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Pampalone M, Vitale G, Gruttadauria S, Amico G, Iannolo G, Douradinha B, Mularoni A, Conaldi PG, Pietrosi G. Human Amnion-Derived Mesenchymal Stromal Cells: A New Potential Treatment for Carbapenem-Resistant Enterobacterales in Decompensated Cirrhosis. Int J Mol Sci 2022; 23:ijms23020857. [PMID: 35055040 PMCID: PMC8775978 DOI: 10.3390/ijms23020857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/05/2022] [Accepted: 01/11/2022] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Spontaneous bacterial peritonitis (SBP) is a severe and often fatal infection in patients with decompensated cirrhosis and ascites. The only cure for SBP is antibiotic therapy, but the emerging problem of bacterial resistance requires novel therapeutic strategies. Human amniotic mesenchymal stromal cells (hA-MSCs) possess immunomodulatory and anti-inflammatory properties that can be harnessed as a therapy in such a context. METHODS An in vitro applications of hA-MSCs in ascitic fluid (AF) of cirrhotic patients, subsequently infected with carbapenem-resistant Enterobacterales, was performed. We evaluated the effects of hA-MSCs on bacterial load, innate immunity factors, and macrophage phenotypic expression. RESULTS hA-MSCs added to AF significantly reduce the proliferation of both bacterial strains at 24 h and diversely affect M1 and M2 polarization, C3a complement protein, and ficolin 3 concentrations during the course of infection, in a bacterial strain-dependent fashion. CONCLUSION This study shows the potential usefulness of hA-MSC in treating ascites infected with carbapenem-resistant bacteria and lays the foundation to further investigate antibacterial and anti-inflammatory roles of hA-MSC in in vivo models.
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Affiliation(s)
- Mariangela Pampalone
- Ri.MED Foundation, 90133 Palermo, Italy; (G.V.); (G.A.); (B.D.)
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS-ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), 90127 Palermo, Italy; (G.I.); (P.G.C.)
- Correspondence:
| | - Giampiero Vitale
- Ri.MED Foundation, 90133 Palermo, Italy; (G.V.); (G.A.); (B.D.)
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS-ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), 90127 Palermo, Italy; (G.I.); (P.G.C.)
| | - Salvatore Gruttadauria
- Department for the Treatment and Study of Abdominal Disease and Abdominal Transplantation, IRCCS-ISMETT, UPMC, 90127 Palermo, Italy; (S.G.); (G.P.)
- Department of General Surgery and Medical-Surgical Specialties, University of Catania, 95124 Catania, Italy
| | - Giandomenico Amico
- Ri.MED Foundation, 90133 Palermo, Italy; (G.V.); (G.A.); (B.D.)
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS-ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), 90127 Palermo, Italy; (G.I.); (P.G.C.)
| | - Gioacchin Iannolo
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS-ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), 90127 Palermo, Italy; (G.I.); (P.G.C.)
| | - Bruno Douradinha
- Ri.MED Foundation, 90133 Palermo, Italy; (G.V.); (G.A.); (B.D.)
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS-ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), 90127 Palermo, Italy; (G.I.); (P.G.C.)
| | | | - Pier Giulio Conaldi
- Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS-ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), 90127 Palermo, Italy; (G.I.); (P.G.C.)
| | - Giada Pietrosi
- Department for the Treatment and Study of Abdominal Disease and Abdominal Transplantation, IRCCS-ISMETT, UPMC, 90127 Palermo, Italy; (S.G.); (G.P.)
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Takai J, Shimada T, Nakamura T, Engel JD, Moriguchi T. Gata2 heterozygous mutant mice exhibit reduced inflammatory responses and impaired bacterial clearance. iScience 2021; 24:102836. [PMID: 34471858 PMCID: PMC8390858 DOI: 10.1016/j.isci.2021.102836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 05/17/2021] [Accepted: 07/08/2021] [Indexed: 01/18/2023] Open
Abstract
Infectious diseases continually pose global medical challenges. The transcription factor GATA2 establishes gene networks and defines cellular identity in hematopoietic stem/progenitor cells and in progeny committed to specific lineages. GATA2-haploinsufficient patients exhibit a spectrum of immunodeficiencies associated with bacterial, viral, and fungal infections. Despite accumulating clinical knowledge of the consequences of GATA2 haploinsufficiency in humans, it is unclear how GATA2 haploinsufficiency compromises host anti-infectious defenses. To address this issue, we examined Gata2-heterozygous mutant (G2 Het) mice as a model for human GATA2 haploinsufficiency. In vivo inflammation imaging and cytokine multiplex analysis demonstrated that G2 Het mice had attenuated inflammatory responses with reduced levels of inflammatory cytokines, particularly IFN-γ, IL-12p40, and IL-17A, during lipopolysaccharide-induced acute inflammation. Consequently, bacterial clearance was significantly impaired in G2 Het mice after cecal ligation and puncture-induced polymicrobial peritonitis. These results provide direct molecular insights into GATA2-directed host defenses and the pathogenic mechanisms underlying observed immunodeficiencies in GATA2-haploinsufficient patients.
