Proper mechanical stress promotes femoral head recovery from steroid-induced osteonecrosis in rats through the OPG/RANK/RANKL system

Effects of external environment on promoter methylation of PIK3R5 and related pathway regulation in steroid-induced femoral head necrosis

BACKGROUND

Steroid-induced Avascular Necrosis of the Femoral Head (SANFH) is a condition characterized by the necrosis of the femoral head caused by long-term or high-dose hormone usage. Studies have shown that the PI3K/AKT pathway plays a crucial regulatory role in the development of SANFH. The aim of this study is to determine how external environmental factors induce changes in endogenous hormone levels, how these changes lead to steroid-induced femoral head necrosis, and the interrelationship between the changes in PIK3R5 promoter methylation levels and the regulation of the associated signaling pathways.

METHODS

Femoral head samples underwent molecular sequencing analysis. Candidate genes were screened by differential gene analysis and functional enrichment analysis.Methylation level of candidate gene PIK3R5 was verified by methylation-specific PCR(MS-PCR). SANFH model was constructed in New Zealand white rabbits, and the model results were verified by magnetic resonance imaging (MRI) and haematoxylin-eosin (HE) staining.The expression of PIK3R5, PI3K and AKT in rabbit models and human specimens was verified by real-time fluorescence quantitative PCR(RT-qPCR) and Western Blot(WB), respectively.

RESULTS

Human femoral head sequencing results indicate distinct differences in the methylation level and mRNA expression of PIK3R5 in SANFH. MS-PCR results showed the methylation level of SANFH patients was significantly higher than that of the control group (P < 0.01). The RT-qPCR results showed that PIK3R5 and PI3K expression levels in the SANFH group were lower than those in the control group (P < 0.05), and the WB experiment results were consistent with the RT-qPCR results. The MRI and HE staining results showed that the rabbit model of SANFH was successfully constructed, and the results of RT-qPCR and WB were consistent with the results of human tissues.

CONCLUSION

During the occurrence and development of SANFH, PIK3R5 gene regulates the PI3K/AKT pathway through methylation modification, promotes the oxidative stress response of cells, and accelerates the disease process.

The Role of Oxidative Stress in Multiple Exercise-Regulated Bone Homeostasis

Bone is a tissue that is active throughout the lifespan, and its physiological activities, such as growth, development, absorption, and formation, are always ongoing. All types of stimulation that occur in sports play an important role in regulating the physiological activities of bone. Here, we track the latest research progress locally and abroad, summarize the recent, relevant research results, and systematically summarize the effects of different types of exercise on bone mass, bone strength and bone metabolism. We found that different types of exercise have different effects on bone health due to their unique technical characteristics. Oxidative stress is an important mechanism mediating the exercise regulation of bone homeostasis. Excessive high-intensity exercise does not benefit bone health but induces a high level of oxidative stress in the body, which has a negative impact on bone tissue. Regular moderate exercise can improve the body's antioxidant defense ability, inhibit an excessive oxidative stress response, promote the positive balance of bone metabolism, delay age-related bone loss and deterioration of bone microstructures and have a prevention and treatment effect on osteoporosis caused by many factors. Based on the above findings, we provide evidence for the role of exercise in the prevention and treatment of bone diseases. This study provides a systematic basis for clinicians and professionals to reasonably formulate exercise prescriptions and provides exercise guidance for patients and the general public. This study also provides a reference for follow-up research.

The Effect of the Hip Flexion Angle in Osteonecrosis of the Femoral Head Based on China-Japan Friendship Hospital Classification - A Finite Element Study

OBJECTIVE

The alteration in the mechanical environment of the necrotic area is the primary cause of the collapse observed in osteonecrosis of the femoral head (ONFH). This study aims to evaluate the biomechanical implications of the China-Japan Friendship Hospital (CJFH) classification system and hip flexion angles on the necrotic area in ONFH using finite element analysis (FEA). The goal is to provide valuable guidance for hip preservation treatments and serve as a reference for clinical diagnosis and therapeutic interventions.

METHODS

Hip tomography CT scan data from a healthy volunteer was used to create a 3D model of the left hip. The model was preprocessed and imported into Solidworks 2018, based on the CJFH classification. Material parameters and boundary conditions were applied to each fractal model in ANSYS 21.0. Von Mises stresses were calculated, and maximum deformation values were obtained to evaluate the biomechanical effects of the load on the necrotic area and post-necrotic femur, as well as assess each fractal model's collapse risk.

RESULTS

(1) At the same hip flexion angle, maximum deformation followed this order: M Type < C Type < L Type. The L3 type necrotic area experienced the most significant deformation at 0, 60, and 110° angles (1.121, 1.7913, and 1.8239 mm respectively). (2) Under the same CJFH classification, maximum deformation values increased with hip flexion angle (0 < 60 < 110°), suggesting a higher risk of collapse at larger angles. (3) Von Mises stress results showed that the maximum stress was not located in the necrotic area but near the inner and outer edge of the femoral neck, indicating decreased stiffness and strength of the subchondral bone after osteonecrosis.

