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Alic L, Binder CJ, Papac-Milicevic N. The OSE complotype and its clinical potential. Front Immunol 2022; 13:1010893. [PMID: 36248824 PMCID: PMC9561429 DOI: 10.3389/fimmu.2022.1010893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 09/12/2022] [Indexed: 11/17/2022] Open
Abstract
Cellular death, aging, and tissue damage trigger inflammation that leads to enzymatic and non-enzymatic lipid peroxidation of polyunsaturated fatty acids present on cellular membranes and lipoproteins. This results in the generation of highly reactive degradation products, such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), that covalently modify free amino groups of proteins and lipids in their vicinity. These newly generated neoepitopes represent a unique set of damage-associated molecular patterns (DAMPs) associated with oxidative stress termed oxidation-specific epitopes (OSEs). OSEs are enriched on oxidized lipoproteins, microvesicles, and dying cells, and can trigger sterile inflammation. Therefore, prompt recognition and removal of OSEs is required to maintain the homeostatic balance. This is partially achieved by various humoral components of the innate immune system, such as natural IgM antibodies, pentraxins and complement components that not only bind OSEs but in some cases modulate their pro-inflammatory potential. Natural IgM antibodies are potent complement activators, and 30% of them recognize OSEs such as oxidized phosphocholine (OxPC-), 4-HNE-, and MDA-epitopes. Furthermore, OxPC-epitopes can bind the complement-activating pentraxin C-reactive protein, while MDA-epitopes are bound by C1q, C3a, complement factor H (CFH), and complement factor H-related proteins 1, 3, 5 (FHR-1, FHR-3, FHR-5). In addition, CFH and FHR-3 are recruited to 2-(ω-carboxyethyl)pyrrole (CEP), and full-length CFH also possesses the ability to attenuate 4-HNE-induced oxidative stress. Consequently, alterations in the innate humoral defense against OSEs predispose to the development of diseases associated with oxidative stress, as shown for the prototypical OSE, MDA-epitopes. In this mini-review, we focus on the mechanisms of the accumulation of OSEs, the pathophysiological consequences, and the interactions between different OSEs and complement components. Additionally, we will discuss the clinical potential of genetic variants in OSE-recognizing complement proteins – the OSE complotype - in the risk estimation of diseases associated with oxidative stress.
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Affiliation(s)
- Lejla Alic
- Department of Medical Biochemistry, Faculty of Medicine, University of Sarajevo, Sarajevo, Bosnia and Herzegovina
| | - Christoph J. Binder
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Nikolina Papac-Milicevic
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
- *Correspondence: Nikolina Papac-Milicevic,
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2
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Song G, Wang S, Barkestani MN, Mullan C, Fan M, Jiang B, Jiang Q, Li X, Jane-wit D. Membrane attack complexes, endothelial cell activation, and direct allorecognition. Front Immunol 2022; 13:1020889. [PMID: 36211400 PMCID: PMC9539657 DOI: 10.3389/fimmu.2022.1020889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 09/07/2022] [Indexed: 11/18/2022] Open
Abstract
Endothelial cells (ECs) form a critical immune interface regulating both the activation and trafficking of alloreactive T cells. In the setting of solid organ transplantation, donor-derived ECs represent sites where alloreactive T cells encounter major and minor tissue-derived alloantigens. During this initial encounter, ECs may formatively modulate effector responses of these T cells through expression of inflammatory mediators. Direct allorecognition is a process whereby recipient T cells recognize alloantigen in the context of donor EC-derived HLA molecules. Direct alloresponses are strongly modulated by human ECs and are galvanized by EC-derived inflammatory mediators. Complement are immune proteins that mark damaged or foreign surfaces for immune cell activation. Following labeling by natural IgM during ischemia reperfusion injury (IRI) or IgG during antibody-mediated rejection (ABMR), the complement cascade is terminally activated in the vicinity of donor-derived ECs to locally generate the solid-phase inflammatory mediator, the membrane attack complex (MAC). Via upregulation of leukocyte adhesion molecules, costimulatory molecules, and cytokine trans-presentation, MAC strengthen EC:T cell direct alloresponses and qualitatively shape the alloimmune T cell response. These processes together promote T cell-mediated inflammation during solid organ transplant rejection. In this review we describe molecular pathways downstream of IgM- and IgG-mediated MAC assembly on ECs in the setting of IRI and ABMR of tissue allografts, respectively. We describe work demonstrating that MAC deposition on ECs generates ‘signaling endosomes’ that sequester and post-translationally enhance the stability of inflammatory signaling molecules to promote EC activation, a process potentiating EC-mediated direct allorecognition. Additionally, with consideration to first-in-human xenotransplantation procedures, we describe clinical therapeutics based on inhibition of the complement pathway. The complement cascade critically mediates EC activation and improved understanding of relevant effector pathways will uncover druggable targets to obviate dysregulated alloimmune T cell infiltration into tissue allografts.
