RESUMEN
Influenza A virus (IAV) infection leads to the formation of mucosal memory CD4 T cells that can protect the host. An in-depth understanding of the signals that shape memory cell development is required for more effective vaccine design. We have examined the formation of memory CD4 T cells in the lung following IAV infection of mice, characterizing changes to the lung landscape and immune cell composition. IAV-specific CD4 T cells were found throughout the lung at both primary and memory time points. These cells were found near lung airways and in close contact with a range of immune cells including macrophages, dendritic cells, and B cells. Interactions between lung IAV-specific CD4 T cells and major histocompatibility complex (MHC)II+ cells during the primary immune response were important in shaping the subsequent memory pool. Treatment with an anti-MHCII blocking antibody increased the proportion of memory CD4 T cells found in lung airways but reduced interferon-γ expression by IAV-specific immunodominant memory CD4 T cells. The immunodominant CD4 T cells expressed higher levels of programmed death ligand 1 (PD1) than other IAV-specific CD4 T cells and PD1+ memory CD4 T cells were located further away from MHCII+ cells than their PD1-low counterparts. This distinction in location was lost in mice treated with anti-MHCII antibodies. These data suggest that sustained antigen presentation in the lung impacts the formation of memory CD4 T cells by regulating their cytokine production and location.
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Interferon gamma (IFNγ) is a potent antiviral cytokine that can be produced by many innate and adaptive immune cells during infection. Currently, our understanding of which cells produce IFNγ and where they are located at different stages of an infection is limited. We have used reporter mice to investigate in vivo expression of Ifnγ mRNA in the lung and secondary lymphoid organs during and following influenza A virus (IAV) infection. We observed a triphasic production of Ifnγ expression. Unconventional T cells and innate lymphoid cells, particularly NK cells, were the dominant producers of early Ifnγ, while CD4 and CD8 T cells were the main producers by day 10 post-infection. Following viral clearance, some memory CD4 and CD8 T cells continued to express Ifnγ in the lungs and draining lymph node. Interestingly, Ifnγ production by lymph node natural killer (NK), NKT, and innate lymphoid type 1 cells also continued to be above naïve levels, suggesting memory-like phenotypes for these cells. Analysis of the localization of Ifnγ+ memory CD4 and CD8 T cells demonstrated that cytokine+ T cells were located near airways and in the lung parenchyma. Following a second IAV challenge, lung IAV-specific CD8 T cells rapidly increased their expression of Ifnγ while CD4 T cells in the draining lymph node increased their Ifnγ response. Together, these data suggest that Ifnγ production fluctuates based on cellular source and location, both of which could impact subsequent immune responses.
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Cytokine production by memory T cells is a key mechanism of T cell mediated protection. However, we have limited understanding of the persistence of cytokine producing T cells during memory cell maintenance and secondary responses. We interrogated antigen-specific CD4 T cells using a mouse influenza A virus infection model. Although CD4 T cells detected using MHCII tetramers declined in lymphoid and non-lymphoid organs, we found similar numbers of cytokine+ CD4 T cells at days 9 and 30 in the lymphoid organs. CD4 T cells with the capacity to produce cytokines expressed higher levels of pro-survival molecules, CD127 and Bcl2, than non-cytokine+ cells. Transcriptomic analysis revealed a heterogeneous population of memory CD4 T cells with three clusters of cytokine+ cells. These clusters match flow cytometry data and reveal an enhanced survival signature in cells capable of producing multiple cytokines. Following re-infection, multifunctional T cells expressed low levels of the proliferation marker, Ki67, whereas cells that only produce the anti-viral cytokine, interferon-γ, were more likely to be Ki67+ . Despite this, multifunctional memory T cells formed a substantial fraction of the secondary memory pool. Together these data indicate that survival rather than proliferation may dictate which populations persist within the memory pool.
