1
|
Grunin M, de Jong S, Palmer EL, Jin B, Rinker D, Moth C, Capra A, Haines JL, Bush WS, den Hollander AI. Spatial Distribution of Missense Variants within Complement Proteins Associates with Age Related Macular Degeneration. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.08.28.23294686. [PMID: 37693462 PMCID: PMC10491280 DOI: 10.1101/2023.08.28.23294686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Purpose Genetic variants in complement genes are associated with age-related macular degeneration (AMD). However, many rare variants have been identified in these genes, but have an unknown significance, and their impact on protein function and structure is still unknown. We set out to address this issue by evaluating the spatial placement and impact on protein structureof these variants by developing an analytical pipeline and applying it to the International AMD Genomics Consortium (IAMDGC) dataset (16,144 AMD cases, 17,832 controls). Methods The IAMDGC dataset was imputed using the Haplotype Reference Consortium (HRC), leading to an improvement of over 30% more imputed variants, over the original 1000 Genomes imputation. Variants were extracted for the CFH , CFI , CFB , C9 , and C3 genes, and filtered for missense variants in solved protein structures. We evaluated these variants as to their placement in the three-dimensional structure of the protein (i.e. spatial proximity in the protein), as well as AMD association. We applied several pipelines to a) calculate spatial proximity to known AMD variants versus gnomAD variants, b) assess a variant's likelihood of causing protein destabilization via calculation of predicted free energy change (ddG) using Rosetta, and c) whole gene-based testing to test for statistical associations. Gene-based testing using seqMeta was performed using a) all variants b) variants near known AMD variants or c) with a ddG >|2|. Further, we applied a structural kernel adaptation of SKAT testing (POKEMON) to confirm the association of spatial distributions of missense variants to AMD. Finally, we used logistic regression on known AMD variants in CFI to identify variants leading to >50% reduction in protein expression from known AMD patient carriers of CFI variants compared to wild type (as determined by in vitro experiments) to determine the pipeline's robustness in identifying AMD-relevant variants. These results were compared to functional impact scores, ie CADD values > 10, which indicate if a variant may have a large functional impact genomewide, to determine if our metrics have better discriminative power than existing variant assessment methods. Once our pipeline had been validated, we then performed a priori selection of variants using this pipeline methodology, and tested AMD patient cell lines that carried those selected variants from the EUGENDA cohort (n=34). We investigated complement pathway protein expression in vitro , looking at multiple components of the complement factor pathway in patient carriers of bioinformatically identified variants. Results Multiple variants were found with a ddG>|2| in each complement gene investigated. Gene-based tests using known and novel missense variants identified significant associations of the C3 , C9 , CFB , and CFH genes with AMD risk after controlling for age and sex (P=3.22×10 -5 ;7.58×10 -6 ;2.1×10 -3 ;1.2×10 -31 ). ddG filtering and SKAT-O tests indicate that missense variants that are predicted to destabilize the protein, in both CFI and CFH, are associated with AMD (P=CFH:0.05, CFI:0.01, threshold of 0.05 significance). Our structural kernel approach identified spatial associations for AMD risk within the protein structures for C3, C9, CFB, CFH, and CFI at a nominal p-value of 0.05. Both ddG and CADD scores were predictive of reduced CFI protein expression, with ROC curve analyses indicating ddG is a better predictor (AUCs of 0.76 and 0.69, respectively). A priori in vitro analysis of variants in all complement factor genes indicated that several variants identified via bioinformatics programs PathProx/POKEMON in our pipeline via in vitro experiments caused significant change in complement protein expression (P=0.04) in actual patient carriers of those variants, via ELISA testing of proteins in the complement factor pathway, and were previously unknown to contribute to AMD pathogenesis. Conclusion We demonstrate for the first time that missense variants in complement genes cluster together spatially and are associated with AMD case/control status. Using this method, we can identify CFI and CFH variants of previously unknown significance that are predicted to destabilize the proteins. These variants, both in and outside spatial clusters, can predict in-vitro tested CFI protein expression changes, and we hypothesize the same is true for CFH . A priori identification of variants that impact gene expression allow for classification for previously classified as VUS. Further investigation is needed to validate the models for additional variants and to be applied to all AMD-associated genes.
