Potential of resveratrol analogues as antagonists of osteoclasts and promoters of osteoblasts

Evaluating the Efficacy of Resveratrol-Containing Mouthwash as an Adjunct Treatment for Periodontitis: A Randomized Clinical Trial

OBJECTIVES

 To evaluate the effectiveness of resveratrol mouthwash as an adjunct to nonsurgical periodontal treatment of periodontitis.

MATERIALS AND METHODS

 This study was a randomized, double-blind clinical trial study. The study included 57 participants with periodontitis. Clinical parameters (plaque index [PI], bleeding on probing [BOP], probing pocket depth [PPD], and clinical attachment loss [CAL]) were examined at the baseline visit, after 7 days, and after 30 days of using resveratrol mouthwash as an adjunct to nonsurgical periodontal treatment. The salivary levels of (interleukin [IL]-6) and RANKL (receptor activator of nuclear factor-kappa B ligand) were measured and compared before and after treatment. The participants answered the visual analog scale-based assessment questionnaire at the last visit.

STATISTICAL ANALYSIS

 A one-way ANOVA (analysis of variance) test was used to compare the means of multiple groups (test, positive control, negative control) at baseline and after treatment. A paired t-test was also used to compare the means of a single group before and after treatment. In addition, Tukey's multiple comparisons test was used to identify specific pairwise differences between the three groups after finding significant differences with ANOVA. The Chi-square test was also used to compare the distribution of categorical variables like sex between the groups.

RESULTS

 All interventions significantly reduced PI, BOP, PPD, and CAL, but resveratrol and chlorhexidine had a higher significant effect than placebo except for CAL without a significant difference between them. All mouthwashes significantly reduced the salivary concentration of IL-6. However, resveratrol and chlorhexidine had a significantly higher effect than placebo, while the concentration of RANKL was decreased in all groups without a significant difference between them. The participants' responses to the mouthwash questionnaire showed that resveratrol and chlorhexidine had the same feedback without significant differences.

CONCLUSION

 Resveratrol-containing mouthwash could be used as an alternative to chlorhexidine as an adjunct to nonsurgical periodontal treatment of periodontitis.

Promising potential effects of resveratrol on oral and dental health maintenance: a comprehensive review

Resveratrol (RV-3, 5, 4'-trihydroxystilbene) is a natural compound found in plants like red grapes, berries, and peanuts, with promising effects on dental health. It helps strengthen tooth enamel by promoting remineralization, making the teeth more resistant to decay caused by acid-producing bacteria. RV also shields dentin, a vulnerable layer beneath the enamel, from erosion and sensitivity. Its anti-inflammatory properties can reduce inflammation associated with dental conditions such as pulpitis and endodontic diseases. Moreover, RV's antimicrobial activity inhibits the growth of bacteria involved in dental plaque and biofilm formation, preventing their accumulation on the tooth surface. This contributes to a healthier oral environment and prolongs the lifespan of dental restorative materials. However, the research on RV's impact on dental health is in its early stages, and further studies are needed to confirm potential benefits. Important factors such as determining the optimal dosage, understanding its bioavailability, and assessing potential side effects require further investigation. This review focuses on the important role of RV in promoting dental health. It delves into various aspects, including its impact on root health, maintenance of the dental pulp, care for tooth enamel, effectiveness of dental restorative materials, and health of dentin.

Biomaterial Cues for Regulation of Osteoclast Differentiation and Function in Bone Regeneration

Tissue regeneration involves dynamic dialogue between and among different cells and their surrounding matrices. Bone regeneration is specifically governed by reciprocity between osteoblasts and osteoclasts within the bone microenvironment. Osteoclast-directed resorption and osteoblast-directed formation of bone are essential to bone remodeling, and the crosstalk between these cells is vital to curating a sequence of events that culminate in the creation of bone tissue. Among bone biomaterial strategies, many have investigated the use of different material cues to direct the development and activity of osteoblasts. However, less attention has been given to exploring features that similarly target osteoclast formation and activity, with even fewer strategies demonstrating or integrating biomaterial-directed modulation of osteoblast-osteoclast coupling. This review aims to describe various biomaterial cues demonstrated to influence osteoclastogenesis and osteoclast function, emphasizing those that enhance a material construct's ability to achieve bone healing and regeneration. Additionally discussed are approaches that influence the communication between osteoclasts and osteoblasts, particularly in a manner that takes advantage of their coupling. Deepening our understanding of how biomaterial cues may dictate osteoclast differentiation, function, and influence on the microenvironment may enable the realization of bone-replacement interventions with enhanced integrative and regenerative capacities.

