RESUMO
Thymic epithelial cells (TECs) are crucial to the ability of the thymus to generate T cells for the adaptive immune system in vertebrates. However, no in vitro system for studying TEC function exists. Overexpressing the transcription factor FOXN1 initiates transdifferentiation of fibroblasts into TEC-like cells (iTECs) that support T-cell differentiation in culture or after transplant. In this study, we have characterized iTEC programming at the cellular and molecular level in mouse to determine how it proceeds, and have identified mechanisms that can be targeted for improving this process. These data show that iTEC programming consists of discrete gene expression changes that differ early and late in the process, and that iTECs upregulate markers of both cortical and medullary TEC (cTEC and mTEC) lineages. We demonstrate that promoting proliferation enhances iTEC generation, and that Notch inhibition allows the induction of mTEC differentiation. Finally, we show that MHCII expression is the major difference between iTECs and fetal TECs. MHCII expression was improved by co-culturing iTECs with fetal double-positive T-cells. This study supports future efforts to improve iTEC generation for both research and translational uses.
Assuntos
Diferenciação Celular , Células Epiteliais , Fibroblastos , Fatores de Transcrição Forkhead , Timo , Animais , Células Epiteliais/metabolismo , Células Epiteliais/citologia , Timo/citologia , Timo/metabolismo , Timo/embriologia , Fibroblastos/metabolismo , Fibroblastos/citologia , Fatores de Transcrição Forkhead/metabolismo , Fatores de Transcrição Forkhead/genética , Camundongos , Proliferação de Células , Transdiferenciação Celular , Linfócitos T/citologia , Linfócitos T/metabolismo , Embrião de Mamíferos/citologia , Embrião de Mamíferos/metabolismo , Técnicas de Cocultura , Receptores Notch/metabolismoRESUMO
Monosodium glutamate (MSG) is a flavor enhancer commonly used in modern nutrition. In this study, it was aimed to determine the effect of in ovo administered MSG on the embryonic development of thymus, bursa of Fabricius, and percentages of alpha-naphthyl acetate esterase (ANAE) positive lymphocyte by using histological, histometrical, and enzyme histochemical methods in chickens. For this purpose, 410 fertile eggs were used. The eggs were then divided into five groups: group 1 (control group, n = 40 eggs), group 2 (distilled water-injected group, n = 62 eggs), group 3 (0.12 mg/g egg MSG-injected group, n = 80 eggs), group 4 (0.6 mg/g egg MSG-injected group, n = 90 eggs), and group 5 (1.2 mg/g egg MSG-injected group, n = 138 eggs), and injections were performed via the egg yolk. On the 18th and 21st days of the incubation, the eggs were randomly opened from each group until six live embryos were obtained. The embryos of each group were sacrificed by decapitation, and blood, thymus, and bursa of Fabricius tissue samples were taken from the obtained embryos. The MSG-treated groups were found to be retarded embryonic development of thymus and bursa of Fabricius tissue compared to the control and distilled water groups. MSG treatment also resulted in reduced lymphoid follicles count and follicle diameters in bursa of Fabricius (P < 0.05). The percentage of peripheral blood ANAE positive lymphocytes was significantly lower in the MSG-treated groups than in the control and distilled water groups (P < 0.05). In conclusion, it has been found that in ovo administered MSG can adversely affect the embryonic development of thymus and bursa of Fabricius and decrease percentage of ANAE positive lymphocyte.
