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Sultan EY, Rizk DE, Kenawy HI, Hassan R. A small fragment of factor B as a potential inhibitor of complement alternative pathway activity. Immunobiology 2021; 226:152106. [PMID: 34147816 DOI: 10.1016/j.imbio.2021.152106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/06/2021] [Accepted: 06/08/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND The complement system is a key player in innate immunity and a modulator of the adaptive immune system. Among the three pathways of complement, the alternative pathway (AP) accounts for most of the complement activation. Factor B (FB) is a major protease of the AP, making it a promising target to inhibit the AP activity in conditions of uncontrolled complement activation. METHODS Based on the data obtained from sequence analysis and conformational changes associated with FB, we expressed and purified a recombinant FB fragment (FBfr). We tested the inhibitory activity of the protein against the AP by in vitro assays. RESULTS FBfr protein was proven to inhibit the complement AP activity when tested by C3b deposition assay and rabbit erythrocyte hemolytic assay. CONCLUSION Our recombinant FBfr was able to compete with the native human FB, which allowed it to inhibit the AP activity. This novel compound is a good candidate for further characterization and testing to be used in complement diagnostic tests and as a drug lead in the field of complement therapeutics.
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Affiliation(s)
- Enas Yasser Sultan
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt
| | - Dina Eid Rizk
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt
| | - Hany Ibrahim Kenawy
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt.
| | - Ramadan Hassan
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt
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2
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Kumar NA, Kunnakkadan U, Thomas S, Johnson JB. In the Crosshairs: RNA Viruses OR Complement? Front Immunol 2020; 11:573583. [PMID: 33133089 PMCID: PMC7550403 DOI: 10.3389/fimmu.2020.573583] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/24/2020] [Indexed: 12/02/2022] Open
Abstract
Complement, a part of the innate arm of the immune system, is integral to the frontline defense of the host against innumerable pathogens, which includes RNA viruses. Among the major groups of viruses, RNA viruses contribute significantly to the global mortality and morbidity index associated with viral infection. Despite multiple routes of entry adopted by these viruses, facing complement is inevitable. The initial interaction with complement and the nature of this interaction play an important role in determining host resistance versus susceptibility to the viral infection. Many RNA viruses are potent activators of complement, often resulting in virus neutralization. Yet, another facet of virus-induced activation is the exacerbation in pathogenesis contributing to the overall morbidity. The severity in disease and death associated with RNA virus infections shows a tip in the scale favoring viruses. Growing evidence suggest that like their DNA counterparts, RNA viruses have co-evolved to master ingenious strategies to remarkably restrict complement. Modulation of host genes involved in antiviral responses contributed prominently to the adoption of unique strategies to keep complement at bay, which included either down regulation of activation components (C3, C4) or up regulation of complement regulatory proteins. All this hints at a possible “hijacking” of the cross-talk mechanism of the host immune system. Enveloped RNA viruses have a selective advantage of not only modulating the host responses but also recruiting membrane-associated regulators of complement activation (RCAs). This review aims to highlight the significant progress in the understanding of RNA virus–complement interactions.
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Affiliation(s)
- Nisha Asok Kumar
- Viral Disease Biology, Department of Pathogen Biology, Rajiv Gandhi Center for Biotechnology, Thiruvananthapuram, India.,Manipal Academy of Higher Education, Manipal, India
| | - Umerali Kunnakkadan
- Viral Disease Biology, Department of Pathogen Biology, Rajiv Gandhi Center for Biotechnology, Thiruvananthapuram, India.,Department of Biotechnology, University of Kerala, Thiruvananthapuram, India
| | - Sabu Thomas
- Cholera and Biofilm Research Lab, Department of Pathogen Biology, Rajiv Gandhi Center for Biotechnology, Thiruvananthapuram, India
| | - John Bernet Johnson
- Viral Disease Biology, Department of Pathogen Biology, Rajiv Gandhi Center for Biotechnology, Thiruvananthapuram, India
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3
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Giang NT, van Tong H, Quyet D, Hoan NX, Nghia TH, Nam NM, Hung HV, Anh DT, Van Mao C, Son HA, Meyer CG, Velavan TP, Toan NL. Complement protein levels and MBL2 polymorphisms are associated with dengue and disease severity. Sci Rep 2020; 10:14923. [PMID: 32913345 PMCID: PMC7484760 DOI: 10.1038/s41598-020-71947-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023] Open
Abstract
The complement system may be crucial during dengue virus infection and progression to severe dengue. This study investigates the role of MBL2 genetic variants and levels of MBL in serum and complement proteins in Vietnamese dengue patients. MBL2 genotypes (- 550L/H, MBL2 codon 54), MBL2 diplotypes (XA/XO, YA/XO) and MBL2 haplotypes (LXPB, HXPA, XO) were associated with dengue in the study population. The levels of complement factors C2, C5, and C5a were higher in dengue and dengue with warning signs (DWS) patients compared to those in healthy controls, while factor D levels were decreased in dengue and DWS patients compared to the levels determined in healthy controls. C2 and C5a levels were associated with the levels of AST and ALT and with WBC counts. C9 levels were negatively correlated with ALT levels and WBC counts, and factor D levels were associated with AST and ALT levels and with platelet counts. In conclusions, MBL2 polymorphisms are associated with dengue in the Vietnamese study population. The levels of the complement proteins C2, C4b, C5, C5a, C9, factor D and factor I are modulated in dengue patients during the clinical course of dengue.
