Project description:Naïve CD4+ T cells coordinate the immune response by acquiring an effector phenotype in response to cytokines. However, the cytokine responses in memory T cells remain largely understudied. We used quantitative proteomics, bulk RNA-seq and single-cell RNA-seq of over 40,000 human naïve and memory CD4+ T cells to generate a detailed map of cytokine-regulated gene expression programs. We demonstrated that cytokine response differs substantially between naïve and memory T cells and showed that memory cells are unable to differentiate into the Th2 phenotype. Moreover, memory T cells acquire a Th17-like phenotype in response to iTreg polarization. At the single-cell level, we demonstrated that T cells form a continuum which progresses from naïve to effector memory T cells. This continuum is accompanied by a gradual increase in the expression levels of chemokines and cytokines and thus represents an effectorness gradient. Finally, we found that T cell cytokine responses are determined by where the cells lie in the effectorness gradient and identified genes whose expression is controlled by cytokines in an effectorness-dependent manner. Our results shed light on the heterogeneity of T cells and their responses to cytokines, provide insight into immune disease inflammation and could inform drug development.
Project description:Innate memory phenotype (IMP) CD4+ T cells are non-conventional αβ T cells exhibiting features of innate immune cells, characterized as CD44high and CD62Llow in periphery. It is recently reported by our group that bone marrow chimeric mice lacking thymic MHCI expression develop predominantly IMP CD8+ T cells, while those lacking hematopoietic MHCI develop predominantly naïve CD8+ T cells. Here we perform hirarchical clustering analysis and found that CD4+ T cells share similar property: chimeras lacking thymic MHCII gave rise to predominantly CD4+ T cells that resemble IMP CD4+ T cells observed in WT mice, and vice versa, chimeras lacking hematopoietic MHCII had a majority of naïve-like CD4+ T cells resembling naïveCD4+ T cells seen in WT mice. We used microarrays to compare the global programme of gene expression to determine whether the hematopoietic MHCII selected CD4+ T cells are IMP, and whether the thymic MHCII selected CD4+ T cells are naïve CD4+ T cells as observed in WT mice. Through hierarchical clustering and analysis of global gene differential expression, we determined that hematopoietic MHCII dependent IMP CD4+ T cells generated from WT bone marrow transplanted into irradiated MHCII-/- recipients, resemble IMP CD4+ T cells in WT mice, while naïve CD4+ T cells generated from MHCII-/- bone marrow transplanted into irradiated WT recipients, resemble naïve CD4+ T cells in WT mice.
Project description:The importance of CD4+ T helper (Th) cells is well appreciated in view of their essential role in the elicitation of antibody and cytotoxic T cell responses. However, the mechanisms that determine the selection of immunodominant epitopes within complex protein antigens remain elusive. Here, we used ex vivo stimulation of memory T cells and screening of naïve and memory T cell libraries, combined with T cell cloning and TCR sequencing, to dissect the human naïve and memory CD4+ T cell repertoire against the influenza pandemic H1 hemagglutinin (H1-HA). We found that naïve CD4+ T cells have a broad repertoire, being able to recognize naturally processed as well as cryptic peptides spanning the whole H1-HA sequence. In contrast, memory Th cells were primarily directed against just a few immunodominant peptides that were readily detected by mass spectrometry-based MHC-II peptidomics and predicted by structural accessibility analysis. Collectively, these findings reveal the presence of a broad repertoire of naïve T cells specific for cryptic H1-HA peptides, and demonstrate that antigen processing represents a major constraint determining immunodominance.
Project description:Memory T cells are primed for rapid responses to antigen; however, the molecular mechanisms responsible for priming remain incompletely defined. CpG methylation in promoters is an epigenetic modification, which regulates gene transcription. Using targeted bisulfite sequencing, we examined methylation of 2100 genes (56,000 CpG) mapped by deep sequencing to T cell activation in human naïve and memory CD4 T cells. 466 CpGs (132 genes) displayed differential methylation between naïve and memory cells. 21 genes exhibited both differential methylation and gene expression before activation, linking promoter DNA methylation states to gene regulation; 6 genes encode proteins closely studied in T cells while 15 genes represent novel targets for further study. 39 genes exhibited reduced methylation in memory cells coupled with increased gene expression with activation compared to naïve cells, revealing specific genes more rapidly expressed in memory compared to naïve cells and potentially regulated by DNA methylation. These findings define a DNA methylation signature unique to memory CD4 T cells and correlated with activation-induced gene expression. transcriptome of primary human naïve and memory CD4 T cells at rest and 48 hours post-activation.
Project description:CD4+ T cells orchestrate both humoral and cytotoxic immune responses. While it is known that CD4+ T cell proliferation relies on autophagy, direct identification of the autophagosomal cargo involved is still missing. Here, we created a transgenic mouse model, which, for the first time, enables us to directly map the proteinaceous content of autophagosomes in any primary cell by LC3 proximity labelling. IL-7Rα, a cytokine receptor mostly found in naïve and memory T cells, was reproducibly detected in autophagosomes of activated CD4+ T cells. Consistently, CD4+ T cells lacking autophagy showed increased IL-7Rα surface expression, while no defect in internalisation was observed. Mechanistically, excessive surface IL-7Rα sequestrates the common gamma chain, impairing the IL-2R assembly and downstream signalling crucial for T cell proliferation. This study provides proof-of-principle that key autophagy substrates can be reliably identified with this model to help mechanistically unravel autophagy’s contribution to healthy physiology and disease.
Project description:Memory T cells are primed for rapid responses to antigen; however, the molecular mechanisms responsible for priming remain incompletely defined. CpG methylation in promoters is an epigenetic modification, which regulates gene transcription. Using targeted bisulfite sequencing, we examined methylation of 2100 genes (56,000 CpG) mapped by deep sequencing to T cell activation in human naïve and memory CD4 T cells. 466 CpGs (132 genes) displayed differential methylation between naïve and memory cells. 21 genes exhibited both differential methylation and gene expression before activation, linking promoter DNA methylation states to gene regulation; 6 genes encode proteins closely studied in T cells while 15 genes represent novel targets for further study. 39 genes exhibited reduced methylation in memory cells coupled with increased gene expression with activation compared to naïve cells, revealing specific genes more rapidly expressed in memory compared to naïve cells and potentially regulated by DNA methylation. These findings define a DNA methylation signature unique to memory CD4 T cells and correlated with activation-induced gene expression. RNA sequencing of primary human naïve and memory CD4 T cells at rest and 48 hours post-activation.
Project description:Memory T cells are primed for rapid responses to antigen; however, the molecular mechanisms responsible for priming remain incompletely defined. CpG methylation in promoters is an epigenetic modification, which regulates gene transcription. Using targeted bisulfite sequencing, we examined methylation of 2100 genes (56,000 CpG) mapped by deep sequencing to T cell activation in human naïve and memory CD4 T cells. 466 CpGs (132 genes) displayed differential methylation between naïve and memory cells. 21 genes exhibited both differential methylation and gene expression before activation, linking promoter DNA methylation states to gene regulation; 6 genes encode proteins closely studied in T cells while 15 genes represent novel targets for further study. 39 genes exhibited reduced methylation in memory cells coupled with increased gene expression with activation compared to naïve cells, revealing specific genes more rapidly expressed in memory compared to naïve cells and potentially regulated by DNA methylation. These findings define a DNA methylation signature unique to memory CD4 T cells and correlated with activation-induced gene expression. Targeted bisulfite sequencing of primary human naïve and memory CD4 T cells at rest and 48 hours post-activation.