Project description:Known for nearly a century, but through mechanisms that remain elusive, cells retain a memory of inflammation that equips them to react quickly and broadly to diverse secondary stimuli. Using mouse epidermal stem cells as a model, we elucidate how cells establish, maintain and recall inflammatory memory. Specifically, we landscape and functionally interrogate temporal, dynamic changes to chromatin accessibility, histone modifications and transcription factor binding that occur during inflammation, post-resolution and in memory recall following injury. We unearth an essential, unifying role for the general stress-responsive transcription factor FOS, which partners with JUN and cooperates with stimulus-specific STAT3 to establish memory; JUN then remains with other homeostatic factors on memory domains, facilitating rapid FOS re-recruitment and gene re-activation upon diverse secondary challenges. Extending our findings, we offer a comprehensive, potentially universal mechanism behind inflammatory memory and less discriminate recall, phenomena with profound implications for tissue fitness in health and disease.
Project description:Memory T cells provide long-lasting defense responses through their ability to rapidly reactivate. How memory T cells efficiently ‘recall’ an inflammatory transcriptional program remains unclear. Here, we show that primary human CD4+ memory T helper (Th) cells carry three distinct activation-inducible recall gene modules that drive metabolic adaptation, T cell activation and inflammatory cytokine production. Enhancer elements controlling recall genes were epigenetically primed through the local maintenance of transcription-permissive chromatin in resting memory Th cells. At the three-dimensional level, recall genes clustered in transcriptionally permissive subnuclear compartments and resided in topologically associating domains (‘memory TADs’), in which activation-associated promoter-enhancer interactions were pre-formed. This primed epigenomic landscape was exploited by AP-1 transcription factors - including MAF - to promote rapid transcriptional activation. Finally, recall genes and their enhancers were linked to memory Th cell dysfunction in chronic inflammatory disease. Together, our results implicate multi-scale epigenomic priming - comprising a specialized three-dimensional chromatin organization - as a key mechanism underlying immunological memory.
Project description:Memory T cells provide long-lasting defense responses through their ability to rapidly reactivate. How memory T cells efficiently ‘recall’ an inflammatory transcriptional program remains unclear. Here, we show that primary human CD4+ memory T helper (Th) cells carry three distinct activation-inducible recall gene modules that drive metabolic adaptation, T cell activation and inflammatory cytokine production. Enhancer elements controlling recall genes were epigenetically primed through the local maintenance of transcription-permissive chromatin in resting memory Th cells. At the three-dimensional level, recall genes clustered in transcriptionally permissive subnuclear compartments and resided in topologically associating domains (‘memory TADs’), in which activation-associated promoter-enhancer interactions were pre-formed. This primed epigenomic landscape was exploited by AP-1 transcription factors - including MAF - to promote rapid transcriptional activation. Finally, recall genes and their enhancers were linked to memory Th cell dysfunction in chronic inflammatory disease. Together, our results implicate multi-scale epigenomic priming - comprising a specialized three-dimensional chromatin organization - as a key mechanism underlying immunological memory.
Project description:During T cell responses, a fraction of activated cells adopts a memory phenotype and returns to quiescence. These long-lived memory T cells retain an irreversible molecular imprint that enables them to mount a secondary recall response to the same antigen that is faster and greater in magnitude than the primary response of a naive cell. Memory T cells provide long-lasting immunological protection, forming the foundation for vaccination strategies and representing prime targets for immunotherapies to treat diseases characterized by dysfunctional memory T cells - including cancer and chronic inflammation. The molecular circuitry that endows memory T cells with their rapid recall ability remains incompletely understood. Here, we applied a multi-layered 1D-3D epigenomics approach to systematically dissect the molecular program driving rapid recall in primary human Th2 cells.
Project description:Memory B cell responses are more rapid and of greater magnitude than are primary antibody responses. The mechanisms by which these secondary responses are eventually attenuated remain unknown. We demonstrate that the transcription factor ZBTB32 limits the rapidity and duration of antibody recall responses. ZBTB32 is highly expressed by mouse and human memory B cells, but not by their naïve counterparts. Zbtb32-/- mice mount normal primary antibody responses to T-dependent antigens. However, Zbtb32-/- memory B cell-mediated recall responses occur more rapidly and persist longer than do control responses. Microarray analyses demonstrate that Zbtb32-/- secondary bone marrow plasma cells display elevated expression of genes that promote cell cycle progression and mitochondrial function relative to wild-type controls. BrdU labeling and adoptive transfer experiments confirm more rapid production and a cell-intrinsic survival advantage of Zbtb32-/- secondary plasma cells relative to wild-type counterparts. ZBTB32 is therefore a novel negative regulator of antibody recall responses. CD45.2 wild type and Zbtb32-/- splenocytes from NP-CGG-immune donors were transferred into CD45.1 recipients and challenged with NP-CGG. CD45.2 donor NP-specific memory B cells were isolated from the spleen 7 days later. 5-6 biological replicates of each genotype were performed.
