory, low back, and cancer-related pain. Specifically, the focus includes GPX4's physiological roles, antioxidant defense mechanisms, regulation of ferroptosis, involvement in signal transduction pathways, and metabolic regulation. By summarizing current research, we highlight the potential of GPX4-targeted therapies in pain management.

Identification and Validation of Pivotal Genes in Osteoarthritis Combined with WGCNA Analysis

Introduction

The prevalence of osteoarthritis (OA), the most common chronic joint condition, is increasing due to the aging population and escalating obesity rates, leading to a significant impact on human health and well-being. Thus, analyzing the key targets of OA through bioinformatics can help discover new biomarkers to improve its diagnosis.

Methods

The microarray and RNA-seq results were screened from the Gene Expression Omnibus (GEO) database. Functional enrichment analyses, protein-protein interaction (PPI) analysis, and weighted gene co-expression network analysis (WGCNA) of the DEGs were performed. RT-qPCR and WB were further performed to verify the hub gene expression in OA rat.

Results

In this study, 35 key genes were identified through differential expression analysis and weighted gene co-expression network analysis (WGCNA) using the GSE169077 and GSE114007 datasets. Enrichment analysis revealed that these key genes were predominantly enriched in the HIF-1 signaling pathway, ECM-receptor interaction, and FoxO signaling pathway. Through the integration of protein-protein interaction (PPI) analysis, validation in animal models and ROC curve analysis, four pivotal genes (GADD45B, CLDN5, HILPDA and CDKN1B) were finally identified.

Conclusion

In conclusion, these identified key genes could serve as novel targets for predicting and treating OA, offering fresh insights into its etiology and pathogenesis.

Selenomethionine alleviates T-2 toxin-induced articular chondrocyte ferroptosis via the system Xc-/GSH/GPX4 axis

T-2 toxin can induce bone and cartilage development disorder, and oxidative stress plays an important role in it. It is well known that selenomethionine (Se-Met) has antioxidative stress properties and promotes the repair of cartilage lesion, but it remains unclear whether Se-Met can relieve damaged cartilage exposure to T-2 toxin. Here, the oxidative stress and ferroptosis of chondrocytes exposure to T-2 toxin were observed. Mechanistically, T-2 toxin increased ROS, lipid ROS, MDA and Fe2+ contents in chondrocytes, decreased GSH and GPX4 activity, and inhibited the system Xc-/GSH/GPX4 antioxidant axis. In addition, the mitochondria of chondrocytes shrunk and the mitochondrial crest decreased or disappeared. However, Fer-1 (Ferrostatin-1) inhibited ferroptosis induced by T-2 toxin in chondrocytes. The Se-Met alleviated lipid peroxidation, oxidative stress, and damaged mitochondrial in T-2 toxin-infected chondrocytes, enhanced antioxidant enzyme activity, and activated the system Xc-/GSH/GPX4 axis, thereby antagonizing ferroptosis of chondrocytes and alleviating articular cartilage damage. In conclusion, our findings highlight the essentiality of ferroptosis in chondrocyte caused by T-2 toxin, elucidate how Se-Met offers protection against this injury and provide research evidence for the drug treatment target of Kashin-Beck disease.

Inhibition of ASIC1a reduces ferroptosis in rheumatoid arthritis articular chondrocytes via the p53/NRF2/SLC7A11 pathway