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Affiliation(s)
- Guiyu Song
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
- Department of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Shaoxun Wang
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
| | - Mahsa Nouri Barkestani
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Clancy Mullan
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, United States
| | - Matthew Fan
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Bo Jiang
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
- Department of Vascular Surgery, The First Hospital of China Medical University, Shenyang, China
| | - Quan Jiang
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Xue Li
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
- Department of Nephrology, The First Hospital of China Medical University, Shenyang, China
| | - Dan Jane-wit
- Section of Cardiovascular Medicine, Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, United States
- Department of Cardiology, West Haven VA Medical Center, West Haven, CT, United States
- *Correspondence: Dan Jane-wit,
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3
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Lorey MB, Öörni K, Kovanen PT. Modified Lipoproteins Induce Arterial Wall Inflammation During Atherogenesis. Front Cardiovasc Med 2022; 9:841545. [PMID: 35310965 PMCID: PMC8927694 DOI: 10.3389/fcvm.2022.841545] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/26/2022] [Indexed: 12/15/2022] Open
Abstract
Circulating apolipoprotein B-containing lipoproteins, notably the low-density lipoproteins, enter the inner layer of the arterial wall, the intima, where a fraction of them is retained and modified by proteases, lipases, and oxidizing agents and enzymes. The modified lipoproteins and various modification products, such as fatty acids, ceramides, lysophospholipids, and oxidized lipids induce inflammatory reactions in the macrophages and the covering endothelial cells, initiating an increased leukocyte diapedesis. Lipolysis of the lipoproteins also induces the formation of cholesterol crystals with strong proinflammatory properties. Modified and aggregated lipoproteins, cholesterol crystals, and lipoproteins isolated from human atherosclerotic lesions, all can activate macrophages and thereby induce the secretion of proinflammatory cytokines, chemokines, and enzymes. The extent of lipoprotein retention, modification, and aggregation have been shown to depend largely on differences in the composition of the circulating lipoprotein particles. These properties can be modified by pharmacological means, and thereby provide opportunities for clinical interventions regarding the prevention and treatment of atherosclerotic vascular diseases.
