Oxidative stress: A common pathological state in a high-risk population for osteoporosis

Dichotomitin promotes osteoblast differentiation and improves osteoporosis by inhibiting oxidative stress

OBJECTIVE

Osteoporosis is a systemic disease with high morbidity and significant adverse effects. Increasing evidence supports the close relationship between oxidative stress and osteoporosis, suggesting that treatment with antioxidants may be a viable approach. This study evaluated the antioxidant properties of dichotomitin (DH) and its potential protective effects against osteoporosis.

METHODS

SD rats were divided into three groups: Sham, OVX, and OVX + DH (5 mg/kg, intraperitoneal injection twice weekly). After three months, blood samples, femurs, and tibiae were collected for analysis. Micro-CT evaluated the femoral, while histological examination assessed tibial tissues. Serum osteogenic biochemical markers were measured. In vitro, osteogenic differentiation was induced with varying concentrations of DH, followed by ALP and ARS staining. RT-qPCR and western blot were used to assess the expression of osteogenesis-related genes and proteins. Additionally, an oxidative stress cell model was established, dividing cells into control, H2O2-treated, and H2O2 + DH-treated groups. Expression of oxidative stress-related genes and proteins was assessed using real-time quantitative PCR and western blotting.

RESULTS

Micro-CT and histological staining revealed decreased and disrupted bone trabeculae in the OVX group, whereas the DH-treated group exhibited enhanced bone trabecular area and structure compared to the OVX group. In vitro studies showed that DH enhanced ALP activity and elevated expression of RUNX2, OPN, OCN, SOD1, and SOD2.

CONCLUSION

DH has the potential to enhance osteoblast differentiation and alleviate osteoporosis through the attenuation of oxidative stress.

Acetyl-11-keto-β-boswellia acid attenuates Ti particle-induced osteoblastic oxidative stress and osteolysis through the Foxo3 signaling pathway

Oxidative stress injury in osteoblasts is one of the leading causes of periprosthetic osteolysis (PPOL). Acetyl-11-keto-β-boswellia acid (AKBA) has been used as an antioxidant in the treatment of various diseases, but its antioxidant mechanism in osteolysis has yet to be elucidated. In this study, a mouse cranial osteolysis model was constructed, and MC3T3-E1 cells and bone marrow mesenchymal stem cells (BMSCs) were cultured in vitro. Western blotting and immunofluorescence staining revealed that titanium (Ti) particles aggravated osteoblast oxidative stress injury and apoptosis. Ti particles and hydrogen peroxide reduced the osteogenic ability of BMSCs. At a certain concentration, AKBA alleviated the oxidative stress injury of MC3T3-E1 cells induced by Ti particles and enhanced the osteogenic ability of BMSCs, and the expression of Forkhead box O3 (Foxo3) increased with increasing AKBA concentration. To verify the antioxidant mechanism of AKBA, we designed and synthesized Foxo3-targeting siRNAs. We found that after Foxo3 expression was inhibited, the protective effect of AKBA on osteoblasts decreased significantly. Moreover, AKBA treatment suppressed bone mass loss in the skull mediated by Ti particles in mice. Therefore, we suggest that AKBA alleviates the oxidative stress injury in osteoblasts induced by Ti particles, at least in part, by regulating the expression of Foxo3. In this study, the mechanism and biosafety of AKBA in treating PPOL were demonstrated to some extent.

Paederosidic acid protect bone mass in lipopolysaccharide-treated rats by reducing oxidative stress and inflammatory

Paederosidic acid (PA) has shown beneficial effects in anti-inflammatory studies, but it is unclear whether PA has positive impacts on bone loss induced by lipopolysaccharide (LPS). This study aims to investigate the influence of PA on bone loss in LPS-treated rats. The study assesses changes in the viability and osteogenic potential of MC3T3-E1 cells, as well as osteoclast differentiation in RAW264.7 cells in the presence of LPS using CCK-8, ALP staining, AR staining, and Tartrate-resistant acid phosphatase (TRAP) staining. In vitro experiments indicate that LPS-induced inhibition of osteoclasts (OC) and Superoxide Dismutase 2 (SOD2) correlates with heightened levels of inflammation and oxidative stress. Furthermore, PA has demonstrated the ability to alleviate oxidative stress and inflammation, enhance osteogenic differentiation, and suppress osteoclast differentiation. Animal experiments also show that PA significantly upregulates SOD2 expression while downregulating TNF-α expression (all, p < 0.05), leading to the restoration of impaired bone metabolism, improved bone strength, and increased bone mineral density (all, p < 0.05), compared to the control group. The collective experimental findings strongly suggest that PA can enhance osteogenic activity in the presence of LPS by reducing inflammation and oxidative stress, hindering osteoclast differentiation; hence mitigating bone loss in LPS-treated rat models.

Application of extracellular vesicles in diabetic osteoporosis

As the population ages, the occurrence of osteoporosis is becoming more common. Diabetes mellitus is one of the factors in the development of osteoporosis. Compared with the general population, the incidence of osteoporosis is significantly higher in diabetic patients. Diabetic osteoporosis (DOP) is a metabolic bone disease characterized by abnormal bone tissue structure due to hyperglycemia and insulin resistance, reduced bone strength and increased risk of fractures. This is a complex mechanism that occurs at the cellular level due to factors such as blood vessels, inflammation, and hyperglycemia and insulin resistance. Although the application of some drugs in clinical practice can reduce the occurrence of DOP, the incidence of fractures caused by DOP is still very high. Extracellular vesicles (EVs) are a new communication mode between cells, which can transfer miRNAs and proteins from mother cells to target cells through membrane fusion, thereby regulating the function of target cells. In recent years, the role of EVs in the pathogenesis of DOP has been widely demonstrated. In this article, we first describe the changes in the bone microenvironment of osteoporosis. Second, we describe the pathogenesis of DOP. Finally, we summarize the research progress and challenges of EVs in DOP.

Mitochondria in skeletal system-related diseases

Skeletal system-related diseases, such as osteoporosis, arthritis, osteosarcoma and sarcopenia, are becoming major public health concerns. These diseases are characterized by insidious progression, which seriously threatens patients' health and quality of life. Early diagnosis and prevention in high-risk populations can effectively prevent the deterioration of these patients. Mitochondria are essential organelles for maintaining the physiological activity of the skeletal system. Mitochondrial functions include contributing to the energy supply, modulating the Ca2+ concentration, maintaining redox balance and resisting the inflammatory response. They participate in the regulation of cellular behaviors and the responses of osteoblasts, osteoclasts, chondrocytes and myocytes to external stimuli. In this review, we describe the pathogenesis of skeletal system diseases, focusing on mitochondrial function. In addition to osteosarcoma, a characteristic of which is active mitochondrial metabolism, mitochondrial damage occurs during the development of other diseases. Impairment of mitochondria leads to an imbalance in osteogenesis and osteoclastogenesis in osteoporosis, cartilage degeneration and inflammatory infiltration in arthritis, and muscle atrophy and excitationcontraction coupling blockade in sarcopenia. Overactive mitochondrial metabolism promotes the proliferation and migration of osteosarcoma cells. The copy number of mitochondrial DNA and mitochondria-derived peptides can be potential biomarkers for the diagnosis of these disorders. High-risk factor detection combined with mitochondrial component detection contributes to the early detection of these diseases. Targeted mitochondrial intervention is an effective method for treating these patients. We analyzed skeletal system-related diseases from the perspective of mitochondria and provided new insights for their diagnosis, prevention and treatment by demonstrating the relationship between mitochondria and the skeletal system.

Polyphenols and Functionalized Hydrogels for Osteoporotic Bone Regeneration

Osteoporosis induces severe oxidative stress and disrupts bone metabolism, complicating the treatment of bone defects. Current therapies often have side effects and require lengthy bone regeneration periods. Hydrogels, known for their flexible mechanical properties and degradability, are promising carriers for drugs and bioactive factors in bone tissue engineering. However, they lack the ability to regulate the local pathological environment of osteoporosis and expedite bone repair. Polyphenols, with antioxidative, anti-inflammatory, and bone metabolism-regulating properties, have emerged as a solution. Combining hydrogels and polyphenols, polyphenol-based hydrogels can regulate local bone metabolism and oxidative stress while providing mechanical support and tissue adhesion, promoting osteoporotic bone regeneration. This review first provides a brief overview of the types of polyphenols and the mechanisms of polyphenols in facilitating adhesion, antioxidant, anti-inflammatory, and bone metabolism modulation in modulating the pathological environment of osteoporosis. Next, this review examines recent advances in hydrogels for the treatment of osteoporotic bone defects, including their use in angiogenesis, oxidative stress modulation, drug delivery, and stem cell therapy. Finally, it highlights the latest research on polyphenol hydrogels in osteoporotic bone defect regeneration. Overall, this review aims to facilitate the clinical application of polyphenol hydrogels for the treatment of osteoporotic bone defects.