Collapse
|
2
|
Busch C, Rau S, Sekulic A, Perie L, Huber C, Gehrke M, Joussen AM, Zipfel PF, Wildner G, Skerka C, Strauß O. Increased plasma level of terminal complement complex in AMD patients: potential functional consequences for RPE cells. Front Immunol 2023; 14:1200725. [PMID: 37359546 PMCID: PMC10287163 DOI: 10.3389/fimmu.2023.1200725] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/23/2023] [Indexed: 06/28/2023] Open
Abstract
Purpose Polymorphisms in complement genes are risk-associated for age-related macular degeneration (AMD). Functional analysis revealed a common deficiency to control the alternative complement pathway by risk-associated gene polymorphisms. Thus, we investigated the levels of terminal complement complex (TCC) in the plasma of wet AMD patients with defined genotypes and the impact of the complement activation of their plasma on second-messenger signaling, gene expression, and cytokine/chemokine secretion in retinal pigment epithelium (RPE) cells. Design Collection of plasma from patients with wet AMD (n = 87: 62% female and 38% male; median age 77 years) and controls (n = 86: 39% female and 61% male; median age 58 years), grouped for risk factor smoking and genetic risk alleles CFH 402HH and ARMS2 rs3750846, determination of TCC levels in the plasma, in vitro analysis on RPE function during exposure to patients' or control plasma as a complement source. Methods Genotyping, measurement of TCC concentrations, ARPE-19 cell culture, Ca2+ imaging, gene expression by qPCR, secretion by multiplex bead analysis of cell culture supernatants. Main outcome measures TCC concentration in plasma, intracellular free Ca2+, relative mRNA levels, cytokine secretion. Results TCC levels in the plasma of AMD patients were five times higher than in non-AMD controls but did not differ in plasma from carriers of the two risk alleles. Complement-evoked Ca2+ elevations in RPE cells differed between patients and controls with a significant correlation between TCC levels and peak amplitudes. Comparing the Ca2+ signals, only between the plasma of smokers and non-smokers, as well as heterozygous (CFH 402YH) and CFH 402HH patients, revealed differences in the late phase. Pre-stimulation with complement patients' plasma led to sensitization for complement reactions by RPE cells. Gene expression for surface molecules protective against TCC and pro-inflammatory cytokines increased after exposure to patients' plasma. Patients' plasma stimulated the secretion of pro-inflammatory cytokines in the RPE. Conclusion TCC levels were higher in AMD patients but did not depend on genetic risk factors. The Ca2+ responses to patients' plasma as second-messenger represent a shift of RPE cells to a pro-inflammatory phenotype and protection against TCC. We conclude a substantial role of high TCC plasma levels in AMD pathology.
Collapse
Affiliation(s)
- Catharina Busch
- Department of Ophthalmology, University Hospital Leipzig, Leipzig, Germany
| | - Saskia Rau
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, Berlin, Germany
| | - Andjela Sekulic
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, Berlin, Germany
| | - Luce Perie
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knoell-Institute, Jena, Germany
| | - Christian Huber
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, Berlin, Germany
| | - Miranda Gehrke
- Section of Immunobiology, Department of Ophthalmology, University Hospital, Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
| | - Antonia M. Joussen
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, Berlin, Germany
| | - Peter F. Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knoell-Institute, Jena, Germany
- Institute of Microbiology, Friedrich-Schiller-University, Jena, Germany
| | - Gerhild Wildner
- Section of Immunobiology, Department of Ophthalmology, University Hospital, Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
| | - Christine Skerka
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knoell-Institute, Jena, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, Berlin, Germany
| |
Collapse
|
3
|
de Jong S, Tang J, Clark SJ. Age-related macular degeneration: A disease of extracellular complement amplification. Immunol Rev 2023; 313:279-297. [PMID: 36223117 DOI: 10.1111/imr.13145] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Age-related macular degeneration (AMD) is a major cause of vision impairment in the Western World, and with the aging world population, its incidence is increasing. As of today, for the majority of patients, no treatment exists. Multiple genetic and biochemical studies have shown a strong association with components in the complement system and AMD, and evidence suggests a major role of remodeling of the extracellular matrix underlying the outer blood/retinal barrier. As part of the innate immune system, the complement cascade acts as a first-line defense against pathogens, and upon activation, its amplification loop ensures a strong, rapid, and sustained response. Excessive activation, however, can lead to host tissue damage and cause complement-associated diseases like AMD. AMD patients present with aberrant activation of the alternative pathway, especially in ocular tissues but also on a systemic level. Here, we review the latest findings of complement activation in AMD, and we will discuss in vivo observations made in human tissue, cellular models, the potential synergy of different AMD-associated pathways, and conclude on current clinical trials and the future outlook.
