201
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Renner B, Coleman K, Goldberg R, Amura C, Holland-Neidermyer A, Pierce K, Orth HN, Molina H, Ferreira VP, Cortes C, Pangburn MK, Holers VM, Thurman JM. The complement inhibitors Crry and factor H are critical for preventing autologous complement activation on renal tubular epithelial cells. THE JOURNAL OF IMMUNOLOGY 2010; 185:3086-94. [PMID: 20675597 DOI: 10.4049/jimmunol.1000111] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Congenital and acquired deficiencies of complement regulatory proteins are associated with pathologic complement activation in several renal diseases. To elucidate the mechanisms by which renal tubular epithelial cells (TECs) control the complement system, we examined the expression of complement regulatory proteins by the cells. We found that Crry is the only membrane-bound complement regulator expressed by murine TECs, and its expression is concentrated on the basolateral surface. Consistent with the polarized localization of Crry, less complement activation was observed when the basolateral surface of TECs was exposed to serum than when the apical surface was exposed. Furthermore, greater complement activation occurred when the basolateral surface of TECs from Crry(-/-)fB(-/-) mice was exposed to normal serum compared with TECs from wild-type mice. Complement activation on the apical and basolateral surfaces was also greater when factor H, an alternative pathway regulatory protein found in serum, was blocked from interacting with the cells. Finally, we injected Crry(-/-)fB(-/-) and Crry(+/+)fB(-/-) mice with purified factor B (an essential protein of the alternative pathway). Spontaneous complement activation was seen on the tubules of Crry(-/-)fB(-/-) mice after injection with factor B, and the mice developed acute tubular injury. These studies indicate that factor H and Crry regulate complement activation on the basolateral surface of TECs and that factor H regulates complement activation on the apical surface. However, congenital deficiency of Crry or reduced expression of the protein on the basolateral surface of injured cells permits spontaneous complement activation and tubular injury.
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Affiliation(s)
- Brandon Renner
- Department of Medicine, University of Colorado Denver School of Medicine, Denver, CO 80045, USA
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202
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Hajishengallis G. Complement and periodontitis. Biochem Pharmacol 2010; 80:1992-2001. [PMID: 20599785 DOI: 10.1016/j.bcp.2010.06.017] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2010] [Revised: 06/06/2010] [Accepted: 06/08/2010] [Indexed: 12/31/2022]
Abstract
Although the complement system is centrally involved in host defense, its overactivation or deregulation (e.g., due to inherent host genetic defects or due to pathogen subversion) may excessively amplify inflammation and contribute to immunopathology. Periodontitis is an oral infection-driven chronic inflammatory disease which exerts a systemic impact on health. This paper reviews evidence linking complement to periodontal inflammation and pathogenesis. Clinical and histological observations show a correlation between periodontal inflammatory activity and local complement activation. Certain genetic polymorphisms or deficiencies in specific complement components appear to predispose to increased susceptibility to periodontitis. Animal model studies and in vitro experiments indicate that periodontal bacteria can either inhibit or activate distinct components of the complement cascade. Porphyromonas gingivalis, a keystone species in periodontitis, subverts complement receptor 3 and C5a anaphylatoxin receptor signaling in ways that promote its adaptive fitness in the presence of non-productive inflammation. Overall, available evidence suggests that complement activation or subversion contributes to periodontal pathogenesis, although not all complement pathways or functions are necessarily destructive. Effective complement-targeted therapeutic intervention in periodontitis would require determining the precise roles of the various inductive or effector complement pathways. This information is essential as it may reveal which specific pathways need to be blocked to counteract microbial evasion and inflammatory pathology or, conversely, kept intact to promote host immunity.
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Affiliation(s)
- George Hajishengallis
- Department of Microbiology and Immunology, University of Louisville School of Dentistry, Loueisville, KY 40292, USA.
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203
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Dunkelberger JR, Song WC. Role and mechanism of action of complement in regulating T cell immunity. Mol Immunol 2010; 47:2176-86. [PMID: 20603023 DOI: 10.1016/j.molimm.2010.05.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Complement is a part of the innate immune system that contributes to first-line host defense. It is also implicated in a number of human inflammatory conditions and has attracted interest as a potential therapeutic target. Understanding the basic biology of complement and its mechanism(s) of action is imperative for developing complement-based treatments for infectious and autoimmune diseases. One of the exciting new developments in this regard is the revelation that complement plays an important role in T cell immunity. In this review, we highlight recent published studies implicating complement in models of CD4+ and CD8+ T cell immune responses, and discuss its potential mechanism(s) action in these processes. We also comment on issues that may impact data interpretation and draw attention to their consideration in future studies.
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Affiliation(s)
- Jason R Dunkelberger
- Institute for Translational Medicine and Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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204
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Tezel G, Yang X, Luo C, Kain AD, Powell DW, Kuehn MH, Kaplan HJ. Oxidative stress and the regulation of complement activation in human glaucoma. Invest Ophthalmol Vis Sci 2010; 51:5071-82. [PMID: 20484586 DOI: 10.1167/iovs.10-5289] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE As part of ongoing studies on proteomic alterations during glaucomatous neurodegeneration, this study focused on the complement system. METHODS Human retinal protein samples obtained from donor eyes with (n = 10) or without (n = 10) glaucoma were analyzed by a quantitative proteomic approach using mass spectrometry. Cellular localization of protein expression for different complement components and regulators were also determined by immunohistochemical analysis of an additional group of human donor eyes with glaucoma (n = 34) compared with age-matched control eyes without glaucoma (n = 20). In addition, to determine the regulation of complement factor H (CFH) by oxidative stress, in vitro experiments were performed using rat retinal cell cultures incubated in the presence and absence of an oxidant treatment. RESULTS Proteomic analysis detected the expression and differential regulation of several complement components in glaucomatous samples, which included proteins involved in the classical and the lectin pathways of complement activation. In addition, several complement regulatory proteins were detected in the human retinal proteome, and glaucomatous samples exhibited a trend toward downregulation of CFH expression. In vitro experiments revealed that oxidative stress, which was also prominently detectable in the glaucomatous human retinas, downregulated CFH expression in retinal cells. CONCLUSIONS These findings expand the current knowledge of complement activation by presenting new evidence in human glaucoma and support that despite important roles in tissue cleaning and healing, a potential deficiency in intrinsic regulation of complement activation, as is evident in the presence of oxidative stress, may lead to uncontrolled complement attack with neurodestructive consequences.
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Affiliation(s)
- Gülgün Tezel
- Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Louisville, Kentucky, USA.
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205
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Kadam AP, Sahu A. Identification of Complin, a novel complement inhibitor that targets complement proteins factor B and C2. THE JOURNAL OF IMMUNOLOGY 2010; 184:7116-24. [PMID: 20483772 DOI: 10.4049/jimmunol.1000200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complement factor B (fB) is a key constituent of the alternative pathway (AP). Its central role in causing inflammation and tissue injury through activation of the AP urges the need for its therapeutic targeting. In the current study, we have screened phage-displayed random peptide libraries against fB and identified a novel cyclic hendecapeptide that inhibits activation of fB and the AP. Structure-activity studies revealed that: 1) the cysteine-constrained structure of the peptide is essential for its activity; 2) Ile5, Arg6, Leu7, and Tyr8 contribute significantly to its inhibitory activity; and 3) retro-inverso modification of the peptide results in loss of its activity. Binding studies performed using surface plasmon resonance suggested that the peptide has two binding sites on fB, which are located on the Ba and Bb fragments. Studies on the mechanism of inhibition revealed that the peptide does not block the interaction of fB with the activated form of C3, thereby suggesting that the peptide inhibits fB activation primarily by inhibiting its cleavage by factor D. The peptide showed a weak effect on preformed C3 and C5 convertases. Like inhibition of fB cleavage, the peptide also inhibited C2 cleavage by activated C1s and activation of the classical as well as lectin pathways. Based on its inhibitory activities, we named the peptide Complin.