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Affiliation(s)
- Martina B. Lorey
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
- Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Katariina Öörni
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
- Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- *Correspondence: Katariina Öörni
| | - Petri T. Kovanen
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
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4
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Kiss MG, Binder CJ. The multifaceted impact of complement on atherosclerosis. Atherosclerosis 2022; 351:29-40. [DOI: 10.1016/j.atherosclerosis.2022.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 02/17/2022] [Accepted: 03/09/2022] [Indexed: 12/12/2022]
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5
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Mulfaul K, Mullin NK, Giacalone JC, Voigt AP, DeVore M, Stone EM, Tucker BA, Mullins RF. Local Factor H production by human choroidal endothelial cells mitigates complement deposition: implications for macular degeneration. J Pathol 2022; 257:29-38. [PMID: 35038170 PMCID: PMC9007903 DOI: 10.1002/path.5867] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/14/2021] [Accepted: 01/12/2022] [Indexed: 11/11/2022]
Abstract
Activation of the alternative complement pathway is an initiating event in the pathology of Age-related Macular Degeneration (AMD). Unchecked complement activation leads to the formation of a pro-lytic pore, the Membrane Attack Complex (MAC). MAC deposition is observed on the choriocapillaris of AMD patients and likely causes lysis of choroidal endothelial cells (CECs). Complement factor H (FH, encoded by the gene CFH), is an inhibitor of complement. Both loss of function of FH and reduced choroidal levels of FH have been reported in AMD. It is plausible that reduced local FH availability promotes MAC deposition on CECs. FH is produced primarily in the liver; however, cells including the retinal pigment epithelium can produce FH locally. We hypothesized that CECs produce FH locally to protect against MAC deposition. We aimed to investigate the effect of reduced FH levels in the choroid to determine whether increasing local FH could protect CECs from MAC deposition. We demonstrated that siRNA knockdown of FH (CFH) in human immortalized CECs results in increased MAC deposition. We generated AMD iPSC-derived CECs and found that overexpression of FH protects against MAC deposition. These results suggest that local CEC-produced FH protects against MAC deposition, and that increasing local FH protein may be beneficial in limiting MAC deposition in AMD. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kelly Mulfaul
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Nathaniel K Mullin
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Joseph C Giacalone
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Andrew P Voigt
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Melette DeVore
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Edwin M Stone
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Budd A Tucker
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Robert F Mullins
- Institute for Vision Research, Department of Ophthalmology & Visual Sciences, University of Iowa, Iowa City, IA, USA
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6
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Duan S, Sun L, Nie G, Chen J, Zhang C, Zhu H, Huang Z, Qian J, Zhao X, Xing C, Zhang B, Yuan Y. Association of Glomerular Complement C4c Deposition With the Progression of Diabetic Kidney Disease in Patients With Type 2 Diabetes. Front Immunol 2020; 11:2073. [PMID: 32983156 PMCID: PMC7492595 DOI: 10.3389/fimmu.2020.02073] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/30/2020] [Indexed: 12/24/2022] Open
Abstract
Objectives: As accumulating data supporting the potential role of the complement system in the pathogenesis of diabetic kidney disease (DKD), the present study aimed to explore the association of glomerular complement C4c deposition with the baseline clinicopathological characteristics and the prognosis of DKD in type 2 diabetes (T2DM) patients. Methods: A total of 79 T2DM patients with biopsy-proven DKD were enrolled. Clinicopathological features and renal outcomes were compared between groups divided by the glomerular C4c deposition patterns and median values of serum C4. Renal outcomes were defined by doubling of serum creatinine level or progression to end-stage renal disease (ESRD). A Cox proportional hazards model was employed to identify the risk factors associated with renal events. Results: Patients with glomerular C4c deposition had worse renal insufficiency than those without C4c deposits, along with higher 24-h urinary protein, triglyceride, but lower serum albumin and higher interstitial inflammation score. Besides, serum C4 levels positively correlated with urinary protein and serum C3 levels. During 21.85 ± 16.32 months of follow-up, Kaplan-Meier curve analysis showed significantly faster deterioration of renal function for patients with positive glomerular C4c deposition as well as higher levels of serum C4. More specifically, more than 50% of the patients with glomerular C4c had co-deposition of C3c or C1q, and patients with glomerular complement complex of C4c and one or two of C3/C1q deposition had more severe proteinuria and a higher rate of DKD progression than those with negative C4c deposits. The univariate Cox regression indicated that factors of combined serum and glomerular C4, urinary protein, serum creatinine, serum C3, combined glomerular C4c and IgM and interstitial inflammation were associated with an increased risk of DKD, but only glomerular C4c intensity (HR 1.584, 95% CI [1.001, 2.508], p = 0.0497), as well as baseline age and diabetic neuropathy, were independent risk factors for renal survival by the multivariate Cox analysis. Conclusions: Glomerular C4c deposition was associated with deteriorated renal function and outcomes in patients with T2DKD. Glomerular C4c deposition was an independent risk factor for DKD progression.
