Suppression of apoptosis in osteocytes, the potential way of natural medicine in the treatment of osteonecrosis of the femoral head

Fibroblast IRF7-mediated chondrocyte apoptosis affects the progression of collapse in steroid-induced osteonecrosis of the femoral head

PURPOSE

The objective of this study was to identify potential genes implicated in the "peri-collapse" synovium of osteonecrosis of the femoral head through coding gene sequencing and to further clarify their specific mechanisms via in vitro experiments.

METHODS

Steroid-induced osteonecrosis of the femoral head (SIONFH) (n = 3), femoral neck fracture (FNF) (n = 3), and hip osteoarthritis (HOA) (n = 3) Synovial tissue of the hip joint was collected in total hip arthroplasty. A cellular model of SIONFH constructed from rat synovial fibroblasts by lipopolysaccharide intervention. Lentiviral technology was used to construct a model for fibroblast knockout of the Irf7 gene. HE was used to compare the characteristics of synovial tissue damage, and immunofluorescence and immunohistochemistry were used to compare the expression levels of VIM, IRF7, and IFNα. PCR, WB, and IF were used to examine Irf7 knockdown efficiency, chondrocyte proliferation (Col2a1, Aggrecan, Sox9), cartilage matrix degradation (Mmp13), and apoptosis (Bcl2, Bax, and Caspase3) expression under co-culture conditions. Crystalline violet staining was used to observe the migration rate of fibroblasts, and flow cytometry was used to detect the apoptosis level of chondrocytes under co-culture conditions.

RESULTS

Transcriptome sequencing of synovial tissue and fibroblasts ultimately screened for six differential genes, HOOK1, RNPC3, KCNA3, CD48, IRF7, SAMD9. Compared to FNF and HOA, synovial inflammatory cell recruitment and synovial hyperplasia were more pronounced in SIONFH. IF and IHC confirmed high expression of IRF7 and IFNα in the synovium of SIONFH. PCR and WB results suggested that fibroblasts highly expressed Irf7, Hook1, Rnpc3, Kcna3, Cd48, Samd9, Il-6, and Tnfα after lipopolysaccharide intervention, and the expression levels of Il-6 and Tnfα were significantly reduced after knockdown of Irf7 (P < 0.001). In the co-culture system, fibroblasts intervened with lipopolysaccharide significantly promoted chondrocyte apoptosis, the rate of cartilage matrix degradation, while inhibiting the level of chondrocyte proliferation, and this result was significantly reversed in Irf7 knockout fibroblasts. This was supported by flow cytometry results.

CONCLUSIONS

IRF7, HOOK1, RNPC3, KCNA3, CD48, and SAMD9 as potential genes affecting the progression of SIONFH collapse. Irf7 mediates the fibroblast inflammatory response and affects the collapse process of SIONFH by influencing chondrocyte apoptosis. Thus, intervention in IRF7 holds promise as one of the key targets for reversing the collapse process of SIONFH.

Activation of PI3K-AKT pathway prevents steroid-induced osteonecrosis of the femoral head via inhibiting Cuproptosis

This study delved into the role of the PI3K/AKT signaling pathway and cuproptosis in steroid-induced osteonecrosis of the femoral head (SIONFH), assessing the therapeutic potential of the PI3K agonist 740Y-P. We analyzed femoral head specimens from SIONFH patients using DIA proteomics, identifying differentially expressed proteins linked to cuproptosis. In vitro, MC3T3-E1 cells treated with dexamethasone (DEX) exhibited hallmarks of cuproptosis, including downregulation of DLAT, PDHB, SLC25A3, and FDX1, increased copper ions, and reduced osteogenic potential, as shown by decreased ALP activity and RUNX2/BMP2 expression. The PI3K/AKT pathway's modulation of FDX1 was key to cuproptosis regulation; activating it with 740Y-P restored FDX1 levels and partially recovered osteogenic capacity. An in vivo rat model of SIONFH treated with 740Y-P demonstrated improved bone parameters, reversed osteogenic suppression, and upregulated PI3K/AKT/FDX1 expression, validating the pathway's role in cuproptosis and the agonist's therapeutic potential for treating SIONFH and glucocorticoid-associated bone disorders.

