The natural flavonoid galangin inhibits osteoclastic bone destruction and osteoclastogenesis by suppressing NF-κB in collagen-induced arthritis and bone marrow-derived macrophages

We investigated the effect of galangin, a natural flavonoid, on osteoclastic bone destruction in collagen-induced arthritis and examined the molecular mechanisms by which galangin affects osteoclastogenesis in bone marrow derived macrophages. In mice with collagen-induced arthritis, administration of galangin significantly reduced the arthritis clinical score, edema and severity of disease without toxicity. Interestingly, galangin treatment during a later stage of collagen-induced arthritis, using mice with a higher clinical arthritis score, still significantly slowed the progression of the disease. Extensive cartilage and bone erosive changes as well as synovial inflammation, synovial hyperplasia and pannus formation were dramatically inhibited in arthritic mice treated with galangin. Furthermore, galangin-treated arthritic mice showed a significant reduction in the concentrations of IL-1β, TNF-α and IL-17 . We found that galangin inhibited osteoclastogenic factors and osteoclast formation in bone marrow-derived macrophages and osteoblast co-cultured cells, and increased osteoprotegerin (OPG) levels in osteoblasts. Galangin and NF-κB siRNA suppressed RANKL-induced phosphorylation of the c-jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), but not AKT and extracellular signal-regulated kinase 1/2 (ERK1/2). Also, the JNK inhibitor SP600125 and p38 inhibitor SB203580 reduced RANKL-induced expressions of phospho-c-Jun, c-fos and NFATc1 genes during osteoclast development. In addition, galangin suppressed RANKL-induced phosphorylation of NF-κB, phospho-IκBα, inflammatory cytokines and osteoclast formation in bone marrow-derived macrophages. Our data suggest that galangin prevented osteoclastic bone destruction and osteoclastogenesis in osteoclast precursors as well as in collagen-induced arthritis mice without toxicity via attenuation of RANKL-induced activation of JNK, p38 and NF-κB pathways.     

c-Jun NH2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 is a critical regulator for arthritis progression by meditating inflammation in mice model

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease. However, the pathogenesis of RA is not fully understood. Here, we reported that c-Jun NH2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1, also known as JNK-interacting protein 3 (JIP3)) was significantly important for collagen-induced arthritis (CIA) in mice. Mice with JIP3 knockout (JIP3^−/−) showed a significant decrease in arthritis index and swollen joint count in CIA mice. The histopathology of spleen and joint was markedly alleviated by JIP3 deficiency in CIA mice. Excessive macrophage activation in CIA mice was also inhibited by JIP3 deletion. CIA-induced RANKL/RANK/OPG system mRNA expression was blocked in JIP3-knockout mice. In addition, CIA-triggered cytokine secretion and TLRs/NF-κB activation was inactivated by JIP3-deficiency. In line with the inhibition of inflammation by JIP3-knockout, it also significantly suppressed JNK pathway activation induced by CIA, as evidenced by the down-regulation of p-JNK, p-c-Jun, AFT-2 and Elk-1 in joints. In vitro, RANKL-exposed RAW264.7 cells showed a significant reduction of osteoclast formation using TRAP staining. Moreover, JIP3 inhibition reduced the RANKL-caused expression of osteoclastic genes and inflammatory regulators, as well as activation of TLRs/NF-κB and JNK signaling pathways. Importantly, we found that promoting JNK activity could abrogate JIP3 knockdown-suppressed osteoclastic genes expression, inflammatory response and NF-κB activation. These findings suggested that JIP3 could significantly impede osteoclast formation and function by regulating JNK activation, illustrating a novel therapeutic strategy for managing arthritis and preventing bone destruction.     

Tatarinan O,a lignin-like compound from the roots of Acorus tatarinowii Schott inhibits osteoclast differentiation through suppressing the expression of c-Fos and NFATc1

Osteoclasts (OC) are large multinucleated cells derived from monocyte/macrophage precursors. Suppressing osteoclastogenesis is considered as an effective therapeutic approach to erosive bone disease. The root of Acorus tatarinowii Schott, a well-known traditional Chinese medicine was used to treat rheumatosis and other inflammatory disease. However, the effects of tatarinan O (TO), one of the lignin-like compounds isolated from the roots of Acorus tatarinowii Schott during bone development are still unclear. In the present study, we explored the effect of TO on RANKL-induced osteoclastogenesis in vitro. TO was found to suppress osteoclast differentiation from RANKL-stimulated mouse bone marrow macrophages (BMMs) without significant cytotoxicity. TO also dose-dependently suppressed bone resorption activity of mature osteoclasts. Additionally, TO apparently inhibited the expression of osteoclastic marker genes, such as MMP-9, Cts K and TRAP. Furthermore, our results showed that TO decreased RANKL-induced expression of c-Fos and NFATc1 without influencing NF-κB activation and MAPK phosphorylation. Hence, for the first time we revealed that TO dose-dependently inhibited osteoclastogenesis from RANKL-stimulated mouse BMMs via decreasing the expression of NFATc1 and c-Fos.     

