Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 116
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Biol Chem ; 294(37): 13638-13656, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31337704

RESUMO

Magnesium transporter 1 (MAGT1) critically mediates magnesium homeostasis in eukaryotes and is highly-conserved across different evolutionary branches. In humans, loss-of-function mutations in the MAGT1 gene cause X-linked magnesium deficiency with Epstein-Barr virus (EBV) infection and neoplasia (XMEN), a disease that has a broad range of clinical and immunological consequences. We have previously shown that EBV susceptibility in XMEN is associated with defective expression of the antiviral natural-killer group 2 member D (NKG2D) protein and abnormal Mg2+ transport. New evidence suggests that MAGT1 is the human homolog of the yeast OST3/OST6 proteins that form an integral part of the N-linked glycosylation complex, although the exact contributions of these perturbations in the glycosylation pathway to disease pathogenesis are still unknown. Using MS-based glycoproteomics, along with CRISPR/Cas9-KO cell lines, natural killer cell-killing assays, and RNA-Seq experiments, we now demonstrate that humans lacking functional MAGT1 have a selective deficiency in both immune and nonimmune glycoproteins, and we identified several critical glycosylation defects in important immune-response proteins and in the expression of genes involved in immunity, particularly CD28. We show that MAGT1 function is partly interchangeable with that of the paralog protein tumor-suppressor candidate 3 (TUSC3) but that each protein has a different tissue distribution in humans. We observed that MAGT1-dependent glycosylation is sensitive to Mg2+ levels and that reduced Mg2+ impairs immune-cell function via the loss of specific glycoproteins. Our findings reveal that defects in protein glycosylation and gene expression underlie immune defects in an inherited disease due to MAGT1 deficiency.

2.
J Exp Med ; 216(8): 1828-1842, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31196981

RESUMO

Mg2+ is required at micromolar concentrations as a cofactor for ATP, enzymatic reactions, and other biological processes. We show that decreased extracellular Mg2+ reduced intracellular Mg2+ levels and impaired the Ca2+ flux, activation marker up-regulation, and proliferation after T cell receptor (TCR) stimulation. Reduced Mg2+ specifically impairs TCR signal transduction by IL-2-inducible T cell kinase (ITK) due to a requirement for a regulatory Mg2+ in the catalytic pocket of ITK. We also show that altered catalytic efficiency by millimolar changes in free basal Mg2+ is an unrecognized but conserved feature of other serine/threonine and tyrosine kinases, suggesting a Mg2+ regulatory paradigm of kinase function. Finally, a reduced serum Mg2+ concentration in mice causes an impaired CD8+ T cell response to influenza A virus infection, reduces T cell activation, and exacerbates morbidity. Thus, Mg2+ directly regulates the active site of specific kinases during T cell responses, and maintaining a high serum Mg2+ concentration is important for antiviral immunity in otherwise healthy animals.

3.
J Exp Med ; 216(6): 1311-1327, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31040185

RESUMO

Interleukin-2, which conveys essential signals for immunity, operates through a heterotrimeric receptor. Here we identify human interleukin-2 receptor (IL-2R) ß chain (IL2RB) gene defects as a cause of life-threatening immune dysregulation. We report three homozygous mutations in the IL2RB gene of eight individuals from four consanguineous families that cause disease by distinct mechanisms. Nearly all patients presented with autoantibodies, hypergammaglobulinemia, bowel inflammation, dermatological abnormalities, lymphadenopathy, and cytomegalovirus disease. Patient T lymphocytes lacked surface expression of IL-2Rß and were unable to respond to IL-2 stimulation. By contrast, natural killer cells retained partial IL-2Rß expression and function. IL-2Rß loss of function was recapitulated in a recombinant system in which IL2RB mutations caused reduced surface expression and IL-2 binding. Stem cell transplant ameliorated clinical symptoms in one patient; forced expression of wild-type IL-2Rß also increased the IL-2 responsiveness of patient T lymphocytes in vitro. Insights from these patients can inform the development of IL-2-based therapeutics for immunological diseases and cancer.

4.
J Exp Med ; 216(6): 1244-1254, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31068379

RESUMO

Since the early 20th century, immunologists have investigated mechanisms that protect vertebrates from damaging immune responses against self-antigens by mature lymphocytes, i.e., peripheral tolerance. These mechanisms have been increasingly delineated at the molecular level, ultimately culminating in new therapeutics that have revolutionized clinical oncology. Here, we describe basic science and clinical discoveries that converge mainly on two molecules, CTLA-4 and PD-1, that were recognized with the 2018 Nobel Prize in Physiology or Medicine awarded to James Allison and Tasuku Honjo. We discuss their investigations and those of many others in the field that contravene tolerance through checkpoint inhibition to boost immune killing of malignant cells. We also discuss the mechanisms underlying each therapy, the efficacy achieved, and the complications of therapy. Finally, we hint at research questions for the future that could widen the success of cancer immunotherapy.

