Osteoclast-Associated Receptor (OSCAR) Distribution in the Synovial Tissues of Patients with Active RA and TNF-α and RANKL Regulation of Expression by Osteoclasts In Vitro

The predictive value of soluble osteoclast-associated receptor for the prognosis of acute coronary syndrome

At present, prognostic biomarkers of acute coronary syndrome (ACS) are fewer. The aim of this study was to explore the predictive value of soluble osteoclast-associated receptor (sOSCAR) level for the major adverse cardiovascular events (MACE) occurring within 30 days after ACS. From January to August 2020, a total of 108 patients with ACS who were admitted to our hospital, were enrolled in this study. Of the 108 patients, 79 were men and 29 women. Patient-related data, including age, sex, body mass index, history of type 2 diabetes, history of hyperlipidemia and serum sOSCAR level, were collected. All patients were followed up for 30 days. Based on MACE occurrence, the 108 patients were divided into MACE group (n = 17) and non-MACE group (n = 91). The baseline data were compared between the two groups, MACE-independent risk factors were identified by multivariate regression analysis, and the predictive value of sOSCAR for MACE occurring within 30 days after CAS was analyzed using receiver operating characteristic (ROC) curve. At the same time, according to the type of ACS, the 108 patients with ACS were divided into unstable angina (UA) group (n = 29), non ST-segment elevation myocardial infarction (USTEMI) group (n = 45) and ST-segment elevation myocardial infarction (STEMI) group (n = 34), and then the sOSCAR level and MACE incidence were observed in each group. The serum sOSCAR level was significantly lower in the MACE group [130(100,183)] than in the non-MACE group [301(220,370)] (P = 0.000). The area under ROC curve of sOSCAR level for MACE occurring within 30 days after CAS was 0.860 with 95%CI 0.782–0.919, P < 0.001. Multivariate regression analysis indicated that the sOSCAR level was an independent risk factor for the MACE occurring within 30 days after CAS (OR 0.26, 95%CI 0.087–0.777, P = 0.04). The MACE incidence (0%) was the lowest but the sOSCAR level was the highest in the UA group, while in the STEMI group, the MACE incidence (23.53%) was the higest but the sOSCAR level was the lowest among the UA, STEMI and NSTEMI groups. Serum sOSCAR level may be used as a predictor of MACE occurring within the short-term after ACS. The higher the sOSCAR level, the lower the MACE incidence.

Tumour necrosis factor-α promotes BMHSC differentiation by increasing P2X7 receptor in oestrogen-deficient osteoporosis

The exact mechanism of tumour necrosis factor α (TNF‐α) promoting osteoclast differentiation is not completely clear. A variety of P2 purine receptor subtypes have been confirmed to be widely involved in bone metabolism. Thus, the purpose of this study was to explore whether P2 receptor is involved in the differentiation of osteoclasts. Mouse bone marrow haematopoietic stem cells (BMHSCs) were co‐cultured with TNF‐α to explore the effect of TNF‐α on osteoclast differentiation and bone resorption capacity in vitro, and changes in the P2 receptor were detected at the same time. The P2 receptor was silenced and overexpressed to explore the effect on differentiation of BMHSCs into osteoclasts. In an in vivo experiment, the animal model of PMOP was established in ovariectomized mice, and anti‐TNF‐α intervention was used to detect the ability of BMHCs to differentiate into osteoclasts as well as the expression of the P2 receptor. It was confirmed in vitro that TNF‐α at a concentration of 20 ng/mL up‐regulated the P2X7 receptor of BMHSCs through the PI3k/Akt signalling pathway, promoted BMHSCs to differentiate into a large number of osteoclasts and enhanced bone resorption. In vivo experiments showed that more P2X7 receptor positive osteoclasts were produced in postmenopausal osteoporotic mice. Anti‐TNF‐α could significantly delay the progression of PMOP by inhibiting the production of osteoclasts. Overall, our results revealed a novel function of the P2X7 receptor and suggested that suppressing the P2X7 receptor may be an effective strategy to delay bone formation in oestrogen deficiency‐induced osteoporosis.

The Antiosteoporosis Effects of Yishen Bugu Ye Based on Its Regulation on the Differentiation of Osteoblast and Osteoclast

Yishen Bugu Ye (YSBGY), a traditional Chinese medicine comprising 12 types of medicinal herbs, is often prescribed in China to increase bone strength. In this study, the antiosteoporotic effects of YSBGY were investigated in C57BL/6 mice afflicted with dexamethasone- (Dex-) induced osteoporosis (OP). The results showed that YSBGY reduced the interstitial edema in the liver and kidney of mice with Dex-induced OP. It also increased the number of trabecular bone elements and chondrocytes in the femur, promoted cortical bone thickness and trabecular bone density, and modulated the OP-related indexes in the femur and tibia of OP mice. It also increased the serum concentrations of type I collagen, osteocalcin, osteopontin, bone morphogenetic protein-2, bone morphogenetic protein receptor type 2, C-terminal telopeptide of type I collagen, and runt-related transcription factor-2 and reduced those of tartrate-resistant acid phosphatase 5 and nuclear factor of activated T cells in these mice, suggesting that it improved osteoblast differentiation and suppressed osteoclast differentiation. The anti-inflammatory effect of YSBGY was confirmed by the increase in the serum concentrations of interleukin- (IL-) 33 and the decrease in concentrations of IL-1, IL-7, and tumor necrosis factor-α in OP mice. Furthermore, YSBGY enhanced the serum concentrations of superoxide dismutase and catalase in these mice, indicating that it also exerted antioxidative effects. This is the first study to confirm the antiosteoporotic effects of YSBGY in mice with Dex-induced OP, and it showed that these effects may be related to the YSBGY-induced modulation of the osteoblast/osteoclast balance and serum concentrations of inflammatory factors. These results provide experimental evidence supporting the use of YSBGY for supporting bone formation in the clinical setting.

