Intercellular Communication between Keratinocytes and Fibroblasts Induces Local Osteoclast Differentiation: a Mechanism Underlying Cholesteatoma-Induced Bone Destruction

Bone homeostasis is maintained by a balance in activity between bone-resorbing osteoclasts and bone-forming osteoblasts. Shifting the balance toward bone resorption causes osteolytic bone diseases such as rheumatoid arthritis and periodontitis. Osteoclast differentiation is regulated by receptor activator of nuclear factor κB ligand (RANKL), which, under some pathological conditions, is produced by T and B lymphocytes and synoviocytes. However, the mechanism underlying bone destruction in other diseases is little understood. Bone destruction caused by cholesteatoma, an epidermal cyst in the middle ear resulting from hyperproliferation of keratinizing squamous epithelium, can lead to lethal complications. In this study, we succeeded in generating a model for cholesteatoma, epidermal cyst-like tissue, which has the potential for inducing osteoclastogenesis in mice. Furthermore, anin vitrococulture system composed of keratinocytes, fibroblasts, and osteoclast precursors was used to demonstrate that keratinocytes stimulate osteoclast differentiation through the induction of RANKL in fibroblasts. Thus, this study demonstrates that intercellular communication between keratinocytes and fibroblasts is involved in the differentiation and function of osteoclasts, which may provide the molecular basis of a new therapeutic strategy for cholesteatoma-induced bone destruction.

Download Full-text

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

Molecular and Cellular Biology ◽

10.1128/mcb.01075-15 ◽

2016 ◽

Vol 36 (19) ◽

pp. 2451-2463 ◽

Cited By ~ 13

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.

Download Full-text

Plasma membrane calcium ATPase regulates bone mass by fine-tuning osteoclast differentiation and survival

The Journal of Cell Biology ◽

10.1083/jcb.201204067 ◽

2012 ◽

Vol 199 (7) ◽

pp. 1145-1158 ◽

Cited By ~ 42

Author(s):

Hyung Joon Kim ◽

Vikram Prasad ◽

Seok-Won Hyung ◽

Zang Hee Lee ◽

Sang-Won Lee ◽

...

Keyword(s):

Plasma Membrane ◽

Bone Mass ◽

Osteoclast Differentiation ◽

Premenopausal Women ◽

Fine Tuning ◽

Bone Homeostasis ◽

Regulatory Loop ◽

And Function

The precise regulation of Ca2+ dynamics is crucial for proper differentiation and function of osteoclasts. Here we show the involvement of plasma membrane Ca2+ ATPase (PMCA) isoforms 1 and 4 in osteoclastogenesis. In immature/undifferentiated cells, PMCAs inhibited receptor activator of NF-κB ligand–induced Ca2+ oscillations and osteoclast differentiation in vitro. Interestingly, nuclear factor of activated T cell c1 (NFATc1) directly stimulated PMCA transcription, whereas the PMCA-mediated Ca2+ efflux prevented NFATc1 activation, forming a negative regulatory loop. PMCA4 also had an anti-osteoclastogenic effect by reducing NO, which facilitates preosteoclast fusion. In addition to their role in immature cells, increased expression of PMCAs in mature osteoclasts prevented osteoclast apoptosis both in vitro and in vivo. Mice heterozygous for PMCA1 or null for PMCA4 showed an osteopenic phenotype with more osteoclasts on bone surface. Furthermore, PMCA4 expression levels correlated with peak bone mass in premenopausal women. Thus, our results suggest that PMCAs play important roles for the regulation of bone homeostasis in both mice and humans by modulating Ca2+ signaling in osteoclasts.

Download Full-text

Padina pavonica Extract Promotes In Vitro Differentiation and Functionality of Human Primary Osteoblasts

Marine Drugs ◽

10.3390/md17080473 ◽

2019 ◽

Vol 17 (8) ◽

pp. 473

Author(s):

Mariagiulia Minetti ◽

Giulia Bernardini ◽

Manuele Biazzo ◽

Gilles Gutierrez ◽

Michela Geminiani ◽

...