Nitrostilbenes: Synthesis and Biological Evaluation as Potential Anti-Influenza Virus Agents

Resveratrol (RSV) is a natural stilbene polyphenolic compound found in several plant species. It is characterized by antioxidant properties, and its role in controlling viral replication has been demonstrated for different viral infections. Despite its promising antiviral properties, RSV biological activity is limited by its low bioavailability and high metabolic rate. In this study, we optimized its structure by synthesizing new RSV derivatives that maintained the phenolic scaffold and contained different substitution patterns and evaluated their potential anti-influenza virus activity. The results showed that viral protein synthesis decreased 24 h post infection; particularly, the nitro-containing compounds strongly reduced viral replication. The molecules did not exert their antioxidant properties during infection; in fact, they were not able to rescue the virus-induced drop in GSH content or improve the antioxidant response mediated by the Nrf2 transcription factor and G6PD enzyme. Similar to what has already been reported for RSV, they interfered with the nuclear-cytoplasmic traffic of viral nucleoprotein, probably inhibiting cellular kinases involved in the regulation of specific steps of the virus life cycle. Overall, the data indicate that more lipophilic RSV derivatives have improved antiviral efficacy compared with RSV and open the way for new cell-targeted antiviral strategies.

Research Progress of Natural Small-Molecule Compounds Related to Tumor Differentiation

Tumor differentiation is a therapeutic strategy aimed at reactivating the endogenous differentiation program of cancer cells and inducing cancer cells to mature and differentiate into other types of cells. It has been found that a variety of natural small-molecule drugs can induce tumor cell differentiation both in vitro and in vivo. Relevant molecules involved in the differentiation process may be potential therapeutic targets for tumor cells. Compared with synthetic drugs, natural small-molecule antitumor compounds have the characteristics of wide sources, structural diversity and low toxicity. In addition, natural drugs with structural modification and transformation have relatively concentrated targets and enhanced efficacy. Therefore, using natural small-molecule compounds to induce malignant cell differentiation represents a more targeted and potential low-toxicity means of tumor treatment. In this review, we focus on natural small-molecule compounds that induce differentiation of myeloid leukemia cells, osteoblasts and other malignant cells into functional cells by regulating signaling pathways and the expression of specific genes. We provide a reference for the subsequent development of natural small molecules for antitumor applications and promote the development of differentiation therapy.

Multiple Effects of Resveratrol on Osteosarcoma Cell Lines

Osteosarcoma (OS) is the most common primary bone sarcoma affecting the life of pediatric patients. The clinical treatment faces numerous difficulties, including the adverse effects of chemotherapies, chemoresistance, and recurrences. In this study, the effects of resveratrol (RSV), a natural polyphenol, on OS cell lines were investigated to evaluate its action as an adjuvant therapy to the current chemotherapy regimens. RSV exhibited multiple tumor-suppressing activities on OS cell lines, inducing a series of critical events. We found (1) a cell growth inhibition due to an increase in cell distress, which was, in part, due to the involvement of the AKT and caspase-3 pathways, (2) an increase in cellular differentiation due to major gene expression levels of the osteoblastic differentiation genes, (3) an inhibition of IL-6 secretion due to an epigenetic effect on the IL-6 promoter, and (4) an inhibition of OS cells migration related to the decrease in IL-8 secretion levels due to an epigenetic effect on its promoter. Finally, the cotreatment of RSV with doxorubicin and cisplatin increased their cytotoxic effect on OS cells. Although further investigations are mandatory, it seems RSV might be a promising therapeutic adjuvant agent for OS cell treatment, exerting an antitumor effect when combined with chemotherapy.

