RESUMO
The niche is typically considered as a pre-established structure sustaining stem cells. Therefore, the regulation of its formation remains largely unexplored. Whether distinct molecular mechanisms control the establishment versus maintenance of a stem cell niche is unknown. To address this, we compared perinatal and adult bone marrow mesenchymal stromal cells (MSCs), a key component of the hematopoietic stem cell (HSC) niche. MSCs exhibited enrichment in genes mediating m6A mRNA methylation at the perinatal stage and downregulated the expression of Mettl3, the m6A methyltransferase, shortly after birth. Deletion of Mettl3 from developing MSCs but not osteoblasts led to excessive osteogenic differentiation and a severe HSC niche formation defect, which was significantly rescued by deletion of Klf2, an m6A target. In contrast, deletion of Mettl3 from MSCs postnatally did not affect HSC niche. Stem cell niche generation and maintenance thus depend on divergent molecular mechanisms, which may be exploited for regenerative medicine.
Assuntos
Células-Tronco Hematopoéticas , Células-Tronco Mesenquimais , Metiltransferases , Camundongos Endogâmicos C57BL , Nicho de Células-Tronco , Animais , Camundongos , Adenosina/metabolismo , Adenosina/análogos & derivados , Diferenciação Celular , Epigênese Genética , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/citologia , Fatores de Transcrição Kruppel-Like , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/citologia , Metiltransferases/metabolismo , Metiltransferases/genética , Osteoblastos/metabolismo , Osteoblastos/citologia , Osteogênese , RNA Mensageiro/metabolismo , RNA Mensageiro/genética , Transcriptoma/genética , HumanosRESUMO
Non-hematopoietic cells are essential contributors to hematopoiesis. However, heterogeneity and spatial organization of these cells in human bone marrow remain largely uncharacterized. We used single-cell RNA sequencing (scRNA-seq) to profile 29,325 non-hematopoietic cells and discovered nine transcriptionally distinct subtypes. We simultaneously profiled 53,417 hematopoietic cells and predicted their interactions with non-hematopoietic subsets. We employed co-detection by indexing (CODEX) to spatially profile over 1.2 million cells. We integrated scRNA-seq and CODEX data to link predicted cellular signaling with spatial proximity. Our analysis revealed a hyperoxygenated arterio-endosteal neighborhood for early myelopoiesis, and an adipocytic localization for early hematopoietic stem and progenitor cells (HSPCs). We used our CODEX atlas to annotate new images and uncovered mesenchymal stromal cell (MSC) expansion and spatial neighborhoods co-enriched for leukemic blasts and MSCs in acute myeloid leukemia (AML) patient samples. This spatially resolved, multiomic atlas of human bone marrow provides a reference for investigation of cellular interactions that drive hematopoiesis.
Assuntos
Medula Óssea , Células-Tronco Hematopoéticas , Células-Tronco Mesenquimais , Proteômica , Análise de Célula Única , Transcriptoma , Humanos , Análise de Célula Única/métodos , Medula Óssea/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/citologia , Proteômica/métodos , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Hematopoese , Nicho de Células-Tronco , Células da Medula Óssea/metabolismo , Células da Medula Óssea/citologiaRESUMO
Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.
