RESUMEN
Bone destruction is a hallmark of chronic inflammation, and bone-resorbing osteoclasts arising under such a condition differ from steady-state ones. However, osteoclast diversity remains poorly explored. Here, we combined transcriptomic profiling, differentiation assays and in vivo analysis in mouse to decipher specific traits for inflammatory and steady-state osteoclasts. We identified and validated the pattern-recognition receptors (PRR) Tlr2, Dectin-1, and Mincle, all involved in yeast recognition as major regulators of inflammatory osteoclasts. We showed that administration of the yeast probiotic Saccharomyces boulardii CNCM I-745 (Sb) in vivo reduced bone loss in ovariectomized but not sham mice by reducing inflammatory osteoclastogenesis. This beneficial impact of Sb is mediated by the regulation of the inflammatory environment required for the generation of inflammatory osteoclasts. We also showed that Sb derivatives as well as agonists of Tlr2, Dectin-1, and Mincle specifically inhibited directly the differentiation of inflammatory but not steady-state osteoclasts in vitro. These findings demonstrate a preferential use of the PRR-associated costimulatory differentiation pathway by inflammatory osteoclasts, thus enabling their specific inhibition, which opens new therapeutic perspectives for inflammatory bone loss.
Asunto(s)
Osteoporosis , Probióticos , Animales , Ratones , Osteogénesis , Osteoporosis/terapia , Receptor Toll-Like 2 , Saccharomyces/genética , Saccharomyces/metabolismoRESUMEN
CD4+ T cells are critical orchestrators of immune responses against a large variety of pathogens, including viruses. While multiple CD4+ T cell subtypes and their key transcriptional regulators have been identified, there is a lack of consistent definition for CD4+ T cell transcriptional states. In addition, the progressive changes affecting CD4+ T cell subtypes during and after immune responses remain poorly defined. Using single-cell transcriptomics, we characterized the diversity of CD4+ T cells responding to self-resolving and chronic viral infections in mice. We built a comprehensive map of virus-specific CD4+ T cells and their evolution over time, and identified six major cell states consistently observed in acute and chronic infections. During the course of acute infections, T cell composition progressively changed from effector to memory states, with subtype-specific gene modules and kinetics. Conversely, in persistent infections T cells acquired distinct, chronicity-associated programs. By single-cell T cell receptor (TCR) analysis, we characterized the clonal structure of virus-specific CD4+ T cells across individuals. Virus-specific CD4+ T cell responses were essentially private across individuals and most T cells differentiated into both Tfh and Th1 subtypes irrespective of their TCR. Finally, we showed that our CD4+ T cell map can be used as a reference to accurately interpret cell states in external single-cell datasets across tissues and disease models. Overall, this study describes a previously unappreciated level of adaptation of the transcriptional states of CD4+ T cells responding to viruses and provides a new computational resource for CD4+ T cell analysis.
Asunto(s)
Linfocitos T , Virosis , Animales , Linfocitos T CD4-Positivos , Ratones , Receptores de Antígenos de Linfocitos T/genéticaRESUMEN
Under steady-state conditions, conventional CD4+ T lymphocytes are classically divided into naïve (CD44lo CD62Lhi) and memory (CD44hi CD62Llo) cell compartments. While the latter population is presumed to comprise a mixture of distinct subpopulations of explicit foreign antigen (Ag)-specific "authentic" memory and foreign Ag-independent memory-phenotype (MP) cells, phenotypic markers differentially expressed in these two cell types have yet to be identified. Moreover, while MP cells themselves have been previously described as heterogeneous, it is unknown whether they consist of distinct subsets defined by marker expression. In this study, we demonstrate using combined single-cell RNA sequencing and flow cytometric approaches that self-driven MP CD4+ T lymphocytes are divided into CD127hi Sca1lo, CD127hi Sca1hi, CD127lo Sca1hi, and CD127lo Sca1lo subpopulations that are Bcl2lo, while foreign Ag-specific memory cells are CD127hi Sca1hi Bcl2hi. We further show that among the four MP subsets, CD127hi Sca1hi lymphocytes represent the most mature and cell division-experienced subpopulation derived from peripheral naïve precursors. Finally, we provide evidence arguing that this MP subpopulation exerts the highest responsiveness to Th1-differentiating cytokines and can induce colitis. Together, our findings define MP CD4+ T lymphocytes as a unique, self-driven population consisting of distinct subsets that differ from conventional foreign Ag-specific memory cells in marker expression and establish functional relevance for the mature subset of CD127hi Sca1hi MP cells.