Keyword(s):

Healthy Lifestyle ◽

Fold Increase ◽

Nuclear Factor Κb ◽

Collagen Type I ◽

Bone Diseases ◽

Type I ◽

Bone Homeostasis ◽

Safe Product ◽

Differentiation Stage

Marine algae have gained much importance in the development of nutraceutical products due to their high content of bioactive compounds. In this work, we investigated the activity of Padina pavonica with the aim to demonstrate the pro-osteogenic ability of its extract on human primary osteoblast (HOb). Our data indicated that the acetonic extract of P. pavonica (EPP) is a safe product as it did not show any effect on osteoblast viability. At the same time, EPP showed to possess a beneficial effect on HOb functionality, triggering their differentiation and mineralization abilities. In particular EPP enhanced the expression of the earlier differentiation stage markers: a 5.4-fold increase in collagen type I alpha 1 chain (COL1A1), and a 2.3-fold increase in alkaline phosphatase (ALPL), as well as those involved in the late differentiation stage: a 3.7-fold increase in osteocalcin (BGLAP) expression and a 2.8-fold in osteoprotegerin (TNFRSF11B). These findings were corroborated by the enhancement in ALPL enzymatic activity (1.7-fold increase) and by the reduction of receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) ratio (0.6-fold decrease). Moreover, EPP demonstrated the capacity to enhance the bone nodules formation by 3.2-fold in 4 weeks treated HOb. Therefore, EPP showed a significant capability of promoting osteoblast phenotype. Given its positive effect on bone homeostasis, EPP could be used as a useful nutraceutical product that, in addition to a healthy lifestyle and diet, can be able to contrast and prevent bone diseases, especially those connected with ageing, such as osteoporosis (OP).

Download Full-text

ELMO1 Regulates RANKL-Stimulated Differentiation and Bone Resorption of Osteoclasts

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.702916 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xinyue Liang ◽

Yafei Hou ◽

Lijuan Han ◽

Shuxiang Yu ◽

Yunyun Zhang ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Bone Resorption ◽

Bone Erosion ◽

Osteoclast Differentiation ◽

Small Gtpases ◽

Bone Diseases ◽

Bone Homeostasis ◽

Nucleotide Exchange

Bone homeostasis is a metabolic balance between the new bone formation by osteoblasts and old bone resorption by osteoclasts. Excessive osteoclastic bone resorption results in low bone mass, which is the major cause of bone diseases such as rheumatoid arthritis. Small GTPases Rac1 is a key regulator of osteoclast differentiation, but its exact mechanism is not fully understood. ELMO and DOCK proteins form complexes that function as guanine nucleotide exchange factors for Rac activation. Here, we report that ELMO1 plays an important role in differentiation and bone resorption of osteoclasts. Osteoclast precursors derived from bone marrow monocytes (BMMs) of Elmo1–/– mice display defective adhesion and migration during differentiation. The cells also have a reduced activation of Rac1, p38, JNK, and AKT in response to RANKL stimulation. Importantly, we show that bone erosion is alleviated in Elmo1–/– mice in a rheumatoid arthritis mouse model. Taken together, our results suggest that ELMO1, as a regulator of Rac1, regulates osteoclast differentiation and bone resorption both in vitro and in vivo.

Download Full-text

HDAC2 regulates FoxO1 during RANKL-induced osteoclastogenesis

AJP Cell Physiology ◽

10.1152/ajpcell.00351.2015 ◽

2016 ◽

Vol 310 (10) ◽

pp. C780-C787 ◽

Cited By ~ 17

Author(s):

Ce Dou ◽

Nan Li ◽

Ning Ding ◽

Chuan Liu ◽

Xiaochao Yang ◽

...