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Affiliation(s)
- Ngo Truong Giang
- Department of Pathophysiology, Vietnam Military Medical University, 160 Phung Hung, Ha Dong, Hanoi, Vietnam.,Department of Biology and Medical Genetics, Vietnam Military Medical University, Hanoi, Vietnam
| | - Hoang van Tong
- Department of Pathophysiology, Vietnam Military Medical University, 160 Phung Hung, Ha Dong, Hanoi, Vietnam. .,Institute of Biomedicine and Pharmacy, Vietnam Military Medical University, 222 Phung Hung, Ha Dong, Hanoi, Vietnam.
| | - Do Quyet
- Institute of Biomedicine and Pharmacy, Vietnam Military Medical University, 222 Phung Hung, Ha Dong, Hanoi, Vietnam
| | - Nghiem Xuan Hoan
- 108 Military Central Hospital, Hanoi, Vietnam.,Vietnamese-German Center for Medical Research, VG-CARE, Hanoi, Vietnam
| | - Trinh Huu Nghia
- 103 Military Hospital, Vietnam Military Medical University, Hanoi, Vietnam
| | - Nguyen Minh Nam
- 103 Military Hospital, Vietnam Military Medical University, Hanoi, Vietnam
| | - Hoang Vu Hung
- 103 Military Hospital, Vietnam Military Medical University, Hanoi, Vietnam
| | - Do Tuan Anh
- 103 Military Hospital, Vietnam Military Medical University, Hanoi, Vietnam
| | - Can Van Mao
- Department of Pathophysiology, Vietnam Military Medical University, 160 Phung Hung, Ha Dong, Hanoi, Vietnam
| | - Ho Anh Son
- Department of Pathophysiology, Vietnam Military Medical University, 160 Phung Hung, Ha Dong, Hanoi, Vietnam.,Institute of Biomedicine and Pharmacy, Vietnam Military Medical University, 222 Phung Hung, Ha Dong, Hanoi, Vietnam
| | - Christian G Meyer
- Vietnamese-German Center for Medical Research, VG-CARE, Hanoi, Vietnam.,Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,Duy Tan University, Faculty of Medicine, Da Nang, Vietnam
| | - Thirumalaisamy P Velavan
- Vietnamese-German Center for Medical Research, VG-CARE, Hanoi, Vietnam.,Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,Duy Tan University, Faculty of Medicine, Da Nang, Vietnam
| | - Nguyen Linh Toan
- Department of Pathophysiology, Vietnam Military Medical University, 160 Phung Hung, Ha Dong, Hanoi, Vietnam.
