Magnesium Lithospermate B Protects against Lipopolysaccharide-Induced Bone Loss by Inhibiting RANKL/RANK Pathway

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

Alkaline earth metals for osteogenic scaffolds: From mechanisms to applications

Regeneration of bone defects is a significant challenge today. As alternative approaches to the autologous bone, scaffold materials have remarkable features in treating bone defects; however, the various properties of current scaffold materials still fall short of expectations. Due to the osteogenic capability of alkaline earth metals, their application in scaffold materials has become an effective approach to improving their properties. Furthermore, numerous studies have shown that combining alkaline earth metals leads to better osteogenic properties than applying them alone. In this review, the physicochemical and physiological characteristics of alkaline earth metals are introduced, mainly focusing on their mechanisms and applications in osteogenesis, especially magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Furthermore, this review highlights the possible cross-talk between pathways when alkaline earth metals are combined. Finally, some of the current drawbacks of scaffold materials are enumerated, such as the high corrosion rate of Mg scaffolds and defects in the mechanical properties of Ca scaffolds. Moreover, a brief perspective is also provided regarding future directions in this field. It is worth exploring that whether the levels of alkaline earth metals in newly regenerated bone differs from those in normal bone. The ideal ratio of each element in the bone tissue engineering scaffolds or the optimal concentration of each elemental ion in the created osteogenic environment still needs further exploration. The review not only summarizes the research developments in osteogenesis but also offers a direction for developing new scaffold materials.

Lipopolysaccharide-Induced Bone Loss in Rodent Models: A Systematic Review and Meta-Analysis

Osteoporosis has traditionally been characterized by underlying endocrine mechanisms, though evidence indicates a role of inflammation in its pathophysiology. Lipopolysaccharide (LPS), a component of gram-negative bacteria that reside in the intestines, can be released into circulation and stimulate the immune system, upregulating bone resorption. Exogenous LPS is used in rodent models to study the effect of systemic inflammation on bone, and to date a variety of different doses, routes, and durations of LPS administration have been used. The study objective was to determine whether systemic administration of LPS induced inflammatory bone loss in rodent models. A systematic search of Medline and four other databases resulted in a total of 110 studies that met the inclusion criteria. Pooled standardized mean differences (SMDs) and corresponding 95% confidence intervals (CI) with a random-effects meta-analyses were used for bone volume fraction (BV/TV) and volumetric bone mineral density (vBMD). Heterogeneity was quantified using the I² statistic. Shorter-term (<2 weeks) and longer-term (>2 weeks) LPS interventions were analyzed separately because of intractable study design differences. BV/TV was significantly reduced in both shorter-term (SMD = -3.79%, 95% CI [-4.20, -3.38], I² 62%; p < 0.01) and longer-term (SMD = -1.50%, 95% CI [-2.00, -1.00], I² 78%; p < 0.01) studies. vBMD was also reduced in both shorter-term (SMD = -3.11%, 95% CI [-3.78, -2.44]; I² 72%; p < 0.01) and longer-term (SMD = -3.49%, 95% CI [-4.94, -2.04], I² 82%; p < 0.01) studies. In both groups, regardless of duration, LPS negatively impacted trabecular bone structure but not cortical bone structure, and an upregulation in bone resorption demonstrated by bone cell staining and serum biomarkers was reported. This suggests systemically delivered exogenous LPS in rodents is a viable model for studying inflammatory bone loss, particularly in trabecular bone. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Functionalization of TiO2 for Better Performance as Orthopedic Implants

This review mainly focuses on the surface functionalization approaches of titanium dioxide (TiO₂) to prevent bacterial infections and facilitate osteointegration simultaneously for titanium (Ti)-based orthopedic implants. Infection is one of the major causes of implant failure. Meanwhile, it is also critical for the bone-forming cells to integrate with the implant surface. TiO₂ is the native oxide layer of Ti which has good biocompatibility as well as enriched physical, chemical, electronic, and photocatalytic properties. The formed nanostructures during fabrication and the enriched properties of TiO₂ have enabled various functionalization methods to combat the micro-organisms and enhance the osteogenesis of Ti implants. This review encompasses the various modifications of TiO₂ in aspects of topology, drug loading, and element incorporation, as well as the most recently developed electron transfer and electrical tuning approaches. Taken together, these approaches can endow Ti implants with better bactericidal and osteogenic abilities via the functionalization of TiO₂.

