1
|
Okrój M, Volokhina E. Editorial: Complement and Immunotherapeutics. Front Immunol 2021; 12:663459. [PMID: 33717205 PMCID: PMC7943609 DOI: 10.3389/fimmu.2021.663459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 11/29/2022] Open
Affiliation(s)
- Marcin Okrój
- Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Gdańsk, Poland
| | - Elena Volokhina
- Department of Pediatric Nephrology, Amalia Children's Hospital, Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands.,Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| |
Collapse
|
2
|
Willems E, Lorés-Motta L, Zanichelli A, Suffritti C, van der Flier M, van der Molen RG, Langereis JD, van Drongelen J, van den Heuvel LP, Volokhina E, van de Kar NC, Keizer-Garritsen J, Levin M, Herberg JA, Martinon-Torres F, Wessels HJ, de Breuk A, Fauser S, Hoyng CB, den Hollander AI, de Groot R, van Gool AJ, Gloerich J, de Jonge MI. Quantitative multiplex profiling of the complement system to diagnose complement-mediated diseases. Clin Transl Immunology 2020; 9:e1225. [PMID: 33318796 PMCID: PMC7724921 DOI: 10.1002/cti2.1225] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 09/30/2020] [Revised: 11/16/2020] [Accepted: 11/16/2020] [Indexed: 02/06/2023] Open
Abstract
Objectives Complement deficiencies are difficult to diagnose because of the variability of symptoms and the complexity of the diagnostic process. Here, we applied a novel ‘complementomics’ approach to study the impact of various complement deficiencies on circulating complement levels. Methods Using a quantitative multiplex mass spectrometry assay, we analysed 44 peptides to profile 34 complement proteins simultaneously in 40 healthy controls and 83 individuals with a diagnosed deficiency or a potential pathogenic variant in 14 different complement proteins. Results Apart from confirming near or total absence of the respective protein in plasma of complement‐deficient patients, this mass spectrometry‐based profiling method led to the identification of additional deficiencies. In many cases, partial depletion of the pathway up‐ and/or downstream of the absent protein was measured. This was especially found in patients deficient for complement inhibitors, such as angioedema patients with a C1‐inhibitor deficiency. The added value of complementomics was shown in three patients with poorly defined complement deficiencies. Conclusion Our study shows the potential clinical utility of profiling circulating complement proteins as a comprehensive read‐out of various complement deficiencies. Particularly, our approach provides insight into the intricate interplay between complement proteins due to functional coupling, which contributes to the better understanding of the various disease phenotypes and improvement of care for patients with complement‐mediated diseases.
Collapse
Affiliation(s)
- Esther Willems
- Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.,Radboud Center for Infectious Diseases Radboud University Medical Center Nijmegen The Netherlands.,Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Laura Lorés-Motta
- Department of Ophthalmology Donders Institute for Brain Cognition and Behaviour Radboud University Medical Center Nijmegen The Netherlands
| | - Andrea Zanichelli
- Department of Biomedical and Clinical Sciences Luigi Sacco ASST Fatebenefratelli Sacco University of Milan Milan Italy
| | - Chiara Suffritti
- Department of Biomedical and Clinical Sciences Luigi Sacco ASST Fatebenefratelli Sacco University of Milan Milan Italy
| | - Michiel van der Flier
- Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.,Radboud Center for Infectious Diseases Radboud University Medical Center Nijmegen The Netherlands.,Department of Pediatrics University Medical Center Utrecht Utrecht The Netherlands.,Amalia Children's Hospital Radboud University Medical Center Nijmegen The Netherlands
| | - Renate G van der Molen
- Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Jeroen D Langereis
- Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Joris van Drongelen
- Department of Obstetrics and Gynecology Radboud University Medical Center Nijmegen The Netherlands
| | - Lambert P van den Heuvel
- Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.,Amalia Children's Hospital Radboud University Medical Center Nijmegen The Netherlands