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4
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Dobó J, Kocsis A, Gál P. Be on Target: Strategies of Targeting Alternative and Lectin Pathway Components in Complement-Mediated Diseases. Front Immunol 2018; 9:1851. [PMID: 30135690 PMCID: PMC6092519 DOI: 10.3389/fimmu.2018.01851] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/26/2018] [Indexed: 12/20/2022] Open
Abstract
The complement system has moved into the focus of drug development efforts in the last decade, since its inappropriate or uncontrolled activation has been recognized in many diseases. Some of them are primarily complement-mediated rare diseases, such as paroxysmal nocturnal hemoglobinuria, C3 glomerulonephritis, and atypical hemolytic uremic syndrome. Complement also plays a role in various multifactorial diseases that affect millions of people worldwide, such as ischemia reperfusion injury (myocardial infarction, stroke), age-related macular degeneration, and several neurodegenerative disorders. In this review, we summarize the potential advantages of targeting various complement proteins with special emphasis on the components of the lectin (LP) and the alternative pathways (AP). The serine proteases (MASP-1/2/3, factor D, factor B), which are responsible for the activation of the cascade, are straightforward targets of inhibition, but the pattern recognition molecules (mannose-binding lectin, other collectins, and ficolins), the regulatory components (factor H, factor I, properdin), and C3 are also subjects of drug development. Recent discoveries about cross-talks between the LP and AP offer new approaches for clinical intervention. Mannan-binding lectin-associated serine proteases (MASPs) are not just responsible for LP activation, but they are also indispensable for efficient AP activation. Activated MASP-3 has recently been shown to be the enzyme that continuously supplies factor D (FD) for the AP by cleaving pro-factor D (pro-FD). In this aspect, MASP-3 emerges as a novel feasible target for the regulation of AP activity. MASP-1 was shown to be required for AP activity on various surfaces, first of all on LPS of Gram-negative bacteria.
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Affiliation(s)
- József Dobó
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Andrea Kocsis
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Péter Gál
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
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5
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Iyer A, Xu W, Reid RC, Fairlie DP. Chemical Approaches to Modulating Complement-Mediated Diseases. J Med Chem 2017; 61:3253-3276. [DOI: 10.1021/acs.jmedchem.7b00882] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Abishek Iyer
- Centre for Inflammation and Disease Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Weijun Xu
- ARC Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert C. Reid
- ARC Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David P. Fairlie
- Centre for Inflammation and Disease Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
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6
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Menaldo DL, Bernardes CP, Jacob-Ferreira AL, Nogueira-Santos CG, Casare-Ogasawara TM, Pereira-Crott LS, Sampaio SV. Effects of Bothrops atrox venom and two isolated toxins on the human complement system: Modulation of pathways and generation of anaphylatoxins. Mol Immunol 2016; 80:91-100. [DOI: 10.1016/j.molimm.2016.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/18/2016] [Accepted: 10/25/2016] [Indexed: 10/20/2022]
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7
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Foley JH. Examining coagulation-complement crosstalk: complement activation and thrombosis. Thromb Res 2016; 141 Suppl 2:S50-4. [DOI: 10.1016/s0049-3848(16)30365-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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8
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Kouser L, Abdul-Aziz M, Tsolaki AG, Singhal D, Schwaeble WJ, Urban BC, Khan HA, Sim RB, Kishore U. A recombinant two-module form of human properdin is an inhibitor of the complement alternative pathway. Mol Immunol 2016; 73:76-87. [PMID: 27060503 DOI: 10.1016/j.molimm.2016.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/04/2016] [Accepted: 03/07/2016] [Indexed: 02/08/2023]
Abstract
Properdin upregulates the alternative complement pathway by binding and stabilising the C3 convertase complex (C3bBb). Properdin is a soluble glycoprotein and its flexible rod-like 53kDa monomers form cyclic polymers (dimers, trimers, tetramers and pentamers). The properdin monomer consists of seven thrombospondin type I repeats (TSR 0-6), which are similar and homologous to domains found in circumsporozoite and thrombospondin-related anonymous proteins of Plasmodium species, ETP100 of Eimeria tenella, various complement components C6-C9, and thrombospondin I and II. Using deletion constructs, TSR4 and TSR5 of human properdin were implicated in C3b binding and stabilising C3 convertase. However, individually expressed TSR4 or TSR5 failed to bind properdin ligands. Here, we have expressed and characterized biologically active TSR4 and TSR5 together (TSR4+5) in tandem in Escherichia coli, fused to maltose-binding protein. MBP-TSR4+5 bind solid-phase C3b, sulfatides and glycosaminoglycans. In addition, functionally active recombinant TSR4+5 modules inhibit the alternative pathway of complement.
