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Espino-Gonzalez E, Dalbram E, Mounier R, Gondin J, Farup J, Jessen N, Treebak JT. Impaired skeletal muscle regeneration in diabetes: From cellular and molecular mechanisms to novel treatments. Cell Metab 2024; 36:1204-1236. [PMID: 38490209 DOI: 10.1016/j.cmet.2024.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 01/10/2024] [Accepted: 02/22/2024] [Indexed: 03/17/2024]
Abstract
Diabetes represents a major public health concern with a considerable impact on human life and healthcare expenditures. It is now well established that diabetes is characterized by a severe skeletal muscle pathology that limits functional capacity and quality of life. Increasing evidence indicates that diabetes is also one of the most prevalent disorders characterized by impaired skeletal muscle regeneration, yet underlying mechanisms and therapeutic treatments remain poorly established. In this review, we describe the cellular and molecular alterations currently known to occur during skeletal muscle regeneration in people with diabetes and animal models of diabetes, including its associated comorbidities, e.g., obesity, hyperinsulinemia, and insulin resistance. We describe the role of myogenic and non-myogenic cell types on muscle regeneration in conditions with or without diabetes. Therapies for skeletal muscle regeneration and gaps in our knowledge are also discussed, while proposing future directions for the field.
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Affiliation(s)
- Ever Espino-Gonzalez
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Emilie Dalbram
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Rémi Mounier
- Institut NeuroMyoGène, Unité Physiopathologie et Génétique du Neurone et du Muscle, Université Claude Bernard Lyon 1, CNRS UMR 5261, Inserm U1315, Univ Lyon, Lyon, France
| | - Julien Gondin
- Institut NeuroMyoGène, Unité Physiopathologie et Génétique du Neurone et du Muscle, Université Claude Bernard Lyon 1, CNRS UMR 5261, Inserm U1315, Univ Lyon, Lyon, France
| | - Jean Farup
- Department of Biomedicine, Aarhus University, Aarhus 8000, Denmark; Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus 8200, Denmark
| | - Niels Jessen
- Department of Biomedicine, Aarhus University, Aarhus 8000, Denmark; Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus 8200, Denmark; Department of Clinical Pharmacology, Aarhus University Hospital, Aarhus 8200, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark.
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Wu M, Jia BB, Li MF. Complement C3 and Activated Fragment C3a Are Involved in Complement Activation and Anti-Bacterial Immunity. Front Immunol 2022; 13:813173. [PMID: 35281048 PMCID: PMC8913944 DOI: 10.3389/fimmu.2022.813173] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 02/04/2022] [Indexed: 12/13/2022] Open
Abstract
In the complement system, C3 is a central component in complement activation, immune defense and immune regulation. In all pathways of complement activation, the pivotal step is conversion of the component C3 to C3b and C3a, which is responsible to eliminate the pathogen and opsonization. In this study, we examined the immunological properties of C3 and its activated fragment C3a from Japanese flounder (Paralichthys olivaceus) (PoC3 and PoC3a), a teleost species with important economic value. PoC3 is composed of 1655 amino acid residues, contains the six domains and highly conserved GCGEQ sequence of the C3 family. We found that PoC3 expression occurred in nine different tissues and was upregulated by bacterial challenge. In serum, PoC3 was able to bind to a broad-spectrum of bacteria, and purified native PoC3 could directly kill specific pathogen. When PoC3 expression in Japanese flounder was knocked down by siRNA, serum complement activity was significantly decreased, and bacterial replication in fish tissues was significantly increased. Recombinant PoC3a (rPoC3a) exhibited apparent binding capacities to bacteria and Japanese flounder peripheral blood leukocytes (PBL) and induce chemotaxis of PBL. Japanese flounder administered rPoC3a exhibited enhanced resistance against bacterial infection. Taken together, these results indicate that PoC3 is likely a key factor of complement activation, and PoC3 and PoC3a are required for optimal defense against bacterial infection in teleost.