Assuntos
Bolsa de Fabricius , Galinhas , Linfócitos , Timo , Animais , Bolsa de Fabricius/embriologia , Embrião de Galinha , Desenvolvimento Embrionário , Naftol AS D Esterase , Glutamato de Sódio/farmacologia , Timo/embriologia , ÁguaRESUMO
OBJECTIVE: The immunological factors have role in the development of preeclampsia. The thymus is one of the main organs of the fetal immune system. The aim of this prospective clinical study was to investigate the association between fetal thymus volume and preeclampsia by adding the 3-dimensional measurement of thymus volume to the routine fetal ultrasound scan at 11-14 week of gestation. STUDY DESIGN: Totally 72 pregnant women in their first trimester of pregnancy were included and 3-D fetal thymus volume was measured with sonographic VOCAL programme. All women gestational period was followed. The data of women with preeclampsia (n = 10, study group) and without preeclampsia (n = 62, control group) were compared. MAIN OUTCOME MEASURES: Fetal thymus volume, preeclampsia development. RESULTS: Fetal thymus volume, mean gestational age at birth and newborn birthweight were found to be statistically lower in cases with preeclampsia compared with those without any complications. When the fetal thymus volume measured by the VOCAL programme in the study group was used as a marker for preeclampsia development, the limit value was 0.0375 cm3; sensitivity was 87.1% and specificity was 50% (AUC 85.3%, P < .001, 95% CI 0.751-0.949). As a result of binary logistic regression analysis; the low fetal thymus volume measured at 11-14 gestational weeks can be used as a predictive factor for preeclampsia (P < .001). CONCLUSIONS: According to the results of this study; the development of preeclampsia may be predicted by measuring 3-D fetal thymus volume at the first trimester.
Assuntos
Pré-Eclâmpsia/diagnóstico , Timo/embriologia , Adulto , Biomarcadores/análise , Estudos de Casos e Controles , Feminino , Humanos , Imageamento Tridimensional/métodos , Gravidez , Primeiro Trimestre da Gravidez , Estudos Prospectivos , Sensibilidade e Especificidade , Timo/diagnóstico por imagem , Ultrassonografia Pré-Natal/métodosRESUMO
Immunosenescence is a hallmark of aging and manifests as increased susceptibility to infection, autoimmunity, and cancer in the elderly. One component of immunosenescence is thymic involution, age-associated shrinkage of the thymus, observed in all vertebrates studied to date. The naked mole rat (Heterocephalus glaber) has become an attractive animal model in aging research due to its extreme longevity and resistance to disease. Here, we show that naked mole rats display no thymic involution up to 11 years of age. Furthermore, we found large ectopic cervical thymi in addition to the canonical thoracic thymus, both being identical in their cell composition. The developmental landscape in naked mole rat thymi revealed overt differences from the murine T-cell compartment, most notably a decrease of CD4+ /CD8+ double-positive cells and lower abundance of cytotoxic effector T cells. Our observations suggest that naked mole rats display a delayed immunosenescence. Therapeutic interventions aimed at reversing thymic aging remain limited, underscoring the importance of understanding the cellular and molecular mechanisms behind a sustained immune function in the naked mole rat.
Assuntos
Longevidade/fisiologia , Timo/embriologia , Animais , Modelos Animais de Doenças , Masculino , Ratos-Toupeira , RatosRESUMO
Alternative pre-mRNA splicing is a critical step to generate multiple transcripts, thereby dramatically enlarging the proteomic diversity. Thus, a common feature of most alternative splicing factor knockout models is lethality. However, little is known about lineage-specific alternative splicing regulators in a physiological setting. Here, we report that NSrp70 is selectively expressed in developing thymocytes, highest at the double-positive (DP) stage. Global splicing and transcriptional profiling revealed that NSrp70 regulates the cell cycle and survival of thymocytes by controlling the alternative processing of various RNA splicing factors, including the oncogenic splicing factor SRSF1. A conditional-knockout of Nsrp1 (NSrp70-cKO) using CD4Cre developed severe defects in T cell maturation to single-positive thymocytes, due to insufficient T cell receptor (TCR) signaling and uncontrolled cell growth and death. Mice displayed severe peripheral lymphopenia and could not optimally control tumor growth. This study establishes a model to address the function of lymphoid-lineage-specific alternative splicing factor NSrp70 in a thymic T cell developmental pathway.
