Persistent Activation of STAT3 Pathway in the Retina Induced Vision Impairment and Retinal Degenerative Changes in Ageing Mice.

Neurotrophic factors can promote the survival of degenerating retinal cells through the activation of STAT3 pathway. Thus, augmenting STAT3 activation in the retina has been proposed as potential therapy for retinal dystrophies. On the other hand, aberrant activation of STAT3 pathway is oncogenic and implicated in diverse human diseases. Furthermore, the STAT3/SOCS3 axis has been shown to induce the degradation of rhodopsin during retinal inflammation. In this study, we generated and used mice with constitutive activation of STAT3 pathway in the retina to evaluate the safety and consequences of enhancing STAT3 activities in the retina as a potential treatment for retinal degenerative diseases. We show that long-term activation of the STAT3 pathway can induce retinal degenerative changes and also exacerbate uveitis and other intraocular inflammatory diseases. Mechanisms underlying the development of vision impairment in the STAT3c-Tg mice derived in part from STAT3-mediated inhibition of rhodopsin and overexpression of SOCS3 in the retina. These results suggest that much caution should be exercised in the use of STAT3 augmentation therapy for retinal dystrophies.

Diagnostic value of peripheral blood immune profiling in colorectal cancer.

PURPOSE: Little is known about the clinical value of peripheral blood immune profiling. Here, we aimed to identify colorectal cancer (CRC)-related peripheral blood immune cells and develop liquid biopsy-based immune profiling models for CRC diagnosis. METHODS: Peripheral blood from 131 preoperative patients with CRC and 174 healthy controls was analyzed by flow cytometry and automated hematology. CRC-related immune factors were identified by comparing the mean values of immune cell percentages and counts. Subsequently, CRC diagnostic algorithms were constructed using binary logistic regression. RESULTS: Significant differences were observed in percentages and counts of white blood cells, lymphocytes, neutrophils, regulatory T cells, and myeloid-derived suppressor cells (MDSCs) of patients and controls. The neutrophil/lymphocyte and Th1/Th2 ratios were also significantly different. Likewise, the percentages and counts of peripheral blood programed death 1, cytotoxic T lymphocyte antigen 4, B-and T-lymphocyte attenuator, and lymphocyte activation gene-3 were higher in patients with CRC. The binary logistic regression model included 12 variables, age, CD3+%, NK%, CD4+CD279+%, CD4+CD25+%, CD4+CD152+%, CD3+CD366+%, CD3+CD272+%, CD3+CD223+%, CD158b-CD314+CD3-CD56+%, Th2%, and MDSCs cells/µL, for the prediction of cancer. Results of retrospective and prospective evaluation of the area under the curve, sensitivity, and specificity were 0.980 and 0.940, 91.53% and 85.80%, and 93.50% and 86.20%, respectively. CONCLUSION: Peripheral blood immune profiling may be valuable in evaluating the immunity of CRC patients. Our liquid biopsy-based immune diagnostic method and its algorithms may serve as a novel tool for CRC diagnosis. Future largescale studies are needed for better characterization of its diagnostic value and potential for clinical application.

Salvia plebeia R.Br. inhibits signal transduction of IL-6 and prevents ovariectomy-induced bone loss by suppressing osteoclastogenesis.

The interleukin-6 (IL-6) family of cytokines plays a key role in the pathogenesis of rheumatoid arthritis and osteoporosis through the regulation of bone formation and resorption. In this study, it was observed that ethanol extract of Salvia plebeia R.Br. (S.P-EE) inhibited IL-6-induced signaling cascade including phosphorylation of JAK2/STAT3 and ERK. Subsequently, it was examined whether S.P-EE treatment could recover bone loss in ovariectomized (OVX) mice. Indeed, S.P-EE exhibited both preventive and therapeutic effect on OVX-induced bone loss in trabecular microarchitecture along with significant increase in bone mineral density and content. To understand the mechanism of action of S.P-EE in bone metabolism, the effect of S.P-EE on osteoclast differentiation and activity was investigated. S.P-EE significantly inhibited RANKL-induced osteoclast differentiation by suppressing phosphorylation of MAPK and Akt, and expression of NFATc1 and osteoclast marker genes. S.P-EE also inhibited bone-resorbing activity of osteoclasts. Furthermore, isolation and identification of the active compounds which are responsible for the inhibitory effect of S.P-EE on osteoclast differentiation was carried out. Six major flavonoids and plebeiolide A-C were isolated and examined their effects on osteoclast differentiation. Luteolin and hispidulin, and plebeiolide A and C, not B exhibited potent inhibitory activity on RANKL-induced osteoclast formation.