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Affiliation(s)
- Meng Wu
- Chinese Academy of Sciences (CAS) & Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Bei-bei Jia
- Chinese Academy of Sciences (CAS) & Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Mo-fei Li
- Chinese Academy of Sciences (CAS) & Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- *Correspondence: Mo-fei Li,
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Appiah SA, Foxx CL, Langgartner D, Palmer A, Zambrano CA, Braumüller S, Schaefer EJ, Wachter U, Elam BL, Radermacher P, Stamper CE, Heinze JD, Salazar SN, Luthens AK, Arnold AL, Reber SO, Huber-Lang M, Lowry CA, Halbgebauer R. Evaluation of the gut microbiome in association with biological signatures of inflammation in murine polytrauma and shock. Sci Rep 2021; 11:6665. [PMID: 33758228 PMCID: PMC7988149 DOI: 10.1038/s41598-021-85897-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/05/2021] [Indexed: 12/03/2022] Open
Abstract
Severe injuries are frequently accompanied by hemorrhagic shock and harbor an increased risk for complications. Local or systemic inflammation after trauma/hemorrhage may lead to a leaky intestinal epithelial barrier and subsequent translocation of gut microbiota, potentially worsening outcomes. To evaluate the extent with which trauma affects the gut microbiota composition, we performed a post hoc analysis of a murine model of polytrauma and hemorrhage. Four hours after injury, organs and plasma samples were collected, and the diversity and composition of the cecal microbiome were evaluated using 16S rRNA gene sequencing. Although cecal microbial alpha diversity and microbial community composition were not found to be different between experimental groups, norepinephrine support in shock animals resulted in increased alpha diversity, as indicated by higher numbers of distinct microbial features. We observed that the concentrations of proinflammatory mediators in plasma and intestinal tissue were associated with measures of microbial alpha and beta diversity and the presence of specific microbial drivers of inflammation, suggesting that the composition of the gut microbiome at the time of trauma, or shortly after trauma exposure, may play an important role in determining physiological outcomes. In conclusion, we found associations between measures of gut microbial alpha and beta diversity and the severity of systemic and local gut inflammation. Furthermore, our data suggest that four hours following injury is too early for development of global changes in the alpha diversity or community composition of the intestinal microbiome. Future investigations with increased temporal-spatial resolution are needed in order to fully elucidate the effects of trauma and shock on the gut microbiome, biological signatures of inflammation, and proximal and distal outcomes.
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Affiliation(s)
- Sandra A Appiah
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Christine L Foxx
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Dominik Langgartner
- Laboratory for Molecular Psychosomatics, Department of Psychosomatic Medicine and Psychotherapy, University Ulm, 89081, Ulm, Germany
| | - Annette Palmer
- Institute of Clinical and Experimental Trauma Immunology, Centre for Biomedical Research, University Hospital Ulm, University Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany
| | - Cristian A Zambrano
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Sonja Braumüller
- Institute of Clinical and Experimental Trauma Immunology, Centre for Biomedical Research, University Hospital Ulm, University Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany
| | - Evan J Schaefer
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Ulrich Wachter
- Institute for Anaesthesiological Pathophysiology and Process Development, University of Ulm, Ulm, Germany
| | - Brooke L Elam
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Peter Radermacher
- Institute for Anaesthesiological Pathophysiology and Process Development, University of Ulm, Ulm, Germany
| | - Christopher E Stamper
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Jared D Heinze
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Stephanie N Salazar
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Amalia K Luthens
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Andrea L Arnold
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Stefan O Reber
- Laboratory for Molecular Psychosomatics, Department of Psychosomatic Medicine and Psychotherapy, University Ulm, 89081, Ulm, Germany
| | - Markus Huber-Lang
- Institute of Clinical and Experimental Trauma Immunology, Centre for Biomedical Research, University Hospital Ulm, University Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany.