Collapse
Affiliation(s)
- Sarah de Jong
- Department for Ophthalmology, University Eye Clinic, Eberhard Karls University of Tübingen, Tübingen, Germany.,Department for Ophthalmology, Institute for Ophthalmic Research, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Jiaqi Tang
- Department for Ophthalmology, University Eye Clinic, Eberhard Karls University of Tübingen, Tübingen, Germany.,Department for Ophthalmology, Institute for Ophthalmic Research, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Simon J Clark
- Department for Ophthalmology, University Eye Clinic, Eberhard Karls University of Tübingen, Tübingen, Germany.,Department for Ophthalmology, Institute for Ophthalmic Research, Eberhard Karls University of Tübingen, Tübingen, Germany.,Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| |
Collapse
|
4
|
Sharma A, Gupta S, Patil AB, Vijay N. Birth and death in terminal complement pathway. Mol Immunol 2022; 149:174-187. [PMID: 35908437 DOI: 10.1016/j.molimm.2022.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/15/2022] [Accepted: 07/18/2022] [Indexed: 10/16/2022]
Abstract
The cytolytic activity of the membrane attack complex (MAC) is pivotal in the complement-mediated elimination of pathogens. Terminal complement pathway (TCP) genes encode the proteins that form the MAC. Although the TCP genes are well conserved within most vertebrate species, the early evolution of the TCP genes is poorly understood. Based on the comparative genomic analysis of the early evolutionary history of the TCP homologs, we evaluated four possible scenarios that could have given rise to the vertebrate TCP. Currently available genomic data support a scheme of complex sequential protein domain gains that may be responsible for the birth of the vertebrate C6 gene. The subsequent duplication and divergence of this vertebrate C6 gene formed the C7, C8α, C8β, and C9 genes. Compared to the widespread conservation of TCP components within vertebrates, we discovered that C9 has disintegrated in the genomes of galliform birds. Publicly available genome and transcriptome sequencing datasets of chicken from Illumina short read, PacBio long read, and Optical mapping technologies support the validity of the genome assembly at the C9 locus. In this study, we have generated a > 120X coverage whole-genome Chromium 10x linked-read sequencing dataset for the chicken and used it to verify the loss of the C9 gene in the chicken. We find multiple CR1 (chicken repeat 1) element insertions within and near the remnant exons of C9 in several galliform bird genomes. The reconstructed chronology of events shows that the CR1 insertions occurred after C9 gene loss in an early galliform ancestor. Loss of C9 in galliform birds, in contrast to conservation in other vertebrates, may have implications for host-pathogen interactions. Our study of C6 gene birth in an early vertebrate ancestor and C9 gene death in galliform birds provides insights into the evolution of the TCP.
Collapse
Affiliation(s)
- Ashutosh Sharma
- Computational Evolutionary Genomics Lab, Department of Biological Sciences, IISER Bhopal, Bhauri, Madhya Pradesh, India
| | - Saumya Gupta
- Computational Evolutionary Genomics Lab, Department of Biological Sciences, IISER Bhopal, Bhauri, Madhya Pradesh, India
| | - Ajinkya Bharatraj Patil
- Computational Evolutionary Genomics Lab, Department of Biological Sciences, IISER Bhopal, Bhauri, Madhya Pradesh, India
| | - Nagarjun Vijay
- Computational Evolutionary Genomics Lab, Department of Biological Sciences, IISER Bhopal, Bhauri, Madhya Pradesh, India.
| |
Collapse
|
5
|
Shughoury A, Sevgi DD, Ciulla TA. Molecular Genetic Mechanisms in Age-Related Macular Degeneration. Genes (Basel) 2022; 13:genes13071233. [PMID: 35886016 PMCID: PMC9316037 DOI: 10.3390/genes13071233] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/30/2022] [Accepted: 07/05/2022] [Indexed: 11/29/2022] Open
Abstract
Age-related macular degeneration (AMD) is among the leading causes of irreversible blindness worldwide. In addition to environmental risk factors, such as tobacco use and diet, genetic background has long been established as a major risk factor for the development of AMD. However, our ability to predict disease risk and personalize treatment remains limited by our nascent understanding of the molecular mechanisms underlying AMD pathogenesis. Research into the molecular genetics of AMD over the past two decades has uncovered 52 independent gene variants and 34 independent loci that are implicated in the development of AMD, accounting for over half of the genetic risk. This research has helped delineate at least five major pathways that may be disrupted in the pathogenesis of AMD: the complement system, extracellular matrix remodeling, lipid metabolism, angiogenesis, and oxidative stress response. This review surveys our current understanding of each of these disease mechanisms, in turn, along with their associated pathogenic gene variants. Continued research into the molecular genetics of AMD holds great promise for the development of precision-targeted, personalized therapies that bring us closer to a cure for this debilitating disease.
