RESUMEN
Human inborn errors of IFN-γ immunity underlie mycobacterial diseases. We describe patients with Mycobacterium bovis (BCG) disease who are homozygous for loss-of-function mutations of SPPL2A. This gene encodes a transmembrane protease that degrades the N-terminal fragment (NTF) of CD74 (HLA invariant chain) in antigen-presenting cells. The CD74 NTF therefore accumulates in the HLA class II+ myeloid and lymphoid cells of SPPL2a-deficient patients. This toxic fragment selectively depletes IL-12- and IL-23-producing CD1c+ conventional dendritic cells (cDC2s) and their circulating progenitors. Moreover, SPPL2a-deficient memory TH1* cells selectively fail to produce IFN-γ when stimulated with mycobacterial antigens in vitro. Finally, Sppl2a-/- mice lack cDC2s, have CD4+ T cells that produce small amounts of IFN-γ after BCG infection, and are highly susceptible to infection with BCG or Mycobacterium tuberculosis. These findings suggest that inherited SPPL2a deficiency in humans underlies mycobacterial disease by decreasing the numbers of cDC2s and impairing IFN-γ production by mycobacterium-specific memory TH1* cells.
Asunto(s)
Ácido Aspártico Endopeptidasas/genética , Ácido Aspártico Endopeptidasas/metabolismo , Células Dendríticas/inmunología , Proteínas de la Membrana/metabolismo , Infecciones por Mycobacterium/inmunología , Mycobacterium bovis/fisiología , Mycobacterium tuberculosis/fisiología , Células TH1/inmunología , Tuberculosis/inmunología , Animales , Antígenos de Diferenciación de Linfocitos B/metabolismo , Células Cultivadas , Antígenos HLA/metabolismo , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Inmunidad , Memoria Inmunológica , Lactante , Interferón gamma/metabolismo , Linfadenopatía , Masculino , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación/genética , Infecciones por Mycobacterium/genética , VacunaciónRESUMEN
Rationale and Objectives: Up to 20% of idiopathic interstitial lung disease is familial, referred to as familial pulmonary fibrosis (FPF). An integrated analysis of FPF genetic risk was performed by comprehensively evaluating for genetic rare variants (RVs) in a large cohort of FPF kindreds. Methods: Whole-exome sequencing and/or candidate gene sequencing from affected individuals in 569 FPF kindreds was performed, followed by cosegregation analysis in large kindreds, gene burden analysis, gene-based risk scoring, cell-type enrichment analysis, and coexpression network construction. Measurements and Main Results: It was found that 14.9-23.4% of genetic risk in kindreds could be explained by RVs in genes previously linked to FPF, predominantly telomere-related genes. New candidate genes were identified in a small number of families-including SYDE1, SERPINB8, GPR87, and NETO1-and tools were developed for evaluation and prioritization of RV-containing genes across kindreds. Several pathways were enriched for RV-containing genes in FPF, including focal adhesion and mitochondrial complex I assembly. By combining single-cell transcriptomics with prioritized candidate genes, expression of RV-containing genes was discovered to be enriched in smooth muscle cells, type II alveolar epithelial cells, and endothelial cells. Conclusions: In the most comprehensive FPF genetic study to date, the prevalence of RVs in known FPF-related genes was defined, and new candidate genes and pathways relevant to FPF were identified. However, new RV-containing genes shared across multiple kindreds were not identified, thereby suggesting that heterogeneous genetic variants involving a variety of genes and pathways mediate genetic risk in most FPF kindreds.
Asunto(s)
Enfermedades Pulmonares Intersticiales , Fibrosis Pulmonar , Humanos , Fibrosis Pulmonar/genética , Células Endoteliales , Enfermedades Pulmonares Intersticiales/genética , Factores de Riesgo , Telómero , Predisposición Genética a la Enfermedad/genética , Receptores del Ácido Lisofosfatídico/genéticaRESUMEN
BACKGROUND: Inborn errors of immunity (IEI) are a group of monogenic diseases that confer susceptibility to infection, autoimmunity, and cancer. Despite the life-threatening consequences of some IEI, their genetic cause remains unknown in many patients. OBJECTIVE: We investigated a patient with an IEI of unknown genetic etiology. METHODS: Whole-exome sequencing identified a homozygous missense mutation of the gene encoding ezrin (EZR), substituting a threonine for an alanine at position 129. RESULTS: Ezrin is one of the subunits of the ezrin, radixin, and moesin (ERM) complex. The ERM complex links the plasma membrane to the cytoskeleton and is crucial for the assembly of an efficient immune response. The A129T mutation abolishes basal phosphorylation and decreases calcium signaling, leading to complete loss of function. Consistent with the pleiotropic function of ezrin in myriad immune cells, multidimensional immunophenotyping by mass and flow cytometry revealed that in addition to hypogammaglobulinemia, the patient had low frequencies of switched memory B cells, CD4+ and CD8+ T cells, MAIT, γδ T cells, and centralnaive CD4+ cells. CONCLUSIONS: Autosomal-recessive human ezrin deficiency is a newly recognized genetic cause of B-cell deficiency affecting cellular and humoral immunity.