Assuntos
Hematopoiese Clonal , DNA (Citosina-5-)-Metiltransferases , DNA Metiltransferase 3A , Periodontite , Animais , DNA (Citosina-5-)-Metiltransferases/metabolismo , DNA (Citosina-5-)-Metiltransferases/genética , Camundongos , Hematopoiese Clonal/genética , Humanos , Periodontite/genética , Periodontite/patologia , Mutação , Masculino , Feminino , Inflamação/genética , Inflamação/patologia , Osteoclastos/metabolismo , Camundongos Endogâmicos C57BL , Adulto , Interleucina-17/metabolismo , Interleucina-17/genética , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Hematopoese/genética , Osteogênese/genética , Células-Tronco Hematopoéticas/metabolismo , Reabsorção Óssea/genética , Reabsorção Óssea/patologia , Pessoa de Meia-IdadeRESUMO
Hematopoietic stem cells (HSCs) and downstream progenitors have long been studied based on phenotype, cell purification, proliferation, and transplantation into myeloablated recipients. These experiments, complemented by data on expression profiles, mouse mutants, and humans with hematopoietic defects, are the foundation for the current hematopoietic differentiation tree. However, there are fundamental gaps in our knowledge of the quantitative and qualitative operation of the HSC/progenitor system under physiological and pathological conditions in vivo. The hallmarks of HSCs, self-renewal and multipotency, are observed in in vitro assays and cell transplantation experiments; however, the extent to which these features occur naturally in HSCs and progenitors remains uncertain. We focus here on work that strives to address these unresolved questions, with emphasis on fate mapping and modeling of the hematopoietic flow from stem cells toward myeloid and lymphoid lineages during development and adult life.
Assuntos
Envelhecimento/imunologia , Diferenciação Celular , Hematopoese , Células-Tronco Hematopoéticas/fisiologia , Células Progenitoras Linfoides/fisiologia , Animais , Linhagem da Célula , Autorrenovação Celular , Humanos , Camundongos , Modelos Teóricos , TranscriptomaRESUMO
Blood and lymphatic vessels form a versatile transport network and provide inductive signals to regulate tissue-specific functions. Blood vessels in bone regulate osteogenesis and hematopoiesis, but current dogma suggests that bone lacks lymphatic vessels. Here, by combining high-resolution light-sheet imaging and cell-specific mouse genetics, we demonstrate presence of lymphatic vessels in mouse and human bones. We find that lymphatic vessels in bone expand during genotoxic stress. VEGF-C/VEGFR-3 signaling and genotoxic stress-induced IL6 drive lymphangiogenesis in bones. During lymphangiogenesis, secretion of CXCL12 from proliferating lymphatic endothelial cells is critical for hematopoietic and bone regeneration. Moreover, lymphangiocrine CXCL12 triggers expansion of mature Myh11+ CXCR4+ pericytes, which differentiate into bone cells and contribute to bone and hematopoietic regeneration. In aged animals, such expansion of lymphatic vessels and Myh11-positive cells in response to genotoxic stress is impaired. These data suggest lymphangiogenesis as a therapeutic avenue to stimulate hematopoietic and bone regeneration.
Assuntos
Regeneração Óssea , Vasos Linfáticos , Idoso , Animais , Humanos , Camundongos , Células Endoteliais , LinfangiogêneseRESUMO
Dopaminergic projections regulate various brain functions and are implicated in many neuropsychiatric disorders. There are two anatomically and functionally distinct dopaminergic projections connecting the midbrain to striatum: nigrostriatal, which controls movement, and mesolimbic, which regulates motivation. However, how these discrete dopaminergic synaptic connections are established is unknown. Through an unbiased search, we identify that two groups of antagonistic TGF-ß family members, bone morphogenetic protein (BMP)6/BMP2 and transforming growth factor (TGF)-ß2, regulate dopaminergic synapse development of nigrostriatal and mesolimbic neurons, respectively. Projection-preferential expression of their receptors contributes to specific synapse development. Downstream, Smad1 and Smad2 are specifically activated and required for dopaminergic synapse development and function in nigrostriatal vs. mesolimbic projections. Remarkably, Smad1 mutant mice show motor defects, whereas Smad2 mutant mice show lack of motivation. These results uncover the molecular logic underlying the proper establishment of functionally segregated dopaminergic synapses and may provide strategies to treat relevant, projection-specific disease symptoms by targeting specific BMPs/TGF-ß and/or Smads.