Eudesmane-type sesquiterpenoids from Salvia plebeia inhibit IL-6-induced STAT3 activation.

Seven eudesmane-type sesquiterpenoid lactones and the known plebeiolide C were isolated from an ethanol-soluble extract of the aerial parts of Salvia plebeia R. Br. Their structures were determined via NMR and MS, and their absolute configurations were elucidated using ECD, and X-ray crystallographic analysis, as well as the modified Mosher ester method. All isolates were evaluated for their inhibitory effects on IL6-induced STAT3 promoter activation in stably transfected Hep3B cells. Of these isolates, eudebeiolide D exhibited an inhibitory effect with the IC50 value of 1.1 µM.

Study of the UV Light Conversion of Feruloyl Amides from Portulaca oleracea and Their Inhibitory Effect on IL-6-Induced STAT3 Activation.

Two new feruloyl amides, N-cis-hibiscusamide (5) and (7'S)-N-cis-feruloylnormetanephrine (9), and eight known feruloyl amides were isolated from Portulaca oleracea L. and the geometric conversion of the ten isolated feruloyl amides by UV light was verified. The structures of the feruloyl amides were determined based on spectroscopic data and comparison with literature data. The NMR data revealed that the structures of the isolated compounds showed cis/trans-isomerization under normal laboratory light conditions. Therefore, cis and trans-isomers of feruloyl amides were evaluated for their convertibility and stability by UV light of a wavelength of 254 nm. After 96 h of UV light exposure, 23.2%-35.0% of the cis and trans-isomers were converted to trans-isomers. Long-term stability tests did not show any significant changes. Among all compounds and conversion mixtures collected, compound 6 exhibited the strongest inhibition of IL-6-induced STAT3 activation in Hep3B cells, with an IC50 value of 0.2 µM. This study is the first verification of the conversion rates and an equilibrium ratio of feruloyl amides. These results indicate that this natural material might provide useful information for the treatment of various diseases involving IL-6 and STAT3.

Sesquiterpenoids from the Rhizomes of Curcuma phaeocaulis and Their Inhibitory Effects on LPS-Induced TLR4 Activation.

Two new guaiane-type (2, 6) and one new furanogermacrane-type (11) sesquiterpenoids have been isolated along with twelve known compounds from an EtOAc-soluble extract of Curcuma phaeocaulis rhizomes. The structures of the isolated compounds were elucidated using a combination of NMR, MS, and circular dichroism (CD) spectra. The inhibitory effects of each compound on lipopolysaccharide (LPS)-induced Toll-like receptor 4 (TLR4) activation in THP-1-Blue cells were assessed, and compound 4 showed more potent inhibitory activity against LPS-stimulated TLR4 activation.

Oleanolic acid acetate inhibits rheumatoid arthritis by modulating T cell immune responses and matrix-degrading enzymes.

Rheumatoid arthritis (RA) is a chronic autoimmune disease associated with a combination of synovium joint inflammation, synovium hyperplasia, and destruction of cartilage and bone. Oleanolic acid acetate (OAA), a compound isolated from Vigna angularis, has been known to possess pharmacological activities, including anti-inflammation and anti-bone destruction. In this study, we investigated the effects of OAA on RA and the underlying mechanisms of action by using a type-II collagen-induced arthritis (CIA) mouse model and tumor necrosis factor (TNF)-α-stimulated RA synovial fibroblasts. Oral administration of OAA decreased the clinical arthritis symptoms, paw thickness, histologic and radiologic changes, and serum total and anti-type II collagen IgG, IgG1, and IgG2a levels. OAA administration reduced Th1/Th17 phenotype CD4(+) T lymphocyte expansions and inflammatory cytokine productions in T cell activated draining lymph nodes and spleen. OAA reduced the expression and production of inflammatory mediators, such as cytokines and matrix metalloproteinase (MMP)-1/3, in the ankle joint tissue and RA synovial fibroblasts by down-regulating Akt, mitogen-activated protein kinases, and nuclear factor-κB. Our results clearly support that OAA plays a therapeutic role in RA pathogenesis by modulating helper T cell immune responses and matrix-degrading enzymes. The immunosuppressive effects of OAA were comparable to dexamethasone and ketoprofen. We provide evidences that OAA could be a potential therapeutic candidate for RA.

