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Stevens KH, Baas LM, van der Velden TJAM, Bouwmeester RN, van Dillen N, Dorresteijn EM, van Zuilen AD, Wetzels JFM, Michels MAHM, van de Kar NCAJ, van den Heuvel LP. Modeling complement activation on human glomerular microvascular endothelial cells. Front Immunol 2023; 14:1206409. [PMID: 37954621 PMCID: PMC10634509 DOI: 10.3389/fimmu.2023.1206409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 10/03/2023] [Indexed: 11/14/2023] Open
Abstract
Introduction Atypical hemolytic uremic syndrome (aHUS) is a rare kidney disease caused by dysregulation of the complement alternative pathway. The complement dysregulation specifically leads to damage to the glomerular endothelium. To further understand aHUS pathophysiology, we validated an ex vivo model for measuring complement deposition on both control and patient human glomerular microvascular endothelial cells (GMVECs). Methods Endothelial cells were incubated with human test sera and stained with an anti-C5b-9 antibody to visualize and quantify complement depositions on the cells with immunofluorescence microscopy. Results First, we showed that zymosan-activated sera resulted in increased endothelial C5b-9 depositions compared to normal human serum (NHS). The levels of C5b-9 depositions were similar between conditionally immortalized (ci)GMVECs and primary control GMVECs. The protocol with ciGMVECs was further validated and we additionally generated ciGMVECs from an aHUS patient. The increased C5b-9 deposition on control ciGMVECs by zymosan-activated serum could be dose-dependently inhibited by adding the C5 inhibitor eculizumab. Next, sera from five aHUS patients were tested on control ciGMVECs. Sera from acute disease phases of all patients showed increased endothelial C5b-9 deposition levels compared to NHS. The remission samples showed normalized C5b-9 depositions, whether remission was reached with or without complement blockage by eculizumab. We also monitored the glomerular endothelial complement deposition of an aHUS patient with a hybrid complement factor H (CFH)/CFH-related 1 gene during follow-up. This patient had already chronic kidney failure and an ongoing deterioration of kidney function despite absence of markers indicating an aHUS flare. Increased C5b-9 depositions on ciGMVECs were observed in all samples obtained throughout different diseases phases, except for the samples with eculizumab levels above target. We then tested the samples on the patient's own ciGMVECs. The C5b-9 deposition pattern was comparable and these aHUS patient ciGMVECs also responded similar to NHS as control ciGMVECs. Discussion In conclusion, we demonstrate a robust and reliable model to adequately measure C5b-9-based complement deposition on human control and patient ciGMVECs. This model can be used to study the pathophysiological mechanisms of aHUS or other diseases associated with endothelial complement activation ex vivo.
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Affiliation(s)
- Kes H. Stevens
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Laura M. Baas
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Thea J. A. M. van der Velden
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Romy N. Bouwmeester
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Niels van Dillen
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Eiske M. Dorresteijn
- Department of Pediatric Nephrology, Sophia Children’s Hospital, Erasmus Medical Center, Rotterdam, Netherlands
| | - Arjan D. van Zuilen
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - Jack F. M. Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Marloes A. H. M. Michels
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Nicole C. A. J. van de Kar
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Lambertus P. van den Heuvel
- Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Pediatrics/Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
- Department of Development and Regeneration, University Hospitals Leuven, Leuven, Belgium
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2
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Turudic D, Pokrajac D, Tasic V, Kasumovic D, Prohaszka Z, Milosevic D. The Rationale of Complement Blockade of the MCP ggaac Haplotype following Atypical Hemolytic Uremic Syndrome of Three Southeastern European Countries with a Literature Review. Int J Mol Sci 2023; 24:13041. [PMID: 37685848 PMCID: PMC10487996 DOI: 10.3390/ijms241713041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/10/2023] [Accepted: 08/16/2023] [Indexed: 09/10/2023] Open
Abstract
We present eight cases of the homozygous MCPggaac haplotype, which is considered to increase the likelihood and severity of atypical hemolytic uremic syndrome (aHUS), especially in combination with additional risk aHUS mutations. Complement blockade (CBT) was applied at a median age of 92 months (IQR 36-252 months). The median number of relapses before CBT initiation (Eculizumab) was two. Relapses occurred within an average of 22.16 months (median 17.5, minimum 8 months, and maximum 48 months) from the first subsequent onset of the disease (6/8 patients). All cases were treated with PI/PEX, and rarely with renal replacement therapy (RRT). When complement blockade was applied, children had no further disease relapses. Children with MCPggaac haplotype with/without additional gene mutations can achieve remission through renal replacement therapy without an immediate need for complement blockade. If relapse of aHUS occurs soon after disease onset or relapses are repeated frequently, a permanent complement blockade is required. However, the duration of such a blockade remains uncertain. If complement inhibition is not applied within 4-5 relapses, proteinuria and chronic renal failure will eventually occur.
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Affiliation(s)
- Daniel Turudic
- Department of Pediatrics, University Hospital Centre Zagreb, Kispaticeva 12, 10000 Zagreb, Croatia
| | - Danka Pokrajac
- Pediatric Clinic, Clinical Center, University of Sarajevo, Patriotske Lige 81, 71000 Sarajevo, Bosnia and Herzegovina;
| | - Velibor Tasic
- Medical Faculty Skopje, University Children’s Hospital, 1010 Skopje, North Macedonia;
| | - Dino Kasumovic
- Department of Nephrology and Dialysis, Dubrava University Hospital, School of Medicine, University of Zagreb, 10000 Zagreb, Croatia;
| | - Zoltan Prohaszka
- Department of Internal Medicine and Hematology, Semmelweis University, 1085 Budapest, Hungary;
- Research Group for Immunology and Haematology, Eotvos Lorand Research Network (Office for Supported Research Groups), Semmelweis University, 1085 Budapest, Hungary
| | - Danko Milosevic
- Croatian Academy of Medical Sciences, Kaptol ul. 15, 10000 Zagreb, Croatia;
- Department of Pediatrics, Zabok General Hospital, and the Croatian Veterans Hospital, Bračak 8, 49210 Bračak, Croatia
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3
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Claes KJ, Geerts I, Lemahieu W, Wilmer A, Kuypers DRJ, Koshy P, Ombelet S. Atypical Hemolytic Uremic Syndrome Occurring After Receipt of mRNA-1273 COVID-19 Vaccine Booster: A Case Report. Am J Kidney Dis 2023; 81:364-367. [PMID: 36342000 PMCID: PMC9484133 DOI: 10.1053/j.ajkd.2022.07.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 07/22/2022] [Indexed: 02/08/2023]
Abstract
Atypical hemolytic uremic syndrome (aHUS) is a subtype of thrombotic microangiopathy (TMA) characterized by a dysregulation of the alternative complement pathway. Here, we report a previously healthy 38-year-old woman in whom aHUS developed after a COVID-19 vaccine booster. One day after receipt of a booster dose of mRNA-1273 vaccine, she felt ill. Because of persistent headache, nausea, and general malaise, she went to her general practitioner, who referred her to the hospital after detecting hypertension and acute kidney injury. A diagnosis of TMA was made. Her treatment consisted of blood pressure control, hemodialysis, plasma exchange, and respiratory support. Kidney biopsy confirmed the diagnosis of acute TMA. The patient was referred for treatment with eculizumab, and kidney function improved after initiation of this therapy. Genetic analysis revealed a pathogenic C3 variant. SARS-CoV-2 infection as a trigger for complement activation and development of aHUS has been described previously. In addition, there is one reported case of aHUS occurring after receipt of the adenovirus-based COVID-19 vaccine ChAdOx1 nCoV-19, but, to our knowledge, this is the first case of aHUS occurring after a booster dose of an mRNA COVID-19 vaccine in a patient with an underlying pathogenic variant in complement C3. Given the time frame, we hypothesize that the vaccine probably was the trigger for development of aHUS in this patient.
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Affiliation(s)
- Kathleen J Claes
- Department of Microbiology, Immunology and Transplantation, Nephrology and Renal Transplantation Research Group, KU Leuven, Leuven, Belgium; Department of Nephrology and Renal Transplantation, UZ Leuven, Leuven, Belgium.
| | - Inge Geerts
- Departments of Laboratory Medicine, Imelda Hospital, Bonheiden, Belgium
| | - Wim Lemahieu
- Department of Nephrology, Imelda Hospital, Bonheiden, Belgium
| | - Alexander Wilmer
- Department of Microbiology, Immunology and Transplantation, Laboratory for Clinical Infectious and Inflammatory Disorders, KU Leuven, Leuven, Belgium; Department of General Internal Medicine, Medical Intensive Care Unit, UZ Leuven, Leuven, Belgium
| | - Dirk R J Kuypers
- Department of Microbiology, Immunology and Transplantation, Nephrology and Renal Transplantation Research Group, KU Leuven, Leuven, Belgium; Department of Nephrology and Renal Transplantation, UZ Leuven, Leuven, Belgium
| | | | - Sara Ombelet
- Department of Nephrology, Imelda Hospital, Bonheiden, Belgium
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Rodríguez de Córdoba S. Genetic variability shapes the alternative pathway complement activity and predisposition to complement-related diseases. Immunol Rev 2023; 313:71-90. [PMID: 36089777 PMCID: PMC10086816 DOI: 10.1111/imr.13131] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The implementation of next-generation sequencing technologies has provided a sharp picture of the genetic variability in the components and regulators of the alternative pathway (AP) of the complement system and has revealed the association of many AP variants with different rare and common diseases. An important finding that has emerged from these analyses is that each of these complement-related diseases associate with genetic variants altering specific aspects of the activation and regulation of the AP. These genotype-phenotype correlations have provided valuable insights into their pathogenic mechanisms with important diagnostic and therapeutic implications. While genetic variants in coding regions and structural variants are reasonably well characterized and occasionally have been instrumental to uncover unknown features of the complement proteins, data about complement expressed quantitative trait loci are still very limited. A crucial task for future studies will be to identify these quantitative variations and to determine their impact in the overall activity of the AP. This is fundamental as it is now clear that the consequences of genetic variants in the AP are additive and that susceptibility or resistance to disease is the result of specific combinations of genetic variants in different complement components and regulators ("complotypes").
