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1.
Dev Cell ; 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31607651

RESUMO

There are limited data on fetal and early life development of human intestinal immunity. Using mass cytometry (CyTOF) and next-generation sequencing of B and T cell receptor (BCR and TCR) repertoires, we demonstrate complex intestinal immunity from 16 weeks' gestational age (GA). Both BCR and TCR repertoires are diverse with CDRH and CDR3ß length increasing with advancing GA. The difference-from-germline, CDR insertions and/or deletions, similarly occur in utero for TCR but not BCR, suggesting earlier mucosal T than B cell maturity. Innate immunity is dominated by macrophages, dendritic cells (DCs), innate lymphoid cells (ILCs), and natural killer (NK) cells. Follicular and transitional B cells are enriched in fetuses while CD69+IgM+ B cells are abundant in infants. Both CD4+ and CD8+ T cells are abundant, capable of secreting cytokines and are phenotypically of the tissue resident memory state in utero. Our data provide the foundation for a 2nd trimester and infant intestinal immune atlas and suggest that a complex innate and adaptive immune landscape exists significantly earlier than previously reported.

2.
Blood ; 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31501153

RESUMO

Dysregulated immune responses are essential underlying causes of a plethora of pathologies including cancer, autoimmunity and immunodeficiency. We here investigated four patients from unrelated families presenting with immunodeficiency, autoimmunity, and malignancy. We identified four distinct homozygous mutations in TNFRSF9 encoding the Tumor Necrosis Factor superfamily member CD137/4-1BB, leading to reduced or loss of protein expression. Lymphocytic responses crucial for immune surveillance, including activation, proliferation, and differentiation, were impaired. Genetic reconstitution of CD137 reversed these defects. CD137 deficiency is a novel inborn error of human immunity characterized by lymphocytic defects with early-onset Epstein-Barr virus (EBV)-associated lymphoma. Our findings elucidate a functional role and relevance of CD137 in human immune homeostasis and antitumor responses.

3.
Front Immunol ; 10: 1672, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31379863

RESUMO

The alpha subunit of IL-7 receptor (IL7R7α) is critical for the differentiation of T cells, specifically for the development and maintenance of γδT cells. Mutations in IL7RA are associated with Severe Combined Immunodeficiency (SCID). Infants with IL7RA deficiency can be identified through newborn screening program. We aimed at defining the immunological and genetic parameters that are directly affected by the IL7RA mutation on the immune system of five unrelated patients which were identified by our newborn screening program for SCID. The patients were found to have a novel identical homozygote mutation in IL7RA (n.c.120 C>G; p.F40L). Both surface expression of IL7Rα and functionality of IL-7 signaling were impaired in patients compared to controls. Structural modeling demonstrated instability of the protein structure due to the mutation. Lastly the TRG immune repertoire of the patients showed reduced diversity, increased clonality and differential CDR3 characteristics. Interestingly, the patients displayed significant different clinical outcome with two displaying severe clinical picture of immunodeficiency and three had spontaneous recovery. Our data supports that the presented IL7RA mutation affects the IL-7 signaling and shaping of the TRG repertoire, reinforcing the role of IL7RA in the immune system, while non-genetic factors may exist that attribute to the ultimate clinical presentation and disease progression.

