bims-imseme Biomed News
on Immunosenescence and T cell metabolism
Issue of 2022‒06‒12
ten papers selected by
Pierpaolo Ginefra
Ludwig Institute for Cancer Research

  1. J Immunol. 2022 Jun 06. pii: ji2101090. [Epub ahead of print]
      CD8+ T cell proliferation and differentiation into effector and memory states are high-energy processes associated with changes in cellular metabolism. CD28-mediated costimulation of T cells activates the PI3K/AKT/mammalian target of rapamycin signaling pathway and induces eukaryotic translation initiation factor 4E-dependent translation through the derepression by 4E-BP1 and 4E-BP2. In this study, we demonstrate that 4E-BP1/2 proteins are required for optimum proliferation of mouse CD8+ T cells and the development of an antiviral effector function. We show that translation of genes encoding mitochondrial biogenesis is impaired in T cells derived from 4E-BP1/2-deficient mice. Our findings demonstrate an unanticipated role for 4E-BPs in regulating a metabolic program that is required for cell growth and biosynthesis during the early stages of CD8+ T cell expansion.
  2. Int J Mol Sci. 2022 May 26. pii: 5970. [Epub ahead of print]23(11):
      Accelerated glycolysis leads to secretion and accumulation of lactate and protons in the tumor environment and determines the efficacy of adoptive T cell and checkpoint inhibition therapy. Here, we analyzed effects of lactic acid on different human CD4 T cell subsets and aimed to increase CD4 T cell resistance towards lactic acid. In all CD4 T cell subsets analyzed, lactic acid inhibited metabolic activity (glycolysis and respiration), cytokine secretion, and cell proliferation. Overexpression of the lactate-metabolizing isoenzyme LDHB increased cell respiration and mitigated lactic acid effects on intracellular cytokine production. Strikingly, LDHB-overexpressing cells preferentially migrated into HCT116 tumor spheroids and displayed higher expression of cytotoxic effector molecules. We conclude, that LDHB overexpression might be a promising strategy to increase the efficacy of adoptive T cell transfer therapy.
    Keywords:  LDH; T cell metabolism; T cells; adoptive cell transfer; glycolysis; interferon gamma; lactate; lactic acid
  3. J Cell Biol. 2022 Jul 04. pii: e202203095. [Epub ahead of print]221(7):
      Fbxo7 is associated with cancer and Parkinson's disease. Although Fbxo7 recruits substrates for SCF-type ubiquitin ligases, it also promotes Cdk6 activation in a ligase-independent fashion. We discovered PFKP, the gatekeeper of glycolysis, in a screen for Fbxo7 substrates. PFKP is an essential Cdk6 substrate in some T-ALL cells. We investigated the molecular relationship between Fbxo7, Cdk6, and PFKP, and the effect of Fbxo7 on T cell metabolism, viability, and activation. Fbxo7 promotes Cdk6-independent ubiquitination and Cdk6-dependent phosphorylation of PFKP. Importantly, Fbxo7-deficient cells have reduced Cdk6 activity, and hematopoietic and lymphocytic cells show high expression and significant dependency on Fbxo7. CD4+ T cells with reduced Fbxo7 show increased glycolysis, despite lower cell viability and activation levels. Metabolomic studies of activated CD4+ T cells confirm increased glycolytic flux in Fbxo7-deficient cells, alongside altered nucleotide biosynthesis and arginine metabolism. We show Fbxo7 expression is glucose-responsive at the mRNA and protein level and propose Fbxo7 inhibits PFKP and glycolysis via its activation of Cdk6.