Asunto(s)
Linfocitos T CD8-positivos , Citoesqueleto , Humanos , Citoesqueleto/metabolismo , Membrana Celular/metabolismo , Inmunidad HumoralRESUMEN
Human BCL10 deficiency causes combined immunodeficiency with bone marrow transplantation as its only curative option. To date, there are four homozygous mutations described in the literature that were identified in four unrelated patients. Here, we describe a fifth patient with a novel mutation and summarize what we have learned about BCL10 deficiency. Due to the severity of the disease, accurate knowledge of its clinical and immunological characteristics is instrumental for early diagnosis and adequate clinical management of the patients.
Asunto(s)
Síndromes de Inmunodeficiencia , Humanos , Proteína 10 de la LLC-Linfoma de Células B/genética , Trasplante de Médula Ósea , Síndromes de Inmunodeficiencia/diagnóstico , Síndromes de Inmunodeficiencia/genética , Síndromes de Inmunodeficiencia/terapia , Mutación/genéticaRESUMEN
Mendelian susceptibility to mycobacterial disease (MSMD) is characterized by clinical disease caused by weakly virulent mycobacteria, such as environmental mycobacteria and Bacillus Calmette-Guérin vaccines, in otherwise healthy individuals. All known genetic etiologies disrupt interferon (IFN)-γ immunity. Germline bi-allelic mutations of IFNGR2 can underlie partial or complete forms of IFN-γ receptor 2 (IFN-γR2) deficiency. Patients with partial IFN-γR2 deficiency express a dysfunctional molecule on the cell surface. We studied three patients with MSMD from two unrelated kindreds from Turkey (P1, P2) and India (P3), by whole-exome sequencing. P1 and P2 are homozygous for a mutation of the initiation codon(c.1A>G) of IFNGR2, whereas P3 is homozygous for a mutation of the second codon (c.4delC). Overexpressed mutant alleles produce small amounts of full-length IFN-γR2 resulting in an impaired, but not abolished, response to IFN-γ. Moreover, SV40-fibroblasts of P1 and P2 responded weakly to IFN-γ, and Epstein Barr virus-transformed B cells had a barely detectable response to IFN-γ. Studies in patients' primary T cells and monocyte-derived macrophages yielded similar results. The residual expression of IFN-γR2 protein of normal molecular weight and function is due to the initiation of translation between the second and ninth non-AUG codons. We thus describe mutations of the first and second codons of IFNGR2, which define a new form of partial recessive IFN-γR2 deficiency. Residual levels of IFN-γ signaling were very low, accounting for the more severe clinical phenotype of these patients with residual expression levels of normally functional surface receptors than of patients with partial recessive IFN-γR2 deficiency due to surface-expressed dysfunctional receptors, whose residual levels of IFN-γ signaling were higher.
Asunto(s)
Alelos , Codón Iniciador , Predisposición Genética a la Enfermedad , Mutación de Línea Germinal , Homocigoto , Infecciones por Mycobacterium/genética , Receptores de Interferón/genética , Niño , Preescolar , Femenino , Humanos , India , Lactante , Recién Nacido , Masculino , Turquía , Secuenciación del ExomaRESUMEN
In 2014, a child with broad combined immunodeficiency (CID) who was homozygous for a private BCL10 allele was reported to have complete inherited human BCL10 deficiency. In the present study, we report a new BCL10 mutation in another child with CID who was homozygous for a BCL10 variant (R88X), previously reported as a rare allele in heterozygosis (minor allele frequency, 0.000003986). The mutant allele was a loss-of-expression and loss-of-function allele. As with the previously reported patient, this patient had complete BCL10 deficiency. The clinical phenotype shared features, such as respiratory infections, but differed from that of the previous patient that he did not develop significant gastroenteritis episodes or chronic colitis. Cellular and immunological phenotypes were similar to those of the previous patient. TLR4, TLR2/6, and Dectin-1 responses were found to depend on BCL10 in fibroblasts, and final maturation of T cell and B cell maturation into memory cells was affected. Autosomal-recessive BCL10 deficiency should therefore be considered in children with CID.
