Research Center Biomedica en Enfermedades Raras

Entrín Bajo, Spain

Research Center Biomedica en Enfermedades Raras

Entrín Bajo, Spain
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Lopez-Perrote A.,CSIC - Biological Research Center | Harrison R.E.S.,University of California at Riverside | Subias M.,CSIC - Biological Research Center | Subias M.,Research Center Biomedica en Enfermedades Raras | And 5 more authors.
Molecular Immunology | Year: 2017

C3b, the central component of the alternative pathway (AP) of the complement system, coexists as a mixture of conformations in solution. These conformational changes can affect interactions with other proteins and complement regulators. Here we combine a computational model for electrostatic interactions within C3b with molecular imaging to study the conformation of C3b. The computational analysis shows that the TED domain in C3b is tethered ionically to the macroglobulin (MG) ring. Monovalent counterion concentration affects the magnitude of electrostatic forces anchoring the TED domain to the rest of the C3b molecule in a thermodynamic model. This is confirmed by observing NaCl concentration dependent conformational changes using single molecule electron microscopy (EM). We show that the displacement of the TED domain is compatible with C3b binding to Factor B (FB), suggesting that the regulation of the C3bBb convertase could be affected by conditions that promote movement in the TED domain. Our molecular model also predicts mutations that could alter the positioning of the TED domain, including the common R102G polymorphism, a risk variant for developing age-related macular degeneration. The common C3b isoform, C3bS, and the risk isoform, C3bF, show distinct energetic barriers to displacement in the TED that are related to a network of electrostatic interactions at the interface of the TED and MG-ring domains of C3b. These computational predictions agree with experimental evidence that shows differences in conformation observed in C3b isoforms purified from homozygous donors. Altogether, we reveal an ionic, reversible attachment of the TED domain to the MG ring that may influence complement regulation in some mutations and polymorphisms of C3b. © 2016 Elsevier Ltd


Jozsi M.,Eötvös Loránd University | Tortajada A.,CSIC - Biological Research Center | Tortajada A.,Research Center Biomedica en Enfermedades Raras | Uzonyi B.,Eötvös Loránd University | And 5 more authors.
Trends in Immunology | Year: 2015

Complement factor H-related proteins (FHRs) are strongly associated with different diseases involving complement dysregulation, which suggests a major role for these proteins regulating complement activation. Because FHRs are evolutionarily and structurally related to complement inhibitor factor H (FH), the initial assumption was that the FHRs are also negative complement regulators. Whereas weak complement inhibiting activities were originally reported for these molecules, recent developments indicate that FHRs may enhance complement activation, with important implications for the role of these proteins in health and disease. We review these findings here, and propose that FHRs represent a complex set of surface recognition molecules that, by competing with FH, provide improved discrimination of self and non-self surfaces and play a central role in determining appropriate activation of the complement pathway. © 2015 Elsevier Ltd.


Chinchilla D.S.,CSIC - Biological Research Center | Chinchilla D.S.,Research Center Biomedica en Enfermedades Raras | Pinto S.,CSIC - Biological Research Center | Pinto S.,Research Center Biomedica en Enfermedades Raras | And 11 more authors.
Clinical Journal of the American Society of Nephrology | Year: 2014

Background and objectives: Atypical hemolytic uremic syndrome is characterized by vascular endothelial damage caused by complement dysregulation. Consistently, complement inhibition therapies are highly effective in most patients with atypical hemolytic uremic syndrome. Recently, it was shown that a significant percentage of patients with early-onset atypical hemolytic uremic syndrome carry mutations in diacylglycerol kinase-e, an intracellular protein with no obvious role in complement. These data support an alternative, complement- independent mechanism leading to thrombotic microangiopathy that has implications for treatment of early-onset atypical hemolytic uremic syndrome. To get additional insights into this new form of atypical hemolytic uremic syndrome, the diacylglycerol kinase-e gene in a cohort with atypical hemolytic uremic syndrome was analyzed. Design, setting, participants, & measurements: Eighty-three patients with early-onset atypical hemolytic uremic syndrome (,2 years) enrolled in the Spanish atypical hemolytic uremic syndrome registry between 1999 and 2013 were screened for mutations in diacylglycerol kinase-e. These patients were also fully characterized for mutations in the genes encoding factorH,membrane cofactor protein, factor I, C3, factor B, and thrombomodulin CFHRs copy number variations and rearrangements, and antifactor H antibodies. Results: Four patients carried mutations in diacylglycerol kinase-e, one p.H536Qfs*16 homozygote and three compound heterozygotes (p.W322*/p.P498R, two patients; p.Q248H/p.G484Gfs*10, one patient). Three patients also carried heterozygous mutations in thrombomodulin or C3. Extensive plasma infusions controlled atypical hemolytic uremic syndrome recurrences and prevented renal failure in the two patients with diacylglycerol kinase-e and thrombomodulin mutations. A positive response to plasma infusions and complement inhibition treatment was also observed in the patient with concurrent diacylglycerol kinase-« and C3 mutations. Conclusions: Data suggest that complement dysregulation influences the onset and disease severity in carriers of diacylglycerol kinase-e mutations and that treatments on the basis of plasma infusions and complement inhibition are potentially useful in patients with combined diacylglycerol kinase-e and complement mutations. A comprehensive understanding of the genetic component predisposing to atypical hemolytic uremic syndrome is, therefore, critical to guide an effective treatment. © 2014 by the American Society of Nephrology.


