Resveratrol promotes osteogenesis via activating SIRT1/FoxO1 pathway in osteoporosis mice

Obesity induced caveolin-1 impairs osteogenesis via activating mitophagy and inhibiting Sirt1 signaling

Obesity has become a major global health problem and the effect on bone formation has received increasing attention. However, the interaction between obesity and bone metabolism is complex and still not fully understood. Here, we show that caveolin-1 (Cav1), a membrane scaffold protein involved in regulating a variety of cellular processes, plays a key regulatory role as a bridge connecting obesity and bone metabolism. High-fat diet (HFD)-induced obese C57BL/6J mouse displayed a significant increase in Cav1 expression and lower osteogenic activity; In vitro treatment of osteoblastic MC3T3-E1 cells with 1 mM free fatty acids (FFA) significantly promoted Cav1 expression and PINK1/Parkin regulated mitophagy, but inhibited the expression of osteogenic marker genes. Conversely, reduced expression of the Cav1 gene prevented these effects. Both endogenous oxidative stress and Sirt1 pathway were also significantly reduced after Cav1 knockdown in FFA-treated cells. Finally, Cav1-Sirt1 docking and co-immunoprecipitation results showed that Cav1 interacted with Sirt1 and FFA enhanced the interaction. Taken together, these results suggest that obesity impairs bone development and formation through up-regulation of the Cav1 gene, which lead to inhibition of Sirt1/FOXO1 and Sirt1/PGC-1α signaling pathways through interacting with Sirt1 molecule, and an increase of mitophagy level.

Anti-osteoporosis effect of bioactives in edible medicinal plants: a comprehensive review

Current treatments for osteoporosis include a calcium-rich diet, adequate exercise, and medication. Many synthetic drugs, although fast-acting, can cause a range of side effects for patients when taken over a long period, such as irritation of the digestive tract and a burden on the kidneys. As the world's population ages, the prevalence of osteoporosis is increasing, and the development of safe and effective treatments is urgently needed. Active compounds in edible and medicinal homologous plants have been used for centuries to improve bone quality. It is possible to employ them as dietary supplements to prevent osteoporosis. In this review, we analyze the influencing factors of osteoporosis and systematically summarize the research progress on the anti-osteoporosis effects of active compounds in edible and medicinal homologous plants. The literature suggests that some naturally occurring active compounds in edible and medicinal homologous plants can inhibit bone loss, prevent the degeneration of bone cell microstructure, and reduce bone fragility through alleviating oxidative stress, regulating autophagy, anti-inflammation, improving gut flora, and regulating estrogen level with little side effects. Our review provides useful guidance for the use of edible and medicinal homologous plants and the development of safer novel anti-osteoporosis dietary supplements.

Microbiota and Resveratrol: How Are They Linked to Osteoporosis?

Osteoporosis (OP), which is characterized by a decrease in bone density and increased susceptibility to fractures, is closely linked to the gut microbiota (GM). It is increasingly realized that the GM plays a key role in the maintenance of the functioning of multiple organs, including bone, by producing bioactive metabolites such as short-chain fatty acids (SCFA). Consequently, imbalances in the GM, referred to as dysbiosis, have been identified with a significant reduction in beneficial metabolites, such as decreased SCFA associated with increased chronic inflammatory processes, including the activation of NF-κB at the epigenetic level, which is recognized as the main cause of many chronic diseases, including OP. Furthermore, regular or long-term medications such as antibiotics and many non-antibiotics such as proton pump inhibitors, chemotherapy, and NSAIDs, have been found to contribute to the development of dysbiosis, highlighting an urgent need for new treatment approaches. A promising preventive and adjuvant approach is to combat dysbiosis with natural polyphenols such as resveratrol, which have prebiotic functions and ensure an optimal microenvironment for beneficial GM. Resveratrol offers a range of benefits, including anti-inflammatory, anti-oxidant, analgesic, and prebiotic effects. In particular, the GM has been shown to convert resveratrol, into highly metabolically active molecules with even more potent beneficial properties, supporting a synergistic polyphenol-GM axis. This review addresses the question of how the GM can enhance the effects of resveratrol and how resveratrol, as an epigenetic modulator, can promote the growth and diversity of beneficial GM, thus providing important insights for the prevention and co-treatment of OP.

Revealing the key role of cuproptosis in osteoporosis via the bioinformatic analysis and experimental validation of cuproptosis-related genes

The incidence of osteoporosis has rapidly increased owing to the ageing population. Cuproptosis, a novel mechanism that regulates cell death, may be a new therapeutic approach. However, the relevance of cuproptosis in the immune microenvironment and osteoporosis immunotherapy is still unknown. We intersected the differentially expressed genes from osteoporotic samples with 75 cuproptosis-related genes to identify 16 significantly expressed cuproptosis genes. We further explored the connection between the cuproptosis pattern, immune microenvironment, and immunotherapy. The weighted gene co-expression network analysis algorithm was used to identify cuproptosis phenotype-associated genes, and we used quantitative real-time PCR and immunohistochemistry in mouse femur tissues to verify hub gene (MAP2K2, FDX1, COX19, VEGFA, CDKN2A, and NFE2L2) expression. Six hub genes and 59 cuproptosis phenotype-associated genes involved in immunisation were identified among the osteoporosis and control groups, and the majority of these 59 genes were enriched in the inflammatory response, as well as in signal transducers, Janus kinase, and transcription pathway activators. In addition, two different clusters of cuproptosis were found, and immune infiltration analysis showed that gene Cluster 1 had a greater immune score and immune infiltration level. Further analysis revealed that three key genes (COX19, MAP2K2, and FDX1) were highly correlated with immune cell infiltration, and external experiments validated the association of these three genes with the prognosis of osteoporosis. We used the three key mRNAs COX19, MAP2K2, and FDX1 as a classification model that may systematically elucidate the complex connection between cuproptosis and the immune microenvironment of osteoporosis. New insights into osteoporosis pathogenesis and immunotherapy prospects may be gained from this study.

Ghrelin alleviates intestinal ischemia-reperfusion injury by activating the GHSR-1α/Sirt1/FOXO1 pathway

Ischemia-reperfusion (IR) injury is primarily characterized by the restoration of blood flow perfusion and oxygen supply to ischemic tissue and organs, but it paradoxically leads to tissue injury aggravation. IR injury is a challenging pathophysiological process that is difficult to avoid clinically and frequently occurs during organ transplantation, surgery, shock resuscitation, and other processes. The major causes of IR injury include increased levels of free radicals, calcium overload, oxidative stress, and excessive inflammatory response. Ghrelin is a newly discovered brain-intestinal peptide with anti-inflammatory and antiapoptotic effects that improve blood supply. The role and mechanism of ghrelin in intestinal ischemia-reperfusion (IIR) injury remain unclear. We hypothesized that ghrelin could attenuate IIR-induced oxidative stress and apoptosis. To investigate this, we established IIR by using a non-invasive arterial clip to clamp the root of the superior mesenteric artery (SMA) in mice. Ghrelin was injected intraperitoneally at a dose of 50 μg/kg 20 min before IIR surgery, and [D-Lys3]-GHRP-6 was injected intraperitoneally at a dose of 12 nmol/kg 20 min before ghrelin injection. We mimicked the IIR process with hypoxia-reoxygenation (HR) in Caco-2 cells, which are similar to intestinal epithelial cells in structure and biochemistry. Our results showed that ghrelin inhibited IIR/HR-induced oxidative stress and apoptosis by activating GHSR-1α. Moreover, it was found that ghrelin activated the GHSR-1α/Sirt1/FOXO1 signaling pathway. We further inhibited Sirt1 and found that Sirt1 was critical for ghrelin-mediated mitigation of IIR/HR injury. Overall, our data suggest that pretreatment with ghrelin reduces oxidative stress and apoptosis to attenuate IIR/HR injury by binding with GHSR-1α to further activate Sirt1.

Lycopene Promotes Osteogenesis and Reduces Adipogenesis through Regulating FoxO1/PPARγ Signaling in Ovariectomized Rats and Bone Marrow Mesenchymal Stem Cells

Recent interest in preventing the development of osteoporosis has focused on the regulation of redox homeostasis. However, the action of lycopene (LYC), a strong natural antioxidant compound, on osteoporotic bone loss remains largely unknown. Here, we show that oral administration of LYC to OVX rats for 12 weeks reduced body weight gain, improved lipid metabolism, and preserved bone quality. In addition, LYC treatment inhibited ROS overgeneration in serum and bone marrow in OVX rats, and in BMSCs upon H2O2 stimulation, leading to inhibiting adipogenesis and promoting osteogenesis during bone remodeling. At the molecular level, LYC improved bone quality via an increase in the expressions of FoxO1 and Runx2 and a decrease in the expressions of PPARγ and C/EBPα in OVX rats and BMSCs. Collectively, these findings suggest that LYC attenuates osteoporotic bone loss through promoting osteogenesis and inhibiting adipogenesis via regulation of the FoxO1/PPARγ pathway driven by oxidative stress, presenting a novel strategy for osteoporosis management.