Asunto(s)
Proteína 10 de la LLC-Linfoma de Células B/genética , Linfocitos B/inmunología , Síndromes de Inmunodeficiencia/genética , Mutación/genética , Linfocitos T/inmunología , Células Cultivadas , Trastornos de los Cromosomas , Homocigoto , Humanos , Memoria Inmunológica , Lactante , Lectinas Tipo C/metabolismo , Masculino , Infecciones del Sistema Respiratorio , Receptores Toll-Like/metabolismoRESUMEN
Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN-γ immunity. Since 1996, disease-causing mutations have been found in 11 genes, which, through allelic heterogeneity, underlie 21 different genetic disorders. We briefly review here progress in the study of molecular, cellular and clinical aspects of MSMD since the last comprehensive review published in 2014. Highlights include the discoveries of (1) a new genetic etiology, autosomal recessive signal peptide peptidase-like 2 A deficiency, (2) TYK2-deficient patients with a clinical phenotype of MSMD, (3) an allelic form of partial recessive IFN-γR2 deficiency, and (4) two forms of syndromic MSMD: RORγ/RORγT and JAK1 deficiencies. These recent findings illustrate how genetic and immunological studies of MSMD can shed a unique light onto the mechanisms of protective immunity to mycobacteria in humans.
Asunto(s)
Predisposición Genética a la Enfermedad , Infecciones por Mycobacterium/genética , Alelos , Sitios Genéticos , Geografía , Humanos , Mutación/genéticaRESUMEN
The integrity of the interferon (IFN)-γ circuit is necessary to mount an effective immune response to intra-macrophagic pathogens, especially Mycobacteria. Inherited monogenic defects in this circuit that disrupt the production of, or response to, IFN-γ underlie a primary immunodeficiency known as Mendelian susceptibility to mycobacterial disease (MSMD). Otherwise healthy patients display a selective susceptibility to clinical disease caused by poorly virulent mycobacteria such as BCG (bacille Calmette-Guérin) vaccines and environmental mycobacteria, and more rarely by other intra-macrophagic pathogens, particularly Salmonella and M. tuberculosis. There is high genetic and allelic heterogeneity, with 19 genetic etiologies due to mutations in 10 genes that account for only about half of the patients reported. An efficient laboratory diagnostic approach to suspected MSMD patients is important, because it enables the establishment of specific therapeutic measures that will improve the patient's prognosis and quality of life. Moreover, it is essential to offer genetic counseling to affected families. Herein, we review the various genetic and immunological diagnostic approaches that can be used in concert to reach a molecular and cellular diagnosis in patients with MSMD.
Asunto(s)
Predisposición Genética a la Enfermedad/genética , Síndromes de Inmunodeficiencia/diagnóstico , Síndromes de Inmunodeficiencia/genética , Interferón gamma/genética , Técnicas de Diagnóstico Molecular , Infecciones por Mycobacterium/genética , Vacuna BCG , Humanos , MycobacteriumRESUMEN
The protein-coding exome of a patient with a monogenic disease contains about 20,000 variants, only one or two of which are disease causing. We found that 58% of rare variants in the protein-coding exome of the general population are located in only 2% of the genes. Prompted by this observation, we aimed to develop a gene-level approach for predicting whether a given human protein-coding gene is likely to harbor disease-causing mutations. To this end, we derived the gene damage index (GDI): a genome-wide, gene-level metric of the mutational damage that has accumulated in the general population. We found that the GDI was correlated with selective evolutionary pressure, protein complexity, coding sequence length, and the number of paralogs. We compared GDI with the leading gene-level approaches, genic intolerance, and de novo excess, and demonstrated that GDI performed best for the detection of false positives (i.e., removing exome variants in genes irrelevant to disease), whereas genic intolerance and de novo excess performed better for the detection of true positives (i.e., assessing de novo mutations in genes likely to be disease causing). The GDI server, data, and software are freely available to noncommercial users from lab.rockefeller.edu/casanova/GDI.