Assuntos
Processamento Alternativo/genética , Carcinogênese/metabolismo , Desenvolvimento Embrionário/genética , Hematopoese/genética , Melanoma/metabolismo , Timócitos/metabolismo , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Apoptose/genética , Carcinogênese/genética , Proliferação de Células/genética , Genômica , Células HEK293 , Humanos , Lectinas Tipo C/metabolismo , Linfopenia/genética , Linfopenia/metabolismo , Melanoma/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Reação em Cadeia da Polimerase , RNA-Seq , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Antígenos de Linfócitos T/metabolismo , Fatores de Processamento de Serina-Arginina/genética , Fatores de Processamento de Serina-Arginina/metabolismo , Timo/embriologia , Timo/metabolismoRESUMO
The appearance of the paediatric thymus changes as the normal process of thymic involution occurs. Thymic tissue may be orthotopic within the anterior mediastinum or ectopically located along the course of its embryological development. The variable appearance of orthotopic and ectopic thymic tissue in children on imaging studies may lead to misinterpretation of the normal thymus as pathology. Recognition of normal thymic tissue can mitigate unnecessary further diagnostic testing and patient anxiety. In this review, we discuss the embryological development and anatomical variants of normal thymus, and demonstrate the multimodality imaging features of the normal thymus in children, including positron-emission tomography, and diffusion-weighted imaging and in- and opposed-phase imaging on magnetic resonance imaging. We demonstrate the normal thymus mimicking pathological processes and discuss features that distinguish normal thymus, including thymic rebound hyperplasia, from pathology.
Assuntos
Coristoma/diagnóstico por imagem , Timo , Hiperplasia do Timo/diagnóstico por imagem , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Timo/diagnóstico por imagem , Timo/embriologia , Timo/crescimento & desenvolvimentoRESUMO
The thymus supports T-cell development via specialized microenvironments that ensure a diverse, functional and self-tolerant T-cell population. These microenvironments are classically defined as distinct cortex and medulla regions that each contain specialized subsets of stromal cells. Extensive research on thymic epithelial cells (TEC) within the cortex and medulla has defined their essential roles during T-cell development. Significantly, there are additional non-epithelial stromal cells (NES) that exist alongside TEC within thymic microenvironments, including multiple subsets of mesenchymal and endothelial cells. In contrast to our current understanding of TEC biology, the developmental origins, lineage relationships, and functional properties, of NES remain poorly understood. However, experimental evidence suggests these cells are important for thymus function by either directly influencing T-cell development, or by indirectly regulating TEC development and/or function. Here, we focus attention on the contribution of NES to thymic microenvironments, including their phenotypic identification and functional classification, and explore their impact on thymus function.
Assuntos
Comunicação Celular , Células Endoteliais/metabolismo , Células-Tronco Mesenquimais/metabolismo , Timócitos/metabolismo , Timo/metabolismo , Animais , Microambiente Celular , Células Endoteliais/imunologia , Humanos , Células-Tronco Mesenquimais/imunologia , Organogênese , Fenótipo , Transdução de Sinais , Timócitos/imunologia , Timo/embriologia , Timo/imunologiaRESUMO
The thymus' key function in the immune system is to provide the necessary environment for the development of diverse and self-tolerant T lymphocytes. While recent evidence suggests that the thymic stroma is comprised of more functionally distinct subpopulations than previously appreciated, the extent of this cellular heterogeneity in the human thymus is not well understood. Here we use single-cell RNA sequencing to comprehensively profile the human thymic stroma across multiple stages of life. Mesenchyme, pericytes and endothelial cells are identified as potential key regulators of thymic epithelial cell differentiation and thymocyte migration. In-depth analyses of epithelial cells reveal the presence of ionocytes as a medullary population, while the expression of tissue-specific antigens is mapped to different subsets of epithelial cells. This work thus provides important insight on how the diversity of thymic cells is established, and how this heterogeneity contributes to the induction of immune tolerance in humans.