Th17 Cell-Related Gene Biomarkers in Osteoporosis: Comprehensive Bioinformatics Analysis and In Vivo Validation

The interaction between the bone and immune systems has a major role in osteoporosis regulation. However, the infiltration of T helper 17 (Th17) cells and their associated genes in osteoporosis remains unclear. The GSE35959 dataset was obtained from the Gene Expression Omnibus (GEO) database, and the Immune Cell Abundance Identifier (ImmuCellAI) program was used to evaluate the abundance of 24 immune cell types, including Th17 cells. Differential analysis and relevance analysis were performed to identify differentially expressed Th17 cell-related genes (DETh17RGs) in osteoporosis. The potential functions of DETh17RGs were analyzed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment. Hub DETh17RGs were obtained through comprehensive analysis using Weighted Gene Co-Expression Network Analysis (WGCNA) and the CytoHubba plug-in algorithm. The expression levels of hub genes were validated using additional osteoporosis datasets. Additionally, the transcript levels of Hub genes in a mice model of osteoporosis were examined using quantitative PCR (qPCR). 464 DETh17RGs were identified in this study, with 421 genes showing positive associations and 43 genes showing negative associations. Among these, seven genes (CD44, TGFB1, ACTN4, ARHGDIA, ESR1, TLN1, FLNA) were considered as Hub DETh17RGs. The qPCR transcript levels of hub DETh17RGs in a mice model of osteoporosis exhibited consistent expression trends with the bioinformatics analysis. This research enhances our understanding of the molecular mechanisms involving Th17 cells in the development of osteoporosis and contributes to the discovery of potential biomarkers.

Sirt1 alleviates osteoarthritis via promoting FoxO1 nucleo-cytoplasm shuttling to facilitate autophagy

This study aims to investigate the role and underlying mechanisms of Sirt1 in the pathophysiological process of OA. Safranine O and HE staining were utilized to identify pathological changes in the cartilage tissue. Immunohistochemistry was employed to evaluate the expression levels of proteins. IL-1β treatment and TamCartSirt1flox/flox mice were utilized to induce OA model both in vitro and in vivo. Key autophagy-related transcription factors, autophagy-related genes, and chondrocyte extracellular matrix (ECM) breakdown enzyme markers were examined using multi assays. Immunofluorescence staining revealed subcellular localization and gene expression patterns. ChIP assay and Co-immunoprecipitation assay were conducted to investigate the interactions between FoxO1 and the promoter regions of Atg7 and Sirt1. Our results demonstrate that Sirt1 deficiency exhibited inhibitory effects on ECM synthesis and autophagy, as well as exacerbated angiogenesis. Moreover, Atg7, Foxo1, and Sirt1 could form a protein complex. Sirt1 was observed to facilitate nuclear translocation of FoxO1, enhancing its transcriptional activity. Furthermore, FoxO1 was found to bind to the promoter regions of Atg7 and Sirt1, potentially regulating their expression. This study provides valuable insights into the involvement of Sirt1-Atg7-FoxO1 loop in OA, opening new avenues for targeted therapeutic interventions aiming to mitigate cartilage degradation and restore joint function.

Effects of the combination of Epimedii Folium and Ligustri Lucidi Fructus on apoptosis and autophagy in SOP rats and osteoblasts via PI3K/AKT/mTOR pathway

BACKGROUND

This study aimed to investigate the effects of the combination of Epimedii Folium (EF) and Ligustri Lucidi Fructus (LLF) on regulating apoptosis and autophagy in senile osteoporosis (SOP) rats.

METHODS

Firstly, we identified the components in the decoction and drug-containing serum of EL (EF&LLF) by Ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS). Secondly, SOP rats were treated with EF, LLF, EL and caltrate to evaluate the advantages of EL. Finally, H2O2-, chloroquine-, and MHY1485-induced osteoblasts were treated with different doses of EL to reveal the molecular mechanism of EL. We detected bone microstructure, oxidative stress levels, ALP activity and the expressions of Bax, Bcl-2, caspase3, P53, Beclin-1, p-PI3K, PI3K, p-Akt, Akt, p-mTOR, mTOR, and LC3 in vivo and in vitro.

RESULTS

36 compounds in EL decoction and 23 in EL-containing serum were identified, including flavonoids, iridoid terpenoids, phenylethanoid glycosides, polyols and triterpenoids. EL could inhibit apoptosis activity and increase ALP activity. In SOP rats and chloroquine-inhibited osteoblasts, EL could improve bone tissue microstructure and osteoblasts functions by upregulating Bcl-2, Beclin1, and LC3-II/LC3-I, while downregulating p53 in all treatment groups. In H2O2-induced osteoblasts, EL could upregulate the protein and mRNA expressions of Bcl-2 while downregulate LC3-II/LC3-I, p53 and Beclin1. Besides, EL was able to down-regulate PI3K/AKT/mTOR pathway which activated in SOP rats and MHY1485-induced osteoblasts.

CONCLUSIONS

These findings demonstrate that EL with bone protective effects on SOP rats by regulating autophagy and apoptosis via PI3K/Akt/mTOR signaling pathway, which might be an alternative medicine for the treatment of SOP.

Mg-ZIF nanozyme regulates the switch between osteogenic and lipogenic differentiation in BMSCs via lipid metabolism

The accumulation of reactive oxygen species (ROS) within the bone marrow microenvironment leads to diminished osteogenic differentiation and heightened lipogenic differentiation of mesenchymal stem cells residing in the bone marrow, ultimately playing a role in the development of osteoporosis (OP). Mitigating ROS levels is a promising approach to counteracting OP. In this study, a nanozyme composed of magnesium-based zeolitic imidazolate frameworks (Mg-ZIF) was engineered to effectively scavenge ROS and alleviate OP. The results of this study indicate that Mg-ZIF exhibits significant potential in scavenging ROS and effectively promoting osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Additionally, Mg-ZIF was found to inhibit the differentiation of BMSCs into adipose cells. In vivo experiments further confirmed the ability of Mg-ZIF to mitigate OP by reducing ROS levels. Mechanistically, Mg-ZIF enhances the differentiation of BMSCs into osteoblasts by upregulating lipid metabolic pathways through ROS scavenging. The results indicate that Mg-ZIF has potential as an effective therapeutic approach for the treatment of osteoporosis.

Exploring epigenetic strategies for the treatment of osteoporosis

The worldwide trend toward an aging population has resulted in a higher incidence of chronic conditions, such as osteoporosis. Osteoporosis, a prevalent skeletal disorder characterized by decreased bone mass and increased fracture risk, encompasses primary and secondary forms, each with distinct etiologies. Mechanistically, osteoporosis involves an imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Current pharmacological interventions for osteoporosis, such as bisphosphonates, denosumab, and teriparatide, aim to modulate bone turnover and preserve bone density. Hormone replacement therapy and lifestyle modifications are also recommended to manage the condition. While current medications offer therapeutic options, they are not devoid of limitations. Recent studies have highlighted the importance of epigenetic mechanisms, including DNA methylation and histone modifications, in regulating gene expression during bone remodeling. The use of epigenetic drugs, or epidrugs, to target these mechanisms offers a promising avenue for therapeutic intervention in osteoporosis. In this review, we comprehensively examine the recent advancements in the application of epidrugs for treating osteoporosis.

Hippocampal and gut AMPK activation attenuates enterocolitis-like symptoms and co-occurring depressive-like behavior in ulcerative colitis model mice: Involvement of brain-gut autophagy

Patients with inflammatory bowel disease, including ulcerative colitis (UC) and Crohn's disease, have a high incidence of psychiatric disorders, including depression and anxiety. However, the underlying pathogenic mechanism remains unknown. Dextran sulfate sodium (DSS)-treated mice, a model of UC, exhibit depressive-like behavior and reduced adenosine monophosphate-activated protein kinase (AMPK) activity, which regulates various physiological functions in the brain and gut. However, comprehensive studies on UC pathophysiology with co-occurring depression focused on brain-gut AMPK activity are lacking. Therefore, we aimed to investigate whether resveratrol (RES), an AMPK activator, prevented DSS-induced UC-like symptoms and depressive-like behavior. DSS treatment induced UC-like pathology and depressive-like behavior, as assessed via the tail suspension test. Moreover, western blotting and immunohistochemical studies revealed that DSS increased p-p70S6 kinase (Thr389), p62, tumor necrosis factor-α, interleukin (IL)-1β, IL-18, NLR family pyrin domain containing 3 (NLRP3), cleaved caspase-1, cleaved Gasdermin-D (GSDMD), and cleaved caspase-3 expression levels in the rectum and hippocampus, and increased CD40, iNOS, and Kelch-like ECH-associated protein 1 expression levels, and the number of Iba1-positive cells in the hippocampus, and decreased p-AMPK and LC3II/I expression levels, and the number of NF-E2-related factor 2 (Nrf2)-positive cells, and reduced neurogenesis in the hippocampus. These changes were reversed by the RES administration. RES also enhanced PGC1α and SOD1 expression in the hippocampus of DSS-treated male mice. Moreover, NLRP3 staining was observed in the neurons and microglia, and cleaved GSDMD staining in neurons in the hippocampus of DSS-treated mice. Notably, RES prevented UC-like pathology and depressive-like behavior and enhancement of autophagy, decreased rectal and hippocampal inflammatory cytokines and inflammasome, and induced the Nrf2-PGC1α-SOD1 pathway in the hippocampus, resulting in neurogenesis in the hippocampal dentate gyrus. Our findings suggest that brain-gut AMPK activation may be an important therapeutic strategy in patients with UC and depression.

