Protective effects of resveratrol on osteoporosis via activation of the SIRT1-NF-κB signaling pathway in rats

Sirtuins: exploring next-gen therapeutics in the pathogenesis osteoporosis and associated diseases

OBJECTIVE

Osteoporosis poses a substantial public health challenge due to an ageing population and the lack of adequate treatment options. The condition is marked by a reduction in bone mineral density, resulting in an elevated risk of fractures. The reduction in bone density and strength, as well as musculoskeletal issues that come with aging, present a significant challenge for individuals impacted by these conditions, as well as the healthcare system worldwide.

METHODS

Literature survey was conducted until May 2023 using databases such as Web of Science, PubMed, Scopus, and Google Scholar.

RESULT

Sirtuins 1-7 (SIRT1-SIRT7), which are a group of Nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases, possess remarkable capabilities to increase lifespan and combat diseases related to aging. Research has demonstrated that these proteins play an important role in regular skeletal development and maintenance by directly impacting bone cells. Their dysfunction could be a factor in various bone conditions. Studies conducted on animals before clinical trials have shown that administering Sirtuins agonists to mice provides a safeguard against osteoporosis resulting from aging, menopause, and immobilization. These findings imply that Sirtuins may be a viable target for addressing the irregularity in bone remodeling and treating osteoporosis and other skeletal ailments.

CONCLUSION

The purpose of this review was to present a thorough and current evaluation of the existing knowledge on Sirtuins biology, with a particular emphasis on their involvement in maintaining bone homeostasis and contributing to osteoporosis. Additionally, the review examines potential pharmacological interventions targeting Sirtuins for the treatment of osteoporosis.

SIRT1 and ZNF350 as novel biomarkers for osteoporosis: a bioinformatics analysis and experimental validation

BACKGROUND

Osteoporosis (OP) is characterized by bone mass decrease and bone tissue microarchitectural deterioration in bone tissue. This study identified potential biomarkers for early diagnosis of OP and elucidated the mechanism of OP.

METHODS

Gene expression profiles were downloaded from Gene Expression Omnibus (GEO) for the GSE56814 dataset. A gene co-expression network was constructed using weighted gene co-expression network analysis (WGCNA) to identify key modules associated with healthy and OP samples. Functional enrichment analysis was conducted using the R clusterProfiler package for modules to construct the transcriptional regulatory factor networks. We used the "ggpubr" package in R to screen for differentially expressed genes between the two samples. Gene set variation analysis (GSVA) was employed to further validate hub gene expression levels between normal and OP samples using RT-PCR and immunofluorescence to evaluate the potential biological changes in various samples.

RESULTS

There was a distinction between the normal and OP conditions based on the preserved significant module. A total of 100 genes with the highest MM scores were considered key genes. Functional enrichment analysis suggested that the top 10 biological processes, cellular component and molecular functions were enriched. The Toll-like receptor signaling pathway, TNF signaling pathway, PI3K-Akt signaling pathway, osteoclast differentiation, JAK-STAT signaling pathway, and chemokine signaling pathway were identified by Kyoto Encyclopedia of Genes and Genomes pathway analysis. SIRT1 and ZNF350 were identified by Wilcoxon algorithm as hub differentially expressed transcriptional regulatory factors that promote OP progression by affecting oxidative phosphorylation, apoptosis, PI3K-Akt-mTOR signaling, and p53 pathway. According to RT-PCR and immunostaining results, SIRT1 and ZNF350 levels were significantly higher in OP samples than in normal samples.

CONCLUSION

SIRT1 and ZNF350 are important transcriptional regulatory factors for the pathogenesis of OP and may be novel biomarkers for OP treatment.

