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Poddar NK, Khan A, Fatima F, Saxena A, Ghaley G, Khan S. Association of mTOR Pathway and Conformational Alterations in C-Reactive Protein in Neurodegenerative Diseases and Infections. Cell Mol Neurobiol 2023; 43:3815-3832. [PMID: 37665407 DOI: 10.1007/s10571-023-01402-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/15/2023] [Indexed: 09/05/2023]
Abstract
Inflammatory biomarkers have been very useful in detecting and monitoring inflammatory processes along with providing helpful information to select appropriate therapeutic strategies. C-reactive protein (CRP) is a nonspecific, but quite useful medical acute inflammatory biomarker and is associated with persistent chronic inflammatory processes. Several studies suggest that different levels of CRP are correlated with neurological disorders such as Alzheimer's disease (AD). However, dynamics of CRP levels have also been observed in virus/bacterial-related infections leading to inflammatory responses and this triggers mTOR-mediated pathways for neurodegeneration diseases. The biophysical structural transition from CRP to monomeric CRP (mCRP) and the significance of the ratio of CRP levels on the onset of symptoms associated with inflammatory response have been discussed. In addition, mTOR inhibitors act as immunomodulators by downregulating the expression of viral infection and can be explored as a potential therapy for neurological diseases.
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Affiliation(s)
- Nitesh Kumar Poddar
- Department of Biosciences, Manipal University Jaipur, Jaipur-Ajmer Express Highway, Dehmi Kalan, Near GVK Toll Plaza, Jaipur, Rajasthan, India, 303007.
| | - Arshma Khan
- Department of Biotechnology, Invertis University, Bareilly, Uttar Pradesh, India, 243123
| | - Falak Fatima
- Amity Institute of Biotechnology, Amity University, Uttar Pradesh, Noida, India, 201301
| | - Anshulika Saxena
- Department of Biosciences, Manipal University Jaipur, Jaipur-Ajmer Express Highway, Dehmi Kalan, Near GVK Toll Plaza, Jaipur, Rajasthan, India, 303007
| | - Garima Ghaley
- Department of Biosciences, Manipal University Jaipur, Jaipur-Ajmer Express Highway, Dehmi Kalan, Near GVK Toll Plaza, Jaipur, Rajasthan, India, 303007
| | - Shahanavaj Khan
- Department of Medical Lab Technology, Indian Institute of Health and Technology (IIHT), Deoband, Saharanpur, Uttar Pradesh, India, 247554.
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Lv JM, Huang XP, Chen JY, Cheng B, Chen WZ, Yuan P, Wu F, Li HY. Cholesterol-binding sequence is a key regulatory motif of cellular folding and conformational activation for C-reactive protein. Mol Immunol 2022; 152:123-128. [DOI: 10.1016/j.molimm.2022.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/13/2022] [Accepted: 10/23/2022] [Indexed: 11/06/2022]
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Noone DP, van der Velden TT, Sharp TH. Cryo-Electron Microscopy and Biochemical Analysis Offer Insights Into the Effects of Acidic pH, Such as Occur During Acidosis, on the Complement Binding Properties of C-Reactive Protein. Front Immunol 2022; 12:757633. [PMID: 34975846 PMCID: PMC8716467 DOI: 10.3389/fimmu.2021.757633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 11/22/2021] [Indexed: 11/15/2022] Open
Abstract
The pentraxin family of proteins includes C-reactive protein (CRP), a canonical marker for the acute phase inflammatory response. As compared to normal physiological conditions in human serum, under conditions associated with damage and inflammation, such as acidosis and the oxidative burst, CRP exhibits modulated biochemical properties that may have a structural basis. Here, we explore how pH and ligand binding affect the structure and biochemical properties of CRP. Cryo-electron microscopy was used to solve structures of CRP at pH 7.5 or pH 5 and in the presence or absence of the ligand phosphocholine (PCh), which yielded 7 new high-resolution structures of CRP, including pentameric and decameric complexes. Structures previously derived from crystallography were imperfect pentagons, as shown by the variable angles between each subunit, whereas pentameric CRP derived from cryoEM was found to have C5 symmetry, with subunits forming a regular pentagon with equal angles. This discrepancy indicates flexibility at the interfaces of monomers that may relate to activation of the complement system by the C1 complex. CRP also appears to readily decamerise in solution into dimers of pentamers, which obscures the postulated binding sites for C1. Subtle structural rearrangements were observed between the conditions tested, including a putative change in histidine protonation that may prime the disulphide bridges for reduction and enhanced ability to activate the immune system. Enzyme-linked immunosorbent assays showed that CRP had markedly increased association to the C1 complex and immunoglobulins under conditions associated with acidosis, whilst a reduction in the Ca2+ concentration lowered this pH-sensitivity for C1q, but not immunoglobulins, suggesting different modes of binding. These data suggest a model whereby a change in the ionic nature of CRP and immunological proteins can make it more adhesive to potential ligands without large structural rearrangements.