| | - Elena Volokhina
- Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.,Amalia Children's Hospital Radboud University Medical Center Nijmegen The Netherlands
| | - Nicole Caj van de Kar
- Amalia Children's Hospital Radboud University Medical Center Nijmegen The Netherlands
| | - Jenneke Keizer-Garritsen
- Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Michael Levin
- Department of Medicine Section for Paediatrics Imperial College London London UK
| | - Jethro A Herberg
- Department of Medicine Section for Paediatrics Imperial College London London UK
| | - Federico Martinon-Torres
- Translational Pediatrics and Infectious Diseases Instituto de Investigación Sanitaria de Santiago Hospital Clínico Universitario de Santiago Santiago de Compostela Spain
| | - Hans Jtc Wessels
- Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Anita de Breuk
- Department of Ophthalmology Donders Institute for Brain Cognition and Behaviour Radboud University Medical Center Nijmegen The Netherlands
| | - Sascha Fauser
- Department of Ophthalmology University Hospital Cologne Koln Germany.,F. Hoffmann - La Roche AG Basel Switzerland
| | - Carel B Hoyng
- 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
| | - Ronald de Groot
- Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.,Radboud Center for Infectious Diseases Radboud University Medical Center Nijmegen The Netherlands
| | - Alain J van Gool
- Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Jolein Gloerich
- Translational Metabolic Laboratory Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands
| | - Marien I de Jonge
- Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.,Radboud Center for Infectious Diseases Radboud University Medical Center Nijmegen The Netherlands
| |
Collapse
|
3
|
Willems E, Alkema W, Keizer-Garritsen J, Suppers A, van der Flier M, Philipsen RHLA, van den Heuvel LP, Volokhina E, van der Molen RG, Herberg JA, Levin M, Wright VJ, Ahout IML, Ferwerda G, Emonts M, Boeddha NP, Rivero-Calle I, Torres FM, Wessels HJCT, de Groot R, van Gool AJ, Gloerich J, de Jonge MI. Biosynthetic homeostasis and resilience of the complement system in health and infectious disease. EBioMedicine 2019; 45:303-313. [PMID: 31262714 PMCID: PMC6642076 DOI: 10.1016/j.ebiom.2019.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [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: 04/08/2019] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND The complement system is a central component of the innate immune system. Constitutive biosynthesis of complement proteins is essential for homeostasis. Dysregulation as a consequence of genetic or environmental cues can lead to inflammatory syndromes or increased susceptibility to infection. However, very little is known about steady state levels in children or its kinetics during infection. METHODS With a newly developed multiplex mass spectrometry-based method we analyzed the levels of 32 complement proteins in healthy individuals and in a group of pediatric patients infected with bacterial or viral pathogens. FINDINGS In plasma from young infants we found reduced levels of C4BP, ficolin-3, factor B, classical pathway components C1QA, C1QB, C1QC, C1R, and terminal pathway components C5, C8, C9, as compared to healthy adults; whereas the majority of complement regulating (inhibitory) proteins reach adult levels at very young age. Both viral and bacterial infections in children generally lead to a slight overall increase in complement levels, with some exceptions. The kinetics of complement levels during invasive bacterial infections only showed minor changes, except for a significant increase and decrease of CRP and clusterin, respectively. INTERPRETATION The combination of lower levels of activating and higher levels of regulating complement proteins, would potentially raise the threshold of activation, which might lead to suppressed complement activation in the first phase of life. There is hardly any measurable complement consumption during bacterial or viral infection. Altogether, expression of the complement proteins appears surprisingly stable, which suggests that the system is continuously replenished. FUND: European Union's Horizon 2020, project PERFORM, grant agreement No. 668303.