The role of the PKCζ/JNK signaling pathway in regulating the development of femoral head necrosis

Osteonecrosis of the femoral head (ONFH) is a debilitating condition characterized by the death of bone cells in the hip joint, resulting in profound disability. This condition has a significant global prevalence. Glucocorticoid (GC)-induced apoptosis of bone cells serves as a crucial cellular mechanism underlying ONFH. The protein kinase C zeta (PKCζ) and c-Jun N-terminal kinase (JNK)/c-Jun cascades have been implicated in the progression of ONFH, yet their interrelationship and contributions to disease development remain unclear. The objective of this study was to investigate the combined impact of PKCζ and JNK/c-Jun signaling on dexamethasone (Dex)-induced apoptosis in osteoblasts in vitro and in GC-induced ONFH rat models in vivo. In vitro experiments were conducted using hFOB1.19 osteoblastic cells to scrutinize the effects of Dex-induced apoptosis. The role of the PKCζ/JNK/c-Jun signaling pathway in this process was examined using naringenin-7-O-β-D-Glucuronide (N7G), a PKC inhibitor, and anisomycin, a JNK activator. The findings were further validated using a rat model of ONFH in vivo. Our results revealed that PKCζ activation augmented JNK/c-Jun signaling and facilitated Dex-induced osteoblast apoptosis. Inhibition of PKCζ with N7G mitigated these effects, while JNK activation with anisomycin intensified them. Similar regulatory effects on osteoblast apoptosis and ONFH progression were observed in the in vivo rat models. Glucocorticoids can induce osteoblast apoptosis and contribute to the development of ONFH by activating the PKCζ/JNK/c-Jun signaling pathway. This study provides compelling evidence supporting the potential therapeutic value of comprehending the pathogenesis of ONFH and developing targeted treatments for this debilitating condition.

Mechanism of IRF8 on osteocyte apoptosis in steroid-induced osteonecrosis of the femoral head

BACKGROUND

Steroid-induced osteonecrosis of the femoral head (SONFH) is a metabolic disorder that leads to structural changes, collapse of the femoral head, and joint dysfunction. This study investigates the role of interferon regulatory factor 8 (IRF8) in osteocyte apoptosis in SONFH, so as to find new targets for the treatment of SONFH.

METHODS

Murine long bone osteocyte-Y4 cells were cultured and treated with dexamethasone to establish SONFH cell models. si-IRF8 was transfected into the cells. The expression levels of IRF8, B cell leukemia/lymphoma 2 (Bcl-2), BCL2 associated X (Bax), zinc finger protein 667 (ZNF667), and miR-181a-5p were detected. Cell apoptosis and viability were detected. The enrichment of IRF8 on the miR-181a-5p promoter was assayed. The binding relationship between IRF8 and miR-181a-5p promoter, and between miR-181a-5p and ZNF667 3'UTR sequence was verified. Combined experiments with miR-181a-5p knockdown or ZNF667 overexpression were performed to observe the changes in cell apoptosis.

RESULTS

IRF8 and ZNF667 were increased in SONFH cells and miR-181a-5p was decreased. Inhibition of IRF8 increased SONFH cell viability and reduced apoptosis. Mechanistically, IRF8 was enriched in the miR-181a-5p promoter to inhibit miR-181a-5p and miR-181a-5p targeted and inhibited ZNF667. miR-181a-5p knockdown or ZNF667 overexpression could alleviate the inhibitory effect of IRF8 down-regulation on osteocyte apoptosis in SONFH.

CONCLUSION

IRF8 was enriched in the miR-181a-5p promoter to inhibit miR-181a-5p, thus promoting ZNF667 levels and increasing osteocyte apoptosis in SONFH, which may be a new theoretical basis for the treatment of SONFH.