Asunto(s)
Ataxias Espinocerebelosas , Linfocitos T , Linfocitos T CD4-Positivos , Humanos , Fenotipo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Ataxias Espinocerebelosas/metabolismo , Linfocitos T/metabolismo , TranscriptomaRESUMEN
Although BTB-zinc finger (BTB-ZF) transcription factors control the differentiation of multiple hematopoietic and immune lineages, how they function is poorly understood. The BTB-ZF factor Thpok controls intrathymic CD4+ T cell development and the expression of most CD4+ and CD8+ lineage genes. Here, we identify the nucleosome remodeling and deacetylase (NuRD) complex as a critical Thpok cofactor. Using mass spectrometry and coimmunoprecipitation in primary T cells, we show that Thpok binds NuRD components independently of DNA association. We locate three amino acid residues within the Thpok BTB domain that are required for both NuRD binding and Thpok functions. Conversely, a chimeric protein merging the NuRD component Mta2 to a BTB-less version of Thpok supports CD4+ T cell development, indicating that NuRD recruitment recapitulates the functions of the Thpok BTB domain. We found that NuRD mediates Thpok repression of CD8+ lineage genes, including the transcription factor Runx3, but is dispensable for Cd4 expression. We show that these functions cannot be performed by the BTB domain of the Thpok-related factor Bcl6, which fails to bind NuRD. Thus, cofactor binding critically contributes to the functional specificity of BTB-ZF factors, which control the differentiation of most hematopoietic subsets.
Asunto(s)
Linfocitos T CD4-Positivos , Complejo Desacetilasa y Remodelación del Nucleosoma Mi-2 , Diferenciación Celular , Linaje de la Célula , Complejo Desacetilasa y Remodelación del Nucleosoma Mi-2/metabolismo , Factores de TranscripciónRESUMEN
While T cell receptor (TCR) αß+CD8α+CD8ß- intraepithelial lymphocytes (CD8αα+ IELs) differentiate from thymic IEL precursors (IELps) and contribute to gut homeostasis, the transcriptional control of their development remains poorly understood. In the present study we showed that mouse thymocytes deficient for the transcription factor leukemia/lymphoma-related factor (LRF) failed to generate TCRαß+CD8αα+ IELs and their CD8ß-expressing counterparts, despite giving rise to thymus and spleen CD8αß+ T cells. LRF-deficient IELps failed to migrate to the intestine and to protect against T cell-induced colitis, and had impaired expression of the gut-homing integrin α4ß7. Single-cell RNA-sequencing found that LRF was necessary for the expression of genes characteristic of the most mature IELps, including Itgb7, encoding the ß7 subunit of α4ß7. Chromatin immunoprecipitation and gene-regulatory network analyses both defined Itgb7 as an LRF target. Our study identifies LRF as an essential transcriptional regulator of IELp maturation in the thymus and subsequent migration to the intestinal epithelium.
