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Boero E, Gorham RD, Francis EA, Brand J, Teng LH, Doorduijn DJ, Ruyken M, Muts RM, Lehmann C, Verschoor A, van Kessel KPM, Heinrich V, Rooijakkers SHM. Purified complement C3b triggers phagocytosis and activation of human neutrophils via complement receptor 1. Sci Rep 2023; 13:274. [PMID: 36609665 PMCID: PMC9822988 DOI: 10.1038/s41598-022-27279-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 12/29/2022] [Indexed: 01/07/2023] Open
Abstract
The complement system provides vital immune protection against infectious agents by labeling them with complement fragments that enhance phagocytosis by immune cells. Many details of complement-mediated phagocytosis remain elusive, partly because it is difficult to study the role of individual complement proteins on target surfaces. Here, we employ serum-free methods to couple purified complement C3b onto E. coli bacteria and beads and then expose human neutrophils to these C3b-coated targets. We examine the neutrophil response using a combination of flow cytometry, confocal microscopy, luminometry, single-live-cell/single-target manipulation, and dynamic analysis of neutrophil spreading on opsonin-coated surfaces. We show that purified C3b can potently trigger phagocytosis and killing of bacterial cells via Complement receptor 1. Comparison of neutrophil phagocytosis of C3b- versus antibody-coated beads with single-bead/single-target analysis exposes a similar cell morphology during engulfment. However, bulk phagocytosis assays of C3b-beads combined with DNA-based quenching reveal that these are poorly internalized compared to their IgG1 counterparts. Similarly, neutrophils spread slower on C3b-coated compared to IgG-coated surfaces. These observations support the requirement of multiple stimulations for efficient C3b-mediated uptake. Together, our results establish the existence of a direct pathway of phagocytic uptake of C3b-coated targets and present methodologies to study this process.
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Affiliation(s)
- Elena Boero
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands ,grid.425088.3GSK, 53100 Siena, Italy
| | - Ronald D. Gorham
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands ,grid.417555.70000 0000 8814 392XSanofi, Waltham, MA 02451 USA
| | - Emmet A. Francis
- grid.27860.3b0000 0004 1936 9684Department of Biomedical Engineering, University of California Davis, Davis, CA 95616 USA
| | - Jonathan Brand
- grid.27860.3b0000 0004 1936 9684Department of Biomedical Engineering, University of California Davis, Davis, CA 95616 USA
| | - Lay Heng Teng
- grid.27860.3b0000 0004 1936 9684Department of Biomedical Engineering, University of California Davis, Davis, CA 95616 USA
| | - Dennis J. Doorduijn
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Maartje Ruyken
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Remy M. Muts
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Christian Lehmann
- grid.5330.50000 0001 2107 3311Laboratory of Dendritic Cell Biology, Department of Dermatology, University Hospital of Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Admar Verschoor
- grid.15474.330000 0004 0477 2438Department of Otorhinolaryngology, Technische Universität München and Klinikum Rechts der Isar, 81675 Munich, Germany
| | - Kok P. M. van Kessel
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Volkmar Heinrich
- grid.27860.3b0000 0004 1936 9684Department of Biomedical Engineering, University of California Davis, Davis, CA 95616 USA
| | - Suzan H. M. Rooijakkers
- grid.5477.10000000120346234Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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Nuutila J, Hohenthal U, Oksi J, Jalava-Karvinen P. Rapid detection of bacterial infection using a novel single-tube, four-colour flow cytometric method: Comparison with PCT and CRP. EBioMedicine 2021; 74:103724. [PMID: 34844193 PMCID: PMC8633870 DOI: 10.1016/j.ebiom.2021.103724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/04/2021] [Accepted: 11/16/2021] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND A key factor behind the unnecessary use of antibiotics is the lack of rapid and accurate diagnostic tests. In this study, we developed a novel and fast flow cytometric single-tube method to detect bacterial infections within 30 minutes. METHODS Quantitative flow cytometric four-colour analysis of host biomarkers CD35, CD64, CD329, and MHC class I expression on neutrophils and lymphocytes was performed on samples taken from 841 febrile patients with suspected infection. Obtained data was incorporated into the four-colour bacterial infection (FCBI)-index, using the developed bacterial infection algorithm. FINDINGS In distinguishing between microbiologically confirmed bacterial (n = 193) and viral (n = 291) infections, the FCBI-index method was superior to serum C-reactive protein (CRP) and procalcitonin (PCT). In 269 confirmed viral respiratory tract infections, 43% (95% CI: 37-49%) of the patients had an increased FCBI-index, suggesting probable bacterial coinfection. INTERPRETATION The proposed FCBI-index test might be a potent additional tool when assessing appropriateness of empiric antibiotic treatment. FUNDING This study has been financially supported by Turku University Hospital (Turku, Finland) and The Finnish Medical Foundation.
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Affiliation(s)
- Jari Nuutila
- Department of Life Technologies, University of Turku, Turku, Finland.
| | - Ulla Hohenthal
- Turku University Hospital, Department of Medicine, Turku, Finland; Faculty of Medicine, University of Turku, Turku, Finland
| | - Jarmo Oksi
- Turku University Hospital, Department of Medicine, Turku, Finland; Faculty of Medicine, University of Turku, Turku, Finland
| | - Päivi Jalava-Karvinen
- Turku University Hospital, Department of Medicine, Turku, Finland; Faculty of Medicine, University of Turku, Turku, Finland
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Janssen WJ, Stefanski AL, Bochner BS, Evans CM. Control of lung defence by mucins and macrophages: ancient defence mechanisms with modern functions. Eur Respir J 2016; 48:1201-1214. [PMID: 27587549 DOI: 10.1183/13993003.00120-2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 06/12/2016] [Indexed: 12/14/2022]
Abstract
Owing to the need to balance the requirement for efficient respiration in the face of tremendous levels of exposure to endogenous and environmental challenges, it is crucial for the lungs to maintain a sustainable defence that minimises damage caused by this exposure and the detrimental effects of inflammation to delicate gas exchange surfaces. Accordingly, epithelial and macrophage defences constitute essential first and second lines of protection that prevent the accumulation of potentially harmful agents in the lungs, and under homeostatic conditions do so effectively without inducing inflammation. Though epithelial and macrophage-mediated defences are seemingly distinct, recent data show that they are linked through their shared reliance on airway mucins, in particular the polymeric mucin MUC5B. This review highlights our understanding of novel mechanisms that link mucus and macrophage defences. We discuss the roles of phagocytosis and the effects of factors contained within mucus on phagocytosis, as well as newly identified roles for mucin glycoproteins in the direct regulation of leukocyte functions. The emergence of this nascent field of glycoimmunobiology sets forth a new paradigm for considering how homeostasis is maintained under healthy conditions and how it is restored in disease.
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Affiliation(s)
- William J Janssen
- Dept of Medicine, National Jewish Health, Denver, CO, USA Dept of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | | | - Bruce S Bochner
- Dept of Medicine, Division of Allergy-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Christopher M Evans
- Dept of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
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Linnartz-Gerlach B, Schuy C, Shahraz A, Tenner AJ, Neumann H. Sialylation of neurites inhibits complement-mediated macrophage removal in a human macrophage-neuron Co-Culture System. Glia 2015; 64:35-47. [PMID: 26257016 DOI: 10.1002/glia.22901] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 07/22/2015] [Accepted: 07/23/2015] [Indexed: 01/08/2023]
Abstract
The complement system has been implicated in the removal of dysfunctional synapses and neurites during development and in disease processes in the mouse, but it is unclear how far the mouse data can be transferred to humans. Here, we co-cultured macrophages derived from human THP1 monocytes and neurons derived from human induced pluripotent stem cells, to study the role of the complement system in a human model. Components of the complement system were expressed by the human macrophages and human neuronal culture, while receptors of the complement cascade were expressed by human macrophages as shown via gene transcript analysis and flow cytometry. We mimicked pathological conditions leading to an altered glycocalyx by treatment of human neurons with sialidases. Desialylated human neurites were opsonized by the complement component C1q. Furthermore, human neurites with an intact sialic acid cap remained untouched, while desialylated human neurites were removed and ingested by human macrophages. While blockage of the complement receptor 1 (CD35) had no effect, blockage of CD11b as part of the complement receptor 3 (CR3) reversed the effect on macrophage phagocytosis of desialylated human neurites. Data demonstrate that in the human system sialylation of the neuronal glycocalyx serves as an inhibitory flag for complement binding and CR3-mediated phagocytosis by macrophages.
