Haematopoietic stem cells (HSCs) differ from their committed progeny by relying primarily on anaerobic glycolysis rather than mitochondrial oxidative phosphorylation for energy production. However, ...whether this change in the metabolic program is the cause or the consequence of the unique function of HSCs remains unknown. Here we show that enforced modulation of energy metabolism impacts HSC self-renewal. Lowering the mitochondrial activity of HSCs by chemically uncoupling the electron transport chain drives self-renewal under culture conditions that normally induce rapid differentiation. We demonstrate that this metabolic specification of HSC fate occurs through the reversible decrease of mitochondrial mass by autophagy. Our data thus reveal a causal relationship between mitochondrial metabolism and fate choice of HSCs and also provide a valuable tool to expand HSCs outside of their native bone marrow niches.
In recent years, immunotherapy has become the most promising therapy for a variety of cancer types. The development of immune checkpoint blockade (ICB) therapies, the adoptive transfer of ...tumor-specific T cells (adoptive cell therapy (ACT)) or the generation of T cells engineered with chimeric antigen receptors (CAR) have been successfully applied to elicit durable immunological responses in cancer patients. However, not all the patients respond to these therapies, leaving a consistent gap of therapeutic improvement that still needs to be filled. The innate immune components of the tumor microenvironment play a pivotal role in the activation and modulation of the adaptive immune response against the tumor. Indeed, several efforts are made to develop strategies aimed to harness innate immune cells in the context of cancer immunotherapy. In this review, we describe the contribution of innate immune cells in T-cell-based cancer immunotherapy and the therapeutic approaches implemented to broaden the efficacy of these therapies in cancer patients.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
It has been recently shown that increased oxidative phosphorylation, as reflected by increased mitochondrial activity, together with impairment of the mitochondrial stress response, can severely ...compromise hematopoietic stem cell (HSC) regeneration. Here we show that the NAD+-boosting agent nicotinamide riboside (NR) reduces mitochondrial activity within HSCs through increased mitochondrial clearance, leading to increased asymmetric HSC divisions. NR dietary supplementation results in a significantly enlarged pool of progenitors, without concurrent HSC exhaustion, improves survival by 80%, and accelerates blood recovery after murine lethal irradiation and limiting-HSC transplantation. In immune-deficient mice, NR increased the production of human leucocytes from hCD34+ progenitors. Our work demonstrates for the first time a positive effect of NAD+-boosting strategies on the most primitive blood stem cells, establishing a link between HSC mitochondrial stress, mitophagy, and stem-cell fate decision, and unveiling the potential of NR to improve recovery of patients suffering from hematological failure including post chemo- and radiotherapy.
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•Vitamin B3 analogs improve hematopoietic stem cell (HSC) and progenitor function•Nicotinamide riboside (NR) increases mitochondrial recycling in HSCs•In vitro NR exposure induces asymmetric mitochondrial distribution in dividing HSCs•NR dietary supplementation improves survival after HSC transplantation in mice
Naveiras and colleagues describe the effects of vitamin B3 derivatives in blood formation, of which they find nicotinamide riboside (NR) to most potently increase blood progenitors. Treating purified mouse or human blood stem cells with NR improved their mitochondrial quality and reduced the toxicity of bone marrow transplantation in mice.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
The capacity of T cells to identify and kill cancer cells has become a central pillar of immune-based cancer therapies. However, T cells are characterized by a dysfunctional state in most tumours. A ...major obstacle for proper T-cell function is the metabolic constraints posed by the tumour microenvironment (TME). In the TME, T cells compete with cancer cells for macronutrients (sugar, proteins, and lipid) and micronutrients (vitamins and minerals/ions). While the role of macronutrients in T-cell activation and function is well characterized, the contribution of micronutrients and especially ions in anti-tumour T-cell activities is still under investigation. Notably, ions are important for most of the signalling pathways regulating T-cell anti-tumour function. In this review, we discuss the role of six biologically relevant ions in T-cell function and in anti-tumour immunity, elucidating potential strategies to adopt to improve immunotherapy via modulation of ion metabolism.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The in vitro expansion of long-term hematopoietic stem cells (HSCs) remains a substantial challenge, largely because of our limited understanding of the mechanisms that control HSC fate choices. ...Using single-cell multigene expression analysis and time-lapse microscopy, here we define gene expression signatures and cell cycle hallmarks of murine HSCs and the earliest multipotent progenitors (MPPs), and analyze systematically single HSC fate choices in culture. Our analysis revealed twelve differentially expressed genes marking the quiescent HSC state, including four genes encoding cell-cell interaction signals in the niche. Under basal culture conditions, most HSCs rapidly commit to become early MPPs. In contrast, when we present ligands of the identified niche components such as JamC or Esam within artificial niches, HSC cycling is reduced and long-term multipotency in vivo is maintained. Our approach to bioengineer artificial niches should be useful in other stem cell systems.Haematopoietic stem cell (HSC) self-renewal is not sufficiently understood to recapitulate in vitro. Here, the authors generate gene signature and cell cycle hallmarks of single murine HSCs, and use identified endothelial receptors Esam and JamC as substrates to enhance HSC growth in engineered niches.