Lipoteichoic acid restrains macrophage senescence via β-catenin/FOXO1/REDD1 pathway in age-related osteoporosis

Osteoporosis and its related fractures are common causes of morbidity and mortality in older adults, but its underlying molecular and cellular mechanisms remain largely unknown. In this study, we found that lipoteichoic acid (LTA) treatment could ameliorate age-related bone degeneration and attenuate intramedullary macrophage senescence. FOXO1 signaling, which was downregulated and deactivated in aging macrophages, played a key role in the process. Blocking FOXO1 signaling caused decreased REDD1 expression and increased phosphorylation level of mTOR, a major driver of aging, as well as aggravated bone loss and deteriorated macrophage senescence. Moreover, LTA elevated FOXO1 signaling through β-catenin pathway while β-catenin inhibition significantly suppressed FOXO1 signaling, promoted senescence-related protein expression, and accelerated bone degeneration and macrophage senescence. Our findings indicated that β-catenin/FOXO1/REDD1 signaling plays a physiologically significant role that protecting macrophages from senescence during aging.

Resveratrol as sensitizer in colorectal cancer plasticity

Despite tremendous medical treatment successes, colorectal cancer (CRC) remains a leading cause of cancer deaths worldwide. Chemotherapy as monotherapy can lead to significant side effects and chemoresistance that can be linked to several resistance-activating biological processes, including an increase in inflammation, cellular plasticity, multidrug resistance (MDR), inhibition of the sentinel gene p53, and apoptosis. As a consequence, tumor cells can escape the effectiveness of chemotherapeutic agents. This underscores the need for cross-target therapeutic approaches that are not only pharmacologically safe but also modulate multiple potent signaling pathways and sensitize cancer cells to overcome resistance to standard drugs. In recent years, scientists have been searching for natural compounds that can be used as chemosensitizers in addition to conventional medications for the synergistic treatment of CRC. Resveratrol, a natural polyphenolic phytoalexin found in various fruits and vegetables such as peanuts, berries, and red grapes, is one of the most effective natural chemopreventive agents. Abundant in vitro and in vivo studies have shown that resveratrol, in interaction with standard drugs, is an effective chemosensitizer for CRC cells to chemotherapeutic agents and thus prevents drug resistance by modulating multiple pathways, including transcription factors, epithelial-to-mesenchymal transition-plasticity, proliferation, metastasis, angiogenesis, cell cycle, and apoptosis. The ability of resveratrol to modify multiple subcellular pathways that may suppress cancer cell plasticity and reversal of chemoresistance are critical parameters for understanding its anti-cancer effects. In this review, we focus on the chemosensitizing properties of resveratrol in CRC and, thus, its potential importance as an additive to ongoing treatments.

Molecular mechanism of resveratrol promoting differentiation of preosteoblastic MC3T3-E1 cells based on network pharmacology and experimental validation

The purpose of this study was to investigate the mechanism by which resveratrol (Res) inhibits apoptosis and promotes proliferation and differentiation of pre-osteoblastic MC3T3-E1 cells, laying the groundwork for the treatment of osteoporosis (OP). The TCMSP database was used to find the gene targets for Res. The GeneCards database acquire the gene targets for OP. After discovering the potential target genes, GO, KEGG, and Reactome enrichment analysis were conducted. Verifying the major proteins involved in apoptosis can bind to Res using molecular docking. CCK8 measured the proliferative activity of mouse pre-osteoblasts in every group following Res intervention. Alkaline phosphatase staining (ALP) and alizarin red staining to measure the ability of osteogenic differentiation. RT-qPCR to determine the expression levels of Runx2 and OPG genes for osteogenic differentiation ability of cells. Western blot to measure the degree of apoptosis-related protein activity in each group following Res intervention. The biological processes investigated for GO of Res therapeutic OP involved in cytokine-mediated signaling pathway, negative regulation of apoptotic process, Aging, extrinsic apoptotic signaling pathway in absence of ligand, according to potential therapeutic target enrichment study. Apoptosis, FoxO signaling pathway, and TNF signaling pathway are the primary KEGG signaling pathways. Recactome pathways are primarily engaged in Programmed Cell Death, Apoptosis, Intrinsic Apoptotic Pathway, and Caspase activation via extrinsic apoptotic signaling pathways. This research established a new approach for Res treatment of OP by demonstrating how Res controls the apoptosis-related proteins TNF, IL6, and CASP3 to suppress osteoblast death and increase osteoclastogenesis.

The effects of resveratrol in animal models of primary osteoporosis: a systematic review and meta-analysis

BACKGROUND

There is still a lack of sufficient evidence-based medical data on the effect of resveratrol (Res) on primary osteoporosis (OP). This meta-analysis aimed to comprehensively evaluate the role of Res in animal models of primary OP.

METHODS

The PubMed, Cochrane Library, Web of Science and Embase databases were searched up to August 2023. The risk of bias was assessed by the SYRCLE RoB tool. Random- or fixed-effects models were used to determine the 90% confidence interval (CI) or standardized mean difference (SMD). Statistical analysis was performed with RevMan 5.4 and Stata 14.0.

RESULTS

A total of 24 studies containing 714 individuals were included. Compared with those in the control group, the bone mineral density (BMD) (P < 0.00001), bone volume/total volume (BV/TV) (P < 0.001), trabecular thickness (Tb.Th) (P < 0.00001), and trabecular number (Tb.N) (P < 0.00001) were markedly greater, and the trabecular separation (Tb.Sp) (P < 0.00001) was significantly greater. Compared with the control group, the Res group also exhibited marked decreases in alkaline phosphatase (ALP) (P < 0.05), tartrate-resistant acid phosphatase 5b (TRAP5b) (P < 0.01), and type I collagen strong carboxyl peptide (CTX-1) (P < 0.00001) and a marked increase in osteoprotegerin (OPG) (P < 0.00001).

CONCLUSION

In summary, we concluded that Res can markedly increase BMD, improve morphometric indices of trabecular microstructure and serum bone turnover markers (BTMs), and exert a protective effect in animal models of primary osteoporosis. This study can supply experimental reference for Res in primary osteoporosis treatment.

Mitochondrial dysfunction and therapeutic perspectives in osteoporosis

Osteoporosis (OP) is a systemic skeletal disorder characterized by reduced bone mass and structural deterioration of bone tissue, resulting in heightened vulnerability to fractures due to increased bone fragility. This condition primarily arises from an imbalance between the processes of bone resorption and formation. Mitochondrial dysfunction has been reported to potentially constitute one of the most crucial mechanisms influencing the pathogenesis of osteoporosis. In essence, mitochondria play a crucial role in maintaining the delicate equilibrium between bone formation and resorption, thereby ensuring optimal skeletal health. Nevertheless, disruption of this delicate balance can arise as a consequence of mitochondrial dysfunction. In dysfunctional mitochondria, the mitochondrial electron transport chain (ETC) becomes uncoupled, resulting in reduced ATP synthesis and increased generation of reactive oxygen species (ROS). Reinforcement of mitochondrial dysfunction is further exacerbated by the accumulation of aberrant mitochondria. In this review, we investigated and analyzed the correlation between mitochondrial dysfunction, encompassing mitochondrial DNA (mtDNA) alterations, oxidative phosphorylation (OXPHOS) impairment, mitophagy dysregulation, defects in mitochondrial biogenesis and dynamics, as well as excessive ROS accumulation, with regards to OP (Figure 1). Furthermore, we explore prospective strategies currently available for modulating mitochondria to ameliorate osteoporosis. Undoubtedly, certain therapeutic strategies still require further investigation to ensure their safety and efficacy as clinical treatments. However, from a mitochondrial perspective, the potential for establishing effective and safe therapeutic approaches for osteoporosis appears promising.

Polyphenols as potential preventers of osteoporosis: A comprehensive review on antioxidant and anti-inflammatory effects, molecular mechanisms, and signal pathways in bone metabolism

Osteoporosis (OP) is a skeletal disorder characterized by decreased bone density, alterations in bone microstructure, and increased damage to the bones. As the population ages and life expectancy increases, OP has become a global epidemic, drawing attention from scientists and doctors. Because of polyphenols have favorable antioxidant and anti-allergy effects, which are regarded as potential methods to prevent angiocardipathy and OP. Polyphenols offer a promising approach to preventing and treating OP by affecting bone metabolism, reducing bone resolution, maintaining bone density, and lowering the differentiation level of osteoclasts (OC). There are multiple ways in which polyphenols affect bone metabolism. This article provides an overview of how polyphenols inhibit oxidative stress, exert antibacterial effects, and prevent the occurrence of OP. Furthermore, we will explore the regulatory mechanisms and signaling pathways implicated in this process.

