Toll-like receptor 7 regulates osteoclastogenesis in rheumatoid arthritis

2019 ◽  
Vol 166 (3) ◽  
pp. 259-270 ◽  
Author(s):  
Kyoung-Woon Kim ◽  
Bo-Mi Kim ◽  
Ji-Yeon Won ◽  
Kyung-Ann Lee ◽  
Hae-Rim Kim ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Osteoclast Differentiation ◽  
Bone Destruction ◽  
Synovial Fibroblasts ◽  
Enzyme Linked Immunosorbent Assay ◽  
Signal Molecules ◽  
Signal Pathways ◽  
Tartrate Resistant Acid Phosphatase ◽  
Toll Like Receptor ◽  
Multinucleated Cells

Abstract This study aimed to determine the regulatory role of toll-like receptor 7 (TLR7) in receptor activator of nuclear factor kappa-B ligand (RANKL) production and osteoclast differentiation in rheumatoid arthritis (RA). In confocal microscopy, the co-expression of TLR7, CD55 and RANKL was determined in RA synovial fibroblasts. After RA synovial fibroblasts were treated with imiquimod, the RANKL gene expression and protein production were determined by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Osteoclastogenesis from peripheral blood CD14+ monocytes which were cultured with imiquimod was assessed by determining the numbers of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. The signal pathways mediating the TLR7-induced RANKL expression and osteoclastogenesis were analysed after inhibition of intracellular signal molecules and their phosphorylation. Imiquimod stimulated the expression of TLR7 and RANKL and production of RANKL in RA synovial fibroblasts, increasing the phosphorylation of TRAF6, IRF7, mitogen-activated protein kinases (MAPK), c-Jun and NFATc1. When CD14+ monocytes were cultured with imiquimod or co-cultured with imiquimod-pre-treated RA synovial fibroblasts, they were differentiated into TRAP+ multinucleated osteoclasts in the absence of RANKL. TLR7 activation-induced osteoclastogenesis in RA through direct induction of osteoclast differentiation from its precursors and up-regulation of RANKL production in RA synovial fibroblasts. Thus, the blockage of TLR7 pathway could be a promising therapeutic strategy for preventing bone destruction in RA.

scholarly journals Promotion of osteoclastogenesis by IL-26 in rheumatoid arthritis

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Kyung-Ann Lee ◽  
Kyoung-Woon Kim ◽  
Bo-Mi Kim ◽  
Ji-Yeon Won ◽  
Hong Ki Min ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Peripheral Blood ◽  
Osteoclast Differentiation ◽  
Joint Damage ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
Dependent Manner ◽  
Receptor Subunit ◽  
Blood Monocytes ◽  
Peripheral Blood Monocytes

Abstract Background The inflammatory cascade in the rheumatoid arthritis (RA) synovium is modulated by a variety of cytokine and chemokine networks; however, the roles of IL-26, in RA pathogenesis, are poorly defined. Here, we investigated the functional role of interleukin-26 (IL)-26 in osteoclastogenesis in RA. Methods We analyzed levels of IL-20 receptor subunit A (IL-20RA), CD55, and receptor activator of nuclear factor kappaB (NF-κB) ligand (RANKL) in RA fibroblast-like synoviocytes (FLSs) using confocal microscopy. Recombinant human IL-26-induced RANKL expression in RA-FLSs was examined using real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Human peripheral blood monocytes were cultured with macrophage colony-stimulating factor (M-CSF) and IL-26, after which osteoclastogenesis was evaluated by counting the number of tartrate-resistant acid phosphatase-positive multinucleated cells. Additionally, osteoclastogenesis was evaluated by monocytes co-cultured with IL-26-prestimulated FLSs. Results The expression of IL-20RA in RA-FLSs was higher than that in osteoarthritis-FLSs. Additionally, in IL-26-pretreated RA-FLSs, the expression of IL-20RA (but not IL-10 receptor subunit B) and RANKL increased in a dose-dependent manner, with IL-26-induced RANKL expression reduced by IL-20RA knockdown. Moreover, IL-26-induced RANKL expression was significantly downregulated by inhibition of signal transducer and activator of transcription 1, mitogen-activated protein kinase, and NF-κB signaling. Furthermore, IL-26 promoted osteoclast differentiation from peripheral blood monocytes in the presence of low dose of RANKL, with IL-26 exerting an additive effect. Furthermore, co-culture of IL-26-pretreated RA-FLSs with peripheral blood monocytes also increased osteoclast differentiation in the absence of addition of RANKL. Conclusions IL-26 regulated osteoclastogenesis in RA through increased RANKL expression in FLSs and direct stimulation of osteoclast differentiation. These results suggest the IL-26/IL-20RA/RANKL axis as a potential therapeutic target for addressing RA-related joint damage.