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Affiliation(s)
- Bettina Linnartz-Gerlach
- Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Bonn, 53127, Germany
| | - Christine Schuy
- Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Bonn, 53127, Germany
| | - Anahita Shahraz
- Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Bonn, 53127, Germany
| | - Andrea J Tenner
- Department of Molecular Biology and Biochemistry, Institute for Immunology, University of California, Irvine, California, 92697, USA
| | - Harald Neumann
- Neural Regeneration Group, Institute of Reconstructive Neurobiology, University Hospital Bonn, University of Bonn, Bonn, 53127, Germany
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Nuutila J, Jalava-Karvinen P, Hohenthal U, Kotilainen P, Pelliniemi TT, Nikoskelainen J, Lilius EM. Bacterial infection (BI)-INDEX: an improved and simplified rapid flow cytometric bacterial infection marker. Diagn Microbiol Infect Dis 2013; 78:116-26. [PMID: 24315569 DOI: 10.1016/j.diagmicrobio.2013.10.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 10/11/2013] [Accepted: 10/11/2013] [Indexed: 12/21/2022]
Abstract
The aim of this study was to develop a rapid and simple flow cytometric bacterial infection marker. In this prospective comparative study, quantitative flow cytometric analysis of CD10, CD35, CD66b, CD282, and MHC Class I molecules on human neutrophils, monocytes, and B-lymphocytes from 141 hospitalized febrile patients with suspected infection and from 50 healthy controls was performed. We developed a flow cytometric marker of local and systemic bacterial infections, designated "bacterial infection (BI)-INDEX", incorporating the quantitative analysis of CD10, CD35, MHCI, CD66b, and CD282 on neutrophils, monocytes, and B-lymphocytes, which displayed 90% sensitivity and 96% specificity in distinguishing between microbiologically confirmed bacterial (n = 31) and viral infections (n = 27) within a 1-h time-frame. We propose that our novel rapid BI-INDEX test will be useful in assisting physicians to ascertain whether antibiotic treatment is required, thus limiting unnecessary antimicrobial usage.
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Affiliation(s)
- Jari Nuutila
- Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | | | - Ulla Hohenthal
- Department of Medicine, Turku University Hospital, 20521 Turku, Finland
| | - Pirkko Kotilainen
- Department of Medicine, Turku University Hospital, 20521 Turku, Finland
| | | | | | - Esa-Matti Lilius
- Department of Biochemistry, University of Turku, 20014 Turku, Finland
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7
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Bose N, Chan ASH, Guerrero F, Maristany CM, Qiu X, Walsh RM, Ertelt KE, Jonas AB, Gorden KB, Dudney CM, Wurst LR, Danielson ME, Elmasry N, Magee AS, Patchen ML, Vasilakos JP. Binding of Soluble Yeast β-Glucan to Human Neutrophils and Monocytes is Complement-Dependent. Front Immunol 2013; 4:230. [PMID: 23964276 PMCID: PMC3740326 DOI: 10.3389/fimmu.2013.00230] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/22/2013] [Indexed: 01/24/2023] Open
Abstract
The immunomodulatory properties of yeast β-1,3/1,6 glucans are mediated through their ability to be recognized by human innate immune cells. While several studies have investigated binding of opsonized and unopsonized particulate β-glucans to human immune cells mainly via complement receptor 3 (CR3) or Dectin-1, few have focused on understanding the binding characteristics of soluble β-glucans. Using a well-characterized, pharmaceutical-grade, soluble yeast β-glucan, this study evaluated and characterized the binding of soluble β-glucan to human neutrophils and monocytes. The results demonstrated that soluble β-glucan bound to both human neutrophils and monocytes in a concentration-dependent and receptor-specific manner. Antibodies blocking the CD11b and CD18 chains of CR3 significantly inhibited binding to both cell types, establishing CR3 as the key receptor recognizing the soluble β-glucan in these cells. Binding of soluble β-glucan to human neutrophils and monocytes required serum and was also dependent on incubation time and temperature, strongly suggesting that binding was complement-mediated. Indeed, binding was reduced in heat-inactivated serum, or in serum treated with methylamine or in serum reacted with the C3-specific inhibitor compstatin. Opsonization of soluble β-glucan was demonstrated by detection of iC3b, the complement opsonin on β-glucan-bound cells, as well as by the direct binding of iC3b to β-glucan in the absence of cells. Binding of β-glucan to cells was partially inhibited by blockade of the alternative pathway of complement, suggesting that the C3 activation amplification step mediated by this pathway also contributed to binding.
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9
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Polando R, Dixit UG, Carter CR, Jones B, Whitcomb JP, Ballhorn W, Harintho M, Jerde CL, Wilson ME, McDowell MA. The roles of complement receptor 3 and Fcγ receptors during Leishmania phagosome maturation. J Leukoc Biol 2013; 93:921-32. [PMID: 23543768 DOI: 10.1189/jlb.0212086] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Leishmania are intracellular parasites adapted to surviving in macrophages, whose primary function is elimination of invading pathogens. Leishmania entry into host cells is receptor-mediated. These parasites are able to engage multiple host cell-surface receptors, including MR, TLRs, CR3, and FcγRs. Here, we investigated the role of CR3 and FcγR engagement on the maturation of Leishmania-containing phagosomes using CD11b-/- and FcγR-/- macrophages, and assessing EEA1 and lysosome-associated proteins is necessary for the phagosome maturation delay, characteristic of Leishmania infection. Leishmania-containing phagosomes do not fuse with lyosomes until 5 h postinfection in WT mice. Phagolysosome fusion occurs by 1 h in CD11b and FcγR common chain KO macrophages, although receptor deficiency does not influence Leishmania entry or viability. We also investigated the influence of serum components and their effects on phagosome maturation progression. Opsonization with normal mouse serum, complement-deficient serum, or serum from Leishmania-infected mice all influenced phagosome maturation progression. Our results indicate that opsonophagocytosis influences phagosomal trafficking of Leishmania without altering the intracellular fate.
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Affiliation(s)
- Rachel Polando
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
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Nuutila J, Jalava-Karvinen P, Hohenthal U, Kotilainen P, Pelliniemi TT, Nikoskelainen J, Lilius EM. A rapid flow cytometric method for distinguishing between febrile bacterial and viral infections. J Microbiol Methods 2012; 92:64-72. [PMID: 23154042 DOI: 10.1016/j.mimet.2012.11.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 11/02/2012] [Accepted: 11/05/2012] [Indexed: 11/26/2022]
Abstract
Antibiotic resistance due to the inappropriate use of antimicrobials is one of the most critical public health problems worldwide. A major factor underlying the unnecessary use of antibiotics is the lack of rapid and accurate diagnostic tests. Therefore, we aimed to develop a novel rapid flow cytometric method for distinguishing between febrile bacterial and viral infections. In this prospective comparative study, quantitative flow cytometric analysis of FcγRII/CD32, CR1/CD35, MHC Class I receptor (MHCI), and C5aR/CD88 on human phagocytes was performed in 286 hospitalized febrile patients with suspected infection. After using microbiological and serological detection methods, or clinical diagnosis, 205 patients were identified with either bacterial (n=136) or viral (n=69) infection. Receptor data from patients were compared to those of 50 healthy controls. We developed a flow cytometric marker of local and systemic bacterial infections designated "bacterial infection score (BIS)" incorporating the quantitative analysis of FcγRII/CD32, CR1/CD35, C5aR/CD88 and MHCI on neutrophils and/or monocytes, which displays 91% sensitivity and 92% specificity in distinguishing between microbiologically confirmed bacterial (n=77) and serologically confirmed viral infections (n=61) within 1h. The BIS method was effectively applied to distinguish between bacterial and viral (pandemic H1N1 influenza) pneumonia cases with 96% sensitivity and 92% specificity. We propose that the rapid BIS test can assist physicians in deciding whether antibiotic treatment is necessary, thus reducing unnecessary antimicrobial use.
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Affiliation(s)
- Jari Nuutila
- Department of Biochemistry, University of Turku, Turku, Finland.
