RESUMEN
The thymus is essential for establishing adaptive immunity yet undergoes age-related involution that leads to compromised immune responsiveness. The thymus is also extremely sensitive to acute insult and although capable of regeneration, this capacity declines with age for unknown reasons. We applied single-cell and spatial transcriptomics, lineage-tracing and advanced imaging to define age-related changes in nonhematopoietic stromal cells and discovered the emergence of two atypical thymic epithelial cell (TEC) states. These age-associated TECs (aaTECs) formed high-density peri-medullary epithelial clusters that were devoid of thymocytes; an accretion of nonproductive thymic tissue that worsened with age, exhibited features of epithelial-to-mesenchymal transition and was associated with downregulation of FOXN1. Interaction analysis revealed that the emergence of aaTECs drew tonic signals from other functional TEC populations at baseline acting as a sink for TEC growth factors. Following acute injury, aaTECs expanded substantially, further perturbing trophic regeneration pathways and correlating with defective repair of the involuted thymus. These findings therefore define a unique feature of thymic involution linked to immune aging and could have implications for developing immune-boosting therapies in older individuals.
Asunto(s)
Envejecimiento , Células Epiteliales , Factores de Transcripción Forkhead , Regeneración , Timo , Timo/inmunología , Animales , Células Epiteliales/inmunología , Regeneración/inmunología , Ratones , Envejecimiento/inmunología , Factores de Transcripción Forkhead/metabolismo , Factores de Transcripción Forkhead/genética , Transición Epitelial-Mesenquimal/inmunología , Ratones Endogámicos C57BL , Masculino , Timocitos/inmunología , Timocitos/metabolismo , Femenino , Análisis de la Célula IndividualRESUMEN
Group 2 innate lymphoid cells (ILC2s) are essential to maintain tissue homeostasis. In cancer, ILC2s can harbor both pro-tumorigenic and anti-tumorigenic functions, but we know little about their underlying mechanisms or whether they could be clinically relevant or targeted to improve patient outcomes. Here, we found that high ILC2 infiltration in human melanoma was associated with a good clinical prognosis. ILC2s are critical producers of the cytokine granulocyte-macrophage colony-stimulating factor, which coordinates the recruitment and activation of eosinophils to enhance antitumor responses. Tumor-infiltrating ILC2s expressed programmed cell death protein-1, which limited their intratumoral accumulation, proliferation and antitumor effector functions. This inhibition could be overcome in vivo by combining interleukin-33-driven ILC2 activation with programmed cell death protein-1 blockade to significantly increase antitumor responses. Together, our results identified ILC2s as a critical immune cell type involved in melanoma immunity and revealed a potential synergistic approach to harness ILC2 function for antitumor immunotherapies.
Asunto(s)
Anticuerpos/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Inhibidores de Puntos de Control Inmunológico/farmacología , Interleucina-33/farmacología , Linfocitos/efectos de los fármacos , Melanoma Experimental/tratamiento farmacológico , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Neoplasias Cutáneas/tratamiento farmacológico , Animales , Línea Celular Tumoral , Quimiotaxis de Leucocito/efectos de los fármacos , Citotoxicidad Inmunológica/efectos de los fármacos , Eosinófilos/efectos de los fármacos , Eosinófilos/inmunología , Eosinófilos/metabolismo , Femenino , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Humanos , Linfocitos/inmunología , Linfocitos/metabolismo , Masculino , Melanoma Experimental/genética , Melanoma Experimental/inmunología , Melanoma Experimental/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Fenotipo , Receptor de Muerte Celular Programada 1/genética , Receptor de Muerte Celular Programada 1/metabolismo , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/inmunología , Neoplasias Cutáneas/metabolismoRESUMEN
The detection of aberrant cells by natural killer (NK) cells is controlled by the integration of signals from activating and inhibitory ligands and from cytokines such as IL-15. We identified cytokine-inducible SH2-containing protein (CIS, encoded by Cish) as a critical negative regulator of IL-15 signaling in NK cells. Cish was rapidly induced in response to IL-15, and deletion of Cish rendered NK cells hypersensitive to IL-15, as evidenced by enhanced proliferation, survival, IFN-γ production and cytotoxicity toward tumors. This was associated with increased JAK-STAT signaling in NK cells in which Cish was deleted. Correspondingly, CIS interacted with the tyrosine kinase JAK1, inhibiting its enzymatic activity and targeting JAK for proteasomal degradation. Cish(-/-) mice were resistant to melanoma, prostate and breast cancer metastasis in vivo, and this was intrinsic to NK cell activity. Our data uncover a potent intracellular checkpoint in NK cell-mediated tumor immunity and suggest possibilities for new cancer immunotherapies directed at blocking CIS function.
