Naringenin can Inhibit the Pyroptosis of Osteoblasts by Activating the Nrf2/HO-1 Signaling Pathway and Alleviate the Differentiation Disorder of Osteoblasts Caused by Microgravity

Naringenin (4,5,7-trihydroxyflavone, NAR) is an effective active ingredient in Rhizoma Drynariae, which has many biological functions, encompassing anti-inflammatory and -oxidant functions. Prior research has shown that NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasomes possessed a significant contribution to osteoporosis. However, the NAR impact on bone loss caused by microgravity remains unclear. Classical microgravity simulation methods were used to induce simulated microgravity (SMG) in mice and cells. Microcomputed tomography, immunohistochemical examination, and hematoxylin and eosin staining were implemented to ascertain alterations in bone microstructure and morphology in mice subsequent to NAR gavage. Cellular investigations were implemented encompassing quantitative real-time polymerase chain reaction, Western blotting, and immunofluorescence labeling to investigate the molecular mechanism behind NAR resistance to microgravity-induced bone loss. Our research has shown that NAR can significantly enhance the SMG-stimulated alterations in bone microstructure and morphology in mice, mainly by increasing the trabecular thickness, bone volume fraction, and trabecular number while increasing the bone trabecula number. Cell experiments also showed that SMG caused the activation of inflammatory corpuscles of NLRP3 and induced pyroptosis simultaneously, which can be confirmed by the upregulation of protein and mRNA expression levels such as those of NLRP3, cleaved caspase-1, gasdermin D, and apoptosis-associated speck-like protein. The occurrence of pyroptosis further led to the disorder of osteogenic differentiation, which showed that the osteopontin, Runt-related transcription factor 2, bone morphogenetic protein 2, and alkaline phosphatase expression levels were decreased. The intervention of NAR can activate the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway, reverse this phenomenon via controlling the reactive oxygen species generation in cells and correcting mitochondrial malfunction, weaken the pyroptosis of osteoblasts (OBs), and promote osteogenic differentiation. In summary, NAR could hinder the pyroptosis of OBs caused by SMG and promote osteogenic differentiation via activating the Nrf2/HO-1 pathway. This provides a unique view for inhibiting bone loss under weightlessness and confirms the NAR capacity in treating microgravity-stimulated bone loss, giving new ideas and methods for future space medicine development.

Calycosin prevents bone loss induced by hindlimb unloading

Bone loss induced by microgravity exposure seriously endangers the astronauts' health, but its countermeasures still have certain limitations. The study aims to find potential protective drugs for the prevention of the microgravity-induced bone loss. Here, we utilized the network pharmacology approach to discover a natural compound calycosin by constructing the compound-target interaction network and analyzing the topological characteristics of the network. Furthermore, the hind limb unloading (HLU) rats' model was conducted to investigate the potential effects of calycosin in the prevention of bone loss induced by microgravity. The results indicated that calycosin treatment group significantly increased the bone mineral density (BMD), ameliorated the microstructure of femoral trabecular bone, the thickness of cortical bone and the biomechanical properties of the bone in rats, compared that in the HLU group. The analysis of bone turnover markers in serum showed that both the bone formation markers and bone resorption markers decreased after calycosin treatment. Moreover, we found that bone remodeling-related cytokines in serum including IFN-γ, IL-6, IL-8, IL-12, IL-4, IL-10 and TNF-α were partly recovered after calycosin treatment compared with HLU group. In conclusion, calycosin partly recovered hind limb unloading-induced bone loss through the regulation of bone remodeling. These results provided the evidence that calycosin might play an important role in maintaining bone mass in HLU rats, indicating its promising application in the treatment of bone loss induced by microgravity.

Using real-world evidence for pharmacovigilance and drug safety-related decision making by a resource-limited health authority: 10 years of experience in Taiwan

PURPOSE

Real-world evidence has become increasingly relevant in regulatory decision making. Compared to large regulatory bodies, the national pharmacovigilance system in Taiwan is still under development, and the aim of this study is to demonstrate how a resource-limited health authority utilizes real-world evidence in decision making.

METHODS

We described different sources of real-world data available in Taiwan and illustrated the structural framework that integrates real-world evidence into Taiwan's national pharmacovigilance system. Additionally, we reviewed real-world studies conducted in the past 10 years and provided examples to show how these studies influenced drug safety-related decision making in Taiwan.

RESULTS

During the past 10 years, real-world evidence used when making drug safety-related regulatory decisions in Taiwan was mainly generated from nationwide claims databases, but other sources of real-world data, such as national registries and large electronic hospital databases, also became available recently. Different types of real-world evidence, including drug utilization studies, risk evaluation studies, and risk minimization measure evaluation studies, have been used to support regulatory decisions in Taiwan.

CONCLUSIONS

Through collaborations between the government and academics, Taiwan has started to integrate real-world evidence into the national pharmacovigilance system. However, future efforts, including linkages between different sources of real-world data and improvements in procedural and methodological practices, are needed to generate more regulatory-quality real-world evidence.

