scholarly journals Adenosine A2A Receptor Mediates Inhibition of Synovitis and Osteoclastogenesis after Electroacupuncture in Rats with Collagen-Induced Arthritis

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Zhong-heng Du ◽  
Chun-wu Zhang ◽  
Wen-xia Xie ◽  
Yong Chen ◽  
Wen-jie Cong ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Peripheral Blood ◽  
Bone Erosion ◽  
Osteoclast Formation ◽  
Control Group ◽  
Tartrate Resistant Acid Phosphatase ◽  
Collagen Induced Arthritis ◽  
Ankle Joints ◽  
Trap Staining ◽  
Adenosine A2a

Background. This study was to investigate the role of adenosine A2A receptors (A2AR) in inhibiting the effect of electroacupuncture (EA) on osteoclastogenesis in collagen-induced arthritis (CIA). Methods. Wistar rats were divided into four groups: sham-control group, CIA-control group, CIA-EA group, and CIA-EA-SCH58261 (A2AR antagonist) group. We detected tumor necrosis factor-α (TNF-α), nuclear transcription factor-κB (NF-κB), receptor activator of NF-κB ligand (RANKL), protein kinase A (PKA), and extracellular regulatory protein kinase 1/2 (ERK1/2) in peripheral blood by ELISA. PKA, ERK1/2, and NF-κB in ankle joints were determined by western blotting. We evaluated the arthritis damage by histological examination and determined the number of osteoclasts by tartrate-resistant acid phosphatase (TRAP) staining. Results. EA treatment downregulated the expression of TNF-α, RANKL, PKA, ERK1/2, and NF-κB in peripheral blood but increased the levels of PKA and ERK1/2 in ankle joints. Importantly, EA treatment reduced bone erosion as evidenced by the histological findings and inhibited osteoclastogenesis as revealed by TRAP staining. All these effects of the EA treatment were reversed by combining EA treatment with the A2AR antagonist SCH58261. Conclusion. Our data suggest that EA treatment activated A2AR. The effects of the A2AR antagonist SCH58261 suggest that the inhibition of osteoclast formation, the inhibition of TNF-α, RANKL, and NF-κB expression, and the increase of ERK1/2 are all dependent on this EA-induced A2AR activation. It is therefore likely that these pathways with clearly defined roles in inflammation and bone erosion are at least partially involved in the mediation of the inhibition of synovitis and osteoclast formation induced by EA.

scholarly journals Systemic Resolvin E1 (RvE1) Treatment Does Not Ameliorate the Severity of Collagen-Induced Arthritis (CIA) in Mice: A Randomized, Prospective, and Controlled Proof of Concept Study

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Rafael Scaf de Molon ◽  
Rogier M. Thurlings ◽  
Birgitte Walgreen ◽  
Monique M. Helsen ◽  
Peter M. van der Kraan ◽  
...  
Keyword(s):  
Bone Erosion ◽  
Bone Destruction ◽  
Joint Inflammation ◽  
Therapeutic Strategies ◽  
Negative Control ◽  
Control Group ◽  
Human Rheumatoid Arthritis ◽  
Collagen Induced Arthritis ◽  
Ankle Joints ◽  
Synovial Explants

Specialized proresolving mediators (SPRM), which arise from n-3 long-chain polyunsaturated fatty acids (n-3FA), promote resolution of inflammation and may help to prevent progression of an acute inflammatory response into chronic inflammation in patients with arthritis. Thus, this study is aimed at determining whether systemic RvE1 treatment reduces arthritis onset and severity in murine collagen-induced arthritis (CIA) and spontaneous cytokine production by human rheumatoid arthritis (RA) synovial explants. 10-week-old DBA1/J male mice were subjected to CIA and treated systemically with 0.1 μg RvE1, 1 μg RvE1, 5 mg/kg anti-TNF (positive control group), PBS (negative control group), or with a combination of 1 μg of RvE1 plus 5 mg/kg anti-TNF using prophylactic or therapeutic strategies. After CIA immunization, mice were treated twice a week by RvE1 or anti-TNF for 10 days. Arthritis development was assessed by visual scoring of paw swelling and histology of ankle joints. Moreover, human RA synovial explants were incubated with 1 nM, 10 nM, or 100 nM of RvE1, and cytokine levels (IL-1β, IL-6, IL-8, IL-10, INF-γ, and TNF-α) were measured using Luminex bead array. CIA triggered significant inflammation in the synovial cavity, proteoglycan loss, and cartilage and bone destruction in the ankle joints of mice. Prophylactic and therapeutic RvE1 regimens did not ameliorate CIA incidence and severity. Anti-TNF treatment significantly abrogated signs of joint inflammation, bone erosion, and proteoglycan depletion, but additional RvE1 treatment did not further reduce the anti-TNF-mediated suppression of the disease. Treatment with different concentrations of RvE1 did not decrease the expression of proinflammatory cytokines in human RA synovial explants in the studied conditions. Collectively, our findings demonstrated that RvE1 treatment was not an effective approach to treat CIA in DBA1/J mice in both prophylactic and therapeutic strategies. Furthermore, no effects were noticed when human synovial explants were incubated with different concentrations of RvE1.