AEBP1 restores osteoblastic differentiation under dexamethasone treatment by activating PI3K/AKT signalling

Adipocyte enhancer-binding protein 1 (AEBP1) is closely implicated in osteoblastic differentiation and bone fracture; this research aimed to investigate the effect of AEBP1 on restoring osteoblastic differentiation under dexamethasone (Dex) treatment, and its interaction with the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway. Pre-osteoblastic MC3T3-E1 cells were cultured in osteogenic medium and treated by Dex to mimic steroid-induced osteonecrosis cellular model. They were then further transfected with control or AEBP1-overexpressed lentiviral vectors. Finally, cells were treated with the PI3K inhibitor LY294002, with or without AEBP1-overexpressed lentiviral vectors. AEBP1 expression showed a downward trend in MC3T3-E1 cells under Dex treatment in a dose-dependent manner. AEBP1-overexpressed lentiviral vectors increased relative cell viability, alkaline phosphatase (ALP) staining, Alizarin red staining and osteoblastic differentiation markers including osteocalcin (OCN), osteopontin (OPN), collagen type I alpha 1 (COL1A1), runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP2), but decreased cell apoptosis rate in MC3T3-E1 cells under Dex treatment; besides, AEBP1-overexpressed lentiviral vectors positively regulated p-PI3K and p-AKT expressions. Furthermore, LY294002 treatment decreased relative cell viability, Alizarin red staining, osteoblastic differentiation markers including OCN, OPN, RUNX2 and BMP, increased cell apoptosis rate and did not affect ALP staining in MC3T3-E1 cells under Dex treatment; meanwhile, LY294002 treatment weakened the effect of AEBP1 overexpression vectors on the above cell functions. AEBP1 restores osteoblastic differentiation under Dex treatment by activating the PI3K/AKT pathway.

Translational horizons in stem cell therapy for osteonecrosis of the femoral head: a journey from basic research to clinical practice through bibliometric insights

BACKGROUND

Osteonecrosis of the femoral head (ONFH) significantly impacts young and middle-aged adults, with steroid use implicated in many cases. Traditional treatments have limited efficacy, prompting a shift towards innovative approaches, such as stem cell therapy, offering less invasive regenerative solutions.

METHODS

Using bibliometric analysis from 1997 to 2023, we identified 392 articles on stem cell therapy for ONFH from the Web of Science Core Collection and analysed them using VOSviewer and CiteSpace to identify key trends and research directions.

RESULTS

From 1997 to 2023, stem cell therapy for ONFH research expanded significantly, with 392 articles evidencing global collaboration, particularly from China, the United States and South Korea. The field is characterised by 158 core authors across 26 clusters and contributions from 417 institutions in 104 research clusters, with Shanghai Jiao Tong University as a notable leader. This research is disseminated through 23 journal clusters, emphasising interdisciplinary work, with Clinical Orthopaedics and Related Research among the most influential journals. Key findings include the identification of the most influential papers, highlighting advances, such as use of autologous mesenchymal stem cells (MSCs) and innovative delivery mechanisms. High-frequency keyword analysis further mapped the evolution of the field, from basic mechanisms to advanced therapies, underscoring a trend towards more targeted stem cell treatments for ONFH.

CONCLUSION

Stem cell therapy for ONFH has advanced significantly, showcasing a successful transition from basic research to clinical practice, particularly highlighted by developments in use of autologous MSCs and delivery methods. Future research will focus on refining therapies through exosome technology, targeted modulation of stress and inflammation and integration with surgical techniques, with the aim of tailored patient care and improved ONFH outcomes.

Exploring the genetic association between immune cells and susceptibility to osteonecrosis using large-scale population data

Objectives

Research shows a close association between aberrant immune reactions in osteonecrotic tissues and immune cell infiltration. However, due to limitations in sample size and dataset comprehensiveness, the causal relationship between them is not fully established. This study aims to determine whether there is a causal relationship using a larger and more diverse dataset.

