RESUMEN
Macrophages and conventional dendritic cells (cDCs) are distributed throughout the body, maintaining tissue homeostasis and tolerance to self and orchestrating innate and adaptive immunity against infection and cancer. As they complement each other, it is important to understand how they cooperate and the mechanisms that integrate their functions. Both are exposed to commensal microbes, pathogens, and other environmental challenges that differ widely among anatomical locations and over time. To adjust to these varying conditions, macrophages and cDCs acquire spatiotemporal adaptations (STAs) at different stages of their life cycle that determine how they respond to infection. The STAs acquired in response to previous infections can result in increased responsiveness to infection, termed training, or in reduced responses, termed paralysis, which in extreme cases can cause immunosuppression. Understanding the developmental stage and location where macrophages and cDCs acquire their STAs, and the molecular and cellular players involved in their induction, may afford opportunities to harness their beneficial outcomes and avoid or reverse their deleterious effects. Here we review our current understanding of macrophage and cDC development, life cycle, function, and STA acquisition before, during, and after infection.We propose a unified framework to explain how these two cell types adjust their activities to changing conditions over space and time to coordinate their immunosurveillance functions.
Asunto(s)
Inmunidad Adaptativa , Células Dendríticas , Animales , Diferenciación Celular , Humanos , Tolerancia Inmunológica , MacrófagosRESUMEN
Sepsis induces immune alterations, which last for months after the resolution of illness. The effect of this immunological reprogramming on the risk of developing cancer is unclear. Here we use a national claims database to show that sepsis survivors had a lower cumulative incidence of cancers than matched nonsevere infection survivors. We identify a chemokine network released from sepsis-trained resident macrophages that triggers tissue residency of T cells via CCR2 and CXCR6 stimulations as the immune mechanism responsible for this decreased risk of de novo tumor development after sepsis cure. While nonseptic inflammation does not provoke this network, laminarin injection could therapeutically reproduce the protective sepsis effect. This chemokine network and CXCR6 tissue-resident T cell accumulation were detected in humans with sepsis and were associated with prolonged survival in humans with cancer. These findings identify a therapeutically relevant antitumor consequence of sepsis-induced trained immunity.
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Macrófagos , Neoplasias , Sepsis , Humanos , Sepsis/inmunología , Macrófagos/inmunología , Femenino , Neoplasias/inmunología , Neoplasias/terapia , Masculino , Receptores CXCR6/metabolismo , Animales , Linfocitos T/inmunología , Receptores CCR2/metabolismo , Persona de Mediana Edad , Ratones , Anciano , Quimiocinas/metabolismo , AdultoRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMEN
Sepsis and trauma cause inflammation and elevated susceptibility to hospital-acquired pneumonia. As phagocytosis by macrophages plays a critical role in the control of bacteria, we investigated the phagocytic activity of macrophages after resolution of inflammation. After resolution of primary pneumonia, murine alveolar macrophages (AMs) exhibited poor phagocytic capacity for several weeks. These paralyzed AMs developed from resident AMs that underwent an epigenetic program of tolerogenic training. Such adaptation was not induced by direct encounter of the pathogen but by secondary immunosuppressive signals established locally upon resolution of primary infection. Signal-regulatory protein α (SIRPα) played a critical role in the establishment of the microenvironment that induced tolerogenic training. In humans with systemic inflammation, AMs and also circulating monocytes still displayed alterations consistent with reprogramming six months after resolution of inflammation. Antibody blockade of SIRPα restored phagocytosis in monocytes of critically ill patients in vitro, which suggests a potential strategy to prevent hospital-acquired pneumonia.
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Epigénesis Genética , Inflamación/etiología , Pulmón/inmunología , Pulmón/metabolismo , Macrófagos Alveolares/metabolismo , Animales , Biomarcadores , Reprogramación Celular , Citocinas/metabolismo , Humanos , Tolerancia Inmunológica , Inmunofenotipificación , Inflamación/metabolismo , Inflamación/patología , Mediadores de Inflamación/metabolismo , Pulmón/patología , Macrófagos/inmunología , Macrófagos/metabolismo , Macrófagos Alveolares/inmunología , Ratones , Monocitos/inmunología , Monocitos/metabolismo , Fagocitosis/inmunología , Neumonía/etiología , Neumonía/metabolismo , Neumonía/patología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismoRESUMEN
The antigen-presenting molecule MR1 presents vitamin B-related antigens (VitB antigens) to mucosal-associated invariant T (MAIT) cells through an uncharacterized pathway. We show that MR1, unlike other antigen-presenting molecules, does not constitutively present self-ligands. In the steady state it accumulates in a ligand-receptive conformation within the endoplasmic reticulum. VitB antigens reach this location and form a Schiff base with MR1, triggering a 'molecular switch' that allows MR1-VitB antigen complexes to traffic to the plasma membrane. These complexes are endocytosed with kinetics independent of the affinity of the MR1-ligand interaction and are degraded intracellularly, although some MR1 molecules acquire new ligands during passage through endosomes and recycle back to the surface. MR1 antigen presentation is characterized by a rapid 'off-on-off' mechanism that is strictly dependent on antigen availability.