Novel insights into the complex architecture of osteoporosis molecular genetics

Osteoporosis is a prevalent osteodegenerative disease and silent killer linked to a decrease in bone mass and decline of bone microarchitecture, due to impaired bone matrix mineralization, raising the risk of fracture. Nevertheless, the process of bone matrix mineralization is still an unsolved mystery. Osteoporosis is a polygenic disorder associated with genetic and environmental risk factors; however, the majority of genes associated with osteoporosis remain largely unknown. Several signaling pathways regulate bone mass; therefore, dysregulation of a single signaling pathway leads to metabolic bone disease owing to high or low bone mass. Parathyroid hormone, core-binding factor α-1 (Cbfa1), Wnt/β-catenin, the receptor activator of the nuclear factor kappa-B (NF-κB) ligand (RANKL), myostatin, and osteogenic exercise signaling pathways play pivotal roles in the regulation of bone mass. The myostatin signaling pathway increases bone resorption by activating the RANKL signaling pathway, whereas osteogenic exercise inhibits myostatin and sclerostin while inducing irisin that consequentially activates the Cbfa1 and Wnt/β-catenin bone formation pathways. The aims of this review are to summarize what is known about osteoporosis-related signaling pathways; define the role of these pathways in osteoporosis drug discovery; focus light on the link between bone, muscle, pancreas, and adipose integrative physiology and osteoporosis; and underline the emerging role of osteogenic exercise in the prevention of, and care for, osteoporosis, obesity, and diabetes.

Inhibition of JNK and activation of the AMPK-Nrf2 axis by corosolic acid suppress osteolysis and oxidative stress

The intracellular reactive oxygen species contribute to RANKL-induced osteoclastogenesis and osteolysis. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a redox-sensitive transcription factor, is critical in the cellular defense against oxidative stress by induction of antioxidants and cytoprotective enzymes. In the current study, it was first demonstrated that RANKL-induced osteoclastogenesis and hydroxylapatite resorption were suppressed by Corosolic acid (CA) via inhibiting p-JNK and activating p-AMPK. Meanwhile, p-65, p-38, Akt, and GSK-3β were partly inhibited during the treatment of CA. Osteoclastogenesis related genes, including NFATc1, c-fos, cathepsin K, and CTR were down-regulated by CA as well. Furthermore, the intracellular oxidative stress of CA-treated osteoclasts was dramatically decreased and Nrf2 was translocated into the nucleus to activate antioxidants including HO-1, NQO-1, and GCLC by CA. The LPS-induced mice calvarial osteolysis model was established for the in vivo investigation. Micro-CT morphometric analysis revealed that the treatment of CA restored LPS-induced bone loss and formation of osteoclasts. Besides, p-p65 and p-JNK were activated in the LPS group but inhibited by CA in vivo. The treatment of CA also activated p-AMPK during its attenuating LPS-induced osteolysis. Conclusively, CA effectively protects against LPS-induced osteolysis by suppressing osteoclastogenesis and oxidative stress through the inhibition of the JNK and activation of the AMPK-Nrf2 axis.

Glycyrrhizin Suppresses RANKL-Induced Osteoclastogenesis and Oxidative Stress Through Inhibiting NF-κB and MAPK and Activating AMPK/Nrf2

The treatment for osteoporosis involves inhibiting bone resorption and osteoclastogenesis. Glycyrrhizin (GLY) is a triterpenoid saponin glycoside known to be as the most medically efficacious component of the licorice plant. It has strong anti-inflammatory, antioxidant, and antitumor properties. We investigated the effect of GLY on osteoclastogenesis, bone resorption, and intracellular oxidative stress and its molecular mechanisms. In vitro osteoclastogenesis assays were performed using bone marrow monocytes with and without glycyrrhizin. We also evaluated the effects of glycyrrhizin on the secretion of TNF-α, IL-1β, and IL-6 in LPS-stimulated RAW 264.7 cells using ELISA. The effects of glycyrrhizin on the expression of osteoclast-related genes, such as Nfatc1, c-fos, Trap, and cathepsin K (CK), were investigated by RT-PCR. Intracellular reactive oxygen species (ROS) were detected in receptor activator of nuclear factor kappa-Β ligand (RANKL)-stimulated osteoclasts in the presence and absence of glycyrrhizin. During the inhibition of osteoclastogenesis by glycyrrhizin, phosphorylation of AMPK, Nrf2, NF-κB, and MAPK was analyzed using western blotting. Our results showed that glycyrrhizin significantly inhibited RANKL-induced osteoclastogenesis, downregulated the expression of NFATc1, c-fos, TRAP, CK, DC-STAMP, and OSCAR, and inhibited p65, p38, and JNK. Glycyrrhizin was found to significantly decrease the secretion of inflammatory cytokines (TNF-α, IL-1β, and IL-6). Additionally, glycyrrhizin reduced the formation of ROS in osteoclasts by inducing AMPK phosphorylation and nuclear transfer of NRF2, resulting in an upregulation of antioxidant enzymes, such as HO-1, NQO-1, and GCLC. In summary, we found that glycyrrhizin inhibited RANKL-induced osteoclastogenesis. It was also indicated that glycyrrhizin could reduce oxidative stress by inhibiting the MAPK and NF-κB pathways and activating the AMPK/NRF2 signaling. Therefore, glycyrrhizin may be used as an effective therapeutic agent against osteoporosis and bone resorption.