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Carrillo-Conde BR, Ramer-Tait AE, Wannemuehler MJ, Narasimhan B. Chemistry-dependent adsorption of serum proteins onto polyanhydride microparticles differentially influences dendritic cell uptake and activation. Acta Biomater 2012; 8:3618-28. [PMID: 22684115 DOI: 10.1016/j.actbio.2012.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 05/29/2012] [Accepted: 06/01/2012] [Indexed: 11/26/2022]
Abstract
The delivery of antigen-loaded microparticles to dendritic cells (DCs) may benefit from surface optimization of the microparticles themselves, thereby exploiting the material properties and introducing signals that mimic pathogens. Following in vivo administration microparticle surface characteristics are likely to be significantly modified as proteins are quickly adsorbed onto their surface. In this work we describe the chemistry-dependent serum protein adsorption patterns on polyanhydride particles and the implications for their molecular interactions with DCs. The enhanced expression of MHC II and CD40 on DCs after incubation with amphiphilic polyanhydride particles, and the increased secretion of IL-6, TNF-α, and IL-12p40 by hydrophobic polyanhydride particles exemplified the chemistry-dependent activation of DCs by sham-coated particles. The presence of proteins such as complement component 3 and IgG further enhanced the adjuvant properties of these vaccine carriers by inducing DC maturation (i.e. increased cell surface molecule expression and cytokine secretion) in a chemistry-dependent manner. Utilizing DCs derived from complement receptor 3-deficient mice (CR3(-/-) mice) identified a requirement for CR3 in the internalization of both sham- and serum-coated particles. These studies provide valuable insights into the rational design of targeted vaccine platforms aimed at inducing robust immune responses and improving vaccine efficacy.
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Schwartz JT, Barker JH, Long ME, Kaufman J, McCracken J, Allen LAH. Natural IgM mediates complement-dependent uptake of Francisella tularensis by human neutrophils via complement receptors 1 and 3 in nonimmune serum. THE JOURNAL OF IMMUNOLOGY 2012; 189:3064-77. [PMID: 22888138 DOI: 10.4049/jimmunol.1200816] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A fundamental step in the life cycle of Francisella tularensis is bacterial entry into host cells. F. tularensis activates complement, and recent data suggest that the classical pathway is required for complement factor C3 deposition on the bacterial surface. Nevertheless, C3 deposition is inefficient and neither the specific serum components necessary for classical pathway activation by F. tularensis in nonimmune human serum nor the receptors that mediate infection of neutrophils have been defined. In this study, human neutrophil uptake of GFP-expressing F. tularensis strains live vaccine strain and Schu S4 was quantified with high efficiency by flow cytometry. Using depleted sera and purified complement components, we demonstrated first that C1q and C3 were essential for F. tularensis phagocytosis, whereas C5 was not. Second, we used purification and immunodepletion approaches to identify a critical role for natural IgM in this process, and then used a wbtA2 mutant to identify LPS O-Ag and capsule as prominent targets of these Abs on the bacterial surface. Finally, we demonstrate using receptor-blocking Abs that CR1 (CD35) and CR3 (CD11b/CD18) acted in concert for phagocytosis of opsonized F. tularensis by human neutrophils, whereas CR3 and CR4 (CD11c/CD18) mediated infection of human monocyte-derived macrophages. Altogether, our data provide fundamental insight into mechanisms of F. tularensis phagocytosis and support a model whereby natural IgM binds to surface capsular and O-Ag polysaccharides of F. tularensis and initiates the classical complement cascade via C1q to promote C3 opsonization of the bacterium and phagocytosis via CR3 and either CR1 or CR4 in a phagocyte-specific manner.
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Affiliation(s)
- Justin T Schwartz
- Inflammation Program, University of Iowa and Veterans Administration Medical Center, Iowa City, IA 52242, USA
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Ueno N, Wilson ME. Receptor-mediated phagocytosis of Leishmania: implications for intracellular survival. Trends Parasitol 2012; 28:335-44. [PMID: 22726697 DOI: 10.1016/j.pt.2012.05.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 05/18/2012] [Accepted: 05/21/2012] [Indexed: 01/12/2023]
Abstract
The extracellular promastigote stage of Leishmania spp. is transmitted to mammals by a sand fly vector. Leishmania promastigotes ligate host macrophage receptors, triggering phagocytosis and subsequent internalization, a crucial step for survival. Parasites transform intracellularly to the amastigote stage. Many studies document different receptors detecting promastigotes and amastigotes, but the relative importance of each interaction is ill-defined. Recent studies suggest that the macrophage receptors utilized during phagocytosis impact the intracellular fate of the parasite. This review summarizes the receptors implicated in Leishmania phagocytosis over the past 30 years. It then proceeds to weigh the evidence for or against their potential roles in intracellular parasite trafficking.
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Affiliation(s)
- Norikiyo Ueno
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
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Yoshikawa N, Sakamoto K, Mizuno S, Sakaguchi J, Miyamoto H, Mine T, Sasaki H, Fumoto S, Nishida K. Multiple components in serum contribute to hepatic transgene expression by lipoplex in mice. J Gene Med 2012; 13:632-43. [PMID: 22002583 DOI: 10.1002/jgm.1618] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Interaction of cationic liposome/plasmid DNA complex (lipoplex) with serum was not a limiting factor for in vivo transfection. After intraportal injection of lipoplex, hepatic transgene expression was enhanced by interaction with serum in mice. In the present study, we analyzed the mechanism of enhanced hepatic transgene expression of lipoplex by interaction with serum components. METHODS Lipoplexes were incubated with several serum components for 5 min at 37 ° C before administration. Transfection efficiency of lipoplexes was measured 6 h after intraportal injection of lipoplex in mice. RESULTS Depletion of divalent cation from serum decreased hepatic transgene expression. The addition of calcium ion to divalent cation-depleted serum restored transgene expression. Heat-inactivated serum and bovine serum albumin diminished the enhancing effect of serum on hepatic transgene expression. On the other hand, removal of anionic proteins from serum using an anion-exchanging column was critical for the enhancing effect of serum on transgene expression. Among the serum components tested, fibronectin and complement component C3 enhanced hepatic transgene expression. CONCLUSIONS Hepatic transgene expression by lipoplex was enhanced by interaction with multiple components in serum. Interaction of lipoplex with serum could be an important factor for successful in vivo gene transfer. Hence, the information obtained in the present study is valuable for the future development of effective gene carriers.
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Affiliation(s)
- Naoki Yoshikawa
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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Park SY, Shin YP, Kim CH, Park HJ, Seong YS, Kim BS, Seo SJ, Lee IH. Immune evasion of Enterococcus faecalis by an extracellular gelatinase that cleaves C3 and iC3b. THE JOURNAL OF IMMUNOLOGY 2009; 181:6328-36. [PMID: 18941224 DOI: 10.4049/jimmunol.181.9.6328] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Enterococcus faecalis (Ef) accounts for most cases of enterococcal bacteremia, which is one of the principal causes of nosocomial bloodstream infections (BSI). Among several virulence factors associated with the pathogenesis of Ef, an extracellular gelatinase (GelE) has been known to be the most common factor, although its virulence mechanisms, especially in association with human BSI, have yet to be demonstrated. In this study, we describe the complement resistance mechanism of Ef mediated by GelE. Using purified GelE, we determined that it cleaved the C3 occurring in human serum into a C3b-like molecule, which was inactivated rapidly via reaction with water. This C3 convertase-like activity of GelE was shown to result in a consumption of C3 and thus inhibited the activation of the complement system. Also, GelE was confirmed to degrade an iC3b that was deposited on the Ag surfaces without affecting the bound C3b. This proteolytic effect of GelE against the major complement opsonin resulted in a substantial reduction in Ef phagocytosis by human polymorphonuclear leukocytes. In addition, we verified that the action of GelE against C3, which is a central component of the complement cascade, was human specific. Taken together, it was suggested that GelE may represent a promising molecule for targeting human BSI associated with Ef.
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Affiliation(s)
- Shin Yong Park
- Department of Biotechnology, Hoseo University, Asan City, Chungnam, South Korea
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Abstract
PURPOSE OF REVIEW To commence proper treatment as rapidly as possible and to reduce unnecessary antibiotic treatments, timely knowledge of whether the infection is bacterial or viral in origin would be beneficial for the clinician. As a reliable prediction of the causative agent of bacterial infection is not possible based on clinical features, there is an ongoing need for sensitive and specific markers of bacterial infection. RECENT FINDINGS The most common differential diagnosis methods are reviewed here. It is also demonstrated that the measurement of the expression of complement receptors, particularly CR1 (CD35), on neutrophils can be a useful preliminary test to differentiate between bacterial and viral infections. In addition, a novel marker of local and systemic bacterial infections designated 'clinical infection score (CIS) point', which incorporates quantitative analysis of complement receptors on neutrophils and standard clinical laboratory data and displays 98% sensitivity and 97% specificity in distinguishing between bacterial and viral infections, is presented. SUMMARY We conclude that the diagnostic yield of measured individual variables in distinguishing between bacterial and viral infections increases upon combination.