Osteoinductive activity of bisdemethoxycurcumin and its synergistic protective effect with human amniotic mesenchymal stem cells against ovariectomy-induced osteoporosis mouse model

Osteoporosis is a common disease characterized by skeletal fragility and microarchitectural deterioration. However, existing conventional drugs exhibit limited efficacy and can elicit severe adverse effects; moreover, and novel stem cell-based therapies have not exhibited sufficient therapeutic efficacy. Our hypothesis is that an appropriate osteogenic inducer may improve their therapeutic efficacy. In this study, we found that bisdemethoxycurcumin (BDMC) stimulates the differentiation of human amniotic mesenchymal stem cells (hAMSCs) into osteoblasts without inducing cytotoxicity. Here BDMC enhances calcium deposition in hAMSCs, while promoting the expression of early and late markers of osteoblast differentiation, including ALP, runt-related transcription factor 2, osterix, COL1-α1, osteocalcin, and osteopontin at the transcriptional and translational levels. Mechanistically, BDMC was found to activate the JAK2/STAT3 pathway; whereas AG490 (JAK2/STAT3 pathway inhibitor) inhibited BDMC functioning. Subsequently, we found that the combinatorial therapy of BDMC and hAMSC had a positive synergistic effect on osteoporotic mouse model induced by bilateral ovariectomy, including inhibiting bone loss and bone resorption and improving bone micro-architecture. Moreover, BDMC inhibited production of the bone resorption markers C-terminal telopeptide of type I collagen, and tartrate resistant acid phosphatase, while promoting serum levels of bone formation markers OCN, and procollagen I N-terminal propeptide. BDMC also improved liver and kidney function in osteoporotic mouse model. Collectively, BDMC improved osteoporosis by enhancing hAMSC osteogenesis and exhibited a protective effect on liver and kidney function in an osteoporotic mouse model. Hence, BDMC may serve as an effective adjuvant, and combined therapy with hAMSCs is a promising new approach toward osteoporosis treatment.

Effects of Extracellular Osteoanabolic Agents on the Endogenous Response of Osteoblastic Cells

The complex multidimensional skeletal organization can adapt its structure in accordance with external contexts, demonstrating excellent self-renewal capacity. Thus, optimal extracellular environmental properties are critical for bone regeneration and inextricably linked to the mechanical and biological states of bone. It is interesting to note that the microstructure of bone depends not only on genetic determinants (which control the bone remodeling loop through autocrine and paracrine signals) but also, more importantly, on the continuous response of cells to external mechanical cues. In particular, bone cells sense mechanical signals such as shear, tensile, loading and vibration, and once activated, they react by regulating bone anabolism. Although several specific surrounding conditions needed for osteoblast cells to specifically augment bone formation have been empirically discovered, most of the underlying biomechanical cellular processes underneath remain largely unknown. Nevertheless, exogenous stimuli of endogenous osteogenesis can be applied to promote the mineral apposition rate, bone formation, bone mass and bone strength, as well as expediting fracture repair and bone regeneration. The following review summarizes the latest studies related to the proliferation and differentiation of osteoblastic cells, enhanced by mechanical forces or supplemental signaling factors (such as trace metals, nutraceuticals, vitamins and exosomes), providing a thorough overview of the exogenous osteogenic agents which can be exploited to modulate and influence the mechanically induced anabolism of bone. Furthermore, this review aims to discuss the emerging role of extracellular stimuli in skeletal metabolism as well as their potential roles and provide new perspectives for the treatment of bone disorders.

Resveratrol inhibits adipocyte differentiation and cellular senescence of human bone marrow stromal stem cells

