ABSTRACT: Short-term hypoxia synergizes with interleukin 15 priming in driving glycolytic gene transcription and supports human natural killer cell activities.
Project description:Natural killer (NK) cells induce apoptosis in infected and transformed cells and produce immunoregulatory cytokines. At this, NK cells operate in inflammatory and tumor environments low in oxygen (hypoxic) and with immunosuppressive properties. In vitro studies of NK cells are, however, commonly performed in ambient air (normoxia). We evaluated the immediate impact of short-term hypoxia on various intrinsic activities of resting and IL-15 primed NK cells and determined underlying transcriptional pathway regulations using a 2 × 2 factorial design. Hypoxia stimulated migration through extracellular matrix, supported secretion of specific chemokines, and shifted amounts of susceptible leukemia target cells toward late apoptosis. IL-15 was a powerful inducer of anabolic gene transcription. Associations of hypoxia with HIF-1 and glycolytic pathways were dependent on priming which represented the largest contrasts observed. Regulatory patterns and RT-PCR validated synergistic hypoxia-IL-15 interactions in upregulation of key glycolytic enzymes suggest an important function for anaerobic glycolysis in priming, underpinning the emerging role of glycolytic switching in driving NK cell function. Adaption to short-term hypoxia appeared however transitory. We conclude that control of oxygen in vitro can promote NK cell features desirable for adoptive transfer therapy.
Project description:This is a mathematical model comprised of non-linear ordinary differential equations describing the dynamic relationship between hypoxia-inducible factor-1 alpha (HIF-1a) mRNA, HIF-1a protein, and interleukin-15-mediated upstream signalling events in natural killer cells from human blood. Regulatory expressions are also included for mammalian target of rapamycin (mTOR), nuclear factor-kappa beta, and signal transducer and activator of transcription 3 (STAT3).
Project description:Environmental hypoxia typically induces phenotypic remodelling in animals, including bolstered oxygen transport and storage, and glycolytic enzyme activities, typically coordinated by the transcription factor hypoxia-inducible factor (HIF). The calanoid copepod Daphnia responds to hypoxia by a HIF-dependent increase in expression of extracellular hemoglobin (Hb), however little is known about the glycolytic response. We compared the Daphnia from 4 lakes in terms of transcriptome using RNASeq analysis of red versus pale animals. Cluster analysis showed that the impact of lake was much greater than the impact of colour. However, in each lake there were a series of colour dependent differences, including many of the known targets of HIF in mammals.
Project description:High altitude conditions improve glucose tolerance and reduce diabetes risk, but the physiological mechanism is not well-understood. Using mouse models, we found that hypoxia alone robustly improved glucose tolerance and that the effect persisted for weeks after returning to normal oxygen levels. PET/CT imaging suggested a significant, unknown glucose sink beyond major internal organs. We hypothesized that hypoxia-induced red blood cells (RBCs) serve as this sink. Manipulating RBC numbers through phlebotomy or transfusion directly altered blood glucose, establishing RBCs as necessary and sufficient for this effect. In chronic hypoxia, RBCs showed a sustained ~3-fold increase in glucose uptake and ~2-fold increase in GLUT1 protein abundance, specifically in newly synthesized RBCs, which ultimately contributes to increased glycolytic flux towards 2,3-DPG. Mechanistically, acute hypoxia promotes displacement of GAPDH from inhibitory Band 3 binding through competitive interactions with deoxyhemoglobin, thereby boosting glycolytic flux and driving 2,3-DPG production. We also found that hypoxia or our small molecule hypoxia-mimetic, HypoxyStat, rescued hyperglycemia in mouse models of type 1 and type 2 diabetes. Our findings identify RBCs as key regulators of systemic glucose metabolism, highlighting a novel therapeutic approach for hyperglycemic disorders.
Project description:Upon antigen stimulation, the bioenergetic demands of T cells increase dramatically over the resting state. Although a role for the metabolic switch to glycolysis has been suggested to support increased anabolic activities and facilitate T cell growth and proliferation, whether cellular metabolism controls T cell lineage choices remains poorly understood. Here we report that the glycolytic pathway is actively regulated during the differentiation of inflammatory TH17 and Foxp3-expressing regulatory T cells (Treg), and controls cell fate determination. TH17 but not Treg-inducing conditions resulted in strong upregulation of the glycolytic activity and induction of glycolytic enzymes. Blocking glycolysis inhibited TH17 development while promoting Treg cell generation. Moreover, the transcription factor hypoxia-inducible factor 1a (HIF1a) was selectively expressed in TH17 cells and its induction required signaling through mTOR, a central regulator of cellular metabolism. HIF1a-dependent transcriptional program was important for mediating glycolytic activity, thereby contributing to the lineage choices between TH17 and Treg cells. Lack of HIF1a resulted in diminished TH17 development but enhanced Treg differentiation, and protected mice from autoimmune CNS inflammation. Our studies demonstrate that HIF1a-dependent glycolytic pathway orchestrates a metabolic checkpoint for the differentiation of TH17 and Treg cells. Naïve CD4 T cells from wild-type and HIF1a-deficient mice (in triplicates each group) were differentiated under TH17 conditions for 2.5 days, and RNA was analyzed by microarrays.