Yangonin treats inflammatory osteoporosis by inhibiting the secretion of inflammatory factors and RANKL expression

OBJECTIVES

As the main cause of osteoporosis, abnormal activity of osteoclasts could disrupt the balance between bone resorption and formation. Moreover, up-regulation of nuclear factor-kappa ligand (RANKL) expression by chronic inflammation-mediated inflammatory factors might contribute to the differentiation of osteoclast precursor cells. Therefore, an anti-inflammatory agent named yangonin was presented for inhibiting osteoclast and relieving inflammatory osteoporosis through down-regulating inflammatory factors.

METHODS

We established a model of macrophage inflammation and then verified the anti-inflammatory effect of yangonin. The inhibitory effect of yangonin on osteoclasts was detected by tartrate-resistant acid phosphatase (TRAP) staining, Western blotting and quantitative real-time PCR (qRT-PCR). Finally, micro-CT, TRAP and hematoxylin-eosin (HE) staining were used to show the effect of yangonin on inflammatory osteoporosis in vivo.

RESULTS

Our results suggested that yangonin was able to reduce the secretion of inflammatory factors, down-regulate osteoclast-related genes such as TRAP, RANKL, cathepsin K (CTSK) and nuclear factor-activated T-cell 1 (NFATc1). Furthermore, it was demonstrated that yangonin could suppress the function of inflammatory cytokines in osteoclast differentiation and reporting, wherein NF-κB, AKT and downstream c-Fos/NFATc1 signaling pathways were involved. In an in vivo study, we implied that yangonin has a relieving effect on inflammatory osteoporosis.

CONCLUSION

Our research shows that yangonin down-regulates inflammatory factors and inhibits the bone-breaking effect of inflammation through NF-κB, AKT and downstream c-Fos/NFATc1 signaling pathways to achieve the purpose of treating inflammatory osteoporosis.

Heat-Killed Lacticaseibacillus paracasei GMNL-653 Exerts Antiosteoporotic Effects by Restoring the Gut Microbiota Dysbiosis in Ovariectomized Mice

Osteoporosis is a metabolic inflammatory disease, an imbalance occurs between bone resorption and formation, leading to bone loss. Anti-inflammatory diet is considered having the potential to ameliorate osteoporosis. Heat-killed probiotics exhibit health benefits in relation to their immunomodulatory effects, but the detail mechanism involved in gut microbiota balance, host metabolism, immunity, and bone homeostasis remains unclear. In this study, we evaluated the antiosteoporotic effects of heat-killed Lacticaseibacillus paracasei GMNL-653 in vitro and in ovariectomized (OVX) mice. Furthermore, whole-genome sequencing and comparative genomics analysis demonstrated potentially genes involved in antiosteoporotic activity. The GMNL-653 exerts anti-inflammatory activity which restored gut microbiota dysbiosis and maintained intestinal barrier integrity in the OVX mice. The levels of IL-17 and LPS in the sera decreased following GMNL-653 treatment compared with those of the vehicle control; mRNA levels of RANKL were reduced and TGF-β and IL-10 enhanced in OVX-tibia tissue after treatment. The levels of IL-17 were significantly associated with gut microbiota dysbiosis. Gut microbial metagenomes were further analyzed by PICRUSt functional prediction, which reveal that GMNL-653 intervention influence in several host metabolic pathways. The analysis of whole-genome sequencing accompanied by comparative genomics on three L. paracasei strains revealed a set of GMNL-653 genes that are potentially involved in antiosteoporotic activity. Our findings validated antiosteoporotic activity of heat-killed GMNL-653 using in vitro and in vivo models, to whole-genome sequencing and identifying genes potentially involved in this gut microbiota–bone axis.

Magnesium Picolinate Improves Bone Formation by Regulation of RANK/RANKL/OPG and BMP-2/Runx2 Signaling Pathways in High-Fat Fed Rats

Magnesium (Mg) deficiency may affect bone metabolism by increasing osteoclasts, decreasing osteoblasts, promoting inflammation/oxidative stress, and result in subsequent bone loss. The objective of the present study was to identify the molecular mechanism underlying the bone protective effect of different forms of Mg (inorganic magnesium oxide (MgO) versus organic magnesium picolinate (MgPic) compound) in rats fed with a high-fat diet (HFD). Forty-two Wistar albino male rats were divided into six group (n = 7): (i) control, (ii) MgO, (iii) MgPic, (iv) HFD, (v) HFD + MgO, and (vi) HFD + MgPic. Bone mineral density (BMD) increased in the Mg supplemented groups, especially MgPic, as compared with the HFD group (p < 0.001). As compared with the HFD + MgO group, the HFD + MgPic group had higher bone P (p < 0.05) and Mg levels (p < 0.001). In addition, as compared to MgO, MgPic improved bone formation by increasing the levels of osteogenetic proteins (COL1A1 (p < 0.001), BMP2 (p < 0.001), Runx2 (p < 0.001), OPG (p < 0.05), and OCN (p < 0.001), IGF-1 (p < 0.001)), while prevented bone resorption by reducing the levels of RANK and RANKL (p < 0.001). In conclusion, the present data showed that the MgPic could increase osteogenic protein levels in bone more effectively than MgO, prevent bone loss, and contribute to bone formation in HFD rats.