The association between dietary flavonoid intake and bone mineral density and osteoporosis in US adults: data from NHANES 2007-2008, 2009-2010 and 2017-2018

BACKGROUND

Epidemiological studies investigating the association between flavonoid intake and bone mineral density (BMD) draw inconsistent conclusions. Our study aims to investigate the association between flavonoid intake and BMD and osteoporosis and the mediating role of composite dietary antioxidant index (CDAI) in their relationship using data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

The study assessed the relationship between flavonoid intake and femur BMD and osteoporosis in 10,225 individuals from NHANES 2007-2010 and 2017-2018. Multivariable linear regression analyses were used to detect the association between flavonoid intake and femur BMD in adult Americans. Restricted cubic splines (RCS) were used to examine the nonlinear relationship between flavonoid intake and their subclasses and osteoporosis risk in individuals 20 years or older. We explored the mediating role of CDAI in the association between flavonoid intake and BMD.

RESULTS

In fully adjusted multivariable regression analyses, compared with people in the first quartile, people in the fourth quartile of total flavonoid intake have a higher BMD at total femur (0.013, 95% CI: 0.004, 0.022, P = 0.001), femur neck (0.010, 95% CI: 0.004, 0.017, P = 0.001), trochanter (0.010, 95% CI: 0.004, 0.017, P = 0.001), and intertrochanter (0.012, 95% CI: 0.003, 0.020, P = 0.006). The positive relationship between flavonoid intake and femur BMD was present in both sexes. Furthermore, we found that people in the fourth quartile of total flavonoid intake have a lower risk of osteoporosis compared with the first quartile (OR = 0.686, 95% CI: 0.528-0.890, P = 0.005). RCS found a linear inverse relationship between total flavonoid intake and osteoporosis in individuals ≥ 20 years (Overall P = 0.015, nonlinear P = 0.086). Moreover, CDAI partially mediates the association of total flavonoid intake with femur BMD.

CONCLUSIONS

Our findings suggest that higher flavonoid intake is associated with higher BMD and lower risk of osteoporosis in Americans. Furthermore, we found distinct associations between different flavonoid subclasses and osteoporosis risk. More studies with stronger evidence are needed to explore the causal association between flavonoid intake and bone health and their underlying mechanisms.

Primary Osteoporosis Induced by Androgen and Estrogen Deficiency: The Molecular and Cellular Perspective on Pathophysiological Mechanisms and Treatments

Primary osteoporosis is closely linked to hormone deficiency, which disrupts the balance of bone remodeling. It affects postmenopausal women but also significantly impacts older men. Estrogen can promote the production of osteoprotegerin, a decoy receptor for RANKL, thereby preventing RANKL from activating osteoclasts. Furthermore, estrogen promotes osteoblast survival and function via activation of the Wnt signaling pathway. Likewise, androgens play a critical role in bone metabolism, primarily through their conversion to estrogen in men. Estrogen deficiency accelerates bone resorption through a rise in pro-inflammatory cytokines (IL-1, IL-6, TNF-α) and RANKL, which promote osteoclastogenesis. In the classic genomic pathway, estrogen binds to estrogen receptors in the cytoplasm, forming a complex that migrates to the nucleus and binds to estrogen response elements on DNA, regulating gene transcription. Androgens can be defined as high-affinity ligands for the androgen receptor; their combination can serve as a ligand-inducible transcription factor. Hormone replacement therapy has shown promise but comes with associated risks and side effects. In contrast, the non-genomic pathway involves rapid signaling cascades initiated at the cell membrane, influencing cellular functions without directly altering gene expression. Therefore, the ligand-independent actions and rapid signaling pathways of estrogen and androgen receptors can be harnessed to develop new drugs that provide bone protection without the side effects of traditional hormone therapies. To manage primary osteoporosis, other pharmacological treatments (bisphosphonates, teriparatide, RANKL inhibitors, sclerostin inhibitors, SERMs, and calcitonin salmon) can ameliorate osteoporosis and improve BMD via actions on different pathways. Non-pharmacological treatments include nutritional support and exercise, as well as the dietary intake of antioxidants and natural products. The current study reviews the processes of bone remodeling, hormone actions, hormone receptor status, and therapeutic targets of primary osteoporosis. However, many detailed cellular and molecular mechanisms underlying primary osteoporosis seem complicated and unexplored and warrant further investigation.

Chlorogenic Acid-Cucurbit[n]uril Nanocomplex Delivery System: Synthesis and Evaluations for Potential Applications in Osteoporosis Medication

Purpose

Based on nanomedicine strategies, this study employed cucurbit[7]uril (Q[7]) as the macromolecular carrier to synthesize nanocomplex drug delivery system for chlorogenic acid (CGA). The nanocomplex drug delivery system is intended to overcome the unsatisfactory biocompatibility and bioavailability of CGA and realizing its potential role in long-term osteoporosis (OP) medication.

Methods

The nanocomplex was synthesized by the reflux stirring method. The chemical structure of the nanocomplex was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), UV-visible spectrophotometry (UV-vis), zeta potential analysis and transmission electronic microscope (TEM). The Cell Counting Kit-8 (CCK-8) assay, Live/Dead staining assay, and cytoskeleton staining were conducted to testify the biocompatibility of the nanocomplex. The release assay, Ferric Reducing Ability of Plasma (Frap) assay and Reactive oxygen species (ROS) staining were implemented to evaluate the release profile of CGA as well as its remaining antioxidative levels.

Results

CGA and Q[7] formed hydrogen bonding through an exclusion interaction, with the binding ratio more than 1:1. The nanocomplex had a crystalline and spherical-like structure and improved thermal stability. The nanocomplex demonstrated better biocompatibility than free CGA. The release profile of CGA from the nanocomplex was much steadier, and 70% of CGA was released in 5 days. The CGA released from the nanocomplex maintained its antioxidative properties at high levels and effectively eliminated the accumulated ROS in MC3T3-E1 cells under oxidative stress.

Conclusion

Q[7] has been demonstrated to be an ideal nanocarrier for CGA and the nanocomplex delivery system holds the potential for the long-term medication strategy of OP.

Metformin improves HPRT1-targeted purine metabolism and repairs NR4A1-mediated autophagic flux by modulating FoxO1 nucleocytoplasmic shuttling to treat postmenopausal osteoporosis

Osteoporosis is a major degenerative metabolic bone disease that threatens the life and health of postmenopausal women. Owing to limitations in detection methods and prevention strategy awareness, the purpose of osteoporosis treatment is more to delay further deterioration rather than to fundamentally correct bone mass. We aimed to clarify the pathogenesis of postmenopausal osteoporosis and optimize treatment plans. Our experiments were based on previous findings that oxidative stress mediates bone metabolism imbalance after oestrogen deficiency. Through energy metabolism-targeted metabolomics, we revealed that purine metabolism disorder is the main mechanism involved in inducing oxidative damage in bone tissue, which was verified via the use of machine-learning data from human databases. Xanthine and xanthine oxidase were used to treat osteoblasts to construct a purine metabolism disorder model. The activity and differentiation ability of osteoblasts decreased after X/XO treatment. Transcriptomic sequencing indicated that autophagic flux damage was involved in purine metabolism-induced oxidative stress in osteoblasts. Additionally, we performed serum metabolomics combined with network pharmacology to determine the pharmacological mechanism of metformin in the treatment of postmenopausal osteoporosis. HPRT1 was the potential target filtered from the hub genes, and FoxO1 signalling was the key pathway mediating the effect of metformin in osteoblasts. We also revealed that SIRT3-mediated deacetylation promoted the nuclear localization of FoxO1 to increase the expression of HPRT1. HPRT1 upregulation promoted purine anabolism and prevented the accumulation of ROS caused by purine catabolism to reverse oxidative damage in osteoblasts. We propose that purine metabolism disorder-induced oxidative stress is important for the pathogenesis of postmenopausal osteoporosis. The therapeutic mechanism of metformin should be confirmed through subsequent drug optimization and development studies to improve bone health in postmenopausal women.

Assessing the causal relationship between plasma proteins and osteoporosis: novel insights into pathological mechanisms and therapeutic implications

Identifying dysregulated plasma proteins in osteoporosis (OP) progression offers insights into prevention and treatment. This study found 8 such proteins associated with OP, suggesting them as therapy targets. This discovery may cut drug development costs and improve personalized treatments.

PURPOSE

This study aims to identify potential therapeutic targets for OP using summary data-based Mendelian randomization (SMR) and colocalization analysis methods. Furthermore, we seek to explore the biological significance and pharmacological value of these drug targets.