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Affiliation(s)
- Jari Nuutila
- Department of Biochemistry, University of Turku, Turku, Finland.
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Rinder CS, Smith MJ, Rinder HM, Cortright DN, Brodbeck RM, Krause JE, Smith BR. Leukocyte effects of C5a-receptor blockade during simulated extracorporeal circulation. Ann Thorac Surg 2007; 83:146-52. [PMID: 17184649 DOI: 10.1016/j.athoracsur.2006.08.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2006] [Revised: 08/03/2006] [Accepted: 08/04/2006] [Indexed: 12/22/2022]
Abstract
BACKGROUND Distinct pathways of leukocyte activation during simulated cardiopulmonary bypass are mediated by the complement C5a anaphylatoxin. We hypothesized that a human C5a receptor antagonist would specifically inhibit the inflammatory response of neutrophils to simulated extracorporeal circulation, while preserving the C5b-9 pathway for innate immunity. METHODS An in vitro extracorporeal circuit recirculated fresh heparinized whole blood through a membrane oxygenator with and without addition of a small molecule human C5a receptor antagonist. Samples were periodically drawn over 90 minutes for complement and leukocyte activation studies. RESULTS Addition of the C5a receptor antagonist to simulated extracorporeal circulation abrogated both neutrophil CD11b upregulation and interleukin 8 release (p < 0.01 for both), despite full generation of C3a and C5b-9; however, elastase release from neutrophils was unaffected. Although C5a receptor blockade only trended toward inhibiting monocyte CD11b upregulation (p = 0.09), circuit clearance of both monocytes (p = 0.04) and neutrophils (p = 0.01) was significantly decreased. In addition, the C5a receptor antagonist completely blocked both neutrophil-platelet and monocyte-platelet conjugate formation (p < 0.001 for both), without affecting platelet P-selectin expression. CONCLUSIONS C5a receptor blockade during simulated extracorporeal circulation completely blocked neutrophil beta2 integrin upregulation and induction of plasma interleukin 8, suggesting an acute downregulatory effect on neutrophil chemotaxis-related pathways, while preserving terminal complement generation and neutrophil elastase release. Inhibition of leukocyte-platelet conjugate formation suggests a novel function for leukocyte adhesive receptors, possibly related to preservation of elastase generation.
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Affiliation(s)
- Christine S Rinder
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06520-8051, USA.
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Chellat F, Merhi Y, Moreau A, Yahia L. Therapeutic potential of nanoparticulate systems for macrophage targeting. Biomaterials 2005; 26:7260-75. [PMID: 16023200 DOI: 10.1016/j.biomaterials.2005.05.044] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The use of non-viral nanoparticulate systems for the delivery of therapeutic agents is receiving considerable attention for medical and pharmaceutical applications. This increasing interest results from the fact that these systems can be designed to meet specific physicochemical requirements, and they display low toxic and immunogenic effects. Among potential cellular targets by drug-loaded nanoparticles, macrophages are considered because they play a central role in inflammation and they act as reservoirs for microorganisms that are involved with deadly infectious diseases. The most common and potent drugs used in macrophage-mediated diseases treatment often induce unwanted side effects, when applied as a free form, due to the necessity of high doses to induce a satisfactory effect. This could result in their systemic spreading, a lack of bioavailability at the desired sites, and a short half-life. Therefore, the use of drug-loaded nanoparticles represents a good alternative to avoid, or at least decrease, side effects and increase efficacy. In this manuscript, we present an overview of the usefulness of nanoparticles for macrophage-mediated therapies in particular. We discuss, though not exhaustively, the potential of therapeutic agent-loaded nanoparticles for some macrophage-mediated diseases. We also underline the most important parameters that affect the interaction mechanisms of the macrophages and the physicochemical aspects of the particulate systems that may influence their performance in macrophage-targeted therapies.
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Affiliation(s)
- Fatiha Chellat
- Biomedical Engineering Institute, Ecole Polytechnique de Montréal, C.P. 6079, Succursale Centre-ville, Montréal, Qué., Canada H3C 3A7.
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Josefsson EC, Gebhard HH, Stossel TP, Hartwig JH, Hoffmeister KM. The macrophage alphaMbeta2 integrin alphaM lectin domain mediates the phagocytosis of chilled platelets. J Biol Chem 2005; 280:18025-32. [PMID: 15741160 DOI: 10.1074/jbc.m501178200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
alpha(M)beta(2) integrin receptors on myeloid cells mediate the adhesion or uptake of diverse ligands. Ligand binding occurs in the alpha(M) chain, which is composed of an I domain and a lectin domain. The alpha(M) I domain binds iC3b, fibrinogen, intercellular adhesion molecule-1, and other ligands and mediates the adhesion of neutrophils to platelet glycoprotein Ibalpha (GPIbalpha). alpha(M)beta(2) also recognizes beta-GlcNAc residues on GPIbalpha that are clustered on platelets after cooling. The phagocytosis of chilled platelets could be reconstituted when Chinese hamster ovary cells were transfected with alpha(M)beta(2). Replacement of the I domain or the lectin domain of the alpha(M) chain with the corresponding domain from the alpha(X) chain (p150) revealed that the activity of the alpha(M)beta(2) integrin toward chilled platelets resides within the lectin domain and does not require the I domain. Additional evidences for this conclusion are: 1) Sf9 cells expressing solely the alpha(M) lectin domain bound chilled platelets, and 2) soluble recombinant alpha(M) lectin domain inhibited the phagocytosis of chilled platelets by alpha(M)beta(2)-expressing THP-1 cells, whereas I domain substrates showed no inhibitory effect. Therefore chilled platelets are removed from blood by an interaction between beta-GlcNAc residues on clustered GPIbalpha and the lectin domain of alpha(M) chain of the alpha(M)beta(2) integrin, distinguishing this interaction from those mediated by the alpha(M) I domain.
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Affiliation(s)
- Emma C Josefsson
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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20
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Russo-Carbolante EMDS, Azzolini AECS, Polizello ACM, de Assis-Pandochi AI, Lucisano-Valim YM. Propylthiouracil and thiamazole do not alter in vitro neutrophil oxidative burst. Metabolism 2005; 54:300-5. [PMID: 15736106 DOI: 10.1016/j.metabol.2004.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Propylthiouracil and thiamazole are thionamides used in the treatment of hyperthyroidism. In addition to reducing thyroid hormone synthesis, these drugs have other activities that improve the hypermetabolic state of the patients as well as adverse and toxic effects. The capacity of these 2 drugs to interfere with the production of reactive oxygen species of human neutrophils exposed in vitro to these drugs was evaluated. The production of reactive oxygen species was assessed by chemiluminescence assays and the cells were stimulated with zymosan particles opsonized with a pool of normal human serum. No alteration was found in the chemiluminescence response of treated human neutrophils when compared to controls. The results show that these drugs, at the studied concentrations and with the experimental approach used, have no direct effect on the production of oxidative burst of neutrophils. We conclude that if these drugs have any action on the oxidative metabolism of neutrophils these might include some metabolization steps that do not take place in this in vitro model.
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21
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Jelezarova E, Luginbuehl A, Lutz HU. C3b2-IgG Complexes Retain Dimeric C3 Fragments at All Levels of Inactivation. J Biol Chem 2003; 278:51806-12. [PMID: 14527961 DOI: 10.1074/jbc.m304613200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C3b2-IgG complexes are formed during complement activation in serum by attachment of two C3b molecules (the proteolytically activated form of C3) to one IgG heavy chain (IgG HC) via ester bonds. Because of the presence of two C3b molecules, these complexes are very efficient activators of the alternative complement pathway. Likewise, dimeric C3b is known to enhance complement receptor 1-dependent phagocytosis, and dimeric C3d (the smallest thioester-containing fragment of C3) linked to a protein antigen facilitates CR2-dependent B-cell proliferation. Because the efficiency of all these interactions depends on the number of C3 fragments, we investigated whether C3b2-IgG complexes retained dimeric structure upon physiological inactivation. We used two-dimensional SDS-PAGE and Western blot to study the arrangement of the C3b molecules by analyzing the fragmentation pattern after cleavage of the ester bonds. Upon inactivation with factors H and I, a 185-kDa band was generated under reducing conditions. It released IgG HC and the 65-kDa fragment of C3b alpha' chain after hydrolysis of the ester bonds with hydroxylamine. The two C3b molecules were not 65-kDa-to-40-kDa linked, because neither ester-bonded 65 kDa HC nor 65 kDa-40 kDa fragments were observed, nor was a 40-kDa peptide released after hydroxylamine cleavage. Factor I and CR1 cleaved the C3b2-IgG molecule to its final physiological product, C3dg2-IgG, which migrated as a 133-kDa fragment in reduced form. This fragment released exclusively C3dg (the final physiological product of C3b inactivation by factor I) and IgG HC. C3dg2-HC appeared as a double band on SDS-PAGE only at low gel porosity, suggesting the presence of two conformers of the same composition. Our results suggest that, upon physiological inactivation, C3b2-IgG complexes retain dimeric inactivated C3b and C3dg, which allows bivalent binding to the corresponding complement receptors.
