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2.
Nat Commun ; 10(1): 3106, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31308374

RESUMO

Immune responses need to be controlled tightly to prevent autoimmune diseases, yet underlying molecular mechanisms remain partially understood. Here, we identify biallelic mutations in three patients from two unrelated families in differentially expressed in FDCP6 homolog (DEF6) as the molecular cause of an inborn error of immunity with systemic autoimmunity. Patient T cells exhibit impaired regulation of CTLA-4 surface trafficking associated with reduced functional CTLA-4 availability, which is replicated in DEF6-knockout Jurkat cells. Mechanistically, we identify the small GTPase RAB11 as an interactor of the guanine nucleotide exchange factor DEF6, and find disrupted binding of mutant DEF6 to RAB11 as well as reduced RAB11+CTLA-4+ vesicles in DEF6-mutated cells. One of the patients has been treated with CTLA-4-Ig and achieved sustained remission. Collectively, we uncover DEF6 as player in immune homeostasis ensuring availability of the checkpoint protein CTLA-4 at T-cell surface, identifying a potential target for autoimmune and/or cancer therapy.

3.
Front Immunol ; 9: 588, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29651288

RESUMO

Specific granule deficiency (SGD) is a rare disorder characterized by abnormal neutrophils evidenced by reduced granules, absence of granule proteins, and atypical bilobed nuclei. Mutations in CCAAT/enhancer-binding protein-ε (CEBPE) are one molecular etiology of the disease. Although C/EBPε has been studied extensively, the impact of CEBPE mutations on neutrophil biology remains elusive. Here, we identified two SGD patients bearing a previously described heterozygous mutation (p.Val218Ala) in CEBPE. We took this rare opportunity to characterize SGD neutrophils in terms of granule distribution and protein content. Granules of patient neutrophils were clustered and polarized, suggesting that not only absence of specific granules but also defects affecting other granules contribute to the phenotype. Our analysis showed that remaining granules displayed mixed protein content and lacked several glycoepitopes. To further elucidate the impact of mutant CEBPE, we performed detailed proteomic analysis of SGD neutrophils. Beside an absence of several granule proteins in patient cells, we observed increased expression of members of the linker of nucleoskeleton and cytoskeleton complex (nesprin-2, vimentin, and lamin-B2), which control nuclear shape. This suggests that absence of these proteins in healthy individuals might be responsible for segmented shapes of neutrophilic nuclei. We further show that the heterozygous mutation p.Val218Ala in CEBPE causes SGD through prevention of nuclear localization of the protein product. In conclusion, we uncover that absence of nuclear C/EBPε impacts on spatiotemporal expression and subsequent distribution of several granule proteins and further on expression of proteins controlling nuclear shape.

4.
J Clin Immunol ; 38(3): 273-277, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29564582

RESUMO

PURPOSE: Adenosine deaminase 2 (ADA2) have been reported to cause vasculitic diseases and immunodeficiency recently. Patients present with stroke episodes and rashes mimicking polyarteritis nodosa (PAN). We report a patient who has been followed up with severe neutropenia and found an unexpectedly revealed novel mutation in CECR1 affecting ADA2. METHODS: We reviewed medical records and clinical history of the patient. No mutations in other known neutropenia genes such as ELA, G6PC3, HAX1, AP3B1, LAMTOR2, VPS13B, VPS45, GFI1, JAGN1, or WAS could be detected. Sanger sequencing was used to confirm the genetic variants in the patient and relatives. RESULTS: Genetic analysis by exome sequencing revealed a novel mutation in the gene CECR1 (c.G962A; p.G321E) which segregated perfectly in the relatives. CONCLUSION: This is the first DADA2 patient presenting with severe neutropenia. We suggest that in patients with unexplained cytopenias combined with immunodeficiency, fevers of unknown origin and high inflammation markers, DADA2 should be considered.

5.
J Clin Immunol ; 37(8): 790-800, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28956255

RESUMO

INTRODUCTION: LPS-responsive beige-like anchor protein (LRBA) deficiency is a primary immunodeficiency categorized as common variable immunodeficiency associated with autoimmune manifestations and inflammatory bowel diseases; however, the clinical spectrum has been extended. Here, we present our cohort of Turkish LRBA-deficient patients from a single center, demonstrating a diversity of clinical manifestations. METHOD: Seven affected individuals from five families were assessed retrospectively in this study. RESULTS: Of the seven patients with LRBA deficiency, four had homozygous, and two had compound heterozygous mutations. One patient remained disease free until the last follow-up (age 17 years). The most common clinical manifestations of the six symptomatic patients were organomegaly (6/6), autoimmunity (6/6), and chronic diarrhea (5/6). Recurrent infectious episodes were observed in three patients. None of the patients had hypogammaglobulinemia at presentation. B cell subpopulation analysis revealed low numbers of switched-memory B cell numbers in two of the four tested patients. During the disease course, three of the patients died, two of them underwent successful hematopoietic stem cell transplantation (HSCT) from matched sibling donors, and one is under abatacept therapy. CONCLUSION: LRBA defects should always be kept in mind as a differential diagnosis for patients with autoimmune disease affecting multiple organs, chronic diarrhea, and organomegalies. In our experience, early HSCT is a life-saving therapeutic strategy.