The activation of acid-sensing ion channel 1a (ASIC1a) in response to extracellular acidification leads to an increase in extracellular calcium influx, thereby exacerbating the degeneration of articular chondrocytes in rheumatoid arthritis (RA). It has been suggested that the inhibition of extracellular calcium influx could potentially impede chondrocyte ferroptosis. The cystine transporter, solute carrier family 7 member 11 (SLC7A11), is recognized as a key regulator of ferroptosis. Recent studies suggest that the tumor suppressor gene p53 facilitates the induction of ferroptosis by suppressing the upregulation of SLC7A11. This process is mediated by the nuclear factor erythroid 2-related factor 2 (NRF2), a key transcription factor integral to the maintenance of cellular redox homeostasis and the regulation of inflammatory responses. This study aims to investigate the role of ASIC1a in the ferroptosis of RA chondrocytes and to determine the involvement of the p53/NRF2/SLC7A11 pathway in its underlying mechanism. In vitro experiments revealed that acidosis induces ferroptosis and reduces the expression of NRF2 and SLC7A11 in chondrocytes. Moreover, acidification significantly increased p53 protein levels in chondrocytes. Pifithrin-α (PFN-α), a p53 inhibitor, mitigated acidosis-induced ferroptosis and restored the diminished expression of NRF2 and SLC7A11. Furthermore, PcTx-1, an ASIC1a inhibitor, inhibited acidification-induced ferroptosis, enhanced the protein levels of SLC7A11 and NRF2, and reduced p53 expression. In vivo experiments demonstrated that the ASIC1a-specific inhibitor PcTx-1 ameliorated histopathological characteristics of ankle joints in collagen-induced arthritis (CIA) mice, decreased p53 expression, and enhanced NRF2 and SLC7A11 expression in chondrocytes. These findings suggest that ASIC1a inhibition may mitigate acidification-induced ferroptosis in articular chondrocytes in RA, potentially via the p53/NRF2/SLC7A11 pathway.

Therapeutic Potential of Targeting Ferroptosis in Periprosthetic Osteolysis Induced by Ultra-High-Molecular-Weight Polyethylene Wear Debris

Background/Objectives: Periprosthetic osteolysis is the primary cause of arthroplasty failure in the majority of patients. Mechanistically, wear debris released from the articulating surfaces of a prosthesis initiates local inflammation and several modes of regulated cell death programs, such as ferroptosis, which represents a promising therapeutic target in various chronic inflammatory diseases. Thus, the current study aimed at exploring the therapeutic potential of targeting ferroptosis in a polyethylene-wear-debris-induced osteolysis model. Methods: Inverted cell culture model was used for stimulating the cells with wear debris in vitro, and calvarial osteolysis model was used for evaluating the therapeutic effects of inhibitors in vivo. Results: The immunostaining of periprosthetic bone tissues demonstrated a number of osteocytes expressing ferroptosis markers. Likewise, the expressions of ferroptosis markers were confirmed in polyethylene-wear-debris-stimulated osteocyte-like cells and primary osteoblasts in a direct stimulation model but not in an indirect stimulation model. Furthermore, polyethylene wear debris was implanted onto calvarial bone and mice were treated with the ferroptosis inhibitors DFO and Fer-1. These treatments alleviated the inflammatory and pathological bone resorption induced by the wear debris implantation. Conclusions: Our data broaden the knowledge of the pathogenesis of periprosthetic osteolysis and highlight ferroptosis as a promising therapeutic target.

M13, an anthraquinone compound isolated from Morinda officinalis alleviates the progression of the osteoarthritis via the regulation of STAT3

BACKGROUND

Osteoarthritis (OA) is characterized by the progressive deterioration of articular cartilage, leading to joint pain and functional impairment. OA severely impacts quality of life and presents a substantial societal burden. Currently, effective treatment options remain limited. Morinda officinalis (MO), a traditional Chinese herb, is commonly used to treat rheumatoid arthritis and alleviate joint pain. M13, an anthraquinone extracted from MO, has shown significant anti-inflammatory properties, making it a promising candidate for the treatment of OA. However, its role in inhibiting OA progression and the mechanisms involved remain poorly understood.

PURPOSE

The objective of this study is to examine the impact of M13 on osteoarthritis and uncover the mechanisms.

METHODS

The effects of M13 on OA were assessed using TNF-α induced chondrocyte models and mice with destabilization of the medial meniscus (DMM). Celecoxib was used as a positive control. We evaluated the expression of factors related to chondrocyte degeneration and inflammation through qRT-PCR, immunoblotting, and immunofluorescence. Chondrocyte viability was measured using CCK-8 assays, EdU staining, and flow cytometry. Molecular docking, molecular dynamics simulations and isothermal titration calorimetry (ITC) were performed to evaluate the binding efficacy of target proteins. Additionally, the therapeutic effects of M13 in OA mice were confirmed through in vivo experiments.

