scholarly journals Anti-Osteoporosis Effects of the Eleutherococcus senticosus, Achyranthes japonica, and Atractylodes japonica Mixed Extract Fermented with Nuruk

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 3904
Author(s):  
So Young Eun ◽  
Yoon-Hee Cheon ◽  
Gyeong Do Park ◽  
Chong Hyuk Chung ◽  
Chang Hoon Lee ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Diseases ◽  
Marker Genes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Specific Marker ◽  
Eleutherococcus Senticosus ◽  
Achyranthes Japonica ◽  
Atractylodes Japonica

Vigeo is a mixture of fermented extracts of Eleutherococcus senticosus Maxim (ESM), Achyranthes japonica (Miq.) Nakai (AJN), and Atractylodes japonica Koidzumi (AJK) manufactured using the traditional Korean nuruk fermentation method. Although the bioactive effects of ESM, AJN, and AJK have already been reported, the pharmacological effects of Vigeo have not been proven. Therefore, in this study, we investigated whether Vigeo had inhivitory effects on lipopolysaccharide (LPS)-induced inflammatory bone loss in vivo and receptor activator of nuclear factor-B ligand (RANKL)-induced osteoclastogenesis and the related mechanism in vitro. Vigeo administration conferred effective protection against bone loss induced by excessive inflammatory response and activity of osteoclasts in LPS-induced inflammatory osteoporosis mouse model. In addition, Vigeo significantly suppressed the formation of tartrate-resistant acid phosphatase-positive osteoclasts induced by RANKL and inhibited F-actin formation and bone resorbing activity without any cytotoxicity. Moreover, Vigeo significantly inhibited RANKL-induced phosphorylation of p38, ERK, JNK, IκB, and AKT and degradation of IkB. Additionally, Vigeo strongly inhibited the mRNA and protein expression of c-FOS and NFATc1 and subsequently attenuated the expression of osteoclast specific marker genes induced by RANKL. We demonstrated for the first time the anti-osteoporosis effect of Vigeo, suggesting that it could be a potential therapeutic candidate for the treatment of osteoclast-mediated inflammatory bone diseases.

scholarly journals 3-Hydroxyolean-12-en-27-oic Acids Inhibit RANKL-Induced Osteoclastogenesis in Vitro and Inflammation-Induced Bone Loss in Vivo

2020 ◽  
Vol 21 (15) ◽  
pp. 5240
Author(s):  
Wonyoung Seo ◽  
Suhyun Lee ◽  
Phuong Thao Tran ◽  
Thi Quynh-Mai Ngo ◽  
Okwha Kim ◽  
...  
Keyword(s):  
Bone Destruction ◽  
Osteoclast Formation ◽  
Bone Diseases ◽  
Marker Genes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Specific Marker ◽  
Nuclear Factor ◽  
Activated T Cells

Olean-12-en-27-oic acids possess a variety of pharmacological effects. However, their effects and underlying mechanisms on osteoclastogenesis remain unclear. This study aimed to investigate the anti-osteoclastogenic effects of five olean-12-en-27-oic acid derivatives including 3α,23-isopropylidenedioxyolean-12-en-27-oic acid (AR-1), 3-oxoolean-12-en-27-oic acid (AR-2), 3α-hydroxyolean-12-en-27-oic acid (AR-3), 23-hydroxy-3-oxoolean-12-en-27-oic acid (AR-4), and aceriphyllic acid A (AR-5). Among the five olean-12-en-27-oic acid derivatives, 3-hydroxyolean-12-en-27-oic acid derivatives, AR-3 and AR-5, significantly inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced mature osteoclast formation by reducing the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, F–actin ring formation, and mineral resorption activity. AR-3 and AR-5 decreased RANKL-induced expression levels of osteoclast-specific marker genes such as c-Src, TRAP, and cathepsin K (CtsK) as well as c-Fos and nuclear factor of activated T cells cytoplasmic 1 (NFATc1). Mice treated with either AR-3 or AR-5 showed significant protection of the mice from lipopolysaccharide (LPS)-induced bone destruction and osteoclast formation. In particular, AR-5 suppressed RANKL-induced phosphorylation of JNK and ERK mitogen-activated protein kinases (MAPKs). The results suggest that AR-3 and AR-5 attenuate osteoclast formation in vitro and in vivo by suppressing RANKL-mediated MAPKs and NFATc1 signaling pathways and could potentially be lead compounds for the prevention or treatment of osteolytic bone diseases.