Asunto(s)
Linfocitos T CD4-Positivos , Virus de la Influenza A , Linfocitos T CD4-Positivos/metabolismo , Antígeno Ki-67 , Citocinas/metabolismo , Interferón gamma/metabolismo , Memoria InmunológicaRESUMEN
Spillover events of avian influenza A viruses (IAVs) to humans could represent the first step in a future pandemic1. Several factors that limit the transmission and replication of avian IAVs in mammals have been identified. There are several gaps in our understanding to predict which virus lineages are more likely to cross the species barrier and cause disease in humans1. Here, we identified human BTN3A3 (butyrophilin subfamily 3 member A3)2 as a potent inhibitor of avian IAVs but not human IAVs. We determined that BTN3A3 is expressed in human airways and its antiviral activity evolved in primates. We show that BTN3A3 restriction acts primarily at the early stages of the virus life cycle by inhibiting avian IAV RNA replication. We identified residue 313 in the viral nucleoprotein (NP) as the genetic determinant of BTN3A3 sensitivity (313F or, rarely, 313L in avian viruses) or evasion (313Y or 313V in human viruses). However, avian IAV serotypes, such as H7 and H9, that spilled over into humans also evade BTN3A3 restriction. In these cases, BTN3A3 evasion is due to substitutions (N, H or Q) in NP residue 52 that is adjacent to residue 313 in the NP structure3. Thus, sensitivity or resistance to BTN3A3 is another factor to consider in the risk assessment of the zoonotic potential of avian influenza viruses.
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Aves , Interacciones Microbiota-Huesped , Virus de la Influenza A , Gripe Aviar , Gripe Humana , Zoonosis Virales , Animales , Humanos , Aves/virología , Virus de la Influenza A/clasificación , Virus de la Influenza A/genética , Virus de la Influenza A/crecimiento & desarrollo , Virus de la Influenza A/aislamiento & purificación , Gripe Aviar/transmisión , Gripe Aviar/virología , Gripe Humana/prevención & control , Gripe Humana/transmisión , Gripe Humana/virología , Primates , Sistema Respiratorio/metabolismo , Sistema Respiratorio/virología , Medición de Riesgo , Zoonosis Virales/prevención & control , Zoonosis Virales/transmisión , Zoonosis Virales/virología , Replicación ViralRESUMEN
The lung is frequently and repeatedly exposed to invading pathogens and thus requires constant immunosurveillance. Professional antigen presenting cells (APCs), including dendritic cells, engulf invading pathogens and present their peptides via major histocompatibility complexes (MHC) I and II, to CD8 or CD4 T cells. Epithelial cells and stromal cells (including fibroblasts) provide more than structural support, they are increasingly recognised as key players in the immune response, acting as non-professional APCs through interactions with antigen experienced T cells that migrate to the lung. The importance of the contributions of non-professional and professional APCs to T cell function in vivo, is currently unclear. This review summarises the roles of professional and non-professional APCs in lung immunity, at the steady state and following viral insult, with particular emphasis on their ability to interact with and influence T cells.
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Presentación de Antígeno , Células Presentadoras de Antígenos , Humanos , Linfocitos T CD4-Positivos , Pulmón , Complejo Mayor de HistocompatibilidadRESUMEN
PURPOSE: Low-dose whole lung radiation therapy (LDLR) has been proposed as a treatment for patients with acute respiratory distress syndrome associated with SARS-CoV-2 infection, and clinical trials are underway. There is an urgent need for preclinical evidence to justify this approach and inform dose, scheduling, and mechanisms of action. METHODS AND MATERIALS: Female C57BL/6 mice were treated with intranasal bleomycin sulfate (7.5 or 11.25 units/kg, day 0) and then exposed to whole lung radiation therapy (0.5, 1.0, or 1.5 Gy, or sham; day 3). Bodyweight was measured daily, and lung tissue was harvested for histology and flow cytometry on day 10. Computed tomography lung imaging was performed before radiation (day 3) and pre-endpoint (day 10). RESULTS: Bleomycin caused pneumonitis of variable severity, which correlated with weight loss. LDLR at 1.0 Gy was associated with a significant increase in the proportion of mice recovering to 98% of initial bodyweight, and a proportion of these mice exhibited less severe histopathologic lung changes. Mice experiencing moderate initial weight loss were more likely to respond to LDLR than those experiencing severe initial weight loss. In addition, LDLR (1.0 Gy) significantly reduced bleomycin-induced increases in interstitial macrophages, CD103+ dendritic cells (DCs), and neutrophil-DC hybrids. Overall, bleomycin-treated mice exhibited significantly higher percentages of nonaerated lung in left than right lungs, and LDLR (1.0 Gy) limited further reductions in aerated lung volume in right but not left lungs. LDLR at 0.5 and 1.5 Gy did not improve bodyweight, flow cytometric, or radiologic readouts of bleomycin-induced pneumonitis. CONCLUSIONS: Our data support the concept that LDLR can ameliorate acute inflammatory lung injury, identify 1.0 Gy as the most effective dose, and provide evidence that it is more effective in the context of moderate than severe pneumonitis. Mechanistically, LDLR at 1.0 Gy significantly suppressed bleomycin-induced accumulation of pulmonary interstitial macrophages, CD103+ DCs, and neutrophil-DC hybrids.
