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Allogeneic hematopoietic stem cell transplantation (alloSCT) is, in many clinical settings, the only curative treatment for acute myeloid leukemia (AML). The clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. However, AML relapse remains the top cause of posttransplant death; this highlights the urgent need to enhance GVL. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. In this article, we report, the successful establishment of a novel (to our knowledge) humanized GVL model system by transplanting clinically paired donor PBMCs and patient AML into MHC class I/II knockout NSG mice. We observed significantly reduced leukemia growth in humanized mice compared with mice that received AML alone, demonstrating a functional GVL effect. Using this model system, we studied human GVL responses against human AML cells in vivo and discovered that AML induced T cell depletion, likely because of increased T cell apoptosis. In addition, AML caused T cell exhaustion manifested by upregulation of inhibitory receptors, increased expression of exhaustion-related transcription factors, and decreased T cell function. Importantly, combined blockade of human T cell-inhibitory pathways effectively reduced leukemia burden and reinvigorated CD8 T cell function in this model system. These data, generated in a highly clinically relevant humanized GVL model, not only demonstrate AML-induced inhibition of alloreactive T cells but also identify promising therapeutic strategies targeting T cell depletion and exhaustion for overcoming GVL failure and treating AML relapse after alloSCT.
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Relapse of acute myeloid leukemia (AML) remains a significant concern due to persistent leukemia-initiating stem cells (LICs) that are typically not targeted by most existing therapies. Using a murine AML model, human AML cell lines, and patient samples, we show that AML LICs are sensitive to endogenous and exogenous cyclopentenone prostaglandin-J (CyPG), Δ12-PGJ2, and 15d-PGJ2, which are increased upon dietary selenium supplementation via the cyclooxygenase-hematopoietic PGD synthase pathway. CyPGs are endogenous ligands for peroxisome proliferator-activated receptor gamma and GPR44 (CRTH2; PTGDR2). Deletion of GPR44 in a mouse model of AML exacerbated the disease suggesting that GPR44 activation mediates selenium-mediated apoptosis of LICs. Transcriptomic analysis of GPR44-/- LICs indicated that GPR44 activation by CyPGs suppressed KRAS-mediated MAPK and PI3K/AKT/mTOR signaling pathways, to enhance apoptosis. Our studies show the role of GPR44, providing mechanistic underpinnings of the chemopreventive and chemotherapeutic properties of selenium and CyPGs in AML.
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Leucemia Mieloide Aguda , Selenio , Humanos , Ratones , Animales , Fosfatidilinositol 3-Quinasas , Transducción de Señal , Línea CelularRESUMEN
Inflammation skews bone marrow hematopoiesis increasing the production of myeloid effector cells at the expense of steady-state erythropoiesis. A compensatory stress erythropoiesis response is induced to maintain homeostasis until inflammation is resolved. In contrast to steady-state erythroid progenitors, stress erythroid progenitors (SEPs) utilize signals induced by inflammatory stimuli. However, the mechanistic basis for this is not clear. Here we reveal a nitric oxide (NO)-dependent regulatory network underlying two stages of stress erythropoiesis, namely proliferation, and the transition to differentiation. In the proliferative stage, immature SEPs and cells in the niche increased expression of inducible nitric oxide synthase ( Nos2 or iNOS ) to generate NO. Increased NO rewires SEP metabolism to increase anabolic pathways, which drive the biosynthesis of nucleotides, amino acids and other intermediates needed for cell division. This NO-dependent metabolism promotes cell proliferation while also inhibiting erythroid differentiation leading to the amplification of a large population of non-committed progenitors. The transition of these progenitors to differentiation is mediated by the activation of nuclear factor erythroid 2-related factor 2 (Nfe2l2 or Nrf2). Nrf2 acts as an anti-inflammatory regulator that decreases NO production, which removes the NO-dependent erythroid inhibition and allows for differentiation. These data provide a paradigm for how alterations in metabolism allow inflammatory signals to amplify immature progenitors prior to differentiation. Key points: Nitric-oxide (NO) dependent signaling favors an anabolic metabolism that promotes proliferation and inhibits differentiation.Activation of Nfe2l2 (Nrf2) decreases NO production allowing erythroid differentiation.
