TNF-α regulates the early development of avascular necrosis of the femoral head by mediating osteoblast autophagy and apoptosis via the p38 MAPK/NF-κB signaling pathway

Identification of steroid-induced osteonecrosis of the femoral head biomarkers based on immunization and animal experiments

BACKGROUND

Steroid-induced osteonecrosis of femoral head (SONFH) is a severe health risk, and this study aims to identify immune-related biomarkers and pathways associated with the disease through bioinformatics analysis and animal experiments.

METHOD

Using SONFH-related datasets obtained from the GEO database, we performed differential expression analysis and weighted gene co-expression network analysis (WGCNA) to extract SONFH-related genes. A protein-protein interaction (PPI) network was then constructed, and core sub-network genes were identified. Immune cell infiltration and clustering analysis of SONFH samples were performed to assess differences in immune cell populations. WGCNA analysis was used to identify module genes associated with immune cells, and hub genes were identified using machine learning. Internal and external validation along with animal experiments were conducted to confirm the differential expression of hub genes and infiltration of immune cells in SONFH.

RESULTS

Differential expression analysis revealed 502 DEGs. WGCNA analysis identified a blue module closely related to SONFH, containing 1928 module genes. Intersection analysis between DEGs and blue module genes resulted in 453 intersecting genes. The PPI network and MCODE module identified 15 key targets enriched in various signaling pathways. Analysis of immune cell infiltration showed statistically significant differences in CD8 + t cells, monocytes, macrophages M2 and neutrophils between SONFH and control samples. Unsupervised clustering classified SONFH samples into two clusters (C1 and C2), which also exhibited significant differences in immune cell infiltration. The hub genes (ICAM1, NR3C1, and IKBKB) were further identified using WGCNA and machine learning analysis. Based on these hub genes, a clinical prediction model was constructed and validated internally and externally. Animal experiments confirmed the upregulation of hub genes in SONFH, with an associated increase in immune cell infiltration.

CONCLUSION

This study identified ICAM1, NR3C1, and IKBKB as potential immune-related biomarkers involved in immune cell infiltration of CD8 + t cells, monocytes, macrophages M2, neutrophils and other immune cells in the pathogenesis of SONFH. These biomarkers act through modulation of the chemokine signaling pathway, Toll-like receptor signaling pathway, and other pathways. These findings provide valuable insights into the disease mechanism of SONFH and may aid in future drug development efforts.

Propolis as an autophagy modulator in relation to its roles in redox balance and inflammation regulation

Autophagy is a degradation process that is evolutionarily conserved and is essential in maintaining cellular and physiological homeostasis through lysosomal removal and elimination of damaged peptides, proteins and cellular organelles. The dysregulation of autophagy is implicated in various diseases and disorders, including cancers, infection-related, and metabolic syndrome-related diseases. Propolis has been demonstrated in various studies including many human clinical trials to have antimicrobial, antioxidant, anti-inflammatory, immune-modulator, neuro-protective, and anti-cancer. Nevertheless, the autophagy modulation properties of propolis have not been extensively studied and explored. The role of propolis and its bioactive compounds in modulating cellular autophagy is possibly due to their dual role in redox balance and inflammation. The present review attempts to discuss the activities of propolis as an autophagy modulator in biological models in relation to various diseases/disorders which has implications in the development of propolis-based nutraceuticals, functional foods, and complementary therapies.

Noncoding RNAs: the crucial role of programmed cell death in osteoporosis

Osteoporosis is the most common skeletal disease characterized by an imbalance between bone resorption and bone remodeling. Osteoporosis can lead to bone loss and bone microstructural deterioration. This increases the risk of bone fragility and fracture, severely reducing patients' mobility and quality of life. However, the specific molecular mechanisms involved in the development of osteoporosis remain unclear. Increasing evidence suggests that multiple noncoding RNAs show differential expression in the osteoporosis state. Meanwhile, noncoding RNAs have been associated with an increased risk of osteoporosis and fracture. Noncoding RNAs are an important class of factors at the level of gene regulation and are mainly involved in cell proliferation, cell differentiation, and cell death. Programmed cell death is a genetically-regulated form of cell death involved in regulating the homeostasis of the internal environment. Noncoding RNA plays an important role in the programmed cell death process. The exploration of the noncoding RNA-programmed cell death axis has become an interesting area of research and has been shown to play a role in many diseases such as osteoporosis. In this review, we summarize the latest findings on the mechanism of noncoding RNA-mediated programmed cell death on bone homeostasis imbalance leading to osteoporosis. And we provide a deeper understanding of the role played by the noncoding RNA-programmed cell death axis at the gene regulatory level of osteoporosis. We hope to provide a unique opportunity to develop novel diagnostic and therapeutic approaches for osteoporosis.