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Affiliation(s)
- Archana P Kadam
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, India
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206
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Kaikkonen MU, Maatta AI, Ylä-Herttuala S, Airenne KJ. Screening of complement inhibitors: shielded baculoviruses increase the safety and efficacy of gene delivery. Mol Ther 2010; 18:987-92. [PMID: 20179675 PMCID: PMC2890102 DOI: 10.1038/mt.2010.25] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
One of the major obstacles in the use of baculovirus vectors for in vivo gene transfer is the virus inactivation by serum complement. In this study, we investigated the effect of decay-accelerating factor (DAF), factor H (FH)-like protein-1 (FHL-1), C4b-binding protein (C4BP), and membrane cofactor protein (MCP) on protection of baculovirus vectors from the complement-mediated inactivation. Complement regulatory proteins were displayed on baculovirus surface as fusions to membrane anchor of the vesicular stomatitis virus-G (VSV-G) protein. This strategy resulted in abundant expression of recombinant proteins on the viral envelope while viral titers comparable to control virus were reached. The surface-modified vectors exhibited complement resistance in vitro, DAF showing the highest level of protection. Intraportal delivery of DAF-displaying baculovirus resulted in increased survival and enhanced gene expression in immunocompetent mice. Mice receiving DAF-displaying baculovirus also exhibited lower level of liver inflammation as evidenced by aspartate aminotransferase (AST). In line with this, macrophages treated with DAF baculovirus produced lower levels of inflammatory cytokines IL-1beta, IL-6, and IL-12p40 compared to control virus. These results suggest that DAF-display can protect the vector against complement inactivation but also reduce complement-mediated inflammation injury. In conclusion, complement shielded baculovirus vectors represent attractive tools for effective in vivo gene delivery.
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Affiliation(s)
- Minna U Kaikkonen
- Department of Biotechnology and Molecular Medicine, AI Virtanen Institute, University of Eastern Finland, Kuopio, Finland
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207
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Hajishengallis G, Lambris JD. Crosstalk pathways between Toll-like receptors and the complement system. Trends Immunol 2010; 31:154-63. [PMID: 20153254 DOI: 10.1016/j.it.2010.01.002] [Citation(s) in RCA: 203] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 01/09/2010] [Accepted: 01/14/2010] [Indexed: 02/08/2023]
Abstract
The Toll-like receptors (TLRs) and complement are key innate defense systems that are triggered rapidly upon infection. Although both systems have been investigated primarily as separate entities, an emerging body of evidence indicates extensive crosstalk between complement and TLR signaling pathways. Analysis of these data suggests that the complement-TLR interplay reinforces innate immunity or regulates excessive inflammation, through synergistic or antagonistic interactions, respectively. However, the facility of complement and TLRs for communication is exploited by certain pathogens as a means to modify the host response in ways that favor the persistence of the pathogens. Further elucidation of regulatory links between complement and TLRs is essential for understanding their complex roles in health and disease.
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Affiliation(s)
- George Hajishengallis
- University of Louisville School of Dentistry, Division of Oral Health and Systemic Disease, Louisville, KY, USA.
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208
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Complement disorders and hereditary angioedema. J Allergy Clin Immunol 2010; 125:S262-71. [DOI: 10.1016/j.jaci.2009.10.063] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 10/01/2009] [Accepted: 10/07/2009] [Indexed: 01/28/2023]
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209
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Acquisition of complement resistance through incorporation of CD55/decay-accelerating factor into viral particles bearing baculovirus GP64. J Virol 2010; 84:3210-9. [PMID: 20071581 DOI: 10.1128/jvi.02519-09] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A major obstacle to gene transduction by viral vectors is inactivation by human complement in vivo. One way to overcome this is to incorporate complement regulatory proteins, such as CD55/decay accelerating factor (DAF), into viral particles. Lentivirus vectors pseudotyped with the baculovirus envelope protein GP64 have been shown to acquire more potent resistance to serum inactivation and longer transgene expression than those pseudotyped with the vesicular stomatitis virus (VSV) envelope protein G. However, the molecular mechanisms underlying resistance to serum inactivation in pseudotype particles bearing the GP64 have not been precisely elucidated. In this study, we generated pseudotype and recombinant VSVs bearing the GP64. Recombinant VSVs generated in human cell lines exhibited the incorporation of human DAF in viral particles and were resistant to serum inactivation, whereas those generated in insect cells exhibited no incorporation of human DAF and were sensitive to complement inactivation. The GP64 and human DAF were detected on the detergent-resistant membrane and were coprecipitated by immunoprecipitation analysis. A pseudotype VSV bearing GP64 produced in human DAF knockdown cells reduced resistance to serum inactivation. In contrast, recombinant baculoviruses generated in insect cells expressing human DAF or carrying the human DAF gene exhibited resistance to complement inactivation. These results suggest that the incorporation of human DAF into viral particles by interacting with baculovirus GP64 is involved in the acquisition of resistance to serum inactivation.
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210
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Li B, Xi H, Diehl L, Lee WP, Sturgeon L, Chinn J, Deforge L, Kelley RF, Wiesmann C, van Lookeren Campagne M, Sidhu SS. Improving therapeutic efficacy of a complement receptor by structure-based affinity maturation. J Biol Chem 2010; 284:35605-11. [PMID: 19833734 DOI: 10.1074/jbc.m109.035170] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
CRIg is a recently discovered complement C3 receptor expressed on a subpopulation of tissue-resident macrophages. The extracellular IgV domain of CRIg (CRIg-ECD) holds considerable promise as a potential therapeutic because it selectively inhibits the alternative pathway of complement by binding to C3b and inhibiting proteolytic activation of C3 and C5. However, CRIg binds weakly to the convertase subunit C3b (K(D) = 1.1 microm), and thus a relatively high concentration of protein is required to reach nearly complete complement inhibition. To improve therapeutic efficacy while minimizing risk of immunogenicity, we devised a phage display strategy to evolve a high affinity CRIg-ECD variant with a minimal number of mutations. Using the crystal structure of CRIg in complex with C3b as a guide for library design, we isolated a CRIg-ECD double mutant (Q64R/M86Y, CRIg-v27) that showed increased binding affinity and improved complement inhibitory activity relative to CRIg-ECD. In a mouse model of arthritis, treatment with a Fc fusion of CRIg-v27 resulted in a significant reduction in clinical scores compared with treatment with an Fc fusion of CRIg-ECD. This study clearly illustrates how phage display technology and structural information can be combined to generate proteins with nearly natural sequences that act as potent complement inhibitors with greatly improved therapeutic efficacy.
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Affiliation(s)
- Bing Li
- Department of Antibody Engineering, South San Francisco, California 94080, USA
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211
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Abstract
The complement system is an essential component of innate immunity that has been more recently recognized as an unexpected player in various pathological states. These include age-related macular degeneration, atypical haemolytic uraemic syndrome, allergy, foetal loss, and axonal and myelin degradation after trauma. Its importance has also been recognized in physiological processes including haematopoietic stem cell homing to the bone marrow, liver regeneration and modulation of adaptive immune responses. Although the complement system has long been known to be involved in autoimmune and inflammatory diseases, few agents that target the complement system are currently approved for clinical use. However, renewed interest in modulating this system in various pathological conditions has emerged, and several agents are now in development.
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212
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Jongerius I, Puister M, Wu J, Ruyken M, van Strijp JAG, Rooijakkers SHM. Staphylococcal complement inhibitor modulates phagocyte responses by dimerization of convertases. THE JOURNAL OF IMMUNOLOGY 2009; 184:420-5. [PMID: 19949103 DOI: 10.4049/jimmunol.0902865] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The human pathogen Staphylococcus aureus produces several complement-evasion molecules that enable the bacterium to withstand the host immune response. The human-specific staphylococcal complement inhibitor (SCIN) blocks the central C3 convertase enzymes that trigger critical complement functions, such as C3b deposition, phagocytosis, and C5a generation. SCIN effectively blocks the conversion of C3 by alternative pathway C3 convertases (C3bBb), but also induces dimerization of these enzymes. In this study, we show that formation of dimeric convertases by SCIN is important for S. aureus immune evasion because it modulates complement recognition by phagocytic receptors. Dimeric, but not monomeric, SCIN convertases showed an impaired binding to complement receptor 1 and the complement receptor of the Ig superfamily. The dimerization site of SCIN is essential for its strong antiphagocytic properties. These studies provide critical insights into the unique immune-evasion strategies used by S. aureus.
