Anemonin Attenuates RANKL-Induced Osteoclastogenesis and Ameliorates LPS-Induced Inflammatory Bone Loss in Mice via Modulation of NFATc1

Brain-Derived Neurotrophic Factor (BDNF) Enhances Osteogenesis and May Improve Bone Microarchitecture in an Ovariectomized Rat Model

BACKGROUND

Brain-derived neurotrophic factor (BDNF) has gained attention as a therapeutic agent due to its potential biological activities, including osteogenesis. However, the molecular mechanisms involved in the osteogenic activity of BDNF have not been fully understood. This study aimed to investigate the action of BDNF on the osteoblast differentiation in bone marrow stromal cells, and its influence on signaling pathways. In addition, to evaluate the clinical efficacy, an in vivo animal study was performed.

METHODS

Preosteoblast cells (MC3T3-E1), bone marrow-derived stromal cells (ST2), and a direct 2D co-culture system were treated with BDNF. The effect of BDNF on cell proliferation was determined using the CCK-8 assay. Osteoblast differentiation was assessed based on alkaline phosphatase (ALP) activity and staining and the protein expression of multiple osteoblast markers. Calcium accumulation was examined by Alizarin red S staining. For the animal study, we used ovariectomized Sprague-Dawley rats and divided them into BDNF and normal saline injection groups. MicroCT, hematoxylin and eosin (H&E), and tartrate-resistant acid phosphatase (TRAP) stain were performed for analysis.

RESULTS

BDNF significantly increased ALP activity, calcium deposition, and the expression of osteoblast differentiation-related proteins, such as ALP, osteopontin, etc., in both ST-2 and the MC3T3-E1 and ST-2 co-culture systems. Moreover, the effect of BDNF on osteogenic differentiation was diminished by blocking tropomyosin receptor kinase B, as well as inhibiting c-Jun N-terminal kinase and p38 MAPK signals. Although the animal study results including bone density and histology showed increased osteoblastic and decreased osteoclastic activity, only a portion of parameters reached statistical significance.

CONCLUSIONS

Our study results showed that BDNF affects osteoblast differentiation through TrkB receptor, and JNK and p38 MAPK signal pathways. Although not statistically significant, the trend of such effects was observed in the animal experiment.

Anemonin ameliorates human diploid fibroblasts 2BS and IMR90 cell senescence by PARP1-NAD+-SIRT1 signaling pathway

OBJECTIVE

Aging becomes the most predominant risk factor for all age-associated pathological conditions with the increase of life expectancy and the aggravation of social aging. Slowing down the speed of aging is considered an effective way to improve health, but so far, effective anti-aging methods are relatively lacking.

METHODS

Anemonin (ANE) was screened from eight existing small-molecule compounds by cell viability assay. The function of ANE was determined by the analysis of cell proliferation, β -galactosidase (SA-β -Gal) activity, cell cycle, SASP secretion, NAD+/NADH ratio, and other aging-related indicators. The targets of ANE were predicted by Drug Target Prediction System (DTPS) and Swiss Targe Prediction System. The effect of ANE on PARP-1-NAD+-SIRT1 signaling pathway was assessed by quantitative reverse-transcription polymerase chain reaction (RT-PCR), Western blot, PARP1, NAD+ and SIRT1 activity detection.

RESULTS

ANE can delay cell senescence; PARP1 is one of the targets of ANE and plays a crucial role in ANE anti-aging; ANE release more NAD+ by inhibiting PARP1 activity, thereby conversely promoting the function of SIRT1 and delay cell senescence.

CONCLUSIONS

Our study indicates that ANE can delay cellular senescence through the PARP1-NAD+-SIRT1 signaling pathway, which may be considered as an effective anti-aging strategy.