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.

Regulatory mechanisms of autophagy-related ncRNAs in bone metabolic diseases

Bone metabolic diseases have been tormented and are plaguing people worldwide due to the lack of effective and thorough medical interventions and the poor understanding of their pathogenesis. Non-coding RNAs (ncRNAs) are heterogeneous transcripts that cannot encode the proteins but can affect the expressions of other genes. Autophagy is a fundamental mechanism for keeping cell viability, recycling cellular contents through the lysosomal pathway, and maintaining the homeostasis of the intracellular environment. There is growing evidence that ncRNAs, autophagy, and crosstalk between ncRNAs and autophagy play complex roles in progression of metabolic bone disease. This review investigated the complex mechanisms by which ncRNAs, mainly micro RNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), regulate autophagic pathway to assist in treating bone metabolism disorders. It aimed at identifying the autophagy role in bone metabolism disorders and understanding the role, potential, and challenges of crosstalk between ncRNAs and autophagy for bone metabolism disorders treatment.

Mechanisms of polydatin against spinal cord ischemia-reperfusion injury based on network pharmacology, molecular docking and molecular dynamics simulation

BACKGROUND

Polydatin has shown considerable pharmacological activities in ischemia-reperfusion injuries of various organs. However, its effects and mechanisms in spinal cord ischemia-reperfusion injury have not been fully established. In this study, the mechanisms of polydatin against spinal cord ischemia-reperfusion injury were investigated via network pharmacology, molecular docking and molecular dynamics simulation.

METHODS

Spinal cord ischemia-reperfusion injury-related targets were obtained from the GeneCards database, while polydatin-related action targets were obtained from the CTD and SwissTarget databases. A protein-protein interaction network of potential targets was constructed using the String platform. After selecting the potential key targets, GO functional enrichment and KEGG pathway enrichment analyses were performed via the Metascape database, and a network map of "drug-target-pathway-disease" constructed. The relationships between polydatin and various key targets were assessed via molecular docking. Molecular dynamics simulation was conducted for optimal core protein-compound complexes obtained by molecular docking.

RESULTS

Topological analysis of the PPI network revealed 14 core targets. GO functional enrichment analysis revealed that 435 biological processes, 12 cell components and 29 molecular functions were enriched while KEGG pathway enrichment analysis revealed 91 enriched signaling pathways. Molecular docking showed that polydatin had the highest binding affinity for MAPK3, suggesting that MAPK3 is a key target of polydatin against spinal cord ischemia-reperfusion injury. Molecular dynamics simulations revealed good binding abilities between polydatin and MAPK3.

CONCLUSIONS

Polydatin exerts its effects on spinal cord ischemia-reperfusion injury through multiple targets and pathways. MAPK3 may be a key target of polydatin in spinal cord ischemia-reperfusion injury.

Establishment of the multi-component bone-on-a-chip: to explore therapeutic potential of DNA aptamers on endothelial cells

Background: Despite great efforts to develop microvascular bone chips in previous studies, current bone chips still lacked multi-component of human-derived cells close to human bone tissue. Bone microvascular endothelial cells (BMECs) were demonstrated to be closely related to the glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). Tumor necrosis factor-alpha (TNF-α) aptamer has been proved to bind to its receptor and block cascade activities. Objective: There are two main objectives in this study: 1) to establish a multi-component bone-on-a-chip within the microfluidic system in vitro, 2) to explore the therapeutic potential of TNF-α aptamer on BMECs in the GC-induced ONFH model. Methods: Histological features of clinical samples were analyzed before BMECs isolation. The functional bone-on-a-chip consists of the vascular channel, stromal channel and structure channel. GC-induced ONFH model was established based on the multi-component of human-derived cells. Truncation and dimerization were performed on a previously reported DNA aptamer (VR11). BMECs apoptosis, cytoskeleton and angiogenesis status in the ONFH model were observed by the TUNEL staining and confocal microscope. Results: The multi-component of BMECs, human embryonic lung fibroblasts and hydroxyapatite were cultured within the microfluidic bone-on-a-chip. TNF-α was found up-regulated in the necrotic regions of femoral heads in clinical samples and similar results were re-confirmed in the ONFH model established in the microfluidic platform by detecting cell metabolites. Molecular docking simulations indicated that the truncated TNF-α aptamer could improve the aptamer-protein interactions. Further results from the TUNEL staining and confocal microscopy showed that the truncated aptamer could protect BMECs from apoptosis and alleviate GC-induced damages to cytoskeleton and vascularization. Conclusion: In summary, a microfluidic multi-component bone-on-a-chip was established with 'off-chip' analysis of cell metabolism. GC-induced ONFH model was achieved based on the platform. Our findings provided initial evidence on the possible potentials of TNF-α aptamer as a new type of TNF-α inhibitor for patients with ONFH.