Asunto(s)
Exoma , Enfermedades Genéticas Congénitas/genética , Humanos , Curva ROCRESUMEN
Background: Mutations in genes affecting interferon-γ (IFN-γ) immunity have contributed to understand the role of IFN-γ in protection against intracellular pathogens. However, inborn errors in STAT4, which controls interleukin-12 (IL-12) responses, have not yet been reported. Our objective was to determine the genetic defect in a family with a history of paracoccidioidomycosis. Methods: Genetic analysis was performed by whole-exome sequencing and Sanger sequencing. STAT4 phosphorylation (pSTAT4) and translocation to the nucleus, IFN-γ release by patient lymphocytes, and microbicidal activity of patient monocytes/macrophages were assessed. The effect on STAT4 function was evaluated by site-directed mutagenesis using a lymphoblastoid B cell line (B-LCL) and U3A cells. Results: A heterozygous missense mutation, c.1952 A>T (p.E651V) in STAT4 was identified in the index patient and her father. Patient's and father's lymphocytes showed reduced pSTAT4, nuclear translocation, and impaired IFN-γ production. Mutant B-LCL and U3A cells also displayed reduced pSTAT4. Patient's and father's peripheral blood mononuclear cells and macrophages demonstrated impaired fungicidal activity compared with those from healthy controls that improved in the presence of recombinant human IFN-γ, but not rhIL-12. Conclusion: Our data suggest autosomal dominant STAT4 deficiency as a novel inborn error of IL-12-dependent IFN-γ immunity associated with susceptibility to paracoccidioidomycosis.
Asunto(s)
Predisposición Genética a la Enfermedad , Interferón gamma/deficiencia , Subunidad p35 de la Interleucina-12/metabolismo , Mutación Missense , Paracoccidioidomicosis/genética , Factor de Transcripción STAT4/genética , Adulto , Anciano , Línea Celular , Salud de la Familia , Femenino , Genotipo , Heterocigoto , Humanos , Linfocitos/inmunología , Macrófagos/inmunología , Masculino , Análisis de Secuencia de ADNRESUMEN
B-cell lymphoma 10 (BCL10) is not essential for actin polymerisation after FcγR stimulation in human fibroblasts.
Asunto(s)
Actinas/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Fibroblastos/metabolismo , Síndromes de Inmunodeficiencia/genética , Polimerizacion , Receptores de IgG/inmunología , Proteínas Adaptadoras Transductoras de Señales/inmunología , Proteína 10 de la LLC-Linfoma de Células B , Proteínas Adaptadoras de Señalización CARD/inmunología , Estudios de Casos y Controles , Caspasas/inmunología , Fibroblastos/inmunología , Humanos , Síndromes de Inmunodeficiencia/inmunología , Síndromes de Inmunodeficiencia/metabolismo , Microscopía Fluorescente , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas , FN-kappa B/inmunología , Proteínas de Neoplasias/inmunología , Transducción de Señal/inmunologíaRESUMEN
Antibody deficiencies can be caused by a variety of defects that interfere with B-cell development, maturation, and/or function. Using whole-exome sequencing we found a PIK3R1 mutation in a patient with hypogammaglobulinemia and a narrow clinical phenotype of respiratory infections. Early diagnosis is crucial; careful analysis of B and T-cells followed by genetic analyses may help to distinguish activated PI3K-delta syndrome (APDS) from other, less severe, predominantly antibody deficiencies.
