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The most common congenital viral infection is CMV, which leads to numerous neurologic disabilities. Using a mouse model of congenital CMV, we previously determined that Ag-specific CD8+ T cells traffic to the brain in a CCR9-dependent manner. The mechanism by which these CD8+ T cells acquire a CCR9-dependent "brain-tropic" phenotype remains unclear. In this study, we identify the key factor that imprints brain homing specificity on CD8+ T cells, the source of production, and the location where CCR9 expression is induced. Specifically, we discovered that CCR9 is induced on CD8+ T cells by retinoic acid-producing CD8α+ dendritic cells in the cervical lymph node postinfection. We found that retinoic acid is important for CD8+ T cells to establish tissue residency in the brain. Collectively, our data expand the role of retinoic acid during infection and mechanistically demonstrate how CD8+ T cells are primed to protect the brain during congenital viral infection.
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T cell development is fundamental to immune system establishment, yet how this development changes with age remains poorly understood. Here, we construct a transcriptional and epigenetic atlas of T cell developmental programs in neonatal and adult mice, revealing the ontogeny of divergent gene regulatory programs and their link to age-related differences in phenotype and function. Specifically, we identify a gene module that diverges with age from the earliest stages of genesis and includes programs that govern effector response and cell cycle regulation. Moreover, we reveal that neonates possess more accessible chromatin during early thymocyte development, likely establishing poised gene expression programs that manifest later in thymocyte development. Finally, we leverage this atlas, employing a CRISPR-based perturbation approach coupled with single-cell RNA sequencing as a readout to uncover a conserved transcriptional regulator, Zbtb20, that contributes to age-dependent differences in T cell development. Altogether, our study defines transcriptional and epigenetic programs that regulate age-specific differences in T cell development.
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Cellular programming of naïve T cells can improve the efficacy of adoptive T-cell therapy. However, the current ex vivo engineering of T cells requires the pre-activation of T cells, which causes them to lose their naïve state. In this study, cationic-polymer-functionalized nanowires were used to pre-program the fate of primary naïve CD8+ T cells to achieve a therapeutic response in vivo. This was done by delivering single or multiple microRNAs to primary naïve mouse and human CD8+ T cells without pre-activation. The use of nanowires further allowed for the delivery of large, whole lentiviral particles with potential for long-term integration. The combination of deletion and overexpression of miR-29 and miR-130 impacted the ex vivo T-cell differentiation fate from the naïve state. The programming of CD8+ T cells using nanowire-delivered co-delivery of microRNAs resulted in the modulation of T-cell fitness by altering the T-cell proliferation, phenotypic and transcriptional regulation, and secretion of effector molecules. Moreover, the in vivo adoptive transfer of murine CD8+ T cells programmed through the nanowire-mediated dual delivery of microRNAs provided enhanced immune protection against different types of intracellular pathogen (influenza and Listeria monocytogenes). In vivo analyses demonstrated that the simultaneous alteration of miR-29 and miR-130 levels in naïve CD8+ T cells reduces the persistence of canonical memory T cells whereas increases the population of short-lived effector T cells. Nanowires could potentially be used to modulate CD8+ T-cell differentiation and achieve a therapeutic response in vivo without the need for pre-activation.
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Linfocitos T CD8-positivos , MicroARNs , Nanocables , MicroARNs/genética , Animales , Nanocables/química , Linfocitos T CD8-positivos/inmunología , Ratones , Humanos , Diferenciación Celular , Ratones Endogámicos C57BLRESUMEN
CD8+ T cells are classically recognized as adaptive lymphocytes based on their ability to recognize specific foreign antigens and mount memory responses. However, recent studies indicate that some antigen-inexperienced CD8+ T cells can respond to innate cytokines alone in the absence of cognate T cell receptor stimulation, a phenomenon referred to as bystander activation. Here, we demonstrate that neonatal CD8+ T cells undergo a robust and diverse program of bystander activation, which corresponds to enhanced innate-like protection against unrelated pathogens. Using a multi-omics approach, we found that the ability of neonatal CD8+ T cells to respond to innate cytokines derives from their capacity to undergo rapid chromatin remodeling, resulting in the usage of a distinct set of enhancers and transcription factors typically found in innate-like T cells. We observed that the switch between innate and adaptive functions in the CD8+ T cell compartment is mediated by changes in the abundance of distinct subsets of cells. The innate CD8+ T cell subset that predominates in early life was also present in adult mice and humans. Our findings provide support for the layered immune hypothesis and indicate that the CD8+ T cell compartment is more functionally diverse than previously thought.