Bone marrow adipose tissue (BMAT) is a unique adipose depot originating from bone marrow stromal stem cells (BMSCs) and regulates bone homeostasis and energy metabolism. An increased BMAT volume is observed in several conditions e.g. obesity, type 2 diabetes, osteoporosis and is known to be associated with bone fragility and increased risk for fracture. Therapeutic approaches to decrease the accumulation of BMAT are clinically relevant. In a screening experiment of natural compounds, we identified Resveratrol (RSV), a plant-derived antioxidant mediating biological effects via sirtuin- related mechanisms, to exert significant effects of BMAT formation. Thus, we examined in details the effects RSV on adipocytic and osteoblastic differentiation of tolermerized human BMSCs (hBMSC-TERT). RSV (1.0 μM) enhanced osteoblastic differentiation and inhibited adipocytic differentiation of hBMSC-TERT when compared with control and Sirtinol (Sirtuin inhibitor). Global gene expression profiling and western blot analysis revealed activation of a number of signaling pathways including focal adhesion kinase (FAK). Pharmacological inhibition of FAK using (PF-573228) and AKT inhibitor (LY-294002) (5μM), diminished RSV-induced osteoblast differentiation. In addition, RSV reduced the levels of senescence-associated secretory phenotype (SASP), gene markers associated with senescence (P53, P16, and P21), intracellular ROS levels and increased gene expression of enzymes protecting cells from oxidative damage (HMOX1 and SOD3). In vitro treatment of primary hBMSCs from aged patients characterized with high adipocytic and low osteoblastic differentiation ability with RSV, significantly enhanced osteoblast and decreased adipocyte formation when compared to hBMSCs from young donors. RSV targets hBMSCs and inhibits adipogenic differentiation and senescence-associated phenotype and thus a potential agent for treating conditions of increased BMAT formation.

Inhibitory effects of resveratrol on orthodontic tooth movement and associated root resorption in rats

OBJECTIVE

To investigate the effect of resveratrol (RSV) on orthodontic tooth movement (OTM) and orthodontic induced root resorption (OIRR) in rats.

METHODS

Thirty-six male Wistar rats used in this study were randomly divided into three groups of 12 animals each. All test subjects underwent a 50 g orthodontic force each, generated from a nickel-titanium closed-coil spring. The control group were fed carboxymethylcellulose (CMC) while rats in other two groups were fed 5 mg/kg/d RSV or 10 mg/kg/d RSV (dissolved in CMC). After 14 days of OTM, all rats were sacrificed, after which each group was randomly divided into two subgroups (6 test subjects in each subgroup). One subgroup was used to measure the amount of OTM and assessed by hematoxylin and eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemistry staining of Receptor Activator of Nuclear Factor-κ B Ligand (RANKL), Osteoprotegerin (OPG), Runt-related transcription factor 2 (RUNX2), as well as Osteocalcin (OCN). The second subgroup was used to analyze OIRR via scanning electron microscopy.

RESULTS

Compared with the control group, the RSV groups showed a significant decrease in the distance of OTM and the OIRR ratio (p＜0.05). The number of TRAP positive osteoclasts and the expression of RANKL in periodontal tissue of the RSV groups were significantly inhibited (p＜0.01) while the expression of OPG, RUNX2, and OCN were remarkably promoted (p＜0.05). The effect of 10 mg/kg/d RSV group was more obvious than that of 5 mg/kg/d RSV group (p＜0.05).

CONCLUSIONS

RSV could reduce the extent of OTM and root resorption areas.

Effects of resveratrol on bone health in type 2 diabetic patients. A double-blind randomized-controlled trial

Objectives

Patients with type 2 diabetes (T2DM) are at increased fracture risk. Resveratrol has shown beneficial effects on bone health in few studies. The aim of this trial was to investigate the effects of resveratrol on bone mineral density (BMD) and on calcium metabolism biomarkers in T2DM patients.

Methods

In this double-blind randomized placebo-controlled trial 192 T2DM outpatients were randomized to receive resveratrol 500 mg/day (Resv500 arm), resveratrol 40 mg/day (Resv40 arm) or placebo for 6 months. BMD, bone mineral content (BMC), serum calcium, phosphorus, alkaline phosphatase, and 25-hydroxy vitamin D were measured at baseline and after 6 months.

Results

At follow-up, calcium concentrations increased in all patients, while within-group variations in alkaline phosphatase were higher in both resveratrol arms, and 25-hydroxy vitamin D increased in the Resv500 arm only, without between-group differences. Whole-body BMD significantly decreased in the placebo group, while whole-body BMC decreased in both the placebo and Resv40 arms. No significant changes in BMD and BMC values occurred in the Resv500 arm. The adjusted mean differences of change from baseline were significantly different in the Resv500 arm vs placebo for whole-body BMD (0.01 vs −0.03 g/cm², p = 0.001), whole-body BMC (4.04 vs −58.8 g, p < 0.001), whole-body T-score (0.15 vs −0.26), and serum phosphorus (0.07 vs −0.01 µmol/L, p = 0.002). In subgroup analyses, in Resv500 treated-patients BMD values increased to higher levels in those with lower calcium and 25-hydroxy vitamin D values, and in alcohol drinkers.