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Affiliation(s)
- Dylan P Noone
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Tijn T van der Velden
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
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Labarrere CA, Kassab GS. Pattern Recognition Proteins: First Line of Defense Against Coronaviruses. Front Immunol 2021; 12:652252. [PMID: 34630377 PMCID: PMC8494786 DOI: 10.3389/fimmu.2021.652252] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 08/31/2021] [Indexed: 01/08/2023] Open
Abstract
The rapid outbreak of COVID-19 caused by the novel coronavirus SARS-CoV-2 in Wuhan, China, has become a worldwide pandemic affecting almost 204 million people and causing more than 4.3 million deaths as of August 11 2021. This pandemic has placed a substantial burden on the global healthcare system and the global economy. Availability of novel prophylactic and therapeutic approaches are crucially needed to prevent development of severe disease leading to major complications both acutely and chronically. The success in fighting this virus results from three main achievements: (a) Direct killing of the SARS-CoV-2 virus; (b) Development of a specific vaccine, and (c) Enhancement of the host's immune system. A fundamental necessity to win the battle against the virus involves a better understanding of the host's innate and adaptive immune response to the virus. Although the role of the adaptive immune response is directly involved in the generation of a vaccine, the role of innate immunity on RNA viruses in general, and coronaviruses in particular, is mostly unknown. In this review, we will consider the structure of RNA viruses, mainly coronaviruses, and their capacity to affect the lungs and the cardiovascular system. We will also consider the effects of the pattern recognition protein (PRP) trident composed by (a) Surfactant proteins A and D, mannose-binding lectin (MBL) and complement component 1q (C1q), (b) C-reactive protein, and (c) Innate and adaptive IgM antibodies, upon clearance of viral particles and apoptotic cells in lungs and atherosclerotic lesions. We emphasize on the role of pattern recognition protein immune therapies as a combination treatment to prevent development of severe respiratory syndrome and to reduce pulmonary and cardiovascular complications in patients with SARS-CoV-2 and summarize the need of a combined therapeutic approach that takes into account all aspects of immunity against SARS-CoV-2 virus and COVID-19 disease to allow mankind to beat this pandemic killer.
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Affiliation(s)
| | - Ghassan S Kassab
- California Medical Innovations Institute, San Diego, CA, United States
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5
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Li HY, Tang ZM, Wang Z, Lv JM, Liu XL, Liang YL, Cheng B, Gao N, Ji SR, Wu Y. C-Reactive Protein Protects Against Acetaminophen-Induced Liver Injury by Preventing Complement Overactivation. Cell Mol Gastroenterol Hepatol 2021; 13:289-307. [PMID: 34536564 PMCID: PMC8599171 DOI: 10.1016/j.jcmgh.2021.09.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 12/10/2022]
Abstract
BACKGROUND AND AIMS C-reactive protein (CRP) is a hepatocyte-produced marker of inflammation yet with undefined function in liver injury. We aimed to examine the role of CRP in acetaminophen-induced liver injury (AILI). METHODS The effects of CRP in AILI were investigated using CRP knockout mice and rats combined with human CRP rescue. The mechanisms of CRP action were investigated in vitro and in mice with Fcγ receptor 2B knockout, C3 knockout, or hepatic expression of CRP mutants defective in complement interaction. The therapeutic potential of CRP was investigated by intraperitoneal administration at 2 or 6 hours post-AILI induction in wild-type mice. RESULTS CRP knockout exacerbated AILI in mice and rats, which could be rescued by genetic knock-in, adeno-associated virus-mediated hepatic expression or direct administration of human CRP. Mechanistically, CRP does not act via its cellular receptor Fcγ receptor 2B to inhibit the early phase injury to hepatocytes induced by acetaminophen; instead, CRP acts via factor H to inhibit complement overactivation on already injured hepatocytes, thereby suppressing the late phase amplification of inflammation likely mediated by C3a-dependent actions of neutrophils. Importantly, CRP treatment effectively alleviated AILI with a significantly extended therapeutic time window than that of N-acetyl cysteine. CONCLUSION Our results thus identify CRP as a crucial checkpoint that limits destructive activation of complement in acute liver injury, and we argue that long-term suppression of CRP expression or function might increase the susceptibility to AILI.