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Linfocitos T CD8-positivos , Inmunidad Innata , Humanos , Adulto , Ratones , Animales , Citocinas , Subgrupos de Linfocitos T , AntígenosRESUMEN
Chronic viral infections, such as HIV and hepatitis C virus, represent a major public health problem. Although it is well understood that neonates and adults respond differently to chronic viral infections, the underlying mechanisms remain unknown. In this study, we transferred neonatal and adult CD8+ T cells into a mouse model of chronic infection (lymphocytic choriomeningitis virus clone 13) and dissected out the key cell-intrinsic differences that alter their ability to protect the host. Interestingly, we found that neonatal CD8+ T cells preferentially became effector cells early in chronic infection compared with adult CD8+ T cells and expressed higher levels of genes associated with cell migration and effector cell differentiation. During the chronic phase of infection, the neonatal cells retained more immune functionality and expressed lower levels of surface markers and genes related to exhaustion. Because the neonatal cells protect from viral replication early in chronic infection, the altered differentiation trajectories of neonatal and adult CD8+ T cells is functionally significant. Together, our work demonstrates how cell-intrinsic differences between neonatal and adult CD8+ T cells influence key cell fate decisions during chronic infection.
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Coriomeningitis Linfocítica , Ratones , Animales , Infección Persistente , Virus de la Coriomeningitis Linfocítica , Linfocitos T CD8-positivos , Diferenciación Celular , Ratones Endogámicos C57BL , Enfermedad CrónicaRESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the ongoing global pandemic associated with morbidity and mortality in humans. Although disease severity correlates with immune dysregulation, the cellular mechanisms of inflammation and pathogenesis of COVID-19 remain relatively poorly understood. Here, we used mouse-adapted SARS-CoV-2 strain MA10 to investigate the role of adaptive immune cells in disease. We found that while infected wild-type mice lost ~10% weight by 3 to 4 days postinfection, rag-/- mice lacking B and T lymphocytes did not lose weight. Infected lungs at peak weight loss revealed lower pathology scores, fewer neutrophils, and lower interleukin-6 and tumor necrosis factor-α in rag-/- mice. Mice lacking αß T cells also had less severe weight loss, but adoptive transfer of T and B cells into rag-/- mice did not significantly change the response. Collectively, these findings suggest that while adaptive immune cells are important for clearing SARS-CoV-2 infection, this comes at the expense of increased inflammation and pathology.
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COVID-19 , SARS-CoV-2 , Humanos , Ratones , Animales , Linfocitos T , Inflamación , Pérdida de Peso , Modelos Animales de EnfermedadRESUMEN
Skeletal muscle regeneration is driven by the interaction of myogenic and non-myogenic cells. In aging, regeneration is impaired due to dysfunctions of myogenic and non-myogenic cells, but this is not understood comprehensively. We collected an integrated atlas of 273,923 single-cell transcriptomes from muscles of young, old, and geriatric mice (~5, 20, 26 months-old) at six time-points following myotoxin injury. We identified eight cell types, including T and NK cells and macrophage subtypes, that displayed accelerated or delayed response dynamics between ages. Through pseudotime analysis, we observed myogenic cell states and trajectories specific to old and geriatric ages. To explain these age differences, we assessed cellular senescence by scoring experimentally derived and curated gene-lists. This pointed to an elevation of senescent-like subsets specifically within the self-renewing muscle stem cells in aged muscles. This resource provides a holistic portrait of the altered cellular states underlying skeletal muscle regenerative decline across mouse lifespan.