CONCLUSION

The study found that femoral head collapse risk was higher when the necrotic area was located in the lateral column under the same stress load and flexion angle. Mechanical properties of the necrotic area changed, resulting in decreased bone strength and stiffness. Large-angle hip flexion is more likely to cause excessive deformation of the necrotic area; thus, ONFH patients should reduce or avoid large-angle hip flexion during weight-bearing training in rehabilitation activities.

A Pilot Experiment to Measure the Initial Mechanical Stability of the Femoral Head Implant in a Cadaveric Model of Osteonecrosis of Femoral Head Involving up to 50% of the Remaining Femoral Head

Background and Objectives: Currently, only patients with osteonecrosis of the femoral head (ONFH), who had bone defects involving 30–33.3% of the remaining femoral head, are indicated in hip resurfacing arthroplasty (HRA). In an experimental cadaver model of ONFH involving up to 50% of the remaining femoral head, the initial stability of the femoral head implant (FHI) at the interface between the implant and the remaining femoral head was measured. Materials and Methods: The ten specimens and the remaining ten served as the experimental group and the control group, respectively. We examined the degree of the displacement of the FHI, the bonding strength between the FHI and the retained bone and that at the interface between the FHI and bone cement. Results: Changes in the degree of displacement at the final phase from the initial phase were calculated as 0.089 ± 0.036 mm in the experimental group and 0.083 ± 0.056 mm in the control group. However, this difference reached no statistical significance (p = 0.7789). Overall, there was an increase in the degree of displacement due to the loading stress, with increased loading cycles in both groups. In cycles of up to 6000 times, there was a steep increase. After cycles of 8000 times, however, there was a gradual increase. Moreover, in cycles of up to 8000 times, there was an increase in the difference in the degree of displacement due to the loading stress between the two groups. After cycles of 8000 times, however, such difference remained almost unchanged. Conclusions: In conclusion, orthopedic surgeons could consider performing the HRA in patients with ONFH where the bone defects involved up to 50% of the remaining femoral head, without involving the femoral head–neck junction in the anterior and superior area of the femoral head. However, more evidence-based studies are warranted to justify our results.

Bioinformatics Analysis of the Key Genes and Pathways in Multiple Myeloma

Objective

To study the differentially expressed genes between multiple myeloma and healthy whole blood samples by bioinformatics analysis, find out the key genes involved in the occurrence, development and prognosis of multiple myeloma, and analyze and predict their functions.

Methods

The gene chip data GSE146649 was downloaded from the GEO expression database. The gene chip data GSE146649 was analyzed by R language to obtain the genes with different expression in multiple myeloma and healthy samples, and the cluster analysis heat map was constructed. At the same time, the protein-protein interaction (PPI) networks of these DEGs were established by STRING and Cytoscape software. The gene co-expression module was constructed by weighted correlation network analysis (WGCNA). The hub genes were identified from key gene and central gene. TCGA database was used to analyze the expression of differentially expressed genes in patients with multiple myeloma. Finally, the expression level of TNFSF11 in whole blood samples from patients with multiple myeloma was analyzed by RT qPCR.

Results

We identified four genes (TNFSF11, FGF2, SGMS2, IGFBP7) as hub genes of multiple myeloma. Then, TCGA database was used to analyze the survival of TNFSF11, FGF2, SGMS2 and IGFBP7 in patients with multiple myeloma. Finally, the expression level of TNFSF11 in whole blood samples from patients with multiple myeloma was analyzed by RT qPCR.

Conclusion

The study suggests that TNFSF11, FGF2, SGMS2 and IGFBP7 are important research targets to explore the pathogenesis, diagnosis and treatment of multiple myeloma.

IL-34 Aggravates Steroid-Induced Osteonecrosis of the Femoral Head via Promoting Osteoclast Differentiation

IL-34 can promote osteoclast differentiation and activation, which may contribute to steroid-induced osteonecrosis of the femoral head (ONFH). Animal model was constructed in both BALB/c and IL-34 deficient mice to detect the relative expression of inflammation cytokines. Micro-CT was utilized to reveal the internal structure. In vitro differentiated osteoclast was induced by culturing bone marrow-derived macrophages with IL-34 conditioned medium or M-CSF. The relative expression of pro-inflammation cytokines, osteoclast marker genes, and relevant pathways molecules was detected with quantitative real-time RT-PCR, ELISA, and Western blot. Up-regulated IL-34 expression could be detected in the serum of ONFH patients and femoral heads of ONFH mice. IL-34 deficient mice showed the resistance to ONFH induction with the up-regulated trabecular number, trabecular thickness, bone value fraction, and down-regulated trabecular separation. On the other hand, inflammatory cytokines, such as TNF-α, IFN-γ, IL-6, IL-12, IL-2, and IL-17A, showed diminished expression in IL-34 deficient ONFH induced mice. IL-34 alone or works in coordination with M-CSF to promote osteoclastogenesis and activate ERK, STAT3, and non-canonical NF-κB pathways. These data demonstrate that IL-34 can promote the differentiation of osteoclast through ERK, STAT3, and non-canonical NF-κB pathways to aggravate steroid-induced ONFH, and IL-34 can be considered as a treatment target.

