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Phenotypic analysis by flow cytometry is one of the most utilized primary tools to study the hematopoietic system. Here, we present a complex panel designed for spectral flow cytometry that allows for the in-depth analysis of the mouse hematopoietic stem and progenitor compartments. The developed panel encompasses the hematopoietic stem cell (HSC) compartment, an array of multipotent progenitors with early marks of lineage specification and a series of progenitors associated with lymphoid, granulo-macrophagic, megakaryocytic and erythroid lineage commitment. It has a built-in redundancy for key markers known to decipher the fine architecture of the HSC compartment by segregating subsets with different functional potential. As a resource, we used this panel to provide a snapshot view of the evolution of these phenotypically defined hematopoietic compartments during the life of the animals. We show that by using a spectral cytometer, this panel is compatible with the analysis of GFP-expressing gene-reporter mice across the hematopoietic system. We leverage this tool to determine how previously described markers such as CD150, CD34, CD105, CD41, ECPR, and CD49b define specific HSC subsets and confirm that high expression of the transcription factor Gfi1 is a hallmark of the most primitive HSC compartment. Altogether, our results provide a convenient protocol to obtain in one analysis a more extensive view of the hematopoietic architecture in mouse models. Our results could also serve as a base for further development of high-end panels leveraging spectral flow cytometry beyond the 15-fluorochrome panel presented in this report. © 2020 International Society for Advancement of Cytometry.
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Células Madre Hematopoyéticas , Factores de Transcripción , Animales , Biomarcadores , Diferenciación Celular , Linaje de la Célula , Citometría de Flujo , RatonesRESUMEN
The transcription factor Ikaros is essential for B cell development. However, its molecular functions in B cell fate specification and commitment have remained elusive. We show here that the transcription factor EBF restored the generation of CD19(+) pro-B cells from Ikaros-deficient hematopoietic progenitors. Notably, these pro-B cells, despite having normal expression of the transcription factors EBF and Pax5, were not committed to the B cell fate. They also failed to recombine variable gene segments at the immunoglobulin heavy-chain locus. Ikaros promoted heavy-chain gene rearrangements by inducing expression of the recombination-activating genes as well as by controlling accessibility of the variable gene segments and compaction of the immunoglobulin heavy-chain locus. Thus, Ikaros is an obligate component of a network that regulates B cell fate commitment and immunoglobulin heavy-chain gene recombination.
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Linfocitos B/fisiología , Genes de Inmunoglobulinas/genética , Factor de Transcripción Ikaros/metabolismo , Cadenas Pesadas de Inmunoglobulina/genética , VDJ Recombinasas/genética , Animales , Sitios de Unión , Diferenciación Celular , Línea Celular , Linaje de la Célula , Reordenamiento Génico/genética , Reordenamiento Génico/inmunología , Factor de Transcripción Ikaros/genética , RatonesRESUMEN
Haematopoietic stem cells (HSCs) self-renew for life, thereby making them one of the few blood cells that truly age. Paradoxically, although HSCs numerically expand with age, their functional activity declines over time, resulting in degraded blood production and impaired engraftment following transplantation. While many drivers of HSC ageing have been proposed, the reason why HSC function degrades with age remains unknown. Here we show that cycling old HSCs in mice have heightened levels of replication stress associated with cell cycle defects and chromosome gaps or breaks, which are due to decreased expression of mini-chromosome maintenance (MCM) helicase components and altered dynamics of DNA replication forks. Nonetheless, old HSCs survive replication unless confronted with a strong replication challenge, such as transplantation. Moreover, once old HSCs re-establish quiescence, residual replication stress on ribosomal DNA (rDNA) genes leads to the formation of nucleolar-associated γH2AX signals, which persist owing to ineffective H2AX dephosphorylation by mislocalized PP4c phosphatase rather than ongoing DNA damage. Persistent nucleolar γH2AX also acts as a histone modification marking the transcriptional silencing of rDNA genes and decreased ribosome biogenesis in quiescent old HSCs. Our results identify replication stress as a potent driver of functional decline in old HSCs, and highlight the MCM DNA helicase as a potential molecular target for rejuvenation therapies.