Asunto(s)
Inmunoterapia/métodos , Células Asesinas Naturales/inmunología , Neoplasias/terapia , Proteínas Supresoras de la Señalización de Citocinas/metabolismo , Animales , Proliferación Celular/genética , Citotoxicidad Inmunológica/genética , Vigilancia Inmunológica , Interferón gamma/metabolismo , Interleucina-15/metabolismo , Janus Quinasa 1/metabolismo , Activación de Linfocitos/genética , Melanoma Experimental , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Terapia Molecular Dirigida , Neoplasias/inmunología , Transducción de Señal/genética , Proteínas Supresoras de la Señalización de Citocinas/genéticaRESUMEN
Venetoclax, a first-in-class BH3 mimetic drug targeting BCL-2, has improved outcomes for patients with chronic lymphocytic leukemia (CLL). Early measurements of the depth of the venetoclax treatment response, assessed by minimal residual disease, are strong predictors of long-term clinical outcomes. Yet, there are limited data concerning the early changes induced by venetoclax treatment that might inform strategies to improve responses. To address this gap, we conducted longitudinal mass cytometric profiling of blood cells from patients with CLL during the first five weeks of venetoclax monotherapy. At baseline, we resolved CLL heterogeneity at the single-cell level to define multiple subpopulations in all patients distinguished by proliferative, metabolic and cell survival proteins. Venetoclax induced significant reduction in all CLL subpopulations coincident with rapid upregulation of pro-survival BCL-2, BCL-XL and MCL-1 proteins in surviving cells, which had reduced sensitivity to the drug. Mouse models recapitulated the venetoclax-induced elevation of survival proteins in B cells and CLL-like cells that persisted in vivo, with genetic models demonstrating that extensive apoptosis and access to the B cell cytokine, BAFF, were essential. Accordingly, analysis of patients with CLL that were treated with venetoclax or the anti-CD20 antibody obinutuzumab exhibited marked elevation of BAFF and increased pro-survival proteins in leukemic cells that persisted. Overall, these data highlight the rapid adaptation of CLL cells to targeted therapies via homeostatic factors and support co-targeting of cytokine signals to achieve deeper and more durable long-term responses.
RESUMEN
Foxp3⺠regulatory T (Treg) cells are a crucial immunosuppressive population of CD4⺠T cells, yet the homeostatic processes and survival programs that maintain the Treg cell pool are poorly understood. Here we report that peripheral Treg cells markedly alter their proliferative and apoptotic rates to rapidly restore numerical deficit through an interleukin 2-dependent and costimulation-dependent process. By contrast, excess Treg cells are removed by attrition, dependent on the Bim-initiated Bak- and Bax-dependent intrinsic apoptotic pathway. The antiapoptotic proteins Bcl-xL and Bcl-2 were dispensable for survival of Treg cells, whereas Mcl-1 was critical for survival of Treg cells, and the loss of this antiapoptotic protein caused fatal autoimmunity. Together, these data define the active processes by which Treg cells maintain homeostasis via critical survival pathways.