7.
Adv Immunol ; 138: 99-193, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29731008

RESUMO

Proper regulation of the immune system is required for protection against pathogens and preventing autoimmune disorders. Inborn errors of the immune system due to inherited or de novo germline mutations can lead to the loss of protective immunity, aberrant immune homeostasis, and the development of autoimmune disease, or combinations of these. Forward genetic screens involving clinical material from patients with primary immunodeficiencies (PIDs) can vary in severity from life-threatening disease affecting multiple cell types and organs to relatively mild disease with susceptibility to a limited range of pathogens or mild autoimmune conditions. As central mediators of innate and adaptive immune responses, T cells are critical orchestrators and effectors of the immune response. As such, several PIDs result from loss of or altered T cell function. PID-associated functional defects range from complete absence of T cell development to uncontrolled effector cell activation. Furthermore, the gene products of known PID causal genes are involved in diverse molecular pathways ranging from T cell receptor signaling to regulators of protein glycosylation. Identification of the molecular and biochemical cause of PIDs can not only guide the course of treatment for patients, but also inform our understanding of the basic biology behind T cell function. In this chapter, we review PIDs with known genetic causes that intrinsically affect T cell function with particular focus on perturbations of biochemical pathways.

9.
Cancer Epidemiol ; 52: 70-74, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29248801

RESUMO

BACKGROUND: Epstein-Barr virus (EBV) causes endemic Burkitt lymphoma (eBL). EBV control was improved by magnesium (Mg2+) supplementation in XMEN, an X-linked genetic disease associated with Mg2+ deficiency, high circulating EBV levels (viral loads), and EBV-related lymphomas. We, therefore, investigated the relationship between Mg2+ levels and EBV levels and eBL in Uganda. METHODS: Plasma Mg2+ was measured in 45 women with low or high circulating EBV levels, 40 pediatric eBL cases, and 79 healthy children. Mg2+ uptake by T-lymphocytes was evaluated in samples from healthy donors. RESULTS: Plasma Mg2+ deficiency (plasma level <1.8 mg/dl) was more likely in women with high- vs. low-EBV levels (76.0% vs. 35%; odds ratio [OR] 11.3, 95% CI 2.14-60.2), controlling for age, and in eBL cases than controls (42.0% vs. 13.9%; OR 3.61, 95% CI 1.32-9.88), controlling for sex, age group, and malaria status. Mg2+ uptake by T-lymphocytes was related to extracellular Mg2+ concentration. INTERPRETATION: Plasma Mg2+ deficiency is associated with high EBV levels and eBL.

10.
J Immunol ; 200(1): 110-118, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29187589

RESUMO

Understanding the control of Ag restimulation-induced T cell death (RICD), especially in cancer immunotherapy, where highly proliferating T cells will encounter potentially large amounts of tumor Ags, is important now more than ever. It has been known that growth cytokines make T cells susceptible to RICD, but the precise molecular mediators that govern this in T cell subsets is unknown until now. STAT proteins are a family of transcription factors that regulate gene expression programs underlying key immunological processes. In particular, STAT5 is known to favor the generation and survival of memory T cells. In this study, we report an unexpected role for STAT5 signaling in the death of effector memory T (TEM) cells in mice and humans. TEM cell death was prevented with neutralizing anti-IL-2 Ab or STAT5/JAK3 inhibitors, indicating that STAT5 signaling drives RICD in TEM cells. Moreover, we identified a unique patient with a heterozygous missense mutation in the coiled-coil domain of STAT5B that presented with autoimmune lymphoproliferative syndrome-like features. Similar to Stat5b-/- mice, this patient exhibited increased CD4+ TEM cells in the peripheral blood. The mutant STAT5B protein dominantly interfered with STAT5-driven transcriptional activity, leading to global downregulation of STAT5-regulated genes in patient T cells upon IL-2 stimulation. Notably, CD4+ TEM cells from the patient were strikingly resistant to cell death by in vitro TCR restimulation, a finding that was recapitulated in Stat5b-/- mice. Hence, STAT5B is a crucial regulator of RICD in memory T cells in mice and humans.