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Senescencia Celular/fisiología , Replicación del ADN/fisiología , Células Madre Hematopoyéticas/patología , Estrés Fisiológico , Animales , Proliferación Celular , Senescencia Celular/genética , Daño del ADN/genética , ADN Ribosómico/genética , Femenino , Regulación de la Expresión Génica , Células Madre Hematopoyéticas/citología , Histonas/genética , Histonas/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas de Mantenimiento de Minicromosoma/genéticaRESUMEN
Blood production is ensured by rare, self-renewing haematopoietic stem cells (HSCs). How HSCs accommodate the diverse cellular stresses associated with their life-long activity remains elusive. Here we identify autophagy as an essential mechanism protecting HSCs from metabolic stress. We show that mouse HSCs, in contrast to their short-lived myeloid progeny, robustly induce autophagy after ex vivo cytokine withdrawal and in vivo calorie restriction. We demonstrate that FOXO3A is critical to maintain a gene expression program that poises HSCs for rapid induction of autophagy upon starvation. Notably, we find that old HSCs retain an intact FOXO3A-driven pro-autophagy gene program, and that ongoing autophagy is needed to mitigate an energy crisis and allow their survival. Our results demonstrate that autophagy is essential for the life-long maintenance of the HSC compartment and for supporting an old, failing blood system.
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Autofagia/genética , Metabolismo Energético/genética , Factores de Transcripción Forkhead/metabolismo , Regulación de la Expresión Génica , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Estrés Fisiológico/genética , Envejecimiento , Animales , Apoptosis , Restricción Calórica , Supervivencia Celular/genética , Senescencia Celular , Citocinas/deficiencia , Citocinas/metabolismo , Privación de Alimentos , Proteína Forkhead Box O3 , Homeostasis , Ratones , Ratones Endogámicos C57BLRESUMEN
Expansion of myeloid cells associated with solid tumor development is a key contributor to neoplastic progression. Despite their clinical relevance, the mechanisms controlling myeloid cell production and activity in cancer remains poorly understood. Using a multistage mouse model of breast cancer, we show that production of atypical T cell-suppressive neutrophils occurs during early tumor progression, at the onset of malignant conversion, and that these cells preferentially accumulate in peripheral tissues but not in the primary tumor. Production of these cells results from activation of a myeloid differentiation program in bone marrow (BM) by a novel mechanism in which tumor-derived granulocyte-colony stimulating factor (G-CSF) directs expansion and differentiation of hematopoietic stem cells to skew hematopoiesis toward the myeloid lineage. Chronic skewing of myeloid production occurred in parallel to a decrease in erythropoiesis in BM in mice with progressive disease. Significantly, we reveal that prolonged G-CSF stimulation is both necessary and sufficient for the distinguishing characteristics of tumor-induced immunosuppressive neutrophils. These results demonstrate that prolonged G-CSF may be responsible for both the development and activity of immunosuppressive neutrophils in cancer.