Assuntos
Células Epiteliais/metabolismo , Perfilação da Expressão Gênica/métodos , Heterogeneidade Genética , Análise de Célula Única/métodos , Timo/metabolismo , Adulto , Animais , Diferenciação Celular/genética , Linhagem da Célula/genética , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Humanos , Mesoderma/citologia , Mesoderma/metabolismo , Camundongos , Pericitos/citologia , Pericitos/metabolismo , Linfócitos T/citologia , Linfócitos T/metabolismo , Timócitos/citologia , Timócitos/metabolismo , Timo/citologia , Timo/embriologiaRESUMO
T-Cell development is a major branch of lymphoid development and a key output of hematopoiesis, especially in early life, but the molecular requirements for T-cell potential have remained obscure. Considerable advances have now been made toward solving this problem through single-cell transcriptome studies, interfaced with in vitro differentiation assays that monitor potential efficiently at the single-cell level. This review focuses on a series of recent reports studying mouse and human early T-cell precursors, both in the developing fetus and in stringently purified postnatal samples of intrathymic and prethymic T-lineage precursors. Cross-comparison of results reveals a robustly conserved core program in mouse and human, but with some informative and provocative variations between species and between ontogenic states. Repeated findings are the multipotent progenitor regulatory signature of thymus-seeding cells and the proximity of the T-cell program to dendritic cell programs, especially to plasmacytoid dendritic cells in humans.
Assuntos
Hematopoese , Células Precursoras de Linfócitos T/citologia , Análise de Célula Única/métodos , Animais , Antígenos de Diferenciação de Linfócitos T/análise , Linhagem da Célula , Movimento Celular , Separação Celular , Células Cultivadas , Células Dendríticas/citologia , Feto/citologia , Feto/imunologia , Regulação da Expressão Gênica no Desenvolvimento , Hematopoese/genética , Humanos , Camundongos , Células-Tronco Multipotentes/citologia , Células Precursoras de Linfócitos T/classificação , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Proteínas Repressoras/fisiologia , Especificidade da Espécie , Timo/citologia , Timo/embriologia , Timo/crescimento & desenvolvimento , Transcriptoma , Proteínas Supressoras de Tumor/fisiologiaRESUMO
Type 2 innate lymphoid cells (ILC2) contribute to immune homeostasis, protective immunity and tissue repair. Here we demonstrate that functional ILC2 cells can arise in the embryonic thymus from shared T cell precursors, preceding the emergence of CD4+CD8+ (double-positive) T cells. Thymic ILC2 cells migrated to mucosal tissues, with colonization of the intestinal lamina propria. Expression of the transcription factor RORα repressed T cell development while promoting ILC2 development in the thymus. From RNA-seq, assay for transposase-accessible chromatin sequencing (ATAC-seq) and chromatin immunoprecipitation followed by sequencing (ChIP-seq) data, we propose a revised transcriptional circuit to explain the co-development of T cells and ILC2 cells from common progenitors in the thymus. When Notch signaling is present, BCL11B dampens Nfil3 and Id2 expression, permitting E protein-directed T cell commitment. However, concomitant expression of RORα overrides the repression of Nfil3 and Id2 repression, allowing ID2 to repress E proteins and promote ILC2 differentiation. Thus, we demonstrate that RORα expression represents a critical checkpoint at the bifurcation of the T cell and ILC2 lineages in the embryonic thymus.
Assuntos
Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular , Linhagem da Célula , Imunidade Inata , Membro 1 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Timócitos/metabolismo , Timo/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Movimento Celular , Células Cultivadas , Técnicas de Cocultura , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Proteína 2 Inibidora de Diferenciação/genética , Proteína 2 Inibidora de Diferenciação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Membro 1 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Técnicas de Cultura de Órgãos , Fenótipo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transdução de Sinais , Timócitos/imunologia , Timo/embriologia , Timo/imunologia , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismoRESUMO
During embryonic development, multiple waves of hematopoietic progenitors with distinct lineage potential are differentially regulated in time and space. Two different waves of thymic progenitors colonize the fetal thymus where they contribute to thymic organogenesis and homeostasis. The origin, the lineage differentiation potential of the first wave, and their relative contribution in shaping the thymus architecture, remained, however, unclear. Here, we show that the first wave of thymic progenitors comprises a unique population of bipotent T and innatel lymphoid cells (T/ILC), generating a lymphoid tissue inducer cells (LTi's), in addition to invariant Vγ5+ T cells. Transcriptional analysis revealed that innate lymphoid gene signatures and, more precisely, the LTi-associated transcripts were expressed in the first, but not in the second, wave of thymic progenitors. Depletion of early thymic progenitors in a temporally controlled manner showed that the progeny of the first wave is indispensable for the differentiation of autoimmune regulator-expressing medullary thymic epithelial cells (mTECs). We further show that these progenitors are of strict hematopoietic stem cell origin, despite the overlap between lymphopoiesis initiation and the transient expression of lymphoid-associated transcripts in yolk sac (YS) erythromyeloid-restricted precursors. Our work highlights the relevance of the developmental timing on the emergence of different lymphoid subsets, required for the establishment of a functionally diverse immune system.
