Curcumin (diferuloylmethane) inhibits receptor activator of NF-kappa B ligand-induced NF-kappa B activation in osteoclast precursors and suppresses osteoclastogenesis

Changes in gene expression in human skeletal stem cells transduced with constitutively active Gsα correlates with hallmark histopathological changes seen in fibrous dysplastic bone

Fibrous dysplasia (FD) of bone is a complex disease of the skeleton caused by dominant activating mutations of the GNAS locus encoding for the α subunit of the G protein-coupled receptor complex (Gsα). The mutation involves a substitution of arginine at position 201 by histidine or cysteine (Gsα^{R201H or R201C}), which leads to overproduction of cAMP. Several signaling pathways are implicated downstream of excess cAMP in the manifestation of disease. However, the pathogenesis of FD remains largely unknown. The overall FD phenotype can be attributed to alterations of skeletal stem/progenitor cells which normally develop into osteogenic or adipogenic cells (in cis), and are also known to provide support to angiogenesis, hematopoiesis, and osteoclastogenesis (in trans). In order to dissect the molecular pathways rooted in skeletal stem/progenitor cells by FD mutations, we engineered human skeletal stem/progenitor cells with the Gsα^R201C mutation and performed transcriptomic analysis. Our data suggest that this FD mutation profoundly alters the properties of skeletal stem/progenitor cells by pushing them towards formation of disorganized bone with a concomitant alteration of adipogenic differentiation. In addition, the mutation creates an altered in trans environment that induces neovascularization, cytokine/chemokine changes and osteoclastogenesis. In silico comparison of our data with the signature of FD craniofacial samples highlighted common traits, such as the upregulation of ADAM (A Disintegrin and Metalloprotease) proteins and other matrix-related factors, and of PDE7B (Phosphodiesterase 7B), which can be considered as a buffering process, activated to compensate for excess cAMP. We also observed high levels of CEBPs (CCAAT-Enhancer Binding Proteins) in both data sets, factors related to browning of white fat. This is the first analysis of the reaction of human skeletal stem/progenitor cells to the introduction of the FD mutation and we believe it provides a useful background for further studies on the molecular basis of the disease and for the identification of novel potential therapeutic targets.

Curcumin-activated autophagy plays a negative role in its anti-osteoclastogenic effect

BACKGROUND/PURPOSE

It remains unclear what role curcumin plays in the autophagy of osteoclast precursors (OCPs) during osteoclastogenesis, since some researchers found that curcumin has the ability to inhibit osteoclastogenesis. While others have considered it as an autophagy activator. This study aimed to determine the effect of curcumin-regulated autophagy on osteoclastogenesis.

RESULTS

The results revealed that direct administration of curcumin enhanced the OCP autophagy response in bone marrow-derived macrophages (BMMs). Curcumin could also abate RANKL's stimulatory effect on OCP autophagy and osteoclastogenesis. Autophagic suppression related to pharmacological inhibitors or gene silencing could further enhance the inhibitory effect of curcumin on osteoclastogenesis. As expected, curcumin ameliorated ovariectomy (OVX)-induced bone loss and its effect could be promoted by an autophagy inhibitor (chloroquine).

CONCLUSIONS

In conclusion, curcumin can directly enhance the autophagic activity of OCPs, which inhibits its anti-osteoclastogeneic effects. Autophagy inhibition-based drugs are expected to enhance curcumin's efficacy in treating osteoporosis.

Recovery Of Bone And Muscle Mass In Patients With Chronic Kidney Disease And Iron Overload On Hemodialysis And Taking Combined Supplementation With Curcumin And Resveratrol

Introduction

Malnutrition is common in haemodialysis patients and closely related to morbidity and mortality. We evaluated the effect of twelve weeks of supplementation with resveratrol and curcumin on recovery of bone and muscle mass and protein oxidation, lipid peroxidation on patients with chronic kidney disease and iron overload undergoing hemodialysis, we performed a randomized, double-blind, placebo-controlled trial.

Methods

We included a total of 40 patients, were randomly assigned to two groups, 20 to the group with antioxidant supplementation (Resveratrol + Curcumin) (Group A), treated with a daily oral dose of 500 mg of Resveratrol and 500 mg of Curcumin, and 20 to the control group treated with placebo (Group B).

Results

Significant differences were found in the body composition of the patients between both groups. There was a significant difference in Body Mass Index (BMI) values (p = 0.002), fat percentage (p = 0.007), muscle mass (p = 0.01) bone mass (p = 0.01), as well as in the score of the subjective global evaluation (p = 0.03). Also differences were found between the basal and final serum levels of Triglycerides (TG) (p = 0.01), VLDL (p = 0.003). A significant decrease in the levels of serum ferritin (2003.69 ± 518.73 vs 1795.65 ± 519.00 ng/mL; p = 0.04). Nor were significant differences observed between the baseline and the final Thiobarbituric Acid Reactive Substances (TBARS) values (70.45 ± 69.21 vs 50.19 ± 32.62, p = 0.24). The same results was obtained for carbonyl values (2.67 ± 0.75 vs 2.50 ± 0.85; p = 0.50).

Discussion

The present study is the first assay on patients with chronic kidney disease and iron overload that demonstrates the beneficial effects of combined supplementation with Curcumin and Resveratrol on muscle and bone mass. There was a significant decrease in circulating levels of ferritin, to finding that remarkably novel.

Effects of somatostatin, curcumin, and quercetin on the fatty acid profile of breast cancer cell membranes

Breast cancer is a worldwide commonly found malignancy in women and effective treatment is regarded as a huge clinical challenge even in the presence of several treatment options. Extensive literature is available demonstrating polyphenols as phytopharmaceutical anticancer agents. Among the polyphenols, quercetin and curcumin have been reported to have a strong potential against breast cancer. However, so far, no comprehensive study has been performed to demonstrate the anticarcinogenic effects of curcumin, quercetin, and their combinations with somatostatin on the fatty acid profile of breast cancer cell membranes. We used MCF-7 and MDA-MB231 breast cancer cells incubated with curcumin and quercetin for 24 h, in the absence and presence of somatostatin, at their EC₅₀ concentrations to evaluate membrane fatty acid based functional lipidomics together with the followup of EGFR and MAPK signaling pathways. The two cell lines gave different membrane free fatty acid reorganization. In MCF-7 cells, the following changes were observed: an increase of ω6 linoleic acid in the cells incubated with somatostatin + quercetin and quercetin and a decrease of ω3 acids in the cells incubated with somatostatin + curcumin compared to somatostatin and significant increases of monounsaturated fatty acid (MUFA), mono-trans arachidonic acid levels and docosapentaenoic acid for the cells incubated with somatostatin + quercetin compared to the control cells. In MDA-MB231 cells, incubations with curcumin, quercetin, and somatostatin + quercetin induced the most significant membrane remodeling with the increase of stearic acid, diminution of ω6 linoleic, arachidonic acids, and ω3 (docosapentaenoic and docosahexaenoic acids). Distinct signaling pathway changes were found for these cell lines. In MCF-7 cells, separate or combined incubations with somatostatin and quercetin, significantly decreased EGFR and incubation with curcumin decreased MAPK signaling. In MDA-MB231 cells, incubation with curcumin decreased AKT1 and p-AKT1 (Thr308) levels. Incubation with curcumin and quercetin decreased the EGFR levels. Our results showed that cytostatic and antioxidant treatments can be combined to induce membrane fatty acid changes, including lipid isomerization as specific free radical driven process, and to influence signaling pathways. This study aimed to contribute to the literature on these antioxidants in the treatment of breast cancer to clarify the effects and mechanisms in combination with somatostatin.