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Affiliation(s)
- Ilse Jongerius
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
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213
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Tarakanova VL, Molleston JM, Goodwin M, Virgin HW. MHV68 complement regulatory protein facilitates MHV68 replication in primary macrophages in a complement independent manner. Virology 2009; 396:323-8. [PMID: 19910013 DOI: 10.1016/j.virol.2009.10.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 10/19/2009] [Indexed: 11/19/2022]
Abstract
Murine gammaherpesvirus-68 (MHV68) is genetically related to human Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus and provides a tractable model to study gammaherpesvirus-host interactions in vivo and in vitro. The MHV68-encoded v-RCA product inhibits murine complement activation and shares sequence homology with other virus and host regulators of complement activation. Here we show that v-RCA is required for efficient MHV68 replication in primary murine macrophages, but not in murine embryonic fibroblasts. v-RCA-deficient MHV68 mutant viruses display defects in viral DNA synthesis in infected macrophages. Importantly, attenuated growth of v-RCA mutant viruses is not rescued in macrophages lacking critical components of the complement system including C3, indicating that the macrophage-specific role of v-RCA in MHV68 replication is complement-independent. This contrasts with the situation in vivo in which attenuated neurovirulence of v-RCA mutant viruses is rescued in C3-deficient mice. This study shows a novel, complement independent cell-type-specific function of a gammaherpesvirus RCA protein.
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Affiliation(s)
- Vera L Tarakanova
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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214
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Lu X, Li Y, Simovic MO, Peckham R, Wang Y, Tsokos GC, Dalle Lucca JJ. Decay-accelerating factor attenuates C-reactive protein-potentiated tissue injury after mesenteric ischemia/reperfusion. J Surg Res 2009; 167:e103-15. [PMID: 20189588 DOI: 10.1016/j.jss.2009.10.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 09/14/2009] [Accepted: 10/14/2009] [Indexed: 11/16/2022]
Abstract
BACKGROUND C-reactive protein (CRP) is an acute pro-inflammatory mediator that has been demonstrated to enhance ischemia/reperfusion (IR) injury by virtue of activating the complement system. CRP is able to interact with complement proteins such as C1q, complement factor H, and C4b-binding protein. Since complement activation is central in the expression of tissue injury following IR, we have investigated the effects of human decay-accelerating factor (DAF), a complement inhibitor, on CRP-potentiated complement activation and tissue injury in mice subjected to mesenteric IR. MATERIALS AND METHODS Male C57B1/6 mice were allocated into eight groups: (1) Sham-operated group without IR injury; (2) CRP+Sham group; (3) IR group; (4) CRP+IR group; (5) DAF group; (6) CRP+DAF group; (7) IR+DAF group, and (8) CRP+IR+DAF group. Intestinal and lung injury, neutrophil infiltration, myeloperoxidase (MPO) expression, complement component deposition, and interleukin-6 (IL-6) production were assessed for each treatment group of mice. RESULTS We report that administration of DAF significantly attenuates the CRP-enhanced intestinal injury as well as remote lung damages following acute mesenteric IR in mice, while DAF inhibits complement activation, suppresses neutrophil infiltration, and reduces IL-6 production. CONCLUSIONS Our study suggests that inhibition complement activation with DAF may prove useful for the treatment of post-ischemic inflammatory injuries associated with an increased production of CRP.
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Affiliation(s)
- Xinyue Lu
- Division of Military Casualty Research, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
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215
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Abstract
The complement system is important for cellular integrity and tissue homeostasis. Complement activation mediates the removal of microorganisms and the clearance of modified self cells, such as apoptotic cells. Complement regulators control the spontaneously activated complement cascade and any disturbances in this delicate balance can result in damage to tissues and in autoimmune disease. Therefore, insights into the mechanisms of complement regulation are crucial for understanding disease pathology and for enabling the development of diagnostic tools and therapies for complement-associated diseases.
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Affiliation(s)
- Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Beutenbergstrasse 11a, Jena, Germany.
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216
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Mechanisms of avoidance of host immunity by Neisseria meningitidis and its effect on vaccine development. THE LANCET. INFECTIOUS DISEASES 2009; 9:418-27. [PMID: 19555901 DOI: 10.1016/s1473-3099(09)70132-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neisseria meningitidis remains an important cause of severe sepsis and meningitis worldwide. The bacterium is only found in human hosts, and so must continually coexist with the immune system. Consequently, N meningitidis uses multiple mechanisms to avoid being killed by antimicrobial proteins, phagocytes, and, crucially, the complement system. Much remains to be learnt about the strategies N meningitidis employs to evade aspects of immune killing, including mimicry of host molecules by bacterial structures such as capsule and lipopolysaccharide, which poses substantial problems for vaccine design. To date, available vaccines only protect individuals against subsets of meningococcal strains. However, two promising vaccines are currently being assessed in clinical trials and appear to offer good prospects for an effective means of protecting individuals against endemic serogroup B disease, which has proven to be a major challenge in vaccine research.
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217
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Upregulation of CD59: potential mechanism of accommodation in a large animal model. Transplantation 2009; 87:1308-17. [PMID: 19424030 DOI: 10.1097/tp.0b013e3181a19afc] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND Survival of ABO-mismatched kidneys with stable renal function despite the persistence of anti-ABO antibodies is called accommodation. The mechanism of accommodation is unclear, but may involve complement regulatory proteins such as CD59. The development of alpha-1,3-galactosyltransferase knock-out (GalT-KO) swine that produce anti-Gal antibodies provides a large animal model capable of determining the role of complement regulatory proteins in accommodation. METHODS ELISA and antibody fluorescence-activated cell sorting were used to examine the rate of anti-Gal antibody expression as a function of age. Major histocompatibility complex-matched kidneys were transplanted from Gal-positive MGH miniature swine to MGH GalT-KO swine with systemic immunosuppression. One recipient underwent adsorbtion of anti-Gal antibodies before transplantation. Graft survival, antibody, and complement deposition patterns and CD59 expression were determined. RESULTS Three animals rejected Gal-positive kidneys by humoral mechanisms. One animal with low titers of anti-Gal antibody displayed spontaneous accommodation and the animal that was treated with antibody adsorbtion also displayed accommodation. Rejected grafts had deposition of IgM, IgG, C3, and C5b-9 with low expression of CD59, whereas accommodated grafts had low deposition of C5b-9 and high expression of CD59. Retransplantation of one accommodated graft to a naïve GalT-KO animal confirmed that changes in the graft were responsible for the lack of C5b-9 deposition. CONCLUSION GalT-KO miniature swine produce anti-Gal antibodies and titers increase with age. These anti-Gal antibodies can cause rejection of major histocompatibility complex-matched kidneys unless accommodation occurs. CD59 up-regulation seems to be involved in the mechanism of accommodation by preventing the formation of the membrane attack complex (MAC) on the accommodated graft.
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218
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Gaines AR, Lee-Stroka H, Byrne K, Scott DE, Uhl L, Lazarus E, Stroncek DF. Investigation of whether the acute hemolysis associated with Rh(o)(D) immune globulin intravenous (human) administration for treatment of immune thrombocytopenic purpura is consistent with the acute hemolytic transfusion reaction model. Transfusion 2009; 49:1050-8. [PMID: 19220820 PMCID: PMC3418653 DOI: 10.1111/j.1537-2995.2008.02083.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Immune thrombocytopenic purpura and secondary thrombocytopenia patients treated with Rh(o)(D) immune globulin intravenous (human; anti-D IGIV) have experienced acute hemolysis, which is inconsistent with the typical presentation of extravascular hemolysis -- the presumed mechanism of action of anti-D IGIV. Although the mechanism of anti-D-IGIV-associated acute hemolysis has not been established, the onset, signs/symptoms, and complications appear consistent with the intravascular hemolysis of acute hemolytic transfusion reactions (AHTRs). In transfusion medicine, the red blood cell (RBC) antigen-antibody incompatibility(-ies) that precipitate AHTRs can be detected in vitro with compatibility testing. Under the premise that anti-D-IGIV-associated acute hemolysis results from RBC antigen-antibody-mediated complement activation, this study evaluated whether the incompatibility(-ies) could be detected in vitro with a hemolysin assay, which would support the AHTR model as the hemolytic mechanism. STUDY DESIGN AND METHODS Seven anti-D IGIV lots were tested to determine the RBC antibody identities in those lots, including four lots that had been implicated in acute hemolytic episodes. Hemolysin assays were performed that tested each of 73 RBC specimens against each lot, including the RBCs of one patient who had experienced acute hemolysis after anti-D IGIV administration. RESULTS Only two anti-D IGIV lots contained RBC antibodies beyond those expected. No hemolysis endpoint was observed in any of the hemolysin assays. CONCLUSION Although the findings did not support the AHTR model, the results are reported to contribute knowledge about the mechanism of anti-D-IGIV-associated acute hemolysis and to prompt continued investigation into cause(s), prediction, and prevention of this potentially serious adverse event.
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Affiliation(s)
- Ann Reed Gaines
- Office of Biostatistics and Epidemiology, Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20852, USA.