Oxyresveratrol attenuates bone resorption by inhibiting the mitogen-activated protein kinase pathway in ovariectomized rats

BACKGROUND

Bone is continuously produced by osteoblasts and resorbed by osteoclasts to maintain homeostasis. Impaired bone resorption by osteoclasts causes bone diseases such as osteoporosis and arthritis. Most pharmacological treatment of osteoporosis focuses on inhibiting osteoclast differentiation, often to restore osteoclast/osteoclast balance. However, recent osteoporosis treatments have various side effects. According to a recent study, resveratrol, known as a stilbenoid family, is known to increase bone density, and the osteoclast inhibitory effect was confirmed using oxyresveratrol, a stilbenoid family. Here, we investigated the effect of oxyresveratrol on osteoclast differentiation and an ovariectomized mouse model.

METHODS

Mouse leukemia monocyte/macrophage cell line RAW 264.7 was treated with oxyresveratrol, and cell cytotoxicity was confirmed by measuring MTT assay. Tartrate-resistant acid phosphatase (TRAP), an enzyme marker for osteoclasts, was confirmed by staining. In addition, osteoclast differentiation markers and MAPK-related markers were confirmed at the mRNA level and protein expression. The effect of oxyresveratrol was confirmed using ovariectomized mice. Deoxypyridinoline (DPD) was measured using mouse urine and TRAP activity was observed using serum. Bone mineral density was also measured using Micro-CT.

RESULTS

The polyphenol oxyresveratrol inhibited receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced osteoclast differentiation of RAW 264.7 cells. Furthermore, oxyresveratrol inhibited TRAP activity and actin-ring formation. Moreover, oxyresveratrol suppressed the phosphorylation of the RANKL-induced mitogen-activated protein kinases (MAPKs) p38, JNK, and ERK and significantly reduced the expression of bone differentiation markers (NFATc1, cathepsin K, and TRAP).

CONCLUSION

Oxyresveratrol inhibits osteoclast differentiation via MAPK and increases bone density in ovariectomized rats, suggesting it has therapeutic potential for bone diseases such as osteoporosis. We confirmed the osteoporosis prevention effect of OR in Raw 264.7 cells, and future studies should confirm the effect of OR using rat bone marrow-derived cells.

Daily supplement of sesame oil prevents postmenopausal osteoporosis via maintaining serum estrogen and aromatase levels in rats

Estrogen deficiency is one of the main causes of postmenopausal osteoporosis in elderly women. Hormone replacement therapy has been employed to manage postmenopausal osteoporosis; however, it has raised concerns related to heart attacks and breast cancer. Sesame oil has been reported to affect sex hormone status. The aim of the present study is to evaluate the effect of sesame oil supplement on postmenopausal osteoporosis in rats. We used female Sprague Dawley rats that underwent bilaterally ovariectomy (OVX) as an experimental postmenopausal osteoporosis animal model. These rats were orally administrated sesame oil (0.25 or 0.5 mL/kg/day) for four months as the therapeutic group. We assessed bone mineral density (BMD) and the levels of osteocalcin, procollagen-I C-terminal propeptide (PICP), collagen cross-linked N-telopeptide (NTx), estradiol, and aromatase in the sera. The daily supplementation of sesame oil significantly increased BMD, serum osteocalcin levels, and trabecular areas in the OVX-treated rats. Sesame oil also elevated serum PICP levels and decreased NTx levels in these rats. Furthermore, sesame oil effectively maintained serum estradiol and aromatase levels in the OVX-induced osteoporosis rats. In conclusion, daily supplementation of sesame oil prevents postmenopausal osteoporosis by maintaining serum estrogen and aromatase levels, while also modulating the imbalance between bone formation and resorption in osteoporosis rats.

SRT2183 and SRT1720, but not Resveratrol, Inhibit Osteoclast Formation and Resorption in the Presence or Absence of Sirt1

Background

Osteoclastic bone resorption markedly increases with aging, leading to osteoporosis characterized by weak and fragile bones. Mice exhibit greater bone resorption and poor bone mass when Sirt1 is removed from their osteoclasts. Here we investigated the ex vivo impacts of putative Sirt1 activators, Resveratrol (RSV), SRT2183, and SRT1720, on osteoclast formation and activity in primary mouse bone marrow cells (BMCs) derived from wild-type (WT) and osteoclast specific Sirt1 knockout (OC-Sirt1KO) mice and in the RAW264.7 mouse macrophage cell line.