5.
J Clin Immunol ; 39(4): 401-413, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31037583

RESUMO

MALT1 (mucosa-associated lymphoid tissue lymphoma-translocation gene 1) is an intracellular signaling protein that activates NFκB and is crucial for both the adaptive and innate immune responses. Only 6 patients with immune deficiencies secondary to inherited mutations in the MALT1 gene have been described. PURPOSE: To provide clinical and immunological insights from 2 patients diagnosed with MALT1 immunodeficiency syndrome due to a novel MALT1 mutation. METHODS: Two cousins with suspected combined immunodeficiency underwent immunological and genetic work-up, including lymphocyte phenotyping, lymphocyte activation by mitogen stimulation, and next-generation sequencing (NGS) of T cell receptor gamma chain (TRG) repertoire. Whole exome sequencing was performed to identify the underlying genetic defect. RESULTS: Clinical findings included recurrent infections, failure to thrive, lymphadenopathy, dermatitis, and autoimmunity. Immune work-up revealed lymphocytosis, low to normal levels of immunoglobulins, absence of regulatory T cells, and low Th17 cells. A normal proliferative response was induced by phytohemagglutinin and IL-2 but was diminished with anti-CD3. TRG repertoire was diverse with a clonal expansion pattern. Genetic analysis identified a novel autosomal recessive homozygous c.1799T>A; p. I600N missense mutation in MALT1. MALT1 protein expression was markedly reduced, and in vitro IL-2 production and NFκB signaling pathway were significantly impaired. CONCLUSIONS: Two patients harboring a novel MALT1 mutation presented with signs of immune deficiency and dysregulation and were found to have an abnormal T cell receptor repertoire. These findings reinforce the link between MALT1 deficiency and combined immunodeficiency. Early diagnosis is crucial, and curative treatment by hematopoietic stem cell transplantation may be warranted.

6.
Blood ; 132(22): 2362-2374, 2018 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-30254128

RESUMO

ARPC1B is a key factor for the assembly and maintenance of the ARP2/3 complex that is involved in actin branching from an existing filament. Germline biallelic mutations in ARPC1B have been recently described in 6 patients with clinical features of combined immunodeficiency (CID), whose neutrophils and platelets but not T lymphocytes were studied. We hypothesized that ARPC1B deficiency may also lead to cytoskeleton and functional defects in T cells. We have identified biallelic mutations in ARPC1B in 6 unrelated patients with early onset disease characterized by severe infections, autoimmune manifestations, and thrombocytopenia. Immunological features included T-cell lymphopenia, low numbers of naïve T cells, and hyper-immunoglobulin E. Alteration in ARPC1B protein structure led to absent/low expression by flow cytometry and confocal microscopy. This molecular defect was associated with the inability of patient-derived T cells to extend an actin-rich lamellipodia upon T-cell receptor (TCR) stimulation and to assemble an immunological synapse. ARPC1B-deficient T cells additionally displayed impaired TCR-mediated proliferation and SDF1-α-directed migration. Gene transfer of ARPC1B in patients' T cells using a lentiviral vector restored both ARPC1B expression and T-cell proliferation in vitro. In 2 of the patients, in vivo somatic reversion restored ARPC1B expression in a fraction of lymphocytes and was associated with a skewed TCR repertoire. In 1 revertant patient, memory CD8+ T cells expressing normal levels of ARPC1B displayed improved T-cell migration. Inherited ARPC1B deficiency therefore alters T-cell cytoskeletal dynamics and functions, contributing to the clinical features of CID.

7.
Artigo em Inglês | MEDLINE | ID: mdl-29772310

RESUMO

BACKGROUND: Mutations in recombination-activating gene (RAG) 1 and RAG2 are associated with a broad range of clinical and immunologic phenotypes in human subjects. OBJECTIVE: Using a flow cytometry-based assay, we aimed to measure the recombinase activity of naturally occurring RAG2 mutant proteins and to correlate our results with the severity of the clinical and immunologic phenotype. METHODS: Abelson virus-transformed Rag2-/- pro-B cells engineered to contain an inverted green fluorescent protein (GFP) cassette flanked by recombination signal sequences were transduced with retroviruses encoding either wild-type or 41 naturally occurring RAG2 variants. Bicistronic vectors were used to introduce compound heterozygous RAG2 variants. The percentage of GFP-expressing cells was evaluated by using flow cytometry, and high-throughput sequencing was used to analyze rearrangements at the endogenous immunoglobulin heavy chain (Igh) locus. RESULTS: The RAG2 variants showed a wide range of recombination activity. Mutations associated with severe combined immunodeficiency and Omenn syndrome had significantly lower activity than those detected in patients with less severe clinical presentations. Four variants (P253R, F386L, N474S, and M502V) previously thought to be pathogenic were found to have wild-type levels of activity. Use of bicistronic vectors permitted us to assess more carefully the effect of compound heterozygous mutations, with good correlation between GFP expression and the number and diversity of Igh rearrangements. CONCLUSIONS: Our data support genotype-phenotype correlation in the setting of RAG2 deficiency. The assay described can be used to define the possible disease-causing role of novel RAG2 variants and might help predict the severity of the clinical phenotype.