TAGLN2 regulates T cell activation by stabilizing the actin cytoskeleton at the immunological synapse.

The formation of an immunological synapse (IS) requires tight regulation of actin dynamics by many actin polymerizing/depolymerizing proteins. However, the significance of actin stabilization at the IS remains largely unknown. In this paper, we identify a novel function of TAGLN2--an actin-binding protein predominantly expressed in T cells--in stabilizing cortical F-actin, thereby maintaining F-actin contents at the IS and acquiring LFA-1 (leukocyte function-associated antigen-1) activation after T cell receptor stimulation. TAGLN2 blocks actin depolymerization and competes with cofilin both in vitro and in vivo. Knockout of TAGLN2 (TAGLN2(-/-)) reduced F-actin content and destabilized F-actin ring formation, resulting in decreased cell adhesion and spreading. TAGLN2(-/-) T cells displayed weakened cytokine production and cytotoxic effector function. These findings reveal a novel function of TAGLN2 in enhancing T cell responses by controlling actin stability at the IS.

Salvia plebeia extract inhibits the inflammatory response in human rheumatoid synovial fibroblasts and a murine model of arthritis.

Salvia plebeia R. Br. has been used to treat a variety of inflammatory diseases and as an antioxidant in many countries, including Korea and China. In this study, we investigated the effects of S. plebeia extract (SPE) on inflammatory arthritis and the underlying mechanisms of action. We used a collagen-induced arthritis (CIA) mouse model. TNF-α-stimulated rheumatoid arthritis (RA) synovial fibroblasts were used to elucidate the underlying mechanisms of action. Oral administration of SPE improved the clinical arthritis score, footpad thickness, and histologic changes, as well as serum IgG1 and IgG2a levels. SPE administration inhibited Th1/Th2/Th17 phenotype CD4(+) T lymphocyte expansion in inguinal lymph node and expression of inflammatory mediators such as cytokines, MMP-1, and MMP-3 in the ankle joint tissue. SPE significantly suppressed the expression of cytokines and MMP-1 by down-regulating NF-κB, Akt, and mitogen-activated protein kinases in RA synovial fibroblasts. Taken together, these results indicate that SPE is therapeutically efficacious against chronic inflammatory arthritis, suggesting that SPE is a candidate for treating RA.

Purslane suppresses osteoclast differentiation and bone resorbing activity via inhibition of Akt/GSK3ß-c-Fos-NFATc1 signaling in vitro and prevents lipopolysaccharide-induced bone loss in vivo.

Purslane (Portulaca oleracea L.) is popular as a potherb in many areas of Europe, Asia, and the Mediterranean region and is widely distributed around the globe. It has a wide range of pharmacological effects, such as antibacterial, anti-aging, anti-inflammatory, and anti-oxidative properties. Although the extract of purslane has numerous beneficial pharmacological effects, its effect on osteoclasts remains unknown. We aimed to investigate the anti-osteoclastogenic activity in vitro and in vivo and to elucidate the underlying mechanism. The effect of purslane on the differentiation and function of bone marrow-derived macrophages (BMMs) into osteoclasts was examined using a phenotype assay such as tartrate-resistant acid phosphatase (TRAP) staining, F-actin staining, and pit assay and followed by confirmation by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. To address the effect of purslane in vivo, the inflammatory, lipopolysaccharide (LPS)-induced osteolysis mouse model was chosen. Bone volume and bone microarchitecture were evaluated by microcomputed tomography and histologic analysis. Purslane inhibited receptor activator of nuclear factor-kappa B ligand (RANKL)-stimulated osteoclast differentiation accompanied by inhibition of Akt/glycogen synthase kinase 3ß (GSK3ß) signaling, which could underlie purslane-induced downregulation of c-Fos and nuclear factor of activated T cells 1 (NFATc1) expression levels, transcription factors that regulate osteoclast-specific genes, as well as osteoclast fusion and resorption-related molecules. Moreover, in vivo studies further verified the bone protection activity of purslane in the LPS-induced osteolysis animal model. Purslane could exhibit its anti-osteoclastogenic activity by inhibiting Akt/GSK3ß-c-Fos-NFATc1 signaling cascades. Therefore, purslane is a potential natural medicine for the treatment of osteoclast-related diseases.

Phytocomponent 4-hydroxy-3-methoxycinnamaldehyde ablates T-cell activation by targeting protein kinase C-θ and its downstream pathways.