Subias M.,CSIC - Biological Research Center | Subias M.,Research Center Biomedica en Enfermedades Raras | Tortajada A.,CSIC - Biological Research Center | Tortajada A.,Research Center Biomedica en Enfermedades Raras | And 16 more authors.
Journal of Immunology | Year: 2014

The alternative pathway (AP) is critical for the efficient activation of complement regardless of the trigger. It is also a major player in pathogenesis, as illustrated by the long list of diseases in which AP activation contributes to pathology. Its relevance to human disease is further emphasized by the high prevalence of pathogenic inherited defects and acquired autoantibodies disrupting components and regulators of the AP C3-convertase. Because pharmacological downmodulation of the AP emerges as a broad-spectrum treatment alternative, there is a powerful interest in developing new molecules to block formation and/or activity of the AP C3-convertase. In this paper, we describe the generation of a novel mAb targeting human factor B (FB). mAb FB48.4.2, recognizing with high affinity an evolutionary-conserved epitope in the Ba fragment of FB, very efficiently inhibited formation of the AP C3-proconvertase by blocking the interaction between FB and C3b. In vitro assays using rabbit and sheep erythrocytes demonstrated that FB28.4.2 was a potent AP inhibitor that blocked complement-mediated hemolysis in several species. Using ex vivo models of disease we demonstrated that FB28.4.2 protected paroxysmal nocturnal hemoglobinuria erythrocytes from complement-mediated hemolysis and inhibited both C3 fragment and C5b-9 deposition on ADP-activated HMEC-1 cells, an experimental model for atypical hemolytic uremic syndrome. Moreover, i.v. injection of FB28.4.2 in rats blocked complement activation in rat serum and prevented the passive induction of experimental autoimmune Myasthenia gravis. As a whole, these data demonstrate the potential value of FB28.4.2 for the treatment of disorders associated with AP complement dysregulation in man and animal models. Copyright © 2014 by The American Association of Immunologists, Inc.


PubMed | Hospital Universitario La Paz, University of Bonn, Research Center Biomedica en Enfermedades Raras, Servicio de Nefrologia Pediatrica. and 3 more.
Type: Journal Article | Journal: Clinical journal of the American Society of Nephrology : CJASN | Year: 2014

Atypical hemolytic uremic syndrome is characterized by vascular endothelial damage caused by complement dysregulation. Consistently, complement inhibition therapies are highly effective in most patients with atypical hemolytic uremic syndrome. Recently, it was shown that a significant percentage of patients with early-onset atypical hemolytic uremic syndrome carry mutations in diacylglycerol kinase-, an intracellular protein with no obvious role in complement. These data support an alternative, complement-independent mechanism leading to thrombotic microangiopathy that has implications for treatment of early-onset atypical hemolytic uremic syndrome. To get additional insights into this new form of atypical hemolytic uremic syndrome, the diacylglycerol kinase- gene in a cohort with atypical hemolytic uremic syndrome was analyzed.Eighty-three patients with early-onset atypical hemolytic uremic syndrome (<2 years) enrolled in the Spanish atypical hemolytic uremic syndrome registry between 1999 and 2013 were screened for mutations in diacylglycerol kinase-. These patients were also fully characterized for mutations in the genes encoding factor H, membrane cofactor protein, factor I, C3, factor B, and thrombomodulin CFHRs copy number variations and rearrangements, and antifactor H antibodies.Four patients carried mutations in diacylglycerol kinase-, one p.H536Qfs*16 homozygote and three compound heterozygotes (p.W322*/p.P498R, two patients; p.Q248H/p.G484Gfs*10, one patient). Three patients also carried heterozygous mutations in thrombomodulin or C3. Extensive plasma infusions controlled atypical hemolytic uremic syndrome recurrences and prevented renal failure in the two patients with diacylglycerol kinase- and thrombomodulin mutations. A positive response to plasma infusions and complement inhibition treatment was also observed in the patient with concurrent diacylglycerol kinase- and C3 mutations.Data suggest that complement dysregulation influences the onset and disease severity in carriers of diacylglycerol kinase- mutations and that treatments on the basis of plasma infusions and complement inhibition are potentially useful in patients with combined diacylglycerol kinase- and complement mutations. A comprehensive understanding of the genetic component predisposing to atypical hemolytic uremic syndrome is, therefore, critical to guide an effective treatment.