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Therapies targeting oncogene addiction have had a tremendous impact on tumor growth and patient outcome, but drug resistance continues to be problematic. One approach to deal with the challenge of resistance entails extending anticancer treatments beyond targeting cancer cells by additionally altering the tumor microenvironment. Understanding how the tumor microenvironment contributes to the evolution of diverse resistance pathways could aid in the design of sequential treatments that can elicit and take advantage of a predictable resistance trajectory. Tumor-associated macrophages often support neoplastic growth and are frequently the most abundant immune cell found in tumors. Here, we used clinically relevant in vivo Braf-mutant melanoma models with fluorescent markers to track the stage-specific changes in macrophages under targeted therapy with Braf/Mek inhibitors and assessed the dynamic evolution of the macrophage population generated by therapy pressure-induced stress. During the onset of a drug-tolerant persister state, Ccr2+ monocyte-derived macrophage infiltration rose, suggesting that macrophage influx at this point could facilitate the onset of stable drug resistance that melanoma cells show after several weeks of treatment. Comparison of melanomas that develop in a Ccr2-proficient or -deficient microenvironment demonstrated that lack of melanoma infiltrating Ccr2+ macrophages delayed onset of resistance and shifted melanoma cell evolution towards unstable resistance. Unstable resistance was characterized by sensitivity to targeted therapy when factors from the microenvironment were lost. Importantly, this phenotype was reversed by coculturing melanoma cells with Ccr2+ macrophages. Overall, this study demonstrates that the development of resistance may be directed by altering the tumor microenvironment to improve treatment timing and the probability of relapse. SIGNIFICANCE: Ccr2+ melanoma macrophages that are active in tumors during the drug-tolerant persister state following targeted therapy-induced regression are key contributors directing melanoma cell reprogramming toward specific therapeutic resistance trajectories.
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Melanoma , Recurrencia Local de Neoplasia , Humanos , Melanoma/tratamiento farmacológico , Melanoma/genética , Melanoma/patología , Inmunoterapia , Macrófagos/metabolismo , Proteínas Proto-Oncogénicas B-raf , Resistencia a Antineoplásicos/genética , Inhibidores de Proteínas Quinasas/farmacología , Línea Celular Tumoral , Microambiente TumoralRESUMEN
Historically, the immune system was believed to develop along a linear axis of maturity from fetal life to adulthood. Now, it is clear that distinct layers of immune cells are generated from unique waves of hematopoietic progenitors during different windows of development. This model, known as the layered immune model, has provided a useful framework for understanding why distinct lineages of B cells and γδ T cells arise in succession and display unique functions in adulthood. However, the layered immune model has not been applied to CD8+ T cells, which are still often viewed as a uniform population of cells belonging to the same lineage, with functional differences between cells arising from environmental factors encountered during infection. Recent studies have challenged this idea, demonstrating that not all CD8+ T cells are created equally and that the functions of individual CD8+ T cells in adults are linked to when they were created in the host. In this review, we discuss the accumulating evidence suggesting there are distinct ontogenetic subpopulations of CD8+ T cells and propose that the layered immune model be extended to the CD8+ T cell compartment.
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Linfocitos T CD8-positivos , Sistema Inmunológico , Subgrupos de Linfocitos T , Humanos , Antígenos CD8/inmunología , Linfocitos T CD8-positivos/inmunología , Desarrollo Humano/fisiología , Sistema Inmunológico/citología , Sistema Inmunológico/crecimiento & desarrollo , Sistema Inmunológico/inmunología , Sistema Inmunológico/fisiología , Inmunidad/inmunología , Inmunidad/fisiología , Subgrupos de Linfocitos T/inmunologíaRESUMEN
CD8+ T lymphocytes infiltrate the brain during congenital CMV infection and promote viral clearance. However, the mechanisms by which CD8+ T cells are recruited to the brain remain unclear. Using a mouse model of congenital CMV, we found a gut-homing chemokine receptor (CCR9) was preferentially expressed in CD8+ T cells localized in the brain postinfection. In the absence of CCR9 or CCL25 (CCR9's ligand) expression, CD8+ T cells failed to migrate to key sites of infection in the brain and protect the host from severe forms of disease. Interestingly, we found that expression of CCR9 on CD8+ T cells was also responsible for spatial temporal positioning of T cells in the brain. Collectively, our data demonstrate that the CMV-infected brain uses a similar mechanism for CD8+ T cell homing as the small intestine.