| | - Christopher A Lowry
- Department of Integrative Physiology and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, 80309, USA
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA
- Department of Physical Medicine and Rehabilitation and Center for Neuroscience, University of Colorado Anschutz, Medical Campus, Aurora, CO, 80045, USA
- Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), Rocky Mountain Regional Veterans Affairs Medical Center (RMRVAMC), Aurora, CO, 80045, USA
- Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE), Aurora, CO, 80045, USA
| | - Rebecca Halbgebauer
- Institute of Clinical and Experimental Trauma Immunology, Centre for Biomedical Research, University Hospital Ulm, University Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany
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Yang W, Hu P. Skeletal muscle regeneration is modulated by inflammation. J Orthop Translat 2018; 13:25-32. [PMID: 29662788 PMCID: PMC5892385 DOI: 10.1016/j.jot.2018.01.002] [Citation(s) in RCA: 154] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 01/08/2018] [Accepted: 01/09/2018] [Indexed: 01/01/2023] Open
Abstract
Skeletal muscle regeneration is a complex process orchestrated by multiple steps. Recent findings indicate that inflammatory responses could play central roles in bridging initial muscle injury responses and timely muscle injury reparation. The various types of immune cells and cytokines have crucial roles in muscle regeneration process. In this review, we briefly summarise the functions of acute inflammation in muscle regeneration. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE Immune system is closely relevant to the muscle regeneration. Understanding the mechanisms of inflammation in muscle regeneration is therefore critical for the development of effective regenerative, and therapeutic strategies in muscular disorders. This review provides information for muscle regeneration research regarding the effects of inflammation on muscle regeneration.
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Affiliation(s)
| | - Ping Hu
- State Key Laboratory of Cell Biology, Center of Excellence in Molecular and Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, China
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Coulthard LG, Woodruff TM. Is the complement activation product C3a a proinflammatory molecule? Re-evaluating the evidence and the myth. THE JOURNAL OF IMMUNOLOGY 2015; 194:3542-8. [PMID: 25848071 DOI: 10.4049/jimmunol.1403068] [Citation(s) in RCA: 194] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The complement activation product C3a is often described as a proinflammatory mediator, alongside its downstream cousin, C5a. However, emerging studies show that C3a has several anti-inflammatory facets in vivo. For example, in the acute inflammatory response, C3a acts in direct opposition to C5a, through preventing the accumulation of neutrophils in inflamed tissues by independently regulating their mobilization. This acute, protective, and opposing activity of C3a to C5a is also illustrated in models of septicemia. In this article, we reinvestigate the discovery and original classification of C3a as a proinflammatory mediator and highlight the emerging studies demonstrating anti-inflammatory effects for C3a in the immune response. It is our hope that this review illuminates these apparently contradictory roles for C3a and challenges the general dogma surrounding C3a, which, historically, has ubiquitously been described as a proinflammatory mediator. In light of this, we urge investigators to use "inflammatory modulator" as the descriptor for C3a.
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Affiliation(s)
- Liam G Coulthard
- School of Biomedical Sciences, University of Queensland, St. Lucia 4072, Queensland, Australia
| | - Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, St. Lucia 4072, Queensland, Australia
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Zipfel PF, Hallström T, Riesbeck K. Human complement control and complement evasion by pathogenic microbes – Tipping the balance. Mol Immunol 2013; 56:152-60. [DOI: 10.1016/j.molimm.2013.05.222] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Zipfel PF, Skerka C. Staphylococcus aureus: the multi headed hydra resists and controls human complement response in multiple ways. Int J Med Microbiol 2013; 304:188-94. [PMID: 24461453 DOI: 10.1016/j.ijmm.2013.11.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Gram positive human pathogen Staphylococcus aureus causes a spectrum of human diseases including pneumonia, tissue and skin infections, endocarditis, pneumonia and sepsis. The increasing number of resistant bacteria and the threat of methicillin resistant S. aureus (MRSA) urge for the need to develop new antibacterial compounds. A prerequisite for development of such anti microbial compounds is a better understanding of the complex immune crosstalk between the pathogenic bacterium and its human host. To this end proteins staphylococcal proteins that contribute to innate immune evasion especially to complement control need to be identified and their mode of action needs to be analyzed in order to provide new targets for immune interference.