Cabello J.,Center for Biomedical Research of la Rioja | Samann J.,Center for Biochemistry and Molecular Cell Research | Gomez-Orte E.,Center for Biomedical Research of la Rioja | Erazo T.,Autonomous University of Barcelona | And 15 more authors.
Cell Death and Disease | Year: 2014

Apoptotic cell death is an integral part of cell turnover in many tissues, and proper corpse clearance is vital to maintaining tissue homeostasis in all multicellular organisms. Even in tissues with high cellular turnover, apoptotic cells are rarely seen because of efficient clearance mechanisms in healthy individuals. In Caenorhabditis elegans, two parallel and partly redundant conserved pathways act in cell corpse engulfment. The pathway for cytoskeletal rearrangement requires the small GTPase CED-10 Rac1 acting for an efficient surround of the dead cell. The CED-10 Rac pathway is also required for the proper migration of the distal tip cells (DTCs) during the development of the C. elegans gonad. Parkin, the mammalian homolog of the C. elegans PDR-1, interacts with Rac1 in aged human brain and it is also implicated with actin dynamics and cytoskeletal rearrangements in Parkinsons's disease, suggesting that it might act on engulfment. Our genetic and biochemical studies indicate that PDR-1 inhibits apoptotic cell engulfment and DTC migration by ubiquitylating CED-10 for degradation. © 2014 Macmillan Publishers Limited All rights reserved.


Tortajada A.,CSIC - Biological Research Center | Tortajada A.,Research Center Biomedica en Enfermedades Raras | Yebenes H.,CSIC - Biological Research Center | Abarrategui-Garrido C.,Research Center Biomedica en Enfermedades Raras | And 21 more authors.
Journal of Clinical Investigation | Year: 2013

C3 glomerulopathies (C3G) are a group of severe renal diseases with distinct patterns of glomerular inflammation and C3 deposition caused by complement dysregulation. Here we report the identification of a familial C3G-associated genomic mutation in the gene complement factor H-related 1 (CFHR1), which encodes FHR1. The mutation resulted in the duplication of the N-terminal short consensus repeats (SCRs) that are conserved in FHR2 and FHR5. We determined that native FHR1, FHR2, and FHR5 circulate in plasma as homo- and hetero-oligomeric complexes, the formation of which is likely mediated by the conserved N-terminal domain. In mutant FHR1, duplication of the N-terminal domain resulted in the formation of unusually large multimeric FHR complexes that exhibited increased avidity for the FHR1 ligands C3b, iC3b, and C3dg and enhanced competition with complement factor H (FH) in surface plasmon resonance (SPR) studies and hemolytic assays. These data revealed that FHR1, FHR2, and FHR5 organize a combinatorial repertoire of oligomeric complexes and demonstrated that changes in FHR oligomerization influence the regulation of complement activation. In summary, our identification and characterization of a unique CFHR1 mutation provides insights into the biology of the FHRs and contributes to our understanding of the pathogenic mechanisms underlying C3G. Copyright © 2013, American Society for Clinical Investigation.