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Affiliation(s)
- Hai-Yun Li
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Zhao-Ming Tang
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Zhe Wang
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Jian-Min Lv
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Xiao-Ling Liu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, P.R. China
| | - Yu-Lin Liang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, P.R. China
| | - Bin Cheng
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, P.R. China
| | - Ning Gao
- Department of Infectious Disease, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Shang-Rong Ji
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, P.R. China,Shang-Rong Ji, PhD, MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, P.R. China. fax: 86-931-8914102.
| | - Yi Wu
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, P.R. China,Key Laboratory of Precision Medicine to Pediatric Diseases of Shaanxi Province, Xi’an Children’s Hospital, Xi'an Jiaotong University, Xi'an, P.R. China,Correspondence Address correspondence to: Yi Wu, PhD, MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an 710061, P.R. China. fax: 86-029-82657013.
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6
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Ngwa DN, Singh SK, Gang TB, Agrawal A. Treatment of Pneumococcal Infection by Using Engineered Human C-Reactive Protein in a Mouse Model. Front Immunol 2020; 11:586669. [PMID: 33117400 PMCID: PMC7575696 DOI: 10.3389/fimmu.2020.586669] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/11/2020] [Indexed: 12/22/2022] Open
Abstract
C-reactive protein (CRP) binds to several species of bacterial pathogens including Streptococcus pneumoniae. Experiments in mice have revealed that one of the functions of CRP is to protect against pneumococcal infection by binding to pneumococci and activating the complement system. For protection, however, CRP must be injected into mice within a few hours of administering pneumococci, that is, CRP is protective against early-stage infection but not against late-stage infection. It is assumed that CRP cannot protect if pneumococci got time to recruit complement inhibitor factor H on their surface to become complement attack-resistant. Since the conformation of CRP is altered under inflammatory conditions and altered CRP binds to immobilized factor H also, we hypothesized that in order to protect against late-stage infection, CRP needed to change its structure and that was not happening in mice. Accordingly, we engineered CRP molecules (E-CRP) which bind to factor H on pneumococci but do not bind to factor H on any host cell in the blood. We found that E-CRP, in cooperation with wild-type CRP, was protective regardless of the timing of administering E-CRP into mice. We conclude that CRP acts via two different conformations to execute its anti-pneumococcal function and a model for the mechanism of action of CRP is proposed. These results suggest that pre-modified CRP, such as E-CRP, is therapeutically beneficial to decrease bacteremia in pneumococcal infection. Our findings may also have implications for infections with antibiotic-resistant pneumococcal strains and for infections with other bacterial species that use host proteins to evade complement-mediated killing.
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Affiliation(s)
- Donald N Ngwa
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Sanjay K Singh
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Toh B Gang
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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7
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Lv JM, Chen JY, Liu ZP, Yao ZY, Wu YX, Tong CS, Cheng B. Celluar Folding Determinants and Conformational Plasticity of Native C-Reactive Protein. Front Immunol 2020; 11:583. [PMID: 32296446 PMCID: PMC7137756 DOI: 10.3389/fimmu.2020.00583] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/13/2020] [Indexed: 11/13/2022] Open
Abstract
C-reactive protein (CRP) is an acute phase reactant secreted by hepatocytes as a pentamer. The structure formation of pentameric CRP has been demonstrated to proceed in a stepwise manner in live cells. Here, we further dissect the sequence determinants that underlie the key steps in cellular folding and assembly of CRP. The initial folding of CRP subunits depends on a leading sequence with a conserved dipeptide that licenses the formation of the hydrophobic core. This drives the bonding of the intra-subunit disulfide requiring a favorable niche largely conferred by a single residue within the C-terminal helix. A conserved salt bridge then mediates the assembly of folded subunits into pentamer. The pentameric assembly harbors a pronounced plasticity in inter-subunit interactions, which may form the basis for a reversible activation of CRP in inflammation. These results provide insights into how sequence constraints are evolved to dictate structure and function of CRP.