METHODS

To identify potential therapeutic targets for OP, we conducted SMR and colocalization analysis. Plasma protein (pQTL, exposure) data were sourced from the study by Ferkingstad et al. (n = 35,559). Summary statistics for bone mineral density (BMD, outcome) were obtained from the GWAS Catalog (n = 56,284). Additionally, we utilized enrichment analysis, protein-protein interaction (PPI) network analysis, drug prediction, and molecular docking to further analyze the biological significance and pharmacological value of these drug targets.

RESULTS

In the SMR analysis, while 20 proteins showed significance, only 8 potential drug targets (GCKR, ERBB3, CFHR1, GPN1, SDF2, VTN, BET1L, and SERPING1) received support from colocalization (PP.H4 > 0.8). These proteins are closely associated with immune function in terms of biological significance. Molecular docking also demonstrated favorable binding of drugs to proteins, consistent with existing structural data, further substantiating the pharmacological value of these targets.

CONCLUSIONS

The study identified 8 potential drug targets for OP. These prospective targets are believed to have a higher chance of success in clinical trials, thus aiding in prioritizing OP drug development and reducing development costs.

Antioxidant 1,2,3,4,6-Penta-O-galloyl-β-D-glucose Alleviating Apoptosis and Promoting Bone Formation Is Associated with Estrogen Receptors

1,2,3,4,6-penta-O-galloyl-β-D-glucose (PGG) is the main phenolic active ingredient in Paeoniae Radix Alba, which is commonly used for the treatment of osteoporosis (OP). PGG is a potent natural antioxidant, and its effects on OP remain unknown. This study aimed to investigate the effects of PGG on promoting bone formation and explore its estrogen receptor (ER)-related mechanisms. A hydrogen peroxide-induced osteoblast apoptosis model was established in MC3T3-E1 cells. The effects of PGG were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, alkaline phosphatase (ALP) staining, RT-qPCR, and Western blot methods. Furthermore, a prednisolone-induced zebrafish OP model was employed to study the effects in vivo. ER inhibitors and molecular docking methods were used further to investigate the interactions between PGG and ERs. The results showed that PGG significantly enhanced cell viability and decreased cell apoptosis by restoring mitochondrial function, attenuating reactive oxygen species levels, decreasing the mitochondrial membrane potential, and enhancing ATP production. PGG enhanced ALP expression and activity and elevated osteogenic differentiation. PGG also promoted bone formation in the zebrafish model, and these effects were reversed by ICI182780. These results provide evidence that the effects of PGG in alleviating apoptosis and promoting bone formation may depend on ERs. As such, PGG is considered a valuable candidate for treating OP.

Targeting CDC42 reduces skeletal degeneration after hematopoietic stem cell transplantation

ABSTRACT

Osteopenia and osteoporosis are common long-term complications of the cytotoxic conditioning regimen for hematopoietic stem cell transplantation (HSCT). We examined mesenchymal stem and progenitor cells (MSPCs), which include skeletal progenitors, from mice undergoing HSCT. Such MSPCs showed reduced fibroblastic colony-forming units frequency, increased DNA damage, and enhanced occurrence of cellular senescence, whereas there was a reduced bone volume in animals that underwent HSCT. This reduced MSPC function correlated with elevated activation of the small Rho guanosine triphosphate hydrolase CDC42, disorganized F-actin distribution, mitochondrial abnormalities, and impaired mitophagy in MSPCs. Changes and defects similar to those in mice were also observed in MSPCs from humans undergoing HSCT. A pharmacological treatment that attenuated the elevated activation of CDC42 restored F-actin fiber alignment, mitochondrial function, and mitophagy in MSPCs in vitro. Finally, targeting CDC42 activity in vivo in animals undergoing transplants improved MSPC quality to increase both bone volume and trabecular bone thickness. Our study shows that attenuation of CDC42 activity is sufficient to attenuate reduced function of MSPCs in a BM transplant setting.

From Genomics to Metabolomics: Molecular Insights into Osteoporosis for Enhanced Diagnostic and Therapeutic Approaches

Osteoporosis (OP) is a prevalent skeletal disorder characterized by decreased bone mineral density (BMD) and increased fracture risk. The advancements in omics technologies-genomics, transcriptomics, proteomics, and metabolomics-have provided significant insights into the molecular mechanisms driving OP. These technologies offer critical perspectives on genetic predispositions, gene expression regulation, protein signatures, and metabolic alterations, enabling the identification of novel biomarkers for diagnosis and therapeutic targets. This review underscores the potential of these multi-omics approaches to bridge the gap between basic research and clinical applications, paving the way for precision medicine in OP management. By integrating these technologies, researchers can contribute to improved diagnostics, preventative strategies, and treatments for patients suffering from OP and related conditions.

Cinobufagin Suppresses Lipid Peroxidation and Inflammation in Osteoporotic Mice by Promoting the Delivery of miR-3102-5p by Macrophage-Derived Exosomes

Background

Cinobufagin, the primary active compound in toad venom, is commonly used for anti-tumor, anti-inflammatory, and analgesic purposes. However, its specific bone-protective effects remain uncertain. This research aims to ascertain the bone-protective properties of cinobufagin and investigate underlying mechanisms.

Methods

Mice were ovariectomized to establish an osteoporosis model, followed by intraperitoneal injections of cinobufagin and cinobufagin-treated RAW.264.7-derived exosomes for therapy. MicroCT, HE staining, and TRAP staining were employed to evaluate bone mass and therapeutic outcomes, while mRNA sequencing and immunoblotting were utilized to assess markers of bone metabolism, inflammation, and lipid peroxidation. Osteoblast and osteoclast precursor cells were differentiated to observe the impact of cinobufagin-treated exosomes derived from RAW264.7 cells on bone metabolism. Exosomes characteristics were studied using transmission electron microscopy and particle size analysis, and miRNA binding targets in exosomes were determined by luciferase reporting.

Results

In ovariectomized mice, cinobufagin and cinobufagin-treated exosomes from RAW264.7 cells increased trabecular bone density and mass in the femur, while also decreasing inflammation and lipid peroxidation. The effect was reversed by an exosomes inhibitor. In vitro experiments revealed that cinobufagin-treated exosomes from RAW264.7 cells enhanced osteogenic and suppressed osteoclast differentiation, possibly linked to Upregulated miR-3102-5p in RAW-derived exosomes. MiR-3102-5p targets the 3'UTR region of alox15, thereby suppressing its expression and reducing the lipid peroxidation process in osteoblasts.

Conclusion

Overall, this study clarified cinobufagin's bone-protective effects and revealed that cinobufagin can enhance the delivery of miR-3102-5p targeting alox15 through macrophage-derived exosomes, demonstrating anti-lipid peroxidation and anti-inflammatory effects.

Low T3 Syndrome is Associated with Imbalance of Bone Turnover Biomarker in Patients with Type 2 Diabetes

Objectives

To investigate the variation in bone turnover biomarkers among patients with type 2 diabetes (T2D) and low triiodothyronine levels (Low T3 syndrome).

Materials and Methods

This retrospective analytic study included 418 inpatient records from Shanghai Pudong Hospital covering the years 2021 to 2023. Laboratory data related to metabolic and bone turnover biomarkers in patients were analyzed with T2D and the low T3 syndrome.

Results

The results indicated that patients with reduced serum T3 levels exhibited statistically significant variations in thyroid function, age, fasting plasma glucose (FPG), glycated hemoglobin A1c (HbA1c), and the proportion of medication history associated with diabetes in comparison to euthyroid patients. In addition to parathyroid hormones, bone turnover biomarkers including N-terminal middle molecular fragment of osteocalcin (NMID), plasma calcium (Ca2+), β C-terminal cross-linking telopeptide of type 1 collagen (β-CTX), and 25-hydroxyvitamin D3 (25 OH VitD3) exhibited significant changes in patients with decreased T3 levels. Evident irregularities were observed in patients with a decreased T3 level, including elevated serum creatinine (SCr), decreased concentrations of albumin and total protein, and a decreased estimated glomerular filtration rate (eGFR), as assessed through hepatic and renal testing, respectively. Significant associations between bone turnover biomarkers and the subsequent variables (gender, adiposity, hepatic, renal, and thyroid function) were revealed through the correlational analysis. Further investigation utilized multivariate linear regression to determine that, in addition to thyroid function, several other factors such as age, gender, bodyweight, pancreatic, hepatic, and renal function, affected the variability in bone turnover biomarkers among patients demonstrating a low serum T3 level.

Conclusions

This comparative study demonstrated that despite age, gender, bodyweight, hepatic, renal function, thyroid hormone and pancreatic function were significant factors associated with bone metabolism in patients with T2D and Low T3 syndrome, which may increase the risk of osteoporosis.