Collapse
Affiliation(s)
- Esther Willems
- Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands; Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
| | - Wynand Alkema
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jenneke Keizer-Garritsen
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Anouk Suppers
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Michiel van der Flier
- Department of Pediatrics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ria H L A Philipsen
- Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lambert P van den Heuvel
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands; Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elena Volokhina
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands; Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Renate G van der Molen
- Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jethro A Herberg
- Department of Medicine, Section for Paediatrics, Imperial College London, London, UK
| | - Michael Levin
- Department of Medicine, Section for Paediatrics, Imperial College London, London, UK
| | - Victoria J Wright
- Department of Medicine, Section for Paediatrics, Imperial College London, London, UK
| | - Inge M L Ahout
- Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Gerben Ferwerda
- Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marieke Emonts
- Department of Paediatric Immunology, Infectious Diseases and Allergy, Great North Children's Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK; Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK; NIHR Newcastle Biomedical Research Centre based at Newcastle upon Tyne Hospitals NHS Trust and Newcastle University, Newcastle upon Tyne, UK
| | - Navin P Boeddha
- Intensive Care and Department of Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Irene Rivero-Calle
- Translational Pediatrics and Infectious Diseases, Hospital Clínico Universitario de Santiago, Instituto de Investigación Sanitaria de Santiago, Santiago de Compostela, Galicia, Spain
| | - Federico Martinon Torres
- Translational Pediatrics and Infectious Diseases, Hospital Clínico Universitario de Santiago, Instituto de Investigación Sanitaria de Santiago, Santiago de Compostela, Galicia, Spain
| | - Hans J C T Wessels
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Ronald de Groot
- Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alain J van Gool
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Jolein Gloerich
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Marien I de Jonge
- Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| |
Collapse
|
4
|
Michels M, van de Kar N, Okrój M, Blom A, van Kraaij S, van den Heuvel L, Volokhina E. Two interesting cases of prolonged classical pathway convertase activity: C4NeF and a non-autoantibody serum factor. Mol Immunol 2018. [DOI: 10.1016/j.molimm.2018.06.241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
5
|
de Jong S, Volokhina E, Nilsson S, Bakker B, van den Heuvel L, Blom A, de Jong E, Hollander AD. Functional analysis of 126 rare missense variants in CFI associated with age-related macular degeneration, atypical uremic syndrome. Mol Immunol 2018. [DOI: 10.1016/j.molimm.2018.06.259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
6
|
van den Heuvel L, Sarlea A, Duineveld C, Mollnes TE, Wijnsma K, Wetzels J, van de Kar N, Volokhina E. Eculizumab therapy monitoring: Residual hemolysis in alternative pathway test is not caused by C5 activity. Mol Immunol 2018. [DOI: 10.1016/j.molimm.2018.06.240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
7
|
Osborne AJ, Breno M, Borsa NG, Bu F, Frémeaux-Bacchi V, Gale DP, van den Heuvel LP, Kavanagh D, Noris M, Pinto S, Rallapalli PM, Remuzzi G, Rodríguez de Cordoba S, Ruiz A, Smith RJH, Vieira-Martins P, Volokhina E, Wilson V, Goodship THJ, Perkins SJ. Statistical Validation of Rare Complement Variants Provides Insights into the Molecular Basis of Atypical Hemolytic Uremic Syndrome and C3 Glomerulopathy. J Immunol 2018; 200:2464-2478. [PMID: 29500241 DOI: 10.4049/jimmunol.1701695] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/31/2018] [Indexed: 01/02/2023]
Abstract
Atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy (C3G) are associated with dysregulation and overactivation of the complement alternative pathway. Typically, gene analysis for aHUS and C3G is undertaken in small patient numbers, yet it is unclear which genes most frequently predispose to aHUS or C3G. Accordingly, we performed a six-center analysis of 610 rare genetic variants in 13 mostly complement genes (CFH, CFI, CD46, C3, CFB, CFHR1, CFHR3, CFHR4, CFHR5, CFP, PLG, DGKE, and THBD) from >3500 patients with aHUS and C3G. We report 371 novel rare variants (RVs) for aHUS and 82 for C3G. Our new interactive Database of Complement Gene Variants was used to extract allele frequency data for these 13 genes using the Exome Aggregation Consortium server as the reference genome. For aHUS, significantly more protein-altering rare variation was found in five genes CFH, CFI, CD46, C3, and DGKE than in the Exome Aggregation Consortium (allele frequency < 0.01%), thus correlating these with aHUS. For C3G, an association was only found for RVs in C3 and the N-terminal C3b-binding or C-terminal nonsurface-associated regions of CFH In conclusion, the RV analyses showed nonrandom distributions over the affected proteins, and different distributions were observed between aHUS and C3G that clarify their phenotypes.