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Neumonía , Radioterapia , Animales , Bleomicina , COVID-19/radioterapia , Modelos Animales de Enfermedad , Femenino , Humanos , Pulmón/diagnóstico por imagen , Ratones , Ratones Endogámicos C57BL , Neumonía/inducido químicamente , Pérdida de PesoRESUMEN
Communication between stromal and immune cells is essential to maintain tissue homeostasis, mount an effective immune response and promote tissue repair. This 'crosstalk' occurs in both the steady state and following a variety of insults, for example, in response to local injury, at sites of infection or cancer. What do we mean by crosstalk between cells? Reciprocal activation and/or regulation occurs between immune and stromal cells, by direct cell contact and indirect mechanisms, including the release of soluble cytokines. Moving beyond cell-to-cell contact, this review investigates the complexity of 'cross-space' cellular communication. We highlight different examples of cellular communication by a variety of lung stromal and immune cells following tissue insults. This review examines how the 'geography of the lung microenvironment' is altered in various disease states; more specifically, we investigate how this influences lung epithelial cells and fibroblasts via their communication with immune cells and each other.
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Linfocitos T CD8-positivos/inmunología , Células Epiteliales/inmunología , Fibroblastos/inmunología , Pulmón/patología , Células del Estroma/inmunología , Animales , Comunicación Celular , Microambiente Celular , Humanos , Inmunidad CelularRESUMEN
Memory T cells respond rapidly in part because they are less reliant on a heightened levels of costimulatory molecules. This enables rapid control of secondary infecting pathogens but presents challenges to efforts to control or silence memory CD4 T cells, for example in antigen-specific tolerance strategies for autoimmunity. We have examined the transcriptional and functional consequences of reactivating memory CD4 T cells in the absence of an adjuvant. We find that memory CD4 T cells generated by infection or immunisation survive secondary activation with antigen delivered without adjuvant, regardless of their location in secondary lymphoid organs or peripheral tissues. These cells were, however, functionally altered following a tertiary immunisation with antigen and adjuvant, proliferating poorly but maintaining their ability to produce inflammatory cytokines. Transcriptional and cell cycle analysis of these memory CD4 T cells suggests they are unable to commit fully to cell division potentially because of low expression of DNA repair enzymes. In contrast, these memory CD4 T cells could proliferate following tertiary reactivation by viral re-infection. These data indicate that antigen-specific tolerogenic strategies must examine multiple parameters of Tcell function, and provide insight into the molecular mechanisms that may lead to deletional tolerance of memory CD4 T cells.
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Linfocitos T CD4-Positivos/inmunología , Tolerancia Inmunológica/inmunología , Memoria Inmunológica/inmunología , Animales , Antígenos/inmunología , Autoinmunidad/inmunología , Ciclo Celular/inmunología , Proliferación Celular/fisiología , Citocinas/inmunología , Reparación del ADN/inmunología , Femenino , Inflamación/inmunología , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Transcripción Genética/inmunologíaRESUMEN
RNA viruses are a major human health threat. The life cycles of many highly pathogenic RNA viruses like influenza A virus (IAV) and Lassa virus depends on host mRNA, because viral polymerases cleave 5'-m7G-capped host transcripts to prime viral mRNA synthesis ("cap-snatching"). We hypothesized that start codons within cap-snatched host transcripts could generate chimeric human-viral mRNAs with coding potential. We report the existence of this mechanism of gene origination, which we named "start-snatching." Depending on the reading frame, start-snatching allows the translation of host and viral "untranslated regions" (UTRs) to create N-terminally extended viral proteins or entirely novel polypeptides by genetic overprinting. We show that both types of chimeric proteins are made in IAV-infected cells, generate T cell responses, and contribute to virulence. Our results indicate that during infection with IAV, and likely a multitude of other human, animal and plant viruses, a host-dependent mechanism allows the genesis of hybrid genes.
