Project description:Neonates often generate incomplete immunity against intracellular pathogens, although the mechanism of this defect is poorly understood. An important question is whether the impaired development of memory CD8+ T cells in neonates is due to an immature priming environment or lymphocyte-intrinsic defects. Here we show that neonatal and adult CD8+ T cells adopted different fates when responding to equal amounts of stimulation in the same host. While adult CD8+ T cells differentiated into a heterogeneous pool of effector and memory cells, neonatal CD8+ T cells preferentially gave rise to short-lived effector cells and exhibited a distinct gene expression profile. Surprisingly, impaired neonatal memory formation was not due to a lack of responsiveness, but instead because neonatal CD8+ T cells expanded more rapidly than adult cells and quickly became terminally differentiated. Collectively, these findings demonstrate that neonatal CD8+ T cells exhibit an imbalance in effector and memory CD8+ T cell differentiation, which impairs the formation of memory CD8+ T cells in early life mRNA profiles of effector CD8+ T cells from neonatal and adult mice
Project description:Neonates often generate incomplete immunity against intracellular pathogens, although the mechanism of this defect is poorly understood. An important question is whether the impaired development of memory CD8+ T cells in neonates is due to an immature priming environment or lymphocyte-intrinsic defects. Here we show that neonatal and adult CD8+ T cells adopted different fates when responding to equal amounts of stimulation in the same host. While adult CD8+ T cells differentiated into a heterogeneous pool of effector and memory cells, neonatal CD8+ T cells preferentially gave rise to short-lived effector cells and exhibited a distinct gene expression profile. Surprisingly, impaired neonatal memory formation was not due to a lack of responsiveness, but instead because neonatal CD8+ T cells expanded more rapidly than adult cells and quickly became terminally differentiated. Collectively, these findings demonstrate that neonatal CD8+ T cells exhibit an imbalance in effector and memory CD8+ T cell differentiation, which impairs the formation of memory CD8+ T cells in early life
Project description:Using killer cell lectin-like receptor G1 as a marker to distinguish terminal effector cells from memory precursors, we found that despite their diverse cell fates both subsets possessed remarkably similar gene expression profiles and functioned as equally potent killer cells. However, only the memory precursors were capable of making IL-2 thus defining a novel effector cell that was cytotoxic, expressed granzyme B, and produced inflammatory cytokines in addition to IL-2. This effector population then differentiated into long-lived protective memory T cells capable of self-renewal and rapid re-call responses. Mechanistic studies showed that cells that continued to receive antigenic stimulation during the later stages of infection were more likely to become terminal effectors. Importantly, curtailing antigenic stimulation towards the tail-end of the acute infection enhanced the generation of memory cells. These studies support the decreasing potential model of memory differentiation and show that the duration of antigenic stimulation is a critical regulator of memory formation Experiment Overall Design: An important question in memory development is understanding the differences between effector CD8 T cells that die versus effector cells that survive and give rise to memory cells. In this study we provide a comprehensive phenotypic, functional and genomic profiling of terminal effectors and memory precursors, towards better understanding the generation of these subsets. The two effector subsets were FACS purified during the early expansion phase (Days 4-5 post-infection) and extensively analyzed for their phenotypic (eg. CD127, CD62L, CD27, Bcl-2, Granzyme B, etc.) and functional properties (cytokine production, cytotoxicity, homeostatic proliferation, recall proliferation), and gene expression profiles (by genome-wide microarray analyses). Mechanistic studies involving the extent of proliferation and duration of antigen stimulation on memory differentiation potential of effectors were also performed using adoptive transfer techniques.