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Infecciones por Citomegalovirus , Receptores CCR , Humanos , Receptores CCR/metabolismo , Linfocitos T CD8-positivos/metabolismo , Intestino Delgado/metabolismo , Infecciones por Citomegalovirus/metabolismo , Encéfalo/metabolismoRESUMEN
Microbial exposure during development can elicit long-lasting effects on the health of an individual. However, how microbial exposure in early life leads to permanent changes in the immune system is unknown. Here, we show that the microbial environment alters the set point for immune susceptibility by altering the developmental architecture of the CD8+ T cell compartment. In particular, early microbial exposure results in the preferential expansion of highly responsive fetal-derived CD8+ T cells that persist into adulthood and provide the host with enhanced immune protection against intracellular pathogens. Interestingly, microbial education of fetal-derived CD8+ T cells occurs during thymic development rather than in the periphery and involves the acquisition of a more effector-like epigenetic program. Collectively, our results provide a conceptual framework for understanding how microbial colonization in early life leads to lifelong changes in the immune system.
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Linfocitos T CD8-positivos , Feto , Inmunidad , Diferenciación Celular , Escolaridad , Epigenómica , Feto/inmunología , Feto/microbiologíaRESUMEN
The fate-mapping mouse has become an essential tool in the immunologist's toolbox. Although traditionally used by developmental biologists to trace the origins of cells, immunologists are turning to fate-mapping to better understand the development and function of immune cells. Thus, an expansion in the variety of fate-mapping mouse models has occurred to answer fundamental questions about the immune system. These models are also being combined with new genetic tools to study cancer, infection, and autoimmunity. In this review, we summarize different types of fate-mapping mice and describe emerging technologies that might allow immunologists to leverage this valuable tool and expand our functional knowledge of the immune system.
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Tecnología , Animales , Linaje de la Célula , Humanos , Ratones , Ratones TransgénicosRESUMEN
MicroRNAs (miRNAs) have emerged as critical regulators of cell fate in the CD8+ T cell response to infection. Although there are several examples of miRNAs acting on effector CD8+ T cells after infection, it is unclear whether differential expression of one or more miRNAs in the naive state is consequential in altering their long-term trajectory. To answer this question, we examine the role of miR-29 in neonatal and adult CD8+ T cells, which express different amounts of miR-29 only prior to infection and adopt profoundly different fates after immune challenge. We find that manipulation of miR-29 expression in the naive state is sufficient for age-adjusting the phenotype and function of CD8+ T cells, including their regulatory landscapes and long-term differentiation trajectories after infection. Thus, miR-29 acts as a developmental switch by controlling the balance between a rapid effector response in neonates and the generation of long-lived memory in adults.
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Linfocitos T CD8-positivos/inmunología , Memoria Inmunológica , Listeriosis/inmunología , Activación de Linfocitos/inmunología , MicroARNs/genética , Adolescente , Adulto , Factores de Edad , Animales , Linfocitos T CD8-positivos/microbiología , Diferenciación Celular , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Humanos , Listeria monocytogenes/inmunología , Listeriosis/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Adulto JovenRESUMEN
We are just beginning to understand the diversity of the peripheral T cell compartment, which arises from the specialization of different T cell subsets and the plasticity of individual naive T cells to adopt different fates. Although the progeny of a single T cell can differentiate into many phenotypes following infection, individual T cells are biased towards particular phenotypes. These biases are typically ascribed to random factors that occur during and after antigenic stimulation. However, the T cell compartment does not remain static with age, and shifting immune challenges during ontogeny give rise to T cells with distinct functional properties. Here, we argue that the developmental history of naive T cells creates a 'hidden layer' of diversity that persists into adulthood. Insight into this diversity can provide a new perspective on immunity and immunotherapy across the lifespan.