Results

We found that SRT2183 and SRT1720 inhibit the formation of osteoclasts and actin belts in BMCs and RAW264.7 cells, whereas RSV does not. We also observed that the OC-Sirt1KO mice exhibited less bone mineral density, and the BMCs harvested from these mice yielded more osteoclasts than BMCs harvested from littermate controls. Interestingly, both SRT2183 and SRT1720 reduced osteoclast and actin belt formation in BMCs from OC-Sirt1KO mice. SRT2183 and SRT1720 also significantly disrupted actin belts of mature osteoclasts generated from BMCs of WT mice, within 3 and 6 hours of administration, respectively. Furthermore, these compounds inhibited the resorption activity of mature osteoclasts, while RSV did not.

Conclusion

Our findings suggest SRT2183 and SRT1720 impede bone resorption by disrupting actin belts of mature osteoclasts, inhibit actin belt formation, and inhibit osteoclastogenesis even in the absence of Sirt1. Thus, the mechanism of action of these compounds appears to extend beyond Sirt1 activation and possibly pave the way for potential new therapies in alleviating osteoporosis associated bone loss.

Resveratrol prevents ovariectomy-induced bone quality deterioration by improving the microarchitectural and biophysicochemical properties of bone

INTRODUCTION

Osteoporosis is a major health problem that is very common worldwide and is characterized by both low bone density and deterioration in bone quality. New treatment options without side effects have become an active area of research in recent years. This study was designed to investigate the preventive effects of resveratrol on bone quality deterioration caused by ovariectomy.

MATERIALS AND METHODS

Sixty rats were randomly divided into five groups (12 animals per group): Control, Sham-operated (SHAM), ovariectomized (OVX), OVX + Resveratrol-40 mg/kg/day (OVX + Res40), OVX + Resveratrol-80 mg/kg/day (OVX + Res80). Resveratrol was administered by oral gavage (40 and 80 mg/kg/day) for ten weeks. Micro-CT measurements, biomechanical testing, Raman spectroscopy analysis, and RT-PCR analysis were performed. ALP, OCN, TAS, and TOS levels were also measured from blood serum.

RESULTS

Bone strength, bone volume/total volume, trabecular volume, and trabecular thickness were higher in the OVX + RES-80 group than in the OVX group. Resveratrol increased osteogenic differentiation, as the expression of osteogenic markers ALP, Col1A1, Runx2, OPG, OCN increased in both OVX + RES-80 and OVX + RES-40 groups compared to the OVX group. 80 mg/kg/day resveratrol administration decreased the levels of ALP, OCN and TOS in ovariectomized rats. Raman spectroscopy findings showed a preventive effect of resveratrol administration against ovariectomy-induced deterioration in biophysiochemical properties of bone tissue.

CONCLUSION

This study revealed that administration of different doses of 80 mg/kg/day and 40 mg/kg/day of resveratrol had protective effects on bone quality deterioration caused by ovariectomy.

microRNA-29b-3p/sirtuin-1/peroxisome proliferator-activated receptor γ suppress osteogenic differentiation

Osteoporosis is described as an age-associated impairment of bone formation. microRNA (miR)-29b-3p was thought to be linked to osteoblast differentiation; however, the underlying molecular pathways are yet unknown. The study's goal was to look into the involvement of miR-29b-3p in osteoporosis and the pathophysiological mechanisms. A murine model of estrogen deficiency-induced bone loss was established to simulate postmenopausal osteoporosis. Reverse transcription-quantitative PCR (RT-qPCR) was performed to assess the level of miR-29b-3p of bone tissue. Additionally, miR-29b-3p/sirtuin-1 (SIRT1)/peroxisome proliferator-activated receptor γ (PPARγ) axis in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was examined. Osteogenesis-related markers, including alkaline phosphatase (ALP), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2), were assessed at protein and molecular levels. ALP staining and Alizarin Red staining were used to detect ALP activity and calcium deposition. The ovariectomy group was shown to express miR-29b-3p at higher levels in vitro, and miR-29b-3p mimics suppressed osteogenic differentiation and protein/mRNA expression levels of osteogenesis-related markers in vivo. SIRT1 was identified as a target of miR-29b-3p using luciferase reporter assays. Overexpression of SIRT1 reduced the inhibition of osteogenic differentiation by miR-29b-3p. Rosiglitazone, an activator of PPARγ signaling, was able to reverse the downregulation of the osteogenic differentiation of BMSCs and the protein expression of PPARγ caused by miR-29b-3p inhibitors. The results revealed that osteogenesis was suppressed by miR-29b-3p, which blocks the SIRT1/PPARγ axis. These results suggested that postmenopausal osteoporosis could be treated by targeting miR-29b-3p SIRT1/PPARγ.