Matrix stiffness regulates mitochondria-lysosome contacts to modulate the mitochondrial network, alleviate the senescence of MSCs

The extracellular microenvironment encompasses the extracellular matrix, neighbouring cells, cytokines, and fluid components. Anomalies in the microenvironment can trigger aging and a decreased differentiation capacity in mesenchymal stem cells (MSCs). MSCs can perceive variations in the firmness of the extracellular matrix and respond by regulating mitochondrial function. Diminished mitochondrial function is intricately linked to cellular aging, and studies have shown that mitochondria-lysosome contacts (M-L contacts) can regulate mitochondrial function to sustain cellular equilibrium. Nonetheless, the influence of M-L contacts on MSC aging under varying matrix stiffness remains unclear. In this study, utilizing single-cell RNA sequencing and atomic force microscopy, we further demonstrate that reduced matrix stiffness in older individuals leads to MSC aging and subsequent decline in osteogenic ability. Mechanistically, augmented M-L contacts under low matrix stiffness exacerbate MSC aging by escalating mitochondrial oxidative stress and peripheral division. Moreover, under soft matrix stiffness, cytoskeleton reorganization facilitates rapid movement of lysosomes. The M-L contacts inhibitor ML282 ameliorates MSC aging by reinstating mitochondrial network and function. Overall, our findings confirm that MSC aging is instigated by disruption of the mitochondrial network and function induced by matrix stiffness, while also elucidating the potential mechanism by which M-L Contact regulates mitochondrial homeostasis. Crucially, this presents promise for cellular anti-aging strategies centred on mitochondria, particularly in the realm of stem cell therapy.

Oxysophocarpine attenuates inflammatory osteolysis by modulating the NF-κb pathway and the reactive oxygen species-related Nrf2 signaling pathway

BACKGROUND AND AIM

Inflammatory diseases often result in bone loss due to persistent inflammation, which activates osteoclasts and increases bone resorption. Oxysophocarpine (OSC), a bioalkaloid extracted from the roots of Sophora japonica and other leguminous plants, has neuroprotective and anti-tumor properties. However, it is still uncertain whether OSC can effectively inhibit the differentiation of osteoclasts and bone resorption. Therefore, this study explored the potential role of OSC in osteoclast formation and inflammatory osteolysis and its underlying mechanisms.

EXPERIMENTAL PROCEDURE

This study involved inducing primary mouse bone marrow macrophages (BMMs) into osteoclasts using macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL) and examined the effects of OSC on osteoclast (OC) differentiation, function, and intracellular reactive oxygen species (ROS) production. The impact of OSC on the expression of osteoclast-specific genes and inflammation-related factors was assessed using real-time quantitative PCR. Additionally, changes in oxidative stress-related factors, NF-κB, and MAPK signaling pathways were examined using western blotting. Finally, this study investigated the influence of OSC on a mouse cranial bone resorption model induced by titanium (Ti) particles in vivo.

RESULTS

OSC inhibited OC differentiation and resorption and reduces intracellular ROS levels. Moreover, OSC suppressed IL-1β, TNF-α, IL-6, and osteoclast-specific gene transcription while increasing Nrf2 and HO-1 protein expression. Furthermore, OSC inhibited the expression and autoregulation of the NFATc1 gene, ultimately leading to a reduction in Ti particle-induced bone resorption in mice.

CONCLUSION

OSC could be regarded as an innovative medication for the treatment of osteoclast-associated inflammatory osteolytic diseases.

7,8-DHF inhibits BMSC oxidative stress via the TRKB/PI3K/AKT/NRF2 pathway to improve symptoms of postmenopausal osteoporosis

Postmenopausal osteoporosis (PMO) is characterized by bone loss and microstructural damage, and it is most common in older adult women. Currently, there is no cure for PMO. The flavonoid chemical 7,8-dihydroxyflavone (7,8-DHF) specifically activates tropomyosin receptor kinase B (TRKB). Furthermore, 7,8-DHF has various biological characteristics, including anti-inflammatory and antioxidant effects. However, the specific implications and fundamental mechanisms of 7,8-DHF in PMO remain unclear. We used protein imprinting, flow cytometry, tissue staining, and other methods to estimate the preventive mechanisms of 7,8-DHF against hydrogen peroxide (H2O2)-induced apoptosis in primary mouse bone marrow mesenchymal stem cells (BMSCs), osteogenic differentiation ability, and bone mass in ovariectomized (OVX) mice. We found that 7,8-DHF effectively prevented H2O2-induced reductions in the viability and osteogenic differentiation capacity of primary BMSCs. Mechanistically, 7,8-DHF induced the TRKB to activate the PI3K/AKT/NRF2 pathway. In vivo experiments with the OVX mouse model confirmed that 7,8-DHF can inhibit oxidative stress and promote bone formation, indicating that 7,8-DHF improves the viability and osteogenic differentiation ability of BMSCs stimulated via H2O2 by activating the TRKB/PI3K/AKT and NRF2 pathways, thereby improving PMO.

Exploring the role of circ-0091579/miR-1225-5p and circ-HIPK3/miR-338-3p axes in the pathogenesis of postmenopausal osteoporosis

CircRNAs have been increasingly appreciated as modulators of osteoporosis. This study investigated the expression of circ-0091579 and circ-HIPK3 in PBMCs of postmenopausal women with osteopenia and osteoporosis, aiming to underline their molecular mechanisms involved in pathogenesis of the disease. Seventy patients were stratified into two groups: 35 with osteopenia and 35 with osteoporosis, along with 30 healthy controls. Expressions of circ-0091579 and circ-HIPK3, miR-1225-5p and miR-338-3p, together with NF-κB, were assessed using RT-PCR. Keap1, Nrf2, and MAFB were determined using Western blot, while RANKL, OPG, IL-1β, and IL-6 were measured by ELISA. GSH and MDA were estimated colorimetrically. Data revealed that circ-0091579 was markedly upregulated, whereas miR-1225-5p was downregulated in patients relative to controls. Additionally, circ-HIPK3 was significantly decreased, while miR-338-3p was increased in the diseased groups. Circ-0091579 was directly correlated with RANKL/OPG, NF-κB, IL-1β, IL-6 and MDA, while inversely correlated with miR-1225-5p, T-score, BMD and GSH. Meanwhile, circ-HIPK3 and miR-338-3p were interrelated in an opposite manner. Eventually, the interplay among these downstream players induced an imbalance in bone homeostasis, triggering osteoporosis. Notably, these circRNAs differentiated patients from controls and those with osteopenia from osteoporotic ones. Thus, they could serve as biomarkers for early detection and tracking of osteoporosis.

Plasma haem oxygenase-1 may represent a first-in-class biomarker of oxidative stress in rheumatoid arthritis

OBJECTIVES

This study explores the early identification of rheumatoid arthritis (RA) patients at elevated risk of progression. Haem-oxygenase-1 (HO-1) is a marker of oxidative stress in inflammation. Here, we investigate HO-1 as a biomarker of oxidative stress and its association with clinical disease activity and radiographic progression in RA.

METHOD

Baseline HO-1 was measured sequentially in plasma samples from patients with early rheumatoid arthritis (eRA) (n = 80). Disease Activity Score based on 28-joint count-C-reactive protein, Clinical Disease Activity Index, and total Sharp score were used to evaluate the disease course serially over 2 years. Paired plasma and synovial fluid samples were examined for HO-1 in active established rheumatoid arthritis (esRA) (n = 20). Plasma from healthy control subjects was also included (n = 35).

RESULTS

Plasma HO-1 levels were increased in eRA {1373 pg/mL [interquartile range (IQR) 1110-2050]} and esRA [2034 pg/mL (IQR 1630-2923)] compared with controls [1064 pg/mL (IQR 869.5-1378)]. HO-1 plasma levels decreased with treatment. Baseline HO-1 correlated with disease activity and radiographic progression. A strong, linear correlation was found between synovial and plasma HO-1 levels (r = 0.75, p < 0.001).

CONCLUSION

In eRA, plasma levels of HO-1 were increased and correlated with disease and radiographic progression. A baseline measurement of plasma HO-1 levels demonstrated superior performance to currently used clinical and serological disease markers in the prediction of radiographic progression. Plasma HO-1 may function as a first-in-class biomarker of synovial oxidative stress in RA.

The potential therapeutic role of curcumin in osteoporosis treatment: based on multiple signaling pathways

Osteoporosis is a common chronic metabolic bone disease caused by disturbances in normal bone metabolism and an imbalance between osteoblasts and osteoclasts. Osteoporosis is characterized by a decrease in bone mass and bone density, leading to increased bone fragility. Osteoporosis is usually treated with medications and surgical methods, but these methods often produce certain side effects. Therefore, the use of traditional herbal ingredients for the treatment of osteoporosis has become a focus of attention and a hot topic in recent years. Curcumin, widely distributed among herbs such as turmeric, tulip, and curcuma longa, contains phenolic, terpenoid, and flavonoid components. Modern pharmacological studies have confirmed that curcumin has a variety of functions including antioxidant and anti-inflammatory properties. In addition, curcumin positively regulates the differentiation and promotes the proliferation of osteoblasts, which play a crucial role in bone formation. Multiple studies have shown that curcumin is effective in the treatment of osteoporosis as it interacts with a variety of signaling pathway targets, thereby interfering with the formation of osteoblasts and osteoclasts and regulating the development of osteoporosis. This review summarized the key signaling pathways and their mechanisms of action of curcumin in the prevention and treatment of osteoporosis and analyzed their characteristics and their relationship with osteoporosis and curcumin. This not only proves the medicinal value of curcumin as a traditional herbal ingredient but also further elucidates the molecular mechanism of curcumin's anti-osteoporosis effect, providing new perspectives for the prevention and treatment of osteoporosis through multiple pathways.

