101
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Denk S, Taylor RP, Wiegner R, Cook EM, Lindorfer MA, Pfeiffer K, Paschke S, Eiseler T, Weiss M, Barth E, Lambris JD, Kalbitz M, Martin T, Barth H, Messerer DAC, Gebhard F, Huber-Lang MS. Complement C5a-Induced Changes in Neutrophil Morphology During Inflammation. Scand J Immunol 2017; 86:143-155. [PMID: 28671713 DOI: 10.1111/sji.12580] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/26/2017] [Indexed: 12/20/2022]
Abstract
The complement and neutrophil defence systems, as major components of innate immunity, are activated during inflammation and infection. For neutrophil migration to the inflamed region, we hypothesized that the complement activation product C5a induces significant changes in cellular morphology before chemotaxis. Exposure of human neutrophils to C5a dose- and time-dependently resulted in a rapid C5a receptor-1 (C5aR1)-dependent shape change, indicated by enhanced flow cytometric forward-scatter area values. Similar changes were observed after incubation with zymosan-activated serum and in blood neutrophils during murine sepsis, but not in mice lacking the C5aR1. In human neutrophils, Amnis high-resolution digital imaging revealed a C5a-induced decrease in circularity and increase in the cellular length/width ratio. Biomechanically, microfluidic optical stretching experiments indicated significantly increased neutrophil deformability early after C5a stimulation. The C5a-induced shape changes were inhibited by pharmacological blockade of either the Cl-/HCO3--exchanger or the Cl- -channel. Furthermore, actin polymerization assays revealed that C5a exposure resulted in a significant polarization of the neutrophils. The functional polarization process triggered by ATP-P2X/Y-purinoceptor interaction was also involved in the C5a-induced shape changes, because pretreatment with suramin blocked not only the shape changes but also the subsequent C5a-dependent chemotactic activity. In conclusion, the data suggest that the anaphylatoxin C5a regulates basic neutrophil cell processes by increasing the membrane elasticity and cell size as a consequence of actin-cytoskeleton polymerization and reorganization, transforming the neutrophil into a migratory cell able to invade the inflammatory site and subsequently clear pathogens and molecular debris.
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Affiliation(s)
- S Denk
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, Ulm, Germany
| | - R P Taylor
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - R Wiegner
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, Ulm, Germany
| | - E M Cook
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - M A Lindorfer
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - K Pfeiffer
- Department of General and Visceral Surgery, Ulm University, Ulm, Germany
| | - S Paschke
- Department of General and Visceral Surgery, Ulm University, Ulm, Germany
| | - T Eiseler
- Department of Internal Medicine I, Ulm University, Ulm, Germany
| | - M Weiss
- Department of Anesthesiology, University Hospital Ulm, Ulm, Germany
| | - E Barth
- Department of Anesthesiology, University Hospital Ulm, Ulm, Germany
| | - J D Lambris
- Department of Pathology, University of Pennsylvania, Philadelphia, PA, USA
| | - M Kalbitz
- Department of Traumatology, Hand-, Plastic-, and Reconstructive Surgery, University Hospital Ulm, Ulm, Germany
| | - T Martin
- Institute of Pharmacology and Toxicology, University Hospital Ulm, Ulm, Germany
| | - H Barth
- Institute of Pharmacology and Toxicology, University Hospital Ulm, Ulm, Germany
| | - D A C Messerer
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, Ulm, Germany
| | - F Gebhard
- Department of Traumatology, Hand-, Plastic-, and Reconstructive Surgery, University Hospital Ulm, Ulm, Germany
| | - M S Huber-Lang
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, Ulm, Germany
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102
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Park SY, Shrestha S, Youn YJ, Kim JK, Kim SY, Kim HJ, Park SH, Ahn WG, Kim S, Lee MG, Jung KS, Park YB, Mo EK, Ko Y, Lee SY, Koh Y, Park MJ, Song DK, Hong CW. Autophagy Primes Neutrophils for Neutrophil Extracellular Trap Formation during Sepsis. Am J Respir Crit Care Med 2017; 196:577-589. [PMID: 28358992 DOI: 10.1164/rccm.201603-0596oc] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
RATIONALE Neutrophils are key effectors in the host's immune response to sepsis. Excessive stimulation or dysregulated neutrophil functions are believed to be responsible for sepsis pathogenesis. However, the mechanisms regulating functional plasticity of neutrophils during sepsis have not been fully determined. OBJECTIVES We investigated the role of autophagy in neutrophil functions during sepsis in patients with community-acquired pneumonia. METHODS Neutrophils were isolated from patients with sepsis and stimulated with phorbol 12-myristate 13-acetate (PMA). The levels of reactive oxygen species generation, neutrophil extracellular trap (NET) formation, and granule release, and the autophagic status were evaluated. The effect of neutrophil autophagy augmentation was further evaluated in a mouse model of sepsis. MEASUREMENTS AND MAIN RESULTS Neutrophils isolated from patients who survived sepsis showed an increase in autophagy induction, and were primed for NET formation in response to subsequent PMA stimulation. In contrast, neutrophils isolated from patients who did not survive sepsis showed dysregulated autophagy and a decreased response to PMA stimulation. The induction of autophagy primed healthy neutrophils for NET formation and vice versa. In a mouse model of sepsis, the augmentation of autophagy improved survival via a NET-dependent mechanism. CONCLUSIONS These results indicate that neutrophil autophagy primes neutrophils for increased NET formation, which is important for proper neutrophil effector functions during sepsis. Our study provides important insights into the role of autophagy in neutrophils during sepsis.
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Affiliation(s)
- So Young Park
- 1 Department of Pulmonary and Critical Care Medicine, KyungHee University Medical Center, Seoul, Republic of Korea
| | | | | | - Jun-Kyu Kim
- 3 Department of Physiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | | | - Hyun Jung Kim
- 4 Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Republic of Korea
| | - So-Hee Park
- 5 Department of Pulmonary and Critical Care Medicine, KyungHee University Hospital at Gangdong, Seoul, Republic of Korea
| | | | - Shin Kim
- 6 Department of Immunology, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Myung Goo Lee
- 7 Lung Research Institute of Hallym University, College of Medicine, Hallym University, Chuncheon, Republic of Korea.,8 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea
| | - Ki-Suck Jung
- 7 Lung Research Institute of Hallym University, College of Medicine, Hallym University, Chuncheon, Republic of Korea.,9 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea
| | - Yong Bum Park
- 7 Lung Research Institute of Hallym University, College of Medicine, Hallym University, Chuncheon, Republic of Korea.,10 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Kangdong Sacred Heart Hospital, Seoul, Republic of Korea; and
| | - Eun-Kyung Mo
- 7 Lung Research Institute of Hallym University, College of Medicine, Hallym University, Chuncheon, Republic of Korea.,10 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Kangdong Sacred Heart Hospital, Seoul, Republic of Korea; and
| | - Yousang Ko
- 7 Lung Research Institute of Hallym University, College of Medicine, Hallym University, Chuncheon, Republic of Korea.,10 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Kangdong Sacred Heart Hospital, Seoul, Republic of Korea; and
| | - Suh-Young Lee
- 7 Lung Research Institute of Hallym University, College of Medicine, Hallym University, Chuncheon, Republic of Korea.,8 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea
| | - Younsuck Koh
- 11 Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Myung Jae Park
- 1 Department of Pulmonary and Critical Care Medicine, KyungHee University Medical Center, Seoul, Republic of Korea
| | | | - Chang-Won Hong
- 3 Department of Physiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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103
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Inhibition of complement C5 protects against organ failure and reduces mortality in a baboon model of Escherichia coli sepsis. Proc Natl Acad Sci U S A 2017; 114:E6390-E6399. [PMID: 28720697 DOI: 10.1073/pnas.1706818114] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Bacterial sepsis triggers robust activation of the complement system with subsequent generation of anaphylatoxins (C3a, C5a) and the terminal complement complex (TCC) that together contribute to organ failure and death. Here we tested the effect of RA101295, a 2-kDa macrocyclic peptide inhibitor of C5 cleavage, using in vitro whole-blood assays and an in vivo baboon model of Escherichia coli sepsis. RA101295 strongly inhibited E. coli-induced complement activation both in vitro and in vivo by blocking the generation of C5a and the soluble form of TCC, sC5b-9. RA101295 reduced the E. coli-induced "oxidative burst," as well as leukocyte activation, without affecting host phagocytosis of E. coli RA101295 treatment reduced plasma LPS content in E. coli-challenged baboons, implying reduced complement-mediated bacteriolysis, whereas treated animals showed slightly improved bacterial clearance during the bacteremic stage compared with controls. Treatment with RA101295 also improved consumptive coagulopathy and preserved endothelial anticoagulant and vascular barrier functions. RA101295 abolished sepsis-induced surges in proinflammatory cytokines and attenuated systemic circulatory and febrile responses, likely reflecting decreased systemic levels of LPS and C5a. Overall, RA101295 treatment was associated with significant organ protection and markedly reduced mortality compared with nontreated controls (four of five animals survived in a 100% lethal model). We therefore conclude that inhibition of C5 cleavage during the bacteremic stage of sepsis could be an important therapeutic approach to prevent sepsis-induced inflammation, consumptive coagulopathy, and subsequent organ failure and death.
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104
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Genster N, Østrup O, Schjalm C, Eirik Mollnes T, Cowland JB, Garred P. Ficolins do not alter host immune responses to lipopolysaccharide-induced inflammation in vivo. Sci Rep 2017; 7:3852. [PMID: 28634324 PMCID: PMC5478672 DOI: 10.1038/s41598-017-04121-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/09/2017] [Indexed: 11/17/2022] Open
Abstract
Ficolins are a family of pattern recognition molecules that are capable of activating the lectin pathway of complement. A limited number of reports have demonstrated a protective role of ficolins in animal models of infection. In addition, an immune modulatory role of ficolins has been suggested. Yet, the contribution of ficolins to inflammatory disease processes remains elusive. To address this, we investigated ficolin deficient mice during a lipopolysaccharide (LPS)-induced model of systemic inflammation. Although murine serum ficolin was shown to bind LPS in vitro, there was no difference between wildtype and ficolin deficient mice in morbidity and mortality by LPS-induced inflammation. Moreover, there was no difference between wildtype and ficolin deficient mice in the inflammatory cytokine profiles after LPS challenge. These findings were substantiated by microarray analysis revealing an unaltered spleen transcriptome profile in ficolin deficient mice compared to wildtype mice. Collectively, results from this study demonstrate that ficolins are not involved in host response to LPS-induced systemic inflammation.
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Affiliation(s)
- Ninette Genster
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Olga Østrup
- Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, DK-2100, Copenhagen, Denmark
| | - Camilla Schjalm
- Department of Immunology, Oslo University Hospital, Rikshospitalet, 0424, Oslo, Norway
| | - Tom Eirik Mollnes
- Department of Immunology, Oslo University Hospital, Rikshospitalet, 0424, Oslo, Norway
- Research Laboratory, Nordland Hospital, Bodø, and K.J. Jebsen TREC, University of Tromsø, Tromsø, Norway
- Centre of Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jack B Cowland
- The Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Genetics, Copenhagen University Hospital, Copenhagen, Denmark
| | - Peter Garred
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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105
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Denk S, Neher MD, Messerer DAC, Wiegner R, Nilsson B, Rittirsch D, Nilsson-Ekdahl K, Weckbach S, Ignatius A, Kalbitz M, Gebhard F, Weiss ME, Vogt J, Radermacher P, Köhl J, Lambris JD, Huber-Lang MS. Complement C5a Functions as a Master Switch for the pH Balance in Neutrophils Exerting Fundamental Immunometabolic Effects. THE JOURNAL OF IMMUNOLOGY 2017; 198:4846-4854. [PMID: 28490576 DOI: 10.4049/jimmunol.1700393] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 04/16/2017] [Indexed: 01/08/2023]
Abstract
During sepsis, excessive activation of the complement system with generation of the anaphylatoxin C5a results in profound disturbances in crucial neutrophil functions. Moreover, because neutrophil activity is highly dependent on intracellular pH (pHi), we propose a direct mechanistic link between complement activation and neutrophil pHi In this article, we demonstrate that in vitro exposure of human neutrophils to C5a significantly increased pHi by selective activation of the sodium/hydrogen exchanger. Upstream signaling of C5a-mediated intracellular alkalinization was dependent on C5aR1, intracellular calcium, protein kinase C, and calmodulin, and downstream signaling regulated the release of antibacterial myeloperoxidase and lactoferrin. Notably, the pH shift caused by C5a increased the glucose uptake and activated glycolytic flux in neutrophils, resulting in a significant release of lactate. Furthermore, C5a induced acidification of the extracellular micromilieu. In experimental murine sepsis, pHi of blood neutrophils was analogously alkalinized, which could be normalized by C5aR1 inhibition. In the clinical setting of sepsis, neutrophils from patients with septic shock likewise exhibited a significantly increased pHi These data suggest a novel role for the anaphylatoxin C5a as a master switch of the delicate pHi balance in neutrophils resulting in profound inflammatory and metabolic changes that contribute to hyperlactatemia during sepsis.
