Project description:T lymphocytes responding to microbial infection give rise to effector cells that mediate acute host defense and memory cells that provide long-lived immunity, but the fundamental question of when and how these cells arise remains unresolved. Here we combine single-cell gene expression analyses with machine-learning approaches to trace the transcriptional roadmap of individual CD8+ T lymphocytes throughout the course of an immune response in vivo. Gene expression signatures predictive of eventual fates could be discerned as early as the first T lymphocyte division and may be influenced by asymmetric partitioning of the interleukin-2 receptor during mitosis. These findings underscore the importance of single-cell analyses in understanding fate determination and provide new insights into the specification of divergent lymphocyte fates early during an immune response to microbial infection.
Project description:During microbial infection, responding CD8+ T lymphocytes differentiate into heterogeneous subsets that together provide immediate and durable protection. To elucidate the dynamic transcriptional changes that underlie this process, we applied a single-cell RNA sequencing approach and analyzed individual CD8+ T lymphocytes sequentially throughout the course of a viral infection in vivo. Our analyses revealed a striking transcriptional divergence among cells that had undergone their first division and identified previously unknown molecular determinants controlling CD8+ T lymphocyte fate specification, including Ezh2, the catalytic component of the Polycomb Repressive Complex 2. Our data provide a revised model of terminal effector cell differentiation initiated by an early burst of transcriptional activity and subsequently refined by epigenetic silencing of transcripts associated with memory lymphocytes. These findings provide unexpected insights into tightly coupled transcriptional and epigenetic mechanisms underlying CD8+ T lymphocyte fate specification and highlight the power and necessity of single-cell approaches.
Project description:T lymphocytes responding to microbial infection give rise to effector cells that mediate acute host defense and memory cells that provide long-lived immunity, but the fundamental question of when and how these cells arise remains unresolved. Here we combine single-cell gene expression analyses with machine-learning approaches to trace the transcriptional roadmap of individual CD8+ T lymphocytes throughout the course of an immune response in vivo. Gene expression signatures predictive of eventual fates could be discerned as early as the first T lymphocyte division and may be influenced by asymmetric partitioning of the interleukin-2 receptor during mitosis. These findings underscore the importance of single-cell analyses in understanding fate determination and provide new insights into the specification of divergent lymphocyte fates early during an immune response to microbial infection. The goal of the study was to profile the gene expression in single CD8+ T cells responding in vivo to a microbial infection over multiple timepoints. 5 x 103 CD8+ CD45.1+ T cells transgenic for the OT-1 T cell receptor (which recognizes Listeria monocytogenes expressing ovalbumin (Lm-ova)) were adoptively transferred into congenic wild-type CD45.2 C57/B6J recipients, followed by infection intravenously one day later with 5 x 103 colony-forming units (CFU) of Lm-OVA. Splenocytes were isolated from recipient mice at 5, 7, or 45 days post-infection. To isolate cells at 3 days post-infection, 2 x 104 OT-1 CD8+ T cells were adoptively transferred. To isolate cells that had undergone their first division, 2 x 106 OT-1 CD8+ T cells were first labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE) prior to adoptive transfer and recipient mice were sacrificed at 48 hours post-infection. Unactivated naM-CM-/ve OT-1 CD45.1+ CD8+ T cells were also included. Cells were stained with fluorochrome-labeled antibodies against CD8, CD44, CD4, CD11b, CD11c, and F4/80, and sorted on a MoFlo (Beckman Coulter) or FACS Aria II (BD Biosciences) flow cytometer. The Ct value for each gene analyzed in each individual cell at each time point is reported in the Matrix non-normalized. The 94 ABI TaqMan Assay IDs are listed on the left (A2-A96), along with the accession number (B2-B96) and corresponding gene name (C2-C96) of each gene studied. The Il2 gene expression assay was duplicated. Each heading (D1-BCV)) represents a single cell from each of 13 timepoints or T cell subset that were profiled. The timepoints/T cell subsets and number of each cells profiled from each timepoint/T cell subset were: unactivated naM-CM-/ve (149 cells), distal daughter (48), proximal daughter (83), division 1 (144), day 3 post-infection (143), day 5 post-infection memory precursor (Tmp) (90), day 5 post-infection short-lived effector (Tsle) (79), day 5 post-infection (154), day 7 post-infection memory precursor Tmp (62), day 7 post-infection short-lived effector Tsle (89), day 7 post-infection (134), central memory Tcm (138), and effector memory Tem (136).