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Affiliation(s)
- Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Products Research and Infection Biology, Hans-Knöll Institute, Beutenbergstr. 11a, 07745 Jena, Germany; Friedrich Schiller University Jena, 07745 Jena, Germany.
| | - Christine Skerka
- Department of Infection Biology, Leibniz Institute for Natural Products Research and Infection Biology, Hans-Knöll Institute, Beutenbergstr. 11a, 07745 Jena, Germany
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8
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Luo S, Hoffmann R, Skerka C, Zipfel PF. Glycerol-3-phosphate dehydrogenase 2 is a novel factor H-, factor H-like protein 1-, and plasminogen-binding surface protein of Candida albicans. J Infect Dis 2012. [PMID: 23204165 DOI: 10.1093/infdis/jis718] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Candida albicans uses human complement regulators such as factor H and factor H-like protein 1 (FHL-1) for immune evasion. To define the whole panel of fungal complement-evasion molecules, C. albicans cell extract was absorbed to a factor H-coupled matrix. One 52-kDa protein was eluted and identified by mass spectrometry as glycerol-3-phosphate dehydrogenase 2 (Gpd2). Consequently, Gpd2 was recombinantly expressed and purified. Recombinant Gpd2 binds factor Hand and FHL-1, mainly via short consensus repeat 7; and binds plasminogen, via lysine residues. The 3 human complement regulators, when attached to candida Gpd2, became functionally active, and the attached host proteins assist in inactivation of the complement cascade or cleave fibrinogen in the extracellular matrix component fibrinogen. Polyclonal Gpd2 antiserum was generated and localized Gpd2 at the surface of C. albicans. In addition, candida Gpd2 bound to human nonphagocytic cells but not to phagocytic U937 cells. Thus, candida Gpd2 is a novel fungal immune evasion protein that binds several human complement regulators and, in addition, binds human cells.
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Affiliation(s)
- Shanshan Luo
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Germany
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9
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Yang Y, Li Q, Ju Z, Huang J, Zhou L, Li R, Li J, Shi F, Zhong J, Wang C. Three novel single-nucleotide polymorphisms of complement component 4 gene (C4A) in Chinese Holstein cattle and their associations with milk performance traits and CH50. Vet Immunol Immunopathol 2012; 145:223-32. [DOI: 10.1016/j.vetimm.2011.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 11/11/2011] [Accepted: 11/14/2011] [Indexed: 11/28/2022]
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Pasupuleti M, Schmidtchen A, Malmsten M. Antimicrobial peptides: key components of the innate immune system. Crit Rev Biotechnol 2011; 32:143-71. [PMID: 22074402 DOI: 10.3109/07388551.2011.594423] [Citation(s) in RCA: 514] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Life-threatening infectious diseases are on their way to cause a worldwide crisis, as treating them effectively is becoming increasingly difficult due to the emergence of antibiotic resistant strains. Antimicrobial peptides (AMPs) form an ancient type of innate immunity found universally in all living organisms, providing a principal first-line of defense against the invading pathogens. The unique diverse function and architecture of AMPs has attracted considerable attention by scientists, both in terms of understanding the basic biology of the innate immune system, and as a tool in the design of molecular templates for new anti-infective drugs. AMPs are gene-encoded short (<100 amino acids), amphipathic molecules with hydrophobic and cationic amino acids arranged spatially, which exhibit broad spectrum antimicrobial activity. AMPs have been the subject of natural evolution, as have the microbes, for hundreds of millions of years. Despite this long history of co-evolution, AMPs have not lost their ability to kill or inhibit the microbes totally, nor have the microbes learnt to avoid the lethal punch of AMPs. AMPs therefore have potential to provide an important breakthrough and form the basis for a new class of antibiotics. In this review, we would like to give an overview of cationic antimicrobial peptides, origin, structure, functions, and mode of action of AMPs, which are highly expressed and found in humans, as well as a brief discussion about widely abundant, well characterized AMPs in mammals, in addition to pharmaceutical aspects and the additional functions of AMPs.
