RESUMO
Fibroblasts, the most abundant structural cells, exert homeostatic functions but also drive disease pathogenesis. Single-cell technologies have illuminated the shared characteristics of pathogenic fibroblasts in multiple diseases including autoimmune arthritis, cancer and inflammatory colitis. However, the molecular mechanisms underlying the disease-associated fibroblast phenotypes remain largely unclear. Here, we identify ETS1 as the key transcription factor governing the pathological tissue-remodeling programs in fibroblasts. In arthritis, ETS1 drives polarization toward tissue-destructive fibroblasts by orchestrating hitherto undescribed regulatory elements of the osteoclast differentiation factor receptor activator of nuclear factor-κB ligand (RANKL) as well as matrix metalloproteinases. Fibroblast-specific ETS1 deletion resulted in ameliorated bone and cartilage damage under arthritic conditions without affecting the inflammation level. Cross-tissue fibroblast single-cell data analyses and genetic loss-of-function experiments lent support to the notion that ETS1 defines the perturbation-specific fibroblasts shared among various disease settings. These findings provide a mechanistic basis for pathogenic fibroblast polarization and have important therapeutic implications.
Assuntos
Artrite Reumatoide , Fibroblastos , Proteína Proto-Oncogênica c-ets-1 , Artrite Reumatoide/metabolismo , Artrite Reumatoide/patologia , Fibroblastos/metabolismo , Fibroblastos/patologia , Humanos , Metaloproteinases da Matriz/metabolismo , Proteína Proto-Oncogênica c-ets-1/genética , Proteína Proto-Oncogênica c-ets-1/metabolismo , Ligante RANK/genética , Fatores de Transcrição/metabolismoRESUMO
INTRODUCTION: The buccal bone resorption and the deformation of soft tissue contour are major problems of immediate implant treatment. This study aims to examine the changes of alveolar bone and soft tissue after immediate implant placement in different buccal gap distances. MATERIALS AND METHODS: Eight implants were placed randomly in the mandibular premolar sockets of 6 hybrid dogs with 1, 2, and 3 mm buccal gap distances. The dogs were killed after 2 or 4 months for morphometric and microcomputed tomography analyses. DISCUSSION: After 2 months, the 3-mm group had the highest buccal bone volume (BV), buccal bone/soft tissue thickness, and the lowest bone resorption. The wider the buccal gap, the more buccal bone and soft tissue were formed in this experimental setting. After 4 months, the buccal BV had decreased significantly in the 1-mm and the 2-mm groups, whereas the 3-mm group resisted to buccal bone resorption. This difference was more pronounced at the crest. CONCLUSION: The 3 mm is the optimal gap distance among the groups examined, which drastically influences the healing of bone and soft tissue surrounding the implants.
Assuntos
Perda do Osso Alveolar/etiologia , Implantes Dentários/efeitos adversos , Perda do Osso Alveolar/diagnóstico por imagem , Processo Alveolar/diagnóstico por imagem , Animais , Implantação Dentária Endóssea/efeitos adversos , Implantação Dentária Endóssea/métodos , Cães , Doenças da Gengiva/diagnóstico por imagem , Doenças da Gengiva/etiologia , Doenças Mandibulares/diagnóstico por imagem , Doenças Mandibulares/etiologia , Microtomografia por Raio-XRESUMO
BACKGROUND: Recent single-cell RNA sequencing (scRNA-seq) analysis revealed the functional heterogeneity and pathogenic cell subsets in immune cells, synovial fibroblasts and bone cells in rheumatoid arthritis (RA). JAK inhibitors which ameliorate joint inflammation and bone destruction in RA, suppress the activation of various types of cells in vitro. However, the key cellular and molecular mechanisms underlying the potent clinical effects of JAK inhibitors on RA remain to be determined. Our aim is to identify a therapeutic target for JAK inhibitors in vivo. METHODS: We performed scRNA-seq analysis of the synovium of collagen-induced arthritis (CIA) mice treated with or without a JAK inhibitor, followed by a computational analysis to identify the drug target cells and signaling pathways. We utilized integrated human RA scRNA-seq datasets and genetically modified mice administered with the JAK inhibitor for the confirmation of our findings. RESULTS: scRNA-seq analysis revealed that oncostatin M (OSM) driven macrophage-fibroblast interaction is highly activated under arthritic conditions. OSM derived from macrophages, acts on OSM receptor (OSMR)-expressing synovial fibroblasts, activating both inflammatory and tissue-destructive subsets. Inflammatory synovial fibroblasts stimulate macrophages, mainly through IL-6, to exacerbate inflammation. Tissue-destructive synovial fibroblasts promote osteoclast differentiation by producing RANKL to accelerate bone destruction. scRNA-seq analysis also revealed that OSM-signaling in synovial fibroblasts is the main signaling pathway targeted by JAK inhibitors in vivo. Mice specifically lacking OSMR in synovial fibroblasts (Osmr∆Fibro) displayed ameliorated inflammation and joint destruction in arthritis. The JAK inhibitor was effective on the arthritis of the control mice while it had no effect on the arthritis of Osmr∆Fibro mice. CONCLUSIONS: OSM functions as one of the key cytokines mediating pathogenic macrophage-fibroblast interaction. OSM-signaling in synovial fibroblasts is one of the main signaling pathways targeted by JAK inhibitors in vivo. The critical role of fibroblast-OSM signaling in autoimmune arthritis was shown by a combination of mice specifically deficient for OSMR in synovial fibroblasts and administration of the JAK inhibitor. Thus, the OSM-driven synovial macrophage-fibroblast circuit is proven to be a key driver of autoimmune arthritis, serving as a crucial drug target in vivo.