Asunto(s)
Linfocitos Intraepiteliales , Leucemia , Linfoma , Animales , Antígenos CD8/genética , Antígenos CD8/metabolismo , Linfocitos T CD8-positivos/metabolismo , Cadenas beta de Integrinas , Mucosa Intestinal/metabolismo , Linfocitos Intraepiteliales/metabolismo , Leucemia/metabolismo , Linfoma/metabolismo , Ratones , Ratones Noqueados , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , Factores de Transcripción/metabolismoRESUMEN
During the immune response, CD4+ T cells differentiate into distinct effector subtypes, including follicular helper T (Tfh) cells that help B cells, and into memory cells. Tfh and memory cells are required for long-term immunity; both depend on the transcription factor Bcl6, raising the question whether they differentiate through similar mechanisms. Here, using single-cell RNA and ATAC sequencing, we show that virus-responding CD4+ T cells lacking both Bcl6 and Blimp1 can differentiate into cells with transcriptomic, chromatin accessibility, and functional attributes of memory cells but not of Tfh cells. Thus, Bcl6 promotes memory cell differentiation primarily through its repression of Blimp1. These findings demonstrate that distinct mechanisms underpin the differentiation of memory and Tfh CD4+ cells and define the Bcl6-Blimp1 axis as a potential target for promoting long-term memory T cell differentiation.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Diferenciación Celular/inmunología , Células T de Memoria/inmunología , Factor 1 de Unión al Dominio 1 de Regulación Positiva/inmunología , Proteínas Proto-Oncogénicas c-bcl-6/inmunología , Células T Auxiliares Foliculares/inmunología , Animales , Linfocitos T CD4-Positivos/metabolismo , Diferenciación Celular/genética , Células Cultivadas , Secuenciación de Inmunoprecipitación de Cromatina/métodos , Perfilación de la Expresión Génica/métodos , Células T de Memoria/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Factor 1 de Unión al Dominio 1 de Regulación Positiva/genética , Factor 1 de Unión al Dominio 1 de Regulación Positiva/metabolismo , Proteínas Proto-Oncogénicas c-bcl-6/genética , Proteínas Proto-Oncogénicas c-bcl-6/metabolismo , RNA-Seq/métodos , Análisis de la Célula Individual/métodos , Células T Auxiliares Foliculares/metabolismoRESUMEN
SARS-CoV-2 has caused a global pandemic that has infected more than 250 million people worldwide. Although several vaccine candidates have received emergency use authorization, there is still limited knowledge on how vaccine dosing affects immune responses. We performed mechanistic studies in mice to understand how the priming dose of an adenovirus-based SARS-CoV-2 vaccine affects long-term immunity to SARS-CoV-2. We first primed C57BL/6 mice with an adenovirus serotype 5 vaccine encoding the SARS-CoV-2 spike protein, similar to that used in the CanSino and Sputnik V vaccines. The vaccine prime was administered at either a standard dose or 1000-fold lower dose, followed by a boost with the standard dose 4 weeks later. Initially, the low dose prime induced lower immune responses relative to the standard dose prime. However, the low dose prime elicited immune responses that were qualitatively superior and, upon boosting, exhibited substantially more potent recall and functional capacity. We also report similar effects with a simian immunodeficiency virus (SIV) vaccine. These findings show an unexpected advantage of fractionating vaccine prime doses, warranting a reevaluation of vaccine trial protocols for SARS-CoV-2 and other pathogens.
Asunto(s)
Vacunas contra la COVID-19/inmunología , Inmunogenicidad Vacunal , Adenoviridae/genética , Adenoviridae/inmunología , Animales , Linfocitos T CD8-positivos/inmunología , Vacunas contra la COVID-19/química , Relación Dosis-Respuesta Inmunológica , Femenino , Vectores Genéticos , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have shown efficacy against SARS-CoV-2, it is unknown if coronavirus vaccines can also protect against other coronaviruses that may infect humans in the future. Here, we show that coronavirus vaccines elicited cross-protective immune responses against heterologous coronaviruses. In particular, we show that a severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) vaccine developed in 2004 and known to protect against SARS-CoV-1 conferred robust heterologous protection against SARS-CoV-2 in mice. Similarly, prior coronavirus infections conferred heterologous protection against distinct coronaviruses. Cross-reactive immunity was also reported in patients with coronavirus disease 2019 (COVID-19) and in individuals who received SARS-CoV-2 vaccines, and transfer of plasma from these individuals into mice improved protection against coronavirus challenges. These findings provide the first demonstration to our knowledge that coronavirus vaccines (and prior coronavirus infections) can confer broad protection against heterologous coronaviruses and establish a rationale for universal coronavirus vaccines.