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Affiliation(s)
- Jian-Min Lv
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, China
| | - Jun-Yao Chen
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Zu-Pei Liu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Zhen-Yu Yao
- Xi'an Key Laboratory of Children's Health and Diseases, The Affiliated Children Hospital, Children's Research Institute, Xi'an Jiaotong University, Xi'an, China
| | - Yue-Xin Wu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Cheng-Sen Tong
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Bin Cheng
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
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8
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Williams RD, Moran JA, Fryer AA, Littlejohn JR, Williams HM, Greenhough TJ, Shrive AK. Monomeric C-Reactive Protein in Serum With Markedly Elevated CRP Levels Shares Common Calcium-Dependent Ligand Binding Properties With an in vitro Dissociated Form of C-Reactive Protein. Front Immunol 2020; 11:115. [PMID: 32117266 PMCID: PMC7010908 DOI: 10.3389/fimmu.2020.00115] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/16/2020] [Indexed: 01/16/2023] Open
Abstract
A monomeric form of C-reactive protein (CRP) which precipitates with cell wall pneumococcal C polysaccharide (CWPS) and retains the ability to reversibly bind to its ligand phosphocholine has been produced through urea-induced dissociation at an optimized concentration of 3 M urea over a 10 weeks period. Dissociated samples were purified via size exclusion chromatography and characterized by western blot, phosphocholine affinity chromatography and CWPS precipitation. Human serum samples from patients with raised CRP levels (>100 mg/L as determined by the clinical laboratory assay) were purified by affinity and size exclusion chromatography and analyzed (n = 40) to determine whether circulating monomeric CRP could be detected ex vivo. All 40 samples tested positive for pentameric CRP via western blot and enzyme linked immunosorbent assay (ELISA) analysis. Monomeric C-reactive protein was also identified in all 40 patient samples tested, with an average level recorded of 1.03 mg/L (SE = ±0.11). Both the in vitro monomeric C-reactive protein and the human serum monomeric protein displayed a molecular weight of approximately 23 kDa, both were recognized by the same anti-CRP monoclonal antibody and both reversibly bound to phosphocholine in a calcium-dependent manner. In common with native pentameric CRP, the in vitro mCRP precipitated with CWPS. These overlapping characteristics suggest that a physiologically relevant, near-native monomeric CRP, which retains the structure and binding properties of native CRP subunits, has been produced through in vitro dissociation of pentameric CRP and also isolated from serum with markedly elevated CRP levels. This provides a clear route toward the in-depth study of the structure and function of physiological monomeric CRP.
