RESUMEN
The adaptors DOCK8 and MyD88 have been linked to serological memory. Here we report that DOCK8-deficient patients had impaired antibody responses and considerably fewer CD27(+) memory B cells. B cell proliferation and immunoglobulin production driven by Toll-like receptor 9 (TLR9) were considerably lower in DOCK8-deficient B cells, but those driven by the costimulatory molecule CD40 were not. In contrast, TLR9-driven expression of AICDA (which encodes the cytidine deaminase AID), the immunoglobulin receptor CD23 and the costimulatory molecule CD86 and activation of the transcription factor NF-κB, the kinase p38 and the GTPase Rac1 were intact. DOCK8 associated constitutively with MyD88 and the tyrosine kinase Pyk2 in normal B cells. After ligation of TLR9, DOCK8 became tyrosine-phosphorylated by Pyk2, bound the Src-family kinase Lyn and linked TLR9 to a Src-kinase Syk-transcription factor STAT3 cascade essential for TLR9-driven B cell proliferation and differentiation. Thus, DOCK8 functions as an adaptor in a TLR9-MyD88 signaling pathway in B cells.
Asunto(s)
Linfocitos B/inmunología , Factores de Intercambio de Guanina Nucleótido/inmunología , Memoria Inmunológica/inmunología , Factor 88 de Diferenciación Mieloide/inmunología , Receptor Toll-Like 9/inmunología , Adolescente , Animales , Diferenciación Celular/inmunología , Niño , Preescolar , Citometría de Flujo , Quinasa 2 de Adhesión Focal/inmunología , Humanos , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Neutrófilos/inmunología , Fosforilación , Factor de Transcripción STAT3/inmunología , Familia-src Quinasas/inmunologíaRESUMEN
BACKGROUND: Inborn errors of immunity are mostly monogenic. However, disease phenotype and outcome may be modified by the coexistence of a second gene defect. OBJECTIVE: We sought to identify the genetic basis of the disease in a patient who experienced bleeding episodes, pancytopenia, hepatosplenomegaly, and recurrent pneumonia that resulted in death. METHODS: Genetic analysis was done using next-generation sequencing. Protein expression and phosphorylation were determined by immunoblotting. T-cell proliferation and F-actin levels were studied by flow cytometry. RESULTS: The patient harbored 2 homozygous deletions in STX11 (c.369_370del, c.374_376del; p.V124fs60∗) previously associated with familial hemophagocytic lymphohistiocytosis and a novel homozygous missense variant in SLP76 (c.767C>T; p.T256I) that resulted in an approximately 85% decrease in SLP76 levels and absent T-cell proliferation. The patient's heterozygous family members showed an approximately 50% decrease in SLP76 levels but normal immune function. SLP76-deficient J14 Jurkat cells did not express SLP76 and had decreased extracellular signal-regulated kinase signaling, basal F-actin levels, and polymerization following T-cell receptor stimulation. Reconstitution of J14 cells with T256I mutant SLP76 resulted in low protein expression and abnormal extracellular signal-regulated kinase phosphorylation and F-actin polymerization after T-cell receptor activation compared with normal expression and J14 function when wild-type SLP76 was introduced. CONCLUSIONS: The hypomorphic mutation in SLP76 tones down the hyperinflammation due to STX11 deletion, resulting in a combined immunodeficiency that overshadows the hemophagocytic lymphohistiocytosis phenotype. To our knowledge, this study represents the first report of the opposing effects of 2 gene defects on the disease in a patient with an inborn error of immunity.
