Aspirin prevents estrogen deficiency-induced bone loss by inhibiting osteoclastogenesis and promoting osteogenesis

COX-2 inhibition as a therapeutic strategy for bone loss in Staphylococcus aureus osteomyelitis

Bone loss in Staphylococcus aureus (S. aureus) osteomyelitis poses a serious challenge to orthopedic treatment, but the underlying mechanism of systemic osteoporosis caused by chronic infection is not completely clear. In this study, γ-irradiation-killed S. aureus (IKSA) was applied to simulate the inflammation and explore the mechanism of systemic bone loss caused by it. In this study, we found that the systemic application of IKSA caused bone loss in mice through increasing osteoclasts and decreasing osteoblasts. An immune response profile with up-regulated COX-2 is identified based on our transcriptional data from IKSA mice bone marrow cells. COX-2 expression is widely up-regulated in bone marrow immune cells, such as myeloid-derived suppressor cells (MDSCs), neutrophils and macrophages in the IKSA-treated mice. Mechanistically, COX-2 stimulated the increasing proportion of MDSCs and neutrophils and the inflammatory response of the bone marrow immune cells, that may regulate bone metabolism. Importantly, COX-2 inhibitor, celecoxib could rescue the bone loss induced by IKSA, which may reason from decrease of inflammatory gene expression in MDSCs, neutrophils and macrophages. Excitingly, COX-2 expression is also increased in bone marrow from mice and patients with S. aureus osteomyelitis. These findings suggested a therapeutic potential for inhibiting COX-2 in combating bone loss in S. aureus osteomyelitis.

Application of Mendelian randomization analysis to explore causal associations of aspirin use with bone mineral density and risk of fracture

OBJECTIVE

Previous observational studies on the association between aspirin use, bone mineral density (BMD), and fracture risk have yielded controversial results. This study explored the causal relationship between aspirin use, BMD, and fracture risk using Mendelian randomization (MR).

METHODS

Summary data for aspirin use and BMD of five different body parts (femoral neck, lumbar spine, forearm, heel, and ultra distal forearm) and fractures were obtained from the integrative epidemiology unit open genome-wide association studies database for bidirectional MR analysis. An appropriate model was chosen based on Cochran's Q test, with inverse variance-weighted as the primary method for MR analysis, supplemented by the weighted-median and MR-Egger methods. MR-Egger and MR-PRESSO were used to test for horizontal pleiotropy and exclude significant outliers that could bias the results. Various sensitivity analyses, including leave-one-out analysis, were conducted to ensure the robustness of the findings.

RESULTS

Aspirin use significantly increased lumbar spine BMD (odds ratio [OR] = 4.660; 95% confidence interval [CI]: 1.365-15.906; P = 0.014). No significant causal association was found between aspirin use and fracture risk (beta = 59.951; 95% CI: -265.189-385.091; P = 0.718). No significant reverse causality was observed.

CONCLUSION

This study indicates that aspirin use does not significantly affect fracture risk but has a significant protective effect on lumbar spine BMD, revealing a potential benefit of aspirin against osteoporosis.

Manipulation of signaling pathways in bone tissue engineering and regenerative medicine: Current knowledge, novel strategies, and future directions

During osteogenesis, a large number of bioactive molecules, macromolecules, cells, and cellular signals are activated to induce bone growth and development. The activation of molecular pathways leads to the occurrence of cellular events, ultimately resulting in observable changes. Therefore, in the studies of bone tissue engineering and regenerative medicine, it is essential to target fundamental events to exploit the mechanisms involved in osteogenesis. In this context, signaling pathways are activated during osteogenesis and trigger the activation of numerous other processes involved in osteogenesis. Direct influence of signaling pathways should allow to manipulate the signaling pathways themselves and impact osteogenesis. A combination of sequential cascades takes place to drive the progression of osteogenesis. Also, the occurrence of these processes and, more generally, cellular and molecular processes related to osteogenesis necessitate the presence of transcription factors and their activity. The present review focuses on outlining several signaling pathways and transcription factors influencing the development of osteogenesis, and describes various methods of their manipulation to induce and enhance bone formation.

Metabolic syndrome promotes resistance to aspirin in mitigating bone loss in murine periodontal disease

AIMS

This study aimed to investigate the protective effects of aspirin (ASA) on alveolar bone loss in a mouse model with metabolic syndrome (MetS) and concurrent periodontal disease (PD). Specifically, the study sought to determine whether ASA could mitigate bone loss in MetS and non-MetS animals with PD and explore the correlation between gingival nitric oxide (NO) levels and bone resorption.

MAIN METHODS

Newborn female Swiss mice were administered monosodium glutamate (MSG) (4 mg/g) during the initial 5 days of life to induce MetS (MetS group), while the control group (SAL) was administered saline. On the 60th day, PD was induced in both groups. Half of the animals were treated daily with ASA (40 mg/kg). MetS was characterized by the Lee index, blood glucose, and cardiovascular parameters. Maxillae were evaluated by microtomography and histopathology, showing significant bone loss after PD induction.