Conclusions

Supplementation with 500 mg resveratrol prevented bone density loss in patients with T2DM, in particular, in those with unfavorable conditions at baseline.

The polyphenol resveratrol promotes skeletal growth in mice through a sirtuin 1-bone morphogenic protein 2 longevity axis

BACKGROUND AND PURPOSE

The polyphenol resveratrol (RSV) exists in high quantities in certain foods (e.g. grapes and nuts). However, the capacity of RSV to confer physiological health benefits and a biological mechanism through which this might occur remains unclear.

EXPERIMENTAL APPROACH

Aged, RSV-treated (300 mg·kg^-1 ·day^-1 ) and genetically modified [endothelial NOS (eNOS^-/- )] female mice were assessed using histomorphometric and μCT analysis. Alongside in vivo analysis, molecular siRNA knockdown and pharmacological manipulation of eNOS, BMP2 and sirtuin 1 (SIRT1) and functional cellular assays in an osteoblast cell line panel, explored the mechanism through which RSV might impact overall bone volume.

KEY RESULTS

RSV promoted osteoblast activity and bone growth in vivo. RSV dose-dependently and simultaneously increased alkaline phosphatase (ALP) and eNOS levels. Similarly, NO-donor treatment increased ALP, runt homology transcription factor 2, BMP2 and stimulated bone formation, whilst eNOS-deficient mice displayed a bone loss phenotype. Moreover, RSV-induced increase in ALP and BMP2 expression was blocked in eNOS^-/- osteoblasts and by BMP-inhibitor noggin. The longevity-linked SIRT1 enzyme was positively regulated by RSV and SIRT1 deletion reduced eNOS, BMP2 and ALP. Like eNOS deletion, loss of SIRT1 blocked RSV-induced osteoblast activity; however, SIRT1 levels remained unchanged in eNOS^-/- mice, indicating RSV activation of SIRT1 stimulates BMP2 release via eNOS. This signalling axis is supported by decreased SIRT1, eNOS and BMP2 confirmed in old versus young bone.

CONCLUSIONS AND IMPLICATIONS

These findings suggest a new mechanism of action in bone remodelling and the ageing skeleton, where RSV positively impacts bone homeostasis via SIRT1 activation of BMP2.

Resveratrol controlled the fate of porcine pancreatic stem cells through the Wnt/β-catenin signaling pathway mediated by Sirt1

Porcine pancreatic stem cells (PSCs) are considered promising transplant materials that may be used to treat diabetes, but some problems, such as insufficient cell number and low differentiation efficiency, should be solved before its clinical application. Resveratrol is a natural polyphenolic compound that can alleviate the complications of diabetes. In this study, we aimed to explore the specific effect of resveratrol on porcine PSCs. We treated porcine PSCs with 10 μM, 25 μM resveratrol to explore the effect of resveratrol on porcine PSCs. We found that 10 μM resveratrol improved the proliferation of porcine PSCs, increased the expression of A-β-catenin (active β-catenin), Pcna, C-Myc, Bcl-2 and sirtuin-1 (Sirt1), and decreased the expression of P53, Caspase3. While 25 μM resveratrol had almost opposite effect compared with 10 μM resveratrol group. The utilization of Dickkopf-related protein 1 (DKK1, Wnt signaling pathway inhibitor) and nicotinamide (Sirt1 inhibitor) suggested that resveratrol regulated cell proliferation by controlling Wnt signaling pathway and this effect was mediated by Sirt1. Our results further revealed that 10 μM resveratrol promoted the formation of β-like cells regulated by Wnt/β-catenin signal pathway. Relatively low-dose resveratrol could improve porcine PSCs fate. It lays theoretical foundation for diabetes treatment with cell transplantation in future.