Assuntos
Corpo Estriado , Dopamina , Animais , Camundongos , Mesencéfalo , Motivação , Movimento , SinapsesRESUMO
Multiple sclerosis (MS) is a T cell-mediated autoimmune disease of the central nervous system (CNS). Bone marrow hematopoietic stem and progenitor cells (HSPCs) rapidly sense immune activation, yet their potential interplay with autoreactive T cells in MS is unknown. Here, we report that bone marrow HSPCs are skewed toward myeloid lineage concomitant with the clonal expansion of T cells in MS patients. Lineage tracing in experimental autoimmune encephalomyelitis, a mouse model of MS, reveals remarkable bone marrow myelopoiesis with an augmented output of neutrophils and Ly6Chigh monocytes that invade the CNS. We found that myelin-reactive T cells preferentially migrate into the bone marrow compartment in a CXCR4-dependent manner. This aberrant bone marrow myelopoiesis involves the CCL5-CCR5 axis and augments CNS inflammation and demyelination. Our study suggests that targeting the bone marrow niche presents an avenue to treat MS and other autoimmune disorders.
Assuntos
Encefalomielite Autoimune Experimental , Esclerose Múltipla , Animais , Medula Óssea , Hematopoese , Humanos , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Bone marrow (BM)-mediated trained innate immunity (TII) is a state of heightened immune responsiveness of hematopoietic stem and progenitor cells (HSPC) and their myeloid progeny. We show here that maladaptive BM-mediated TII underlies inflammatory comorbidities, as exemplified by the periodontitis-arthritis axis. Experimental-periodontitis-related systemic inflammation in mice induced epigenetic rewiring of HSPC and led to sustained enhancement of production of myeloid cells with increased inflammatory preparedness. The periodontitis-induced trained phenotype was transmissible by BM transplantation to naive recipients, which exhibited increased inflammatory responsiveness and disease severity when subjected to inflammatory arthritis. IL-1 signaling in HSPC was essential for their maladaptive training by periodontitis. Therefore, maladaptive innate immune training of myelopoiesis underlies inflammatory comorbidities and may be pharmacologically targeted to treat them via a holistic approach.
Assuntos
Artrite , Periodontite , Animais , Células-Tronco Hematopoéticas , Imunidade Inata , Camundongos , MielopoeseRESUMO
Metastasis has been considered as the terminal step of tumor progression. However, recent genomic studies suggest that many metastases are initiated by further spread of other metastases. Nevertheless, the corresponding pre-clinical models are lacking, and underlying mechanisms are elusive. Using several approaches, including parabiosis and an evolving barcode system, we demonstrated that the bone microenvironment facilitates breast and prostate cancer cells to further metastasize and establish multi-organ secondary metastases. We uncovered that this metastasis-promoting effect is driven by epigenetic reprogramming that confers stem cell-like properties on cancer cells disseminated from bone lesions. Furthermore, we discovered that enhanced EZH2 activity mediates the increased stemness and metastasis capacity. The same findings also apply to single cell-derived populations, indicating mechanisms distinct from clonal selection. Taken together, our work revealed an unappreciated role of the bone microenvironment in metastasis evolution and elucidated an epigenomic reprogramming process driving terminal-stage, multi-organ metastases.
Assuntos
Neoplasias Ósseas/secundário , Neoplasias da Mama/patologia , Metástase Neoplásica , Neoplasias da Próstata/patologia , Microambiente Tumoral , Animais , Apoptose , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias Ósseas/genética , Neoplasias Ósseas/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Proliferação de Células , Progressão da Doença , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Gastrointestinal enterochromaffin cells regulate bone and gut homeostasis via serotonin (5-hydroxytryptamine [5-HT]) production. A recent report suggested that gut microbes regulate 5-HT levels; however, the precise underlying molecular mechanisms are unexplored. Here, we reveal that the cation channel Piezo1 in the gut acts as a sensor of single-stranded RNA (ssRNA) governing 5-HT production. Intestinal epithelium-specific deletion of mouse Piezo1 profoundly disturbed gut peristalsis, impeded experimental colitis, and suppressed serum 5-HT levels. Because of systemic 5-HT deficiency, conditional knockout of Piezo1 increased bone formation. Notably, fecal ssRNA was identified as a natural Piezo1 ligand, and ssRNA-stimulated 5-HT synthesis from the gut was evoked in a MyD88/TRIF-independent manner. Colonic infusion of RNase A suppressed gut motility and increased bone mass. These findings suggest gut ssRNA as a master determinant of systemic 5-HT levels, indicating the ssRNA-Piezo1 axis as a potential prophylactic target for treatment of bone and gut disorders.