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Affiliation(s)
- Suyan Duan
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Lianqin Sun
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Guangyan Nie
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Jiajia Chen
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Chengning Zhang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Huanhuan Zhu
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Zhimin Huang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Jun Qian
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Xiufen Zhao
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Changying Xing
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Bo Zhang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Yanggang Yuan
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
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7
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Shimizu K, Miyata H, Abekura Y, Oka M, Kushamae M, Kawamata T, Mizutani T, Kataoka H, Nozaki K, Miyamoto S, Aoki T. High-Fat Diet Intake Promotes the Enlargement and Degenerative Changes in the Media of Intracranial Aneurysms in Rats. J Neuropathol Exp Neurol 2020; 78:798-807. [PMID: 31340038 DOI: 10.1093/jnen/nlz057] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/21/2019] [Accepted: 06/13/2019] [Indexed: 11/12/2022] Open
Abstract
Subarachnoid hemorrhage due to rupture of intracranial aneurysms is a life-threatening disease. Although some previous reports have demonstrated an association between lipid accumulation and degenerative changes in aneurysmal walls in humans, epidemiological studies have failed to identify dyslipidemia as a risk factor for intracranial aneurysms. Thus, we examined whether an increase in serum cholesterol levels facilitates the progression of intracranial aneurysms in a rat model. Rats were given a high-fat diet (HFD) and subjected to an intracranial aneurysm model. The HFD elevated their serum cholesterol levels. The intracranial aneurysms induced at the anterior cerebral artery-olfactory artery bifurcation were significantly larger in the high-fat group than in the normal-chow group. Histological analysis demonstrated that the loss of medial smooth muscle layers was exacerbated in the high-fat group and indicated the presence of macrophage-derived foam cells in the lesions. In in vitro experiments, the expression levels of the pro-inflammatory genes induced by LPS in RAW264.7-derived foam cells were significantly higher than those in RAW264.7 cells. The combination of these results suggests that increased serum cholesterol levels facilitate degenerative changes in the media and the progression of intracranial aneurysms presumably through foam cell transformation.
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Affiliation(s)
- Kampei Shimizu
- Department of Molecular Pharmacology, Research Institute.,Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita City, Osaka, Japan.,Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto City, Kyoto, Japan
| | - Haruka Miyata
- Department of Molecular Pharmacology, Research Institute.,Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita City, Osaka, Japan.,Department of Neurosurgery, Shiga University of Medical Science, Otsu City, Shiga, Japan
| | - Yu Abekura
- Department of Molecular Pharmacology, Research Institute.,Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita City, Osaka, Japan.,Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto City, Kyoto, Japan
| | - Mieko Oka
- Department of Molecular Pharmacology, Research Institute.,Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita City, Osaka, Japan.,Department of Neurosurgery, Tokyo Women's Medical University
| | - Mika Kushamae
- Department of Molecular Pharmacology, Research Institute.,Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita City, Osaka, Japan.,Department of Neurosurgery, Showa University School of Medicine, Tokyo, Japan
| | | | - Tohru Mizutani
- Department of Neurosurgery, Showa University School of Medicine, Tokyo, Japan
| | - Hiroharu Kataoka
- Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto City, Kyoto, Japan
| | - Kazuhiko Nozaki
- Department of Neurosurgery, Shiga University of Medical Science, Otsu City, Shiga, Japan
| | - Susumu Miyamoto
- Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto City, Kyoto, Japan
| | - Tomohiro Aoki
- Department of Molecular Pharmacology, Research Institute.,Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita City, Osaka, Japan
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Huang C, Fisher KP, Hammer SS, Busik JV. Extracellular Vesicle-Induced Classical Complement Activation Leads to Retinal Endothelial Cell Damage via MAC Deposition. Int J Mol Sci 2020; 21:ijms21051693. [PMID: 32121610 PMCID: PMC7084203 DOI: 10.3390/ijms21051693] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 12/11/2022] Open
Abstract
Several studies have suggested that there is a link between membrane attack complex (MAC) deposition in the retina and the progression of diabetic retinopathy (DR). Our recent investigation demonstrated that circulating IgG-laden extracellular vesicles contribute to an increase in retinal vascular permeability in DR through activation of the complement system. However, the mechanism through which extracellular vesicle-induced complement activation contributes to retinal vascular cytolytic damage in DR is not well understood. In this study, we demonstrate that IgG-laden extracellular vesicles in rat plasma activate the classical complement pathway, and in vitro Streptozotocin (STZ)-induced rat diabetic plasma results in MAC deposition and cytolytic damage in human retinal endothelial cells (HRECs). Moreover, removal of the plasma extracellular vesicles reduced the MAC deposition and abrogated cytolytic damage seen in HRECs. Together, the results of this study demonstrate that complement activation by IgG-laden extracellular vesicles in plasma could lead to MAC deposition and contribute to endothelium damage and progression of DR.