Tablysin-15 inhibits osteoclastogenesis and LPS-induced bone loss via attenuating the integrin αvβ3 pathway

Excessive osteoclast leads to the imbalance in bone reconstruction and results in osteolytic diseases, such as osteoporosis and rheumatic arthritis. Integrin α_vβ₃ abundantly expresses on osteoclast and plays a critical role in the formation and function of osteoclast, therefore, blockage of α_vβ₃ has become an attractive therapeutic option for osteolytic diseases. In this study, we find that Tablysin-15, a RGD motif containing disintegrin, concentration-dependently suppresses RANKL-induced osteoclastogenesis, F-actin ring formation and bone resorption without affecting the cell viabilities. Tablysin-15 binds to integrin α_vβ₃ and inhibits the activation of FAK-associated signaling pathways. Tablysin-15 also suppresses the activation of NF-кB, MAPK, and Akt-NFATc1 signaling pathways, which are crucial transcription factors during osteoclast differentiation. Moreover, Tablysin-15 decreases the osteoclastogenesis marker gene expression, including MMP-9, TRAP, CTSK, and c-Src. Finally, Tablysin-15 significantly inhibits LPS-induced bone loss in a mouse model. Taken together, our results indicate that Tablysin-15 significantly suppresses osteoclastogenesis in vitro and in vivo, thus it might be a excellent candidate for treating osteolytic-related diseases.

Desalted duck egg white peptides promoted osteogenesis via wnt/β-catenin signal pathway

Osteoporosis is a degenerative disease that threatens bone health of the elderly (especially postmenopausal women). Since osteoporosis is important to prevent, the aim of this study was to investigate the regulation of desalted duck egg white peptides (DPs) on osteoporosis. In this study, the effects of DPs on bone formation were evaluated using MC3T3-E1 cells and ovariectomized (OVX) rats. DPs significantly enhanced the preosteoblasts proliferation, differentiation, and matrix mineralization via the upregulation of wnt3a expression, low-density lipoprotein receptor-related protein-5 (LRP-5), β-catenin, runt-related transcription factor 2 (Runx2), and osteoprotegerin (OPG) (P < 0.05). The intracellular calcium concentration was significantly elevated by DPs (P < 0.05), which is attributed to calcium influx and L-type calcium channels. Additionally, OVX rat model experiment indicated that DPs (600 mg/kg bw) had a superior effect against bone loss induced by estrogen deficiency, as it significantly declined bone turnover markers, and significantly increased biomechanical parameters (P < 0.05). Mineralized bone surfaces and bone microstructure were also obviously improved by DPs treatment. Immunohistochemical analysis showed that receptor activator of nuclear factor κ B (RANK) expression of tibia in DPs group was significantly reduced compared with the model group (P < 0.05). Our results demonstrated that DPs could enhance preosteoblasts differentiation and antiosteoporosis via wnt/β-catenin signal pathway and several key osteogenic transcription factors such as Runx2 and OPG. PRACTICAL APPLICATION: High-value utilization of salted duck egg white, a byproduct of food industry, is worthy of in-depth study. Desalted duck egg white peptides (DPs) were proved to promote bone formation, which suggests the potentials of DPs as cofactors in osteoporosis prevention.