RESUMO
The ontogeny and fate of stem cells have been extensively investigated by lineage-tracing approaches. At distinct anatomical sites, bone tissue harbors multiple types of skeletal stem cells, which may independently supply osteogenic cells in a site-specific manner. Periosteal stem cells (PSCs) and growth plate resting zone stem cells (RZSCs) critically contribute to intramembranous and endochondral bone formation, respectively. However, it remains unclear whether there is functional crosstalk between these two types of skeletal stem cells. Here we show PSCs are not only required for intramembranous bone formation, but also for the growth plate maintenance and prolonged longitudinal bone growth. Mice deficient in PSCs display progressive defects in intramembranous and endochondral bone formation, the latter of which is caused by a deficiency in PSC-derived Indian hedgehog (Ihh). PSC-specific deletion of Ihh impairs the maintenance of the RZSCs, leading to a severe defect in endochondral bone formation in postnatal life. Thus, crosstalk between periosteal and growth plate stem cells is essential for post-developmental skeletal growth.
Assuntos
Condrócitos , Lâmina de Crescimento , Animais , Proteínas Hedgehog/genética , Camundongos , Osteogênese/genética , Células-TroncoRESUMO
In rheumatoid arthritis (RA), osteoclastic bone resorption causes structural joint damage as well as periarticular and systemic bone loss. Periarticular bone loss is one of the earliest indices of RA, often preceding the onset of clinical symptoms via largely unknown mechanisms. Excessive osteoclastogenesis induced by receptor activator of NF-κB ligand (RANKL) expressed by synovial fibroblasts causes joint erosion, whereas the role of RANKL expressed by lymphocytes in various types of bone damage has yet to be elucidated. In the bone marrow of arthritic mice, we found an increase in the number of RANKL-expressing plasma cells, which displayed an ability to induce osteoclastogenesis in vitro. Genetic ablation of RANKL in B-lineage cells resulted in amelioration of periarticular bone loss, but not of articular erosion or systemic bone loss, in autoimmune arthritis. We also show conclusive evidence for the critical contribution of synovial fibroblast RANKL to joint erosion in collagen-induced arthritis on the arthritogenic DBA/1J background. This study highlights the importance of plasma-cell RANKL in periarticular bone loss in arthritis and provides mechanistic insight into the early manifestation of bone lesion induced by autoimmunity.
Assuntos
Artrite Experimental/imunologia , Osteogênese/imunologia , Plasmócitos/imunologia , Animais , Artrite Experimental/patologia , Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Linfócitos B/imunologia , Linfócitos B/patologia , Células da Medula Óssea/imunologia , Células da Medula Óssea/patologia , Reabsorção Óssea/imunologia , Reabsorção Óssea/patologia , Feminino , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Transgênicos , Plasmócitos/patologia , Ligante RANK/deficiência , Ligante RANK/genética , Ligante RANK/imunologia , Membrana Sinovial/imunologia , Membrana Sinovial/patologiaRESUMO
Osteoclasts are the exclusive bone-resorbing cells, playing a central role in bone metabolism, as well as the bone damage that occurs under pathological conditions1,2. In postnatal life, haematopoietic stem-cell-derived precursors give rise to osteoclasts in response to stimulation with macrophage colony-stimulating factor and receptor activator of nuclear factor-κB ligand, both of which are produced by osteoclastogenesis-supporting cells such as osteoblasts and osteocytes1-3. However, the precise mechanisms underlying cell fate specification during osteoclast differentiation remain unclear. Here, we report the transcriptional profiling of 7,228 murine cells undergoing in vitro osteoclastogenesis, describing the stepwise events that take place during the osteoclast fate decision process. Based on our single-cell transcriptomic dataset, we find that osteoclast precursor cells transiently express CD11c, and deletion of receptor activator of nuclear factor-κB specifically in CD11c-expressing cells inhibited osteoclast formation in vivo and in vitro. Furthermore, we identify Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (Cited2) as the molecular switch triggering terminal differentiation of osteoclasts, and deletion of Cited2 in osteoclast precursors in vivo resulted in a failure to commit to osteoclast fate. Together, the results of this study provide a detailed molecular road map of the osteoclast differentiation process, refining and expanding our understanding of the molecular mechanisms underlying osteoclastogenesis.
Assuntos
Osteoclastos/fisiologia , Osteogênese/fisiologia , Transdução de Sinais/fisiologia , Animais , Células da Medula Óssea , Antígeno CD11c/metabolismo , Proliferação de Células , Bases de Dados Factuais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Osteogênese/genética , Gravidez , Proteínas Repressoras/metabolismo , Transdução de Sinais/genética , Transativadores/metabolismo , Fatores de Transcrição de p300-CBPRESUMO
The immune system evolved to efficiently eradicate invading bacteria and terminate inflammation through balancing inflammatory and regulatory T-cell responses. In autoimmune arthritis, pathogenic TH17 cells induce bone destruction and autoimmune inflammation. However, whether a beneficial function of T-cell-induced bone damage exists is unclear. Here, we show that bone-damaging T cells have a critical function in the eradication of bacteria in a mouse model of periodontitis, which is the most common infectious disease. Bacterial invasion leads to the generation of specialized TH17 cells that protect against bacteria by evoking mucosal immune responses as well as inducing bone damage, the latter of which also inhibits infection by removing the tooth. Thus, bone-damaging T cells, which may have developed to stop local infection by inducing tooth loss, function as a double-edged sword by protecting against pathogens while also inducing skeletal tissue degradation.