scholarly journals Interleukin (IL)-25 suppresses IL-22 induced osteoclastogenesis in rheumatoid arthritis via STAT3 and p38 MAPK/IκBα pathway

2020 ◽  
Author(s):  
Hong Ki Min ◽  
Ji-Yeon Won ◽  
Bo-Mi Kim ◽  
Kyung-Ann Lee ◽  
Seoung-Joon Lee ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Synovial Fluid ◽  
P38 Mapk ◽  
Human Peripheral Blood ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
Blood Monocytes ◽  
Rankl Expression

Abstract Background The present study aimed to evaluate the suppressive role of interleukin (IL)-25 in IL-22-induced osteoclastogenesis and receptor activator of nuclear factor κB ligand (RANKL) expression in rheumatoid arthritis (RA). Methods Serum from patients with RA and osteoarthritis (OA), and healthy controls, as well as synovial fluid from patients with RA and OA were collected, and the levels of IL-22 and IL-25 were measured. RA and OA synovial tissues were stained against IL-25. Fibroblast-like synoviocytes (FLSs) of patients with RA were cultured with IL-22, in the presence or absence of IL-25, and RANKL expression was measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA). Human peripheral blood monocytes were cultured under IL-22/RANKL + M-CSF, with or without IL-25, and tartrate-resistant acid phosphatase (TRAP)-positive cells and osteoclast-related markers were investigated to determine osteoclastogenesis. Results Serum and synovial IL-25 levels in RA were up-regulated compared to those in OA and healthy control, and elevated expression of IL-25 in RA synovial tissue was re-confirmed. IL-25 and IL-22 levels showed significant correlation in serum and synovial fluid. Pre-treatment of FLS with IL-25 reduced IL-22-induced RANKL expression at the RNA level. The suppressive effects of IL-25 were confirmed to occur through the STAT3 and p38 MAPK/IκBα pathways. IL-25 reduced osteoclast differentiation and suppressed the expression of osteoclast-related markers. Conclusion In the current study, we demonstrated the regulatory effect of IL-25 on IL-22-induced osteoclastogenesis. Therapeutic approach involving augmentation of IL-25 regulatory response may serve as a novel treatment option for RA, especially by suppressing osteoclastogenesis.

scholarly journals OP0241 IL9 MODULATION OF OSTEOCLASTS DIFFERENTIATION AND IMPACTS ON BONE METABOLISM

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 152.1-152
Author(s):  
M. Saad ◽  
S. Rauber ◽  
G. Schett ◽  
A. Ramming
Keyword(s):  
Rheumatoid Arthritis ◽  
Bone Metabolism ◽  
Mouse Models ◽  
Intracellular Signaling ◽  
Bone Matrix ◽  
Osteoclast Differentiation ◽  
Bone Destruction ◽  
Microcomputed Tomography ◽  
Tartrate Resistant Acid Phosphatase ◽  
Resolution Of Inflammation