Assuntos
Apoptose , Síndrome Linfoproliferativa Autoimune/imunologia , Linfócitos T CD4-Positivos/imunologia , Sobrevivência Celular , Fator de Transcrição STAT5/metabolismo , Animais , Anticorpos Neutralizantes/metabolismo , Síndrome Linfoproliferativa Autoimune/genética , Células Cultivadas , Feminino , Humanos , Memória Imunológica , Interleucina-2/imunologia , Ativação Linfocitária , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação de Sentido Incorreto/genética , Fator de Transcrição STAT5/genética , Transdução de Sinais , Transcrição Genética
12.
Blood ; 130(21): 2307-2316, 2017 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-28972011

RESUMO

Pathogenic gain-of-function variants in the genes encoding phosphoinositide 3-kinase δ (PI3Kδ) lead to accumulation of transitional B cells and senescent T cells, lymphadenopathy, and immune deficiency (activated PI3Kδ syndrome [APDS]). Knowing the genetic etiology of APDS afforded us the opportunity to explore PI3Kδ inhibition as a precision-medicine therapy. Here, we report in vitro and in vivo effects of inhibiting PI3Kδ in APDS. Treatment with leniolisib (CDZ173), a selective PI3Kδ inhibitor, caused dose-dependent suppression of PI3Kδ pathway hyperactivation (measured as phosphorylation of AKT/S6) in cell lines ectopically expressing APDS-causative p110δ variants and in T-cell blasts derived from patients. A clinical trial with 6 APDS patients was conducted as a 12-week, open-label, multisite, within-subject, dose-escalation study of oral leniolisib to assess safety, pharmacokinetics, and effects on lymphoproliferation and immune dysregulation. Oral leniolisib led to a dose-dependent reduction in PI3K/AKT pathway activity assessed ex vivo and improved immune dysregulation. We observed normalization of circulating transitional and naive B cells, reduction in PD-1+CD4+ and senescent CD57+CD4- T cells, and decreases in elevated serum immunoglobulin M and inflammatory markers including interferon γ, tumor necrosis factor, CXCL13, and CXCL10 with leniolisib therapy. After 12 weeks of treatment, all patients showed amelioration of lymphoproliferation with lymph node sizes and spleen volumes reduced by 39% (mean; range, 26%-57%) and 40% (mean; range, 13%-65%), respectively. Thus, leniolisib was well tolerated and improved laboratory and clinical parameters in APDS, supporting the specific inhibition of PI3Kδ as a promising new targeted therapy in APDS and other diseases characterized by overactivation of the PI3Kδ pathway. This trial was registered at www.clinicaltrials.gov as #NCT02435173.


Assuntos
Classe I de Fosfatidilinositol 3-Quinases/antagonistas & inibidores , Síndromes de Imunodeficiência/tratamento farmacológico , Síndromes de Imunodeficiência/enzimologia , Terapia de Alvo Molecular , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Pirimidinas/farmacologia , Animais , Quimiocinas/sangue , Criança , Pré-Escolar , Classe I de Fosfatidilinositol 3-Quinases/imunologia , Classe I de Fosfatidilinositol 3-Quinases/metabolismo , Demografia , Relação Dose-Resposta a Droga , Feminino , Humanos , Imunoglobulina M/sangue , Síndromes de Imunodeficiência/imunologia , Síndromes de Imunodeficiência/patologia , Lactente , Linfonodos/efeitos dos fármacos , Linfonodos/patologia , Ativação Linfocitária/efeitos dos fármacos , Masculino , Mutação/genética , Tamanho do Órgão , Fenótipo , Piridinas/farmacocinética , Pirimidinas/farmacocinética , Ratos , Baço/efeitos dos fármacos , Baço/patologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Transfecção
14.
N Engl J Med ; 377(1): 52-61, 2017 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-28657829

RESUMO

BACKGROUND: Studies of monogenic gastrointestinal diseases have revealed molecular pathways critical to gut homeostasis and enabled the development of targeted therapies. METHODS: We studied 11 patients with abdominal pain and diarrhea caused by early-onset protein-losing enteropathy with primary intestinal lymphangiectasia, edema due to hypoproteinemia, malabsorption, and less frequently, bowel inflammation, recurrent infections, and angiopathic thromboembolic disease; the disorder followed an autosomal recessive pattern of inheritance. Whole-exome sequencing was performed to identify gene variants. We evaluated the function of CD55 in patients' cells, which we confirmed by means of exogenous induction of expression of CD55. RESULTS: We identified homozygous loss-of-function mutations in the gene encoding CD55 (decay-accelerating factor), which lead to loss of protein expression. Patients' T lymphocytes showed increased complement activation causing surface deposition of complement and the generation of soluble C5a. Costimulatory function and cytokine modulation by CD55 were defective. Genetic reconstitution of CD55 or treatment with a complement-inhibitory therapeutic antibody reversed abnormal complement activation. CONCLUSIONS: CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy (the CHAPLE syndrome) is caused by abnormal complement activation due to biallelic loss-of-function mutations in CD55. (Funded by the National Institute of Allergy and Infectious Diseases and others.).