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Affiliation(s)
- Stephanie Denk
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, 89081 Ulm, Germany
| | - Miriam D Neher
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, 89081 Ulm, Germany
| | - David A C Messerer
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, 89081 Ulm, Germany
| | - Rebecca Wiegner
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, 89081 Ulm, Germany
| | - Bo Nilsson
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - Daniel Rittirsch
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, 8091 Zurich, Switzerland
| | | | - Sebastian Weckbach
- Department of Orthopedic Surgery, Ulm University, University and Rehabilitation Clinics Ulm, 89081 Ulm, Germany
| | - Anita Ignatius
- Institute of Orthopedic Research and Biomechanics, Ulm University, 89081 Ulm, Germany
| | - Miriam Kalbitz
- Department of Traumatology, Hand, Plastic, and Reconstructive Surgery, University Hospital Ulm, 89081 Ulm, Germany
| | - Florian Gebhard
- Department of Traumatology, Hand, Plastic, and Reconstructive Surgery, University Hospital Ulm, 89081 Ulm, Germany
| | - Manfred E Weiss
- Department of Anesthesiology, University Hospital Ulm, 89081 Ulm, Germany
| | - Josef Vogt
- Institute of Anesthesiological Pathophysiology and Process Engineering, Ulm University, 89081 Ulm, Germany
| | - Peter Radermacher
- Institute of Anesthesiological Pathophysiology and Process Engineering, Ulm University, 89081 Ulm, Germany
| | - Jörg Köhl
- Institute for Systemic Inflammation Research, University of Lübeck, 23538 Lübeck, Germany.,Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229; and
| | - John D Lambris
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Markus S Huber-Lang
- Institute of Clinical and Experimental Trauma-Immunology, University Hospital Ulm, 89081 Ulm, Germany;
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106
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Holt BA, Bellavia MC, Potter D, White D, Stowell SR, Sulchek T. Fc microparticles can modulate the physical extent and magnitude of complement activity. Biomater Sci 2017; 5:463-474. [PMID: 28067347 PMCID: PMC5330945 DOI: 10.1039/c6bm00608f] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complement system is an integral component of the humoral immune system, and describes a cascade of interacting proteins responsible for the opsonization and lysis of foreign pathogens, in addition to the recruitment of immune cells. However, complement activation is also implicated in the progression and complication of immune dysfunctions such as sepsis. Microparticle (MP) biomaterials capable of tuning the local magnitude of serum complement activation could improve complement-mediated cytotoxicity to serum-resistant bacteria or calm an overactive immune response during sepsis. We demonstrate that model Fc-functionalized microparticles can be designed to either enhance or diminish the local cytotoxic effect of complement activation in human serum. The particles were formed with either the antibody Fc domains oriented outward from the particle surface or randomly adsorbed in a non-oriented fashion. In the oriented Fc form, complement products were directly sequestered to the particle surface, including C5a, a potent anaphylatoxin that, when elevated, is associated with poor sepsis prognosis. The oriented particle also lowered the cytotoxicity of serum and thus decreased the antibiotic effect when compared to serum alone. Conversely, the non-oriented microparticles were found to sequester similar levels of C5a, but much lower levels of iC3b and TCC on the microparticle surface, thereby increasing the amount of the soluble terminal complement complex. In addition, the non-oriented microparticles extend the distance over which TCC forms and enhance serum cytotoxicity to bacteria. Together, these two types of complement-modulating particles provide the first biomaterial that can functionally modify the range of complement activation at sites distant from the particle surface. Thus, biomaterials that exploit Fc presentation provide new possibilities to functionally modulate complement activation to achieve a desired clinical result.
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Affiliation(s)
- Brandon Alexander Holt
- Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology and Emory University, Atlanta, GA, USA. and The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Michael C Bellavia
- Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology and Emory University, Atlanta, GA, USA. and The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Daniel Potter
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA and The G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - David White
- United States Department of Agriculture, National Centers for Animal Health, Ames, Iowa, USA
| | - Sean R Stowell
- Center for Transfusion and Cellular Therapies, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Todd Sulchek
- Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology and Emory University, Atlanta, GA, USA. and The G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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107
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Kasztelewicz B, Piotrowska E, Tołłoczko J, Borszewska-Kornacka MK, Gregorek H, Dzierżanowska-Fangrat K. Assessment of interleukin-17A, C5a and RANTES for early diagnosis of neonatal sepsis - a preliminary study. Cent Eur J Immunol 2017; 41:376-382. [PMID: 28450800 PMCID: PMC5382877 DOI: 10.5114/ceji.2016.64783] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/26/2016] [Indexed: 12/13/2022] Open
Abstract
The aim of the present study was to investigate serum levels of novel markers: interleukin 17A (IL-17A), anaphylatoxin C5a and chemokine regulated upon activation normal T-cell expressed and secreted (RANTES) in neonates with clinically suspected early-onset neonatal sepsis (EONS), and to compare their values with those of non-infected neonates. Eighteen neonates with clinical signs and symptoms of EONS were enrolled in this study. Fifty healthy, non-infected neonates served as the control group. In all neonates serum levels of IL-17A, C5a and RANTES were measured by solid-phase sandwich enzyme-linked immunosorbent assay (ELISA). At the time of investigation serum levels of anaphylatoxin C5a were significantly higher in neonates with clinical symptoms of EONS than in non-infected neonates (median 65.35 vs. 50.4 ng/ml, p = 0.034), whereas levels of RANTES were similar and levels of IL-17A were under detection limit of the method. Based on these preliminary results, serum levels of C5a may be a useful marker of inflammation in early onset neonatal sepsis. Because traditional methods of microbiological diagnostics in EONS are frequently unsuccessful, the search for an alternative laboratory biomarkers is of great clinical importance. Thus, there is a strong need for further studies evaluating usefulness of this anaphylatoxin in EONS diagnosis on a larger group of patients.
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Affiliation(s)
- Beata Kasztelewicz
- Department of Clinical Microbiology and Immunology, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Ewa Piotrowska
- Neonatal Intensive Care Unit, The Nicolaus Copernicus Hospital in Olsztyn, Olsztyn, Poland
| | - Justyna Tołłoczko
- Department of Neonatology and Neonatal Intensive Care, Medical University of Warsaw, Warsaw, Poland
| | | | - Hanna Gregorek
- Department of Clinical Microbiology and Immunology, The Children’s Memorial Health Institute, Warsaw, Poland
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108
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Bettac L, Denk S, Seufferlein T, Huber-Lang M. Complement in Pancreatic Disease-Perpetrator or Savior? Front Immunol 2017; 8:15. [PMID: 28144242 PMCID: PMC5239781 DOI: 10.3389/fimmu.2017.00015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 01/05/2017] [Indexed: 12/13/2022] Open
Abstract
The complement system is a major pillar of the humoral innate immune system. As a first line of defense against pathogens, it mediates early inflammatory response and links different branches of humoral and cellular immunity. Disorders affecting the exocrine pancreas, such as acute pancreatitis, potentially lead to a life-threatening systemic inflammatory response with aberrant activation of complement and coagulation cascades. Pancreatic proteases can activate key effectors of the complement system, which in turn drive local and systemic inflammation. Beyond that, the extent of pancreas–complement interaction covers complex pro- and anti-inflammatory mechanisms, which to this day remain to be fully elucidated. This review provides a comprehensive overview of the pathophysiological role of complement in diseases of the exocrine pancreas, based on existing experimental and clinical data. Participation of complement in acute and chronic pancreatitis is addressed, as well as its role in tumor immunology. Therapeutic strategies targeting complement in these diseases have long been proposed but have not yet arrived in the clinical setting.
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Affiliation(s)
- Lucas Bettac
- Department of Internal Medicine I, University Hospital of Ulm , Ulm , Germany
| | - Stephanie Denk
- Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Ulm , Ulm , Germany
| | - Thomas Seufferlein
- Department of Internal Medicine I, University Hospital of Ulm , Ulm , Germany
| | - Markus Huber-Lang
- Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Ulm , Ulm , Germany
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109
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C5a and pain development: An old molecule, a new target. Pharmacol Res 2016; 112:58-67. [DOI: 10.1016/j.phrs.2016.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 12/13/2022]
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110
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Pleiotropic regulations of neutrophil receptors response to sepsis. Inflamm Res 2016; 66:197-207. [DOI: 10.1007/s00011-016-0993-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/24/2016] [Accepted: 09/20/2016] [Indexed: 12/21/2022] Open
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111
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Choudhry N, Li K, Zhang T, Wu KY, Song Y, Farrar CA, Wang N, Liu CF, Peng Q, Wu W, Sacks SH, Zhou W. The complement factor 5a receptor 1 has a pathogenic role in chronic inflammation and renal fibrosis in a murine model of chronic pyelonephritis. Kidney Int 2016; 90:540-54. [PMID: 27370410 PMCID: PMC4996631 DOI: 10.1016/j.kint.2016.04.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 04/12/2016] [Accepted: 04/28/2016] [Indexed: 02/07/2023]
Abstract
Complement factor 5a (C5a) interaction with its receptor (C5aR1) contributes to the pathogenesis of inflammatory diseases, including acute kidney injury. However, its role in chronic inflammation, particularly in pathogen-associated disorders, is largely unknown. Here we tested whether the development of chronic inflammation and renal fibrosis is dependent on C5aR1 in a murine model of chronic pyelonephritis. C5aR1-deficient (C5aR1-/-) mice showed a significant reduction in bacterial load, tubule injury and tubulointerstitial fibrosis in the kidneys following infection, compared with C5aR1-sufficient mice. This was associated with reduced renal leukocyte infiltration specifically for the population of Ly6Chi proinflammatory monocytes/macrophages and reduced intrarenal gene expression of key proinflammatory and profibrogenic factors in C5aR1-/- mice following infection. Antagonizing C5aR1 decreased renal bacterial load, tissue inflammation and tubulointerstitial fibrosis. Ex vivo and in vitro studies showed that under infection conditions, C5a/C5aR1 interaction upregulated the production of proinflammatory and profibrogenic factors by renal tubular epithelial cells and monocytes/macrophages, whereas the phagocytic function of monocytes/macrophages was down-regulated. Thus, C5aR1-dependent bacterial colonization of the tubular epithelium, C5a/C5aR1-mediated upregulation of local inflammatory responses to uropathogenic E. coli and impairment of phagocytic function of phagocytes contribute to persistent bacterial colonization of the kidney, chronic renal inflammation and subsequent tubulointerstitial fibrosis.