Anemonin inhibits sepsis-induced acute kidney injury via mitigating inflammation and oxidative stress

Elevated inflammation and oxidative stress (OS) are the main pathologic features of acute kidney injury (AKI)-caused by sepsis. Here, we made an investigation into the protective effects of the natural compound Anemonin (ANE) on sepsis-induced AKI both in vitro and in vivo. Lipopolysaccharide (LPS) was applied to construct an in vitro AKI model in renal tubular epithelial cells, and the septic C57BL/6J mouse model was constructed via cecal ligation and puncture (CLP). Cell viability and apoptosis were detected. The levels of p53, Bax, Bcl2, Caspase3, Caspase8, Caspase9, AMP-activated protein kinase (AMPK), Sirt-1, and forkhead box O3 were determined by Western Blot or RT-PCR. The reactive oxygen species level and OS markers were measured. Furthermore, the pathological changes of kidneys were evaluated by hematoxylin-eosin staining and immunohistochemistry. As per the information presented, ANE improved LPS-elicited apoptosis, inflammatory response, and OS in a dose-dependent pattern in renal tubular epithelial cells. Besides, ANE activated the AMPK/Sirt-1 pathway, and the AMPK inhibitor (Compound C) and Sirt-1 inhibitor (EX-527) significantly attenuated ANE-mediated protection on renal tubular epithelial cells. In vivo, ANE mitigated the levels of serum creatinine and urea nitrogen in the CLP-induced mouse sepsis model, reduced the renal tissue injury score, and attenuated OS, inflammation, and apoptosis levels in the kidney. Taken together, this study suggested that ANE has protective effects in sepsis-triggered AKI through repressing inflammation, OS, and cell apoptosis by activating the AMPK/Sirt-1 pathway.

Mechanism of regulating macrophages/osteoclasts in attenuating wear particle-induced aseptic osteolysis

Joint replacement surgery is the most effective treatment for end-stage arthritis. Aseptic loosening caused by periprosthetic osteolysis is a common complication after joint replacement. Inflammation induced by wear particles derived from prosthetic biomaterials is a major cause of osteolysis. We emphasize that bone marrow-derived macrophages and their fusion-derived osteoclasts play a key role in this pathological process. Researchers have developed multiple intervention approaches to regulate macrophage/osteoclast activation. Aiming at wear particle-induced periprosthetic aseptic osteolysis, this review separately discusses the molecular mechanism of regulation of ROS formation and inflammatory response through intervention of macrophage/osteoclast RANKL-MAPKs-NF-κB pathway. These molecular mechanisms regulate osteoclast activation in different ways, but they are not isolated from each other. There is also a lot of crosstalk among the different mechanisms. In addition, other bone and joint diseases related to osteoclast activation are also briefly introduced. Therefore, we discuss these new findings in the context of existing work with a view to developing new strategies for wear particle-associated osteolysis based on the regulation of macrophages/osteoclasts.

Anemonin reduces hydrogen peroxide-induced oxidative stress, inflammation and extracellular matrix degradation in nucleus pulposus cells by regulating NOX4/NF-κB signaling pathway

BACKGROUND

Excessive oxidative stress plays a critical role in the progression of various diseases, including intervertebral disk degeneration (IVDD). Recent studies have found that anemonin (ANE) possesses antioxidant and anti-inflammatory effects. However, the role of ANE in IVDD is still unclear. Therefore, this study investigated the effect and mechanism of ANE on H₂O₂ induced degeneration of nucleus pulposus cells (NPCs).

METHODS

NPCs were pretreated with ANE, and then treated with H₂O₂. NOX4 was upregulated by transfection of pcDNA-NOX4 into NPCs. Cytotoxicity was detected by MTT, oxidative stress-related indicators and inflammatory factors were measured by ELISA, mRNA expression was assessed by RT-PCR, and protein expression was tested by western blot.