Effects of resveratrol and cigarette smoking onbone healing: histomorphometric evaluation

BACKGROUND/AIM

The aim of the present study is to investigate the effects of cigarette smoke (CS) and simultaneous application of resveratrol on bone healing histomorphometrically and to evaluate the effects of resveratrol on negative effects of CS.

MATERIALS AND METHODS

For 4 weeks, Sprague Dawley rats were exposed to cigarette smoke at the equivalent of 6 cigarettes per day. After this period, monocortical defects were created in femurs by a trephine bur on day 28. Starting from the day of defect creation to the 28th postoperative day, rats were given 20 mg/kg body weight resveratrol. Histomorphometric examination of the number of osteoblasts and osteoclasts, as well as new bone area, was conducted.

RESULTS

Investigations were carried out on 33 rats. Differences between osteoblast numbers in the control and CS groups were significant, and CS caused a reduction in the number of osteoblasts. Areas of new bone formation in the resveratrol and control groups were higher than in the smoking and smoking+resveratrol groups.

CONCLUSION

Smoking appeared to have adverse effects upon bone healing and resveratrol administration helped to reduce these effects.

Defective skeletal mineralization in pediatric CKD

Although traditional diagnosis and treatment of renal osteodystrophy focused on changes in bone turnover, current data demonstrate that abnormalities in skeletal mineralization are also prevalent in pediatric chronic kidney disease (CKD) and likely contribute to skeletal morbidities that continue to plague this population. It is now clear that alterations in osteocyte biology, manifested by changes in osteocytic protein expression, occur in early CKD before abnormalities in traditional measures of mineral metabolism are apparent and may contribute to defective skeletal mineralization. Current treatment paradigms advocate the use of 1,25(OH)2vitamin D for the control of secondary hyperparathyroidism; however, these agents fail to correct defective skeletal mineralization and may exacerbate already altered osteocyte biology. Further studies are critically needed to identify the initial trigger for abnormalities of skeletal mineralization as well as the potential effects that current therapeutic options may have on osteocyte biology and bone mineralization.

Plant-derived anticancer agents: a promising treatment for bone metastasis

Bone metastasis is a very frequent complication of advanced cancer, and it remains an incurable disease. Current therapies that have been approved for the treatment of bone metastases delay the occurrence of skeletal-related events and can extend the patient's lifespan by a few years. However, they will not cure or cause the regression of established bone metastases, and new side effects are emerging after prolonged treatment. Thus, new therapies are severely needed. There are compelling evidences from in vitro and in vivo preclinical studies that support the use of compounds derived from plants to treat several forms of cancers including bone metastasis. More than 25% of the drugs used during the past 20 years were directly derived from plants, whereas another 25% are chemically altered natural products. Still, only 5-15% of the ∼250 000 higher plants have ever been investigated for bioactive compounds. There is a growing interest for the study of anticancer drugs with relatively low side effects that target specific key signaling pathways that control the establishment and progression of the cancer metastasis. Therefore, further studies are needed to identify new natural compounds with high efficiency in cancer prevention and treatment. Extensive reviews about plant-derived agents and their use in cancer have been published, but none when it comes to the treatment of bone metastases. Only a few of these compounds have been evaluated for the treatment of bone metastasis; here we describe some of the most prominent ones that are having the potential to reach the clinic soon.

Osteogenic effects of resveratrol in vitro: potential for the prevention and treatment of osteoporosis

There are a number of pharmacological agents for the treatment of bone mineral loss and osteoporosis. Hormone replacement therapy (HRT) with estrogen is an established treatment, but it has several adverse side effects and can increase the risk of cancer, heart disease, and stroke. There is increasing interest in nutritional factors and naturally occurring phytochemical compounds with the potential for preventing age-related and postmenopausal bone loss. Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenolic phytoestrogen with osteogenic and osteoinductive properties. It can modify the metabolism of bone cells and has the capacity to modulate bone turnover. This paper provides an overview of current research on resveratrol and its effects on bone cells in vitro, highlighting the challenges and opportunities facing this area of research, especially in the context of providing nutritional support for postmenopausal women who may not benefit from HRT and older patients with various forms of arthritis, metabolic bone disease, and osteoporosis.