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There is an unmet need for novel therapies to treat acute myeloid leukemia (AML) and the associated relapse that involves persistent leukemia stem cells (LSCs). An experimental AML rodent model to test therapies based on successfully transplanting these cells via retro-orbital injections in recipient mice is fraught with challenges. The aim of this study was to develop an easy, reliable, and consistent method to generate a robust murine model of AML using an intra-peritoneal route. In the present protocol, bone marrow cells were transduced with a retrovirus expressing human MLL-AF9 fusion oncoprotein. The efficiency of lineage negative (Lin-) and Lin-Sca-1+c-Kit+ (LSK) populations as donor LSCs in the development of primary AML was tested, and intra-peritoneal injection was adopted as a new method to generate AML. Comparison between intra-peritoneal and retro-orbital injections was done in serial transplantations to compare and contrast the two methods. Both Lin- and LSK cells transduced with human MLL-AF9 virus engrafted well in the bone marrow and spleen of recipients, leading to a full-blown AML. The intra-peritoneal injection of donor cells established AML in recipients upon serial transplantation, and the infiltration of AML cells was detected in the blood, bone marrow, spleen, and liver of recipients by flow cytometry, qPCR, and histological analyses. Thus, intra-peritoneal injection is an efficient method of AML induction using serial transplantation of donor leukemic cells.
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Leucemia Mieloide Aguda , Ratones , Animales , Humanos , Leucemia Mieloide Aguda/terapia , Leucemia Mieloide Aguda/patología , Médula Ósea/patología , Células de la Médula ÓseaRESUMEN
Interleukin-4 (IL-4) is a signature cytokine pivotal in Type 2 helper T cell (Th2) immune response, particularly in allergy and hypersensitivity. Interestingly, IL-4 increases endogenous levels of prostaglandin D2 (PGD2 ) and its metabolites, Δ12 -prostaglandin J2 (Δ12 -PGJ2 ) and 15-deoxy-Δ12,14 -prostaglandin J2 (15d-PGJ2 ), collectively called cyclopentenone PGs (CyPGs). However, the therapeutic role of IL-4 in hematologic malignancies remains unclear. Here, we employed a murine model of acute myeloid leukemia (AML), where human MLL-AF9 fusion oncoprotein was expressed in hematopoietic progenitor cells, to test the effect of IL-4 treatment in vivo. Daily intraperitoneal treatment with IL-4 at 60 µg/kg/d significantly alleviated the severity of AML, as seen by decreased leukemia-initiating cells (LICs). The effect of IL-4 was mediated, in part, by the enhanced expression of hematopoietic- PGD2 synthase (H-PGDS) to effect endogenous production of CyPGs, through autocrine and paracrine signaling mechanisms. Similar results were seen with patient-derived AML cells cultured ex vivo with IL-4. Use of GW9662, a peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, suggested endogenous CyPGs-PPARγ axis mediated p53-dependent apoptosis of LICs by IL-4. Taken together, our results reveal a beneficial role of IL-4 treatment in AML suggesting a potential therapeutic regimen worthy of clinical trials in patients with AML.
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Interleucina-4 , Leucemia Mieloide Aguda , Prostaglandina D2 , Animales , Citocinas , Humanos , Interleucina-4/farmacología , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/metabolismo , Ratones , PPAR gamma/metabolismo , Prostaglandina D2/metabolismoRESUMEN
Steady state erythropoiesis produces new erythrocytes at a constant rate to replace the senescent cells that are removed by macrophages in the liver and spleen. However, infection and tissue damage disrupt the production of erythrocytes by steady state erythropoiesis. During these times, stress erythropoiesis is induced to compensate for the loss of erythroid output. The strategy of stress erythropoiesis is different than steady state erythropoiesis. Stress erythropoiesis generates a wave of new erythrocytes to maintain homeostasis until steady state conditions are resumed. Stress erythropoiesis relies on the rapid proliferation of immature progenitor cells that do not differentiate until the increase in serum Erythropoietin (Epo) promotes the transition to committed progenitors that enables their synchronous differentiation. Emerging evidence has revealed a central role for cell metabolism in regulating the proliferation and differentiation of stress erythroid progenitors. During the initial expansion stage, the immature progenitors are supported by extensive metabolic changes which are designed to direct the use of glucose and glutamine to increase the biosynthesis of macromolecules necessary for cell growth and division. At the same time, these metabolic changes act to suppress the expression of genes involved in erythroid differentiation. In the subsequent transition stage, changes in niche signals alter progenitor metabolism which in turn removes the inhibition of erythroid differentiation generating a bolus of new erythrocytes to alleviate anemia. This review summarizes what is known about the metabolic regulation of stress erythropoiesis and discusses potential mechanisms for metabolic regulation of proliferation and differentiation.