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5
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Raina R, Sethi SK, Dragon-Durey MA, Khooblall A, Sharma D, Khandelwal P, Shapiro R, Boyer O, Yap HK, Bagga A, Licht C. Systematic review of atypical hemolytic uremic syndrome biomarkers. Pediatr Nephrol 2022; 37:1479-1493. [PMID: 35118546 DOI: 10.1007/s00467-022-05451-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND OBJECTIVES Observing biomarkers that affect alternative pathway dysregulation components may be effective in obtaining a new and more rapid diagnostic portrayal of atypical hemolytic uremic syndrome. We have conducted a systematic review on the aHUS biomarkers: C3, C5a, C5b-9, factor B, complement factor B, H, and I, CH50, AH50, D-dimer, as well as anti-CFH antibodies. METHODS An exhaustive literature search was conducted for aHUS patient population plasma/serum, collected/reported at the onset of diagnosis. A total of 60 studies were included with the data on 837 aHUS subjects, with at least one biomarker reported. RESULTS The biomarkers C3 [mean (SD): 72.1 (35.0), median: 70.5 vs. reference range: 75-175 mg/dl, n = 752]; CH50 [28.3 (32.1), 24.3 vs. 30-75 U/ml, n = 63]; AH50 [27.6% (30.2%), 10% vs. ≥ 46%, n = 23]; and CFB [13.1 (6.6), 12.4, vs. 15.2-42.3 mg/dl, n = 19] were lower among aHUS subjects as compared with the reference range. The biomarkers including C4 [mean (SD): 20.4 (9.5), median: 20.5 vs. reference range: 14-40 mg/dl, n = 343]; C4d [7.2 (6.5), 4.8 vs. ≤ 9.8 μg/ml, n = 108]; CFH [40.2 (132.3), 24.5 vs. 23.6-43.1 mg/dl, n = 123 subjects]; and CFI [8.05 (5.01), 6.55 mg/dl vs. 4.4-18.1 mg/dl, n = 38] were all observed to be within the reference range among aHUS subjects. The biomarkers C5a [mean (SD): 54.9 (32.9), median: 48.8 vs. reference range: 10.6-26.3 mg/dl, n = 117]; C5b-9 [466.0 (401.4), 317 (186-569.7) vs. ≤ 250 ng/ml, n = 174]; Bb [2.6 (2.1), 1.9 vs. ≤ 1.6 μg/ml, n = 77] and D-dimer [246 (65.05), 246 vs. < 2.2 ng/ml, 2, n = 2 subjects] were higher among patients with aHUS compared with the reference range. CONCLUSION If a comprehensive complement profile were built using our data, aHUS would be identified by low levels of C3, CH50, AH50, and CFB along with increased levels of C5a, C5b-9, Bb, anti-CFH autoantibodies, and D-dimer. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Rupesh Raina
- Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, OH, USA. .,Department of Nephrology, Akron Children's Hospital, Akron, OH, USA.
| | - Sidharth K Sethi
- Kidney and Renal Transplant Institute, Medanta, The Medicity Hospital, Gurgaon, Haryana, India
| | | | - Amrit Khooblall
- Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, OH, USA.,Department of Nephrology, Akron Children's Hospital, Akron, OH, USA
| | - Divya Sharma
- Department of Medicine, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Priyanka Khandelwal
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India
| | | | - Olivia Boyer
- Service de Néphrologie Pédiatrique, AP-HP, Centre de Référence de maladies rénales rares de l'enfant et de l'adulte (MARHEA), Hôpital Necker - Enfants Malades, 149 Rue de Sèvres, 75015, Paris, France.,Institut Imagine, Laboratoire des maladies rénales héréditaires, INSERM UMR 1163, Université de Paris, Paris, France
| | - Hui Kim Yap
- Shaw-NKF-NUH Children's Kidney Centre, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, Kent Ridge, Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Arvind Bagga
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Christoph Licht
- Cell Biology Program, SickKids Research Institute, Toronto, ON, Canada.,Department of Paediatrics, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Division of Nephrology, The Hospital for Sick Children, Toronto, ON, Canada
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Zhang Y, Goodfellow RX, Ghiringhelli Borsa N, Dunlop HC, Presti SA, Meyer NC, Shao D, Roberts SM, Jones MB, Pitcher GR, Taylor AO, Nester CM, Smith RJH. Complement Factor I Variants in Complement-Mediated Renal Diseases. Front Immunol 2022; 13:866330. [PMID: 35619721 PMCID: PMC9127439 DOI: 10.3389/fimmu.2022.866330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/08/2022] [Indexed: 11/26/2022] Open
Abstract
C3 glomerulopathy (C3G) and atypical hemolytic uremic syndrome (aHUS) are two rare diseases caused by dysregulated activity of the alternative pathway of complement secondary to the presence of genetic and/or acquired factors. Complement factor I (FI) is a serine protease that downregulates complement activity in the fluid phase and/or on cell surfaces in conjunction with one of its cofactors, factor H (FH), complement receptor 1 (CR1/CD35), C4 binding protein (C4BP) or membrane cofactor protein (MCP/CD46). Because altered FI activity is causally related to the pathogenesis of C3G and aHUS, we sought to test functional activity of select CFI missense variants in these two patient cohorts. We identified 65 patients (16, C3G; 48, aHUS; 1 with both) with at least one rare variant in CFI (defined as a MAF < 0.1%). Eight C3G and eleven aHUS patients also carried rare variants in either another complement gene, ADAMTS13 or THBD. We performed comprehensive complement analyses including biomarker profiling, pathway activity and autoantibody testing, and developed a novel FI functional assay, which we completed on 40 patients. Seventy-eight percent of rare CFI variants (31/40) were associated with FI protein levels below the 25th percentile; in 22 cases, FI levels were below the lower limit of normal (type 1 variants). Of the remaining nine variants, which associated with normal FI levels, two variants reduced FI activity (type 2 variants). No patients carried currently known autoantibodies (including FH autoantibodies and nephritic factors). We noted that while rare variants in CFI predispose to complement-mediated diseases, phenotypes are strongly contingent on the associated genetic background. As a general rule, in isolation, a rare CFI variant most frequently leads to aHUS, with the co-inheritance of a CD46 loss-of-function variant driving the onset of aHUS to the younger age group. In comparison, co-inheritance of a gain-of-function variant in C3 alters the phenotype to C3G. Defects in CFH (variants or fusion genes) are seen with both C3G and aHUS. This variability underscores the complexity and multifactorial nature of these two complement-mediated renal diseases.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Richard J. H. Smith
- Molecular Otolaryngology and Renal Research Laboratories, University of Iowa, Iowa City, IA, United States
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Pollack S, Eisenstein I, Mory A, Paperna T, Ofir A, Baris-Feldman H, Weiss K, Veszeli N, Csuka D, Shemer R, Glaser F, Prohászka Z, Magen D. A Novel Homozygous In-Frame Deletion in Complement Factor 3 Underlies Early-Onset Autosomal Recessive Atypical Hemolytic Uremic Syndrome - Case Report. Front Immunol 2021; 12:608604. [PMID: 34248927 PMCID: PMC8264753 DOI: 10.3389/fimmu.2021.608604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 05/24/2021] [Indexed: 11/21/2022] Open
Abstract
Background and Objectives Atypical hemolytic uremic syndrome (aHUS) is mostly attributed to dysregulation of the alternative complement pathway (ACP) secondary to disease-causing variants in complement components or regulatory proteins. Hereditary aHUS due to C3 disruption is rare, usually caused by heterozygous activating mutations in the C3 gene, and transmitted as autosomal dominant traits. We studied the molecular basis of early-onset aHUS, associated with an unusual finding of a novel homozygous activating deletion in C3. Design, Setting, Participants, & Measurements A male neonate with eculizumab-responsive fulminant aHUS and C3 hypocomplementemia, and six of his healthy close relatives were investigated. Genetic analysis on genomic DNA was performed by exome sequencing of the patient, followed by targeted Sanger sequencing for variant detection in his close relatives. Complement components analysis using specific immunoassays was performed on frozen plasma samples from the patient and mother. Results Exome sequencing revealed a novel homozygous variant in exon 26 of C3 (c.3322_3333del, p.Ile1108_Lys1111del), within the highly conserved thioester-containing domain (TED), fully segregating with the familial disease phenotype, as compatible with autosomal recessive inheritance. Complement profiling of the patient showed decreased C3 and FB levels, with elevated levels of the terminal membrane attack complex, while his healthy heterozygous mother showed intermediate levels of C3 consumption. Conclusions Our findings represent the first description of aHUS secondary to a novel homozygous deletion in C3 with ensuing unbalanced C3 over-activation, highlighting a critical role for the disrupted C3-TED domain in the disease mechanism.