scholarly journals Inhibitory Effects of N-[2-(4-acetyl-1-piperazinyl) phenyl]-2-(2-chlorophenoxy) acetamide on Osteoclast Differentiation In Vitro via the Downregulation of TRAF6

2019 ◽  
Vol 20 (20) ◽  
pp. 5196 ◽  
Author(s):  
Zhihao Chen ◽  
Eunjin Cho ◽  
Jinkyung Lee ◽  
Sunwoo Lee ◽  
Tae-Hoon Lee
Keyword(s):  
Bone Resorption ◽  
Mononuclear Cells ◽  
Osteoclast Differentiation ◽  
Bone Diseases ◽  
Marker Genes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Specific Marker ◽  
Potential Candidate ◽  
Dependent Manner

Osteoclasts are poly-nuclear cells that resorb mineral components from old or damaged bone tissue. Primary mononuclear cells are activated by receptor activator of nuclear factor kappa-Β ligand (RANKL) and differentiate into large multinucleated cells. Dysregulation of osteoclast differentiation can lead to pathological bone loss and destruction. Many studies have focused on the development of new molecules to regulate RANKL-mediated signaling. In this study, N-[2-(4-acetyl-1-piperazinyl)phenyl]-2-(2-chlorophenoxy) acetamide (PPOA-N-Ac-2-Cl) led to a significant decrease in the formation of multinucleated tartrate-resistant acid phosphatase (TRAP)-positive cells in a dose-dependent manner, without inducing significant cytotoxicity. PPOA-N-Ac-2-Cl affected the expression of osteoclast-specific marker genes, such as TRAF6, c-fos, DC-STAMP, NFATc1, MMP9, CtsK, and TRAP (Acp5), during RANKL-mediated osteoclastogenesis. Moreover, PPOA-N-Ac-2-Cl significantly attenuated the protein levels of CtsK, a critical protease involved in bone resorption. Accordingly, bone resorption activity and F-actin ring formation decreased in the presence of PPOA-N-Ac-2-Cl. In conclusion, this study shows that PPOA-N-Ac-2-Cl acts as an inhibitor of osteoclast differentiation and may serve as a potential candidate agent for the treatment of osteoclast-related bone diseases by virtue of attenuating bone resorption.

scholarly journals Monocrotaline Suppresses RANKL-Induced Osteoclastogenesis In Vitro and Prevents LPS-Induced Bone Loss In Vivo

2018 ◽  
Vol 48 (2) ◽  
pp. 644-656 ◽  
Author(s):  
Cheng-Ming Wei ◽  
Yi-Ji Su ◽  
Xiong Qin ◽  
Jia-Xin Ding ◽  
Qian Liu ◽  
...  
Keyword(s):  
Critical Role ◽  
Osteoclast Differentiation ◽  
Osteoclast Formation ◽  
Bone Diseases ◽  
Marker Genes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Dependent Manner ◽  
And Function