Systems genetics and bioinformatics analyses using ESR1-correlated genes identify potential candidates underlying female bone development

Estrogen receptor α (ESR1) is involved in E2 signaling and plays a major role in postmenopausal bone loss. However, the molecular network underlying ESR1 has not been explored. We used systems genetics and bioinformatics to identify important genes associated with Esr1 in postmenopausal bone loss. We identified ~2300 Esr1-coexpressed genes in female BXD bone femur, functional analysis of which revealed 'osteoblast signaling' as the most enriched pathway. PPI network led to the identification of 25 'female bone candidates'. The gene-regulatory analysis revealed RUNX2 as a key TF. ANKRD1 and RUNX2 were significantly different between osteoporosis patients and healthy controls. Sp7, Col1a1 and Pth1r correlated with multiple femur bone phenotypes in BXD mice. miR-3121-3p targeted Csf1, Ankrd1, Sp7 and Runx2. β-estradiol treatment markedly increased the expression of these candidates in mouse osteoblast. Our study revealed that Esr1-correlated genes Ankrd1, Runx2, Csf1 and Sp7 may play important roles in female bone development.

An Injectable Thermosensitive Hydrogel Containing Resveratrol and Dexamethasone-Loaded Carbonated Hydroxyapatite Microspheres for the Regeneration of Osteoporotic Bone Defects

Bone defects in osteoporosis usually present excessive reactive oxygen species (ROS), abnormal inflammation levels, irregular shapes and impaired bone regeneration ability; therefore, osteoporotic bone defects are difficult to repair. In this study, an injectable thermosensitive hydrogel poly (D, L-lactide)-poly (ethylene glycol)- poly (D, L-lactide) (PLEL) system containing resveratrol (Res) and dexamethasone (DEX) is designed to create a microenvironment conducive to osteogenesis in osteoporotic bone defects. This PLEL hydrogel is injected and filled irregular defect areas and achieving a rapid sol-gel transition in situ. Res has a strong anti-inflammatory effects that can effectively remove excess free radicals at the damaged site, guide macrophage polarization to the M2 phenotype, and regulate immune responses. Additionally, DEX can promote osteogenic differentiation. In vitro experiments showed that the hydrogel effectively promoted osteogenic differentiation of mesenchymal stem cells, removed excess intracellular ROS, and regulated macrophage polarization to reduce inflammatory responses. In vivo experiments showed that the hydrogel promoted osteoporotic bone defect regeneration and modulated immune responses. Overall, this study confirmed that the hydrogel can treat osteoporotic bone defects by synergistically modulating bone damage microenvironment, alleviating inflammatory responses, and promoting osteogenesis; thus, it represents a promising drug delivery strategy to repair osteoporotic bone defects.

Platelet factor 4 induces bone loss by inhibiting the integrin α5-FAK-ERK pathway

BACKGROUND

The effect of platelet factor 4 (PF4) on bone marrow mesenchymal stem cells (BMMSCs) and osteoporosis is poorly understood. Therefore, this study aimed to evaluate the effects of PF4-triggered bone destruction in mice and determine the underlying mechanism.

METHODS

First, in vitro cell proliferation and cell cycle of BMMSCs were assessed using a CCK8 assay and flow cytometry, respectively. Osteogenic differentiation was confirmed using staining and quantification of alkaline phosphatase and Alizarin Red S. Next, an osteoporotic mouse model was established by performing bilateral ovariectomy (OVX). Furthermore, the PF4 concentrations were obtained using enzyme-linked immunosorbent assay. The bone microarchitecture of the femur was evaluated using microCT and histological analyses. Finally, the key regulators of osteogenesis and pathways were investigated using quantitative real-time polymerase chain reaction and Western blotting.

RESULTS

Human PF4 widely and moderately decreased the cell proliferation and osteogenic differentiation ability of BMMSCs. Furthermore, the levels of PF4 in the serum and bone marrow were generally increased, whereas bone microarchitecture deteriorated due to OVX. Moreover, in vivo mouse PF4 supplementation triggered bone deterioration of the femur. In addition, several key regulators of osteogenesis were downregulated, and the integrin α5-focal adhesion kinase-extracellular signal-regulated kinase (ITGA5-FAK-ERK) pathway was inhibited due to PF4 supplementation.

CONCLUSIONS

PF4 may be attributed to OVX-induced bone loss triggered by the suppression of bone formation in vivo and alleviate BMMSC osteogenic differentiation by inhibiting the ITGA5-FAK-ERK pathway.

5-(3',4'-dihydroxyphenyl)-γ-valerolactone, a microbiota metabolite of flavan-3-ols, activates SIRT1-mediated autophagy to attenuate H₂O₂-induced inhibition of osteoblast differentiation in MC3T3-E1 cells

Phenolic compounds are promising agents for the prevention of osteoporosis. 5-(3',4'-dihydroxyphenyl)-γ-valerolactone (DHPV) is the major microbiota metabolite of the flavan-3-ols phenolic compound. Herein, we aimed to investigate the potential mechanisms underlying the effects of DHPV on an osteoblast cell model with H2O2-induced oxidative injury. The MC3T3-E1 cell cultured with H2O2 was used as an oxidative injury model after pretreating with DHPV. Pretreatment with DHPV significantly attenuated cell viability decline, enhanced the activity of alkaline phosphatase and mineralization capacity in MC3T3-E1 cells. Reduced reactive oxygen species (ROS) and malondialdehyde (MDA) levels as well as increased in mitochondrial membrane potential and superoxide dismutase (SOD) activities indicated that DHPV affected both the oxidative and antioxidative processes in the cells. DHPV administration increased the LC3-II/I ratio and Beclin-1 protein levels, thereby promoting autophagy, which perhaps contributes to ROS elimination. However, the inhibition of Sirtuin 1 (SIRT1) by SIRT1 small interfering RNA reduced the protective effect of DHPV or SRT1720, as revealed by the increased ROS and MDA levels and decreased SOD, LC3-II/I ratio and Beclin-1 levels. DHPV may promote autophagy and reduce oxidative stress through the SIRT1-mediated pathway, thereby protecting MC3T3-E1 cells from H2O2-induced oxidative damage.

Protective effect and possible mechanisms of resveratrol in animal models of osteoporosis: A preclinical systematic review and meta-analysis

Resveratrol (RES) has extensively been utilized to treat osteoporosis (OP) in animal models. However, the anti-OP effects of RES have not been tested during clinical application due to the lack of evidence and poor knowledge of the underlying mechanisms. Moreover, there is little preclinical evidence to support the use of RES in the management of OP. In the present paper, we conducted a preclinical systematic review and meta-analysis to assess the efficacy of RES in animal OP models. The potential mechanisms underlying the efficacy of RES against OP were summarized. The online databases PubMed, CNKI, EMBASE, Wanfang, Web of Science, Chinese Biomedical Literature, Cochrane Library, and Chinese VIP were retrieved from inception to December 2021. The CAMARADES 10-item quality checklist was utilized to assess the risk of bias of the included studies. STATA 12.0 software was employed to analyze the data. The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Thirteen studies containing 248 animals were included yielding a mean risk of bias score of 5.54 (range 4-7). The pooled estimates showed that the administration of RES could significantly elevate the bone mineral density (BMD) both at femur (SMD = 2.536; 95% CI = 1.950-3.122; p < 0.001) and lumbar spine (SMD = 1.363; 95% CI = 0894-1.832; p < 0.001), bone volume over total volume (BV/TV) (SMD = 2.543; 95% CI = 2.023-3.062; p < 0.001), trabecular linear density (Tb.N) (SMD = 2.724; 95% CI = 2.186-3.262; p < 0.001) and trabecular thickness (Tb.Th) (SMD = 1.745; 95% CI = 1.294-2.196; p < 0.001), while serum phosphorus (S-P) (SMD = -2.168; 95% CI = -2.753 to -1.583; p < 0.001) and trabecular separation (Tb.Sp) (SMD = -2.856; 95% CI = -4.218 to -1.494; p < 0.001) were significantly reduced in animal OP models. No significant change in serum calcium (S-Ca) (SMD = -2.448; 95% CI = -5.255-0.360; p = 0.087) was observed after RES treatment. Furthermore, RES could significantly improve the bone biomechanical indexes: bone maximum load (BML) (SMD = 2.563; 95% CI = 1.827-3.299; p < 0.001) and connectivity density (Conn.D) (SMD = 1.512; 95% CI = 0.909-2.116; p < 0.001) and decrease the structural model index (SMI) (SMD = -2.522; 95% CI = -3.243 to -1.801; p < 0.001). Overall, the present study revealed that RES has huge prospects as a medicine or dietary supplement for the clinical treatment of OP. High-quality studies with stringent designs and larger sample sizes are warranted to substantiate our conclusion.

Molecular and Cellular Mechanisms of Osteoporosis

Osteoporosis is a widespread systemic disease characterized by a decrease in bone mass and an imbalance of the microarchitecture of bone tissue. Experimental and clinical studies devoted to investigating the main pathogenetic mechanisms of osteoporosis revealed the important role of estrogen deficiency, inflammation, oxidative stress, cellular senescence, and epigenetic factors in the development of bone resorption due to osteoclastogenesis, and decreased mineralization of bone tissue and bone formation due to reduced function of osteoblasts caused by apoptosis and age-depended differentiation of osteoblast precursors into adipocytes. The current review was conducted to describe the basic mechanisms of the development of osteoporosis at molecular and cellular levels and to elucidate the most promising therapeutic strategies of pathogenetic therapy of osteoporosis based on articles cited in PubMed up to September 2023.

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.

