Effects of Melandrium firmum Rohrbach on RANKL‑induced osteoclast differentiation and OVX rats

Proteomic analysis of exosomal proteins associated with bone healing speed in a rat tibial fracture model

This study investigates the impact of exosomes on bone fracture healing in a rat tibial model, distinguishing between fast and slow healing processes. Bone healing and protein expression were assessed through X-ray examinations, hematoxylin and eosin staining, and immunohistochemical staining. Exosomes were isolated, characterized and subjected to liquid chromatography-mass spectrometry for protein analysis. Molecular differences were explored using differentially expressed protein analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment and protein-protein interaction networks. Differential bone healing patterns and protein expressions were observed between the control and model groups. Exosomes were successfully isolated and characterized, revealing 2004 identified proteins, including distinct expression profiles. Notably, ribosomal proteins, ferritin and beta-actin emerged as pivotal players in bone fracture healing. This study unveils dynamic changes in bone healing and underscores the role of exosomes in the process. Identified proteins and pathways offer valuable insights for developing innovative therapeutic strategies for bone healing.

Gleditsiae fructus regulates osteoclastogenesis by inhibiting the c‑Fos/NFATc1 pathway and alleviating bone loss in an ovariectomy model

Medical and economic developments have allowed the human lifespan to extend and, as a result, the elderly population has increased worldwide. Osteoporosis is a common geriatric disease that has no symptoms and even a small impact can cause fractures in patients, leading to a serious deterioration in the quality of life. Osteoporosis treatment typically involves bisphosphonates and selective estrogen receptor modulators. However, these treatments are known to cause severe side effects, such as mandibular osteonecrosis and breast cancer, if used for an extended period of time. Therefore, it is essential to develop therapeutic agents from natural products that have fewer side effects. Gleditsiae fructus (GF) is a dried or immature fruit of Gleditsia sinensis Lam. and is composed of various triterpenoid saponins. The anti‑inflammatory effect of GF has been confirmed in various diseases, and since the anti‑inflammatory effect plays a major role in inhibiting osteoclast differentiation, GF was expected to be effective in osteoclast differentiation and menopausal osteoporosis; however, to the best of our knowledge, it has not yet been studied. Therefore, the present study was designed to examine the effect of GF on osteoclastogenesis and to investigate the mechanism underlying inhibition of osteoclast differentiation. The effects of GF on osteoclastogenesis were determined in vitro by tartrate‑resistant acid phosphatase (TRAP) staining, pit formation assays, filamentous actin (F‑actin) ring formation assays, western blotting and reverse transcription‑quantitative PCR analyses. Furthermore, the administration of GF to an animal model exhibiting menopausal osteoporosis allowed for the analysis of alterations in the bone microstructure of the femur using micro‑CT. Additionally, assessments of femoral tissue and serum were conducted. The present study revealed that the administration of GF resulted in a reduction in osteoclast levels, F‑actin rings, TRAP activity and pit area. Furthermore, GF showed a dose‑dependent suppression of nuclear factor of activated T‑cells cytoplasmic, c‑Fos and other osteoclastogenesis‑related markers.

Effects of glucagon‑like peptide‑1 receptor agonists on fracture healing in a rat osteoporotic model

Osteoporosis is a common disease characterized by reduced bone mass, microstructural deterioration, fragility and consequent fragility fractures and is particularly prevalent among the elderly population. Although glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have positive effects on bones, their role in the prevention of osteoporotic fractures remains to be elucidated. The present study assigned female Sprague Dawley rats with osteoporotic fractures into variectomized osteoporosis (OVX), OVX + liraglutide (LIRA) (50 µg/kg/day subcutaneous LIRA) and control groups. At 3 and 6 weeks postoperatively, X-ray, tartrate-resistant acid phosphatase (TRAP) staining, histological and biomechanical assays and assessment of femoral bone mineral density (BMD) were performed. Compared with the OVX group, GLP-1 RA treatment improved the formation of calluses and osseous union. TRAP staining showed significantly fewer osteoclasts in the OVX + LIRA group compared with the OVX group. In the osteoporotically fractured rats, LIRA improved bone strength at the femoral diaphysis, stiffness, ultimate load and femoral trabecular BMD Compared with the OVX group. GLP-1 RA treatment inhibited osteoclast formation and improved trabecular bone architecture and mass in osteoporotic fracture model rats, leading to improved biomechanical strength. GLP-1 RAs may be used as novel anti-osteoporotic fracture agents.