Background/Aims: Extensive osteoclast formation plays a critical role in bone diseases, including rheumatoid arthritis, periodontitis and the aseptic loosening of orthopedic implants. Thus, identification of agents that can suppress osteoclast formation and bone resorption is important for the treatment of these diseases. Monocrotaline (Mon), the major bioactive component of crotalaria sessiliflora has been investigated for its anti-cancer activities. However, the effect of Mon on osteoclast formation and osteolysis is not known. Methods: The bone marrow macrophages (BMMs) were cultured with M-CSF and RANKL followed by Mon treatment. Then the effects of Mon on osteoclast differentiation were evaluated by counting TRAP (+) multinucleated cells. Moreover, effects of Mon on hydroxyapatite resorption activity of mature osteoclast were studied through resorption areas measurement. The involved potential signaling pathways were analyzed by performed Western blotting and quantitative real-time PCR examination. Further, we established a mouse calvarial osteolysis model to measure the osteolysis suppressing effect of Mon in vivo. Results: In this study, we show that Mon can inhibit RANKL-induced osteoclast formation and function in a dose-dependent manner. Mon inhibits the expression of osteoclast marker genes such as tartrate-resistant acid phosphatase (TRAP) and cathepsin K. Furthermore, Mon inhibits RANKL-induced the activation of p38 and JNK. Consistent with in vitro results, Mon exhibits protective effects in an in vivo mouse model of LPS-induced calvarial osteolysis. Conclusion: Taken together our data demonstrate that Mon may be a potential prophylactic anti-osteoclastic agent for the treatment of osteolytic diseases caused by excessive osteoclast formation and function.

scholarly journals Estrogen Decreases Cytoskeletal Organization by Forming an ERα/SHP2/c-Src Complex in Osteoclasts to Protect against Ovariectomy-Induced Bone Loss in Mice

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 619
Author(s):  
Hyun-Jung Park ◽  
Malihatosadat Gholam-Zadeh ◽  
Sun-Young Yoon ◽  
Jae-Hee Suh ◽  
Hye-Seon Choi
Keyword(s):  
Bone Resorption ◽  
Bone Loss ◽  
Ring Formation ◽  
Tartrate Resistant Acid Phosphatase ◽  
Actin Ring ◽  
Collagen Crosslinks ◽  
Trap Staining ◽  
Src Activation

Loss of ovarian function is closely related to estrogen (E2) deficiency, which is responsible for increased osteoclast (OC) differentiation and activity. We aimed to investigate the action mechanism of E2 to decrease bone resorption in OCs to protect from ovariectomy (OVX)-induced bone loss in mice. In vivo, tartrate-resistant acid phosphatase (TRAP) staining in femur and serum carboxy-terminal collagen crosslinks-1 (CTX-1) were analyzed upon E2 injection after OVX in mice. In vitro, OCs were analyzed by TRAP staining, actin ring formation, carboxymethylation, determination of reactive oxygen species (ROS) level, and immunoprecipitation coupled with Western blot. In vivo and in vitro, E2 decreased OC size more dramatically than OC number and Methyl-piperidino-pyrazole hydrate dihydrochloride (MPPD), an estrogen receptor alpha (ERα) antagonist, augmented the OC size. ERα was found in plasma membranes and E2/ERα signaling affected receptor activator of nuclear factor κB ligand (RANKL)-induced actin ring formation by rapidly decreasing a proto-oncogene tyrosine-protein kinase, cellular sarcoma (c-Src) (Y416) phosphorylation in OCs. E2 exposure decreased physical interactions between NADPH oxidase 1 (NOX1) and the oxidized form of c-Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), leading to higher levels of reduced SHP2. ERα formed a complex with the reduced form of SHP2 and c-Src to decrease c-Src activation upon E2 exposure, which blocked a signal for actin ring formation by decreased Vav guanine nucleotide exchange factor 3 (Vav3) (p–Y) and Ras-related C3 botulinum toxin substrate 1 (Rac1) (GTP) activation in OCs. E2/ERα signals consistently inhibited bone resorption in vitro. In conclusion, our study suggests that E2-binding to ERα forms a complex with SHP2/c-Src to attenuate c-Src activation that was induced upon RANKL stimulation in a non-genomic manner, resulting in an impaired actin ring formation and reducing bone resorption.

scholarly journals Constitutive Activation of β-Catenin in Differentiated Osteoclasts Induces Bone Loss in Mice