Assuntos
Osso e Ossos/metabolismo , Colo/metabolismo , Motilidade Gastrointestinal/genética , Canais Iônicos/metabolismo , RNA/metabolismo , Serotonina/biossíntese , Serotonina/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Osso e Ossos/citologia , Cálcio/metabolismo , Colite/genética , Colite/metabolismo , Colite/prevenção & controle , Colo/fisiologia , Fezes/química , Feminino , Motilidade Gastrointestinal/fisiologia , Células HEK293 , Humanos , Imuno-Histoquímica , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Canais Iônicos/genética , Ligantes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microbiota/efeitos dos fármacos , Fator 88 de Diferenciação Mieloide/metabolismo , Osteoclastos/metabolismo , Pirazinas/farmacologia , RNA/farmacologia , Ribonuclease Pancreático/administração & dosagem , Serotonina/sangue , Serotonina/deficiência , Tiadiazóis/farmacologiaRESUMO
Brain metastasis (br-met) develops in an immunologically unique br-met niche. Central nervous system-native myeloid cells (CNS-myeloids) and bone-marrow-derived myeloid cells (BMDMs) cooperatively regulate brain immunity. The phenotypic heterogeneity and specific roles of these myeloid subsets in shaping the br-met niche to regulate br-met outgrowth have not been fully revealed. Applying multimodal single-cell analyses, we elucidated a heterogeneous but spatially defined CNS-myeloid response during br-met outgrowth. We found Ccr2+ BMDMs minimally influenced br-met while CNS-myeloid promoted br-met outgrowth. Additionally, br-met-associated CNS-myeloid exhibited downregulation of Cx3cr1. Cx3cr1 knockout in CNS-myeloid increased br-met incidence, leading to an enriched interferon response signature and Cxcl10 upregulation. Significantly, neutralization of Cxcl10 reduced br-met, while rCxcl10 increased br-met and recruited VISTAHi PD-L1+ CNS-myeloid to br-met lesions. Inhibiting VISTA- and PD-L1-signaling relieved immune suppression and reduced br-met burden. Our results demonstrate that loss of Cx3cr1 in CNS-myeloid triggers a Cxcl10-mediated vicious cycle, cultivating a br-met-promoting, immune-suppressive niche.
Assuntos
Neoplasias Encefálicas/imunologia , Neoplasias Encefálicas/secundário , Quimiocina CXCL10/metabolismo , Terapia de Imunossupressão , Células Mieloides/metabolismo , Animais , Células da Medula Óssea/metabolismo , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Receptor 1 de Quimiocina CX3C/metabolismo , Sistema Nervoso Central/patologia , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Interferons/metabolismo , Macrófagos/metabolismo , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Testes de Neutralização , Fenótipo , Linfócitos T/imunologia , Transcriptoma/genéticaRESUMO
Stroma is a poorly defined non-parenchymal component of virtually every organ with key roles in organ development, homeostasis, and repair. Studies of the bone marrow stroma have defined individual populations in the stem cell niche regulating hematopoietic regeneration and capable of initiating leukemia. Here, we use single-cell RNA sequencing (scRNA-seq) to define a cellular taxonomy of the mouse bone marrow stroma and its perturbation by malignancy. We identified seventeen stromal subsets expressing distinct hematopoietic regulatory genes spanning new fibroblastic and osteoblastic subpopulations including distinct osteoblast differentiation trajectories. Emerging acute myeloid leukemia impaired mesenchymal osteogenic differentiation and reduced regulatory molecules necessary for normal hematopoiesis. These data suggest that tissue stroma responds to malignant cells by disadvantaging normal parenchymal cells. Our taxonomy of the stromal compartment provides a comprehensive bone marrow cell census and experimental support for cancer cell crosstalk with specific stromal elements to impair normal tissue function and thereby enable emergent cancer.