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Caperuzas de ARN/genética , Infecciones por Virus ARN/genética , Proteínas Recombinantes de Fusión/genética , Regiones no Traducidas 5'/genética , Animales , Bovinos , Línea Celular , Cricetinae , Perros , Humanos , Virus de la Influenza A/metabolismo , Ratones , Proteínas Mutantes Quiméricas/genética , Proteínas Mutantes Quiméricas/metabolismo , Sistemas de Lectura Abierta/genética , Caperuzas de ARN/metabolismo , Infecciones por Virus ARN/metabolismo , Virus ARN/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Viral/metabolismo , ARN Polimerasa Dependiente del ARN/genética , ARN Polimerasa Dependiente del ARN/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Transcripción Genética/genética , Proteínas Virales/metabolismo , Replicación Viral/genéticaRESUMEN
FoxP3+ regulatory T cells (Tregs) control inflammation and maintain mucosal homeostasis, but their functions during infection are poorly understood. Th1, Th2, and Th17 cells can be identified by master transcription factors (TFs) T-bet, GATA3, and RORγT; Tregs also express these TFs. While T-bet+ Tregs can selectively suppress Th1 cells, it is unclear whether distinct Treg populations can alter Th bias. To address this, we used Salmonella enterica serotype Typhimurium to induce nonlethal colitis. Following infection, we observed an early colonic Th17 response within total CD4 T cells, followed by a Th1 bias. The early Th17 response, which contains both Salmonella-specific and non-Salmonella-specific cells, parallels an increase in T-bet+ Tregs. Later, Th1 cells and RORγT+ Tregs dominate. This reciprocal dynamic may indicate that Tregs selectively suppress Th cells, shaping the immune response. Treg depletion 1-2 days post-infection shifted the early Th17 response to a Th1 bias; however, Treg depletion 6-7 days post-infection abrogated the Th1 bias. Thus, Tregs are necessary for the early Th17 response, and for a maximal Th1 response later. These data show that Tregs shape the overall tissue CD4 T cell response and highlight the potential for subpopulations of Tregs to be used in targeted therapeutic approaches.
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Infecciones por Salmonella/inmunología , Salmonella/fisiología , Subgrupos de Linfocitos T/inmunología , Linfocitos T Reguladores/inmunología , Animales , Diferenciación Celular , Microambiente Celular , Factores de Transcripción Forkhead/genética , Activación de Linfocitos , Depleción Linfocítica , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismoRESUMEN
Analysis of chemokine receptor, and atypical chemokine receptor, expression is frequently hampered by the lack of availability of high-quality antibodies and the species specificity of those that are available. We have previously described methodology utilizing Alexa-Fluor-labeled chemokine ligands as versatile reagents to detect receptor expression. Previously this has been limited to hematopoietic cells and methodology for assessing expression of receptors on stromal cells has been lacking. Among chemokine receptors, the ones most frequently expressed on stromal cells belong to the atypical chemokine receptor subfamily. These receptors do not signal in the classic sense in response to ligand but scavenge their ligands and degrade them and thus sculpt in vivo chemokine gradients. Here, we demonstrate the ability to use either intratracheal or intravenous, Alexa-Fluor-labeled chemokine administration to detect stromal cell populations expressing the atypical chemokine receptor ACKR2. Using this methodology, we demonstrate, for the first time, expression of ACKR2 on blood endothelial cells. This observation sets the lung aside from other tissues in which ACKR2 is exclusively expressed on lymphatic endothelial cells and suggest unique roles for ACKR2 in the pulmonary environment.