Asunto(s)
Actinas , Linfohistiocitosis Hemofagocítica , Humanos , Quinasas MAP Reguladas por Señal Extracelular , Linfohistiocitosis Hemofagocítica/genética , Mutación , Proteínas Qa-SNARE/genética , Receptores de Antígenos de Linfocitos T/genética , Transducción de SeñalRESUMEN
BACKGROUND: Inborn errors of immunity have been implicated in causing immune dysregulation, including allergic diseases. STAT6 is a key regulator of allergic responses. OBJECTIVES: This study sought to characterize a novel gain-of-function STAT6 mutation identified in a child with severe allergic manifestations. METHODS: Whole-exome and targeted gene sequencing, lymphocyte characterization, and molecular and functional analyses of mutated STAT6 were performed. RESULTS: This study reports a child with a missense mutation in the DNA binding domain of STAT6 (c.1114G>A, p.E372K) who presented with severe atopic dermatitis, eosinophilia, and elevated IgE. Naive lymphocytes from the affected patient displayed increased TH2- and suppressed TH1- and TH17-cell responses. The mutation augmented both basal and cytokine-induced STAT6 phosphorylation without affecting dephosphorylation kinetics. Treatment with the Janus kinase 1/2 inhibitor ruxolitinib reversed STAT6 hyperresponsiveness to IL-4, normalized TH1 and TH17 cells, suppressed the eosinophilia, and improved the patient's atopic dermatitis. CONCLUSIONS: This study identified a novel inborn error of immunity due to a STAT6 gain-of-function mutation that gave rise to severe allergic dysregulation. Janus kinase inhibitor therapy could represent an effective targeted treatment for this disorder.
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Dermatitis Atópica , Eosinofilia , Hipersensibilidad , Niño , Humanos , Factores de Transcripción/genética , Mutación con Ganancia de Función , Dermatitis Atópica/genética , Hipersensibilidad/genética , Eosinofilia/genética , Factor de Transcripción STAT6/genética , Factor de Transcripción STAT6/metabolismo , Células Th2RESUMEN
BACKGROUND: RASGRP1-deficiency results in an immune dysregulation and immunodeficiency that manifest as autoimmunity, lymphoproliferation, lymphopenia, defective T cell function, and increased incidence of Epstein-Bar Virus infections and lymphomas. OBJECTIVE: To investigate the mechanism of autoimmune hemolytic anemia and infections in a male patient of consanguineous parents from Lebanon. METHODS: Genetic diagnosis was obtained using next generation and Sanger sequencing. Protein expression and phosphorylation were determined by immunoblotting. T and B cell development and function were studied by flow cytometry. Cytokine and immunoglobulin secretions were quantified by enzyme-linked immunosorbent assay. RESULTS: The patient suffered from severe lymphopenia especially affecting the T cell compartment. Genetic analysis revealed a homozygous insertion of adenine at position 1396_1397 in RASGRP1 that abolished protein expression and downstream Ras signaling. T cells from the patient showed severe activation defects resulting in uncontrolled Epstein-Bar Virus-induced B cell proliferation. B cells from the patient were normal. CONCLUSION: This report expands the spectrum of mutations in patients with RasGRP1 deficiency, and provides evidence for the important role RasGRP1 plays in the ability of T cells to control Epstein-Bar Virus-induced B cell proliferation. CLINICAL IMPLICATIONS: Following diagnosis, the patient will be maintained on oral valganciclovir and monitored regularly for Epstein-Bar Virus infections to avoid the development of Epstein-Bar Virus- induced B cell lymphoma. He is also candidate for hematopoietic stem cell transplantation.
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Infecciones por Virus de Epstein-Barr , Síndromes de Inmunodeficiencia , Linfopenia , Humanos , Masculino , Proliferación Celular/genética , Proteínas de Unión al ADN/genética , Infecciones por Virus de Epstein-Barr/complicaciones , Infecciones por Virus de Epstein-Barr/genética , Factores de Intercambio de Guanina Nucleótido/genética , Factores de Intercambio de Guanina Nucleótido/metabolismo , Herpesvirus Humano 4 , Síndromes de Inmunodeficiencia/complicaciones , Síndromes de Inmunodeficiencia/genética , Linfopenia/complicaciones , Linfopenia/genética , MutaciónRESUMEN
Glioblastoma is the most common and aggressive primary malignant brain tumour. The prognosis of patients with glioblastoma is poor, and their overall survival averages at 1 year, despite advances made in cancer therapy. The emergence of immunotherapy, a strategy that targets the natural mechanisms of immune evasion by cancerous cells, has revolutionised the treatment of melanoma, lung cancer and other solid tumours; however, immunotherapy failed to improve the prognosis of patients with glioblastoma. This is attributed to the fact that glioblastoma is endowed with numerous mechanisms of resistance that include the intrinsic resistance, which refers to the location of the tumour within the brain and the nature of the blood-brain barrier, as well as the adaptive and acquired resistance that result from the tumour heterogeneity and its immunosuppressive microenvironment. Glioblastoma is notorious for its inter and intratumoral heterogeneity, which, coupled with its spatial and temporal evolution, limits its immunogenicity. In addition, the tumour microenvironment is enriched with immunosuppressive cells and molecules that hinder the reactivity of cytotoxic immune cells and the success of immunotherapies. In this article, we review the mechanisms of resistance of glioblastoma to immunotherapy and discuss treatment strategies to overcome them worthy of further exploration.
