Rosmarinic acid and arbutin suppress osteoclast differentiation by inhibiting superoxide and NFATc1 downregulation in RAW 264.7 cells

5'-Methylthioadenosine strongly suppresses RANKL-induced osteoclast differentiation and function via inhibition of RANK-NFATc1 signalling pathways

Excessive osteoclast-mediated bone resorption is a critical cause of osteoporosis affecting many aging people worldwide. 5'-Methylthioadenosine (MTA) is a natural sulfur-containing nucleoside normally produced in prokaryotes, plants, yeast, and higher eukaryotes via polyamine metabolism. MTA affects various physiological responses particularly the inflammatory pathway in both normal and cancerous cells and modulates the activation of nuclear factor-κB involved in the osteoclastogenesis signalling process. While several studies have reported that natural products possess anti-osteoclastogenesis phenolics and flavonoids, the effect of nucleoside derivatives on osteoclastogenesis remains limited. Therefore, this study aimed to explore the molecular mechanisms by which MTA affects pre-osteoclastic RAW 264.7 cells as a potential alleviation compound for inflammation-mediated bone loss. Osteoclasts were established by incubating RAW264.7 macrophage cells with receptor activator of nuclear factor kappa B ligand (RANKL) and macrophage colony-stimulating factor, the vital cytokines for activation of osteoclast differentiation. Cell viability was measured using MTT assays at 24, 48, and 72 h. The suppressive effect of MTA on RANKL-induced osteoclast differentiation and function was assessed using tartrate-resistant acid phosphatase (TRAP) analysis, qRT-PCR, and pit formation, Western blot, and immunofluorescence assays. MTA showed dose-dependent anti-osteoclastogenic activity by inhibiting TRAP-positive cell and pit formation and reducing essential digestive enzymes, including TRAP, cathepsin K, and matrix metallopeptidase 9. MTA was observed to suppress the osteoclast transduction pathway through (RANKL)-induced nuclear factor kappa-light-chain-enhancer of activated B cells (NFƘB); it attenuated NFƘB-P65 expression and down-regulated cFos proto-oncogene and nuclear factor of activated T cell c1 (NFATc1), the main regulators of osteoclasts. Moreover, the suppression of RANK (the initial receptor triggering several osteoclastogenic transduction pathways) was observed. Thus, this study highlights the potential of MTA as an effective therapeutic compound for restoring bone metabolic disease by inhibiting the RANK-NFATc1 signal pathway.

Osteoclast formation from mouse bone marrow cells on micro/nano-scale patterned surfaces

OBJECTIVES

Osteoclasts can sense the surface topography of materials. However, it is difficult to identify the structural factors that affect osteoclast formation and its function. Furthermore, we hypothesized that the type of osteoclast precursor cells also affects osteoclastogenesis in the materials. In this study, we investigated the effects of defined micro/nanoscale patterns on osteoclastogenesis from bone marrow cells (BMCs).

METHODS

Various cyclo-olefin polymer (COP) patterns were prepared using nanoimprinting. The effects of shape, size, and height of the patterns, and the wettability of the patterned surfaces on osteoclastogenesis from BMCs were evaluated in vitro.

RESULTS

Osteoclast formation was promoted on pillars (diameter, 1 μm or 500 nm; height, 500 nm). Notably, osteoclastogenesis from BMCs was better promoted on hydrophobic pillars than on hydrophilic pillars. In contrast, decreased osteoclast formation was observed on the nanopillars (diameter, 100 nm; height, 200 nm).

CONCLUSIONS

We demonstrated the promotion of osteoclast formation from BMCs on hydrophobic pillars with diameters of 1 μm and 500 nm. Some cellular behaviors in the patterns were dependent on the type of osteoclast precursor cells. The designed patterns are useful for designing the surface of dental implants or bone replacement materials with a controllable balance between osteoblast and osteoclast activities.