RESULTS

ANE attenuated H₂O₂-induced inhibition of NPCs activity. H₂O₂ enhanced oxidative stress, namely, increased ROS and MDA levels and decreased SOD level. However, these were suppressed and pretreated by ANE. ANE treatment repressed the expression of inflammatory factors (IL-6, IL-1β and TNF-α) in H₂O₂-induced NPCs. ANE treatment also prevented the degradation of extracellular matrix induced by H₂O₂, showing the downregulation of MMP-3, 13 and ADAMTS-4, 5 and the upregulation of collagen II. NOX4 is a key factor regulating oxidative stress. Our study confirmed that ANE could restrain NOX4 and p-NF-κB. In addition, overexpression of NOX4 counteracted the antioxidant and anti-inflammatory activities of ANE in H₂O₂-induced NPCs, and the inhibition of the degradation of extracellular matrix induced by ANE was also reversed by overexpression of NOX4.

CONCLUSION

ANE repressed oxidative stress, inflammation and extracellular matrix degradation in H₂O₂-induced NPCs by inhibiting NOX4/NF-κB pathway. Our study indicated that ANE might be a candidate drug for the treatment of IVDD.

FTY720 Attenuates LPS-Induced Inflammatory Bone Loss by Inhibiting Osteoclastogenesis via the NF-κB and HDAC4/ATF Pathways

Osteoclast (OC) abnormalities lead to many osteolytic diseases, such as osteoporosis, inflammatory bone erosion, and tumor-induced osteolysis. Exploring effective strategies to remediate OCs dysregulation is essential. FTY720, also known as fingolimod, has been approved for the treatment of multiple sclerosis and has anti-inflammatory and immunosuppressive effects. Here, we found that FTY720 inhibited osteoclastogenesis and OC function by inhibiting nuclear factor kappa-B (NF-κB) signaling. Interestingly, we also found that FTY720 inhibited osteoclastogenesis by upregulating histone deacetylase 4 (HDAC4) expression levels and downregulating activating transcription factor 4 (ATF4) expression levels. In vivo, FTY720 treatment prevented lipopolysaccharide- (LPS-) induced calvarial osteolysis and significantly reduced the number of tartrate-resistant acid phosphatase- (TRAP-) positive OCs. Taken together, these results demonstrate that FTY720 can inhibit osteoclastogenesis and ameliorate inflammation-induced bone loss. Which may provide evidence of a new therapeutic target for skeletal diseases caused by OC abnormalities.

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).

MicroRNA-506 ameliorates breast cancer-induced osteolytic bone metastasis via the NFATc-1 signaling pathway

Breast cancer is becoming a common life-threatening disease, especially in women, along with higher incidence and mortality. MicroRNA (miR)-506 was reported to participate in breast cancer progression, while the role of miR-506 in breast cancer-induced osteolytic bone metastasis is unclear. In the present study, we found significant downregulation of miR-506 in breast cancer tissues and cell lines. Overexpression of miR-506 notably reduced the proliferative, migratory and invasive rates of MCF7 and MDA-MB-231 cells, and reduced the production of inflammatory factors IL-6 and TNF-α in MCF7 cells. Moreover, overexpression of miR-506 obviously inhibited tumor growth in an in vivo animal model. In addition, overexpression of miR-560 efficiently attenuated breast cancer-induced osteolysis in vivo, which was characterized by increased bone volume/total volume (BT/TV), trabecular number (Tb. N), and trabecular thickness (Tb. Th), as well as the reduced trabecular separation (Tb. Sp). The nuclear factor of activated T cell cytoplasmic 1 (NFATc1) was identified as a downstream target of miR-506, and overexpression of miR-506 could inhibit breast cancer progression by targeting NFATc1. Furthermore, our results showed that NFATc-1 might participate in the inhibition of miR-506 on breast cancer-induced osteolysis. In conclusion, our findings provide insights into understanding the pathogenesis of breast cancer and breast cancer-induced osteolytic bone metastasis, and miR-506 might serve as a novel biomarker for this disease.