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Affiliation(s)
- Jun Takai
- Division of Medical Biochemistry, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - Takashi Shimada
- Division of Medical Biochemistry, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - Tadaho Nakamura
- Division of Pharmacology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - James Douglas Engel
- Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Takashi Moriguchi
- Division of Medical Biochemistry, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
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Lasola JJM, Kamdem H, McDaniel MW, Pearson RM. Biomaterial-Driven Immunomodulation: Cell Biology-Based Strategies to Mitigate Severe Inflammation and Sepsis. Front Immunol 2020; 11:1726. [PMID: 32849612 PMCID: PMC7418829 DOI: 10.3389/fimmu.2020.01726] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 06/29/2020] [Indexed: 12/11/2022] Open
Abstract
Inflammation is an essential component of a wide variety of disease processes and oftentimes can increase the deleterious effects of a disease. Finding ways to modulate this essential immune process is the basis for many therapeutics under development and is a burgeoning area of research for both basic and translational immunology. In addition to developing therapeutics for cellular and molecular targets, the use of biomaterials to modify innate and adaptive immune responses is an area that has recently sparked significant interest. In particular, immunomodulatory activity can be engineered into biomaterials to elicit heightened or dampened immune responses for use in vaccines, immune tolerance, or anti-inflammatory applications. Importantly, the inherent physicochemical properties of the biomaterials play a significant role in determining the observed effects. Properties including composition, molecular weight, size, surface charge, and others affect interactions with immune cells (i.e., nano-bio interactions) and allow for differential biological responses such as activation or inhibition of inflammatory signaling pathways, surface molecule expression, and antigen presentation to be encoded. Numerous opportunities to open new avenues of research to understand the ways in which immune cells interact with and integrate information from their environment may provide critical solutions needed to treat a variety of disorders and diseases where immune dysregulation is a key inciting event. However, to elicit predictable immune responses there is a great need for a thorough understanding of how the biomaterial properties can be tuned to harness a designed immunological outcome. This review aims to systematically describe the biological effects of nanoparticle properties-separate from additional small molecule or biologic delivery-on modulating innate immune cell responses in the context of severe inflammation and sepsis. We propose that nanoparticles represent a potential polypharmacological strategy to simultaneously modify multiple aspects of dysregulated immune responses where single target therapies have fallen short for these applications. This review intends to serve as a resource for immunology labs and other associated fields that would like to apply the growing field of rationally designed biomaterials into their work.
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Affiliation(s)
- Jackline Joy Martín Lasola
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Henry Kamdem
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Michael W. McDaniel
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Ryan M. Pearson
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, United States
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Wu X, Yao D, Bao L, Liu D, Xu X, An Y, Zhang X, Cao B. Ficolin A derived from local macrophages and neutrophils protects against lipopolysaccharide-induced acute lung injury by activating complement. Immunol Cell Biol 2020; 98:595-606. [PMID: 32339310 DOI: 10.1111/imcb.12344] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 12/12/2022]
Abstract
Ficolins are important and widely distributed pattern recognition molecules that can induce lectin complement pathway activation and initiate the innate immune response. Although ficolins can bind lipopolysaccharide (LPS) in vitro, the sources, dynamic changes and roles of local ficolins in LPS-induced pulmonary inflammation and injury remain poorly understood. In this study, we established a ficolin knockout mouse model by clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) technology, and used flow cytometry and hematoxylin and eosin staining to study the expressions and roles of local ficolins in LPS-induced pulmonary inflammation and injury. Our results show that besides ficolin B (FcnB), ficolin A (FcnA) is also expressed in leukocytes from the bone marrow, peripheral blood, lung and spleen. Further analyses showed that macrophages and neutrophils are the main sources of FcnA and FcnB, and T and B cells also express a small amount of FcnB. The intranasal administration of LPS induced local pulmonary inflammation with the increased recruitment of macrophages and neutrophils. LPS stimulation induced increased expression of FcnA and FcnB in neutrophils at the acute stage and in macrophages at the late stage. The severity of the lung injury and local inflammation of Fcna-/- mice was increased by the induction of extracellular complement activation. The recovery of LPS-induced local lung inflammation and injury was delayed in Fcnb-/- mice. Hence, these findings suggested that the local macrophage- and neutrophil-derived FcnA protects against LPS-induced acute lung injury by mediating extracellular complement activation.