Collapse
Affiliation(s)
- Aumer Shughoury
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Duriye Damla Sevgi
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Thomas A Ciulla
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Clearside Biomedical, Inc., Alpharetta, GA 30005, USA
- Midwest Eye Institute, Indianapolis, IN 46290, USA
| |
Collapse
|
6
|
Structural basis of soluble membrane attack complex packaging for clearance. Nat Commun 2021; 12:6086. [PMID: 34667172 PMCID: PMC8526713 DOI: 10.1038/s41467-021-26366-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 10/01/2021] [Indexed: 12/15/2022] Open
Abstract
Unregulated complement activation causes inflammatory and immunological pathologies with consequences for human disease. To prevent bystander damage during an immune response, extracellular chaperones (clusterin and vitronectin) capture and clear soluble precursors to the membrane attack complex (sMAC). However, how these chaperones block further polymerization of MAC and prevent the complex from binding target membranes remains unclear. Here, we address that question by combining cryo electron microscopy (cryoEM) and cross-linking mass spectrometry (XL-MS) to solve the structure of sMAC. Together our data reveal how clusterin recognizes and inhibits polymerizing complement proteins by binding a negatively charged surface of sMAC. Furthermore, we show that the pore-forming C9 protein is trapped in an intermediate conformation whereby only one of its two transmembrane β-hairpins has unfurled. This structure provides molecular details for immune pore formation and helps explain a complement control mechanism that has potential implications for how cell clearance pathways mediate immune homeostasis. To prevent unregulated complement activation, extracellular chaperones capture soluble precursors to the membrane attack complex (sMAC). Here, structural analysis of sMAC reveals how clusterin recognizes heterogeneous sMAC complexes and inhibits polymerization of complement protein C9.
Collapse
|
7
|
Afanasyeva TAV, Corral-Serrano JC, Garanto A, Roepman R, Cheetham ME, Collin RWJ. A look into retinal organoids: methods, analytical techniques, and applications. Cell Mol Life Sci 2021; 78:6505-6532. [PMID: 34420069 PMCID: PMC8558279 DOI: 10.1007/s00018-021-03917-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/14/2021] [Accepted: 08/09/2021] [Indexed: 12/15/2022]
Abstract
Inherited retinal diseases (IRDs) cause progressive loss of light-sensitive photoreceptors in the eye and can lead to blindness. Gene-based therapies for IRDs have shown remarkable progress in the past decade, but the vast majority of forms remain untreatable. In the era of personalised medicine, induced pluripotent stem cells (iPSCs) emerge as a valuable system for cell replacement and to model IRD because they retain the specific patient genome and can differentiate into any adult cell type. Three-dimensional (3D) iPSCs-derived retina-like tissue called retinal organoid contains all major retina-specific cell types: amacrine, bipolar, horizontal, retinal ganglion cells, Müller glia, as well as rod and cone photoreceptors. Here, we describe the main applications of retinal organoids and provide a comprehensive overview of the state-of-art analysis methods that apply to this model system. Finally, we will discuss the outlook for improvements that would bring the cellular model a step closer to become an established system in research and treatment development of IRDs.
Collapse
Affiliation(s)
- Tess A V Afanasyeva
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
| | | | - Alejandro Garanto
- Department of Pediatrics, Amalia Children's Hospital and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald Roepman
- Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michael E Cheetham
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
| | - Rob W J Collin
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands.