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Affiliation(s)
- Lubna Kouser
- Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | - Munirah Abdul-Aziz
- Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Anthony G Tsolaki
- Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | - Dipti Singhal
- Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | - Wilhelm J Schwaeble
- Department of Infection, Immunity and Inflammation, Maurice Shock Medical Sciences Building, University Road, Leicester, LE1 9HN, UK
| | - Britta C Urban
- Liverpool School of Tropical Medicine, Pembroke Place Liverpool, L3 5QA, UK
| | - Haseeb A Khan
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Robert B Sim
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK; Department of Infection, Immunity and Inflammation, Maurice Shock Medical Sciences Building, University Road, Leicester, LE1 9HN, UK
| | - Uday Kishore
- Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK.
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9
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Kouser L, Abdul-Aziz M, Nayak A, Stover CM, Sim RB, Kishore U. Properdin and factor h: opposing players on the alternative complement pathway "see-saw". Front Immunol 2013; 4:93. [PMID: 23630525 PMCID: PMC3632793 DOI: 10.3389/fimmu.2013.00093] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/05/2013] [Indexed: 12/16/2022] Open
Abstract
Properdin and factor H are two key regulatory proteins having opposite functions in the alternative complement pathway. Properdin up-regulates the alternative pathway by stabilizing the C3bBb complex, whereas factor H downregulates the pathway by promoting proteolytic degradation of C3b. While factor H is mainly produced in the liver, there are several extrahepatic sources. In addition to the liver, factor H is also synthesized in fetal tubuli, keratinocytes, skin fibroblasts, ocular tissue, adipose tissue, brain, lungs, heart, spleen, pancreas, kidney, muscle, and placenta. Neutrophils are the major source of properdin, and it is also produced by monocytes, T cells and bone marrow progenitor cell line. Properdin is released by neutrophils from intracellular stores following stimulation by N-formyl-methionine-leucine-phenylalanine (fMLP) and tumor necrosis factor alpha (TNF-α). The HEP G2 cells derived from human liver has been found to produce functional properdin. Endothelial cells also produce properdin when induced by shear stress, thus is a physiological source for plasma properdin. The diverse range of extrahepatic sites for synthesis of these two complement regulators suggests the importance and need for local availability of the proteins. Here, we discuss the significance of the local synthesis of properdin and factor H. This assumes greater importance in view of recently identified unexpected and novel roles of properdin and factor H that are potentially independent of their involvement in complement regulation.
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Affiliation(s)
- Lubna Kouser
- Centre for Infection, Immunity and Disease Mechanisms, Biosciences, School of Health Sciences and Social Care, Brunel University London, UK
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10
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Gęca A, Gola J, Dudek S, Jasik K, Muc-Wierzgoń M, Nowakowska-Zajdel E, Niedworok E, Mazurek U. Expression of Genes Associated with H Factor in Fibroblasts Infected with Borrelia Spirochaetes. Scand J Immunol 2012; 76:354-8. [DOI: 10.1111/j.1365-3083.2012.02741.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Microbe-specific C3b deposition in the horseshoe crab complement system in a C2/factor B-dependent or -independent manner. PLoS One 2012; 7:e36783. [PMID: 22611464 PMCID: PMC3351276 DOI: 10.1371/journal.pone.0036783] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/09/2012] [Indexed: 02/07/2023] Open
Abstract
Complement C3 plays an essential role in the opsonization of pathogens in the mammalian complement system, whereas the molecular mechanism underlying C3 activation in invertebrates remains unknown. To understand the molecular mechanism of C3b deposition on microbes, we characterized two types of C2/factor B homologs (designated TtC2/Bf-1 and TtC2/Bf-2) identified from the horseshoe crab Tachypleus tridentatus. Although the domain architectures of TtC2/Bf-1 and TtC2/Bf-2 were identical to those of mammalian homologs, they contained five-repeated and seven-repeated complement control protein domains at their N-terminal regions, respectively. TtC2/Bf-1 and TtC2/Bf-2 were synthesized and glycosylated in hemocytes and secreted to hemolymph plasma, which existed in a complex with C3 (TtC3), and their activation by microbes was absolutely Mg2+-dependent. Flow cytometric analysis revealed that TtC3b deposition was Mg2+-dependent on Gram-positive bacteria or fungi, but not on Gram-negative bacteria. Moreover, this analysis demonstrated that Ca2+-dependent lectins (C-reactive protein-1 and tachylectin-5A) were required for TtC3b deposition on Gram-positive bacteria, and that a Ca2+-independent lectin (Tachypleus plasma lectin-1) was definitely indispensable for TtC3b deposition on fungi. In contrast, a horseshoe crab lipopolysaccharide-sensitive protease factor C was necessary and sufficient to deposit TtC3b on Gram-negative bacteria. We conclude that plasma lectins and factor C play key roles in microbe-specific TtC3b deposition in a C2/factor B-dependent or -independent manner.