The Effects of Nutrient Signaling Regulators in Combination with Phytocannabinoids on the Senescence-Associated Phenotype in Human Dermal Fibroblasts

Identifying effective anti-aging compounds is a cornerstone of modern longevity, aging, and skin-health research. There is considerable evidence of the effectiveness of nutrient signaling regulators such as metformin, resveratrol, and rapamycin in longevity and anti-aging studies; however, their potential protective role in skin aging is controversial. In light of the increasing appearance of phytocannabinoids in beauty products without rigorous research on their rejuvenation efficacy, we decided to investigate the potential role of phytocannabinoids in combination with nutrient signaling regulators in skin rejuvenation. Utilizing CCD-1064Sk skin fibroblasts, the effect of metformin, triacetylresveratrol, and rapamycin combined with phytocannabinoids on cellular viability, functional activity, metabolic function, and nuclear architecture was tested. We found triacetylresveratrol combined with cannabidiol increased the viability of skin fibroblasts (p < 0.0001), restored wound-healing functional activity (p < 0.001), reduced metabolic dysfunction, and ameliorated nuclear eccentricity and circularity in senescent fibroblasts (p < 0.01). Conversely, metformin with or without phytocannabinoids did not show any beneficial effects on functional activity, while rapamycin inhibited cell viability (p < 0.01) and the speed of wound healing (p < 0.001). Therefore, triacetylresveratrol and cannabidiol can be a valuable source of biologically active substances used in aging and more studies using animals to confirm the efficacy of cannabidiol combined with triacetylresveratrol should be performed.

Safety Evaluation of Natural Drugs in Chronic Skeletal Disorders: A Literature Review of Clinical Trials in the Past 20 years

Chronic skeletal disorders (CSDs), including degenerative diseases such as osteoporosis (OP) and autoimmune disorders, have become a leading cause of disability in an ageing society, with natural drugs being indispensable therapeutic options. The clinical safety evaluation (CSE) of natural drugs in CSDs has been given priority and has been intensively studied. To provide fundamental evidence for the clinical application of natural drugs in the elderly population, clinical studies of natural drugs in CSDs included in this review were selected from CNKI, Web of Science, PubMed, Science Direct and Google Scholar since 2001. Seventeen randomized controlled trials (RCTs) met our inclusion criteria: four articles were on OP, seven on osteoarthritis (OA), four on rheumatoid arthritis (RA) and two on gout. Common natural drugs used for the treatment of OP include Epimedium brevicornu Maxim [Berberidaceae], Dipsacus asper Wall ex DC [Caprifoliaceae] root, and Phalaenopsis cornu-cervi (Breda) Blume & Rchb. f[ Orchidaceae], which have been linked to several mild adverse reactions, such as skin rash, gastric dysfunction, abnormal urine, constipation and irritability. The safety of Hedera helix L [Araliaceae] extract, Boswellia serrata Roxb [Burseraceae] extract and extract from perna canaliculus was evaluated in OA and upper abdominal pain, and unstable movements were obsrerved as major side effects. Adverse events, including pneumonia, vomiting, diarrhoea and upper respiratory tract infection, were reported when RA was treated with Tripterygium wilfordii, Hook. F [Celastraceae][TwHF] polyglycosides and quercetin (Capsella bursa-pastoris (L.) Medik [Brassicaceae]). The present review aimed to summarize the CSE results of natural drugs in CSDs and could provide evidence-based information for clinicians.