Assuntos
Células Progenitoras Linfoides/citologia , Linfócitos T/citologia , Timo/citologia , Timo/embriologia , Animais , Células Cultivadas , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Células Progenitoras Linfoides/metabolismo , Linfopoese , Camundongos Endogâmicos C57BL , Linfócitos T/metabolismo , Timo/metabolismo , TranscriptomaRESUMO
INTRODUCTION: Infection and inflammation have been implicated in the etiology and subsequent morbidity associated with preterm birth. At present, there are no tests to assess for fetal compartment infection. The thymus, a gland integral in the fetal immune system, has been shown to involute in animal models of antenatal infection, but its response in human fetuses has not been studied. This study aims: (a) to generate magnetic resonance imaging (MRI) -derived fetal thymus volumes standardized for fetal weight; (b) to compare standardized thymus volumes from fetuses that delivered before 32 weeks of gestation with fetuses that subsequently deliver at term; (c) to assess thymus size as a predictor of preterm birth; and (d) to correlate the presence of chorioamnionitis and funisitis at delivery with thymic volumes in utero in fetuses that subsequently deliver preterm. MATERIAL AND METHODS: Women at high-risk of preterm birth at 20-32 weeks of gestation were recruited. A control group was obtained from existing data sets acquired as part of three research studies. A fetal MRI was performed on a 1.5T or 3T MRI scanner: T2 weighted images were obtained of the entire uterine content and specifically the fetal thorax. A slice-to-volume registration method was used for reconstruction of three-dimensional images of the thorax. Thymus segmentations were performed manually. Body volumes were calculated by manual segmentation and thymus:body volume ratios were generated. Comparison of groups was performed using multiple regression analysis. Normal ranges were created for thymus volume and thymus:body volume ratios using the control data. Receiver operating curves (ROC) curves were generated for thymus:body volume ratio and gestation-adjusted thymus volume centiles as predictors of preterm birth. Placental histology was analyzed where available from pregnancies that delivered very preterm and the presence of chorioamnionitis/funisitis was noted. RESULTS: Normative ranges were created for thymus volume, and thymus volume was standardized for fetal size from fetuses that subsequently delivered at term, but were imaged at 20-32 weeks of gestation. Image data sets from 16 women that delivered <32 weeks of gestation (ten with ruptured membranes and six with intact membranes) and 80 control women that delivered >37 weeks were included. Mean gestation at MRI of the study group was 28+4 weeks (SD 3.2) and for the control group was 25+5 weeks (SD 2.4). Both absolute fetal thymus volumes and thymus:body volume ratios were smaller in fetuses that delivered preterm (P < .001). Of the 16 fetuses that delivered preterm, 13 had placental histology, 11 had chorioamnionitis, and 9 had funisitis. The strongest predictors of prematurity were the thymus volume Z-score and thymus:body volume ratio Z-score (ROC areas 0.915 and 0.870, respectively). CONCLUSIONS: We have produced MRI-derived normal ranges for fetal thymus and thymus:body volume ratios between 20 and 32 weeks of gestation. Fetuses that deliver very preterm had reduced thymus volumes when standardized for fetal size. A reduced thymus volume was also a predictor of spontaneous preterm delivery. Thymus volume may be a suitable marker of the fetal inflammatory response, although further work is needed to assess this, increasing the sample size to correlate the extent of chorioamnionitis with thymus size.