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219
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Halme J, Sachse M, Vogel H, Giese T, Klar E, Kirschfink M. Primary human hepatocytes are protected against complement by multiple regulators. Mol Immunol 2009; 46:2284-9. [PMID: 19446335 DOI: 10.1016/j.molimm.2009.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 04/01/2009] [Accepted: 04/07/2009] [Indexed: 10/20/2022]
Abstract
Inflammatory liver disorders are often associated with a potentially tissue damaging complement activation directly at the main site of complement protein synthesis. As hepatocytes may be the primary target of complement attack, we investigated the expression and protective capacity of soluble and membrane-bound complement regulatory proteins in primary human hepatocytes (PHH). Isolated PHHs were analyzed for their basal and cytokine-induced complement regulator expression by cytofluorometry, rtPCR, confocal laser microscopy and ELISA. Susceptibility to complement-mediated cell lysis was investigated with cytotoxicity tests. In contrast to previous reports, PHHs expressed CD46, CD55, CD59, soluble CD59 (sCD59) and factor H (fH), but not CD35. A low basal expression of CD55 was strongly enhanced by IFN-gamma, IL-1 beta and TNF-alpha. The expression of CD59 could be augmented by IL-1 beta, IL-6 and TNF-alpha but was suppressed by IFN-gamma. CD46 expression was not significantly altered. PHHs synthesized fH and sCD59 and fH was detected on PHH surface after exposure to IL-1 beta. Inhibition experiments revealed that CD59 was most effective in protecting PHHs from complement attack. These data clearly indicate that PHHs are protected by multiple complement regulatory proteins, which are controlled by proinflammatory cytokines. CD59 appears to be pivotal in protecting PHHs against complement-mediated lysis.
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Affiliation(s)
- Jarkko Halme
- Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany
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220
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Markiewski MM, Lambris JD. Is complement good or bad for cancer patients? A new perspective on an old dilemma. Trends Immunol 2009; 30:286-92. [PMID: 19428302 DOI: 10.1016/j.it.2009.04.002] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 04/03/2009] [Accepted: 04/07/2009] [Indexed: 11/18/2022]
Abstract
Several studies of human cancers have established that chronic and insidious inflammation promotes the process of carcinogenesis and exacerbates the growth of existing tumors. Conversely, acute inflammation seems to have the opposite effect. Recent discoveries indicate that this dualism in the role of inflammation in cancer is mirrored by the effects of the complement system on this disease process. Previous studies have suggested that complement proteins can contribute to the immune surveillance of malignant tumors. However, a very recent study has indicated that complement proteins can also promote tumor growth. Here, we describe our current understanding of the role of complement in tumor development and progression.
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Affiliation(s)
- Maciej M Markiewski
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, 19104, USA
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221
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Tomat S, Russo FP, Guido M, Kechagias G, Masier A, Calore C, De Silvestro G, Anegon I, Cozzi E, Calabrese F, Burra P. Study of the microcirculation in hDAF transgenic rat livers xenoperfused with human blood. Xenotransplantation 2009; 16:83-90. [PMID: 19392723 DOI: 10.1111/j.1399-3089.2009.00519.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The microcirculation was assessed in the livers of human decay accelerating factors (hDAF) and wild-type transgenic rats by fluorescent intravital microscopy, histology and histomorphology to determine the benefits of hDAF expression for the microcirculation of a rat liver xenograft perfused with human blood. METHODS Male hDAF transgenic rats (group A; n = 20) and wild-type Sprague-Dawley rats (group B; n = 20) were xenoperfused with human blood, while other male wild-type Sprague-Dawley rats (group C; n = 10) were perfused with allogeneic blood. Following plasma and leukocyte staining with fluorescein sodium, and platelet staining with rhodamine, the right lobe of the liver was assessed by intravital microscopy, counting the numbers of perfused sinusoids and leukocytes adhering to the endothelium per mm(2), and calculating the acinar perfusion index (Pi). The liver underwent histological assessment at the end of each experiment. Mean +/- SEM values were calculated and the Mann-Whitney U-test was used for statistical analysis. RESULTS The number of perfused sinusoids was higher in the group of hDAF rat livers (group A) and controls (group C) than in the group of non-transgenic rat livers perfused with human blood (group B) (P < 0.05), although only group C still had a significantly more perfused sinusoids than the other groups after 90 min of perfusion (P < 0.05). The acinar perfusion index was higher in groups A and C than in group B (P < 0.05); here again, only group C still had a significantly higher Pi than group B after 90 min of perfusion (P < 0.05). There was a massive accumulation of leukocytes that peaked after 5 min and persisted throughout the perfusion in all three groups. Histology showed portal and subendothelial hepatic vein hemorrhage, necrosis and inflammatory reaction, which were particularly evident in group B. CONCLUSION In our study, rat livers transgenic for hDAF were better protected against early tissue damage by perfusion with human blood, but this did not result in a longer xenograft survival.
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Affiliation(s)
- Silvia Tomat
- Department of Surgical and Gastroenterological Sciences, University of Padua, Via Giustiniani 2, VI piano Monoblocco, Padua, Italy
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Abstract
The complement system is one of the key players in the defence against infections. Its activation during the innate immune response leads to the generation of several proteins that contribute to the lysis and opsonization of microorganisms, regulate inflammatory reactions and bridge innate immunity with the subsequent adaptive immune response. Complement is also activated in overwhelming bacterial infections that lead to sepsis, and its protective functions play a role in this frequently lethal disorder. However, despite its role in protection, complement can also contribute to the development of severe complications that significantly worsen the prognosis of septic patients. Therefore, an understanding of the mechanisms involved in the activation of complement during sepsis is essential to our efforts to introduce rational therapies targeting complement to the treatment of patients suffering from this condition. This review presents a current view of the mechanisms involved in the activation of complement in sepsis, in the context of the multiple interactions between complement and other biological systems that are involved in the pathogenesis of this disorder.
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Affiliation(s)
- Maciej M Markiewski
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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223
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Airoldi L, Magagnotti C, Iannuzzi AR, Marelli C, Bagnati R, Pastorelli R, Colombi A, Santaguida S, Chiabrando C, Schiarea S, Fanelli R. Effects of cigarette smoking on the human urinary proteome. Biochem Biophys Res Commun 2009; 381:397-402. [DOI: 10.1016/j.bbrc.2009.02.055] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 02/12/2009] [Indexed: 11/29/2022]
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224
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Adenovirus activates complement by distinctly different mechanisms in vitro and in vivo: indirect complement activation by virions in vivo. J Virol 2009; 83:5648-58. [PMID: 19321608 DOI: 10.1128/jvi.00082-09] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Understanding innate immunity is key to improving the safety of adenovirus (Ad) vectors for systemic gene therapy. Ad has been shown to activate complement in vitro, but activation of complement after Ad injection in vivo has not been directly measured. Using complement protein C3a as a marker of complement activation, we show that types 2 and 5 human Ads cause rapid complement activation after intravenous injection in mice. Unexpectedly, the mechanisms in vivo were different than those in vitro. Antibodies were critical for the activation of complement by Ad in vitro, but antibodies were not required in vivo. The classical pathway was required in vitro, whereas complement activation in vivo involved both classical and nonclassical pathways as well as the reticuloendothelial system. Remarkably, the entry-deficient Ad mutant ts1 was completely unable to activate complement in vivo even though it was fully able to activate complement in vitro. This result demonstrates that the complement system senses intravenously injected Ad primarily by detecting the effects of Ad on cells rather than through direct interaction of complement with virions. Encouragingly, shielding Ad with polyethylene glycol was effective at reducing complement activation both in vitro and in vivo. In summary, intravenously injected Ad rapidly activates complement through multiple pathways, but these pathways are different than those identified by in vitro studies. In vitro studies are poorly predictive of in vivo mechanisms because Ad virions activate complement through indirect mechanisms in vivo.
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225
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Host complement regulatory protein CD59 is transported to the chlamydial inclusion by a Golgi apparatus-independent pathway. Infect Immun 2009; 77:1285-92. [PMID: 19168743 DOI: 10.1128/iai.01062-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Chlamydia is an obligate intracellular bacterium that grows and replicates inside a cytoplasmic inclusion. We report that a host protein, CD59, which regulates complement function at the surfaces of uninfected cells, can be detected at the membrane of the chlamydial inclusion. This localization to the inclusion membrane was specific for CD59 and not a general feature of other glycosylphosphatidylinositol (GPI)-anchored proteins or representative cell surface proteins. Using differential permeabilization studies, we showed that CD59 is localized to the luminal but not the cytoplasmic face of the inclusion membrane, consistent with membrane association via its GPI anchor. Furthermore, CD59 was present at the inclusion even when we prevented it from associating with membrane microdomains via the GPI anchor or when we inhibited general protein transport to the cell surface, indicating that a conventional Golgi apparatus-dependent trafficking mechanism was not involved. Based on these findings, we propose that selected host proteins are trafficked to the inclusion by a Golgi apparatus-independent pathway during a Chlamydia infection.