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Neoplasias Encefálicas , Glioblastoma , Neoplasias Encefálicas/terapia , Glioblastoma/terapia , Humanos , Factores Inmunológicos , Inmunoterapia , Microambiente TumoralRESUMEN
BACKGROUND: The gene AK2 encodes the phosphotransferase adenylate kinase 2 (AK2). Human variants in AK2 cause reticular dysgenesis, a severe combined immunodeficiency with agranulocytosis, lymphopenia, and sensorineural deafness that requires hematopoietic stem cell transplantation for survival. OBJECTIVE: We investigated the mechanisms underlying recurrent sinopulmonary infections and hypogammaglobulinemia in 15 patients, ranging from 3 to 34 years of age, from 9 kindreds. Only 2 patients, both of whom had mildly impaired T-cell proliferation, each had a single clinically significant opportunistic infection. METHODS: Patient cells were studied with next-generation DNA sequencing, tandem mass spectrometry, and assays of lymphocyte and mitochondrial function. RESULTS: We identified 2 different homozygous variants in AK2. AK2G100S and AK2A182D permit residual protein expression, enzymatic activity, and normal numbers of neutrophils and lymphocytes. All but 1 patient had intact hearing. The patients' B cells had severely impaired proliferation and in vitro immunoglobulin secretion. With activation, the patients' B cells exhibited defective mitochondrial respiration and impaired regulation of mitochondrial membrane potential and quality. Although activated T cells from the patients with opportunistic infections demonstrated impaired mitochondrial function, the mitochondrial quality in T cells was preserved. Consistent with the capacity of activated T cells to utilize nonmitochondrial metabolism, these findings revealed a less strict cellular dependence of T-cell function on AK2 activity. Chemical inhibition of ATP synthesis in control T and B cells similarly demonstrated the greater dependency of B cells on mitochondrial function. CONCLUSIONS: Our patients demonstrate the in vivo sequelae of the cell-specific requirements for the functions of AK2 and mitochondria, particularly in B-cell activation and antibody production.
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Adenilato Quinasa/genética , Linfocitos B/inmunología , Homocigoto , Activación de Linfocitos/genética , Mutación Missense , Inmunodeficiencia Combinada Grave/genética , Adenilato Quinasa/inmunología , Adulto , Sustitución de Aminoácidos , Niño , Preescolar , Femenino , Humanos , Masculino , Inmunodeficiencia Combinada Grave/inmunología , Linfocitos T/inmunologíaRESUMEN
BACKGROUND: Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency disorder (PID) characterized by microthrombocytopenia, bloody diarrhea, eczema, recurrent infections, and a high incidence of autoimmunity and malignancy. OBJECTIVE: To investigate the mechanism of thrombocytopenia and infections in four boys of consanguineous parents from Lebanon. METHODS: Patient gDNA was studied using Next Generation Sequencing and Sanger Sequencing. Protein expression was determined by immunoblotting, and mRNA expression by semi-quantitative RT-PCR. F-actin polymerization and cellular proliferation were assayed by flow cytometry. RESULTS: We identified a threonine to a methionine change at position 45 (T45M) of the WAS protein (WASp) that abolished protein expression and disturbed F-actin polymerization and T cell proliferation, but not B cell proliferation. In addition, the levels of the WAS-interacting protein (WIP) were significantly decreased in the patients. CONCLUSION: The mutation identified severely destabilizes WASp and affects the downstream signaling events important for T cell function, but not B cell function. It was previously known that the stability of WASp depends on WIP. In this manuscript, we report that the stability of WIP also depends on WASp. Finally, it is important to suspect X-linked PIDs even in consanguineous families. CLINICAL IMPLICATIONS: The patients are above the optimal age for transplant in WAS, and it is difficult to identify one or more donors for four patients, therefore, they represent ideal candidates for gene therapy or interleukin-2 therapy.