Asunto(s)
Anticuerpos Antivirales/inmunología , Vacunas contra la COVID-19/uso terapéutico , COVID-19/prevención & control , Animales , Linfocitos T CD8-positivos/citología , Reacciones Cruzadas , Mapeo Epitopo , Femenino , Humanos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , SARS-CoV-2 , VacunaciónRESUMEN
Since late 2019, SARS-CoV-2 has caused a global pandemic that has infected 128 million people worldwide. Although several vaccine candidates have received emergency use authorization (EUA), there are still a limited number of vaccine doses available. To increase the number of vaccinated individuals, there are ongoing discussions about administering partial vaccine doses, but there is still a paucity of data on how vaccine fractionation affects vaccine-elicited immunity. We performed studies in mice to understand how the priming dose of a SARS CoV-2 vaccine affects long-term immunity to SARS CoV-2. We first primed C57BL/6 mice with an adenovirus-based vaccine encoding SARS CoV-2 spike protein (Ad5-SARS-2 spike), similar to that used in the CanSino and Sputnik V vaccines. This prime was administered either at a low dose (LD) of 10 6 PFU or at a standard dose (SD) of 10 9 PFU, followed by a SD boost in all mice four weeks later. As expected, the LD prime induced lower immune responses relative to the SD prime. However, the LD prime elicited immune responses that were qualitatively superior, and upon boosting, mice that were initially primed with a LD exhibited significantly more potent immune responses. Overall, these data demonstrate that limiting the priming dose of a SARS CoV-2 vaccine may confer unexpected benefits. These findings may be useful for improving vaccine availability and for rational vaccine design.
RESUMEN
Bcl-3 is an atypical member of the IκB family that acts in the nucleus to modulate transcription of many NF-κB targets in a highly context-dependent manner. Accordingly, complete Bcl-3-/- mice have diverse defects in both innate and adaptive immune responses; however, direct effects of Bcl-3 action in individual immune cell types have not been clearly defined. Here, we document a cell-autonomous role for Bcl-3 in CD8+ T cell differentiation during the response to lymphocytic choriomeningitis virus infection. Single-cell RNA-seq and flow cytometric analysis of virus-specific Bcl3-/- CD8+ T cells revealed that differentiation was skewed towards terminal effector cells at the expense of memory precursor effector cells (MPECs). Accordingly, Bcl3-/- CD8+ T cells exhibited reduced memory cell formation and a defective recall response. Conversely, Bcl-3-overexpression in transgenic CD8+ T cells enhanced MPEC formation but reduced effector cell differentiation. Together, our results establish Bcl-3 as an autonomous determinant of memory/terminal effector cell balance during CD8+ T cell differentiation in response to acute viral infection. Our results provide proof-of-principle for targeting Bcl-3 pharmacologically to optimize adaptive immune responses to infectious agents, cancer cells, vaccines and other stimuli that induce CD8+ T cell differentiation.
Asunto(s)
Proteínas del Linfoma 3 de Células B/metabolismo , Coriomeningitis Linfocítica/inmunología , Virus de la Coriomeningitis Linfocítica/inmunología , FN-kappa B/inmunología , Animales , Proteínas del Linfoma 3 de Células B/genética , Linfocitos T CD8-positivos/inmunología , Diferenciación Celular , Femenino , Citometría de Flujo , Masculino , Ratones , Ratones Transgénicos , Análisis de Secuencia de ARN , Análisis de la Célula IndividualRESUMEN
αß lineage T cells, most of which are CD4+ or CD8+ and recognize MHC I- or MHC II-presented antigens, are essential for immune responses and develop from CD4+CD8+ thymocytes. The absence of in vitro models and the heterogeneity of αß thymocytes have hampered analyses of their intrathymic differentiation. Here, combining single-cell RNA and ATAC (chromatin accessibility) sequencing, we identified mouse and human αß thymocyte developmental trajectories. We demonstrated asymmetric emergence of CD4+ and CD8+ lineages, matched differentiation programs of agonist-signaled cells to their MHC specificity, and identified correspondences between mouse and human transcriptomic and epigenomic patterns. Through computational analysis of single-cell data and binding sites for the CD4+-lineage transcription factor Thpok, we inferred transcriptional networks associated with CD4+- or CD8+-lineage differentiation, and with expression of Thpok or of the CD8+-lineage factor Runx3. Our findings provide insight into the mechanisms of CD4+ and CD8+ T cell differentiation and a foundation for mechanistic investigations of αß T cell development.