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9
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Espericueta V, Manughian-Peter AO, Bally I, Thielens NM, Fraser DA. Recombinant C1q variants modulate macrophage responses but do not activate the classical complement pathway. Mol Immunol 2019; 117:65-72. [PMID: 31739194 DOI: 10.1016/j.molimm.2019.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/03/2019] [Accepted: 10/08/2019] [Indexed: 11/25/2022]
Abstract
Complement protein C1q plays a dual role in a number of inflammatory diseases such as atherosclerosis. While in later stages classical complement pathway activation by C1q exacerbates disease progression, C1q also plays a beneficial role in early disease. Independent of its role in complement activation, we and others have identified a number of potentially beneficial interactions of C1q with phagocytes in vitro, including triggering phagocytosis of cellular and molecular debris and polarizing macrophages toward an anti-inflammatory phenotype. These interactions may also be important in preventing autoimmunity. Here, we characterize variants of recombinant human C1q (rC1q) which no longer initiate complement activation, through mutation of the C1r2C1s2 interaction site. For insight into the structural location of the site of C1q that is important for interaction with phagocytes, we investigated the effect of these mutations on phagocytosis and macrophage inflammatory polarization, as compared to wild-type C1q. Phagocytosis of antibody coated sheep erythrocytes and oxidized LDL was measured in human monocytes and monocyte-derived macrophages (HMDM) respectively that had interacted with rC1q wild-type or variants. Secreted levels of cytokines were also measured in C1q stimulated HMDM. All variants of C1q increased phagocytosis in HMDM compared to controls, similar to native or wild-type rC1q. In addition, levels of certain pro-inflammatory cytokines and chemokines secreted by HMDM were modulated in cells that interacted with C1q variants, similar to wild-type rC1q and native C1q. This includes downregulation of IL-1α, IL-1β, TNFα, MIP-1α, and IL-12p40 by native and rC1q in both resting and M1-polarized HMDM. This suggests that the site responsible for C1q interaction with phagocytes is independent of the C1r2C1s2 interaction site. Further studies with these classical pathway-null variants of C1q should provide greater understanding of the complement-independent role of C1q, and allow for potential therapeutic exploitation.
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Affiliation(s)
- Victoria Espericueta
- Department of Biological Sciences, California State University Long Beach, CA, USA
| | | | - Isabelle Bally
- Univ. Grenoble Alpes, CEA, CNRS, IBS, F-38000, Grenoble, France
| | | | - Deborah A Fraser
- Department of Biological Sciences, California State University Long Beach, CA, USA.