Asunto(s)
Proteína del Síndrome de Wiskott-Aldrich/genética , Síndrome de Wiskott-Aldrich/genética , Enfermedades por Inmunodeficiencia Combinada Ligada al Cromosoma X/genética , Linfocitos B/inmunología , Niño , Preescolar , Consanguinidad , Humanos , Líbano , Masculino , Mutación , Hermanos , Linfocitos T/inmunología , Síndrome de Wiskott-Aldrich/inmunología , Enfermedades por Inmunodeficiencia Combinada Ligada al Cromosoma X/inmunologíaRESUMEN
BACKGROUND: Autosomal dominant anhidrotic ectodermal dysplasia with immune deficiency (AD EDA-ID) is caused by heterozygous point mutations at or close to serine 32 and serine 36 or N-terminal truncations in IκBα that impair its phosphorylation and degradation and thus activation of the canonical nuclear factor κ light chain enhancer of activated B cells (NF-κB) pathway. The outcome of hematopoietic stem cell transplantation is poor in patients with AD EDA-ID despite achievement of chimerism. Mice heterozygous for the serine 32I mutation in IκBα have impaired noncanonical NF-κB activity and defective lymphorganogenesis. OBJECTIVE: We sought to establish genotype-phenotype correlation in patients with AD EDA-ID. METHODS: A disease severity scoring system was devised. Stability of IκBα mutants was examined in transfected cells. Immunologic, biochemical, and gene expression analyses were performed to evaluate canonical and noncanonical NF-κB signaling in skin-derived fibroblasts. RESULTS: Disease severity was greater in patients with IκBα point mutations than in those with truncation mutations. IκBα point mutants were expressed at significantly higher levels in transfectants compared with truncation mutants. Canonical NF-κB-dependent IL-6 secretion and upregulation of the NF-κB subunit 2/p100 and RELB proto-oncogene, NF-κB subunit (RelB) components of the noncanonical NF-κB pathway were diminished significantly more in patients with point mutations compared with those with truncations. Noncanonical NF-κB-driven generation of the transcriptionally active p100 cleavage product p52 and upregulation of CCL20, intercellular adhesion molecule 1 (ICAM1), and vascular cell adhesion molecule 1 (VCAM1), which are important for lymphorganogenesis, were diminished significantly more in LPS plus α-lymphotoxin ß receptor-stimulated fibroblasts from patients with point mutations compared with those with truncations. CONCLUSIONS: IκBα point mutants accumulate at higher levels compared with truncation mutants and are associated with more severe disease and greater impairment of canonical and noncanonical NF-κB activity in patients with AD EDA-ID.
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Displasia Ectodérmica/genética , Displasia Ectodérmica/inmunología , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Enfermedades Genéticas Ligadas al Cromosoma X/inmunología , Genotipo , Síndromes de Inmunodeficiencia/genética , Síndromes de Inmunodeficiencia/inmunología , Transducción de Señal , Proteínas Portadoras/genética , Proteínas Portadoras/inmunología , Quimiocina CCL20/genética , Quimiocina CCL20/inmunología , Displasia Ectodérmica/patología , Enfermedades Genéticas Ligadas al Cromosoma X/patología , Células HEK293 , Humanos , Síndromes de Inmunodeficiencia/patología , Molécula 1 de Adhesión Intercelular/genética , Molécula 1 de Adhesión Intercelular/inmunología , Interleucina-6/genética , Interleucina-6/inmunología , Inhibidor NF-kappaB alfa/genética , Inhibidor NF-kappaB alfa/inmunología , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/inmunología , Mutación Puntual , Enfermedades de Inmunodeficiencia Primaria , Proto-Oncogenes Mas , Transducción de Señal/genética , Transducción de Señal/inmunologíaRESUMEN
Defects in DNA Recombination due to mutations in RAG1/2 or DCLRE1C result in combined immunodeficiency (CID) with a range of disease severity. We present the clinical, immunologic and molecular characteristics of 21 patients with defects in RAG1, RAG2 or DCLRE1C, who accounted for 24% of combined immune deficiency cases in the Kuwait National Primary Immunodeficiency Disorders Registry. The distribution of the patients was as follow: 8 with RAG1 deficiency, 6 with RAG2 deficiency and 7 with DCLRE1C deficiency. Nine patients presented with SCID, 6 with OS, 2 with leaky SCID and 4 with CID and granuloma and/or autoimmunity (CID-G/AI). Eight patients [(7 SCID and 1 OS) (38%)] received hematopoietic stem cell transplant (HSCT). The median age of HSCT was 11.5months and the median time from diagnosis to HSCT was 6months. Fifty percent of the transplanted patients are alive while only 23% of the untransplanted ones are alive.