2018 ◽  
Vol 48 (5) ◽  
pp. 2091-2102 ◽  
Author(s):  
Xin Sui ◽  
Shijian Deng ◽  
Mengmeng Liu ◽  
Linlin Fan ◽  
Yunfei Wang ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Mass ◽  
Bone Growth ◽  
Osteoclast Differentiation ◽  
Marker Genes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Bone Homeostasis ◽  
Micro Computed Tomography ◽  
Constitutive Activation

Background/Aims: Activation of the Wnt/β-catenin signalling pathway has been widely investigated in bone biology and shown to promote bone formation. However, its specific effects on osteoclast differentiation have not been fully elucidated. Our study aimed to identify the role of β-catenin in osteoclastogenesis and bone homeostasis. Methods: In the present study, exon 3 in the β-catenin gene (Ctnnb1) allele encoding phosphorylation target serine/threonine residues was flanked by floxP sequences. We generated mice exhibiting conditional β-catenin activation (Ctsk-Cre;Ctnnb1flox(exon3)/+, designated CA-β-catenin) by crossing Ctnnb1flox(exon3)/flox(exon3) mice with osteoclast-specific Ctsk-Cre mice. Bone growth and bone mass were analysed by micro-computed tomography (micro-CT) and histomorphometry. To further examine osteoclast activity, osteoclasts were induced from bone marrow monocytes (BMMs) isolated from CA-β-catenin and Control mice in vitro. Osteoclast differentiation was detected by tartrate-resistant acid phosphatase (TRAP) staining, immunofluorescence staining and reverse transcription-quantitative PCR (RT–qPCR) analysis. Results: Growth retardation and low bone mass were observed in CA-β-catenin mice. Compared to controls, CA-β-catenin mice had significantly reduced trabecular bone numbers under growth plates as well as thinner cortical bones. Moreover, increased TRAP-positive osteoclasts were observed on the surfaces of trabecular bones and cortical bones in the CA-β-catenin mice; consistent results were observed in vitro. In the CA-β-catenin group, excessive numbers of osteoclasts were induced from BMMs, accompanied by the increased expression of osteoclast-associated marker genes. Conclusion: These results indicated that the constitutive activation of β-catenin in osteoclasts promotes osteoclast formation, resulting in bone loss.

scholarly journals Fucoidan Prevents RANKL-Stimulated Osteoclastogenesis and LPS-Induced Inflammatory Bone Loss via Regulation of Akt/GSK3β/PTEN/NFATc1 Signaling Pathway and Calcineurin Activity

Marine Drugs ◽  
2019 ◽  
Vol 17 (6) ◽  
pp. 345 ◽  
Author(s):  
Sheng-Hua Lu ◽  
Yi-Jan Hsia ◽  
Kuang-Chung Shih ◽  
Tz-Chong Chou
Keyword(s):  
Bone Loss ◽  
Molecular Mechanisms ◽  
Bone Erosion ◽  
Osteoclast Differentiation ◽  
Bone Diseases ◽  
Nuclear Factor ◽  
Activated T Cells ◽  
Calcineurin Activity

Excessive osteoclast differentiation and/or function plays a pivotal role in the pathogenesis of bone diseases such as osteoporosis and rheumatoid arthritis. Here, we examined whether fucoidan, a sulfated polysaccharide present in brown algae, attenuates receptor activator of nuclear factor-κB ligand (RANKL)-stimulated osteoclastogenesis in vitro and lipopolysaccharide (LPS)-induced bone resorption in vivo, and investigated the molecular mechanisms involved. Our results indicated that fucoidan significantly inhibited osteoclast differentiation in RANKL-stimulated macrophages and the bone resorbing activity of osteoclasts. The effects of fucoidan may be mediated by regulation of Akt/GSK3β/PTEN signaling and suppression of the increase in intracellular Ca2+ level and calcineurin activity, thereby inhibiting the translocation of nuclear factor-activated T cells c1 (NFATc1) into the nucleus. However, fucoidan-mediated NFATc1 inactivation was greatly reversed by kenpaullone, a GSK3β inhibitor. In addition, using microcomputer tomography (micro-CT) scanning and bone histomorphometry, we found that fucoidan treatment markedly prevented LPS-induced bone erosion in mice. Collectively, we demonstrated that fucoidan was capable of inhibiting osteoclast differentiation and inflammatory bone loss, which may be modulated by regulation of Akt/GSK3β/PTEN/NFATc1 and Ca2+/calcineurin signaling cascades. These findings suggest that fucoidan may be a potential agent for the treatment of osteoclast-related bone diseases.