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Presentación de Antígeno/inmunología , Antígenos/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Transducción de Señal/inmunología , Antígenos/metabolismo , Línea Celular , Membrana Celular/inmunología , Membrana Celular/metabolismo , Células Cultivadas , Endocitosis/inmunología , Retículo Endoplásmico/inmunología , Retículo Endoplásmico/metabolismo , Endosomas/inmunología , Endosomas/metabolismo , Células HeLa , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/metabolismo , Humanos , Immunoblotting , Espacio Intracelular/inmunología , Espacio Intracelular/metabolismo , Microscopía Confocal , Antígenos de Histocompatibilidad Menor , Unión Proteica/inmunología , Transporte de Proteínas/inmunología , Complejo Vitamínico B/inmunologíaRESUMEN
Lung infections cause prolonged immune alterations and elevated susceptibility to secondary pneumonia. We found that, after resolution of primary viral or bacterial pneumonia, dendritic cells (DC), and macrophages exhibited poor antigen-presentation capacity and secretion of immunogenic cytokines. Development of these "paralyzed" DCs and macrophages depended on the immunosuppressive microenvironment established upon resolution of primary infection, which involved regulatory T (Treg) cells and the cytokine TGF-ß. Paralyzed DCs secreted TGF-ß and induced local Treg cell accumulation. They also expressed lower amounts of IRF4, a transcription factor associated with increased antigen-presentation capacity, and higher amounts of Blimp1, a transcription factor associated with tolerogenic functions, than DCs present during primary infection. Blimp1 expression in DC of humans suffering sepsis or trauma correlated with severity and complicated outcomes. Our findings describe mechanisms underlying sepsis- and trauma-induced immunosuppression, reveal prognostic markers of susceptibility to secondary infections and identify potential targets for therapeutic intervention.
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Células Dendríticas/inmunología , Infecciones por Escherichia coli/inmunología , Virus de la Influenza A/inmunología , Macrófagos/inmunología , Infecciones por Orthomyxoviridae/inmunología , Neumonía/inmunología , Sepsis/inmunología , Anciano , Animales , Presentación de Antígeno , Diferenciación Celular , Células Cultivadas , Escherichia coli , Femenino , Humanos , Tolerancia Inmunológica , Factores Reguladores del Interferón/genética , Factores Reguladores del Interferón/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Persona de Mediana Edad , Factor 1 de Unión al Dominio 1 de Regulación Positiva , Linfocitos T Reguladores/inmunología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Infection with influenza virus results in the deposition of anti-influenza CD8(+) resident memory T cells (T(RM) cells) in the lung. As a consequence of their location in the lung mucosal tissue, these cells are exposed to cytopathic pathogens over the life of the organism and may themselves be susceptible to infection. Here we found that lung T(RM) cells selectively maintained expression of the interferon-induced transmembrane protein IFITM3, a protein that confers broad resistance to viral infection. Lung T(RM) cells that lacked IFITM3 expression were more susceptible to infection than were their normal counterparts and were selectively lost during a secondary bout of infection. Thus, lung T(RM) cells were programmed to retain IFITM3 expression, which facilitated their survival and protection from viral infection during subsequent exposures.