Collapse
Affiliation(s)
- Amy J Osborne
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - Matteo Breno
- Centro di Ricerche Cliniche per le Malattie Rare "Aldo e Cele Daccò," IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri," 24020 Ranica Bergamo, Italy
| | - Nicolo Ghiringhelli Borsa
- Molecular Otolaryngology and Renal Research Laboratories, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Fengxiao Bu
- Molecular Otolaryngology and Renal Research Laboratories, Carver College of Medicine, University of Iowa, Iowa City, IA 52242.,Medical Genetics Center, Southwest Hospital, Chongqing 400038, China
| | - Véronique Frémeaux-Bacchi
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service d'Immunologie Biologique, 75015 Paris, France
| | - Daniel P Gale
- Centre for Nephrology, Royal Free Hospital, University College London, London NW3 2QG, United Kingdom
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.,Department of Pediatric Nephrology, Department of Growth and Regeneration, University Hospital Leuven, 3000 Leuven, Belgium
| | - David Kavanagh
- The National Renal Complement Therapeutics Centre, Newcastle upon Tyne NE1 4LP, United Kingdom.,Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, United Kingdom
| | - Marina Noris
- Centro di Ricerche Cliniche per le Malattie Rare "Aldo e Cele Daccò," IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri," 24020 Ranica Bergamo, Italy
| | - Sheila Pinto
- Department of Cellular and Molecular Medicine, Center for Biological Research and Center for Biomedical Network Research on Rare Diseases, 28040 Madrid, Spain
| | - Pavithra M Rallapalli
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - Giuseppe Remuzzi
- Centro di Ricerche Cliniche per le Malattie Rare "Aldo e Cele Daccò," IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri," 24020 Ranica Bergamo, Italy.,Department of Biomedical and Clinical Sciences, University of Milan, 20122 Milan, Italy; and
| | - Santiago Rodríguez de Cordoba
- Department of Cellular and Molecular Medicine, Center for Biological Research and Center for Biomedical Network Research on Rare Diseases, 28040 Madrid, Spain
| | - Angela Ruiz
- Department of Cellular and Molecular Medicine, Center for Biological Research and Center for Biomedical Network Research on Rare Diseases, 28040 Madrid, Spain
| | - Richard J H Smith
- Molecular Otolaryngology and Renal Research Laboratories, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Paula Vieira-Martins
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service d'Immunologie Biologique, 75015 Paris, France
| | - Elena Volokhina
- Department of Pediatric Nephrology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands
| | - Valerie Wilson
- Northern Molecular Genetics Service, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne NE1 3BZ, United Kingdom
| | - Timothy H J Goodship
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, United Kingdom
| | - Stephen J Perkins
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom;
| |
Collapse
|
8
|
Urban A, Borowska A, Felberg A, van den Heuvel L, Stasiłojć G, Volokhina E, Okrój M. Gain of function mutant of complement factor B K323E mimics pathogenic C3NeF autoantibodies in convertase assays. Autoimmunity 2018; 51:18-24. [PMID: 29308663 DOI: 10.1080/08916934.2017.1423286] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Complement convertases are enzymatic complexes, which play a critical role in propagation and amplification of the complement cascade. Under physiological conditions, convertases decay shortly after being formed in either spontaneous or inhibitor-driven process. Prolongation of their half-life by C3NeF autoantibodies that prevent convertase dissociation results in pathogenic condition often manifested by renal diseases. However, the diagnosis of convertase abnormalities is difficult due to the labile nature of these enzymes and low credibility of existing methods. Only recently, two-step functional assays employing C5-depleted serum or C5 inhibitors were introduced. Their advantage is convertase formation in the physiological milieu of whole serum and the drawback is inter-assay variability due to variations in rabbit erythrocytes used for the haemolysis-based readout. Abovementioned problems demand the application of the internal standard in each experiment. Obtaining a defined preparation of autoantibodies is complicated due to ethical and practical considerations. We found that recombinant, his-tagged factor B (fB) variant K323E retains full hemolytic activity and possess the ability to form convertases with prolonged half-life either in fB-depleted serum or when mixed with normal human serum. Such dominant character of K323E mutation allows using recombinant protein as a reference in functional convertase assays, not limited to these using rabbit erythrocytes. Additionally, our results demonstrate that gain of function mutations in complement components mimic the phenotype of C3NeF. Hence, patients with such "genetic C3NeF" would not benefit from B-cell depletion (e.g. by rituximab) and therefore should be properly diagnosed in order to choose suitable therapeutic intervention.