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The prognosis for acute myeloid leukemia (AML) relapse post allogeneic hematopoietic stem cell transplantation (alloSCT) is dismal. Novel effective treatment is urgently needed. Clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. The mechanisms that mediate immune escape of leukemia (thus causing GVL failure) remain poorly understood. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. Here, using our large, longitudinal clinical tissue bank that include AML cells and G-CSF mobilized donor hematopoietic stem cells (HSCs), we successfully established a novel GVL model in humanized mice. Donor HSCs were injected into immune-deficient NOD-Cg-Prkdcscid IL2rgtm1Wjl /SzJ (NSG) mice to build humanized mice. Immune reconstitution in these mice recapitulated some clinical scenario in the patient who received the corresponding HSCs. Allogeneic but HLA partially matched patient-derived AML cells were successfully engrafted in these humanized mice. Importantly, we observed a significantly reduced (yet incomplete elimination of) leukemia growth in humanized mice compared with that in control NSG mice, demonstrating a functional (but defective) GVL effect. Thus, for the first time, we established a novel humanized mouse model that can be used for studying human GVL responses against human AML cells in vivo. This novel clinically relevant model provides a valuable platform for investigating the mechanisms of human GVL and development of effective leukemia treatments.
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Modelos Animales de Enfermedad , Efecto Injerto vs Leucemia/inmunología , Trasplante de Células Madre Hematopoyéticas/métodos , Células Madre Hematopoyéticas/citología , Leucemia Mieloide Aguda/terapia , Animales , Factor Estimulante de Colonias de Granulocitos/administración & dosificación , Humanos , Leucemia Mieloide Aguda/inmunología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Trasplante HomólogoRESUMEN
Our sphingosine kinase inhibitor (SKI) optimization studies originated with the optimization of the SKI-I chemotype by replacement of the substituted benzyl rings with substituted phenyl rings giving rise to the discovery of SKI-178. We have recently reported that SKI-178 is a dual-targeted inhibitor of both sphingosine kinase isoforms (SphK1/2) and a microtubule disrupting agent (MDA). In mechanism-of-action studies, we have shown that these two separate actions synergize to induce cancer cell death in acute myeloid leukemia (AML) cell and animal models. Owning to the effectiveness of SKI-178, we sought to further refine the chemotype while maintaining "on-target" SKI and MDA activities. Herein, we modified the "linker region" between the substituted phenyl rings of SKI-178 through a structure guided approach. These studies have yielded the discovery of an SKI-178 congener, SKI-349, with log-fold enhancements in both SphK inhibition and cytotoxic potency. Importantly, SKI-349 also demonstrates log-fold improvements in therapeutic efficacy in a retro-viral transduction model of MLL-AF9 AML as compared to previous studies with SKI-178. Together, our results strengthen the hypothesis that simultaneous targeting of the sphingosine kinases (SphK1/2) and the induction of mitotic spindle assembly checkpoint arrest, via microtubule disruption, might be an effective therapeutic strategy for hematological malignancies including AML.