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Enfermedades Autoinmunes/inmunología , Granuloma/inmunología , Inmunodeficiencia Combinada Grave/inmunología , Recombinación V(D)J/genética , Adolescente , Antibacterianos/uso terapéutico , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/terapia , Niño , Preescolar , Proteínas de Unión al ADN/genética , Endonucleasas/genética , Femenino , Perfil Genético , Granuloma/genética , Granuloma/terapia , Trasplante de Células Madre Hematopoyéticas , Proteínas de Homeodominio/genética , Humanos , Inmunoglobulinas Intravenosas/uso terapéutico , Síndromes de Inmunodeficiencia/genética , Síndromes de Inmunodeficiencia/inmunología , Síndromes de Inmunodeficiencia/terapia , Factores Inmunológicos/uso terapéutico , Lactante , Kuwait , Masculino , Proteínas Nucleares/genética , Inmunodeficiencia Combinada Grave/genética , Inmunodeficiencia Combinada Grave/terapiaRESUMEN
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.).
Asunto(s)
Enfermedades Genéticas Congénitas/genética , Factores de Intercambio de Guanina Nucleótido/genética , Síndromes de Inmunodeficiencia/genética , Mutación , Linfocitos T/inmunología , Linfocitos B/inmunología , Linfocitos B/metabolismo , Preescolar , Resultado Fatal , Femenino , Proteínas Activadoras de GTPasa , Genes Recesivos , Enfermedades Genéticas Congénitas/terapia , Factores de Intercambio de Guanina Nucleótido/deficiencia , Trasplante de Células Madre Hematopoyéticas , Humanos , Síndromes de Inmunodeficiencia/terapia , Lactante , Células Asesinas Naturales/inmunología , Masculino , Linaje , Linfocitos T/metabolismo , Proteína de Unión al GTP rac1/metabolismoRESUMEN
JAK3 is a tyrosine kinase essential for signaling downstream of the common gamma chain subunit shared by multiple cytokine receptors. JAK3 deficiency results in T-B+NK- severe combined immune deficiency (SCID). We report a patient with SCID due to a novel mutation in the JAK3 JH4 domain. The function of the JH4 domain remains unknown. This is the first report of a missense mutation in the JAK3 JH4 domain, thereby demonstrating the importance of the JH4 domain of JAK3 in host immunity.