scholarly journals Similarities between IgG-bearing lymphocytes and hairy cells: cytologic and cytochemical studies

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 166-172 ◽  
Author(s):  
T Machii ◽  
T Kitani
Keyword(s):  
Peripheral Blood ◽  
Phase Contrast ◽  
Peripheral Blood Lymphocytes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Normal Peripheral Blood ◽  
Surface Immunoglobulin ◽  
Contrast Microscope ◽  
Trap Staining ◽  
Hairy Cells ◽  
Cytoplasmic Processes

Abstract Six patients with hairy cell leukemia (HCL) were studied for surface immunoglobulin ( sIg ). In all five sIg -positive cases, the heavy chain isotype was IgG. We performed cytologic and cytochemical studies of sIgG + lymphocytes in normal peripheral blood and compared them with hairy cells. Normal sIgM + lymphocytes were also examined. sIgG + and sIgM + lymphocytes made up 0.9% and 6.1% of normal peripheral blood lymphocytes, respectively. Under a phase-contrast microscope, 76% of sIgG + lymphocytes showed cytoplasmic processes similar to those found on hairy cells, whereas most sIgM + lymphocytes had smooth surfaces. Tartrate-resistant acid phosphatase (TRAP) staining revealed that TRAP- positive cells accounted for 65% of sIgG + lymphocytes and 19% of sIgM + lymphocytes. Some (8.3%) of the sIgM + lymphocytes expressed sIgG concomitantly. When sIgM +, sIgM +, sIgG + lymphocytes were excluded, the percentages of cells with surface processes and of TRAP-positive cells in the remaining sIgM +, sIgG - lymphocytes were 10% and 12%, respectively. A very small proportion (0.2%) of sIgM -, sIgG - lymphocytes had cytoplasmic processes. These results indicate that normal sIgG + lymphocytes are cytologically and cytochemically different from most sIgM + lymphocytes and that the phase-contrast microscopic appearances and TRAP activity of sIgG + lymphocytes are similar to those of HCL tumor cells.

Blockage of TRAF6 Signaling Inhibits Osteoclast Formation and Tumor Cell through Blocking the NF-kB and JNK Pathways in Multiple Myeloma.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2511-2511
Author(s):  
Haiming Chen ◽  
Mingjie Li ◽  
Jennifer Li ◽  
Richard A. Campbell ◽  
Cathy S. Wang ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Growth ◽  
Tumor Cell ◽  
Tumor Cells ◽  
Osteoclast Formation ◽  
Dominant Negative ◽  
Control Group ◽  
Affinity Column ◽  
Tartrate Resistant Acid Phosphatase ◽  
Control Vector