Bioinformatics-Based Analysis of Key Genes in Steroid-Induced Osteonecrosis of the Femoral Head That Are Associated with Copper Metabolism

Osteonecrosis of the femoral head (ONFH) is a common disabling disease. Copper has positive effects on cells that regulate bone metabolism. However, the relationship between copper metabolism (CM) and steroid-induced ONFH (SONFH) remains unclear. The GSE123568 dataset was downloaded from the Gene Expression Omnibus. The differentially expressed CM-related SONFH genes (DE-CMR-SONFHGs) were identified via differential analysis and weighted gene coexpression network analysis (WGCNA). Receiver operating characteristic (ROC) analysis was performed for the predictive accuracy of key genes. Targeting drugs and the copper death-related genes (CDRGs) relevant to key genes were investigated. The bioinformatics results were confirmed via quantitative real-time polymerase chain reaction (qRT–PCR) and Western blot (WB) analysis. Two out of 106 DE-CMR-SONFHGs were identified as key genes (PNP and SLC2A1), which had diagnostic value in distinguishing SONFH from control samples and were related to various immune cell infiltrations. Eleven PMP-targeting drugs and five SLC2A1-targeting drugs were identified. The qRT–PCR, as well as WB, results confirmed the downregulation PNP and SLC2A1 and high expression of the CDRGs DLD, PDHB, and MTF1, which are closely related to these two key genes. In conclusion, PNP and SLC2A1 were identified as key genes related to SONFH and may provide insights for SONFH treatment.

Pesticides as a risk factor for cognitive impairment: Natural substances are expected to become alternative measures to prevent and improve cognitive impairment

Pesticides are the most effective way to control diseases, insects, weeds, and fungi. The central nervous system (CNS) is damaged by pesticide residues in various ways. By consulting relevant databases, the systemic relationships between the possible mechanisms of pesticides damage to the CNS causing cognitive impairment and related learning and memory pathways networks, as well as the structure-activity relationships between some natural substances (such as polyphenols and vitamins) and the improvement were summarized in this article. The mechanisms of cognitive impairment caused by pesticides are closely related. For example, oxidative stress, mitochondrial dysfunction, and neuroinflammation can constitute three feedback loops that interact and restrict each other. The mechanisms of neurotransmitter abnormalities and intestinal dysfunction also play an important role. The connection between pathways is complex. NMDAR, PI3K/Akt, MAPK, Keap1/Nrf2/ARE, and NF-κB pathways can be connected into a pathway network by targets such as Ras, Akt, and IKK. The reasons for the improvement of natural substances are related to their specific structure, such as polyphenols with different hydroxyl groups. This review's purpose is to lay a foundation for exploring and developing more natural substances that can effectively improve the cognitive impairment caused by pesticides.

A rescue diet raises the plasma calcium concentration and ameliorates rheumatoid arthritis in mice: Role of CaSR-mediated inhibition of osteoclastogenesis

Calcium modulates bone cell recruitment, differentiation, and function by binding to the calcium-sensing receptor (CaSR). However, the function of CaSR induced by high extracellular calcium (Ca²⁺ _e ) in the regulation of osteoclast formation in rheumatoid arthritis (RA) remains unknown. Here, we used TNFα-transgenic (TNF^TG ) RA mice and their wildtype (WT) littermates fed a normal or a rescue diet (high calcium, high phosphorus, and high lactose diet, termed rescue diet) to compare their joint bone phenotypes. In comparison to TNF^TG mice fed the normal diet, articular bone volume and cartilage area are increased, whereas inflamed area, eroded surface, TRAP⁺ surface, and osteoclast-related genes expression are decreased in TNF^TG mice fed the rescue diet. Besides, TNF^TG mice fed the rescue diet were found to exhibit more CaSR⁺ area and less NFATc1⁺ /TRAP⁺ area. Furthermore, at normal Ca²⁺ _e concentrations, osteoclast precursors (OCPs) from TNF^TG mice formed more osteoclasts than OCPs from WT mice, but the number of osteoclasts gradually decreased when the Ca²⁺ _e concentration increased. Meanwhile, the expression of CaSR increased responding to a high level of Ca²⁺ _e , whereas the expression of NF-κB/NFATc1 signaling molecules decreased. At last, the knockdown of CaSR blocked the inhibition of osteoclast differentiation attributed to high Ca²⁺ _e . Taken together, our findings indicate that high Ca²⁺ _e inhibits osteoclast differentiation in RA mice partially through the CaSR/NF-κB/NFATc1 pathway.