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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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Sun ZJ, Li XQ, Chang DY, Wang SX, Liu G, Chen M, Zhao MH. Complement deposition on renal histopathology of patients with diabetic nephropathy. DIABETES & METABOLISM 2018; 45:363-368. [PMID: 30243617 DOI: 10.1016/j.diabet.2018.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 08/01/2018] [Accepted: 08/27/2018] [Indexed: 12/24/2022]
Abstract
AIMS As the potential role of the complement system in diabetic nephropathy (DN) is increasingly reported, this study aimed to investigate C1q and C3c deposition as seen on renal histopathology, as well as its association with clinical and pathological parameters, in DN patients. METHODS Renal biopsy specimens from 161 DN patients were investigated using direct immunofluorescence, light, and electron microscopy. For direct immunofluorescence, staining for C1q and C3c on fresh-frozen renal tissue was performed immediately after biopsy. Complement deposition was defined as the presence of C1q or C3c of at least 1 + on a 0-4 + Scale. The association between complement deposition and clinicopathological data was also analyzed. RESULTS On direct immunofluorescence microscopy, C1q and C3c were detected in specimens from 44/161 (27.3%) and 89/161 (55.3%) patients, respectively. Regarding clinical data, patients with C1q deposition had a significantly higher level of urinary protein (7.25 ± 4.20 g/24 h vs. 4.97 ± 3.76 g/24 h; P < 0.01) and significantly lower estimated glomerular filtration rate (eGFR; 34.16 ± 25.21 mL/min/1.73 m2 vs. 51.17 ± 31.56 mL/min/1.73 m2, respectively; P < 0.01), whereas patients with vs. without C3c deposition had a significantly lower eGFR (40.09 ± 27.97 mL/min/1.73 m2 vs. 54.48 ± 32.49 mL/min/1.73 m2, respectively; P < 0.01). On renal histopathology, patients with C1q deposition had significantly higher Scores for interstitial fibrosis and tubular atrophy (IFTA), interstitial inflammation and vascular lesions (P < 0.01, P < 0.05 and P < 0.05, respectively), whereas patients with C3c deposition had significantly higher IFTA Scores and proportions of global sclerosis (P < 0.01 and P < 0.01, respectively). CONCLUSION Complement deposition of C1q and C3c on renal histopathology is associated with more severe kidney damage in patients with DN.
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Affiliation(s)
- Z-J Sun
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China
| | - X-Q Li
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China
| | - D-Y Chang
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China
| | - S-X Wang
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China
| | - G Liu
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China
| | - M Chen
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China.
| | - M-H Zhao
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, No. 8, Xishiku street, 100034, Xicheng, Beijing, PR China; Peking-Tsinghua Center for Life Sciences, Beijing 100034, PR China
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12
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Huang C, Fisher KP, Hammer SS, Navitskaya S, Blanchard GJ, Busik JV. Plasma Exosomes Contribute to Microvascular Damage in Diabetic Retinopathy by Activating the Classical Complement Pathway. Diabetes 2018; 67:1639-1649. [PMID: 29866771 PMCID: PMC6054433 DOI: 10.2337/db17-1587] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 05/05/2018] [Indexed: 12/12/2022]
Abstract
Diabetic retinopathy (DR) is a microvascular complication of diabetes and is the leading cause of vision loss in working-age adults. Recent studies have implicated the complement system as a player in the development of vascular damage and progression of DR. However, the role and activation of the complement system in DR are not well understood. Exosomes, small vesicles that are secreted into the extracellular environment, have a cargo of complement proteins in plasma, suggesting that they can participate in causing the vascular damage associated with DR. We demonstrate that IgG-laden exosomes in plasma activate the classical complement pathway and that the quantity of these exosomes is increased in diabetes. Moreover, we show that a lack of IgG in exosomes in diabetic mice results in a reduction in retinal vascular damage. The results of this study demonstrate that complement activation by IgG-laden plasma exosomes could contribute to the development of DR.
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Affiliation(s)
- Chao Huang
- Department of Physiology, Michigan State University, East Lansing, MI
| | - Kiera P Fisher
- Department of Physiology, Michigan State University, East Lansing, MI
| | - Sandra S Hammer
- Department of Physiology, Michigan State University, East Lansing, MI
| | | | - Gary J Blanchard
- Department of Chemistry, Michigan State University, East Lansing, MI
| | - Julia V Busik
- Department of Physiology, Michigan State University, East Lansing, MI
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13
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Complement activation in patients with diabetic nephropathy. DIABETES & METABOLISM 2018; 45:248-253. [PMID: 29729954 DOI: 10.1016/j.diabet.2018.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/15/2018] [Accepted: 04/07/2018] [Indexed: 01/10/2023]
Abstract
AIM Emerging evidence has indicated a role of the complement system in the pathogenesis of diabetic nephropathy (DN), although the pathways of complement activation and their clinicopathological relevance in DN are as yet unclear. The present study aimed to investigate levels of various complement components in plasma and urine of DN patients, and their correlation with clinicopathological parameters. METHODS A total of 68 biopsy-proven DN patients with plasma samples were recruited, including 50 patients who also had urine samples available. Seven complement components (C1q, MBL, Bb, C4d, C3a, C5a, soluble C5b-9) were measured by enzyme-linked immunosorbent assay (Elisa), and any associations between their levels and clinicopathological parameters were then investigated. RESULTS In DN patients, plasma levels of C1q, MBL, Bb, C4d, C3a, C5a and sC5b-9 were significantly higher than in diabetes patients without renal involvement, as were also urinary levels except for C1q, which showed no significant differences between the two groups. Also, urinary levels of C3a and C5a were significantly correlated with serum creatinine, urinary protein and estimated glomerular filtration rate, whereas urinary sC5b-9 was significantly correlated with the latter two (and not serum creatinine). In addition, urinary levels of MBL, Bb and C4d were significantly correlated with urinary protein, while C3a, C4d and Bb significantly correlated with the classification of glomerular lesions in DN. CONCLUSION In DN patients, the complement system is activated and, of the three possible complement pathways, activation of the lectin and alternative pathways is associated with renal damage.