Correlations of soluble osteoclast-associated receptor (sOSCAR) with acute coronary syndrome

Background

An osteoclast-associated receptor (OSCAR) is an immunoglobulin receptor expressed in an osteoclast, and takes part in the formation of an osteoclast. While the soluble OSCAR (sOSCAR) component is reported to be involved in the pathogenesis of arteriosclerosis, the aim of this present study is to investigate the relationship between sOSCAR and acute coronary syndrome (ACS).

Methods

This study enrolled 41 patients with ACS and 33 patients without ACS as a control, from March 2017 to June 2017. The baseline clinical parameters and serum levels of sOSCAR were collected in the participants. The univariate and multivariate logistic regressions were applied to explore the independent association of sOSCAR with ACS. A receiver operating characteristic (ROC) curve was applied to explore the ability of sOSCAR to indicate ACS.

Results

The results showed that the levels of sOSCAR in the patients with ACS was lower than the patients without ACS (P=0.005). The multivariate logistic regression tests demonstrated that a decreased sOSCAR level was independently associated with the presence of ACS (OR: 0.174, 95% CI: 0.047-0.638, P=0.008). ROC analysis showed that the optimal sOSCAR cut-off value for the indication of ACS was <110.87 pg/mL, the corresponding sensitivity was 65.85%, and the specificity was 69.70%.

Conclusions

The decreased levels of sOSCAR are independently associated with the presence of ACS. sOSCAR could then be considered as a potential biomarker for the prediction of ACS.

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.

Modulating calcium-mediated NFATc1 and mitogen-activated protein kinase deactivation underlies the inhibitory effects of kavain on osteoclastogenesis and bone resorption

Osteoclasts are responsible for bone resorption during the process of bone remodeling. Increased osteoclast numbers and bone resorption activity are the main factors contributing to bone loss-related diseases such as osteoporosis. Therefore, modulating the formation and function of osteoclasts is critical for the effective treatment of osteolysis and osteoporosis. Kavain is the active ingredient extracted from the root of the kava plant, which possesses known anti-inflammatory properties. However, the effects of kavain on osteoclastogenesis and bone resorption remain unclear. In this study, we found that kavain inhibits receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and fusion using tartrate-resistant acid phosphatase staining and immunofluorescence. Furthermore, kavain inhibited bone resorption performed by osteoclasts. Using reverse transcription-polymerase chain reaction and western blot analysis, we found that kavain downregulates the expression of osteoclast marker genes, such as nuclear factor of activated T cells, cytoplasmic 1 (Nfatc1), v-atpase d2 (Atp6v0d2), dendrocyte expressed seven transmembrane protein (Dcstamp), matrix metallopeptidase 9 (Mmp9), cathepsin K (Ctsk), and Acp5. Additionally, kavain repressed RANKL-induced calcium oscillations, nuclear factor of activated T cells activation, and mitogen-activated protein kinase phosphorylation, while leaving NF-κB unaffected. We found no effects of kavain on either osteoblast proliferation or differentiation. Besides, kavain inhibited bone loss in ovariectomized mice by suppressing osteoclastogenesis. Collectively, these data suggest a potential use for kavain as a candidate drug for the treatment of osteolytic diseases.

Nicorandil and theophylline can protect experimental rats against complete Freund's adjuvant-induced rheumatoid arthritis through modulation of JAK/STAT/RANKL signaling pathway

Signaling pathways are interesting fields of study of pathogenesis and treatment trials. We elucidated the possible protective effects of nicorandil (15mg/kg/day) and theophylline (20mg/kg/day) on experimentally-induced RA, focusing on the role of JAK (Janus Kinase) / STAT (Signal Transducer and Activator of Transcription) / RANKL (Receptor Activator of Nuclear factor-Kappa B Ligand) / cytokine signaling pathway. Four sets of experiments were performed. First, effect of test agents on normal animals was evaluated. Second, effect of test agents was evaluated on Complete Freund's Adjuvant (CFA; 0.3ml, s.c.)-induced RA to investigate anti-arthritic effect. Third, effect of test agents was evaluated on growth hormone (GH; 2mg/kg/day, s.c.)-induced stimulation of JAK/STAT/RANKL/cytokine signaling pathway to investigate the role of this signaling pathway in their anti-arthritic effect. Fourth, the effect of test agents was performed on CFA/GH-induced RA. To fulfill this purpose, serum anti-citrullinated peptide antibody (ACPA), interleukin-6 (IL-6), and cartilage oligomeric matrix protein (COMP), together with tissue JAK2, STAT3, RANKL, inducible and endothelial nitric oxide synthases (iNOS and eNOS) as well as macrophage inflammatory protein (MIP_1α) were estimated using ELISA, Western blotting and PCR techniques, confirmed by a histopathological study. Test agents significantly corrected JAK2, STAT3, RANKL and IL-6 values in animals receiving GH. Additionally, test agents could correct ACPA, IL-6, COMP, JAK2, STAT3, RANKL, iNOS, eNOS and MIP_1α levels compared with the respective CFA or CFA/GH controls. These results conclude that nicorandil and theophylline have good anti-arthritic effects related to modulation of JAK/STAT/RANKL signaling pathway. Further clinical trials are claimed.