8.
J Immunol ; 199(12): 4036-4045, 2017 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-29127144

RESUMO

Regulation of the actin cytoskeleton is crucial for normal development and function of the immune system, as evidenced by the severe immune abnormalities exhibited by patients bearing inactivating mutations in the Wiskott-Aldrich syndrome protein (WASP), a key regulator of actin dynamics. WASP exerts its effects on actin dynamics through a multisubunit complex termed Arp2/3. Despite the critical role played by Arp2/3 as an effector of WASP-mediated control over actin polymerization, mutations in protein components of the Arp2/3 complex had not previously been identified as a cause of immunodeficiency. Here, we describe two brothers with hematopoietic and immunologic symptoms reminiscent of Wiskott-Aldrich syndrome (WAS). However, these patients lacked mutations in any of the genes previously associated with WAS. Whole-exome sequencing revealed a homozygous 2 bp deletion, n.c.G623DEL-TC (p.V208VfsX20), in Arp2/3 complex component ARPC1B that causes a frame shift resulting in premature termination. Modeling of the disease in zebrafish revealed that ARPC1B plays a critical role in supporting T cell and thrombocyte development. Moreover, the defects in development caused by ARPC1B loss could be rescued by the intact human ARPC1B ortholog, but not by the p.V208VfsX20 variant identified in the patients. Moreover, we found that the expression of ARPC1B is restricted to hematopoietic cells, potentially explaining why a mutation in ARPC1B has now been observed as a cause of WAS, whereas mutations in other, more widely expressed, components of the Arp2/3 complex have not been observed.


Assuntos
Complexo 2-3 de Proteínas Relacionadas à Actina/genética , Plaquetas/patologia , Mutação da Fase de Leitura , Síndromes de Imunodeficiência/genética , Linfopoese/genética , Linfócitos T/patologia , Trombopoese/genética , Citoesqueleto de Actina/metabolismo , Complexo 2-3 de Proteínas Relacionadas à Actina/deficiência , Complexo 2-3 de Proteínas Relacionadas à Actina/metabolismo , Complexo 2-3 de Proteínas Relacionadas à Actina/fisiologia , Pré-Escolar , Códon sem Sentido , Consanguinidade , Evolução Fatal , Humanos , Lactente , Masculino , Complexos Multiproteicos , Linhagem , Polimerização , Recombinação V(D)J , Síndrome de Wiskott-Aldrich/genética , Proteínas de Peixe-Zebra/deficiência , Proteínas de Peixe-Zebra/genética
12.
Blood ; 128(6): 783-93, 2016 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-27301863

RESUMO

Primary immunodeficiency diseases comprise a group of heterogeneous genetic defects that affect immune system development and/or function. Here we use in vitro differentiation of human induced pluripotent stem cells (iPSCs) generated from patients with different recombination-activating gene 1 (RAG1) mutations to assess T-cell development and T-cell receptor (TCR) V(D)J recombination. RAG1-mutants from severe combined immunodeficient (SCID) patient cells showed a failure to sustain progression beyond the CD3(--)CD4(-)CD8(-)CD7(+)CD5(+)CD38(-)CD31(-/lo)CD45RA(+) stage of T-cell development to reach the CD3(-/+)CD4(+)CD8(+)CD7(+)CD5(+)CD38(+)CD31(+)CD45RA(-) stage. Despite residual mutant RAG1 recombination activity from an Omenn syndrome (OS) patient, similar impaired T-cell differentiation was observed, due to increased single-strand DNA breaks that likely occur due to heterodimers consisting of both an N-terminal truncated and a catalytically dead RAG1. Furthermore, deep-sequencing analysis of TCR-ß (TRB) and TCR-α (TRA) rearrangements of CD3(-)CD4(+)CD8(-) immature single-positive and CD3(+)CD4(+)CD8(+) double-positive cells showed severe restriction of repertoire diversity with preferential usage of few Variable, Diversity, and Joining genes, and skewed length distribution of the TRB and TRA complementary determining region 3 sequences from SCID and OS iPSC-derived cells, whereas control iPSCs yielded T-cell progenitors with a broadly diversified repertoire. Finally, no TRA/δ excision circles (TRECs), a marker of TRA/δ locus rearrangements, were detected in SCID and OS-derived T-lineage cells, consistent with a pre-TCR block in T-cell development. This study compares human T-cell development of SCID vs OS patients, and elucidates important differences that help to explain the wide range of immunologic phenotypes that result from different mutations within the same gene of various patients.