Artemisinin inhibits breast cancer-induced osteolysis by inhibiting osteoclast formation and breast cancer cell proliferation

In addition to being used to treat malaria, artemisinin (Art) can be used as an anti-inflammatory and antitumor agent. In this study, we evaluated the effects of Art on osteoclast formation and activation and on the development of breast cancer cells in bone. To evaluate the effect of Art on osteoclast differentiation in vitro, we treated bone marrow-derived macrophages (BMMs) with various concentrations of Art and evaluated the expression of genes and proteins involved in osteoclast formation. We also performed cell counting kit-8 assays to evaluate the toxicity of Art in BMMs and MDA-MB-231 cells. We also performed Transwell assays, wound-healing assays, colony formation assays, and cell apoptosis assays to evaluate the effect of Art in MDA-MB-231 cells. We also evaluated the effect of Art in an in vivo osteoclast bone resorption assay using a nude mouse model. We demonstrated that Art inhibits the differentiation and establishment of osteoclasts even though Art is not toxic to osteoclasts. In addition, Art reduced expression of genes involved in osteoclast formation and inhibited osteoclast bone resorption in a concentration-dependent manner. Based on our data, we believe that Art can inhibit proliferation of breast cancer cells by activating apoptosis pathways, and inhibit osteoclast formation and differentiation by inhibiting activation of cathepsin K, ATPase H+ transporting V0 subunit D2, nuclear factor of activated T cells 1, calcitonin receptor, and tartrate-resistant acid phosphatase and by inhibiting nuclear factor-κB activation.

Comparison between curcumin and all-trans retinoic acid in the osteogenic differentiation of mouse bone marrow mesenchymal stem cells

The use of bone marrow mesenchymal stem cells (BMSCs) has great potential in cell therapy, particularly in the orthopedic field. BMSCs represent a valuable renewable cell source that have been successfully utilized to treat damaged skeletal tissue and bone defects. BMSCs can be induced to differentiate into osteogenic lineages via the addition of inducers to the growth medium. The present study examined the effects of all-trans retinoic acid (ATRA) and curcumin on the osteogenic differentiation of mouse BMSCs. Morphological changes, the expression levels of the bone-associated gene markers bone morphogenetic protein 2, runt-related transcription factor and osterix during differentiation, an in vitro mineralization assay, and changes in osteocalcin expression revealed that curcumin supplementation promoted the osteogenic differentiation of BMSCs. By contrast, the application of ATRA increased osteogenic differentiation during the early stages, but during the later stages, it decreased the mineralization of differentiated cells. In addition, to the best of our knowledge, the present study is the first to examine the effect of curcumin on the osteogenic potency of mouse embryonic fibroblasts (MEFs) after reprogramming with human lim mineralization protein (hLMP-3), which is a positive osteogenic regulator. The results revealed that curcumin-supplemented culture medium increased hLMP-3 osteogenic potency compared with that of MEFs cultured in the non-supplemented medium. The present results demonstrate that enrichment of the osteogenic culture medium with curcumin, a natural osteogenic inducer, increased the osteogenic differentiation capacity of BMSCs as well as that of MEFs reprogrammed with hLMP-3.

Diallyl disulfide alleviates inflammatory osteolysis by suppressing osteoclastogenesis via NF-κB-NFATc1 signal pathway

Skeletal homeostasis is closely effectuated by the regulation of bone formation and bone resorption. Osteoclasts are multinuclear giant cells responsible for bone resorption. Overactivated osteoclasts and excessive bone resorption result in various lytic bone diseases, such as osteoporosis, osteoarthritis, periprosthetic infection, and inflammatory aseptic loosening of orthopedic implants. In consideration of the severe side effects caused by the currently available drugs, exploitation of novel drugs has gradually attracted attention. Because of its anti-inflammatory, antioxidant, and antitumor capacities, diallyl disulfide (DADS), a major oil-soluble organosulfur ingredient compound derived from garlic, has been widely researched. However, the effects of DADS on osteoclasts and lytic bone diseases are still unknown. In this study, we investigated the effects of DADS on receptor activator of NF-κB ligand (RANKL)- and LPS-mediated osteoclastogenesis, LPS-stimulated proinflammatory cytokines related to osteoclasts, and LPS-induced inflammatory osteolysis. The results showed that DADS significantly inhibited RANKL-mediated osteoclast formation, fusion, and bone resorption in a dose-dependent manner via inhibiting the NF-κB and signal transducer and activator of transcription 3 signaling and restraining the interaction of NF-κB p65 with nuclear factor of activated T cells cytoplasmic 1. Furthermore, DADS also markedly suppressed LPS-induced osteoclastogenesis and reduced the production of proinflammatory cytokines with LPS stimulation to indirectly mediate osteoclast formation. Consistent with the in vitro results, DADS prevented the LPS-induced severe bone loss by blocking the osteoclastogenesis. All of the results indicate that DADS may be a potential and exploitable drug used for preventing and impeding osteolytic lesions.-Yang, J., Tang, R., Yi, J., Chen, Y., Li, X., Yu, T., Fei, J. Diallyl disulfide alleviates inflammatory osteolysis by suppressing osteoclastogenesis via NF-κB-NFATc1 signal pathway.

Ursolic Acid Prevents Retinoic Acid-Induced Bone Loss in Rats

OBJECTIVE

To examine the effects of ursolic acid (UA) on mitigating retinoic acid (RA)-induced osteoporosis in rats.

METHODS

Fifty female Sprague-Dawley rats were randomly divided into the control group (n=10) and the osteoporosis group (n=40). The 40 osteoporosis rats were induced by 75 mg/(kg•d) RA once daily for 2 weeks, and then were randomly assigned to vehicle control (model), low-, middle-, and high-dose UA [(UA-L, UA-M, UA-H; 30, 60, 120 mg/(kg•d), respectively] groups (10 rats each). UA were administered once daily to the rats from the 3rd weeks for up to 4 weeks by gavage. Bone turnover markers [serum alkaline phosphatase (ALP), osteocalcin (OCN), urine deoxypyridinoline (DPD)] and other parameters, including serum calcium (S-Ca), serum phosphorus (S-P), urine calcium (U-Ca), urine phosphorus (U-P), and bone mineral density (BMD) of the femur, 4th lumbar vertebra and tibia, bone biomechanical properties and trabecular microarchitecture, were measured.

RESULTS

The osteoporosis in rats was successfully induced by RA. Compared with the model group, UA-M and UA-H significantly reversed the RA-induced changes in S-P, U-Ca, U-P, ALP, OCN and urine DPD ratio and markedly enhanced the BMD of right femur, 4th lumbar vertebra and tibia (Plt;0.05 or Plt;0.01). Further, biomechanical test and microcomputed tomography evaluation also showed that UA-H drastically improved biomechanical properties and trabecular microarchitecture (Plt;0.05 or Plt;0.01).

CONCLUSION

UA could promote bone formation, increase osteoblastic activity and reduce osteoclastic activity in rats, indicating that UA might be a potential therapeutic of RA-induced acute osteoporosis.

Curcumin in tissue engineering: A traditional remedy for modern medicine

Curcumin is the principal polyphenolic compound present in turmeric with broad applications in tissue engineering and regenerative medicine. It has some important inherent properties with the potential to facilitate tissue healing, including anti-inflammatory, anti-oxidant, and antibacterial activities. Therefore, curcumin has been used for the treatment of various damaged tissues, especially wound injuries. There are different forms of curcumin, among which nano-formulations are of a great importance in regenerative medicine. It is also important to design sophisticated delivery systems for controlled/localized delivery of curcumin to the target tissues and organs. Although there are many reports on the advantages of this compound, further research is required to fully explore its clinical usage. The review describes the physicochemical and biological properties of curcumin and the current state of the evidence on its applications in tissue engineering. © 2018 BioFactors, 45(2):135-151, 2019.