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Antineoplásicos/farmacología , Desarrollo de Medicamentos , Inhibidores Enzimáticos/farmacología , Microtúbulos/efectos de los fármacos , Fosfotransferasas (Aceptor de Grupo Alcohol)/antagonistas & inhibidores , Antineoplásicos/síntesis química , Antineoplásicos/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Humanos , Microtúbulos/metabolismo , Estructura Molecular , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Polimerizacion/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
Steady-state erythropoiesis generates new erythrocytes at a constant rate, and it has enormous productive capacity. This production is balanced by the removal of senescent erythrocytes by macrophages in the spleen and liver. Erythroid homeostasis is highly regulated to maintain sufficient erythrocytes for efficient oxygen delivery to the tissues, while avoiding viscosity problems associated with overproduction. However, there are times when this constant production of erythrocytes is inhibited or is inadequate; at these times, erythroid output is increased to compensate for the loss of production. In some cases, increased steady-state erythropoiesis can offset the loss of erythrocytes but, in response to inflammation caused by infection or tissue damage, steady-state erythropoiesis is inhibited. To maintain homeostasis under these conditions, an alternative stress erythropoiesis pathway is activated. Emerging data suggest that the bone morphogenetic protein 4 (BMP4)-dependent stress erythropoiesis pathway is integrated into the inflammatory response and generates a bolus of new erythrocytes that maintain homeostasis until steady-state erythropoiesis can resume. In this perspective, we define the mechanisms that generate new erythrocytes when steady-state erythropoiesis is impaired and discuss experimental models to study human stress erythropoiesis.
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Proteína Morfogenética Ósea 4/genética , Eritrocitos/citología , Células Precursoras Eritroides/citología , Eritropoyesis/genética , Macrófagos/citología , Estrés Fisiológico/genética , Animales , Proteína Morfogenética Ósea 4/inmunología , Senescencia Celular/inmunología , Citocinas/genética , Citocinas/inmunología , Eritrocitos/inmunología , Células Precursoras Eritroides/inmunología , Eritropoyesis/inmunología , Regulación de la Expresión Génica , Humanos , Inflamación , Hígado/citología , Hígado/inmunología , Macrófagos/inmunología , Ratones , Modelos Biológicos , Fagocitosis , Bazo/citología , Bazo/inmunología , Estrés Fisiológico/inmunologíaRESUMEN
Anemic stress induces stress erythropoiesis, which rapidly generates new erythrocytes to restore tissue oxygenation. Stress erythropoiesis is best understood in mice where it is extramedullary and occurs primarily in the spleen. However, both human and mouse stress erythropoiesis use signals and progenitor cells that are distinct from steady-state erythropoiesis. Immature stress erythroid progenitors (SEPs) are derived from short-term hematopoietic stem cells. Although the SEPs are capable of self-renewal, they are erythroid restricted. Inflammation and anemic stress induce the rapid proliferation of SEPs, but they do not differentiate until serum erythropoietin (Epo) levels increase. Here we show that rather than directly regulating SEPs, Epo promotes this transition from proliferation to differentiation by acting on macrophages in the splenic niche. During the proliferative stage, macrophages produce canonical Wnt ligands that promote proliferation and inhibit differentiation. Epo/Stat5-dependent signaling induces the production of bioactive lipid mediators in macrophages. Increased production of prostaglandin J2 (PGJ2) activates peroxisome proliferator-activated receptor γ (PPARγ)-dependent repression of Wnt expression, whereas increased production of prostaglandin E2 (PGE2) promotes the differentiation of SEPs.