Anti-osteoporosis Effect of Fisetin against Ovariectomy Induced Osteoporosis in Rats: In silico, in vitro and in vivo Activity

Osteoporosis is a bone related disease that is characterised by bone loss that further increases the susceptibility to bone fractures and bone frailty due to disturbances in the micro-architecture of bone tissue. Fisetin (flavonoids) exhibited anti-inflammatory and antioxidative stress effects against various diseases. In this protocol, we make an effort to comfort the anti-osteoporosis effect of fisetin against ovariectomy (OVX) induced osteoporosis. A docking study of fisetin and alendronate on the estrogen (α and β) and vitamin D receptors was carried out. SaOS-2 (osteoblast like human) cells were used for the estimation of cell proliferation. The OVX induced OVX model was used and three doses of fisetin and alendronate was given to rats till 16 weeks. The hormone levels, bone turnover markers and biochemical parameters were estimated. Fisetin was docked into estrogen (α and β) and vitamin D receptors, resulting in stable complexes with lower binding scores. Fisetin significantly (p < 0.001) exhibited the induction of cell proliferation against the SaOS-2 cells. OVX induced osteoporosis rats exhibited a suppression of body weight and uterus index, after the Fisetin treatment. Fisetin treatment significantly (p < 0.001) improved the level of bone mineral content (BMC), bone mineral density (BMD) and biochemical parameters such as energy, maximum load, stiffness, young modules, maximum stress and reduced the level of 1,25(OH) 2 D3 and E 2 . Fisetin treatment significantly (p < 0.001) declined the level of phosphorus (P), calcium (Ca) and boosted the level of VitD. Fisetin treatment significantly (p < 0.001) reduced the malonaldehyde (MDA) level and enhanced the glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) level in the bone, intestine and hepatic tissue. Fisetin treatment suppressed the cytokines, RANKL/OPG ratio, receptor activator of nuclear factor-κB ligand (RANKL) and improved the level of osteoprotegerin (OPG). The findings suggest that fisetin could be a beneficial phytoconstituent for the treatment and prevention of postmenopausal osteoporotic complications.

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.

Uncarboxylated osteocalcin promotes osteogenesis and inhibits adipogenesis of mouse bone marrow-derived mesenchymal stem cells via the PKA-AMPK-SIRT1 axis

Osteoporosis is a bone disease characterized by reduced bone density, thin cortical bone and large gaps in the bone's honeycomb structure, which increases the risk of bone fragility. Uncarboxylated osteocalcin (unOC), a vitamin K-dependent bone protein, is known to regulate carbohydrate and energy metabolism. A previous study demonstrated that unOC promotes the differentiation of mouse bone marrow-derived mesenchymal stem cells (BMSCs) into osteoblasts, but inhibits their differentiation into adipocytes. However, the underlying mechanism remains unknown. The present study showed that unOC regulated the differentiation potential of BMSCs via protein kinase A (PKA)/AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1) signaling. SIRT1, a member of the sirtuin family with deacetylation functions, was upregulated by unOC in BMSCs. Transfection analyses with SIRT1 small interfering RNA indicated that the unOC-induced differentiation shift in BMSCs required SIRT1. Examination of SIRT1 downstream targets revealed that unOC regulated the acetylation levels of runt-related transcription factor (RUNX) 2 and peroxisome proliferator-activated receptor γ (PPARγ). Therefore, unOC inhibited adipogenic differentiation by PPARγ acetylation and promoted osteogenic differentiation by RUNX2 deacetylation. Moreover, phosphorylated PKA and AMPK protein levels increased after unOC treatment, which led to the upregulation of SIRT1. Western blot analysis with PKA and AMPK inhibitors indicated that the PKA-AMPK signaling pathway functioned upstream of SIRT1 and positively regulated SIRT1 expression. These findings led us to propose a model in which unOC regulated BMSC osteogenic differentiation through the PKA-AMPK-SIRT1 axis, giving evidence towards the therapeutic potential of unOC in osteoporosis treatment.