Keyword(s):

Bone Resorption ◽

Osteoclast Differentiation ◽

Nuclear Factor Κb ◽

Negative Regulator ◽

Bone Homeostasis ◽

Akt Activation ◽

Histone Deacetylase 2 ◽

Forkhead Box ◽

Receptor Activator ◽

And Function

The bone-resorbing osteoclast (OC) is essential for bone homeostasis, yet deregulation of OCs contributes to diseases such as osteoporosis, osteopetrosis, and rheumatoid arthritis. Here we show that histone deacetylase 2 (HDAC2) is a key positive regulator during receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption. Bone marrow macrophages (BMMs) showed increased HDAC2 expression during osteoclastogenesis. HDAC2 overexpression enhanced, whereas HDAC2 deletion suppressed osteoclastogenesis and bone resorption using lentivirus infection. Mechanistically, upon RANKL activation, HDAC2 activated Akt; Akt directly phosphorylates and abrogates Forkhead box protein O1 (FoxO1), which is a negative regulator during osteoclastogenesis through reducing reactive oxygen species. HDAC2 deletion in BMMs resulted in decreased Akt activation and increased FoxO1 activity during osteoclastogenesis. In conclusion, HDAC2 activates Akt thus suppresses FoxO1 transcription results in enhanced osteoclastogenesis. Our data imply the potential value of HDAC2 as a new target in regulating osteoclast differentiation and function.

Download Full-text

TNF Receptor:Fc Fusion Protein Downregulates RANKL/OPG Ratio by Inhibiting CXCL16/CXCR6 in Active Ankylosing Spondylitis

Current Pharmaceutical Biotechnology ◽

10.2174/1389201021666200302104418 ◽

2020 ◽

Vol 21 ◽

Author(s):

Peiyi Zhang ◽

Shufen Zhou ◽

Zhe Chen ◽

Ye Tian ◽

Qianqian Wang ◽

...

Keyword(s):

Ankylosing Spondylitis ◽

Fusion Protein ◽

Osteoclast Differentiation ◽

Bone Destruction ◽

Serum Levels ◽

Nuclear Factor Κb ◽

Mrna Levels ◽

Before And After ◽

Positive Linear Correlation

Background: Clinical studies indicate that recombinant tumor necrosis factor receptor:Fc fusion protein (rhTNFR:Fc) quickly alleviates symptoms and physical signs of active ankylosing spondylitis (AS), improving the manifestation of spinal inflammation on radiological imaging. However, the regulatory mechanism of rhTNFR:Fc in the chemokine pathway is unclear. Thus we study the mechanism of phlogogenic activity of CXCL16/CXCR6 in AS and the related mechanism of rhTNFR:Fc treatment. Methods: Thirty-two cases of active AS were treated with rhTNFR:Fc for 3 consecutive months. Clinical response was evaluated at baseline and after treatment. CXCL16/CXCR6 expression as well as receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG), essential molecules for osteoclast differentiation, were studied in AS before and after treatment. Further, proliferation of lymphocytes and the RANKL level stimulated by recombinant human CXCL16 (rhCXCL16) were measured in vitro. Results: Thirty cases responded to rhTNFR:Fc treatment. The RANKL level, RANKL/OPG ratio, CXCLl6 level in serum, and CXCLl6 and CXCR6 mRNA levels in active AS were higher than those in controls and treated patients (P<0.001). rhCXCL16 treatment increased lymphocyte proliferation and RANKL level in active AS (P<0.001), but not in controls or treated patients (P>0.05). A positive linear correlation was noted between CXCL16 serum levels and RANKL/OPG ratio and between CXCL16 levels and polymerase chain reaction results (P<0.001). Conclusions: Our findings suggest that rhTNFR:Fc suppresses inflammation and bone destruction of AS by reducing the RANKL/OPG ratio through inhibition of the CXCL16/CXCR6 pathway.