Targeting proteostasis network in osteoporosis: Pathological mechanisms and therapeutic implications

As the most common bone disease, osteoporosis (OP) increases bone fragility and makes patients more vulnerable to the threat of osteoporotic fractures. With the ageing population in today's society, OP has become a huge and growing public health problem. Unfortunately, the clear pathogenesis of OP is still under exploration, and effective interventions are still scarce. Therefore, exploring new targets for pharmacological interventions to develop promising therapeutic drugs for OP is of great clinical value. Previous studies have shown that normal bone remodeling depends on proteostasis, whereas loss of proteostasis during ageing leads to the dysfunctional proteostasis network (PN) that fails to maintain bone homeostasis. Nevertheless, only a few studies have revealed the pathophysiological relationship between bone metabolism and a single component of PN, yet the role of PN as a whole in the pathogenesis of OP is still under investigation. This review comprehensively summarized the role of PN in the pathogenesis of OP and further discussed the potential of PN as innovative drug targets for the therapy of OP.

Mechanisms of action and synergetic formulas of plant-based natural compounds from traditional Chinese medicine for managing osteoporosis: a literature review

Osteoporosis (OP) is a systemic skeletal disease prevalent in older adults, characterized by substantial bone loss and deterioration of microstructure, resulting in heightened bone fragility and risk of fracture. Traditional Chinese Medicine (TCM) herbs have been widely employed in OP treatment owing to their advantages, such as good tolerance, low toxicity, high efficiency, and minimal adverse reactions. Increasing evidence also reveals that many plant-based compounds (or secondary metabolites) from these TCM formulas, such as resveratrol, naringin, and ginsenoside, have demonstrated beneficial effects in reducing the risk of OP. Nonetheless, the comprehensive roles of these natural products in OP have not been thoroughly clarified, impeding the development of synergistic formulas for optimal OP treatment. In this review, we sum up the pathological mechanisms of OP based on evidence from basic and clinical research; emphasis is placed on the in vitro and preclinical in vivo evidence-based anti-OP mechanisms of TCM formulas and their chemically active plant constituents, especially their effects on imbalanced bone homeostasis regulated by osteoblasts (responsible for bone formation), osteoclasts (responsible for bone resorption), bone marrow mesenchymal stem cells as well as bone microstructure, angiogenesis, and immune system. Furthermore, we prospectively discuss the combinatory ingredients from natural products from these TCM formulas. Our goal is to improve comprehension of the pharmacological mechanisms of TCM formulas and their chemically active constituents, which could inform the development of new strategies for managing OP.

FoxO1 Agonists Promote Bone Regeneration in Periodontitis by Protecting the Osteogenesis of Periodontal Ligament Stem Cells

Protecting the function of periodontal ligament stem cells (PDLSCs) is crucial for bone regeneration in periodontitis. Forkhead box protein O1 (FoxO1) has been previously reported as a crucial mediator in bone homeostasis, providing a favorable environment for osteoblast proliferation and differentiation. In this study, we investigated the effect and mechanism of FoxO1 agonists on the osteogenesis of PDLSCs under inflammatory conditions. In this study, we screened FoxO1 agonists by detecting their effects on the osteogenic differentiation of PDLSCs. Then, the function of these agonists in bone regeneration was analyzed in the periodontitis model. We found that hyperoside or 2-furoyl-LIGRLO-amide trifluoroacetate salt (2-Fly) promoted osteogenic differentiation under inflammation by simultaneously inhibiting nuclear factor κB (NF-κB) activation, β-catenin expression, and reactive oxygen species (ROS) production. Moreover, local injection of hyperoside or 2-Fly rescued the expression of FoxO1 and runt-related transcription factor 2 (Runx2) in vivo, alleviating alveolar bone loss and periodontal ligament damage. These findings suggested that FoxO1 agonists exerted a protective effect on osteogenesis in PDLSCs, as a result, facilitating bone formation under inflammatory conditions. Taken together, FoxO1 might serve as a therapeutic target for bone regeneration in periodontitis by mediating multiple signaling pathways.

Effects of resveratrol in an animal model of osteoporosis: a meta-analysis of preclinical evidence

Background

Resveratrol is a natural polyphenol compound that is widely present in herbal medicines such as Reynoutria japonica Houtt., Veratrum nigrum L., and Catsiatora Linn and is used in traditional Chinese medicine to treat metabolic bone deseases. Animal experiments have shown that resveratrol may have a strong treatment effect against osteoporosis (OP). The purpose of this study was to explore the efficacy of resveratrol in treating OP animal models based on preclinical research data.

Methods

This study was completed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI) databases from inception to May 8, 2023, to identify animal experiments on the treatment of OP with resveratrol. The effect sizes of bone mineral density (BMD), parameters of micro-CT, serum calcium, phosphorus, alkaline phosphatase (ALP) and osteocalcin were expressed as the mean differences (MDs) and 95% confidence intervals (CIs). RevMan 5.4 software was used for data analysis.

Results

This meta-analysis included a total of 15 animal experiments, including 438 OP rats. The meta-analysis results showed that compared with the control group, resveratrol (<10, 10-25, 40-50, ≥ 60 mg/kg/day) significantly increased femoral and lumbar bone mineral density (BMD) in OP rats (p < 0.05). Resveratrol (<10 mg/kg/day) significantly increased the BMD of the total body (MD = 0.01, 95% CI: 0.01 to 0.01, p < 0.001). In terms of improving the parameters related to micro-CT, resveratrol (40-50 mg/kg/day) can increase trabecular thickness and trabecular number and reduce trabecular spacing (p < 0.05). Compared with the control group, resveratrol can reduce the concentration of calcium and phosphorus in serum but has no significant effect on serum ALP and osteocalcin (p > 0.05). The results of subgroup analysis showed that resveratrol increased the whole-body BMD of SD rats (p = 0.002) but did not improve the whole-body BMD of 3-month-old rats (p = 0.17).

Conclusion

Resveratrol can increase BMD in OP rat models, and its mechanism of action may be related to improving bone microstructure and regulating calcium and phosphorus metabolism. The clinical efficacy of resveratrol in the treatment of OP deserves further research.

Circular RNA FEACR inhibits ferroptosis and alleviates myocardial ischemia/reperfusion injury by interacting with NAMPT

BACKGROUND

Emerging research has reported that circular RNAs (circRNAs) play important roles in cardiac cell death after myocardial ischemia and reperfusion (I/R). Ferroptosis, a new form of cell death discovered in recent years, has been proven to participate in the regulation of myocardial I/R. This study used circRNA sequencing to explore the key circRNA in the regulation of cardiac ferroptosis after I/R and study the mechanisms of potential circRNA function.

METHODS

We performed circRNA sequencing to explore circRNAs differentially expressed after myocardial I/R. We used quantitative polymerase chain reactions to determine the circRNA expression in different tissues and detect the circRNA subcellular localization in the cardiomyocyte. Gain- and loss-of-function experiments were aimed to examine the function of circRNAs in cardiomyocyte ferroptosis and cardiac tissue damage after myocardial I/R. RNA pull-down was applied to explore proteins interacting with circRNA.

RESULTS

Here, we identified a ferroptosis-associated circRNA (FEACR) that has an underlying regulatory role in cardiomyocyte ferroptosis. FEACR overexpression suppressed I/R-induced myocardial infarction and ameliorated cardiac function. FEACR inhibition induces ferroptosis in cardiomyocytes and FEACR overexpression inhibits hypoxia and reoxygenation-induced ferroptosis. Mechanistically, FEACR directly bound to nicotinamide phosphoribosyltransferase (NAMPT) and enhanced the protein stability of NAMPT, which increased NAMPT-dependent Sirtuin1 (Sirt1) expression, which promoted the transcriptional activity of forkhead box protein O1 (FOXO1) by reducing FOXO1 acetylation levels. FOXO1 further upregulated the transcription of ferritin heavy chain 1 (Fth1), a ferroptosis suppressor, which resulted in the inhibition of cardiomyocyte ferroptosis.

CONCLUSIONS

Our finding reveals that the circRNA FEACR-mediated NAMPT-Sirt1-FOXO1-FTH1 signaling axis participates in the regulation of cardiomyocyte ferroptosis and protects the heart function against I/R injury. Thus, FEACR and its downstream factors could be novel targets for alleviating ferroptosis-related myocardial injury in ischemic heart diseases.

LITAF inhibits colorectal cancer stemness and metastatic behavior by regulating FOXO1-mediated SIRT1 expression

Lipopolysaccharide-induced tumor necrosis factor alpha factor (LITAF) is a transcription factor that activates the transcription of TNF-α and regulates the inflammatory response. LITAF has been found to have potential anti-cancer effects of in several tumors. However, the role of LITAF in colorectal cancer (CRC) remains unclear. Through a comprehensive pan-cancer analysis of the Cancer Genome Atlas (TCGA), LITAF was identified as a differentially downregulated gene in CRC. We hypothesized that LITAF may participate in the modulation of CRC progression. The present study was aimed to investigate the expression profile of LITAF in CRC and its effect on metastatic behavior and stemness as well as the underlying molecular mechanism. The expression profile of LITAF in CRC, and its relationship with the prognosis of CRC were explored using public databases. LITAF expression was detected by quantitative real-time PCR (qRT-PCR), western blot, and immunohistochemistry. Furthermore, the effects of overexpression or knockdown of LITAF on cell proliferation, apoptosis, migration, invasion, and stemness of CRC cells were investigated in vitro. The regulatory effect of LITAF on forkhead Box O 1 (FOXO1)-sirtuin 1 (SIRT1) signaling axis was also explored. In addition, a xenograft mouse model was used to investigate the in-vivo role of LITAF. LITAF was downregulated in tumor tissues and its expression was associated with the prognosis, pathological stage and liver metastasis. In-vitro experiments confirmed that LITAF inhibited tumor cell proliferation, migration, invasion and stemness, and induced cell apoptosis. In vivo experiments demonstrated that LITAF inhibited the tumorigenicity and liver metastasis in tumor-bearing mice. Additionally, LITAF promoted FOXO1-mediated SIRT1 inhibition, thus regulating cancer stemness and malignant phenotypes. LITAF was silenced in CRC and it participated in the progression of CRC by inhibiting CRC cell stemness, and malignant phenotypes. Therefore, LITAF may serve as a novel biomarker of CRC prognosis.