Autoreactive T-cell responses have a crucial role in the pathology and clinical course of autoimmune diseases. Therefore, controlling the activation of these cells is an important strategy for developing therapies and therapeutics. Here, we identified that 4-hydroxy-3-methoxycinnamaldehyde (4H3MC) has a therapeutic potential for T-cell activation by modulating protein kinase C-θ (PKCθ) and its downstream pathways. Pre- and post-treatment with 4H3MC prevented IL-2 release from human transformed and untransformed T cells at the micromolar concentrations without any cytotoxic effects, in fact more efficiently than its structural analogue 4-hydroxycinnamic acid-a previously reported T-cell inhibitor. In silico analysis showed that 4H3MC is a potential inhibitor of PKC isotypes, including PKCθ-a crucial PKC isotype in T cells. Consistently, 4H3MC significantly blocked PKC activity in vitro and also inhibited the phosphorylation of PKCθ in T cells. 4H3MC had no effect on TCR-mediated membrane-proximal-signalling events such as phosphorylation of Zap70. Instead, it attenuated the phosphorylation of mitogen-activated protein kinases (ERK and p38) and promoter activities of NF-κB, AP-1 and NFAT. Taken together, our results provide the evidences that 4H3MC may have curative potential as a novel immune modulator in a broad range of immunopathological disorders by modulating PKCθ activity.

Saikosaponin D isolated from Bupleurum falcatum inhibits selectin-mediated cell adhesion.

Three saikosaponins were isolated from the MeOH extract of the roots of Bupleurum falcatum L.: saikosaponins B3 (1); B4 (2); and D (3). Of the three, compound 3 inhibited the interaction of selectins (E, L, and P) and THP-1 cells with IC50 values of 1.8, 3.0 and 4.3 µM, respectively. Also, the aglycone structure 4 of compound 3 showed moderate inhibitory activity on L-selectin-mediated cell adhesion. From these results, we suspect that compound 3 isolated from Bupleurum falcatum roots would be a good candidate for therapeutic strategies to treat inflammation.

Ampelopsis brevipedunculata extract prevents bone loss by inhibiting osteoclastogenesis in vitro and in vivo.

Osteoclasts play a critical role in bone resorbing disorders such as osteoporosis, periodontitis, and rheumatoid arthritis. Therefore, discovery of agents capable of suppressing osteoclast differentiation may aid the development of a therapeutic access for the treatment of pathological bone loss. Ampelopsis brevipedunculata has been used as herbal folk medicine to treat liver diseases and inflammation in Asia. However, its effects on osteoclast differentiation are unknown. We were aimed to investigate the anti-osteoclastogenic activity in vitro and in vivo and to elucidate the underlying mechanism of Ampelopsis brevipedunculata extract (ABE). In this study, ABE inhibited receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation, the formation of filamentous actin rings and the bone resorbing activity of mature osteoclasts. ABE inhibited RANKL-induced p38 and IκB phosphorylation and IκB degradation. Also, ABE suppressed the mRNA and protein expression of nuclear factor of activated T cells c1 (NFATc1) and c-Fos, and the mRNA expression of genes required for cell fusion and bone resorption, such as osteoclast-associated receptor (OSCAR), tartrate resistant acid phosphatase (TRAP), cathepsin K, dendritic cell-specific transmembrane protein (DC-STAMP), ß3-integrin and osteoclast stimulatory transmembrane protein (OC-STAMP). Furthermore, results of micro-CT and histologic analysis indicated that ABE remarkably prevented lipopolysaccharide (LPS)-induced bone erosion. These results demonstrate that ABE prevents LPS-induced bone erosion through inhibition of osteoclast differentiation and function, suggesting the promise of ABE as a potential cure for various osteoclast-associated bone diseases.

Simultaneous quantitation and validation of triterpenoids and phytosteroids in Phaseolus angularis seeds.

A reproducible analytical method using reverse-phase high liquid performance chromatography combined with UV detecting was developed for the quantitative determination of four compounds isolated from the ethanol extract of Phaseolus angularis seeds (PASE): oleanolic acid (1), oleanolic acid acetate (2), stigmasterol (3) and ß-sitosterol (4). This method was fully validated in terms of linearity (r2 > 0.999), accuracy (98.5%-100.8%), precision (<0.92%), LOD (<0.0035 mg/mL), and LOQ (<0.0115 mg/mL). The effects of the PASE and isolated compounds 1-4 on TLR4 activation were tested in THP1-Blue cells. Among the tested substances, compound 2 showed potent inhibitory activity with an IC50 value of 3.89 ± 0.17 µM.