RESULTS

In primary murine chondrocytes, M13 rescued TNF-α-induced matrix degradation and loss of vitality while suppressing ROS generation. Mechanistically, STAT3 was identified as a target protein of M13, through which M13 mitigated OA by inhibiting the STAT3 signaling pathway. Further in vivo experiments demonstrated that M13 reduced the scores of the Osteoarthritis Research Society International (OARSI), alleviating cartilage impairment. M13 enhanced levels of collagen II and aggrecan in cartilage tissue while decreasing the amounts of cartilage-degrading proteins ADAMTS-5 and MMP13.

CONCLUSION

This is the first study to validate that M13 mitigates the inflammation and damage in cartilage tissue by blocking the STAT3 signaling pathway. These findings hold promise for enhancing innovative clinical interventions targeting OA.

Ferroptosis meets microRNAs: A new frontier in anti-cancer therapy

Ferroptosis is an iron-dependent lipid peroxidation-mediated cell death. It is distinct from other types of cellular death and is recognized as a potential target for cancer therapy. This review discusses the mechanisms of ferroptosis, including its induction and inhibition pathways, its role in lipid metabolism, and its connection to various signaling pathways. We also explored the relationship between microRNAs and ferroptosis, highlighting the potential role of miRNAs targeting genes involved in ferroptosis. Role of miRNAs in metabolic reprogramming during carcinogenesis is well documented. We have discussed the role of miRNAs regulating expression of genes involved in iron metabolism, lipid metabolism, and redox metabolism which are associated with regulation of ferroptosis. In conclusion, we addressed various opportunities and challenges identified in ferroptosis research and its clinical implementation stressing the necessity of customized treatment plans based on each patient's unique vulnerability to the disease. Our article provides a complete overview of microRNAs and ferroptosis, with possible implications for cancer therapy.

Sarsasapogenin stimulates angiogenesis and osteogenesis coupling to treat estrogen deficiency-induced osteoporosis by activating the GPX4/SLIT3/ROBO1 axis

BACKGROUND

Promoting the coupling of osteogenesis and angiogenesis is a crucial strategy for the treatment of postmenopausal osteoporosis (PMOP). Estrogen deficiency induces ferroptosis, which is closely associated with the pathophysiology of PMOP. Sarsasapogenin (SAR) is a natural sapogenin with anti-oxidative effects. However, it is unclear whether SAR has a protective role against the impaired osteogenesis and angiogenesis coupling in PMOP. In this study, we evaluated the efficacy of SAR in estrogen deficiency-induced osteoporosis and explored the underlying mechanisms.

METHODS

Bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) were utilized to assess the in vitro effects of SAR on the coupling of osteogenesis and angiogenesis. In vivo experiments involved bilateral ovariectomy (OVX)-induced osteoporosis in mice and glutathione peroxidase 4 (GPX4)-knockout (KO) mice. Mice were orally administered SAR (5 or 10 mg/kg/d) for a duration of 12 weeks. The direct target of SAR was investigated through molecular docking, a cellular thermal shift assay, and surface plasmon resonance. Additionally, RNA sequencing was employed to elucidate the underlying mechanisms.

RESULTS

SAR treatment improved cell viability and osteogenic differentiation while inhibiting ferroptosis in iron dextran-induced BMSCs. Furthermore, SAR enhanced the production of slit guidance ligand 3 (SLIT3) in these cells, which stimulated angiogenesis by activating its receptor, roundabout human homolog 1 (ROBO1), in HUVECs. An in vitro model of ferroptosis induced by erastin demonstrated that SAR promoted the coupling of osteogenesis and angiogenesis by upregulating the BMSCs-SLIT3/HUVECs-ROBO1 axis. Activation of GPX4 was identified as a contributing factor to the effects of SAR on this coupling. Transfection of GPX4 small interfering RNA (siRNA) in BMSCs negated the impact of SAR on the BMSCs-SLIT3/HUVECs-ROBO1 axis. Additionally, SAR was found to directly interact with GPX4, enhancing protein stability, with an equilibrium dissociation constant of 44.6 μM. Notably, SAR did not increase SLIT3, ROBO1, or indicators of osteogenesis or angiogenesis in GPX4-KO mice.

