Project description:Here we implemented a simple dendritic cell (DC)-mediated immunization approach to study the effects of commonly used adjuvants, Toll like receptor (TLR) ligands, on effector CD8 T cell differentiation and memory T cell development. To our surprise, we found that the TLR4 ligand LPS was far more superior to other TLR ligands in generating memory CD8 T cells upon immunization. LPS boosted clonal expansion similar to the other adjuvants, but fewer of the activated CD8 T cells died during contraction, generating a larger pool of memory cells. Intriguingly, monophosphoryl lipid A (MPLA), another TLR4 ligand, enhanced clonal expansion of effector CD8 T cells, but also promoted their terminal differentiation and contraction; thus, fewer memory CD8 T cells formed and MPLA-primed animals were less protected against secondary infection compared to those primed with LPS. Furthermore, gene expression profiling revealed that LPS-primed effector cells displayed a stronger pro-memory gene expression signature, whereas the gene expression profile of MPLA-primed effector cells had aligned closer with terminal effector CD8 T cells. Mice that contain small number of P14 CD8 T cells were immunized with DC-33 either alone or in combination with LPS or MPLA. KLRG1loIL-7Rhi MPECs were purified by FACS sort, and mRNA isolated from MPECs was subjected to whole-genome expression profiling using Illumina MouseWG-6 v2.0 Expression BeadChip.
Project description:Here we implemented a simple dendritic cell (DC)-mediated immunization approach to study the effects of commonly used adjuvants, Toll like receptor (TLR) ligands, on effector CD8 T cell differentiation and memory T cell development. To our surprise, we found that the TLR4 ligand LPS was far more superior to other TLR ligands in generating memory CD8 T cells upon immunization. LPS boosted clonal expansion similar to the other adjuvants, but fewer of the activated CD8 T cells died during contraction, generating a larger pool of memory cells. Intriguingly, monophosphoryl lipid A (MPLA), another TLR4 ligand, enhanced clonal expansion of effector CD8 T cells, but also promoted their terminal differentiation and contraction; thus, fewer memory CD8 T cells formed and MPLA-primed animals were less protected against secondary infection compared to those primed with LPS. Furthermore, gene expression profiling revealed that LPS-primed effector cells displayed a stronger pro-memory gene expression signature, whereas the gene expression profile of MPLA-primed effector cells had aligned closer with terminal effector CD8 T cells.
Project description:Memory CD8+ T cells are an essential component of protective immunity. Signaling via mechanistic target of rapamycin (mTOR) has been implicated in the regulation of the differentiation of effector and memory T cells. However, little is understood about the mechanisms that control mTOR activity, or the effector pathways regulated by mTOR, in this process. We describe here that tuberous sclerosis 1 (Tsc1), a regulator of mTOR signaling, plays a crucial role in promoting the differentiation and function of memory CD8+ T cells in response to Listeria monocytogenes infection. Mice with specific deletion of Tsc1 in antigen-experienced CD8+ T cells evoked normal effector responses, but were markedly impaired in the generation of memory T cells and their recall responses to antigen re-exposure in a cell-intrinsic manner. Tsc1 deficiency suppressed the generation of memory-precursor effector cells (MPECs) while promoting short-lived effector cell (SLEC) differentiation. Functional genomic analysis indicated that Tsc1 coordinated gene expression programs underlying immune function, transcriptional regulation and cell metabolism. Furthermore, Tsc1 deletion led to excessive mTORC1 activity and dysregulated cellular metabolism including glycolytic and oxidative metabolism. These findings establish a Tsc1-mediated checkpoint in linking immune signaling and cell metabolism to orchestrate memory CD8+ T cell development and function. We used microarrays to explore the gene expression profiles differentially expressed in OVA-specific CD8+ T-cells from wild-type (WT; Tsc1-fl/fl and cre-negative) and Tsc1-/- (Tsc1-fl/fl and Granzyme B-cre-positive) mice
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:Differentiation of CD8+ T lymphocytes into effector and memory cells is key for an adequate immune response and relies on complex interplay of pathways that convey signals from cell surface to nucleus. In this study, we fractionated four CD8+ T cell subtypes; naïve, recently activated effector, effector and memory cells into membrane, cytosol, soluble nucleus, chromatin-bound and cytoskeleton compartments. Using LC-MS/MS analysis, identified peptides were matched to human peptides/proteins (SwissProt). Compartment fractionation and gel-LC-MS separation identified 2399 proteins in total. Among these 735 were detected in all five, 241 in four, 257 in three, 368 in two and 798 found in only one fraction. Comparison between the two most different subsets, naïve and effector, yielded 146 significantly regulated proteins.