Comparative study of oral versus parenteral crocin in mitigating acrolein-induced lung injury in albino rats

Acrolein (Ac) is the second most commonly inhaled toxin, produced in smoke of fires, tobacco smoke, overheated oils, and fried foods; and usually associated with lung toxicity. Crocin (Cr) is a natural carotenoid with a direct antioxidant capacity. Yet, oral administration of crocin as a natural rout is doubtful, because of poor absorbability. Therefore, the current study aimed to compare the potential protective effect of oral versus intraperitoneal (ip) crocin in mitigating Ac-induced lung toxicity. 50 Adult rats were randomly divided into 5 equal groups; Control (oral-saline and ip-saline) group, Cr (oral-Cr and ip-Cr) group, Ac group, oral-Cr/Ac group, and ip-Cr/Ac group; for biochemical, histopathological, and immunohistochemical investigations. Results indicated increased oxidative stress and inflammatory biomarkers in lungs of Ac-treated group. Histopathological and immunohistochemical examinations revealed lung edema, infiltration, fibrosis, and altered expression of apoptotic and anti-apoptotic markers. Compared to oral-Cr/Ac group, the ip-Cr/Ac group demonstrated remarkable improvement in the oxidative, inflammatory, and apoptotic biomarkers, as well as the histopathological alterations. In conclusion, intraperitoneal crocin exerts a more protective effect on acrolein-induced lung toxicity than the orally administered crocin.

Anti-inflammatory effects of anemonin on acute ulcerative colitis via targeted regulation of protein kinase C-θ

Background

Ulcerative colitis (UC) is an inflammatory bowel disease that causes continuous mucosal inflammation. Anemonin is a natural molecule from the Ranunculaceae and Gramineae plants that exerts anti-inflammatory properties. This study aimed to explore the effects and mechanisms of anemonin on UC.

Methods

C57BL/6 mice were administered dextran sulphate sodium (DSS; 3% [w/v]) to establish an animal model of UC. Mice were treated with an intraperitoneal injection of anemonin. Body weight and the disease activity index (DAI) were recorded. Haematoxylin and eosin staining, RT-qPCR, ELISA, and western blotting were performed to evaluate the histopathological changes and tissue inflammation. HT-29 cells were treated with lipopolysaccharide (LPS) and anemonin. Cell inflammation was evaluated using RT-qPCR and western blotting. The target proteins of anemonin were predicted using bioinformatics analysis and confirmed in vitro and in vivo.

Results

Anemonin improved DSS-induced body weight loss, shortened colon length, increased DAI, and induced pathological changes in the colon tissue of mice. Anemonin inhibited DSS-induced colon tissue inflammation as the release of IL-1β, TNF-α, and IL-6 was significantly suppressed. Additionally, anemonin attenuated LPS-induced cytokine production in HT-29 cells. PKC-θ was predicted as a target protein of anemonin. Anemonin did not affect PRKCQ gene transcription, but inhibited its translation. PRKCQ overexpression partially reversed the protective effects of anemonin on HT-29 cells. Adeno-associated virus delivery of the PRKCQ vector significantly reversed the protective effects of anemonin on the mouse colon.

Conclusions

Anemonin has the potential to treat UC. The anti-inflammatory effects of anemonin may be mediated through targeting PKC-θ.

In Vitro Antileishmanial and Antischistosomal Activities of Anemonin Isolated from the Fresh Leaves of Ranunculus multifidus Forsk