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Affiliation(s)
- Shirley Pollack
- Pediatric Nephrology Institute, Ruth Children's Hospital, Haifa, Israel.,Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Israel Eisenstein
- Pediatric Nephrology Institute, Ruth Children's Hospital, Haifa, Israel
| | - Adi Mory
- Genetic Institute, Haifa, Israel
| | | | | | | | | | - Nóra Veszeli
- Research Laboratory, Department of Internal Medicine and Haematology, and MTA-SE Research Group of Immunology and Hematology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - Dorottya Csuka
- Research Laboratory, Department of Internal Medicine and Haematology, and MTA-SE Research Group of Immunology and Hematology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - Revital Shemer
- Laboratory of Molecular Medicine, Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Fabian Glaser
- Bioinformatics Knowledge Unit, The Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Zoltán Prohászka
- Research Laboratory, Department of Internal Medicine and Haematology, and MTA-SE Research Group of Immunology and Hematology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - Daniella Magen
- Pediatric Nephrology Institute, Ruth Children's Hospital, Haifa, Israel.,Laboratory of Molecular Medicine, Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
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Arjona E, Huerta A, Goicoechea de Jorge E, Rodríguez de Córdoba S. Familial risk of developing atypical hemolytic-uremic syndrome. Blood 2020; 136:1558-61. [PMID: 32488248 DOI: 10.1182/blood.2020006931] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 11/20/2022] Open
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Lumbreras J, Subias M, Espinosa N, Ferrer JM, Arjona E, Rodríguez de Córdoba S. The Relevance of the MCP Risk Polymorphism to the Outcome of aHUS Associated With C3 Mutations. A Case Report. Front Immunol 2020; 11:1348. [PMID: 32765494 PMCID: PMC7381106 DOI: 10.3389/fimmu.2020.01348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 05/27/2020] [Indexed: 11/18/2022] Open
Abstract
Thrombotic microangiopathy (TMA) has different etiological causes, and not all of them are well understood. In atypical hemolytic uremic syndrome (aHUS), the TMA is caused by the complement dysregulation associated with pathogenic mutations in complement components and its regulators. Here, we describe a pediatric patient with aHUS in whom the relatively benign course of the disease confused the initial diagnosis. A previously healthy 8-year-old boy developed jaundice, hematuria, hemolytic anemia, thrombopenia, and mild acute kidney injury (AKI) in the context of a diarrhea without hypertension nor oliguria. Spontaneous and complete recovery was observed from the third day of admission. Persistent low C3 plasma levels after recovery raised the suspicion for aHUS, which prompted clinicians to discard the initial diagnosis of Shigatoxin-associated HUS (STEC-HUS). A thorough genetic and molecular study of the complement revealed the presence of an isolated novel pathogenic C3 mutation. The relatively benign clinical course of the disease as well as the finding of a de novo pathogenic C3 mutation are remarkable aspects of this case. The data are discussed to illustrate the benefits of identifying the TMA etiological factor and the relevant contribution of the MCP aHUS risk polymorphism to the disease severity.
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Affiliation(s)
- Javier Lumbreras
- Unidad de Nefrología Infantil, Servicio de Pediatría, Hospital Universitari Son Espases-Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Marta Subias
- Centro de Investigaciones Biológicas Margarita Salas and Ciber de Enfermedades Raras, Madrid, Spain
| | - Natalia Espinosa
- Unidad de Nefrología Infantil, Servicio de Pediatría, Hospital Universitari Son Espases-Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Juana María Ferrer
- Servicio de Inmunología, Hospital Universitari Son Espases-Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Emilia Arjona
- Centro de Investigaciones Biológicas Margarita Salas and Ciber de Enfermedades Raras, Madrid, Spain
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10
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Ellithi M, Shahid M, Abdullah HM, Bleeker J. Complement C3 mutation causing atypical hemolytic uremic syndrome successfully treated with eculizumab. Hematol Transfus Cell Ther 2020; 43:364-367. [PMID: 32265146 PMCID: PMC8446228 DOI: 10.1016/j.htct.2020.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/25/2019] [Accepted: 02/04/2020] [Indexed: 12/05/2022] Open
Affiliation(s)
- Moataz Ellithi
- University of South Dakota, Sanford School of Medicine, Sioux Falls, United States.
| | - Mahum Shahid
- University of South Dakota, Sanford School of Medicine, Sioux Falls, United States
| | | | - Jonathan Bleeker
- University of South Dakota, Sanford School of Medicine, Sioux Falls, United States
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11
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Ojha H, Ghosh P, Singh Panwar H, Shende R, Gondane A, Mande SC, Sahu A. Spatially conserved motifs in complement control protein domains determine functionality in regulators of complement activation-family proteins. Commun Biol 2019; 2:290. [PMID: 31396570 PMCID: PMC6683126 DOI: 10.1038/s42003-019-0529-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022] Open
Abstract
Regulation of complement activation in the host cells is mediated primarily by the regulators of complement activation (RCA) family proteins that are formed by tandemly repeating complement control protein (CCP) domains. Functional annotation of these proteins, however, is challenging as contiguous CCP domains are found in proteins with varied functions. Here, by employing an in silico approach, we identify five motifs which are conserved spatially in a specific order in the regulatory CCP domains of known RCA proteins. We report that the presence of these motifs in a specific pattern is sufficient to annotate regulatory domains in RCA proteins. We show that incorporation of the lost motif in the fourth long-homologous repeat (LHR-D) in complement receptor 1 regains its regulatory activity. Additionally, the motif pattern also helped annotate human polydom as a complement regulator. Thus, we propose that the motifs identified here are the determinants of functionality in RCA proteins.
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Affiliation(s)
- Hina Ojha
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
| | - Payel Ghosh
- Bioinformatics Centre, S. P. Pune University, Pune, 411007 India
| | - Hemendra Singh Panwar
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
| | - Rajashri Shende
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
| | | | - Shekhar C. Mande
- Structural Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
- Present Address: Council of Scientific and Industrial Research (CSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi, 110001 India
| | - Arvind Sahu
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
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12
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Panwar HS, Ojha H, Ghosh P, Barage SH, Raut S, Sahu A. Molecular engineering of an efficient four-domain DAF-MCP chimera reveals the presence of functional modularity in RCA proteins. Proc Natl Acad Sci U S A 2019; 116:9953-8. [PMID: 31036650 DOI: 10.1073/pnas.1818573116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The complement system is highly efficient in targeting pathogens, but lack of its apposite regulation results in host-cell damage, which is linked to diseases. Thus, complement activation is tightly regulated by a series of proteins, which primarily belong to the regulators of complement activation (RCA) family. Structurally, these proteins are composed of repeating complement control protein (CCP) domains where two to four successive domains contribute to the regulatory functions termed decay-accelerating activity (DAA) and cofactor activity (CFA). However, the precise constitution of the functional units and whether these units can be joined to form a larger composition with dual function have not been demonstrated. Herein, we have parsed the functional units for DAA and CFA by constructing chimeras of the decay-accelerating factor (DAF) that exhibits DAA and membrane cofactor protein (MCP) that exhibits CFA. We show that in a four-CCP framework, a functional unit for each of the regulatory activities is formed by only two successive CCPs wherein each participates in the function, albeit CCP2 has a bipartite function. Additionally, optimal activity requires C-terminal domains that enhance the avidity of the molecule for C3b/C4b. Furthermore, by composing a four-CCP DAF-MCP chimera with robust CFA (for C3b and C4b) and DAA (for classical and alternative pathway C3 convertases), named decay cofactor protein, we show that CCP functional units can be linked to design a dual-activity regulator. These data indicate that the regulatory determinants for these two biological processes are distinct and modular in nature.
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13
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Ma Y, Liu Y, Zhang Z, Yang GY. Significance of Complement System in Ischemic Stroke: A Comprehensive Review. Aging Dis 2019; 10:429-462. [PMID: 31011487 PMCID: PMC6457046 DOI: 10.14336/ad.2019.0119] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/19/2019] [Indexed: 12/14/2022] Open
Abstract
The complement system is an essential part of innate immunity, typically conferring protection via eliminating pathogens and accumulating debris. However, the defensive function of the complement system can exacerbate immune, inflammatory, and degenerative responses in various pathological conditions. Cumulative evidence indicates that the complement system plays a critical role in the pathogenesis of ischemic brain injury, as the depletion of certain complement components or the inhibition of complement activation could reduce ischemic brain injury. Although multiple candidates modulating or inhibiting complement activation show massive potential for the treatment of ischemic stroke, the clinical availability of complement inhibitors remains limited. The complement system is also involved in neural plasticity and neurogenesis during cerebral ischemia. Thus, unexpected side effects could be induced if the systemic complement system is inhibited. In this review, we highlighted the recent concepts and discoveries of the roles of different kinds of complement components, such as C3a, C5a, and their receptors, in both normal brain physiology and the pathophysiology of brain ischemia. In addition, we comprehensively reviewed the current development of complement-targeted therapy for ischemic stroke and discussed the challenges of bringing these therapies into the clinic. The design of future experiments was also discussed to better characterize the role of complement in both tissue injury and recovery after cerebral ischemia. More studies are needed to elucidate the molecular and cellular mechanisms of how complement components exert their functions in different stages of ischemic stroke to optimize the intervention of targeting the complement system.
