Taxifolin-mediated Nrf2 activation ameliorates oxidative stress and apoptosis for the treatment of glucocorticoid-induced osteonecrosis of the femoral head

Taxifolin mitigates cisplatin-induced testicular damage by reducing inflammation, oxidative stress, and apoptosis in mice

Cisplatin (CIS) is effective against various cancers but causes significant side effects, including testicular damage. This study investigated the effects of taxifolin (TX), a potent flavonoid with well-known benefits, against CIS-induced testicular injury. Mice received TX (25 and 50 mg/kg) orally for 14 days, with a single injection of CIS (7 mg/kg) on day 8. CIS significantly impaired sperm parameters (motility, viability, and count) and caused notable histopathological alterations in testicular tissue. CIS-treated testicular tissue exhibited elevated MDA and protein carbonyl levels, alongside decreased antioxidant defenses, including GSH, SOD, and catalase activities. TX significantly mitigated the deterioration of sperm parameters and prevented testicular tissue damage. It also restored antioxidant levels and reduced MDA and protein carbonyl contents. Furthermore, CIS elevated pro-inflammatory markers (NF-κB p65, TNF-α, and IL-1β) and apoptosis markers (Bax and caspase-3), while reducing anti-apoptotic Bcl-2 levels. TX effectively suppressed NF-κB activation, reduced pro-inflammatory cytokine production, and inhibited apoptosis in CIS-treated mice. Overall, TX alleviated CIS-induced oxidative stress, inflammation, apoptosis, and testicular damage, thereby improving sperm quality. These findings emphasize TX's potential as a protective agent against CIS-induced testicular damage and warrant further research in human applications.

Knockdown of lncRNA XR_877193.1 suppresses ferroptosis and promotes osteogenic differentiation via the PI3K/AKT signaling pathway in SONFH

Ferroptosis is a novel form of regulated cell death characterized by the iron-dependent accumulation of lipid peroxides. Recent research has suggested that ferroptosis in osteoblasts contributes to steroid-induced osteonecrosis of the femoral head (SONFH). However, the relationship between ferroptosis and SONFH remains unclear. In this study, in vitro experiments show that dexamethasone (Dex) treatment reduces the expressions of key ferroptosis regulators, SLC7A11 and GPX4, in MC3T3-E1 cells. This reduction leads to a decrease in intracellular glutathione (GSH) levels, accompanied by elevated levels of total iron, malondialdehyde (MDA), and reactive oxygen species (ROS). Importantly, the ferroptosis inhibitor ferrostatin-1 (Fer-1) effectively reverses Dex-induced ferroptosis in MC3T3-E1 cells. Furthermore, RNA-seq analysis reveals that the long noncoding RNA (lncRNA) XR_877193.1is significantly upregulated in Dex-treated MC3T3-E1 cells. Functional studies demonstrate that the knockdown of lncRNA XR_877193.1 promotes osteogenic differentiation by inhibiting Dex-induced ferroptosis in MC3T3-E1 cells, whereas its overexpression exacerbates cell death via ferroptosis. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis reveals that the differentially expressed lncRNA XR_877193.1 is enriched in ferroptosis-related pathways, including the PI3K/AKT signaling pathway. Moreover, PI3K/AKT inhibitors reverse ferroptosis in MC3T3-E1 cells inhibited by lncRNA XR_877193.1 knockdown. Collectively, our findings indicate that lncRNA XR_877193.1 knockdown exerts anti-ferroptosis effects by stimulating the PI3K/AKT signaling pathway, suggesting a promising therapeutic strategy for attenuating SONFH.

Mechanistic Insights into Salvigenin for Glucocorticoid-Induced Femoral Head Osteonecrosis: A Network Pharmacology and Experimental Study