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Neoplasias de la Mama/fisiopatología , Hematopoyesis/inmunología , Tolerancia Inmunológica/inmunología , Células Mieloides/inmunología , Invasividad Neoplásica/fisiopatología , Neutrófilos/inmunología , Animales , Bromodesoxiuridina , Línea Celular Tumoral , Femenino , Citometría de Flujo , Factor Estimulante de Colonias de Granulocitos/sangre , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células Mieloides/fisiología , Receptores de Factor Estimulante de Colonias de Granulocito/genéticaRESUMEN
Although in utero hematopoietic cell transplantation is a promising strategy to treat congenital hematopoietic disorders, levels of engraftment have not been therapeutic for diseases in which donor cells have no survival advantage. We used an antibody against the murine c-Kit receptor (ACK2) to deplete fetal host hematopoietic stem cells (HSCs) and increase space within the hematopoietic niche for donor cell engraftment. Fetal mice were injected with ACK2 on embryonic days 13.5 to 14.5 and surviving pups were transplanted with congenic hematopoietic cells on day of life 1. Low-dose ACK2 treatment effectively depleted HSCs within the bone marrow with minimal toxicity and the antibody was cleared from the serum before the neonatal transplantation. Chimerism levels were significantly higher in treated pups than in controls; both myeloid and lymphoid cell chimerism increased because of higher engraftment of HSCs in the bone marrow. To test the strategy of repeated HSC depletion and transplantation, some mice were treated with ACK2 postnatally, but the increase in engraftment was lower than that seen with prenatal treatment. We demonstrate a successful fetal conditioning strategy associated with minimal toxicity. Such strategies could be used to achieve clinically relevant levels of engraftment to treat congenital stem cell disorders.
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Células Madre Fetales/citología , Terapias Fetales/métodos , Trasplante de Células Madre Hematopoyéticas/métodos , Células Madre Hematopoyéticas/citología , Acondicionamiento Pretrasplante/métodos , Animales , Animales Recién Nacidos , Femenino , Células Madre Fetales/inmunología , Células Madre Hematopoyéticas/inmunología , Ratones , Ratones Endogámicos C57BL , Embarazo , Proteínas Proto-Oncogénicas c-kit/administración & dosificación , Proteínas Proto-Oncogénicas c-kit/antagonistas & inhibidores , Proteínas Proto-Oncogénicas c-kit/inmunología , Nicho de Células Madre/inmunologíaRESUMEN
Gestational diabetes is a common medical complication of pregnancy that is associated with adverse perinatal outcomes and an increased risk of metabolic diseases and atherosclerosis in adult offspring. The mechanisms responsible for this delayed pathological transmission remain unknown. In mouse models, we found that the development of atherosclerosis in adult offspring born to diabetic pregnancy can be in part linked to hematopoietic alterations. Although they do not show any gross metabolic disruptions, the adult offspring maintain hematopoietic features associated with diabetes, indicating the acquisition of a lasting diabetic hematopoietic memory. We show that the induction of this hematopoietic memory during gestation relies on the activity of the advanced glycation end product receptor (AGER) and the nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which lead to increased placental inflammation. In adult offspring, we find that this memory is associated with DNA methyltransferase 1 (DNMT1) upregulation and epigenetic changes in hematopoietic progenitors. Together, our results demonstrate that the hematopoietic system can acquire a lasting memory of gestational diabetes and that this memory constitutes a pathway connecting gestational health to adult pathologies.
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Aterosclerosis , Diabetes Gestacional , Sistema Hematopoyético , Humanos , Femenino , Embarazo , Animales , Ratones , Diabetes Gestacional/genética , Placenta/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/genética , Inflamasomas/metabolismo , Sistema Hematopoyético/metabolismoRESUMEN
The dynamics of the hematopoietic flux responsible for blood cell production in native conditions remains a matter of debate. Using CITE-seq analyses, we uncovered a distinct progenitor population that displays a cell cycle gene signature similar to the one found in quiescent hematopoietic stem cells. We further determined that the CD62L marker can be used to phenotypically enrich this population in the Flt3+ multipotent progenitor (MPP4) compartment. Functional in vitro and in vivo analyses validated the heterogeneity of the MPP4 compartment and established the quiescent/slow-cycling properties of the CD62L- MPP4 cells. Furthermore, studies under native conditions revealed a novel hierarchical organization of the MPP compartments in which quiescent/slow-cycling MPP4 cells sustain a prolonged hematopoietic activity at steady-state while giving rise to other lineage-biased MPP populations. Altogether, our data characterize a durable and productive quiescent/slow-cycling hematopoietic intermediary within the MPP4 compartment and highlight early paths of progenitor differentiation during unperturbed hematopoiesis.