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Affiliation(s)
- Emiliana Jelezarova
- Institute of Biochemistry, Swiss Federal Institute of Technology, CH-8093 Zurich, Switzerland.
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22
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Marzocchi-Machado CM, Alves CMOS, Azzolini AECS, Polizello ACM, Carvalho IF, Lucisano-Valim YM. Fcgamma and complement receptors: expression, role and co-operation in mediating the oxidative burst and degranulation of neutrophils of Brazilian systemic lupus erythematosus patients. Lupus 2003; 11:240-8. [PMID: 12043888 DOI: 10.1191/0961203302lu172oa] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have investigated the individual role of FcgammaR and CR, as well as their cooperation, in mediating the oxidative burst and degranulation of neutrophils of Brazilian systemic lupus erythematosus (SLE) patients. Neutrophils were stimulated with the immune complexes (IC)-IgG or -F(ab')2, opsonized or not with normal or SLE human serum. The oxidative burst was decreased in neutrophils of active SLE patients compared to healthy controls when this response was mediated by FcgammaR and/or CR, while the degranulation was unaffected. The SLE hypocomplementemia did not affect the oxidative burst mediated only by CR. FcgammaRII and CR1 expression on neutrophils of active SLE patients was reduced, while the expression of FcgammaRIII and CR3 was unaffected. These results suggest that the different FcgammaR and CR may be involved or cooperate in different ways in the mediation of the oxidative burst and the degranulation. Moreover, the decreased oxidative burst of neutrophils of active SLE patients may not depend only on SLE hypocomplementemia for IC opsonization. These observations are directed at the understanding of how each of these immune system components (FcgammaR, CR and complement) influences the precise biological neutrophil responses both in physiological and pathological conditions. Since the Brazilian population comprises many races, these results are important because they are directed at a specific population of SLE patients.
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Affiliation(s)
- C M Marzocchi-Machado
- Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil
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Ross GD. Role of the lectin domain of Mac-1/CR3 (CD11b/CD18) in regulating intercellular adhesion. Immunol Res 2002; 25:219-27. [PMID: 12018461 DOI: 10.1385/ir:25:3:219] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Leukocyte diapedesis requires that Mac-1/CR3-dependent adhesion be regulated so that cells can move from one attachment site to another. The high affinity adhesion state of Mac-1/CR3 is generated when it forms a lectin-dependent complex with the receptor for urokinase plasminogen activator (uPAR; CD87). The extensively glycosylated uPAR binds to the same C-terminal lectin domain of CD11b that had previously been shown to prime Mac-1/CR3 for cytotoxic degranulation in response to beta-glucan. uPAR and beta-glucan compete for a lectin site that is near to the CBRM1/23 epitope (residues 943-1047) at the C-terminus of CD11b, and thus the lectin domain is critical to both the adhesion and cytotoxic functions of Mac-1/CR3. Adhesion is reversed when the uPA enzyme is captured by its receptor (uPAR), causing uPAR to bind to CD11b at a second site (residues 424-440) that is in between the N-terminal I-domain and the divalent cation binding region.
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Affiliation(s)
- Gordon D Ross
- The James Graham Brown Cancer Center, Department of Pathology, University of Louisville, KY 40292, USA.
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DeMaster E, Schnitzler N, Cheng Q, Cleary P. M(+) group a streptococci are phagocytized and killed in whole blood by C5a-activated polymorphonuclear leukocytes. Infect Immun 2002; 70:350-9. [PMID: 11748201 PMCID: PMC127641 DOI: 10.1128/iai.70.1.350-359.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2001] [Revised: 09/26/2001] [Accepted: 10/10/2001] [Indexed: 11/20/2022] Open
Abstract
Historically, resistance to phagocytosis has been determined by incubating group A streptococci in human blood and comparing the numbers of CFU before and after incubation. Utilizing a flow cytometry-based technique, we have investigated the phagocytosis of M(+) group A streptococci by polymorphonuclear leukocytes (PMNs) in heparinized human peripheral whole blood. Intracellular labeling of streptococci with a nontoxic fluorescent dye allowed us to quantify the association and phagocytosis of M(+) streptococci by PMNs in whole blood in the presence or absence of C5a, a physiologically important chemotactic activator of PMNs. We found that wild-type strains of group A streptococci that are resistant to phagocytosis (determined by the classical Lancefield method) readily associate with C5a-activated whole-blood PMNs. In the absence of opsonizing M-type-specific antibodies, the M(+) streptococci associated with PMNs are phagocytized and killed. In addition, blockade of the beta(2) integrin, CD11b/CD18, with anti-human CD11b monoclonal antibody inhibited association between M(+) streptococci and C5a-activated PMNs. These findings establish a new relationship between M(+) streptococci and PMNs, in which C5a-activated PMNs have the capacity to kill M(+) streptococci in whole blood through a receptor-mediated phagocytic mechanism.
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Affiliation(s)
- Eric DeMaster
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota 55455, USA
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25
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Rivas AL, Quimby FW, Coksaygan O, Alba A, Arina A, Arrobas MJ, González RN, Mohammed HO, Lein DH. Expression of CD3 and CD11b antigens on blood and mammary gland leukocytes and bacterial survival in milk of cows with experimentally induced Staphylococcus aureus mastitis. Am J Vet Res 2001; 62:1840-51. [PMID: 11763169 DOI: 10.2460/ajvr.2001.62.1840] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To differentiate early (1 to 8 days) from late (9 to 14 days) inflammatory phases and assess relationships between leukocyte phenotype and bacterial recovery in cows with Staphylococcus aureus-induced mastitis. ANIMALS 10 first-lactation Holstein cows. PROCEDURE Blood and milk samples were collected from 4 or 6 cows before and after intramammary infusion of sterile broth or S. aureus, respectively. Flow cytometric expression of CD3 and CD11b antigens on blood and milk leukocytes, leukocyte differential counts, bacterial counts in milk, and somatic cell counts were determined longitudinally. RESULTS Density of CD3 molecules decreased on blood lymphocytes and increased on milk lymphocytes after infusion of bacteria. Density of CD11b molecules on lymphocytes and phagocytes and percentage of CD11b+ lymphocytes in milk increased significantly after infusion; maximum values were achieved during the early inflammatory phase. Density of CD3 and CD11b molecules on milk lymphocytes and macrophages, respectively, 1 day after inoculation were negatively correlated with bacterial recovery on day 1 and days 9 to 14, respectively. Density of CD11b molecules on milk macrophages and the ratios of phagocyte to lymphocyte percentages and polymorphonuclear cell to macrophage percentages in milk differentiated the early from the late inflammatory phase. CONCLUSIONS AND CLINICAL RELEVANCE Activation of bovine mammary gland macrophages and T cells in response to intramammary infusion of S. aureus was associated with an inability to culture this bacterium from milk. Identification of specific inflammatory phases of S. aureus-induced mastitis in cows may allow for the design of more efficacious treatment and control programs.
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Affiliation(s)
- A L Rivas
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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26
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Rittig MG, Alvarez-Martinez MT, Porte F, Liautard JP, Rouot B. Intracellular survival of Brucella spp. in human monocytes involves conventional uptake but special phagosomes. Infect Immun 2001; 69:3995-4006. [PMID: 11349069 PMCID: PMC98462 DOI: 10.1128/iai.69.6.3995-4006.2001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella spp. are facultative intracellular parasites of various mammals, including humans, typically infecting lymphoid as well as reproductive organs. We have investigated how B. suis and B. melitensis enter human monocytes and in which compartment they survive. Peripheral blood monocytes readily internalized nonopsonized brucellae and killed most of them within 12 to 18 h. The presence of Brucella-specific antibodies (but not complement) increased the uptake of bacteria without increasing their intracellular survival, whereas adherence of the monocytes or incubation in Ca(2+)- and Mg(2+)-free medium reduced the uptake. Engulfment of all Brucella organisms (regardless of bacterial viability or virulence) initially resulted in phagosomes with tightly apposed walls (TP). Most TP were fully fusiogenic and matured to spacious phagolysosomes containing degraded bacteria, whereas some TP (more in monocyte-derived macrophages, HeLa cells, and CHO cells than in monocytes) remained tightly apposed to intact bacteria. Immediate treatment of infected host cells with the lysosomotropic base ammonium chloride caused a swelling of all phagosomes and a rise in the intraphagosomal pH, abolishing the intracellular survival of Brucella. These results indicate that (i) human monocytes readily internalize Brucella in a conventional way using various phagocytosis-promoting receptors, (ii) the maturation of some Brucella phagosomes is passively arrested between the steps of acidification and phagosome-lysosome fusion, (iii) brucellae are killed in maturing but not in arrested phagosomes, and (iv) survival of internalized Brucella depends on an acidic intraphagosomal pH and/or close contact with the phagosomal wall.