Project description:Asthma is a chronic inflammatory lung disease with intermittent flares predominately mediated through memory T cells. Yet, the identity of long-term memory cells that mediate allergic recall responses are not well defined. In this report, using a mouse model of chronic allergen exposure followed by an allergen-free rest period, we have characterized a sub-population of Th2 cells that secretes IL-9 as an obligate effector cytokine. IL-9-secreting cells have a resident memory T cell phenotype and blocking IL-9 during a recall challenge significantly diminishes airway inflammation and airway hyperreactivity. T cells secrete IL-9 in response to allergen recall and secretion is amplified by IL-33. Using scRNA-seq and scATAC-seq, we define the cellular identity of a distinct populations of T cells with pro-allergic cytokine patterns. Thus, in a recall model of allergic airway inflammation, IL-9 secretion from a multi-cytokine producing cell population is required for an allergen recall response.
Project description:Even though T-cell receptor (TCR) stimulation together with co-stimulation is sufficient for the activation of both naïve and memory T cells, the memory cells are capable of producing lineage specific cytokines much more rapidly than the naïve cells. The mechanisms behind this rapid recall response of the memory cells are still not completely understood. Here, we performed epigenetic profiling of human resting naïve, central and effector memory T cells using ChIP-Seq and found that unlike the naïve cells, the regulatory elements of the cytokine genes in the memory T cells are marked by activating histone modifications even in the resting state. Therefore, the ability to induce expression of rapid recall genes upon activation is associated with the deposition of positive histone modifications during memory T cell differentiation. We propose a model of T cell memory, in which immunological memory state is encoded epigenetically, through poising and transcriptional memory.
Project description:Memory B cell responses are more rapid and of greater magnitude than are primary antibody responses. The mechanisms by which these secondary responses are eventually attenuated remain unknown. We demonstrate that the transcription factor ZBTB32 limits the rapidity and duration of antibody recall responses. ZBTB32 is highly expressed by mouse and human memory B cells, but not by their naïve counterparts. Zbtb32-/- mice mount normal primary antibody responses to T-dependent antigens. However, Zbtb32-/- memory B cell-mediated recall responses occur more rapidly and persist longer than do control responses. Microarray analyses demonstrate that Zbtb32-/- secondary bone marrow plasma cells display elevated expression of genes that promote cell cycle progression and mitochondrial function relative to wild-type controls. BrdU labeling and adoptive transfer experiments confirm more rapid production and a cell-intrinsic survival advantage of Zbtb32-/- secondary plasma cells relative to wild-type counterparts. ZBTB32 is therefore a novel negative regulator of antibody recall responses. CD45.2 wild type and Zbtb32-/- splenocytes from NP-CGG-immune donors were transferred into CD45.1 recipients and challenged with NP-CGG. CD45.2 donor NP-specific plasma cells B cells were isolated from the bone marrow 7 days later. 6 biological replicates of each genotype were performed.
Project description:During a T cell response, naïve CD8 T cells differentiate into effector cells. Subsequently, a subset of effector cells termed memory precursor effector cells (MPECs) further differentiates into functionally mature memory CD8 T cells. The transcriptional network underlying this carefully scripted process is not well understood. Here, we report that the transcription factor FoxO1 plays an integral role in facilitating effector to memory transition and functional maturation of memory CD4 and CD8 T cells. We find that FoxO1 is not required for differentiation of effector cells, but in the absence of FoxO1, memory CD8 T cells displayed features of scenescence and progressive attrition in polyfunctionality, which in turn led to impared recall responses and poor protective immunity. These data suggest that FoxO1 is essential for active maintenance of functional CD8 T cell memory and protective immunity. Under competing conditions in bone marrow Single-cell suspensions from splenocytes of eight samples WT (control) and FoxO1-/- (experimental) LCMV-immune mice were prepared using standard procedures. CD8 T cells were then isoloated using Thy1.2 (CD90.2) (30-H12) microbeads (Miltenyi Biotec). Cells were then stained with anti-CD8, anti-CD44 and Db/NP396 MHC class I tetramer. Activated (CD8+CD44hi), naive (CD8+CD44lo), and virus-specific CD8 T cells were sorted using FACSAria II instrument (BD Biosciences). The purity of the cells was >95%. Total RNA was extracted from the sorted cells by Trizol Reagent. RNA samples were reverse transcribed and Cy3-labeled cDNAs were hyrbidized to Agilent whole Mouse Genome Oligo Microarrays. Fluorscence signals were detected using Agilent's Microarray Scanner system, data was analyzed using the Rosetta Resolver gene expression data analysis system and genes with a fold change < and p-values <0.01 were identified. Microarray data discussed in the paper is focused on virus-specific memory CD8 T cells from samples WT_Tet_2 vs KO_Tet_2.
Project description:The goal of this study is to determine the impact of Tcf1 deficiency on recall capacity of central memory CD8+ T (Tcm) cells. We demonstrate that loss of Tcf1 shows limited impact on Tcm cells at resting state, but severely comprimises activation of glycolysis and other key regulators during recall response. Based on these findings, we propose that Tcf1 preprograms the responsiveness of Tcm cells to secondary challenges.