The relationship between serum monoterpene levels and bone health: a retrospective cross-sectional analysis from the National Health and Nutrition Examination Survey (NHANES) data

Introduction

Monoterpenes, a subset of the terpene family composed of two isoprene units, have garnered significant attention in research circles owing to their potential medicinal benefits. Recent experimental studies indicate that they might exert positive effects on bone health. Nevertheless, the impact of monoterpenes exposure on bone health remains unexplored in humans.

Methods

We examined 748 adults (age ≥ 40 years) from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 to explore the correlation between three monoterpenes (α-pinene, β-pinene, and limonene), bone mineral density (BMD) in the total lumbar spine and proximal femur, FRAX® scores, and prior bone fracture history.

Results and discussion

Our analysis unveiled a significant inverse association between a one-unit increase in the natural logarithm (ln) of α-pinene and limonene and total proximal femur BMD (ß = -0.027, S.E. = 0.008, P = 0.004 and ß = -0.019, S.E. = 0.007, P = 0.016, respectively). As serum α-pinene levels ascended across quintiles, there was a notable decrease in total proximal femur BMD (P for trend = 0.025). The inverse relationship between ln α-pinene levels and total proximal femur BMD was more pronounced in women, especially pre-menopausal women. Compared to subjects with α-pinene and limonene levels at or below the 50th percentiles, those exceeding this threshold exhibited the lowest mean value of total proximal femur BMD (0.8628 g/cm2, S.E. = 0.026, P = 0.009). However, the trend was not statistically significant (P = 0.070). Additionally, all three monoterpenes were linked to a higher prevalence of previous spine fractures, whereas β-pinene showed a reduced incidence of other types of fractures. In this comprehensive survey of American adults aged 40 and above, higher serum levels of α-pinene and limonene correlated with decreased total proximal femur BMD. Furthermore, our findings suggest a potential combined effect of α-pinene and limonene on total proximal femur BMD. Further investigation is essential to elucidate the clinical relevance and causative nature of our findings.

Global Trends in Research of Programmed Cell Death in Osteoporosis: A Bibliometric and Visualized Analysis (2000-2023)

Osteoporosis (OP) is a systemic metabolic bone disease that is characterized by decreased bone mineral density and microstructural damage to bone tissue. Recent studies have demonstrated significant advances in the research of programmed cell death (PCD) in OP. However, there is no bibliometric analysis in this research field. This study searched the Web of Science Core Collection (WoSCC) database for literature related to OP and PCD from 2000 to 2023. This study used VOSviewers 1.6.20, the "bibliometrix" R package, and CiteSpace (6.2.R3) for bibliometric and visualization analysis. A total of 2905 articles from 80 countries were included, with China and the United States leading the way. The number of publications related to PCD in OP is increasing year by year. The main research institutions are Shanghai Jiao Tong University, Chinese Medical University, Southern Medical University, Zhejiang University, and Soochow University. Bone is the most popular journal in the field of PCD in OP, and the Journal of Bone and Mineral Research is the most co-cited journal. These publications come from 14,801 authors, with Liu Zong-Ping, Yang Lei, Manolagas Stavros C, Zhang Wei, and Zhao Hong-Yan having published the most papers. Ronald S. Weinstein was co-cited most often. Oxidative stress and autophagy are the current research hot spots for PCD in OP. This bibliometric study provides the first comprehensive summary of trends and developments in PCD research in OP. This information identifies the most recent research frontiers and hot directions, which will provide a definitive reference for scholars studying PCD in OP.

Saikosaponin A attenuates osteoclastogenesis and bone loss by inducing ferroptosis

To alleviate bone loss, most current drugs target osteoclasts. Saikosaponin A (Ssa), a triterpene saponin derived from Bupleurum falcatum (also known as Radix bupleuri), has immunoregulatory, neuromodulatory, antiviral, anticancer, anti-convulsant, anti-inflammatory, and anti-proliferative effects. Recently, modulation of bone homeostasis was shown to involve ferroptosis. Herein, we aimed to determine Ssa's inhibitory effects on osteoclastogenesis and differentiation, whether ferroptosis is involved, and the underlying mechanisms. Tartrate-resistant acid phosphatase (TRAP) staining, F-actin staining, and pit formation assays were conducted to confirm Ssa-mediated inhibition of RANKL-induced osteoclastogenesis in vitro. Ssa could promote osteoclast ferroptosis and increase mitochondrial damage by promoting lipid peroxidation, as measured by iron quantification, FerroOrange staining, Dichloro-dihydro-fluorescein diacetate, MitoSOX, malondialdehyde, glutathione, and boron-dipyrromethene 581/591 C11 assays. Pathway analysis showed that Ssa can promote osteoclasts ferroptosis by inhibiting the Nrf2/SCL7A11/GPX4 axis. Notably, we found that the ferroptosis inhibitor ferrostatin-1 and the Nrf2 activator tert-Butylhydroquinone reversed the inhibitory effects of Ssa on RANKL-induced osteoclastogenesis. In vivo, micro-computed tomography, hematoxylin and eosin staining, TRAP staining, enzyme-linked immunosorbent assays, and immunofluorescence confirmed that in rats with periodontitis induced by lipopolysaccharide, treatment with Ssa reduced alveolar bone resorption dose-dependently. The results suggested Ssa as a promising drug to treat osteolytic diseases.

Regulation of bone homeostasis by traditional Chinese medicine active scaffolds and enhancement for the osteoporosis bone regeneration

ETHNOPHARMACOLOGICAL RELEVANCE

The active ingredients of traditional Chinese medicine (TCM), such as naringin (NG), Eucommiol, isopsoralen, icariin, Astragalus polysaccharides, and chondroitin sulfate, contained in Drynariae Rhizoma, Eucommiae Cortex, Psoralea corylifolia, Herba Epimedii, Astragalus radix and deer antler, are considered promising candidates for enhancing the healing of osteoporotic defects due to their outstanding bone homeostasis regulating properties. They are commonly used to activate bone repair scaffolds.

AIM OF THE REVIEW

Bone repair scaffolds are inadequate to meet the demands of osteoporotic defect healing due to the lack of regulation of bone homeostasis. Therefore, selecting bone scaffolds activated with TCM to improve the therapeutic effect of repairing osteoporotic bone defects.

MATERIALS AND METHODS

To gather information on bone scaffold activated by traditional Chinese medicine, we conducted a thorough search of several scientific databases, including Google Scholar, Web of Science, Scifinder, Baidu Scholar, PubMed, and China National Knowledge Infrastructure (CNKI).

RESULTS

This review discusses the mechanism of TCM active ingredients in regulating bone homeostasis, including stimulating bone formation and inhibiting bone resorption process and the healing mechanism of traditional bone repair scaffolds activated by them for osteoporotic defect healing.

CONCLUSION

In general, the introduction of TCM active ingredients provides a novel therapeutic approach for modulating bone homeostasis and facilitating osteoporotic defect healing, and also offers a new strategy for design of other unconventional bone defect healing materials.