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Células Endoteliales/inmunología , Pulmón/inmunología , Receptores de Quimiocina/inmunología , Células del Estroma/inmunología , Animales , Carbocianinas/química , Células Endoteliales/citología , Molécula de Adhesión Celular Epitelial/genética , Molécula de Adhesión Celular Epitelial/inmunología , Citometría de Flujo , Colorantes Fluorescentes/química , Expresión Génica , Pulmón/irrigación sanguínea , Pulmón/citología , Ratones , Ratones Noqueados , Receptores de Quimiocina/genética , Coloración y Etiquetado/métodos , Células del Estroma/citologíaRESUMEN
T cell protective immunity is associated with multifunctional memory cells that produce several different cytokines. Currently, our understanding of when and how these cells are generated is limited. We have used an influenza virus mouse infection model to investigate whether the cytokine profile of memory T cells is reflective of primary responding cells or skewed toward a distinct profile. We found that, in comparison to primary cells, memory T cells tended to make multiple cytokines simultaneously. Analysis of the timings of release of cytokine by influenza virus-specific T cells, demonstrated that primary responding CD4 T cells from lymphoid organs were unable to produce a sustained cytokine response. In contrast CD8 T cells, memory CD4 T cells, and primary responding CD4 T cells from the lung produced a sustained cytokine response throughout the restimulation period. Moreover, memory CD4 T cells were more resistant than primary responding CD4 T cells to inhibitors that suppress T cell receptor signaling. Together, these data suggest that memory CD4 T cells display superior cytokine responses compared to primary responding cells. These data are key to our ability to identify the cues that drive the generation of protective memory CD4 T cells following infection.
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Antígenos Virales/farmacología , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD8-positivos/efectos de los fármacos , Regulación de la Expresión Génica/inmunología , Inmunidad Celular/efectos de los fármacos , Memoria Inmunológica , Animales , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/citología , Linfocitos T CD8-positivos/inmunología , Células Dendríticas/citología , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Femenino , Inmunidad Celular/genética , Inmunofenotipificación , Virus de la Influenza A/química , Virus de la Influenza A/inmunología , Interferón gamma/genética , Interferón gamma/inmunología , Interleucina-2/genética , Interleucina-2/inmunología , Pulmón/citología , Pulmón/efectos de los fármacos , Pulmón/inmunología , Ganglios Linfáticos/citología , Ganglios Linfáticos/efectos de los fármacos , Ganglios Linfáticos/inmunología , Activación de Linfocitos/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL , Especificidad de Órganos , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/inmunología , Bazo/citología , Bazo/efectos de los fármacos , Bazo/inmunología , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
Currently, we lack an understanding of the individual and combinatorial roles for chemokine receptors in the inflammatory process. We report studies on mice with a compound deletion of Ccr1, Ccr2, Ccr3, and Ccr5, which together control monocytic and eosinophilic recruitment to resting and inflamed sites. Analysis of resting tissues from these mice, and mice deficient in each individual receptor, provides clear evidence for redundant use of these receptors in establishing tissue-resident monocytic cell populations. In contrast, analysis of cellular recruitment to inflamed sites provides evidence of specificity of receptor use for distinct leukocyte subtypes and no indication of comprehensive redundancy. We find no evidence of involvement of any of these receptors in the recruitment of neutrophils or lymphocytes to resting or acutely inflamed tissues. Our data shed important light on combinatorial inflammatory chemokine receptor function and highlight Ccr2 as the primary driver of myelomonocytic cell recruitment in acutely inflamed contexts.