Revisiting Resveratrol as an Osteoprotective Agent: Molecular Evidence from In Vivo and In Vitro Studies

Resveratrol (RSV) (3,5,4'-trihydroxystilbene) is a stilbene found in abundance in berry fruits, peanuts, and some medicinal plants. It has a diverse range of pharmacological activities, underlining the significance of illness prevention and health promotion. The purpose of this review was to delve deeper into RSV's bone-protective properties as well as its molecular mechanisms. Several in vivo studies have found the bone-protective effects of RSV in postmenopausal, senile, and disuse osteoporosis rat models. RSV has been shown to inhibit NF-κB and RANKL-mediated osteoclastogenesis, oxidative stress, and inflammation while increasing osteogenesis and boosting differentiation of mesenchymal stem cells to osteoblasts. Wnt/β-catenin, MAPKs/JNK/ERK, PI3K/AKT, FoxOs, microRNAs, and BMP2 are among the possible kinases and proteins involved in the underlying mechanisms. RSV has also been shown to be the most potent SIRT1 activator to cause stimulatory effects on osteoblasts and inhibitory effects on osteoclasts. RSV may, thus, represent a novel therapeutic strategy for increasing bone growth and reducing bone loss in the elderly and postmenopausal population.

Resveratrol induces proliferation and differentiation of mouse pre-osteoblast MC3T3-E1 by promoting autophagy

BACKGROUND

In mouse, it was discovered that resveratrol (Res) enhanced osteoporosis (OP) by boosting osteogenesis. Besides, Res can also have an impact on MC3T3-E1 cells, which are crucial for the control of osteogenesis and thus increase osteogenesis. Although some articles have discovered that Res enhanced autophagy to promote the value-added differentiation of MC3T3, it is unclear exactly how this affects the process of osteogenesis in mouse. Therefore, we will show that Res encourages MC3T3-E1 proliferation and differentiation in mouse pre-osteoblasts and further investigate the autophagy-related mechanism for this impact.

METHODS

(1) MC3T3-E1 cells were separated into blank control group and various concentrations (0.01, 0.1, 1, 10, 100µmol/L) of group in order to determine the ideal Res concentration. In the Res group, Cell Counting Kit-8 (CCK-8) was used to measure the proliferation activity of pre-osteoblasts in mice in each group after resveratrol intervention. Alkaline Phosphatase (ALP) and alizarin red staining were used to gauge the degree of osteogenic differentiation, and RT-qPCR was used to measure the expression levels of Runx2 and OCN in the osteogenic differentiation ability of the cells. (2) In the experiment, four groups were set up: the control group, 3MA group, Res group, and Res + 3MA group. To examine cell mineralization, ALP and alizarin red staining were utilized. RT-qPCR and Western blot detection of cell autophagy activity levels and osteogenic differentiation capacity in each group following intervention.

RESULTS

(1) Resveratrol might increase the number of mice pre-osteoblast, with the impact being most pronounced at 10µmol/L (P < 0.05). The nodules developed substantially more often than in the blank control group, and Runx2 and OCN expressions significantly increased (P < 0.05). (2) In contrast to the Res group, after 3MA purine blocked autophagy, the Res + 3MA group's alkaline phosphatase staining and the development of mineralized nodules were reduced. Runx2, OCN, LC3II / LC3I expression decreased, p62 expression increased (P < 0.05).

CONCLUSION

The present study partially or indirectly demonstrated that Res may, through increased autophagy, induce osteogenic differentiation of MC3T3-E1 cells.

Resveratrol prevents ovariectomy-induced bone quality deterioration by improving the microarchitectural and biophysicochemical properties of bone

INTRODUCTION

Osteoporosis is a major health problem that is very common worldwide and is characterized by both low bone density and deterioration in bone quality. New treatment options without side effects have become an active area of research in recent years. This study was designed to investigate the preventive effects of resveratrol on bone quality deterioration caused by ovariectomy.

MATERIALS AND METHODS

Sixty rats were randomly divided into five groups (12 animals per group): Control, Sham-operated (SHAM), ovariectomized (OVX), OVX + Resveratrol-40 mg/kg/day (OVX + Res40), OVX + Resveratrol-80 mg/kg/day (OVX + Res80). Resveratrol was administered by oral gavage (40 and 80 mg/kg/day) for ten weeks. Micro-CT measurements, biomechanical testing, Raman spectroscopy analysis, and RT-PCR analysis were performed. ALP, OCN, TAS, and TOS levels were also measured from blood serum.

RESULTS

Bone strength, bone volume/total volume, trabecular volume, and trabecular thickness were higher in the OVX + RES-80 group than in the OVX group. Resveratrol increased osteogenic differentiation, as the expression of osteogenic markers ALP, Col1A1, Runx2, OPG, OCN increased in both OVX + RES-80 and OVX + RES-40 groups compared to the OVX group. 80 mg/kg/day resveratrol administration decreased the levels of ALP, OCN and TOS in ovariectomized rats. Raman spectroscopy findings showed a preventive effect of resveratrol administration against ovariectomy-induced deterioration in biophysiochemical properties of bone tissue.

CONCLUSION

This study revealed that administration of different doses of 80 mg/kg/day and 40 mg/kg/day of resveratrol had protective effects on bone quality deterioration caused by ovariectomy.

Epigenetic regulation in metabolic diseases: mechanisms and advances in clinical study

Epigenetics regulates gene expression and has been confirmed to play a critical role in a variety of metabolic diseases, such as diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), osteoporosis, gout, hyperthyroidism, hypothyroidism and others. The term 'epigenetics' was firstly proposed in 1942 and with the development of technologies, the exploration of epigenetics has made great progresses. There are four main epigenetic mechanisms, including DNA methylation, histone modification, chromatin remodelling, and noncoding RNA (ncRNA), which exert different effects on metabolic diseases. Genetic and non-genetic factors, including ageing, diet, and exercise, interact with epigenetics and jointly affect the formation of a phenotype. Understanding epigenetics could be applied to diagnosing and treating metabolic diseases in the clinic, including epigenetic biomarkers, epigenetic drugs, and epigenetic editing. In this review, we introduce the brief history of epigenetics as well as the milestone events since the proposal of the term 'epigenetics'. Moreover, we summarise the research methods of epigenetics and introduce four main general mechanisms of epigenetic modulation. Furthermore, we summarise epigenetic mechanisms in metabolic diseases and introduce the interaction between epigenetics and genetic or non-genetic factors. Finally, we introduce the clinical trials and applications of epigenetics in metabolic diseases.

METTL14 alleviates the development of osteoporosis in ovariectomized mice by upregulating m6A level of SIRT1 mRNA

The purpose of this study was to investigate whether METTL14 participated in ovariectomized (OVX)-induced osteoporosis (OP) in mice by regulating the m⁶A level of SIRT1 mRNA. OVX was performed on mice to induce OP, and mouse bone marrow stromal cells (BMSCs) and bone marrow mononuclear macrophages (BMMs) were isolated to induce osteoblast differentiation and osteoclast differentiation, respectively. The morphology of bone trabeculae was evaluated under a micro-CT scanner. The changes in pathology of bone tissues were observed through staining using hematoxylin-eosin. The number of osteoclasts was measured by tartrate-resistant acid phosphatase staining, and the content of serum calcium, PINP, and CTX-I was tested by enzyme-linked immunosorbent assay, accompanied by the measurement of the expression of SIRT1, METTL14, osteogenic marker genes, and osteoclast marker genes. The m⁶A modification level of SIRT1 and the binding between METTL14 and SIRT1 were verified. In OVX mice, SIRT1 and METTL14 were downregulated. Overexpression of SIRT1 or METTL14 increased the expression of osteogenic marker genes but decreased the expression of osteoclast marker genes. Additionally, METTL14 overexpression increased m⁶A level of SIRT1 mRNA. Furthermore, overexpression of METTL14 promoted osteoblast differentiation and suppressed osteoclast differentiation, which were reversed by knockdown of SIRT1. METTL14 promoted osteoblast differentiation and repressed osteoclast differentiation by m⁶A-dependent upregulation of SIRT1 mRNA, thereby alleviating OP development.