Project description:Antibodies targeting “immune checkpoints” have revolutionized cancer therapy by reactivating tumor-resident cytotoxic lymphocytes, primarily CD8 T cells. Interest in targeting analogous pathways in other cytotoxic lymphocytes is growing. Natural killer (NK) cells are key to cancer immunosurveillance by eradicating metastases and driving solid tumor inflammation. NK cell anti-tumor function is dependent on the cytokine interleukin (IL)-15. Ablation of the IL-15 signaling inhibitor CIS (Cish) enhances NK cell anti-tumor immunity by increasing NK cell metabolism and persistence within the tumor microenvironment (TME). The TME has also been shown to impair NK cell fitness via the production of immunosuppressive TGF-b, a suppression which occurs even in the presence of high IL-15 signaling. Here, we identified an unexpected interaction between CIS and the TGF-b signaling pathway in NK cells. Independently, Cish- and Tgfbr2- deficient NK cells are both hyper-responsive to IL-15 and hypo-responsive to TGF-b, with dramatically enhanced anti-tumor immunity. Remarkably, when both these immunosuppressive genes are simultaneously deleted in NK cells, mice are largely resistant to tumor development, suggesting that combining suppression of these two pathways might represent a novel therapeutic strategy to enhance innate anti-cancer immunity.
Project description:Natural Killer (NK) cells, integral to viral immunity and tumor clearance, are impacted by metabolism. A prior study revealed that cytokine stimulation boosts the citrate-malate shuttle and cytosolic acetyl-CoA through ATP citrate lyase (ACLY) in NK cells. Acetyl-CoA is vital for fatty acid synthesis and protein acetylation, including histones. To explore the role of ACLY in NK cell function, we generated an inducible NK-specific Acly knockout mouse model. ACLY loss in NKp46+ NK cells did not alter maturation or IFN-γ production in naïve NK cells. However, ACLY-deficient NK cells exhibited notable proliferation defects in IL-15-priming conditions, associated with impaired glycolysis. The stimulation and priming of NK cells through IL-15 is an important mechanism for enhancing effector and anti-tumor functions. Additionally, IL-15-primed ACLY-deficient NK cells showed reduced effector function in response to DAP12-associated activating receptors (NKG2D, Ly49H). This is because ACLY-deficient NK cells produce lower level of DAP12 during IL-15 priming, which was regulated in epigenetic level. These ACLY-driven deficiency was mostly rescued by acetate-generated acetyl-CoA, except glycolysis. Overall, these findings underscore ACLY's importance in NK cell proliferation and DAP12-driven effector functions.
Project description:Natural Killer (NK) cells, integral to viral immunity and tumor clearance, are impacted by metabolism. A prior study revealed that cytokine stimulation boosts the citrate-malate shuttle and cytosolic acetyl-CoA through ATP citrate lyase (ACLY) in NK cells. Acetyl-CoA is vital for fatty acid synthesis and protein acetylation, including histones. To explore the role of ACLY in NK cell function, we generated an inducible NK-specific Acly knockout mouse model. ACLY loss in NKp46+ NK cells did not alter maturation or IFN-γ production in naïve NK cells. However, ACLY-deficient NK cells exhibited notable proliferation defects in IL-15-priming conditions, associated with impaired glycolysis. The stimulation and priming of NK cells through IL-15 is an important mechanism for enhancing effector and anti-tumor functions. Additionally, IL-15-primed ACLY-deficient NK cells showed reduced effector function in response to DAP12-associated activating receptors (NKG2D, Ly49H). This is because ACLY-deficient NK cells produce lower level of DAP12 during IL-15 priming, which was regulated in epigenetic level. These ACLY-driven deficiency was mostly rescued by acetate-generated acetyl-CoA, except glycolysis. Overall, these findings underscore ACLY's importance in NK cell proliferation and DAP12-driven effector functions.