Asunto(s)
Diferenciación Celular/inmunología , Linaje de la Célula/inmunología , Subgrupos de Linfocitos T/inmunología , Timocitos/inmunología , Animales , Presentación de Antígeno/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Diferenciación Celular/genética , Linaje de la Célula/genética , Epigenoma , Regulación de la Expresión Génica , Redes Reguladoras de Genes , Antígenos de Histocompatibilidad/genética , Antígenos de Histocompatibilidad/inmunología , Antígenos de Histocompatibilidad/metabolismo , Humanos , Ratones , Subgrupos de Linfocitos T/metabolismo , Timocitos/metabolismo , Timo/inmunología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , TranscriptomaRESUMEN
Bone destruction relies on interactions between bone and immune cells. Bone-resorbing osteoclasts (OCLs) were recently identified as innate immune cells activating T cells toward tolerance or inflammation. Thus, pathological bone destruction not only relies on increased osteoclast differentiation, but also on the presence of inflammatory OCLs (i-OCLs), part of which express Cx3cr1. Here, we investigated the contribution of mouse Cx3cr1+ and Cx3cr1neg i-OCLs to bone loss. We showed that Cx3cr1+ and Cx3cr1neg i-OCLs differ considerably in transcriptional and functional aspects. Cx3cr1neg i-OCLs have a high ability to resorb bone and activate inflammatory CD4+ T cells. Although Cx3cr1+ i-OCLs are associated with inflammation, they resorb less and have in vitro an immune-suppressive effect on Cx3cr1neg i-OCLs, mediated by PD-L1. Our results provide new insights into i-OCL heterogeneity. They also reveal that different i-OCL subsets may interact to regulate inflammation. This contributes to a better understanding and prevention of inflammatory bone destruction.
Asunto(s)
Resorción Ósea/metabolismo , Receptor 1 de Quimiocinas CX3C/metabolismo , Inflamación/metabolismo , Osteoclastos/metabolismo , Osteogénesis , Osteoporosis/metabolismo , Animales , Resorción Ósea/inmunología , Resorción Ósea/patología , Resorción Ósea/prevención & control , Receptor 1 de Quimiocinas CX3C/genética , Comunicación Celular , Células Cultivadas , Femenino , Inflamación/inmunología , Inflamación/patología , Inflamación/prevención & control , Ratones Endogámicos C57BL , Ratones Noqueados , Osteoclastos/inmunología , Osteoclastos/patología , Osteoporosis/inmunología , Osteoporosis/patología , Osteoporosis/prevención & control , Ovariectomía , Fenotipo , Transducción de Señal , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Most current tumor immunotherapy strategies leverage cytotoxic CD8+ T cells. Despite evidence for clinical potential of CD4+ tumor-infiltrating lymphocytes (TILs), their functional diversity limits our ability to harness their activity. Here, we use single-cell mRNA sequencing to analyze the response of tumor-specific CD4+ TILs and draining lymph node (dLN) T cells. Computational approaches to characterize subpopulations identify TIL transcriptomic patterns strikingly distinct from acute and chronic anti-viral responses and dominated by diversity among T-bet-expressing T helper type 1 (Th1)-like cells. In contrast, the dLN response includes T follicular helper (Tfh) cells but lacks Th1 cells. We identify a type I interferon-driven signature in Th1-like TILs and show that it is found in human cancers, in which it is negatively associated with response to checkpoint therapy. Our study provides a proof-of-concept methodology to characterize tumor-specific CD4+ T cell effector programs. Targeting these programs should help improve immunotherapy strategies.