Assuntos
Nascimento Prematuro/diagnóstico por imagem , Timo/diagnóstico por imagem , Timo/fisiologia , Ultrassonografia Pré-Natal/métodos , Adulto , Estudos de Casos e Controles , Feminino , Ruptura Prematura de Membranas Fetais/diagnóstico por imagem , Idade Gestacional , Humanos , Recém-Nascido , Imageamento por Ressonância Magnética , Tamanho do Órgão/fisiologia , Projetos Piloto , Gravidez , Gravidez de Alto Risco , Timo/embriologia , Timo/patologiaAssuntos
Veias Braquiocefálicas/anormalidades , Ecocardiografia , Timo/embriologia , Malformações Vasculares/embriologia , Veia Cava Superior/anormalidades , Adulto , Veias Braquiocefálicas/diagnóstico por imagem , Veias Braquiocefálicas/embriologia , Feminino , Humanos , Ilustração Médica , Gravidez , Timo/irrigação sanguínea , Timo/diagnóstico por imagem , Ultrassonografia Pré-Natal , Malformações Vasculares/diagnóstico por imagem , Veia Cava Superior/diagnóstico por imagem , Veia Cava Superior/embriologiaRESUMO
Activation of the aryl hydrocarbon receptor (AHR) by the environmental toxin dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) causes diverse toxicities, including thymus atrophy and hepatosteatosis. The mechanisms by which AHR activation by TCDD leads to these toxicities are not fully understood. Here we studied the effects of TCDD on a major energy pathway, glycolysis, using the chick embryo close to hatching, a well-established model for studying dioxin toxicity. We showed that 24 hr of TCDD treatment causes changes in glycolysis in both thymus and liver. In thymus glands, TCDD decreased mRNAs for glycolytic genes and glucose transporters, glycolytic indices and levels of IL7 mRNA, phosphorylated AKT (pAKT) and HIF1A, stimulators of glycolysis and promoters of survival and proliferation of thymic lymphocytes. In contrast, in liver, TCDD increased mRNA levels for glycolytic genes and glucose transporters, glycolytic endpoints and pAKT levels. Similarly, increases by TCDD in mRNA levels for glycolytic genes and glucose transporters in human primary hepatocytes showed that effects in chick embryo liver pertain also to human cells. Treatment with the glycolytic inhibitor 2-deoxy-d-glucose exacerbated the effects on thymus atrophy by TCDD, supporting a role for decreased glycolysis in thymus atrophy by TCDD, but did not prevent hepatosteatosis. NAD+ precursors abolished TCDD effects on glycolytic endpoints in both thymus and liver. In summary, we report here that dioxin disrupts glycolysis mediated energy metabolism in both thymus and liver, and that it does so in opposite ways, decreasing it in the thymus and increasing it in the liver. Further, the findings support NAD+ boosting as a strategy against metabolic effects of environmental pollutants such as dioxins.
Assuntos
Dioxinas/toxicidade , Glicólise/efeitos dos fármacos , Especificidade de Órgãos/efeitos dos fármacos , Receptores de Hidrocarboneto Arílico/metabolismo , Adulto , Animais , Células Cultivadas , Embrião de Galinha , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Glicólise/genética , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Niacinamida/análogos & derivados , Niacinamida/metabolismo , Dibenzodioxinas Policloradas/toxicidade , Compostos de Piridínio , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Timo/efeitos dos fármacos , Timo/embriologia , Timo/metabolismoRESUMO
Combined Immunodeficiencies (CID) are rare congenital disorders characterized by defective T-cell development that may be associated with B- and NK-cell deficiency. They are usually due to alterations in genes expressed in hematopoietic precursors but in few cases, they are caused by impaired thymic development. Athymia was classically associated with DiGeorge Syndrome due to TBX1 gene haploinsufficiency. Other genes, implicated in thymic organogenesis include FOXN1, associated with Nude SCID syndrome, PAX1, associated with Otofaciocervical Syndrome type 2, and CHD7, one of the genes implicated in CHARGE syndrome. More recently, chromosome 2p11.2 microdeletion, causing FOXI3 haploinsufficiency, has been identified in 5 families with impaired thymus development. In this review, we will summarize the main genetic, clinical, and immunological features related to the abovementioned gene mutations. We will also focus on different therapeutic approaches to treat SCID in these patients.