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Affiliation(s)
- Yuanyuan Ma
- 1Department of Neurology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,2Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yanqun Liu
- 3Department of Neurology, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Zhijun Zhang
- 2Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Guo-Yuan Yang
- 1Department of Neurology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,2Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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14
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Abstract
Atypical hemolytic uremic syndrome (aHUS) is a type of thrombotic microangiopathy (TMA) defined by thrombocytopenia, microangiopathic hemolytic anemia, and renal failure. aHUS is caused by uncontrolled complement activation in the alternative pathway (AP). A variety of genetic defects in complement-related factors or acquired autoantibodies to the complement regulators have been found in 50 to 60% of all cases. Recently, however, the classification and diagnosis of aHUS are becoming more complicated. One reason for this is that some factors, which have not been regarded as complement-related factors, have been reported as predisposing factors for phenotypic aHUS. Given that genotype is highly correlated with the phenotype of aHUS, careful analysis of underlying genetic abnormalities or acquired factors is needed to predict the prognosis or to decide an optimal treatment for the disease. Another reason is that complement dysregulation in the AP have also been found in a part of other types of TMA such as transplantation-related TMA and pregnancy-related complication. Based on these findings, it is now time to redefine aHUS according to the genetic or acquired background of abnormalities.Here, we review the pathogeneses and the corresponding phenotypes of aHUS and complement-related TMAs.
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Affiliation(s)
- Yoko Yoshida
- Division of Nephrology and Endocrinology, the University of Tokyo Hospital
| | - Hideki Kato
- Department of Prevention of Diabetes and Lifestyle-Related Diseases Graduate School of Medicine, the University of Tokyo
| | - Yoichiro Ikeda
- Division of Nephrology and Endocrinology, the University of Tokyo Hospital
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, the University of Tokyo Hospital
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15
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Geerlings MJ, Volokhina EB, de Jong EK, van de Kar N, Pauper M, Hoyng CB, van den Heuvel LP, den Hollander AI. Genotype-phenotype correlations of low-frequency variants in the complement system in renal disease and age-related macular degeneration. Clin Genet 2018; 94:330-338. [PMID: 29888403 PMCID: PMC6175426 DOI: 10.1111/cge.13392] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 05/24/2018] [Accepted: 06/03/2018] [Indexed: 12/28/2022]
Abstract
Genetic alterations in the complement system have been linked to a variety of diseases, including atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathy (C3G), and age‐related macular degeneration (AMD). We performed sequence analysis of the complement genes complement factor H (CFH), complement factor I (CFI), and complement C3 (C3) in 866 aHUS/C3G and 697 AMD patients. In total, we identified 505 low‐frequency alleles, representing 121 unique variants, of which 51 are novel. CFH contained the largest number of unique low‐frequency variants (n = 64; 53%), followed by C3 (n = 32; 26%) and CFI (n = 25; 21%). A substantial number of variants were found in both patients groups (n = 48; 40%), while 41 (34%) variants were found only in aHUS/C3G and 32 (26%) variants were AMD specific. Genotype‐phenotype correlations between the disease groups identified a higher frequency of protein altering alleles in short consensus repeat 20 (SCR20) of factor H (FH), and in the serine protease domain of factor I (FI) in aHUS/C3G patients. In AMD, a higher frequency of protein‐altering alleles was observed in SCR3, SCR5, and SCR7 of FH, the SRCR domain of FI, and in the MG3 domain of C3. In conclusion, we observed a substantial overlap of variants between aHUS/C3G and AMD; however, there is a distinct clustering of variants within specific domains.
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Affiliation(s)
- M J Geerlings
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - E B Volokhina
- Radboud university medical center, Radboud Institute for Molecular Life Sciences, Amalia Children's Hospital, Department of Pediatric Nephrology, Nijmegen, The Netherlands.,Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - E K de Jong
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - N van de Kar
- Radboud university medical center, Radboud Institute for Molecular Life Sciences, Amalia Children's Hospital, Department of Pediatric Nephrology, Nijmegen, The Netherlands
| | - M Pauper
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - C B Hoyng
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - L P van den Heuvel
- Radboud university medical center, Radboud Institute for Molecular Life Sciences, Amalia Children's Hospital, Department of Pediatric Nephrology, Nijmegen, The Netherlands.,Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Pediatrics, Department of Growth and Regeneration, University Hospital Leuven, Leuven, Belgium
| | - A I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
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16
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Goicoechea de Jorge E, López Lera A, Bayarri-Olmos R, Yebenes H, Lopez-Trascasa M, Rodríguez de Córdoba S. Common and rare genetic variants of complement components in human disease. Mol Immunol 2018; 102:42-57. [PMID: 29914697 DOI: 10.1016/j.molimm.2018.06.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 06/06/2018] [Accepted: 06/08/2018] [Indexed: 12/21/2022]
Abstract
Genetic variability in the complement system and its association with disease has been known for more than 50 years, but only during the last decade have we begun to understand how this complement genetic variability contributes to the development of diseases. A number of reports have described important genotype-phenotype correlations that associate particular diseases with genetic variants altering specific aspects of the activation and regulation of the complement system. The detailed functional characterization of some of these genetic variants provided key insights into the pathogenic mechanisms underlying these pathologies, which is facilitating the design of specific anti-complement therapies. Importantly, these analyses have sometimes revealed unknown features of the complement proteins. As a whole, these advances have delineated the functional implications of genetic variability in the complement system, which supports the implementation of a precision medicine approach based on the complement genetic makeup of the patients. Here we provide an overview of rare complement variants and common polymorphisms associated with disease and discuss what we have learned from them.
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Affiliation(s)
- Elena Goicoechea de Jorge
- Department of Immunology, Complutense University, Madrid, Spain; Research Institute Hospital 12 de Octubre (imas12), Madrid, Spain
| | - Alberto López Lera
- Research Institute Hospital Universitario La Paz (IdiPaz), Madrid, Spain; Ciber de Enfermedades Raras, Madrid, Spain
| | - Rafael Bayarri-Olmos
- Department of Clinical Immunology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Hugo Yebenes
- Ciber de Enfermedades Raras, Madrid, Spain; Molecular Pathology and Complement Genetics Unit. Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | | | - Santiago Rodríguez de Córdoba
- Ciber de Enfermedades Raras, Madrid, Spain; Molecular Pathology and Complement Genetics Unit. Centro de Investigaciones Biológicas, CSIC, Madrid, Spain.
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17
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Matsumoto T, Toyoda H, Amano K, Hirayama M, Ishikawa E, Fujimoto M, Ito M, Ohishi K, Katayama N, Yoshida Y, Matsumoto M, Kawamura N, Ikejiri M, Kawakami K, Miyata T, Wada H. Clinical Manifestation of Patients With Atypical Hemolytic Uremic Syndrome With the C3 p.I1157T Variation in the Kinki Region of Japan. Clin Appl Thromb Hemost 2018; 24:1301-1307. [PMID: 29695177 PMCID: PMC6714784 DOI: 10.1177/1076029618771750] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The gain-of-function variation p.I1157T in C3 was previously identified in 8 patients with atypical hemolytic uremic syndrome (aHUS) at Mie University Hospital. In the present study, we identified another 11 patients with aHUS with this variation, including 10 pediatric patients (onset age: 1-16 years). The variation seems to be geographically concentrated around Mie Prefecture in Japan. Fifteen of the 19 patients with aHUS experienced infection as probable triggering events. All 19 patients had renal dysfunction. Seven patients, including 2 from the previous study and 5 from the present study, were treated with eculizumab, with all showing a good response with hematological normalization. Among the 5 eculizumab-treated patients in the present study, 3 had an ambiguous diagnosis of aHUS due to low-grade hemolysis even with elevated levels of lactate dehydrogenase and bilirubin. In those cases, in-house targeted DNA sequencing identified the C3 p.I1157T variation carriers, which enabled the early initiation of treatment with eculizumab. The present study supports the early introduction of eculizumab in patients with aHUS, especially pediatric patients.