Methods

We conducted a comprehensive Mendelian Randomization (MR) analysis to investigate the causal relationship between immune cell characteristics and osteonecrosis. Utilizing publicly available genetic data, we explored the causal relationships between 731 immune cell features and 604 cases from the FinnGen Finnish database, as well as 257 cases from the UK Biobank database with osteonecrosis data. The inverse-variance weighted (IVW) method was used for the primary analysis, and we employed sensitivity analyses to assess the robustness of the main results. In addition, considering data from the two databases used in this study, a meta-analysis was conducted on the significant immune cells associated with osteonecrosis (FDR <0.05).

Results

our findings suggested that specific immune cell signatures, such as CD20- % lymphocytes, CD62L-monocytes, and CD33br HLA DR+ CD14-cells were associated with increased odds of osteonecrosis. In contrast, EM CD4+ activated cells and DP (CD4+ CD8+) T cells were associated with decreased odds. Notably, osteonecrosis was associated with a potential decrease in CD45 on immature MDSC cell content.

Conclusion

From a genetic perspective, we demonstrated a close association between immune cells and osteonecrosis. These findings significantly enhance our understanding of the interplay between immune cell infiltration and the risk of osteonecrosis, contributing to the potential design of therapeutic strategies from an immunological standpoint.

Identification and experimental validation of programmed cell death- and mitochondria-associated biomarkers in osteoporosis and immune microenvironment

Background: Prior research has demonstrated that programmed cell death (PCD) and mitochondria assume pivotal roles in controlling cellular metabolism and maintaining bone cell equilibrium. Nonetheless, the comprehensive elucidation of their mode of operation in osteoporosis (OP) warrants further investigation. Therefore, this study aimed at analyzing the role of genes associated with PCD (PCD-RGs) and mitochondria (mortality factor-related genes; MRGs) in OP. Methods: Differentially expressed genes (DEGs) were identified by subjecting the GSE56815 dataset obtained from the Gene Expression Omnibus database to differential expression analysis and comparing OP patients with healthy individuals. The genes of interest were ascertained through the intersection of DEGs, MRGs, and PCD-RGs; these genes were filtered using machine learning methodologies to discover potential biomarkers. The prospective biomarkers displaying uniform patterns and statistically meaningful variances were identified by evaluating their levels in the GSE56815 dataset and conducting quantitative real-time polymerase chain reaction-based assessments. Moreover, the functional mechanisms of these biomarkers were further delineated by constructing a nomogram, which conducted gene set enrichment analysis, explored immune infiltration, generated regulatory networks, predicted drug responses, and performed molecular docking analyses. Results: Eighteen candidate genes were documented contingent upon the intersection between 2,354 DEGs, 1,136 MRGs, and 1,548 PCD-RGs. The biomarkers DAP3, BIK, and ACAA2 were upregulated in OP and were linked to oxidative phosphorylation. Furthermore, the predictive ability of the nomogram designed based on the OP biomarkers exhibited a certain degree of accuracy. Correlation analysis revealed a strong positive correlation between CD56dim natural killer cells and ACAA2 and a significant negative correlation between central memory CD4+ T cells and DAP3. DAP3, BIK, and ACAA2 were regulated by multiple factors; specifically, SETDB1 and ZNF281 modulated ACAA2 and DAP3, whereas TP63 and TFAP2C governed DAP3 and BIK. Additionally, a stable binding force was observed between the drugs (estradiol, valproic acid, and CGP52608) and the biomarkers. Conclusion: This investigation evidenced that the biomarkers DAP3, BIK, and ACAA2 are associated with PCD and mitochondria in OP, potentially facilitate the diagnosis of OP in clinical settings.

Association between genetically plasma proteins and osteonecrosis: a proteome-wide Mendelian randomization analysis

Background

Previous studies have explored the role of plasma proteins on osteonecrosis. This Mendelian randomization (MR) study further assessed plasma proteins on osteonecrosis whether a causal relationship exists and provides some evidence of causality.