Project description:The generation of CD8+ T-cell memory is an important aim of immunization. While several distinct subsets of CD8+ T-cell memory have been described, the lineage relationships between effector (EFF), effector memory (EM) and central memory (CM) T cells remain contentious. Specifically, there is contradictory experimental evidence to support both the linear (Naive>EFF>EM>CM) and progressive differentiation (Naive>CM>EM>EFF) models. In this study, we applied a systems biology approach to examine global transcriptional relationships between the three major CD8+ T cell subsets arising endogenously as a result of vaccination with three different prime-boost vaccine regimens. Differential gene expression analysis and principle component analysis revealed that central memory cells were more closely related to naive T cells than both effector memory and effector cells. When the transcriptional relationships between subsets were enriched in an unbiased fashion with known global transcriptional changes that result when T-cells repeatedly encounter antigen, our analysis favored a model whereby cumulative antigenic stimulation drives differentiation specifically from Naive > CM > EM > EFF. These findings provide an insight into the lineage relationship between mature CD8+ T-cell subsets and will help in the rational design of vaccines aimed at generating effective immune responses against infections and cancer. Effector (EFF), effector memory (EM), central memory (CM) and naive CD8+ T cells from mice spleen. Memory subset arise endogenously as a result of vaccination with three different prime-boost vaccine regimens: DNA-rAd5, rAd5-rAd5 and rAd5-rLCMV.
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:Immune memory cells are poised to rapidly expand and elaborate effector functions upon reinfection. However, despite heightened readiness to respond, memory cells exist in a functionally quiescent state. The paradigm is that memory cells remain inactive due to lack of TCR stimuli. Here we report a unique role of Tregs in orchestrating memory quiescence by inhibiting effector and proliferation programs through CTLA-4. Loss of Tregs resulted in activation of genome-wide transcriptional programs characteristic of potent effectors, and both developing and established memory quickly reverted to a terminally differentiated (KLRG-1hi/IL-7R±lo/GzmBhi) phenotype, with compromised metabolic fitness, longevity, polyfunctionality and protective efficacy. CTLA-4, an inhibitory receptor overexpressed on Tregs, functionally replaced Tregs in trans to rescue Treg-less memory defects and restore homeostasis of secondary mediators as well. These studies present CD28-CTLA-4-CD80/CD86 axis as a novel target to potentially accelerate vaccine-induced immunity and improve T-cell memory quality in current cancer immunotherapies proposing transient Treg-depletion. We used microarray analysis to detail the global programming of gene expression in LCMV GP33-specific CD8 T cells differentiated in the presence or absence of regulatory T cells Differentiation of memory CD8 T cells entails a progressive transition of highly activated effector program to a quiescent memory program. A key question in the field is to understand the factors that aid in the differentiation of memory cells from effector cells. It is a generally accepted paradigm that effector cells transition to a memory state by default after antigen clearance, since TCR stimuli is the key driver of effector programs in CD8 T cells. We hypothesized that the effector to memory transition of CD8 T cells involves active immunological brakes through regulatory T cells (Tregs) that allow the highly activated effector cells to convert into quiescent memory cells. To address this hypothesis, we used FoxP3-DTR mice to deplete Tregs during the window following antigen clearance, during which the effector CD8 T cells convert to long-lived memory cells. To get a deeper understanding of the global transcriptome of CD8 T cells as they transition from an effector to a memory state, we isolated and arrayed the antigen-specific CD8 T cells at day 16 post-infection that have experienced the transitional environment with and without the presence of Tregs.
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:Effector cells for adoptive immunotherapy can be generated by in vitro stimulation of naïve or memory subsets of CD8+ T cells. While the characteristics of CD8+ T cell subsets are well defined, the heritable influence of those populations on their effector cell progeny is not well understood. We studied effector cells generated from naïve or central memory CD8+ T cells and found that they retained distinct gene expression signatures and developmental programs. Effector cells derived from central memory cells tended to retain their CD62L+ phenotype, but also to acquire KLRG1, an indicator of cellular senescence. In contrast, the effector cell progeny of naïve cells displayed reduced terminal differentiation, and, following infusion, they displayed greater expansion, cytokine production, and tumor destruction. These data indicate that effector cells retain a gene expression imprint conferred by their naïve or central memory progenitors, and they suggest a strategy for enhancing cancer immunotherapy. Experiment Overall Design: Effector cells were generated from naive or central memory CD8+ T cells. The cells were then rested (unstimulated) or restimulated (stimulated). This experimental design resulted in 4 groups (Naïve-derived/stimulated, Naïve-derived/unstimulated, Central memory-derived/stimulated, Central memory-derived/unstimulated). Three replicates from independent experiments were analyzed.