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Affiliation(s)
- Robert D Williams
- School of Life Sciences, Keele University, Staffordshire, United Kingdom
| | - Jennifer A Moran
- School of Life Sciences, Keele University, Staffordshire, United Kingdom
| | - Anthony A Fryer
- Department of Clinical Biochemistry, Institute for Applied Clinical Sciences, University Hospitals of North Midlands, Keele University, Staffordshire, United Kingdom
| | - Jamie R Littlejohn
- School of Life Sciences, Keele University, Staffordshire, United Kingdom
| | - Harry M Williams
- School of Life Sciences, Keele University, Staffordshire, United Kingdom
| | | | - Annette K Shrive
- School of Life Sciences, Keele University, Staffordshire, United Kingdom
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9
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McFadyen JD, Zeller J, Potempa LA, Pietersz GA, Eisenhardt SU, Peter K. C-Reactive Protein and Its Structural Isoforms: An Evolutionary Conserved Marker and Central Player in Inflammatory Diseases and Beyond. Subcell Biochem 2020; 94:499-520. [PMID: 32189313 DOI: 10.1007/978-3-030-41769-7_20] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
C-reactive protein (CRP) is an evolutionary highly conserved member of the pentraxin superfamily of proteins. CRP is widely used as a marker of inflammation, infection and for risk stratification of cardiovascular events. However, there is now a large body of evidence, that continues to evolve, detailing that CRP directly mediates inflammatory reactions and the innate immune response in the context of localised tissue injury. These data support the concept that the pentameric conformation of CRP dissociates into pro-inflammatory CRP isoforms termed pCRP* and monomeric CRP. These pro-inflammatory CRP isoforms undergo conformational changes that facilitate complement binding and immune cell activation and therefore demonstrate the ability to trigger complement activation, activate platelets, monocytes and endothelial cells. The dissociation of pCRP occurs on the surface of necrotic, apoptotic, and ischaemic cells, regular β-sheet structures such as β-amyloid, the membranes of activated cells (e.g., platelets, monocytes, and endothelial cells), and/or the surface of microparticles, the latter by binding to phosphocholine. Therefore, the deposition and localisation of these pro-inflammatory isoforms of CRP have been demonstrated to amplify inflammation and tissue damage in a broad range of clinical conditions including ischaemia/reperfusion injury, Alzheimer's disease, age-related macular degeneration and immune thrombocytopaenia. Given the potentially broad relevance of CRP to disease pathology, the development of inhibitors of CRP remains an area of active investigation, which may pave the way for novel therapeutics for a diverse range of inflammatory diseases.
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Affiliation(s)
- James D McFadyen
- Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.
- Department of Medicine, Monash University, Melbourne, VIC, Australia.
- Department of Clinical Haematology, The Alfred Hospital, Melbourne, VIC, Australia.
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia.
| | - Johannes Zeller
- Department of Plastic and Hand Surgery, Medical Faculty of the University of Freiburg, University of Freiburg Medical Centre, Freiburg, Germany
| | | | - Geoffrey A Pietersz
- Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
- Department of Immunology, Monash University, Melbourne, VIC, Australia
- Burnet Institute, Melbourne, VIC, Australia
| | - Steffen U Eisenhardt
- Department of Plastic and Hand Surgery, Medical Faculty of the University of Freiburg, University of Freiburg Medical Centre, Freiburg, Germany
| | - Karlheinz Peter
- Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.
- Department of Medicine, Monash University, Melbourne, VIC, Australia.
- Department of Immunology, Monash University, Melbourne, VIC, Australia.
- Heart Centre, The Alfred Hospital, Melbourne, VIC, Australia.
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10
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Singh SK, Agrawal A. Functionality of C-Reactive Protein for Atheroprotection. Front Immunol 2019; 10:1655. [PMID: 31379851 PMCID: PMC6646712 DOI: 10.3389/fimmu.2019.01655] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022] Open
Abstract
C-reactive protein (CRP) is a pentameric molecule made up of identical monomers. CRP can be seen in three different forms: native pentameric CRP (native CRP), non-native pentameric CRP (non-native CRP), and monomeric CRP (mCRP). Both native and non-native CRP execute ligand-recognition functions for host defense. The fate of any pentameric CRP after binding to a ligand is dissociation into ligand-bound mCRP. If ligand-bound mCRP is proinflammatory, like free mCRP has been shown to be in vitro, then mCRP along with the bound ligand must be cleared from the site of inflammation. Once pentameric CRP is bound to atherogenic low-density lipoprotein (LDL), it reduces both formation of foam cells and proinflammatory effects of atherogenic LDL. A CRP mutant, that is non-native CRP, which readily binds to atherogenic LDL, has been found to be atheroprotective in a murine model of atherosclerosis. Thus, unlike statins, a drug that can lower only cholesterol levels but not CRP levels should be developed. Since non-native CRP has been shown to bind to all kinds of malformed proteins in general, it is possible that non-native CRP would be protective against all inflammatory states in which host proteins become pathogenic. If it is proven through experimentation employing transgenic mice that non-native CRP is beneficial for the host, then using a small-molecule compound to target CRP with the goal of changing the conformation of endogenous native CRP would be preferred over using recombinant non-native CRP as a biologic to treat diseases caused by pathogenic proteins such as oxidized LDL.