Methods

Summary-level data of 4,907 circulating protein levels were extracted from a large-scale protein quantitative trait loci study including 35,559 individuals by the deCODE Genetics Consortium. The outcome data for osteonecrosis were sourced from the FinnGen study, comprising 1,543 cases and 391,037 controls. MR analysis was conducted to estimate the associations between protein and osteonecrosis risk. Additionally, Phenome-wide MR analysis, and candidate drug prediction were employed to identify potential causal circulating proteins and novel drug targets.

Results

We totally assessed the effect of 1,676 plasma proteins on osteonecrosis risk, of which 71 plasma proteins had a suggestive association with outcome risk (P < 0.05). Notably, Heme-binding protein 1 (HEBP1) was significant positively associated with osteonecrosis risk with convening evidence (OR, 1.40, 95% CI, 1.19 to 1.65, P = 3.96 × 10-5, P FDR = 0.044). This association was further confirmed in other MR analysis methods and did not detect heterogeneity and pleiotropy (all P > 0.05). To comprehensively explore the health effect of HEBP1, the phenome-wide MR analysis found it was associated with 136 phenotypes excluding osteonecrosis (P < 0.05). However, no significant association was observed after the false discovery rate adjustment.

Conclusion

This comprehensive MR study identifies 71 plasma proteins associated with osteonecrosis, with HEBP1, ITIH1, SMOC1, and CREG1 showing potential as biomarkers of osteonecrosis. Nonetheless, further studies are needed to validate this candidate plasma protein.

Identification and analysis of mitochondria-related central genes in steroid-induced osteonecrosis of the femoral head, along with drug prediction

Purpose

Steroid-induced osteonecrosis of the femoral head (SONFH) is a refractory orthopedic hip joint disease that primarily affects middle-aged and young individuals. SONFH may be caused by ischemia and hypoxia of the femoral head, where mitochondria play a crucial role in oxidative reactions. Currently, there is limited literature on whether mitochondria are involved in the progression of SONFH. Here, we aim to identify and validate key potential mitochondrial-related genes in SONFH through bioinformatics analysis. This study aims to provide initial evidence that mitochondria play a role in the progression of SONFH and further elucidate the mechanisms of mitochondria in SONFH.

Methods

The GSE123568 mRNA expression profile dataset includes 10 non-SONFH (non-steroid-induced osteonecrosis of the femoral head) samples and 30 SONFH samples. The GSE74089 mRNA expression profile dataset includes 4 healthy samples and 4 samples with ischemic necrosis of the femoral head. Both datasets were downloaded from the Gene Expression Omnibus (GEO) database. The mitochondrial-related genes are derived from MitoCarta3.0, which includes data for all 1136 human genes with high confidence in mitochondrial localization based on integrated proteomics, computational, and microscopy approaches. By intersecting the GSE123568 and GSE74089 datasets with a set of mitochondrial-related genes, we screened for mitochondrial-related genes involved in SONFH. Subsequently, we used the good Samples Genes method in R language to remove outlier genes and samples in the GSE123568 dataset. We further used WGCNA to construct a scale-free co-expression network and selected the hub gene set with the highest connectivity. We then intersected this gene set with the previously identified mitochondrial-related genes to select the genes with the highest correlation. A total of 7 mitochondrial-related genes were selected. Next, we performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis on the selected mitochondrial-related genes using R software. Furthermore, we performed protein network analysis on the differentially expressed proteins encoded by the mitochondrial genes using STRING. We used the GSEA software to group the genes within the gene set in the GSE123568 dataset based on their coordinated changes and evaluate their impact on phenotype changes. Subsequently, we grouped the samples based on the 7 selected mitochondrial-related genes using R software and observed the differences in immune cell infiltration between the groups. Finally, we evaluated the prognostic significance of these features in the two datasets, consisting of a total of 48 samples, by integrating disease status and the 7 gene features using the cox method in the survival R package. We performed ROC analysis using the roc function in the pROC package and evaluated the AUC and confidence intervals using the ci function to obtain the final AUC results.