Assuntos
Proteínas de Homeodomínio/genética , Células-Tronco Pluripotentes Induzidas/patologia , Imunodeficiência Combinada Severa/genética , Imunodeficiência Combinada Severa/patologia , Linfócitos T/patologia , Células Cultivadas , Quebras de DNA , Genes RAG-1 , Humanos , Lactente , Mutação , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Recombinação V(D)J
13.
J Clin Immunol ; 36(4): 341-53, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27063650

RESUMO

PURPOSE: DNA Ligase 4 (LIG4) is a key factor in the non-homologous end-joining (NHEJ) DNA double-strand break repair pathway needed for V(D)J recombination and the generation of the T cell receptor and immunoglobulin molecules. Defects in LIG4 result in a variable syndrome of growth retardation, pancytopenia, combined immunodeficiency, cellular radiosensitivity, and developmental delay. METHODS: We diagnosed a patient with LIG4 syndrome by radiosensitivity testing on peripheral blood cells, and established that two of her four healthy siblings carried the same compound heterozygous LIG4 mutations. An extensive analysis of the immune phenotype, cellular radiosensitivity, telomere length, and T and B cell antigen receptor repertoire was performed in all siblings. RESULTS: In the three genotypically affected individuals, variable severities of radiosensitivity, alterations of T and B cell counts with an increased percentage of memory cells, and hypogammaglobulinemia, were noticed. Analysis of T and B cell antigen receptor repertoires demonstrated increased usage of alternative microhomology-mediated end-joining (MHMEJ) repair, leading to diminished N nucleotide addition and shorter CDR3 length. However, overall repertoire diversity was preserved. CONCLUSIONS: We demonstrate that LIG4 syndrome presents with high clinical variability even within the same family, and that distinctive immunologic abnormalities may be observed also in yet asymptomatic individuals.


Assuntos
DNA Ligase Dependente de ATP/genética , Síndromes de Imunodeficiência , Adolescente , Adulto , Agamaglobulinemia/genética , Agamaglobulinemia/imunologia , Linhagem Celular , Células Cultivadas , Criança , Feminino , Fibroblastos/efeitos da radiação , Granulócitos/efeitos da radiação , Humanos , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/imunologia , Leucócitos Mononucleares/citologia , Contagem de Linfócitos , Subpopulações de Linfócitos/imunologia , Masculino , Mutação , Radiação Ionizante , Adulto Jovem
14.
Nat Rev Immunol ; 16(4): 234-46, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26996199

RESUMO

The recombination-activating gene 1 (RAG1) and RAG2 proteins initiate the V(D)J recombination process, which ultimately enables the generation of T cells and B cells with a diversified repertoire of antigen-specific receptors. Mutations of the RAG genes in humans are associated with a broad spectrum of clinical phenotypes, ranging from severe combined immunodeficiency to autoimmunity. Recently, novel insights into the phenotypic diversity of this disease have been provided by resolving the crystal structure of the RAG complex, by developing novel assays to test recombination activity of the mutant RAG proteins and by characterizing the molecular and cellular basis of immune dysregulation in patients with RAG deficiency.