(-)-Epigallocatechin-3-Gallate Decreases Osteoclastogenesis via Modulation of RANKL and Osteoprotegrin

Osteoporosis is the second most common epidemiologic disease in the aging population worldwide. Previous studies have found that frequent tea drinkers have higher bone mineral density and less hip fracture. We previously found that (-)-epigallocatechin gallate (EGCG) (20⁻100 µmol/L) significantly suppressed receptor activator of nuclear factor-kB ligand (RANKL)-induced osteoclastogenesis and pit formation via inhibiting NF-κB transcriptional activity and nuclear transport of NF-κB in RAW 264.7 cells and murine primary bone marrow macrophage cells. The most important regulation in osteoclastogenesis is the receptor activator of nuclear factor-kB/RANKL/osteoprotegrin (RANK/RANKL/OPG) pathway. In this study, we used the coculture of RAW 264.7 cells and the feeder cells, ST2, to evaluate how EGCG regulated the RANK/RANKL/OPG pathway in RAW 264.7 cells and ST2 cells. We found EGCG decreased the RANKL/OPG ratio in both mRNA expression and secretory protein levels and eventually decreased osteoclastogenesis by TRAP (+) stain osteoclasts and TRAP activity at low concentrations-1 and 10 µmol/L-via the RANK/RANKL/OPG pathway. The effective concentration can be easily achieved in daily tea consumption. Taken together, our results implicate that EGCG could be an important nutrient in modulating bone resorption.

Protection Effect of Curcumin for Macrophage-Involved Polyethylene Wear Particle-Induced Inflammatory Osteolysis by Increasing the Cholesterol Efflux

BACKGROUND Periprosthetic osteolysis, induced by wear particles and inflammation, is a common reason for failure of primary arthroplasty. Curcumin, a nature phenol from plants, has been reported to reduce the inflammation in macrophages. This study aimed to investigate the potential effect of curcumin on macrophage involved, wear particle-induced osteolysis and its mechanism. MATERIAL AND METHODS RAW264.7 macrophages were used to test the effects of polyethylene (PE) particles and curcumin on macrophage cholesterol efflux and phenotypic changes. A mouse model of PE particle-induced calvarial osteolysis was established to test the effects of curcumin in vivo. After 14 days of treatment, the bone quality of the affected areas was analyzed by micro-computed tomography (micro-CT) and histology, and the bone surrounding soft tissues were analyzed at the cellular and molecular levels. RESULTS We found that PE particles can stimulate osteoclastogenesis and produce an M1-like phenotype in macrophages in vitro. Curcumin enhanced the cholesterol efflux in macrophages, and maintained the M0-like phenotype under the influence of PE particles in vitro. Additionally, the cholesterol transmembrane regulators ABCA1, ABCG1, and CAV1 were enhanced by curcumin in vivo. We also found enhanced bone density, reduced osteoclastogenesis, and fewer inflammatory responses in the curcumin treated groups in our mouse osteolysis model. CONCLUSIONS Our study findings indicated that curcumin can inhibit macrophage involved osteolysis and inflammation via promoting cholesterol efflux. Maintaining the cholesterol efflux might be a potential strategy to prevent periprosthetic osteolysis after total joint arthroplasty surgery.

Modulatory Effects of Plant Polyphenols on Bone Remodeling: A Prospective View From the Bench to Bedside

During the past, a more comprehensive knowledge of mechanisms implicated in bone resorption processes has driven researchers to develop a compound library of many small molecules that specifically interfere with the genesis of osteoclast precursors cells. Natural compounds that suppress osteoclast commitment may have therapeutic value in treating pathologies associated with bone resorption like osteoporosis, rheumatoid arthritis, bone metastasis, and periodontal disease. The present review is focused on the current knowledge on the polyphenols derived from plants that could be efficacious in suppressing osteoclast differentiation and bone resorption.

Dose-response assessment of chemically modified curcumin in experimental periodontitis

BACKGROUND

CMC2.24, a novel tri-ketonic chemically modified compound based on natural di-ketonic curcumin, has been shown to reduce bone loss and inflammatory mediators in experimental periodontitis, however, a potential dose-response relationship was not determined. The purpose of this study was to assess the effects of different doses of CMC2.24 on inflammation and bone resorption in vivo and also to describe on the effects of CMC2.24 on macrophage response.

METHODS

CMC2.24 was administered daily to animals for 28 days by oral gavage, at the following doses: 0 (control), 1, 3, 10, and 30 mg/kg of body weight. Experimental periodontitis was induced by injections of lipopolysaccharide (LPS) into the gingival tissues. Outcomes assessed were bone resorption, detection of tartrate-resistant acid phosphatase, and determination of gene expression. In vitro, macrophages (RAW264.7) were treated with different concentrations of CMC2.24: 1, 3, 10, and 30 μM and then subjected to different activation stimuli. Gene expression, phagocytic activity, production of reactive oxygen species (ROS) and cytokine production were evaluated.

RESULTS

CMC2.24 inhibited bone resorption, osteoclastogenesis, and tumor necrosis factor (TNF)-α expression in vivo. These beneficial responses reached maximum levels at a dose of 1 mg/kg, i.e. no dose-dependent effect. In vitro, CMC2.24 reduced the production of TNF-α and interleukin-10, inhibited phagocytic activity and stimulated production of ROS. A dose-dependent effect was observed only for ROS production.

CONCLUSION

Low doses of CMC2.24 (1 mg/kg/day) administered orally were sufficient to significantly inhibit alveolar bone resorption associated with the experimental periodontal disease; whereas in vitro macrophage inflammatory gene expression and phagocytosis were reduced, whereas production of ROS was stimulated.

Combination therapy of curcumin and alendronate modulates bone turnover markers and enhances bone mineral density in postmenopausal women with osteoporosis

OBJECTIVE

This study evaluated the effects of combination therapy of curcumin and alendronate on BMD and bone turnover markers in postmenopausal women with osteoporosis.

SUBJECTS AND METHODS

In a randomized, double-blind trial study, 60 postmenopausal women were divided into three groups: control, alendronate, and alendronate + curcumin. Each group included 20 patients. Total body, total hip, lumbar spine and femoral neck BMDs were measured by dual-energy X-ray absorptiometry (DXA) at baseline and after 12 months of therapy. Bone turnover markers such as bone-specific alkaline phosphatase (BALP), osteocalcin and C-terminal cross-linking telopeptide of type I collagen (CTx) were measured at the outset and 6 months later.

RESULTS

Patients in the control group suffered a significant decrease in BMD and increased bone turnover markers at the end of study. The group treated with only alendronate showed significantly decreased levels of BALP and CTx and increased levels of osteocalcin compared to the control group. The alendronate group also showed significant increases in the total body, total hip, lumbar spine and femoral neck BMDs at the end of study compared to the control group. In the curcumin + alendronate group, BALP and CTx levels decreased and osteocalcin levels increased significantly at the end of study compared to the control and alendronate groups. BMD indexes also increased in four areas significantly at the end of study compared to the control and alendronate groups.

CONCLUSION

The combination of curcumin and alendronate has beneficial effects on BMD and bone turnover markers among postmenopausal women with osteoporosis. Arch Endocrinol Metab. 2018;62(4):438-45.