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Affiliation(s)
- Naheed Choudhry
- Medical Research Council Centre for Transplantation, King's College London, Guy's Hospital, London, UK
| | - Ke Li
- Core Research Laboratory, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.
| | - Ting Zhang
- Core Research Laboratory, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Kun-Yi Wu
- Core Research Laboratory, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Yun Song
- Core Research Laboratory, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Conrad A Farrar
- Medical Research Council Centre for Transplantation, King's College London, Guy's Hospital, London, UK
| | - Na Wang
- Core Research Laboratory, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Cheng-Fei Liu
- Core Research Laboratory, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Qi Peng
- Medical Research Council Centre for Transplantation, King's College London, Guy's Hospital, London, UK
| | - Weiju Wu
- Medical Research Council Centre for Transplantation, King's College London, Guy's Hospital, London, UK
| | - Steven H Sacks
- Medical Research Council Centre for Transplantation, King's College London, Guy's Hospital, London, UK
| | - Wuding Zhou
- Medical Research Council Centre for Transplantation, King's College London, Guy's Hospital, London, UK.
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Barratt-Due A, Pischke SE, Nilsson PH, Espevik T, Mollnes TE. Dual inhibition of complement and Toll-like receptors as a novel approach to treat inflammatory diseases-C3 or C5 emerge together with CD14 as promising targets. J Leukoc Biol 2016; 101:193-204. [PMID: 27581539 PMCID: PMC5166441 DOI: 10.1189/jlb.3vmr0316-132r] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 07/01/2016] [Accepted: 07/25/2016] [Indexed: 12/22/2022] Open
Abstract
Review of how targeting key upstream molecules at the recognition phase of innate immunity exert anti-inflammatory effects; a potential therapeutic regimen for inflammatory diseases. The host is protected by pattern recognition systems, including complement and TLRs, which are closely cross-talking. If improperly activated, these systems might induce tissue damage and disease. Inhibition of single downstream proinflammatory cytokines, such as TNF, IL-1β, and IL-6, have failed in clinical sepsis trials, which might not be unexpected, given the substantial amounts of mediators involved in the pathogenesis of this condition. Instead, we have put forward a hypothesis of inhibition at the recognition phase by “dual blockade” of bottleneck molecules of complement and TLRs. By acting upstream and broadly, the dual blockade could be beneficial in conditions with improper or uncontrolled innate immune activation threatening the host. Key bottleneck molecules in these systems that could be targets for inhibition are the central complement molecules C3 and C5 and the important CD14 molecule, which is a coreceptor for several TLRs, including TLR4 and TLR2. This review summarizes current knowledge of inhibition of complement and TLRs alone and in combination, in both sterile and nonsterile inflammatory processes, where activation of these systems is of crucial importance for tissue damage and disease. Thus, dual blockade might provide a general, broad-acting therapeutic regimen against a number of diseases where innate immunity is improperly activated.
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Affiliation(s)
- Andreas Barratt-Due
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway.,Department of Emergencies and Critical Care, Oslo University Hospital, Oslo, Norway
| | - Søren Erik Pischke
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway.,Department of Emergencies and Critical Care, Oslo University Hospital, Oslo, Norway
| | - Per H Nilsson
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway
| | - Terje Espevik
- Centre of Molecular Inflammation Research and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tom Eirik Mollnes
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway; .,Centre of Molecular Inflammation Research and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.,Research Laboratory Nordland Hospital, Bodø, Norway; and.,K. G. Jebsen Thrombosis Research and Expertise Center, University of Tromsø, Tromsø, Norway
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113
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Wysoczynski M, Adamiak M, Suszynska M, Abdel-Latif A, Ratajczak J, Ratajczak MZ. Poor Mobilization in T-Cell-Deficient Nude Mice Is Explained by Defective Activation of Granulocytes and Monocytes. Cell Transplant 2016; 26:83-93. [PMID: 27436627 DOI: 10.3727/096368916x692221] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
It has been reported that both SCID mice and SCID patients poorly mobilize hematopoietic stem/progenitor cells (HSPCs) in response to granulocyte colony-stimulating factor (G-CSF). This defect has been proposed to result from a lack of naturally occurring IgM immunoglobulins to trigger activation of the complement cascade (ComC) and release of C5 cleavage fragments crucial in the mobilization process. However, SCID individuals also have T-cell deficiency, and T cells have been shown to modulate trafficking of HSPCs. To learn more about the role of T lymphocytes, we performed mobilization studies in T-lymphocyte-deficient nude mice and found that these mice respond poorly to G-CSF and zymosan but are normal mobilizers in response to AMD3100. Since nude mice have normal levels of IgM immunoglobulins in peripheral blood and may activate the ComC, we focused on the potential involvement of Gr1+ granulocytes and monocytes, which show defective maturation in these animals. Using a nude mouse mobilization model, we found further support for the proposition that proper function of Gr1+ cells is crucial for optimal mobilization of HSPCs.
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114
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Hwang DE, Choi JM, Yang CS, Lee JJ, Heu W, Jo EK, Kim HS. Effective suppression of C5a-induced proinflammatory response using anti-human C5a repebody. Biochem Biophys Res Commun 2016; 477:1072-1077. [PMID: 27416759 DOI: 10.1016/j.bbrc.2016.07.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/08/2016] [Indexed: 01/21/2023]
Abstract
The strongest anaphylatoxin, C5a, plays a critical role in the proinflammatory responses, causing the pathogenesis of a number of inflammatory diseases including sepsis, asthma, and rheumatoid arthritis. Inhibitors of C5a thus have great potential as therapeutics for various inflammatory disorders. Herein, we present the development of a high-affinity repebody against human C5a (hC5a), which effectively suppresses the proinflammatory response. A repebody scaffold composed of leucine-rich repeat (LRR) modules was previously developed as an alternative protein scaffold. A repebody specifically binding to hC5a was selected through a phage display, and its affinity was increased up to 5 nM using modular engineering. The repebody was shown to effectively inhibit the production of C5a-induced proinflammatory cytokines by human monocytes. To obtain insight into a mode of action by the repebody, we determined its crystal structure in complex with hC5a. A structural analysis revealed that the repebody binds to the D1 and D3 regions of hC5a, overlapping several epitope residues with the hC5a receptor (hC5aR). It is thus likely that the repebody suppresses the hC5a-mediated immune response in monocytes by blocking the binding of hC5a to its receptor. The anti-hC5a repebody can be developed as a potential therapeutic for C5a-involved inflammatory diseases.
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Affiliation(s)
- Da-Eun Hwang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea
| | - Jung-Min Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea
| | - Chul-Su Yang
- Department of Molecular and Life Sciences, Hanyang University, Ansan, 15588, Republic of Korea
| | - Joong-Jae Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea
| | - Woosung Heu
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea
| | - Eun-Kyeong Jo
- Department of Microbiology, Chungnam National University College of Medicine, Daejeon, Republic of Korea
| | - Hak-Sung Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea.
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115
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Role of cellular events in the pathophysiology of sepsis. Inflamm Res 2016; 65:853-868. [PMID: 27392441 DOI: 10.1007/s00011-016-0970-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/11/2016] [Accepted: 06/25/2016] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Sepsis is a dysregulated host immune response due to an uncontrolled infection. It is a leading cause of mortality in adult intensive care units globally. When the host immune response induced against a local infection fails to contain it locally, it progresses to sepsis, severe sepsis, septic shock and death. METHOD Literature survey was performed on the roles of different innate and adaptive immune cells in the development and progression of sepsis. Additionally, the effects of septic changes on reprogramming of different immune cells were also summarized to prepare the manuscript. FINDINGS Scientific evidences to date suggest that the loss of balance between inflammatory and anti-inflammatory responses results in reprogramming of immune cell activities that lead to irreversible tissue damaging events and multi-organ failure during sepsis. Many surface receptors expressed on immune cells at various stages of sepsis have been suggested as biomarkers for sepsis diagnosis. Various immunomodulatory therapeutics, which could improve the functions of immune cells during sepsis, were shown to restore immunological homeostasis and improve survival in animal models of sepsis. CONCLUSION In-depth and comprehensive knowledge on the immune cell activities and their correlation with severity of sepsis will help clinicians and scientists to design effective immunomodulatory therapeutics for treating sepsis.
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Bidirectional Crosstalk between C5a Receptors and the NLRP3 Inflammasome in Macrophages and Monocytes. Mediators Inflamm 2016; 2016:1340156. [PMID: 27382187 PMCID: PMC4921141 DOI: 10.1155/2016/1340156] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/04/2016] [Accepted: 05/15/2016] [Indexed: 11/17/2022] Open
Abstract
C5a is an inflammatory mediator generated by complement activation that positively regulates various arms of immune defense, including Toll-like receptor 4 (TLR4) signaling. The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is activated by pathogen products and cellular/tissue damage products and is a major contributor of IL-1β. In this study, we investigate whether C5a modulates lipopolysaccharide- (LPS-) induced NLRP3 inflammasome activation in myeloid cells. Appearance of plasma IL-1β during endotoxemia was reduced in C5aR1−/− mice when compared to wild-type mice. In vitro, C5a significantly enhanced LPS-induced production of IL-1β in bone marrow Ly6C-high inflammatory monocytes, accompanied by augmented intracellular pro-IL-1β expression. This effect was abolished during p38 blockade by SB 203580 and in the absence of C5aR1. Conversely, C5a suppressed LPS-induced macrophage production of IL-1β, which was accompanied by attenuated levels of pro-IL-1β, NLRP3, and caspase-1 expression. C5a's suppressive effects were negated during phosphoinositide 3-kinase (PI3K) inhibition by wortmannin but were largely preserved in the absence of C5aR1. Thus, C5a bidirectionally amplifies TLR4-mediated NLRP3 inflammasome activation in monocytes while suppressing this pathway in macrophages. However, as C5aR1 deficiency attenuates the IL-1β response to LPS challenge in vivo, our results suggest overall that C5a augments physiologic inflammasome responses.
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117
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Ricklin D, Reis ES, Lambris JD. Complement in disease: a defence system turning offensive. Nat Rev Nephrol 2016; 12:383-401. [PMID: 27211870 DOI: 10.1038/nrneph.2016.70] [Citation(s) in RCA: 377] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although the complement system is primarily perceived as a host defence system, a more versatile, yet potentially more harmful side of this innate immune pathway as an inflammatory mediator also exists. The activities that define the ability of the complement system to control microbial threats and eliminate cellular debris - such as sensing molecular danger patterns, generating immediate effectors, and extensively coordinating with other defence pathways - can quickly turn complement from a defence system to an aggressor that drives immune and inflammatory diseases. These host-offensive actions become more pronounced with age and are exacerbated by a variety of genetic factors and autoimmune responses. Complement can also be activated inappropriately, for example in response to biomaterials or transplants. A wealth of research over the past two decades has led to an increasingly finely tuned understanding of complement activation, identified tipping points between physiological and pathological behaviour, and revealed avenues for therapeutic intervention. This Review summarizes our current view of the key activating, regulatory, and effector mechanisms of the complement system, highlighting important crosstalk connections, and, with an emphasis on kidney disease and transplantation, discusses the involvement of complement in clinical conditions and promising therapeutic approaches.