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Affiliation(s)
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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11
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Ngwa DN, Agrawal A. Structure-Function Relationships of C-Reactive Protein in Bacterial Infection. Front Immunol 2019; 10:166. [PMID: 30863393 PMCID: PMC6400226 DOI: 10.3389/fimmu.2019.00166] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 01/18/2019] [Indexed: 12/26/2022] Open
Abstract
One host defense function of C-reactive protein (CRP) is to protect against Streptococcus pneumoniae infection as shown by experiments employing murine models of pneumococcal infection. The protective effect of CRP is due to reduction in bacteremia. There is a distinct relationship between the structure of CRP and its anti-pneumococcal function. CRP is functional in both native and non-native pentameric structural conformations. In the native conformation, CRP binds to pneumococci through the phosphocholine molecules present on the C-polysaccharide of the pneumococcus and the anti-pneumococcal function probably involves the known ability of ligand-complexed CRP to activate the complement system. In the native structure-function relationship, CRP is protective only when given to mice within a few hours of the administration of pneumococci. The non-native pentameric conformation of CRP is created when CRP is exposed to conditions mimicking inflammatory microenvironments, such as acidic pH and redox conditions. In the non-native conformation, CRP binds to immobilized complement inhibitor factor H in addition to being able to bind to phosphocholine. Recent data using CRP mutants suggest that the factor H-binding function of non-native CRP is beneficial: in the non-native structure-function relationship, CRP can be given to mice any time after the administration of pneumococci irrespective of whether the pneumococci became complement-resistant or not. In conclusion, while native CRP is protective only against early stage infection, non-native CRP is protective against both early stage and late stage infections. Because non-native CRP displays phosphocholine-independent anti-pneumococcal activity, it is quite possible that CRP functions as a general anti-bacterial molecule.
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Affiliation(s)
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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12
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Guo Q, Xu C, Sun C, Zhao Y, Zhang W. Soluble Myeloid Triggering Receptor Expressed on Myeloid Cell 1 Might Have More Diagnostic Value for Bacterial Ascites than C-reactive Protein. Open Life Sci 2018; 13:456-462. [PMID: 33817114 PMCID: PMC7874684 DOI: 10.1515/biol-2018-0054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/29/2018] [Indexed: 11/15/2022] Open
Abstract
The timely and accurate diagnosis of ascites is of great significance for early treatment and prognostication. This study explored the value of soluble myeloid triggering receptor expressed on myeloid cell 1 (sTREM-1) and C-reactive protein (CRP) for assessing ascites. A total of 133 patients with ascites who received treatment at the Affiliated Hospital of Taishan Medical University between September 2015 and September 2017 were retrospectively analyzed. The ascites in 22, 45, 33 and 33 patients were tuberculous, bacterial, tumorous, and transudative, respectively. Healthy volunteers (n=30) who received a health examination at the same hospital during the same period constituted the control group. Before treatment, both ascitic sTREM-1 and CRP showed significant differences among the ascites subgroups (P<0.001), with the highest levels in the bacterial subgroup. Serum sTREM-1 and CRP also showed significant differences among the groups. A correlation analysis showed a positive correlation between sTREM-1 and CRP. ROC curves of the bacterial subgroup showed that when the optimal cutoff point was set to 20.2, the sensitivity, specificity, positive predictive value, and negative predictive value of the serum sTREM-1 index were 0.933, 0.955, 0.914, and 0.965, respectively. sTREM-1 may provide more diagnostic value than CRP for the diagnosis of bacterial ascites.
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Affiliation(s)
- Qiang Guo
- Department of Infectious Diseases, Affiliated Hospital of Taishan Medical University, Tai'an 271000, China
| | - Chuanqin Xu
- Department of Infectious Diseases, Affiliated Hospital of Taishan Medical University, Tai'an 271000, China
| | - Chao Sun
- Department of Infectious Diseases, Affiliated Hospital of Taishan Medical University, Tai'an 271000, China
| | - Yubao Zhao
- Department of Infectious Diseases, Affiliated Hospital of Taishan Medical University, Tai'an 271000, China
| | - Weifu Zhang
- Department of Public Health, Affiliated Hospital of Taishan Medical University, Tai'an 271000, China
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