Harnessing cerium-based biomaterials for the treatment of bone diseases

Bone, an actively metabolic organ, undergoes constant remodeling throughout life. Disturbances in the bone microenvironment can be responsible for pathologically bone diseases such as periodontitis, osteoarthritis, rheumatoid arthritis and osteoporosis. Conventional bone tissue biomaterials are not adequately adapted to complex bone microenvironment. Therefore, there is an urgent clinical need to find an effective strategy to improve the status quo. In recent years, nanotechnology has caused a revolution in biomedicine. Cerium(III, IV) oxide, as an important member of metal oxide nanomaterials, has dual redox properties through reversible binding with oxygen atoms, which continuously cycle between Ce(III) and Ce(IV). Due to its special physicochemical properties, cerium(III, IV) oxide has received widespread attention as a versatile nanomaterial, especially in bone diseases. This review describes the characteristics of bone microenvironment. The enzyme-like properties and biosafety of cerium(III, IV) oxide are also emphasized. Meanwhile, we summarizes controllable synthesis of cerium(III, IV) oxide with different nanostructural morphologies. Following resolution of synthetic principles of cerium(III, IV) oxide, a variety of tailored cerium-based biomaterials have been widely developed, including bioactive glasses, scaffolds, nanomembranes, coatings, and nanocomposites. Furthermore, we highlight the latest advances in cerium-based biomaterials for inflammatory and metabolic bone diseases and bone-related tumors. Tailored cerium-based biomaterials have already demonstrated their value in disease prevention, diagnosis (imaging and biosensors) and treatment. Therefore, it is important to assist in bone disease management by clarifying tailored properties of cerium(III, IV) oxide in order to promote the use of cerium-based biomaterials in the future clinical setting. STATEMENT OF SIGNIFICANCE: In this review, we focused on the promising of cerium-based biomaterials for bone diseases. We reviewed the key role of bone microenvironment in bone diseases and the main biological activities of cerium(III, IV) oxide. By setting different synthesis conditions, cerium(III, IV) oxide nanostructures with different morphologies can be controlled. Meanwhile, tailored cerium-based biomaterials can serve as a versatile toolbox (e.g., bioactive glasses, scaffolds, nanofibrous membranes, coatings, and nanocomposites). Then, the latest research advances based on cerium-based biomaterials for the treatment of bone diseases were also highlighted. Most importantly, we analyzed the perspectives and challenges of cerium-based biomaterials. In future perspectives, this insight has given rise to a cascade of cerium-based biomaterial strategies, including disease prevention, diagnosis (imaging and biosensors) and treatment.

Role of O-linked N-acetylglucosamine protein modification in oxidative stress-induced autophagy: a novel target for bone remodeling

O-linked N-acetylglucosamine protein modification (O-GlcNAcylation) is a dynamic post-translational modification (PTM) involving the covalent binding of serine and/or threonine residues, which regulates bone cell homeostasis. Reactive oxygen species (ROS) are increased due to oxidative stress in various pathological contexts related to bone remodeling, such as osteoporosis, arthritis, and bone fracture. Autophagy serves as a scavenger for ROS within bone marrow-derived mesenchymal stem cells, osteoclasts, and osteoblasts. However, oxidative stress-induced autophagy is affected by the metabolic status, leading to unfavorable clinical outcomes. O-GlcNAcylation can regulate the autophagy process both directly and indirectly through oxidative stress-related signaling pathways, ultimately improving bone remodeling. The present interventions for the bone remodeling process often focus on promoting osteogenesis or inhibiting osteoclast absorption, ignoring the effect of PTM on the overall process of bone remodeling. This review explores how O-GlcNAcylation synergizes with autophagy to exert multiple regulatory effects on bone remodeling under oxidative stress stimulation, indicating the application of O-GlcNAcylation as a new molecular target in the field of bone remodeling.

Association between composite dietary antioxidant and bone mineral density in children and adolescents aged 8-19 years: findings from NHANES

Dietary antioxidants may have beneficial effects on bone health, but it remains uncertain in children and adolescents. This study investigates the association of composite dietary antioxidant index (CDAI) with bone mineral density (BMD) in children and adolescents aged 8-19 years from the National Health and Nutrition Examination Survey (NHANES) 2007-2010. The study assessed the relationship between CDAI and BMD in 2994 individuals aged 8-19 years (average age 13.48 ± 3.32 years) from the NHANES 2007-2010. Multivariate linear regression analyses were utilized to detect the association between CDAI and total spine, femur neck, and total femur BMD, adjusting for confounders including age, race/ethnicity, sex, poverty income ratio (PIR), body mass index (BMI), serum phosphorus and calcium. Stratified analyses and interaction tests were performed to examine the stability of the results. The weighted characteristics showed that subjects in the fourth CDAI quartile were more likely to be older, men, and Non-Hispanic White. They have higher values of serum total calcium and phosphorus. After adjusting all confounders, CDAI was positively associated with the total spine (β = 0.0031 95% CI 0.0021-0.0040), total femur (β = 0.0039 95% CI 0.0028-0.0049), and femur neck BMD (β = 0.0031 95% CI 0.0021-0.0040) in children and adolescents. Furthermore, we found no interaction effects between different race/ethnicity, age, and sex groups. Our findings suggest that dietary intake of multiple antioxidants was positively associated with BMD in children and adolescents. These findings provide valuable evidence for improving bone health in the early stages of life. However, more prospective studies are required to validate our findings and their causal relationship.

New insights into dairy management and the prevention and treatment of osteoporosis: The shift from single nutrient to dairy matrix effects-A review

Dairy is recognized as a good source of calcium, which is important for preventing osteoporosis. However, the relationship between milk and bone health is more complex than just calcium supplementation. It is unwise to focus solely on observing the effects of a single nutrient. Lactose, proteins, and vitamins in milk, as well as fatty acids, oligosaccharides, and exosomes, all work together with calcium to enhance its bioavailability and utilization efficiency through various mechanisms. We evaluate the roles of dairy nutrients and active ingredients in maintaining bone homeostasis from the perspective of the dairy matrix effects. Special attention is given to threshold effects, synergistic effects, and associations with the gut-bone axis. We also summarize the associations between probiotic/prebiotic milk, low-fat/high-fat milk, lactose-free milk, and fortified milk with a reduced risk of osteoporosis and discuss the potential benefits and controversies of these dairy products. Moreover, we examine the role of dairy products in increasing peak bone mass during adolescence and reducing bone loss in old age. It provides a theoretical reference for the use of dairy products in the accurate prevention and management of osteoporosis and related chronic diseases and offers personalized dietary recommendations for bone health in different populations.

Metal-Organic Framework-Based Nanomaterials for Regulation of the Osteogenic Microenvironment

As the global population ages, bone diseases have become increasingly prevalent in clinical settings. These conditions often involve detrimental factors such as infection, inflammation, and oxidative stress that disrupt bone homeostasis. Addressing these disorders requires exogenous strategies to regulate the osteogenic microenvironment (OME). The exogenous regulation of OME can be divided into four processes: induction, modulation, protection, and support, each serving a specific purpose. To this end, metal-organic frameworks (MOFs) are an emerging focus in nanomedicine, which show tremendous potential due to their superior delivery capability. MOFs play numerous roles in OME regulation such as metal ion donors, drug carriers, nanozymes, and photosensitizers, which have been extensively explored in recent studies. This review presents a comprehensive introduction to the exogenous regulation of OME by MOF-based nanomaterials. By discussing various functional MOF composites, this work aims to inspire and guide the creation of sophisticated and efficient nanomaterials for bone disease management.

The Role of Traditional Chinese Medicines in the Treatment of Osteoporosis

Osteoporosis (OP) represents a substantial public health issue and is associated with increasing rates of morbidity and mortality. It is characterized by reduced bone mineral density, deterioration of bone tissue quality, disruption of the microarchitecture of bones, and compromised bone strength. These changes may be attributed to the following factors: intercellular communication between osteoblasts and osteoclasts; imbalanced bone remodeling; imbalances between osteogenesis and adipogenesis; imbalances in hormonal regulation; angiogenesis; chronic inflammation; oxidative stress; and intestinal microbiota imbalances. Treating a single aspect of the disease is insufficient to address its multifaceted nature. In recent decades, traditional Chinese medicine (TCM) has shown great potential in the treatment of OP, and the therapeutic effects of Chinese patent drugs and Chinese medicinal herbs have been scientifically proven. TCMs, which contain multiple components, can target the diverse pathogeneses of OP through a multitargeted approach. Herbs such as XLGB, JTG, GSB, Yinyanghuo, Gusuibu, Buguzhi, and Nvzhenzi are among the TCMs that can be used to treat OP and have demonstrated promising effects in this context. They exert their therapeutic effects by targeting various pathways involved in bone metabolism. These TCMs balance the activity of osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells), and they exhibit anti-inflammatory, immunomodulatory, anti-oxidative, and estrogen-like functions. These multifaceted mechanisms underlie the efficacy of these herbs in the management and treatment of OP. Herein, we examine the efficacy of various Chinese herbs and Chinese patent drugs in treating OP by reviewing previous clinical trials and basic experiments, and we examine the potential mechanism of these therapies to provide evidence regarding the use of TCM for treating OP.

Exogenous and endogenous antioxidants in osteoporosis risk: causal associations unveiled by Mendelian Randomization analysis

Background

Recent epidemiological studies and animal experiments have highlighted the significant role of oxidative stress in the development of osteoporosis (OP). The provision of antioxidants is widely considered a fundamental strategy to combat free radical-induced stress, inhibit oxidative damage, and potentially reverse the adverse effects of oxidative stress on bone health. However, there is no consensus in the scientific literature regarding the practical effectiveness of antioxidants in OP prevention and treatment. Some studies have not shown a clear connection between antioxidant supplementation and decreased OP risk. Therefore, it is essential to clarify the potential causal relationship between antioxidants and the development of OP.