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Diferenciación Celular , Células Eritroides/metabolismo , Macrófagos/metabolismo , Receptores de Eritropoyetina/metabolismo , Transducción de Señal , Bazo/metabolismo , Nicho de Células Madre , Animales , Dinoprostona/genética , Dinoprostona/metabolismo , Células Eritroides/citología , Humanos , Macrófagos/citología , Ratones , Ratones Transgénicos , PPAR gamma/genética , PPAR gamma/metabolismo , Prostaglandina D2/análogos & derivados , Prostaglandina D2/genética , Prostaglandina D2/metabolismo , Receptores de Eritropoyetina/genética , Factor de Transcripción STAT5/genética , Factor de Transcripción STAT5/metabolismo , Bazo/citologíaRESUMEN
Bone marrow medullary erythropoiesis is primarily homeostatic. It produces new erythrocytes at a constant rate, which is balanced by the turnover of senescent erythrocytes by macrophages in the spleen. Despite the enormous capacity of the bone marrow to produce erythrocytes, there are times when it is unable to keep pace with erythroid demand. At these times stress erythropoiesis predominates. Stress erythropoiesis generates a large bolus of new erythrocytes to maintain homeostasis until steady state erythropoiesis can resume. In this review, we outline the mechanistic differences between stress erythropoiesis and steady state erythropoiesis and show that their responses to inflammation are complementary. We propose a new hypothesis that stress erythropoiesis is induced by inflammation and plays a key role in maintaining erythroid homeostasis during inflammatory responses.
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Eritropoyesis/inmunología , Inflamación/inmunología , Estrés Fisiológico/inmunología , Animales , Humanos , RatonesRESUMEN
In contrast to steady-state erythropoiesis, which generates new erythrocytes at a constant rate, stress erythropoiesis rapidly produces a large bolus of new erythrocytes in response to anemic stress. In this study, we illustrate that Yes-associated protein (Yap1) promotes the rapid expansion of a transit-amplifying population of stress erythroid progenitors in vivo and in vitro. Yap1-mutated erythroid progenitors failed to proliferate in the spleen after transplantation into lethally irradiated recipient mice. Additionally, loss of Yap1 impaired the growth of actively proliferating erythroid progenitors in vitro. This role in proliferation is supported by gene expression profiles showing that transiently amplifying stress erythroid progenitors express high levels of genes associated with Yap1 activity and genes induced by Yap1. Furthermore, Yap1 promotes the proliferation of stress erythroid progenitors in part by regulating the expression of key glutamine-metabolizing enzymes. Thus, Yap1 acts as an erythroid regulator that coordinates the metabolic status with the proliferation of erythroid progenitors to promote stress erythropoiesis.
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Proteínas Adaptadoras Transductoras de Señales/fisiología , Proteínas de Ciclo Celular/fisiología , Células Precursoras Eritroides/fisiología , Eritropoyesis/fisiología , Regeneración/fisiología , Proteínas Adaptadoras Transductoras de Señales/genética , Alelos , Animales , División Celular , Células Cultivadas , Inducción Enzimática , Células Precursoras Eritroides/citología , Eliminación de Gen , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Ratones , Ratones Endogámicos C57BL , ARN Mensajero/biosíntesis , Quimera por Radiación , Tolerancia a Radiación , Proteínas Recombinantes/metabolismo , Bazo/citología , Estrés Fisiológico/genética , Factores de Transcripción/genética , Proteínas Señalizadoras YAPRESUMEN
Prostaglandin D2 and its cyclopentenone metabolites [cyclopentenone prostaglandins (CyPGs)], Δ12prostaglandin J2 and 15-deoxy-Δ12,14-prostaglandin J2, act through 2 GPCRs, d-type prostanoid 1 and the chemoattractant receptor homologous molecule expressed on type 2 T-helper cells (Crth2). In addition to its role in allergy and asthma, the role of Crth2 in the resolution of inflammation, to mediate the proresolving functions of endogenous CyPGs, is not well understood. We investigated the regulation of LPS or zymosan-induced inflammatory response by signals from the Crth2 receptor in macrophages that lack Crth2 expression [knockout (KO)]. Increased expression of proinflammatory genes, including Tnf-α, was observed in Crth2 KO cells. Targeting the endogenous biosynthetic pathway of CyPGs with indomethacin or HQL79, which inhibit cyclooxygenases or hematopoietic prostaglandin D synthase, respectively, or use of Crth2 antagonists recapitulated the proinflammatory phenotype as in Crth2 KO cells. Ligand-dependent activation of Crth2 by 13,14-dihydro-15-keto-prostaglandin D2 increased Ca2+ influx through store-operated Ca2+ entry (SOCE) accompanied by the up-regulation of stromal interaction molecule 1 and calcium release-activated calcium modulator 1 expression, suggesting that the proresolution effects of CyPG-dependent activation of SOCE could be mediated by Crth2 during inflammation. Interestingly, Crth2 signaling down-regulated the Ca2+-regulated heat stable protein 1 that stabilizes Tnf-α mRNA via the increased expression of microRNA 155 to dampen inflammatory responses triggered through the TNF-α-NF-κB axis. In summary, these studies present a novel regulatory role for Crth2 during inflammatory response in macrophages.-Diwakar, B. T., Yoast, R., Nettleford, S., Qian, F., Lee, T.-J., Berry, S., Huffnagle, I., Rossi, R. M., Trebak, M., Paulson, R. F., Prabhu, K. S. Crth2 receptor signaling down-regulates lipopolysaccharide-induced NF-κB activation in murine macrophages via changes in intracellular calcium.