Assuntos
Linfócitos B/imunologia , Proteínas de Ligação a DNA/genética , Proteínas de Homeodomínio/genética , Proteínas Nucleares/genética , Imunodeficiência Combinada Severa/genética , Linfócitos T/imunologia , Recombinação V(D)J/imunologia , Terapia Genética , Humanos , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/imunologia , Síndromes de Imunodeficiência/terapia , Mutação , Fenótipo , Imunodeficiência Combinada Severa/imunologia , Imunodeficiência Combinada Severa/terapia , Recombinação V(D)J/genética
15.
Oncotarget ; 7(11): 12962-74, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26887046

RESUMO

Mutations in the Recombination Activating Gene 1 (RAG1) can cause a wide variety of clinical and immunological phenotypes in humans, ranging from absence of T and B lymphocytes to occurrence of autoimmune manifestations associated with expansion of oligoclonal T cells and production of autoantibodies. Although the mechanisms underlying this phenotypic heterogeneity remain poorly understood, some genotype-phenotype correlations can be made. Currently, mouse models of Rag deficiency are restricted to RAG1-/- mice and to knock-in models carrying severe missense mutations. The Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9 system is a novel and powerful gene-editing strategy that permits targeted introduction of DNA double strand breaks with high efficiency through simultaneous delivery of the Cas9 endonuclease and a guide RNA (gRNA). Here, we report on CRISPR-based, single-step generation and characterization of mutant mouse models in which gene editing was attempted around residue 838 of RAG1, a region whose functional role had not been studied previously.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes/métodos , Proteínas de Homeodomínio/genética , Camundongos Mutantes/genética , Animais , Camundongos , Mutagênese Sítio-Dirigida/métodos , Zigoto
16.
Sci Immunol ; 1(6)2016 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-28783691

RESUMO

Recombination-activating genes 1 and 2 (RAG1 and RAG2) play a critical role in T and B cell development by initiating the recombination process that controls the expression of T cell receptor (TCR) and immunoglobulin genes. Mutations in the RAG1 and RAG2 genes in humans cause a broad spectrum of phenotypes, including severe combined immunodeficiency (SCID) with lack of T and B cells, Omenn syndrome, leaky SCID, and combined immunodeficiency with granulomas or autoimmunity (CID-G/AI). Using next-generation sequencing, we analyzed the TCR and B cell receptor (BCR) repertoire in 12 patients with RAG mutations presenting with Omenn syndrome (n = 5), leaky SCID (n = 3), or CID-G/AI (n = 4). Restriction of repertoire diversity skewed usage of variable (V), diversity (D), and joining (J) segment genes, and abnormalities of CDR3 length distribution were progressively more prominent in patients with a more severe phenotype. Skewed usage of V, D, and J segment genes was present also within unique sequences, indicating a primary restriction of repertoire. Patients with Omenn syndrome had a high proportion of class-switched immunoglobulin heavy chain transcripts and increased somatic hypermutation rate, suggesting in vivo activation of these B cells. These data provide a framework to better understand the phenotypic heterogeneity of RAG deficiency.

17.
J Clin Invest ; 125(11): 4135-48, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-26457731

RESUMO

Patients with mutations of the recombination-activating genes (RAG) present with diverse clinical phenotypes, including severe combined immune deficiency (SCID), autoimmunity, and inflammation. However, the incidence and extent of immune dysregulation in RAG-dependent immunodeficiency have not been studied in detail. Here, we have demonstrated that patients with hypomorphic RAG mutations, especially those with delayed-onset combined immune deficiency and granulomatous/autoimmune manifestations (CID-G/AI), produce a broad spectrum of autoantibodies. Neutralizing anti-IFN-α or anti-IFN-ω antibodies were present at detectable levels in patients with CID-G/AI who had a history of severe viral infections. As this autoantibody profile is not observed in a wide range of other primary immunodeficiencies, we hypothesized that recurrent or chronic viral infections may precipitate or aggravate immune dysregulation in RAG-deficient hosts. We repeatedly challenged Rag1S723C/S723C mice, which serve as a model of leaky SCID, with agonists of the virus-recognizing receptors TLR3/MDA5, TLR7/-8, and TLR9 and found that this treatment elicits autoantibody production. Altogether, our data demonstrate that immune dysregulation is an integral aspect of RAG-associated immunodeficiency and indicate that environmental triggers may modulate the phenotypic expression of autoimmune manifestations.