Project description:Through a diversity of functional lineages, cells of the innate and adaptive immune system either drive or constrain immune reactions within tumors. Thus, while the immune system has a powerful ability to recognize and kill cancer cells, this function is often suppressed preventing clearance of disease. The transcription factor (TF) BACH2 controls the differentiation and function of multiple innate and adaptive immune lineages, but its role in regulating tumor immunity is not known. Here, we demonstrate that BACH2 is required to establish immunosuppression within tumors. We found that growth of subcutaneously implanted tumors was markedly impaired in Bach2-deficient mice and coincided with intratumoral activation of both innate and adaptive immunity but was dependent upon adaptive immunity. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression. These findings demonstrate that BACH2 is a key component of the molecular programme of tumor immunosuppression and identify a new target for development of therapies aimed at reversing immunosuppression in cancer. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression.
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:We utilize single-cell sequencing (scSeq) of lymphocyte immune repertoires and transcriptomes to quantitatively profile the adaptive immune response in COVID-19 patients of varying age. Our scSeq analysis defines the adaptive immune repertoire and transcriptome in convalescent COVID-19 patients and shows important age-related differences implicated in immunity against SARS-CoV-2.
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:Through a diversity of functional lineages, cells of the innate and adaptive immune system either drive or constrain immune reactions within tumors. Thus, while the immune system has a powerful ability to recognize and kill cancer cells, this function is often suppressed preventing clearance of disease. The transcription factor (TF) BACH2 controls the differentiation and function of multiple innate and adaptive immune lineages, but its role in regulating tumor immunity is not known. Here, we demonstrate that BACH2 is required to establish immunosuppression within tumors. We found that growth of subcutaneously implanted tumors was markedly impaired in Bach2-deficient mice and coincided with intratumoral activation of both innate and adaptive immunity but was dependent upon adaptive immunity. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression. These findings demonstrate that BACH2 is a key component of the molecular programme of tumor immunosuppression and identify a new target for development of therapies aimed at reversing immunosuppression in cancer.
Project description:Neuroinflammation in the brain contributes to the pathogenesis of Parkinson’s disease (PD), but the potential dysregulation of peripheral immunity has not been systematically investigated for idiopathic PD (iPD). Here we showed an elevated peripheral cytotoxic immune milieu, with more terminally-differentiated effector memory (TEMRA) CD8 T, CD8+ NKT cells and circulating cytotoxic molecules in fresh blood of early-to-mid iPD, especially in females, after analyzing >700 innate and adaptive features. This profile, also reflected by fewer CD8+FOXP3+ regulatory T cells, was confirmed in another subcohort. Co-expression between cytotoxic molecules was selectively enhanced in CD8 TEMRA and effector memory (TEM) cells. Single-cell RNA-sequencing analysis demonstrated the accelerated CD8 differentiation within CD8 compartments, enhanced cytotoxic pathways in CD8 TEMRA and TEM cells, while CD8 central-memory (TCM) and naïve cells were already more-active and transcriptionally-reprogrammed. Our work provides a comprehensive map of dysregulated peripheral immunity in iPD, proposing previously-unrecognized candidates for early diagnosis and treatments.
Project description:Persistent exposure to antigen leads to T cell exhaustion and immunologic dysfunction. We examined the immune exhaustion markers TIGIT and PD-1 in HIV-infected and healthy individuals and the relationship with cytotoxic CD8+ T lymphocyte (CTL) activity. Frequencies of TIGIT but not PD-1 positively correlated with CTL activity in HIV-aviremic and healthy individuals; however, there was no correlation in HIV-viremic individuals. Transcriptome analyses revealed upregulation of genes associated with antiviral immunity in TIGIT+ versus TIGIT-CD8+ T cells. Our data suggest that TIGIT+CD8+ T cells do not necessarily represent a state of immune exhaustion and maintain an intrinsic cytotoxicity in HIV-infected individuals.