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Hematopoyesis , Células Madre Hematopoyéticas , Diferenciación Celular , División Celular , Células Madre MultipotentesRESUMEN
Activating non-inherited mutations in the guanine nucleotide-binding protein G(q) subunit alpha (GNAQ) gene family have been identified in childhood vascular tumors. Patients experience extensive disfigurement, chronic pain and severe complications including a potentially lethal coagulopathy termed Kasabach-Merritt phenomenon. Animal models for this class of vascular tumors do not exist. This has severely hindered the discovery of the molecular consequences of GNAQ mutations in the vasculature and, in turn, the preclinical development of effective targeted therapies. Here we report a mouse model expressing hyperactive mutant GNAQ in endothelial cells. Mutant mice develop vascular and coagulopathy phenotypes similar to those seen in patients. Mechanistically, by transcriptomic analysis we demonstrate increased mitogen activated protein kinase signaling in the mutant endothelial cells. Targeting of this pathway with Trametinib suppresses the tumor growth by reducing vascular cell proliferation and permeability. Trametinib also prevents the development of coagulopathy and improves mouse survival.
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Melanoma , Neoplasias de la Úvea , Neoplasias Vasculares , Animales , Ratones , Subunidades alfa de la Proteína de Unión al GTP/metabolismo , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/genética , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Células Endoteliales/metabolismo , Apoptosis , Melanoma/genética , Neoplasias de la Úvea/genética , Mutación , Modelos Animales de Enfermedad , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Línea Celular TumoralRESUMEN
Higher body mass index (BMI) is characterized as a chronic inflammatory state with endothelial dysfunction. Endothelial injury after allogeneic hematopoietic stem cell transplantation (allo-HSCT) puts patients at risk for such complications as transplantation-associated thrombotic microangiopathy (TA-TMA) and acute graft-versus-host-disease (aGVHD). To evaluate the impact of increased BMI on endothelial injury after allo-HSCT in pediatric and young adult patients, we conducted a retrospective cohort study evaluating 476 consecutive allo-HSCT children and young adult recipients age 0 to 20 years. Our analysis was subdivided based on distinct age categories (<2 years and 2 to 20 years). BMI was considered as a variable but was also expressed in standard deviations from the mean adjusted for age and sex (z-score), based on established criteria from the World Health Organization (age <2 years) and the Centers for Disease Control and Prevention (age 2 to 20 years) to account for differences associated with age. Primary endpoints included the incidences of TA-TMA and aGVHD. Increased BMI z-score was associated with TA-TMA after allo-HSCT in patients age <2 years (median, 18.1; IQR, 17 to 20; P = .006) and in patients age 2 to 20 years (median, 18.7; IQR, 16 to 21.9; P = .02). Higher BMI z-score correlated with TA-TMA risk in both age groups, with a BMI z-score of .9 in the younger cohort and .7 (IQR, -.4 to 1.6; P = .04) in the older cohort. Increased BMI z-score was associated with an increased risk of TA-TMA in a multivariate analysis of the entire cohort (odds ratio [OR], 1.2; 95% confidence interval [CI], 1.05 to 1.37; P = .008). Multivariate analysis also demonstrated that patients with BMI in the 85th percentile or greater had an increased risk of developing TA-TMA compared to those with a lower BMI percentile (OR, 2.66; 95% CI, 1.62 to 4.32; P < .001). Baseline and day +7 ST2 levels were elevated in subjects with TA-TMA compared to those without TA-TMA in both age groups. Baseline sC5b-9 concentration was not correlated with BMI z-score, but sC5b-9 concentration was increased markedly by 7 days post-allo-HSCT in patients age <2 years who later developed TA-TMA compared to those who never developed TA-TMA (P = .001). The median BMI z-score was higher for patients with aGVHD compared to patients without aGVHD (.7 [range, -3.9 to 3.9] versus .2 [range, -7.8 to 5.4]; P = .03). We show that high BMI is associated with augmented risk of endothelial injury after HSCT, specifically TA-TMA. These data identify a high-risk population likely to benefit from early interventions to prevent endothelial injury and prompt treatment of established endothelial injury.