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12
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Sun QY, Bao J. Purification, cloning and characterization of a metalloproteinase from Naja atra venom. Toxicon 2010; 56:1459-69. [DOI: 10.1016/j.toxicon.2010.08.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 08/30/2010] [Accepted: 08/31/2010] [Indexed: 11/28/2022]
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13
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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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14
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Ruiz-Gómez G, Lim J, Halili MA, Le GT, Madala PK, Abbenante G, Fairlie DP. Structure-activity relationships for substrate-based inhibitors of human complement factor B. J Med Chem 2009; 52:6042-52. [PMID: 19743866 DOI: 10.1021/jm900781m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human complement is a cascading network of plasma proteins important in immune defense, cooperatively effecting recognition, opsonization, destruction, and removal of pathogens and infected/damaged cells. Overstimulated or unregulated complement activation can result in immunoinflammatory diseases. Key serine proteases in this cascade are difficult to study due to their multiprotein composition, short lifetimes, formation on membranes, or serum circulation as inactive zymogens. Factor B is inactive at pH 7, but a catalytically active serine protease under alkaline conditions, enabling structure-activity relationship studies for 63 substrate-based peptide inhibitors with 4-7 residues and a C-terminal aldehyde. A potent factor B inhibitor was hexpeptide Ac-RLTbaLAR-H (IC(50) 250 nM, pH 9.5), which at pH 7 also blocked formation of membrane attack complex via the "alternative pathway" of complement activation and inhibited human complement mediated lysis of rabbit erythrocytes. Inhibitors of factor B may be valuable probes and drug leads for complement mediated immunity and disease.
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Affiliation(s)
- Gloria Ruiz-Gómez
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
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15
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Qu H, Ricklin D, Lambris JD. Recent developments in low molecular weight complement inhibitors. Mol Immunol 2009; 47:185-95. [PMID: 19800693 DOI: 10.1016/j.molimm.2009.08.032] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 08/28/2009] [Indexed: 11/18/2022]
Abstract
As a key part of the innate immune system, complement plays an important role not only in defending against invading pathogens but also in many other biological processes. Inappropriate or excessive activation of complement has been linked to many autoimmune, inflammatory, and neurodegenerative diseases, as well as ischemia-reperfusion injury and cancer. A wide array of low molecular weight complement inhibitors has been developed to target various components of the complement cascade. Their efficacy has been demonstrated in numerous in vitro and in vivo experiments. Though none of these inhibitors has reached the market so far, some of them have entered clinical trials and displayed promising results. This review provides a brief overview of the currently developed low molecular weight complement inhibitors, including short peptides and synthetic small molecules, with an emphasis on those targeting components C1 and C3, and the anaphylatoxin receptors.
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Affiliation(s)
- Hongchang Qu
- Department of Pathology and Laboratory Medicine, School of Medicine, University of Pennsylvania, 401 Stellar Chance, 422 Curie Blvd., Philadelphia, PA 19104, USA
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16
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Halili MA, Ruiz-Gómez G, Le GT, Abbenante G, Fairlie DP. Complement component C2, inhibiting a latent serine protease in the classical pathway of complement activation. Biochemistry 2009; 48:8466-72. [PMID: 19642650 DOI: 10.1021/bi900679r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The innate immune response to infection or injury involves an antigen-antibody triggered classical pathway (CP) of complement activation, in which soluble and cell surface plasma proteins cooperatively effect elimination of foreign organisms and damaged host cells. However, protracted or dysfunctional complement activation can lead to inflammatory diseases. Complement component 2 bound to C4b is cleaved by classical (C1s) or lectin (MASP2) proteases to produce C4bC2a, a very short-lived C3 convertase (t(1/2) 2 min) that in turn cleaves C3 to C3a and C3b, leading ultimately to formation of Membrane Attack Complex (MAC) and lysis of bacteria and damaged cells. C2 has the same serine protease domain as C4bC2a but in an inactive zymogen-like conformation, requiring cofactor-induced conformational change for activity. Here, we show that C2 has catalytic protease activity in its own right above pH 7, in the absence of cofactor, processing C3 and C3-derived chromogenic peptide fragments. In contrast to the instability of C3 convertase (t(1/2) 2 min, pH 7), the C2 enzyme is indefinitely stable under alkaline conditions, facilitating studies of its catalytic properties and development of small molecule inhibitors. We characterize the catalytic activity of C2 against C3 and short paranitroanilide peptide substrates, and identify potent small molecule inhibitors of C2 that also inhibit classical pathway C3 convertase, MAC formation, and hemolysis of sensitized sheep erythrocytes. These results provide a new avenue and valuable new insights to inhibiting CP complement activation relevant to inflammatory diseases.