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Affiliation(s)
- Daniel Ricklin
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, 401 Stellar Chance, 422 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Edimara S Reis
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, 401 Stellar Chance, 422 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - John D Lambris
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, 401 Stellar Chance, 422 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA
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118
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Hajishengallis G, Krauss JL, Jotwani R, Lambris JD. Differential capacity for complement receptor-mediated immune evasion by Porphyromonas gingivalis depending on the type of innate leukocyte. Mol Oral Microbiol 2016; 32:154-165. [PMID: 27081768 DOI: 10.1111/omi.12161] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2016] [Indexed: 01/02/2023]
Abstract
The complement system plays a central role in immunity and inflammation, although certain pathogens can exploit complement to undermine protective immunity. In this context, the periodontal keystone pathogen Porphyromonas gingivalis was previously shown by our group to evade killing by neutrophils or macrophages through exploitation of complement C5a receptor 1 (C5aR1) and complement receptor 3 (CR3). Here, we examined whether P. gingivalis uses complement receptors to also subvert killing by dendritic cells. In line with earlier independent studies, intracellular viable P. gingivalis bacteria could be recovered from mouse bone-marrow-derived dendritic cells (BMDC) or human monocyte-derived dendritic cells (MDDC) exposed to the pathogen. However, in the presence of C5a, the intracellular survival of P. gingivalis was significantly decreased in a C5aR1-dependent way. Further work using wild-type and receptor-knockout BMDC showed that, in the presence of C3a, the C3a receptor (C3aR) similarly enhanced the intracellular killing of P. gingivalis. In contrast, C5aR2, an alternative receptor for C5a (G protein-coupled receptor 77), was associated with increased intracellular P. gingivalis viable counts, consistent with the notion that C5aR2 functions as a negative regulator of C5aR1 activity. Moreover, P. gingivalis failed to use CR3 as a phagocytic receptor in BMDC, in contrast to our earlier findings in macrophages where CR3-mediated uptake promotes P. gingivalis survival. Collectively, these data show that complement receptors mediate cell-type-specific effects on how innate leukocytes handle P. gingivalis, which appears to exploit complement to preferentially evade those cells (neutrophils and macrophages) that are most often encountered in its predominant niche, the periodontal pocket.
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Affiliation(s)
- G Hajishengallis
- Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - J L Krauss
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, KY, USA
| | - R Jotwani
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, KY, USA
| | - J D Lambris
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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119
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Berger BE. The Alternative Pathway of Complement and the Evolving Clinical-Pathophysiological Spectrum of Atypical Hemolytic Uremic Syndrome. Am J Med Sci 2016; 352:177-90. [PMID: 27524217 DOI: 10.1016/j.amjms.2016.05.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 03/31/2016] [Accepted: 05/03/2016] [Indexed: 01/31/2023]
Abstract
Complement-mediated atypical hemolytic uremic syndrome (aHUS) comprises approximately 90% of cases of aHUS, and results from dysregulation of endothelial-anchored complement activation with resultant endothelial damage. The discovery of biomarker ADAMTS13 has enabled a more accurate diagnosis of thrombotic thrombocytopenic purpura (TTP) and an appreciation of overlapping clinical features of TTP and aHUS. Given our present understanding of the pathogenic pathways involved in aHUS, it is unlikely that a specific test will be developed. Rather the use of biomarker data, complement functional analyses, genomic analyses and clinical presentation will be required to diagnose aHUS. This approach would serve to clarify whether a thrombotic microangiopathy present in a complement-amplifying condition arises from the unmasking of a genetically driven aHUS versus a time-limited complement storm-mediated aHUS due to direct endothelial damage in which no genetic predisposition is present. Although both scenarios result in the phenotypic expression of aHUS and involve the alternate pathway of complement activation, long-term management would differ.
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Affiliation(s)
- Bruce E Berger
- School of Medicine, Case Western Reserve University, Cleveland, Ohio.
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120
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Discovery of functionally selective C5aR2 ligands: novel modulators of C5a signalling. Immunol Cell Biol 2016; 94:787-95. [PMID: 27108698 DOI: 10.1038/icb.2016.43] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 04/19/2016] [Accepted: 04/20/2016] [Indexed: 12/22/2022]
Abstract
The complement cascade is comprised of a highly sophisticated network of innate immune proteins that are activated in response to invading pathogens or tissue injury. The complement activation peptide, C5a, binds two seven transmembrane receptors, namely the C5a receptor 1 (C5aR1) and C5a receptor 2 (C5aR2, or C5L2). C5aR2 is a non-G-protein-signalling receptor whose biological role remains controversial. Some of this controversy arises owing to the lack of selective ligands for C5aR2. In this study, a library of 61 peptides based on the C-terminus of C5a was assayed for the ability to selectively modulate C5aR2 function. Two ligands (P32 and P59) were identified as functionally selective C5aR2 ligands, exhibiting selective recruitment of β-arrestin 2 via C5aR2, partial inhibition of C5a-induced ERK1/2 activation and lipopolysaccharide-stimulated interleukin-6 release from human monocyte-derived macrophages. Importantly, neither ligand could induce ERK1/2 activation or inhibit C5a-induced ERK1/2 activation via C5aR1 directly. Finally, P32 inhibited C5a-mediated neutrophil mobilisation in wild-type, but not C5aR2(-/-) mice. These functionally selective ligands for C5aR2 are novel tools that can selectively modulate C5a activity in vitro and in vivo, and thus will be valuable tools to interrogate C5aR2 function.
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121
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Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists. Sci Rep 2016; 6:24575. [PMID: 27094554 PMCID: PMC4837355 DOI: 10.1038/srep24575] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 03/31/2016] [Indexed: 12/13/2022] Open
Abstract
Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3 nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1 -3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents.
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Complement Factor 3 Could Be an Independent Risk Factor for Mortality in Patients with HBV Related Acute-on-Chronic Liver Failure. BIOMED RESEARCH INTERNATIONAL 2016; 2016:3524842. [PMID: 27144164 PMCID: PMC4837248 DOI: 10.1155/2016/3524842] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 03/08/2016] [Accepted: 03/20/2016] [Indexed: 12/30/2022]
Abstract
The complement is thought to be involved in the pathogenesis of multiple liver disorders. However, its role in patients with HBV related acute-on-chronic liver failure (HBV-ACLF) remains unclear. Serum levels of the third and fourth complement components (C3, C4) and complement function (CH50) were examined in this prospective, observational study. Associations between their expression and disease activity were analyzed. Survival was analyzed by Kaplan-Meier curves. Predictors of clinical outcome were determined by Cox regression analysis. C3, C4, and CH50 levels were significantly lower in HBV-ACLF patients compared to controls. C3, C4, and CH50 levels were negatively correlated with Tbil levels but positively associated with PTA levels. C3 levels were negatively associated with MELD-Na. C3 levels were significantly lower in HBV-ACLF patients who died compared to patients who survived. In a median hospital stay of 39 days, mortality occurred in 41 patients with a progressive increase based on C3 grade (P = 0.008). The actuarial probability of developing mortality was significantly higher in patients with low C3 grade compared to those with high C3 grade (P < 0.001). Multivariate Cox regression analysis showed that C3 levels were an independent predictor of mortality. Complement played a pathogenic role in HBV-ACLF patients and C3 was an independent predictor of mortality.
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Abstract
The unique properties of nucleic acid aptamers and their suitability to therapeutic applications have attracted the attention of researchers for more than 2 decades. Aptamers exhibit significant advantages relative to antibody-based therapeutics and can serve dual roles as either the therapeutic agent itself or a targeting modality. Despite this intense research interest, aptamers have been slow to reach the clinic, partly due to practical limitations that can be overcome by rational chemical modifications and ingenious aptamer selection approaches. This review highlights the latest efforts to use aptamers in therapeutic applications, the key properties of aptamers that can be exploited, the aptamers that are currently in clinical trials, as well as speculation on the future of aptamers in the field of nanomedicine.
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Affiliation(s)
- Christopher M C Mattice
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
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124
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Khor KH, Moore TA, Shiels IA, Greer RM, Arumugam TV, Mills PC. A Potential Link between the C5a Receptor 1 and the β1-Adrenoreceptor in the Mouse Heart. PLoS One 2016; 11:e0146022. [PMID: 26727203 PMCID: PMC4699762 DOI: 10.1371/journal.pone.0146022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 12/11/2015] [Indexed: 12/17/2022] Open
Abstract
Purpose Inflammation may contribute to the pathogenesis of specific cardiovascular diseases, but it is uncertain if mediators released during the inflammatory process will affect the continued efficacy of drugs used to treat clinical signs of the cardiac disease. We investigated the role of the complement 5a receptor 1 (C5aR1/CD88) in the cardiac response to inflammation or atenolol, and the effect of C5aR1 deletion in control of baseline heart rate in an anesthetized mouse model. Methods An initial study showed that PMX53, an antagonist of C5aR1 in normal C57BL6/J (wild type, WT) mice reduced heart rate (HR) and appeared to have a protective effect on the heart following induced sepsis. C5aR1 knockout (CD88-/-) mice had a lower HR than wild type mice, even during sham surgery. A model to assess heart rate variability (HRV) in anesthetized mice was developed to assess the effects of inhibiting the β1-adrenoreceptor (β1-AR) in a randomized crossover study design. Results HR and LF Norm were constitutively lower and SDNN and HF Norm constitutively higher in the CD88-/- compared with WT mice (P< 0.001 for all outcomes). Administration of atenolol (2.5 mg/kg) reduced the HR and increased HRV (P< 0.05, respectively) in the wild type but not in the CD88-/- mice. There was no shift of the sympathovagal balance post-atenolol in either strains of mice (P> 0.05), except for the reduced LF/HF (Lower frequency/High frequency) ratio (P< 0.05) at 60 min post-atenolol, suggesting increased parasympathetic tone of the heart due to the effect of atenolol administration. The HR of the WT mice were lower post atenolol compared to the CD88-/- mice (P = 0.001) but the HRV of CD88-/- mice were significantly increased (P< 0.05), compared with WT mice. Conclusion Knockout of the C5aR1 attenuated the effect of β1-AR in the heart, suggesting an association between the β1-AR and C5aR1, although further investigation is required to determine if this is a direct or causal association.
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Affiliation(s)
- Kuan Hua Khor
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
- Faculty of Veterinary Medicine, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Tyson A. Moore
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Ian A. Shiels
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Ristan M. Greer
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Thiruma V. Arumugam
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Paul C. Mills
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
- * E-mail:
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125
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McDonald CR, Tran V, Kain KC. Complement Activation in Placental Malaria. Front Microbiol 2015; 6:1460. [PMID: 26733992 PMCID: PMC4685051 DOI: 10.3389/fmicb.2015.01460] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 12/07/2015] [Indexed: 01/06/2023] Open
Abstract
Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.
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Affiliation(s)
- Chloe R McDonald
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, TorontoON, Canada; Department of Global Health and Population, Harvard School of Public Health, BostonMA, USA
| | - Vanessa Tran
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, Toronto ON, Canada
| | - Kevin C Kain
- Sandra Rotman Laboratories, Sandra Rotman Centre for Global Health, Toronto General Research Institute, University Health Network, TorontoON, Canada; Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, TorontoON, Canada
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126
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Defining the Systemic Inflammatory Response Syndrome in Equine Neonates. Vet Clin North Am Equine Pract 2015; 31:463-81. [DOI: 10.1016/j.cveq.2015.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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127
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Skjeflo EW, Sagatun C, Dybwik K, Aam S, Urving SH, Nunn MA, Fure H, Lau C, Brekke OL, Huber-Lang M, Espevik T, Barratt-Due A, Nielsen EW, Mollnes TE. Combined inhibition of complement and CD14 improved outcome in porcine polymicrobial sepsis. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:415. [PMID: 26612199 PMCID: PMC4662001 DOI: 10.1186/s13054-015-1129-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/04/2015] [Indexed: 01/16/2023]
Abstract
Introduction Sepsis is an exaggerated and dysfunctional immune response to infection. Activation of innate immunity recognition systems including complement and the Toll-like receptor family initiate this disproportionate inflammatory response. The aim of this study was to explore the effect of combined inhibition of the complement component C5 and the Toll-like receptor co-factor CD14 on survival, hemodynamic parameters and systemic inflammation including complement activation in a clinically relevant porcine model of polymicrobial sepsis. Methods Norwegian landrace piglets (4 ± 0.5 kg) were blindly randomized to a treatment group (n = 12) receiving the C5 inhibitor coversin (OmCI) and anti-CD14 or to a positive control group (n = 12) receiving saline. Under anesthesia, sepsis was induced by a 2 cm cecal incision and the piglets were monitored in standard intensive care for 8 hours. Three sham piglets had a laparotomy without cecal incision or treatment. Complement activation was measured as sC5b-9 using enzyme immunoassay. Cytokines were measured with multiplex technology. Results Combined C5 and CD14 inhibition significantly improved survival (p = 0.03). Nine piglets survived in the treatment group and four in the control group. The treatment group had significantly lower pulmonary artery pressure (p = 0.04) and ratio of pulmonary artery pressure to systemic artery pressure (p < 0.001). Plasma sC5b-9 levels were significantly lower in the treatment group (p < 0.001) and correlated significantly with mortality (p = 0.006). IL-8 and IL-10 were significantly (p < 0.05) lower in the treatment group. Conclusions Combined inhibition of C5 and CD14 significantly improved survival, hemodynamic parameters and inflammation in a blinded, randomized trial of porcine polymicrobial sepsis.