Project description:T cells receive numerous positive and negative signals during primary antigen encounter that control their proliferation and function, but how these signals are integrated to modulate T cell memory has not been fully characterized. In these studies, we demonstrate that combining seemingly opposite signals, CTLA-4 blockade and rapamycin-mediated mTOR inhibition, during in vivo T cell priming leads to both an increase in the frequency of memory CD8+ T cells and improved memory responses to tumors and bacterial challenges. This enhanced efficacy corresponds to increased early expansion and memory precursor differentiation of CD8+ T cells and increased mitochondrial biogenesis and spare respiratory capacity in memory CD8+ T cells in mice treated with anti-CTLA-4 and rapamycin during immunization. Collectively, these results reveal that mTOR inhibition cooperates with rather than antagonizes blockade of CTLA-4, promoting unrestrained effector function and proliferation and an optimal metabolic program for CD8+ T cell memory. Total RNA was isolated from FACS-sorted, antigen-specific CD8+T cells from different treatment conditions at 5 or 35 days after primary T cell activation
Project description:The mammalian gastrointestinal tract contains a diverse ecosystem of microbial species collectively making up the gut microbiome. Emerging evidence highlights a critical relationship between gut microbiota and neurocognitive development. Consumption of unhealthy yet palatable dietary factors associated with obesity and metabolic dysfunction (e.g., saturated fat, added sugar) produces microbiota dysbiosis and negatively impacts neurocognitive function, particularly when consumed during early life developmental periods. Here we explore whether excessive early life consumption of added sugars negatively impacts neurocognitive development via the gut microbiome. Using a rodent model of habitual sugar-sweetened beverage (SSB) consumption during the adolescent stage of development, we first show that excessive early life sugar intake impairs hippocampal-dependent memory function when tested during adulthood while preserving other neurocognitive domains. Gut microbiome genomic sequencing analyses reveal that early life SSB consumption alters the abundance of various bacterial populations, including elevations in operational taxonomic units within the genus Parabacteroides (P. distasonis and P. johnsonii) whose abundance negatively correlated with memory task performance. Additional results reveal that in vivo Parabacteroides enrichment of cultured P. distasonis and P. johnsonii bacterial species in adolescent rats severely impairs memory function during adulthood. Hippocampus transcriptome analyses identify gene expression alterations in neurotransmitter synaptic signaling, intracellular kinase signaling, metabolic function, neurodegenerative disease, and dopaminergic synaptic signaling-associated pathways as potential mechanisms linking microbiome outcomes with memory impairment. Collectively these results identify microbiota dysbiosis as a mechanism through which early life unhealthy dietary patterns negatively impact neurocognitive outcomes.
Project description:DNMT3a is a de novo DNA methyltransferase expressed robustly after T cell activation that regulates plasticity of CD4+ T cell cytokine expression. Here we show that DNMT3a is critical for directing early CD8+ T cell effector and memory fate decisions. While effector function of DNMT3a knockout T cells is normal, they develop more memory precursor and fewer terminal effector cells in a T cell intrinsic manner compared to wild-type animals. Rather than increasing plasticity of differentiated effector CD8+ T cells, loss of DNMT3a biases differentiation of early effector cells into memory precursor cells. This is attributed in part to ineffective repression of Tcf1 expression in knockout T cells, as DNMT3a localizes to the Tcf7 promoter and catalyzes its de novo methylation in early effector WT CD8+ T cells. This data identifies DNMT3a as a crucial regulator of CD8+ early effector cell differentiation and effector versus memory fate decisions. Examination of global genomic DNA methylation by MBD-seq in naïve CD8 T cells and CD8 T cells 8 days post Vaccinia-Ova infection, comparing OT1 TCR-Tg CD8 T cells isolated from WT and T cell conditional DNMT3a KO mice.
Project description:CD8+ T cells play a crucial role in the clearance of intracellular pathogens through the generation of cytotoxic effector cells that eliminate infected cells and long-lived memory cells that provide enhanced protection against reinfection. We have previously shown that the inhibitor of E protein transcription factors, Id2, is necessary for accumulation of effector and memory CD8+ T cells during infection. Here we show that CD8+ T cells lacking Id2 did not generate a robust terminally-differentiated KLRG1hi effector population, but displayed a cell-surface phenotype and cytokine profile consistent with memory precursors, raising the question as to whether loss of Id2 impairs the differentiation and/or survival of effector-memory cells. We found that deletion of Bim rescued Id2-deficient CD8+ cell survival during infection. However, the dramatic reduction in KLRG1hi cells caused by loss of Id2 remained in the absence of Bim, such that Id2/Bim double-deficient cells form an exclusively KLRG1loCD127hi memory precursor population. Thus we describe a role for Id2 in both the survival and differentation of normal CD8+ effector and memory populations. Gene-expression analysis of Wild-type, Id2KO, Id2KOBimKO and BimKO effector CD8+ cells on day 6 of Listeria infection. 2 or more replicates per sample were analyzed.