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226
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Complement-dependent T-cell lymphopenia caused by thymocyte deletion of the membrane complement regulator Crry. Blood 2009; 113:2684-94. [PMID: 19136662 DOI: 10.1182/blood-2008-05-157966] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although complement lysis is frequently used for the purification of lymphocyte subpopulations in vitro, how lymphocytes escape complement attack in vivo has not been clearly delineated. Here, we show that conditional gene targeting of a murine membrane complement regulator Crry on thymocytes led to complement-dependent peripheral T-cell lymphopenia. Notably, despite evidence of hypersensitivity to complement attack, Crry-deficient T cells escaped complement injury and developed normally in the thymus, because of low intrathymic complement activity. Crry-deficient T cells were eliminated in the periphery by a C3- and macrophage-mediated but C5-independent mechanism. Thus, Crry is essential for mature T-cell survival in the periphery but not for lymphogenesis in the thymus. The observation that the thymus is a complement-privileged site may have implications for complement-based antitumor therapies.
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227
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228
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McDonald CA, Yang JY, Marathe V, Yen TY, Macher BA. Combining results from lectin affinity chromatography and glycocapture approaches substantially improves the coverage of the glycoproteome. Mol Cell Proteomics 2008; 8:287-301. [PMID: 18923192 DOI: 10.1074/mcp.m800272-mcp200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Identification of glycosylated proteins, especially those in the plasma membrane, has the potential of defining diagnostic biomarkers and therapeutic targets as well as increasing our understanding of changes occurring in the glycoproteome during normal differentiation and disease processes. Although many cellular proteins are glycosylated they are rarely identified by mass spectrometric analysis (e.g. shotgun proteomics) of total cell lysates. Therefore, methods that specifically target glycoproteins are necessary to facilitate their isolation from total cell lysates prior to their identification by mass spectrometry-based analysis. To enrich for plasma membrane glycoproteins the methods must selectively target characteristics associated with proteins within this compartment. We demonstrate that the application of two methods, one that uses periodate to label glycoproteins of intact cells and a hydrazide resin to capture the labeled glycoproteins and another that targets glycoproteins with sialic acid residues using lectin affinity chromatography, in conjunction with liquid chromatography-tandem mass spectrometry is effective for plasma membrane glycoprotein identification. We demonstrate that this combination of methods dramatically increases coverage of the plasma membrane proteome (more than one-half of the membrane glycoproteins were identified by the two methods uniquely) and also results in the identification of a large number of secreted glycoproteins. Our approach avoids the need for subcellular fractionation and utilizes a simple detergent lysis step that effectively solubilizes membrane glycoproteins. The plasma membrane localization of a subset of proteins identified was validated, and the dynamics of their expression in HeLa cells was evaluated during the cell cycle. Results obtained from the cell cycle studies demonstrate that plasma membrane protein expression can change up to 4-fold as cells transit the cell cycle and demonstrate the need to consider such changes when carrying out quantitative proteomics comparison of cell lines.
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Affiliation(s)
- Claudia A McDonald
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USA
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229
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Rampersad R, Barton A, Sadovsky Y, Nelson DM. The C5b-9 membrane attack complex of complement activation localizes to villous trophoblast injury in vivo and modulates human trophoblast function in vitro. Placenta 2008; 29:855-61. [PMID: 18783824 DOI: 10.1016/j.placenta.2008.07.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2008] [Revised: 07/11/2008] [Accepted: 07/22/2008] [Indexed: 12/31/2022]
Abstract
The complement system plays an important role in normal human pregnancy. Uncontrolled activation of this system has been associated with many disease states. We tested the hypothesis that the C5b-9 membrane attack complex (MAC) localizes to sites of villous injury and modulates trophoblast function. Placental sections from pregnancies with no complications, intrauterine growth restriction, or preeclampsia were immunostained and the surface density for MAC and fibrin was determined by morphometric analysis. Primary cytotrophoblasts from term placentas were cultured in a FiO(2) of <1%, 8% and 20% with 10% human serum containing active MAC or heat-inactivated control serum. Immunofluorescent MAC binding to trophoblast was quantified, and the neoepitopes formed in cytokeratin 18 filaments and poly-ADP-ribose polymerase during apoptosis were used to measure cell death. Trophoblast differentiation was assessed by HCG secretion, formation of syncytia, and expression of syncytin. MAC localized to fibrin deposits in normal placentas, and especially in placentas from IUGR and preeclampsia. MAC binding to cytotrophoblasts was inversely proportional to FiO(2) and enhanced apoptosis. MAC increased markers of differentiation in cultures at 72h (medium HCG, syncytia and syncytin expression). Our findings demonstrate that MAC associates with fibrin deposits at sites of villous injury in vivo. Hypoxia also enhances MAC deposition in cultured trophoblasts and MAC alters trophoblast function in a phenotype specific manner.
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Affiliation(s)
- R Rampersad
- Department of Obstetrics and Gynecology, Washington University, 4566 Scott Avenue, Saint Louis, MO 63110, USA.
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230
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The Role of Complement in the Mechanism of Action of Rituximab for B‐Cell Lymphoma: Implications for Therapy. Oncologist 2008; 13:954-66. [DOI: 10.1634/theoncologist.2008-0089] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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231
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Identification of differentially expressed immune-relevant genes in Chinese soft-shelled turtle (Trionyx sinensis) infected with Aeromonas hydrophila. Vet Immunol Immunopathol 2008; 125:82-91. [DOI: 10.1016/j.vetimm.2008.05.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 05/08/2008] [Accepted: 05/08/2008] [Indexed: 12/18/2022]
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232
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Deficiency of decay-accelerating factor and complement receptor 1-related gene/protein y on murine platelets leads to complement-dependent clearance by the macrophage phagocytic receptor CRIg. Blood 2008; 112:1109-19. [PMID: 18524992 DOI: 10.1182/blood-2008-01-134304] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Complement activation on human platelets is known to cause platelet degranulation and activation. To evaluate how normal platelets escape complement attack in vivo, we studied the fate of murine platelets deficient in 2 membrane complement regulatory proteins using an adoptive transfer model. We show here that deficiency of either decay-accelerating factor (DAF) or complement receptor 1-related gene/protein y (Crry) on murine platelets was inconsequential, whereas DAF and Crry double deficiency led to rapid clearance of platelets from circulation in a complement- and macrophage-dependent manner. This finding contrasted with the observation on erythrocytes, where Crry deficiency alone resulted in complement susceptibility. Quantitative flow cytometry showed DAF and Crry were expressed at similar levels on platelets, whereas Crry expression was 3 times higher than DAF on erythrocytes. Antibody blocking or gene ablation of the newly identified complement receptor CRIg, but not complement receptor 3 (CR3), rescued DAF/Crry-deficient platelets from complement-dependent elimination. Surprisingly, deficiency of CRIg, CR3, and other known complement receptors failed to prevent Crry-deficient erythrocytes from complement-mediated clearance. These results show a critical but redundant role of DAF and Crry in platelet survival and suggest that complement-opsonized platelets and erythrocytes engage different complement receptors on tissue macrophages in vivo.
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233
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Ramo K, Cashman SM, Kumar-Singh R. Evaluation of adenovirus-delivered human CD59 as a potential therapy for AMD in a model of human membrane attack complex formation on murine RPE. Invest Ophthalmol Vis Sci 2008; 49:4126-36. [PMID: 18487376 DOI: 10.1167/iovs.08-2025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Complement-mediated damage to the retinal pigment epithelium (RPE), Bruch membrane, and choroid has been associated with pathogenesis in age-related macular degeneration (AMD). The terminal step of complement activation involves lysis of cells by the insertion of the membrane attack complex (MAC) in the plasma membrane. The hypothesis that local overexpression of human CD59 (hCD59) delivered by an adenovirus (Ad) vector to primary murine RPE cells in vitro, RPE in vivo, or cornea ex vivo protects those cells from human MAC deposition and lysis was tested. METHODS A humanized model of MAC deposition on murine cells and murine ocular tissues including RPE and cornea was developed to permit testing of human complement regulators in mice. A recombinant adenovirus-expressing hCD59 was generated, and this virus was injected into the subretinal space of adult mice. Subsequently, eyecups from these mice were exposed to human serum, and the levels of MAC deposition on the RPE were quantified. hCD59 was also expressed on murine cornea ex vivo and in murine hepatocytes, and primary RPE cells in vitro and levels of human MAC deposition and cell lysis were measured. RESULTS Adenovirus-mediated delivery of hCD59 to the RPE, cornea, or cells in culture protects those cells from human MAC deposition and MAC-mediated damage and vesiculation. CONCLUSIONS The humanized model of MAC deposition on murine ocular tissues allows testing of human complement regulators that may have potential in the treatment of AMD or other diseases associated with complement activation.