Background:Osteoclasts are multinucleated cells originating from the monocytes/macrophage lineage and require receptor activator of NF-κB ligand (RANK-L) and macrophage-colony-stimulating factor (M-CSF) for their development. They play a major role in bone remodeling by degrading the calcified bone matrix. They are considered as one of the culprits in bone destruction in many inflammatory diseases e.g. rheumatoid arthritis and osteoporosis. In previous work by our group, it was observed that IL-9 mediated the resolution of inflammation in rheumatoid arthritis and hence protected against bone degradation in animal models. Despite this protection was particularly associated to the resolution of inflammation, our data also supported the hypothesis of a direct signalling of IL-9 to osteoclasts.Objectives:The aim of this study was to investigate the modulating effect of IL-9 on osteoclasts and on the bone metabolism.Methods:Osteoclasts differentiation was studied in the mouse models of antigen induced arthritis (AIA) and KBxN serum induced arthritis (SIA) in the presence and absence of IL-9 by histomorphometric analysis and microcomputed tomography scans (µCT). Osteoclasts were generated from bone marrow derived monocytes of BALB/c mice with M-CSF, RANKL and IL-9, which were added in varying concentrations to induce osteoclast differentiation. Tartrate-resistant acid phosphatase (TRAP) staining was performed to follow the differentiation steps from monocytes into multinucleated osteoclasts and to determine the effects of IL-9 on osteoclastogenesis. Additionally, we performed RNA-seq and seahorse analysis to detect IL-9 dependent, differentially expressed genes and metabolites. Intracellular signaling as induced by IL9R activation was followed by western blot analysis.Results:IL-9 KO mice showed higher numbers of osteoclasts as compared to wild-type mice in the mouse models of AIA and SIA. Microcomputed tomography showed pronounced loss of the trabecular network and bone volume as signs of inflammation-induced osteopenia in Il9−/− mice. We found that osteoclasts express high levels of IL-9R. Next, monocytes were differentiated into osteoclasts in the presence of different concentrations of recombinant IL-9. Cells cultured in the presence of IL-9 showed significantly impaired differentiation into osteoclasts. We observed phosphorylation of STAT3 and STAT5 in cultured osteoclasts in dependency of IL-9. Furthermore, the presence of IL-9 during osteoclast differentiation impacted the gene expression levels of characteristic osteoclast related genes such as NFATc1, Cathepsin K and TRAP. Furthermore, IL-9 showed a major impact on mitochondrial respiration rate and glycolysis as assessed by Seahorse assays.Conclusion:IL-9 exerted direct effects on osteoclast differentiation and modulated the expression of several genes that are related to osteoclast differentiation and function.Disclosure of Interests:mina saad: None declared, Simon Rauber: None declared, Georg Schett Speakers bureau: AbbVie, BMS, Celgene, Janssen, Eli Lilly, Novartis, Roche and UCB, Andreas Ramming Grant/research support from: Pfizer, Novartis, Consultant of: Boehringer Ingelheim, Novartis, Gilead, Pfizer, Speakers bureau: Boehringer Ingelheim, Roche, Janssen

scholarly journals Interleukin (IL)-25 suppresses IL-22 induced osteoclastogenesis in rheumatoid arthritis via STAT3 and p38 MAPK/IκBα pathway

2019 ◽  
Author(s):  
Hong Ki Min ◽  
Ji-Yeon Won ◽  
Bo-Mi Kim ◽  
Kyung-Ann Lee ◽  
Seoung-Joon Lee ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Synovial Fluid ◽  
P38 Mapk ◽  
Human Peripheral Blood ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
Blood Monocytes ◽  
Rankl Expression

Abstract Background The present study aimed to evaluate the suppressive role of interleukin (IL)-25 in IL-22-induced osteoclastogenesis and receptor activator of nuclear factor κB ligand (RANKL) expression in rheumatoid arthritis (RA).Methods Serum from patients with RA and osteoarthritis (OA), and healthy controls, as well as synovial fluid from patients with RA and OA were collected, and the levels of IL-22 and IL-25 were measured. RA and OA synovial tissues were stained against IL-25. Fibroblast-like synoviocytes (FLSs) of patients with RA were cultured with IL-22, in the presence or absence of IL-25, and RANKL expression was measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA). Human peripheral blood monocytes were cultured under IL-22/RANKL, with or without IL-25, and tartrate-resistant acid phosphatase (TRAP)-positive cells and osteoclast-related markers were investigated to determine osteoclastogenesis.Results Serum and synovial IL-25 levels in RA were up-regulated compared to those in OA and healthy control, and elevated expression of IL-25 in RA synovial tissue was re-confirmed. IL-25 and IL-22 levels showed significant correlation in serum and synovial fluid. Pre-treatment of FLS with IL-25 reduced IL-22-induced RANKL expression at the RNA level. The suppressive effects of IL-25 were confirmed to occur through the STAT3 and p38 MAPK/IκBα pathways. IL-25 reduced osteoclast differentiation and suppressed the expression of osteoclast-related markers.Conclusion In the current study, we demonstrated the regulatory effect of IL-25 on IL-22-induced osteoclastogenesis. Therapeutic approach involving augmentation of IL-25 regulatory response may serve as a novel treatment option for RA, especially by suppressing osteoclastogenesis.