Asunto(s)
Apoptosis/inmunología , Factores de Transcripción Forkhead/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Animales , Apoptosis/genética , Supervivencia Celular/genética , Supervivencia Celular/inmunología , Femenino , Factores de Transcripción Forkhead/genética , Eliminación de Gen , Homeostasis/inmunología , Interleucina-2/metabolismo , Recuento de Linfocitos , Masculino , Ratones , Ratones Noqueados , Proteína 1 de la Secuencia de Leucemia de Células Mieloides , Proteínas Proto-Oncogénicas c-bcl-2/genética , Transducción de SeñalRESUMEN
Immunological tolerance is established and maintained by a diverse array of safeguards that work together to protect against autoimmunity. Despite the identification of numerous tolerogenic processes, the basis for cooperation among them remains poorly understood. We sought to identify synergy among several well-defined tolerance mediators that alone provide protection only from mild autoimmune symptoms in C57BL/6 mice: BIM, AIRE, CBL-B, and PD-1. Survey of a range of compound mutant mice revealed that the combined loss of the autoimmune regulator, AIRE, with PD-1 unleashed a spontaneous, lethal autoimmune disease. Pdcd1−/−Aire−/− mice succumbed to cachexia before adulthood, with near-complete destruction of the exocrine pancreas. Such fatal autoimmunity was not observed in Pdcd1−/−Bim−/−, Bim−/−Aire−/−, or Cblb−/−Bim−/− mice, suggesting that the cooperation between AIRE-mediated and PD-1mediated tolerance was particularly potent. Immune profiling revealed largely normal development of FOXP3+ regulatory T (Treg) cells in Pdcd1−/−Aire−/− mice, yet excessive, early activation of effector T cells. Adoptive transfer experiments demonstrated that autoimmune exocrine pancreatitis was driven by conventional CD4+ T cells and could not be prevented by the cotransfer of Treg cells from wild-type mice. The development of autoimmunity in mixed bone marrow chimeras supported these observations, indicating that failure of recessive tolerance was responsible for disease. These findings reveal a potent tolerogenic axis between AIRE and PD-1 that has implications for our understanding of how immune checkpoint blockade might synergize with subclinical defects in central tolerance to elicit autoimmune disease.
Asunto(s)
Pancreatitis Autoinmune , Tolerancia Inmunológica , Tolerancia Periférica , Receptor de Muerte Celular Programada 1 , Factores de Transcripción , Animales , Pancreatitis Autoinmune/genética , Pancreatitis Autoinmune/inmunología , Autoinmunidad/genética , Tolerancia Inmunológica/genética , Ratones , Ratones Endogámicos C57BL , Tolerancia Periférica/genética , Tolerancia Periférica/inmunología , Receptor de Muerte Celular Programada 1/genética , Receptor de Muerte Celular Programada 1/fisiología , Timo/inmunología , Factores de Transcripción/genética , Factores de Transcripción/fisiología , Proteína AIRERESUMEN
Venetoclax (VEN) inhibits the prosurvival protein BCL2 to induce apoptosis and is a standard therapy for chronic lymphocytic leukemia (CLL), delivering high complete remission rates and prolonged progression-free survival in relapsed CLL but with eventual loss of efficacy. A spectrum of subclonal genetic changes associated with VEN resistance has now been described. To fully understand clinical resistance to VEN, we combined single-cell short- and long-read RNA-sequencing to reveal the previously unappreciated scale of genetic and epigenetic changes underpinning acquired VEN resistance. These appear to be multilayered. One layer comprises changes in the BCL2 family of apoptosis regulators, especially the prosurvival family members. This includes previously described mutations in BCL2 and amplification of the MCL1 gene but is heterogeneous across and within individual patient leukemias. Changes in the proapoptotic genes are notably uncommon, except for single cases with subclonal losses of BAX or NOXA. Much more prominent was universal MCL1 gene upregulation. This was driven by an overlying layer of emergent NF-κB (nuclear factor kappa B) activation, which persisted in circulating cells during VEN therapy. We discovered that MCL1 could be a direct transcriptional target of NF-κB. Both the switch to alternative prosurvival factors and NF-κB activation largely dissipate following VEN discontinuation. Our studies reveal the extent of plasticity of CLL cells in their ability to evade VEN-induced apoptosis. Importantly, these findings pinpoint new approaches to circumvent VEN resistance and provide a specific biological justification for the strategy of VEN discontinuation once a maximal response is achieved rather than maintaining long-term selective pressure with the drug.