T cell activation is dependent upon the integration of antigenic, co-stimulatory and cytokine-derived signals and the availability and acquisition of nutrients from the environment. Furthermore, T ...cell activation is accompanied by reprogramming of cellular metabolism to provide the energy and building blocks for proliferation, differentiation and effector function. Transforming growth factor β (TGFβ) has pleiotropic effects on T cell populations, having both an essential role in the maintenance of immune tolerance but also context-dependent pro-inflammatory functions. We set out to define the mechanisms underpinning the suppressive effects of TGFβ on mouse CD8
T cell activation. RNA-sequencing analysis of TCR-stimulated T cells determined that Myc-regulated genes were highly enriched within gene sets downregulated by TGFβ. Functional analysis demonstrated that TGFβ impeded TCR-induced upregulation of amino acid transporter expression, amino acid uptake and protein synthesis. Furthermore, TCR-induced upregulation of Myc-dependent glycolytic metabolism was substantially inhibited by TGFβ treatment with minimal effects on mitochondrial respiration. Thus, our data suggest that inhibition of Myc-dependent metabolic reprogramming represents a major mechanism underpinning the suppressive effects of TGFβ on CD8
T cell activation.
Despite the tremendous success of adoptive T-cell therapies (ACT) in fighting certain hematologic malignancies, not all patients respond, a proportion experience relapse, and effective ACT of most ...solid tumors remains elusive. In order to improve responses to ACT suppressive barriers in the solid tumor microenvironment (TME) including insufficient nutrient availability must be overcome. Here we explored how enforced expression of the high-affinity glucose transporter GLUT3 impacted tumor-directed T cells. Overexpression of GLUT3 in primary murine CD8
+
T cells enhanced glucose uptake and increased glycogen and fatty acid storage, and was associated with increased mitochondrial fitness, reduced ROS levels, higher abundance of the anti-apoptotic protein Mcl-1, and better resistance to stress. Importantly, GLUT3-OT1 T cells conferred superior control of B16-OVA melanoma tumors and, in this same model, significantly improved survival. Moreover, a proportion of treated mice were cured and protected from re-challenge, indicative of long-term T cell persistence and memory formation. Enforcing expression of GLUT3 is thus a promising strategy to improve metabolic fitness and sustaining CD8
+
T cell effector function in the context of ACT.
Steady hematopoiesis is essential for lifelong production of all mature blood cells. Hematopoietic stem and progenitor cells (HSPCs) found in the bone marrow ensure hematopoietic homeostasis in an ...organism. Failure of this complex process, which involves a fine balance of self-renewal and differentiation fates, often result in severe hematological conditions such as leukemia and lymphoma. Several molecular and metabolic programs, internal or in close interaction with the bone marrow niche, have been identified as important regulators of HSPC function. More recently, nutrient sensing pathways have emerged as important modulators of HSC homing, dormancy, and function in the bone marrow. Here we describe a method for reliable measurement of various amino acids and minerals in different rare bone marrow (BM) populations, namely HSPCs. We found that the amino acid profile of the most primitive hematopoietic compartments (KLS) did not differ significantly from the one of their direct progenies (common myeloid progenitor CMP), while granulocyte-monocyte progenitors (GMPs), on the opposite of megakaryocyte-erythroid progenitors (MEPs), have higher content of the majority of amino acids analyzed. Additionally, we identified intermediates of the urea cycle to be differentially expressed in the KLS population and were found to lower mitochondrial membrane potential, an established readout on self-renewal capability. Moreover, we were able to profile for the first time 12 different minerals and detect differences in elemental contents between different HSPC compartments. Importantly, essential dietary trace elements, such as iron and molybdenum, were found to be enriched in granulocyte-monocyte progenitors (GMPs). We envision this amino acid and mineral profiling will allow identification of novel metabolic and nutrient sensing pathways important in HSPC fate regulation.