Leishmaniasis and schistosomiasis are neglected tropical diseases (NTDs) infecting the world’s poorest populations. Effectiveness of the current antileishmanial and antischistosomal therapies are significantly declining, which calls for an urgent need of new effective and safe drugs. In Ethiopia fresh leaves of Ranunculus multifidus Forsk. are traditionally used for the treatment of various ailments including leishmaniasis and eradication of intestinal worms. In the current study, anemonin isolated from the fresh leaves of R. multifidus was assessed for its in vitro antileishmanial and antischistosomal activities. Anemonin was isolated from the hydro-distilled extract of the leaves of R. multifidus. Antileishmanial activity was assessed on clinical isolates of the promastigote and amastigote forms of Leishmania aethiopica and L. donovani clinical isolates. Resazurin reduction assay was used to determine antipromastigote activity, while macrophages were employed for antiamastigote and cytotoxicity assays. Antischistosomal assays were performed against adult Schistosoma mansoni and newly transformed schistosomules (NTS). Anemonin displayed significant antileishmanial activity with IC₅₀ values of 1.33 nM and 1.58 nM against promastigotes and 1.24 nM and 1.91 nM against amastigotes of L. aethiopica and L. donovani, respectively. It also showed moderate activity against adult S. mansoni and NTS (49% activity against adult S. mansoni at 10 µM and 41% activity against NTS at 1 µM). The results obtained in this investigation indicate that anemonin has the potential to be used as a template for designing novel antileishmanial and antischistosomal pharmacophores.

Phytomolecules Repurposed as Covid-19 Inhibitors: Opportunity and Challenges

The SARS-CoV-2 virus has spread worldwide to cause a full blown pandemic since 2020. To date, several promising synthetic therapeutics are repurposed and vaccines through different stages of clinical trials were approved and being administered, but still the efficacy of the drugs and vaccines are yet to be decoded. This article highlights the importance of traditional medicinal plants and the phytomolecules derived from them, which possess in vitro antiviral and anti-CoV properties and further explores their potential as inhibitors to molecular targets of SARS-CoV-2 that were evaluated by in silico approaches. Botanicals in traditional medicinal systems have been investigated for anti-SARS-CoV-2 activity through in silico and in vitro studies. However, information linking structure of phytomolecules to their antiviral activity is limited. Most phytomolecules with anti-CoV activity were studied for inhibition of the human ACE2 receptor through which the virus enters host cells, and non-structural proteins 3CLpro and PLpro. Although the proteases are ideal anti-CoV targets, information on plant-based inhibitors for the CoV structural proteins, e.g., spike, envelope, membrane, nucleocapsid required further investigations. In absence of scientific evaluations through in vitro and biocompatibility studies, plant-based antivirals fall short as treatment options. Plant-based anti-SARS-CoV-2 therapeutics can be promising alternatives to their synthetic counterparts as they are economical and bear fewer chances of toxicity, side effects, and viral resistance. Our review could provide a systematic overview of the potential phytomolecules which can be repurposed and subjected to further modes of experimental evaluation to qualify for use in treatment and prophylaxis of SARS-CoV-2 infections.

Systems pharmacology dissection of action mechanisms for herbs in osteoporosis treatment

Objective

Osteoporosis has become the biggest cause of non-fatal health issue. Currently, the limitations of traditional anti-osteoporosis drugs such as long-term ill-effects and drug resistance, have raised concerns toward complementary and alternative therapies, particularly herbal medicines and their natural active compounds. Thus, this study aimed to provide an integrative analysis of active chemicals, drug targets and interacting pathways of the herbs for osteoporosis treatment.

Methods

Here, we introduced a systematic pharmacology model, combining the absorption, distribution, metabolism, and excretion (ADME) screening model, drug targeting and network pharmacology, to probe into the therapeutic mechanisms of herbs in osteoporosis.

Results

We obtained 86 natural compounds with favorable pharmacokinetic profiles and their 58 targets from seven osteoporosis-related herbs. Network analysis revealed that they probably synergistically work through multiple mechanisms, such as suppressing inflammatory response, maintaining bone metabolism or improving organism immunity, to benefit patients with osteoporosis. Furthermore, experimental results showed that all the five compounds (calycosin, asperosaponin VI, hederagenin, betulinic acid and luteolin) enhanced osteoblast proliferation and differentiation in vitro, which corroborated the validity of this system pharmacology approach. Notably, gentisin and aureusidin among the identified compounds were first predicted to be associated with osteoporosis.