Assuntos
Autoanticorpos/imunologia , Autoantígenos/imunologia , Doenças Autoimunes/imunologia , Citocinas/imunologia , Proteínas de Ligação a DNA/deficiência , Doença Granulomatosa Crônica/imunologia , Proteínas de Homeodomínio/imunologia , Proteínas Nucleares/deficiência , Imunodeficiência Combinada Severa/imunologia , Adolescente , Adulto , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Especificidade de Anticorpos , Autoanticorpos/sangue , Doenças Autoimunes/genética , Criança , Pré-Escolar , RNA Helicases DEAD-box/imunologia , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Feminino , Doença Granulomatosa Crônica/genética , Doença Granulomatosa Crônica/terapia , Proteínas de Homeodomínio/genética , Humanos , Lactente , Helicase IFIH1 Induzida por Interferon , Masculino , Camundongos , Camundongos Endogâmicos , Proteínas Nucleares/genética , Imunodeficiência Combinada Severa/genética , Imunodeficiência Combinada Severa/terapia , Receptores Toll-Like/agonistas , Receptores Toll-Like/imunologia , Viroses/imunologia , Adulto Jovem
18.
J Clin Immunol ; 35(8): 754-60, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26515615

RESUMO

PURPOSE: Hypomorphic mutations in RAG1 and RAG2 are associated with significant clinical heterogeneity and symptoms of immunodeficiency or autoimmunity may be late in appearance. As a result, immunosuppressive medications may be introduced that can have life-threatening consequences. We describe a previously healthy 13-month-old girl presenting with rash and autoimmune hemolytic anemia, while highlighting the importance of vigilance and consideration of an underlying severe immunodeficiency disease prior to instituting immunosuppressive therapy. METHODS: Given clinical deterioration of the patient and a temporal association with recently administered vaccinations, virus genotyping was carried out via 4 real-time Forster Resonance Energy Transfer PCR protocols targeting vaccine-associated single nucleotide polymorphisms. Genomic DNA was extracted from whole blood and analyzed via the next-generation sequencing method of sequencing-by-synthesis. Immune function studies included immunophenotyping of peripheral blood lymphocytes, mitogen-induced proliferation and TLR ligand-induced production of TNFα. Analysis of recombination activity of wild-type and mutant RAG2 constructs was performed. RESULTS: Virus genotyping revealed vaccine-strain VZV, mumps, and rubella. Next-generation sequencing identified heterozygosity for RAG2 R73H and P180H mutations. Profound lymphopenia was associated with intense corticosteroid therapy, with some recovery after steroid reduction. Residual, albeit low, RAG2 protein activity was demonstrated. CONCLUSIONS: Because of the association of RAG deficiency with late-onset presentation and autoimmunity, live virus vaccination and immunosuppressive therapies are often initiated and can result in negative consequences. Here, hypomorphic RAG2 mutations were linked to disseminated vaccine-strain virus infections following institution of corticosteroid therapy for autoimmune hemolytic anemia.


Assuntos
Anemia Hemolítica Autoimune/diagnóstico , Herpes Zoster/diagnóstico , Herpesvirus Humano 3/fisiologia , Síndromes de Imunodeficiência/diagnóstico , Vacinas Virais/imunologia , Adolescente , Corticosteroides/administração & dosagem , Corticosteroides/efeitos adversos , Anemia Hemolítica Autoimune/complicações , Anemia Hemolítica Autoimune/tratamento farmacológico , Células Cultivadas , Proteínas de Ligação a DNA/genética , Feminino , Herpes Zoster/complicações , Herpes Zoster/tratamento farmacológico , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Síndromes de Imunodeficiência/complicações , Síndromes de Imunodeficiência/tratamento farmacológico , Imunossupressão , Ativação Linfocitária/efeitos dos fármacos , Proteínas Nucleares/genética , Linhagem
19.
J Allergy Clin Immunol ; 136(1): 140-150.e7, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25917813