Asunto(s)
Antineoplásicos , Leucemia Linfocítica Crónica de Células B , Humanos , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Leucemia Linfocítica Crónica de Células B/genética , Leucemia Linfocítica Crónica de Células B/metabolismo , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , FN-kappa B , Resistencia a Antineoplásicos/genética , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/uso terapéutico , Recurrencia , Antineoplásicos/uso terapéuticoRESUMEN
Due to the myriad interactions between prosurvival and proapoptotic members of the Bcl-2 family of proteins, establishing the mechanisms that regulate the intrinsic apoptotic pathway has proven challenging. Mechanistic insights have primarily been gleaned from in vitro studies because genetic approaches in mammals that produce unambiguous data are difficult to design. Here we describe a mutation in mouse and human Bak that specifically disrupts its interaction with the prosurvival protein Bcl-xL Substitution of Glu75 in mBak (hBAK Q77) for leucine does not affect the three-dimensional structure of Bak or killing activity but reduces its affinity for Bcl-xL via loss of a single hydrogen bond. Using this mutant, we investigated the requirement for physical restraint of Bak by Bcl-xL in apoptotic regulation. In vitro, Bak(Q75L) cells were significantly more sensitive to various apoptotic stimuli. In vivo, loss of Bcl-xL binding to Bak led to significant defects in T-cell and blood platelet survival. Thus, we provide the first definitive in vivo evidence that prosurvival proteins maintain cellular viability by interacting with and inhibiting Bak.
Asunto(s)
Apoptosis/genética , Plaquetas/citología , Linfocitos T/citología , Proteína Destructora del Antagonista Homólogo bcl-2/metabolismo , Proteína bcl-X/metabolismo , Animales , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Plaquetas/efectos de los fármacos , Plaquetas/metabolismo , Línea Celular , Supervivencia Celular/genética , Humanos , Ratones , Ratones Endogámicos C57BL , Mutación , Unión Proteica , Conformación Proteica , Dominios Proteicos/genética , Linfocitos T/efectos de los fármacos , Linfocitos T/metabolismo , Proteína Destructora del Antagonista Homólogo bcl-2/genéticaRESUMEN
Thymic output is a dynamic process, with high activity at birth punctuated by transient periods of involution during infection. Interferon-α (IFN-α) is a critical molecular mediator of pathogen-induced thymic involution, yet despite the importance of thymic involution, relatively little is known about the molecular integrators that establish sensitivity. Here we found that the microRNA network dependent on the endoribonuclease Dicer, and specifically microRNA miR-29a, was critical for diminishing the sensitivity of the thymic epithelium to simulated infection signals, protecting the thymus against inappropriate involution. In the absence of Dicer or the miR-29a cluster in the thymic epithelium, expression of the IFN-α receptor by the thymic epithelium was higher, which allowed suboptimal signals to trigger rapid loss of thymic cellularity.
Asunto(s)
ARN Helicasas DEAD-box/inmunología , MicroARNs/inmunología , Receptor de Interferón alfa y beta/inmunología , Ribonucleasa III/inmunología , Timo/inmunología , Animales , Artritis/genética , Artritis/inmunología , ARN Helicasas DEAD-box/genética , Femenino , Factores de Transcripción Forkhead/genética , Factores de Transcripción Forkhead/inmunología , Masculino , Ratones , Ribonucleasa III/genética , Timo/citologíaRESUMEN
T cell development occurs in the thymus, where uncommitted progenitors are directed into a range of sublineages with distinct functions. The goal is to generate a TCR repertoire diverse enough to recognize potential pathogens while remaining tolerant of self. Decades of intensive research have characterized the transcriptional programs controlling critical differentiation checkpoints at the population level. However, greater precision regarding how and when these programs orchestrate differentiation at the single-cell level is required. Single-cell RNA sequencing approaches are now being brought to bear on this question, to track the identity of cells and analyze their gene expression programs at a resolution not previously possible. In this review, we discuss recent advances in the application of these technologies that have the potential to yield unprecedented insight to T cell development.