Salvia plebeia suppresses atopic dermatitis-like skin lesions.

Salvia plebeia R. Br. (Lamiaceae) has been used for folk medicines in Asian countries, including Korea and China, to treat skin inflammatory diseases and asthma. In this study, we investigated the effects of S. plebeia extract (SPE) on atopic dermatitis (AD)-like skin lesions and defined underlying mechanisms of action. We established an AD model in BALB/c mice by repeated local exposure of house dust mite extract (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB) to the ears. Repeated alternative treatment of DFE/DNCB caused AD-like skin lesions. The oral administration of SPE decreased AD symptoms based on ear thickness and histopathological analysis, in addition to serum IgE and IgG2a levels. SPE suppressed mast cell infiltration into the ear and serum histamine level. SPE inhibited Th1/Th2/Th17 phenotype CD4(+) T lymphocytes expansion in the lymph node and the expression of Th1/Th2/Th17 cytokines in the ear tissue. To define the underlying mechanisms of action, the tumor necrosis factor (TNF)-α and interferon (IFN)-γ activated human keratinocytes (HaCaT) model was used. SPE significantly suppressed the expression of cytokines and chemokines through the down-regulation of mitogen-activated protein kinases, nuclear factor-κB, and STAT1 in HaCaT cells. Taken together, our results suggest that SPE might be a candidate for the treatment of AD.

Anti-rotavirus effects by combination therapy of stevioside and Sophora flavescens extract.

Anti-rotaviral activities of Sophora flavescens extract (SFE) and stevioside (SV) from Stevia rebaudiana Bertoni either singly or in various combinations were examined in vitro and in vivo using a porcine rotavirus G5[P7] strain. Combination of SFE and SV inhibited in vitro virus replication more efficiently than each single treatment. In the piglet model, SV had no effect on rotavirus enteritis, whereas SFE improved but did not completely cure rotaviral enteritis. Interestingly, combination therapy of SFE and SV alleviated diarrhea, and markedly improved small intestinal lesion score and fecal virus shedding. Acute toxicity tests including the piglet lethal dose 50, and body weight, organ weight and pathological changes for the combination therapy did not show any adverse effect on the piglets. These preliminary data suggest that the combination therapy of SV and SFE is a potential curative medication for rotaviral diarrhea in pigs. Determination of the efficacy of this combination therapy in other species including humans needs to be addressed in the future.

Genipin inhibits RANKL-induced osteoclast differentiation through proteasome-mediated degradation of c-Fos protein and suppression of NF-κB activation.

People over the age of 50 are at risk of osteoporotic fracture, which may lead to increased morbidity and mortality. Osteoclasts are responsible for bone resorption in bone-related disorders. Genipin is a well-known geniposide aglycon derived from Gardenia jasminoides, which has long been used in oriental medicine for controlling diverse conditions such as inflammation and infection. We aimed to evaluate the effects of genipin on RANKL-induced osteoclast differentiation and its mechanism of action. Genipin dose-dependently inhibited early stage RANKL-induced osteoclast differentiation in bone marrow macrophages (BMMs) during culture. Genipin inhibited RANKL-induced IκB degradation and suppressed the mRNA expression of osteoclastic markers such as NFATc1, TRAP, and OSCAR in RANKL-treated BMMs, but did not affect c-Fos mRNA expression. Interestingly, genipin markedly inhibited c-Fos protein expression in BMMs, which was reversed in the presence of the proteosome inhibitor MG-132. Furthermore, genipin inhibited RANKL-mediated osteoclast differentiation, which was also rescued by overexpression of c-Fos and NFATc1 in BMMs. Taken together, our findings indicate that genipin down-regulated RANKL-induced osteoclast differentiation through inhibition of c-Fos protein proteolysis as well as inhibition of IκB degradation. Our findings indicate that genipin could be a useful drug candidate that lacks toxic side effects for the treatment of osteoporosis.

Oleanolic acid acetate inhibits osteoclast differentiation by downregulating PLCγ2-Ca(2+)-NFATc1 signaling, and suppresses bone loss in mice.