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Affiliation(s)
- Takeshi Matsumoto
- 1 Division of Blood Transfusion Medicine and Cell Therapy, Mie University Hospital, Tsu, Japan
| | - Hidemi Toyoda
- 2 Department of Pediatrics, Mie University Graduate School of Medicine, Tsu, Japan
| | - Keishirou Amano
- 2 Department of Pediatrics, Mie University Graduate School of Medicine, Tsu, Japan
| | - Masahiro Hirayama
- 2 Department of Pediatrics, Mie University Graduate School of Medicine, Tsu, Japan
| | - Eiji Ishikawa
- 3 Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Mika Fujimoto
- 3 Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Masaaki Ito
- 3 Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Kohshi Ohishi
- 1 Division of Blood Transfusion Medicine and Cell Therapy, Mie University Hospital, Tsu, Japan
| | - Naoyuki Katayama
- 4 Department of Hematology and Oncology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Yoko Yoshida
- 5 Department of Blood Transfusion Medicine, Nara Medical University, Kashihara, Japan
| | - Masanori Matsumoto
- 5 Department of Blood Transfusion Medicine, Nara Medical University, Kashihara, Japan
| | | | - Makoto Ikejiri
- 7 Central Laboratory, Mie University Hospital, Tsu, Japan
| | - Keiki Kawakami
- 8 Department of Hematology, Suzuka General Hospital, Suzuka, Japan
| | - Toshiyuki Miyata
- 9 Departments of Molecular Pathogenesis and Cerebrovascular Medicine, National Central and Cardiovascular Center, Suita, Japan
| | - Hideo Wada
- 10 Department of Molecular and Laboratory Medicine, Mie University Graduate School of Medicine, Tsu, Mie, Japan
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18
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Marin AV, Cárdenas PP, Jiménez-Reinoso A, Muñoz-Ruiz M, Regueiro JR. Lymphocyte integration of complement cues. Semin Cell Dev Biol 2018; 85:132-142. [PMID: 29438807 DOI: 10.1016/j.semcdb.2018.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/08/2018] [Indexed: 12/17/2022]
Abstract
We address current data, views and puzzles on the emerging topic of regulation of lymphocytes by complement proteins or fragments. Such regulation is believed to take place through complement receptors (CR) and membrane complement regulators (CReg) involved in cell function or protection, respectively, including intracellular signalling. Original observations in B cells clearly support that complement cues through CR improve their performance. Other lymphocytes likely integrate complement-derived signals, as most lymphoid cells constitutively express or regulate CR and CReg upon activation. CR-induced signals, particularly by anaphylatoxins, clearly regulate lymphoid cell function. In contrast, data obtained by CReg crosslinking using antibodies are not always confirmed in human congenital deficiencies or knock-out mice, casting doubts on their physiological relevance. Unsurprisingly, human and mouse complement systems are not completely homologous, adding further complexity to our still fragmentary understanding of complement-lymphocyte interactions.
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Affiliation(s)
- Ana V Marin
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Paula P Cárdenas
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Anaïs Jiménez-Reinoso
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Miguel Muñoz-Ruiz
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Jose R Regueiro
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain.
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19
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Abstract
The complement cascade is an ancient defense system that destroys and eliminates threats to normal homeostasis in the bloodstream and tissues. Although multiple controls keep complement in check to minimize innocent bystander injury to normal cells and tissues, defects in complement regulation due to mutations in, or autoantibodies to, complement control proteins underlie the pathogenesis of several hemolytic diseases including paroxysmal nocturnal hemoglobinuria, and atypical hemolytic uremic syndrome. In autoimmune hemolytic anemias complement plays an important role in erythrocyte destruction mediated by antierythrocyte antibodies. The pathogenic mechanisms of these hemolytic diseases are discussed, with an emphasis on pivotal steps in complement activation.
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Affiliation(s)
- Ronald P Taylor
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA.
| | - Margaret A Lindorfer
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA
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20
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Thergaonkar RW, Narang A, Gurjar BS, Tiwari P, Puraswani M, Saini H, Sinha A, Varma B, Mukerji M, Hari P, Bagga A. Targeted exome sequencing in anti-factor H antibody negative HUS reveals multiple variations. Clin Exp Nephrol 2017; 22:653-660. [PMID: 28939980 DOI: 10.1007/s10157-017-1478-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/03/2017] [Indexed: 02/01/2023]
Abstract
BACKGROUND Genetic susceptibility to atypical hemolytic uremic syndrome (aHUS) may lie within genes regulating or activating the alternate complement and related pathways converging on endothelial cell activation. METHODS We tested 32 Indian patients of aHUS negative for antibodies to complement factor H for genetic variations in a panel of 15 genes, i.e., CFH, CFHR1-5, CFI, CFB, C3, CD46, MASP2, DGKE, ADAMTS13, THBD and PLG using next-generation DNA sequencing and for copy number variation in CFHR1-3. RESULTS Despite absence of a public database of exome variations in the Indian population and limited functional studies, we could establish a genetic diagnosis in 6 (18.8%) patients using a stringent scheme of prioritization. One patient carried a likely pathogenic variation. The number of patients carrying possibly pathogenic variation was as follows: 1 variation: 5 patients, 2 variations: 9 patients, 3 variations: 5 patients, 4 variations: 9 patients, 5 variations: 2 patients and 6 variations: 2 patients. Homozygous deletion of CFHR1-3 was present in five patients; none of these carried a diagnostic genetic variation. Patients with or without diagnostic variation did not differ significantly in terms of enrichment of genetic variations that were rare/novel or predicted deleterious, or for possible environmental triggers. CONCLUSION We conclude that genetic testing for multiple genes in patients with aHUS negative for anti-FH antibodies reveals multiple candidate variations that require prioritization. Population data on variation frequency of the Indian population and supportive functional studies are likely to improve diagnostic yield.
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Affiliation(s)
- R W Thergaonkar
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Ankita Narang
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | | | - Pradeep Tiwari
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Mamta Puraswani
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Himanshi Saini
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Aditi Sinha
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Binuja Varma
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Mitali Mukerji
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Pankaj Hari
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Arvind Bagga
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India.
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21
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Huerta A, Arjona E, Portoles J, Lopez-Sanchez P, Rabasco C, Espinosa M, Cavero T, Blasco M, Cao M, Manrique J, Cabello-Chavez V, Suñer M, Heras M, Fulladosa X, Belmar L, Sempere A, Peralta C, Castillo L, Arnau A, Praga M, Rodriguez de Cordoba S. A retrospective study of pregnancy-associated atypical hemolytic uremic syndrome. Kidney Int 2017; 93:450-459. [PMID: 28911789 DOI: 10.1016/j.kint.2017.06.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/23/2017] [Accepted: 06/30/2017] [Indexed: 12/24/2022]
Abstract
Pregnancy-associated atypical hemolytic uremic syndrome (aHUS) refers to the thrombotic microangiopathy resulting from uncontrolled complement activation during pregnancy or the postpartum period. Pregnancy-associated aHUS is a devastating disease for which there is a limited clinical understanding and treatment experience. Here we report a retrospective study to analyze the clinical and prognostic data of 22 cases of pregnancy-associated aHUS from the Spanish aHUS Registry under different treatments. Sixteen patients presented during the first pregnancy and as many as nine patients required hemodialysis at diagnosis. Identification of inherited complement abnormalities explained nine of the 22 cases, with CFH mutations and CFH to CFHR1 gene conversion events being the most prevalent genetic alterations associated with this disorder (66%). In thirteen of the cases, pregnancy complications were sufficient to trigger a thrombotic microangiopathy in the absence of genetic or acquired complement alterations. The postpartum period was the time with highest risk to develop the disease and the group shows an association of cesarean section with pregnancy-associated aHUS. Seventeen patients underwent plasma treatments with a positive renal response in only three cases. In contrast, ten patients received eculizumab with an excellent renal response in all, independent of carrying or not inherited complement abnormalities. Although the cohort is relatively small, the data suggest that pregnancy-associated aHUS is not different from other types of aHUS and suggest the efficacy of eculizumab treatment over plasma therapies. This study may be useful to improve prognosis in this group of aHUS patients.
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Affiliation(s)
- Ana Huerta
- Department of Nephrology, Hospital Universitario Puerta de Hierro Majadahonda, Madrid, Spain; RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain.
| | - Emilia Arjona
- Department of Cellular and Molecular Medicine, Center for Biological Research, Madrid, Spain; Center for Biomedical Network Research on Rare Diseases, Madrid, Spain
| | - Jose Portoles
- Department of Nephrology, Hospital Universitario Puerta de Hierro Majadahonda, Madrid, Spain; RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain
| | - Paula Lopez-Sanchez
- Department of Nephrology, Hospital Universitario Puerta de Hierro Majadahonda, Madrid, Spain
| | - Cristina Rabasco
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Mario Espinosa
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Teresa Cavero
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital 12 de Octubre, Madrid, Spain
| | - Miquel Blasco
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Mercedes Cao
- Department of Nephrology, Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
| | - Joaquin Manrique
- Department of Nephrology, Clinica Universitaria de Navarra, Pamplona, Spain
| | | | - Marta Suñer
- Department of Nephrology, Hospital Universitario Virgen del Rocío, Seville, Spain
| | - Manuel Heras
- Department of Nephrology, Complejo Asistencial de Segovia, Segovia, Spain
| | - Xavier Fulladosa
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital de Bellvitge, Barcelona, Spain
| | - Lara Belmar
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital Universitario Marques de Valdecilla, Santander, Spain
| | - Amparo Sempere
- Department of Hematology, Hospital Universitari Politecnic La Fe, Valencia, Spain
| | - Carmen Peralta
- Department of Nephrology, Hospital Universitari de Tarragona Joan XXIII, Tarragona, Spain
| | - Lorena Castillo
- Department of Nephrology, Hospital Universitari de Tarragona Joan XXIII, Tarragona, Spain
| | - Alvaro Arnau
- Department of Nephrology, Hospital Universitario Donostia, Donostia, Spain
| | - Manuel Praga
- RedinRen RD016/009/009, Instituto de Salud Carlos III, Madrid, Spain; Department of Nephrology, Hospital 12 de Octubre, Madrid, Spain
| | - Santiago Rodriguez de Cordoba
- Department of Cellular and Molecular Medicine, Center for Biological Research, Madrid, Spain; Center for Biomedical Network Research on Rare Diseases, Madrid, Spain.