Cell death regulation: A new way for natural products to treat osteoporosis

Osteoporosis is a common metabolic bone disease that results from the imbalance of homeostasis within the bone. Intra-bone homeostasis is dependent on a precise dynamic balance between bone resorption by osteoclasts and bone formation by mesenchymal lineage osteoblasts, which comprises a series of complex and highly standardized steps. Programmed cell death (PCD) (e.g., apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis) is a cell death process that involves a cascade of gene expression events with tight structures. These events play a certain role in regulating bone metabolism by determining the fate of bone cells. Moreover, existing research has suggested that natural products derived from a wide variety of dietary components and medicinal plants modulate the PCDs based on different mechanisms, which show great potential for the prevention and treatment of osteoporosis, thus revealing the emergence of more acceptable complementary and alternative drugs with lower costs, fewer side effects and more long-term application. Accordingly, this review summarizes the common types of PCDs in the field of osteoporosis. Moreover, from the perspective of targeting PCDs, this review also discussed the roles of currently reported natural products in the treatment of osteoporosis and the involved mechanisms. Based on this, this review provides more insights into new molecular mechanisms of osteoporosis and provides a reference for developing more natural anti-osteoporosis drugs in the future.

Blocking Cx43 alleviates neuropathic pain in rats with chronic constriction injury via the P2X4 and P38/ERK-P65 pathways

Neuropathic pain is a growing concern in the medical community, and studies on new analgesic targets for neuropathic pain have become a new hot spot. Whether Connexin43 (Cx43) has a key role in neuropathic pain mediated by the purinergic 2X4 (P2X4) receptor in rats with chronic constriction injury (CCI) was explored in this study. Our experimental results show that blockade of Cx43 could attenuate neuropathic pain in rats suffering from CCI via the P2X4, p38, ERK, and NF-kB signalling pathways. These results suggest that Cx43 may be a promising therapeutic target for the development of novel pharmacological agents in the management of neuropathic pain.

Strategies of Macrophages to Maintain Bone Homeostasis and Promote Bone Repair: A Narrative Review

Bone homeostasis (a healthy bone mass) is regulated by maintaining a delicate balance between bone resorption and bone formation. The regulation of physiological bone remodeling by a complex system that involves multiple cells in the skeleton is closely related to bone homeostasis. Loss of bone mass or repair of bone is always accompanied by changes in bone homeostasis. However, due to the complexity of bone homeostasis, we are currently unable to identify all the mechanisms that affect bone homeostasis. To date, bone macrophages have been considered a third cellular component in addition to osteogenic spectrum cells and osteoclasts. As confirmed by co-culture models or in vivo experiments, polarized or unpolarized macrophages interact with multiple components within the bone to ensure bone homeostasis. Different macrophage phenotypes are prone to resorption and formation of bone differently. This review comprehensively summarizes the mechanisms by which macrophages regulate bone homeostasis and concludes that macrophages can control bone homeostasis from osteoclasts, mesenchymal cells, osteoblasts, osteocytes, and the blood/vasculature system. The elaboration of these mechanisms in this narrative review facilitates the development of macrophage-based strategies for the treatment of bone metabolic diseases and bone defects.

Autophagy: An important target for natural products in the treatment of bone metabolic diseases

Bone homeostasis depends on a precise dynamic balance between bone resorption and bone formation, involving a series of complex and highly regulated steps. Any imbalance in this process can cause disturbances in bone metabolism and lead to the development of many associated bone diseases. Autophagy, one of the fundamental pathways for the degradation and recycling of proteins and organelles, is a fundamental process that regulates cellular and organismal homeostasis. Importantly, basic levels of autophagy are present in all types of bone-associated cells. Due to the cyclic nature of autophagy and the ongoing bone metabolism processes, autophagy is considered a new participant in bone maintenance. Novel therapeutic targets have emerged as a result of new mechanisms, and bone metabolism can be controlled by interfering with autophagy by focusing on certain regulatory molecules in autophagy. In parallel, several studies have reported that various natural products exhibit a good potential to mediate autophagy for the treatment of metabolic bone diseases. Therefore, we briefly described the process of autophagy, emphasizing its function in different cell types involved in bone development and metabolism (including bone marrow mesenchymal stem cells, osteoblasts, osteocytes, chondrocytes, and osteoclasts), and also summarized research advances in natural product-mediated autophagy for the treatment of metabolic bone disease caused by dysfunction of these cells (including osteoporosis, rheumatoid joints, osteoarthritis, fracture nonunion/delayed union). The objective of the study was to identify the function that autophagy serves in metabolic bone disease and the effects, potential, and challenges of natural products for the treatment of these diseases by targeting autophagy.