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Affiliation(s)
- Maria A Halili
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld 4072, Australia
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17
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Park JY, Mun JH, Lee BH, Heo SH, Kim GH, Yoo HW. Proteomic analysis of sera of asymptomatic, early-stage patients with Wilson's disease. Proteomics Clin Appl 2009; 3:1185-1190. [PMID: 20556197 PMCID: PMC2883077 DOI: 10.1002/prca.200800057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Revised: 06/11/2009] [Accepted: 06/16/2009] [Indexed: 01/22/2023]
Abstract
Wilson's disease (WD) is characterized by excessive accumulation of intracellular copper in liver and extrahepatic tissues, leading to significant oxidative stress and tissue damage. To date, several diagnostic biomarkers for WD such as serum ceruloplasmin, serum or urine copper levels and copper content in liver have been identified. However, these biomarkers may not be convincing for the diagnosis in some WD patients. To identify additional novel diagnostic biomarkers, we compared the serum protein profiles of asymptomatic childhood WD patients (n=20), without neurologic manifestation or liver cirrhosis, with normal controls (n=13). Fourteen spots, five up-regulated and nine down-regulated (>2-fold), were differentially expressed in WD patients in comparison to normal control on 2-DE. Among them, three spots were down-regulated in both male and female WD. MS/MS analysis revealed that the three spots were complement component C3, complement factor B and alpha-2 macroglobulin. By comparative proteome analysis, complement component C3, complement factor B and alpha-2 macroglobulin, which are related to oxidative stress and inflammation, turned out to be good candidates for novel diagnostic biomarkers for early stages of WD.
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Affiliation(s)
- Jung-Young Park
- Genome Research Center for Birth Defects and Genetic Diseases, Asan Institute for Life Sciences Seoul, Korea
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Wei W, Wu H, Xu H, Xu T, Zhang X, Chang K, Zhang Y. Cloning and molecular characterization of two complement Bf/C2 genes in large yellow croaker (Pseudosciaena crocea). FISH & SHELLFISH IMMUNOLOGY 2009; 27:285-295. [PMID: 19490942 DOI: 10.1016/j.fsi.2009.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 05/20/2009] [Accepted: 05/24/2009] [Indexed: 05/27/2023]
Abstract
Complement components factor B and C2 are two crucial proteases in the alternative pathway (AP) and classical pathway (CP). Two Bf/C2 cDNAs, LycBf/C2A and LycBf/C2B were isolated from the large yellow croaker (Pseudosciaena crocea) by suppression subtractive hybridization (SSH) and rapid amplification of cDNA ends (RACE). Through sequence alignment and computer 3D modeling analysis, we found that both of the deduced proteins contain three complement control protein (CCP) modules, a von Willebrand factor A (vWFA) domain, and one serine protease (SP) domain. Both structural analysis and phylogenetic analyses suggested that LycBf/C2A is more like human factor B than human C2 while LycBf/C2B is more human C2-like. After that, RT-PCR assay showed that LycBf/C2A and LycBf/C2B were mostly expressed in liver, albeit detectable in other tissues. Finally, after being infected with attenuated live Vibrio anguillarum strain, the expression level of LycBf/C2A and LycBf/C2B were found remarkably up-regulated in liver, spleen and kidney, indicating that the two complement factors play a pivotal role in the immune response to bacterial challenge in large yellow croaker.
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Affiliation(s)
- Wei Wei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
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