Methods

The study utilized the inverse variance weighted (IVW) approach as the primary analytical method in the Mendelian Randomization (MR) framework to investigate the causal effects of five exogenous and six endogenous antioxidants on the risk of OP. To thoroughly assess potential pleiotropic effects and heterogeneity among the data analyzed, the MR-Egger intercept test was employed, and Cochran's Q statistic was calculated.

Results

In the evaluation of exogenous antioxidants, single-directional two-sample MR analyses did not reveal any statistically significant relationship between these agents and the risk of OP. Regarding endogenous antioxidants, bidirectional two-sample MR analyses were conducted, which generally indicated that most genetically regulated endogenous antioxidants had no significant association with the onset risk of OP. A significant causal relationship was found between OP and serum albumin levels (β: -0.0552, 95%CI: -0.0879 to -0.0225, p < 0.0011 after Bonferroni adjustment, power = 100%).

Conclusion

The research uncovers OP as a possible determinant contributing to a decrement in serum albumin levels, and further suggests a potentially intimate relationship between the downward trajectory of serum albumin concentrations and the advancement of the OP disease process.

Calcified Cartilage-Guided Identification of Osteogenic Molecules and Geometries

Calcified cartilage digested by chondroclasts provides an excellent scaffold to initiate bone formation. We analyzed bioactive proteins and microarchitecture of calcified cartilage either separately or in combination and evaluated biomimetic osteogenic culture conditions of surface-coated micropatterning. To do so, we prepared a crude extract from porcine femoral growth plates, which enhanced in vitro mineralization when coated on flat-bottom culture dishes, and identified four candidate proteins by fractionation and mass spectrometry. Murine homologues of two candidates, desmoglein 4 (DSG4) and peroxiredoxin 6 (PRDX6), significantly promoted osteogenic activity based on in vitro mineralization and osteoblast differentiation. Moreover, we observed DSG4 and PRDX6 protein expression in mouse femur. In addition, we designed circular, triangular, and honeycomb micropatterns with 30 or 50 μm units, either isolated or connected, to mimic hypertrophic chondrocyte-sized compartments. Isolated, larger honeycomb patterns particularly enhanced osteogenesis in vitro. Mineralization on micropatterns was positively correlated with the reduction of osteoblast migration distance in live cell imaging. Finally, we evaluated possible combinatorial effects of coat proteins and micropatterns and observed an additive effect of DSG4 or PRDX6 coating with micropatterns. These data suggest that combining a bioactive surface coating with osteogenic micropatterns may recapitulate initiation of bone formation during endochondral ossification.

Mediation of mitochondrial DNA copy number and oxidative stress in fluoride-related bone mineral density alteration in Chinese farmers

Excessive fluoride can adversely affect bone mineral density (BMD). Oxidative stress and mitochondrial dysfunction are crucial mechanisms of health damage induced by fluoride. Here, a cross-sectional survey involving 907 Chinese farmers (aged 18-60) was carried out in Tongxu County in 2017, aiming to investigate the significance of mitochondrial DNA copy number (mtDNAcn) and oxidative stress in fluoride-related BMD change. Concentrations of urinary fluoride (UF), serum oxidative stress biomarkers, including total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA), as well as relative mtDNAcn in peripheral blood were determined. The multivariable linear model and mediation analysis were performed to assess associations between UF, oxidative stress, and relative mtDNAcn with BMD. Results showed that GSH-Px levels increased by 6.98 U/mL [95% confidence interval (CI) 3.41-10.56)] with each 1.0 mg/L increment of UF. After stratification, the T-AOC, relative mtDNAcn, and BMD decreased by 0.04 mmol/L (-0.08 ~ -0.01), 0.29-unit (-0.55 ~ -0.04), and 0.18-unit (-0.33 ~ -0.03) with every 1.0 mg/L elevation of UF in the excessive fluoride group (EFG, adults with UF > 1.6 mg/L), respectively. Furthermore, T-AOC and relative mtDNAcn were favorably related to the BMD in the EFG (β = 0.82, 95%CI 0.16-1.48 for T-AOC; β = 0.11, 95%CI 0.02-0.19 for relative mtDNAcn). Mediation analysis showed that relative mtDNAcn and T-AOC mediated 15.4% and 17.1% of the connection between excessive fluoride and reduced BMD, respectively. Findings suggested that excessive fluoride was related to lower BMD in adults, and the decrement of T-AOC and relative mtDNAcn partially mediate this relationship.

Novel Peptides from Sturgeon Ovarian Protein Hydrolysates Prevent Oxidative Stress-Induced Dysfunction in Osteoblast Cells: Purification, Identification, and Characterization

This study aimed to explore antioxidant peptides derived from sturgeon (Acipenser schrenckii) ovaries that exhibit antiosteoporotic effects in oxidative-induced MC3T3-E1 cells. The F3-15 component obtained from sturgeon ovarian protein hydrolysates (SOPHs) via gel filtration and RP-HPLC significantly increased the cell survival rate (from 49.38 ± 2.88 to 76.26 ± 2.09%). Two putative antioxidant-acting peptides, FDWDRL (FL6) and FEGPPFKF (FF8), were screened from the F3-15 faction via liquid chromatography-tandem mass spectrometry (LC-MS/MS) and through prediction by computer simulations. Molecular docking results indicated that the possible antioxidant mechanisms of FL6 and FF8 involved blocking the active site of human myeloperoxidase (hMPO). The in vitro tests showed that FL6 and FF8 were equally adept at reducing intracellular ROS levels, increasing the activity of antioxidant enzymes, and protecting cells from oxidative injuries by inhibiting the mitogen-activated protein kinase (MAPK) pathway and activating the phosphoinositide-3 kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase-3β (GSK-3β) signaling pathway. Moreover, both peptides could increase differentiation and mineralization abilities in oxidatively damaged MC3T3-E1 cells. Furthermore, FF8 exhibited high resistance to pepsin and trypsin, showcasing potential for practical applications.

Lipolysis products from triglyceride-rich lipoproteins induce stress protein ATF3 in osteoblasts

High fat diets overwhelm the physiological mechanisms for absorption, storage, and utilization of triglycerides (TG); consequently TG, TG-rich lipoproteins (TGRL), and TGRL remnants accumulate, circulate systemically, producing dyslipidemia. This associates with, or is causative for increased atherosclerotic cardiovascular risk, ischemic stroke, fatty liver disease, and pancreatitis. TGRL hydrolysis by endothelial surface-bound lipoprotein lipase (LPL) generates metabolites like free fatty acids which have proinflammatory properties. While osteoblasts utilize fatty acids as an energy source, dyslipidemia is associated with negative effects on the skeleton. In this study we investigated the effects of TGRL lipolysis products (TGRL-LP) on expression of a stress responsive transcription factor, termed activating transcription factor 3 (ATF3), reactive oxygen species (ROS), ATF3 target genes, and angiopoietin-like 4 (Angptl4) in osteoblasts. As ATF3 negatively associates with osteoblast differentiation, we also investigated the skeletal effects of global ATF3 deletion in mice. TGRL-LP increased expression of Atf3, proinflammatory proteins Ptgs2 and IL-6, and induced ROS in MC3T3-E1 osteoblastic cells. Angptl4 is an endogenous inhibitor of LPL which was transcriptionally induced by TGRL-LP, while recombinant Angptl4 prevented TG-driven Atf3 induction. Atf3 global knockout male mice demonstrated increased trabecular and cortical microarchitectural parameters. In summary, we find that TGRL-LP induce osteoblastic cell stress as evidenced by expression of ATF3, which may contribute to the negative impact of dyslipidemia in the skeleton. Further, concomitant induction of Angptl4 in osteoblasts might play a protective role by reducing local lipolysis.

Pharmacological inhibition of endoplasmic reticulum stress mitigates osteoporosis in a mouse model of hindlimb suspension

Hindlimb suspension (HLS) mice exhibit osteoporosis of the hindlimb bones and may be an excellent model to test pharmacological interventions. We investigated the effects of inhibiting endoplasmic reticulum (ER) stress with 4-phenyl butyrate (4-PBA) on the morphology, physicochemical properties, and bone turnover markers of hindlimbs in HLS mice. We randomly divided 21 male C57BL/6J mice into three groups, ground-based controls, untreated HLS group and 4-PBA treated group (HLS+4PBA) (100mg/kg/day, intraperitoneal) for 21 days. We investigated histopathology, micro-CT imaging, Raman spectroscopic analysis, and gene expression. Untreated HLS mice exhibited reduced osteocyte density, multinucleated osteoclast-like cells, adipocyte infiltration, and reduced trabecular striations on micro-CT than the control group. Raman spectroscopy revealed higher levels of ER stress, hydroxyproline, non-collagenous proteins, phenylalanine, tyrosine, and CH2Wag as well as a reduction in proteoglycans and adenine. Furthermore, bone alkaline phosphatase and osteocalcin were downregulated, while Cathepsin K, TRAP, and sclerostin were upregulated. Treatment with 4-PBA partially restored normal bone histology, increased collagen crosslinking, and mineralization, promoted anti-inflammatory markers, and downregulated bone resorption markers. Our findings suggest that mitigating ER stress with 4-PBA could be a therapeutic intervention to offset osteoporosis in conditions mimicking hindlimb suspension.