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22
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de Jorge EG, Yebenes H, Serna M, Tortajada A, Llorca O, de Córdoba SR. How novel structures inform understanding of complement function. Semin Immunopathol 2017; 40:3-14. [PMID: 28808775 DOI: 10.1007/s00281-017-0643-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/03/2017] [Indexed: 11/30/2022]
Abstract
During the last decade, the complement field has experienced outstanding advancements in the mechanistic understanding of how complement activators are recognized, what C3 activation means, how protein complexes like the C3 convertases and the membrane attack complex are assembled, and how positive and negative complement regulators perform their function. All of this has been made possible mostly because of the contributions of structural biology to the study of the complement components. The wealth of novel structural data has frequently provided support to previously held knowledge, but often has added alternative and unexpected insights into complement function. Here, we will review some of these findings focusing in the alternative and terminal complement pathways.
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Affiliation(s)
- Elena Goicoechea de Jorge
- Department of Microbiology I (Immunology), Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Hugo Yebenes
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Marina Serna
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Agustín Tortajada
- Department of Microbiology I (Immunology), Complutense University School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Oscar Llorca
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain.,Structural Biology Programme, CNIO, C/ Melchor Fernández Almagro 3, 28029, Madrid, Spain
| | - Santiago Rodríguez de Córdoba
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain. .,Ciber de Enfermedades Raras, Madrid, Spain.
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23
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Liu G, Arnaud P, Offmann B, Picimbon JF. Genotyping and Bio-Sensing Chemosensory Proteins in Insects. Sensors (Basel) 2017; 17:E1801. [PMID: 28777348 PMCID: PMC5579523 DOI: 10.3390/s17081801] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/28/2017] [Accepted: 07/29/2017] [Indexed: 12/20/2022]
Abstract
Genotyping is the process of determining differences in the genetic make-up of an individual and comparing it to that of another individual. Focus on the family of chemosensory proteins (CSPs) in insects reveals differences at the genomic level across various strains and biotypes, but none at the level of individuals, which could be extremely useful in the biotyping of insect pest species necessary for the agricultural, medical and veterinary industries. Proposed methods of genotyping CSPs include not only restriction enzymatic cleavage and amplification of cleaved polymorphic sequences, but also detection of retroposons in some specific regions of the insect chromosome. Design of biosensors using CSPs addresses tissue-specific RNA mutations in a particular subtype of the protein, which could be used as a marker of specific physiological conditions. Additionally, we refer to the binding properties of CSP proteins tuned to lipids and xenobiotic insecticides for the development of a new generation of biosensor chips, monitoring lipid blood concentration and chemical environmental pollution.
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Affiliation(s)
- Guoxia Liu
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China.
| | - Philippe Arnaud
- Protein Engineering and Functionality Unit, University of Nantes, Nantes 44322, France.
| | - Bernard Offmann
- Protein Engineering and Functionality Unit, University of Nantes, Nantes 44322, France.
| | - Jean-François Picimbon
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China.
- QILU University of Technology, School of Bioengineering, Jinan 250353, China.
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24
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Abstract
Endothelium is strategically located at the interface between blood and interstitial tissues, placing thus endothelial cell as a key player in vascular homeostasis. Endothelial cells are in a dynamic equilibrium with their environment and constitute concomitantly a source, a barrier, and a target of defensive mediators. This review will discuss the recent advances in our understanding of the complex crosstalk between the endothelium, the complement system and the hemostasis in health and in disease. The first part will provide a general introduction on endothelial cells heterogeneity and on the physiologic role of the complement and hemostatic systems. The second part will analyze the interplay between complement, hemostasis and endothelial cells in physiological conditions and their alterations in diseases. Particular focus will be made on the prototypes of thrombotic microangiopathic disorders, resulting from complement or hemostasis dysregulation-mediated endothelial damage: atypical hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. Novel aspects of the pathophysiology of the thrombotic microangiopathies will be discussed.
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Affiliation(s)
- Lubka T Roumenina
- INSERM UMRS 1138, Cordeliers Research Center, Université Pierre et Marie Curie (UPMC-Paris-6) and Université Paris Descartes Sorbonne Paris-Cité, Paris, France.
| | - Julie Rayes
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Marie Frimat
- INSERM UMR 995, Lille, France.,Nephrology Department, CHU Lille, Lille, France
| | - Veronique Fremeaux-Bacchi
- INSERM UMRS 1138, Cordeliers Research Center, Université Pierre et Marie Curie (UPMC-Paris-6) and Université Paris Descartes Sorbonne Paris-Cité, Paris, France.,Assistance Publique - Hôpitaux de Paris, Service d'Immunologie Biologique, Hôpital Européen Georges Pompidou, Paris, France
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25
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Chen P, Zhu L, Yu F, Han SS, Meng SJ, Guo WY, Zhang H, Song Y. Different types of glomerulonephritis associated with the dysregulation of the complement alternative pathway in 2 brothers: A case report. Medicine (Baltimore) 2017; 96:e7144. [PMID: 28614243 PMCID: PMC5478328 DOI: 10.1097/md.0000000000007144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
RATIONALE C3 glomerulonephritis (C3GN) and complement-mediated hemolytic uremic syndrome (HUS) both result from the abnormal regulation of the complement system. A significant number of patients with C3GN or complement-mediated HUS have mutations of more than 1 complement protein. This discovery has had a major impact on identifying the underlying cause of familial C3GN or complement-mediated HUS. PATIENT CONCERNS We report the cases of 2 brothers (herein referred to as patient II-1 and patient II-9), both with complement disorders that differed in their clinical and genetic features. DIAGNOSES Patient II-1 clinically presented with nephrotic syndrome and acute kidney injury and pathologically presented with C3GN combined with thrombotic microangiopathy (TMA) and subacute tubulointerstitial nephritis. Meanwhile, patient II-9 clinically presented with HUS and pathologically presented with TMA combined with acute severe tubular injury. INTERVENTIONS Screenings for genetic mutations contributed to complement system dysregulation were performed on patient II-1. OUTCOMES The genome sequencing identified that patient II-1 had a heterozygous mutation in the C3 gene (c.C1774T/p.R592W). Nine other relatives of the brothers were checked for this C3 mutation and only the daughter of patient II-1 (herein referred to as patient III-2) carried it, but so far, she does not have any clinical manifestations of kidney disease. LESSIONS Family members with a dysregulation of the complement alternative pathway may differ in its clinical and genetic features.
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Affiliation(s)
- Pei Chen
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Li Zhu
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Feng Yu
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Sha-Sha Han
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Si-Jun Meng
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Wei-yi Guo
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Hong Zhang
- Renal Division, Department of Medicine, Peking University First Hospital
- Peking University Institute of Nephrology
- Key Laboratory of Renal Disease, Ministry of Health of China
- Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education
| | - Yan Song
- Department of Nephrology, The First Affiliated Hospital of Chinese PLA General Hospital, Beijing, China
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Mizuno M, Suzuki Y, Ito Y. Complement regulation and kidney diseases: recent knowledge of the double-edged roles of complement activation in nephrology. Clin Exp Nephrol 2017; 22:3-14. [DOI: 10.1007/s10157-017-1405-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 03/14/2017] [Indexed: 12/28/2022]
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27
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López-Perrote A, Harrison RES, Subías M, Alcorlo M, Rodríguez de Córdoba S, Morikis D, Llorca O. Ionic tethering contributes to the conformational stability and function of complement C3b. Mol Immunol 2017; 85:137-147. [PMID: 28254726 DOI: 10.1016/j.molimm.2016.12.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 12/13/2016] [Accepted: 12/15/2016] [Indexed: 11/28/2022]
Abstract
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.
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Affiliation(s)
- Andrés López-Perrote
- Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain
| | - Reed E S Harrison
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Marta Subías
- Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain; Centro de Investigación Biomédica en Enfermedades Raras, Madrid, Spain
| | - Martín Alcorlo
- Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain
| | - Santiago Rodríguez de Córdoba
- Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain; Centro de Investigación Biomédica en Enfermedades Raras, Madrid, Spain.
| | - Dimitrios Morikis
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - Oscar Llorca
- Centro de Investigaciones Biológicas, Spanish National Research Council (CSIC), Madrid, Spain.
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28
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Geerlings MJ, de Jong EK, den Hollander AI. The complement system in age-related macular degeneration: A review of rare genetic variants and implications for personalized treatment. Mol Immunol 2016; 84:65-76. [PMID: 27939104 PMCID: PMC5380947 DOI: 10.1016/j.molimm.2016.11.016] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/12/2016] [Accepted: 11/18/2016] [Indexed: 01/18/2023]
Abstract
The complement system plays a central role in age-related macular degeneration (AMD). Common and rare genetic variants in complement genes have been identified in AMD. Several of the rare variants affect the functioning of the complement system. However, a genetic association with AMD cannot always be proven. Functional assays can help identify patients for complement inhibiting therapies.
Age-related macular degeneration (AMD) is a progressive retinal disease and the major cause of irreversible vision loss in the elderly. Numerous studies have found both common and rare genetic variants in the complement pathway to play a role in the pathogenesis of AMD. In this review we provide an overview of rare variants identified in AMD patients, and summarize the functional consequences of rare genetic variation in complement genes on the complement system. Finally, we discuss the relevance of this work in light of ongoing clinical trials that study the effectiveness of complement inhibitors against AMD.
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Affiliation(s)
- Maartje J Geerlings
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Eiko K de Jong
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anneke I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.