Collapse
Affiliation(s)
- Aleksandra Urban
- a Department of Medical Biotechnology , Intercollegiate Faculty of Biotechnology UG-GUMED , Gdańsk , Poland
| | - Anna Borowska
- a Department of Medical Biotechnology , Intercollegiate Faculty of Biotechnology UG-GUMED , Gdańsk , Poland
| | - Anna Felberg
- a Department of Medical Biotechnology , Intercollegiate Faculty of Biotechnology UG-GUMED , Gdańsk , Poland
| | - Lambertus van den Heuvel
- b Department of Pediatric Nephrology , Radboud University Medical Center , Nijmegen , The Netherlands.,c Department of Laboratory Medicine , Radboud University Medical Center , Nijmegen , The Netherlands.,d Department of Pediatric Nephrology , University Hospitals Leuven , Leuven , Belgium.,e Department of Growth and Regeneration , University Hospitals Leuven , Leuven , Belgium
| | - Grzegorz Stasiłojć
- a Department of Medical Biotechnology , Intercollegiate Faculty of Biotechnology UG-GUMED , Gdańsk , Poland
| | - Elena Volokhina
- b Department of Pediatric Nephrology , Radboud University Medical Center , Nijmegen , The Netherlands.,c Department of Laboratory Medicine , Radboud University Medical Center , Nijmegen , The Netherlands
| | - Marcin Okrój
- a Department of Medical Biotechnology , Intercollegiate Faculty of Biotechnology UG-GUMED , Gdańsk , Poland
| |
Collapse
|
9
|
Michels M, Okroj M, Blom A, van Kraaij S, van de Kar N, Volokhina E, van den Heuvel B. Detection of convertase-stabilizing factors in patients with complement-mediated renal diseases: Translation to a diagnostic approach. Mol Immunol 2017. [DOI: 10.1016/j.molimm.2017.06.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
10
|
Volokhina E, Wijnsma K, van der Molen R, Roeleveld N, van der Velden T, Goertz J, Sweep F, Brüggemann RJ, Wetzels J, van de Kar N, van den Heuvel L. Eculizumab Dosing Regimen in Atypical HUS: Possibilities for Individualized Treatment. Clin Pharmacol Ther 2017; 102:671-678. [DOI: 10.1002/cpt.686] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/03/2017] [Accepted: 03/08/2017] [Indexed: 01/30/2023]
Affiliation(s)
- E Volokhina
- Department of Pediatric Nephrology; Amalia Children's Hospital, Radboud University Medical Center; Nijmegen The Netherlands
- Department of Laboratory Medicine; Radboud University Medical Center; Nijmegen The Netherlands
| | - K Wijnsma
- Department of Pediatric Nephrology; Amalia Children's Hospital, Radboud University Medical Center; Nijmegen The Netherlands
| | - R van der Molen
- Department of Laboratory Medicine; Radboud University Medical Center; Nijmegen The Netherlands
| | - N Roeleveld
- Department of Pediatric Nephrology; Amalia Children's Hospital, Radboud University Medical Center; Nijmegen The Netherlands
- Department of Health Evidence; Radboud University Medical Center; Nijmegen The Netherlands
| | - T van der Velden
- Department of Pediatric Nephrology; Amalia Children's Hospital, Radboud University Medical Center; Nijmegen The Netherlands
| | - J Goertz
- Department of Laboratory Medicine; Radboud University Medical Center; Nijmegen The Netherlands
| | - F Sweep
- Department of Laboratory Medicine; Radboud University Medical Center; Nijmegen The Netherlands
| | - RJ Brüggemann
- Department of Pharmacy; Radboud University Medical Center; Nijmegen The Netherlands
| | - J Wetzels
- Department of Nephrology; Radboud University Medical Center; Nijmegen The Netherlands
| | - N van de Kar
- Department of Pediatric Nephrology; Amalia Children's Hospital, Radboud University Medical Center; Nijmegen The Netherlands
| | - L van den Heuvel
- Department of Pediatric Nephrology; Amalia Children's Hospital, Radboud University Medical Center; Nijmegen The Netherlands
- Department of Laboratory Medicine; Radboud University Medical Center; Nijmegen The Netherlands
- Department of Pediatrics; University Hospitals Leuven; Leuven Belgium
| |
Collapse
|
11
|
Gustavsen A, Bergseth G, Volokhina E, van den Heuvel L, Skattum L, Mollnes T, Barratt-Due A. Eculizumab treatment in pregnancy complicated with APS – Effects on mother and infant. Immunobiology 2016. [DOI: 10.1016/j.imbio.2016.06.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
12
|