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Eosinófilos/inmunología , Inflamación/inmunología , Monocitos/inmunología , Receptores CCR/inmunología , Animales , Quimiocinas/inmunología , Quimiocinas/metabolismo , Eosinófilos/metabolismo , Perfilación de la Expresión Génica/métodos , Inflamación/genética , Inflamación/metabolismo , Linfocitos/inmunología , Linfocitos/metabolismo , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Monocitos/metabolismo , Neutrófilos/inmunología , Neutrófilos/metabolismo , Receptores CCR/genética , Receptores CCR/metabolismo , Receptores CCR1/inmunología , Receptores CCR1/metabolismo , Receptores CCR2/inmunología , Receptores CCR2/metabolismo , Receptores CCR3/inmunología , Receptores CCR3/metabolismo , Receptores CCR5/inmunología , Receptores CCR5/metabolismoRESUMEN
OBJECTIVE: The principal objective was to test the effectiveness of an online learning tool to improve midwives' accuracy of blood loss estimations in a birthing pool environment. The secondary objective was to assess the acceptability of the online learning tool to the midwives using it. DESIGN: A one group pre-test, post-test experiment with immediate and six weeks follow-up to test ability together with an online questionnaire to assess perceived usefulness of an online learning tool. SETTING: A large NHS maternity hospital comprising an acute care obstetric unit, a small district unit labour ward, one alongside midwifery-led unit and three freestanding midwifery-led units. PARTICIPANTS: Volunteer NHS employed midwives who had experience in caring for women labouring and giving birth in water (nâ¯=â¯24). INTERVENTION: An online learning tool comprising six randomly ordered short video simulations of blood loss in a birthing pool in real time, and a tutorial giving verbal and pictorial guidance on making accurate blood loss estimations in water was developed then piloted. Midwives' accuracy scores for estimating blood loss in each of the videos were calculated at three timepoints; pre and immediately post the learning component, and six weeks later. The estimated blood loss volume was subtracted from the actual blood loss volume, to give the difference between estimated and real blood loss in millilitres (ml) which was then converted to percentage difference to standardise comparison across the six volumes. The differences between pre- and post-learning for each of the six blood volumes was analysed using a repeated measures ANOVA. Statistical significance was set at pâ¯<â¯0.05. An online questionnaire incorporated questions using Likert scales to gauge confidence and competence and free text. Free text responses were analysed using a modified form of inductive content analysis. FINDINGS: Twenty-two midwives completed the online learning and immediate post-test, 14 completed a post-test after six weeks, and 15 responded to the online questionnaire. Pre-test results showed under-estimation of all blood loss volumes and particularly for the two largest volumes (1000 and 1100â¯ml). Across all volumes, accuracy of estimation was significantly improved at post-test 1. Accuracy diminished slightly, but overall improvement remained, at post-test 2. Participants rated the online tool positively and made suggestions for refining it. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: This is the first study measuring the accuracy of midwives' blood loss estimations in a birthing pool using real-time simulations and testing the effectiveness of an online learning tool to improve this important skill. Our findings indicate a need to develop interventions to improve midwives' accuracy at visually estimating blood loss in water, and the potential of an online approach. Most women who labour and/or give birth in water do so in midwifery-led settings without immediate access to medical support. Accuracy in blood loss estimations is an essential core skill.
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Educación Continua en Enfermería/normas , Hemorragia/clasificación , Partería/normas , Parto Normal/clasificación , Estadística como Asunto/normas , Adulto , Análisis de Varianza , Competencia Clínica/normas , Educación a Distancia/métodos , Educación a Distancia/normas , Educación Continua en Enfermería/métodos , Femenino , Hemorragia/etiología , Humanos , Internet , Partería/métodos , Parto Normal/métodos , Embarazo , Evaluación de Programas y Proyectos de Salud/métodos , Investigación Cualitativa , Medicina Estatal/organización & administración , Estadística como Asunto/métodos , Encuestas y CuestionariosRESUMEN
Chemokines have been shown to be essential players in a range of cancer contexts. In this study, we demonstrate that mice deficient in the atypical chemokine receptor Ackr2 display impaired development of metastasis in vivo in both cell line and spontaneous models. Further analysis reveals that this relates to increased expression of the chemokine receptor CCR2, specifically by KLRG1+ NK cells from the Ackr2-/- mice. This leads to increased recruitment of KLRG1+ NK cells to CCL2-expressing tumors and enhanced tumor killing. Together, these data indicate that Ackr2 limits the expression of CCR2 on NK cells and restricts their tumoricidal activity. Our data have important implications for our understanding of the roles for chemokines in the metastatic process and highlight Ackr2 and CCR2 as potentially manipulable therapeutic targets in metastasis.
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Células Asesinas Naturales/inmunología , Neoplasias Experimentales/inmunología , Receptores de Quimiocina/metabolismo , Animales , Carcinoma Pulmonar de Lewis , Movimiento Celular , Quimiocina CCL2/metabolismo , Citotoxicidad Inmunológica , Lectinas Tipo C , Melanoma Experimental , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Metástasis de la Neoplasia , Receptores CCR2/metabolismo , Receptores de Quimiocina/genética , Receptores Inmunológicos/metabolismoRESUMEN
Immunological memory provides rapid protection to pathogens previously encountered through infection or vaccination. CD4 T-cells play a central role in all adaptive immune responses. Vaccines must, therefore, activate CD4 T-cells if they are to generate protective immunity. For many diseases, we do not have effective vaccines. These include human immunodeficiency virus (HIV), tuberculosis and malaria, which are responsible for many millions of deaths each year across the globe. CD4 T-cells play many different roles during the immune response coordinating the actions of many other cells. In order to harness the diverse protective effects of memory CD4 T-cells, we need to understand how memory CD4 T-cells are generated and how they protect the host. Here we review recent findings on the location of different subsets of memory CD4 T-cells that are found in peripheral tissues (tissue resident memory T-cells) and in the circulation (central and effector memory T-cells). We discuss the generation of these cells, and the evidence that demonstrates how they provide immune protection in animal and human challenge models.
