Genetic investigation of Nordic patients with complement-mediated kidney diseases

BackgroundComplement activation in atypical hemolytic uremic syndrome (aHUS), C3 glomerulonephropathy (C3G) and immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) may be associated with rare genetic variants. Here we describe gene variants in the Swedish and Norwegian populations.MethodsPatients with these diagnoses (N=141) were referred for genetic screening. Sanger or next-generation sequencing were performed to identify genetic variants in 16 genes associated with these conditions. Nonsynonymous genetic variants are described when they have a minor allele frequency of <1% or were previously reported as being disease-associated.ResultsIn patients with aHUS (n=94, one also had IC-MPGN) 68 different genetic variants or deletions were identified in 60 patients, of which 18 were novel. Thirty-two patients had more than one genetic variant. In patients with C3G (n=40) 29 genetic variants, deletions or duplications were identified in 15 patients, of which 9 were novel. Eight patients had more than one variant. In patients with IC-MPGN (n=7) five genetic variants were identified in five patients. Factor H variants were the most frequent in aHUS and C3 variants in C3G. Seventeen variants occurred in more than one condition.ConclusionGenetic screening of patients with aHUS, C3G and IC-MPGN is of paramount importance for diagnostics and treatment. In this study, we describe genetic assessment of Nordic patients in which 26 novel variants were found

Mortalidade entre Idosos no Estado do Paraná e no município de Foz do Iguaçu

Trabalho de Conclusão da Residência apresentado ao Programa de Residência Multiprofissional em Saúde da Família da Universidade Federal da Integração Latino- Americana, como requisito parcial para obtenção do título de Especialista em Saúde da Família na modalidade de residência. Orientador: Walfrido Svoboda. (Prof. Dr. do Curso de Saúde Coletiva - UNILA) e Coorientadora: Carmen Justina Gamarra. (Profa. Dra. do Curso de Saúde Coletiva - UNILA)Objetivo: Analisar a tendência da mortalidade entre idosos residentes no estado do Paraná e no município de Foz do Iguaçu, no período de 2001 a 2012, e mortalidade proporcional por capítulos CID-10. Método: Trata-se de um estudo descritivo, ecológico de série temporal. Os dados dos óbitos e da população idosa de 60 anos ou mais foram obtidos por meio do Sistema de Informação de mortalidade SIM/DATASUS. Foram calculadas as taxas anuais de mortalidade bruta e padronizadas por sexo e faixa etária. Para os dados de mortalidade proporcional por capítulos CID-10 foram calculados os percentuais para os anos selecionados de 2001; 2006; 2011; 2016. As informações foram tabuladas em planilhas do Excel, sendo construídas tabelas e gráficos e analisados por meio de regressão linear simples. Resultados: Observou-se tendência declinante da mortalidade dos idosos no estado do Paraná e no município de Foz do Iguaçu. Ao longo do estudo verificou-se que as doenças do aparelho circulatório constituem-se como a primeira e principal causa de óbito, seguido das neoplasias e doenças do aparelho respiratório. Conclusão: No período analisado, a tendência da mortalidade padronizadas dos idosos obteve decréscimo tanto no Estado como no município, sendo observados maiores coeficientes de mortalidade entre os homens quando comparado às mulheres.Objective: To analyze the mortality trend among elderly people living in the state of Para- ná and in the municipality of Foz do Iguaçu, from 2001 to 2012, and proportional mortality by ICD-10 chapters. Method: This is a descriptive, ecological time series study. Data on deaths and the elderly population aged 60 years and over were obtained using the SIM / Datasus Mortality Infor- mation System. Gross annual mortality rates were standardized and standardized by gen- der and age group. The information was tabulated in Excel spreadsheets, and tables and graphs were constructed and analyzed using simple linear regression. Results: In general terms, a declining trend in mortality among the elderly was observed in the state of Paraná and in the city of Foz do Iguaçu. Throughout the study it was verified that diseases of the circulatory system constitute the first and main cause of death, fol- lowed by neoplasias and diseases of the respiratory system. Conclusion: In the period analyzed, the general trend of standardized mortality among the elderly decreased both in the state and in the municipality, with higher mortality rates among men when compared to womenObjetivo: Analizar la tendencia de la mortalidad entre ancianos residentes en el estado de Paraná y en el municipio de Foz do Iguaçu, en el período de 2001 a 2012, y mortali- dad proporcional por capítulos CID-10. Método: Se trata de un estudio descriptivo, eco- lógico de serie temporal. Los datos de mortalidad y de la población de la tercera edad (mayor de 60años) fueron obtenidos por medio del sistema de información de mortalidad SIM/DATASUS. Fueron calculadas las tasas anuales de mortalidad bruta y estandariza- das por sexo y edad. Las informaciones fueron tabuladas en planillas de cálculo Micro- soft Excel, siendo construidas tablas, gráficos e analizados por medio de regresión linear simple. Resultados: En términos generales fue observada la tendencia declinante de la mortali- dad en personas de la tercera edad en el Estado de Paraná y en el Municipio de Foz de Iguazú. A lo largo de este estudio, se verifico que las enfermedades del aparato circula- torio se consideran como la primera causa de muerte, seguido por Cáncer e enfermeda- des del Aparato Respiratorio. Conclusión: En el periodo analizado, la tendencia de la mortalidad estandarizada en personas de la tercera edad obtuvo decrecimos tanto en el Estado de Paraná como en el Municipio, siendo observados mayores coeficientes de mortalidad en hombres compara- do con mujere