Efficacy of curcumin and Boswellia for knee osteoarthritis: Systematic review and meta-analysis

PURPOSE

The unfavorable safety profiles of commonly prescribed knee osteoarthritis (OA) treatments have led clinicians and patients to seek safer alternatives. Research has suggested that curcuminoid and boswellia formulations could moderate key inflammatory pathways that are associated with worsening symptoms and disease progression. We conducted a systematic review and meta-analysis to assess the efficacy and safety of these treatments vs. placebo or NSAIDs for knee OA.

METHODS

We searched Medline, EMBASE, Google Scholar, Web of Science and the Cochrane database from inception to February 21, 2018. We also hand searched reference lists and reviewed conference proceedings. We included randomized clinical trials (RCTs) comparing curcuminoid or boswellia formulations with placebo or NSAIDs for knee OA. We calculated standardized mean differences (SMD) or risk ratios (RR) for all relevant outcomes. Meta-analyses were conducted using random effects models. Heterogeneity was assessed using the I2 statistic.

RESULTS

Eleven RCTs (N = 1009) were eligible for analysis. Study quality was low overall, and most included RCTs were conducted on fewer than 100 participants. Both curcuminoid and boswellia formulations were statistically significantly more effective than placebo for pain relief and functional improvement. There were no significant differences between curcuminoids or boswellia and placebo in safety outcomes. Curcuminoids showed no statistically significant differences in efficacy outcomes compared to NSAIDs; patients receiving curcuminoids were significantly less likely to experience gastrointestinal adverse events. No RCTs compared boswellia against approved NSAIDs.

CONCLUSIONS

The results of our study suggest that curcuminoid and boswellia formulations could be a valuable addition to the knee OA treatment regimens by relieving symptoms while reducing safety risks. The current body of evidence is not adequate in size or quality to make any meaningful clinical practice recommendations. Further research through large, high quality RCTs probably investigating the synergistic effect of these products with other OA treatments is warranted.

Various roles of heme oxygenase-1 in response of bone marrow macrophages to RANKL and in the early stage of osteoclastogenesis

Heme oxygenase-1 (HO-1; encoded by Hmox1), a downstream target of the Nrf2 transcription factor, has been postulated to be a negative regulator of osteoclasts (OCLs) differentiation. Here, we further explored such a hypothesis by examining HO-1 effects in different stages of osteoclastogenesis. We confirmed the inhibition of the expression of OCLs markers by Nrf2. In contrast, both the lack of the active Hmox1 gene or HO-1 silencing in OCLs precursor cells, bone marrow macrophages (BMMs), decreased their differentiation towards OCLs, as indicated by the analysis of OCLs markers such as TRAP. However, no effect of HO-1 deficiency was observed when HO-1 expression was silenced in BMMs or RAW264.7 macrophage cell line pre-stimulated with RANKL (considered as early-stage OCLs). Moreover, cobalt protoporphyrin IX (CoPPIX) or hemin, the known HO-1 inducers, inhibited OCLs markers both in RANKL-stimulated RAW264.7 cells and BMMs. Strikingly, a similar effect occurred in HO-1^-/- cells, indicating HO-1-independent activity of CoPPIX and hemin. Interestingly, plasma of HO-1^-/- mice contained higher TRAP levels, which suggests an increased number of bone-resorbing OCLs in the absence of HO-1 in vivo. In conclusion, our data indicate that HO-1 is involved in the response of bone marrow macrophages to RANKL and the induction of OCLs markers, but it is dispensable in early-stage OCLs. However, in vivo HO-1 appears to inhibit OCLs formation.

Effects of Curcumin on Bone Loss and Biochemical Markers of Bone Turnover in Patients with Spinal Cord Injury

BACKGROUND

Osteoporosis is one of the most common problems of patients with spinal cord injuries (SCIs). The current study aimed to evaluate the antiosteoporotic effects of curcumin on densitometry parameters and biomarkers of bone turnovers among patients with SCI.

MATERIALS AND METHODS

The current controlled clinical trial was conducted among 100 patients with SCI referred to an outpatient clinic of rehabilitation in Ilam City, Iran, in 2013-2015. The intervention group received 110/mg/kg/day curcumin for 6 months and the control group received placebo. Bone mineral density (BMD) was measured in all patients. The level of procollagen type I N-terminal propeptide, serum carboxy-terminal telopeptide of type I collagen, osteocalcin, and bone-specific alkaline phosphates were compared before and after study.

RESULTS

BMD indicators of lumbar, femoral neck, and total hip in the control group significantly decreased compared with the beginning of study. However, in the curcumin group, a significant increase was observed in BMD indicators of lumbar, femoral neck, and hip at the end of study compared with the beginning. There was also a significant difference between interventional and control groups for the mean BMD of femoral neck and hip at the end of study (0.718 ± 0.002 g/cm² vs. 0.712 ± 0.003 g/cm² and 0.742 ± 0.031 g/cm² vs. 0.692 ± 0.016 g/cm², respectively).

CONCLUSIONS

Curcumin, via modulation of densitometry indices and bone resorption markers, showed inhibitory effects on the process of osteoporosis. Treatment with curcumin was significantly associated with a decrease in the osteoporosis progression and bone turnover markers of patients with SCI after 6 months.

Innovative evaluation of local injective gel of curcumin on the orthodontic tooth movement in rats

Background

Curcumin is the most active compound in turmeric. It can suppress the nuclear factor kappa-light-chain-enhancer of activated B cells pathway and prevent the osteoclastogenesis procedure. This study aimed to be the first to evaluate the effect of curcumin on the rate of orthodontic tooth movement (OTM).

Materials and Methods

Forty rats were used as follows in each group: (1) negative control: Did not receive any appliance or injection; (2) positive control: received 0.03 cc normal saline and appliance; (3) gelatin plus curcumin (G): Received 0.03 cc hydrogel and appliance; and (4) chitosan plus curcumin (Ch): Received 0.03 cc hydrogel and appliance. They were anesthetized and closed nickel-titanium coil springs were installed between the first molars and central incisors unilaterally as the orthodontic appliance. After 21 days, the rats were decapitated, and the distance between the first and second molars was measured by a leaf gauge. Howship's lacunae, blood vessels, osteoclast-like cells, and root resorption lacunae were evaluated in the histological analysis. Data were analyzed by one-way ANOVA, Tukey's test, and t-test (P < 0.05 consider significant).

Results

No significant difference was found in OTM between groups delivered orthodontic forces. Curcumin inhibited root and bone resorption, osteoclastic recruitment, and angiogenesis significantly.

Conclusion

Curcumin had no significant inhibitory effect on OTM. While it had a significant role on decreasing bone or root resorption (P > 0.05).

Methoxsalen supplementation attenuates bone loss and inflammatory response in ovariectomized mice

Methoxsalen (MTS) is a natural bioactive compound found in a variety of plants that has many known biofunctions; however, its effects on osteoporosis and related mechanisms are not clear. This study examined whether MTS exhibited preventive effects against postmenopausal osteoporosis. Female C3H/HeN mice were divided into four groups: Sham, ovariectomy (OVX), OVX with MTS (0.02% in diet), and OVX with estradiol (0.03 μg/day, s.c). After 6 weeks, MTS supplementation significantly increased femur bone mineral density and bone surface along with bone surface/total volume. MTS significantly elevated the levels of serum formation markers (estradiol, osteocalcin and bone-alkaline phosphatase) such as estradiol in OVX mice. Tartrate resistant acid phosphatase staining revealed that MTS suppressed osteoclast numbers and formation in femur tissues compared with the OVX group. Supplementation of MTS slightly up-regulated osteoblastogenesis-related genes (Runx-2, osterix, osteocalcin, and Alp) expression, whereas it significantly down-regulated inflammatory genes (Nfκb and Il6) expression in femur tissue compared with the OVX group. These results indicate that MTS supplementation effectively prevented OVX-induced osteoporosis via enhancement of bone formation and suppression of inflammatory response in OVX mice. Our study provides valid scientific information regarding the development and application of MTS as a food ingredient, a food supplement or an alternative agent for preventing postmenopausal osteoporosis.

Curcumin induces osteoblast differentiation through mild-endoplasmic reticulum stress-mediated such as BMP2 on osteoblast cells

AIMS

Curcumin (diferuloylmethane or [1E,6E]-1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6heptadiene-3,5-dione) is a phenolic natural product derived from the rhizomes of the turmeric plant, Curcuma longa. It is reported to have various biological actions such as anti-oxidative, anti-inflammatory, and anti-cancer effects. However, the molecular mechanism of osteoblast differentiation by curcumin has not yet been reported.

MAIN METHODS

The cytotoxicity of curcumin was identified using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Expression of osteogenic markers and endoplasmic reticulum (ER) stress markers in C3H1-T1/2 cells were measured using reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blotting. Alkaline phosphatase (ALP) staining was performed to assess ALP activity in C3H10T1/2 cells. Transcriptional activity was detected using a luciferase reporter assay.

KEY FINDINGS

Curcumin increased the expression of genes such as distal-less homeobox 5 (Dlx5), runt-related transcription factor 2 (Runx2), ALP, and osteocalcin (OC), which subsequently induced osteoblast differentiation in C3H10T1/2 cells. In addition, ALP activity and mineralization was found to be increased by curcumin treatment. Curcumin also induced mild ER stress similar to bone morphogenetic protein 2 (BMP2) function in osteoblast cells. Next, we confirmed that curcumin increased mild ER stress and osteoblast differentiation similar to BMP2 in C3H10T1/2 mesenchymal stem cells. Transient transfection studies also showed that curcumin increased ATF6-Luc activity, while decreasing the activities of CREBH-Luc and SMILE-Luc. In addition, similar to BMP2, curcumin induced the phosphorylation of Smad 1/5/9.

SIGNIFICANCE

Overall, these results demonstrate that curcumin-induced mild ER stress increases osteoblast differentiation via ATF6 expression in C3H10T1/2 cells.

Curcumin ameliorates the in vitro efficacy of carfilzomib in human multiple myeloma U266 cells targeting p53 and NF-κB pathways

Multiple myeloma (MM) is a malignant B-cell neoplasm with accumulation of malignant plasma cells in bone marrow. Pharmacological therapy improves response frequency even if with various associated toxicities. Herein, we investigated if combination of curcumin with carfilzomib (CFZ) can induce a better cytotoxic effect on in vitro cultured U266 cells. Cell viability data showed that curcumin significantly ameliorates CFZ cytotoxic effect. Furthermore, curcumin alone did not affect proteasome at the tested dose, confirming the involvement of different mechanisms in the observed effects. U266 cells exposure to curcumin or CFZ increased reactive species (RS) levels, although their production did not appear further potentiated following drugs combination. Interestingly, NF-κB nuclear accumulation was reduced by treatment with CFZ or curcumin, and was more deeply decreased in cells treated with CFZ-curcumin combinations, very likely due to the different mechanisms through which they target NF-κB. Our results confirmed the induction of p53/p21 axis and G0/G1 cell cycle arrest in anticancer activities of both drugs, an effect more pronounced for the CFZ-curcumin tested combinations. Furthermore, curcumin addition enhanced CFZ proapoptotic effect. These findings evidence that curcumin can ameliorate CFZ efficacy, and lead us to hypothesize that this effect might be useful to optimize CFZ therapy in MM patients.

Curcumin Attenuation of Wear Particle-Induced Osteolysis via RANKL Signaling Pathway Suppression in Mouse Calvarial Model

Wear particle-induced chronic inflammation and osteoclastogenesis are two critical factors in the osteolytic process. Curcumin (CUR) is an active compound of the medicinal herb Curcuma longa and has anti-inflammatory and antiosteoclastogenic properties. Our study tested the hypothesis that CUR might attenuate polymethylmethacrylate- (PMMA-) induced inflammatory osteolysis using mouse calvaria osteolysis model in vivo and in vitro. The mice were divided into four groups: phosphate-buffered saline group, CUR, PMMA, and PMMA + CUR groups. Three days before PMMA particle implantation, the mice were intraperitoneally injected with CUR (25 mg/kg/day). Ten days after the operation, the mouse calvaria was harvested for microcomputed tomography, histomorphometry, and molecular biology analysis. As expected, CUR markedly reduced the secretion of tumor necrosis factor-α, interleukin- (IL-) 1β, and IL-6 in the calvarial organ culture. Moreover, CUR suppressed osteoclastogenesis and decreased bone resorption in vivo compared with PMMA-stimulated calvaria. Furthermore, CUR downregulated the osteoclast-specific gene expression and reversed the receptor activator of nuclear factor kappa-B ligand (RANKL)/osteoprotegerin messenger RNA and protein ratio in PMMA particle-stimulated mice. These results suggest that CUR attenuated PMMA particle-induced inflammatory osteolysis by suppressing the RANKL signaling pathway in the murine calvarium, which could be a candidate compound to prevent and treat AL.

p-Coumaric acid, a dietary polyphenol ameliorates inflammation and curtails cartilage and bone erosion in the rheumatoid arthritis rat model

This study was designed to explore the underlying mechanism of p-coumaric acid (CA), a dietary polyphenol in adjuvant-induced arthritis (AIA) rat model with reference to synovitis and osteoclastogenesis. Celecoxib (COX-2 selective inhibitor) (5 mg/kg b.wt) was used as a reference drug. CA remarkably suppressed the paw edema, body weight loss and inflammatory cytokine and chemokine levels (TNF-α, IL-1β, IL-6, and MCP-1) in serum and ankle joint of arthritic rats. Consistently, CA reduced the expression of osteoclastogenic factors (RANKL and TRAP), pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-17), and inflammatory enzymes (iNOS and COX-2) in arthritic rats. However, OPG expression was found elevated. Besides, the abundance of transcription factors (NF-κB-p65, and p-NF-κB-p65, NFATc-1, and c-Fos) and MAP kinases (JNK, p-JNK, and ERK1/2) expression was alleviated in CA administered arthritic rats. In addition, CA truncated osteoclastogenesis by regulating the RANKL/OPG imbalance in arthritic rats and suppressing the RANKL-induced NFATc-1 and c-Fos expression in vitro. Radiological (CT and DEXA scan) and histological assessments authenticated that CA inhibited TRAP, bone destruction and cartilage degradation in association with enhanced bone mineral density. Taken together, our findings suggest that CA demonstrated promising anti-arthritic effect and could prove useful as an alternative drug in RA therapeutics. © 2017 BioFactors, 43(5):698-717, 2017.

Phenolics Isolated from Aframomum meleguta Enhance Proliferation and Ossification Markers in Bone Cells

Osteoporosis is a serious health problem characterized by decreased bone mineral density and deterioration of bone microarchitecture. Current antiosteoporotic agents exhibit a wide range of adverse effects; meanwhile, phytochemicals are effective and safer alternatives. In the current work, nine compounds belonging to hydroxyphenylalkane and diarylheptanoid groups were isolated from Aframomum meleguea seeds and identified as 6-gingerol (1), 6-paradol (2), 8-dehydrogingerdione (3), 8-gingerol (4), dihydro-6-paradol (5), dihydrogingerenone A (6), dihydrogingerenone C (7), 1,7-bis(3,4-dihydroxy-5-methoxyphenyl)heptane-3,5-diyl diacetate (8), and 1-(3,4-dihydroxy-5-methoxyphenyl)-7-(3,4-dihydroxyphenyl)heptane-3,5-diyl diacetate (9). The structures of isolated compounds were established by NMR and mass spectral data, in addition to referring to literature data. Exposure of MCF-7, MG-63, and SAOS-2 cells to subcytotoxic concentrations of the compounds under investigation resulted in accelerated proliferation. Among them, paradol was selected for further detailed biochemical analysis in SAOS-2 cells. DNA flowcytometric analysis of cell cycle distribution revealed that paradol did not induce any significant change in the proliferation index of SAOS-2 cells. Assessment of osteogenic gene expression revealed that paradol enhanced the expression of osteocyte and osteoblast-related genes and inhibited osteoclast and RUNX suppressor genes. Biochemically, paradol enhanced alkaline phosphatase activity and vitamin D content and decreased the osteoporotic marker acid phosphatase. In conclusion, paradol, which is a major constituents of A. melegueta seeds, exhibited potent proliferative and ossification characteristics in bone cells.

Molecular signaling mechanisms behind polyphenol-induced bone anabolism

For millennia, in the different cultures all over the world, plants have been extensively used as a source of therapeutic agents with wide-ranging medicinal applications, thus becoming part of a rational clinical and pharmacological investigation over the years. As bioactive molecules, plant-derived polyphenols have been demonstrated to exert many effects on human health by acting on different biological systems, thus their therapeutic potential would represent a novel approach on which natural product-based drug discovery and development could be based in the future. Many reports have provided evidence for the benefits derived from the dietary supplementation of polyphenols in the prevention and treatment of osteoporosis. Polyphenols are able to protect the bone, thanks to their antioxidant properties, as well as their anti-inflammatory actions by involving diverse signaling pathways, thus leading to bone anabolic effects and decreased bone resorption. This review is meant to summarize the research works performed so far, by elucidating the molecular mechanisms of action of polyphenols in a bone regeneration context, aiming at a better understanding of a possible application in the development of medical devices for bone tissue regeneration.

The Therapeutic Effects of Combination Therapy with Curcumin and Alendronate on Spine Fusion Surgery in the Ovariectomized Rats

Objective

The purpose of this study was to evaluate the therapeutic effects of combination therapy with curcumin and alendronate on spine fusion surgery in ovariectomized rats.

Methods

Thirty-two female Sprague-Dawley rats (12 weeks old) underwent bilateral ovariectomy (OVX). Eight weeks after surgery, animals underwent intertransverse spine fusion at L4–5. The rats were randomly distributed amongst 4 groups; untreated OVX group, curcumin administered group, alendronate administered group, and the combination therapy group. At 8 weeks after fusion surgery, the animals were sacrificed and the fusion mass was assessed by manual palpation, radiographic scan, and micro-computed tomographic scan. In addition, mechanical strength was determined by a 3-point bending test.

Results

Based on the results of manual palpation testing and 3-dimensional micro-computed tomography scanning, solid bone fusion rate was 50% (4 of 8) in the OVX group, 75% (6 of 8) in the alendronate-only and curcumin-only group, and 87.5% (7 of 8) in the combination therapy group, respectively. The combination therapy group had a higher fusion rate compared with the other treatment groups, though not statistically significantly (p>0.05). And the combination therapy group had a significant increase in fusion volume at 8 weeks after spine fusion surgery compared with curcumin-only group (p=0.039). The 3-point bending test showed that combination therapy group had a significantly greater maximal load value compared to that of curcumin-only group (p=0.024).

Conclusion

The present study demonstrated that additional treatment of curcumin and alendronate after spine fusion surgery in rat can promote higher fusion volume, and improve bone mechanical strength.

Curcumin, the golden nutraceutical: multitargeting for multiple chronic diseases

Curcumin, a yellow pigment in the Indian spice Turmeric (Curcuma longa), which is chemically known as diferuloylmethane, was first isolated exactly two centuries ago in 1815 by two German Scientists, Vogel and Pelletier. However, according to the pubmed database, the first study on its biological activity as an antibacterial agent was published in 1949 in Nature and the first clinical trial was reported in The Lancet in 1937. Although the current database indicates almost 9000 publications on curcumin, until 1990 there were less than 100 papers published on this nutraceutical. At the molecular level, this multitargeted agent has been shown to exhibit anti-inflammatory activity through the suppression of numerous cell signalling pathways including NF-κB, STAT3, Nrf2, ROS and COX-2. Numerous studies have indicated that curcumin is a highly potent antimicrobial agent and has been shown to be active against various chronic diseases including various types of cancers, diabetes, obesity, cardiovascular, pulmonary, neurological and autoimmune diseases. Furthermore, this compound has also been shown to be synergistic with other nutraceuticals such as resveratrol, piperine, catechins, quercetin and genistein. To date, over 100 different clinical trials have been completed with curcumin, which clearly show its safety, tolerability and its effectiveness against various chronic diseases in humans. However, more clinical trials in different populations are necessary to prove its potential against different chronic diseases in humans. This review's primary focus is on lessons learnt about curcumin from clinical trials.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

β-Carotene suppresses osteoclastogenesis and bone resorption by suppressing NF-κB signaling pathway

AIMS

β-Carotene is a natural anti-oxidant, which has been used for treatment of cancer and cardiovascular diseases. Recently, the ameliorating function of β-carotene in osteoporosis has been implicated. However, the precise mechanism of β-carotene in prevention and treatment of osteoporosis is largely unknown. In the present study, we aimed to elucidate how β-carotene affects osteoclast formation and bone resorption.

MAIN METHODS

Bone marrow-derived monocytes/-macrophages (BMM) were exposed to 0.05, 0.1, 0.2, 0.4 and 0.6μM β-carotene, followed by evaluation of cell viability, lactate dehydrogenase (LDH) release, receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastogenesis and resorption pits formation. Key factors in nuclear factor kappa B (NF-ĸB) and mitogen-activated protein kinases (MAPK) pathways were evaluated with western blot after BMM cells were exposed to RANKL and β-carotene. The effects of β-carotene in nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), c-Fos and cathepsin K (CTSK) expression were also evaluated.

KEY FINDINGS

β-Carotene significantly inhibited BMM viability and promoted LDH release at concentrations of 0.4 and 0.6μM. A decrease in RANKL-induced osteoclastogenesis and resorption was also observed after β-carotene treatment. β-Carotene attenuated the NF-ĸB pathway activation by RANKL, with no effect on MAPK pathway. β-Carotene suppressed the upregulation of NFATc1 and c-Fos by RANKL.

SIGNIFICANCE

We clarified the anti-osteoclastogenic role of β-carotene, which is mediated by NF-κB signaling.

Curculactones A and B induced the differentiation of C3H10T1/2 and MC3T3-E1 cells to osteoblasts

Curculactones A and B are rare γ-lactone derivatives obtained from yellow, natural curcumin following γ-irradiation, and are a type of small molecules with a moderate anti-obesity effect. However, the exact role of curculactones A and B in osteoblast differentiation is unknown. In this study, the effects of curculactones A and B on the differentiation of the mesenchymal cell line C3H10T1/2 and pre-osteoblast cell line MC3T3-E1 to osteoblasts were examined. Curculactones A or B could markedly increase the mRNA levels of osteogenic marker genes and alkaline phosphatase (ALP) activity. Collectively, our findings indicate that curculactones A or B induced osteoblast differentiation through osteogenic expression of genes such as distal-less homeobox 5 (Dlx5), runt-related transcription factor 2 (Runx2), ALP, and osteocalcin (OC).