Inhibition of miR-93-5p promotes osteogenic differentiation in a rabbit model of trauma-induced osteonecrosis of the femoral head

Trauma‐induced osteonecrosis of the femoral head (TIONFH) is characterized by femoral head collapse accompanied by degenerative changes of the hip. We previously reported that miR‐93‐5p expression is abnormally high in patients with TIONFH, but the role of miR‐93‐5p in the TIONFH process remains unclear. Herein, we investigated the role of miR‐93‐5p in TIONFH in a rabbit model. Bone marrow mesenchymal stem cells (BMSCs) were used for both in vivo and in vitro experiments. A rabbit model of TIONFH was injected with BMSCs transfected with miR‐93‐5p inhibitor. In addition, both an miR‐93‐5p mimic and negative control were transfected into BMSCs. Expression of miR‐93‐5p was significantly increased in the model group compared with control samples. An miR‐93‐5p inhibitor induced the expression of bone morphogenetic protein 2 (BMP‐2) and alkaline phosphatase. Furthermore, expression of osteogenesis‐related markers (BMP‐2, secreted phosphoprotein 1, RUNX family transcription factor 2 and Osterix) was higher in the miR‐93‐5p inhibitor group, as revealed by quantitative PCR and western blotting. In addition, in vitro experimentation revealed that an miR‐93‐5p mimic decreased BMP‐2 and TNF receptor superfamily member 11b expression, but increased receptor activator of nuclear factor‐kappaB ligand expression. In summary, the miR‐93‐5p inhibitor could promote osteogenic differentiation by increasing BMP‐2 expression during the development of TIONFH. Thus, miR‐93‐5p may have potential as a therapeutic target for TIONF treatment.

Acupotomy Contributes to Suppressing Subchondral Bone Resorption in KOA Rabbits by Regulating the OPG/RANKL Signaling Pathway

Subchondral bone lesions, as the crucial inducement for accelerating cartilage degeneration, have been considered as the initiating factor and the potential therapeutic target of knee osteoarthritis (KOA). Acupotomy, the biomechanical therapy guided by traditional Chinese meridians theory, alleviates cartilage deterioration by correcting abnormal mechanics. Whether this mechanical effect of acupotomy inhibits KOA subchondral bone lesions is indistinct. This study aimed to investigate the effects of acupotomy on inhibiting subchondral bone resorption and to define the possible mechanism in immobilization-induced KOA rabbits. After KOA modeling, 8 groups of rabbits (4w/6w acupotomy, 4w/6w electroacupuncture, 4w/6w model, and 4w/6w control groups) received the indicated intervention for 3 weeks. Histological and bone histomorphometry analyses revealed that acupotomy prevented both cartilage surface erosion and subchondral bone loss. Further, acupotomy suppressed osteoclast activity and enhanced osteoblast activity in KOA subchondral bone, showing a significantly decreased expression of tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinases-9 (MMP-9), and cathepsin K (Ctsk) and a significantly increased expression of osteocalcin (OCN); this regulation may be mediated by blocking the decrease in osteoprotegerin (OPG) and the increase in NF-κB receptor activated protein ligand (RANKL). These findings indicated that acupotomy inhibited osteoclast activity and promoted osteoblast activity to ameliorate hyperactive subchondral bone resorption and cartilage degeneration in immobilization-induced KOA rabbits, which may be mediated by the OPG/RANKL signaling pathway. Taken together, our results indicate that acupotomy may have therapeutic potential in KOA by restoring the balance between bone formation and bone resorption to attenuate subchondral bone lesions.

Astragaloside IV ameliorates steroid-induced osteonecrosis of the femoral head by repolarizing the phenotype of pro-inflammatory macrophages

Osteonecrosis of the femoral head (ON-FH) is a common complication of steroid use. Pro-inflammatory macrophages play a crucial role in the apoptosis of osteocytes. The objective of the study was to evaluate a plant extract astragaloside IV (AS-IV) in treating ON-FN. Bone-marrow-derived macrophages (BMDMs) were treated with lipopolysaccharides (LPS), IFN-γ or IL-4 to induce M1 and M2-like phenotypes. Quantitative real-time PCR and Western blot were used to examine M1 and M2 phenotypic markers. Flow cytometry was used to analyze MHC II, CD206, F4/80, and CD11b levels and cell apoptosis. Glucocorticoid was used to induce ON-FN in mice. TNF-α and IL-1β levels in femoral head were determined using enzyme-linked immunosorbent assay. AS-IV repolarized macrophages from M1 to M2 phenotypes. Culture medium from AS-IV treated M1 macrophages induced less cell apoptosis osteocytes compared to that from untreated M1 macrophages. In ON-FH mice, the ratio of M1 macrophages was decreased in the femoral head by AS-IV, concomitant with a decrease in TNF-α and IL-1β levels. AS-IV is effective in alleviating ON-FH through its effects in repolarizing macrophages from M1-like phenotype to M2-like phenotype, promoting survival of osteocytes, reducing arthritic symptoms, and decreasing inflammatory cytokines.