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Affiliation(s)
- Kasmir Ramo
- Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, USA
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234
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Cummings KL, Waggoner SN, Tacke R, Hahn YS. Role of complement in immune regulation and its exploitation by virus. Viral Immunol 2008; 20:505-24. [PMID: 18158725 DOI: 10.1089/vim.2007.0061] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Complement is activated during the early phase of viral infection and promotes destruction of virus particles as well as the initiation of inflammatory responses. Recently, complement and complement receptors have been reported to play an important role in the regulation of innate as well as adaptive immune responses during infection. The regulation of host immune responses by complement involves modulation of dendritic cell activity in addition to direct effects on T-cell function. Intriguingly, many viruses encode homologs of complement regulatory molecules or proteins that interact with complement receptors on antigen-presenting cells and lymphocytes. The evolution of viral mechanisms to alter complement function may augment pathogen persistence and limit immune-mediated tissue destruction. These observations suggest that complement may play an important role in both innate and adaptive immune responses to infection as well as virus-mediated modulation of host immunity.
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Affiliation(s)
- Kara L Cummings
- Beirne Carter Center for Immunology Research and Department of Microbiology, University of Virginia, Charlottesville, Virginia
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235
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Yin W, Ghebrehiwet B, Weksler B, Peerschke EIB. Regulated complement deposition on the surface of human endothelial cells: effect of tobacco smoke and shear stress. Thromb Res 2007; 122:221-8. [PMID: 18166221 DOI: 10.1016/j.thromres.2007.11.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 11/20/2007] [Accepted: 11/27/2007] [Indexed: 12/23/2022]
Abstract
Cigarette smoke and hemodynamic stress both contribute to vascular inflammation and associated atherosclerosis. We recently demonstrated direct activation of complement components C4 and C3 on human endothelial cells (EC). The present study was designed to explore complement activation on bone marrow microvascular endothelial cells (BMEC) and human umbilical vein endothelial cells (HUVEC) in response to endothelial cell injury by tobacco smoke extract, shear stress, or other known inflammatory and atherogenic mediators, lipopolysaccharide (LPS) and INF-gamma. Following treatment, confluent EC monolayers were exposed to plasma (60 min, 37 degrees C), and cell surface deposition of stable complement derivatives C4d, iC3b and SC5b-9 was measured in situ using an ELISA approach. Consistent with previous results, moderate levels of C4d, iC3b and SC5b-9 deposition were observed on native EC monolayers exposed to human plasma. Tobacco smoke and shear stress enhanced EC C4d deposition. In contrast, LPS and INF-gamma failed to affect EC mediated complement activation, despite evidence of EC activation illustrated by ICAM-1 expression. The combination of tobacco smoke and shear stress nearly doubled EC C4d expression. No increases in iC3b or SC5b-9 were noted, suggesting inhibition of classical and alternative pathway C3 convertase assembly or activity. Indeed, concomitantly increased surface expression of complement regulatory proteins CD35 (CR1) and CD55 was observed following EC exposure to tobacco smoke and shear stress. These results suggest that a balance between complement activation and regulation exists at the EC surface, and may impact vascular injury leading to thrombosis, arteriosclerosis, and atherogenesis.
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Affiliation(s)
- Wei Yin
- Department of Pathology and Laboratory of Medicine, Weill Medical College of Cornell University, New York, New York, USA
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236
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Molecular cloning and expression of channel catfish, Ictalurus punctatus, complement membrane attack complex inhibitor CD59. Vet Immunol Immunopathol 2007; 120:246-53. [DOI: 10.1016/j.vetimm.2007.07.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 07/11/2007] [Accepted: 07/17/2007] [Indexed: 11/23/2022]
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237
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Activator-specific requirement of properdin in the initiation and amplification of the alternative pathway complement. Blood 2007; 111:732-40. [PMID: 17916747 DOI: 10.1182/blood-2007-05-089821] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Properdin is a positive regulator of alternative pathway (AP) complement. The current understanding of properdin function is that it facilitates AP complement activation by stabilizing the C3 convertase C3bBb. Properdin-deficient patients are susceptible to lethal meningococcal infection, but the mechanism of this selective predisposition is not fully understood. By gene targeting in the mouse, we show here that properdin is essential for AP complement activation induced by bacterial lipopolysacharride (LPS) and lipooligosacharride (LOS) and other, but not all, AP complement activators. LPS- and LOS-induced AP complement activation was abolished in properdin-/- mouse serum, and properdin-/- mice were unable to clear Crry-deficient erythrocytes, which are known to be susceptible to AP complement-mediated extravascular hemolysis. In contrast, zymosan- and cobra venom factor-induced AP complement activation, and classical pathway-triggered AP complement amplification were only partially or minimally affected in properdin-/- mice. We further show that the ability of human properdin to restore LPS-dependent AP complement activity in properdin-/- mouse serum correlated with the human properdin-binding affinity of the LPS. These results reveal a novel role of properdin in AP complement initiation and have implications for understanding the selective predisposition of properdin-deficient patients to meningococcal infection.
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238
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Wang L, Halliday D, Johnson PM, Christmas SE. Expression of complement regulatory proteins on human natural killer cell subsets. Immunol Lett 2007; 112:104-9. [PMID: 17719652 DOI: 10.1016/j.imlet.2007.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 07/10/2007] [Accepted: 07/12/2007] [Indexed: 02/07/2023]
Abstract
The cell surface complement regulatory (CReg) proteins CD46, CD55 and CD59 are widely distributed on human leucocytes and protect against complement-mediated damage. To investigate heterogeneity in CReg protein expression by human natural killer (NK) cells, levels were assessed on resting and activated NK cell subsets identified phenotypically on the basis of expression of CD56 and CD158 markers. Levels of all three CReg proteins on CD56+ cells were lower than on T cells (p<0.05). Freshly isolated CD56(bright) cells expressed higher levels of CD55 than CD56dim cells (p<0.05). CD158a+ cells expressed significantly lower levels of both CD46 and CD59, and CD158e+ cells expressed significantly lower levels of CD46, than CD158a(-) CD158e(-) cells, respectively (both p<0.05). Stimulation with PHA did not significantly alter NK cell surface CReg protein levels whereas, following culture with IL-2, CD46 and CD59 were decreased on both CD56bright and CD56dim subsets (p<0.05). In the case of CD59, this was independent of T cells. Only CD46 was significantly downregulated on CD158b+ (GL183+) and CD158e (NKB1+) subsets (p<0.05). However, culture in IL-15 significantly increased levels of all three CReg proteins. These observations that CReg proteins are downregulated on certain NK cell subsets following activation with IL-2 are opposite to previous findings for other leucocyte subpopulations. Activated NK cells may instead use other strategies for protection against complement-mediated damage in a local inflammatory response.
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Affiliation(s)
- Lin Wang
- Division of Immunology, School of Infection and Host Defence, University of Liverpool, Liverpool, UK
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239
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Zipfel PF, Mihlan M, Skerka C. The alternative pathway of complement: a pattern recognition system. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 598:80-92. [PMID: 17892206 DOI: 10.1007/978-0-387-71767-8_7] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute for Natural Products Research, Jena, Germany.