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Calcio/metabolismo , Regulación hacia Abajo , Lipopolisacáridos/farmacología , Macrófagos/metabolismo , FN-kappa B/metabolismo , Receptores Inmunológicos/metabolismo , Receptores de Prostaglandina/metabolismo , Transducción de Señal , Animales , Inflamación/metabolismo , Inflamación/prevención & control , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células RAW 264.7 , Receptores Inmunológicos/genética , Receptores de Prostaglandina/genéticaRESUMEN
Inflammation alters bone marrow hematopoiesis to favor the production of innate immune effector cells at the expense of lymphoid cells and erythrocytes. Furthermore, proinflammatory cytokines inhibit steady-state erythropoiesis, which leads to the development of anemia in diseases with chronic inflammation. Acute anemia or hypoxic stress induces stress erythropoiesis, which generates a wave of new erythrocytes to maintain erythroid homeostasis until steady-state erythropoiesis can resume. Although hypoxia-dependent signaling is a key component of stress erythropoiesis, we found that inflammation also induced stress erythropoiesis in the absence of hypoxia. Using a mouse model of sterile inflammation, we demonstrated that signaling through Toll-like receptors (TLRs) paradoxically increased the phagocytosis of erythrocytes (erythrophagocytosis) by macrophages in the spleen, which enabled expression of the heme-responsive gene encoding the transcription factor SPI-C. Increased amounts of SPI-C coupled with TLR signaling promoted the expression of Gdf15 and Bmp4, both of which encode ligands that initiate the expansion of stress erythroid progenitors (SEPs) in the spleen. Furthermore, despite their inhibition of steady-state erythropoiesis in the bone marrow, the proinflammatory cytokines TNF-α and IL-1ß promoted the expansion and differentiation of SEPs in the spleen. These data suggest that inflammatory signals induce stress erythropoiesis to maintain erythroid homeostasis when inflammation inhibits steady-state erythropoiesis.
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Proteínas de Unión al ADN/inmunología , Eritropoyesis/inmunología , Hemo/inmunología , Inflamación/inmunología , Estrés Fisiológico/inmunología , Animales , Proteína Morfogenética Ósea 4/genética , Proteína Morfogenética Ósea 4/inmunología , Proteína Morfogenética Ósea 4/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Eritrocitos/inmunología , Eritrocitos/metabolismo , Células Precursoras Eritroides/inmunología , Células Precursoras Eritroides/metabolismo , Eritropoyesis/genética , Factor 15 de Diferenciación de Crecimiento/genética , Factor 15 de Diferenciación de Crecimiento/inmunología , Factor 15 de Diferenciación de Crecimiento/metabolismo , Hemo/metabolismo , Inflamación/genética , Inflamación/metabolismo , Macrófagos/inmunología , Macrófagos/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Fagocitosis/genética , Fagocitosis/inmunología , Transducción de Señal/genética , Transducción de Señal/inmunología , Bazo/inmunología , Bazo/metabolismo , Estrés Fisiológico/genéticaRESUMEN
Anemic stress induces the proliferation of stress erythroid progenitors in the murine spleen that subsequently differentiate to generate erythrocytes to maintain homeostasis. This process relies on the interaction between stress erythroid progenitors and the signals generated in the splenic erythroid niche. In this study, we demonstrate that although growth-differentiation factor 15 (Gdf15) is not required for steady-state erythropoiesis, it plays an essential role in stress erythropoiesis. Gdf15 acts at 2 levels. In the splenic niche, Gdf15-/- mice exhibit defects in the monocyte-derived expansion of the splenic niche, resulting in impaired proliferation of stress erythroid progenitors and production of stress burst forming unit-erythroid cells. Furthermore, Gdf15 signaling maintains the hypoxia-dependent expression of the niche signal, Bmp4, whereas in stress erythroid progenitors, Gdf15 signaling regulates the expression of metabolic enzymes, which contribute to the rapid proliferation of stress erythroid progenitors. Thus, Gdf15 functions as a comprehensive regulator that coordinates the stress erythroid microenvironment with the metabolic status of progenitors to promote stress erythropoiesis.