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Affiliation(s)
- Espen W Skjeflo
- Research Laboratory, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway. .,Faculty of Health Sciences, K. G. Jebsen TREC, University of Tromsø, 9037, Tromsø, Norway.
| | - Caroline Sagatun
- Department of Surgery, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway.
| | - Knut Dybwik
- Department of Anestesiology, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway. .,Faculty of Professional Studies, University of Nordland, Universitetsaleen 11, 8049, Bodø, Norway.
| | - Sturla Aam
- Faculty of Medicine, Ludwig Maximillian University, Professor Huber Platz 2, 80539, Munich, Germany.
| | - Sven H Urving
- Department of Anestesiology, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway.
| | - Miles A Nunn
- Volution Immuno Pharmaceuticals Limited, 5 Argosy Court, Whitley Business Park, Coventry, CV3 4GA, UK.
| | - Hilde Fure
- Research Laboratory, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway.
| | - Corinna Lau
- Research Laboratory, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway.
| | - Ole-Lars Brekke
- Research Laboratory, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway. .,Faculty of Health Sciences, K. G. Jebsen TREC, University of Tromsø, 9037, Tromsø, Norway.
| | - Markus Huber-Lang
- Department of Traumatology, Center of Surgery, University of Ulm, Albert Einstein Allee 23, 89081, Ulm, Germany.
| | - Terje Espevik
- Centre of Molecular Inflammation Research, and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Høgskoleringen 1, 7491, Trondheim, Norway.
| | - Andreas Barratt-Due
- Department of Immunology, Oslo University Hospital and K.G. Jebsen IRC, University of Oslo, PB 4960 Nydalen, 0424, Oslo, Norway. .,Division of Emergencies and Critical Care, Rikshospitalet, Oslo University Hospital Oslo, Sognsvannsveien 20, 0372, Oslo, Norway.
| | - Erik W Nielsen
- Faculty of Health Sciences, K. G. Jebsen TREC, University of Tromsø, 9037, Tromsø, Norway. .,Department of Anestesiology, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway. .,Faculty of Professional Studies, University of Nordland, Universitetsaleen 11, 8049, Bodø, Norway. .,Department of Immunology, Oslo University Hospital and K.G. Jebsen IRC, University of Oslo, PB 4960 Nydalen, 0424, Oslo, Norway.
| | - Tom E Mollnes
- Research Laboratory, Nordland Hospital, Prinsens Gate 164, 8092, Bodø, Norway. .,Faculty of Health Sciences, K. G. Jebsen TREC, University of Tromsø, 9037, Tromsø, Norway. .,Centre of Molecular Inflammation Research, and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Høgskoleringen 1, 7491, Trondheim, Norway. .,Department of Immunology, Oslo University Hospital and K.G. Jebsen IRC, University of Oslo, PB 4960 Nydalen, 0424, Oslo, Norway.
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Experimental Malaria in Pregnancy Induces Neurocognitive Injury in Uninfected Offspring via a C5a-C5a Receptor Dependent Pathway. PLoS Pathog 2015; 11:e1005140. [PMID: 26402732 PMCID: PMC4581732 DOI: 10.1371/journal.ppat.1005140] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 08/11/2015] [Indexed: 02/06/2023] Open
Abstract
The in utero environment profoundly impacts childhood neurodevelopment and behaviour. A substantial proportion of pregnancies in Africa are at risk of malaria in pregnancy (MIP) however the impact of in utero exposure to MIP on fetal neurodevelopment is unknown. Complement activation, in particular C5a, may contribute to neuropathology and adverse outcomes during MIP. We used an experimental model of MIP and standardized neurocognitive testing, MRI, micro-CT and HPLC analysis of neurotransmitter levels, to test the hypothesis that in utero exposure to malaria alters neurodevelopment through a C5a-C5aR dependent pathway. We show that malaria-exposed offspring have persistent neurocognitive deficits in memory and affective-like behaviour compared to unexposed controls. These deficits were associated with reduced regional brain levels of major biogenic amines and BDNF that were rescued by disruption of C5a-C5aR signaling using genetic and functional approaches. Our results demonstrate that experimental MIP induces neurocognitive deficits in offspring and suggest novel targets for intervention. A growing body of evidence has established the importance of the in utero environment on neurodevelopment and long-term cognitive and behavioral outcomes. These data suggest factors that disrupt the tightly regulated in utero environment can modify normal neurodevelopmental processes. Approximately 125 million pregnancies worldwide are at risk of malaria infection every year. However the impact of in utero exposure to MIP on fetal neurodevelopment is unknown. Here we use a mouse model of malaria in pregnancy to examine the impact of maternal malaria exposure on neurocognitive outcomes in offspring. We observed impaired learning and memory and depressive-like behavior in malaria-exposed offspring that were neither congenitally infected nor low birth weight. These neurocognitive impairments were associated with decreased tissue levels of neurotransmitters in regions of the brain linked to the observed deficits. Disruption of maternal C5a complement receptor signaling restored the levels of neurotransmitters and rescued the associated cognitive phenotype observed in malaria-exposed offspring. This study provides the first evidence implicating a causal link between pre-natal exposure to malaria, complement signaling and subsequent neurocognitive impairment in offspring.
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129
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Lewis SM, Treacher DF, Edgeworth J, Mahalingam G, Brown CS, Mare TA, Stacey M, Beale R, Brown KA. Expression of CD11c and EMR2 on neutrophils: potential diagnostic biomarkers for sepsis and systemic inflammation. Clin Exp Immunol 2015; 182:184-94. [PMID: 26153037 DOI: 10.1111/cei.12679] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2015] [Indexed: 12/26/2022] Open
Abstract
There is a need for cellular biomarkers to differentiate patients with sepsis from those with the non-infectious systemic inflammatory response syndrome (SIRS). In this double-blind study we determined whether the expression of known (CD11a/b/c, CD62L) and putative adhesion molecules [CD64, CD97 and epidermal growth factor (EGF)-like molecule containing mucin-like hormone receptor (EMR2)] on blood neutrophils could serve as useful biomarkers of infection and of non-infectious SIRS in critically ill patients. We studied 103 patients with SIRS, 83 of whom had sepsis, and 50 healthy normal subjects, using flow cytometry to characterize neutrophils phenotypically in whole blood samples. Patients with SIRS had an increased prevalence of neutrophils expressing CD11c, CD64 and EMR2 in comparison with healthy subjects (P < 0.001), but normal expression of CD11a, CD11b, CD62L and CD97. An increase in the percentage of neutrophils bearing CD11c was associated with sepsis, EMR2 with SIRS and CD64 with sepsis and SIRS. Neutrophils expressing CD11c had the highest sensitivity (81%) and specificity (80%) for the detection of sepsis, and there was an association between the percentage of neutrophils expressing EMR2 and the extent of organ failure (P < 0.05). Contrary to other reports, we did not observe an abnormal expression of CD11b or CD62L on neutrophils from patients with SIRS, and suggest that this discrepancy is due to differences in cell processing protocols. We propose that blood neutrophils expressing CD11c and EMR2 be considered as potential biomarkers for sepsis and SIRS, respectively.
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Affiliation(s)
- S M Lewis
- Intensive Care Unit, Guy's and St Thomas' NHS Foundation Trust, London.,Department of Vascular Immunology, Division of Asthma, Allergy and Lung Biology, King's College London
| | - D F Treacher
- Intensive Care Unit, Guy's and St Thomas' NHS Foundation Trust, London
| | - J Edgeworth
- Department of Infection, Guy's and St Thomas' NHS Foundation Trust, University of Leeds, London, UK
| | - G Mahalingam
- Department of Vascular Immunology, Division of Asthma, Allergy and Lung Biology, King's College London
| | - C S Brown
- Intensive Care Unit, Guy's and St Thomas' NHS Foundation Trust, London
| | - T A Mare
- Intensive Care Unit, Guy's and St Thomas' NHS Foundation Trust, London.,Department of Vascular Immunology, Division of Asthma, Allergy and Lung Biology, King's College London
| | - M Stacey
- School of Molecular and Cellular Biology, University of Leeds, London, UK
| | - R Beale
- Intensive Care Unit, Guy's and St Thomas' NHS Foundation Trust, London.,Department of Vascular Immunology, Division of Asthma, Allergy and Lung Biology, King's College London
| | - K A Brown
- Intensive Care Unit, Guy's and St Thomas' NHS Foundation Trust, London.,Department of Vascular Immunology, Division of Asthma, Allergy and Lung Biology, King's College London
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130
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McDonald CR, Darling AM, Conroy AL, Tran V, Cabrera A, Liles WC, Wang M, Aboud S, Urassa W, Fawzi WW, Kain KC. Inflammatory and Angiogenic Factors at Mid-Pregnancy Are Associated with Spontaneous Preterm Birth in a Cohort of Tanzanian Women. PLoS One 2015; 10:e0134619. [PMID: 26247200 PMCID: PMC4527774 DOI: 10.1371/journal.pone.0134619] [Citation(s) in RCA: 16] [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: 02/28/2015] [Accepted: 07/11/2015] [Indexed: 01/08/2023] Open
Abstract
Research Question Preterm birth (PTB) is the leading cause of perinatal mortality worldwide, with the greatest burden occurring in resource-constrained settings. Based on the hypothesis that altered placental angiogenesis and inflammation early in pregnancy lead to PTB, we examined whether levels of inflammatory and angiogenic mediators, measured early in pregnancy, were predictive of spontaneous PTB (sPTB). Study Design Plasma samples were collected from a prospective cohort of primigravid Tanzanian women between 12–27 weeks gestation. A panel of 18 markers was screened on a training cohort of 426 women. Markers associated with sPTB in the training cohort were repeated in a test cohort of 628 women. All markers were measured by ELISA. Findings In both the training and test cohorts plasma levels of IL-18BP, sICAM-1, sEndoglin and CHI3L1 were elevated and Leptin was lower at enrollment in women who subsequently experienced sPTB. In multivariate analysis women with plasma levels of CHI3L1, C5a, sICAM-1, AngptL3, sEndgolin, sFlt-1 and IL-18BP in the highest quartile had an increased risk of sPTB compared with those in the lowest quartile. Women with Leptin and Ang2 in the highest quartile had a reduced risk of sPTB compared with women in the lowest quartile. Implications Levels of angiogenic and inflammatory mediators measured at mid-pregnancy were associated with subsequent sPTB. These findings provide insight into mechanisms underlying sPTB and suggest biomarkers that may have clinical utility in risk-stratifying pregnancies.