Obesity and Bone Health: A Complex Relationship

Recent scientific evidence has shown an increased risk of fractures in patients with obesity, especially in those with a higher visceral adipose tissue content. This contradicts the old paradigm that obese patients were more protected than those with normal weight. Specifically, in older subjects in whom there is a redistribution of fat from subcutaneous adipose tissue to visceral adipose tissue and an infiltration of other tissues such as muscle with the consequent sarcopenia, obesity can accentuate the changes characteristic of this age group that predisposes to a greater risk of falls and fractures. Other factors that determine a greater risk in older subjects with obesity are chronic proinflammatory status, altered adipokine secretion, vitamin D deficiency, insulin resistance and reduced mobility. On the other hand, diagnostic tests may be influenced by obesity and its comorbidities as well as by body composition, and risk scales may underestimate the risk of fractures in these patients. Weight loss with physical activity programs and cessation of high-fat diets may reduce the risk. Finally, more research is needed on the efficacy of anti-osteoporotic treatments in obese patients.

Obesity, Bone Loss, and Periodontitis: The Interlink

Obesity and periodontitis are both common health concerns that have given rise to considerable economic and societal burden worldwide. There are established negative relationships between bone metabolism and obesity, obesity and diabetes mellitus (DM), and DM and periodontitis, to name a few, with osteoporosis being considered a long-term complication of obesity. In the oral cavity, bone metabolic disorders primarily display as increased risks for periodontitis and alveolar bone loss. Obesity-driven alveolar bone loss and mandibular osteoporosis have been observed in animal models without inoculation of periodontopathogens. Clinical reports have also indicated a possible association between obesity and periodontitis. This review systematically summarizes the clinical periodontium changes, including alveolar bone loss in obese individuals. Relevant laboratory-based reports focusing on biological interlinks in obesity-associated bone remodeling via processes like hyperinflammation, immune dysregulation, and microbial dysbiosis, were reviewed. We also discuss the potential mechanism underlying obesity-enhanced alveolar bone loss from both the systemic and periodontal perspectives, focusing on delineating the practical considerations for managing periodontal disease in obese patients.

The antagonistic effect of selenium on lead-induced apoptosis and necroptosis via P38/JNK/ERK pathway in chicken kidney

Lead (Pb), as a toxic heavy metal pollutant, has been paid much attention. Pb is often discharged into the environment through the soot, wastewater and waste residue in industrial production, which poses a great threat to animal health. Selenium (Se) is a trace element known to antagonize the toxicity caused by heavy metals. However, the interaction between Se and Pb in chicken kidney and its specific biological mechanism are still unclear. So, we constructed chicken models of Pb exposure and Pb, Se co-exposure. Therefore, we used western blot and qRT-PCR to detect the expression of related genes. The results showed that Pb activated the MAPK signaling pathway by up-regulating the expression of MARK pathway genes to induce the expression of pro-apoptotic genes and necroptosis-related genes. Se can regulate the MARK signaling pathway and attenuated the expression of MAPK pathway genes altered by Pb to reduce apoptosis and necroptosis of chicken kidney cells. Our study gives new ideas for the specific mechanism of Pb nephrotoxicity and provides a reference for comparative medicine and clinical medication.

Cryogenic 3D Printing of ß-TCP/PLGA Composite Scaffolds Incorporated With BpV (Pic) for Treating Early Avascular Necrosis of Femoral Head

Avascular necrosis of femoral head (ANFH) is a disease that is characterized by structural changes and collapse of the femoral head. The exact causes of ANFH are not yet clear, but small advances in etiopathogenesis, diagnosis and treatment are achieved. In this study, ß-tricalcium phosphate/poly lactic-co-glycolic acid composite scaffolds incorporated with bisperoxovanadium [bpV (pic)] (bPTCP) was fabricated through cryogenic 3D printing and were utilized to treat rat models with early ANFH, which were constructed by alcohol gavage for 6 months. The physical properties of bPTCP scaffolds and in vitro bpV (pic) release from the scaffolds were assessed. It was found that the sustained release of bpV (pic) promoted osteogenic differentiation and inhibited adipose differentiation of bone marrow-derived mesenchymal stem cells. Micro-computed tomography scanning and histological analysis confirmed that the progression of ANFH in rats was notably alleviated in bPTCP scaffolds. Moreover, it was noted that the bPTCP scaffolds inhibited phosphatase and tensin homolog and activated the mechanistic target of rapamycin signaling. The autophagy induced by bPTCP scaffolds could partially prevent apoptosis, promote osteogenesis and angiogenesis, and hence eventually prevent the progression of ANFH, suggesting that the bPTCP scaffold are promising candidate to treat ANFH.