scholarly journals β2-Adrenergic Receptor Signaling in Osteoblasts Contributes to the Catabolic Effect of Glucocorticoids on Bone

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1412-1422 ◽  
Author(s):  
Yun Ma ◽  
Jeffry S. Nyman ◽  
Huan Tao ◽  
Heather H. Moss ◽  
Xiangli Yang ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Cells ◽  
Sympathetic Nerves ◽  
Bone Diseases ◽  
Autonomic Nerves ◽  
High Dose ◽  
Bone Homeostasis ◽  
Adrenergic Stimulation

Abstract The sympathetic nervous system is a physiological regulator of bone homeostasis. Autonomic nerves are indeed present in bone, bone cells express the β2-adrenergic receptors (β2AR), and pharmacological or genetic disruption of sympathetic outflow to bone induces bone gain in rodents. These recent findings implied that conditions that affect β2AR signaling in osteoblasts and/or sympathetic drive to bone may contribute to bone diseases. In this study, we show that dexamethasone stimulates the expression of the β2AR in differentiated primary calvarial osteoblasts, as measured by an increase in Adrβ2 mRNA and β2AR protein level after short-term dexamethasone treatment. Isoproterenol-induced cAMP accumulation and the expression of the β2AR target gene Rankl were also significantly increased after dexamethasone pretreatment, indicating that dexamethasone promotes the responsiveness of differentiated osteoblasts to adrenergic stimulation. These in vitro results led to the hypothesis that glucocorticoid-induced bone loss, provoked by increased endogenous or high-dose exogenous glucocorticoids given for the treatment of inflammatory diseases, might, at least in part, be mediated by increased sensitivity of bone-forming cells to the tonic inhibitory effect of sympathetic nerves on bone formation or their stimulatory effect on bone resorption. Supporting this hypothesis, both pharmacological and genetic β2AR blockade in mice significantly reduced the bone catabolic effect of high-dose prednisolone in vivo. This study emphasizes the importance of sympathetic nerves in the regulation of bone homeostasis and indicates that this neuroskeletal signaling axis can be modulated by hormones or drugs and contribute to enhance pathological bone loss.

scholarly journals Transcriptional Modulator Ifrd1 Regulates Osteoclast Differentiation through Enhancing the NF-κB/NFATc1 Pathway

2016 ◽  
Vol 36 (19) ◽  
pp. 2451-2463 ◽  
Author(s):  
Takashi Iezaki ◽  
Kazuya Fukasawa ◽  
Gyujin Park ◽  
Tetsuhiro Horie ◽  
Takashi Kanayama ◽  
...  
Keyword(s):  
Bone Loss ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Bone Diseases ◽  
Nuclear Factor ◽  
Activator Protein 1 ◽  
Bone Homeostasis ◽  
Activated T Cells

