Anti-Osteoporotic Effects of n-trans-Hibiscusamide and Its Derivative Alleviate Ovariectomy-Induced Bone Loss in Mice by Regulating RANKL-Induced Signaling

Bone marrow mesenchymal stem cells overexpressing stromal cell- derived factor 1 aid in bone formation in osteoporotic mice

BACKGROUND

Osteoporosis is characterized by low systemic bone mineral content and destruction of bone microarchitecture. Promoting bone regeneration and reversing its loss by infusion of exogenous bone marrow mesenchymal stem cells (BMSCs) is a potentially effective treatment for osteoporosis. However, their limited migration to target organs reduces the therapeutic effect of the cells. Stromal cell-derived factor 1 (SDF1) is a chemokine that induces targeted cell migration through the SDF1/CXCR4 (C-X-C chemokine receptor 4) axis and can induce migration of exogenous mesenchymal stem cells to sites of high SDF1 concentration. There are no studies on BMSCs overexpressing SDF1 (SDF1-BMSCs) in osteoporotic mice in vivo. We aimed to investigate if the increased SDF1 concentration facilitated cell migration to the bone.

METHODS

We used lentivirus to construct BMSCs overexpressing SDF1 or knocking down CXCR4. We verified the proliferation ability of the cells in vitro using Cell Counting Kit-8 (CCK8) and 5-Bromodeoxyuridinc (BrdU), the migration ability of the cells using Transwell, and the osteogenic and lipogenic ability of the cells using osteogenic and lipogenic induction solutions. In in vivo experiments, we induced osteoporosis in 72 female mice by ovariectomy and injected different groups of cells via the tail vein. Femoral tissue samples were collected for a fixed time, and the osteogenic and homing abilities of the cells were verified by MicroCT and tissue section staining.

RESULTS

We successfully demonstrated that high expression of SDF1 promoted cell proliferation and migration in vitro, without affecting their cell differentiation ability. In an ovariectomized mouse model, SDF1-BMSCs were more likely to be home to the femur than the BMSCs, had a better pro-osteogenic ability, and had higher expression of Wnt-1. Blocking the SDF1/CXCR4 axis reduced the homing of exogenous mesenchymal stem cells (MSCs) to the femur and their osteogenic capacity.

CONCLUSIONS

SDF1-BMSCs can further promote bone formation by increasing the number of cells homing to the femur in osteoporotic mice. Our study shows that stem cells can promote their proliferation and home to the femur via the SDF1/CXCR4 axis and further help bone formation via Wnt-1 signaling.

Correlation of serum anti-Mullerian hormone and Inhibin-B levels with osteoporosis of menopausal woman in Chinese Daur ethnic group

PURPOSE

To investigate the diagnostic value of anti-Mullerian hormone (AMH) and Inhibin B (InhB) in menopausal women with osteoporosis from the Chinese Daur ethnic group.

METHODS

A total of 175 menopausal women were selected and divided into the osteoporosis group (N = 90) and the control group (N = 85). BMD was measured by dual-energy X-ray absorptiometry, and laboratory indicators of osteoporosis, for example, serum osteocalcin (OC), β-collagen special sequence (β-CTX), and procollagen type I amino-terminal propeptide (PINP), bone alkaline phosphatase (BALP), AMH, and InhB were measured by commercial kits. The relationship between osteoporosis and AMH or InhB was analyzed. The predictive values of AMH and InhB were reflected by the ROC curve and logistic regression.

RESULTS

The level of BMD was decreased and the levels of OC, β-CTX, PINP, and BALP of the menopausal osteoporosis group were increased. The concentration of AMH and InhB in the menopausal osteoporosis group was decreased and they had connections with each other. AMH and InhB could be used as independent indicators for the occurrence of osteoporosis in menopausal women and their combination had a higher diagnostic value.

CONCLUSION

AMH and InhB measurements in menopausal women had a certain clinical significance in the detection of osteoporosis. The occurrence of osteoporosis was related to BMD, OC, β-CTX, BALP, AMH, and InhB.

The role of melatonin in the development of postmenopausal osteoporosis

Melatonin is an important endogenous hormone that modulates homeostasis in the microenvironment. Recent studies have indicated that serum melatonin levels are closely associated with the occurrence and development of osteoporosis in postmenopausal women. Exogenous melatonin could also improve bone mass and increase skeletal strength. To determine the underlying mechanisms of melatonin in the prevention and treatment of postmenopausal osteoporosis, we performed this review to analyze the role of melatonin in bone metabolism according to its physiological functions. Serum melatonin is related to bone mass, the measurement of which is a potential method for the diagnosis of osteoporosis. Melatonin has a direct effect on bone remodeling by promoting osteogenesis and suppressing osteoclastogenesis. Melatonin also regulates the biological rhythm of bone tissue, which benefits its osteogenic effect. Additionally, melatonin participates in the modulation of the bone microenvironment. Melatonin attenuates the damage induced by oxidative stress and inflammation on osteoblasts and prevents osteolysis from reactive oxygen species and inflammatory factors. As an alternative drug for osteoporosis, melatonin can improve the gut ecology, remodel microbiota composition, regulate substance absorption and maintain metabolic balance, all of which are beneficial to the health of bone structure. In conclusion, our review systematically demonstrates the effects of melatonin on bone metabolism. Based on the evidence in this review, melatonin will play a more important role in the diagnosis, prevention and treatment of postmenopausal osteoporosis.

Tereticornate A suppresses RANKL-induced osteoclastogenesis via the downregulation of c-Src and TRAF6 and the inhibition of RANK signaling pathways

Excessive osteoclast differentiation and activation are closely associated with the development and progression of osteoporosis. Natural plant-derived compounds that can inhibit osteoclastogenesis are an efficient strategy for the prevention and treatment of osteoporosis. Tereticornate A (TA) is a natural terpene ester compound extracted from the leaves and branches of Eucalyptus gracilis, with antiviral, antibacterial, and anti-inflammatory activities. However, the effect of TA on osteoclastogenesis and the underlying molecular mechanism remain unclear. Based on the key role of the NF-κB pathway in the regulation of osteoclastogenesis and the observation that TA exhibits an anti-inflammatory effect by inhibiting NF-κB activity, we speculated that TA could exert anti-osteoclastogenesis activity. Herein, TA could inhibit the RANKL-induced osteoclast differentiation and formation of F-actin rings in RAW 264.7 cells. Mechanistically, TA downregulated the expression of c-Src and TRAF6, and also suppressed the RANKL-stimulated canonical RANK signaling pathways, including AKT, MAPK (p38, JNK, and ERK), and NF-κB; ultimately, downregulating the expression of NFATc1 and c-Fos, the key transcriptional factors required for the expression of genes (e.g., TRAP, cathepsin K, β-Integrin, MMP-9, ATP6V0D2, and DC-STAMP) that govern osteoclastogenesis. Our findings demonstrated that TA could effectively inhibit RANKL-induced osteoclastogenesis via the downregulation of c-Src and TRAF6 and the inhibition of RANK signaling pathways. Thus, TA could serve as a novel osteoclastogenesis inhibitor and might have beneficial effects on bone health.