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Affiliation(s)
- M G Rittig
- INSERM U-431, Université de Montpellier II, Montpellier, France.
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27
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Kizaki T, Suzuki K, Hitomi Y, Iwabuchi K, Onoé K, Ishida H, Izawa T, Ji LL, Ohno H, Kizkai T. Activation and apoptosis of murine peritoneal macrophages by acute cold stress. Biochem Biophys Res Commun 2001; 283:700-6. [PMID: 11341782 DOI: 10.1006/bbrc.2001.4843] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Effects of acute cold stress (5 degrees C for 24 h) on the functions of peritoneal macrophages and the mechanisms for controlling host homeostasis were investigated in mice. Phagocytic activity and expression of the cell surface adhesion molecule CD11b/CD18 were markedly increased in peritoneal exudate cells by acute cold stress. These alterations were attributable to an increased number and phenotypical changes of adherent cells from acute cold-stressed mice. On the other hand, a lipopolysaccharide-induced activity of src-family tyrosine kinase Fgr, an expression of interleukin-1beta (IL-1 beta) mRNA, and a bioactivity of IL-1 in the culture supernatants of adherent cells from acute cold-stressed mice were markedly lower than those from control mice. A time course study revealed that the number of adherent cells in peritoneal exudate cells was markedly increased in mice exposed to cold for 24 h but returned to normal numbers when mice were exposed to cold for 72 h. DNA fragmentation and Annexin-V(+) cells were observed in peritoneal exudate cells from acute-cold stressed mice. Thus, cold stress activated macrophages but these macrophages were destined to be eliminated by apoptosis.
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Affiliation(s)
- T Kizaki
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Tokyo, Mitaka, 181-8611, Japan.
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28
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Nockher WA, Wiemer J, Scherberich JE. Haemodialysis monocytopenia: differential sequestration kinetics of CD14+CD16+ and CD14++ blood monocyte subsets. Clin Exp Immunol 2001; 123:49-55. [PMID: 11167997 PMCID: PMC1905970 DOI: 10.1046/j.1365-2249.2001.01436.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In peripheral blood the majority of circulating monocytes present a CD14highCD16- (CD14++) phenotype, while a subpopulation shows a CD14lowCD16+ (CD14+CD16+) surface expression. During haemodialysis (HD) using cellulosic membranes transient leukopenia occurs. In contrast, synthetic biocompatible membranes do not induce this effect. We compared the sequestration kinetics for the CD14+CD16+ and CD14++ monocyte subsets during haemodialysis using biocompatible dialysers. Significant monocytopenia, as measured by the leucocyte count, occurred only during the first 30 min. However, remarkable differences were observed between the different monocyte subsets. CD14++ monocyte numbers dropped to 77 +/- 13% of the predialysis level after 15 min, increasing to > or = 93% after 60 min. In contrast, the CD14+CD16+ subset decreased to 33 +/- 15% at 30 min and remained suppressed for the course of dialysis (67 +/- 11% at 240 min). Approximately 6 h after the end of HD the CD14+CD16+ cells returned to basal levels. Interestingly, the CD14+CD16+ monocytes did not show rebound monocytosis while a slight monocytosis of CD14++ monocytes was occasionally observed during HD. A decline in CD11c surface density paralleled the sequestration of CD14+CD16+ monocytes. Basal surface densities of important adhesion receptors differed significantly between the CD14+CD16+ and CD14++ subsets. In conclusion, during HD the CD14+CD16+ subset revealed different sequestration kinetics, with a more pronounced and longer disappearance from the blood circulation, compared with CD14++ monocytes. This sequestration kinetics may be due to a distinct surface expression of major adhesion receptors which facilitate leucocyte-leucocyte, as well as leucocyte-endothelial, interactions.
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Affiliation(s)
- W A Nockher
- Institute of Clinical Chemistry, Hospital München-Bogenhausen and 2nd Medical Department, Hospital München-Harlaching, München, Germany
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Marzocchi-Machado CM, Russo EM, Alves CM, Polizello AC, Azzolini AE, Lucisano-Valim YM. Effect of low-dose prednisone in vivo on the ability of complement receptor to mediate an oxidative burst in rat neutrophils. IMMUNOPHARMACOLOGY 2000; 49:247-54. [PMID: 10996022 DOI: 10.1016/s0162-3109(00)00204-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Glucocorticoids have been used in the treatment of a variety of inflammatory processes including autoimmune diseases. However, the influence of low-dose glucocorticoids on the respiratory burst activity of neutrophils has not been studied. The aim of this work was to study the effect of treatment with low-dose prednisone on the oxidative burst of rat peripheral blood neutrophils. Wistar male rats were treated with prednisone by gavage (28, 87 or 257 microg/animal/day) for 7 or 15 days. These doses are equivalent to 10, 30 or 90 mg/adult human ( approximately 70 kg)/day, respectively. Sera from normal rats were used to opsonize zymosan (opZy). Neutrophils (1x10(5)) were stimulated by opZy and the oxidative burst of control or treated rat cells was measured by luminol-dependent chemiluminescence (CL). Prednisone did not affect the CL of rat neutrophils for either period of treatment, or any studied doses, when compared with controls. These results suggest that the low-dose prednisone has no effect on the oxidative burst mediated by complement receptors during the rat neutrophil phagocytosis of complement-opZy.
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Affiliation(s)
- C M Marzocchi-Machado
- Laboratory of Biochemistry, Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences, Universidade de São Paulo, SP, 14040-903, Ribeirão Preto, Brazil.
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Abstract
CR3 (CD11b/CD18), a beta(2) integrin, has a key role in innate antimicrobial defenses, as evidenced by the leukocyte adhesion (CD18) deficiency syndrome in humans and the CD11b knockout mouse. CR3 is a highly versatile pattern-recognition receptor that activates leukocytes via signaling complexes and actin reorganization, mediates phagocytosis, and promotes leukocyte transmigration.
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Affiliation(s)
- M R Ehlers
- BioNebraska, Inc., 3820 NW 46thStreet, Lincoln, NE 68524, USA
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Abstract
Leishmania are intracellular protozoan parasites of macrophages. At the cellular level, the disease leishmaniasis involves the invasion of tissue macrophages by the parasite, the avoidance of cellular killing mechanisms, and the subsequent intracellular replication of parasites, with the eventual spread of the organisms to adjacent macrophages. This paper describes the process by which Leishmania organisms invade macrophages, with an overview of some of the molecules involved in this process; the mechanisms available to macrophages that have the potential to restrict the growth of Leishmania within them; and the ways that Leishmania and Leishmania-derived molecules can modulate macrophage functions and circumvent leukocyte antimicrobial responses.