Padilla N.,University of Barcelona | Padilla N.,Institute dInvestigacions Biomediques August Pi i Sunyer IDIBAPS | Padilla N.,Research Center Biomedica en Enfermedades Raras | Junque C.,University of Barcelona | And 17 more authors.
Brain Research | Year: 2014

Intrauterine growth restriction (IUGR) is associated with a high risk of abnormal neurodevelopment. Underlying neuroanatomical substrates are partially documented. We hypothesized that at 12 months preterm infants would evidence specific white-matter microstructure alterations and gray-matter differences induced by severe IUGR. Twenty preterm infants with IUGR (26-34 weeks of gestation) were compared with 20 term-born infants and 20 appropriate for gestational age preterm infants of similar gestational age. Preterm groups showed no evidence of brain abnormalities. At 12 months, infants were scanned sleeping naturally. Gray-matter volumes were studied with voxel-based morphometry. White-matter microstructure was examined using tract-based spatial statistics. The relationship between diffusivity indices in white matter, gray matter volumes, and perinatal data was also investigated. Gray-matter decrements attributable to IUGR comprised amygdala, basal ganglia, thalamus and insula bilaterally, left occipital and parietal lobes, and right perirolandic area. Gray-matter volumes positively correlated with birth weight exclusively. Preterm infants had reduced FA in the corpus callosum, and increased FA in the anterior corona radiata. Additionally, IUGR infants had increased FA in the forceps minor, internal and external capsules, uncinate and fronto-occipital white matter tracts. Increased axial diffusivity was observed in several white matter tracts. Fractional anisotropy positively correlated with birth weight and gestational age at birth. These data suggest that IUGR differentially affects gray and white matter development preferentially affecting gray matter. At 12 months IUGR is associated with a specific set of structural gray-matter decrements. White matter follows an unusual developmental pattern, and is apparently affected by IUGR and prematurity combined. © 2013 Elsevier B.V.


Padilla N.,University of Barcelona | Padilla N.,Institute dInvestigacions Biomediques August Pi i Sunyer IDIBAPS | Padilla N.,Research Center Biomedica en Enfermedades Raras | Falcon C.,Institute dInvestigacions Biomediques August Pi i Sunyer IDIBAPS | And 22 more authors.
Brain Research | Year: 2011

Previous evidence suggests that preterm newborns with intrauterine growth restriction (IUGR) have specific neurostructural and neurodevelopmental anomalies, but it is unknown whether these effects persist in early childhood. We studied a sample of 18 preterm IUGR, 15 preterm AGA - born between 26 and 34 weeks of gestational age (GA) - and 15 healthy born-term infants. Infants were scanned at 12 months corrected age (CA), in a 3T scanner, without sedation. Analyses were made by automated lobar volumetry and voxel-based morphometry (VBM). The neurodevelopmental outcome was assessed in all subjects at 18 months CA with the Bayley Scale for Infant and Toddler Development, third edition. IUGR infants had reduced relative volumes for the insular and temporal lobes. According to VBM, IUGR infants had bilateral reduced gray matter (GM) in the temporal, parietal, frontal, and insular regions compared with the other groups. IUGR infants had increased white matter (WM) in temporal regions compared to the AGA group and in frontal, parietal, occipital, and insular regions compared to the term group. They also showed decreased WM in the cerebellum and a non-significant trend in the hippocampus compared to term infants. IUGR infants had reduced neurodevelopmental scores, which were positively correlated with GM in various regions. These data suggest that the IUGR induces a distinct brain pattern of structural changes that persist at 1 year of life and are associated with specific developmental difficulties. © 2011 Elsevier B.V. All rights reserved.


Ferri G.,University of Modena and Reggio Emilia | Corradini B.,University of Modena and Reggio Emilia | Estany-Gestal A.,University of Santiago de Compostela | Diz P.S.,University of Santiago de Compostela | And 3 more authors.
Forensic Science International: Genetics Supplement Series | Year: 2011

Suicide is a devastating psychopathological trait with familial transmission. According to epidemiological data suicide is partly under genetic influence. Despite the extensive body of association studies, to date genetic factors linked to suicide diathesis are largely unknown. In this study a set of 8 SNPs and a 43. bp ins/del was genotyped in an Italian sample of suicide completers (n= 65) and control subjects (n= 77). The selected markers are spread across multiple brain pathways: serotonergic, stress-related HPA axis, catecholamine metabolism and nitric oxide (NO) neurotransmission. Basic analysis at single loci shows significant differences in allele and genotype distributions between victims and controls for TPH1-rs1800532(allele A) and NOSI-rs693534(allele A), pointing to an association with the group of suicides. Presented results are intended to be exploratory, requiring further investigation in a larger sample size. Systematic efforts in suicide research is quite important in order to empower understanding of risk factors and developing preventive strategies in clinical practice. © 2011 Elsevier Ireland Ltd.

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