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Affiliation(s)
- Chloe R. McDonald
- SAR Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Anne M. Darling
- Department of Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Andrea L. Conroy
- SAR Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Canada
| | - Vanessa Tran
- SAR Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Canada
| | - Ana Cabrera
- SAR Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Canada
| | - W. Conrad Liles
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Molin Wang
- Department of Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Said Aboud
- Department of Microbiology and Immunology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Willy Urassa
- Department of Microbiology and Immunology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Wafaie W. Fawzi
- Department of Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Kevin C. Kain
- SAR Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, Canada
- * E-mail:
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131
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Allen KS, Sawheny E, Kinasewitz GT. Anticoagulant modulation of inflammation in severe sepsis. World J Crit Care Med 2015; 4:105-115. [PMID: 25938026 PMCID: PMC4411562 DOI: 10.5492/wjccm.v4.i2.105] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/13/2015] [Accepted: 02/09/2015] [Indexed: 02/06/2023] Open
Abstract
Inflammation and coagulation are so tightly linked that the cytokine storm which accompanies the development of sepsis initiates thrombin activation and the development of an intravascular coagulopathy. This review examines the interaction between the inflammatory and coagulation cascades, as well as the role of endogenous anticoagulants in regulating this interaction and dampening the activity of both pathways. Clinical trials attempting to improve outcomes in patients with severe sepsis by inhibiting thrombin generation with heparin and or endogenous anticoagulants are reviewed. In general, these trials have failed to demonstrate that anticoagulant therapy is associated with improvement in mortality or morbidity. While it is possible that selective patients who are severely ill with a high expected mortality may be shown to benefit from such therapy, at the present time none of these anticoagulants are neither approved nor can they be recommended for the treatment of sepsis.
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132
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Egge KH, Thorgersen EB, Pischke SE, Lindstad JK, Pharo A, Bongoni AK, Rieben R, Nunn MA, Barratt-Due A, Mollnes TE. Organ inflammation in porcine Escherichia coli sepsis is markedly attenuated by combined inhibition of C5 and CD14. Immunobiology 2015; 220:999-1005. [PMID: 25956456 DOI: 10.1016/j.imbio.2015.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 03/05/2015] [Accepted: 04/18/2015] [Indexed: 12/28/2022]
Abstract
Sepsis is an infection-induced systemic inflammatory syndrome, potentially causing organ failure. We previously showed attenuating effects on inflammation, thrombogenicity and haemodynamics by inhibiting the Toll-like receptor co-factor CD14 and complement factor C5 in a porcine Escherichia coli-induced sepsis model. The present study explored the effect on organ inflammation in these pigs. Tissue samples were examined from the combined treatment group (n = 8), the positive (n = 8) and negative (n = 6) control groups after 4h of sepsis. Inflammatory biomarkers were measured using ELISA, multiplex and qPCR analysis. Combined inhibition of C5 and CD14 markedly attenuated IL-1β by 31-66% (P < 0.05) and IL-6 by 54-96% (P < 0.01) in liver, kidney, lung and spleen; IL-8 by 65-100% in kidney, lung, spleen, and heart (P < 0.05) and MCP-1 by 46-69% in liver, kidney, spleen and heart (P < 0.05). Combined inhibition significantly attenuated tissue factor mRNA upregulation in spleen (P < 0.05) and IP-10 mRNA upregulation in four out of five organs. Finally, C5aR mRNA downregulation was prevented in heart and kidney (P < 0.05). Combined inhibition of C5 and CD14 thus markedly attenuated inflammatory responses in all organs examined. The anti-inflammatory effects observed in lung and heart may explain the delayed haemodynamic disturbances observed in septic pigs receiving combined inhibition of C5 and CD14.
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Affiliation(s)
- Kjetil H Egge
- Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway; K. G. Jebsen IRC, University of Oslo, Oslo, Norway
| | - Ebbe B Thorgersen
- Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway; K. G. Jebsen IRC, University of Oslo, Oslo, Norway; Department of Transplantation Medicine, Section for Transplant Surgery, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Søren E Pischke
- Interventional Center, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Julie K Lindstad
- Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway; K. G. Jebsen IRC, University of Oslo, Oslo, Norway
| | - Anne Pharo
- Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway; K. G. Jebsen IRC, University of Oslo, Oslo, Norway
| | - Anjan K Bongoni
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Robert Rieben
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Miles A Nunn
- Volution Immuno Pharmaceuticals Limited SA, London, United Kingdom
| | - Andreas Barratt-Due
- Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway; K. G. Jebsen IRC, University of Oslo, Oslo, Norway
| | - Tom E Mollnes
- Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway; K. G. Jebsen IRC, University of Oslo, Oslo, Norway; Research Laboratory, Nordland Hospital and Faculty of Health Sciences, K. G. Jebsen TREC, University of Tromsø, Tromsø, Norway; Centre of Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim, Norway.
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Abstract
The complement system is an essential component of the immune system. It is a highly integrative system and has a number of functions, including host defense, removal of injured cells and debris, modulation of metabolic and regenerative processes, and regulation of adaptive immunity. Complement is activated via different pathways and it is regulated tightly by several mechanisms to prevent host injury. Imbalance between complement activation and regulation can manifest in disease and injury to self. This article provides an outline of complement activation pathways, regulatory mechanisms, and normal physiologic functions of the system.
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Affiliation(s)
- Juan Carlos Varela
- Division of Hematology, Department of Medicine, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Stephen Tomlinson
- Department of Microbiology and Immunology, Ralph H. Johnson Veterans Affairs Medical Center, Medical University of South Carolina, Charleston, SC, USA.
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134
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Predictive value of the complement system for sepsis-induced disseminated intravascular coagulation in septic patients in emergency department. J Crit Care 2015; 30:290-5. [DOI: 10.1016/j.jcrc.2014.11.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 10/28/2014] [Accepted: 11/13/2014] [Indexed: 11/21/2022]
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135
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Duggan S, Leonhardt I, Hünniger K, Kurzai O. Host response to Candida albicans bloodstream infection and sepsis. Virulence 2015; 6:316-26. [PMID: 25785541 PMCID: PMC4601378 DOI: 10.4161/21505594.2014.988096] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Candida albicans is a major cause of bloodstream infection which may present as sepsis and septic shock - major causes of morbidity and mortality world-wide. After invasion of the pathogen, innate mechanisms govern the early response. Here, we outline the models used to study these mechanisms and summarize our current understanding of innate immune responses during Candida bloodstream infection. This includes protective immunity as well as harmful responses resulting in Candida induced sepsis. Neutrophilic granulocytes are considered principal effector cells conferring protection and recognize C. albicans mainly via complement receptor 3. They possess a range of effector mechanisms, contributing to elimination of the pathogen. Neutrophil activation is closely linked to complement and modulated by activated mononuclear cells. A thorough understanding of these mechanisms will help in creating an individualized approach to patients suffering from systemic candidiasis and aid in optimizing clinical management.
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Affiliation(s)
- Seána Duggan
- a Septomics Research Center ; Friedrich-Schiller-University and Leibniz-Institute for Natural Product Research and Infection Biology-Hans-Knoell-Institute ; Jena , Germany
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136
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Hünniger K, Bieber K, Martin R, Lehnert T, Figge MT, Löffler J, Guo RF, Riedemann NC, Kurzai O. A second stimulus required for enhanced antifungal activity of human neutrophils in blood is provided by anaphylatoxin C5a. THE JOURNAL OF IMMUNOLOGY 2014; 194:1199-210. [PMID: 25539819 DOI: 10.4049/jimmunol.1401845] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Polymorphonuclear neutrophilic granulocytes (PMN) as cellular components of innate immunity play a crucial role in the defense against systemic Candida albicans infection. To analyze stimuli that are required for PMN activity during C. albicans infection in a situation similar to in vivo, we used a human whole-blood infection model. In this model, PMN activation 10 min after C. albicans infection was largely dependent on the anaphylatoxin C5a. Most importantly, C5a enabled blood PMN to overcome filament-restricted recognition of C. albicans and allowed efficient elimination of nonfilamentous C. albicans cph1Δ/efg1Δ from blood. Major PMN effector mechanisms, including oxidative burst, release of secondary granule contents and initial fungal phagocytosis could be prevented by blocking C5a receptor signaling. Identical effects were achieved using a humanized Ab specifically targeting human C5a. Phagocytosis of C. albicans 10 min postinfection was mediated by C5a-dependent enhancement of CD11b surface expression on PMN, thus establishing the C5a-C5aR-CD11b axis as a major modulator of early anti-Candida immune responses in human blood. In contrast, phagocytosis of C. albicans by PMN 60 min postinfection occurred almost independently of C5a and mainly contributed to activation of phagocytically active PMN at later time points. Our results show that C5a is a critical mediator in human blood during C. albicans infection.
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Affiliation(s)
- Kerstin Hünniger
- Septomics Research Center, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany
| | - Kristin Bieber
- Septomics Research Center, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany
| | - Ronny Martin
- Septomics Research Center, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany
| | - Teresa Lehnert
- Applied Systems Biology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany; Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Marc Thilo Figge
- Applied Systems Biology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany; Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Jürgen Löffler
- Department of Internal Medicine II, University Hospital Wuerzburg, 97080 Wuerzburg, Germany
| | | | - Niels C Riedemann
- InflaRx GmbH, 07745 Jena, Germany; Department of Anesthesiology and Intensive Care Therapy, Jena University Hospital, 07747 Jena, Germany; Center for Sepsis Control and Care, Jena University Hospital, 07747 Jena, Germany; and
| | - Oliver Kurzai
- Septomics Research Center, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany; Center for Sepsis Control and Care, Jena University Hospital, 07747 Jena, Germany; and German National Reference Center for Invasive Fungal Infections, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, 07745 Jena, Germany
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137
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El-Shimy WS, El-Dib AS, Nagy HM, Sabry W. A study of IL-6, IL-8, and TNF-α as inflammatory markers in COPD patients. THE EGYPTIAN JOURNAL OF BRONCHOLOGY 2014. [DOI: 10.4103/1687-8426.145698] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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138
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An LL, Mehta P, Xu L, Turman S, Reimer T, Naiman B, Connor J, Sanjuan M, Kolbeck R, Fung M. Complement C5a potentiates uric acid crystal-induced IL-1β production. Eur J Immunol 2014; 44:3669-79. [PMID: 25229885 DOI: 10.1002/eji.201444560] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 08/05/2014] [Accepted: 09/11/2014] [Indexed: 12/11/2022]
Abstract
Anaphylatoxin C5a released upon complement activation is associated with both acute and chronic inflammations such as gout. The pathogenesis of gout was identified as uric acid crystal deposition in the joints that activates inflammasome, leading to IL-1β release. However, little is known about the interaction between complement activation and monosodium urate/uric acid (MSU) crystal-induced inflammasome activation or IL-1β production. Here, we report that MSU crystal-induced proinflammatory cytokines/chemokines in human whole blood is predominantly regulated by C5a through its interaction with C5a receptor. C5a induces pro-IL-1β and IL-1β production in human primary monocytes, and potentiates MSU or cholesterol crystals in IL-1β production. This potentiation is caspase-1 dependent and requires intracellular Ca(2+) mobilization, K(+) efflux, and cathepsin B activity. Our results provide insight into the role of C5a as an endogenous priming signal that is required for the initiation of uric acid crystal-induced IL-1β production. C5a could potentially be a therapeutic target together with IL-1β antagonists for the treatment of complement-dependent and inflammasome-associated diseases.
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Affiliation(s)
- Ling-Ling An
- Department of Respiratory, Inflammation and Autoimmune Diseases, MedImmune, LLC, Gaithersburg, MD, USA
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Lord JM, Midwinter MJ, Chen YF, Belli A, Brohi K, Kovacs EJ, Koenderman L, Kubes P, Lilford RJ. The systemic immune response to trauma: an overview of pathophysiology and treatment. Lancet 2014; 384:1455-65. [PMID: 25390327 PMCID: PMC4729362 DOI: 10.1016/s0140-6736(14)60687-5] [Citation(s) in RCA: 481] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Improvements in the control of haemorrhage after trauma have resulted in the survival of many people who would otherwise have died from the initial loss of blood. However, the danger is not over once bleeding has been arrested and blood pressure restored. Two-thirds of patients who die following major trauma now do so as a result of causes other than exsanguination. Trauma evokes a systemic reaction that includes an acute, non-specific, immune response associated, paradoxically, with reduced resistance to infection. The result is damage to multiple organs caused by the initial cascade of inflammation aggravated by subsequent sepsis to which the body has become susceptible. This Series examines the biological mechanisms and clinical implications of the cascade of events caused by large-scale trauma that leads to multiorgan failure and death, despite the stemming of blood loss. Furthermore, the stark and robust epidemiological finding--namely, that age has a profound influence on the chances of surviving trauma irrespective of the nature and severity of the injury--will be explored. Advances in our understanding of the inflammatory response to trauma, the impact of ageing on this response, and how this information has led to new and emerging treatments aimed at combating immune dysregulation and reduced immunity after injury will also be discussed.