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Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Pulmón/inmunología , Proteínas de la Membrana/metabolismo , Infecciones por Orthomyxoviridae/inmunología , Orthomyxoviridae/inmunología , Animales , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/virología , Metilación de ADN , Memoria Inmunológica , Interferón-alfa/metabolismo , Pulmón/virología , Proteínas de la Membrana/inmunología , Ratones , Ratones Endogámicos C57BL , Infecciones por Orthomyxoviridae/metabolismo , Infecciones por Orthomyxoviridae/virología , Interferencia de ARN , ARN Interferente Pequeño , Mucosa Respiratoria/inmunología , Mucosa Respiratoria/virologíaRESUMEN
The development of dendritic cells (DCs) depends on signaling via the FMS-like tyrosine kinase 3 (Flt3) receptor. How Flt3 signaling impacts terminally differentiated DC function is unknown. This is important given the increasing interest in exploiting Flt3 for vaccination and tumor immunotherapy. Here, we examined DCs in mice harboring constitutively activated Flt3 (Flt3-ITD). Flt3ITD/ITD mice possessed expanded splenic DC subsets including plasmacytoid DC, conventional DC (cDC)1, cDC2, double positive (DP) cDC1 (CD11c+ CD8+ CD11b- CD103+ CD86+), noncanonical (NC) cDC1 (CD11c+ CD8+ CD11b- CD103- CD86-) and single positive (SP) cDC1 (CD11c+ CD8+ CD11b- CD103- CD86+). Outcomes of constitutive Flt3 signaling differed depending on the cDC subset examined. In comparison with wild type (WT) DCs, all Flt3ITD/ITD cDCs displayed an altered surface phenotype with changes in costimulatory molecules, major histocompatibility complex class I (MHC I) and II (MHC II). Cytokine secretion patterns, antigen uptake, antigen proteolysis and antigen presenting function differed between WT and Flt3ITD/ITD subsets, particularly cDC2. In summary, Flt3 signaling impacts the function of terminally differentiated cDCs with important consequences for antigen presentation.
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Presentación de Antígeno , Células Dendríticas , Transducción de Señal , Tirosina Quinasa 3 Similar a fms , Animales , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Tirosina Quinasa 3 Similar a fms/metabolismo , Ratones , Ratones Endogámicos C57BL , Citocinas/metabolismo , Diferenciación CelularRESUMEN
The antigen presentation molecule MR1 (major histocompatibility complex, class I-related) presents ligands derived from the riboflavin (vitamin B) synthesis pathway, which is not present in mammalian species or viruses, to mucosal-associated invariant T (MAIT) cells. In this study, we demonstrate that varicella zoster virus (VZV) profoundly suppresses MR1 expression. We show that VZV targets the intracellular reservoir of immature MR1 for degradation, while preexisting, ligand-bound cell surface MR1 is protected from such targeting, thereby highlighting an intricate temporal relationship between infection and ligand availability. We also identify VZV open reading frame (ORF) 66 as functioning to suppress MR1 expression when this viral protein is expressed during transient transfection, but this is not apparent during infection with a VZV mutant virus lacking ORF66 expression. This indicates that VZV is likely to encode multiple viral genes that target MR1. Overall, we identify an immunomodulatory function of VZV whereby infection suppresses the MR1 biosynthesis pathway.
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Herpesvirus Humano 3 , Antígenos de Histocompatibilidad Clase I , Animales , Herpesvirus Humano 3/genética , Ligandos , Antígenos de Histocompatibilidad Menor , Complejo Mayor de Histocompatibilidad , MamíferosRESUMEN
Bacterial synthesis of vitamin B2 generates a by-product, 5-(2-oxopropylideneamino)-d-ribityl-aminouracil (5-OP-RU), with potent immunological properties in mammals, but it is rapidly degraded in water. This natural product covalently bonds to the key immunological protein MR1 in the endoplasmic reticulum of antigen presenting cells (APCs), enabling MR1 refolding and trafficking to the cell surface, where it interacts with T cell receptors (TCRs) on mucosal associated invariant T lymphocytes (MAIT cells), activating their immunological and antimicrobial properties. Here, we strategically modify this natural product to understand the molecular basis of its recognition by MR1. This culminated in the discovery of new water-stable compounds with extremely powerful and distinctive immunological functions. We report their capacity to bind MR1 inside APCs, triggering its expression on the cell surface (EC50 17â nM), and their potent activation (EC50 56â pM) or inhibition (IC50 80â nM) of interacting MAIT cells. We further derivatize compounds with diazirine-alkyne, biotin, or fluorophore (Cy5 or AF647) labels for detecting, monitoring, and studying cellular MR1. Computer modeling casts new light on the molecular mechanism of activation, revealing that potent activators are first captured in a tyrosine- and serine-lined cleft in MR1 via specific pi-interactions and H-bonds, before more tightly attaching via a covalent bond to Lys43 in MR1. This chemical study advances our molecular understanding of how bacterial metabolites are captured by MR1, influence cell surface expression of MR1, interact with T cells to induce immunity, and offers novel clues for developing new vaccine adjuvants, immunotherapeutics, and anticancer drugs.