KEY FINDINGS

Animals with MetS exhibited higher alveolar bone loss than controls. SAL animals treated with ASA had less bone loss than their MetS counterparts. Gingival NO levels were elevated in animals with PD, and a strong correlation was found between NO levels and bone resorption. ASA reduced NO in non-MetS animals, but MetS animals were resistant to this effect.

SIGNIFICANCE

These findings suggest a protective mechanism of ASA against bone loss in non-MetS animals with PD, an effect that was not observed in MetS animals. Consequently, this study provides novel insights into the intricate relationship between MetS and PD in mice.

The role of the Piezo1 channel in osteoblasts under cyclic stretching: A study on osteogenic and osteoclast factors

OBJECTIVES

Orthodontic tooth movement is a mechanobiological reaction induced by appropriate forces, including bone remodeling. The mechanosensitive Piezo channels have been shown to contribute to bone remodeling. However, information about the pathways through which Piezo channels affects osteoblasts remains limited. Thus, we aimed to investigate the influence of Piezo1 on the osteogenic and osteoclast factors in osteoblasts under mechanical load.

MATERIALS AND METHODS

Cyclic stretch (CS) experiments on MC3T3-E1 were conducted using a BioDynamic mechanical stretching device. The Piezo1 channel blocker GsMTx4 and the Piezo1 channel agonist Yoda1 were used 12 h before the application of CS. MC3T3-E1 cells were then subjected to 15% CS, and the expression of Piezo1, Piezo2, BMP-2, OCN, Runx2, RANKL, p-p65/p65, and ALP was measured using quantitative real-time polymerase chain reaction, western blot, alkaline phosphatase staining, and immunofluorescence staining.

RESULTS

CS of 15% induced the highest expression of Piezo channel and osteoblast factors. Yoda1 significantly increased the CS-upregulated expression of Piezo1 and ALP activity but not Piezo2 and RANKL. GsMTx4 downregulated the CS-upregulated expression of Piezo1, Piezo2, Runx2, OCN, p-65/65, and ALP activity but could not completely reduce CS-upregulated BMP-2.

CONCLUSIONS

The appropriate force is more suitable for promoting osteogenic differentiation in MC3T3-E1. The Piezo1 channel participates in osteogenic differentiation of osteoblasts through its influence on the expression of osteogenic factors like BMP-2, Runx2, and OCN and is involved in regulating osteoclasts by influencing phosphorylated p65. These results provide a foundation for further exploration of osteoblast function in orthodontic tooth movement.

A Machine Learning Framework for Screening Plasma Cell-Associated Feature Genes to Estimate Osteoporosis Risk and Treatment Vulnerability

Osteoporosis, in which bones become fragile owing to low bone density and impaired bone mass, is a global public health concern. Bone mineral density (BMD) has been extensively evaluated for the diagnosis of low bone mass and osteoporosis. Circulating monocytes play an indispensable role in bone destruction and remodeling. This work proposed a machine learning-based framework to investigate the impact of circulating monocyte-associated genes on bone loss in osteoporosis patients. Females with discordant BMD levels were included in the GSE56815, GSE7158, GSE7429, and GSE62402 datasets. Circulating monocyte types were quantified via CIBERSORT, with subsequent selection of plasma cell-associated DEGs. Generalized linear models, random forests, extreme gradient boosting (XGB), and support vector machines were adopted for feature selection. Artificial neural networks and nomograms were subsequently constructed for osteoporosis diagnosis, and the molecular machinery underlying the identified genes was explored. SVM outperformed the other tuned models; thus, the expression of several genes (DEFA4, HLA-DPB1, LCN2, HP, and GAS7) associated with osteoporosis were determined. ANNs and nomograms were proposed to robustly distinguish low and high BMDs and estimate the risk of osteoporosis. Clozapine, aspirin, pyridoxine, etc. were identified as possible treatment agents. The expression of these genes is extensively posttranscriptionally regulated by miRNAs and m6A modifications. Additionally, they participate in modulating key signaling pathways, e.g., autophagy. The machine learning framework based on plasma cell-associated feature genes has the potential for estimating personalized risk stratification and treatment vulnerability in osteoporosis patients.

Multifaceted Materials for Enhanced Osteogenesis and Antimicrobial Properties on Bioplastic Polyetheretherketone Surfaces: A Review

Implant-associated infections and the increasing number of bone implants loosening and falling off after implantation have become urgent global challenges, hence the need for intelligent alternative solutions to combat implant loosening and falling off. The application of polyetheretherketone (PEEK) in biomedical and medical therapy has aroused great interest, especially because its elastic modulus close to bone provides an effective alternative to titanium implants, thereby preventing the possibility of bone implants loosening and falling off due to the mismatch of elastic modulus. In this Review, we provide a comprehensive overview of recent advances in surface modifications to prevent bone binding deficiency and bacterial infection after implantation of bone implants, starting with inorganics for surface modification, followed by organics that can effectively promote bone integration and antimicrobial action. In addition, surface modifications derived from cells and related products of biological activity have been proposed, and there is increasing evidence of clinical potential. Finally, the advantages and future challenges of surface strategies against medical associated poor osseointegration and infection are discussed, with promising prospects for developing novel osseointegration and antimicrobial PEEK materials.