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29
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Abstract
As a preformed defense system, complement faces a delicate challenge in providing an immediate, forceful response to pathogens even at first encounter, while sparing host cells in the process. For this purpose, it engages a tightly regulated network of plasma proteins, cell surface receptors, and regulators. Complement component C3 plays a particularly versatile role in this process by keeping the cascade alert, acting as a point of convergence of activation pathways, fueling the amplification of the complement response, exerting direct effector functions, and helping to coordinate downstream immune responses. In recent years, it has become evident that nature engages the power of C3 not only to clear pathogens but also for a variety of homeostatic processes ranging from tissue regeneration and synapse pruning to clearing debris and controlling tumor cell progression. At the same time, its central position in immune surveillance makes C3 a target for microbial immune evasion and, if improperly engaged, a trigger point for various clinical conditions. In our review, we look at the versatile roles and evolutionary journey of C3, discuss new insights into the molecular basis for C3 function, provide examples of disease involvement, and summarize the emerging potential of C3 as a therapeutic target.
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Affiliation(s)
- Daniel Ricklin
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Edimara S Reis
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Dimitrios C Mastellos
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
- National Center for Scientific Research 'Demokritos', Athens, Greece
| | - Piet Gros
- Utrecht University, Utrecht, The Netherlands
| | - John D Lambris
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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30
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Fung KW, Wright DW, Gor J, Swann MJ, Perkins SJ. Domain structure of human complement C4b extends with increasing NaCl concentration: implications for its regulatory mechanism. Biochem J 2016; 473:4473-91. [PMID: 27738201 DOI: 10.1042/BCJ20160744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 01/06/2023]
Abstract
During the activation of complement C4 to C4b, the exposure of its thioester domain (TED) is crucial for the attachment of C4b to activator surfaces. In the C4b crystal structure, TED forms an Arg104-Glu1032 salt bridge to tether its neighbouring macroglobulin (MG1) domain. Here, we examined the C4b domain structure to test whether this salt bridge affects its conformation. Dual polarisation interferometry of C4b immobilised at a sensor surface showed that the maximum thickness of C4b increased by 0.46 nm with an increase in NaCl concentration from 50 to 175 mM NaCl. Analytical ultracentrifugation showed that the sedimentation coefficient s20,w of monomeric C4b of 8.41 S in 50 mM NaCl buffer decreased to 7.98 S in 137 mM NaCl buffer, indicating that C4b became more extended. Small angle X-ray scattering reported similar RG values of 4.89-4.90 nm for C4b in 137-250 mM NaCl. Atomistic scattering modelling of the C4b conformation showed that TED and the MG1 domain were separated by 4.7 nm in 137-250 mM NaCl and this is greater than that of 4.0 nm in the C4b crystal structure. Our data reveal that in low NaCl concentrations, both at surfaces and in solution, C4b forms compact TED-MG1 structures. In solution, physiologically relevant NaCl concentrations lead to the separation of the TED and MG1 domain, making C4b less capable of binding to its complement regulators. These conformational changes are similar to those seen previously for complement C3b, confirming the importance of this salt bridge for regulating both C4b and C3b.
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31
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Heurich M, Preston RJS, O'Donnell VB, Morgan BP, Collins PW. Thrombomodulin enhances complement regulation through strong affinity interactions with factor H and C3b-Factor H complex. Thromb Res 2016; 145:84-92. [PMID: 27513882 DOI: 10.1016/j.thromres.2016.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/20/2016] [Accepted: 07/29/2016] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Coagulation and complement systems are simultaneously activated at sites of tissue injury, leading to thrombin generation and opsonisation with C3b. Thrombomodulin (TM) is a cell-bound regulator of thrombin activation, but can also enhance the regulatory activity of complement factor H (FH), thus accelerating the degradation of C3b into inactive iC3b. OBJECTIVES This study sought to determine the biophysical interaction affinities of two recombinant TM analogs with thrombin, FH and C3b in order to analyze their ability to regulate serum complement activity. METHODS Surface plasmon resonance (SPR) analysis was used to determine binding affinities of TM analogs with FH and C3b, and compared to thrombin as positive control. The capacity of the two recombinant TM analogs to regulate complement in serum was tested in standard complement hemolytic activity assays. RESULTS SPR analysis showed that both TM analogs bind FH and C3b-Factor H with nanomolar and C3b with micromolar affinity; binding affinity for its natural ligand thrombin was several fold higher than for FH. At a physiological relevant concentration, TM inhibits complement hemolytic activity in serum via FH dependent and independent mechanisms. CONCLUSIONS TM exhibits significant binding affinity for complement protein FH and C3b-FH complex and its soluble form is capable at physiologically relevant concentrations of inhibiting complement activation in serum.
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Affiliation(s)
- M Heurich
- Division of Infection & Immunity and Systems Immunity Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom.
| | - R J S Preston
- Department of Clinical Medicine, School of Medicine, Trinity College Dublin, Ireland; National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin 12, Ireland
| | - V B O'Donnell
- Division of Infection & Immunity and Systems Immunity Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - B P Morgan
- Division of Infection & Immunity and Systems Immunity Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - P W Collins
- Division of Infection & Immunity and Systems Immunity Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
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Abstract
Hemolytic anemia can be caused by various hereditary or acquired diseases. Classification is usually based on corpuscular or extracorpuscular defects. Beside the anemia, laboratory testing indicates increased lactate dehydrogenase, unconjugated bilirubin and reticulocytes as well as reduced or absent plasma haptoglobin. Knowledge of further diagnostic procedures (e.g., Coombs test, schistocytes, hemoglobin electrophoresis or flow cytometric analysis) leads in many cases to an underlying disease with differentiated therapeutic options. Autoimmune hemolytic anemia (AIHA) is often associated with diseases as HIV, connective tissue disease, lymphomas or malignant tumors and the hemolytic process is preexisting in many cases. Thrombotic microvascular diseases (e.g., thrombotic thrombocytopenic purpura or hemolytic-uremic syndrome) are further important causes of hemolytic anemia which need immediate diagnosis and treatment.
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Affiliation(s)
- A Tuchscherer
- Klinik I für Innere Medizin, Uniklinik Köln, Kerpener Str. 62, 50937, Köln, Deutschland,
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Toyoda H, Wada H, Miyata T, Amano K, Kihira K, Iwamoto S, Hirayama M, Komada Y. Disease Recurrence After Early Discontinuation of Eculizumab in a Patient With Atypical Hemolytic Uremic Syndrome With Complement C3 I1157T Mutation. J Pediatr Hematol Oncol 2016; 38:e137-9. [PMID: 26840081 DOI: 10.1097/MPH.0000000000000505] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Eculizumab, terminal complement inhibitor, has become the frontline treatment for atypical hemolytic uremic syndrome (aHUS). However, the optimal treatment schedule has not yet been established. We describe here an aHUS patient with a mutation of C3 I1157T who achieved remission with eculizumab and suffered a recurrence after eculizumab discontinuation, a clinical situation that has not been previously described in patients with C3 mutation. A 9-year-old male experienced an onset of aHUS after viral gastroenteritis and was treated with hemodialysis. At 13 years of age he developed bacterial enterocolitis due to Campylobacter jejuni and experienced a recurrence of aHUS. Eculizumab was initiated on day 4 after disease onset resulting in recovering laboratory parameters. The patient received eculizumab for 5 months before its discontinuation. Second relapse induced by bacterial pharyngitis was confirmed 4 months after eculizumab discontinuation and prompt eculizumab reinitiation resulted in rapid remission. The patients carrying mutations in CFH or C3 have a high frequency of relapse and worse prognosis. More than 50% of aHUS relapses occurred during the first year after the onset. Therefore, long-term treatment with eculizumab is appropriate in patients with aHUS who have experienced a relapse or have mutations associated with poor prognosis.
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Forneris F, Wu J, Xue X, Ricklin D, Lin Z, Sfyroera G, Tzekou A, Volokhina E, Granneman JC, Hauhart R, Bertram P, Liszewski MK, Atkinson JP, Lambris JD, Gros P. Regulators of complement activity mediate inhibitory mechanisms through a common C3b-binding mode. EMBO J 2016; 35:1133-49. [PMID: 27013439 PMCID: PMC4868954 DOI: 10.15252/embj.201593673] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 02/29/2016] [Indexed: 01/17/2023] Open
Abstract
Regulators of complement activation (RCA) inhibit complement‐induced immune responses on healthy host tissues. We present crystal structures of human RCA (MCP, DAF, and CR1) and a smallpox virus homolog (SPICE) bound to complement component C3b. Our structural data reveal that up to four consecutive homologous CCP domains (i–iv), responsible for inhibition, bind in the same orientation and extended arrangement at a shared binding platform on C3b. Large sequence variations in CCP domains explain the diverse C3b‐binding patterns, with limited or no contribution of some individual domains, while all regulators show extensive contacts with C3b for the domains at the third site. A variation of ~100° rotation around the longitudinal axis is observed for domains binding at the fourth site on C3b, without affecting the overall binding mode. The data suggest a common evolutionary origin for both inhibitory mechanisms, called decay acceleration and cofactor activity, with variable C3b binding through domains at sites ii, iii, and iv, and provide a framework for understanding RCA disease‐related mutations and immune evasion.