Role of sirtuins in bone biology: Potential implications for novel therapeutic strategies for osteoporosis

The decline in bone mass and bone strength and musculoskeletal problems associated with aging constitute a major challenge for affected individuals and the healthcare system globally. Sirtuins 1-7 (SIRT1-SIRT7) are a family of nicotinamide adenine dinucleotide-dependent deacetylases with remarkable abilities to promote longevity and counteract age-related diseases. Sirtuin knockout and transgenic models have provided novel insights into the function and signaling of these proteins in bone homeostasis. Studies have revealed that sirtuins play a critical role in normal skeletal development and homeostasis through their direct action on bone cells and that their dysregulation might contribute to different bone diseases. Preclinical studies have demonstrated that mice treated with sirtuin agonists show protection against age-related, postmenopausal, and immobilization-induced osteoporosis. These findings suggest that sirtuins could be potential targets for the modulation of the imbalance in bone remodeling and treatment of osteoporosis and other bone disorders. The aim of this review was to provide a comprehensive updated review of the current knowledge on sirtuin biology, focusing specifically on their roles in bone homeostasis and osteoporosis, and potential pharmacological interventions targeting sirtuins for the treatment of osteoporosis.

Diosmetin reduces bone loss and osteoclastogenesis by regulating the expression of TRPV1 in osteoporosis rats

Background

Osteoporosis is a systemic skeletal disorder and occurs frequently in postmenopausal women and older men. This study aimed to examine whether diosmetin (DIO) can relieve estrogen deficiency—induced osteoporosis and to explore the underlying mechanisms of this potential effect.

Methods

Forty-nine Sprague-Dawley (SD) rats were divided into seven groups. Six groups underwent bilateral ovariectomy (OVX), while the sham group underwent ovarian exposure surgery. DIO and evodiamine were administered 3 days before surgery, and then subcutaneously every 3 days for 3 months in the following fashion: group I, DIO (100 mg/kg); group II, OVX; group III, OVX + DIO (50 mg/kg); group IV, OVX + DIO (100 mg/kg); group V, OVX + evodiamine (10 mg/kg) group; group VI, OVX + DIO (100 mg/kg) + evodiamine (10 mg/kg) group. Bone histopathological damage, bone loss, osteoclast production, and the expression level of transient receptor potential vanilloid 1 (TRPV1) were detected.

Results

Compared with the sham group, the expression of bone resorption–related genes, osteoclast-associated receptor (OSCAR) (1.00%±0.16% versus 4.5%±0.28%, **, P<0.01) and tartrate-resistant acid phosphatase (TRAP) (2.0%±0.6% versus 18.00±1.2%, ***, P<0.001), was increased significantly. The protein level of osteogenic marker proteins, osterix (Osx) (1.0%±0.1% versus 0.03%±0.01%, **, P<0.01) and type 1 collagen (COL1A1) (1.0%±0.13% versus 0.13%±0.05%, **, P<0.01) was decreased significantly with the increase of TRPV1 (1.0%±0.15% versus 2.89%±0.28%, **, P<0.01) protein level. Notably, DIO can alleviate some abnormal symptoms related to osteoporosis.

Conclusions

DIO can relieve typical osteoporosis symptoms in an OVX osteoporosis rat model. The underlying mechanism may be associated with the downregulation of TRPV1.

Advancements in therapeutic drugs targeting of senescence

Aging leads to a high burden on society, both medically and economically. Cellular senescence plays an essential role in the initiation of aging and age-related diseases. Recent studies have highlighted the therapeutic value of senescent cell deletion in natural aging and many age-related disorders. However, the therapeutic strategies for manipulating cellular senescence are still at an early stage of development. Among these strategies, therapeutic drugs that target cellular senescence are arguably the most highly anticipated. Many recent studies have demonstrated that a variety of drugs exhibit healthy aging effects. In this review, we summarize different types of drugs promoting healthy aging – such as senolytics, senescence-associated secretory phenotype (SASP) inhibitors, and nutrient signaling regulators – and provide an update on their potential therapeutic merits. Taken together, our review synthesizes recent advancements in the therapeutic potentialities of drugs promoting healthy aging with regard to their clinical implications.