| |
Collapse
|
8
|
McMahon O, Hallam TM, Patel S, Harris CL, Menny A, Zelek WM, Widjajahakim R, Java A, Cox TE, Tzoumas N, Steel DHW, Shuttleworth VG, Smith-Jackson K, Brocklebank V, Griffiths H, Cree AJ, Atkinson JP, Lotery AJ, Bubeck D, Morgan BP, Marchbank KJ, Seddon JM, Kavanagh D. The rare C9 P167S risk variant for age-related macular degeneration increases polymerization of the terminal component of the complement cascade. Hum Mol Genet 2021; 30:1188-1199. [PMID: 33783477 PMCID: PMC8212764 DOI: 10.1093/hmg/ddab086] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 12/25/2022] Open
Abstract
Age-related macular degeneration (AMD) is a complex neurodegenerative eye disease with behavioral and genetic etiology and is the leading cause of irreversible vision loss among elderly Caucasians. Functionally significant genetic variants in the alternative pathway of complement have been strongly linked to disease. More recently, a rare variant in the terminal pathway of complement has been associated with increased risk, Complement component 9 (C9) P167S. To assess the functional consequence of this variant, C9 levels were measured in two independent cohorts of AMD patients. In both cohorts, it was demonstrated that the P167S variant was associated with low C9 plasma levels. Further analysis showed that patients with advanced AMD had elevated sC5b-9 compared to those with non-advanced AMD, although this was not associated with the P167S polymorphism. Electron microscopy of membrane attack complexes (MACs) generated using recombinantly produced wild type or P167S C9 demonstrated identical MAC ring structures. In functional assays, the P167S variant displayed a higher propensity to polymerize and a small increase in its ability to induce hemolysis of sheep erythrocytes when added to C9-depleted serum. The demonstration that this C9 P167S AMD risk polymorphism displays increased polymerization and functional activity provides a rationale for the gene therapy trials of sCD59 to inhibit the terminal pathway of complement in AMD that are underway.
Collapse
Affiliation(s)
- O McMahon
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - T M Hallam
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - S Patel
- Department of Ophthalmology and Visual Sciences, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - C L Harris
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - A Menny
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| | - W M Zelek
- Division of Infection and Immunity, School of Medicine, Systems Immunity Research Institute, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - R Widjajahakim
- Department of Ophthalmology and Visual Sciences, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - A Java
- Divisions of Nephrology and Rheumatology, Department of Medicine, Washington University, St Louis, MO 63110, USA
| | - T E Cox
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - N Tzoumas
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - D H W Steel
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - V G Shuttleworth
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - K Smith-Jackson
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - V Brocklebank
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - H Griffiths
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - A J Cree
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - J P Atkinson
- Divisions of Nephrology and Rheumatology, Department of Medicine, Washington University, St Louis, MO 63110, USA
| | - A J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - D Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| | - B P Morgan
- Division of Infection and Immunity, School of Medicine, Systems Immunity Research Institute, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - K J Marchbank
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - J M Seddon
- Department of Ophthalmology and Visual Sciences, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - D Kavanagh
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| |
Collapse
|
9
|
de Jong S, Gagliardi G, Garanto A, de Breuk A, Lechanteur YTE, Katti S, van den Heuvel LP, Volokhina EB, den Hollander AI. Implications of genetic variation in the complement system in age-related macular degeneration. Prog Retin Eye Res 2021; 84:100952. [PMID: 33610747 DOI: 10.1016/j.preteyeres.2021.100952] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 12/23/2022]
Abstract
Age-related macular degeneration (AMD) is the main cause of vision loss among the elderly in the Western world. While AMD is a multifactorial disease, the complement system was identified as one of the main pathways contributing to disease risk. The strong link between the complement system and AMD was demonstrated by genetic associations, and by elevated complement activation in local eye tissue and in the systemic circulation of AMD patients. Several complement inhibitors have been and are being explored in clinical trials, but thus far with limited success, leaving the majority of AMD patients without treatment options to date. This indicates that there is still a gap of knowledge regarding the functional implications of the complement system in AMD pathogenesis and how to bring these towards clinical translation. Many different experimental set-ups and disease models have been used to study complement activation in vivo and in vitro, and recently emerging patient-derived induced pluripotent stem cells and genome-editing techniques open new opportunities to study AMD disease mechanisms and test new therapeutic strategies in the future. In this review we provide an extensive overview of methods employed to understand the molecular processes of complement activation in AMD pathogenesis. We discuss the findings, advantages and challenges of each approach and conclude with an outlook on how recent, exciting developments can fill in current knowledge gaps and can aid in the development of effective complement-targeting therapeutic strategies in AMD.