Assuntos
Antígenos CD55/genética , Ativação do Complemento/genética , Proteínas do Sistema Complemento/metabolismo , Mutação , Enteropatias Perdedoras de Proteínas/genética , Trombose/genética , Antígenos CD55/sangue , Criança , Pré-Escolar , Ativação do Complemento/efeitos dos fármacos , Inativadores do Complemento/farmacologia , Feminino , Homozigoto , Humanos , Imunoglobulina A/sangue , Lactente , Intestino Delgado/patologia , Masculino , Linhagem , Enteropatias Perdedoras de Proteínas/complicações , Estatísticas não Paramétricas , Síndrome , Linfócitos T/metabolismo
15.
Nat Immunol ; 18(7): 813-823, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28530713

RESUMO

The transcriptional programs that guide lymphocyte differentiation depend on the precise expression and timing of transcription factors (TFs). The TF BACH2 is essential for T and B lymphocytes and is associated with an archetypal super-enhancer (SE). Single-nucleotide variants in the BACH2 locus are associated with several autoimmune diseases, but BACH2 mutations that cause Mendelian monogenic primary immunodeficiency have not previously been identified. Here we describe a syndrome of BACH2-related immunodeficiency and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency and intestinal inflammation. The mutations disrupted protein stability by interfering with homodimerization or by causing aggregation. We observed analogous lymphocyte defects in Bach2-heterozygous mice. More generally, we observed that genes that cause monogenic haploinsufficient diseases were substantially enriched for TFs and SE architecture. These findings reveal a previously unrecognized feature of SE architecture in Mendelian diseases of immunity: heterozygous mutations in SE-regulated genes identified by whole-exome/genome sequencing may have greater significance than previously recognized.


Assuntos
Doenças Autoimunes/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Síndromes de Imunodeficiência/genética , Corticosteroides/uso terapêutico , Adulto , Doenças Autoimunes/complicações , Colite/complicações , Colite/genética , Colite/patologia , Feminino , Febre/complicações , Febre/tratamento farmacológico , Febre/genética , Haploinsuficiência , Heterozigoto , Humanos , Síndromes de Imunodeficiência/complicações , Linfopenia/complicações , Linfopenia/genética , Masculino , Pessoa de Meia-Idade , Mutação , Pancitopenia/complicações , Pancitopenia/tratamento farmacológico , Pancitopenia/genética , Linhagem , Polimorfismo de Nucleotídeo Único , Recidiva , Infecções Respiratórias/complicações , Infecções Respiratórias/diagnóstico por imagem , Infecções Respiratórias/genética , Esplenomegalia/complicações , Esplenomegalia/genética , Síndrome , Tomografia Computadorizada por Raios X , Adulto Jovem
16.
Diabetologia ; 60(8): 1475-1482, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28455654

RESUMO

AIMS/HYPOTHESIS: Insulin is widely considered to be a driver antigen in type 1 diabetes in humans and in mouse models of the disease. Therefore, insulin or insulin analogues are candidates for tolerogenic drugs to prevent disease onset in individuals with risk of diabetes. Previous experiments have shown that autoimmune diabetes can be prevented in NOD mice by repeated doses of insulin administered via an oral, nasal or parenteral route, but clinical trials in humans have not succeeded. The hypoglycaemic activity of insulin is dose-limiting in clinical studies attempting tolerance and disease prevention. Here, we aimed to investigate the therapeutic potential of metabolically inactive insulin analogue (MII) in NOD mice. METHODS: The tolerogenic potential of MII to prevent autoimmune diabetes was studied by administering multiple i.v. or s.c. injections of MII to non-diabetic 7-12-week-old female NOD mice in three geographical colony locations. The incidence of diabetes was assessed from daily or weekly blood glucose measurements. The effect of MII on insulin autoantibody levels was studied using an electrochemiluminescence-based insulin autoantibody assay. The effect on the number of insulin-reactive CD8+ and CD4+ T lymphocytes in peripheral lymphoid tissue was studied with MHC class I and MHC class II tetramers, respectively. RESULTS: We found that twice-weekly s.c. administration of MII accelerates rather than prevents diabetes. High-dose i.v. treatment did not prevent disease or affect insulin autoantibody levels, but it increased the amount of insulin-reactive CD4+ T lymphocytes in peripheral lymphoid tissue. CONCLUSIONS/INTERPRETATION: Our data suggest that parenteral MII, even when used in high doses, has little or no therapeutic potential in NOD mice and may exacerbate disease.