Activation of FoxO1/SIRT1/RANKL/OPG pathway may underlie the therapeutic effects of resveratrol on aging-dependent male osteoporosis

Background

Age-dependent male osteoporosis remains a poorly studied medical problem despite its significance. It is estimated that at least 1 of 5 men will suffer from osteoporotic consequences. Given that multiple mechanisms are involved in the process of senescence, much attention has been given to compounds with polymodal actions. To challenge such a health problem, we tested here the therapeutic potential of resveratrol in male osteoporosis. We also studied the possible molecular mechanisms that may underlie resveratrol effects.

Methods

Thirty male Wistar albino rats were used in the present study. Rats were divided (10/group) into: control (3–4 months old weighing 150–200 g receiving vehicle), aged (18–20 months old, weighing 350–400 g and receiving vehicle), and resveratrol treated aged (18–20 months old, weighing 350–400 g and receiving resveratrol 20 mg/kg/day for 6 weeks) groups. Assessment of serum calcium, phosphate, bone specific alkaline phosphatase, inflammatory cytokines, oxidative stress markers, and rat femur gene expression of FoxO1, SIRT1, RANKL and OPG proteins was carried out. Histopathological assessment of different levels of rat femur was also performed.

Results

Age-dependent osteoporosis resulted in significant increase in serum levels of phosphate, bone specific alkaline phosphatase, hsCRP, IL-1β, IL-6, TNF-α, MDA, NO, and RANKL gene expression. However, there was significant decrease in serum level of GSH, and gene expression of FoxO1, SIRT1 and OPG. Osteoporotic changes were seen in femur epiphysis, metaphysis and diaphysis. Resveratrol restored significantly age-dependent osteoporotic changes.

Conclusion

We concluded that resveratrol can play an important role in the prevention of male osteoporosis. Resveratrol can counter the molecular changes in male osteoporosis via anti-inflammatory, anti-oxidant and gene modifying effects.

Resveratrol promotes osteoblastic differentiation in a rat model of postmenopausal osteoporosis by regulating autophagy

OBJECTIVE

Resveratrol is a natural polyphenolic compound that ameliorates postmenopausal osteoporosis by activating the estrogen receptor. Research has shown that resveratrol exhibits some type of estrogen receptor agonist activity, reducing the risk of breast cancer. However, its mechanism of action remains largely unknown. This study aims to investigate the effect of resveratrol on osteoblastic and osteoclastic differentiation and its potential role in the regulation of autophagy.

METHODS

Sprague Dawley (SD) rats underwent ovariectomies (OVX) and were administered resveratrol (at 10, 20 or 40 mg/kg/d) for 8 weeks. The calcium content and the bone mineral density (BMD) were measured in the lumbar vertebrae (L3) and the right distal femur-tibia bone region. The osteoblasts and osteoclasts were isolated from rat lumbar vertebrae by enzyme digestion and bone marrow induction, respectively. The cells were then cultured with resveratrol in combination with bafilomycin or leupeptin to inhibit or activate autophagy, respectively. Western blotting was used to assess the differentiation markers and autophagy-related genes in the osteoblasts and osteoclasts.

RESULTS

Compared to the sham group, the bone calcium content and BMD were significantly decreased in the OVX group (p < 0.05), while resveratrol attenuated these in a dose-dependent manner. In the osteoblasts, vascular endothelial growth factor (VEGF), and alpha-1 type I collagen (COL1A1) were markedly decreased, and in osteoclasts, the receptor activator of nuclear factor-κB ligand (RANKL) was increased in the OVX group, while resveratrol reversed this pattern in a dose-dependent manner. The inhibition of autophagy in osteoblasts and its activation in osteoclasts was observed in the OVX group. However, with resveratrol, this was reversed in a dose-dependent manner.