A Novel Mechanism of Bacterial Toxin Transfer within Host Blood Cell-Derived Microvesicles.

Shiga toxin (Stx) is the main virulence factor of enterohemorrhagic Escherichia coli, which are non-invasive strains that can lead to hemolytic uremic syndrome (HUS), associated with renal failure and death. Although bacteremia does not occur, bacterial virulence factors gain access to the circulation and are thereafter presumed to cause target organ damage. Stx was previously shown to circulate bound to blood cells but the mechanism by which it would potentially transfer to target organ cells has not been elucidated. Here we show that blood cell-derived microvesicles, shed during HUS, contain Stx and are found within patient renal cortical cells. The finding was reproduced in mice infected with Stx-producing Escherichia coli exhibiting Stx-containing blood cell-derived microvesicles in the circulation that reached the kidney where they were transferred into glomerular and peritubular capillary endothelial cells and further through their basement membranes followed by podocytes and tubular epithelial cells, respectively. In vitro studies demonstrated that blood cell-derived microvesicles containing Stx undergo endocytosis in glomerular endothelial cells leading to cell death secondary to inhibited protein synthesis. This study demonstrates a novel virulence mechanism whereby bacterial toxin is transferred within host blood cell-derived microvesicles in which it may evade the host immune system

Factor D Inhibition Blocks Complement Activation Induced by Mutant Factor B Associated With Atypical Hemolytic Uremic Syndrome and Membranoproliferative Glomerulonephritis

Funding Information: The authors wish to thank Dr Marina Noris and Dr Roberta Donadelli, Istituto di Ricerche Farmacologiche Mario Negri, Bergamo Italy for excellent technical advice for the assay of factor B cleavage by the C3 convertase. Dr Ravi Bhongir and Dr Sandra Jovic, Infection Medicine, Clinical Sciences Lund are acknowledged for their help with the surface plasmon resonance assays. The authors thank Drs Markus Heidenblad, Sofia Saal and Bj?rn Hallstr?m of the Center for Molecular Diagnostics, Region Sk?ne and Clinical Genomics Lund, SciLifeLab, Lund University for next-generation sequencing. Dr Henning Gong carried out part of the mutagenesis study as part of his master?s thesis. The kidney biopsies of Patient 3 were assessed by Dr. Melinda Raki, Department of Pathology, Oslo University Hospital, Oslo Norway, Dr. Sabine Leh, Department of Pathology, Haukeland Univeristy Hospital Bergen, Norway, Professor Sanjeev Sethi and Professor Fernando Fervenza of the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota. This work was presented in preliminary poster form at the17th Congress of the International Pediatric Nephrology Association, Iguacu Brazil, September 20-24, 2016, at the 6th International Conference ?HUS & related diseases?, Innsbruck, Austria, June 11-13, 2017, the 16th European Meeting of Complement in Human Disease, Copenhagen, Denmark, September 8-12, 2017, the 18th Congress of the International Pediatric Nephrology Association, Venice, Italy October 17-21, 2019. Publisher Copyright: © Copyright © 2021 Aradottir, Kristoffersson, Roumenina, Bjerre, Kashioulis, Palsson and Karpman.Complement factor B (FB) mutant variants are associated with excessive complement activation in kidney diseases such as atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathy and membranoproliferative glomerulonephritis (MPGN). Patients with aHUS are currently treated with eculizumab while there is no specific treatment for other complement-mediated renal diseases. In this study the phenotype of three FB missense variants, detected in patients with aHUS (D371G and E601K) and MPGN (I242L), was investigated. Patient sera with the D371G and I242L mutations induced hemolysis of sheep erythrocytes. Mutagenesis was performed to study the effect of factor D (FD) inhibition on C3 convertase-induced FB cleavage, complement-mediated hemolysis, and the release of soluble C5b-9 from glomerular endothelial cells. The FD inhibitor danicopan abrogated C3 convertase-associated FB cleavage to the Bb fragment in patient serum, and of the FB constructs, D371G, E601K, I242L, the gain-of-function mutation D279G, and the wild-type construct, in FB-depleted serum. Furthermore, the FD-inhibitor blocked hemolysis induced by the D371G and D279G gain-of-function mutants. In FB-depleted serum the D371G and D279G mutants induced release of C5b-9 from glomerular endothelial cells that was reduced by the FD-inhibitor. These results suggest that FD inhibition can effectively block complement overactivation induced by FB gain-of-function mutations.Peer reviewe