  4. Cell Rep Med. 2022 Jun 03. pii: S2666-3791(22)00187-2. [Epub ahead of print] 100655
      Tumor escape mechanisms for immunotherapy include deficiencies in antigen presentation, diminishing adaptive CD8+ T cell antitumor activity. Although innate natural killer (NK) cells are triggered by loss of MHC class I, their response is often inadequate. To increase tumor susceptibility to both innate and adaptive immune elimination, we performed parallel genome-wide CRISPR-Cas9 knockout screens under NK and CD8+ T cell pressure. We identify all components, RNF31, RBCK1, and SHARPIN, of the linear ubiquitination chain assembly complex (LUBAC). Genetic and pharmacologic ablation of RNF31, an E3 ubiquitin ligase, strongly sensitizes cancer cells to NK and CD8+ T cell killing. This occurs in a tumor necrosis factor (TNF)-dependent manner, causing loss of A20 and non-canonical IKK complexes from TNF receptor complex I. A small-molecule RNF31 inhibitor sensitizes colon carcinoma organoids to TNF and greatly enhances bystander killing of MHC antigen-deficient tumor cells. These results merit exploration of RNF31 inhibition as a clinical pharmacological opportunity for immunotherapy-refractory cancers.
    Keywords:  NK cells; T cells; bystander killing; function-based genome-wide screens; immunotherapy resistance
  5. Nat Commun. 2022 Jun 03. 13(1): 3111
      Cytotoxic T cells are important components of natural anti-tumor immunity and are harnessed in tumor immunotherapies. Immune responses to tumors and immune therapy outcomes largely vary among individuals, but very few studies examine the contribution of intrinsic behavior of the T cells to this heterogeneity. Here we show the development of a microfluidic-based in vitro method to track the outcome of antigen-specific T cell activity on many individual cancer spheroids simultaneously at high spatiotemporal resolution, which we call Multiscale Immuno-Oncology on-Chip System (MIOCS). By combining parallel measurements of T cell behaviors and tumor fates with probabilistic modeling, we establish that the first recruited T cells initiate a positive feedback loop to accelerate further recruitment to the spheroid. We also provide evidence that cooperation between T cells on the spheroid during the killing phase facilitates tumor destruction. Thus, we propose that both T cell accumulation and killing function rely on collective behaviors rather than simply reflecting the sum of individual T cell activities, and the possibility to track many replicates of immune cell-tumor interactions with the level of detail our system provides may contribute to our understanding of immune response heterogeneity.
  6. Br J Haematol. 2022 Jun 08.
      Immune thrombocytopenia (ITP) is an acquired autoimmune disease, in which the imbalance of CD4+ T cell subsets play a key role in the pathogenesis. Since T cells highly depend on metabolism for their function, we hypothesized that T cell dysfunction may be due to intracellular metabolic reprogramming. We found that in ITP, T cell metabolism shifts from oxidative phosphorylation to glycolysis. Empagliflozin, a sodium-glucose cotransporter 2 inhibitor, has shown regulatory metabolic effects on proximal tubular epithelial cells and cardiac cells beyond glucose lowering. However, the effects of empagliflozin on T cells remain unknown. To further investigate the metabolic dysfunction of CD4+ T cells in ITP, we explored the effect of empagliflozin on CD4+ T-cell differentiation in ITP. Our results are the first to show that increased glycolysis in CD4+ T cells resulted in an unbalanced CD4+ T-cell population. Furthermore, empagliflozin can affect the differentiation of CD4+ T-cell subsets by inhibiting Th1 and Th17 cell populations while increasing Tregs. Empagliflozin appears to regulate CD4+ T cells through inhibiting the mTOR signal pathway. Considering these results, we propose that empagliflozin could be used as a potential therapeutic option for ITP by modulating metabolic reprogramming in CD4+ T cells.