Asunto(s)
Riboflavina , Humanos , Riboflavina/metabolismo , Riboflavina/química , Riboflavina/farmacología , Riboflavina/biosíntesis , Riboflavina/análogos & derivados , Agentes Inmunomoduladores/química , Agentes Inmunomoduladores/farmacología , Agentes Inmunomoduladores/metabolismo , Antígenos de Histocompatibilidad Clase I/metabolismo , Antígenos de Histocompatibilidad Clase I/inmunología , Antígenos de Histocompatibilidad Menor/metabolismo , Células T Invariantes Asociadas a Mucosa/metabolismo , Células T Invariantes Asociadas a Mucosa/inmunología , Factores Inmunológicos/farmacología , Factores Inmunológicos/química , Factores Inmunológicos/metabolismo , Células Presentadoras de Antígenos/metabolismo , Células Presentadoras de Antígenos/inmunología , Ribitol/análogos & derivados , Uracilo/análogos & derivadosRESUMEN
MHC class II (MHC II) Ag presentation by dendritic cells (DCs) is critical for CD4+ T cell immunity. Cell surface levels of MHC II loaded with peptide is controlled by ubiquitination. In this study, we have examined how MHC II ubiquitination impacts immunity using MHC IIKRKI/KI mice expressing mutant MHC II molecules that are unable to be ubiquitinated. Numbers of conventional DC (cDC) 1, cDC2 and plasmacytoid DCs were significantly reduced in MHC IIKRKI/KI spleen, with the remaining MHC IIKRKI/KI DCs expressing an altered surface phenotype. Whereas Ag uptake, endosomal pH, and cathepsin protease activity were unaltered, MHC IIKRKI/KI cDC1 produced increased inflammatory cytokines and possessed defects in Ag proteolysis. Immunization of MHC IIKRKI/KI mice identified impairments in MHC II and MHC class I presentation of soluble, cell-associated and/or DC-targeted OVA via mAb specific for DC surface receptor Clec9A (anti-Clec9A-OVA mAb). Reduced T cell responses and impaired CTL killing was observed in MHC IIKRKI/KI mice following immunization with cell-associated and anti-Clec9A-OVA. Immunization of MHC IIKRKI/KI mice failed to elicit follicular Th cell responses and generated barely detectable Ab to anti-Clec9A mAb-targeted Ag. In summary, MHC II ubiquitination in DCs impacts the homeostasis, phenotype, cytokine production, and Ag proteolysis by DCs with consequences for Ag presentation and T cell and Ab-mediated immunity.
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Linfocitos T CD4-Positivos/inmunología , Células Dendríticas/inmunología , Centro Germinal/inmunología , Antígenos de Histocompatibilidad Clase II/metabolismo , Animales , Presentación de Antígeno/genética , Células Cultivadas , Citotoxicidad Inmunológica , Antígenos de Histocompatibilidad Clase II/genética , Inmunidad Celular , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutación/genética , UbiquitinaciónRESUMEN
Rationale: Brain injury induces systemic immunosuppression, increasing the risk of viral reactivations and altering neurological recovery. Objectives: To determine if systemic immune alterations and lung replication of herpesviridae are associated and can help predict outcomes after brain injury. Methods: We collected peripheral blood mononuclear cells in patients with severe brain injury requiring invasive mechanical ventilation. We systematically searched for respiratory herpes simplex virus (HSV) replications in tracheal aspirates. We also performed chromatin immunoprecipitation sequencing, RNA-sequencing, and in vitro functional assays of monocytes and CD4 T cells collected on Day 1 to characterize the immune response to severe acute brain injury. The primary outcome was the Glasgow Outcome Scale Extended at 6 months. Measurements and Main Results: In 344 patients with severe brain injury, lung HSV reactivations were observed in 39% of the 232 patients seropositive for HSV and independently associated with poor neurological recovery at 6 months (hazard ratio, 1.90; 95% confidence interval, 1.08-3.57). Weighted gene coexpression network analyses of the transcriptomic response of monocytes to brain injury defined a module of 721 genes, including PD-L1 and CD80, enriched for the binding DNA motif of the transcriptional factor Zeb2 and whose ontogenic analyses revealed decreased IFN-γ-mediated and antiviral response signaling pathways. This monocyte signature was preserved in a validation cohort and predicted the neurological outcome at 6 months with good accuracy (area under the curve, 0.786; 95% confidence interval, 0.593-0.978). Conclusions: A specific monocyte signature is associated with HSV reactivation and predicts poor recovery after brain injury. The alterations of the immune control of herpesviridae replication are understudied and represent a novel therapeutic target.