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Affiliation(s)
- Xu Wu
- National Clinical Research Center for Respiratory Diseases, Clinical Center for Pulmonary Infections, China-Japan Friendship Hospital, Capital Medical University, Beijing, 100029, China
| | - Duoduo Yao
- Department of Immunology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Linlin Bao
- NHC Key Laboratory of Human Disease Comparative Medicine , Beijing Key Laboratory for Animal Models of Emerging and Remerging Infectious Diseases, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Comparative Medicine Center, Peking Union Medical College, Beijing, 100021, China
| | - Di Liu
- Core Facility for Protein Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaoxue Xu
- Department of Core Facility Center, Capital Medical University, Beijing, 100069, China
| | - Yunqing An
- Department of Immunology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Xulong Zhang
- Department of Immunology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Bin Cao
- National Clinical Research Center for Respiratory Diseases, Clinical Center for Pulmonary Infections, China-Japan Friendship Hospital, Capital Medical University, Beijing, 100029, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100006, China
- Tsinghua University-Peking University Joint Center for Life Sciences, Beijing, 100084, China
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Liu H, Feye KM, Nguyen YT, Rakhshandeh A, Loving CL, Dekkers JCM, Gabler NK, Tuggle CK. Acute systemic inflammatory response to lipopolysaccharide stimulation in pigs divergently selected for residual feed intake. BMC Genomics 2019; 20:728. [PMID: 31610780 PMCID: PMC6792331 DOI: 10.1186/s12864-019-6127-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 09/20/2019] [Indexed: 12/23/2022] Open
Abstract
Background It is unclear whether improving feed efficiency by selection for low residual feed intake (RFI) compromises pigs’ immunocompetence. Here, we aimed at investigating whether pig lines divergently selected for RFI had different inflammatory responses to lipopolysaccharide (LPS) exposure, regarding to clinical presentations and transcriptomic changes in peripheral blood cells. Results LPS injection induced acute systemic inflammation in both the low-RFI and high-RFI line (n = 8 per line). At 4 h post injection (hpi), the low-RFI line had a significantly lower (p = 0.0075) mean rectal temperature compared to the high-RFI line. However, no significant differences in complete blood count or levels of several plasma cytokines were detected between the two lines. Profiling blood transcriptomes at 0, 2, 6, and 24 hpi by RNA-sequencing revealed that LPS induced dramatic transcriptional changes, with 6296 genes differentially expressed at at least one time point post injection relative to baseline in at least one line (n = 4 per line) (|log2(fold change)| ≥ log2(1.2); q < 0.05). Furthermore, applying the same cutoffs, we detected 334 genes differentially expressed between the two lines at at least one time point, including 33 genes differentially expressed between the two lines at baseline. But no significant line-by-time interaction effects were detected. Genes involved in protein translation, defense response, immune response, and signaling were enriched in different co-expression clusters of genes responsive to LPS stimulation. The two lines were largely similar in their peripheral blood transcriptomic responses to LPS stimulation at the pathway level, although the low-RFI line had a slightly lower level of inflammatory response than the high-RFI line from 2 to 6 hpi and a slightly higher level of inflammatory response than the high-RFI line at 24 hpi. Conclusions The pig lines divergently selected for RFI had a largely similar response to LPS stimulation. However, the low-RFI line had a relatively lower-level, but longer-lasting, inflammatory response compared to the high-RFI line. Our results suggest selection for feed efficient pigs does not significantly compromise a pig’s acute systemic inflammatory response to LPS, although slight differences in intensity and duration may occur.
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Affiliation(s)
- Haibo Liu
- Department of Animal Science, Iowa State University, 2258 Kildee Hall, Ames, IA, 50011, USA
| | - Kristina M Feye
- Interdepartmental Immunobiology, Department of Animal Science, Iowa State University, 2258 Kildee Hall, Ames, IA, 50011, USA
| | - Yet T Nguyen
- Department of Mathematics and Statistics, Old Dominion University, Norfolk, VA, 23529, USA
| | - Anoosh Rakhshandeh
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, 79409, USA
| | - Crystal L Loving
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, ARS, USDA, 1920 Dayton Ave, Ames, IA, 50010, USA
| | - Jack C M Dekkers
- Department of Animal Science, Iowa State University, 239 Kildee Hall, Ames, IA, 50011, USA
| | - Nicholas K Gabler
- Department of Animal Science, Iowa State University, 239 Kildee Hall, Ames, IA, 50011, USA
| | - Christopher K Tuggle
- Department of Animal Science, Iowa State University, 2255 Kildee Hall, Ames, IA, 50011, USA.