Conclusion

Herbs and their natural compounds, being characterized as the classical combination therapies, might be engaged in multiple mechanisms to coordinately improve the osteoporosis symptoms. This work may contribute to offer novel strategies and clues for the therapy and drug discovery of osteoporosis and other complex diseases.

Acanthopanax senticosus aqueous extract ameliorates ovariectomy-induced bone loss in middle-aged mice by inhibiting the receptor activator of nuclear factor-κB ligand-induced osteoclastogenesis

Acanthopanax senticosus (Ciwujia) has broad-spectrum pharmacological activities, including osteoprotective effects. However, the mechanisms underlying these effects remain unclear. We investigated whether Acanthopanax senticosus aqueous extract (ASAE) ameliorates ovariectomy-induced bone loss in middle-aged mice through inhibition of osteoclastogenesis. In vitro, ASAE significantly suppressed the receptor activator of nuclear factor-κB ligand (RANKL)-stimulated osteoclast differentiation and formation of F-actin rings by downregulating the expression of the nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), c-Fos, and osteoclastogenesis-related marker genes and proteins, including c-Src, tartrate-resistant acid phosphatase (TRAP), cathepsin K, β3-integrin, and matrix metallopeptidase-9 (MMP-9). This was achieved by inhibiting RANK signaling pathways, including p65, c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38 in osteoclast precursors. In vivo, ASAE markedly ameliorated bone loss in ovariectomized (OVX) middle-aged mice. ASAE significantly inhibited the serum levels of tartrate-resistant acid phosphatase 5b (TRACP-5b) and RANKL, whereas it increased those of osteocalcin, procollagen 1 N-terminal peptide (P1NP), and osteoprotegerin in OVX mice. ASAE significantly inhibited the OVX-induced expression of osteoclast-specific proteins and genes in the femur. In conclusion, ASAE prevents ovariectomy-induced bone loss in middle-aged mice by inhibiting RANKL-induced osteoclastogenesis through suppression of RANK signaling pathways and could be potentially used in mediated treatment of osteoclast-related diseases (e.g., osteoporosis).

Coenzyme Q10 enhances remyelination and regulate inflammation effects of cuprizone in corpus callosum of chronic model of multiple sclerosis

Multiple Sclerosis (MS) is a chronic, progressive demyelinating disease of the central nervous system that causes the most disability in young people, besides trauma. Coenzyme Q10 (CoQ10)-also known as ubiquinone-is an endogenous lipid-soluble antioxidant in the mitochondrial oxidative respiratory chain which can reduce oxidative stress and inflammation, the processes associated with demyelination in MS. Cuprizone (CPZ) intoxication is a well-established model of inducing MS, best for studying demyelination-remyelination. In this study, we examined for the first time the role of CoQ10 in preventing demyelination and induction of remyelination in the chronic CPZ model of MS. 40 male mice were divided into four groups. 3 group chewed CPZ-containing food for 12 weeks to induce MS. After 4 weeks, one group were treated with CoQ10 (150 mg/kg/day) by daily gavage until the end of the experiment, while CPZ poisoning continued. At the end of 12 weeks, tail suspension test (TST) and open field test (OFT) was taken and animals were sacrificed to assess myelin basic protein (MBP), oligodendrocyte transcription factor-1 (Olig1), tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) by real-time polymerase chain reaction (real-time PCR) and total antioxidant capacity (TAC) and superoxide dismutase (SOD) by Elisa test. Luxol fast blue (LFB) staining was used to evaluate histological changes. CoQ10 administration promoted remyelination in histological findings. MBP and Olig-1 expression were increased significantly in CoQ10 treated group compare to the CPZ-intoxicated group. CoQ10 treatment alleviated stress oxidative status induced by CPZ and dramatically suppress inflammatory biomarkers. CPZ ingestion made no significant difference between normal control group and the CPZ-intoxicated group in TST and OFT. CoQ10 can enhance remyelination in the CPZ model and potentially might have same effects in MS patients.