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Lesiones Encefálicas , Herpes Simple , Herpesvirus Humano 1 , Herpesvirus Humano 1/genética , Humanos , Leucocitos Mononucleares , MonocitosRESUMEN
The antigen-presenting molecule MR1 (MHC class I-related protein 1) presents metabolite antigens derived from microbial vitamin B2 synthesis to activate mucosal-associated invariant T (MAIT) cells. Key aspects of this evolutionarily conserved pathway remain uncharacterized, including where MR1 acquires ligands and what accessory proteins assist ligand binding. We answer these questions by using a fluorophore-labeled stable MR1 antigen analog, a conformation-specific MR1 mAb, proteomic analysis, and a genome-wide CRISPR/Cas9 library screen. We show that the endoplasmic reticulum (ER) contains a pool of two unliganded MR1 conformers stabilized via interactions with chaperones tapasin and tapasin-related protein. This pool is the primary source of MR1 molecules for the presentation of exogenous metabolite antigens to MAIT cells. Deletion of these chaperones reduces the ER-resident MR1 pool and hampers antigen presentation and MAIT cell activation. The MR1 antigen-presentation pathway thus co-opts ER chaperones to fulfill its unique ability to present exogenous metabolite antigens captured within the ER.
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Retículo Endoplásmico/genética , Antígenos de Histocompatibilidad Clase I/genética , Metaboloma/genética , Antígenos de Histocompatibilidad Menor/genética , Proteómica , Presentación de Antígeno/genética , Antígenos/genética , Antígenos/inmunología , Sistemas CRISPR-Cas/genética , Humanos , Ligandos , Activación de Linfocitos/genética , Proteínas de Transporte de Membrana/genética , Chaperonas Moleculares/genética , Chaperonas Moleculares/inmunología , Células T Invariantes Asociadas a Mucosa/inmunología , Riboflavina/genéticaRESUMEN
The low mutational burden of epithelial ovarian cancer (EOC) is an impediment to immunotherapies that rely on conventional MHC-restricted, neoantigen-reactive T lymphocytes. Mucosa-associated invariant T (MAIT) cells are MR1-restricted T cells with remarkable immunomodulatory properties. We sought to characterize intratumoral and ascitic MAIT cells in EOC. Single-cell RNA sequencing of six primary human tumor specimens demonstrated that MAIT cells were present at low frequencies within several tumors. When detectable, these cells highly expressed CD69 and VSIR, but otherwise exhibited a transcriptomic signature inconsistent with overt cellular activation and/or exhaustion. Unlike mainstream CD8+ T cells, CD8+ MAIT cells harbored high transcript levels of TNF, PRF1, GZMM and GNLY, suggesting their arming and cytotoxic potentials. In a congenic, MAIT cell-sufficient mouse model of EOC, MAIT and invariant natural killer T cells amassed in the peritoneal cavity where they showed robust IL-17A and IFN-γ production capacities, respectively. However, they gradually lost these functions with tumor progression. In a cohort of 23 EOC patients, MAIT cells were readily detectable in all ascitic fluids examined. In a sub-cohort in which we interrogated ascitic MAIT cells for functional impairments, several exhaustion markers, most notably VISTA, were present on the surface. However, ascitic MAIT cells were capable of producing IFN-γ, TNF-α and granzyme B, but neither IL-17A nor IL-10, in response to an MR1 ligand, bacterial lysates containing MR1 ligands, or a combination of IL-12 and IL-18. In conclusion, ascitic MAIT cells in EOC possess inducible effector functions that may be modified in future immunotherapeutic strategies.