Collapse
Affiliation(s)
- Sarah de Jong
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Giuliana Gagliardi
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Pediatrics, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Amalia Children's Hospital, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Anita de Breuk
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Yara T E Lechanteur
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Suresh Katti
- Gemini Therapeutics Inc., Cambridge, MA, 02139, USA
| | - Lambert P van den Heuvel
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Amalia Children's Hospital, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Elena B Volokhina
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Amalia Children's Hospital, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Anneke I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Human Genetics, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands.
| |
Collapse
|
10
|
Barnum SR, Bubeck D, Schein TN. Soluble Membrane Attack Complex: Biochemistry and Immunobiology. Front Immunol 2020; 11:585108. [PMID: 33240274 PMCID: PMC7683570 DOI: 10.3389/fimmu.2020.585108] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
The soluble membrane attack complex (sMAC, a.k.a., sC5b-9 or TCC) is generated on activation of complement and contains the complement proteins C5b, C6, C7, C8, C9 together with the regulatory proteins clusterin and/or vitronectin. sMAC is a member of the MACPF/cholesterol-dependent-cytolysin superfamily of pore-forming molecules that insert into lipid bilayers and disrupt cellular integrity and function. sMAC is a unique complement activation macromolecule as it is comprised of several different subunits. To date no complement-mediated function has been identified for sMAC. sMAC is present in blood and other body fluids under homeostatic conditions and there is abundant evidence documenting changes in sMAC levels during infection, autoimmune disease and trauma. Despite decades of scientific interest in sMAC, the mechanisms regulating its formation in healthy individuals and its biological functions in both health and disease remain poorly understood. Here, we review the structural differences between sMAC and its membrane counterpart, MAC, and examine sMAC immunobiology with respect to its presence in body fluids in health and disease. Finally, we discuss the diagnostic potential of sMAC for diagnostic and prognostic applications and potential utility as a companion diagnostic.
Collapse
Affiliation(s)
| | - Doryen Bubeck
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | |
Collapse
|
11
|
Lashkari K, Teague GC, Beattie U, Betts J, Kumar S, McLaughlin MM, López FJ. Plasma biomarkers of the amyloid pathway are associated with geographic atrophy secondary to age-related macular degeneration. PLoS One 2020; 15:e0236283. [PMID: 32764794 PMCID: PMC7413518 DOI: 10.1371/journal.pone.0236283] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/02/2020] [Indexed: 12/17/2022] Open
Abstract
Geographic atrophy (GA) is an advanced form of dry age-related macular degeneration (AMD), in which local inflammation and hyperactivity of the complement pathway have been implicated in its pathophysiology. This study explores whether any surrogate biomarkers are specifically associated with GA. Plasma from subjects with GA, intermediate dry AMD and non-AMD control were evaluated in 2 cohorts. Cohort 1 was assayed in a 320-analyte Luminex library. Statistical analysis was performed using non-parametric and parametric methods (Kruskal-Wallis, principal component analysis, partial least squares and multivariate analysis of variance (MANOVA) and univariate ANCOVAs). Bioinformatic analysis was conducted and identified connections to the amyloid pathway. Statistically significant biomarkers identified in Cohort 1 were then re-evaluated in Cohort 2 using individual ELISA and multiplexing. Of 320 analytes in Cohort 1, 273 were rendered measurable, of which 56 were identified as changing. Among these markers, 40 were identified in univariate ANCOVAs. Serum amyloid precursor protein (sAPP) was analyzed by a separate ELISA and included in further analyses. The 40 biomarkers, sAPP and amyloid-β (Aβ) (1–42) (included for comparison) were evaluated in Cohort 2. This resulted in 11 statistically significant biomarkers, including sAPP and Aβ(1–40), but not Aβ(1–42). Other biomarkers identified included serum proteases- tissue plasminogen activator, tumor-associated trypsinogen inhibitor, matrix metalloproteinases 7 and 9, and non-proteases- insulin-like growth factor binding protein 6, AXL receptor tyrosine kinase, omentin, pentraxin-3 and osteopontin. Findings suggest that there is a preferential processing of APP to Aβ(1–40) over Aβ(1–42), and a potential role for the carboxylase activity of the γ-secretase protein, which preferentially splices sAPPβ to Aβ(1–40). Other markers are associated with the breakdown and remodeling of the extracellular matrix, and loss of homeostasis, possibly within the photoreceptor-retinal pigment epithelium-choriocapillaris complex. These data suggest novel disease pathways associated with GA pathogenesis and could provide potential novel targets for treatment of GA.