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Neoplasias/inmunología , Transcriptoma/inmunología , Virus/inmunología , Animales , Linfocitos T CD8-positivos/inmunología , Línea Celular Tumoral , Humanos , Inmunoterapia/métodos , Interferón Tipo I/inmunología , Linfocitos Infiltrantes de Tumor/inmunología , Ratones , Ratones Endogámicos C57BL , Células TH1/inmunología , Microambiente Tumoral/inmunologíaRESUMEN
The generation of high-affinity neutralizing antibodies, the objective of most vaccine strategies, occurs in B cells within germinal centers (GCs) and requires rate-limiting "help" from follicular helper CD4+ T (Tfh) cells. Although Tfh differentiation is an attribute of MHC II-restricted CD4+ T cells, the transcription factors driving Tfh differentiation, notably Bcl6, are not restricted to CD4+ T cells. Here, we identified a requirement for the CD4+-specific transcription factor Thpok during Tfh cell differentiation, GC formation, and antibody maturation. Thpok promoted Bcl6 expression and bound to a Thpok-responsive region in the first intron of Bcl6. Thpok also promoted the expression of Bcl6-independent genes, including the transcription factor Maf, which cooperated with Bcl6 to mediate the effect of Thpok on Tfh cell differentiation. Our findings identify a transcriptional program that links the CD4+ lineage with Tfh differentiation, a limiting factor for efficient B cell responses, and suggest avenues to optimize vaccine generation.
Asunto(s)
Diferenciación Celular/inmunología , Proteínas Proto-Oncogénicas c-bcl-6/inmunología , Proteínas Proto-Oncogénicas c-maf/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Factores de Transcripción/inmunología , Transcripción Genética/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Femenino , Regulación de la Expresión Génica/inmunología , Centro Germinal/inmunología , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BLRESUMEN
Memory CD4+ T cells mediate long-term immunity, and their generation is a key objective of vaccination strategies. However, the transcriptional circuitry controlling the emergence of memory cells from early CD4+ antigen-responders remains poorly understood. Here, using single-cell RNA-seq to study the transcriptome of virus-specific CD4+ T cells, we identified a gene signature that distinguishes potential memory precursors from effector cells. We found that both that signature and the emergence of memory CD4+ T cells required the transcription factor Thpok. We further demonstrated that Thpok cell-intrinsically protected memory cells from a dysfunctional, effector-like transcriptional program, similar to but distinct from the exhaustion pattern of cells responding to chronic infection. Mechanistically, Thpok- bound genes encoding the transcription factors Blimp1 and Runx3 and acted by antagonizing their expression. Thus, a Thpok-dependent circuitry promotes both memory CD4+ T cells' differentiation and functional fitness, two previously unconnected critical attributes of adaptive immunity.