Background/Objectives: Glucocorticoid-induced osteonecrosis of the femoral head (GIOFH) is a debilitating condition resulting from impaired bone metabolism and vascular disruption due to prolonged glucocorticoid use. This study aimed to explore the therapeutic potential of salvigenin, a flavonoid with antioxidative and estrogen-like properties, in alleviating GIOFH by modulating estrogen receptor alpha (ESR1) pathways. Methods: A network pharmacology approach was utilized to identify salvigenin's potential targets and their association with GIOFH. Protein-protein interaction networks, along with Gene Ontology and KEGG pathway analyses, were conducted to clarify salvigenin's multi-target mechanisms. Molecular docking and dynamics simulations assessed the interaction between salvigenin and ESR1. Experimental validation included in vitro assays on MG63 cells treated with dexamethasone (Dex) to mimic GIOFH, evaluating oxidative stress, apoptosis, osteogenic differentiation, and ESR1 expression. Results: Network analysis identified ESR1, NOS3, and MMP9 as key hub targets of salvigenin. Molecular docking and dynamics simulations confirmed stable binding of salvigenin to ESR1. Salvigenin significantly reduced Dex-induced oxidative stress and apoptosis in osteoblasts while restoring osteogenic differentiation and ESR1 expression. Functional assays showed improved mineralized nodule formation, ALP activity, and mitochondrial integrity in salvigenin-treated cells. Conclusions: Salvigenin exhibits significant therapeutic potential in addressing GIOFH through ESR1-mediated pathways. These results offer a strong foundation for future translational studies and the development of salvigenin-based therapies for glucocorticoid-induced bone disorders.

Hip joint-preserving strategies for treating osteonecrosis of the femoral head: From nonoperative to operative procedures

Osteonecrosis of the femoral head (ONFH) has an exceedingly high prevalence and disability rate, causing a tremendous socioeconomic burden. The prevalence of ONFH is increasing, while the population of the patients with ONFH is becoming younger. Once the femoral head collapses, treatment becomes difficult and often requires a hip joint replacement, which is not favorable for young patients. Therefore, hip joint-preserving treatments at an early stage of ONFH are particularly important. This study provides a comprehensive review on hip-preserving strategies for treating ONFH, including nonoperative treatments (e.g., protective weight bearing, hyperbaric oxygen, pulsed electromagnetic, extracorporeal shockwave, bisphosphonate, anticoagulants, hypolipidemics, vasodilators, and traditional Chinese medicine) and operative treatments (e.g., core decompression, osteotomy, bone grafting, mesenchymal stem cell transplantation, tantalum rods, and tissue engineering). Nonoperative treatments aim to slow down the progression of the disease and delay the need for joint replacement; however, they usually cannot effectively prevent the progression of the disease, except in cases of small necrosis areas (<10 %). Additionally, nonoperative treatments have unclear mechanisms that require further investigation. In contrast, operative treatments may stop the negative outcomes of necrosis and therefore appear to be more promising. Currently, an emerging area in operative treatments is regenerative medicine, which could promote the generation of bone tissues and blood vessels and restore hip joint function to pre-necrotic levels as much as possible. This review seeks to not only provide an important reference for clinicians when choosing appropriate strategies for treating ONFH but also offer certain guidance for future basic research in developing ONFH treatments.

The translational potential of this article

The incidence of ONFH is increasing, and patients are becoming younger on average. Therefore, the development of hip joint-preserving strategies to treat ONFH at earlier stages is urgently needed, particularly for young patients. However, a comprehensive review is lacking regarding the currently-available hip joint-preserving strategies and their effectiveness. This study is motivated to fill this gap and serve as an important reference for clinicians in choosing appropriate strategies to treat ONFH.

Astaxanthin Prevents Glucocorticoid-Induced Femoral Head Osteonecrosis by Targeting Ferroptosis through the JAK2/STAT3 Signaling Pathway

Glucocorticoid (GC) is extensively used in clinical practice, and the osteonecrosis of the femoral head caused by them is a common issue in orthopedic surgery, yet the underlying mechanisms remain unclear. Astaxanthin (AST), a potent natural antioxidant, has an unexplored impact on GC-induced osteonecrosis of the femoral head (GIONFH). This study explores the effects and mechanisms of AST in counteracting dexamethasone (Dex)-induced ferroptosis and GIONFH. We developed a rat model of GIONFH using intraperitoneal Dex injections and conducted in vitro analysis by culturing osteoblasts (OBs) with Dex treatment. We assessed the impact of AST on Dex-treated OBs using C11-BODIPY and FerroOrange staining, mitochondrial functionality tests, and protein expression analyses through Western blot and immunofluorescence. The influence of AST on bone microarchitecture of femoral head in rat was assessed using micro-CT, hematoxylin and eosin staining, immunofluorescence, and immunohistochemistry at imaging and histological levels. Our findings suggest that AST exerts an inhibitory effect on Dex-induced ferroptosis and GIONFH. In vitro, AST treatment increased glutathione and decreased malondialdehyde, lipid peroxidation, and mitochondrial-reactive oxygen species. Additionally, AST treatment also enhances the phosphorylation of STAT3, upregulates glutathione peroxidase 4 and osteogenic-related proteins, and stimulates bone formation. To delve deeper into the mechanism, the findings revealed that AST triggered activation of JAK2/STAT3 signaling. Moreover, the use of siRNA-STAT3 blocked the beneficial effect of AST in OBs cultivated with Dex. In brief, AST combats GIONFH by activating the JAK2/STAT3 pathway to inhibit ferroptosis.