Collapse
Affiliation(s)
- Kameran Lashkari
- Schepens Eye Research Institute, Mass Eye & Ear, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| | - Gianna C. Teague
- Schepens Eye Research Institute, Mass Eye & Ear, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ursula Beattie
- Schepens Eye Research Institute, Mass Eye & Ear, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joanna Betts
- Alternative Discovery & Development, GlaxoSmithKline, King of Prussia, Pennsylvania, United States of America
| | - Sanjay Kumar
- Alternative Discovery & Development, GlaxoSmithKline, King of Prussia, Pennsylvania, United States of America
| | - Megan M. McLaughlin
- Alternative Discovery & Development, GlaxoSmithKline, King of Prussia, Pennsylvania, United States of America
| | - Francisco J. López
- Alternative Discovery & Development, GlaxoSmithKline, King of Prussia, Pennsylvania, United States of America
| |
Collapse
|
12
|
Simmons KT, Mazzilli JL, Mueller-Ortiz SL, Domozhirov AY, Garcia CA, Zsigmond EM, Wetsel RA. Complement Receptor 1 (CR1/CD35)-expressing retinal pigment epithelial cells as a potential therapy for age-related macular degeneration. Mol Immunol 2019; 118:91-98. [PMID: 31862673 DOI: 10.1016/j.molimm.2019.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 10/25/2019] [Accepted: 11/25/2019] [Indexed: 12/30/2022]
Abstract
The purpose of this study was to identify a membrane-bound complement inhibitor that could be overexpressed on retinal pigment epithelial cells (RPE) providing a potential therapy for age-related macular degeneration (AMD). This type of therapy may allow replacement of damaged RPE with cells that are able to limit complement activation in the retina. Complement Receptor 1 (CR1) is a membrane-bound complement inhibitor commonly found on erythrocytes and immune cells. In this study, QPCR and flow cytometry data demonstrated that CR1 is not well-expressed by RPE, indicating that its overexpression may provide extra protection from complement activation. To screen CR1 for this ability, a stable CR1-expressing ARPE19 line was created using a combination of antibiotic selection and FACS. Cell-based assays were used to demonstrate that addition of CR1 inhibited deposition of complement proteins C3b and C6 on the transfected line. In the end, this study identifies CR1 as a complement inhibitor that may be overexpressed on stem cell-derived RPE to create a potential "enhanced" cell therapy for AMD. A combination cell/complement therapy may create transplantable RPE better suited to avoid complement-mediated lysis and limit chronic inflammation in the retina.
Collapse
Affiliation(s)
- Ken T Simmons
- Brown Foundation Institute of Molecular Medicine, Research Center for Immunology and Autoimmune Diseases, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States
| | - John L Mazzilli
- Brown Foundation Institute of Molecular Medicine, Research Center for Immunology and Autoimmune Diseases, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States
| | - Stacey L Mueller-Ortiz
- Brown Foundation Institute of Molecular Medicine, Research Center for Immunology and Autoimmune Diseases, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States
| | - Aleksey Y Domozhirov
- Brown Foundation Institute of Molecular Medicine, Research Center for Immunology and Autoimmune Diseases, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States
| | - Charles A Garcia
- Department of Ophthalmology and Visual Sciences, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States
| | - Eva M Zsigmond
- Brown Foundation Institute of Molecular Medicine, Research Center for Immunology and Autoimmune Diseases, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States
| | - Rick A Wetsel
- Brown Foundation Institute of Molecular Medicine, Research Center for Immunology and Autoimmune Diseases, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, United States.
| |
Collapse
|
13
|
Predictive genetics for AMD: Hype and hopes for genetics-based strategies for treatment and prevention. Exp Eye Res 2019; 191:107894. [PMID: 31862397 DOI: 10.1016/j.exer.2019.107894] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/14/2019] [Accepted: 12/04/2019] [Indexed: 01/18/2023]
Abstract
Age-related macular degeneration (AMD) is a complex disease with multiple genetic and environmental risk factors. In the age of molecular genetics, many investigators have established a link between genes and development or progression of the disease. This later evolved to determine whether phenotypic features of AMD have distinct genetic profiles. Molecular genetics have subsequently been introduced as factors in risk assessment models, increasing the predictive value of these tools. Models seek to predict either development or progression of disease, and different AMD-related genes aid our understanding of these respective features. Several investigators have attempted to link molecular genetics with treatment response, but results and their clinical significance vary. Ocular and systemic biomarkers may interact with established genes, promising future routes of ongoing clinical assessment. Our understanding of AMD molecular genetics is not yet sufficient to recommend routine testing, despite its utility in the research setting. Clinicians must be wary of misusing population-based risk models from genetic and biomarker associations, as they are not necessarily relevant for individual counseling. This review addresses the known uses of predictive genetics, and suggests future directions.