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Affiliation(s)
- Janet M Lord
- MRC-ARUK Centre for Musculoskeletal Ageing Research, School of Immunity and Infection, University of Birmingham, Birmingham, UK; NIHR Surgical Reconstruction and Microbiology Research Centre, University of Birmingham, Birmingham, UK
| | - Mark J Midwinter
- NIHR Surgical Reconstruction and Microbiology Research Centre, University of Birmingham, Birmingham, UK; School of Health and Population Sciences, University of Birmingham, Birmingham, UK
| | - Yen-Fu Chen
- NIHR Surgical Reconstruction and Microbiology Research Centre, University of Birmingham, Birmingham, UK; School of Health and Population Sciences, University of Birmingham, Birmingham, UK; Division of Health Sciences, University of Warwick, Coventry, UK
| | - Antonio Belli
- NIHR Surgical Reconstruction and Microbiology Research Centre, University of Birmingham, Birmingham, UK; Neurotrauma and Neurodegeneration Section, University of Birmingham, Birmingham, UK
| | - Karim Brohi
- Centre for Trauma Sciences, Blizard Institute, Queen Mary University of London, London, UK
| | - Elizabeth J Kovacs
- Loyola University Chicago Health Sciences Campus, Stritch School of Medicine, Department of Surgery, Burn and Shock Trauma Institute, Maywood, IL, USA
| | - Leo Koenderman
- University Medical Centre Utrecht, Department of Respiratory Medicine, Utrecht, Netherlands
| | - Paul Kubes
- University of Calgary, Department of Physiology and Pharmacology, Calvin Phoebe and Joan Snyder Institute for Chronic Disease, Calgary, Canada
| | - Richard J Lilford
- School of Health and Population Sciences, University of Birmingham, Birmingham, UK; Division of Health Sciences, University of Warwick, Coventry, UK.
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140
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Microfluidic platform for the quantitative analysis of leukocyte migration signatures. Nat Commun 2014; 5:4787. [PMID: 25183261 PMCID: PMC4155519 DOI: 10.1038/ncomms5787] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 07/24/2014] [Indexed: 12/22/2022] Open
Abstract
Leukocyte migration into tissues is characteristic of inflammation. It is usually measured in vitro as the average displacement of populations of cells towards a chemokine gradient, not acknowledging other patterns of cell migration. Here, we designed and validated a microfluidic migration platform to simultaneously analyze four qualitative migration patterns: chemo-attraction, -repulsion, -kinesis and -inhibition, using single-cell quantitative metrics of direction, speed, persistence, and fraction of cells responding. We find that established chemokines C5a and IL-8 induce chemoattraction and repulsion in equal proportions, resulting in the dispersal of cells. These migration signatures are characterized by high persistence and speed and are independent of the chemokine dose or receptor expression. Furthermore, we find that twice as many T-lymphocytes migrate away than towards SDF-1 and their directional migration patterns are not persistent. Overall, our platform characterizes migratory signature responses and uncovers an avenue for precise characterization of leukocyte migration and therapeutic modulators.
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141
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Nonhematopoietic β-Arrestin-1 inhibits inflammation in a murine model of polymicrobial sepsis. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:2297-309. [PMID: 24946011 DOI: 10.1016/j.ajpath.2014.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 04/28/2014] [Accepted: 05/07/2014] [Indexed: 12/15/2022]
Abstract
β-Arrestin-1 (βArr1), a scaffolding protein critical in G-protein coupled receptor desensitization has more recently been found to be important in the pathogenesis of various inflammatory diseases. We sought to understand the role of βArr1 in sepsis pathogenesis using a mouse model of polymicrobial sepsis. Although in previous studies we established that βArr1 deficiency protects mice from endotoxemia, here we demonstrate that the absence of βArr1 remarkably renders mice more susceptible to mortality in polymicrobial sepsis. In accordance with the mortality pattern, early production of inflammatory mediators was markedly enhanced in βArr1 knockout mice systemically and locally in various organs. In addition, enhanced inflammation in the heart was associated with increased NFκB activation. Compared to these effects, immune cell infiltration, thymic apoptosis, and immune suppression during polymicrobial sepsis were unaffected by a deficiency of βArr1. Additionally, enhanced inflammation and consequent higher mortality were not observed in heterozygous mice, suggesting that one allele of βArr1 was sufficient for this protective negative regulatory role. We further demonstrate that, unexpectedly, βArr1 in nonhematopoietic cells is critical and sufficient for inhibiting sepsis-induced inflammation, whereas hematopoietic βArr1 is likely redundant. Taken together, our results reveal a novel and previously unrecognized negative regulatory role of the nonhematopoietic βArr1 in sepsis-induced inflammation.
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142
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Stang K, Krajewski S, Neumann B, Kurz J, Post M, Stoppelkamp S, Fennrich S, Avci-Adali M, Armbruster D, Schlensak C, Burgener IA, Wendel HP, Walker T. Hemocompatibility testing according to ISO 10993-4: discrimination between pyrogen- and device-induced hemostatic activation. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 42:422-8. [PMID: 25063137 DOI: 10.1016/j.msec.2014.05.070] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/07/2014] [Accepted: 05/30/2014] [Indexed: 12/14/2022]
Abstract
Next to good hemocompatibility performance of new medical devices, which has to be tested according to the ISO 10993-4, the detection of pyrogen-contaminated devices plays a pivotal role for safe device application. During blood contact with pyrogen-contaminated devices, intense inflammatory and hemostatic reactions are feared. The aim of our study was to investigate the influence of pyrogenic contaminations on stents according to the ISO 10993-4. The pyrogens of different origins like lipopolysaccharides (LPS), purified lipoteichoic acid (LTA) or zymosan were used. These pyrogens were dried on stents or dissolved and circulated in a Chandler-loop model for 90 min at 37°C with human blood. Before and after circulation, parameters of the hemostatic system including coagulation, platelets, complement and leukocyte activation were investigated. The complement system was activated by LPS isolated from Klebsiella pneumoniae and Pseudomonas aeruginosa and by LTA. Leukocyte activation was triggered by LPS isolated from K. pneumoniae, LTA and zymosan, whereas coagulation and platelet activation were only slightly influenced. Our data indicate that pyrogen-contaminated devices lead to an alteration in the hemostatic response when compared to depyrogenized devices. Therefore, pyrogenicity testing should be performed prior to hemocompatibility tests according to ISO 10993-4 in order to exclude hemostatic activation induced by pyrogen contaminations.
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Affiliation(s)
- Katharina Stang
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Stefanie Krajewski
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Bernd Neumann
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Julia Kurz
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Marcell Post
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Sandra Stoppelkamp
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Stefan Fennrich
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Meltem Avci-Adali
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Doris Armbruster
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany
| | - Christian Schlensak
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Iwan Anton Burgener
- Department of Small Animal Medicine, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 23, 04109 Leipzig, Germany.
| | - Hans Peter Wendel
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
| | - Tobias Walker
- Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany.
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143
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Kim JH, Oh SJ, Ahn S, Chung DH. IFN-γ-producing NKT cells exacerbate sepsis by enhancing C5a generation via IL-10-mediated inhibition of CD55 expression on neutrophils. Eur J Immunol 2014; 44:2025-35. [PMID: 24723363 DOI: 10.1002/eji.201343937] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 02/15/2014] [Accepted: 03/31/2014] [Indexed: 12/19/2022]
Abstract
A role for NKT cells has been implicated in sepsis, but the mechanism by which NKT cells contribute to sepsis remains unclear. Here, we examined WT and NKT-cell-deficient mice of C57BL/6 background during cecal ligation and puncture-induced sepsis. The levels of C5a, IFN-γ, and IL-10 were higher in the serum and peritoneal fluid of WT mice than in those of CD1d(-/-) mice, while the mortality rate was lower in CD1d(-/-) mice than in WT mice. C5a blockade decreased mortality of WT mice during sepsis, whereas it did not alter that of CD1d(-/-) mice. As assessed by intracellular staining, NKT cells expressed IFN-γ, while neutrophils expressed IL-10. Upon coculture, IL-10-deficient NKT cells enhanced IL-10 production by WT, but not IFN-γR-deficient, neutrophils. Meanwhile, CD1d(-/-) mice exhibited high CD55 expression on neutrophils during sepsis, whereas those cells from WT mice expressed minimal levels of CD55. Recombinant IL-10 administration into CD1d(-/-) mice reduced CD55 expression on neutrophils. Furthermore, adoptive transfer of sorted WT, but not IFN-γ-deficient, NKT cells into CD1d(-/-) mice suppressed CD55 expression on neutrophils, but increased IL-10 and C5a levels. Taken together, IFN-γ-producing NKT cells enhance C5a generation via IL-10-mediated inhibition of CD55 expression on neutrophils, thereby exacerbating sepsis.
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Affiliation(s)
- Ji Hyung Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea; Laboratory of Immune Regulation, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea; Ji Hyung Kim, Program in Cellular and Molecular Medicine at Children's Hospital, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
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144
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Huber-Lang M, Barratt-Due A, Pischke SE, Sandanger Ø, Nilsson PH, Nunn MA, Denk S, Gaus W, Espevik T, Mollnes TE. Double blockade of CD14 and complement C5 abolishes the cytokine storm and improves morbidity and survival in polymicrobial sepsis in mice. THE JOURNAL OF IMMUNOLOGY 2014; 192:5324-31. [PMID: 24790148 DOI: 10.4049/jimmunol.1400341] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Sepsis and septic shock, caused by an excessive systemic host-inflammatory response, are associated with high morbidity and mortality. The complement system and TLRs provide important pattern recognition receptors initiating the cytokine storm by extensive cross-talk. We hypothesized that double blockade of complement C5 and the TLR coreceptor CD14 could improve survival of experimental polymicrobial sepsis. Mice undergoing cecal ligation and puncture (CLP)-induced sepsis were treated with neutralizing anti-CD14 Ab biG 53, complement C5 inhibitor coversin (Ornithodoros moubata C inhibitor), or a combination thereof. The inflammatory study (24-h observation) revealed statistically significant increases in 22 of 24 measured plasma biomarkers in the untreated CLP group, comprising 14 pro- and anti-inflammatory cytokines and 8 chemokines, growth factors, and granulocyte activation markers. Single CD14 or C5 blockade significantly inhibited 20 and 19 of the 22 biomarkers, respectively. Combined CD14 and C5 inhibition significantly reduced all 22 biomarkers (mean reduction 85%; range 54-95%) compared with the untreated CLP group. Double blockade was more potent than single treatment and was required to significantly inhibit IL-6 and CXCL1. Combined inhibition significantly reduced morbidity (motility and eyelid movement) and mortality measured over 10 d. In the positive control CLP group, median survival was 36 h (range 24-48 h). Combined treatment increased median survival to 96 h (range 24-240 h) (p = 0.001), whereas survival in the single-treatment groups was not significantly increased (median and range for anti-CD14 and anti-C5 treatment were 36 h [24-48 h] and 48 h [24-96 h]). Combined with standard intervention therapy, specific blockade of CD14 and C5 might represent a promising new therapeutic strategy for treatment of polymicrobial sepsis.