Asunto(s)
Diferenciación Celular/inmunología , Linfocitos T/inmunología , Animales , Humanos , Análisis de Secuencia de ARN/métodos , Timo/inmunologíaRESUMEN
MHC class II (MHC II) displays peptides at the cell surface, a process critical for CD4+ T cell development and priming. Ubiquitination is a mechanism that dictates surface MHC II with the attachment of a polyubiquitin chain to peptide-loaded MHC II, promoting its traffic away from the plasma membrane. In this study, we have examined how MHC II ubiquitination impacts the composition and function of both conventional CD4+ T cell and regulatory T cell (Treg) compartments. Responses were examined in two models of altered MHC II ubiquitination: MHCIIKRKI /KI mice that express a mutant MHC II unable to be ubiquitinated or mice that lack membrane-associated RING-CH 8 (MARCH8), the E3 ubiquitin ligase responsible for MHC II ubiquitination specifically in thymic epithelial cells. Conventional CD4+ T cell populations in thymus, blood, and spleen of MHCIIKRKI/KI and March8 -/- mice were largely unaltered. In MLRs, March8 -/-, but not MHCIIKRKI/KI, CD4+ T cells had reduced reactivity to both self- and allogeneic MHC II. Thymic Treg were significantly reduced in MHCIIKRKI/KI mice, but not March8 -/- mice, whereas splenic Treg were unaffected. Neither scenario provoked autoimmunity, with no evidence of immunohistopathology and normal levels of autoantibody. In summary, MHC II ubiquitination in specific APC types does not have a major impact on the conventional CD4+ T cell compartment but is important for Treg development.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Linfocitos T Reguladores/inmunología , Ubiquitinación/inmunología , Animales , Presentación de Antígeno/inmunología , Células Dendríticas/inmunología , Células Epiteliales/inmunología , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Bazo/inmunología , Timo/inmunología , Ubiquitina/inmunología , Ubiquitina-Proteína Ligasas/inmunologíaRESUMEN
Somatically acquired mutations in PHF6 (plant homeodomain finger 6) frequently occur in hematopoietic malignancies and often coincide with ectopic expression of TLX3. However, there is no functional evidence to demonstrate whether these mutations contribute to tumorigenesis. Similarly, the role of PHF6 in hematopoiesis is unknown. We report here that Phf6 deletion in mice resulted in a reduced number of hematopoietic stem cells (HSCs), an increased number of hematopoietic progenitor cells, and an increased proportion of cycling stem and progenitor cells. Loss of PHF6 caused increased and sustained hematopoietic reconstitution in serial transplantation experiments. Interferon-stimulated gene expression was upregulated in the absence of PHF6 in hematopoietic stem and progenitor cells. The numbers of hematopoietic progenitor cells and cycling hematopoietic stem and progenitor cells were restored to normal by combined loss of PHF6 and the interferon α and ß receptor subunit 1. Ectopic expression of TLX3 alone caused partially penetrant leukemia. TLX3 expression and loss of PHF6 combined caused fully penetrant early-onset leukemia. Our data suggest that PHF6 is a hematopoietic tumor suppressor and is important for fine-tuning hematopoietic stem and progenitor cell homeostasis.
Asunto(s)
Células Madre Hematopoyéticas/citología , Proteínas de Homeodominio/metabolismo , Leucemia/etiología , Proteínas Represoras/fisiología , Animales , Carcinogénesis , Regulación de la Expresión Génica , Humanos , Ratones , Ratones Noqueados , Receptores de Interferón , Proteínas Represoras/genética , Proteínas Supresoras de TumorRESUMEN
Although the proapoptotic BH3-only protein, Bim, is required for deletion of autoreactive thymocytes, Bim-deficient mice do not succumb to extensive organ-specific autoimmune disease. To determine whether other BH3-only proteins safeguard tolerance in the absence of Bim, we screened mice lacking Bim as well as other BH3-only proteins. Most strains showed no additional defects; however, mice deficient for both Puma and Bim spontaneously developed autoimmunity in multiple organs, and their T cells could transfer organ-specific autoimmunity. Puma- and Bim-double-deficient mice had a striking accumulation of mature, single-positive thymocytes, suggesting an additional defect in thymic deletion was the basis for disease. Transgenic mouse models of thymocyte deletion by peripheral neoantigens confirmed that the loss of Bim and Puma allowed increased numbers of autoreactive thymocytes to escape deletion. Our data show that Puma cooperates with Bim to impose a thymic-deletion checkpoint to peripheral self-antigens and cement the notion that defects in apoptosis alone are sufficient to cause autoimmune disease.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/inmunología , Autoantígenos/inmunología , Autoinmunidad/inmunología , Proteínas de la Membrana/inmunología , Proteínas Proto-Oncogénicas/inmunología , Timocitos/inmunología , Proteínas Supresoras de Tumor/inmunología , Animales , Apoptosis/genética , Apoptosis/inmunología , Proteínas Reguladoras de la Apoptosis/genética , Autoinmunidad/genética , Proteína 11 Similar a Bcl2 , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Femenino , Citometría de Flujo , Masculino , Proteínas de la Membrana/genética , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/inmunología , Autotolerancia/genética , Autotolerancia/inmunología , Linfocitos T/inmunología , Linfocitos T/metabolismo , Timocitos/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/inmunología , Proteínas Supresoras de Tumor/genéticaRESUMEN