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Inflammation can be protective or pathogenic depending on context and timeframe. Acute inflammation, including the accumulation of CD4 T cells, accompanies protective immune responses to pathogens, but the presence of activated CD4 T cells at sites of inflammation is associated with chronic inflammatory disease. While significant progress has been made in understanding the migration of CD4 T cells into inflamed sites, the signals that lead to their persistence are poorly characterized. Using a murine ear model of acute inflammation and intravital two-photon imaging, we have dissected the signals that mediate CD4 T cell persistence. We report the unexpected finding that the bioactive lipid, sphingosine-1-phosphate (S1P), is both necessary and sufficient for the persistence of activated CD4 T cells at peripheral tissues in acute inflammation. S1P mediated the enhanced motility of CD4 T cells at inflamed tissues but did not affect their migration to the downstream draining lymph node. We found that sphingosine kinase-1, which regulates S1P production is increased at inflamed sites in mice and in patients with the chronic inflammatory disease, rheumatoid arthritis. Together, these data suggest that S1P, or its regulators, may be key targets to promote or disrupt accumulation of CD4 T cells at inflamed tissues.
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Methods that enable the identification of virus-specific CD4 and CD8 T cells are key to our understanding of how the adaptive immune response controls viral infection. Here we describe two distinct methods to evaluate the T cell response to influenza A virus (IAV). The number and phenotype of T cells that respond to natural IAV epitopes can be assessed by flow cytometry using MHC class I and class II tetramers. Using this system, IAV-specific T cells can be tracked in various organs within the same animal, or, in different cohorts, the response can be evaluated at several time points following infection. While providing clear quantitative data, flow cytometry cannot provide any information about T cell location within the lung or interactions between responding T cells and other cell types. Here we also describe a method to examine activated CD4 T cells in the lungs of living animals using multiphoton intravital microscopy, thus providing real-time analysis of T cell behavior during an infection.
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Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Virus de la Influenza A/inmunología , Pulmón/inmunología , Pulmón/virología , Infecciones por Orthomyxoviridae/inmunología , Inmunidad Adaptativa/inmunología , Animales , Epítopos/inmunología , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Infecciones por Orthomyxoviridae/virologíaRESUMEN
Immunological memory is one of the defining features of the adaptive immune system. As key orchestrators and mediators of immunity, CD4 T cells are central to the vast majority of adaptive immune responses. Generated following an immune response, memory CD4 T cells retain pertinent information about their activation environment enabling them to make rapid effector responses upon reactivation. These responses can either benefit the host by hastening the control of pathogens or cause damaging immunopathology. Here, we will discuss the diversity of the memory CD4 T cell pool, the signals that influence the transition of activated T cells into that pool, and highlight how activation requirements differ between naïve and memory CD4 T cells. A greater understanding of these factors has the potential to aid the design of more effective vaccines and to improve regulation of pathologic CD4 T cells, such as in the context of autoimmunity and allergy.
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The production of high affinity, class switched antibodies produced by B cells hinges on the effective differentiation of T follicular helper (Tfh) cells. Here we define conditions specifically enhancing Tfh differentiation and providing protection in a model of influenza infection. Tfh responses were associated with prolonged antigen presentation by dendritic cells (DCs), which maintained T cell/DC interactions into stage 3 (>72 hr) of activation. Blocking stage 3 interactions ablated Tfh generation, demonstrating a causal link between T cell-DC behaviour and functional outcomes. The current data therefore explain how duration of antigen presentation affects the dynamics of T cell-DC interactions and consequently determine Tfh cell differentiation in the developing immune response.