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Affiliation(s)
- Markus Huber-Lang
- Department of Traumatology, Center of Surgery, University of Ulm, Ulm 89081, Germany
| | - Andreas Barratt-Due
- Department of Immunology, Oslo University Hospital, Rikshospitalet, University of Oslo, Oslo N-0027, Norway; K.G. Jebsen Inflammation Research Centre, University of Oslo, Oslo N-0027, Norway
| | - Søren E Pischke
- The Interventional Centre, Oslo University Hospital, Oslo N-0027, Norway; Department of Anesthesiology, Oslo University Hospital, Oslo N-0027, Norway
| | - Øystein Sandanger
- Research Institute of Internal Medicine, Oslo University Hospital, Oslo N-0027, Norway
| | - Per H Nilsson
- Department of Immunology, Oslo University Hospital, Rikshospitalet, University of Oslo, Oslo N-0027, Norway
| | - Miles A Nunn
- Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, United Kingdom
| | - Stephanie Denk
- Department of Traumatology, Center of Surgery, University of Ulm, Ulm 89081, Germany
| | - Wilhelm Gaus
- Department of Epidemiology and Biostatistics, University of Ulm, Ulm 89081, Germany
| | - Terje Espevik
- Centre of Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Tom E Mollnes
- Department of Immunology, Oslo University Hospital, Rikshospitalet, University of Oslo, Oslo N-0027, Norway; Centre of Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim 7491, Norway; Research Laboratory, Nordland Hospital Bodø, University of Tromsø, Tromsø 9019, Norway; and Faculty of Health Sciences, University of Tromsø, Tromsø 9019, Norway
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145
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C5a2 can modulate ERK1/2 signaling in macrophages via heteromer formation with C5a1 and β-arrestin recruitment. Immunol Cell Biol 2014; 92:631-9. [PMID: 24777312 DOI: 10.1038/icb.2014.32] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/02/2014] [Accepted: 04/02/2014] [Indexed: 01/08/2023]
Abstract
The complement system is a major component of our innate immune system, in which the complement proteins C5a and C5a-des Arg bind to two G-protein-coupled receptors: namely, the C5a receptor (C5a1) and C5a receptor like-2 receptor (C5a2, formerly called C5L2). Recently, it has been demonstrated that C5a, but not C5a-des Arg, upregulates heteromer formation between C5a1 and C5a2, leading to an increase in IL-10 release from human monocyte-derived macrophages (HMDMs). A bioluminescence resonance energy transfer (BRET) assay was used to assess the recruitment of β-arrestins by C5a and C5a-des Arg at the C5a1 and C5a2 receptors. C5a demonstrated elevated β-arrestin 2 recruitment levels in comparison with C5a-des Arg, whereas no significant difference was observed at C5a2. A constitutive complex that formed between β-arrestin 2 and C5a2 accounted for half of the BRET signal observed. Interestingly, both C5a and C5a-des Arg exhibited higher potency for β-arrestin 2 recruitment via C5a2, indicating preference for C5a2 over C5a1. When C5a was tested in a functional ERK1/2 assay in HMDMs, inhibition of ERK1/2 was observed only at concentrations at or above the EC50 for heteromer formation. This suggested that increased recruitment of the β-arrestin-C5a2 complex at these C5a concentrations might have an inhibitory role on C5a1 signaling through ERK1/2. An improved understanding of C5a2 modulation of signaling in acute inflammation could be of benefit in the development of ligands for conditions such as sepsis.
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146
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Skjeflo EW, Christiansen D, Espevik T, Nielsen EW, Mollnes TE. Combined inhibition of complement and CD14 efficiently attenuated the inflammatory response induced by Staphylococcus aureus in a human whole blood model. THE JOURNAL OF IMMUNOLOGY 2014; 192:2857-64. [PMID: 24516199 DOI: 10.4049/jimmunol.1300755] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The complement and TLR systems are activated in sepsis, contributing to an unfavorable inflammatory "storm." Combined inhibition of these systems has been documented to efficiently attenuate the inflammatory responses induced by Gram-negative bacteria. In this study, we hypothesized that the combined inhibition would attenuate the inflammatory responses induced by Gram-positive bacteria. Staphylococcus aureus bacteria (strains Cowan and Wood), as well as S. aureus cell wall lipoteichoic acid (LTA), were incubated in thrombin-inhibited human whole blood. Complement was inhibited at the level of C3 and C5, and the TLRs by inhibiting CD14 and TLR2. Thirty-four inflammatory markers were measured by multiplex technology and flow cytometry. Thirteen markers increased significantly in response to Cowan and Wood, and 12 in response to LTA. Combined inhibition with the C3 inhibitor compstatin and the anti-CD14 Ab 18D11 significantly reduced 92 (Cowan, LTA) and 85% (Wood) of these markers. Compstatin alone significantly reduced 54 (Cowan), 38 (Wood), and 83% (LTA), whereas anti-CD14 alone significantly reduced 23, 15, and 67%, respectively. Further experiments showed that the effects of complement inhibition were mainly due to inhibition of C5a interaction with the C5a receptor. The effects on inhibiting CD14 and TLR2 were similar. The combined regimen was more efficient toward the bacterial effects than either complement or anti-CD14 inhibition alone. Complement was responsible for activation of and phagocytosis by both granulocytes and monocytes. Disrupting upstream recognition by inhibiting complement and CD14 efficiently attenuated S. aureus-induced inflammation and might be a promising treatment in both Gram-negative and Gram-positive sepsis.
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147
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Resurrecting inactive antimicrobial peptides from the lipopolysaccharide trap. Antimicrob Agents Chemother 2014; 58:1987-96. [PMID: 24419338 DOI: 10.1128/aac.02321-13] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Host defense antimicrobial peptides (AMPs) are a promising source of antibiotics for the treatment of multiple-drug-resistant pathogens. Lipopolysaccharide (LPS), the major component of the outer leaflet of the outer membrane of Gram-negative bacteria, functions as a permeability barrier against a variety of molecules, including AMPs. Further, LPS or endotoxin is the causative agent of sepsis killing 100,000 people per year in the United States alone. LPS can restrict the activity of AMPs inducing aggregations at the outer membrane, as observed for frog AMPs, temporins, and also in model AMPs. Aggregated AMPs, "trapped" by the outer membrane, are unable to traverse the cell wall, causing their inactivation. In this work, we show that these inactive AMPs can overcome LPS-induced aggregations while conjugated with a short LPS binding β-boomerang peptide motif and become highly bactericidal. The generated hybrid peptides exhibit activity against Gram-negative and Gram-positive bacteria in high-salt conditions and detoxify endotoxin. Structural and biophysical studies establish the mechanism of action of these peptides in LPS outer membrane. Most importantly, this study provides a new concept for the development of a potent broad-spectrum antibiotic with efficient outer membrane disruption as the mode of action.
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148
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Ghosh A, Datta A, Jana J, Kar RK, Chatterjee C, Chatterjee S, Bhunia A. Sequence context induced antimicrobial activity: insight into lipopolysaccharide permeabilization. ACTA ACUST UNITED AC 2014; 10:1596-612. [DOI: 10.1039/c4mb00111g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Mechanistic insights into the permeabilization of the outer membrane of Gram negative bacteria by an antimicrobial peptide lactoferrampin, a 17 residue peptide, using high and low resolution spectroscopy in conjunction with MD simulation.
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Affiliation(s)
- Anirban Ghosh
- Biomolecular NMR and Drug Design Laboratory
- Department of Biophysics
- Bose Institute
- Kolkata 700054, India
| | - Aritreyee Datta
- Biomolecular NMR and Drug Design Laboratory
- Department of Biophysics
- Bose Institute
- Kolkata 700054, India
| | - Jagannath Jana
- Biomolecular NMR and Drug Design Laboratory
- Department of Biophysics
- Bose Institute
- Kolkata 700054, India
| | - Rajiv Kumar Kar
- Biomolecular NMR and Drug Design Laboratory
- Department of Biophysics
- Bose Institute
- Kolkata 700054, India
| | | | - Subhrangsu Chatterjee
- Biomolecular NMR and Drug Design Laboratory
- Department of Biophysics
- Bose Institute
- Kolkata 700054, India
| | - Anirban Bhunia
- Biomolecular NMR and Drug Design Laboratory
- Department of Biophysics
- Bose Institute
- Kolkata 700054, India
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149
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Zou L, Feng Y, Li Y, Zhang M, Chen C, Cai J, Gong Y, Wang L, Thurman JM, Wu X, Atkinson JP, Chao W. Complement factor B is the downstream effector of TLRs and plays an important role in a mouse model of severe sepsis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 191:5625-35. [PMID: 24154627 PMCID: PMC3906719 DOI: 10.4049/jimmunol.1301903] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Severe sepsis involves massive activation of the innate immune system and leads to high mortality. Previous studies have demonstrated that various types of TLRs mediate a systemic inflammatory response and contribute to organ injury and mortality in animal models of severe sepsis. However, the downstream mechanisms responsible for TLR-mediated septic injury are poorly understood. In this article, we show that activation of TLR2, TLR3, and TLR4 markedly enhanced complement factor B (cfB) synthesis and release by macrophages and cardiac cells. Polymicrobial sepsis, created by cecal ligation and puncture in a mouse model, augmented cfB levels in the serum, peritoneal cavity, and major organs including the kidney and heart. Cecal ligation and puncture also led to the alternative pathway activation, C3 fragment deposition in the kidney and heart, and cfB-dependent C3dg elevation. Bacteria isolated from septic mice activated the serum alternative pathway via a factor D-dependent manner. MyD88 deletion attenuated cfB/C3 upregulation as well as cleavage induced by polymicrobial infection. Importantly, during sepsis, absence of cfB conferred a protective effect with improved survival and cardiac function and markedly attenuated acute kidney injury. cfB deletion also led to increased neutrophil migratory function during the early phase of sepsis, decreased local and systemic bacterial load, attenuated cytokine production, and reduced neutrophil reactive oxygen species production. Together, our data indicate that cfB acts as a downstream effector of TLR signaling and plays a critical role in the pathogenesis of severe bacterial sepsis.
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Affiliation(s)
- Lin Zou
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Yan Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Yan Li
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Ming Zhang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Chan Chen
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Jiayan Cai
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Yu Gong
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Larry Wang
- Pathology and Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA
| | - Joshua M. Thurman
- Department of Medicine, University of Colorado Denver School of Medicine, Aurora, CO
| | - Xiaobo Wu
- Department of Medicine, Washington University School of Medicine, St Louis, MO
| | - John P. Atkinson
- Department of Medicine, Washington University School of Medicine, St Louis, MO
| | - Wei Chao
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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150
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Croker DE, Halai R, Fairlie DP, Cooper MA. C5a, but not C5a-des Arg, induces upregulation of heteromer formation between complement C5a receptors C5aR and C5L2. Immunol Cell Biol 2013; 91:625-33. [PMID: 24060963 DOI: 10.1038/icb.2013.48] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 08/21/2013] [Accepted: 08/22/2013] [Indexed: 11/09/2022]
Abstract
Receptors for C5a have an important role in innate immunity and inflammation where their expression and activation is tightly regulated. There are two known receptors for C5a: the C5a receptor (C5aR) and the C5a receptor like-2 (C5L2) receptor. Here we hypothesized that activation of C5aR might lead to heteromer formation with C5L2, as a downregulatory mechanism for C5aR signaling. To investigate this experimentally, bioluminescent resonance energy transfer (BRET) was implemented and supported by wide-field microscopy to analyze receptor localization in transfected HEK293 cells and human monocyte-derived macrophages (HMDM). BRET experiments indicated the presence of constitutive C5aR-C5L2 heteromers, where C5a, but not C5a-des Arg, was able to induce further heteromer formation, which was inhibited by a C5aR-specific antagonist. The data obtained suggest that C5aR-C5L2 can form heteromers in a process enhanced by C5a, but not by C5a-des Arg. There was also a significant difference in the levels of the anti-inflammatory cytokine IL-10 detected in HMDM following exposure to C5a compared with that seen for C5a-des Arg but no differences in the pro-inflammatory cytokines TNFα and IL-6. These subtle differences in C5a and C5a-des Arg induced receptor function may be of benefit in understanding the regulation of C5a in acute inflammation.
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Affiliation(s)
- Daniel E Croker
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
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