Chromium Picolinate Regulates Bone Metabolism and Prevents Bone Loss in Diabetic Rats

Diabetic osteoporosis (DOP) is an abnormal metabolic disease caused by long-term hyperglycemia. In this study, a model rat of streptozotocin (STZ)-induced diabetes was established, and chromium picolinate (5 mg·kg-1) was given; the changes in blood glucose and body weight were detected before and after administration; and bone mineral density (BMD), bone morphology, bone turnover markers, inflammatory cytokines, and oxidative stress indicators were observed in each group. We found that after chromium picolinate (CP) intervention for 8 weeks, the blood glucose level was decreased; the BMD, the bone histomorphology parameters, and the pathological structure were improved; the expression of bone resorption-related proteins was downregulated; and the expression of bone formation-related proteins was upregulated. Meanwhile, serum antioxidant activity was increased, and inflammatory cytokine levels were decreased. In conclusion, CP could alleviate DOP by anti-oxidation, inhibition of bone turnover, anti-inflammation, and regulation of the OPG/RANKL/RANK signaling pathway. Therefore, CP has important application values for further development as a functional food or active medicine in DOP 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.

Effect of Hyperprolactinemia on Bone Metabolism: Focusing on Osteopenia/Osteoporosis

Prolactin is a hormone secreted from lactotroph cells in the anterior pituitary gland to induce lactation after birth. Hyperprolactinemia unrelated to lactation is a common cause of amenorrhea in women of a childbearing age, and a consequent decrease in the gonadotropin-releasing hormone (GnRH) by a high prolactin level can result in decreased bone mineral density. Osteoporosis is a common skeletal disorder characterized by decreased bone mineral density (BMD) and quality, which results in decreased bone strength. In patients with hyperprolactinemia, changes in BMD can be induced indirectly by the inhibition of the GnRH-gonadal axis due to increased prolactin levels or by the direct action of prolactin on osteoblasts and, possibly, osteoclast cells. This review highlights the recent work on bone remodeling and discusses our knowledge of how prolactin modulates these interactions, with a brief literature review on the relationship between prolactin and bone metabolism and suggestions for new possibilities.

Partial body fat percentage as a predictor of fragility fractures in a large cohort: a cross-sectional study

Objectives

BMI is a component of fracture risk calculators; however, it may be too simplistic to predict fracture risk. There is emerging evidence for the role that fat plays as a predictor of fracture. Partial body fat percentage (PBF%) may be a novel way to predict both hip and non-hip fractures. The aim of this study is to evaluate PBF% as a predictor of fragility fractures.

Methods

A multivariate logistic regression analysis was conducted looking at PBF% as a predicter of both non-hip and hip fractures in an observational cohort. Our results were adjusted for age, biological sex, gender, smoking status, excess alcohol consumption (>3 units/day), current steroid therapy and the T-scores in both femurs. To allow for comparison, the same model was used with BMI, height and weight as the primary predictor of fracture. A subgroup analysis was conducted stratified by fracture site. A sensitivity analysis using a negative binomial regression was conducted.

Results

A total of 31 447 patients were included in our analysis [mean age 64.9 years (s.d. 12.9)]. PBF% was shown to predict all non-hip fractures after adjustment [odds ratio (OR) 22.14 (95% CI 15.08, 32.50)]. Hip fractures were not predicted by our model [OR 4.19 (95% CI 0.43, 41.46)]. Sensitivity analysis demonstrated a lack of predictive capability for hip fracture but not non-hip fractures.

Conclusion

PBF% may be a suitable predictor for all non-hip fractures, independent of confounding variables. More research is needed on whether it can predict hip fractures.

The Effects and Safety of Silymarin on β-thalassemia in Children and Adolescents: A Systematic Review based on Clinical Trial Studies

BACKGROUND

β-thalassemia imposes significant complications on affected patients. Silymarin, a natural flavonoid complex, has potential therapeutic properties.

OBJECTIVE

This systematic review aims to comprehensively evaluate the literature on the mechanistic effects of Silymarin on β-thalassemia outcomes in children and adolescents.

METHODS

A systematic search of electronic databases, including MEDLINE/PubMed, Embase, Scopus, Cochrane Library, and Web of Science (WOS), was done to identify relevant clinical trials before January 2024. Various data were extracted, including study characteristics, outcomes measured (hematological parameters, oxidative stress markers, iron metabolism, and other outcomes), proposed mechanisms, and safety.

RESULTS

By iron chelation effects, Silymarin can reduce reactive oxygen species (ROS) production, increase intracellular antioxidant enzyme glutathione (GSH), and insert antioxidant effects. It also attenuated inflammation through reduced tumor necrosis factor-alpha (TNF-α), transforming growth factor-β1 (TGF-β1), interferon-gamma (IFNγ), C-reactive protein (CRP), interleukin 6 (IL-6), IL-17, and IL-23 levels and increase in IL-4 and IL-10 levels. By reducing iron overload conditions, Silymarin indicates modulatory effects on immune abnormalities, inhibits red blood cell (RBC) hemolysis, increases RBC count, and minimizes the need for a transfusion. Moreover, it reduces myocardial and hepatic siderosis, improves liver function tests, and modifies abnormal enzymes, particularly for aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), total bilirubin, and total protein levels. Silymarin also reduces iron overload, increases antioxidant and anti-inflammatory capacity in cardiomyocytes, and reveals antioxidant effects.

CONCLUSION

Silymarin indicates promising effects on various aspects of children and adolescents with β-thalassemia and has no serious side effects on the investigated dosage.

Nrf2 Mitigates RANKL and M-CSF Induced Osteoclast Differentiation via ROS-Dependent Mechanisms

Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been shown to be a negative regulator of osteoclast differentiation, but the precise mechanisms have not yet been established. We examined the precise roles of Nrf2 in regulating antioxidants and reactive oxygen species (ROS) levels, especially the cytoplasmic and mitochondrial ROS during osteoclastogenesis in vitro. In the current study, we found that the absence of Nrf2 promotes osteoclast differentiation in bone-marrow-derived macrophages (BMMs) and RAW 264.7 cells. The receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) significantly lowered the levels of Nrf2 and its downstream antioxidant enzymes at mRNA and/or protein levels during osteoclast differentiation in the BMMs of mice and RAW 264.7 mouse leukemic monocytes. Compared to the wild-type cells, Nrf2-deficient cells exhibited heightened sensitivity to both transient RANKL-induced cytoplasmic ROS and prolonged RANKL and M-CSF-induced cytoplasmic and mitochondrial ROS accumulation. Furthermore, exogenous antioxidant agents, including N-acetyl-cysteine (NAC), diphenyleneiodonium chloride (DPI), and mitoquinone mesylate (MitoQ), exhibited substantial capability to suppress the elevation of ROS levels during osteoclast differentiation induced by Nrf2 deficiency, and they consequently inhibited osteoclast differentiation augmented by the lack of Nrf2. The activation of phosphorylated c-FOS resulting from elevated ROS promoted osteoclast differentiation. The inhibition of c-FOS blocked osteoclast differentiation, which was elevated by Nrf2-deficiency. Taken together, these data reveal that Nrf2 effectively decreased the accumulation of intracellular ROS and the phosphorylation of c-FOS during osteoclastic differentiation by regulating antioxidant enzymes and subsequently inhibited RANKL-induced osteoclast differentiation.

A comprehensive review on environmental pollutants and osteoporosis: Insights into molecular pathways

A significant problem that has an impact on community wellbeing is environmental pollution. Environmental pollution due to air, water, or soil pollutants might pose a severe risk to global health, necessitating intense scientific effort. Osteoporosis is a common chronic condition with substantial clinical implications on mortality, morbidity, and quality of life. It is closely linked to bone fractures. Worldwide, osteoporosis affects around 200 million people, and every year, there are almost 9 million fractures. There is evidence that certain environmental factors may increase the risk of osteoporosis in addition to traditional risk factors. It is crucial to understand the molecular mechanisms at play because there is a connection between osteoporosis and exposure to environmental pollutants such as heavy metals, air pollutants, endocrine disruptors, metal ions and trace elements. Hence, in this scoping review, we explore potential explanations for the link between pollutants and bone deterioration through deep insights into molecular pathways. Understanding and recognizing these pollutants as modifiable risk factors for osteoporosis would possibly help to enhance environmental policy thereby aiding in the improvement of bone health and improving patient quality of life.

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.