Assuntos
Abatacepte/uso terapêutico , Proteínas Adaptadoras de Transdução de Sinal/genética , Doenças Autoimunes/genética , Imunodeficiência de Variável Comum/genética , Imunossupressores/uso terapêutico , Doenças Inflamatórias Intestinais/genética , Mutação/genética , Adolescente , Doenças Autoimunes/diagnóstico , Doenças Autoimunes/tratamento farmacológico , Criança , Imunodeficiência de Variável Comum/diagnóstico , Imunodeficiência de Variável Comum/tratamento farmacológico , Intervalo Livre de Doença , Evolução Fatal , Feminino , Homozigoto , Humanos , Lactente , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/tratamento farmacológico , Masculino , Sepse , Turquia
6.
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
7.
N Engl J Med ; 372(25): 2409-22, 2015 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-26083206

RESUMO

Background Combined immunodeficiencies are marked by inborn errors of T-cell immunity in which the T cells that are present are quantitatively or functionally deficient. Impaired humoral immunity is also common. Patients have severe infections, autoimmunity, or both. The specific molecular, cellular, and clinical features of many types of combined immunodeficiencies remain unknown. Methods We performed genetic and cellular immunologic studies involving five unrelated children with early-onset invasive bacterial and viral infections, lymphopenia, and defective T-cell, B-cell, and natural killer (NK)-cell responses. Two patients died early in childhood; after allogeneic hematopoietic stem-cell transplantation, the other three had normalization of T-cell function and clinical improvement. Results We identified biallelic mutations in the dedicator of cytokinesis 2 gene (DOCK2) in these five patients. RAC1 activation was impaired in the T cells. Chemokine-induced migration and actin polymerization were defective in the T cells, B cells, and NK cells. NK-cell degranulation was also affected. Interferon-α and interferon-λ production by peripheral-blood mononuclear cells was diminished after viral infection. Moreover, in DOCK2-deficient fibroblasts, viral replication was increased and virus-induced cell death was enhanced; these conditions were normalized by treatment with interferon alfa-2b or after expression of wild-type DOCK2. Conclusions Autosomal recessive DOCK2 deficiency is a new mendelian disorder with pleiotropic defects of hematopoietic and nonhematopoietic immunity. Children with clinical features of combined immunodeficiencies, especially with early-onset, invasive infections, may have this condition. (Supported by the National Institutes of Health and others.).


Assuntos
Doenças Genéticas Inatas/genética , Fatores de Troca do Nucleotídeo Guanina/genética , Síndromes de Imunodeficiência/genética , Mutação , Linfócitos T/imunologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Pré-Escolar , Evolução Fatal , Feminino , Genes Recessivos , Doenças Genéticas Inatas/terapia , Fatores de Troca do Nucleotídeo Guanina/deficiência , Transplante de Células-Tronco Hematopoéticas , Humanos , Síndromes de Imunodeficiência/terapia , Lactente , Células Matadoras Naturais/imunologia , Masculino , Linhagem , Linfócitos T/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo
8.
J Pediatr Gastroenterol Nutr ; 60(3): 332-8, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25373860

RESUMO

OBJECTIVES: In the present study, we studied a cohort of patients with very early onset inflammatory bowel disease (IBD) to determine the frequency of mutations in the interleukin 10 (IL10) receptor genes as a cause of early-onset IBD. METHODS: Sanger sequencing was performed to determine the presence of IL10 and/or IL10 receptor mutations in 17 patients with a diagnosis of very early onset IBD (disease onset <2 years of age in 15 patients, between 3 and 4 years in the other 2). Mutation screening was performed including all of the coding regions of the IL10, IL10RA, and IL10RB genes. We then compared the follow-up findings of the patients with IL10 receptor mutations in terms of demographic, clinical, laboratory, and treatment response properties with those of patients diagnosed as having very early onset IBD with no mutation. RESULTS: We identified 3 patients bearing mutations in the IL10 or IL10 receptor genes, including 1 mutation in IL10RB that has been described recently (c.G477A, p.Trp159*) and 2 novel mutations affecting the IL10RA gene (c.T192G, p.Tyr64 and c.T133G, p.Trp45Gly). Collectively, these mutations thus provided genetic etiology for 17.6% of the cohort under investigation. The presence of a family history of IBD and the clinical course of Crohn disease differed between patients with mutations in the IL-10 pathway and those without such mutations. Although perianal fistulas were found in all of the patients with IL10 receptor mutations, they were found in only 14.3% of those without such mutations. The lower values of weight-for-age and height-for-age z scores, necessity for more intensive therapy, achievement of longer periods until remission, and frequent relapses in the patients bearing mutations in the IL10 receptor genes all underlined the severity of the disease and its relatively poor response to treatment. CONCLUSIONS: In spite of the small number of patients with mutations affecting the IL-10 signaling pathway in our study, in all of the patients with IL10 receptor mutations, the disease onset occurs at an early age, the prognosis is poor, and the response to treatment is insufficient.


Assuntos
Predisposição Genética para Doença , Doenças Inflamatórias Intestinais/genética , Subunidade alfa de Receptor de Interleucina-10/genética , Subunidade beta de Receptor de Interleucina-10/genética , Mutação , Fístula Retal/etiologia , Substituição de Aminoácidos , Pré-Escolar , Estudos de Coortes , Terapia Combinada , Doença de Crohn/diagnóstico , Doença de Crohn/genética , Doença de Crohn/fisiopatologia , Doença de Crohn/terapia , Éxons , Feminino , Seguimentos , Estudos de Associação Genética , Humanos , Lactente , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/fisiopatologia , Doenças Inflamatórias Intestinais/terapia , Interleucina-10/genética , Interleucina-10/metabolismo , Subunidade alfa de Receptor de Interleucina-10/metabolismo , Subunidade beta de Receptor de Interleucina-10/metabolismo , Masculino , Polimorfismo de Nucleotídeo Único , Prognóstico , Índice de Gravidade de Doença
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