Volokhina E, Tahir OE, Kömhoff M, Morre S, van Furth M, Singh B, Okroj M, van de Kar N, Riesbeck K, Blom A, van den Heuvel L. Genetic changes predisposing to complement dysregulation and infection may play role in a case of atypical hemolytic uremic syndrome. Immunobiology 2016. [DOI: 10.1016/j.imbio.2016.06.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
Emirova K, Volokhina E, Tolstova E, van den Heuvel B. Recovery of renal function after long-term dialysis and resolution of cardiomyopathy in a patient with aHUS receiving eculizumab. BMJ Case Rep 2016; 2016:bcr-2015-213928. [PMID: 26880823 DOI: 10.1136/bcr-2015-213928] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We present the case of a 18-month-old girl with renal and cardiac manifestations of atypical haemolytic uraemic syndrome (aHUS), and a novel complement factor H mutation. Transient haematological remission was achieved with intensive plasmapheresis, but cardiac function deteriorated and renal function was not restored. Initiation of eculizumab after 6 months of dialysis significantly improved organ function. At 43 months after presentation, haematological values had normalised and cardiac function had improved. Dialysis was discontinued after 10 months (the longest reported time in a patient with aHUS) and the estimated glomerular filtration rate had recovered to 70 mL/min/1.73 m(2). In conclusion, treatment of aHUS with eculizumab, even after long-term dialysis, can significantly improve renal function. Discontinuation of dialysis and resolution of cardiac function has implications on the potential recovery and treatment choice of such patients. Earlier initiation of eculizumab, however, might have prevented the irreversible renal sclerosis and cardiac dysfunction.
Collapse
Affiliation(s)
- Khadizha Emirova
- The AI Evdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation
| | - Elena Volokhina
- Department of Paediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Evgenia Tolstova
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bert van den Heuvel
- Department of Paediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| |
Collapse
|
15
|
Wijnsma KL, van Bommel SAM, van der Velden T, Volokhina E, Schreuder MF, van den Heuvel LP, van de Kar NCAJ. Fecal diagnostics in combination with serology: best test to establish STEC-HUS. Pediatr Nephrol 2016; 31:2163-70. [PMID: 27240858 PMCID: PMC5039220 DOI: 10.1007/s00467-016-3420-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [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] [Received: 01/22/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 12/17/2022]
Abstract
BACKGROUND In the majority of pediatric patients, the hemolytic-uremic syndrome (HUS) is caused by an infection with Shiga toxin-producing Escherichia coli (STEC), mostly serotype O157. It is important to discriminate between HUS caused by STEC and complement-mediated HUS (atypical HUS) due to differences in treatment and outcome. As STEC and its toxins can only be detected in the patient's stool for a short period of time after disease onset, the infectious agent may go undetected using only fecal diagnostic tests. Serum antibodies to lipopolysaccharide (LPS) of STEC persist for several weeks and may therefore be of added value in the diagnosis of STEC. METHODS All patients with clinical STEC-HUS who were treated at Radboud University Medical Center between 1990 and 2014 were included in this retrospective single-center study. Clinical and diagnostic microbiological data were collected. Immunoglobulin M (IgM) antibodies against LPS of STEC serotype O157 were detected by a serological assay (ELISA). RESULTS Data from 65 patients weres available for analysis. Fecal diagnostic testing found evidence of an STEC infection in 34/63 patients (54 %). Serological evidence of STEC O157 was obtained in an additional 16 patients. This is an added value of 23 % (p < 0.0001) when the serological antibody assay is used in addition to standard fecal diagnostic tests to confirm the diagnosis STEC-HUS. This added value becomes especially apparent when the tests are performed more than 7 days after the initial manifestation of the gastrointestinal symptoms. CONCLUSIONS The serological anti-O157 LPS assay clearly makes a positive contribution when used in combination with standard fecal diagnostic tests to diagnose STEC-HUS and should be incorporated in clinical practice.