Assuntos
Células da Medula Óssea/metabolismo , Diferenciação Celular , Homeostase , Leucemia Mieloide Aguda/metabolismo , Osteoblastos/metabolismo , Osteogênese , Microambiente Tumoral , Animais , Células da Medula Óssea/patologia , Humanos , Leucemia Mieloide Aguda/patologia , Camundongos , Osteoblastos/patologia , Células Estromais/metabolismo , Células Estromais/patologiaRESUMO
Nutritional status potentially influences immune responses; however, how nutritional signals regulate cellular dynamics and functionality remains obscure. Herein, we report that temporary fasting drastically reduces the number of lymphocytes by â¼50% in Peyer's patches (PPs), the inductive site of the gut immune response. Subsequent refeeding seemingly restored the number of lymphocytes, but whose cellular composition was conspicuously altered. A large portion of germinal center and IgA+ B cells were lost via apoptosis during fasting. Meanwhile, naive B cells migrated from PPs to the bone marrow during fasting and then back to PPs during refeeding when stromal cells sensed nutritional signals and upregulated CXCL13 expression to recruit naive B cells. Furthermore, temporal fasting before oral immunization with ovalbumin abolished the induction of antigen-specific IgA, failed to induce oral tolerance, and eventually exacerbated food antigen-induced diarrhea. Thus, nutritional signals are critical in maintaining gut immune homeostasis.
Assuntos
Linfócitos B/fisiologia , Imunidade nas Mucosas , Animais , Antígenos/imunologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Medula Óssea/imunologia , Medula Óssea/metabolismo , Quimiocina CXCL13/genética , Quimiocina CXCL13/metabolismo , Jejum , Regulação da Expressão Gênica , Glicólise , Imunoglobulina A/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Estado Nutricional , Ovalbumina/imunologia , Nódulos Linfáticos Agregados/imunologia , Nódulos Linfáticos Agregados/metabolismo , Nódulos Linfáticos Agregados/patologia , Receptores CXCR5/genética , Receptores CXCR5/metabolismo , Transdução de Sinais , Células Estromais/citologia , Células Estromais/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
Immune checkpoint therapy (ICT) shows encouraging results in a subset of patients with metastatic castration-resistant prostate cancer (mCRPC) but still elicits a sub-optimal response among those with bone metastases. Analysis of patients' bone marrow samples revealed increased Th17 instead of Th1 subsets after ICT. To further evaluate the different tumor microenvironments, we injected mice with prostate tumor cells either subcutaneously or intraosseously. ICT in the subcutaneous CRPC model significantly increases intra-tumoral Th1 subsets and improves survival. However, ICT fails to elicit an anti-tumor response in the bone CRPC model despite an increase in the intra-tumoral CD4 T cells, which are polarized to Th17 rather than Th1 lineage. Mechanistically, tumors in the bone promote osteoclast-mediated bone resorption that releases TGF-ß, which restrains Th1 lineage development. Blocking TGF-ß along with ICT increases Th1 subsets and promotes clonal expansion of CD8 T cells and subsequent regression of bone CRPC and improves survival.