Role of Autophagy Machinery Dysregulation in Bacterial Chondronecrosis with Osteomyelitis (BCO)

Autophagy is a cell survival and homeostasis mechanism involving lysosomal degradation of cellular components and foreign bodies. It plays a role in bone homeostasis, skeletal diseases, and bacterial infections as both a cell-survival or cell-death pathway. This study sought to determine if autophagy played a role in bacterial chondronecrosis with osteomyelitis (BCO). BCO is a prominent cause of lameness in modern broilers and results from bacterial infection of mechanically stressed leg bone growth plates. The protein and gene expression of key autophagy machinery was analyzed in both normal and BCO-affected broilers using real-time qPCR and immunoblot, respectively. Gene expression showed a significant downregulation of key target signatures involved in every stage of autophagy in BCO-affected bone, such as ATG13, SQSTM1 (p62), ATG9B, ATG16L, ATG12, LC3C, and RAB7A. Additionally, protein expression for LC3 was also significantly lower in BCO. An in vitro study using human fetal osteoblast cells challenged with BCO isolate, Staphylococcus agnetis 908, showed a similar dysregulation of autophagy machinery along with a significant decrease in cell viability. When autophagy was inhibited via 3-methyladenine or chloroquine, comparable decreases in cell viability were seen along with dysregulation of autophagy machinery. Together, these results are the first to implicate autophagy machinery dysregulation in the pathology of BCO.

Osteoimmune reaction caused by novel silicocarnotite bioceramic promoting osteogenesis through MAPK pathway

The host immune response to implant is a key factor in determining the fate of bone grafts, which is thought to be a regulator of tissue regeneration. Figuring out the...

Role of the major histocompatibility complex class II protein presentation pathway in bone immunity imbalance in postmenopausal osteoporosis

Bone immunity regulates osteoclast differentiation and bone resorption and is a potential target for the treatment of postmenopausal osteoporosis (PMOP). The molecular network between bone metabolism and the immune system is complex. However, the molecular mechanism underlying the involvement of the major histocompatibility complex class II (MHC-II) molecule protein presentation pathway in PMOP remains to be elucidated. The MHC-II molecule is a core molecule of the protein presentation pathway. It is combined with the processed short peptide and presented to T lymphocytes, thereby activating them to become effector T cells. T-cell-derived inflammatory factors promote bone remodeling in PMOP. Moreover, the MHC-II molecule is highly expressed in osteoclast precursors. MHC-II transactivator (CIITA) is the main regulator of MHC-II gene expression and the switch for protein presentation. CIITA is also a major regulator of osteoclast differentiation and bone homeostasis. Therefore, we hypothesized that the MHC-II promotes osteoclast differentiation, providing a novel pathogenic mechanism and a potential target for the treatment of PMOP.

Network Pharmacology-Based Analysis on the Action Mechanism of Oleanolic Acid to Alleviate Osteoporosis

Oleanolic acid (OA) is a triterpenoid commonly found in plants and has shown extensive pharmaceutical activities. This study aimed to investigate the underlying mechanism of antiosteoporosis (OP) action of OA by utilizing the network pharmacology approach and molecular docking methods. First, the targets of OA were identified using the GeneCards, Stitch, and Swisstarget databases, and the targets related to OP were mined using the NCBI, Genecards, and DisGeNet databases. The overlapped targets of OA and OP were regarded as candidate targets, and the String database was used to obtain the protein-protein interactions among the targets. Then, Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway enrichment pathways of the candidate targets were performed using the DAVID database. In addition, the top 16 targets in the protein interaction network were used for molecular docking. Finally, an animal model constructed using d-galactose-induced oxidative stress and a low-calcium diet with accelerated bone loss was used to verify the in vivo effects of OA on osteoporotic mice. A total of 42 candidate targets for OA to treat OP were obtained. According to the protein-protein interaction network, MAPK1 showed the highest connectivity with other proteins. Additionally, GO analysis identified the top 20 biological processes, 9 cellular components, and top 20 molecular functions. Moreover, the candidate targets were mainly involved in 13 signaling pathways such as TNF signaling pathway, insulin resistance, MAPK signaling pathway, apoptosis, and PI3K-Akt signaling pathways. Furthermore, molecular docking revealed that OA has a high degree of connections with 16 key proteins. In addition, the anti-OP effects of OA are further validated through the in vivo model. Altogether, our study elucidated the candidate targets for OA to alleviate OP, explored the protein-protein interactions and related signaling pathways of the targets, and validated the anti-OP effects of OA. It could provide a better understanding of the action mechanism in OA to treat OP.