Sciadopitysin suppresses RANKL-mediated osteoclastogenesis and prevents bone loss in LPS-treated mice

Previous studies reported that sciadopitysin (Sc), a type of biflavonoids, protects reactive oxygen species (ROS)-mediated osteoblast dysfunction, but its role in osteoclastogenesis remains unclear. In this study, we observed that Sc dose-dependently suppressed RANKL-induced osteoclastogenesis and bone resorption. Our results indicated that Sc treatment strongly reduced RANKL-induced osteoclast-specific genes expression, including cathepsin K (CTSK), tartrate-resistant acid phosphatase (TRAP) and MMP-9. Furthermore, Sc apparently attenuated RANKL-increased expressions of c-Fos and NFATc1. Meanwhile, Sc also strikingly inhibited the activation of NF-κB without altering the phosphorylation of MAPKs (p38, JNK and ERK1/2). Finally, our study demonstrated that Sc administration could reverse the bone loss in LPS-induced mice model. This study suggests that Sc inhibits RANKL-induced osteoclastogenesis and bone loss by inhibiting NF-κB activation and reducing the expression of c-Fos and NFATc1. Therefore, Sc might be benefit for RANKL-mediated osteolytic bone diseases.     

Chebulanin exerts its anti-inflammatory and anti-arthritic effects via inhibiting NF-κB and MAPK activation in collagen-induced arthritis mice

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovial inflammation and progressive joint destruction. Chebulanin is a natural polyphenol acid isolated from the traditional Tibetan medicine Terminalia chebula Retz that has previously been reported to possess anti-inflammatory properties. The present study aimed to investigate the anti-inflammatory and anti-arthritic effects of chebulanin and explore its underlying mechanisms in vivo and in vitro using a collagen-induced arthritis (CIA) mouse model and lipopolysaccharide (LPS) stimulated RAW264.7 cell inflammation model. Arthritis severity scores were assessed twice weekly; the levels of cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum were detected using enzyme-linked immunosorbent assay kits; histopathological assessment was performed using micro computed tomography and hematoxylin and eosin staining. Activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways were assessed using western blotting. The inhibition of translocation of cytosolic p38 and p65 into the nucleus was observed using immunofluorescence staining and western blotting in vitro. Chebulanin significantly suppressed the progression and development of RA in CIA mice by decreasing the arthritis severity scores, attenuating paw swelling and joint destruction, and reducing the levels of IL-6 and TNF-α significantly (p < 0.05). Furthermore, chebulanin reduced the levels of excised phosphorylated (p)-p38, phosphorylated-c-JUN N-terminal kinase (p-JNK), p-p65 and phosphorylated NF-κB inhibitor alpha (p-IκBα) in CIA mice, but did not affect the level of phosphorylated extracellular-signal-regulated kinase (ERK). In addition, chebulanin could inhibit the nuclear translocation of p38 and p65 in LPS-stimulated macrophages in dose-dependent manner. In conclusion, this study demonstrated that chebulanin exerts anti-inflammatory and anti-arthritic effects by inhibiting the activation of NF-κB and MAPK signaling pathways.     

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.     