Assuntos
Linhagem da Célula , Imunoterapia , Linfócitos T Auxiliares-Indutores/citologia , Microambiente Tumoral , Animais , Antígenos/metabolismo , Neoplasias Ósseas/secundário , Antígeno CTLA-4/metabolismo , Linhagem da Célula/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Clonais , Citocinas/metabolismo , Modelos Animais de Doenças , Memória Imunológica/efeitos dos fármacos , Ipilimumab/farmacologia , Masculino , Camundongos , Osteoclastos/efeitos dos fármacos , Osteoclastos/metabolismo , Receptor de Morte Celular Programada 1/metabolismo , Neoplasias de Próstata Resistentes à Castração/imunologia , Neoplasias de Próstata Resistentes à Castração/patologia , Análise de Sobrevida , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Células Th1/efeitos dos fármacos , Fator de Crescimento Transformador beta/metabolismo , Microambiente Tumoral/efeitos dos fármacosRESUMO
Unlike sessile macrophages that occupy specialized tissue niches, non-classical monocytes (NCMs)-circulating phagocytes that patrol and cleanse the luminal surface of the vascular tree-are characterized by constant movement. Here, we examined the nature of the NCM's nurturing niche. Expression of the growth factor CSF1 on endothelial cells was required for survival of NCMs in the bloodstream. Lack of endothelial-derived CSF1 did not affect blood CSF1 concentration, suggesting that NCMs rely on scavenging CSF1 present on endothelial cells. Deletion of the transmembrane chemokine and adhesion factor CX3CL1 on endothelial cells impaired NCM survival. Mechanistically, endothelial-derived CX3CL1 and integrin subunit alpha L (ITGAL) facilitated the uptake of CSF1 by NCMs. CSF1 was produced by all tissular endothelial cells, and deletion of Csf1 in all endothelial cells except bone marrow sinusoids impaired NCM survival, arguing for a model where the full vascular tree acts as a niche for NCMs and where survival and patrolling function are connected.
RESUMO
Mutations of the CBP/p300 histone acetyltransferase (HAT) domain can be linked to leukemic transformation in humans, suggestive of a checkpoint of leukocyte compartment sizes. Here, we examined the impact of reversible inhibition of this domain by the small-molecule A485. We found that A485 triggered acute and transient mobilization of leukocytes from the bone marrow into the blood. Leukocyte mobilization by A485 was equally potent as, but mechanistically distinct from, granulocyte colony-stimulating factor (G-CSF), which allowed for additive neutrophil mobilization when both compounds were combined. These effects were maintained in models of leukopenia and conferred augmented host defenses. Mechanistically, activation of the hypothalamus-pituitary-adrenal gland (HPA) axis by A485 relayed shifts in leukocyte distribution through corticotropin-releasing hormone receptor 1 (CRHR1) and adrenocorticotropic hormone (ACTH), but independently of glucocorticoids. Our findings identify a strategy for rapid expansion of the blood leukocyte compartment via a neuroendocrine loop, with implications for the treatment of human pathologies.
Assuntos
Medula Óssea , Histona Acetiltransferases , Humanos , Histona Acetiltransferases/metabolismo , Medula Óssea/metabolismo , Histonas/metabolismo , Neutrófilos/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismoRESUMO
Stem cell regulation and hierarchical organization of human skeletal progenitors remain largely unexplored. Here, we report the isolation of a self-renewing and multipotent human skeletal stem cell (hSSC) that generates progenitors of bone, cartilage, and stroma, but not fat. Self-renewing and multipotent hSSCs are present in fetal and adult bones and can also be derived from BMP2-treated human adipose stroma (B-HAS) and induced pluripotent stem cells (iPSCs). Gene expression analysis of individual hSSCs reveals overall similarity between hSSCs obtained from different sources and partially explains skewed differentiation toward cartilage in fetal and iPSC-derived hSSCs. hSSCs undergo local expansion in response to acute skeletal injury. In addition, hSSC-derived stroma can maintain human hematopoietic stem cells (hHSCs) in serum-free culture conditions. Finally, we combine gene expression and epigenetic data of mouse skeletal stem cells (mSSCs) and hSSCs to identify evolutionarily conserved and divergent pathways driving SSC-mediated skeletogenesis. VIDEO ABSTRACT.