Gujiansan Ameliorates Avascular Necrosis of the Femoral Head by Regulating Autophagy via the HIF-1α/BNIP3 Pathway

Background

Clinically, the traditional Chinese medicine compound Gujiansan has been widely used in the treatment of steroid-induced avascular necrosis of the femoral head (SANFH). The present study aimed to investigate the mechanisms underlying the therapeutic effect of Gujiansan.

Methods

A rat model of SANFH was established by the injection of dexamethasone (DEX) at a high dosage of 25 mg/kg/d. Then, Gujiansan was intragastrically administered for 2 weeks, 4 weeks, and 8 weeks, and histological examination of the femoral head was performed. The expression levels of related mRNAs and proteins were analyzed by qRT-PCR, Western blotting, and immunohistochemistry, and the levels of bone biochemical markers and cytokines were detected with ELISA kits.

Results

Gujiansan administration ameliorated SANFH and induced the expression of hypoxia-inducible factor-1α (HIF-1α), Bcl-2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3), LC3, and Beclin-1 in the rat model in a dose- and time-dependent manner, and Gujiansan promoted osteocalcin secretion at the femoral head. In addition, Gujiansan increased the levels of bone formation- and bone resorption-specific markers (osteocalcin (OC), bone-specific alkaline phosphatase (BAP), tartrate resistant acid phosphatase-5b (TRACP-5b), N-terminal telopeptides of type I collagen (NTX-1), and C-terminal telopeptide of type I collagen (CTX-1)) and decreased the levels of proinflammatory cytokines (TNF-α, IL-6, and CRP) in a dose- and time-dependent manner.

Conclusions

Gujiansan accelerates the formation of a new bone, promotes the absorption of the damaged bone, inhibits the inflammatory response, induces autophagy of the femoral head via the HIF-1α/BNIP3 pathway, and ultimately ameliorates SANFH.

Network Pharmacology-Based Investigation on the Anti-Osteoporosis Mechanism of Astragaloside IV

Astragaloside IV is the main active ingredient of Astragalus membranaceus. Studies have found that it can promote the proliferation of osteoblasts and can antagonize the apoptosis of mouse osteoblasts induced by hydrogen peroxide, but its molecular mechanism for the treatment of osteoporosis is still not clear. First, we used 3 online platforms: CTD, PharmMapper and SwissTargetPrediction to retrieve the targets of Astragaloside IV, and collected osteoporosis-related targets. Next, we used Cytoscape 3.7.2 software to construct a visual network diagram of PPI and further screened the key genes of Astragaloside IV in the treatment of osteoporosis using cluster analysis. Finally, after the receptor and ligand were docked, the binding activity was assessed by docking score. We obtained 102 overlapping targets of Astragaloside IV and osteoporosis. According to the node degree value in the PPI network, the top 10 genes were PIK3CA, MAPK1, SRC, STAT3, VEGFA, HSP90AA1, RELA, AKT1, IGF1, EGFR, of which SRC, AKT1, PIK3CA could bind stably to Astragaloside IV. KEGG pathway enrichment results showed that Astragaloside IV treated osteoporosis through 10 main pathways, including PI3K-Akt signaling pathway, FoxO signaling pathway, MAPK pathway, and so on. The classification of these pathways belongs to signal transduction, immune system, development and regeneration and endocrine system. Astragaloside IV is significantly related to several pathways involved in osteoporosis, such as PI3K-Akt, FoxO signaling pathway and MAPK pathway. SRC, AKT1, and PIK3CA can bind stably with Astragaloside IV, and they may be hub genes for the treatment of osteoporosis.