Assuntos
Imunodeficiência Combinada Severa/genética , Imunodeficiência Combinada Severa/imunologia , Imunodeficiência Combinada Severa/patologia , Linfócitos T/imunologia , Timo/anormalidades , Humanos , Timo/embriologia , Timo/imunologiaRESUMO
Maternal influenza A viral infections in humans are associated with low birth weight, increased risk of pre-term birth, stillbirth and congenital defects. To examine the effect of maternal influenza virus infection on placental and fetal growth, pregnant C57BL/6 mice were inoculated intranasally with influenza A virus A/CA/07/2009 pandemic H1N1 or phosphate-buffered saline (PBS) at E3.5, E7.5 or E12.5, and the placentae and fetuses collected and weighed at E18.5. Fetal thymuses were pooled from each litter. Placentae were examined histologically, stained by immunohistochemistry (IHC) for CD34 (hematopoietic progenitor cell antigen) and vascular channels quantified. RNA from E7.5 and E12.5 placentae and E7.5 fetal thymuses was subjected to RNA sequencing and pathway analysis. Placental weights were decreased in litters inoculated with influenza at E3.5 and E7.5. Placentae from E7.5 and E12.5 inoculated litters exhibited decreased labyrinth development and the transmembrane protein 150A gene was upregulated in E7.5 placentae. Fetal weights were decreased in litters inoculated at E7.5 and E12.5 compared to controls. RNA sequencing of E7.5 thymuses indicated that 957 genes were downregulated ≥2-fold including Mal, which is associated with Toll-like receptor signaling and T cell differentiation. There were 28 upregulated genes. It is concluded that maternal influenza A virus infection impairs fetal thymic gene expression as well as restricting placental and fetal growth.
Assuntos
Vírus da Influenza A Subtipo H1N1/fisiologia , Influenza Humana/genética , Influenza Humana/fisiopatologia , Placenta/metabolismo , Efeitos Tardios da Exposição Pré-Natal/genética , Timo/metabolismo , Transcriptoma , Animais , Feminino , Desenvolvimento Fetal , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Influenza Humana/embriologia , Influenza Humana/virologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Placenta/virologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Efeitos Tardios da Exposição Pré-Natal/virologia , Timo/embriologiaRESUMO
Innate and adaptive immune systems continuously interchange information and orchestrate their immune responses to protect the host. γδT cells play crucial roles, as they incorporate both innate and adaptive immune characteristics. Dendritic epidermal T cells (DETC) are specialized γδT cells, which are uniquely positioned to rapidly respond to skin wounds and infections. Their elongated dendrite morphology allows them to be in continuous contact with multiple neighboring keratinocytes and Langerhans cells. Cellular interactions are fundamental to the formation, activation and maintenance of immune cell functions during steady state and pathology. Recent technological advances, especially in the field of cellular imaging, have contributed greatly to the characterization of complex cellular interactions in a spatiotemporally resolved manner. In this review, we will highlight the often-underappreciated function of DETC and other γδT cells during steady state and an ongoing immune response. More specifically, we discuss how DETC-precursors are shaped in the fetal thymus during embryogenesis as well as how direct cell-cell interactions of DETC with neighboring epidermal cells shape skin homeostasis and effector functions. Furthermore, we will discuss seminal work and recent discoveries made in the γδT cell field, which have highlighted the importance of γδT cells in the skin, both in humans and mice.