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BackgroundCD8+ T cells are vital for their protective roles against pathogens and cancer. Aging and cancer are known to promote defecst in the quality and quantity of functional naïve T cells thus ...lowering immune surveillance. Interventions aimed to improve and to sustain the quality of naïve T cells are needed for cancer immunoprevention. We recently showed that the mitochondrial modulator mitophagy inducer Urolithin-A (UroA) improves immune system function by ameliorating the mitochondrial pool in Hematopoietic Stem Cells (HSCs).1 However, the direct contribution of UroA on the homeostasis and functionality of CD8+ T cells has not been investigated.MethodsWe adopted in vitro assays and in vivo tumor models to investigate the contribution of UroA in improving CD8+T quality and functionality.ResultsOur current study demonstrates that orally supplemented UroA reduces tumor progression in mice in a CD8+ T-cell dependent manner. We show that preexposure to UroA enriched diet is sufficient to induce a robust antitumor response identifying UroA as an immunosurveillance agent. Notably, UroA supplementation promotes expansion of naïve CD8+ T cells in vivo. Furthermore, UroA improves cytokine production, mitochondrial activity in CD8+ T cells and promotes memory differentiation in vitro. Interestingly, we reveal the transcription factor FOXO1 as a non-mitochondrial target of UroA in CD8+ T indicating a novel mitophagy-independent UroA mode of action. Furthermore, we have optimized dosage and timing of UroA supplementation in vitro for long expansion of CD8+T cells with a superior anti-tumor in the context of adoptive T cell therapy (ACT).ConclusionsOverall, our finding provide preclinical evidence supporting the therapeutic function of UroA as novel immunomodulator to improve immunosurveillance.ReferenceMukul Girotra, Yi-Hsuan Chiang, Melanie Charmoy, Pierpaolo Ginefra, Helen Carrasco Hope, Charles Bataclan, Yi-Ru Yu, Frederica Schyrr, Fabien Franco, Hartmut Geiger, Stephane Cherix, Ping-Chih Ho, Olaia Naveiras, Johan Auwerx, Werner Held, Nicola Vannini. Nature Aging.
BackgroundCAR-T cell therapy has emerged as a key strategy for cancer treatment. The success of CD19-directed CAR-T cells on haematological malignancies has generated a wide interest in the expansion ...of this approach to solid tumors. However, the clinical outcomes in this context have been unexpectedly poor due to both extrinsic and intrinsic suppressive factors that drive T cell dysfunction within the tumor microenvironment. A fundamental characteristic that contributes to anti-tumor T cell functionality and that determines CAR-T cell efficacy is the maintenance of mitochondrial fitness, which has been shown to sustain memory/stem-like properties and provide prolonged T cell responses. However, mitochondrial dysfunction is a hallmark of aging. How age-associated alterations of immune metabolism affect the outcome of CAR-T cell therapy remains poorly understood.MethodsHere we generate Her2-directed CAR-T cells from young and old mice. We combined in vitro assays with an in vivo Her2-expressing B16 tumour model to investigate the metabolism and functionality of CAR-T cells. Additionally, we validate our findings using human CD19 CAR-T cells from young (<30yo) and old (>70yo) donors.ResultsHere, we show that CAR-T cells from old mice display remarkable defects in mitochondrial activity and mass. Furthermore, aged CAR-T cells are unable to reach an appropriate stem-like phenotype, as shown by a lower proportion of CD44+CD62L+TCF1+ CAR-T cells. As a result, aged CAR-T cells are unable to survive in vivo and control tumor growth upon adoptive cell transfer. We unveil that aged CAR-T cells decrease NAD levels which we link to the upregulation of CD38, a cell membrane protein with NADase properties. We further observe that aged CAR-T are not able to respond to NAD boosters and, importantly, that higher CD38 levels are associated with lower mitochondrial activity. Indeed, blockade of CD38 activity using the small molecule 78c restores NAD levels and mitochondrial function when administered in combination with NAD boosters. In vivo, our combination treatment (CD38i + NAD-booster) restores functionality of aged CAR-T cells, promoting long-term CAR-T cell survival and controlling tumor growth as its younger counterparts. Furthermore, we show that also CAR-T cells generated from old human donors display an impaired mitochondrial fitness, which is rescued upon treatment with CD38i + NAD-booster.ConclusionsOur work proposes a model where the age-associated upregulation of CD38 drives NAD decline and mitochondrial dysfunction in CAR-T leading to limited acquisition of memory/stem-like characteristics. We identify CD38 as a promising target to restore stem-like properties of CAR-T cells.
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