Oxidative Stress and Natural Antioxidants in Osteoporosis: Novel Preventive and Therapeutic Approaches

This review reports in detail the cellular and molecular mechanisms which regulate the bone remodeling process in relation to oxidative stress (OS), inflammatory factors, and estrogen deficiency. OS is considered an important pathogenic factor of osteoporosis, inducing osteocyte apoptosis and varying levels of specific factors, such as receptor activator κB ligand (RANKL), sclerostin, and, according to recent evidence, fibroblast growth factor 23, with consequent impairment of bone remodeling and high bone resorption. Bone loss increases the risk of fragility fractures, and the most commonly used treatments are antiresorptive drugs, followed by anabolic drugs or those with a double effect. In addition, recent data show that natural antioxidants contained in the diet are efficient in preventing and reducing the negative effects of OS on bone remodeling and osteocytes through the involvement of sirtuin type 1 enzyme. Indeed, osteocytes and some of their molecular factors are considered potential biological targets on which antioxidants can act to prevent and reduce bone loss, as well as to promote bone anabolic and regenerative processes by restoring physiological bone remodeling. Several data suggest including antioxidants in novel therapeutic approaches to develop better management strategies for the prevention and treatment of osteoporosis and OS-related bone diseases. In particular, anthocyanins, as well as resveratrol, lycopene, oleuropein, some vitamins, and thiol antioxidants, could have protective and therapeutic anti-osteoporotic effects.

Role of Sirtuins in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease leading to joint destruction. The causes of RA are not fully known. Most likely, the development of the disease depends on the coexistence of many factors, such as hereditary factors, immune system defects, gender, infectious agents, nicotine, and stress. Various epigenetic changes have been identified and correlated with the aggressive phenotype of RA, including the involvement of sirtuins, which are enzymes found in all living organisms. Their high content in the human body can slow down the aging processes, reduce cell death, counteract the appearance of inflammation, and regulate metabolic processes. Sirtuins can participate in several steps of RA pathogenesis. This narrative review presents, collects, and discusses the role of all sirtuins (1-7) in the pathogenesis of rheumatoid arthritis.

A ROS/GAS5/SIRT1 reinforcing feedback promotes oxidative stress-induced adipogenesis in bone marrow-derived mesenchymal stem cells during osteoporosis

BACKGROUND

LincGAS5 have been reported to regulate the progression of osteoporosis (OP). However, the relationship between LincGAS5 and reactive oxygen species (ROS) in osteoporosis were still unclear.

METHODS

Bilateral ovariectomy (OVX) rat were established as OP model and verified by the Micro-computed tomography. The ROS level of BMSCs derived from OVX and control rat were detected by Immunofluorescence (IF) and flow cytometry. The role of GAS5, miR-23b-3p and SIRT1 on the osteogenic differentiation were dectected by ARS saining and ALP staining, while the The Oil Red O staining and flow cytometry (FCM) were hired to determine adipogenic differentiation of BMSCs under different treatment. The expression of GAS5,miR-23b-3p and SIRT1 in BMSCs was detected by RT-qPCR and the correlation among them was analyzed. In addition, Luciferase activity was used to detect whether miR-23b-3p combined with GAS5 and SIRT1 in OP mice BMSCs.

RESULTS

We established the OVX rat model and found higher ROS level in BMSCs isolated from OVX rats. Meanwhile, GAS5 was down-regulated by ROS and remarkably lowly expressed in OVX rat comparing with the negative control. We confirmed GAS5 inhibited adipogenesis and promoted osteoporosis progression. Mechanically, GAS5 bound with miR-23b-3p and suppressed its biological function. We also identified that miR-23b-3p bound with Sirtuin 1 (SIRT1) and decreased its stability. Furthermore, SIRT1 suppressed ROS production in BMSCs, which in turn un-regulated GAS5 expression through ROS-GAS5 axis.

CONCLUSION

We identified a negative feedback loop, ROS-GAS5-SIRT1, in osteoporosis progression. Our findings provided potential targets and biomarkers for osteoporosis prevention and treatment.

A synthetic peptide from Sipunculus nudus promotes bone formation via Estrogen/MAPK signal pathway based on network pharmacology

The tripeptide Leu-Pro-Lys (LPK), derived from the Sipunculus nudus protein, was synthesized and studied to investigate its potential protective effect on bone formation. The effect and mechanism of LPK were analyzed through network pharmacology, bioinformatics, and experimental pharmacology. The study found that LPK at concentrations of 25 μg/mL and 50 μg/mL significantly increased ALP activity and mineralization in C3H10 cells. LPK also increased the expression of COL1A1 and promoted bone formation in zebrafish larvae. Network pharmacology predicted 148 interaction targets between LPK and bone development, and analysis of the protein-protein interaction network identified 13 hub genes, including ESR1, MAPK8, and EGFR, involved in bone development. Through KEGG enrichment pathways analysis, it was determined that LPK promotes bone development by regulating endocrine resistance, the relaxin signaling pathway, and the estrogen signaling pathway. Molecular docking results showed direct interactions between LPK and ESR1, MAPK8, and MAPK14. Additional verification experiments using western blot assay revealed that LPK significantly upregulated the expression of genes related to bone formation, including COL1A1, OPG, RUNX2, ESR1, phosphorylated MAPK14, and phosphorylated MAPK8 in C3H10 cells. These results suggest that LPK promotes bone formation by activating the estrogen/MAPK signaling pathway.

Resveratrol Ameliorates High Altitude Hypoxia-Induced Osteoporosis by Suppressing the ROS/HIF Signaling Pathway

Hypoxia at high-altitude leads to osteoporosis. Resveratrol (RES), as an antioxidant, has been reported to promote osteoblastogenesis and suppress osteoclastogenesis. However, the therapeutic effect of RES against osteoporosis induced by high-altitude hypoxia remains unclear. Thus, this study was intended to investigate the potential effects of RES on high-altitude hypoxia-induced osteoporosis both in vivo and in vitro. Male Wistar rats were given RES (400 mg/kg) once daily for nine weeks under hypoxia, while the control was allowed to grow under normoxia. Bone mineral density (BMD), the levels of bone metabolism-related markers, and the changes on a histological level were measured. Bone marrow-derived mesenchymal stem cells (BMSCs) and RAW264.7 were incubated with RES under hypoxia, with a control growing under normoxia, followed by the evaluation of proliferation and differentiation. The results showed that RES inhibited high-altitude hypoxia-induced reduction in BMD, enhanced alkaline phosphatase (ALP), osteocalcin (OCN), calcitonin (CT) and runt-related transcription factor 2 (RUNX2) levels, whereas it reduced cross-linked carboxy-terminal telopeptide of type I collagen (CTX-I) levels and tartrate-resistant acid phosphatase (TRAP) activity in vivo. In addition, RES attenuated histological deteriorations in the femurs. In vitro, RES promoted osteoblastogenesis and mineralization in hypoxia-exposed BMSCs, along with promotion in RUNX2, ALP, OCN and osteopontin (OPN) levels, and inhibited the proliferation and osteoclastogenesis of RAW264.7. The promotion effects of RES on osteoblastogenesis were accompanied by the down-regulation of reactive oxygen species (ROS) and hypoxia inducible factor-1α (HIF-1α) induced by hypoxia. These results demonstrate that RES can alleviate high-altitude hypoxia-induced osteoporosis via promoting osteoblastogenesis by suppressing the ROS/HIF-1α signaling pathway. Thus, we suggest that RES might be a potential treatment with minimal side effects to protect against high-altitude hypoxia-induced osteoporosis.

Resveratrol Synergistically Promotes BMP9-Induced Osteogenic Differentiation of Mesenchymal Stem Cells

Background. Mesenchymal stem cells (MSCs) differentiate into osteocytes, adipocytes, and chondrocytes. Resveratrol and bone morphogenetic protein 9 (BMP9) are known osteogenic induction factors of MSCs, but the effect of both resveratrol and BMP9 on osteogenesis is unknown. Herein, we explored whether resveratrol cooperates with BMP9 to improve osteogenic induction. Methods. The osteogenic induction of resveratrol and BMP9 on C3H10T1/2 cells was evaluated by detecting the staining and activity of the early osteogenic marker alkaline phosphatase (ALP). In addition, the late osteogenic effect was measured by the mRNA and protein levels of osteogenic markers, such as osteopontin (OPN) and osteocalcin (OCN). To assess the bone formation function of resveratrol plus BMP9 in vivo, we transplanted BMP9-infected C3H10T1/2 cells into nude mice followed by intragastric injection of resveratrol. Western blot (WB) analysis was utilized to elucidate the mechanism of resveratrol plus BMP9. Results. Resveratrol not only enhanced osteogenic induction alone but also improved BMP9-induced ALP at 3, 5, and 7 d postinduction. Both the early osteogenic markers (ALP, Runx2, and SP7) and the late osteogenic markers (OPN and OCN) were significantly increased when resveratrol was combined with BMP9. The fetal limb explant culture further verified these results. The in vivo bone formation experiment, which involved transplanting BMP9-overexpressing C3H10T1/2 cells into nude mice, also confirmed that resveratrol synergistically enhanced the BMP9-induced bone formation function. Resveratrol phosphorylated adenosine monophosphate- (AMP-) activated protein kinase (AMPK) and stimulated autophagy, but these effects were abolished by inhibiting AMPK and Beclin1 using an inhibitor or siRNA. Conclusions. Resveratrol combined with BMP9 significantly improves the osteogenic induction of C3H10T1/2 cells by activating AMPK and autophagy.