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Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Microangiopatías Trombóticas , Estados Unidos , Adulto Joven , Humanos , Niño , Recién Nacido , Lactante , Preescolar , Adolescente , Adulto , Estudios Retrospectivos , Índice de Masa Corporal , Microangiopatías Trombóticas/complicaciones , Factores de Riesgo , Trasplante de Células Madre Hematopoyéticas/efectos adversosRESUMEN
Purpose of review: Immunological memory is an important evolutionary adaptation of the immune system. Previously restricted to the adaptive immune system, the concept of memory has recently been broadened to the innate immune system. This review summarizes recent studies that highlight the contribution of the hematopoietic stem cells (HSCs) in supporting immunological memory. Recent findings: Short-lived innate immune cells can build a long-lasting memory of infection to improve their response to secondary challenges. Studies show that these unexpected properties of the innate immune system are sustained by epigenetic and metabolic changes in the HSC compartment. Summary: HSCs are durably altered in response to pathogens and serve as long-term support for innate immune memory. Many questions remain regarding the mechanisms contributing to the induction and the maintenance of this immune memory in HSCs. Answering these questions will open new perspectives to understand how environmental factors shape the HSC activity over time.
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Hematopoietic stem cell (HSC) activity is tightly controlled to ensure the integrity of the hematopoietic system during the organism's lifetime. How the HSC compartment maintains its long-term fitness in conditions of chronic stresses associated with systemic metabolic disorders is poorly understood. In this study, we show that obesity functionally affects the long-term function of the most immature engrafting HSC subpopulation. We link this altered regenerative activity to the oxidative stress and the aberrant constitutive activation of the AKT signaling pathway that characterized the obese environment. In contrast, we found minor disruptions of the HSC function in obese mice at steady state, suggesting that active mechanisms could protect the HSC compartment from its disturbed environment. Consistent with this idea, we found that FOXO proteins in HSCs isolated from obese mice become insensitive to their normal upstream regulators such as AKT, even during intense oxidative stress. We established that hyperglycemia, a key condition associated with obesity, is directly responsible for the alteration of the AKT-FOXO axis in HSCs and their abnormal oxidative stress response. As a consequence, we observed that HSCs isolated from a hyperglycemic environment display enhanced resistance to oxidative stress and DNA damage. Altogether, these results indicate that chronic metabolic stresses associated with obesity and/or hyperglycemia affect the wiring of the HSCs and modify their oxidative stress response. These data suggest that the uncoupling of FOXO from its environmental regulators could be a key adaptive strategy that promotes the survival of the HSC compartment in obesity.
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Células Madre Hematopoyéticas , Hiperglucemia , Animales , Daño del ADN , Ratones , Estrés Oxidativo , Transducción de SeñalRESUMEN
PURPOSE OF REVIEW: The hematopoietic stem cell (HSC) compartment is the cornerstone of a lifelong blood cell production but also contributes to the ability of the hematopoietic system to dynamically respond to environmental challenges. This review summarizes our knowledge about the interaction between HSCs and its inflammatory environment during life and questions how its disruption could affect the health of the hematopoietic system. RECENT FINDINGS: The latest research demonstrates the direct role of inflammatory signals in promoting the emergence of the HSCs during development and in setting their steady-state activity in adults. They indicate that inflammatory patho-physiological conditions or immunological history could shape the structure and biology of the HSC compartment, therefore altering its overall fitness. SUMMARY: Through instructive and/or selective mechanisms, the inflammatory environment seems to provide a key homeostatic signal for HSCs. Although the mechanistic basis of this complex interplay remains to be fully understood, its dysregulation has broad consequences on HSC physiology and the development of hematological diseases. As such, developing experimental models that fully recapitulate a normal basal inflammatory state could be essential to fully assess HSC biology in native conditions.