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Células T Invariantes Asociadas a Mucosa , Neoplasias Ováricas , Animales , Ascitis , Linfocitos T CD8-positivos , Carcinoma Epitelial de Ovario , Señales (Psicología) , Citocinas , Femenino , Antígenos de Histocompatibilidad Clase I/genética , Humanos , Interleucina-17 , Ligandos , Ratones , Antígenos de Histocompatibilidad MenorRESUMEN
MHC-related protein 1 (MR1) presents microbial riboflavin metabolites to mucosal-associated invariant T (MAIT) cells for surveillance of microbial presence. MAIT cells express a semi-invariant T-cell receptor (TCR), which recognizes MR1-antigen complexes in a pattern-recognition-like manner. Recently, diverse populations of MR1-restricted T cells have been described that exhibit broad recognition of tumor cells and appear to recognize MR1 in association with tumor-derived self-antigens, though the identity of these antigens remains unclear. Here, we have used TCR gene transfer and engineered MR1-expressing antigen-presenting cells to probe the MR1 restriction and antigen reactivity of a range of MR1-restricted TCRs, including model tumor-reactive TCRs. We confirm MR1 reactivity by these TCRs, show differential dependence on lysine at position 43 of MR1 (K43) and demonstrate competitive inhibition by the MR1 ligand 6-formylpterin. TCR-expressing reporter lines, however, failed to recapitulate the robust tumor specificity previously reported, suggesting an importance of accessory molecules for MR1-dependent tumor reactivity. Finally, MR1-mutant cell lines showed that distinct residues on the α1/α2 helices were required for TCR binding by different MR1-restricted T cells and suggested central but distinct docking modes by the broad family of MR1-restricted αß TCRs. Collectively, these data are consistent with recognition of distinct antigens by diverse MR1-restricted T cells.
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Células T Invariantes Asociadas a Mucosa , Receptores de Antígenos de Linfocitos T alfa-beta , Antígenos de Histocompatibilidad Clase I/metabolismo , Antígenos de Histocompatibilidad Menor/genética , Receptores de Antígenos de Linfocitos T/metabolismo , Receptores de Antígenos de Linfocitos T alfa-beta/genéticaRESUMEN
Understanding the complex elements affecting signal resolution in cytometry is key for quality experimental design and data. In this study, we incorporate autofluorescence as a contributing factor to our understanding of resolution in cytometry and corroborate its impact in fluorescence signal detection through mathematical predictions supported by empirical evidence. Our findings illustrate the critical importance of autofluorescence extraction via full spectrum unmixing in unmasking dim signals and delineating the expression and subset distribution of low abundance markers in discovery projects. We apply our findings to the precise definition of the tissue and cellular distribution of a weakly expressed fluorescent protein that reports on a low-abundance immunological gene. Exploiting the full spectrum coverage enabled by Aurora 5L, we describe a novel approach to the isolation of pure cell subset-specific autofluorescence profiles based on high dimensionality reduction algorithms. This method can also be used to unveil differences in the autofluorescent fingerprints of tissues in homeostasis and after immunological challenges.
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Algoritmos , Colorantes , InmunofenotipificaciónRESUMEN
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.
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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
This work presents the CODEUS platform, which includes a simulation tool together with an online experimental demonstrator to offer analysis and testing flexibility for researchers and developers in Ultrasonic Indoor Positioning Systems (UIPSs). The simulation platform allows most common encoding techniques and sequences to be tested in a configurable UIPS. It models the signal modulation and processing, the ultrasonic transducers' response, the beacon distribution, the channel propagation effects, the synchronism, and the application of different positioning algorithms. CODEUS provides results and performance analysis for different metrics and at different stages of the signal processing. The UIPS simulation tool is specified by means of the MATLAB© App-Designer environment, which enables the definition of a user-friendly interface. It has also been linked to an online demonstrator that can be managed remotely by means of a website, thus avoiding any hardware requirement or equipment on behalf of researchers. This demonstrator allows the selected transmission schemes, modulation or encoding techniques to be validated in a real UIPS, therefore enabling a fast and easy way of carrying out experimental tests in a laboratory environment, while avoiding the time-consuming tasks related to electronic design and prototyping in the UIPS field. Both simulator and online demonstrator are freely available for researchers and students through the corresponding website.
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Procesamiento de Señales Asistido por Computador , Ultrasonido , Algoritmos , Simulación por Computador , HumanosRESUMEN
Dendritic cells (DCs) are essential for initiating immune responses. Depending on the environment, the type of DC and the way in which they interact with T cells, these immune responses can be beneficial or detrimental. DCs can be exploited as cellular vectors for vaccines against infection and cancer. The development and maintenance of DCs is dependent on the FMS-like tyrosine kinase 3 (Flt3)/Flt3 ligand (Flt3L) signaling cascade. Flt3 is also one of the most commonly mutated genes in acute myeloid leukemia and as such represents an attractive drug target. In this review, Flt3 is discussed with a particular focus on DCs. We detail the lifecycle of Flt3, from transcription to degradation, and interrogate recent studies as to how this pathway can be manipulated for immunotherapy, vaccination and treatment of autoimmune disease.