    Keywords:  SGLT2 inhibitor; T subsets; glycolysis; immune thrombocytopenia; oxidative phosphorylation
  7. J Cell Sci. 2022 Jun 06. pii: jcs.259481. [Epub ahead of print]
      We investigated the role of telomerase and telomere repeat binding factor 2 (TRF2) in T cell dysfunction in chronic viral infection. We found that the expression and activity of telomerase in CD4 T cells from HCV patients or people living with HIV (PLWH) are intact, but TRF2 expression is significantly inhibited at the post-transcriptional level, suggesting that TRF2 inhibition is responsible for the CD4 T cell dysfunction observed during chronic viral infection. Silencing TRF2 expression in healthy CD4 T cells induced telomeric DNA damage and CD4 T cell dysfunction without affecting telomerase activity or translocation - similar to what we observed in CD4 T cells from HCV patients and PLWH. These findings indicate that premature T cell aging and dysfunction during chronic HCV or HIV infection are primarily caused by chronic immune stimulation and T cell over-activation/proliferation that induce telomeric DNA damage due to TRF2 inhibition, rather than telomerase disruption. This study suggests that restoring TRF2 may provide a novel approach to prevent telomeric DNA damage and premature T cell aging, thus rejuvenating T cell functions during chronic viral infection.
    Keywords:  CD4 T cell dysfunction; DNA damage; HCV; HIV; Telomere erosion
  8. STAR Protoc. 2022 Jun 17. 3(2): 101441
      Studying the metabolic fitness of T cells is fundamental to understand how immune responses are regulated. Here, we describe a step-by-step protocol optimized to efficiently generate and isolate effector antigen-specific CD8+ T cells ex vivo using costimulation. We also detail steps to evaluate their metabolic activity using Seahorse technology. This protocol can be used to measure the glycolytic potential of effector murine T cells in response to different manipulations, such as infections, adjuvant studies, gene editing, or metabolite supplementation. For complete details on the use and execution of this protocol, please refer to Agliano et al. (2022).
    Keywords:  Cell Biology; Cell isolation; Cell-based Assays; Flow Cytometry/Mass Cytometry; Immunology; Metabolism
  9. Nat Cell Biol. 2022 Jun 06.
      Mitochondrial metabolites regulate leukaemic and normal stem cells by affecting epigenetic marks. How mitochondrial enzymes localize to the nucleus to control stem cell function is less understood. We discovered that the mitochondrial metabolic enzyme hexokinase 2 (HK2) localizes to the nucleus in leukaemic and normal haematopoietic stem cells. Overexpression of nuclear HK2 increases leukaemic stem cell properties and decreases differentiation, whereas selective nuclear HK2 knockdown promotes differentiation and decreases stem cell function. Nuclear HK2 localization is phosphorylation-dependent, requires active import and export, and regulates differentiation independently of its enzymatic activity. HK2 interacts with nuclear proteins regulating chromatin openness, increasing chromatin accessibilities at leukaemic stem cell-positive signature and DNA-repair sites. Nuclear HK2 overexpression decreases double-strand breaks and confers chemoresistance, which may contribute to the mechanism by which leukaemic stem cells resist DNA-damaging agents. Thus, we describe a non-canonical mechanism by which mitochondrial enzymes influence stem cell function independently of their metabolic function.
  10. Nat Commun. 2022 Jun 07. 13(1): 3156
      Many vital processes in the eye are under circadian regulation, and circadian dysfunction has emerged as a potential driver of eye aging. Dietary restriction is one of the most robust lifespan-extending therapies and amplifies circadian rhythms with age. Herein, we demonstrate that dietary restriction extends lifespan in Drosophila melanogaster by promoting circadian homeostatic processes that protect the visual system from age- and light-associated damage. Altering the positive limb core molecular clock transcription factor, CLOCK, or CLOCK-output genes, accelerates visual senescence, induces a systemic immune response, and shortens lifespan. Flies subjected to dietary restriction are protected from the lifespan-shortening effects of photoreceptor activation. Inversely, photoreceptor inactivation, achieved via mutating rhodopsin or housing flies in constant darkness, primarily extends the lifespan of flies reared on a high-nutrient diet. Our findings establish the eye as a diet-sensitive modulator of lifespan and indicates that vision is an antagonistically pleiotropic process that contributes to organismal aging.