Bone homeostasis is maintained by the synergistic actions of bone-resorbing osteoclasts and bone-forming osteoblasts. Here, we show that the transcriptional coactivator/repressor interferon-related developmental regulator 1 (Ifrd1) is expressed in osteoclast lineages and represents a component of the machinery that regulates bone homeostasis. Ifrd1 expression was transcriptionally regulated in preosteoclasts by receptor activator of nuclear factor κB (NF-κB) ligand (RANKL) through activator protein 1. Global deletion of murineIfrd1increased bone formation and decreased bone resorption, leading to a higher bone mass. Deletion ofIfrd1in osteoclast precursors prevented RANKL-induced bone loss, although no bone loss was observed under normal physiological conditions. RANKL-dependent osteoclastogenesis was impairedin vitroinIfrd1-deleted bone marrow macrophages (BMMs).Ifrd1deficiency increased the acetylation of p65 at residues K122 and K123 via the inhibition of histone deacetylase-dependent deacetylation in BMMs. This repressed the NF-κB-dependent transcription of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), an essential regulator of osteoclastogenesis. These findings suggest that an Ifrd1/NF-κB/NFATc1 axis plays a pivotal role in bone remodelingin vivoand represents a therapeutic target for bone diseases.

scholarly journals LEFTY, a Member of the Transforming Growth Factor-β Superfamily, Inhibits Uterine Stromal Cell Differentiation: A Novel Autocrine Role

Endocrinology ◽  
2010 ◽  
Vol 151 (3) ◽  
pp. 1320-1330 ◽  
Author(s):  
Meiyi Tang ◽  
Devendra Naidu ◽  
Patrick Hearing ◽  
Stuart Handwerger ◽  
Siamak Tabibzadeh
Keyword(s):  
Medroxyprogesterone Acetate ◽  
Transforming Growth Factor ◽  
Marker Genes ◽  
Specific Marker ◽  
Normal Endometrium ◽  
Ovariectomized Mice ◽  
Decidual Cells ◽  
Pregnant Mice

LEFTY is expressed in normal endometrium in cells that decidualize. To understand the importance of this expression, we have studied the effect of LEFTY on decidualization in vitro and in vivo. Exposure of human uterine fibroblast (HuF) cells to recombinant LEFTY blocked the induction of the decidual differentiation-specific marker genes, IGFBP1 (IGF-binding protein 1) and PRL (prolactin) in response to medroxyprogesterone acetate, estradiol, and prostaglandin E2. The inhibitory effect was associated with decreased induction of the transcription factors ETS1 and FOXO1, both of which are essential for decidualization. Overexpression of LEFTY in decidualized HuF cells with an adenovirus that transduced LEFTY caused a marked decrease in IGFBP1 secretion, and withdrawal of medroxyprogesterone acetate from decidualized cells resulted in a decrease in IGFBP1 secretion and an increase in LEFTY expression. Moreover, overexpression of LEFTY in decidualized cells reprogrammed the cells to a less differentiated state and attenuated expression of decidual markers. Uterine decidualization was markedly attenuated and litter size was significantly reduced by retroviral transduction of LEFTY in the uterine horns of pregnant mice or by induction of LEFTY expression by doxycycline treatment in Tet-On conditional LEFTY transgenic pregnant mice. In addition, administration of the contraceptive agent drospirenone to ovariectomized mice induced a marked increase in LEFTY expression and inhibited decidualization. Taken together, these finding indicate that LEFTY acts as a molecular switch that modulates both the induction of decidual differentiation and the maintenance of a decidualized state. Because decidual cells express abundant amounts of LEFTY, the action of LEFTY on decidualization occurs by an autocrine mechanism.

scholarly journals POS0400 METABOLIC CHANGES INDUCED BY ANTI-MALONDIALDEHYDE/MALINDIALDEHYDE-ACETALDEHYDE ANTIBODIES PROMOTE OSTEOCLAST DEVELOPMENT

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 429-429
Author(s):  
K. Sakuraba ◽  
A. Krishnamurthy ◽  
A. Circiumaru ◽  
V. Joshua ◽  
H. Wähämaa ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Bone Loss ◽  
Molecular Mechanisms ◽  
Cellular Metabolism ◽  
Tca Cycle ◽  
Tartrate Resistant Acid Phosphatase ◽  
Fcγ Receptor ◽  
Research Support