Reflections about Osteoarthritis and Curcuma longa

Osteoarthritis (OA) is a chronic inflammatory degenerative process that affects joints such as the hands, hips, shoulders, feet, spine, and especially knees in millions of people worldwide. Some authors have shown that Curcuma longa components may exhibit benefic effects in the treatment of degenerative diseases as OA. This plant belongs to the family Zingiberaceae and it is popularly known as turmeric or saffron. This review intended to perform a retrospective search to identify studies involving humans and animal models. This review was based on articles linking OA and C. longa. Databases as Medline, Science Direct, and Lilacs were consulted and a retrospective search was carried out in order to identify studies involving humans and animal models. The curcuminoids from C. longa exhibit actions at different locations in the pathogenesis of OA once it may play an important role as anti-inflammatory, down-regulating enzymes as phospholipase A2, cyclooxygenase-2, and lipoxygenases, and reducing tumor necrosis factor-alpha-and interleukins such as interleukin-1β (IL-1β), IL-6, and IL-8. They also act as inducer of apoptosis in synoviocytes, decreasing the inflammation process and may also reduce the synthesis of reactive oxygen species. For these reasons, new pharmaceutical technology and pharmacological studies should be proposed to determine the dose, the best delivery vehicle, pharmaceutical formulation and route of administration of this plant so its use as an adjunct in the treatment of OA may become a reality in clinical practice.

Anticancer Activity of Curcumin and Its Analogues: Preclinical and Clinical Studies

Curcumin has been shown to have a wide variety of therapeutic effects, ranging from anti-inflammatory, chemopreventive, anti-proliferative, and anti-metastatic. This review provides an overview of the recent research conducted to overcome the problems with the bioavailability of curcumin, and of the preclinical and clinical studies that have reported success in combinatorial strategies coupling curcumin with other treatments. Research on the signaling pathways that curcumin treatment targets shows that it potently acts on major intracellular components involved in key processes such as genomic modulations, cell invasion and cell death pathways. Curcumin is a promising molecule for the prevention and treatment of cancer.

Curcumin protects human adipose-derived mesenchymal stem cells against oxidative stress-induced inhibition of osteogenesis

The detrimental effects of oxidative stress on the skeletal system have been documented, and understanding the mechanisms is important to design a therapeutic strategy. As an antioxidant and anti-inflammatory agent, the active ingredient of turmeric curcumin has been used as medication for numerous complications including bone loss. However, it is unclear if curcumin could influence the osteogenic potential of mesenchymal stem cells (MSCs), particularly in oxidative injuries. Here we demonstrate that curcumin treatment protects cell death caused by hydrogen peroxide (H2O2) exposure in human adipose-derived MSCs in vitro. Importantly, curcumin is able to enhance the osteoblast differentiation of human adipose-derived MSCs that is inhibited by H2O2. Notably, both oxidative stress and the inhibition of Wnt/β-catenin signaling are attenuated by curcumin treatment. These results suggest that curcumin can promote osteoblast differentiation of MSCs and protect the inhibitory effect elicited by oxidative injury. The findings support potential use of curcumin or related antioxidants in MSC-based bone regeneration for disease related with oxidative stress-induced bone loss.

Curcumin eluting nanofibers augment osteogenesis toward phytochemical based bone tissue engineering

Curcumin is a phenolic compound isolated from Curcuma longa that is known to exhibit wide ranging biological activity including potential benefits for bone growth. The aim of this work was to engineer curcumin eluting tissue scaffolds and investigate their potential use in bone tissue regeneration. We prepared curcumin loaded poly(ε-caprolactone) (PCL) nanofibers by electrospinning. Morphological characterization of the nanofibers revealed that the average diameter of neat fibers and that of fibers with 1 wt% and 5 wt% curcumin is 840  ±  130 nm, 827  ±  129 nm and 680  ±  110 nm, respectively. Fourier transformation infrared spectroscopy and ¹H nuclear magnetic resonance confirmed the successful loading of the drug in fibers. In aqueous medium, the fibers released  ≈18% of the encapsulated drug in 3 d and  ≈60% in 9 d. The cell response to the curcumin loaded nanofibers was assessed using MC3T3-E1 pre-osteoblasts. Cell proliferation was moderated with increased loading of curcumin and was 50% lower on the fibers containing 5% curcumin at day 10 than the control fibers. Osteogenesis was confirmed by assaying the expression of alkaline phosphatase and staining of mineral deposits by Alizarin red stain, which were both markedly higher for 1% curcumin compared to neat polymer but lower for 5% curcumin. Mineral deposition was also confirmed chemically by Fourier transform infrared spectroscopy. These results were corroborated by increased gene and protein expression of known osteogenic markers in 1% curcumin. Thus, controlled release of curcumin from polymer scaffolds is a promising strategy for bone tissue regeneration.

Natural products for treatment of bone erosive diseases: The effects and mechanisms on inhibiting osteoclastogenesis and bone resorption

Excessive bone resorption plays a central role on the development of bone erosive diseases, including osteoporosis, rheumatoid arthritis, and periodontitis. Osteoclasts, bone-resorbing multinucleated cells, are differentiated from hemopoietic progenitors of the monocyte/macrophage lineage. Regulation of osteoclast differentiation is considered an effective therapeutic target to the treatment of pathological bone loss. Natural plant-derived products, with potential therapeutic and preventive activities against bone-lytic diseases, have received increasing attention in recent years because of their whole regulative effects and specific pharmacological activities, which are more suitable for long-term use than chemically synthesized medicines. In this review, we summarized the detailed research progress on the active compounds derived from medical plants with potential anti-resorptive effects and their molecular mechanisms on inhibiting osteoclast formation and function. The active ingredients derived from natural plants that are efficacious in suppressing osteoclastogenesis and bone resorption include flavonoids, terpenoids (sesquiterpenoids, diterpenoids, triterpenoids), glycosides, lignans, coumarins, alkaloids, polyphenols, limonoids, quinones and others (steroid, oxoxishhone, fatty acid). Studies have shown that above natural products exert the inhibitory effects via regulating many factors involved in the process of osteoclast differentiation and bone resorption, including the essential cytokines (RANKL, M-CSF), transcription factors (NFATc1, c-Fos), signaling pathways (NF-κB, MAPKs, Src/PI3K/Akt, the calcium ion signaling), osteoclast-specific genes (TRAP, CTSK, MMP-9, integrin β3, OSCAR, DC-STAMP, Atp6v0d2) and local factors (ROS, LPS, NO). The development of osteoclast-targeting natural products is of great value for the prevention or treatment of bone diseases and for bone regenerative medicine.

Aspirin inhibits osteoclastogenesis by suppressing the activation of NF-κB and MAPKs in RANKL-induced RAW264.7 cells

Aspirin is a commonly used medicine as an effective antipyretic, analgesic and anti-inflammatory drug. Previous studies have demonstrated its potential effects of anti-postmenopausal osteoporosis, while the molecular mechanisms remain unclear. The effects of aspirin on receptor-activator of nuclear factor κB (NF-κB) ligand (RANKL)-induced osteoclasts were investigated in RAW264.7 cells in the current study. Using tartrate-resistant acid phosphatase (TRAP) staining, it was observed that aspirin inhibited the differentiation of RANKL-induced RAW264.7 cells. The mRNA expression of osteoclastic marker genes, including cathepsin K, TRAP, matrix metalloproteinase 9 and calcitonin receptor, were suppressed by aspirin as identified using reverse transcription-quantitative polymerase chain reaction analysis. The immunofluorescence assay indicated that aspirin markedly inhibited NF-κB p65 translocation to the nucleus in RANKL-induced RAW264.7 cells. In addition, aspirin also suppressed the phosphorylation of mitogen-activated protein kinases (MAPKs), observed by western blot analysis. Taken together, these data identified that aspirin inhibits osteoclastogenesis by suppressing the activation of NF-κB and MAPKs in RANKL-induced RAW264.7 cells, implying that aspirin may possess therapeutic potential for use in the prevention and treatment of osteoporosis.