The differentiation of hematopoietic precursors into the many functionally distinct T-cell types produced by the thymus is a complex process. It proceeds through a series of stages orchestrated by a variety of thymic microenvironments that shape the T-cell developmental processes. Numerous cytokine and cell surface receptors direct thymocyte differentiation but the primary determinant of cell fate is the engagement of the T-cell antigen receptor (TCR). The strength of the TCR signal and the maturation stage of the thymocyte receiving it can direct the various differentiation programs or, alternatively, end the process by inducing cell death. The regulation of thymocyte death is critical for the efficiency of thymic T-cell differentiation and the preservation of immune tolerance. A detailed knowledge of mechanisms that eliminate thymocytes from the T-cell repertoire is essential to understand the "logic" of T-cell selection in the thymus. This review focuses on the central role of the BCL-2 family of proteins in the apoptotic checkpoints that punctuate thymocyte differentiation and the consequences of defects in these processes.
Asunto(s)
Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Linfocitos T/fisiología , Timocitos/fisiología , Timo/inmunología , Animales , Muerte Celular , Diferenciación Celular , Microambiente Celular , Tolerancia Central , Hematopoyesis , Humanos , Receptores de Antígenos de Linfocitos T/metabolismoRESUMEN
T-cell differentiation is governed by interactions with thymic epithelial cells (TECs) and defects in this process undermine immune function and tolerance. To uncover new strategies to restore thymic function and adaptive immunity in immunodeficiency, we sought to determine the molecular mechanisms that control life and death decisions in TECs. Guided by gene expression profiling, we created mouse models that specifically deleted prosurvival genes in TECs. We found that although BCL-2 and BCL-XL were dispensable for TEC homeostasis, MCL-1 deficiency impacted on TECs as early as embryonic day 15.5, resulting in early thymic atrophy and T-cell lymphopenia, with near complete loss of thymic tissue by 2 months of age. MCL-1 was not necessary for TEC differentiation but was continually required for the survival of mature cortical and medullary TECs and the maintenance of thymic architecture. A screen of TEC trophic factors in organ cultures showed that epidermal growth factor upregulated MCL-1 via MAPK/ERK kinase activity, providing a molecular mechanism for the support of TEC survival. This signaling axis governing TEC survival and thymic function represents a new target for strategies for thymic protection and regeneration.
Asunto(s)
Supervivencia Celular/genética , Células Epiteliales/metabolismo , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/genética , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/metabolismo , Timo/fisiología , Animales , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Supervivencia Celular/efectos de los fármacos , Factor de Crecimiento Epidérmico/farmacología , Células Epiteliales/efectos de los fármacos , Femenino , Expresión Génica , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Homeostasis/genética , Inmunofenotipificación , Linfopenia/genética , Masculino , Ratones , Ratones Noqueados , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Timocitos/citología , Timocitos/inmunología , Timocitos/metabolismo , Timo/patología , Proteína bcl-X/genética , Proteína bcl-X/metabolismoRESUMEN
Natural killer cells constitute potent innate lymphoid cells that play a major role in both tumor immunosurveillance and viral clearance via their effector functions. A four-stage model of NK cell functional maturation has been established according to the expression of CD11b and CD27, separating mature NK (mNK) cells into distinct populations that exhibit specific phenotypic and functional properties. To identify genetic factors involved in the regulation of NK cell functional maturation, we performed a linkage analysis on F2 (B6.Rag1-/- × NOD.Rag1-/- intercross) mice. We identified six loci on chromosomes 2, 4, 7, 10, 11, and 18 that were linked to one or more mNK cell subsets. Subsequently, we performed an in silico analysis exploiting mNK cell subset microarray data, highlighting various genes and microRNAs as potential regulators of the functional maturation of NK cells. Together, the combination of our unbiased genetic linkage study and the in silico analysis positions genes known to affect NK cell biology along the specific stages of NK cell functional maturation. Moreover, this approach allowed us to uncover a novel candidate gene in the regulation of NK cell maturation, namely Trp53 Using mice deficient for Trp53, we confirm that this tumor suppressor regulates NK cell functional maturation. Additional candidate genes revealed in this study may eventually serve as targets for the modulation of NK cell functional maturation to potentiate both tumor immunosurveillance and viral clearance.