Assuntos
Desenvolvimento Ósseo/fisiologia , Osso e Ossos/citologia , Células-Tronco Hematopoéticas/citologia , Animais , Osso e Ossos/metabolismo , Cartilagem/citologia , Diferenciação Celular , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/fisiologia , Células-Tronco Mesenquimais/citologia , Camundongos , Camundongos Endogâmicos C57BL , Transdução de Sinais , Análise de Célula Única/métodos , Células-Tronco/citologia , Células Estromais/citologia , Transcriptoma/genéticaRESUMO
Irisin is secreted by muscle, increases with exercise, and mediates certain favorable effects of physical activity. In particular, irisin has been shown to have beneficial effects in adipose tissues, brain, and bone. However, the skeletal response to exercise is less clear, and the receptor for irisin has not been identified. Here we show that irisin binds to proteins of the αV class of integrins, and biophysical studies identify interacting surfaces between irisin and αV/ß5 integrin. Chemical inhibition of the αV integrins blocks signaling and function by irisin in osteocytes and fat cells. Irisin increases both osteocytic survival and production of sclerostin, a local modulator of bone remodeling. Genetic ablation of FNDC5 (or irisin) completely blocks osteocytic osteolysis induced by ovariectomy, preventing bone loss and supporting an important role of irisin in skeletal remodeling. Identification of the irisin receptor should greatly facilitate our understanding of irisin's function in exercise and human health.
Assuntos
Adipócitos/metabolismo , Tecido Adiposo/metabolismo , Remodelação Óssea , Fibronectinas/metabolismo , Integrina alfaV/metabolismo , Osteócitos/metabolismo , Osteólise/metabolismo , Adipócitos/patologia , Animais , Linhagem Celular Tumoral , Feminino , Fibronectinas/genética , Células HEK293 , Humanos , Integrina alfaV/genética , Camundongos , Osteócitos/patologia , Osteólise/genéticaRESUMO
Hematopoietic stem cell transplantation is a potential curative therapy for malignant and nonmalignant diseases. Improving the efficiency of stem cell collection and the quality of the cells acquired can broaden the donor pool and improve patient outcomes. We developed a rapid stem cell mobilization regimen utilizing a unique CXCR2 agonist, GROß, and the CXCR4 antagonist AMD3100. A single injection of both agents resulted in stem cell mobilization peaking within 15 min that was equivalent in magnitude to a standard multi-day regimen of granulocyte colony-stimulating factor (G-CSF). Mechanistic studies determined that rapid mobilization results from synergistic signaling on neutrophils, resulting in enhanced MMP-9 release, and unexpectedly revealed genetic polymorphisms in MMP-9 that alter activity. This mobilization regimen results in preferential trafficking of stem cells that demonstrate a higher engraftment efficiency than those mobilized by G-CSF. Our studies suggest a potential new strategy for the rapid collection of an improved hematopoietic graft.
Assuntos
Mobilização de Células-Tronco Hematopoéticas/métodos , Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/imunologia , Adulto , Animais , Benzilaminas , Quimiocina CXCL2/farmacologia , Ciclamos , Feminino , Células-Tronco Hematopoéticas/efeitos dos fármacos , Compostos Heterocíclicos/farmacologia , Humanos , Masculino , Metaloproteinase 9 da Matriz/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Endogâmicos ICR , Polimorfismo GenéticoRESUMO
Diet profoundly influences physiology. Whereas over-nutrition elevates risk for disease via its influence on immunity and metabolism, caloric restriction and fasting appear to be salutogenic. Despite multiple correlations observed between diet and health, the underlying biology remains unclear. Here, we identified a fasting-induced switch in leukocyte migration that prolongs monocyte lifespan and alters susceptibility to disease in mice. We show that fasting during the active phase induced the rapid return of monocytes from the blood to the bone marrow. Monocyte re-entry was orchestrated by hypothalamic-pituitary-adrenal (HPA) axis-dependent release of corticosterone, which augmented the CXCR4 chemokine receptor. Although the marrow is a safe haven for monocytes during nutrient scarcity, re-feeding prompted mobilization culminating in monocytosis of chronologically older and transcriptionally distinct monocytes. These shifts altered response to infection. Our study shows that diet-in particular, a diet's temporal dynamic balance-modulates monocyte lifespan with consequences for adaptation to external stressors.