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Inmunidad Celular/inmunología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Animales , Diferenciación Celular/inmunología , Humanos , Memoria Inmunológica/inmunología , Ratones , Receptores de Antígenos de Linfocitos T/inmunologíaRESUMEN
Neonatal CD4+ and CD8+ T cells have historically been characterized as immature or defective. However, recent studies prompt a reinterpretation of the functions of neonatal T cells. Rather than a population of cells always falling short of expectations set by their adult counterparts, neonatal T cells are gaining recognition as a distinct population of lymphocytes well suited for the rapidly changing environment in early life. In this review, I will highlight new evidence indicating that neonatal T cells are not inert or less potent versions of adult T cells but instead are a broadly reactive layer of T cells poised to quickly develop into regulatory or effector cells, depending on the needs of the host. In this way, neonatal T cells are well adapted to provide fast-acting immune protection against foreign pathogens, while also sustaining tolerance to self-antigens.
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Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Inmunidad Adaptativa , Animales , Biomarcadores , Diferenciación Celular/inmunología , Interacciones Huésped-Patógeno , Humanos , Memoria Inmunológica , Activación de Linfocitos/inmunología , Células Progenitoras Linfoides/citología , Células Progenitoras Linfoides/inmunología , Células Progenitoras Linfoides/metabolismo , Fenotipo , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/metabolismo , Transducción de Señal , Subgrupos de Linfocitos T/citologíaRESUMEN
Neonates often develop poor immunity against intracellular pathogens. Because CD8+ T cells are essential for eliminating infectious agents, it is crucial to understand why they behave differently in early life. Previous studies in mice have demonstrated that neonatal CD8+ T cells fail to form memory because of an intrinsic propensity to differentiate into short-lived effectors. However, the underlying mechanisms remain undefined. We now show that neonatal CD8+ T cells exhibit higher glycolytic activity than adult CD8+ T cells postinfection, which may be due to age-related differences in Lin28b expression. Importantly, when glycolysis is pharmacologically inhibited, the impaired formation of neonatal memory CD8+ T cells can be restored. Collectively, these data suggest that neonatal CD8+ T cells are inherently biased toward undergoing glycolytic metabolism postinfection, which compromises their ability to develop into memory CD8+ T cells in early life.
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Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Glucólisis/inmunología , Memoria Inmunológica/inmunología , Traslado Adoptivo/métodos , Animales , Animales Recién Nacidos , Linfocitos T CD8-positivos/efectos de los fármacos , Células Cultivadas , Desoxiglucosa/farmacología , Glucólisis/efectos de los fármacos , Memoria Inmunológica/efectos de los fármacos , Interleucina-2/farmacología , Listeria monocytogenes/inmunología , Listeriosis/inmunología , Listeriosis/microbiología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismoRESUMEN
It is well known that males and females respond differently to intracellular pathogens. Females mount a more robust immune response than males, which decreases their susceptibility to infection but comes at the cost of increasing immunopathology. However, the underlying basis for sex-specific differences in the CD8+ T cell response to infection remains poorly understood. In this study, we show that female CD8+ T cells have an intrinsic propensity to become short-lived effectors, whereas male CD8+ T cells give rise to more memory precursor effector cells after murine infection with either a virus (vaccinia virus) or bacteria (Listeria monocytogenes). Interestingly, we found that the propensity of female CD8+ T cells to form short-lived effectors is not because they respond to lower amounts of cognate Ag but rather because they have an enhanced capacity to respond to IL-12, which facilitates more effector cell differentiation at each round of cell division. Our findings provide key insights into the sex-based immunological differences that underlie variations in the susceptibility to infection in males and females. ImmunoHorizons, 2019, 3: 121-132.