scholarly journals Interleukin (IL)-25 suppresses IL-22-induced osteoclastogenesis in rheumatoid arthritis via STAT3 and p38 MAPK/IκBα pathway

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Hong Ki Min ◽  
Ji-Yeon Won ◽  
Bo-Mi Kim ◽  
Kyung-Ann Lee ◽  
Seoung-Joon Lee ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Synovial Fluid ◽  
P38 Mapk ◽  
Human Peripheral Blood ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
Blood Monocytes ◽  
Rankl Expression

Abstract Background The present study aimed to evaluate the suppressive role of interleukin (IL)-25 in IL-22-induced osteoclastogenesis and receptor activator of nuclear factor κB ligand (RANKL) expression in rheumatoid arthritis (RA). Methods Serum from patients with RA and osteoarthritis (OA), and healthy controls, and synovial fluid from patients with RA and OA were collected, and the levels of IL-22 and IL-25 were measured. RA and OA synovial tissues were stained against IL-25. Fibroblast-like synoviocytes (FLSs) of patients with RA were cultured with IL-22, in the presence or absence of IL-25, and RANKL expression was measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA). Human peripheral blood monocytes were cultured under IL-22/RANKL + M-CSF, with or without IL-25, and tartrate-resistant acid phosphatase (TRAP)-positive cells and osteoclast-related markers were investigated to determine osteoclastogenesis. Results Serum and synovial IL-25 levels in RA were upregulated compared to those in OA and healthy control, and elevated expression of IL-25 in RA synovial tissue was re-confirmed. IL-25 and IL-22 levels showed significant correlation in serum and synovial fluid. Pre-treatment of FLS with IL-25 reduced IL-22-induced RANKL expression at the RNA level. The suppressive effects of IL-25 were confirmed to occur through the STAT3 and p38 MAPK/IκBα pathways. IL-25 reduced osteoclast differentiation and suppressed the expression of osteoclast-related markers. Conclusion In the current study, we demonstrated the regulatory effect of IL-25 on IL-22-induced osteoclastogenesis. Therapeutic approach involving augmentation of IL-25 regulatory response may serve as a novel treatment option for RA, especially by suppressing osteoclastogenesis.

scholarly journals Regulation of Th17 Cytokine-Induced Osteoclastogenesis via SKI306X in Rheumatoid Arthritis

2019 ◽  
Vol 8 (7) ◽  
pp. 1012
Author(s):  
Hae-Rim Kim ◽  
Kyoung-Woon Kim ◽  
Bo-Mi Kim ◽  
Ji-Yeon Won ◽  
Hong-Ki Min ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Real Time ◽  
Real Time Pcr ◽  
Joint Destruction ◽  
Osteoclast Differentiation ◽  
Synovial Fibroblasts ◽  
Tartrate Resistant Acid Phosphatase ◽  
Rankl Expression ◽  
Th17 Cytokines ◽  
Th17 Cytokine

This study aimed to investigate the regulatory effect of SKI305X, a mixed extract of three herbs, in T helper (Th)17 cytokine-induced inflammation and joint destruction in rheumatoid arthritis (RA). Synovial fibroblasts were isolated from RA patients and cultured with Th17 cytokines including interleukin (IL)-17, IL-21, and IL-22 and SKI306X, and tumor necrosis factor (TNF)-, IL-1, and receptor activator of nuclear factor kappa-Β ligand (RANKL) expression and production were investigated using real-time PCR and ELISA of culture media. After peripheral blood (PB) cluster of differentiation (CD)14+ monocytes were cultured in media supplemented with Th17 cytokines and SKI306X, tartrate-resistant acid phosphatase positive (TRAP+) multinucleated giant cells (mature osteoclasts) were enumerated and gene expression associated with osteoclast maturation was assessed via real-time PCR analysis. After PB monocytes were co-cultured with IL-17-stimulated RA synovial fibroblasts in the presence of SKI306, osteoclast differentiation was assessed. When RA synovial fibroblasts were cultured with IL-17, IL-21, and IL-22, TNF-, IL-1, and RANKL expression and production were increased; however, SKI306X reduced cytokine expression and production. When PB monocytes were cultured in media supplemented with Th17 cytokines, osteoclast differentiation was stimulated; however, SKI306X decreased osteoclast differentiation and osteoclast maker expression. When PB monocytes were co-cultured with IL-17-stimulated RA synovial fibroblasts, osteoclast differentiation was increased; however, SKI306X decreased osteoclast differentiation and osteoclast maker expression. SKI306X reduced Th17 cytokine-induced TNF-, IL-1, and RANKL expression and osteoclast differentiation, providing novel insights into adjuvant therapy for regulating inflammation and joint destruction in RA.