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Jarlhelt I, Genster N, Kirketerp-Møller N, Skjoedt MO, Garred P. The ficolin response to LPS challenge in mice. Mol Immunol 2019; 108:121-127. [PMID: 30818229 DOI: 10.1016/j.molimm.2019.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/07/2019] [Accepted: 02/15/2019] [Indexed: 12/30/2022]
Abstract
The ficolins belong to an important family of pattern recognition molecules, which contributes to complement activation via the lectin pathway. How the ficolins respond to inflammatory stimuli remains only partly understood. In the present study, we investigated the ficolin A and ficolin B expression and protein distribution patterns in a mouse model of LPS-induced inflammation. The time- and tissue-specific expression of ficolin A and B was determined by real time PCR. Furthermore, ficolin protein levels in serum and bone marrow extracts from LPS challenged mice were determined by novel in-house developed sandwich ELISAs. Ficolin A was mainly expressed in liver and spleen. However, our data also suggested that ficolin A is expressed in bone marrow, which is the main site of ficolin B expression. The level of ficolin A and B expression was increased after stimulation with LPS in the investigated tissues. This was followed by a downregulation of expression, causing mRNA levels to return to baseline 24 h post LPS challenge. Protein levels appeared to follow the same pattern as the expression profiles, with an exception of ficolin B levels in serum, which kept increasing for 24 h. Ficolin A was likewise significantly increased in bronchoalveolar lavage fluid from mice infected with the fungi A. fumigatus, pointing towards a similar effect of the ficolins in non-sterile mouse models of inflammation. The results demonstrate that LPS-induced inflammation can induce a significant ficolin response, suggesting that the murine ficolins are acute phase reactants with increase in both mRNA expression and protein levels during systemic inflammation.
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Affiliation(s)
- Ida Jarlhelt
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ninette Genster
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nikolaj Kirketerp-Møller
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel-Ole Skjoedt
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, 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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Bidula S, Sexton DW, Schelenz S. Ficolins and the Recognition of Pathogenic Microorganisms: An Overview of the Innate Immune Response and Contribution of Single Nucleotide Polymorphisms. J Immunol Res 2019; 2019:3205072. [PMID: 30868077 PMCID: PMC6379837 DOI: 10.1155/2019/3205072] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 11/29/2018] [Accepted: 12/24/2018] [Indexed: 12/19/2022] Open
Abstract
Ficolins are innate pattern recognition receptors (PRR) and play integral roles within the innate immune response to numerous pathogens throughout the circulation, as well as within organs. Pathogens are primarily removed by direct opsonisation following the recognition of cell surface carbohydrates and other immunostimulatory molecules or via the activation of the lectin complement pathway, which results in the deposition of C3b and the recruitment of phagocytes. In recent years, there have been a number of studies implicating ficolins in the recognition and removal of numerous bacterial, viral, fungal, and parasitic pathogens. Moreover, there has been expanding evidence highlighting that mutations within these key immune proteins, or the possession of particular haplotypes, enhance susceptibility to colonization by pathogens and dysfunctional immune responses. This review will therefore encompass previous knowledge on the role of ficolins in the recognition of bacterial and viral pathogens, while acknowledging the recent advances in the immune response to fungal and parasitic infections. Additionally, we will explore the various genetic susceptibility factors that predispose individuals to infection.
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Affiliation(s)
- Stefan Bidula
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Darren W. Sexton
- School of Pharmacy and Biomolecular Science, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Silke Schelenz
- Department of Microbiology, Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK
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The Pneumococcal Surface Proteins PspA and PspC Sequester Host C4-Binding Protein To Inactivate Complement C4b on the Bacterial Surface. Infect Immun 2018; 87:IAI.00742-18. [PMID: 30323030 DOI: 10.1128/iai.00742-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 10/11/2018] [Indexed: 12/15/2022] Open
Abstract
Complement is a critical component of antimicrobial immunity. Various complement regulatory proteins prevent host cells from being attacked. Many pathogens have acquired the ability to sequester complement regulators from host plasma to evade complement attack. We describe here how Streptococcus pneumoniae adopts a strategy to prevent the formation of the C3 convertase C4bC2a by the rapid conversion of surface bound C4b and iC4b into C4dg, which remains bound to the bacterial surface but no longer forms a convertase complex. Noncapsular virulence factors on the pneumococcus are thought to facilitate this process by sequestering C4b-binding protein (C4BP) from host plasma. When S. pneumoniae D39 was opsonized with human serum, the larger C4 activation products C4b and iC4b were undetectable, but the bacteria were liberally decorated with C4dg and C4BP. With targeted deletions of either PspA or PspC, C4BP deposition was markedly reduced, and there was a corresponding reduction in C4dg and an increase in the deposition of C4b and iC4b. The effect was greatest when PspA and PspC were both knocked out. Infection experiments in mice indicated that the deletion of PspA and/or PspC resulted in the loss of bacterial pathogenicity. Recombinant PspA and PspC both bound serum C4BP, and both led to increased C4b and reduced C4dg deposition on S. pneumoniae D39. We conclude that PspA and PspC help the pneumococcus to evade complement attack by binding C4BP and so inactivating C4b.
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