SND-117, a sinomenine bivalent alleviates type II collagen-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder that affects about 1% of the population worldwide. RA is mainly manifested by persistent synovitis and progressive joint destruction. The aim of the present study was to examine the anti-arthritis effects of SND-117, a sinomenine bivalent that is obtained from the structure modification of a clinically available anti-RA drug, sinomenine. The arthritis model (CIA) was established by immunizing DBA/1 mice with type II collagen, and the arthritis scores including inflammation, joint destruction and bone erosion were assessed after booster immunization for 3 weeks. The levels of cytokines such as IL-1β, IL-6 and TNF-α were analyzed by quantitative PCR and ELISA. The TNF-α induced NF-κB activation in fibroblast-like synovial cells (FLSCs) was analyzed by Western blot. SND-117 significantly relieved the inflammatory symptoms of collagen-induced arthritis, reduced bone erosion and joint destruction in CIA mice. The serum levels of IL-1β, IL-6 and TNF-α of CIA mice were markedly decreased by SND-117. SND-117 also strongly inhibited the phosphorylation and nuclear translocation of NF-κB p65 in FLSCs upon TNF-α stimulation. These data demonstrated that SND-117 could effectively block the pathogenesis of collagen-induced arthritis in CIA mice via inhibition of NF-κB signaling, and might provide potential clinic benefits in rheumatoid arthritis management.     

青藤碱对胶原诱导性关节炎小鼠肿瘤坏死因子-α、白介素-17及核因子-κB的影响

目的 观察青藤碱(SIN)对胶原诱导性关节炎(CIA)小鼠关节炎指数(AI)评分、血清肿瘤坏死因子-α(TNF-α)、白细胞介素-17(IL-17)及滑膜核因子-κB(NF-κB)蛋白表达的影响.方法 将30只DBA/1小鼠用随机数字表法分为正常组、CIA组、SIN组3组,每组各10只,诱导CIA组与SIN组小鼠建立CIA模型,予青藤碱(SIN)药物干预SIN组,对三组分别进行AI评分,测定血清TNF-α、IL-17的水平及滑膜NF-κB蛋白的表达.结果 SIN组和CIA组TNF-α、IL-17的水平及滑膜NF-κB蛋白的表达均较正常组升高,且SIN组小鼠的AI评分较CIA组明显降低,血清TNF-α[(170.73±11.05)pg·mL-1比(347.97±13.45)pg·mL-1,F=1021.67,P<0.01]、IL-17[(470.30±122.02)pg·mL-1比(621.78±48.96)pg·mL-1,F=184.42,P<0.01]水平明显减少,滑膜NF-κB[(0.53±0.04)pg·mL-1比(0.84±0.04)pg·mL-1,F=804.05,P<0.01]蛋白的表达下调.结论 SIN能改善CIA小鼠关节肿胀,降低血清TNF-α、IL-17的分泌,这可能与其下调了滑膜NF-κB的表达有关.     

实验性关节炎大鼠滑膜组织核因子-κB基质金属蛋白酶-9表达相关性分析

目的观察核因子κB(NF-κB)、基质金属蛋白酶(MMP)-9在实验性关节炎(CIA)和对照组大鼠滑膜组织中不同时间点的表达差异及其血浆中肿瘤坏死因子(TNF)-α、白细胞介素(IL)-1β的含量变化,探讨这些细胞因子在CIA发病中的作用机制,为类风湿关节炎(RA)今后的治疗提供理论依椐。方法将42只雄性Wistar大鼠随机分为模型组和对照组,通过免疫组织化学的方法检测各组大鼠不同时期滑膜组织NF-κB、MMP-9的表达水平,用放射免疫法(RIA)测定TNF-α、IL-1β的血浆含量,同时观察其发病时间与关节炎指数(AI)积分、病理评分及上述细胞因子之间的关系。结果随着CIA大鼠发病时间延长,AI和病理评分逐渐增加,NF-κB、MMP-9表达水平和TNF-α、IL-1β血浆含量也随之增加。CIA大鼠这些细胞因子的测定值都显著高于对照组(P<0.01),AI、病理评分与NF-κB、MMP-9呈正相关关系(P<0.05);CIA大鼠滑膜组织NF-κB、MMP-9表达水平之间呈正相关(P<0.05),而且它们的表达水平与IL-1β、TNF-α血浆含量之间亦呈正相关(P<0.05)。结论通过与TNF-α和IL-1β相互作用,滑膜组织中NF-κB、MMP-9的表达之间可能互相影响、互相促进,形成正反馈式的损坏机制,在CIA大鼠病情进展中起着重要作用,可能是RA发生发展以及骨质侵蚀的关键因子。     

Regulation of osteoclastogenesis by ganoderic acid DM isolated from Ganoderma lucidum

The preventative effects of the ethanol extracts of Ganoderma lucidum against the ovariectomized (Ovx)-induced deterioration of bone density in 11-week-old female Sprague Dawley (SD) rats were investigated. The results showed that the G. lucidum-treated Ovx rats showed improved bone density compared with the Ovx rats. We studied the effects of G. lucidum on osteoclastic differentiation using bone marrow cells and RAW 264 cell D-clone (RAW-D). Differentiation, in response to receptor activator of NF-κB ligand (RANKL) and a tumor necrosis factor α (TNF-α), was inhibited by the ethanol extracts of G. lucidum and ganoderic acid DM which was isolated as one of the active compounds by bioassay-guided fractionation. Ganoderic acid DM especially suppresses the expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1). This suppression leads to the inhibition of dendritic cell-specific transmembrane protein (DC-STAMP) expression and reduces osteoclast fusion.     