Asunto(s)
Linfocitos T CD4-Positivos/fisiología , Subgrupos de Linfocitos T/fisiología , Factores de Transcripción/metabolismo , Animales , Antígenos Virales/inmunología , Diferenciación Celular , Células Cultivadas , Subunidad alfa 3 del Factor de Unión al Sitio Principal/metabolismo , Humanos , Memoria Inmunológica/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Factor 1 de Unión al Dominio 1 de Regulación Positiva/metabolismo , Unión Proteica , Análisis de Secuencia de ARN , Análisis de la Célula Individual , Factores de Transcripción/genética , TranscriptomaRESUMEN
CD8+ T cells are preprogrammed for cytotoxic differentiation in the thymus as they acquire expression of the transcription factor Runx3. However, a subset of effector CD8+ T cells (Tc17) produce IL-17 and fail to express cytotoxic genes. Here, we show that the transcription factors directing IL-17 production, STAT3 and RORγt, inhibit cytotoxicity despite persistent Runx3 expression. Cytotoxic gene repression did not require the transcription factor Thpok, which in CD4+ T cells restrains Runx3 functions and cytotoxicity; and STAT3 restrained cytotoxic gene expression in CD8+ T cells responding to viral infection in vivo. STAT3-induced RORγt represses cytotoxic genes by inhibiting the functions but not the expression of the "cytotoxic" transcription factors T-bet and Eomesodermin. Thus, the transcriptional circuitry directing IL-17 expression inhibits cytotoxic functions. However, by allowing expression of activators of the cytotoxic program, this inhibitory mechanism contributes to the instability of IL-17-producing T cells.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Citotoxicidad Inmunológica/genética , Factor de Transcripción STAT3/metabolismo , Animales , Células Cultivadas , Subunidad alfa 3 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 3 del Factor de Unión al Sitio Principal/metabolismo , Interleucina-17/genética , Interleucina-17/metabolismo , Ratones , Ratones Endogámicos C57BL , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismoRESUMEN
Bone destruction is a hallmark of chronic rheumatic diseases. Although the role of osteoclasts in bone loss is clearly established, their implication in the inflammatory response has not been investigated despite their monocytic origin. Moreover, specific markers are lacking to characterize osteoclasts generated in inflammatory conditions. Here, we have explored the phenotype of inflammatory osteoclasts and their effect on CD4+ T cell responses in the context of bone destruction associated with inflammatory bowel disease. We used the well-characterized model of colitis induced by transfer of naive CD4+ T cells into Rag1-/- mice, which is associated with severe bone destruction. We set up a novel procedure to sort pure osteoclasts generated in vitro to analyze their phenotype and specific immune responses by FACS and qPCR. We demonstrated that osteoclasts generated from colitic mice induced the emergence of TNFα-producing CD4+ T cells, whereas those generated from healthy mice induced CD4+ FoxP3+ regulatory T cells, in an antigen-dependent manner. This difference is related to the osteoclast origin from monocytes or dendritic cells, to their cytokine expression pattern, and their environment. We identified CX3 CR1 as a marker of inflammatory osteoclasts and we demonstrated that the differentiation of CX3 CR1+ osteoclasts is controlled by IL-17 in vitro. This work is the first demonstration that, in addition to participating to bone destruction, osteoclasts also induce immunogenic CD4+ T cell responses upon inflammation. They highlight CX3 CR1 as a novel dual target for antiresorptive and anti-inflammatory treatment in inflammatory chronic diseases. © 2016 American Society for Bone and Mineral Research.
Asunto(s)
Resorción Ósea/metabolismo , Linfocitos T CD4-Positivos/metabolismo , Receptor 1 de Quimiocinas CX3C/biosíntesis , Regulación de la Expresión Génica , Enfermedades Inflamatorias del Intestino/metabolismo , Osteoclastos/metabolismo , Factor de Necrosis Tumoral alfa/biosíntesis , Animales , Resorción Ósea/etiología , Resorción Ósea/genética , Resorción Ósea/patología , Linfocitos T CD4-Positivos/patología , Receptor 1 de Quimiocinas CX3C/genética , Enfermedades Inflamatorias del Intestino/complicaciones , Enfermedades Inflamatorias del Intestino/genética , Enfermedades Inflamatorias del Intestino/patología , Ratones , Ratones Noqueados , Osteoclastos/patología , Factor de Necrosis Tumoral alfa/genéticaRESUMEN
In addition to MHC restriction and its structural correlate the recognition of an MHC-peptide complex by the TCR, T-cell reactivity is constrained by positive and negative selection in the thymus. While mouse genetic studies have provided compelling evidence for both processes, the actual impact of selection on the mature T-cell repertoire has remained difficult to assess, in particular because it has so far not been possible to follow the intrathymic differentiation of antigen-specific T cells carrying endogenous TCR specificities. In this issue of the European Journal of Immunology, Hesnard et al. [Eur. J. Immunol. 2016. 46: 560-569] report the detection of human antigen-specific immature thymocytes, thereby opening the way to addressing these questions. Here, we discuss the implications of this technological advance.