Collapse
Affiliation(s)
- Kioa L Wijnsma
- Department of Pediatric Nephrology, Radboudumc Amalia Children's Hospital, Radboud University Medical Center, P.O. Box 1901, 6500 HB, Nijmegen, Netherlands.
| | - Sheila A M van Bommel
- Department of Pediatric Nephrology, Radboudumc Amalia Children's Hospital, Radboud University Medical Center, P.O. Box 1901, 6500 HB, Nijmegen, Netherlands
| | - Thea van der Velden
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Elena Volokhina
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Michiel F Schreuder
- Department of Pediatric Nephrology, Radboudumc Amalia Children's Hospital, Radboud University Medical Center, P.O. Box 1901, 6500 HB, Nijmegen, Netherlands
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology, Radboudumc Amalia Children's Hospital, Radboud University Medical Center, P.O. Box 1901, 6500 HB, Nijmegen, Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Pediatrics, University Hospital Leuven, Leuven, Belgium
| | - Nicole C A J van de Kar
- Department of Pediatric Nephrology, Radboudumc Amalia Children's Hospital, Radboud University Medical Center, P.O. Box 1901, 6500 HB, Nijmegen, Netherlands
| |
Collapse
|
16
|
Volokhina E. Novel Sequence Variation Affects GPIbα in Post-diarrheal Hemolytic Uremic Syndrome. Nephrol Ther 2014. [DOI: 10.4172/2161-0959.s11-007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
17
|
Volokhina E, Westra D, Xue X, Gros P, van de Kar N, van den Heuvel L. Novel C3 mutation p.Lys65Gln in aHUS affects complement factor H binding. Pediatr Nephrol 2012; 27:1519-24. [PMID: 22669319 PMCID: PMC3407361 DOI: 10.1007/s00467-012-2183-z] [Citation(s) in RCA: 32] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 12/25/2022]
Abstract
BACKGROUND Atypical hemolytic uremic syndrome (aHUS) is associated with mutations affecting complement proteins and regulators and with autoantibodies against complement factor H (CFH). Approximately half of the aHUS patients progress to end-stage renal disease. DNA analysis of the risk factor genes is important for prognosis of aHUS recurrence after renal transplantation. METHODS Mutational screening of C3 encoding the central complement component was performed by Sanger sequencing in 70 aHUS patients. Mutated and wild type recombinant C3b proteins were produced and their affinity to CFH was analyzed by ELISA. RESULTS A single novel missense change p.Lys65Gln in C3 was found in 3 aHUS patients. The alteration leads to decreased binding of C3b to CFH in vitro. All three patients acquired the illness as adults and had a first aHUS episode after renal transplantation or suffered recurrence of the disease after transplantation. CONCLUSIONS The novel C3 change was found in 3 aHUS patients. It results in decreased C3b binding to CFH and thus might lead to impaired C3b inactivation in vivo. The p.Lys65Gln is likely to be associated with aHUS after kidney transplantation and, therefore, might be an important prognostic factor.