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Janus Quinasa 3/metabolismo , Osteomielitis/genética , Inmunodeficiencia Combinada Grave/genética , Columna Vertebral/patología , Resultado Fatal , Femenino , Humanos , Lactante , Janus Quinasa 3/genética , Mutación , Osteomielitis/complicaciones , Dominios Proteicos , Inmunodeficiencia Combinada Grave/complicaciones , Inmunodeficiencia Combinada Grave/patologíaRESUMEN
PURPOSE: The dedicator of cytokinesis 8 (DOCK8) deficiency is an autosomal recessive-combined immunodeficiency whose clinical spectra include recurrent infections, autoimmunity, malignancies, elevated serum IgE, eczema, and food allergies. Here, we report on patients with loss of function DOCK8 mutations with profound immune dysregulation suggestive of an immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX)-like disorder. METHODS: Immunophenotyping of lymphocyte subpopulations and analysis of DOCK8 protein expression were evaluated by flow cytometry. T regulatory (Treg) cells were isolated by cell sorting, and their suppressive activity was analyzed by flow cytometry. Gene mutational analysis was performed by whole-exome and Sanger sequencing. RESULTS: Patient 1 (P1) presented at 10 months of age with chronic severe diarrhea and active colitis in the absence of an infectious trigger, severe eczema with elevated serum IgE, and autoimmune hemolytic anemia, suggestive of an IPEX-related disorder. Whole-exome sequencing revealed a homozygous nonsense mutation in DOCK8 at the DOCK-homology region (DHR)-1 (c.1498C>T; p. R500X). Patient P2, a cousin of P1 who carries the same DOCK8 nonsense mutation, presented with eczema and recurrent ear infections in early infancy, and she developed persistent diarrhea by 3 years of age. Patient P3 presented with lymphoproliferation, severe eczema with allergic dysregulation, and chronic diarrhea with colitis. She harbored a homozygous loss of function DOCK8 mutation (c.2402 -1GâA). Treg cell function was severely compromised by both DOCK8 mutations. CONCLUSION: DOCK8 deficiency may present severe immune dysregulation with features that may overlap with those of IPEX and other IPEX-like disorders.
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Trastornos de los Cromosomas/diagnóstico , Diabetes Mellitus Tipo 1/congénito , Diarrea/diagnóstico , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico , Factores de Intercambio de Guanina Nucleótido/genética , Hipersensibilidad/diagnóstico , Enfermedades del Sistema Inmune/congénito , Infecciones/diagnóstico , Mutación/genética , Linfocitos T Reguladores/inmunología , Anemia Hemolítica , Preescolar , Diabetes Mellitus Tipo 1/diagnóstico , Femenino , Genes Recesivos/genética , Humanos , Enfermedades del Sistema Inmune/diagnóstico , Inmunoglobulina E/metabolismo , Inmunofenotipificación , LactanteRESUMEN
The Rho GTPase Cdc42 coordinates regulation of the actin and the microtubule cytoskeleton by binding and activating the Wiskott-Aldrich syndrome protein. We sought to define the role of intrinsic expression of Cdc42 by mature B cells in their activation and function. Mice with inducible deletion of Cdc42 in mature B cells formed smaller germinal centers and had a reduced Ab response, mostly of low affinity to T cell-dependent Ag, compared with wild-type (WT) controls. Spreading formation of long protrusions that contain F-actin, microtubules, and Cdc42-interacting protein 4, and assumption of a dendritic cell morphology in response to anti-CD40 plus IL-4 were impaired in Cdc42-deficient B cells compared with WT B cells. Cdc42-deficient B cells had an intact migratory response to chemokine in vitro, but their homing to the B cell follicles in the spleen in vivo was significantly impaired. Cdc42-deficient B cells induced a skewed cytokine response in CD4(+) T cells, compared with WT B cells. Our results demonstrate a critical role for Cdc42 in the motility of mature B cells, their cognate interaction with T cells, and their differentiation into Ab-producing cells.
Asunto(s)
Linfocitos B/inmunología , Activación de Linfocitos/inmunología , Proteína de Unión al GTP cdc42/inmunología , Animales , Western Blotting , Diferenciación Celular/inmunología , Movimiento Celular/inmunología , Citometría de Flujo , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , Ratones MutantesRESUMEN
BACKGROUND: Coronin-1A (CORO1A) is a regulator of actin dynamics important for T-cell homeostasis. CORO1A deficiency causes T(-)B(+) natural killer-positive severe combined immunodeficiency or T-cell lymphopenia with severe viral infections. However, because all known human mutations in CORO1A abrogate protein expression, the role of the protein's functional domains in host immunity is unknown. OBJECTIVE: We sought to identify the cause of the primary immunodeficiency in 2 young adult siblings with a history of disseminated varicella, cutaneous warts, and CD4(+) T-cell lymphopenia. METHODS: We performed immunologic, genetic, and biochemical studies in the patients, family members, and healthy control subjects. RESULTS: Both patients had CD4(+) T-cell lymphopenia and decreased lymphocyte proliferation to mitogens. IgG, IgM, IgA, and specific antibody responses were normal. Whole-genome sequencing identified a homozygous frameshift mutation in CORO1A disrupting the last 2 C-terminal domains by replacing 61 amino acids with a novel 91-amino-acid sequence. The CORO1A(S401fs) mutant was expressed in the patients' lymphocytes at a level comparable with that of wild-type CORO1A in normal lymphocytes but did not oligomerize and had impaired cytoskeletal association. CORO1A(S401fs) was associated with increased filamentous actin accumulation in T cells, severely defective thymic output, and impaired T-cell survival but normal calcium flux and cytotoxicity, demonstrating the importance of CORO1A oligomerization and subcellular localization in T-cell homeostasis. CONCLUSIONS: We describe a truncating mutation in CORO1A that permits protein expression and survival into young adulthood. Our studies demonstrate the importance of intact CORO1A C-terminal domains in thymic egress and T-cell survival, as well as in defense against viral pathogens.