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Affiliation(s)
- Mukesh Pasupuleti
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, Canada.
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Immune escape of the human facultative pathogenic yeast Candida albicans: the many faces of the Candida Pra1 protein. Int J Med Microbiol 2011; 301:423-30. [PMID: 21565550 DOI: 10.1016/j.ijmm.2011.04.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Infectious diseases caused by human pathogenic fungi represent a major and global health problem. Based on the limited efficacy of existing drugs and the increasing resistance to antifungal compounds, new strategies are urgently needed to fight such fungal infections. The medically important pathogen Candida albicans can exist as an opportunistic yeast, but can also cause severe diseases, septicaemia, and death. In order to establish new strategies to fight Candida infections and to interfere with survival of the pathogen, it is highly relevant to understand the molecular and immunology interactions between the pathogen C. albicans and the human host. This immune cross talk has moved into the focus of infectious disease research. In this review, we summarize the diverse and multiple levels of the immune cross talk between the fungal pathogen C. albicans and the human host. In particular, we define how one single fungal protein Pra1 (pH-regulated antigen 1) interferes and controls host immune attack at multiple levels and thus contributes to fungal immune escape. Candida Pra1 represents a promising candidate for immune interference.
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Reuter M, Caswell CC, Lukomski S, Zipfel PF. Binding of the human complement regulators CFHR1 and factor H by streptococcal collagen-like protein 1 (Scl1) via their conserved C termini allows control of the complement cascade at multiple levels. J Biol Chem 2010; 285:38473-85. [PMID: 20855886 DOI: 10.1074/jbc.m110.143727] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Group A streptococci (GAS) utilize soluble human complement regulators to evade host complement attack. Here, we characterized the binding of the terminal complement complex inhibitor complement Factor H-related protein 1 (CFHR1) and of the C3 convertase regulator Factor H to the streptococcal collagen-like proteins (Scl). CFHR1 and Factor H, but no other member of the Factor H protein family (CFHR2, CFHR3, or CFHR4A), bound to the two streptococcal proteins Scl1.6 and Scl1.55, which are expressed by GAS serotypes M6 and M55. The two human regulators bound to the Scl1 proteins via their conserved C-terminal attachment region, i.e. CFHR1 short consensus repeats 3-5 (SCR3-5) and Factor H SCR18-20. Binding was affected by ionic strength and by heparin. CFHR1 and the C-terminal attachment region of Factor H did not bind to Scl1.1 and Scl2.28 proteins but did bind to intact M1-type and M28-type GAS, which express Scl1.1 and Scl2.28, respectively, thus arguing for the presence of an additional binding mechanism to CFHR1 and Factor H. Furthermore mutations within the C-terminal heparin-binding region and Factor H mutations that are associated with the acute renal disease atypical hemolytic uremic syndrome blocked the interaction with the two streptococcal proteins. Binding of CFHR1 affected the complement regulatory functions of Factor H on the level of the C3 convertase. Apparently, streptococci utilize two types of complement regulator-acquiring surface proteins; type A proteins, as represented by Scl1.6 and Scl1.55, bind to CFHR1 and Factor H via their conserved C-terminal region and do not bind the Factor H-like protein 1 (FHL-1). On the contrary, type B proteins, represented by M-, M-like, and the fibronectin-binding protein Fba proteins, bind Factor H and FHL-1 via domain SCR7 and do not bind CFHR1. In conclusion, binding of CFHR1 is at the expense of Factor H-mediated regulatory function at the level of C3 convertase and at the gain of a regulator that controls complement at the level of the C5 convertase and formation of the terminal complement complex.
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Affiliation(s)
- Michael Reuter
- Department of Infection Biology, Hans Knoell Institute, 07745 Jena, Germany
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