Abstract We have recently shown that silencing of tumor necrosis factor receptor-associated factor 6 (TRAF6) with a C-terminal siRNA inhibits proliferation and increases apoptosis of multiple myeloma (MM) tumor cells. In addition, TRAF6 ubiquitin ligase is also essential for receptor activator of nuclear factor kappa B ligand (RANKL) signaling and osteoclast differentiation. Based on TRAF6, CD40, and RANKL sequences and the TRAF6 interaction domain with CD40 or RANKL resides between residues 333 to 508, we cloned a sequence representing a 167 amino acid sequence from this domain in order to produce a TRAF6 dominant negative fragment (TRAF6dn) from the NIH gene bank (U78798) into the PCRII-TOPO vector. Subsequently, we re-cloned this fragment into an expression vector (pLenti6.2-hTRAF6dn). Expression of the TRAF6 dominant negative peptide was confirmed by Western blot analysis. We used human MM monocytes isolated by anti-CD14 micro-bead affinity column from MM patients’ peripheral blood (PB) or bone marrow (BM). In order to quantify osteoclast formation, the cells were fixed and stained for tartrate resistant acid phosphatase following seven days of culture. The BM and PB CD14+ cells were cultured on slide-culture dishes at a density of 2 × 105 cells per well. The cells infected with the pLenti6.2-hTRAF6dn or with the control vector, pLenti6.2/GW/EmGFP, were treated with 50ng/ml RANKL and 10ng/ml mCSF at the beginning of the culture period, and these factors were added again during a medium change after three days of incubation. We found that the TRAF6dn vector significantly inhibited osteoclast cell formation of CD14+ cells induced by RANKL and mCSF in a concentration dependent fashion compared with the control group. Furthermore, we examined c-Jun, a component of the transcription factor complex AP-1, which binds and activates transcription at TRE/AP-1 elements. The results showed that total endogenous c-Jun is reduced after TRAF6dn blocks TRAF6 signaling whereas cells infected with the control vector showed no changes in c-Jun. We further examined the effects of TRAF6dn on MM cell growth and apoptosis. Both tumor cells from fresh MM BM and the U266 and MM1s cell lines showed decreased cell proliferation and increased apoptosis in the presence of the TRAF6dn vector at 72 hours whereas the control vector had no effect on MM tumor cell growth or apoptosis. Furthermore, the TRAF6dn vector led to marked decreases in phospho-NF-kB protein levels compared to the control vector. Thus, we have demonstrated that inhibition of TRAF6 with a dominant negative construct both inhibits MM cell growth as well as osteoclast formation, and also reduces NF-kB activation and c-Jun levels which likely results in decreased activation of TRE/AP-1 elements. These studies suggest that the inhibition of TRAF6 may be an excellent therapeutic target for multiple myeloma since its inhibition results in suppression of tumor growth as well as osteoclast formation.

scholarly journals Similarities between IgG-bearing lymphocytes and hairy cells: cytologic and cytochemical studies

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 166-172 ◽  
Author(s):  
T Machii ◽  
T Kitani
Keyword(s):  
Peripheral Blood ◽  
Phase Contrast ◽  
Peripheral Blood Lymphocytes ◽  
Tartrate Resistant Acid Phosphatase ◽  
Normal Peripheral Blood ◽  
Surface Immunoglobulin ◽  
Contrast Microscope ◽  
Trap Staining ◽  
Hairy Cells ◽  
Cytoplasmic Processes

Six patients with hairy cell leukemia (HCL) were studied for surface immunoglobulin ( sIg ). In all five sIg -positive cases, the heavy chain isotype was IgG. We performed cytologic and cytochemical studies of sIgG + lymphocytes in normal peripheral blood and compared them with hairy cells. Normal sIgM + lymphocytes were also examined. sIgG + and sIgM + lymphocytes made up 0.9% and 6.1% of normal peripheral blood lymphocytes, respectively. Under a phase-contrast microscope, 76% of sIgG + lymphocytes showed cytoplasmic processes similar to those found on hairy cells, whereas most sIgM + lymphocytes had smooth surfaces. Tartrate-resistant acid phosphatase (TRAP) staining revealed that TRAP- positive cells accounted for 65% of sIgG + lymphocytes and 19% of sIgM + lymphocytes. Some (8.3%) of the sIgM + lymphocytes expressed sIgG concomitantly. When sIgM +, sIgM +, sIgG + lymphocytes were excluded, the percentages of cells with surface processes and of TRAP-positive cells in the remaining sIgM +, sIgG - lymphocytes were 10% and 12%, respectively. A very small proportion (0.2%) of sIgM -, sIgG - lymphocytes had cytoplasmic processes. These results indicate that normal sIgG + lymphocytes are cytologically and cytochemically different from most sIgM + lymphocytes and that the phase-contrast microscopic appearances and TRAP activity of sIgG + lymphocytes are similar to those of HCL tumor cells.