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Affiliation(s)
- Federico Forneris
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science Utrecht University, Utrecht, The Netherlands
| | - Jin Wu
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science Utrecht University, Utrecht, The Netherlands
| | - Xiaoguang Xue
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science Utrecht University, Utrecht, The Netherlands
| | - Daniel Ricklin
- Department of Pathology & Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Zhuoer Lin
- Department of Pathology & Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Georgia Sfyroera
- Department of Pathology & Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Apostolia Tzekou
- Department of Pathology & Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Elena Volokhina
- Department of Pediatric Nephrology (830), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joke Cm Granneman
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science Utrecht University, Utrecht, The Netherlands
| | - Richard Hauhart
- Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO, USA
| | - Paula Bertram
- Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO, USA
| | - M Kathryn Liszewski
- Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO, USA
| | - John P Atkinson
- Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO, USA
| | - John D Lambris
- Department of Pathology & Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science Utrecht University, Utrecht, The Netherlands
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Pérez-Calatayud ÁA, Briones-Garduño JC, Álvarez-Goris Mdel P, Sánchez Zamora R, Torres Aguilar AA, Mendoza-Mórales RE. [Atipical uremic hemolityc syndrome in pregnancy]. CIR CIR 2016; 84:344-9. [PMID: 27004941 DOI: 10.1016/j.circir.2016.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 02/08/2016] [Indexed: 11/22/2022]
Abstract
Atypical haemolytic uraemic syndrome is one of the main variants of thrombotic microangiopathy, and is characterized by excessive complement activation in the microvasculature. It is also characterised by the clinical triad; non-immune haemolytic anaemia, thrombocytopenia, and acute renal failure. In addition, 60% of patients have mutations in the genes encoding complement regulators (factor H, factor I, membrane cofactor proteins, and thrombomodulin), activators (factor B and C3), as well as autoantibodies against factor H. Multiple factors are required for the disease to manifest itself, including a trigger and gene mutations with adequate penetration. Being one of the differential diagnoses of preeclampsia- eclampsia and HELLP syndrome means that the clinician must be familiar with the disease due to its high mortality, which can be modified with early diagnosis and comprehensive treatment.
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Siomou E, Gkoutsias A, Serbis A, Kollios K, Chaliasos N, Frémeaux-Bacchi V. aHUS associated with C3 gene mutation: a case with numerous relapses and favorable 20-year outcome. Pediatr Nephrol 2016; 31:513-7. [PMID: 26572892 DOI: 10.1007/s00467-015-3267-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 11/02/2015] [Accepted: 11/02/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND Atypical hemolytic uremic syndrome (aHUS) is frequently associated with gene mutations in complement-regulatory proteins and activators. Different complement C3 gene mutations have been associated with different outcomes in aHUS. CASE-DIAGNOSIS/TREATMENT We report the case of a 21-year-old male with a C3 heterozygous gene mutation (p.Ile1157Thr) who developed aHUS at the age of 10 months and had six relapses, the last at the age of 14.5 years. Each relapse was characterized by an apparent predominance of hematological manifestations with milder renal involvement and was followed by complete recovery, with creatinine values and hematological parameters usually recovering after the 3rd to 6th day of hospitalization. The patient was treated with plasma infusion, apart from the initial and the last episode, when dialysis was needed. Twenty years after the onset, he retains normal renal function, with no proteinuria or hypertension. One similar case of highly recurrent aHUS carrying the same C3 mutation as our patient with recovery of renal function has been previously reported. CONCLUSIONS We further support that aHUS associated with the p.Ile1157Thr C3 mutation may be highly recurrent, but with recovered renal function. The prevalent p.Ile1157Thr C3 gene mutation has variable disease manifestations and both severe and milder renal phenotypes have been found.
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Affiliation(s)
- Ekaterini Siomou
- Department of Pediatrics, Ioannina University Hospital, Stavros Niarchos Avenue, GR-45 500, Ioannina, Greece.
| | - Athanasios Gkoutsias
- Department of Pediatrics, Ioannina University Hospital, Stavros Niarchos Avenue, GR-45 500, Ioannina, Greece
| | - Anastasios Serbis
- Department of Pediatrics, Ioannina University Hospital, Stavros Niarchos Avenue, GR-45 500, Ioannina, Greece
| | - Konstantinos Kollios
- Third Department of Pediatrics, Aristotle University School of Medicine, Thessaloniki, Greece
| | - Nikolaos Chaliasos
- Department of Pediatrics, Ioannina University Hospital, Stavros Niarchos Avenue, GR-45 500, Ioannina, Greece
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Abstract
Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.
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Affiliation(s)
- Chloe R McDonald
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, TorontoON, Canada; Department of Global Health and Population, Harvard School of Public Health, BostonMA, USA
| | - Vanessa Tran
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, Toronto ON, Canada
| | - Kevin C Kain
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, TorontoON, Canada; Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, TorontoON, Canada
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Gautam AK, Panse Y, Ghosh P, Reza MJ, Mullick J, Sahu A. Mutational analysis of Kaposica reveals that bridging of MG2 and CUB domains of target protein is crucial for the cofactor activity of RCA proteins. Proc Natl Acad Sci U S A 2015; 112:12794-9. [PMID: 26420870 DOI: 10.1073/pnas.1506449112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The complement system has evolved to annul pathogens, but its improper regulation is linked with diseases. Efficient regulation of the system is primarily provided by a family of proteins termed regulators of complement activation (RCA). The knowledge of precise structural determinants of RCA proteins critical for imparting the regulatory activities and the molecular events underlying the regulatory processes, nonetheless, is still limited. Here, we have dissected the structural requirements of RCA proteins that are crucial for one of their two regulatory activities, the cofactor activity (CFA), by using the Kaposi's sarcoma-associated herpesvirus RCA homolog Kaposica as a model protein. We have scanned the entire Kaposica molecule by sequential mutagenesis using swapping and site-directed mutagenesis, which identified residues critical for its interaction with C3b and factor I. Mapping of these residues onto the modeled structure of C3b-Kaposica-factor I complex supported the mutagenesis data. Furthermore, the model suggested that the C3b-interacting residues bridge the CUB (complement C1r-C1s, Uegf, Bmp1) and MG2 (macroglobulin-2) domains of C3b. Thus, it seems that stabilization of the CUB domain with respect to the core of the C3b molecule is central for its CFA. Identification of CFA-critical regions in Kaposica guided experiments in which the equivalent regions of membrane cofactor protein were swapped into decay-accelerating factor. This strategy allowed CFA to be introduced into decay-accelerating factor, suggesting that viral and human regulators use a common mechanism for CFA.
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Alcorlo M, López-Perrote A, Delgado S, Yébenes H, Subías M, Rodríguez-Gallego C, Rodríguez de Córdoba S, Llorca O. Structural insights on complement activation. FEBS J 2015; 282:3883-91. [PMID: 26250513 DOI: 10.1111/febs.13399] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/06/2015] [Accepted: 08/04/2015] [Indexed: 11/29/2022]
Abstract
The proteolytic cleavage of C3 to generate C3b is the central and most important step in the activation of complement, a major component of innate immunity. The comparison of the crystal structures of C3 and C3b illustrates large conformational changes during the transition from C3 to C3b. Exposure of a reactive thio-ester group allows C3b to bind covalently to surfaces such as pathogens or apoptotic cellular debris. The displacement of the thio-ester-containing domain (TED) exposes hidden surfaces that mediate the interaction with complement factor B to assemble the C3-convertase of the alternative pathway (AP). In addition, the displacement of the TED and its interaction with the macroglobulin 1 (MG1) domain generates an extended surface in C3b where the complement regulators factor H (FH), decay accelerating factor (DAF), membrane cofactor protein (MCP) and complement receptor 1 (CR1) can bind, mediating accelerated decay of the AP C3-convertase and proteolytic inactivation of C3b. In the last few years, evidence has accumulated revealing that the structure of C3b in solution is significantly more flexible than anticipated. We review our current knowledge on C3b structural flexibility to propose a general model where the TED can display a collection of conformations around the MG ring, as well as a few specialized positions where the TED is held in one of several fixed locations. Importantly, this conformational heterogeneity in C3b impacts complement regulation by affecting the interaction with regulators.
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Affiliation(s)
- Martín Alcorlo
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Andrés López-Perrote
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Sandra Delgado
- BioGUNE, Unidad de Biología Estructural - Ed. 800, Derio, Bizkaia, Spain
| | - Hugo Yébenes
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Marta Subías
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - César Rodríguez-Gallego
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Santiago Rodríguez de Córdoba
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain.,Centro Investigaciones Biológicas, Ciber de Enfermedades Raras, Madrid, Spain
| | - Oscar Llorca
- Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas, Madrid, Spain
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de Córdoba SR. Complement genetics and susceptibility to inflammatory disease. Lessons from genotype-phenotype correlations. Immunobiology 2015; 221:709-14. [PMID: 26004345 DOI: 10.1016/j.imbio.2015.05.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/06/2015] [Indexed: 10/23/2022]
Abstract
Different genome-wide linkage and association studies performed during the last 15 years have associated mutations and polymorphisms in complement genes with different diseases characterized by tissue damage and inflammation. These are complex disorders in which genetically susceptible individuals usually develop the pathology as a consequence of environmental triggers. Although complement dysregulation is a common feature of these pathologies, how the disease phenotype is determined is only partly understood. One way to advance understanding is to focus the research in the analysis of the peculiar genotype-phenotype correlations that characterize some of these diseases. I will review here how understanding the functional consequences of these disease-associated complement genetic variants is providing us with novel insights into the underpinning complement biology and a better knowledge of the pathogenic mechanisms underlying each of these pathologies. These advances have important therapeutic and diagnostic implications.
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