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240
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Tan CD, Baldwin WM, Rodriguez ER. Update on cardiac transplantation pathology. Arch Pathol Lab Med 2007; 131:1169-91. [PMID: 17683180 DOI: 10.5858/2007-131-1169-uoctp] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2006] [Indexed: 11/06/2022]
Abstract
CONTEXT The endomyocardial biopsy is the mainstay for monitoring acute allograft rejection in heart transplantation. Objective and accurate assessment of cellular and humoral types of rejection is important to optimize immunosuppressive therapy, avoid therapeutic complications, and improve patient outcome. The grading system for evaluation of heart transplant biopsies published in 1990 was revised in 2004 after more than a decade of implementation. OBJECTIVE In this review, we focus on a practical approach to the evaluation of human heart transplant biopsies as diagnostic surgical pathologic specimens. We discuss the revised International Society of Heart and Lung Transplantation working formulation. DATA SOURCES We reviewed pertinent literature, incorporating ideas and vast experience of participants in various work groups that led to the revision of the 1990 grading system. CONCLUSIONS The grading system for cellular rejection is presented with detailed light microscopic morphology and comparison of the 1990 and 2004 International Society of Heart and Lung Transplantation working formulations. We show how the pathologic recognition of cellular rejection and antibody-mediated rejection has evolved. We emphasize the interpretation of immunostains for complement components C4d and C3d in the diagnosis of antibody-mediated rejection. Evidence of regulation of complement activation in human heart transplant biopsies is presented in this context. We also discuss the pitfalls, caveats, and artifacts in the interpretation of allograft endomyocardial biopsies. Lastly, we discuss the pathology of human cardiac allograft vasculopathy in practical detail.
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Affiliation(s)
- Carmela D Tan
- Department of Anatomic Pathology, The Cleveland Clinic, Cleveland, OH 44195, USA
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241
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Hepburn NJ, Chamberlain-Banoub JL, Williams AS, Morgan BP, Harris CL. Prevention of experimental autoimmune myasthenia gravis by rat Crry-Ig: A model agent for long-term complement inhibition in vivo. Mol Immunol 2007; 45:395-405. [PMID: 17651804 PMCID: PMC2572221 DOI: 10.1016/j.molimm.2007.06.144] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 06/06/2007] [Accepted: 06/07/2007] [Indexed: 11/25/2022]
Abstract
Despite its vital role in innate immunity, complement is involved in a number of inflammatory pathologies and has therefore become a therapeutic target. Most agents generated for anti-complement therapy have short half-lives in plasma, or have been of mouse or human origin, thereby limiting their use either to murine models of disease or to short-term therapy. Here we describe the generation of a long-acting rat therapeutic agent based on the rat complement inhibitor, Crry. Characterisation of various soluble forms of Crry demonstrated that the amino-terminal four short-consensus repeat domains were required for full regulatory and C3b-binding activities. Fusion of these domains to rat IgG2a Fc generated an effective complement inhibitor (rCrry-Ig) with a circulating half-life prolonged from 7 min for Crry alone to 53 h for rCrry-Ig. Systemic administration of rCrry-Ig over 5 weeks generated a weak immune response to the recombinant agent, however this was predominantly IgM in nature and did not neutralise Crry function or cause clearance of the agent from plasma. Administration of rCrry-Ig completely abrogated clinical disease in a rat model of myasthenia gravis whereas soluble Crry lacking the immunoglobulin Fc domain caused a partial response. rCrry-Ig not only ablated clinical disease, but also prevented C3 and C9 deposition at the neuromuscular junction and inhibited cellular infiltration at this site. The long half-life and low immunogenicity of this agent will be useful for therapy in chronic models of inflammatory disease in the rat.
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MESH Headings
- Animals
- Antigens, Surface/blood
- Antigens, Surface/immunology
- Antigens, Surface/isolation & purification
- Antigens, Surface/pharmacology
- Complement C3b/immunology
- Complement Inactivator Proteins/pharmacology
- Complement System Proteins/immunology
- Female
- Half-Life
- Immunoglobulin G/pharmacology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/pathology
- Myasthenia Gravis, Autoimmune, Experimental/prevention & control
- Neuromuscular Junction/drug effects
- Neuromuscular Junction/pathology
- Rats
- Rats, Wistar
- Receptors, Cell Surface/blood
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/isolation & purification
- Recombinant Proteins/biosynthesis
- Recombinant Proteins/blood
- Recombinant Proteins/isolation & purification
- Recombinant Proteins/pharmacology
- Solubility/drug effects
- Surface Plasmon Resonance
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Affiliation(s)
- Natalie J. Hepburn
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Jayne L. Chamberlain-Banoub
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Anwen S. Williams
- Department of Rheumatology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - B. Paul Morgan
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Claire L. Harris
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
- Corresponding author. Tel.: +44 2920745254; fax: +44 2920744001.
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242
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Weeks C, Moratz C, Zacharia A, Stracener C, Egan R, Peckham R, Moore FD, Tsokos GC. Decay-accelerating factor attenuates remote ischemia-reperfusion-initiated organ damage. Clin Immunol 2007; 124:311-27. [PMID: 17631050 DOI: 10.1016/j.clim.2007.05.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 05/04/2007] [Accepted: 05/08/2007] [Indexed: 01/28/2023]
Abstract
Complement activation contributes to the expression of local and remote organ injury in animal models of ischemia-reperfusion (IR). We demonstrate here that a soluble form of decay-accelerating factor (DAF) protects normal C57Bl/6 and autoimmunity-prone B6.MRL/lpr mice subjected to hindlimb IR from remote intestinal and lung injury without affecting the degree of local skeletal muscle injury. In addition, DAF treatment attenuates remote organ injury in mice subjected to mesenteric IR. Soluble DAF allowed the deposition of complement 3 in local and remote injury sites while it limited the presence of terminal membrane attack complex and did not increase animal susceptibility to sepsis. These data provide evidence that soluble DAF might offer clinical benefit to patients suffering remote intestinal or lung damage in response to muscle or other organ injury.
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Affiliation(s)
- Christine Weeks
- Department of Surgery, Brigham and Women's Hospital, Boston, MA 02115, USA
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243
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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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244
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Liu G, Zhang J, Chen X. Molecular and functional characterization of a CD59 analogue from large yellow croaker Pseudosciana crocea. Mol Immunol 2007; 44:3661-71. [PMID: 17531319 DOI: 10.1016/j.molimm.2007.04.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 04/02/2007] [Accepted: 04/06/2007] [Indexed: 10/23/2022]
Abstract
CD59 is a widely distributed membrane-bound inhibitor of the cytolytic membrane attack complex (MAC) of complement. Here, the cDNA of a CD59 analogue was cloned from large yellow croaker (Pseudosciana crocea), a marine fish (LycCD59), by expressed sequence tags (EST) and RACE techniques. The open reading frame (ORF) of 351 nucleotides (nt) of LycCD59 encodes a polypeptide of 117 amino acids (aa), which includes a putative 20-aa NH(2)-signal peptide and a 97-aa coding region with a putative GPI-anchoring site at Asn(71). The deduced LycCD59 protein shared the structural feature of mammalian CD59, including a conserved cysteine skeleton responsible for the formation of disulfide bonds, and a similar pattern of hydrophobic termini. RT-PCR analysis showed that LycCD59 mRNA was broadly expressed in various tissues examined, except for intestine. And Northern blot analysis revealed a single LycCD59 transcript of approximately 1.0kb. LycCD59 expression in blood, spleen, and kidney was significantly up-regulated during 24h of induction with poly(I:C) or inactivated trivalent bacterial vaccine as determined by a relative quantitative real-time PCR analysis, and a coordinated up-regulation of LycCD59 and complement C3 and C7 mRNA was also found in these three tissues post-induction although their up-regulation pattern and extent were somewhat different in various tissues with poly(I:C) or bacterial vaccine. The recombinant protein of LycCD59 produced in E. coli was shown to significantly inhibit the erythrocyte lysis of tilapia (Oreochromis niloticus) in an in vitro hemolytic system, which was mediated by serum from large yellow croaker and tilapia, respectively, but not from mouse and chicken, suggesting that LycCD59 has a species-selective inhibition of complement activation. These results represent the first functional identification of a CD59 analogue in teleost fish, strongly suggesting the presence of regulatory mechanism for terminal complement pathway in teleost fish.
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Affiliation(s)
- Guozhu Liu
- Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, 178 Daxue Road, Xiamen 361005, PR China
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245
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Abstract
The involvement of the immune system in the response to tissue injury has raised the possibility that it might influence tissue, organ or appendage regeneration following injury. One hypothesis that has been discussed is that inflammatory aspects may preclude the occurrence of regeneration, but there is also evidence for more positive roles of immune components. The vertebrate eye is an immunoprivileged site where inflammatory aspects are inhibited by several immunomodulatory mechanisms. In various newt species the ocular tissues such as the lens are regenerative and it has recently been shown that the response to local injury of the lens involves activation of antigen-presenting cells which traffic to the spleen and return to displace and engulf the lens, thereby inducing regeneration from the dorsal iris. The activation of thrombin from prothrombin in the dorsal iris is one aspect of the injury response that is important in the initiation of regeneration. The possible relationships between the immune response and the regenerative response are considered with respect to phylogenetic variation of regeneration in general, and lens regeneration in particular.