Phenotypic Expression of ADAMTS13 in Glomerular Endothelial Cells

Background: ADAMTS13 is the physiological von Willebrand factor (VWF)-cleaving protease. The aim of this study was to examine ADAMTS13 expression in kidneys from ADAMTS13 wild-type (Adamts13+/+) and deficient (Adamts13-/-) mice and to investigate the expression pattern and bioactivity in human glomerular endothelial cells. Methodology/Principal Findings: Immunohistochemistry was performed on kidney sections from ADAMTS13 wild-type and ADAMTS13-deficient mice. Phenotypic differences were examined by ultramorphology. ADAMTS13 expression in human glomerular endothelial cells and dermal microvascular endothelial cells was investigated by real-time PCR, flow cytometry, immunofluorescence and immunoblotting. VWF cleavage was demonstrated by multimer structure analysis and immunoblotting. ADAMTS13 was demonstrated in glomerular endothelial cells in Adamts13+/+ mice but no staining was visible in tissue from Adamts13-/- mice. Thickening of glomerular capillaries with platelet deposition on the vessel wall was detected in Adamts13-/- mice. ADAMTS13 mRNA and protein were detected in both human endothelial cells and the protease was secreted. ADAMTS13 activity was demonstrated in glomerular endothelial cells as cleavage of VWF. Conclusions/Significance: Glomerular endothelial cells express and secrete ADAMTS13. The proteolytic activity could have a protective effect preventing deposition of platelets along capillary lumina under the conditions of high shear stress present in glomerular capillaries. © 2011 Tati et al.published_or_final_versio

Characterization of a novel mutation in the von Willebrand factor propeptide in a distinct subtype of recessive von Willebrand disease

von Willebrand factor (VWF) is a plasma protein that consists of a series of multimers of which the high-molecular-weight VWF multimers are the most potent in platelet adhesion and aggregation. The propeptide of the VWF (VWFpp) is known to be essential in the process of multimer assembly. Genetic studies were performed in a patient with a phenotype of von Willebrand disease (VWD) characterized by very low plasma factor VIII and VWF levels and a VWF consisting of only a dimeric band and total absence of all multimers in plasma. The patient was found to be homozygous for the novel C570S mutation, caused by a 1709G>C transition in exon 14 of the VWF gene coding for the propeptide. Three asymptomatic relatives were found to be heterozygous. In-vitro mutagenesis and expression in COS-7 cells confirmed the detrimental effect of the mutation on VWF multimerization. Our findings show that the C570S mutation in the VWFpp abolishes multimerization of VWF. The mutation probably disrupts the normal configuration of the VWFpp, which is essential for correct orientation of the protomers and ultimately multimerization. The mutant amino acid is located in a region that is highly conserved across several species which underlines its critical role. This variant constitutes a distinct subtype of recessive 2A VWD with the exclusive presence of the dimeric form of VWF in plasma

IgA nephropathy associated with a novel N-terminal mutation in factor H.

Most patients with IgA nephropathy exhibit complement deposition in the glomerular mesangium. Certain cases of IgA nephropathy have been associated with reduced levels of complement factor H. A recent study could not demonstrate mutations at the C-terminal of factor H. We describe a novel heterozygous mutation in factor H, position A48S (nucleotide position 142 G > T, alanine > serine), detected in exon 2 of a 14-year-old girl with IgA nephropathy. The patient exhibited reduced levels of C3 and factor H, the latter suggesting that the mutation affected factor H secretion. The patient developed initial signs and symptoms of glomerulonephritis at the age of 9 years but presented again at the age of 14 years with weight gain, renal failure, nephrotic-range proteinuria and malignant hypertension. Blood tests suggested the development of microangiopathic hemolytic anemia (MAHA) but the renal biopsy was mostly indicative of chronic changes associated with IgA nephropathy as well as vascular changes associated with malignant hypertension. Immunofluorescence exhibited deposits of IgA, C3, and IgM. Screening of the factor H gene revealed, in addition to the mutation, three heterozygous hemolytic uremic syndrome -associated risk polymorphisms (-257 c/t, 2089 a/g, and 2881 g/t) which may have increased the patient's susceptibility to the occurrence of MAHA triggered by malignant hypertension. The combined clinical picture of IgA nephropathy and MAHA may have been partly related to the alterations in factor H