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Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Interacciones Huésped-Patógeno , Infecciones/etiología , Infecciones/metabolismo , Interleucina-12/metabolismo , Traslado Adoptivo , Animales , Antígenos/inmunología , Linfocitos T CD8-positivos/citología , Diferenciación Celular/inmunología , Modelos Animales de Enfermedad , Femenino , Interacciones Huésped-Patógeno/inmunología , Inmunofenotipificación , Masculino , Ratones , Ratones Noqueados , Factores SexualesRESUMEN
Accumulating evidence indicates that the immune system does not develop in a linear fashion, but rather as distinct developmental layers formed from sequential waves of hematopoietic stem cells, each giving rise to unique populations of immune cells at different stages of development. Although recent studies have indicated that conventional CD8+ T cells produced in early life persist into adulthood and exhibit distinct roles during infection, the developmental architecture of the peripheral T cell compartment remains undefined. In this study, we used a mouse model to permanently label CD8+ T cells produced during distinct windows of development and traced their history to generate fate maps of CD8+ T cells produced during different stages of life. We then used mathematical modeling to understand the age structure of the CD8+ T cell compartment across the lifespan. Interestingly, we found that survival rate of CD8+ T cells depends on both the age and developmental origin of the cells. Recently produced cells show an initial rapid decay rate, which slows with age of the animal at which the cells were produced. For cells produced at any age, the rate of decay also slows with the age of the cell. We derive a function to describe this and predict the "age distribution" of the CD8+ T cell pool for animals of any given age. These data provide a quantitative framework for understanding the ontogeny of the CD8+ T cell compartment and help to contextualize age-related changes in the CD8+ T cell response to infection.
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Envejecimiento/inmunología , Linfocitos T CD8-positivos/inmunología , Modelos Inmunológicos , Envejecimiento/genética , Animales , Linfocitos T CD8-positivos/citología , Ratones , Ratones TransgénicosRESUMEN
Heterogeneity is a hallmark feature of the adaptive immune system in vertebrates. Following infection, naive T cells differentiate into various subsets of effector and memory T cells, which help to eliminate pathogens and maintain long-term immunity. The current model suggests there is a single lineage of naive T cells that give rise to different populations of effector and memory T cells depending on the type and amounts of stimulation they encounter during infection. Here, we have discovered that multiple sub-populations of cells exist in the naive CD8+ T cell pool that are distinguished by their developmental origin, unique transcriptional profiles, distinct chromatin landscapes, and different kinetics and phenotypes after microbial challenge. These data demonstrate that the naive CD8+ T cell pool is not as homogeneous as previously thought and offers a new framework for explaining the remarkable heterogeneity in the effector and memory T cell subsets that arise after infection.
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Linfocitos T CD8-positivos/inmunología , Genes del Desarrollo , Listeria monocytogenes/patogenicidad , Animales , Linfocitos T CD8-positivos/efectos de los fármacos , Linfocitos T CD8-positivos/metabolismo , Diferenciación Celular , Línea Celular Tumoral , Cromatina/metabolismo , Citocinas/farmacología , Epítopos de Linfocito T/genética , Epítopos de Linfocito T/metabolismo , Memoria Inmunológica , Interferón gamma/metabolismo , Células Asesinas Naturales/citología , Células Asesinas Naturales/metabolismo , Listeria monocytogenes/metabolismo , Ratones , Ratones Endogámicos C57BL , Análisis de Componente Principal , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Timo/trasplante , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , TranscriptomaRESUMEN
During the ontogeny of the mammalian immune system, distinct lineages of cells arise from fetal and adult hematopoietic stem cells (HSCs) during specific stages of development. However, in some cases, the same immune cell type is produced by both HSC populations, resulting in the generation of phenotypically similar cells with distinct origins and divergent functional properties. In this report, we demonstrate that neonatal CD8+ T cells preferentially become short-lived effectors and adult CD8+ T cells selectively form long-lived memory cells after infection because they are derived from distinct progenitor cells. Notably, we find that naïve neonatal CD8+ T cells originate from a progenitor cell that is distinguished by expression of Lin28b. Remarkably, ectopic expression of Lin28b enables adult progenitors to give rise to CD8+ T cells that are phenotypically and functionally analogous to those found in neonates. These findings suggest that neonatal and adult CD8+ T cells belong to separate lineages of CD8+ T cells, and potentially explain why it is challenging to elicit memory CD8+ T cells in early life.