Biomimetic Extracellular Vesicles Based on Composite Bioactive Ions for the Treatment of Ischemic Bone Disease

Extracellular vesicles (EVs) have demonstrated considerable potential in the treatment of ischemic bone diseases, such as glucocorticoid-induced osteonecrosis of the femoral head (GIONFH). However, the clinical application of EVs faces challenges such as low yield, poor bioactivity, and lack of targeting. Herein, we have developed a platform of multiengineered extracellular vesicle mimetics (EVMs) to address these challenges. By stimulating mesenchymal stem cells (MSCs) with multibioactive ions from TS (Trisilicate, a mixture of calcium silicate, magnesium silicate, and strontium silicate), we obtained endogenously modified TS-MSCs. From these, we further prepared a large quantity of bioactive EVMTS-MSCs through a straightforward extrusion method. Moreover, by integrating metabolic glycoengineering with click chemistry strategies, alendronate (ALN) was surface-modified on EVMTS-MSCs to further prepare ALN-EVMTS-MSCs. The engineered ALN-EVMTS-MSCs demonstrated bone-targeting effects, promoting osteogenesis and angiogenesis. This promoting effect is attributed to the rich presence of miR-21 in the TS-modified EVM, which further silences PTEN to activate the PI3K/AKT signaling pathway, thereby enhancing osteogenesis and angiogenesis. Our treatment strategy for ischemic bone diseases is based on a multiengineered, biomaterial-inspired, metabolic glycoengineering, and click chemistry-based platform of EVM. This study also provides an enhanced understanding of the development and application of engineered vesicles in disease treatment.

Taxifolin attenuates hepatic ischemia-reperfusion injury by enhancing PINK1/Parkin-mediated mitophagy

BACKGROUND

Hepatic ischemia-reperfusion (I/R) injury stands as a recurring clinical challenge in liver transplantation, leading to mitochondrial dysfunction and cellular imbalance. Mitochondria, crucial for hepatocyte metabolism, are significantly damaged during hepatic I/R and the extent of mitochondrial damage correlates with hepatocyte injury. PINK1/Parkin-mediated mitophagy, is a specialized form of cellular autophagy, that maintains mitochondrial quality by identifying and removing damaged mitochondria, thereby restoring cellular homeostasis. Taxifolin (TAX), a natural flavonoid, possesses antioxidant, anti-inflammatory and anticancer properties. This study aimed at investigating the effects of TAX on hepatic I/R and the underlying mechanisms.

METHODS

C57BL/6 mice were pretreated with TAX or vehicle control, followed by 60 min of 70% hepatic ischemia. After 6 h of reperfusion, the mice were euthanized. In vitro, TAX-pretreated primary hepatocytes were subjected to oxygen glucose deprivation/reperfusion (OGD/R).

RESULTS

Hepatic I/R caused mitochondrial damage and apoptosis in hepatocytes, but TAX pretreatment mitigated these effects by normalizing mitochondrial membrane potential and inhibiting reducing apoptotic protein expression. TAX exerted its protective effects by enhancing mitophagy via the PINK1/Parkin pathway. Moreover, silencing the PINK1 gene in primary hepatocytes reversed the beneficial effects of TAX.

CONCLUSION

The results of the study demonstrate that promoting mitophagy through the PINK1/Parkin pathway restores mitochondrial function and protects the liver from I/R, suggesting that it may have therapeutic potential for the treatment of hepatic I/R.