Asunto(s)
Regulación de la Expresión Génica , Ligamiento Genético , Células Asesinas Naturales/fisiología , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Animales , Antígeno CD11b/inmunología , Diferenciación Celular , Procesos de Crecimiento Celular , Células Cultivadas , Simulación por Computador , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/inmunología , Células Asesinas Naturales/inmunología , Ratones , Ratones Endogámicos NOD , MicroARNs/genética , MicroARNs/inmunología , Miembro 7 de la Superfamilia de Receptores de Factores de Necrosis Tumoral/inmunologíaRESUMEN
γδ T cells respond to molecules upregulated following infection or cellular stress using both TCR and non-TCR molecules. The importance of innate signals versus TCR ligation varies greatly. Both innate-like IL-17-producing γδ T (γδT-17) and IFN-γ-producing γδ T (γδT-IFNγ) subsets tune the sensitivity of their TCR following thymic development, allowing robust responses to inflammatory cytokines in the periphery. The remaining conventional γδ T cells retain high TCR responsiveness. We determined homeostatic mechanisms that govern these various subsets in the peripheral lymphoid tissues. We found that, although innate-like γδT-17 and γδT-IFNγ cells share elements of thymic development, they diverge when it comes to homeostasis. Both exhibit acute sensitivity to cytokines compared with conventional γδ T cells, but they do not monopolize the same cytokine. γδT-17 cells rely exclusively on IL-7 for turnover and survival, aligning them with NKT17 cells; IL-7 ligation triggers proliferation, as well as promotes survival, upregulating Bcl-2 and Bcl-xL. γδT-IFNγ cells instead depend heavily on IL-15. They display traits analogous to memory CD8(+) T cells and upregulate Bcl-xL and Mcl-1 upon cytokine stimulation. The conventional γδ T cells display low sensitivity to cytokine-alone stimulation and favor IL-7 for their turnover, characteristics reminiscent of naive αß T cells, suggesting that they may also require tonic TCR signaling for population maintenance. These survival constraints suggest that γδ T cell subsets do not directly compete with each other for cytokines, but instead fall into resource niches with other functionally similar lymphocytes.
Asunto(s)
Homeostasis/inmunología , Inmunidad Innata/inmunología , Subgrupos de Linfocitos T/inmunología , Linfocitos T/inmunología , Traslado Adoptivo , Animales , Citocinas/inmunología , Citometría de Flujo , Interferón gamma/biosíntesis , Interferón gamma/inmunología , Interleucina-17/biosíntesis , Interleucina-17/inmunología , Ratones , Ratones Endogámicos C57BL , Receptores de Antígenos de Linfocitos T gamma-deltaRESUMEN
Targeting survival mechanisms of immune cells may provide an avenue for immune intervention to dampen unwanted responses (e.g. autoimmunity, immunopathology and transplant rejection) or enhance beneficial ones (e.g. immune deficiency, microbial defence and cancer immunotherapy). The selective survival mechanisms of the various immune cell types also avails the possibility of specific tailoring of such interventions. Here, we review the role of the BCL-2 anti-apoptotic family members (BCL-2, BCL-XL, BCL-W, MCL-1 and A1) on cell death/survival of the major immune cell types, for example, T, NK, B, dendritic cell (DC) lineages. There is both selectivity and redundancy among this family. Selectivity comes partly from the expression levels in each of the cell types. For example, plasmacytoid DC express abundant BCL-2 and are susceptible to BCL-2 antagonism or deficiency, whereas conventional DC express abundant A1 and are susceptible to A1 deficiency. There is, however, also functional redundancy; for example, overexpression of MCL-1 can override BCL-2 antagonism in plasmacytoid DC. Moreover, susceptibility to another anti-apoptotic family member can be unmasked, when one or other member is removed. These dual principles of selectivity and redundancy should guide the use of antagonists for manipulating immune cells.