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Células Precursoras Eritroides/metabolismo , Eritropoyesis/genética , Factor 15 de Diferenciación de Crecimiento/genética , Nicho de Células Madre , Estrés Fisiológico , Animales , Diferenciación Celular , Proliferación Celular , Factor 15 de Diferenciación de Crecimiento/metabolismo , Ratones , Ratones Noqueados , Modelos Biológicos , Transducción de SeñalRESUMEN
BACKGROUND: Successful treatment for acute myeloid leukemia (AML) remains challenging. Inhibiting immune checkpoint to enhance anti-tumor response is an attractive strategy for effective leukemia therapeutics. CD73 is a recently recognized immune checkpoint mediator that is highly expressed on tumor cells and stromal cells in tumor microenvironment. The ectonucleotidase activity of CD73 catalyzes AMP to adenosine, which subsequently inhibits anti-tumor immune responses. In this study, we aim to explore the effect of CD73 in AML. METHODS: Peripheral blood samples collected from patients with newly diagnosed AML (n = 27) were used in this study. CD73 expression on each immune cell component was examined by flow cytometry. Phenotypic study of CD73-expressing T cells and analysis of the correlation between CD73 and other immune checkpoints were performed using flow cytometry-based assays. Functional status of CD73+ vs. CD73- T cells was assessed in an in vitro cytokine release assay upon CD3/CD28 antibody stimulation. RESULTS: In contrast to the long recognized immune suppressive effect of CD73-adenosine signaling in tumor tissue, we made a striking observation that in AML, CD73 expression on CD8 T cells associates with an increased immune response. CD73+ CD8 T cells are more functional, whereas CD73- CD8 T cells exhibit features of exhaustion manifested by high expression of inhibitory receptors such as PD-1 and TIGIT, increased intracellular expression of Eomes, reduced capacity of cytokine production, and high susceptibility to apoptosis. CONCLUSIONS: Our data highlight the potential of CD73 as a double-edged sword in anti-leukemia immunity and argue strongly for the combinational treatment by adding immune checkpoint inhibitors to the CD73-targeting approaches.
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5'-Nucleotidasa/inmunología , Leucemia Mieloide Aguda/inmunología , Linfocitos T/inmunología , 5'-Nucleotidasa/genética , Adulto , Anciano , Anciano de 80 o más Años , Regulación hacia Abajo , Femenino , Proteínas Ligadas a GPI/genética , Proteínas Ligadas a GPI/inmunología , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Masculino , Persona de Mediana Edad , Linfocitos T/patología , TransfecciónRESUMEN
The considerable amount of experimental evidence has defined the Hippo pathway as a tumor suppressive pathway and increased expression and/or activity of its oncogenic effectors is frequently observed in cancer. However, clinical studies have failed to attribute cancer development and progression to mutations in the pathway. In explaining this conundrum, we investigated the expression and functions of a C-terminally truncated isoform of large tumor suppressor kinase 1 (LATS1) called short LATS1 (sLATS1) in human cell lines and Drosophila. Intriguingly, through overexpression of sLATS1, we demonstrated that sLATS1 either activates or suppresses the activity of Yes-associated protein (YAP), one of the effectors of the Hippo pathway, in a cell type-specific manner. The activation is mediated through inhibition of full-length LATS1, whereas suppression of YAP is accomplished through sLATS1-YAP interaction. In HEK293T cells, the former mechanism may affect the cellular response more dominantly, whereas in U2OS cells and developing tissues in Drosophila, the latter mechanism may be solely carried out. Finally, to find the clinical relevance of this molecule, we examined the expression of sLATS1 in breast cancer patients. The transcriptome analysis showed that the ratio of sLATS1 to LATS1 was increased in tumor tissues comparing to their adjacent normal tissues.