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Citoesqueleto/metabolismo , Homocigoto , Proteínas de Microfilamentos/genética , Mutación , Multimerización de Proteína , Virosis/etiología , Virosis/metabolismo , Actinas/química , Actinas/metabolismo , Adolescente , Animales , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Degranulación de la Célula/genética , Degranulación de la Célula/inmunología , Supervivencia Celular/genética , Análisis Mutacional de ADN , Femenino , Mutación del Sistema de Lectura , Humanos , Inmunoglobulinas/sangre , Inmunoglobulinas/inmunología , Recuento de Linfocitos , Linfopenia , Masculino , Ratones , Proteínas de Microfilamentos/química , Proteínas de Microfilamentos/metabolismo , Linaje , Fenotipo , Multimerización de Proteína/genética , Transporte de Proteínas , Hermanos , Transducción de Señal , Enfermedades de la Piel/patología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Virosis/diagnóstico , Verrugas/patologíaRESUMEN
BACKGROUND: Dedicator of cytokinesis 8 (DOCK8) deficiency can be cured by allogeneic hematopoietic stem cell transplantation (HSCT). Reports of outcomes are still limited. OBJECTIVE: We sought to analyze the results of HSCT in patients with DOCK8 deficiency and report whether approaches resulting in mixed chimerism result in clinically relevant immune reconstitution. METHODS: We performed a retrospective chart review of 11 patients with DOCK8 deficiency and measured DOCK8 expression and cytokine production. RESULTS: Of 11 patients, 7 received HSCT from related and 4 from unrelated donors; 9 patients received busulfan-based conditioning regimens. Survival was excellent (10 [91%] of 11 patients alive), including a patient who had undergone liver transplantation. Patients showed significant improvements in the frequency and severity of infections. Although eczema resolved in all, food allergies and high IgE levels persisted in some patients. Lymphopenia, eosinophilia, low numbers of naive CD8(+) T cells and switched memory B cells, and TH1/TH2 cytokine imbalance improved in most patients. Although the 8 matched related or unrelated donor recipients had full donor chimerism, all 3 recipients of mismatched unrelated donor HSCT had high levels of donor T-cell chimerism and low B-cell and myeloid cell chimerism (0% to 46%). Almost all switched memory B cells were of donor origin. All patients, including those with mixed chimerism, mounted robust antibody responses to vaccination. CONCLUSION: Allogeneic HSCT ameliorated the infectious and atopic symptoms of patients with DOCK8 deficiency. In patients with mixed chimerism, selective advantage for donor-derived T cells and switched memory B cells promoted restoration of cellular and humoral immunity and protection against opportunistic infection.
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Factores de Intercambio de Guanina Nucleótido/deficiencia , Trasplante de Células Madre Hematopoyéticas , Síndromes de Inmunodeficiencia/inmunología , Linfocitos B/inmunología , Niño , Preescolar , Citocinas/inmunología , Femenino , Humanos , Leucocitos Mononucleares/inmunología , Masculino , Linfocitos T/inmunología , Resultado del TratamientoRESUMEN
ORAI1 is the pore-forming subunit of the calcium release-activated calcium channel responsible for calcium influx into cells triggered by endoplasmic reticulum store depletion. We report here a patient with severe combined immunodeficiency and absent store-operated calcium entry due to a novel mutation in ORAI1 that results in the expression of a C-terminally truncated protein that abolishes ORAI1 binding to STIM1.