T-Cell Mediated Inflammation in Postmenopausal Osteoporosis

Osteoporosis is the most prevalent metabolic bone disease that affects half the women in the sixth and seventh decade of life. Osteoporosis is characterized by uncoupled bone resorption that leads to low bone mass, compromised microarchitecture and structural deterioration that increases the likelihood of fracture with minimal trauma, known as fragility fractures. Several factors contribute to osteoporosis in men and women. In women, menopause - the cessation of ovarian function, is one of the leading causes of primary osteoporosis. Over the past three decades there has been growing appreciation that the adaptive immune system plays a fundamental role in the development of postmenopausal osteoporosis, both in humans and in mouse models. In this review, we highlight recent data on the interactions between T cells and the skeletal system in the context of postmenopausal osteoporosis. Finally, we review recent studies on the interventions to ameliorate osteoporosis.

circRNA expression pattern and ceRNA network in the pathogenesis of aseptic loosening after total hip arthroplasty

Increasing evidence has demonstrated that circular RNA (circRNA) exerts important function in the pathogenesis of some diseases. While, the contributions of circRNAs to aseptic loosening after total hip arthroplasty (THA) remain largely unknown. Our research is to explore the differentially expressed circRNAs (DEcircRNAs) and elucidate complex regulated mechanism of circRNAs in aseptic loosening. The DEcircRNAs were identified by RNA sequencing (RNA-seq) analysis. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was adopted to corroborate these DEcircRNAs. The potential function of circRNAs in aseptic loosening tissue was identified by competing endogenous RNA (ceRNA) analysis. Enrichment analysis was performed for target mRNAs and host genes of the DEcircRNAs by Gene Oncology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). 257 DEcircRNAs were obtained from RNA-seq results. Following the RT-qPCR corroboration, 6 circRNAs (hsa_circ_0007482, hsa_circ_0005232, hsa_circ_0000994, hsa_circ_0000690, hsa_circ_0058092 and hsa_circ_0004496) were selected for further analysis. By circRNA-miRNA and miRNA-mRNA prediction, 6 circRNAs, 138 miRNAs and 1667 mRNAs were identified. Then, circRNA-miRNA-mRNA network was established. The result of GO and KEGG enrichment analysis suggested that the circRNAs were related with some biological functions and pathways of aseptic loosening. A novel pathogenesis and treatment strategy about aseptic loosening after THA was revealed from our study of circRNA-miRNA-mRNA network.

Antibacterial peptides inhibit MC3T3-E1 cells apoptosis induced by TNF-α through p38 MAPK pathway

Background

Antimicrobial peptides (AMP), as a small molecular polypeptide with a broad antibacterial spectrum and high efficiency, have attracted more and more attention. Few pieces of research on the effect of the antimicrobial peptide on osteoblast under inflammatory conditions have so far been reported. The main aim of this work was to investigate the antiapoptosis effect of the antimicrobial peptide on MC3T3-E1 cells induced by TNF-α and its related mechanism.

Methods

Rat MC3T3-E1 cells were co-cultured with different concentrations of antibacterial peptide DP7 and TNF-α.MTS assay, cell scratch test, alkaline phosphatase activity, and alizarin red staining assay were used to determine osteoblast viability in this experiment. Annexin V-FITC/PI double staining cells and flow cytometry were used to analyze apoptosis and Western blot assay detection to show mitogen-activated protein kinase (MAPK) protein expression in rat MC3T3-E1 cells. Then, Realtime polymerase chain reaction (PCR) was used to examine the caspase-3 gene expression. Also, ELISA detection was used to clarify the anti-apoptotic effect of the p38 MAPK inhibitor, SB203580, on cells’ apoptosis.

Results

Antimicrobial peptide could promote the proliferation, migration, and osteogenic ability of MC3T3-E1 cells induced by TNF-α, but inhibit cell apoptosis rate (P<0.05), and the effect was concentration-dependent. Western blot results showed after TNF-αtreatment, the expression of p-p38 MAPK in the MC3T3-E1 cells increased after TNF-α and antimicrobial peptide cotreatment, TNF-α induced p-p38 MAPK phosphorylation was inhibited, and the difference was statistically significant (P<0.05). Realtime PCR results showed that the gene expression of caspase-3 mRNA was up-regulated after TNF-α treatment, while their expression was down-regulated after cultured with TNF-α and antimicrobial peptide. Elisa's analysis showed that cell apoptosis increased after TNF-α treatment alone, and cell apoptosis was reduced to the normal levels when combined with antimicrobial peptide, and cell apoptosis induced by TNF-α was partially abolished when combined with SB203580.

Conclusions

Antimicrobial peptide DP7 could inhibit MC3T3-E1 cells apoptosis induced by TNF-α, and the effect was concentration-dependent. The antiapoptosis activation of the antimicrobial peptide on MC3TE-E1 cells may be related to the inhibition of the p38 MAPK pathway.