Obacunone inhibits RANKL/M-CSF-mediated osteoclastogenesis by suppressing integrin- FAK-Src signaling

Disrupted osteoblastogenesis or aberrant activation of osteoclastogenesis usually results in the break of bone homeostasis thus causing bone-associated diseases like osteoporosis. Obacunone, as a natural compound present in citrus fruits, has been demonstrated for various biological activities including anti-cancer and anti-inflammatory properties. However, the role of obacunone in regulating osteoclastogenesis has not been elucidated so far. Here, using in vitro cell models of RANKL (Receptor activator of nuclear factor-kB ligand) and M-CSF (Macrophage-colony-stimulating factor)-induced osteoclastogenesis, we showed that obacunone inhibited osteoclast differentiation in RAW264.7 cells and bone marrow macrophages (BMMs), as evidenced by obacunone dose-dependent reduction in numbers of osteoclasts and downregulated expressions of osteoclastogenesis-associated key genes. The anti-osteoclastic properties of obacunone were associated with downregulated expressions of Integrin α1 and attenuated activation of Focal adhesion kinase (FAK) and Steroid receptor coactivator (Src) signaling. Functional Integrin α1 blockade or FAK-Src inhibition suppressed RANKL/M-CSF-induced osteoclastogenesis, while Integrin α1 overexpression or FAK/Src activation partially attenuated obacunone's effects on suppressing RANKL/M-CSF-induced osteoclast differentiation. Furthermore, in vivo administration of obacunone displayed super therapeutic effects in attenuating ovariectomy-induced bone loss in mice, as indicated by decreases in serum biomarkers of bone turnover, restoring of femur fracture maximum force, and reversing of the worsened bone-related parameters in ovariectomized animals. Taken together, these findings demonstrate that obacunone has pharmacological activities to suppress osteoclast differentiation through modulating the Integrin-FAK-Src pathway, and suggest that obacunone is a therapeutic candidate for the treatment and prevention of bone diseases such as osteoporosis.

Effect of Taraxaci Herba on Bone Loss in an OVX-Induced Model through the Regulation of Osteoclast Differentiation

Bone is a dynamic tissue that maintains homeostasis with a balance of osteoclasts for bone resorption and osteoblasts for bone formation. Women are deficient in estrogen after menopause, which promotes bone resorption due to excessive activity of osteoclasts, leading to osteoporosis. TH (also known as dandelion) is native to warm regions and has traditionally been used to treat gynecological diseases and inflammation. Menopause is a major cause of osteoporosis as it causes abnormal activity of osteoclasts, and various studies have shown that anti-inflammatory drugs have the potential to treat osteoporosis. We analyzed the effect of TH on osteoclast differentiation and the relevant mechanisms using RANKL. After administration of TH in a menopause-like rat model in which ovariectomy of the was rats carried out, changes in bone microstructure were analyzed via micro-CT, and the antiosteoporosis effect of TH was verified by a histological analysis. In addition, the pharmacological effects of TH in an animal model of osteoporosis were compared and analyzed with osteoporosis medications (17β-estradiol (E₂) and alendronate (ALN)). TH significantly inhibited the initial osteoclast differentiation via the NFATc1/c-Fos mechanism. In addition, bone density in the femur of osteoporotic rats was increased, and the expression of osteoclast-related factors in the serum and tissues was controlled. The results of this study provide objective evidence of the inhibitory effect of TH on osteoclastogenesis and OVX-induced bone loss.

Effects of Sparganii Rhizoma on Osteoclast Formation and Osteoblast Differentiation and on an OVX-Induced Bone Loss Model

Postmenopausal osteoporosis is caused by an imbalance between osteoclasts and osteoblasts and causes severe bone loss. Osteoporotic medicines are classified into bone resorption inhibitors and bone formation promoters according to the mechanism of action. Long-term use of bisphosphonate and selective estrogen receptor modulators (SERMs) can cause severe side effects in postmenopausal osteoporosis patients. Therefore, it is important to find alternative natural products that reduce osteoclast activity and increase osteoblast formation. Sparganii Rhizoma (SR) is the dried tuberous rhizome of Sparganium stoloniferum Buchanan-Hamilton and is called “samreung” in Korea. However, to date, the effect of SR on osteoclast differentiation and the ovariectomized (OVX)-induced bone loss model has not been reported. In vitro, tartrate-resistant acid phosphatase (TRAP) staining, western blots, RT-PCR and other methods were used to examine the effect of SR on osteoclast differentiation and osteoblasts. In vivo, we confirmed the effect of SR in a model of OVX-induced postmenopausal osteoporosis. SR inhibited osteoclast differentiation and decreased the expression of TNF receptor-associated factor 6 (TRAF6), nuclear factor of activated T cells 1 (NFATc1) and c-Fos pathway. In addition, SR stimulates osteoblast differentiation and increased protein expression of the bone morphogenetic protein 2 (BMP-2)/SMAD signaling pathway. Moreover, SR protected against bone loss in OVX-induced rats. Our results appear to advance our knowledge of SR and successfully demonstrate its potential role as a osteoclastogenesis-inhibiting and osteogenesis-promoting herbal medicine for the treatment of postmenopausal osteoporosis.