Plectranthus amboinicus Attenuates Inflammatory Bone Erosion in Mice with Collagen-induced Arthritis by Downregulation of RANKL-induced NFATc1 Expression

2011 ◽  
Vol 38 (9) ◽  
pp. 1844-1857 ◽  
Author(s):  
YU-CHIEH HSU ◽  
CHIA-PI CHENG ◽  
DEH-MING CHANG
Keyword(s):  
Animal Model ◽  
Rosmarinic Acid ◽  
Nuclear Translocation ◽  
Bone Erosion ◽  
Bone Destruction ◽  
Osteoclast Formation ◽  
Collagen Induced Arthritis ◽  
Activated T Cells ◽  
Plectranthus Amboinicus

Objective.Plectranthus amboinicus has been known to treat inflammatory diseases or swelling symptoms. We investigated whether P. amboinicus exhibited an inhibitory effect on osteoclastogenesis in vitro and inflammatory bone erosion in collagen-induced arthritis (CIA) mice, an animal model of rheumatoid arthritis. We attempted to identify the active component of P. amboinicus involved in regulation of osteoclastogenesis.Methods.We treated M-CSF- and RANKL-stimulated murine bone marrow-derived macrophages (BMM) and RANKL-induced RAW264.7 cells with different concentrations of P. amboinicus or rosmarinic acid, a phytopolyphenol purified from P. amboinicus, to monitor osteoclast formation by TRAP staining. The mechanism of the inhibition was studied by biochemical analysis such as RT-PCR and immunoblotting. CIA mice were administered gavages of P. amboinicus (375 mg/kg) or placebo. Then clinical, histological, and biochemical measures were assessed to determine the effects of P. amboinicus on synovial inflammation and bone erosion by H&E staining of the inflamed joints and ELISA.Results.Rosmarinic acid strongly inhibited RANKL-induced NF-κB activation and nuclear factor of activated T cells c1 (NFATc1) nuclear translocation in BMM, and also inhibited RANKL-induced formation of TRAP-positive multinucleated cells. A pit formation assay and the CIA animal model showed that P. amboinicus significantly inhibited the bone-resorbing activity of mature osteoclasts.Conclusion.We postulated that rosmarinic acid conferred the inhibitory activity on P. amboinicus for inhibition of osteoclastogenesis via downregulation of RANKL-induced NFATc1 expression. Our results indicated the possibility of P. amboinicus as a new remedy against inflammatory bone destruction.

scholarly journals Anti-inflammatory Activity of Formononetin in a Collagen-induced Arthritis Mouse Model ofRheumatoid Arthritis

2020 ◽  
Author(s):  
Ying Zhao ◽  
GUIWU QU ◽  
Wenxue Lu ◽  
Qing Lv ◽  
Wenxing Shi ◽  
...  
Keyword(s):  
Mouse Model ◽  
Bone Erosion ◽  
Bone Destruction ◽  
Treated Group ◽  
Control Group ◽  
High Dose ◽  
Collagen Induced Arthritis ◽  
Hind Limbs ◽  
Healthy Control ◽  
Anti Inflammatory

Abstract Background: Rheumatoid arthritis (RA) is a common autoimmune disease characterized by chronic inflammation of the joints, leading to bone erosion and joint dysfunction. Although there are options for the treatment of RA, safer and more effective drugs are still being sought. Formononetin (FMN) is an isoflavonoid compound found in various plants, such as Astragalus propinquus Schischkin and Spatholobus suberectus. It has anti-tumor, anti-bacterial, anti-lipid peroxidation, and estrogen-like activities，and is a noteworthy compound for screening of anti-RA drugs. Methods: To investigate the anti-inflammatory effects of FMN in a collagen-induced arthritis (CIA) mouse model, thirty-six C57BL/6 mice were randomly divided into 6 groups: a healthy control group and 5 CIA groups. Arthritis was induced the CIA groups using chicken collagen type II. The CIA groups were divided in a control group (RA), a tripterygium glycosides (10 mg/kg body weight) treated group (TG), a low-dose (50 mg/kg) FMN group (FMN-L), a middle-dose(100mg/kg) FMN group (FMN-M), and a high-dose (200 mg/kg) FMN group (FMN-H). The control mice and CIA mice in the RA group were treated with an equal volume of 5% carboxymethylcellulose sodium. Drugs were delivered three times a week for four weeks, and the bodyweight, food-uptake, and swelling of the paws were monitored during the treatment process. Inflammatory cytokines and other biochemical indexes in the serum and joint tissues were analyzed, along with the expression levels of NF-κB pathway-related proteins (IκBα, p65, p-p65, TIPE2, and PCNP) in the spleen. Histopathological examinations were processed for the hind limbs. Results: FMN-M dramatically reduced the arthritis index in the CIA mice, inhibited the inflammatory cell infiltration, and prevented damage to the synovium and cartilage. Mechanistic studies suggested that FMN might reduce inflammation by inhibiting IκB-α degradation and by regulating the expression and release of NF-κB p65. Conclusions: These data suggest that FMN might be an active therapeutic agent for RA by preventing bone destruction, regulating inflammatory mediators, and suppressing NF-κB signaling pathways.