Role of Curcumin in Common Musculoskeletal Disorders: a Review of Current Laboratory, Translational, and Clinical Data

The Indian spice turmeric, in which the active and dominant biomolecule is curcumin, has been demonstrated to have significant medicinal properties, including anti-inflammatory and anti-neoplastic effects. This promise is potentially very applicable to musculoskeletal disorders, which are common causes of physician visits worldwide. Research at the laboratory, translational and clinical levels that supports the use of curcumin for various musculoskeletal disorders, such as osteoarthritis, osteoporosis, musculocartilaginous disorders, and sarcoma is here in comprehensively summarized. Though more phase I-III trials are clearly needed, thus far the existing data show that curcumin can indeed potentially be useful in treatment of the hundreds of millions worldwide who are afflicted by these musculoskeletal disorders.

South Asian Medicinal Compounds as Modulators of Resistance to Chemotherapy and Radiotherapy

Cancer is a hyperproliferative disorder that involves transformation, dysregulation of apoptosis, proliferation, invasion, angiogenesis and metastasis. During the last 30 years, extensive research has revealed much about the biology of cancer. Chemotherapy and radiotherapy are the mainstays of cancer treatment, particularly for patients who do not respond to surgical resection. However, cancer treatment with drugs or radiation is seriously limited by chemoresistance and radioresistance. Various approaches and strategies are employed to overcome resistance to chemotherapy and radiation treatment. Many plant-derived phytochemicals have been investigated for their chemo- and radio-sensitizing properties. The peoples of South Asian countries such as India, Pakistan, Sri Lanka, Nepal, Bangladesh and Bhutan have a large number of medicinal plants from which they produce various pharmacologically potent secondary metabolites. The medicinal properties of these compounds have been extensively investigated and many of them have been found to sensitize cancer cells to chemo- and radio-therapy. This review focuses on the role of South Asian medicinal compounds in chemo- and radio-sensitizing properties in drug- and radio-resistant cancer cells. Also discussed is the role of South Asian medicinal plants in protecting normal cells from radiation, which may be useful during radiotherapy of tumors to spare surrounding normal cells.

Therapeutic actions of curcumin in bone disorders

Curcumin is the active component of turmeric extract derived from the Curcuma longa plant. In the last decade, curcumin has raised a considerable interest in medicine owing to its negligible toxicity and multiple therapeutic actions including anti-cancer, anti-inflammatory and anti-microbial activities. Among the various molecular targets of curcumin, some are involved in bone remodeling, which strongly suggests that curcumin can affect the skeletal system. The review sheds light on the current and potential applications of curcumin to treat bone disorders characterized by an excessive resorption activity. Within the scope of this review, the novel formulations of curcumin to overcome its physico-chemical and pharmacokinetic constraints are also discussed.

Calebin A downregulates osteoclastogenesis through suppression of RANKL signalling

Osteoporosis is a bone disease that is exacerbated by aging and age-associated chronic diseases such as cancer. Cancer-induced bone loss is usually treated with bisphosphonates or denosumab, an antibody against receptor activator of nuclear factor (NF)-κB ligand (RANKL). Because these drugs are expensive and have numerous side effects and high rates of toxicity, safer, more effective, and more affordable therapies for osteoporosis are still needed. We identified a compound, calebin A (CA), derived from turmeric (Curcuma longa) that affects osteoclastogenesis through modulation of the RANKL signalling pathway. The CA's effect on NF-κB activation was examined by electrophoretic mobility shift assay. Using mouse macrophages in vitro model, we found that CA suppressed RANKL-induced osteoclast differentiation of macrophages into osteoclasts, and downregulate RANKL-induced osteoclastogenesis-related marker gene expression, including NFATc-1, TRAP, CTR, and cathepsin K. CA also suppressed the osteoclastogenesis induced by multiple myeloma and breast cancer cells. This effect of CA was correlated with suppression of the phosphorylation and degradation of inhibitor of κB and, thus, inhibition of NF-κB activation. Furthermore, we found that an NF-κB-specific inhibitory peptide blocked RANKL-induced osteoclastogenesis, demonstrating that the NF-κB signalling pathway is mandatory for RANKL-induced osteoclastogenesis. Our results conclusively indicate that CA downmodulates the osteoclastogenesis induced by RANKL and by tumour cells through suppression of NF-κB pathway.

Ginger hexane extract suppresses RANKL-induced osteoclast differentiation

Osteoporosis is a debilitating disease caused by decreased bone density. Compounds with anti-osteoclastic activity, such as bisphosphonates, may help in the prevention and treatment of osteoporosis. Herein, we determined the inhibitory effects of ginger hexane extract (GHE) on receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis in RAW264.7 cells. The results showed that GHE (1) suppressed osteoclast differentiation and the formation of actin rings; (2) inhibited the expression of Nfatc1, a master transcriptional factor for osteoclast differentiation, in a dose-dependent manner (10-20 μg/mL); and (3) inhibited other osteoclastogenesis-related genes, such as Oscar, Dc-stamp, Trap, and Mmp9. These findings suggest that GHE may be used to prevent and treat osteoporosis by inhibiting osteoclast differentiation.

Randomized controlled studies on the efficacy of antiarthritic agents in inhibiting cartilage degeneration and pain associated with progression of osteoarthritis in the rat

Background

As an initial step in the development of a local therapeutic to treat osteoarthritis (OA), a number of agents were tested for their ability to block activation of inflammation through nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), subchondral bone changes through receptor activator of nuclear factor κB ligand (RANKL)-mediated osteoclastogenesis, and proteolytic degradation through matrix metalloproteinase (MMP)-13 activity. Candidates with low toxicity and predicted efficacy were further examined using either of two widely accepted models of OA joint degeneration in the rat: the monoiodoacetic acid (MIA) model or the medial meniscal tear/medial collateral ligament tear (MMT/MCLT) model.

Methods

Potential therapeutics were assessed for their effects on the activation of nuclear factor (NF)-κB, RANKL-mediated osteoclastogenesis, and MMP-13 activity in vitro using previously established assays. Toxicity was measured using HeLa cells, a synovial cell line, or primary human chondrocytes. Drugs predicted to perform well in vivo were tested either systemically or via intraarticular injection in the MIA or the MMT/MCLT model of OA. Pain behavior was measured by mechanical hyperalgesia using the digital Randall-Selitto test (dRS) or by incapacitance with weight bearing (WB). Joint degeneration was evaluated using micro computed tomography and a comprehensive semiquantitative scoring of cartilage, subchondral bone, and synovial histopathology.

Results

Several agents were effective both in vitro and in vivo. With regard to pain behavior, systemically delivered clonidine was superior in treating MIA-induced changes in WB or dRS, while systemic clonidine, curcumin, tacrolimus, and fluocinolone were all somewhat effective in modifying MMT/MCLT-induced changes in WB. Systemic tacrolimus was the most effective in slowing disease progression as measured by histopathology in the MMT/MCLT model.

Conclusions

All of the agents that demonstrated highest benefit in vivo, excepting clonidine, were found to inhibit MMP-13, NF-κB, and bone matrix remodeling in vitro. The MIA and MMT/MCLT models of OA, previously shown to possess inflammatory characteristics and to display associated pain behavior, were affected to different degrees by the same drugs. Although no therapeutic was remarkable across all measures, the several which showed the most promise in either model merit continued study with alternative dosing and therapeutic strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0921-5) contains supplementary material, which is available to authorized users.