Osteogenic activity of yellow flag iris (Iris pseudacorus) extract modulating differentiation of osteoblasts and osteoclasts

Bone integrity is maintained through a balance between bone formation by osteoblasts and bone resorption by osteoclasts. Imbalance of the process results in metabolic bone diseases such as osteoporosis. This study investigated the yellow flag iris extract (YFIE) and revealed its anti-osteoporotic effects in osteoblastic MC3T3-E1 mouse cells and RAW 264.7 murine macrophages. When osteoblasts were treated with 1-20 μg/ml YFIE in an osteogenic medium, the bone nodule formation by calcium deposits was markedly enhanced during differentiation. Consistently, YFIE stimulated alkaline phosphatase activity and collagen type I secretion with a substantial effect on osteoblast proliferation. On the other hand, RAW 264.7 macrophages were pre-incubated with 1-20 μg/ml YFIE for 5 days in the presence of receptor activator of nuclear factor-κB ligand (RANKL). Non-toxic YFIE markedly attenuated the differentiation of macrophages to multi-nucleated osteoclasts. YFIE diminished RANKL-elevated tartrate-resistant acid phosphatase activity and bone resorption. In addition, the YFIE treatment retarded RANKL-induced cathepsin K production and carbonic anhydrase II expression, both of which are involved in bone resorption. Therefore, YFIE potentially posesses therapeutic agents that may prevent osteoporosis through promoting bone formation and reducing bone resorption.

Silent information regulator (Sir)T1 inhibits NF-κB signaling to maintain normal skeletal remodeling

Silent information regulator T1 (SirT1) is linked to longevity and negatively controls NF-κB signaling, a crucial mediator of survival and regulator of both osteoclasts and osteoblasts. Here we show that NF-κB repression by SirT1 in both osteoclasts and osteoblasts is necessary for proper bone remodeling and may contribute to the mechanisms linking aging and bone loss. Osteoclast- or osteoblast-specific SirT1 deletion using the Sirt(flox/flox) mice crossed to lysozyme M-cre and the 2.3 kb col1a1-cre transgenic mice, respectively, resulted in decreased bone mass caused by increased resorption and reduced bone formation. In osteoclasts, lack of SirT1 promoted osteoclastogenesis in vitro and activated NF-κB by increasing acetylation of Lysine 310. Importantly, this increase in osteoclastogenesis was blocked by pharmacological inhibition of NF-κB. In osteoblasts, decreased SirT1 reduced osteoblast differentiation, which could also be rescued by inhibition of NF-κB. In further support of the critical role of NF-κB signaling in bone remodeling, elevated NF-κB activity in IκBα(+/-) mice uncoupled bone resorption and formation, leading to reduced bone mass. These findings support the notion that SirT1 is a genetic determinant of bone mass, acting in a cell-autonomous manner in both osteoblasts and osteoclasts, through control of NF-κB and bone cell differentiation.

Measles virus nucleocapsid protein, a key contributor to Paget's disease, increases IL-6 expression via down-regulation of FoxO3/Sirt1 signaling

Measles virus plays an important role as an environmental factor in the pathogenesis of Paget's disease (PD). Previous studies have shown that IL-6 is increased in the bone marrow of Paget's patients and that measles virus nucleocapsid protein (MVNP) induces IL-6 secretion by pagetic osteoclasts. Further, IL-6 plays a critical role in the development of pagetic osteoclasts and bone lesions induced by PD, but the mechanisms regulating IL-6 production by MVNP remain unclear. Our current studies revealed that MVNP expression in osteoclast precursors down-regulated Sirt1 mRNA and protein, a negative regulator of NF-κB activity, which is a key factor for IL-6 expression. MVNP expression in NIH3T3 cells also elevated Il-6 transcription and impaired the expression of Sirt1 mRNA both under basal conditions and upon activation of the Sirt1 upstream regulator FoxO3 by LY294002 (a PI3K/AKT inhibitor). Luciferase activity assays showed that constitutively active FoxO3 abolished the repressive effect of MVNP on reporters driven by either FoxO3 response elements or the Sirt1 promoter. Further, protein stability assays revealed that FoxO3 was degraded more rapidly in MVNP-expressing cells than in control cells following the addition of cycloheximide. Similarly, co-transfection of MVNP and FoxO3 into HEK293 cells demonstrated that MVNP decreased the protein levels of over-expressed FoxO3 in a dose-dependent manner. Treatment with the proteasome inhibitor, MG132, blocked the MVNP-triggered decrease of FoxO3, and the treatment with the serine/threonine phosphatase inhibitor, calyculin A, revealed that MVNP increased phosphorylation of FoxO3. Further, over-expression of Sirt1 or treatment with the Sirt1 activator resveratrol blocked the increase in Il-6 transcription by MVNP. Finally, resveratrol reduced the numbers of TRAP positive multi-nuclear cells in bone marrow cultures from TRAP-MVNP transgenic mice to wild type levels. These results indicate that MVNP decreases FoxO3/Sirt1 signaling to enhance the levels of IL-6, which in part mediate MVNP's contribution to the development of Paget's disease.