Background:Malondialdehyde (MDA) is a highly reactive compound generated during lipid-peroxidation in conditions associated with oxidative stress. MDA can irreversibly modify proteins (e.g. lysine, arginine and histidine residues). In addition, acetaldehyde can further react with MDA adducts to form malondialdehyde-acetaldehyde (MAA) modification. Such protein modifications can lead to immunogenic neo-epitopes that are recognized by autoantibodies. In fact, anti-MDA/MAA IgG antibodies are significantly increased in the serum of patients with autoimmune diseases, such as rheumatoid arthritis (RA) (1). Interestingly, anti-MDA/MAA antibodies have been shown to promote osteoclast (OC) differentiation in vitro suggesting a potential role for these autoantibodies in bone damage associated with RA (1).Objectives:Little is known about the molecular mechanisms activated by autoantibodies in RA. Here, we elucidate the pathways specifically triggered by anti-MDA/MAA autoantibodies in developing osteoclasts.Methods:Recombinant human monoclonal anti-MDA/MAA antibodies, which were previously cloned from single synovial B cells of RA patients, were added to different OC assays. OCs were generated from monocyte-derived macrophages in the presence of the cytokines RANK-L and M-CSF. OC development was monitored by light microscopy following tartrate-resistant acid phosphatase staining and by erosion assays using calcium phosphate-coated plates. Bone morphometrics were studied in anti-MDA/MAA-injected mice using X-ray microscopy. Cellular metabolism was analyzed by mass spectrometry, Seahorse XF Analyzer and a colorimetric L-Lactate assay.Results:Anti-MDA/MAA antibodies induced a robust OC differentiation in vitro and bone loss in vivo. The anti-MDA/MAA antibodies acted on developing OCs by increasing glycolysis via an Fcγ receptor I-mediated pathway and the upregulation of the transcription factors HIF-1α, Myc and CHREBP. Such regulation of cellular metabolism was exclusively observed in the presence of the osteoclastogenic anti-MDA/MAA clones, whereas other RA-associated autoantibodies (anti-MDA/MAA or anti-citrullinated protein antibodies) had no effect on metabolism. The anti-MDA/MAA treatment induced a shift in the tricarboxylic acid (TCA) cycle activity in developing OCs, leading to the accumulation of citrate and aconitate.Conclusion:We described a novel type of autoantibody-induced pathway in RA, which might contribute to increased OC activation and a consequent bone loss. Anti-MDA/MAA antibodies promoted osteoclast development by increasing glycolysis and by modulating the TCA cycle through a signaling pathway that included Fcγ receptor I and a network of transcription factors acting on glycolysis. A TCA cycle bias towards citrate production suggests that the anti-MDA/MAA antibodies might stimulate OCs via increasing lipid biosynthesis in the cells.References:[1]Grönwall C. et al. J. Autoimmunity 84 (2017): 29-45.Acknowledgements:This Project has received funding from FOREUM, Foundation for Research in Rheumatology, from the European Research Council (ERC) grant agreement CoG 2017 - 7722209_PREVENT RA, the EU/EFPIA Innovative Medicine Initiative grant agreement 777357_RTCure, the Konung Gustaf V:s och Drottning Victorias Frimurarestiftelse and Knut and Alice Wallenberg Foundation.Disclosure of Interests:Koji Sakuraba: None declared, Akilan Krishnamurthy: None declared, Alexandra Circiumaru: None declared, Vijay Joshua: None declared, Heidi Wähämaa: None declared, Marianne Engström: None declared, Meng Sun: None declared, Xiaowei Zheng: None declared, Cheng Xu: None declared, Khaled Amara: None declared, Vivianne Malmström Grant/research support from: collaboration with Pfizer, unrelated to the abstract, Sergiu-Bogdan Catrina: None declared, Caroline Grönwall: None declared, Bence Réthi: None declared, Anca Catrina Grant/research support from: collaboration with BMS and Pfizer, unrelated to the present abstract

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