Assuntos
Células Epidérmicas/imunologia , Epiderme/imunologia , Linfócitos Intraepiteliais/imunologia , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Imunidade Adaptativa , Animais , Comunicação Celular , Microambiente Celular , Desenvolvimento Embrionário , Células Epidérmicas/metabolismo , Epiderme/metabolismo , Humanos , Imunidade Inata , Linfócitos Intraepiteliais/metabolismo , Fenótipo , Transdução de Sinais , Timo/embriologia , Timo/imunologia , Timo/metabolismoRESUMO
The thymus generates central immune tolerance by producing self-restricted and self-tolerant T-cells as a result of interactions between the developing thymocytes and the stromal microenvironment, mainly formed by the thymic epithelial cells. The thymic epithelium derives from the endoderm of the pharyngeal pouches, embryonic structures that rely on environmental cues from the surrounding mesenchyme for its development. Here, we review the most recent advances in our understanding of the molecular mechanisms involved in early thymic organogenesis at stages preceding the expression of the transcription factor Foxn1, the early marker of thymic epithelial cells identity. Foxn1-independent developmental stages, such as the specification of the pharyngeal endoderm, patterning of the pouches, and thymus fate commitment are discussed, with a special focus on epithelial-mesenchymal interactions.
Assuntos
Organogênese , Timo/crescimento & desenvolvimento , Animais , Humanos , Transdução de Sinais , Timo/embriologia , Fatores de Transcrição/metabolismoRESUMO
Down syndrome fits an immunophenotype of combined immunodeficiency with immunodysregulation, manifesting with increased susceptibility to infections, autoimmunity, autoinflammatory diseases, and hematologic malignancies. Qualitative and quantitative alterations in innate and adaptive immunity are found in most individuals with Down syndrome. However, there is substantial heterogeneity and no correlation between immunophenotype and clinical presentation. Previously, it was thought that the immunological changes in Down syndrome were caused by precocious aging. We emphasize in this review that the immune system in Down syndrome is intrinsically different from the very beginning. The overexpression of specific genes located on chromosome 21 contributes to immunodeficiency and immunodysregulation, but gene expression differs between genes located on chromosome 21 and depends on tissue and cell type. In addition, trisomy 21 results in gene dysregulation of the whole genome, reflecting the complex nature of this syndrome in comparison to well-known inborn errors of immunity that result from monogenic germline mutations. In this review, we provide an updated overview focusing on inborn errors of adaptive immunity in Down syndrome.
Assuntos
Imunidade Adaptativa/genética , Síndrome de Down/genética , Síndrome de Down/imunologia , Doenças da Imunodeficiência Primária/genética , Doenças da Imunodeficiência Primária/imunologia , Animais , Autoimunidade/genética , Biomarcadores , Relação CD4-CD8 , Sobrevivência Celular/genética , Sobrevivência Celular/imunologia , Citocinas/metabolismo , Suscetibilidade a Doenças , Humanos , Sistema Imunitário/imunologia , Sistema Imunitário/metabolismo , Imunidade Inata/genética , Mediadores da Inflamação/metabolismo , Interferons/metabolismo , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Modelos Biológicos , Receptores de Antígenos de Linfócitos T , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Timo/embriologia , Timo/imunologia , Timo/metabolismoRESUMO
22q11.2 deletion syndrome (DiGeorge), CHARGE syndrome, Nude/SCID and otofaciocervical syndrome type 2 (OTFCS2) are distinct clinical conditions in humans that can result in hypoplasia and occasionally, aplasia of the thymus. Thymic hypoplasia/aplasia is first suggested by absence or significantly reduced numbers of recent thymic emigrants, revealed in standard-of-care newborn screens for T cell receptor excision circles (TRECs). Subsequent clinical assessments will often indicate whether genetic mutations are causal to the low T cell output from the thymus. However, the molecular mechanisms leading to the thymic hypoplasia/aplasia in diverse human syndromes are not fully understood, partly because the problems of the thymus originate during embryogenesis. Rodent and Zebrafish models of these clinical syndromes have been used to better define the underlying basis of the clinical presentations. Results from these animal models are uncovering contributions of different cell types in the specification, differentiation, and expansion of the thymus. Cell populations such as epithelial cells, mesenchymal cells, endothelial cells, and thymocytes are variably affected depending on the human syndrome responsible for the thymic hypoplasia. In the current review, findings from the diverse animal models will be described in relation to the clinical phenotypes. Importantly, these results are suggesting new strategies for regenerating thymic tissue in patients with distinct congenital disorders.