RESUMO

BACKGROUND: The endonuclease ARTEMIS, which is encoded by the DCLRE1C gene, is a component of the nonhomologous end-joining pathway and participates in hairpin opening during the V(D)J recombination process and repair of a subset of DNA double-strand breaks. Patients with ARTEMIS deficiency usually present with severe combined immunodeficiency (SCID) and cellular radiosensitivity, but hypomorphic mutations can cause milder phenotypes (leaky SCID). OBJECTIVE: We sought to correlate the functional effect of human DCLRE1C mutations on phenotypic presentation in patients with ARTEMIS deficiency. METHODS: We studied the recombination and DNA repair activity of 41 human DCLRE1C mutations in Dclre1c(-/-) v-abl kinase-transformed pro-B cells retrovirally engineered with a construct that allows quantification of recombination activity by means of flow cytometry. For assessment of DNA repair efficacy, resolution of γH2AX accumulation was studied after ionizing radiation. RESULTS: Low or absent activity was detected for mutations causing a typical SCID phenotype. Most of the patients with leaky SCID were compound heterozygous for 1 loss-of-function and 1 hypomorphic allele, with significant residual levels of recombination and DNA repair activity. Deletions disrupting the C-terminus result in truncated but partially functional proteins and are often associated with leaky SCID. Overexpression of hypomorphic mutants might improve the functional defect. CONCLUSIONS: Correlation between the nature and location of DCLRE1C mutations, functional activity, and the clinical phenotype has been observed. Hypomorphic variants that have been reported in the general population can be disease causing if combined in trans with a loss-of-function allele. Therapeutic strategies aimed at inducing overexpression of hypomorphic alleles might be beneficial.


Assuntos
Linfócitos B/fisiologia , Mutação/genética , Proteínas Nucleares/genética , Imunodeficiência Combinada Severa/genética , Adolescente , Adulto , Alelos , Linfócitos B/efeitos da radiação , Linhagem Celular Transformada , Criança , Pré-Escolar , Análise Mutacional de DNA , Reparo do DNA/genética , Endonucleases , Heterozigoto , Histonas/metabolismo , Humanos , Lactente , Recém-Nascido , Masculino , Proteínas Oncogênicas v-abl/genética , Proteínas Oncogênicas v-abl/metabolismo , Fenótipo , Tolerância a Radiação/genética , Radiação Ionizante , Recombinação V(D)J/genética , Adulto Jovem
20.
Sci Transl Med ; 7(276): 276ra25, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25717098

RESUMO

Insights into the ontogeny of the human fetal adaptive immune system are of great value for understanding immunocompetence of the developing fetus. However, to date, this has remained largely uncharted territory, in large part because blood samples from healthy, early gestation fetuses have been hard to come by. In a comprehensive study, we analyzed levels of T cell receptor excision circles (TRECs), signal-joint κ receptor excision circles (sjKRECs), and intron recombination signal sequence-K-deleting element (iRSS-Kde) rearrangement, and T and B lymphocyte repertoire clonality in human fetuses from 12 to 26 weeks of gestational age. Using next-generation sequencing, we analyzed the diversity and complexity of T cell receptor ß (TRB) and immunoglobulin heavy chain (IGH) repertoires in four fetuses at 12, 13, 22, and 26 weeks of gestation and in healthy full-term infants. We report the progressive increase of TREC, sjKREC, and iRSS-Kde levels over time and confirm that B cell development precedes T cell development in the human fetus. Temporally and spatially regulated maturation of B and T cell repertoire diversity and complexity during human fetal development was observed, including evidence that immunoglobulin somatic hypermutation and class switch recombination occur already during intrauterine life. Our results help define physiological levels of immunodeficiency in premature infants and may serve as a reference for future studies aimed at investigating the impact of intrauterine pathologies on fetal immune development and function.


Assuntos
Linfócitos B/metabolismo , Desenvolvimento Fetal/imunologia , Linfócitos T/metabolismo , Anticorpos/sangue , Anticorpos/imunologia , Antígenos/metabolismo , Regiões Determinantes de Complementaridade/imunologia , Feminino , Sangue Fetal/metabolismo , Humanos , Switching de Imunoglobulina , Cadeias Pesadas de Imunoglobulinas/química , Lactente , Gravidez , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Hipermutação Somática de Imunoglobulina , Fatores de Tempo
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