CONCLUSION

Overall, resveratrol promotes osteoblastic differentiation and suppresses osteoclastic differentiation in a rat model with postmenopausal osteoporosis by regulating autophagy.

Anti-aging Effects of Calorie Restriction (CR) and CR Mimetics based on the Senoinflammation Concept

Chronic inflammation, a pervasive feature of the aging process, is defined by a continuous, multifarious, low-grade inflammatory response. It is a sustained and systemic phenomenon that aggravates aging and can lead to age-related chronic diseases. In recent years, our understanding of age-related chronic inflammation has advanced through a large number of investigations on aging and calorie restriction (CR). A broader view of age-related inflammation is the concept of senoinflammation, which has an outlook beyond the traditional view, as proposed in our previous work. In this review, we discuss the effects of CR on multiple phases of proinflammatory networks and inflammatory signaling pathways to elucidate the basic mechanism underlying aging. Based on studies on senoinflammation and CR, we recognized that senescence-associated secretory phenotype (SASP), which mainly comprises cytokines and chemokines, was significantly increased during aging, whereas it was suppressed during CR. Further, we recognized that cellular metabolic pathways were also dysregulated in aging; however, CR mimetics reversed these effects. These results further support and enhance our understanding of the novel concept of senoinflammation, which is related to the metabolic changes that occur in the aging process. Furthermore, a thorough elucidation of the effect of CR on senoinflammation will reveal key insights and allow possible interventions in aging mechanisms, thus contributing to the development of new therapies focused on improving health and longevity.

Prediction of pivotal pathways and hub genes associated with osteoporosis by Gibbs sampling

Osteoporosis (OP) is a common metabolic bone disease with high incidence, and is recognized as a major public health problem worldwide. It is essential to clarify the pathogenesis of the disease for improving the diagnosis, prevention and treatment of OP. The aim of this study was to clarify the pivotal pathways and hub genes in OP using Gibbs sampling. The gene expression profile datasets were obtained from Gene Expression Omnibus (GEO) database. The pathways were enriched by Kyoto Encyclopedia of Genes and Genomes (KEGG) with genes intersection ≥5 based on gene expression profile data. Then, the acquired pathways were converted into Markov chains (MC). Gibbs sampling was conducted to obtain a new MC. In addition, the average probabilities of each pathway in two states containing human mesenchymal stem cells (hMSC) _middle-aged and hMSC_elderly were calculated through Markov chain Monte Carlo (MCMC) algorithm. Moreover, gene expression variation was taken into account to adjust the probability. Pivotal pathways were identified under adjusted posterior value >0.8. Then, Gibbs sampling was implemented to find hub genes from pathways. There were 280 pathways determined by the gene intersection ≥5. Gibbs sampling identified two disturbed pathways (pathways in cancer and influenza A) and two hub genes (cyclin A1 and WNT2) under the adjusted probability >0.8. Gene expression analysis showed that all the disturbed pathways and hub genes had increased expression levels in hMSC_middle-aged samples compared with hMSC_elderly samples. We identified two pivotal pathways and two hub genes in OP using Gibbs sampling. The results contribute to the understanding of underlying pathogenesis and could be considered as potential biomarkers for the therapy of OP.

Bone Health and Natural Products- An Insight

Bone metabolism involves a complex balance between matrix deposition, mineralization, and resorption. Numerous evidences have revealed that dietary components and phytoconstituents can influence these processes, through inhibition of bone resorption, thus exhibiting beneficial effects on the skeleton. Various traditional herbal formulae in ayurvedic and Chinese medicine have shown demonstrable benefits in pharmacological models of osteoporosis. The present review discusses normal bone metabolism and disorders caused by bone disruption, with particular reference to osteoporosis and current therapeutic treatment. Furthermore the effects of constituents from natural products on bone tissue are explained, with relevant evidences of efficacy in various experimental models.

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.