CONCLUSIONS

These findings underscore the significance of restoring the GPX4/SLIT3/ROBO1 axis in promoting the coupling of angiogenesis and osteogenesis. SAR mitigates PMOP, in part, by activating the BMSCs-SLIT3/HUVECs-ROBO1 axis, with GPX4 serving as an upstream signaling modulator responsible for SLIT3 production. Our observations provide experimental evidence supporting the clinical application of SAR in the treatment of PMOP.

Transcriptomic Analysis and Experimental Verification of Ferroptosis Signature Genes in Osteoarthritis

Osteoarthritis is a systemic disease that primarily damages articular cartilage and also affects the synovium, ligaments, and bone tissues. The key mechanisms involved are chondrocyte death and degradation of the extracellular matrix. This study aims to identify differentially expressed genes (DEGs) associated with ferroptosis and investigate their roles in the development of osteoarthritis. We used several methods, such as transcriptomic data analysis, gene enrichment analysis, protein-protein interaction network construction, animal model experiments, and immune cell infiltration analysis. Our examination of the GSE114007 dataset uncovered 2614 DEGs, including 1300 that were upregulated and 1314 that were downregulated. From these, we identified eight ferroptosis-related DEGs (FRGs-DEGs). Functional enrichment analysis showed that these genes are significant for cellular migration and tissue remodeling. They are particularly involved in the HIF-1 and PPAR signaling pathways. Additionally, our immune cell infiltration analysis indicated an increase in M0 and M2 macrophages in osteoarthritis samples, while levels of eosinophils and memory B cells were notably decreased. The receiver operating characteristic curve analysis identified GJA1, TIMP Metallopeptidase Inhibitor 1 (TIMP1), and DPP4 as potential biomarkers for osteoarthritis diagnosis, with area under the curve of 0.91, 0.85, and 0.83, respectively. Moreover, RT-qPCR validation in an osteoarthritis rat model confirmed the upregulation of TIMP1, supporting our bioinformatics results. In summary, our study identifies key FRGs-DEGs and their potential roles in osteoarthritis. This research provides new insights into the disease's molecular mechanisms and suggests innovative therapeutic targets for clinical intervention. Future research should aim to include larger patient cohorts and clinical validation to improve the applicability of these findings.

Ferroptosis in hepatocellular carcinoma: Mechanisms and therapeutic implications

Ferroptosis is a novel form of oxidative cell death, in which highly expressed unsaturated fatty acids on the cell membrane are catalyzed by divalent iron or ester oxygenase to promote liposome peroxidation. This process reduces cellular antioxidant capacity, increases lipid reactive oxygen species, and leads to the accumulation of intracellular ferrous ions, which disrupts intracellular redox homeostasis and ultimately causes oxidative cell death. Studies have shown that ferroptosis induces an immune response that has a dual role in liver disease, ferroptosis also offers a promising strategy for precise cancer therapy. Ferroptosis regulators are beneficial in maintaining cellular homeostasis and tissue health, have shown efficacy in treating diseases of the hepatic system. However, the mechanisms of action and molecular regulatory pathways of ferroptosis in hepatocellular carcinoma (HCC) have not been fully elucidated. Therefore, deciphering the role of ferroptosis and its mechanisms in HCC progression is crucial for treating the disease. In this review, we introduce the morphological features and biochemical functions of ferroptosis, outline the molecular regulatory pathways of ferroptosis, and highlights the therapeutic potential of ferroptosis inhibitors and modulators to target it in HCC.

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.