scholarly journals miRNA-7062-5p Promoting Bone Resorption After Bone Metastasis of Colorectal Cancer Through Inhibiting GPR65

2021 ◽  
Vol 9 ◽  
Author(s):  
Liang Chen ◽  
Yu Wang ◽  
Xingchen Lu ◽  
Lili Zhang ◽  
Ziming Wang
Keyword(s):  
Colorectal Cancer ◽  
Bone Metastasis ◽  
Bone Resorption ◽  
Target Gene ◽  
Osteoclast Formation ◽  
Tartrate Resistant Acid Phosphatase ◽  
Differentially Expressed Mirnas ◽  
Metastasis Model ◽  
Trap Staining

Bone metastasis is positively associated with a poor prognosis in patients with colorectal cancer (CRC). CRC always leads to osteolytic change, which is regulated by aberrant activation of osteoclasts. MicroRNAs are remarkedly involved in metastasis of CRC; however, their role in bone metastasis of CRC is still unclear. The aim of this study is to find key microRNAs that are critical to bone resorption in bone metastasis of CRC. In this study, bone metastasis model was established through intratibially injecting CT-26 cells or MC-38 cells. Tartrate-resistant acid phosphatase (TRAP) staining was performed to explore the osteoclastogenesis of primary early osteoclast precursors (OCPs) after stimulation by CT-26 conditioned medium (CM). Then, microarray assay was performed to find differentially expressed miRNAs and mRNAs. The target gene of miRNA was confirmed by dual-luciferase analysis. The effect of miRNA, its target gene on osteoclastogenesis, and involved pathways were explored by Western blot, immunofluorescence analysis, and TRAP staining. Finally, the effect of miRNA on bone resorption in vivo was observed. miRNA-7062-5p was upregulated in early OCPs cultured in CT-26 CM or MC-38 CM. GPR65 was proven to be the target gene of miRNA-7062-5p. Overexpression of GPR65 can rescue the osteoclastogenesis caused by miRNA-7062-5p through activation of AMPK pathway. Local injection of miRNA-7062-5p inhibitors efficiently improved the bone resorption. Our study found the role of miRNA-7062-5p in regulating osteoclast formation, and our findings provided a potential therapeutic target in treatment of bone metastasis of CRC.

scholarly journals Attenuation of Collagen-Induced Arthritis in Rat by Nicotinic Alpha7 Receptor Partial Agonist GTS-21

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yiping Hu ◽  
Ruoxi Liu ◽  
Jinchao Li ◽  
Ye Yue ◽  
Wenxiang Cheng ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Partial Agonist ◽  
Control Group ◽  
Tartrate Resistant Acid Phosphatase ◽  
Collagen Induced Arthritis ◽  
Bone Degradation ◽  
Histological Score ◽  
Hematoxylin And Eosin ◽  
Alpha7 Receptor ◽  
Phosphate Buffered Saline

This research was performed to observe the effect of GTS-21 on Collagen Induced Arthritis (CIA). CIA model was used and after the onset of arthritis, the rats were divided into three groups based on their clinical symptoms score. Two groups were intraperitoneally (IP) injected daily with GTS-21 (1 mg/kg, 2.5 mg/kg) for a week, whereas phosphate buffered saline (PBS) was used for the control group. Cytokine titers, radiological, and histological examinations were performed at different time points after treatment with GTS-21. Compared with those of the control, the levels of TNF-α, IL-1, and IL-6 in the serum were significantly reduced after GTS-21 management. In addition, radiological results show that bone degradation was inhibited as well. Moreover, the hematoxylin and eosin (H&E) staining indicated that the histological score was significantly alleviated in the therapeutic group. Tartrate-resistant acid phosphatase (TRAP) stain-positive cells were also detected in the destruction of the articular cartilage, which was significantly reduced compared with the control group. This study provides the first evidence on the effect of GTS-21 as a potential treatment for RA.