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Affiliation(s)
- M M Kane
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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32
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Affiliation(s)
- W Solbach
- Institute for Medical Microbiology and Hygiene, University of Luebeck, Germany
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33
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Brittingham A, Chen G, McGwire BS, Chang KP, Mosser DM. Interaction of Leishmania gp63 with cellular receptors for fibronectin. Infect Immun 1999; 67:4477-84. [PMID: 10456889 PMCID: PMC96767 DOI: 10.1128/iai.67.9.4477-4484.1999] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The most abundant protein on the surface of the promastigote form of the protozoan parasites Leishmania spp. is a 63-kDa molecule, designated gp63 or leishmanolysin. Because gp63 has been shown to possess fibronectin-like properties, we examined the interaction of gp63 with the cellular receptors for fibronectin. We measured the direct binding of Leishmania to human macrophages or to transfected mammalian cells expressing human fibronectin receptors. Leishmania expressing gp63 exhibited modest but reproducible adhesion to human macrophages and to transfected CHO cells expressing alpha4/beta1 fibronectin receptors. In both cases, this interaction depended on gp63 but occurred independently of the SRYD sequence of gp63, because parasites expressing gp63 with a mutated SRYD sequence bound to macrophages and alpha4/beta1 receptor-expressing cells as well as did wild-type parasites. The contribution of gp63 to parasite adhesion was more pronounced when the assays were performed in the presence of complement, suggesting that the receptors for complement and fibronectin may cooperate to mediate the efficient adhesion of parasites to macrophages. The interaction of gp63 with fibronectin receptors may also play an important role in parasite internalization by macrophages. Erythrocytes to which gp63 was cross-linked were efficiently phagocytized by macrophages, whereas control erythrocytes opsonized with complement alone bound to macrophages but remained peripherally attached to the outside of the cell. Similarly, parasites expressing wild-type gp63 were rapidly and efficiently phagocytized by resting macrophages, whereas parasites lacking gp63 were internalized more slowly. This rapid internalization of gp63-expressing parasites was dependent on the beta1 integrins, because pretreatment of macrophages with monoclonal antibodies to the beta1 integrins decreased the internalization of gp63-expressing parasites. These observations indicate that complement receptors are the primary mediators of parasite adhesion; however, maximal parasite adhesion and internalization may require the participation of the beta1 integrins, which recognize fibronectin-like molecules such as gp63 on the surface of the parasite.
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Affiliation(s)
- A Brittingham
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Rinder CS, Rinder HM, Johnson K, Smith M, Lee DL, Tracey J, Polack G, Higgins P, Yeh CG, Smith BR. Role of C3 cleavage in monocyte activation during extracorporeal circulation. Circulation 1999; 100:553-8. [PMID: 10430771 DOI: 10.1161/01.cir.100.5.553] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We previously demonstrated that inhibiting formation of terminal complement components (C5a and C5b-9) prevents platelet and neutrophil (PMN) but not monocyte activation during simulated extracorporeal circulation (SECC). This study examined whether earlier complement inhibition during SECC, blocking C3a formation, would additionally prevent monocyte activation. METHODS AND RESULTS SECC was established by recirculating heparinized whole blood from human volunteers on a membrane oxygenator. CAB-2, a chimeric protein constructed from genes encoding the complement regulatory proteins CD46 and CD55, inactivates the C3/C5 convertases and blocks in vitro generation of C3a, C5a, and C5b-9. CAB-2 was used in 4 experiments at a final concentration of 300 micrograms/mL and 4 experiments at 30 micrograms/mL; 4 control runs used vehicle alone. Samples were assayed for C3a and C5b-9, monocyte activation (CD11b upregulation), PMN activation (CD11b upregulation and elastase release), and platelet activation (P-selectin expression and monocyte-platelet conjugate formation). CAB-2 at both doses significantly inhibited formation of C3a and C5b-9 during SECC. High-dose CAB-2 significantly blocked monocyte and PMN CD11b upregulation and PMN elastase release. CAB-2 also inhibited formation of platelet activation-dependent monocyte-platelet conjugates. CONCLUSIONS Blockade of complement activation early in the common pathway inhibited monocyte CD11b upregulation during SECC, suggesting that early complement components contribute most to monocyte activation during SECC. As expected, PMN and platelet activation were blocked by terminal complement inhibition. This investigation further elucidates the relation between complement and blood cell activation during simulated cardiopulmonary bypass.
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Affiliation(s)
- C S Rinder
- Department of Laboratory Medicine and Anesthesiology, Yale University School of Medicine, New Haven, CT 06520-8035, USA.
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Xia Y, Ross GD. Generation of Recombinant Fragments of CD11b Expressing the Functional β-Glucan-Binding Lectin Site of CR3 (CD11b/CD18). THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.12.7285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
CR3 (Mac-1; αMβ2 integrin) functions as both a receptor for the opsonic iC3b fragment of C3 triggering phagocytosis or cytotoxicity and an adhesion molecule mediating leukocyte diapedesis. Recent reports have suggested that a CR3 lectin site may be required for both cytotoxic responses and adhesion. Cytotoxic responses require dual recognition of iC3b via the I domain of CD11b and specific microbial surface polysaccharides (e.g., β-glucan) via a separate lectin site. Likewise, adhesion requires a lectin-dependent membrane complex between CR3 and CD87. To characterize the lectin site further, a recombinant baculovirus (rBv) system was developed that allowed high level expression of rCD11b on membranes and in the cytoplasm of Sf21 insect cells. Six rBv were generated that contained truncated cDNA encoding various CD11b domains. Immunoblotting of rBv-infected Sf21 cells showed that some native epitopes were expressed by five of six rCD11b fragments. Lectin activity of rCD11b proteins was evaluated by both flow cytometry with β-glucan-FITC and radioactive binding assays with [125I]β-glucan. Sf21 cells expressing rCD11b that included the C-terminal region, with or without the I-domain, exhibited lectin activity that was inhibited by unlabeled β-glucan or anti-CR3 mAbs. The smallest rCD11b fragment exhibiting lectin activity included the C-terminus and part of the divalent cation binding region. The β-glucan binding affinities of the three C-terminal region-containing rCD11bs expressed on Sf21 cell membranes were not significantly different from each other and were similar to that of neutrophil CR3. These data suggest that the lectin site may be located entirely within CD11b, although lectin site-dependent signaling through CD18 probably occurs with the heterodimer.
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Affiliation(s)
- Yu Xia
- *Division of Experimental Immunology and Immunopathology, Department of Pathology, and
| | - Gordon D. Ross
- *Division of Experimental Immunology and Immunopathology, Department of Pathology, and
- †Department of Microbiology and Immunology, University of Louisville, Louisville, KY 40292
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Ross GD, Vetvicka V, Yan J, Xia Y, Vetvicková J. Therapeutic intervention with complement and beta-glucan in cancer. IMMUNOPHARMACOLOGY 1999; 42:61-74. [PMID: 10408367 DOI: 10.1016/s0162-3109(99)00013-2] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Complement (C) has two major effector systems available for host defense. The membrane attack complex (MAC) generated from components C5-C9 can form membrane-penetrating lesions that lead to cell death by causing a rapid loss of cytoplasmic components. The MAC is only effective against pathogens with outer phospholipid membranes, and cannot kill gram-positive bacteria or yeast whose membranes are protected by cell walls. The most important effector mechanism of C is the opsonization of microbial pathogens with the serum protein C3 that leads to their high avidity attachment to the C3-receptors of phagocytic cells. Pathogens that activate complement are first coated with the C3b fragment of C3, which is rapidly proteolyzed into the iC3b fragment by serum factor I. These iC3b fragments serve to promote the high avidity attachment of the 'iC3b-opsonized' pathogens to the iC3b-receptors (CR3, CD11b/CD18) of phagocytic cells and natural killer (NK) cells, stimulating phagocytosis and/or cytotoxic degranulation. Host cells, including neoplastic tumor cells, have been endowed with natural mechanisms for self-protection against both the MAC and the cytotoxic activation of CR3. This review discusses a novel type of immunotherapy for cancer that uses soluble yeast beta-glucan to override the normal resistance of iC3b-opsonized tumor cells to the cytotoxic activation of phagocyte and NK cell CR3, allowing this important effector mechanism of the C system to function against tumor cells in the same way that it normally functions against bacteria and yeast. Moreover, the cytotoxic activation of beta-glucan-primed NK cell CR3 by iC3b-opsonized tumors is shown to be accompanied by a tumor-localized secretion of the cytokines TNFalpha, IFNalpha, IFNgamma, and IL-6.
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Affiliation(s)
- G D Ross
- Department of Pathology, University of Louisville, KY 40292, USA.