Project description:The differentiation into effector and memory CD8+ T cell subsets was recently associated with specific metabolic pathways to sustain their diverse bioenergetics needs. Clonally expanding T cells rely strongly on glucose and glutamine utilization to maintain high cell proliferation and effector functions. We found that proliferating effector CD8+ T cells, in addition to oxidizing, also reductively carboxylate glutamine, to maintain rapid lipid synthesis for cell proliferation. Interfering with reductive carboxylation by genetic deletion of isocitrate dehydrogenase 2 (IDH2), the enzyme mediating this reaction in the mitochondria, surprisingly did not impair proliferation and effector function upon infection, but skewed the CD8+ T cell response towards enhanced memory differentiation. Pharmacological IDH2 inhibition during in vitro CAR T cell manufacturing also induced memory features and thus strongly enhanced their antitumor activity and persistence upon adoptive cell transfer into murine melanoma tumour models. Mechanistically, IDH2 inhibition caused a disequilibrium in metabolites regulating histone-modifying enzymes, which altered the epigenetic landscape, increasing chromatin accessibility at genes required for memory differentiation. Restoring this metabolite balance or preventing the epigenetic modifications abrogated the enhanced CD8+ T cell memory differentiation and anti-tumour activity induced by IDH2 inhibition. These findings suggest that reductive carboxylation of glutamine in activated CD8+ T cells is dispensable for their effector function, but instead primarily instructs a metabolite composition that epigenetically locks them in a terminal effector differentiation program. Blocking this metabolic route allows for increased memory formation, which can be exploited to optimize CAR T cell production for adoptive cell transfer immunotherapy against cancer.
Project description:The differentiation into effector and memory CD8+ T cell subsets was recently associated with specific metabolic pathways to sustain their diverse bioenergetics needs. Clonally expanding T cells rely strongly on glucose and glutamine utilization to maintain high cell proliferation and effector functions. We found that proliferating effector CD8+ T cells, in addition to oxidizing, also reductively carboxylate glutamine, to maintain rapid lipid synthesis for cell proliferation. Interfering with reductive carboxylation by genetic deletion of isocitrate dehydrogenase 2 (IDH2), the enzyme mediating this reaction in the mitochondria, surprisingly did not impair proliferation and effector function upon infection, but skewed the CD8+ T cell response towards enhanced memory differentiation. Pharmacological IDH2 inhibition during in vitro CAR T cell manufacturing also induced memory features and thus strongly enhanced their antitumor activity and persistence upon adoptive cell transfer into murine melanoma tumour models. Mechanistically, IDH2 inhibition caused a disequilibrium in metabolites regulating histone-modifying enzymes, which altered the epigenetic landscape, increasing chromatin accessibility at genes required for memory differentiation. Restoring this metabolite balance or preventing the epigenetic modifications abrogated the enhanced CD8+ T cell memory differentiation and anti-tumour activity induced by IDH2 inhibition. These findings suggest that reductive carboxylation of glutamine in activated CD8+ T cells is dispensable for their effector function, but instead primarily instructs a metabolite composition that epigenetically locks them in a terminal effector differentiation program. Blocking this metabolic route allows for increased memory formation, which can be exploited to optimize CAR T cell production for adoptive cell transfer immunotherapy against cancer.
Project description:p38 MAPK is activated during CD8+ T cell primary response. p38 activation promotes effector CD8+ T cell terminal differentiation but represses MPEC formation. p38α/beta deficient mice possess a similar number of virus-specific effector CD8+ T cells as wildtype counterparts. Meanwhile p38α/beta deletion doesn’t influence the clearance of LCMV although it impairs the cytolytic activity of CD8+ T cells. Loss of p38α/beta significantly enhances IL-2-producing Tcm accumulation in mouse spleen with no impact on total memory CD8+ T cell numbers yet. And in line with this, more robust proliferation of memory CD8+ T cells in the secondary response and stronger antigen-specific killing ability in rechallenged mice are resulted from p38α/beta deficiency. These results establish a pivotal role for p38α/beta in skewing MPEC formation toward SLEC differentiation, as well as in suppressing Tcm formation, and thus affecting the recall response.