Effects of Itxasol© Components on Gene Expression in Bacteria Related to Infections of the Urinary Tract and to the Inflammation Process

Urinary tract infections (UTIs) represent a health problem of the first magnitude since they affect large segments of the population, cause increased mortality and comorbidity, and have a high incidence of relapse. Therefore, UTIs cause a major socioeconomic concern. Current antibiotic treatments have various limitations such as the appearance of resistance to antibiotics, nephrotoxicity, and side effects such as gastrointestinal problems including microbiota alterations that contribute to increasing antibiotic resistance. In this context, Itxasol© has emerged, approved as an adjuvant for the treatment of UTIs. Designed with biomimetic principles, it is composed of arbutin, umbelliferon, and N-acetyl cysteine. In this work, we review the activities of these three compounds concerning the changes they produce in the expression of bacterial genes and those related to inflammation as well as assess how they are capable of affecting the DNA of bacteria and fungi.

Osteoprotective Effects of ‘Anti-Diabetic’ Polyherbal Mixture in Type 1 Diabetic Rats

Bone loss leading to osteopenia and osteoporosis is a frequent secondary complication of diabetes. This study aimed to evaluate the value of a traditionally used ‘anti-diabetic’ polyherbal mixture as a possible remedy for the prevention of this complication. Diabetes was induced in Wistar female rats with a single intraperitoneal injection of alloxan monohydrate. The animals with blood glucose higher than 20 mmol/L for 14 consecutive days were considered diabetic. For the next 14 days, animals were treated with two concentrations of the polyherbal mixture (10 and 20 g of dry plant material/ kg). Bone histopathology was evaluated using the H&E and Masson’s trichrome staining. Alloxan-induced diabetes triggered bone histological changes characteristic for the development of osteopenia and osteoporosis and treatment with the polyherbal decoction restored these histopathological changes of the bones to the healthy animal level. At the same time, treatment with these tested doses has shown no adverse effects. These findings suggest that this mixture might be used as a remedy for the prevention of diabetic bone loss.

Water Extract of Mentha arvensis L. Attenuates Estrogen Deficiency-Induced Bone Loss by Inhibiting Osteoclast Differentiation

Mentha arvensis L., is an aromatic herb that belongs to the Lamiaceae family and is widely used in medicinal applications, essential oil applications, and food flavoring. The extract of M. arvensis has been reported to exert sedative-hypnotic, anti-inflammatory, anti-fungal, and anti-bacterial effects. However, its effects on bone metabolism have not yet been studied. Here, we investigated the effects of the water extract of M. arvensis (WEMA) on osteoclast formation in vitro and bone loss in an ovariectomized mouse model. We found that WEMA inhibited osteoclast differentiation by directly acting on osteoclast precursor cells. WEMA inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced the expression of cellular oncogene fos (c-Fos) and nuclear factor of activated T cells c1 (NFATc1), crucial transcription factors for osteoclast differentiation, by suppressing RANKL-induced activation of early signaling pathways such as those of mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB). In addition, oral administration of WEMA suppressed ovariectomy-induced trabecular bone loss in mice. We additionally identified phytochemicals in WEMA that are known to have anti-osteoclastogenic or anti-osteoporotic properties. Collectively, these results suggest that WEMA is a promising herbal candidate that can be used to prevent or treat postmenopausal osteoporosis.

Agastache rugosa ethanol extract suppresses bone loss via induction of osteoblast differentiation with alteration of gut microbiota

PURPOSE

Osteoporosis is a metabolic skeletal disease characterized by bone loss and an increased risk of fractures. This study aimed to investigate the therapeutic effect of Agastache rugosa on postmenopausal osteoporosis and elucidate its mechanisms in modulating the bone status.

METHODS AND RESULTS

In the osteoblast differentiation process with MC3T3-E1 pre-osteoblasts, ethanol extract of Agastache rugosa (EEAR) and its compounds increased the expression of the proteins and genes of the osteoblast differentiation-related markers such as Runt-related transcription factor 2 (RUNX2) and β-catenin along with the elevation of calcium deposits. An ovariectomized mouse model was utilized to determine the impact of EEAR extract on postmenopausal osteoporosis. Twelve weeks of AR treatment suppressed the loss of bone strength, which was observed through micro-computed tomography. AR elevated osteogenic markers in the bone marrow cells, and collagen type 1 alpha 1 in the distal femoral bone. The results of the 16S rRNA gene sequencing analysis of cecal gut microbiomes demonstrated that AR reversed the ovariectomy-induced changes in the gut microbiomes.