Owing to their potential pharmacological activities in human disease, natural plant-derived compounds have recently become the focus of increased research interest. In this study, we first isolated oleanolic acid acetate (OAA), a triterpenoid compound, from Vigna angularis (azuki bean) to discover anti-bone resorptive agents. Many studies have identified and described the various medicinal effects of V. angularis extract. However, the pharmacological effect of OAA-derived V. angularis extract, particularly the effect on osteoclastogenesis, is not known. Therefore, we investigated the effect and mechanism of OAA in receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. OAA inhibited RANKL-induced osteoclast differentiation in bone marrow macrophages (BMMs) without any evidence of cytotoxicity. Interestingly, OAA significantly inhibited Btk phosphorylation, phospholipase Cγ2 (PLCγ2) phosphorylation, calcium ion (Ca(2+)) oscillation, and nuclear factor of activated T cell c1 (NFATc1) expression in RANKL-stimulated BMMs, but did not affect RANKL-induced mitogen-activated protein kinase. OAA also inhibited the bone-resorbing activity of mature osteoclasts. Furthermore, mice treated with OAA demonstrated marked attenuation of lipopolysaccharide-induced bone erosion based on micro-computed tomography and histologic analysis of femurs. Taken together, the results suggested that OAA inhibited RANKL-mediated osteoclastogenesis via PLCγ2-Ca(2+)-NFATc1 signaling in vitro and suppressed inflammatory bone loss in vivo.

Vigna angularis inhibits IL-6-induced cellular signalling and ameliorates collagen-induced arthritis.

OBJECTIVES: The present study was conducted in order to assess whether extracts or isolated compounds from Vigna angularis were able to suppress IL-6 signalling and to show the therapeutic effect on collagen-induced arthritis (CIA) in mice. METHODS: The effect of V. angularis on IL-6 signalling was studied by measuring Stat3-dependent luciferase activity, expression of inflammation-related genes, and phosphorylation of Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) induced by IL-6. CIA was induced by immunizing with bovine type II collagen. V. angularis extract (VAE) was administrated orally at 50 and 100 mg/kg from day 1 to day 28. Induction of arthritis was evaluated with a visual scoring system and histological analysis. RESULTS: Extracts or two triterpenoid compounds from V. angularis showed potent inhibitory effects on pSTAT3-inducible luciferase activity, STAT3 tyrosine phosphorylation and the expression of inflammation-related genes induced by IL-6. Administration of VAE significantly suppressed the progression of CIA, accompanied by a reduced antibody response to type II collagen and protection from tissue damage in knee joints. CONCLUSION: Administration of VAE has a therapeutic effect on CIA and this effect is associated with the inhibitory activity on IL-6/STAT3 signalling. These results suggest that extracts or compounds from V. angularis could be a useful treatment for diseases related to IL-6, including RA.

Chlorogenic acid inhibits osteoclast differentiation and bone resorption by down-regulation of receptor activator of nuclear factor kappa-B ligand-induced nuclear factor of activated T cells c1 expression.

Excessive osteoclastic bone resorption plays a critical role in inflammation-induced bone loss such as rheumatoid arthritis and periodontal bone erosion. Therefore, identification of osteoclast targeted-agents may be a therapeutic approach to the treatment of pathological bone loss. In this study, we isolated chlorogenic acid (CGA) from fructus of Gardenia jasminoides to discover anti-bone resorptive agents. CGA is a polyphenol with anti-inflammatory and anti-oxidant activities, however, its effects on osteoclast differentiation is unknown. Thus, we investigated the effect of CGA in receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL)-induced osteoclast differentiation and RANKL signaling. CGA dose-dependently inhibited RANKL-mediated osteoclast differentiation in bone marrow macrophages (BMMs) without any evidence of cytotoxicity. CGA inhibited the phosphorylation of p38, Akt, extracellular signal-regulated kinase (ERK), and inhibitor of nuclear factor-kappa B (IκB), and IκB degradation by RANKL treatment. CGA suppressed the mRNA expression of nuclear factor of activated T cells c1 (NFATc1), TRAP and OSCAR in RANKL-treated bone marrow macrophages (BMMs). Also, overexpression of NFATc1 in BMMs blocked the inhibitory effect of CGA on RANKL-mediated osteoclast differentiation. Furthermore, to evaluate the effects of CGA in vivo, lipopolysaccharide (LPS)-induced bone erosion study was carried out. CGA remarkably attenuated LPS-induced bone loss based on micro-computed tomography and histologic analysis of femurs. Taken together, our findings suggest that CGA may be a potential treatment option for osteoclast-related diseases with inflammatory bone destruction.