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Affiliation(s)
- James W Godwin
- Department of Biochemistry & Molecular Biology, University College London, UK
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246
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Miwa T, Maldonado MA, Zhou L, Yamada K, Gilkeson GS, Eisenberg RA, Song WC. Decay-accelerating factor ameliorates systemic autoimmune disease in MRL/lpr mice via both complement-dependent and -independent mechanisms. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:1258-66. [PMID: 17392165 PMCID: PMC1829459 DOI: 10.2353/ajpath.2007.060601] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Decay-accelerating factor (DAF) is a glycosylphosphatidylinositol-anchored membrane protein that restricts complement activation on autologous cells. Previous studies have established a significant protective activity of DAF in the MRL/lpr murine model of human systemic lupus erythematosus. To dissect the mechanism of protection by DAF in this disease model, we evaluated the effect of C3 gene ablation on disease development in MRL/lpr-Daf-1(-/-) mice. We found no significant difference in lymphadenopathy, splenomegaly, or anti-chromatin autoantibody titer between complement-sufficient and complement-deficient MRL/lpr-Daf-1(-/-) mice. On the other hand, complement deficiency strikingly reduced the incidence and severity of dermatitis in MRL/lpr-Daf-1(-/-) mice. To assess the contribution of DAF expression on lymphocytes versus local tissues in suppressing dermatitis, we generated BM chimeric mice between MRL/lpr-Daf-1(-/-) and MRL/lpr-Daf-1(+/+) mice. Compared with MRL/lpr-Daf-1(-/-) --> MRL/lpr-Daf-1(-/-) controls, MRL/lpr-Daf-1(-/-) --> MRL/lpr-Daf-1(+/+) chimeras developed significantly attenuated dermatitis, suggesting that the protective effect of DAF in suppressing dermatitis is primarily attributable to its local expression. We conclude that DAF works as a complement regulator in the skin to protect MRL/lpr mice from skin inflammation, whereas its inhibitory role in the induction phase of MRL/lpr autoimmunity is complement-independent. Together, these results reveal multiple mechanisms of action for DAF in ameliorating systemic autoimmunity.
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Affiliation(s)
- Takashi Miwa
- Institute for Translational Medicine and Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, 1254 BRBII/III, 421 Curie Blvd., Philadelphia, PA 19104, USA.
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247
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Zhang X, Kimura Y, Fang C, Zhou L, Sfyroera G, Lambris JD, Wetsel RA, Miwa T, Song WC. Regulation of Toll-like receptor-mediated inflammatory response by complement in vivo. Blood 2007; 110:228-36. [PMID: 17363730 PMCID: PMC1896115 DOI: 10.1182/blood-2006-12-063636] [Citation(s) in RCA: 272] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Toll-like receptors (TLRs) and complement are 2 components of innate immunity that are critical for first-line host defense and elicitation of adaptive immune responses. Many pathogen-associated molecular patterns activate both TLR and complement, but whether and how these 2 systems, when coactivated in vivo, interact with each other has not been well studied. We demonstrate here a widespread regulation of TLR signaling by complement in vivo. The TLR ligands lipopolysacharride (TLR4), zymosan (TLR2/6), and CpG oligonucleotide (TLR9) caused, in a complement-dependent manner, strikingly elevated plasma interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and IL-1beta, and/or decreased plasma IL-12 levels in mice deficient in the membrane complement inhibitor decay-accelerating factor (DAF). A similar outcome was observed in wild-type mice cotreated with the TLR ligands and cobra venom factor, a potent complement activator. The regulatory effect of complement on TLR-induced cytokine production in vivo was mediated by the anaphylatoxin receptors C5aR and C3aR. Additionally, changes in lipopolysaccharide (LPS)-induced cytokine production in DAF-deficient mice correlated with increased mitogen-activated protein kinase and nuclear factor-kappaB activation in the spleen. These results reveal a strong interaction between complement and TLR signaling in vivo and suggest a novel mechanism by which complement promotes inflammation and modulates adaptive immunity.
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Affiliation(s)
- Xinhua Zhang
- Institute for Translational Medicine and Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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248
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Abstract
Complement activation contributes to a pathological process in a number of autoimmune and inflammatory diseases, including rheumatoid arthritis (RA). In this review we summarize current knowledge of complement contribution to RA, based on clinical observations in patients and in vivo animal models, as well as on experiments in vitro aiming at elucidation of underlying molecular mechanisms. There is strong evidence that both the classical and the alternative pathways of complement are pathologically activated during RA as well as in animal models for RA. The classical pathway can be initiated by several triggers present in the inflamed joint such as deposited autoantibodies, dying cells, and exposed cartilage proteins such as fibromodulin. B cells producing autoantibodies, which in turn form immune complexes, contribute to RA pathogenesis partly via activation of complement. It appears that anaphylatoxin C5a is the main product of complement activation responsible for tissue damage in RA although deposition of membrane attack complex as well as opsonization with fragments of C3b are also important. Success of complement inhibition in the experimental models described so far encourages novel therapeutic approaches to the treatment of human RA.
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Affiliation(s)
- Marcin Okroj
- Lund University, Department of Laboratory Medicine, University Hospital Malmö, Malmö, Sweden
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249
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Kemper C, Atkinson JP. T-cell regulation: with complements from innate immunity. Nat Rev Immunol 2006; 7:9-18. [PMID: 17170757 DOI: 10.1038/nri1994] [Citation(s) in RCA: 264] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The complement system was traditionally known as an effector arm of humoral immunity. Today we also recognize it as a main element of the innate immune system. In blood and other body fluids complement is a first line of defence against pathogens, because it becomes fully active within seconds. Active complement fragments attach to the invading pathogen to promote opsonization and lysis, triggering a local inflammatory response. This Review focuses on the evolving role of the complement system in the regulation of T-cell responses, from directing the initiation phase, through driving lineage commitment, to regulating the contraction phase.
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Affiliation(s)
- Claudia Kemper
- Washington University School of Medicine, Department of Internal Medicine, Division of Rheumatology, Campus Box 8045, 660 South Euclid Avenue, Saint Louis, Missouri 63110, USA
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250
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Pedersen ED, Frøyland E, Kvissel AK, Pharo AM, Skålhegg BS, Rootwelt T, Mollnes TE. Expression of complement regulators and receptors on human NT2-N neurons--effect of hypoxia and reoxygenation. Mol Immunol 2006; 44:2459-68. [PMID: 17116331 DOI: 10.1016/j.molimm.2006.10.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 10/10/2006] [Indexed: 11/23/2022]
Abstract
Complement activation can cause tissue damage in cerebral stroke by the release of biologically potent activation products and impaired function of regulatory proteins. We investigated the constitutive and hypoxia-reoxygenation-dependent expression of complement receptor 1 (CD35), membrane cofactor protein (CD46), decay-accelerating factor (CD55), protectin (CD59), and complement C3a and C5a receptors (C3aR and C5aR) on human NT2-N neurons. The effect of hypoxia-reoxygenation on C3d-deposition on neurons and endothelial cells was also investigated. NT2-N neurons were examined by cellular enzyme-linked immunosorbent assay and immunofluorescence microscopy. Endothelial cells were examined by flow cytometry. Three hours 1% or 0.1% hypoxia and 21h reoxygenation with 50% AB-serum were used to investigate the effect of hypoxia-reoxygenation on regulators and C3d-deposition. NT2-N neurons expressed significant amounts of CD59 (Clone H19/Clone BRIC229: p=0.000006/p=0.000003), CD46 (p=0.00006), CD55 (p=0.003) and C3aR (p=0.00003). CD35 and C5aR were not significantly expressed. There were no effects of hypoxia-reoxygenation on any of the regulators or receptors after 1% hypoxia and reoxygenation. However, CD55 (p=0.02) was down-regulated after 0.1% hypoxia and subsequent reoxygenation with AB-serum. There were no difference observed in the C3d-deposition during hypoxia-reoxygenation in either neurons or endothelial cells. In conclusion, human NT2-N neurons constitutively express C3aR, CD46, CD55 and, in particular, CD59. The cells may respond to locally produced C3a and, at the same time, be well protected against complement attack. Although severe hypoxia-reoxygenation may down-regulate CD55 expression, it does not seem to influence C3d-deposition.
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Affiliation(s)
- Elena D Pedersen
- Institute of Immunology, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, N-0027 Oslo, Norway.
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