CONCLUSION

Ethanol extract of Agastache rugosa has a therapeutic effect on postmenopausal osteoporosis via bone morphogenic protein, transforming growth factor β, and Wnt signaling pathway. It also increases the diversity of gut microbiota. Therefore, these data suggest that EEAR could be a potential candidate to treat postmenopausal osteoporosis.

Arbutin ameliorates glucocorticoid-induced osteoporosis through activating autophagy in osteoblasts

Chronic long-term glucocorticoid use causes osteoporosis partly by interrupting osteoblast homeostasis and exacerbating bone loss. Arbutin, a natural hydroquinone glycoside, has been reported to have biological activities related to the differentiation of osteoblasts and osteoclasts. However, the role and underlying mechanism of arbutin in glucocorticoid-induced osteoporosis are elusive. In this study, we demonstrated that arbutin administration ameliorated osteoporotic disorders in glucocorticoid dexamethasone (Dex)-induced mouse model, including attenuating the loss of bone mass and trabecular microstructure, promoting bone formation, suppressing bone resorption, and activating autophagy in bone tissues. Furthermore, Dex-stimulated mouse osteoblastic MC3T3-E1 cells were treated with arbutin. Arbutin treatment rescued Dex-induced repression of osteoblast differentiation and mineralization, the downregulation of osteogenic gene expression, reduced autophagic marker expression, and decreased autophagic puncta formation. The application of autophagy inhibitor 3-MA decreased autophagy, differentiation, and mineralization of MC3T3-E1 cells triggered by arbutin. Taken together, our findings suggest that arbutin treatment fends off glucocorticoid-induced osteoporosis, partly through promoting differentiation and mineralization of osteoblasts by autophagy activation.

Inhibitory Effect of a Rosmarinic Acid-Enriched Fraction Prepared from Nga-Mon (Perilla frutescens) Seed Meal on Osteoclastogenesis through the RANK Signaling Pathway

The aim of this study is to determine antioxidant and anti-inflammatory activities relating to the antiosteoporosis effects of various perilla seed meal (PSM) fractions. The remaining waste of perilla seed obtained from cold oil compression was extracted with 70% ethanol and sequentially fractionated according to solvent polarity with hexane, dichloromethane, ethyl acetate, and water. The results indicated that the seed-meal ethyl acetate fraction (SMEF) exhibited the highest antioxidant and anti-inflammatory activities, and rosmarinic acid (RA) content. The signaling pathways induced by the receptor activator of the nuclear factor kappa B (NF-κB) ligand (RANKL) that trigger reactive oxygen species (ROS) and several transcription factors, leading to the induction of osteoclastogenesis, were also investigated. The SMEF clearly showed attenuated RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts and TRAP activity. A Western blot analysis showed that the SMEF significantly downregulated RANKL-induced NF-κB, AP-1 activation, and the nuclear factor of activated T-cell 1 (NFATc1) expression. SMEF also suppressed RANKL-induced osteoclast-specific marker gene-like MMP-9 using zymography. Furthermore, the SMEF showed inhibition of RANKL-induced ROS production in RAW 264.7 cells. The results suggest that the SMEF, which contained high quantities of RA, could be developed as a natural active pharmaceutical ingredient for osteoclastogenic protection and health promotion.

Insights into Arbutin Effects on Bone Cells: Towards the Development of Antioxidant Titanium Implants

Arbutin is a plant-derived glycosylated hydroquinone with antioxidant features, exploited to combat cell damage induced by oxidative stress. The latter hinders the osseointegration of bone prostheses, leading to implant failure. Little is known about arbutin antioxidant effects on human osteoblasts, therefore, this study explores the in vitro protective role of arbutin on osteoblast-like cells (Saos-2) and periosteum-derived progenitor cells (PDPCs). Interestingly, cells exposed to oxidative stress were protected by arbutin, which preserved cell viability and differentiation. Starting from these encouraging results, an antioxidant coating loaded with arbutin was electrosynthesized on titanium. Therefore, for the first time, a polyacrylate-based system was designed to release the effective concentration of arbutin in situ. The innovative coating was characterized from the physico-chemical and morphological point of view to achieve an optimized system, which was in vitro tested with cells. Morpho-functional evaluations highlighted the high viability and good compatibility of the arbutin-loaded coating, which also promoted the expression of PDPC differentiation markers, even under oxidative stress. These results agreed with the coatings’ in vitro antioxidant activity, which showed a powerful scavenging effect against DPPH radicals. Taken together, the obtained results open intriguing opportunities for the further development of natural bioactive coatings for orthopedic titanium implants.