Modulation of Inflammation by Plant-Derived Nutraceuticals in Tendinitis

Tendinitis (tendinopathy) is a pro-inflammatory and painful tendon disease commonly linked with mechanical overuse and associated injuries, drug abuse, and lifestyle factors (including poor diet and physical inactivity) that causes significant healthcare expenditures due to its high incidence. Nuclear factor kappa B (NF-κB) is one of the major pro-inflammatory transcription factors, along with other inflammation signaling pathways, triggered by a variety of stimuli, including cytokines, endotoxins, physical and chemical stressors, hypoxia, and other pro-inflammatory factors. Their activation is known to regulate the expression of a multitude of genes involved in inflammation, degradation, and cell death. The pathogenesis of tendinitis is still poorly understood, whereas efficient and sustainable treatment is missing. Targeting drug suppression of the key inflammatory regulators represents an effective strategy for tendinitis therapy, but requires a comprehensive understanding of their principles of action. Conventional monotherapies are often ineffective and associated with severe side effects in patients. Therefore, agents that modulate multiple cellular targets represent therapeutic treatment potential. Plant-derived nutraceuticals have been shown to act as multi-targeting agents against tendinitis via various anti-oxidant and anti-inflammatory mechanisms, whereat they were able to specifically modulate numerous signaling pathways, including NF-κB, p38/MAPK, JNK/STAT3, and PI3K/Akt, thus down-regulating inflammatory processes. This review discusses the utility of herbal nutraceuticals that have demonstrated safety and tolerability as anti-inflammatory agents for the prevention and treatment of tendinitis through the suppression of catabolic signaling pathways. Limitations associated with the use of nutraceuticals are also described.

STK11 overexpression prevents glucocorticoid-induced osteoporosis via activating the AMPK/SIRT1/PGC1α axis

Osteoporosis (OP) is a frequent orthopedic disease characterized by pain, fractures and deformities. Glucocorticoids are the most common cause of secondary osteoporosis. Here, we aim to explore the function and mechanism of STK11 in glucocorticoid (GC)-induced OP. Human mesenchymal stromal cells (hMSCs) were differentiated under osteogenic or adipogenic culture medium. An in-vitro OP model was induced by dexamethasone (DEX). The viability, differentiation, apoptosis, and ROS level were evaluated for investigating the functions of SKT11 on hMSCs. The SIRT1 inhibitor EX-527, PGC1α inhibitor SR-18292, and AMPK activator metformin were administered into hMSCs for confirming the mechanism of SKT11. Our results showed that STK11 was down-regulated in OP tissues, as well as DEX-treated hMSCs. Overexpressing STK11 attenuated DEX-mediated inhibition of osteogenic differentiation and heightened the activation of the AMPK/SIRT1/PGC1α pathway, whereas STK11 knockdown exerted opposite effects. Inhibiting SIRT1 or PGC1α repressed the promotive effect of STK11 on osteogenic differentiation of hMSCs, while activation of AMPK abated the inhibitory effect of STK11 knockdown on osteogenic differentiation of hMSCs. In conclusion, this study revealed that overexpressing STK11 dampened GC-induced OP by activating the AMPK/SIRT1/PGC1α axis.

Three Classes of Antioxidant Defense Systems and the Development of Postmenopausal Osteoporosis

Osteoporosis is a common bone imbalance disease that threatens the health of postmenopausal women. Estrogen deficiency accelerates the aging of women. Oxidative stress damage is regarded as the main pathogenesis of postmenopausal osteoporosis. The accumulation of reactive oxygen species in the bone microenvironment plays a role in osteoblast and osteoclast apoptosis. Improving the oxidative state is essential for the prevention and treatment of postmenopausal osteoporosis. There are three classes of antioxidant defense systems in the body to eliminate free radicals and peroxides including antioxidant substances, antioxidant enzymes, and repair enzymes. In our review, we demonstrated the mechanism of antioxidants and their effect on bone metabolism in detail. We concluded that glutathione/oxidized glutathione (GSH/GSSG) conversion involved the PI3K/Akt-Nrf2/HO-1 signaling pathway and that the antioxidant enzyme-mediated mitochondrial apoptosis pathway of osteoblasts was necessary for the development of postmenopausal osteoporosis. Since the current therapeutic effects of targeting bone cells are not significant, improving the systemic peroxidation state and then regulating bone homeostasis will be a new method for the treatment of postmenopausal osteoporosis.

Cell-Based Double-Screening Method to Identify a Reliable Candidate for Osteogenesis-Targeting Compounds

Small-molecule compounds strongly affecting osteogenesis can form the basis of effective therapeutic strategies in bone regenerative medicine. A cell-based high-throughput screening system might be a powerful tool for identifying osteoblast-targeting candidates; however, this approach is generally limited with using only one molecule as a cell-based sensor that does not always reflect the activation of the osteogenic phenotype. In the present study, we used the MC3T3-E1 cell line stably transfected with the green fluorescent protein (GFP) reporter gene driven by a fragment of type I collagen promoter (Col-1a1GFP-MC3T3-E1) to evaluate a double-screening system to identify osteogenic inducible compounds using a combination of a cell-based reporter assay and detection of alkaline phosphatase (ALP) activity. Col-1a1GFP-MC3T3-E1 cells were cultured in an osteogenic induction medium after library screening of 1280 pharmacologically active compounds (Lopack¹²⁸⁰). After 7 days, GFP fluorescence was measured using a microplate reader. After 14 days of osteogenic induction, the cells were stained with ALP. Library screening using the Col-1a1/GFP reporter and ALP staining assay detected three candidates with significant osteogenic induction ability. Furthermore, leflunomide, one of the three detected candidates, significantly promoted new bone formation in vivo. Therefore, this double-screening method could identify candidates for osteogenesis-targeting compounds more reliably than conventional methods.

Cordyceps cicadae Ameliorates Renal Hypertensive Injury and Fibrosis Through the Regulation of SIRT1-Mediated Autophagy

Hypertensive renal injury is a complication of hypertension. Cordyceps cicadae (C. cicadae) is a traditional Chinese medicine used to treat chronic kidney diseases especially renal fibrosis. Autophagy is described as a cell self-renewal process that requires lysosomal degradation and is utilized for the maintenance of cellular energy homeostasis. The present study explores the mechanism underlying C. cicadae’s renoprotection on hypertensive nephropathy (HN). First, HN rat models were established on spontaneously hypertensive rats (SHRs). The expression of fibrosis-related protein and autophagy-associated protein was detected in vivo. NRK-52E cells exposed to AngII were chosen to observe the potential health benefits of C. cicadae on renal damage. The level of extracellular matrix accumulation was detected using capillary electrophoresis immunoquantification and immunohistochemistry. After treatment with lysosomal inhibitors (chloroquine) or an autophagy activator (rapamycin), the expression of Beclin-1, LC3II, and SQSTM1/p62 was further investigated. The study also investigated the change in sirtuin1 (SIRT1), fork head box O3a (FOXO3a), and peroxidation (superoxide dismutase (SOD) and malondialdehyde (MDA)) expression when intervened by resveratrol. The changes in SIRT1 and FOXO3a were measured in patients and the SHRs. Here, we observed that C. cicadae significantly decreased damage to renal tubular epithelial cells and TGFβ1, α-smooth muscle actin (α-SMA), collagen I (Col-1), and fibronectin expression. Meanwhile, autophagy defects were observed both in vivo and in vitro. C. cicadae intervention significantly downregulated Beclin-1 and LC3II and decreased SQSTM1/p62, showing an inhibition of autophagic vesicles and the alleviation of autophagy stress. These functions were suppressed by rapamycin, and the results were just as effective as the resveratrol treatment. HN patients and the SHRs exhibited decreased levels of SIRT1 and FOXO3a. We also observed a positive correlation between SIRT1/FOXO3a and antifibrotic effects. Similar to the resveratrol group, the expression of SIRT1/FOXO3a and oxidative stress were elevated by C. cicadae in vivo. Taken together, our findings show that C. cicadae ameliorates tubulointerstitial fibrosis and delays HN progression. Renoprotection was likely attributable to the regulation of autophagic stress mediated by the SIRT1 pathway and achieved by regulating FOXO3a and oxidative stress.

Re-appraising the role of flavonols, flavones and flavonones on osteoblasts and osteoclasts- A review on its molecular mode of action

Bone disorders have become a global concern illustrated with decreased bone mineral density and disruption in microarchitecture of natural bone tissue organization. Natural compounds that promote bone health by augmenting osteoblast functions and suppressing osteoclast functions has gained much attention and offer greater therapeutic value compared to conventional therapies. Amongst several plant-based molecules, flavonoids act as a major combatant in promoting bone health through their multi-faceted biological activities such as antioxidant, anti-inflammatory, and osteogenic properties. They protect bone loss by regulating the signalling cascades involved in osteoblast and osteoclast functions. Flavonoids augment osteoblastogenesis and inhibits osteoclastogenesis through their modulation of various signalling pathways. This review discusses the role of various flavonoids and their molecular mechanisms involved in maintaining bone health by regulating osteoblast and osteoclast functions.