The Effect of Da-Fang-Feng-Tang on Treatment of Type II Collagen-induced Arthritis in DBA/1 Mice

1999 ◽  
Vol 27 (02) ◽  
pp. 205-215 ◽  
Author(s):  
Lian Rong Wang ◽  
Naoki Ishiguro ◽  
Eiji Yamada ◽  
Yoshihiro Nishida ◽  
Koji Sato ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Histological Examination ◽  
Bone Erosion ◽  
Type Ii Collagen ◽  
Treated Group ◽  
Control Group ◽  
Human Rheumatoid Arthritis ◽  
Type Ii ◽  
Collagen Induced Arthritis ◽  
Igg Antibody

Da-Fang-Feng-Tang (DFFr), which is believed to be effective for treating human rheumatoid arthritis (RA), was given to DBA/1 mice at the onset of type II collagen-induced arthritis (CIA) to examine its effect. Granules of the crude DFFT extract were administered by gastric gavage at a dose of 1.6 g/kg/day for 12 weeks, starting the day CIA began. The levels of anticollagen IgG antibody were significantly decreased in the sera of the DFFT-treated group compared with the control group from weeks 2 to 7 after the onset of CIA. The severity of arthritis in the DFFT-treated group was markedly alleviated when compared with the control group. In addition, histological examination of the DFFT-treated group showed less cartilage and bone erosion. These results suggest that administration of DFFT suppressed the development of CIA in mice and support the belief that DFFT is effective in treating human RA.

scholarly journals 4-Acetylantroquinonol B Inhibits Osteoclastogenesis by Inhibiting the Autophagy Pathway in a Simulated Microgravity Model

2020 ◽  
Vol 21 (18) ◽  
pp. 6971
Author(s):  
Chia-Hsin Wu ◽  
Ching-Huei Ou ◽  
I-Chuan Yen ◽  
Shih-Yu Lee
Keyword(s):  
Bone Resorption ◽  
Transmembrane Protein ◽  
Osteoclast Differentiation ◽  
Osteoclast Formation ◽  
Tartrate Resistant Acid Phosphatase ◽  
Nuclear Factor ◽  
Actin Ring ◽  
Activated T Cells ◽  
Cycle Arrest ◽  
Trap Staining

Astronauts suffer from 1–2% bone loss per month during space missions. Targeting osteoclast differentiation has been regarded as a promising strategy to prevent osteoporosis in microgravity (μXg). 4-acetylantroquinonol B (4-AAQB), a ubiquinone from Antrodia cinnamomea, has shown anti-inflammatory and anti-hepatoma activities. However, the effect of 4-AAQB on μXg-induced osteoclastogenesis remains unclear. In this study, we aimed to explore the mechanistic impact of 4-AAQB on osteoclast formation under μXg conditions. The monocyte/macrophage-like cell line RAW264.7 was exposed to simulated μXg (Rotary Cell Culture System; Synthecon, Houston, TX, USA) for 24 h and then treated with 4-AAQB or alendronate (ALN) and osteoclast differentiation factor receptor activator of nuclear factor kappa-B ligand (RANKL). Osteoclastogenesis, bone resorption activity, and osteoclast differentiation-related signaling pathways were analyzed using tartrate-resistant acid phosphatase (TRAP) staining, actin ring fluorescent staining, bone resorption, and western blotting assays. Based on the results of TRAP staining, actin ring staining, and bone resorption assays, we found that 4-AAQB significantly inhibited μXg-induced osteoclast differentiation. The critical regulators of osteoclast differentiation, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), c-Fos, and dendritic cell-specific transmembrane protein (DC-STAMP), were consistently decreased. Meanwhile, osteoclast apoptosis and cell cycle arrest were also observed along with autophagy suppression. Interestingly, the autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) showed similar effects to 4-AAQB. In conclusion, we suggest that 4-AAQB may serve as a potential agent against μXg-induced osteoclast formation.

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