Download Full-text

Hajdu Cheney Mouse Mutants Exhibit Osteopenia, Increased Osteoclastogenesis, and Bone Resorption

Journal of Biological Chemistry ◽

10.1074/jbc.m115.685453 ◽

2015 ◽

Vol 291 (4) ◽

pp. 1538-1551 ◽

Cited By ~ 44

Author(s):

Ernesto Canalis ◽

Lauren Schilling ◽

Siu-Pok Yee ◽

Sun-Kyeong Lee ◽

Stefano Zanotti

Keyword(s):

Bone Resorption ◽

Cortical Bone ◽

Cell Fate ◽

Cancellous Bone ◽

Skeletal Development ◽

Amino Acid Level ◽

Osteoclast Differentiation ◽

Nuclear Factor Κb ◽

And Function

Notch receptors are determinants of cell fate and function and play a central role in skeletal development and bone remodeling. Hajdu Cheney syndrome, a disease characterized by osteoporosis and fractures, is associated with NOTCH2 mutations resulting in a truncated stable protein and gain-of-function. We created a mouse model reproducing the Hajdu Cheney syndrome by introducing a 6955C→T mutation in the Notch2 locus leading to a Q2319X change at the amino acid level. Notch2Q2319X heterozygous mutants were smaller and had shorter femurs than controls; and at 1 month of age they exhibited cancellous and cortical bone osteopenia. As the mice matured, cancellous bone volume was restored partially in male but not female mice, whereas cortical osteopenia persisted in both sexes. Cancellous bone histomorphometry revealed an increased number of osteoclasts and bone resorption, without a decrease in osteoblast number or bone formation. Osteoblast differentiation and function were not affected in Notch2Q2319X cells. The pre-osteoclast cell pool, osteoclast differentiation, and bone resorption in response to receptor activator of nuclear factor κB ligand in vitro were increased in Notch2Q2319X mutants. These effects were suppressed by the γ-secretase inhibitor LY450139. In conclusion, Notch2Q2319X mice exhibit cancellous and cortical bone osteopenia, enhanced osteoclastogenesis, and increased bone resorption.

Download Full-text

Nasturtium officinale Extract Suppresses Osteoclastogenesis in RAW 264 Cells by Inhibiting IκB-Kinase β

Natural Product Communications ◽

10.1177/1934578x211020643 ◽

2021 ◽

Vol 16 (6) ◽

pp. 1934578X2110206

Author(s):

Yukino Tsunekage ◽

Masatoshi Takeiri ◽

Yuri Yoshioka ◽

Shinichi Matsumura ◽

Yoshihide Kimura ◽

...

Keyword(s):

Osteoclast Differentiation ◽

Specific Inhibitor ◽

Nuclear Factor Κb ◽

Bone Diseases ◽

Tartrate Resistant Acid Phosphatase ◽

Nuclear Factor ◽

Activated T Cells ◽

Nasturtium Officinale ◽

Iκb Kinase

Osteoclasts are large, multinucleated, bone-absorbing cells and play a crucial role in osteolytic bone diseases such as osteopetrosis and rheumatoid arthritis. Therefore, controlling osteoclast differentiation and activation has been considered a promising strategy to prevent and treat osteolytic diseases. In this study, we demonstrate, using the mouse monocyte-derived macrophage-like cell line RAW 264, that extract from Nasturtium officinale or watercress, an herb of European origin, suppresses receptor activator of nuclear factor-κB ligand-induced osteoclast differentiation in vitro . N. officinale extract decreased the emergence of tartrate-resistant acid phosphatase-positive differentiated multinuclear cells and inhibited their bone-absorbing activity. The extract decreased expression of genes associated with osteoclast differentiation and function. Induction of nuclear factor of activated T cells c1 (NFATc1), the master transcriptional regulator of osteoclastogenesis, was blunted by N. officinale extract. Activation of nuclear factor-κB and mitogen-activated protein kinases pathways, both of which are necessary for NFATc1 induction and osteoclast differentiation, was also suppressed by the extract. Among upstream kinases, activity of IκB-kinase β (IKKβ), but not that of TGFβ-activated kinase 1, was inhibited by N. officinale extract in vitro. Pharmacological inhibition of IKKβ by a specific inhibitor PS1145 in RAW 264 cells mostly recaptured the inhibitory action of N. officinale extract. These findings provide a novel pharmacological action of N. officinale and its potential usefulness for the prevention of osteoporosis.