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Proteínas Adaptadoras Transductoras de Señales/metabolismo , Neoplasias de la Mama/metabolismo , Fosfoproteínas/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Western Blotting , Carcinogénesis/metabolismo , Técnicas de Cultivo de Célula , Fraccionamiento Celular , Proliferación Celular/genética , Drosophila , Proteínas de Drosophila/metabolismo , Femenino , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Células HEK293 , Vía de Señalización Hippo , Humanos , Inmunoprecipitación , Proteínas Nucleares/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Transducción de Señal , Transactivadores/metabolismo , Factores de Transcripción , Proteínas Señalizadoras YAPRESUMEN
Anemic stress induces a physiological response that includes the rapid production of new erythrocytes. This process is referred to as stress erythropoiesis. It is best understood in the mouse where it is extramedullary and utilizes signals and progenitor cells that are distinct from bone marrow steady-state erythropoiesis. The development of stress erythroid progenitors occurs in close association with the splenic stress erythropoiesis niche. In particular, macrophages in the niche are required for proper stress erythropoiesis. Here we show that the expansion of the niche occurs in concert with the proliferation and differentiation of stress erythroid progenitors. Using lineage tracing analysis in 2 models of anemic stress, we show that the expansion of the splenic niche is due to the recruitment of monocytes into the spleen, which develop into macrophages that form erythroblastic islands. The influx in monocytes into the spleen depends in part on Ccr2-dependent signaling mediated by Ccl2 and other ligands expressed by spleen resident red pulp macrophages. Overall, these data demonstrate the dynamic nature of the spleen niche, which rapidly expands in concert with the stress erythroid progenitors to coordinate the production of new erythrocytes in response to anemic stress.
Asunto(s)
Anemia/metabolismo , Eritropoyesis , Macrófagos/metabolismo , Monocitos/metabolismo , Transducción de Señal , Estrés Fisiológico , Anemia/genética , Anemia/patología , Animales , Quimiocina CCL2/genética , Modelos Animales de Enfermedad , Macrófagos/patología , Ratones , Ratones Noqueados , Monocitos/patologíaRESUMEN
Selenium (Se) is incorporated as the 21st amino acid selenocysteine (Sec) into the growing polypeptide chain of proteins involved in redox gatekeeper functions. Erythropoiesis presents a particular problem to redox regulation as the presence of iron, heme, and unpaired globin chains lead to high levels of free radical-mediated oxidative stress, which are detrimental to erythroid development and can lead to anemia. Under homeostatic conditions, bone marrow erythropoiesis produces sufficient erythrocytes to maintain homeostasis. In contrast, anemic stress induces an alternative pathway, stress erythropoiesis, which rapidly produces new erythrocytes at extramedullary sites, such as spleen, to alleviate anemia. Previous studies suggest that dietary Se protects erythrocytes from such oxidative damage and the absence of selenoproteins causes hemolysis of erythrocytes due to oxidative stress. Furthermore, Se deficiency or lack of selenoproteins severely impairs stress erythropoiesis exacerbating the anemia in rodent models and human patients. Interestingly, erythroid progenitors develop in close proximity with macrophages in structures referred to as erythroblastic islands (EBIs), where macrophage expression of selenoproteins appears to be critical for the expression of heme transporters to facilitate export of heme from macrophage stores to the developing erythroid cells. Here we review the role of Se and selenoproteins in the intrinsic development of erythroid cells in addition to their role in the development of the erythropoietic niche that supports the functional role of EBIs in erythroid expansion and maturation in the spleen during recovery from anemia.