The Impact of Proinflammatory Cytokynes of Rheumatoid Polyarthritis on the Generalized Loss of Bone Mass

2018 ◽  
Vol 69 (9) ◽  
pp. 2541-2545
Author(s):  
Raluca Barzoi ◽  
Elena Rezus ◽  
Codruta Badescu ◽  
Razan Al Namat ◽  
Manuela Ciocoiu
Keyword(s):  
Rheumatoid Arthritis ◽  
Immune Cells ◽  
Osteoclast Differentiation ◽  
Bone Destruction ◽  
Nuclear Factor ◽  
Receptor Activator ◽  
Level Function ◽  
Rheumatoid Polyarthritis ◽  
The Impact ◽  
Nuclear Factor Kb

There is a bidirectional interaction between most immune cells and osteoblasts, osteoclasts and their precursor cells. The receptor activator of nuclear factor-kB ligand (RANKL)/RANK/osteoprotegerin (OPG) system plays an essential role in the formation of osteoblasts, but it also has implications in osteoclast biology and implicitly on the diseases characterized by bone loss. Proinflammatory cytokines existing at synovial level function as direct or indirect stimulators of osteoclast differentiation, but also of its survival or activity, although some cytokines may also play an antiosteocastogenic role. The fate of bone destruction is determined by the balance between osteoclastogenic and antiosteoclastogenic mediators. Our study has shown that the early initiation of the therapy with anti-TNF and anti-IL6 biological agents, in patients with rheumatoid arthritis, inhibits bone destruction, regardless of the anti-inflammatory activity in patients with rheumatoid arthritis.

scholarly journals Kalkitoxin Reduces Osteoclast Formation and Resorption and Protects against Inflammatory Bone Loss

2021 ◽  
Vol 22 (5) ◽  
pp. 2303
Author(s):  
Liang Li ◽  
Ming Yang ◽  
Saroj Kumar Shrestha ◽  
Hyoungsu Kim ◽  
William H. Gerwick ◽  
...  
Keyword(s):  
Bone Loss ◽  
Transmembrane Protein ◽  
Osteoclast Differentiation ◽  
Mapk Signaling ◽  
Osteoclast Formation ◽  
Bone Diseases ◽  
Tartrate Resistant Acid Phosphatase ◽  
Nuclear Factor ◽  
Mineral Density ◽  
Multinucleated Cells

Osteoclasts, bone-specified multinucleated cells produced by monocyte/macrophage, are involved in numerous bone destructive diseases such as arthritis, osteoporosis, and inflammation-induced bone loss. The osteoclast differentiation mechanism suggests a possible strategy to treat bone diseases. In this regard, we recently examined the in vivo impact of kalkitoxin (KT), a marine product obtained from the marine cyanobacterium Moorena producens (previously Lyngbya majuscula), on the macrophage colony-stimulating factor (M-CSF) and on the receptor activator of nuclear factor κB ligand (RANKL)-stimulated in vitro osteoclastogenesis and inflammation-mediated bone loss. We have now examined the molecular mechanism of KT in greater detail. KT decreased RANKL-induced bone marrow-derived macrophages (BMMs) tartrate-resistant acid phosphatase (TRAP)-multinucleated cells at a late stage. Likewise, KT suppressed RANKL-induced pit area and actin ring formation in BMM cells. Additionally, KT inhibited several RANKL-induced genes such as cathepsin K, matrix metalloproteinase (MMP-9), TRAP, and dendritic cell-specific transmembrane protein (DC-STAMP). In line with these results, RANKL stimulated both genes and protein expression of c-Fos and nuclear factor of activated T cells (NFATc1), and this was also suppressed by KT. Moreover, KT markedly decreased RANKL-induced p-ERK1/2 and p-JNK pathways at different time points. As a result, KT prevented inflammatory bone loss in mice, such as bone mineral density (BMD) and osteoclast differentiation markers. These experiments demonstrated that KT markedly inhibited osteoclast formation and inflammatory bone loss through NFATc1 and mitogen-activated protein kinase (MAPK) signaling pathways. Therefore, KT may have potential as a treatment for destructive bone diseases.