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Obesity is a chronic organismal stress that disrupts multiple systemic and tissue-specific functions. In this study, we describe the impact of obesity on the activity of the hematopoietic stem cell (HSC) compartment. We show that obesity alters the composition of the HSC compartment and its activity in response to hematopoietic stress. The impact of obesity on HSC function is progressively acquired but persists after weight loss or transplantation into a normal environment. Mechanistically, we establish that the oxidative stress induced by obesity dysregulates the expression of the transcription factor Gfi1 and that increased Gfi1 expression is required for the abnormal HSC function induced by obesity. These results demonstrate that obesity produces durable changes in HSC function and phenotype and that elevation of Gfi1 expression in response to the oxidative environment is a key driver of the altered HSC properties observed in obesity. Altogether, these data provide phenotypic and mechanistic insight into durable hematopoietic dysregulations resulting from obesity.
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Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Células Madre Hematopoyéticas/metabolismo , Obesidad/genética , Obesidad/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Animales , Proteínas de Unión al ADN/deficiencia , Modelos Animales de Enfermedad , Regulación de la Expresión Génica , Hematopoyesis/genética , Hematopoyesis/fisiología , Trasplante de Células Madre Hematopoyéticas , Células Madre Hematopoyéticas/patología , Ratones , Ratones Congénicos , Ratones Endogámicos C57BL , Ratones Obesos , Ratones Transgénicos , Obesidad/patología , Estrés Oxidativo , Factores de Transcripción/deficiencia , Regulación hacia ArribaRESUMEN
Nonalcoholic fatty liver disease (NAFLD), a common prelude to cirrhosis and hepatocellular carcinoma, is the most common chronic liver disease worldwide. Defining the molecular mechanisms underlying the pathogenesis of NAFLD has been hampered by a lack of animal models that closely recapitulate the severe end of the disease spectrum in humans, including bridging hepatic fibrosis. Here we demonstrate that a novel experimental model employing thermoneutral housing, as opposed to standard housing, resulted in lower stress-driven production of corticosterone, augmented mouse proinflammatory immune responses and markedly exacerbated high-fat diet (HFD)-induced NAFLD pathogenesis. Disease exacerbation at thermoneutrality was conserved across multiple mouse strains and was associated with augmented intestinal permeability, an altered microbiome and activation of inflammatory pathways that are associated with the disease in humans. Depletion of Gram-negative microbiota, hematopoietic cell deletion of Toll-like receptor 4 (TLR4) and inactivation of the IL-17 axis resulted in altered immune responsiveness and protection from thermoneutral-housing-driven NAFLD amplification. Finally, female mice, typically resistant to HFD-induced obesity and NAFLD, develop full disease characteristics at thermoneutrality. Thus, thermoneutral housing provides a sex-independent model of exacerbated NAFLD in mice and represents a novel approach for interrogation of the cellular and molecular mechanisms underlying disease pathogenesis.
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Dieta Alta en Grasa , Vivienda para Animales , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Obesidad/metabolismo , Receptores de Interleucina-17/inmunología , Estrés Fisiológico/inmunología , Temperatura , Receptor Toll-Like 4/metabolismo , Animales , Frío , Corticosterona/metabolismo , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Femenino , Citometría de Flujo , Microbioma Gastrointestinal/inmunología , Perfilación de la Expresión Génica , Bacterias Gramnegativas/inmunología , Células Madre Hematopoyéticas/metabolismo , Humanos , Inflamación , Mucosa Intestinal/metabolismo , Yeyuno/metabolismo , Aprendizaje Automático , Masculino , Ratones , Ratones Noqueados , Enfermedad del Hígado Graso no Alcohólico/inmunología , Obesidad/inmunología , Permeabilidad , Receptores de Interleucina-17/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores Sexuales , Receptor Toll-Like 4/genéticaRESUMEN
This corrects the article DOI: 10.1038/nm.4346.