Magnesium lithospermate B inhibits titanium particles-induced osteoclast formation by c-fos and inhibiting NFATc1 expression

Purpose: Titanium particle-induced osteolysis is one of the important causes of aseptic loosening of artificial joints. Previous studies have shown the potential of natural compounds in preventing Ti particle-induced bone resorption. In this study, we observed the effects of magnesium lithospermate B (MLB) on titanium particle-induced osteoclast activity in vitro. Materials and Methods: RAW264.7 cells were treated with titanium particles (0.1 mg/mL) in the presence or absence of MLB (200 nmol/L). We evaluated the osteoclast formation, bone pits formation and tartrate-resistant acid phosphatase 5b (Tracp5b) levels. Reverse transcription polymerase chain reaction (RT-PCR) and Western blot were used to evaluate osteoclast differentiation-related genes (TRAF6, NFATc1, and c-fos) and protein expression. Results: The number of osteoclasts, pit formation and Tracp5b levels were all the group treated with titanium particles compared to the control group (all p < 0.05). Titanium particles also promoted the expression of the TRAF6, NFATc1 and c-fos genes and protein expression. MLB significantly abolished the titanium particle-enhanced osteoclast and pits formation, and Traf6, NFATc1, and c-fos expression. Conclusions: Our data demonstrated that MLB can suppress titanium-induced osteoclast activity via inhibiting c-fos and NFATc1 expression.

Stachydrine prevents LPS-induced bone loss by inhibiting osteoclastogenesis via NF-κB and Akt signalling

Osteoclast overactivation‐induced imbalance in bone remodelling leads to pathological bone destruction, which is a characteristic of many osteolytic diseases such as rheumatoid arthritis, osteoporosis, periprosthetic osteolysis and periodontitis. Natural compounds that suppress osteoclast formation and function have therapeutic potential for treating these diseases. Stachydrine (STA) is a bioactive alkaloid isolated from Leonurus heterophyllus Sweet and possesses antioxidant, anti‐inflammatory, anticancer and cardioprotective properties. However, its effects on osteoclast formation and function have been rarely described. In the present study, we found that STA suppressed receptor activator of nuclear factor‐κB (NF‐κB) ligand (RANKL)‐induced osteoclast formation and bone resorption, and reduced osteoclast‐related gene expression in vitro. Mechanistically, STA inhibited RANKL‐induced activation of NF‐κB and Akt signalling, thus suppressing nuclear factor of activated T cells c1 induction and nuclear translocation. In addition, STA alleviated bone loss and reduced osteoclast number in a murine model of LPS‐induced inflammatory bone loss. STA also inhibited the activities of NF‐κB and NFATc1 in vivo. Together, these results suggest that STA effectively inhibits osteoclastogenesis both in vitro and in vivo and therefore is a potential option for treating osteoclast‐related diseases.

Forsythiaside inhibited titanium particle-induced inflammation via the NF-κB signaling pathway and RANKL-induced osteoclastogenesis and titanium particle-induced periprosthetic osteolysis via JNK, p38, and ERK signaling pathways

Wear particle-induced periprosthetic osteolysis is the primary complication of the total joint replacement; however, no conservative treatment except for reversal surgery is available for this disease. During the past decade, Chinese herbal medicines have been widely investigated to inhibit osteoclast differentiation, which may exhibit the potential to treat wear particle-induced periprosthetic osteolysis. The present study was aimed at the investigation of the effects of forsythiaside on osteocytes. The current data revealed that the forsythiaside treatment notably inhibited the titanium (Ti) particle-induced inflammation through impaired NF-κB signaling, thereby inhibiting TNF-α and IL-1β. In addition, the in vitro study demonstrated that forsythiaside effectively prevented the RANKL-induced differentiation of osteoclasts and inhibited the expression of osteoclast-specific genes in osteoclasts via inhibition of the JNK signaling pathway. The in vivo study of Ti particle-induced implant-associated osteolysis indicated that forsythiaside could also inhibit osteoclastogenesis. In summary, forsythiaside could inhibit osteoclastogenesis and particle-induced inflammation, resulting in decreased secretion of inflammatory cytokines such as TNF-α and IL-1β. On the other hand, forsythiaside could inhibit RANKL-induced osteoclastogenesis and Ti particle-induced periprosthetic osteolysis via JNK, ERK and p38 signaling pathways. Both the abovementioned biofunctions of forsythiaside contributed to the implant-associated particle-induced osteolysis. Thus, forsythiaside can act as a candidate drug for the precaution of implant-associated particle-induced osteolysis.

Forsythiaside can act as a candidate drug for the precaution of implant-associated particle-induced osteolysis.