Assuntos
Diabetes Mellitus Tipo 1/imunologia , Diabetes Mellitus Tipo 1/prevenção & controle , Insulina/uso terapêutico , Animais , Autoanticorpos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Feminino , Citometria de Fluxo , Hibridomas/metabolismo , Insulina/análogos & derivados , Camundongos , Camundongos Endogâmicos NOD , Camundongos Transgênicos
17.
Cell ; 168(1-2): 37-57, 2017 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-28086098

RESUMO

NF-κB was discovered 30 years ago as a rapidly inducible transcription factor. Since that time, it has been found to have a broad role in gene induction in diverse cellular responses, particularly throughout the immune system. Here, we summarize elaborate regulatory pathways involving this transcription factor and use recent discoveries in human genetic diseases to place specific proteins within their relevant medical and biological contexts.


Assuntos
Inflamação/metabolismo , NF-kappa B/história , NF-kappa B/metabolismo , Animais , História do Século XX , História do Século XXI , Humanos , Inflamação/imunologia , Camundongos , Mutação , NF-kappa B/química , NF-kappa B/genética , Transdução de Sinais
18.
J Exp Med ; 214(1): 91-106, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28011864

RESUMO

In this study, we describe four patients from two unrelated families of different ethnicities with a primary immunodeficiency, predominantly manifesting as susceptibility to Epstein-Barr virus (EBV)-related diseases. Three patients presented with EBV-associated Hodgkin's lymphoma and hypogammaglobulinemia; one also had severe varicella infection. The fourth had viral encephalitis during infancy. Homozygous frameshift or in-frame deletions in CD70 in these patients abolished either CD70 surface expression or binding to its cognate receptor CD27. Blood lymphocyte numbers were normal, but the proportions of memory B cells and EBV-specific effector memory CD8+ T cells were reduced. Furthermore, although T cell proliferation was normal, in vitro-generated EBV-specific cytotoxic T cell activity was reduced because of CD70 deficiency. This reflected impaired activation by, rather than effects during killing of, EBV-transformed B cells. Notably, expression of 2B4 and NKG2D, receptors implicated in controlling EBV infection, on memory CD8+ T cells from CD70-deficient individuals was reduced, consistent with their impaired killing of EBV-infected cells. Thus, autosomal recessive CD70 deficiency is a novel cause of combined immunodeficiency and EBV-associated diseases, reminiscent of inherited CD27 deficiency. Overall, human CD70-CD27 interactions therefore play a nonredundant role in T and B cell-mediated immunity, especially for protection against EBV and humoral immunity.


Assuntos
Linfócitos B/imunologia , Ligante CD27/deficiência , Infecções por Vírus Epstein-Barr/complicações , Doença de Hodgkin/etiologia , Síndromes de Imunodeficiência/complicações , Adolescente , Adulto , Ligante CD27/genética , Linfócitos T CD8-Positivos/imunologia , Criança , Citotoxicidade Imunológica , Feminino , Herpesvirus Humano 4/imunologia , Humanos , Memória Imunológica , Masculino , Mutação , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/fisiologia
20.
Blood ; 128(8): 1037-42, 2016 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-27418640

RESUMO

CTLA-4 is a critical inhibitory "checkpoint" molecule of immune activation. Several recent reports have described patients with immune dysregulation and lymphoproliferative disease resulting from 2 different genetic diseases that directly or indirectly cause CTLA-4 deficiency. Numerous articles have also been published describing CTLA-4 blockade in cancer immunotherapy and its side effects, which are ultimately the consequence of treatment-induced CTLA-4 deficiency. Here, we review these 2 diseases and CTLA-4 blockade therapy, emphasizing the crucial role of CTLA-4 in immune checkpoint regulation.


Assuntos
Antígeno CTLA-4/genética , Pontos de Checagem do Ciclo Celular/genética , Doenças do Sistema Imunitário/genética , Humanos , Doenças do Sistema Imunitário/terapia , Imunoterapia , Mutação/genética , Fenótipo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA