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Shaughnessy J, Chabeda A, Lewis LA, Ram S. Alternative pathway amplification and infections. Immunol Rev 2023; 313:162-180. [PMID: 36336911 DOI: 10.1111/imr.13160] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The alternative pathway (AP) is the phylogenetically oldest arm of the complement system and may have evolved to mark pathogens for elimination by phagocytes. Studies using purified AP proteins or AP-specific serum showed that C3b amplification on bacteria commenced following a lag phase of about 5 min and was highly dependent on the concentration of complement. Most pathogens have evolved several elegant mechanisms to evade complement, including expressing proteases that degrade AP proteins and secreting proteins that block function of C3 convertases. In an example of convergent evolution, many microbes recruit the AP inhibitor factor H (FH) using molecular mechanisms that mimic FH interactions with host cells. In most instances, the AP serves to amplify C3b deposited on microbes by the classical pathway (CP). The role of properdin on microbes appears to be restricted to stabilization of C3 convertases; scant evidence exists for its role as an initiator of the AP on pathogens in the context of serum. Therapeutic complement inhibition carries with it an increased risk of infection. Antibody (Ab)-dependent AP activation may be critical for complement activation by vaccine-elicited Ab when the CP is blocked, and its molecular mechanism is discussed.
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Affiliation(s)
- Jutamas Shaughnessy
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Aleyo Chabeda
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Lisa A Lewis
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Sanjay Ram
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
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2
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Zhou Y, Yan K, Qin Q, Raimi OG, Du C, Wang B, Ahamefule CS, Kowalski B, Jin C, van Aalten DMF, Fang W. Phosphoglucose Isomerase Is Important for Aspergillus fumigatus Cell Wall Biogenesis. mBio 2022; 13:e0142622. [PMID: 35913157 PMCID: PMC9426556 DOI: 10.1128/mbio.01426-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Aspergillus fumigatus is a devastating opportunistic fungal pathogen causing hundreds of thousands of deaths every year. Phosphoglucose isomerase (PGI) is a glycolytic enzyme that converts glucose-6-phosphate to fructose-6-phosphate, a key precursor of fungal cell wall biosynthesis. Here, we demonstrate that the growth of A. fumigatus is repressed by the deletion of pgi, which can be rescued by glucose and fructose supplementation in a 1:10 ratio. Even under these optimized growth conditions, the Δpgi mutant exhibits severe cell wall defects, retarded development, and attenuated virulence in Caenorhabditis elegans and Galleria mellonella infection models. To facilitate exploitation of A. fumigatus PGI as an antifungal target, we determined its crystal structure, revealing potential avenues for developing inhibitors, which could potentially be used as adjunctive therapy in combination with other systemic antifungals. IMPORTANCE Aspergillus fumigatus is an opportunistic fungal pathogen causing deadly infections in immunocompromised patients. Enzymes essential for fungal survival and cell wall biosynthesis are considered potential drug targets against A. fumigatus. PGI catalyzes the second step of the glycolysis pathway, linking glycolysis and the pentose phosphate pathway. As such, PGI has been widely considered as a target for metabolic regulation and therefore a therapeutic target against hypoxia-related diseases. Our study here reveals that PGI is important for A. fumigatus survival and exhibit pleiotropic functions, including development, cell wall glucan biosynthesis, and virulence. We also solved the crystal structure of PGI, thus providing the genetic and structural groundwork for the exploitation of PGI as a potential antifungal target.
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Affiliation(s)
- Yao Zhou
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Kaizhou Yan
- School of Life Sciences, University of Dundeegrid.8241.f, Dundee, United Kingdom
| | - Qijian Qin
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
| | - Olawale G. Raimi
- School of Life Sciences, University of Dundeegrid.8241.f, Dundee, United Kingdom
| | - Chao Du
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Bin Wang
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
| | - Chukwuemeka Samson Ahamefule
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
| | - Bartosz Kowalski
- School of Life Sciences, University of Dundeegrid.8241.f, Dundee, United Kingdom
| | - Cheng Jin
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | | | - Wenxia Fang
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
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3
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Cortes C, Desler C, Mazzoli A, Chen JY, Ferreira VP. The role of properdin and Factor H in disease. Adv Immunol 2022; 153:1-90. [PMID: 35469595 DOI: 10.1016/bs.ai.2021.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The complement system consists of three pathways (alternative, classical, and lectin) that play a fundamental role in immunity and homeostasis. The multifunctional role of the complement system includes direct lysis of pathogens, tagging pathogens for phagocytosis, promotion of inflammatory responses to control infection, regulation of adaptive cellular immune responses, and removal of apoptotic/dead cells and immune complexes from circulation. A tight regulation of the complement system is essential to avoid unwanted complement-mediated damage to the host. This regulation is ensured by a set of proteins called complement regulatory proteins. Deficiencies or malfunction of these regulatory proteins may lead to pro-thrombotic hematological diseases, renal and ocular diseases, and autoimmune diseases, among others. This review focuses on the importance of two complement regulatory proteins of the alternative pathway, Factor H and properdin, and their role in human diseases with an emphasis on: (a) characterizing the main mechanism of action of Factor H and properdin in regulating the complement system and protecting the host from complement-mediated attack, (b) describing the dysregulation of the alternative pathway as a result of deficiencies, or mutations, in Factor H and properdin, (c) outlining the clinical findings, management and treatment of diseases associated with mutations and deficiencies in Factor H, and (d) defining the unwanted and inadequate functioning of properdin in disease, through a discussion of various experimental research findings utilizing in vitro, mouse and human models.
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Affiliation(s)
- Claudio Cortes
- Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI, United States.
| | - Caroline Desler
- Oakland University William Beaumont School of Medicine, Rochester, MI, United States
| | - Amanda Mazzoli
- Oakland University William Beaumont School of Medicine, Rochester, MI, United States
| | - Jin Y Chen
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States.
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4
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Lewis LA, Ram S. Complement interactions with the pathogenic Neisseriae: clinical features, deficiency states, and evasion mechanisms. FEBS Lett 2020; 594:2670-2694. [PMID: 32058583 DOI: 10.1002/1873-3468.13760] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/04/2020] [Accepted: 02/09/2020] [Indexed: 02/06/2023]
Abstract
Neisseria gonorrhoeae causes the sexually transmitted infection gonorrhea, while Neisseria meningitidis is an important cause of bacterial meningitis and sepsis. Complement is a central arm of innate immune defenses and plays an important role in combating Neisserial infections. Persons with congenital and acquired defects in complement are at a significantly higher risk for invasive Neisserial infections such as invasive meningococcal disease and disseminated gonococcal infection compared to the general population. Of note, Neisseria gonorrhoeae and Neisseria meningitidis can only infect humans, which in part may be related to their ability to evade only human complement. This review summarizes the epidemiologic and clinical aspects of Neisserial infections in persons with defects in the complement system. Mechanisms used by these pathogens to subvert killing by complement and preclinical studies showing how these complement evasion strategies may be used to counteract the global threat of meningococcal and gonococcal infections are discussed.
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Affiliation(s)
- Lisa A Lewis
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Sanjay Ram
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA, USA
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5
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Hester MM, Lee CK, Abraham A, Khoshkenar P, Ostroff GR, Levitz SM, Specht CA. Protection of mice against experimental cryptococcosis using glucan particle-based vaccines containing novel recombinant antigens. Vaccine 2019; 38:620-626. [PMID: 31699504 DOI: 10.1016/j.vaccine.2019.10.051] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 11/27/2022]
Abstract
Meningitis due to Cryptococcus neoformans is responsible for upwards of 180,000 deaths worldwide annually, mostly in immunocompromised individuals. Currently there are no licensed fungal vaccines, and even with anti-fungal drug treatment, cryptococcal meningitis is often fatal. Our lab previously demonstrated vaccination with recombinant cryptococcal proteins delivered in glucan particles (GPs) protects mice against an otherwise lethal infection. The aim of the present study was to discover additional cryptococcal antigens affording vaccine-mediated protection. Sixteen proteins, each with evidence of extracellularity, were selected for in vivo testing based on their abundance in protective alkaline extracts of an acapsular C. neoformans strain, their known immunogenicity, and/or their high transcript level during human infection. Candidate antigens were recombinantly expressed in E. coli, purified and loaded into GPs. BALB/c and C57BL/6 mice received three subcutaneous injections of GP-based vaccine, and survival was assessed for 84 days following a lethal orotracheal challenge with strain KN99. As with our six published GP-vaccines, we saw differences in overall protection between mouse strains such that BALB/c mice typically demonstrated better survival than C57BL/6 mice. From these studies, we identified seven new proteins which, when administered as GP-vaccines, protect BALB/c and/or C57BL/6 mice against cryptococcal infection. With these results, we expand the pool of novel protective antigens to eleven proteins and demonstrate the potential for selection of highly transcribed extracellular proteins as vaccine targets. These screens highlight the efficacy of GP-subunit vaccines and identify promising antigens for further testing in anti-cryptococcal, multi-epitope vaccine formulations.
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Affiliation(s)
- Maureen M Hester
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Chrono K Lee
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Ambily Abraham
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Payam Khoshkenar
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Gary R Ostroff
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Stuart M Levitz
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Charles A Specht
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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6
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Abraham A, Ostroff G, Levitz SM, Oyston PCF. A novel vaccine platform using glucan particles for induction of protective responses against Francisella tularensis and other pathogens. Clin Exp Immunol 2019; 198:143-152. [PMID: 31400225 PMCID: PMC6797901 DOI: 10.1111/cei.13356] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2019] [Indexed: 12/13/2022] Open
Abstract
Vaccines are considered the bedrock of preventive medicine. However, for many pathogens, it has been challenging to develop vaccines that stimulate protective, long-lasting immunity. We have developed a novel approach using β-1,3-D-glucans (BGs), natural polysaccharides abundantly present in fungal cell walls, as a biomaterial platform for vaccine delivery. BGs simultaneously provide for receptor-targeted antigen delivery to specialized antigen-presenting cells together with adjuvant properties to stimulate antigen-specific and trained non-specific immune responses. This review focuses on various approaches of using BG particles (GPs) to develop bacterial and fungal vaccine candidates. A special case history for the development of an effective GP tularaemia vaccine candidate is highlighted.
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Affiliation(s)
- A. Abraham
- University of Massachusetts Medical SchoolWorcesterMassachusettsUSA
| | - G. Ostroff
- University of Massachusetts Medical SchoolWorcesterMassachusettsUSA
| | - S. M. Levitz
- University of Massachusetts Medical SchoolWorcesterMassachusettsUSA
| | - P. C. F. Oyston
- CBR Division, Defence Science and Technology Laboratory, Porton DownSalisburyUK
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7
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Michels MAHM, Volokhina EB, van de Kar NCAJ, van den Heuvel LPWJ. The role of properdin in complement-mediated renal diseases: a new player in complement-inhibiting therapy? Pediatr Nephrol 2019; 34:1349-1367. [PMID: 30141176 PMCID: PMC6579773 DOI: 10.1007/s00467-018-4042-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 07/31/2018] [Accepted: 08/03/2018] [Indexed: 12/16/2022]
Abstract
Properdin is known as the only positive regulator of the complement system. Properdin promotes the activity of this defense system by stabilizing its key enzymatic complexes: the complement alternative pathway (AP) convertases. Besides, some studies have indicated a role for properdin as an initiator of complement activity. Though the AP is a powerful activation route of the complement system, it is also involved in a wide variety of autoimmune and inflammatory diseases, many of which affect the kidneys. The role of properdin in regulating complement in health and disease has not received as much appraisal as the many negative AP regulators, such as factor H. Historically, properdin deficiency has been strongly associated with an increased risk for meningococcal disease. Yet only recently had studies begun to link properdin to other complement-related diseases, including renal diseases. In the light of the upcoming complement-inhibiting therapies, it is interesting whether properdin can be a therapeutic target to attenuate AP-mediated injury. A full understanding of the basic concepts of properdin biology is therefore needed. Here, we first provide an overview of the function of properdin in health and disease. Then, we explore its potential as a therapeutic target for the AP-associated renal diseases C3 glomerulopathy, atypical hemolytic uremic syndrome, and proteinuria-induced tubulointerstitial injury. Considering current knowledge, properdin-inhibiting therapy seems promising in certain cases. However, knowing the complexity of properdin's role in renal pathologies in vivo, further research is required to clarify the exact potential of properdin-targeted therapy in complement-mediated renal diseases.
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Affiliation(s)
- Marloes A. H. M. Michels
- Radboud Institute for Molecular Life Sciences, Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Geert Grooteplein Zuid 10, PO Box 9101, 6525 GA Nijmegen, The Netherlands
| | - Elena B. Volokhina
- Radboud Institute for Molecular Life Sciences, Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Geert Grooteplein Zuid 10, PO Box 9101, 6525 GA Nijmegen, The Netherlands ,Department of Laboratory Medicine, Radboud University Medical Center, Geert Grooteplein Zuid 10, PO Box 9101, 6525 GA Nijmegen, The Netherlands
| | - Nicole C. A. J. van de Kar
- Radboud Institute for Molecular Life Sciences, Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Geert Grooteplein Zuid 10, PO Box 9101, 6525 GA Nijmegen, The Netherlands
| | - Lambertus P. W. J. van den Heuvel
- Radboud Institute for Molecular Life Sciences, Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center, Geert Grooteplein Zuid 10, PO Box 9101, 6525 GA Nijmegen, The Netherlands ,Department of Laboratory Medicine, Radboud University Medical Center, Geert Grooteplein Zuid 10, PO Box 9101, 6525 GA Nijmegen, The Netherlands ,Department of Pediatrics/Pediatric Nephrology and Department of Development & Regeneration, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
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8
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Chen JY, Cortes C, Ferreira VP. Properdin: A multifaceted molecule involved in inflammation and diseases. Mol Immunol 2018; 102:58-72. [PMID: 29954621 DOI: 10.1016/j.molimm.2018.05.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/16/2018] [Accepted: 05/23/2018] [Indexed: 01/17/2023]
Abstract
Properdin, the widely known positive regulator of the alternative pathway (AP), has undergone significant investigation over the last decade to define its function in inflammation and disease, including its role in arthritis, asthma, and kidney and cardiovascular diseases. Properdin is a glycoprotein found in plasma that is mainly produced by leukocytes and can positively regulate AP activity by stabilizing C3 and C5 convertases and initiating the AP. Promotion of complement activity by properdin results in changes in the cellular microenvironment that contribute to innate and adaptive immune responses, including pro-inflammatory cytokine production, immune cell infiltration, antigen presenting cell maturation, and tissue damage. The use of properdin-deficient mouse models and neutralizing antibodies has contributed to the understanding of the mechanisms by which properdin contributes to promoting or preventing disease pathology. This review mainly focusses on the multifaceted roles of properdin in inflammation and diseases, and how understanding these roles is contributing to the development of new disease therapies.
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Affiliation(s)
- Jin Y Chen
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States.
| | - Claudio Cortes
- Department of Biomedical Sciences, University of Oakland University School of Medicine, Rochester, MI, United States.
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States.
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9
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Al-Mozaini MA, Tsolaki AG, Abdul-Aziz M, Abozaid SM, Al-Ahdal MN, Pathan AA, Murugaiah V, Makarov EM, Kaur A, Sim RB, Kishore U, Kouser L. Human Properdin Modulates Macrophage: Mycobacterium bovis BCG Interaction via Thrombospondin Repeats 4 and 5. Front Immunol 2018; 9:533. [PMID: 29867915 PMCID: PMC5951972 DOI: 10.3389/fimmu.2018.00533] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 03/01/2018] [Indexed: 02/01/2023] Open
Abstract
Mycobacterium tuberculosis can proficiently enter macrophages and diminish complement activation on its cell surface. Within macrophages, the mycobacterium can suppress macrophage apoptosis and survive within the intracellular environment. Previously, we have shown that complement regulatory proteins such as factor H may interfere with pathogen–macrophage interactions during tuberculosis infection. In this study, we show that Mycobacterium bovis BCG binds properdin, an upregulator of the complement alternative pathway. TSR4+5, a recombinant form of thrombospondin repeats 4 and 5 of human properdin expressed in tandem, which is an inhibitor of the alternative pathway, was also able to bind to M. bovis BCG. Properdin and TSR4+5 were found to inhibit uptake of M. bovis BCG by THP-1 macrophage cells in a dose-dependent manner. Quantitative real-time PCR revealed elevated pro-inflammatory responses (TNF-α, IL-1β, and IL-6) in the presence of properdin or TSR4+5, which gradually decreased over 6 h. Correspondingly, anti-inflammatory responses (IL-10 and TGF-β) showed suppressed levels of expression in the presence of properdin, which gradually increased over 6 h. Multiplex cytokine array analysis also revealed that properdin and TSR4+5 significantly enhanced the pro-inflammatory response (TNF-α, IL-1β, and IL-1α) at 24 h, which declined at 48 h, whereas the anti-inflammatory response (IL-10) was suppressed. Our results suggest that properdin may interfere with mycobacterial entry into macrophages via TSR4 and TSR5, particularly during the initial stages of infection, thus affecting the extracellular survival of the pathogen. This study offers novel insights into the non-complement related functions of properdin during host–pathogen interactions in tuberculosis.
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Affiliation(s)
- Maha Ahmed Al-Mozaini
- College of Health and Life Sciences, Brunel University London, London, United Kingdom.,Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Anthony G Tsolaki
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Munirah Abdul-Aziz
- College of Health and Life Sciences, Brunel University London, London, United Kingdom.,Department of Biochemistry, Oxford University, Oxford, United Kingdom
| | - Suhair M Abozaid
- College of Health and Life Sciences, Brunel University London, London, United Kingdom.,Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Mohammed N Al-Ahdal
- Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Ansar A Pathan
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Valarmathy Murugaiah
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Evgeny M Makarov
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Anuvinder Kaur
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Robert B Sim
- Department of Biochemistry, Oxford University, Oxford, United Kingdom
| | - Uday Kishore
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Lubna Kouser
- College of Health and Life Sciences, Brunel University London, London, United Kingdom
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10
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Harrison RA. The properdin pathway: an "alternative activation pathway" or a "critical amplification loop" for C3 and C5 activation? Semin Immunopathol 2017; 40:15-35. [PMID: 29167939 DOI: 10.1007/s00281-017-0661-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/30/2017] [Indexed: 11/28/2022]
Abstract
This review is not intended to cover in detail all aspects of the discovery and evolution of our understanding of the "alternative pathway" of complement activation, there are many excellent reviews that do this (see Fearon (CRC Crit Rev Immunol 1:1-32, 1979), Pangburn and Müller-Eberhard (Springer Semin Immunopathol 7:163-192, 1984)), but instead to give sufficient background for current concepts to be put in context. The prevailing textbook view, of components having a primary role as an alternative "pathway" for C3 activation, is challenged, with an argument developed for the primary role of the system being that of providing a surface-dependent amplification loop for both C3 and C5 activation. Whatever the mechanism by which the initial C3b molecule is generated, deposition onto a surface has the potential to target that surface for elimination. Elimination or escape from initial targeting is determined by a sophisticated and highly regulated amplification loop for C3 activation. This viewpoint of the system is then briefly developed to provide a context for therapeutic treatment of disease caused, at least in part, by dysregulated amplification of C3 activation, and to highlight some of the challenges that such therapies will face and need to address.
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Affiliation(s)
- Richard A Harrison
- Institute of Infection and Immunity, School of Medicine, Cardiff University, Henry Wellcome Building, Heath Park, Cardiff, CF14 4XN, UK.
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11
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Blatt AZ, Pathan S, Ferreira VP. Properdin: a tightly regulated critical inflammatory modulator. Immunol Rev 2017; 274:172-190. [PMID: 27782331 PMCID: PMC5096056 DOI: 10.1111/imr.12466] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The complement alternative pathway is a powerful arm of the innate immune system that enhances diverse inflammatory responses in the human host. Key to the effects of the alternative pathway is properdin, a serum glycoprotein that can both initiate and positively regulate alternative pathway activity. Properdin is produced by many different leukocyte subsets and circulates as cyclic oligomers of monomeric subunits. While the formation of non‐physiological aggregates in purified properdin preparations and the presence of potential properdin inhibitors in serum have complicated studies of its function, properdin has, regardless, emerged as a key player in various inflammatory disease models. Here, we review basic properdin biology, emphasizing the major hurdles that have complicated the interpretation of results from properdin‐centered studies. In addition, we elaborate on an emerging role for properdin in thromboinflammation and discuss the potential utility of properdin inhibitors as long‐term therapeutic options to treat diseases marked by increased formation of platelet/granulocyte aggregates. Finally, we describe the interplay between properdin and the alternative pathway negative regulator, Factor H, and how aiming to understand these interactions can provide scientists with the most effective ways to manipulate alternative pathway activation in complex systems.
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Affiliation(s)
- Adam Z Blatt
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Sabina Pathan
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA.
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12
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Ma YJ, Lee BL, Garred P. An overview of the synergy and crosstalk between pentraxins and collectins/ficolins: their functional relevance in complement activation. Exp Mol Med 2017; 49:e320. [PMID: 28428631 PMCID: PMC6130212 DOI: 10.1038/emm.2017.51] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 12/30/2016] [Indexed: 02/07/2023] Open
Abstract
The complement system is an innate immune defense machinery comprising components that deploy rapid immune responses and provide efficient protection against foreign invaders and unwanted host elements. The complement system is activated upon recognition of pathogenic microorganisms or altered self-cells by exclusive pattern recognition molecules (PRMs), such as collectins, ficolins and pentraxins. Recent accumulating evidence shows that the different classes of effector PRMs build up a co-operative network and exert synergistic effects on complement activation. In this review, we describe our updated view of the crosstalk between previously unlinked PRMs in complement activation and the potential pathogenic effects during infection and inflammation.
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Affiliation(s)
- Ying Jie Ma
- The Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bok Luel Lee
- National Research Laboratory of Defense Proteins, College of Pharmacy, Pusan National University, Busan, Korea
| | - Peter Garred
- The 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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13
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Aspergillus Cell Wall Chitin Induces Anti- and Proinflammatory Cytokines in Human PBMCs via the Fc-γ Receptor/Syk/PI3K Pathway. mBio 2016; 7:mBio.01823-15. [PMID: 27247234 PMCID: PMC4895119 DOI: 10.1128/mbio.01823-15] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Chitin is an important cell wall component of Aspergillus fumigatus conidia, of which hundreds are inhaled on a daily basis. Previous studies have shown that chitin has both anti- and proinflammatory properties; however the exact mechanisms determining the inflammatory signature of chitin are poorly understood, especially in human immune cells. Human peripheral blood mononuclear cells were isolated from healthy volunteers and stimulated with chitin from Aspergillus fumigatus Transcription and production of the proinflammatory cytokine interleukin-1β (IL-1β) and the anti-inflammatory cytokine IL-1 receptor antagonist (IL-1Ra) were measured from the cell culture supernatant by quantitative PCR (qPCR) or enzyme-linked immunosorbent assay (ELISA), respectively. Chitin induced an anti-inflammatory signature characterized by the production of IL-1Ra in the presence of human serum, which was abrogated in immunoglobulin-depleted serum. Fc-γ-receptor-dependent recognition and phagocytosis of IgG-opsonized chitin was identified as a novel IL-1Ra-inducing mechanism by chitin. IL-1Ra production induced by chitin was dependent on Syk kinase and phosphatidylinositol 3-kinase (PI3K) activation. In contrast, costimulation of chitin with the pattern recognition receptor (PRR) ligands lipopolysaccharide, Pam3Cys, or muramyl dipeptide, but not β-glucan, had synergistic effects on the induction of proinflammatory cytokines by human peripheral blood mononuclear cells (PBMCs). In conclusion, chitin can have both pro- and anti-inflammatory properties, depending on the presence of pathogen-associated molecular patterns and immunoglobulins, thus explaining the various inflammatory signatures reported for chitin. IMPORTANCE Invasive aspergillosis and allergic aspergillosis are increasing health care problems. Patients get infected by inhalation of the airborne spores of Aspergillus fumigatus A profound knowledge of how Aspergillus and its cell wall components are recognized by the host cell and which type of immune response it induces is necessary to develop target-specific treatment options with less severe side effects than the treatment options to date. There is controversy in the literature about the receptor for chitin in human cells. We identified the Fc-γ receptor and Syk/PI3K pathway via which chitin can induce anti-inflammatory immune responses by inducing IL-1 receptor antagonist in the presence of human immunoglobulins but also proinflammatory responses in the presence of bacterial components. This explains why Aspergillus does not induce strong inflammation just by inhalation and rather fulfills an immune-dampening function. While in a lung coinfected with bacteria, Aspergillus augments immune responses by shifting toward a proinflammatory reaction.
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Cagliani R, Forni D, Filippi G, Mozzi A, De Gioia L, Pontremoli C, Pozzoli U, Bresolin N, Clerici M, Sironi M. The mammalian complement system as an epitome of host-pathogen genetic conflicts. Mol Ecol 2016; 25:1324-39. [PMID: 26836579 DOI: 10.1111/mec.13558] [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: 09/21/2015] [Revised: 12/29/2015] [Accepted: 01/27/2016] [Indexed: 12/11/2022]
Abstract
The complement system is an innate immunity effector mechanism; its action is antagonized by a wide array of pathogens and complement evasion determines the virulence of several infections. We investigated the evolutionary history of the complement system and of bacterial-encoded complement-interacting proteins. Complement components targeted by several pathogens evolved under strong selective pressure in primates, with selection acting on residues at the contact interface with microbial/viral proteins. Positively selected sites in CFH and C4BPA account for the human specificity of gonococcal infection. Bacterial interactors, evolved adaptively as well, with selected sites located at interaction surfaces with primate complement proteins. These results epitomize the expectation under a genetic conflict scenario whereby the host's and the pathogen's genes evolve within binding avoidance-binding seeking dynamics. In silico mutagenesis and protein-protein docking analyses supported this by showing that positively selected sites, both in the host's and in the pathogen's interacting partner, modulate binding.
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Affiliation(s)
- Rachele Cagliani
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy
| | - Diego Forni
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy
| | - Giulia Filippi
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, 20126, Milan, Italy
| | - Alessandra Mozzi
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy
| | - Luca De Gioia
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, 20126, Milan, Italy
| | - Chiara Pontremoli
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy
| | - Uberto Pozzoli
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy
| | - Nereo Bresolin
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy.,Dino Ferrari Centre, Department of Physiopathology and Transplantation, University of Milan, Fondazione Ca' Granda IRCCS Ospedale Maggiore Policlinico, 20122, Milan, Italy
| | - Mario Clerici
- Department of Physiopathology and Transplantation, University of Milan, 20090, Milan, Italy.,Don C. Gnocchi Foundation ONLUS, IRCCS, 20148, Milan, Italy
| | - Manuela Sironi
- Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842, Bosisio Parini, Italy
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Protection against Experimental Cryptococcosis following Vaccination with Glucan Particles Containing Cryptococcus Alkaline Extracts. mBio 2015; 6:e01905-15. [PMID: 26695631 PMCID: PMC4701832 DOI: 10.1128/mbio.01905-15] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A vaccine capable of protecting at-risk persons against infections due to Cryptococcus neoformans and Cryptococcus gattii could reduce the substantial global burden of human cryptococcosis. Vaccine development has been hampered though, by lack of knowledge as to which antigens are immunoprotective and the need for an effective vaccine delivery system. We made alkaline extracts from mutant cryptococcal strains that lacked capsule or chitosan. The extracts were then packaged into glucan particles (GPs), which are purified Saccharomyces cerevisiae cell walls composed primarily of β-1,3-glucans. Subcutaneous vaccination with the GP-based vaccines provided significant protection against subsequent pulmonary infection with highly virulent strains of C. neoformans and C. gattii. The alkaline extract derived from the acapsular strain was analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the most abundant proteins were identified. Separation of the alkaline extract by size exclusion chromatography revealed fractions that conferred protection when loaded in GP-based vaccines. Robust Th1- and Th17-biased CD4+ T cell recall responses were observed in the lungs of vaccinated and infected mice. Thus, our preclinical studies have indicated promising cryptococcal vaccine candidates in alkaline extracts delivered in GPs. Ongoing studies are directed at identifying the individual components of the extracts that confer protection and thus would be promising candidates for a human vaccine. The encapsulated yeast Cryptococcus neoformans and its closely related sister species, Cryptococcus gattii, are major causes of morbidity and mortality, particularly in immunocompromised persons. This study reports on the preclinical development of vaccines to protect at-risk populations from cryptococcosis. Antigens were extracted from Cryptococcus by treatment with an alkaline solution. The extracted antigens were then packaged into glucan particles, which are hollow yeast cell walls composed mainly of β-glucans. The glucan particle-based vaccines elicited robust T cell immune responses and protected mice from otherwise-lethal challenge with virulent strains of C. neoformans and C. gattii. The technology used for antigen extraction and subsequent loading into the glucan particle delivery system is relatively simple and can be applied to vaccine development against other pathogens.
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Ma YJ, Hein E, Munthe-Fog L, Skjoedt MO, Bayarri-Olmos R, Romani L, Garred P. Soluble Collectin-12 (CL-12) Is a Pattern Recognition Molecule Initiating Complement Activation via the Alternative Pathway. THE JOURNAL OF IMMUNOLOGY 2015; 195:3365-73. [DOI: 10.4049/jimmunol.1500493] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 07/23/2015] [Indexed: 12/12/2022]
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Abstract
Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement and consequent phagocytosis. Several strains of GAS bind to human-specific complement inhibitors, C4b-binding protein (C4BP) and/or Factor H (FH), to curtail complement C3 (a critical opsonin) deposition. This results in diminished activation of phagocytes and clearance of GAS that may lead to the host being unable to limit the infection. Herein we describe the course of GAS infection in three human complement inhibitor transgenic (tg) mouse models that examined each inhibitor (human C4BP or FH) alone, or the two inhibitors together (C4BPxFH or 'double' tg). GAS infection with strains that bound C4BP and FH resulted in enhanced mortality in each of the three transgenic mouse models compared to infection in wild type mice. In addition, GAS manifested increased virulence in C4BPxFH mice: higher organism burdens and greater elevations of pro-inflammatory cytokines and they died earlier than single transgenic or wt controls. The effects of hu-C4BP and hu-FH were specific for GAS strains that bound these inhibitors because strains that did not bind the inhibitors showed reduced virulence in the 'double' tg mice compared to strains that did bind; mortality was also similar in wild-type and C4BPxFH mice infected by non-binding GAS. Our findings emphasize the importance of binding of complement inhibitors to GAS that results in impaired opsonization and phagocytic killing, which translates to enhanced virulence in a humanized whole animal model. This novel hu-C4BPxFH tg model may prove invaluable in studies of GAS pathogenesis and for developing vaccines and therapeutics that rely on human complement activation for efficacy.
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Levitz SM, Huang H, Ostroff GR, Specht CA. Exploiting fungal cell wall components in vaccines. Semin Immunopathol 2014; 37:199-207. [PMID: 25404118 DOI: 10.1007/s00281-014-0460-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 11/04/2014] [Indexed: 12/30/2022]
Abstract
Innate recognition of fungi leads to strong adaptive immunity. Investigators are trying to exploit this observation in vaccine development by combining antigens with evolutionarily conserved fungal cell wall carbohydrates to induce protective responses. Best studied is β-1,3-glucan, a glycan that activates complement and is recognized by dectin-1. Administration of antigens in association with β-1,3-glucan, either by direct conjugation or complexed in glucan particles, results in robust humoral and cellular immune responses. While the host has a host of mannose receptors, responses to fungal mannoproteins generally are amplified if cells are cooperatively stimulated with an additional danger signal such as a toll-like receptor agonist. Chitosan, a polycationic homopolymer of glucosamine manufactured by the deacetylation of chitin, is being studied as an adjuvant in DNA and protein-based vaccines. It appears particularly promising in mucosal vaccines. Finally, universal and organism-specific fungal vaccines have been formulated by conjugating fungal cell wall glycans to carrier proteins. A major challenge will be to advance these experimental findings so that at risk patients can be protected.
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Affiliation(s)
- Stuart M Levitz
- Department of Medicine (SML, HH, CAS) and Program in Molecular Medicine (GRO), University of Massachusetts Medical School, Worcester, MA, 01605, USA,
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Fusion protein comprising factor H domains 6 and 7 and human IgG1 Fc as an antibacterial immunotherapeutic. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:1452-9. [PMID: 25143339 DOI: 10.1128/cvi.00444-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The emergence of antimicrobial resistance among several medically important pathogens represents a serious threat to human health globally and necessitates the development of novel therapeutics. Complement forms a key arm of innate immune defenses against invading pathogens. A mechanism of complement evasion employed by many pathogens is binding of complement inhibitors, including factor H (FH), a key downregulator of the alternative pathway. Most FH-binding bacteria engage FH through regions in FH spanned by domains 6 and 7 and/or 18 through 20. We created a chimeric protein that comprised human FH domains 6 and 7 fused to human IgG1 Fc (FH6,7/HuFc) and tested its activity as an immunotherapeutic against Neisseria meningitidis, which binds FH through domains 6 and 7. FH6,7/HuFc bound to meningococci and effectively blocked FH binding to bacteria. FH6,7/HuFc enhanced human C3 and C4 deposition and facilitated complement-mediated killing in a dose-responsive manner; complement activation and killing were classical pathway dependent. To investigate in vivo efficacy, infant Wistar rats were treated intraperitoneally (IP) with different doses of FH6,7/HuFc and challenged 2 h later with serogroup C strain 4243 given IP. At 8 to 9 h after the challenge, the FH6,7/HuFc-treated rats had >100-fold fewer CFU per ml of blood than control animals pretreated with phosphate-buffered saline (PBS) or FH18-20/HuFc, which does not bind to meningococci (P < 0.0001). These data provide proof of concept of the utility of FH/Fc fusion proteins as anti-infective immunotherapeutics. Because many microbes share a common binding region(s) in FH, FH/Fc chimeric proteins may be a promising candidate for adjunctive therapy against drug-resistant pathogens.
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De Smet R, Allais L, Cuvelier CA. Recent advances in oral vaccine development: yeast-derived β-glucan particles. Hum Vaccin Immunother 2014; 10:1309-18. [PMID: 24553259 DOI: 10.4161/hv.28166] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Oral vaccination is the most challenging vaccination method due to the administration route. However, oral vaccination has socio-economic benefits and provides the possibility of stimulating both humoral and cellular immune responses at systemic and mucosal sites. Despite the advantages of oral vaccination, only a limited number of oral vaccines are currently approved for human use. During the last decade, extensive research regarding antigen-based oral vaccination methods have improved immunogenicity and induced desired immunological outcomes. Nevertheless, several factors such as the harsh gastro-intestinal environment and oral tolerance impede the clinical application of oral delivery systems. To date, human clinical trials investigating the efficacy of these systems are still lacking. This review addresses the rationale and key biological and physicochemical aspects of oral vaccine design and highlights the use of yeast-derived β-glucan microparticles as an oral vaccine delivery platform.
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Characterization and optimization of the glucan particle-based vaccine platform. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:1585-91. [PMID: 23945157 DOI: 10.1128/cvi.00463-13] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glucan particles (GPs) are hollow porous Saccharomyces cerevisiae cell walls that are treated so that they are composed primarily of β-1,3-d-glucans. Our previous studies showed that GPs can serve as an effective vaccine platform. Here, we characterize CD4(+) T-cell and antibody responses in immunized mice as a function of antigen (ovalbumin) encapsulation, antigen dose, particle numbers, time, immunization schedule, and trapping methods. Although we found that GPs served as an effective adjuvant when admixed with free antigens for IgG1 antibody production, stronger CD4(+) T-cell and IgG2c antibody responses were stimulated when antigens were encapsulated inside GPs, suggesting that the GP platform acts as both an adjuvant and a delivery system. Vigorous T-cell and antibody responses were stimulated even at submicrogram antigen doses, as long as the number of GPs was kept at 5 × 10(7) particles per immunization. One prime and one boost were sufficient to elicit robust immune responses. In addition, strong antigen-specific antibody and T-cell responses prevailed up to 20 months following the last immunization, including those of gamma interferon (IFN-γ), interleukin 17A (IL-17A), and dual IFN-γ/IL-17A-secreting CD4(+) T cells. Finally, robust immune responses were observed using generally recognized as safe (GRAS) materials (alginate and calcium, with or without chitosan) to trap antigens within GPs. Thus, these studies demonstrate that antigens encapsulated into GPs make an effective vaccine platform that combines adjuvanticity and antigen delivery to elicit strong durable immune responses at relatively low antigen doses using translationally relevant formulations.
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Lesher AM, Nilsson B, Song WC. Properdin in complement activation and tissue injury. Mol Immunol 2013; 56:191-8. [PMID: 23816404 DOI: 10.1016/j.molimm.2013.06.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 05/22/2013] [Indexed: 12/22/2022]
Abstract
The plasma protein properdin is the only known positive regulator of complement activation. Although regarded as an initiator of the alternative pathway of complement activation at the time of its discovery more than a half century ago, the role and mechanism of action of properdin in the complement cascade has undergone significant conceptual evolution since then. Despite the long history of research on properdin, however, new insight and unexpected findings on the role of properdin in complement activation, pathogen infection and host tissue injury are still being revealed by ongoing investigations. In this article, we provide a brief review on recent studies that shed new light on properdin biology, focusing on the following three topics: (1) its role as a pattern recognition molecule to direct and trigger complement activation, (2) its context-dependent requirement in complement activation on foreign and host cell surfaces, and (3) its involvement in alternative pathway complement-mediated immune disorders and considerations of properdin as a potential therapeutic target in human diseases.
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Affiliation(s)
- Allison M Lesher
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Complement component 3C3 and C3a receptor are required in chitin-dependent allergic sensitization to Aspergillus fumigatus but dispensable in chitin-induced innate allergic inflammation. mBio 2013; 4:mBio.00162-13. [PMID: 23549917 PMCID: PMC3622928 DOI: 10.1128/mbio.00162-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Levels of the anaphylatoxin C3a are increased in patients with asthma compared with those in nonasthmatics and increase further still during asthma exacerbations. However, the role of C3a during sensitization to allergen is poorly understood. Sensitization to fungal allergens, such as Aspergillus fumigatus, is a strong risk factor for the development of asthma. Exposure to chitin, a structural polysaccharide of the fungal cell wall, induces innate allergic inflammation and may promote sensitization to fungal allergens. Here, we found that coincubation of chitin with serum or intratracheal administration of chitin in mice resulted in the generation of C3a. We established a model of chitin-dependent sensitization to soluble Aspergillus antigens to test the contribution of complement to these events. C3−/− and C3aR−/− mice were protected from chitin-dependent sensitization to Aspergillus and had reduced lung eosinophilia and type 2 cytokines and serum IgE. In contrast, complement-deficient mice were not protected against chitin-induced innate allergic inflammation. In sensitized mice, plasmacytoid dendritic cells from complement-deficient animals acquired a tolerogenic profile associated with enhanced regulatory T cell responses and suppressed Th2 and Th17 responses specific for Aspergillus. Thus, chitin induces the generation of C3a in the lung, and chitin-dependent allergic sensitization to Aspergillus requires C3aR signaling, which suppresses regulatory dendritic cells and T cells and induces allergy-promoting T cells. Asthma is one of the fastest growing chronic illnesses worldwide. Chitin, a ubiquitous polymer in our environment and a key component in the cell wall of fungal spores and the exoskeletons of insects, parasites, and crustaceans, triggers innate allergic inflammation. However, there is little understanding of how chitin is initially recognized by mammals and how early recognition of chitin affects sensitization to environmental allergens and development of allergic asthma. The complement system is evolutionarily one of the oldest facets of the early or innate warning systems in mammals. We studied whether and how complement components influence the recognition of chitin and shape the downstream sensitization toward fungal allergens. We show here that complement recognition of chitin plays a critical role in shaping the behavior of dendritic cells, which in turn regulate the function of T cells that mediate allergic responses to fungi.
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Harboe M, Garred P, Lindstad JK, Pharo A, Müller F, Stahl GL, Lambris JD, Mollnes TE. The role of properdin in zymosan- and Escherichia coli-induced complement activation. THE JOURNAL OF IMMUNOLOGY 2012; 189:2606-13. [PMID: 22851705 DOI: 10.4049/jimmunol.1200269] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Properdin is well known as an enhancer of the alternative complement amplification loop when C3 is activated, whereas its role as a recognition molecule of exogenous pathogen-associated molecular patterns and initiator of complement activation is less understood. We therefore studied the role of properdin in activation of complement in normal human serum by zymosan and various Escherichia coli strains. In ELISA, microtiter plates coated with zymosan induced efficient complement activation with deposition of C4b and terminal complement complex on the solid phase. Virtually no deposition of C4b or terminal complement complex was observed with mannose-binding lectin (MBL)-deficient serum. Reconstitution with purified MBL showed distinct activation in both readouts. In ELISA, normal human serum-induced deposition of properdin by zymosan was abolished by the C3-inhibiting peptide compstatin. Flow cytometry was used to further explore whether properdin acts as an initial recognition molecule reacting directly with zymosan and three E. coli strains. Experiments reported by other authors were made with EGTA Mg²⁺ buffer, permitting autoactivation of C3. We found inhibition by compstatin on these substrates, indicating that properdin deposition depended on initial C3b deposition followed by properdin in a second step. Properdin released from human polymorphonuclear cells stimulated with PMA did not bind to zymosan or E. coli, but when incubated in properdin-depleted serum this form of properdin bound efficiently to both substrates in a strictly C3-dependent manner, as the binding was abolished by compstatin. Collectively, these data indicate that properdin in serum as well as polymorphonuclear-released properdin is unable to bind and initiate direct alternative pathway activation on these substrates.
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Affiliation(s)
- Morten Harboe
- Institute of Immunology, University of Oslo and Oslo University Hospital, Rikshospitalet, NO-0027 Oslo, Norway
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Jawhara S, Pluskota E, Verbovetskiy D, Skomorovska-Prokvolit O, Plow EF, Soloviev DA. Integrin αXβ₂ is a leukocyte receptor for Candida albicans and is essential for protection against fungal infections. THE JOURNAL OF IMMUNOLOGY 2012; 189:2468-77. [PMID: 22844116 DOI: 10.4049/jimmunol.1200524] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The opportunistic fungus Candida albicans is one of the leading causes of infections in immunocompromised patients, and innate immunity provides a principal mechanism for protection from the pathogen. In the present work, the role of integrin α(X)β₂ in the pathogenesis of fungal infection was assessed. Both purified α(X)β₂ and α(X)β₂-expressing human epithelial kidney 293 cells recognized and bound to the fungal hyphae of SC5314 strain of C. albicans but not to the yeast form or to hyphae of a strain deficient in the fungal mannoprotein, Pra1. The binding of the integrin to the fungus was inhibited by β-glucans but not by mannans, implicating a lectin-like activity in recognition but distinct in specificity from that of α(M)β₂. Mice deficient in α(X)β₂ were more prone to systemic infection with the LD₅₀ fungal inoculum decreasing 3-fold in α(X)β₂-deficient mice compared with wild-type mice. After challenging i.v. with 1.5 × 10⁴ cell/g, 60% of control C57BL/6 mice died within 14 d compared with 100% mortality of α(X)β₂-deficient mice within 9 d. Organs taken from α(X)β₂-deficient mice 16 h postinfection revealed a 10-fold increase in fungal invasion into the brain and a 2-fold increase into the liver. These data indicate that α(X)β₂ is important for protection against systemic C. albicans infections and macrophage subsets in the liver, Kupffer cells, and in the brain, microglial cells use α(X)β₂ to control fungal invasion.
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Affiliation(s)
- Samir Jawhara
- Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Cleveland Clinic, Cleveland, OH 44195, USA
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Noss I, Doekes G, Thorne PS, Heederik DJJ, Wouters IM. Comparison of the potency of a variety of β-glucans to induce cytokine production in human whole blood. Innate Immun 2012; 19:10-9. [PMID: 22653750 DOI: 10.1177/1753425912447129] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
β-Glucans are components of fungal cell walls and potent stimulants of innate immunity. The majority of research on biological activities of glucans has focused on β-(1→3)-glucans, which have been implicated in relation to fungal exposure-associated respiratory symptoms and as important stimulatory agents in anti-fungal immune responses. Fungi-and bacteria and plants-produce a wide variety of glucans with vast differences in the proportion and arrangement of their β-(1→3)-, -(1→4)- and -(1→6)-glycosidic linkages. Thus far, the pro-inflammatory potential of different β-glucans has not been studied within the same experimental model. Therefore, we compared the potency of 13 different glucan preparations to induce in vitro production of IL-1β, IL-6, IL-8 and TNF-α in human, whole blood cultures. The strongest inducers of all cytokines were pustulan [β-(1→6)-glucan], lichenan [β-(1→3)-(1→4)-glucan], xyloglucan [β-(1→4)-glucan] and pullulan [α-(1→4)-(1→6)-glucan]. Moderate-to-strong cytokine production was observed for curdlan [β-(1→3)-glucan], baker's yeast glucan [β-(1→3)-(1→6)-glucan] and barley glucan [β-(1→3)-(1→4)-glucan], while all other glucan preparations induced very low, or no, detectable levels of cytokines. We therefore conclude that innate immunity reactions are not exclusively induced by β-(1→3)-glucans, but also by β-(1→6)- and β-(1→4)-structures. Thus, not only β-(1→3)-glucan, but also other β-glucans and particularly β-(1→6)-glucans should be considered in future research.
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Affiliation(s)
- Ilka Noss
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
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Huang H, Ostroff GR, Lee CK, Agarwal S, Ram S, Rice PA, Specht CA, Levitz SM. Relative contributions of dectin-1 and complement to immune responses to particulate β-glucans. THE JOURNAL OF IMMUNOLOGY 2012; 189:312-7. [PMID: 22649195 DOI: 10.4049/jimmunol.1200603] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glucan particles (GPs) are Saccharomyces cerevisiae cell walls chemically extracted so they are composed primarily of particulate β-1,3-D-glucans. GPs are recognized by Dectin-1 and are potent complement activators. Mice immunized with Ag-loaded GPs develop robust Ab and CD4(+) T cell responses. In this study, we examined the relative contributions of Dectin-1 and complement to GP phagocytosis and Ag-specific responses to immunization with OVA encapsulated in GPs. The in vitro phagocytosis of GPs by bone marrow-derived dendritic cells was facilitated by heat-labile serum component(s) independently of Dectin-1. This enhanced uptake was not seen with serum from complement component 3 knockout (C3(-/-)) mice and was also inhibited by blocking Abs directed against complement receptor 3. After i.p. injection, percent phagocytosis of GPs by peritoneal macrophages was comparable in wild-type and Dectin-1(-/-) mice and was not inhibited by the soluble β-glucan antagonist laminarin. In contrast, a much lower percentage of peritoneal macrophages from C3(-/-) mice phagocytosed GPs, and this percentage was further reduced in the presence of laminarin. Subcutaneous immunization of wild-type, Dectin-1(-/-), and C3(-/-) mice with GP-OVA resulted in similar Ag-specific IgG(1) and IgG(2c) type Ab and CD4(+) T cell lymphoproliferative responses. Moreover, while CD4(+) Th1 and Th2 responses measured by ELISPOT assay were similar in the three mouse strains, Th17 responses were reduced in C3(-/-) mice. Thus, although Dectin-1 is necessary for optimal phagocytosis of GPs in the absence of complement, complement dominates when both an intact complement system and Dectin-1 are present. In addition, Th-skewing after GP-based immunization was altered in C3(-/-) mice.
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Affiliation(s)
- Haibin Huang
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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Enhanced bacteremia in human factor H transgenic rats infected by Neisseria meningitidis. Infect Immun 2011; 80:643-50. [PMID: 22104107 DOI: 10.1128/iai.05604-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neisseria meningitidis binds the complement downregulating protein, factor H (fH), which enables the organism to evade host defenses. Two fH ligands, fHbp and NspA, are known to bind specifically to human fH. We developed a human fH transgenic infant rat model to investigate the effect of human fH on meningococcal bacteremia. At 18 h after intraperitoneal challenge with 560 CFU of group B strain H44/76, all 19 human fH-positive rats had positive blood cultures compared to 0 of 7 human fH-negative control littermates (P < 0.0001). Human fH-positive infant rats also developed bacteremia after challenge with isogenic mutants of H44/76 in which genes encoding fHbp and NspA (ΔfHbp ΔNspA mutant) or the lipooligosaccharide sialyltransferase (Δlst mutant) had been inactivated. A fully encapsulated ΔfHbp ΔNspA Δlst mutant unable to sialylate lipooligosaccharide or bind human fH via the known fH ligands did not cause bacteremia, which argued against global susceptibility to bacteremia resulting from random integration of the transgene into the rat genome. In vitro, the wild-type and ΔfHbp ΔNspA mutant strains were killed by as little as 20% wild-type infant rat serum. The addition of 3 μg of human fH/ml permitted survival of the wild-type strain in up to 60% infant rat serum, whereas ≥33 μg of human fH/ml was required to rescue the ΔfHbp ΔNspA mutant. The ability of meningococci lacking expression of fHbp and NspA to cause invasive disease in human fH transgenic rats and to survive in wild-type infant rat serum supplemented with human fH indicates an additional human fH-dependent mechanism of evasion of innate immunity.
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Combined roles of human IgG subclass, alternative complement pathway activation, and epitope density in the bactericidal activity of antibodies to meningococcal factor h binding protein. Infect Immun 2011; 80:187-94. [PMID: 22064712 DOI: 10.1128/iai.05956-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density.
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