Collapse
|
14
|
Smith EN, D'Antonio-Chronowska A, Greenwald WW, Borja V, Aguiar LR, Pogue R, Matsui H, Benaglio P, Borooah S, D'Antonio M, Ayyagari R, Frazer KA. Human iPSC-Derived Retinal Pigment Epithelium: A Model System for Prioritizing and Functionally Characterizing Causal Variants at AMD Risk Loci. Stem Cell Reports 2019; 12:1342-1353. [PMID: 31080113 PMCID: PMC6565613 DOI: 10.1016/j.stemcr.2019.04.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 10/29/2022] Open
Abstract
We evaluate whether human induced pluripotent stem cell-derived retinal pigment epithelium (iPSC-RPE) cells can be used to prioritize and functionally characterize causal variants at age-related macular degeneration (AMD) risk loci. We generated iPSC-RPE from six subjects and show that they have morphological and molecular characteristics similar to those of native RPE. We generated RNA-seq, ATAC-seq, and H3K27ac ChIP-seq data and observed high similarity in gene expression and enriched transcription factor motif profiles between iPSC-RPE and human fetal RPE. We performed fine mapping of AMD risk loci by integrating molecular data from the iPSC-RPE, adult retina, and adult RPE, which identified rs943080 as the probable causal variant at VEGFA. We show that rs943080 is associated with altered chromatin accessibility of a distal ATAC-seq peak, decreased overall gene expression of VEGFA, and allele-specific expression of a non-coding transcript. Our study thus provides a potential mechanism underlying the association of the VEGFA locus with AMD.
Collapse
Affiliation(s)
- Erin N Smith
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA
| | | | - William W Greenwald
- Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Victor Borja
- Institute for Genomic Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Lana R Aguiar
- Institute for Genomic Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, DF, Brazil
| | - Robert Pogue
- Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, DF, Brazil
| | - Hiroko Matsui
- Institute for Genomic Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Paola Benaglio
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA
| | - Shyamanga Borooah
- Centre for Clinical Brain Sciences, School of Clinical Sciences, The University of Edinburgh, Edinburgh, UK; Shiley Eye Institute, University of California San Diego, La Jolla, CA 92093, USA
| | - Matteo D'Antonio
- Institute for Genomic Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Radha Ayyagari
- Shiley Eye Institute, University of California San Diego, La Jolla, CA 92093, USA
| | - Kelly A Frazer
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Cellular and Molecular Medicine East, 9500 Gilman Drive #0761, La Jolla, CA 92093-0761, USA.
| |
Collapse
|
15
|
Menny A, Serna M, Boyd CM, Gardner S, Joseph AP, Morgan BP, Topf M, Brooks NJ, Bubeck D. CryoEM reveals how the complement membrane attack complex ruptures lipid bilayers. Nat Commun 2018; 9:5316. [PMID: 30552328 PMCID: PMC6294249 DOI: 10.1038/s41467-018-07653-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/12/2018] [Indexed: 01/08/2023] Open
Abstract
The membrane attack complex (MAC) is one of the immune system's first responders. Complement proteins assemble on target membranes to form pores that lyse pathogens and impact tissue homeostasis of self-cells. How MAC disrupts the membrane barrier remains unclear. Here we use electron cryo-microscopy and flicker spectroscopy to show that MAC interacts with lipid bilayers in two distinct ways. Whereas C6 and C7 associate with the outer leaflet and reduce the energy for membrane bending, C8 and C9 traverse the bilayer increasing membrane rigidity. CryoEM reconstructions reveal plasticity of the MAC pore and demonstrate how C5b6 acts as a platform, directing assembly of a giant β-barrel whose structure is supported by a glycan scaffold. Our work provides a structural basis for understanding how β-pore forming proteins breach the membrane and reveals a mechanism for how MAC kills pathogens and regulates cell functions.
Collapse
Affiliation(s)
- Anaïs Menny
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Marina Serna
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
- Spanish National Cancer Research Centre, CNIO, Melchor Fernández Almagro, 3.28029, Madrid, Spain
| | - Courtney M Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Scott Gardner
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Agnel Praveen Joseph
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, OX11 0FA, UK
| | - B Paul Morgan
- Division of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK.
| |
Collapse
|