A novel anti-inflammatory and immunomodulatory drug CP-25 alleviated collagen induced arthritis by down-regulating BAFF-NF-κκB signaling pathway

OBJECTIVE To investigated the regulatory effect of paeoniflorin-6′-O-benzene sulfonate(CP-25) on B cell activating factor(BAFF)/BAFF receptor-nuclear factor of kappa B(NF-κB) signaling in B cell of collagen induced-arthritis(CIA) mice.METHODS Mice CIA was induced by injection of typeⅡcollagen(CⅡ).The arthritis index(AI) and swollen joint count(SJC) were assessed,and histopathology of spleen and joints were observed.The percentage of B cells subsets,BAFF receptor expressions were analyzed by flow cytometry.BAFF and immunoglobulin(Ig) levels were measured by protein antibody array.The expressions of TRAF2,MKK3,MKK6,p-P38,and p-NF-κB65 in NF-κB signaling mediated by BAFF were analyzed by western blot.RESULTS CP-25 decreased AI and SJC,restored abnormal weights,reduced thymus index and spleen index,inhibited T/B cells proliferation,alleviated the histopathology of spleen and joints in CIA mice.CP-25 also reduced high levels of serum BAFF and immunoglobulin,decreased CD19+B cells,CD19+CD27+B cells,and CD19-CD27+CD138+plasma cells,inhibited BAFFR and TACI expressions,decreased the expressions of TRAF2,MKK3,MKK6,p-P38,and p-NF-κB65.Compared with biological agents etanercept and rituximab,CP-25 restored high T cells proliferation and percentages of B subsets to normal level,and recovered the high levels of IgA,IgD,IgG1,IgG2 a and high expressions molecules in NF-κB signaling to normal levels.The action intensity of rituximab and etanercept was more strong than CP-25.The inhibitor effects of rituximab and etanercept on AI and SJC,thymus index,proliferation of T cells and B cells subsets were strong,and down-regulated the indexes to under normal levels.CONCLUSION CP-25 might be a promising anti-inflammatory immune and regulation drug,which alleviated CIA and regulated the functions of B cells through BAFF/BAFF receptor-NF-κB signaling.     

Naltrexone (NTX) relieves inflammation in the collagen-induced- arthritis (CIA) rat models through regulating TLR4/NFκB signaling pathway

ObjectiveOur aim was to study the efficacy and mechanism by which NTX alleviate arthritis in CIA rat models in vivo.MethodsFemale Wistar rats were randomly divided into 6 groups, their weights were observed and the severity of arthritis and pathological changes were evaluated by HE staining. T lymphocyte subsets were detected by flow cytometry. The expression of cytokines was detected in peripheral serum by ELISA. Real time PCR, immunohistochemical staining and western blot analysis were utilized to detect the mRNA and protein expression of opioid receptors, TLR4, RANKL and /NF-κB in synovial tissue and the spleen.ResultsThe weight of the rats in the 10 mg/kg NTX group decreased the least, and had the least severe arthritis. CD4⁺ T cells, Th1 cells and Treg cells increased, and CD8⁺T cells, Th1 cells and Th17 cells decreased in the splenic lymphocytes. The expression of proinflammatory cytokines decreased, and the expression of anti-inflammatory cytokines increased. MOR and DOR were strongly expressed in the spleen, whereas KOR and DOR were strongly expressed in synovial tissue. The expression of TLR4, NF-κB and RANKL was reduced in the spleen and synovium in the NTX group.ConclusionsNTX relieved the severity of arthritis in the CIA rat models at a concentration of 10 mg/kg by regulating T lymphocyte subsets and the expression of cytokines. NTX affected opioid receptors to inhibit the TLR4/NF-κB signaling pathway, regulating the systemic immune response and decreasing osteoclast differentiation, thereby alleviating inflammation and the erosion of articular cartilage along with bone tissue.