Asunto(s)
Agammaglobulinemia/genética , Fosfatidilinositol 3-Quinasas/genética , Infecciones del Sistema Respiratorio/genética , Agammaglobulinemia/inmunología , Linfocitos B/inmunología , Niño , Fosfatidilinositol 3-Quinasa Clase Ia , Femenino , Humanos , Mutación , Fenotipo , Infecciones del Sistema Respiratorio/inmunología , Linfocitos T/inmunologíaRESUMEN
Three members of the caspase recruitment domain (CARD) family of adaptors (CARD9, CARD10, and CARD11) are known to form heterotrimers with B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma-translocation gene 1 (MALT1). These 3 CARD-BCL10-MALT1 (CBM) complexes activate nuclear factor κB in both the innate and adaptive arms of immunity. Human inherited defects of the 3 components of the CBM complex, including the 2 adaptors CARD9 and CARD11 and the 2 core components BCL10 and MALT1, have recently been reported. Biallelic loss-of-function mutant alleles underlie several different immunologic and clinical phenotypes, which can be assigned to 2 distinct categories. Isolated invasive fungal infections of unclear cellular basis are associated with CARD9 deficiency, whereas a broad range of clinical manifestations, including those characteristic of T- and B-lymphocyte defects, are associated with CARD11, MALT1, and BCL10 deficiencies. Interestingly, human subjects with these mutations have some features in common with the corresponding knockout mice, but other features are different between human subjects and mice. Moreover, germline and somatic gain-of-function mutations of MALT1, BCL10, and CARD11 have also been found in patients with other lymphoproliferative disorders. This broad range of germline and somatic CBM lesions, including loss-of-function and gain-of-function mutations, highlights the contribution of each of the components of the CBM complex to human immunity.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras de Señalización CARD/genética , Caspasas/genética , Síndromes de Inmunodeficiencia/genética , Micosis/genética , Proteínas de Neoplasias/genética , Inmunidad Adaptativa , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Proteína 10 de la LLC-Linfoma de Células B , Proteínas Adaptadoras de Señalización CARD/metabolismo , Caspasas/metabolismo , Predisposición Genética a la Enfermedad , Guanilato Ciclasa/genética , Humanos , Inmunidad Innata , Ratones , Ratones Noqueados , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas , Mutación/genética , Proteínas de Neoplasias/metabolismo , Polimorfismo GenéticoRESUMEN
We report a molecular study of the two known patients with autosomal recessive, partial interferon-γ receptor (IFN-γR)2 deficiency (homozygous for mutations R114C and G227R), and three novel, unrelated children, homozygous for S124F (P1) and G141R (P2 and P3). IFN-γR2 levels on the surface of the three latter patients' cells are slightly lower than those on control cells. The patients' cells also display impaired, but not abolished, response to IFN-γ. Moreover, the R114C, S124F, G141R and G227R IFNGR2 hypomorphic alleles all encode misfolded proteins with abnormal N-glycosylation. The mutants are largely retained in the endoplasmic reticulum, although a small proportion reach and function at the cell surface. Strikingly, the IFN-γ response of the patients' cells is enhanced by chemical modifiers of N-glycosylation, as previously shown for patients with gain-of-glysosylation T168N and misfolding 382-387dup null mutations. All four in-frame IFNGR2 hypomorphic mutant alleles encoding surface-expressed receptors are thus deleterious by a mechanism involving abnormal N-glycosylation and misfolding of the IFN-γR2 protein. The diagnosis of partial IFN-γR2 deficiency is clinically useful, as affected patients should be treated with IFN-γ, [corrected] unlike patients with complete IFN-γR2 deficiency. Moreover, inhibitors of glycosylation might be beneficial in patients with complete or partial IFN-γR2 deficiency due to misfolding or gain-of-glycosylation receptors.
Asunto(s)
Deficiencias en la Proteostasis/genética , Receptores de Interferón/deficiencia , Receptores de Interferón/genética , Alcaloides/farmacología , Secuencia de Bases , Western Blotting , Niño , Inhibidores Enzimáticos/farmacología , Femenino , Citometría de Flujo , Predisposición Genética a la Enfermedad/genética , Glicosilación/efectos de los fármacos , Humanos , Masculino , Microscopía Confocal , Datos de Secuencia Molecular , Mutación , Infecciones por Mycobacterium/genética , Linaje , TransfecciónAsunto(s)
Proteína 10 de la LLC-Linfoma de Células B/deficiencia , Roturas del ADN de Doble Cadena , Reparación del ADN , Proteína 10 de la LLC-Linfoma de Células B/genética , Línea Celular , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Recombinación Homóloga , Humanos , Peróxido de Hidrógeno/toxicidad , Hidroxiurea/toxicidadRESUMEN
Interferon-γ receptor 2 (IFN-γR2) deficiency is a rare primary immunodeficiency characterized by predisposition to infections with weakly virulent mycobacteria, such as environmental mycobacteria and BCG vaccines. We describe here two children with IFN-γR2 deficiency, from unrelated, consanguineous kindreds of Arab and Israeli descent. The first patient was a boy who died at the age of 4.5 years, from recurrent, disseminated disease caused by Mycobacterium simiae. His IFN-γR2 defect was autosomal recessive and complete. The second patient was a girl with multiple disseminated mycobacterial infections, including infection with M. simiae. She died at the age of 5 years, a short time after the transplantation of umbilical cord blood cells from an unrelated donor. Her IFN-γR2 defect was autosomal recessive and partial. Autosomal recessive IFN-γR2 deficiency is life-threatening, even in its partial form, and genetic diagnosis and familial counseling are therefore particularly important for this condition. These two cases are the first of IFN-γR2 deficiency associated with M. simiae infection to be described.