scholarly journals Role of Synovial Exosomes in Osteoclast Differentiation in Inflammatory Arthritis

Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 120
Author(s):  
Ji Eun Song ◽  
Ji Soo Kim ◽  
Ji Hye Shin ◽  
Ki Won Moon ◽  
Jin Kyun Park ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Inflammatory Arthritis ◽  
Mononuclear Cells ◽  
Osteoclast Differentiation ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
Healthy Donors ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony

This study aimed to investigate the characteristics of exosomes isolated from synovial fluid and their role in osteoclast differentiation in different types of inflammatory arthritis. Exosomes isolated from synovial fluid of rheumatoid arthritis (RA), ankylosing spondylitis (AS), gout, and osteoarthritis (OA) patients were co-incubated with CD14+ mononuclear cells from healthy donors without macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL). Osteoclast differentiation was evaluated via tartrate-resistant acid phosphatase (TRAP) staining and activity and F-actin ring formation. RANKL expression on synovial exosomes was assessed using flow cytometry and an enzyme-linked immunosorbent assay (ELISA). Synovial exosomes were the lowest in OA patients; these induced osteoclastogenesis in the absence of M-CSF and RANKL. Osteoclastogenesis was significantly higher with more exosomes in RA (p = 0.030) than in OA patients, but not in AS or gout patients. On treating macrophages with a specified number of synovial exosomes from RA/AS patients, exosomes induced greater osteoclastogenesis in RA than in AS patients. Synovial exosomal RANKL levels were significantly higher in RA (p = 0.035) than in AS patients. Synovial exosome numbers vary with the type of inflammatory arthritis. Synovial exosomes from RA patients may bear the disease-specific “synovial signature of osteoclastogenesis.”

scholarly journals CD14+CD16− monocytes are the main precursors of osteoclasts in rheumatoid arthritis via expressing Tyro3TK

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Jimeng Xue ◽  
Liling Xu ◽  
Huaqun Zhu ◽  
Mingxin Bai ◽  
Xin Li ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Tyrosine Kinase ◽  
Osteoclast Differentiation ◽  
Tender Joint Count ◽  
Tartrate Resistant Acid Phosphatase ◽  
Dependent Manner ◽  
Monocyte Subsets ◽  
Tender Joint ◽  
Critical Signal

Abstract Background Monocytes as precursors of osteoclasts in rheumatoid arthritis (RA) are well demonstrated, while monocyte subsets in osteoclast formation are still controversial. Tyro3 tyrosine kinase (Tyro3TK) is a member of the receptor tyrosine kinase family involved in immune homeostasis, the role of which in osteoclast differentiation was reported recently. This study aimed to compare the osteoclastic capacity of CD14+CD16+ and CD14+CD16− monocytes in RA and determine the potential involvement of Tyro3TK in their osteoclastogenesis. Methods Osteoclasts were induced from CD14+CD16+ and CD14+CD16− monocyte subsets isolated from healthy control (HC) and RA patients in vitro and evaluated by tartrate-resistant acid phosphatase (TRAP) staining. Then, the expression of Tyro3TK on CD14+CD16+ and CD14+CD16− monocyte subsets in the peripheral blood of RA, osteoarthritis (OA) patients, and HC were evaluated by flow cytometry and qPCR, and their correlation with RA patient clinical and immunological features was analyzed. The role of Tyro3TK in CD14+CD16− monocyte-mediated osteoclastogenesis was further investigated by osteoclast differentiation assay with Tyro3TK blockade. Results The results revealed that CD14+CD16− monocytes were the primary source of osteoclasts. Compared with HC and OA patients, the expression of Tyro3TK on CD14+CD16− monocytes in RA patients was significantly upregulated and positively correlated with the disease manifestations, such as IgM level, tender joint count, and the disease activity score. Moreover, anti-Tyro3TK antibody could inhibit Gas6-mediated osteoclast differentiation from CD14+CD16− monocytes in a dose-dependent manner. Conclusions These findings indicate that elevated Tyro3TK on CD14+CD16− monocytes serves as a critical signal for osteoclast differentiation in RA.

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