Results

Identification and analysis of 7 intersecting DEGs (differentially expressed genes) were obtained among peripheral blood, cartilage samples, hub genes, and mitochondrial-related genes. These 7 DEGs include FTH1, LACTB, PDK3, RAB5IF, SOD2, and SQOR, all of which are upregulated genes with no intersection in the downregulated gene set. Subsequently, GO and KEGG pathway enrichment analysis revealed that the upregulated DEGs are primarily involved in processes such as oxidative stress, release of cytochrome C from mitochondria, negative regulation of intrinsic apoptotic signaling pathway, cell apoptosis, mitochondrial metabolism, p53 signaling pathway, and NK cell-mediated cytotoxicity. GSEA also revealed enriched pathways associated with hub genes. Finally, the diagnostic value of these key genes for hormone-related ischemic necrosis of the femoral head (SONFH) was confirmed using ROC curves.

Conclusion

BID, FTH1, LACTB, PDK3, RAB5IF, SOD2, and SQOR may serve as potential diagnostic mitochondrial-related biomarkers for SONFH. Additionally, they hold research value in investigating the involvement of mitochondria in the pathogenesis of ischemic necrosis of the femoral head.

Exploring the potential mechanism of Taohong Siwu decoction in the treatment of avascular necrosis of the femoral head based on network pharmacology and molecular docking

Based on network pharmacology and molecular docking, this study seeks to investigate the mechanism of Taohong Siwu decoction (THSWD) in the treatment of avascular necrosis of the femoral head (AVNFH). The Traditional Chinese Medicine Systems Pharmacology database was used in this investigation to obtain the active ingredients and related targets for each pharmaceutical constituent in THSWD. To find disease-related targets, the terms "avascular necrosis of the femoral head," "necrosis of the femoral head," "steroid-induced necrosis of the femoral head," "osteonecrosis," and "avascular necrosis of the bone" were searched in the databases DisGeNET, GeneCards, Comparative Toxicogenomics Database, and MalaCards. Following the identification of the overlap targets of THSWD and AVNFH, enrichment analysis using gene ontology, Kyoto Encyclopedia of Genes and Genomes, Reactome, and WikiPathways was conducted. The "THSWD-drug-active compound-intersection gene-hub gene-AVNFH" network and protein-protein interaction network were built using Cytoscape 3.9.1 and string, and CytoHubba was used to screen hub genes. The binding activities of hub gene targets and key components were confirmed by molecular docking. 152 prospective therapeutic gene targets were found in the bioinformatics study of ONFH treated with THSWD, including 38 major gene targets and 10 hub gene targets. The enrichment analysis of 38 key therapeutic targets showed that the biological process of gene ontology analysis mainly involved cytokine-mediated signaling pathway, angiogenesis, cellular response to reactive oxygen species, death-inducing signaling complex. The Kyoto Encyclopedia of Genes and Genomes signaling pathway mainly involves TNF signaling pathway, IL-17 signaling pathway, and the Recactome pathway mainly involves Signaling by Interleukins, Apoptosis, and Intrinsic Pathway for Apoptosis. WikiPathways signaling pathway mainly involves TNF-related weak inducer of apoptosis signaling pathway, IL-18 signaling pathway. According to the findings of enrichment analysis, THSWD cured AVNFH by regulating angiogenesis, cellular hypoxia, inflammation, senescence, apoptosis, cytokines, and cellular proliferation through the aforementioned targets and signaling pathways. The primary component of THSWD exhibits a strong binding force with the key protein of AVNFH. This study sheds new light on the biological mechanism of THSWD in treating AVNFH by revealing the multi-component, multi-target, and multi-pathway features and molecular docking mechanism of THSWD.