Asunto(s)
Síndromes de Inmunodeficiencia/complicaciones , Síndromes de Inmunodeficiencia/genética , Infecciones por Mycobacterium/complicaciones , Infecciones por Mycobacterium/patología , Receptores de Interferón/deficiencia , Receptores de Interferón/genética , Preescolar , Resultado Fatal , Femenino , Predisposición Genética a la Enfermedad , Humanos , Síndromes de Inmunodeficiencia/inmunología , Masculino , Infecciones por Mycobacterium/inmunología , Infecciones por Mycobacterium/mortalidadRESUMEN
PURPOSE: Chronic granulomatous disease (CGD) is characterized by an inability of phagocytes to produce reactive oxygen species (ROS), which are required to kill some microorganisms. CGD patients are known to suffer from recurrent bacterial and/or fungal infections from the first year of life onwards. From 2009 to 2013, 12 cases of CGD were diagnosed in Morocco. We describe here these Moroccan cases of CGD. METHODS: We investigated the genetic, immunological and clinical features of 12 Moroccan patients with CGD from 10 unrelated kindreds. RESULTS: All patients were children suffering from recurrent bacterial and/or fungal infections. All cases displayed impaired NADPH oxidase activity in nitroblue tetrazolium (NBT), dihydrorhodamine (DHR) or 2',7' dichlorofluorescein diacetate (DCFH-DA) assays. Mutation analysis revealed the presence of four different mutations of CYBB in four kindreds, a recurrent mutation of NCF1 in three kindreds, and a new mutation of NCF2 in three patients from a single kindred. A large deletion of CYBB gene has detected in a patient. The causal mutation in the remaining one kindred was not identified. CONCLUSION: The clinical features and infectious agents found in these patients were similar to those in CGD patients from elsewhere. The results of mutation analysis differed between kindreds, revealing a high level of genetic and allelic heterogeneity among Moroccan CGD patients. The small number of patients in our cohort probably reflects a lack of awareness of physicians. Further studies on a large cohort are required to determine the incidence and prevalence of the disease, and to improve the description of the genetic and clinical features of CGD patients in Morocco.
Asunto(s)
Aspergilosis/genética , Infecciones Bacterianas/genética , Enfermedad Granulomatosa Crónica/genética , Glicoproteínas de Membrana/genética , NADPH Oxidasas/genética , Adolescente , Alelos , Aspergilosis/complicaciones , Aspergilosis/inmunología , Aspergilosis/patología , Infecciones Bacterianas/complicaciones , Infecciones Bacterianas/inmunología , Infecciones Bacterianas/patología , Niño , Preescolar , Análisis Mutacional de ADN , Femenino , Genes Recesivos , Enfermedad Granulomatosa Crónica/complicaciones , Enfermedad Granulomatosa Crónica/inmunología , Enfermedad Granulomatosa Crónica/patología , Humanos , Lactante , Recién Nacido , Masculino , Mutación , NADPH Oxidasa 2 , LinajeRESUMEN
Common polymorphisms in complement alternative pathway (AP) proteins C3 (C3(R102G)), factor B (fB(R32Q)), and factor H (fH(V62I)) are associated with age-related macular degeneration (AMD) and other pathologies. Our published work showed that fB(R32Q) influences C3 convertase formation, whereas fH(V62I) affects factor I cofactor activity. Here we show how C3(R102G) (C3S/F) influences AP activity. In hemolysis assays, C3(102G) activated AP more efficiently (EC(50) C3(102G): 157 nM; C3(102R): 191 nM; P < 0.0001). fB binding kinetics and convertase stability were identical, but native and recombinant fH bound more strongly to C3b(102R) (K(D) C3b(102R): 1.0 µM; C3b(102G): 1.4 µM; P < 0.0001). Accelerated decay was unaltered, but fH cofactor activity was reduced for C3b(102G), favoring AP amplification. Combining disease "risk" variants (C3(102G), fB(32R), and fH(62V)) in add-back assays yielded sixfold higher hemolytic activity compared with "protective" variants (C3(102R), fB(32Q), and fH(62I); P < 0.0001). These data introduce the concept of a functional complotype (combination of polymorphisms) defining complement activity in an individual, thereby influencing susceptibility to AP-driven disease.