Ellagic acid blocks RANKL-RANK interaction and suppresses RANKL-induced osteoclastogenesis by inhibiting RANK signaling pathways

Ellagic acid (EA) is a naturally occurring polyphenolic compound that has been shown to exhibit diverse beneficial pharmacological activities including anti-osteoclastogenesis effect. However, the molecular mechanism by which EA inhibits osteoclastogenesis remains to be elucidated. The protein-protein interaction between receptor activator of nuclear factor (NF)-κB ligand (RANKL) and its receptor RANK contributes to osteoclast differentiation and activation in bone remodeling, and is regarded as an important therapeutic target for the treatment of osteoporosis. The current study is focused on investigating whether EA can directly bind to RANKL and/or RANK and block the interaction between RANKL and RANK, thereby inhibiting downstream signaling pathways. Interestingly, we found that EA had strong affinities to RANK and RANKL, with the estimated equilibrium dissociation constants (K_D) of 2.485 × 10^-11 and 1.688 × 10^-9 M, respectively, and could disrupt the interaction between RANKL and RANK, thereby inhibiting RANKL-induced canonical RANK signaling pathways (p65, JNK, ERK, and p38) and expression of downstream master transcriptional factors (NFATc1 and c-Fos) and osteoclast-specific genes and proteins (TRAP, c-Src, and cathepsin K), which could ultimately suppress RANKL-induced osteoclast differentiation and F-actin ring formation. Taken together, our results revealed that EA could block RANKL-RANK interaction and suppress RANKL-induced osteoclastogenesis by inhibiting RANK signaling pathways in RAW 264.7 murine macrophages.

A Review of the Pharmacological Properties of Psoralen

Psoralen is the principal bioactive component in the dried fruits of Cullen corylifolium (L.) Medik (syn. Psoralea corylifolia L), termed "Buguzhi" in traditional Chinese medicine (TCM). Recent studies have demonstrated that psoralen displays multiple bioactive properties, beneficial for the treatment of osteoporosis, tumors, viruses, bacteria, and inflammation. The present review focuses on the research evidence relating to the properties of psoralen gathered over recent years. Firstly, multiple studies have demonstrated that psoralen exerts strong anti-osteoporotic effects via regulation of osteoblast/osteoclast/chondrocyte differentiation or activation due to the participation in multiple molecular mechanisms of the wnt/β-catenin, bone morphogenetic protein (BMP), inositol-requiring enzyme 1 (IRE1)/apoptosis signaling kinase 1 (ASK1)/c-jun N-terminal kinase (JNK) and the Protein Kinase B(AKT)/activator protein-1 (AP-1) axis, and the expression of miR-488, peroxisome proliferators-activated receptor-gamma (PPARγ), and matrix metalloproteinases (MMPs). In addition, the antitumor properties of psoralen are associated with the induction of ER stress-related cell death via enhancement of PERK: Pancreatic Endoplasmic Reticulum Kinase (PERK)/activating transcription factor (ATF), 78kD glucose-regulated protein (GRP78)/C/EBP homologous protein (CHOP), and 94kD glucose-regulated protein (GRP94)/CHOP signaling, and inhibition of P-glycoprotein (P-gp) or ATPase that overcomes multidrug resistance. Furthermore, multiple articles have shown that the antibacterial, anti-inflammatory and neuroprotective effects of psoralen are a result of its interaction with viral polymerase (Pol), destroying the formation of biofilm, and regulating the activation of tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-β), interleukin 4/5/6/8/12/13 (IL-4/5/6/8/12/13), GATA-3, acetylcholinesterase (AChE), and the hypothalamic-pituitary-adrenal (HPA) axis. Finally, the toxic effects and mechanisms of action of psoralen have also been reviewed.