Arbutin promotes MC3T3‑E1 mouse osteoblast precursor cell proliferation and differentiation via the Wnt/β‑catenin signaling pathway

Arbutin is a natural compound extracted from various plants, including bearberry leaves, that exerts multiple effects including skin whitening, anti‑inflammatory and oxidative stress‑protective properties. However, the effects of arbutin on osteoblasts remain unknown. The aim of the present study was to investigate the function and the mechanisms of arbutin on the proliferation and differentiation of MC3T3‑E1 mouse osteoblast precursor cells in vitro. The proliferation of MC3T3‑E1 cells treated with arbutin was assessed using a Cell Counting Kit‑8 assay and a 5‑ethynyl‑2'‑deoxyuridine labeling assay. Additionally, cell cycle and apoptosis were examined using flow cytometry analysis. The effects of arbutin on osteoblast differentiation were investigated using alkaline phosphatase (ALP) staining and by examining the mRNA expression levels of collagen type I α1 chain (COL1A1), bone γ‑carboxyglutamate protein (BGLAP) and Sp7 transcription factor (SP7). To further investigate the molecular mechanism underlying arbutin function in promoting osteogenesis, the mRNA and protein expression levels of runt‑related transcription factor 2 (RUNX2) and β‑catenin were analyzed by reverse transcription‑quantitative polymerase chain reaction and western blotting. Arbutin significantly promoted MC3T3‑E1 cell proliferation and increased the ratio of cells in S‑phase. Treatment with arbutin increased ALP activity and the mRNA expression levels of COL1A1, BGLAP and SP7 in MC3T3‑E1 cells. Furthermore, the protein and the mRNA expression levels of RUNX2 and β‑catenin increased significantly following treatment with arbutin. Collectively, the present findings suggested that arbutin was able to promote proliferation and differentiation of MC3T3‑E1 cells via the Wnt/β‑catenin signaling pathway.

Irisin promotes proliferation but inhibits differentiation in osteoclast precursor cells

The receptor activator of NF-κB ligand-induced osteoclast differentiation has a critical role in the process of bone metabolism. Overactivation of osteoclastogenesis may result in a series of diseases. Irisin, a novel myokine, which was first reported in 2012, has been proposed to mediate the beneficial metabolic effects of exercise. Studies have demonstrated that irisin targets osteoblasts by promoting osteoblast proliferation and differentiation; however, the underlying mechanism regarding the effect of irisin on osteoclasts remains elusive. Using 2 types of osteoclast precursor cells, RAW264.7 cells and mouse bone marrow monocytes, we showed that irisin promoted osteoclast precursor cell proliferation but inhibited osteoclast differentiation. Irisin down-regulated the expression of osteoclast differentiation marker genes, including receptor activators of NF-κB, nuclear factor of activated T cells, cytoplasmic 1, cathepsin K, and tartrate-resistant acid phosphatase (TRAP), as well as decreasing the number of TRAP-positive multinucleated cells and hydroxyapatite resorption pits. Furthermore, we showed that irisin suppressed the NF-κB signaling pathway, but activated the p38 and JNK signaling pathways. In the presence of an inhibitor of p38 and JNK, irisin-induced promotion of RAW264.7 cell proliferation was attenuated. However, irisin-induced inhibition of osteoclast differentiation was not affected by either the p38 or JNK signaling pathway. Our study suggested the direct effect of irisin on osteoclastogenesis and revealed the mechanism responsible for the therapeutic potential of irisin in bone metabolism disease.-Ma, Y., Qiao, X., Zeng, R., Cheng, R., Zhang, J., Luo, Y., Nie, Y., Hu, Y., Yang, Z., Zhang, J., Liu, L., Xu, W., Xu, C. C., Xu, L. Irisin promotes proliferation but inhibits differentiation in osteoclast precursor cells.