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Vĕtvicka V, Hanikýrová M, Vĕtvicková J, Ross GD. Regulation of CR3 (CD11b/CD18)-dependent natural killer (NK) cell cytotoxicity by tumour target cell MHC class I molecules. Clin Exp Immunol 1999; 115:229-35. [PMID: 9933447 PMCID: PMC1905157 DOI: 10.1046/j.1365-2249.1999.00800.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/1998] [Indexed: 11/20/2022] Open
Abstract
Phagocyte and NK cell CR3 functions as both an adhesion molecule and an iC3b receptor mediating cytotoxic responses to microorganisms. Cytotoxic activation of iC3b receptor function requires ligation of both a CD11b I-domain site for iC3b and a lectin site located in the C-terminus of CD11b. Because tumours lack the CR3-binding polysaccharides of bacteria and fungi, iC3b-opsonized tumours do not stimulate CR3-dependent cytotoxicity. Previous studies showed that NK cells could be induced to kill iC3b-opsonized tumours with small soluble beta-glucans that bound with high affinity to CR3, bypassing the absence of similar polysaccharides on tumour membranes. Because CR3 signalling requires several tyrosine phosphorylation events, it appeared possible that CR3-dependent killing of autologous tumour cells might be suppressed by NK cell inhibitory receptors for MHC class I (KIR and CD94/NKG2) whose action involves recruitment of SHP-1 and SHP-2 tyrosine phosphatases. In the current study, Epstein-Barr virus (EBV)-transformed B cells were used as targets following opsonization with iC3b. Soluble beta-glucan primed CR3 for killing of iC3b-coated B cells, but autologous class I-bearing targets were 84% more resistant than class I-deficient Daudi cells. Blockade of target cell class I with a MoAb specific for a domain recognized by both KIR and CD94/NKG2 resulted in comparable killing of class I+ B cells. By contrast, another MoAb to class II had no effect on cytotoxicity. These data suggest that NK cell recognition of class I suppresses CR3/tyrosine kinase-dependent cytotoxicity in the same way as it suppresses cytotoxicity mediated by other tyrosine kinase-linked receptors such as FcgammaRIIIA (CD16).
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Affiliation(s)
- V Vĕtvicka
- Division of Experimental Immunology and Immunopathology, Department of Pathology, University of Louisville, KY, USA
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Abstract
To mimic the sandfly pool feeding process and characterize the cellular and biochemical events that occur during the early stages of promastigote-host interaction, we developed an ex vivo model of human blood infection with Leishmania promastigotes. Within 30 s of blood contact, Leishmania promastigotes bind natural anti-Leishmania antibodies, which then activate the classical complement pathway and opsonization by the third component of complement. The opsonized promastigotes undergo an immune adherence reaction and bind quantitatively to erythrocyte CR1 receptors; opsonized Leishmania amastigotes also bind to erythrocytes. Progression of infection implies promastigote transfer from erythrocytes to acceptor blood leukocytes. After 10 min of ex vivo infection, 25% of all leukocytes contain intracellular parasites, indicating that blood cells are the early targets for the invading promastigotes. We propose that adaptation to the immune adherence mechanism aids Leishmania survival, promoting rapid promastigote phagocytosis by leukocytes. This facilitates host colonization and may represent the parasite's earliest survival strategy. In light of this mechanism, it is unlikely that infection-blocking vaccines can be developed.
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Affiliation(s)
- M Domínguez
- Servicio de Inmunología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, E-28220 Madrid, Spain
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Ehlers MR. The role of complement receptor type 3 in the invasion strategies of Mycobacterium tuberculosis. ADVANCES IN CELLULAR AND MOLECULAR BIOLOGY OF MEMBRANES AND ORGANELLES 1999:81-105. [DOI: 10.1016/s1874-5172(99)80007-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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40
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Ehlers MR, Daffé M. Interactions between Mycobacterium tuberculosis and host cells: are mycobacterial sugars the key? Trends Microbiol 1998; 6:328-35. [PMID: 9746944 DOI: 10.1016/s0966-842x(98)01301-8] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mycobacterium tuberculosis has evolved successful strategies to invade and persist within macrophages. Intimate pathogen-macrophage contacts dictate receptor choice and probably specify the intracellular fate of these microorganisms. Binding to specific receptors, such as complement receptor type 3, could provide an advantage. These interactions appear to involve surface polysaccharides and glycolipids.
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Affiliation(s)
- M R Ehlers
- BioNebraska Inc., Lincoln, NE 68524, USA.
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41
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Affiliation(s)
- J D Ernst
- Department of Medicine, University of California, San Francisco, 94143-0868, USA.
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Cinco M, Murgia R, Presani G, Perticarari S. Integrin CR3 mediates the binding of nonspecifically opsonized Borrelia burgdorferi to human phagocytes and mammalian cells. Infect Immun 1997; 65:4784-9. [PMID: 9353065 PMCID: PMC175686 DOI: 10.1128/iai.65.11.4784-4789.1997] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Like other pathogens, the spirochete Borrelia burgdorferi, the agent of Lyme disease, possesses multiple pathways for cell binding; adhesion to phagocytic cells is of particular interest since it reportedly occurs even in the absence of specific antibodies. This study sets out to investigate how B. burgdorferi binds to human polymorphonuclear leukocytes (PMNs) when an exogenous complement is added and how the CR3 complement receptor, known as Mac-1 or alpha(m)beta2 integrin, is involved in the binding process. Experiments performed on PMNs and CHO Mac-1-expressing cells demonstrate that binding is inhibited by monoclonal anti-iC3b site antibodies, fibrinogen, and N-acetyl-D-glucosamine. These findings, which are not present with non-Mac-transfected CHO cells, indicate that the integrin alpha(m)beta2 acts as a receptor for spirochetes in nonimmune phagocytosis; furthermore, binding occurs on different domains of the CD11b subunit, involving the iC3b site and the lectin domain. The interaction of B. burgdorferi with alpha(m)beta2 integrin adds a novel pathway to Borrelia-phagocyte binding; not only does this binding affect the early stages of phagocytosis, but also it can influence the effector intracellular mechanisms which are activated by the beta2 integrin, as are the cytotoxic mechanisms.
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Affiliation(s)
- M Cinco
- Dipartimento di Scienze Biomediche, Università di Trieste, Italy.
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Sutterwala FS, Noel GJ, Clynes R, Mosser DM. Selective suppression of interleukin-12 induction after macrophage receptor ligation. J Exp Med 1997; 185:1977-85. [PMID: 9166427 PMCID: PMC2196339 DOI: 10.1084/jem.185.11.1977] [Citation(s) in RCA: 261] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Interleukin (IL)-12 is a monocyte- and macrophage-derived cytokine that plays a crucial role in both the innate and the acquired immune response. In this study, we examined the effects that ligating specific macrophage receptors had on the induction of IL-12 by lipopolysaccharide (LPS). We report that ligation of the macrophage Fcgamma, complement, or scavenger receptors inhibited the induction of IL-12 by LPS. Both mRNA synthesis and protein secretion were diminished to near-undetectable levels following receptor ligation. Suppression was specific to IL-12 since IL-10 and tumor necrosis factor-alpha (TNF-alpha) production were not inhibited by ligating macrophage receptors. The results of several different experimental approaches suggest that IL-12 downregulation was due to extracellular calcium influxes that resulted from receptor ligation. First, preventing extracellular calcium influxes, by performing the assays in EGTA, abrogated FcgammaR-mediated IL-12(p40) mRNA suppression. Second, exposure of macrophages to the calcium ionophores, ionomycin or A23187, mimicked receptor ligation and inhibited IL-12(p40) mRNA induction by LPS. Finally, bone marrow-derived macrophages from FcR gamma chain-deficient mice, which fail to flux calcium after receptor ligation, failed to inhibit IL-12(p40) mRNA induction. These results indicate that the calcium influxes that occur as a result of receptor ligation are responsible for inhibiting the induction of IL-12 by LPS. Hence, the ligation of phagocytic receptors on macrophages can lead to a dramatic decrease in IL-12 induction. This downregulation may be a way of limiting proinflammatory responses of macrophages to extracellular pathogens, or suppressing the development of cell-mediated immunity to intracellular pathogens.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Calcium/metabolism
- Calcium/pharmacology
- Down-Regulation
- Egtazic Acid/pharmacology
- Haemophilus influenzae/immunology
- Interleukin-10/biosynthesis
- Interleukin-12/biosynthesis
- Interleukin-12/genetics
- Ionomycin/pharmacology
- Ligands
- Lipopolysaccharides/pharmacology
- Macrophages/immunology
- Macrophages/metabolism
- Membrane Proteins
- Mice
- Mice, Inbred Strains
- Mice, Transgenic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Complement/metabolism
- Receptors, IgG/metabolism
- Receptors, Immunologic/metabolism
- Receptors, Lipoprotein
- Receptors, Scavenger
- Scavenger Receptors, Class B
- Tumor Necrosis Factor-alpha/biosynthesis
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Affiliation(s)
- F S Sutterwala
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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44
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Brittingham A, Mosser DM. Exploitation of the complement system by Leishmania promastigotes. ACTA ACUST UNITED AC 1996; 12:444-7. [PMID: 15275279 DOI: 10.1016/0169-4758(96)10067-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complement has long been acknowledged as an important component of host defense to extracellular pathogens. David Mosser and Andrew Brittingham here describe how Leishmania spp, intracellular pathogens of mononuclear phagocytes, exploit the opsonic and chemotactic effects of complement to initiate infection in the mammalian host.
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Affiliation(s)
- A Brittingham
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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