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Mutación , Proteínas de Neoplasias/genética , Proteína ORAI1/genética , Inmunodeficiencia Combinada Grave/genética , Molécula de Interacción Estromal 1/genética , Secuencia de Bases , Exoma/genética , Resultado Fatal , Femenino , Células HEK293 , Homocigoto , Humanos , Lactante , Proteínas de Neoplasias/metabolismo , Proteína ORAI1/metabolismo , Unión Proteica/genética , Análisis de Secuencia de ADN , Eliminación de Secuencia , Inmunodeficiencia Combinada Grave/metabolismo , Molécula de Interacción Estromal 1/metabolismoRESUMEN
Whole exome sequencing is increasingly used in the diagnosis of primary immunodeficiencies due to the overlapping and atypical presentations of these disorders. We report two patients who presented with recurrent infections and early onset colitis. They were investigated by whole exome sequencing due to suspicion of primary immunodeficiency and found to have mutations in pyrin known to cause familial Mediterranean fever.
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Colitis/genética , Fiebre Mediterránea Familiar/genética , Síndromes de Inmunodeficiencia/genética , Pirina/genética , Preescolar , Colitis/diagnóstico , Consanguinidad , Diagnóstico Diferencial , Fiebre Mediterránea Familiar/diagnóstico , Femenino , Humanos , Síndromes de Inmunodeficiencia/diagnóstico , Lactante , Masculino , MutaciónRESUMEN
To date, several germline mutations have been identified in the LRBA gene in patients suffering from a variety of clinical symptoms. These mutations abolish the expression of the LRBA protein, leading to autoimmunity, chronic diarrhea, B-cell deficiency, hypogammaglobulinemia, functional T-cell defects and aberrant autophagy. We review the clinical and laboratory features of patients with LRBA mutations and present five novel mutations in eight patients suffering from a multitude of clinical features.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Síndromes de Inmunodeficiencia/diagnóstico , Insuficiencia Respiratoria/diagnóstico , Proteínas Adaptadoras Transductoras de Señales/genética , Adolescente , Adulto , Animales , Autoinmunidad/genética , Autofagia/genética , Niño , Preescolar , Consanguinidad , Resultado Fatal , Femenino , Humanos , Lactante , Masculino , Mutación/genética , Linaje , Fenotipo , Adulto JovenRESUMEN
BACKGROUND: A number of heritable immune dysregulatory diseases result from defects affecting regulatory T (Treg) cell development, function, or both. They include immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, which is caused by mutations in forkhead box P3 (FOXP3), and IPEX-like disorders caused by mutations in IL-2 receptor α (IL2RA), signal transducer and activator of transcription 5b (STAT5b), and signal transducer and activator of transcription 1 (STAT1). However, the genetic defects underlying many cases of IPEX-like disorders remain unknown. OBJECTIVE: We sought to identify the genetic abnormalities in patients with idiopathic IPEX-like disorders. METHODS: We performed whole-exome and targeted gene sequencing and phenotypic and functional analyses of Treg cells. RESULTS: A child who presented with an IPEX-like syndrome and severe Treg cell deficiency was found to harbor a nonsense mutation in the gene encoding LPS-responsive beige-like anchor (LRBA), which was previously implicated as a cause of common variable immunodeficiency with autoimmunity. Analysis of subjects with LRBA deficiency revealed marked Treg cell depletion; profoundly decreased expression of canonical Treg cell markers, including FOXP3, CD25, Helios, and cytotoxic T lymphocyte-associated antigen 4; and impaired Treg cell-mediated suppression. There was skewing in favor of memory T cells and intense autoantibody production, with marked expansion of T follicular helper and contraction of T follicular regulatory cells. Whereas the frequency of recent thymic emigrants and the differentiation of induced Treg cells were normal, LRBA-deficient T cells exhibited increased apoptosis and reduced activities of the metabolic sensors mammalian target of rapamycin complexes 1 and 2. CONCLUSION: LRBA deficiency is a novel cause of IPEX-like syndrome and Treg cell deficiency associated with metabolic dysfunction and increased apoptosis of Treg cells.