Collapse
Affiliation(s)
- Elena Volokhina
- Department of Pediatric Nephrology (804), Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Dineke Westra
- Department of Pediatric Nephrology (804), Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Xiaoguang Xue
- Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, the Netherlands
| | - Piet Gros
- Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, the Netherlands
| | - Nicole van de Kar
- Department of Pediatric Nephrology (804), Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lambert van den Heuvel
- Department of Pediatric Nephrology (804), Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands ,Department of Laboratory Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands ,Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium
| |
Collapse
|
18
|
Westra D, Volokhina E, van der Heijden E, Vos A, Huigen M, Jansen J, van Kaauwen E, van der Velden T, van de Kar N, van den Heuvel L. Genetic disorders in complement (regulating) genes in patients with atypical haemolytic uraemic syndrome (aHUS). Nephrol Dial Transplant 2010. [PMID: 20106822 DOI: 10.1093/ndt/gfq01021902819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Atypical HUS (aHUS) is thought to be caused by predisposing mutations in genes encoding complement (regulating) proteins, such as Factor H (CFH), Factor I (IF), membrane co-factor protein (MCP) and Factor B (FB), or by auto-antibodies against CFH (alphaFH) in combination with a homozygous polymorphic deletion of the genes encoding Complement Factor H-related 1 and 3 (DeltaCFHR1/3). The clinical impact of this knowledge is high, as it might be a prognostic factor for the outcome of renal transplantations and kidney donations. METHODS Mutational screening, by means of PCR and DNA sequencing, is performed in the above-mentioned genes in a group of 72 aHUS patients. Also, the presence of alphaFH and DeltaCFHR1/3 was tested in patients and controls. RESULTS In 23 patients, a genetic aberration in at least one gene or the presence of alphaFH was found. A heterozygous mutation was observed in CFH in nine patients, in IF in seven patients and in MCP in three patients. No mutations were observed in FB. Seven patients presented alphaFH, of whom five also carried DeltaCFHR1/3. Three patients carried a combined mutation (two patients: IF and MCP; one patient: IF, alphaFH and DeltaCFHR1/3). A significant difference between patients and controls was detected for the presence of all three associated polymorphisms in CFH. CONCLUSIONS Genetic abnormalities or the presence of alphaFH were detected in 31.9% of the aHUS patients. Furthermore, bigenic mutations were present, indicating that routine DNA mutation analysis of all complement factors associated with aHUS is important.
Collapse
Affiliation(s)
- Dineke Westra
- Department of Paediatric Nephrology, Radboud University Nijmegen Medical Centre (RUNMC), P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Uzunbajakava N, Lenferink A, Kraan Y, Volokhina E, Vrensen G, Greve J, Otto C. Nonresonant confocal Raman imaging of DNA and protein distribution in apoptotic cells. Biophys J 2003; 84:3968-81. [PMID: 12770902 PMCID: PMC1302978 DOI: 10.1016/s0006-3495(03)75124-8] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2002] [Accepted: 01/28/2003] [Indexed: 01/04/2023] Open
Abstract
Nonresonant confocal Raman imaging has been used to map the DNA and the protein distributions in individual single human cells. The images are obtained on an improved homebuilt confocal Raman microscope. After statistical analysis, using singular value decomposition, the Raman images are reconstructed from the spectra covering the fingerprint region. The data are obtained at a step interval of approximately 250 nm and cover a field from 8- to 15- micro m square in size. Dwell times at each pixel are between 0.5 and 2 s, depending on the nature and the state of the cell under investigation. High quality nonresonant Raman images can only be obtained under these conditions using continuous wave high laser powers between 60 and 120 mW. We will present evidence that these laser powers can still safely be used to recover the chemical distributions in fixed cells. The developed Raman imaging method is used to image directly, i.e., without prior labeling, the nucleotide condensation and the protein distribution in the so-called nuclear fragments of apoptotic HeLa cells. In the control (nonapoptotic) HeLa cells, we show, for the first time by Raman microspectroscopy, the presence of the RNA in a cell nucleus.
Collapse
Affiliation(s)
- N Uzunbajakava
- Biomedical Technology Institute, Department of Applied Physics, University of Twente, Enschede, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|