Effect of catch-up growth by various dietary patterns and resveratrol intervention on bone status

Catch-up growth (CUG) after food restriction can increase the risks for insulin resistance-related diseases, and to our knowledge, no previous studies have addressed how bone is influenced by CUG when refeeding diet content differs. The objective of this study was to investigate the bone status resulting from CUG induced by varying refeeding dietary patterns, and to assess the potential influencing factors and the effect of resveratrol on bone status during CUG. Experimental rats were randomly divided into five groups: normal chow (NC) group; CUG group (CUG, containing two subgroups, respectively, refeeding with normal chow or high-fat diet); high-fat diet (HF) group; and resveratrol intervention groups (CUGE and HFE). Bone parameters were detected by dual-energy X-ray absorptiometry. Serum concentrations of tumor necrosis factor (TNF)- α, body weight and food intake were also recorded. Our results showed that food restriction induced a significant decrease in bone parameters. Eight-week CUG by normal chow had a greater degree of improvement in bone mineral density than high-fat diet, and even returned to normal level similar to NC. Bone parameters were elevated in varying degrees in the HF group compared with the NC group. In the resveratrol intervention groups, bone parameters significantly increased. Furthermore, bone parameters were inversely related with serum TNF- α concentrations, but showed positive correlation with body weight. In conclusion, the study shows that CUG can partially reverse the deleterious effects of caloric restriction on bone health, especially in the refeeding with normal chow group. Moreover, resveratrol has a protective effect on bone status during the period of CUG. Serum TNF- α levels and body weight also seem to play an important role in regulating bone parameters.

The effect of antioxidants on the production of pro-inflammatory cytokines and orthodontic tooth movement

Orthodontic force causes gradual compression of the periodontal ligament tissues, which leads to local hypoxia in the compression side of the tissues. In this study, we investigated whether antioxidants exert a regulatory effect on two factors: the expression of pro-inflammatory cytokines in human periodontal ligament fibroblasts (PDLFs) that were exposed to mechanical compression and hypoxia and the rate of orthodontic tooth movement in rats. Exposure of PDLFs to mechanical compression (0.5-3.0 g/cm(2)) or hypoxic conditions increased the production of intracellular reactive oxygen species. Hypoxic treatment for 24 h increased the mRNA levels of IL-1β, IL-6 and IL-8 as well as vascular endothelial growth factor (VEGF) in PDLFs. Resveratrol (10 nM) or N-acetylcysteine (NAC, 20 mM) diminished the transcriptional activity of hypoxiainducible factor-1 and hypoxia-induced expression of VEGF. Combined treatment with mechanical compression and hypoxia significantly increased the expression levels of IL-1β, IL-6, IL-8, TNF-α and VEGF in PDLFs. These levels were suppressed by NAC and resveratrol. The maxillary first molars of rats were moved mesially for seven days using an orthodontic appliance. NAC decreased the amount of orthodontic tooth movement compared to the vehicle-treated group. The results from immunohistochemical staining demonstrated that NAC suppressed the expression of IL-1β and TNF-α in the periodontal ligament tissues compared to the vehicle-treated group. These results suggest that antioxidants have the potential to negatively regulate the rate of orthodontic tooth movement through the down-regulation of pro-inflammatory cytokines in the compression sides of periodontal ligament tissues.