Inhibition of protein disulfide isomerase mitigates steroid-induced osteonecrosis of the femoral head by suppressing osteoclast activity through the reduction of cellular oxidative stress

Osteonecrosis of the femoral head (ONFH) is a devastating and irreversible hip disease usually associated with increased oxidative stress due to the clinical application of high-dose or long-term glucocorticoids (GCs). Previous publications have demonstrated protein disulfide isomerase (PDI) plays a critical role in regulating cellular production of reactive oxygen species (ROS). We therefore ask whether interfering PDI could affect GCs-stimulated osteoclastogenesis. To test the hypothesis, we conducted bioinformatics and network analysis based on potential gene targets of steroid-induced osteonecrosis of the femoral head (SIONFH) in light of multiple databases and concomitantly verified the associated biological effect via the in vitro model of dexamethasone (DEX)-stimulated osteoclastogenesis. The results revealed 70 potential gene targets for SIONFH intervention, including the P4HB gene that encodes PDI. Further analysis based on network topology-based analysis techniques (NTA), protein-protein interaction (PPI) networks, and mouse cell atlas database identified the importance of PDI in regulating the cellular redox state of osteoclast during ONFH. Western blotting (WB) validations also indicated that PDI may be a positive regulator in the process of DEX-stimulated osteoclastogenesis. Hence, various PDI inhibitors were subjected to molecular docking with PDI and their performances were analyzed, including 3-Methyltoxoflavin (3 M) which inhibits PDI expression, and ribostamycin sulfate (RS) which represses PDI chaperone activity. The binding energies of DEX, 3 M, and RS to PDI were -5.3547, -4.2324, and -5.9917 kcal/mol, respectively. The Protein-Ligand Interaction Profiler (PLIP) analysis demonstrated that both hydrogen bonds and hydrophobic interactions were the key contributions to the DEX-PDI and 3M-PDI complexes, while only hydrogen bonds were identified as the predominant driving forces in the RS-PDI complex. Subsequent experiments showed that both 3 M and RS reduced osteoclast differentiation and bone resorption activity by stifling the expression of osteoclastic markers. This reduction was primarily due to the PDI inhibitors boosting the antioxidant system, thereby reducing the production of intracellular ROS. In conclusion, our results supported PDI's involvement in SIONFH progression by regulating ROS in osteoclasts and highlighted PDI inhibitors may serve as potential options for SIONFH treatment.

Nerol mitigates dexamethasone-induced skin aging by activating the Nrf2 signaling pathway in human dermal fibroblasts

Collagen and hyaluronic acid are essential components of the dermis that collaborate to maintain skin elasticity and hydration due to their unique biochemical properties and interactions within the extracellular matrix. Prolonged exposure to glucocorticoids can induce skin aging, which manifests as diminished collagen content and hyaluronic acid levels in the dermis. Nerol, a monoterpene alcohol found in essential oils, was examined in this study for its potential to counteract glucocorticoid-induced skin aging and the underlying mechanism behind its effects. Our findings reveal that non-toxic concentrations of nerol treatment can reinstate collagen content and hyaluronic acid levels in human dermal fibroblasts treated with dexamethasone. Mechanistically, nerol mitigates dexamethasone-induced oxidative stress by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. The protective effects of nerol were significantly abrogated when the Nrf2 pathway was inhibited using the specific inhibitor ML385. In conclusion, nerol protects human dermal fibroblasts against glucocorticoid-induced skin aging by ameliorating oxidative stress via activation of the Nrf2 pathway, thereby highlighting its potential as a therapeutic agent for preventing and treating glucocorticoid-induced skin aging.

Inhibition of insulin degrading enzyme suppresses osteoclast hyperactivity via enhancing Nrf2-dependent antioxidant response in glucocorticoid-induced osteonecrosis of the femoral head

BACKGROUND

Osteoclast hyperactivation due to the pathological overproduction of reactive oxygen species (ROS) stimulated by glucocorticoids (GCs) is one of the key drivers behind glucocorticoid-induced osteonecrosis of the femoral head (GIONFH). The insulin degrading enzyme (IDE), a conserved Zn2+ metallo-endopeptidase, facilitates the DNA binding of glucocorticoid receptor and plays a substantial role in steroid hormone-related signaling pathways. However, the potential role of IDE in the pathogenesis of GIONFH is yet undefined.

METHODS

In this study, we employed network pharmacology and bioinformatics analysis to explore the impact of IDE inhibition on GIONFH with 6bK as an inhibitory agent. Further evidence was collected through in vitro osteoclastogenesis experiments and in vivo evaluations involving methylprednisolone (MPS)-induced GIONFH mouse model.