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Despite great advances in understanding the mechanisms underlying blood production, lineage specification at the level of multipotent progenitors (MPPs) remains poorly understood. Here, we show that MPP2 and MPP3 are distinct myeloid-biased MPP subsets that work together with lymphoid-primed MPP4 cells to control blood production. We find that all MPPs are produced in parallel by hematopoietic stem cells (HSCs), but with different kinetics and at variable levels depending on hematopoietic demands. We also show that the normally rare myeloid-biased MPPs are transiently overproduced by HSCs in regenerating conditions, hence supporting myeloid amplification to rebuild the hematopoietic system. This shift is accompanied by a reduction in self-renewal activity in regenerating HSCs and reprogramming of MPP4 fate toward the myeloid lineage. Our results support a dynamic model of blood development in which HSCs convey lineage specification through independent production of distinct lineage-biased MPP subsets that, in turn, support lineage expansion and differentiation.
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Hematopoyesis , Células Madre Multipotentes/clasificación , Células Madre Multipotentes/citología , Animales , Diferenciación Celular , Linaje de la Célula , Reprogramación Celular , Expresión Génica , Células Madre Hematopoyéticas/clasificación , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/fisiología , Células Progenitoras Linfoides/clasificación , Células Progenitoras Linfoides/citología , Células Progenitoras Linfoides/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Modelos Biológicos , Células Madre Multipotentes/fisiología , Células Progenitoras Mieloides/clasificación , Células Progenitoras Mieloides/citología , Células Progenitoras Mieloides/fisiología , RegeneraciónRESUMEN
Chromosome 7 deletions are highly prevalent in myelodysplastic syndrome (MDS) and likely contribute to aberrant growth through haploinsufficiency. We generated mice with a heterozygous germ line deletion of a 2-Mb interval of chromosome band 5A3 syntenic to a commonly deleted segment of human 7q22 and show that mutant hematopoietic cells exhibit cardinal features of MDS. Specifically, the long-term hematopoietic stem cell (HSC) compartment is expanded in 5A3(+/del) mice, and the distribution of myeloid progenitors is altered. 5A3(+/del) HSCs are defective for lymphoid repopulating potential and show a myeloid lineage output bias. These cell autonomous abnormalities are exacerbated by physiologic aging and upon serial transplantation. The 5A3 deletion partially rescues defective repopulation in Gata2 mutant mice. 5A3(+/del) hematopoietic cells exhibit decreased expression of oxidative phosphorylation genes, increased levels of reactive oxygen species, and perturbed oxygen consumption. These studies provide the first functional data linking 7q22 deletions to MDS pathogenesis.
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Cromosomas Humanos Par 7 , Sitios Genéticos , Haploinsuficiencia , Síndromes Mielodisplásicos/genética , Animales , Modelos Animales de Enfermedad , Humanos , Ratones Endogámicos C57BL , Fosforilación Oxidativa , Oxígeno/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Eliminación de SecuenciaRESUMEN
Multipotent stromal cells (MSCs) and their osteoblastic lineage cell (OBC) derivatives are part of the bone marrow (BM) niche and contribute to hematopoietic stem cell (HSC) maintenance. Here, we show that myeloproliferative neoplasia (MPN) progressively remodels the endosteal BM niche into a self-reinforcing leukemic niche that impairs normal hematopoiesis, favors leukemic stem cell (LSC) function, and contributes to BM fibrosis. We show that leukemic myeloid cells stimulate MSCs to overproduce functionally altered OBCs, which accumulate in the BM cavity as inflammatory myelofibrotic cells. We identify roles for thrombopoietin, CCL3, and direct cell-cell interactions in driving OBC expansion, and for changes in TGF-ß, Notch, and inflammatory signaling in OBC remodeling. MPN-expanded OBCs, in turn, exhibit decreased expression of many HSC retention factors and severely compromised ability to maintain normal HSCs, but effectively support LSCs. Targeting this pathological interplay could represent a novel avenue for treatment of MPN-affected patients and prevention of myelofibrosis.