The renin-angiotensin system in the synovium promotes periarticular osteopenia in a rat model of collagen-induced arthritis

Periarticular osteopenia is the most specific hallmark of rheumatoid arthritis (RA). The renin-angiotensin system (RAS) in the synovium has been found to participate in the pathogenic process of RA. This study examined whether and how RAS regulates periarticular osteopenia in RA. The synovial tissues from patients with RA and osteoarthritis (OA) were prepared. Female Sprague-Dawley rats were treated with either saline, bovine type II collagen (CII) to induce arthritis (CIA), or CII combined with perindopril, an inhibitor of angiotensin-converting enzyme (ACE). Expressions of RAS components, including AT1R, AT2R and ACE, in human and rat synovial tissues were detected. Bone mass of rat joints was examined. Levels of RANKL, OPG and DKK-1 in rat synovium and expressions of TRAF6 and β-catenin in rat bone were examined. The results showed that AT1R, AT2R and ACE in human and rat synovium were up-regulated, but the increased ACE in rat synovial tissues was abrogated by perindopril. While CIA rats displayed increased bone resorption and decreased bone formation, perindopril treatment almost completely abrogated the RAS-mediated osteopenia, indicating that inhibition of ACE reduced the joint damages in rats. The expressions of RANKL and DKK-1 increased in CIA rats as compared with those in the control; TRAF6 was up-regulated and β-catenin was down-regulated in the bone tissues of CIA rats. The changes were then reversed by the use of perindopril. Our findings demonstrate that RAS in the synovium promotes periarticular osteopenia by increasing bone resorption and decreasing bone formation through modulating the RANKL/RANK/TRAF6 and Wnt/β-catenin pathways.

The Natural Product 6-Gingerol Inhibits Inflammation-Associated Osteoclast Differentiation via Reduction of Prostaglandin E₂ Levels

The natural product 6-gingerol, a major bioactive component of the rhizome of ginger (Zingiber officinale), is known to have several beneficial effects on health, including anti-inflammatory activity. The present study aimed to investigate the effects of 6-gingerol on osteoclast differentiation associated with inflammation. 6-Gingerol inhibited osteoclast differentiation in co-cultures of osteoblasts and osteoclast precursor cells in response to the pro-inflammatory cytokine, interleukin (IL)-1. However, it did not affect osteoclast precursor differentiation into osteoclasts induced by the receptor activator of nuclear factor-κB ligand (RANKL), a key cytokine causing osteoclast differentiation. 6-Gingerol inhibited IL-1-induced RANKL expression in osteoblasts, and the addition of RANKL to the co-cultures overcame 6-gingerol-mediated inhibition of osteoclast differentiation. It also suppressed IL-1-induced prostaglandin E₂ (PGE₂) production in osteoblasts, and the addition of exogenous PGE₂ reversed 6-gingerol-mediated inhibition of IL-induced RANKL expression in osteoblasts and osteoclast differentiation in the co-cultures. We found that 6-gingerol reduced PGE₂ levels by suppressing enzymatic activities of cyclooxygenase and PGE synthase, which cooperatively catalyze the conversion of arachidonic acid to PGE₂. Our findings demonstrate that 6-gingerol inhibits IL-1-induced osteoclast differentiation via suppression of RANKL expression in osteoblasts though reduction of PGE₂ levels, suggesting its potential use in treating inflammatory bone destruction associated with excessive PGE₂ production.

Lenalidomide regulates osteocytes fate and related osteoclastogenesis via IL-1β/NF-κB/RANKL signaling

Osteolytic diseases are closely associated with osteocyte fate, indicating a more efficient and crucial role of osteocyte-targeting strategy in inhibiting osteoclastogenesis. Here, we investigated the effects of lenalidomide (Lena) on osteocyte fate in order to regulate osteoclastogenesis via effective cascade-controlling response. Our data revealed that lenalidomide treatment notably rescued IL-1β induced loss of osteocyte viability by inhibiting osteocyte apoptosis with decreased osteoclast-related factors, RANKL and Sclerostin, as demonstrated by the restricted osteoclast formation and reduced bone resorption. Additionally, iTRAQ assay revealed that IL-1β induced activation of NF-κB inhibitor α/β were remarkably downregulated by lenalidomide, showing that lenalidomide impaired NF-κB signaling in osteocytes for inhibiting the expression of osteoclast specific genes in osteoclasts, which was further confirmed by KEGG pathway analysis and Western blot. More interestingly, the in vivo analysis of osteocyte apoptosis and osteoclastogenesis in osteoarthritis mice model indicated a role of lenalidomide in the regulation of osteocyte fate and the consequent inhibition of RANKL-induced osteoclastogenesis. Together, these results suggest that lenalidomide regulates osteocyte fate by attenuating IL-1β/NF-κB signaling, thereby inhibiting RANKL expression for the attenuated osteoclastogenesis both in vitro and vivo, indicating a more efficient remedy among future anti-osteoclastogenesis approaches.