RESULTS

Enrichment analysis indicated a potential role of 6bK in redox regulation amid GIONFH development. In vitro findings revealed that 6bK could attenuate GCs-stimulated overactivation of osteoclast differentiation by interfering with the transcription and expression of key osteoclastic genes (Traf6, Nfatc1, and Ctsk). The use of an H2DCFDA probe and subsequent WB assays introduced the inhibitory effects of 6bK on osteoclastogenesis, linked with the activation of the nuclear factor erythroid-derived 2-like 2 (Nrf2)-mediated antioxidant system. Furthermore, Micro-CT scans validated that 6bK could alleviate GIONFH in MPS-induced mouse models.

CONCLUSIONS

Our findings suggest that 6bK suppresses osteoclast hyperactivity in GCs-rich environment. This is achieved by reducing the accumulation of intracellular ROS via promoting the Nrf2-mediated antioxidant system, thus implying that IDE could be a promising therapeutic target for GIONFH.

Antiplatelet Effects of Flavonoid Aglycones Are Mediated by Activation of Cyclic Nucleotide-Dependent Protein Kinases

Flavonoid aglycones are secondary plant metabolites that exhibit a broad spectrum of pharmacological activities, including anti-inflammatory, antioxidant, anticancer, and antiplatelet effects. However, the precise molecular mechanisms underlying their inhibitory effect on platelet activation remain poorly understood. In this study, we applied flow cytometry to analyze the effects of six flavonoid aglycones (luteolin, myricetin, quercetin, eriodictyol, kaempferol, and apigenin) on platelet activation, phosphatidylserine externalization, formation of reactive oxygen species, and intracellular esterase activity. We found that these compounds significantly inhibit thrombin-induced platelet activation and decrease formation of reactive oxygen species in activated platelets. The tested aglycones did not affect platelet viability, apoptosis induction, or procoagulant platelet formation. Notably, luteolin, myricetin, quercetin, and apigenin increased thrombin-induced thromboxane synthase activity, which was analyzed by a spectrofluorimetric method. Our results obtained from Western blot analysis and liquid chromatography-tandem mass spectrometry demonstrated that the antiplatelet properties of the studied phytochemicals are mediated by activation of cyclic nucleotide-dependent signaling pathways. Specifically, we established by using Förster resonance energy transfer that the molecular mechanisms are, at least partly, associated with the inhibition of phosphodiesterases 2 and/or 5. These findings underscore the therapeutic potential of flavonoid aglycones for clinical application as antiplatelet agents.

Asiatic acid prevents glucocorticoid-induced femoral head osteonecrosis via PI3K/AKT pathway

Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) represents a predominant etiology of non-traumatic osteonecrosis, imposing substantial pain, restricting hip mobility, and diminishing overall quality of life for affected individuals. Centella asiatica (L.) Urb. (CA), an herbal remedy deeply rooted in traditional oriental medicine, has exhibited noteworthy therapeutic efficacy in addressing inflammation and facilitating wound healing. Drawing from CA's historical applications, its anti-inflammatory, anti-apoptotic, and antioxidant attributes may hold promise for managing GIONFH. Asiatic acid (AA), a primary constituent of CA, has been substantiated as a key contributor to its anti-apoptotic, antioxidant, and anti-inflammatory capabilities, showcasing a close association with orthopedic conditions. For the investigation of whether AA could alleviate GIONFH through suppressing oxidative stress, apoptosis, and to delve into its potential cellular and molecular mechanisms, the connection between AA and disease was analyzed through network pharmacology. DEX-induced apoptosis in rat osteoblasts and GIONFH in rat models, got utilized for the verification in vitro/vivo, on underlying mechanism of AA in GIONFH. Network pharmacology analysis reveals a robust correlation between AA and GIONFH in multiple target genes. AA has demonstrated the inhibition of DEX-induced osteoblast apoptosis by modulating apoptotic factors like BAX, BCL-2, Cleaved-caspase3, and cleaved-caspase9. Furthermore, it effectively diminishes the ROS overexpression and regulates oxidative stress through mitochondrial pathway. Mechanistic insights suggest that AA's therapeutic effects involve phosphatidylinositol 3-kinase/Protein kinase B (PI3K/AKT) pathway activation. Additionally, AA has exhibited its potential to ameliorate GIONFH progression in rat models. Our findings revealed that AA mitigated DEX-induced osteoblast apoptosis and oxidative stress through triggering PI3K/AKT pathway. Also, AA can effectively thwart GIONFH occurrence and development in rats.