Chronic diseases, inflammation, and spices: how are they linked?

Extensive research within the last several decades has revealed that the major risk factors for most chronic diseases are infections, obesity, alcohol, tobacco, radiation, environmental pollutants, and diet. It is now well established that these factors induce chronic diseases through induction of inflammation. However, inflammation could be either acute or chronic. Acute inflammation persists for a short duration and is the host defense against infections and allergens, whereas the chronic inflammation persists for a long time and leads to many chronic diseases including cancer, cardiovascular diseases, neurodegenerative diseases, respiratory diseases, etc. Numerous lines of evidence suggest that the aforementioned risk factors induced cancer through chronic inflammation. First, transcription factors NF-κB and STAT3 that regulate expression of inflammatory gene products, have been found to be constitutively active in most cancers; second, chronic inflammation such as pancreatitis, prostatitis, hepatitis etc. leads to cancers; third, activation of NF-κB and STAT3 leads to cancer cell proliferation, survival, invasion, angiogenesis and metastasis; fourth, activation of NF-κB and STAT3 leads to resistance to chemotherapy and radiation, and hypoxia and acidic conditions activate these transcription factors. Therefore, targeting these pathways may provide opportunities for both prevention and treatment of cancer and other chronic diseases. We will discuss in this review the potential of various dietary agents such as spices and its components in the suppression of inflammatory pathways and their roles in the prevention and therapy of cancer and other chronic diseases. In fact, epidemiological studies do indicate that cancer incidence in countries such as India where spices are consumed daily is much lower (94/100,000) than those where spices are not consumed such as United States (318/100,000), suggesting the potential role of spices in cancer prevention.

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.

Sodium Hypochlorite Irrigation and Its Effect on Bond Strength to Dentin

Effective shaping and cleaning of root canals are essential for the success of endodontic treatment. Due to the complex anatomy of root canal spaces, the use of various instrumentation techniques alone is not effective in producing bacteria-free root canal spaces. Irrigation, disinfectants, rinses, and intervisit medications are used in conjunction with the mechanical instrumentation to ensure the success of endodontic treatment. Sodium hypochlorite (NaOCl), a halogenated compound, is routinely used to irrigate the root canal during endodontic treatments. NaOCl has been known for its antibacterial action, proteolytic and dissolution capacity, and debridement properties. NaOCl, however, can alter the composition of dentin and hence its interaction with the adhesive resins used to bond the restorative materials to treated dentin. This review therefore covers in depth the action of NaOCl on dentin-adhesive resin bond strength including both enhancement and reduction, then mechanisms proposed for such action, and finally how the adverse action of NaOCl on dentin can be reversed.

Chlorpheniramine and escitalopram: Similar antidepressant and nitric oxide lowering roles in a mouse model of anxiety

There is a crosstalk between mood disorders and oxidative stress. Chlorpheniramine (CPA), a first generation antihistamine, is hypothesized to have an anxiolytic role at high doses; however, its antidepressant and antioxidant roles have not previously been investigated. The aim of the current study was to evaluate the antidepressant and anxiolytic effects of CPA treatment in association with nitric oxide (NO) and super oxide dismutase (SOD) activity in a mouse model of anxiety. BALB/c mice were divided into unstressed (naïve), control, and CPA- (0.5 mg/kg) and escitalopram- (ESC; 10 mg/kg) treated groups for 3 weeks. Subsequently, they were immobilized for 6 h and subjected to behavioural paradigms as follows: The open field test, the elevated plus maze (EPM) and the forced swim test to investigate motor function, anxiety and depression, respectively. The mice were sacrificed and serum was obtained to detect NO and SOD activity. Compared with the control group, the CPA-treated group demonstrated an antidepressant effect similar to that of the ESC-treated group. In addition, CPA prevented stress-induced NO without affecting SOD activity. CPA did not improve anxiety-like behaviour in the EPM, nor did it improve stress-induced locomotion and rearing, as demonstrated by the OFT. Thus, to the best of our knowledge, this is the first study to evaluate the antidepressant role of CPA in association with NO metabolism. However, further studies are required to elucidate the underlying mechanism.