Download Full-text

PKC-δ deficiency in B cells displays osteopenia accompanied with upregulation of RANKL expression and osteoclast–osteoblast uncoupling

Cell Death and Disease ◽

10.1038/s41419-020-02947-3 ◽

2020 ◽

Vol 11 (9) ◽

Author(s):

Shangfu Li ◽

Qiuli Liu ◽

Depeng Wu ◽

Tianwei He ◽

Jinbo Yuan ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Bone Structure ◽

Bone Cells ◽

Osteoclast Differentiation ◽

Bone Homeostasis ◽

Osteoblast Proliferation ◽

And Function

Abstract PKC-δ is an important molecule for B-cell proliferation and tolerance. B cells have long been recognized to play a part in osteoimmunology and pathological bone loss. However, the role of B cells with PKC-δ deficiency in bone homeostasis and the underlying mechanisms are unknown. We generated mice with PKC-δ deletion selectively in B cells by crossing PKC-δ-loxP mice with CD19-Cre mice. We studied their bone phenotype using micro-CT and histology. Next, immune organs were obtained and analyzed. Western blotting was used to determine the RANKL/OPG ratio in vitro in B-cell cultures, ELISA assay and immunohistochemistry were used to analyze in vivo RANKL/OPG balance in serum and bone sections respectively. Finally, we utilized osteoclastogenesis to study osteoclast function via hydroxyapatite resorption assay, and isolated primary calvaria osteoblasts to investigate osteoblast proliferation and differentiation. We also investigated osteoclast and osteoblast biology in co-culture with B-cell supernatants. We found that mice with PKC-δ deficiency in B cells displayed an osteopenia phenotype in the trabecular and cortical compartment of long bones. In addition, PKC-δ deletion resulted in changes of trabecular bone structure in association with activation of osteoclast bone resorption and decrease in osteoblast parameters. As expected, inactivation of PKC-δ in B cells resulted in changes in spleen B-cell number, function, and distribution. Consistently, the RANKL/OPG ratio was elevated remarkably in B-cell culture, in the serum and in bone specimens after loss of PKC-δ in B cells. Finally, in vitro analysis revealed that PKC-δ ablation suppressed osteoclast differentiation and function but co-culture with B-cell supernatant reversed the suppression effect, as well as impaired osteoblast proliferation and function, indicative of osteoclast–osteoblast uncoupling. In conclusion, PKC-δ plays an important role in the interplay between B cells in the immune system and bone cells in the pathogenesis of bone lytic diseases.

Download Full-text

Regulation of Bone Cell Differentiation and Activation by Microbe-Associated Molecular Patterns

International Journal of Molecular Sciences ◽

10.3390/ijms22115805 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5805

Author(s):

Yeongkag Kwon ◽

Chaeyeon Park ◽

Jueun Lee ◽

Donghyun Park ◽

Sungho Jeong ◽

...

Keyword(s):

Pathogenic Bacteria ◽

Periodontal Diseases ◽

Bone Destruction ◽

Bone Cell ◽

Bone Diseases ◽

Bone Homeostasis ◽

Bone Cell Differentiation ◽

Molecular Patterns

Gut microbiota has emerged as an important regulator of bone homeostasis. In particular, the modulation of innate immunity and bone homeostasis is mediated through the interaction between microbe-associated molecular patterns (MAMPs) and the host pattern recognition receptors including Toll-like receptors and nucleotide-binding oligomerization domains. Pathogenic bacteria such as Porphyromonas gingivalis and Staphylococcus aureus tend to induce bone destruction and cause various inflammatory bone diseases including periodontal diseases, osteomyelitis, and septic arthritis. On the other hand, probiotic bacteria such as Lactobacillus and Bifidobacterium species can prevent bone loss. In addition, bacterial metabolites and various secretory molecules such as short chain fatty acids and cyclic nucleotides can also affect bone homeostasis. This review focuses on the regulation of osteoclast and osteoblast by MAMPs including cell wall components and secretory microbial molecules under in vitro and in vivo conditions. MAMPs could be used as potential molecular targets for treating bone-related diseases such as osteoporosis and periodontal diseases.

Download Full-text