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14
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Belime A, Gravel E, Brenet S, Ancelet S, Caneiro C, Hou Y, Thielens N, Doris E, Ling WL. Mode of PEG Coverage on Carbon Nanotubes Affects Binding of Innate Immune Protein C1q. J Phys Chem B 2017; 122:757-763. [PMID: 28915042 DOI: 10.1021/acs.jpcb.7b06596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Surface modification of nanoparticles with poly(ethylene glycol) (PEG) is used in biomedicine to increase the circulation time of the particles after intravenous injection. Here, we study the interaction of PEG-covered carbon nanotubes (CNTs) with the serum complement protein C1q. Besides being the target-recognizing unit of the initiating complex for the classical pathway of complement in our innate immune system, C1q is involved in a range of important physiological processes. We modified the surface of multiwalled CNTs with covalently grafted PEG and physically adsorbed PEG. Transmission electron microscopy revealed the interaction of these PEG-coated CNTs with C1q. We found abundant C1q coverage on the PEG-grafted CNTs but not on the CNTs with adsorbed PEG. We tested the ability of these CNTs to activate the complement system using in vitro complement activation assays. None of the CNTs studied activated the C1q-dependent classical complement pathway. These findings are pertinent to the safe design and novel biomedical applications of PEGylated CNTs.
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Affiliation(s)
- Agathe Belime
- Service de Chimie Bioorganique et de Marquage (SCBM), CEA, Université Paris-Saclay , 91191 Gif-sur-Yvette, France
| | - Edmond Gravel
- Service de Chimie Bioorganique et de Marquage (SCBM), CEA, Université Paris-Saclay , 91191 Gif-sur-Yvette, France
| | - Sophie Brenet
- Univ. Grenoble Alpes , CNRS, CEA, INAC, SyMMES, F-38000 Grenoble, France
| | - Sarah Ancelet
- Univ. Grenoble Alpes , CEA, CNRS, IBS, F-38000 Grenoble, France
| | | | - Yanxia Hou
- Univ. Grenoble Alpes , CNRS, CEA, INAC, SyMMES, F-38000 Grenoble, France
| | - Nicole Thielens
- Univ. Grenoble Alpes , CEA, CNRS, IBS, F-38000 Grenoble, France
| | - Eric Doris
- Service de Chimie Bioorganique et de Marquage (SCBM), CEA, Université Paris-Saclay , 91191 Gif-sur-Yvette, France
| | - Wai Li Ling
- Univ. Grenoble Alpes , CEA, CNRS, IBS, F-38000 Grenoble, France
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15
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Liu F, Sahoo R, Ge X, Wu L, Ghosh P, Qin X, Halperin JA. Deficiency of the complement regulatory protein CD59 accelerates the development of diabetes-induced atherosclerosis in mice. J Diabetes Complications 2017; 31:311-317. [PMID: 27729184 PMCID: PMC5460985 DOI: 10.1016/j.jdiacomp.2016.08.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 08/15/2016] [Accepted: 08/24/2016] [Indexed: 01/13/2023]
Abstract
AIMS Clinical and experimental evidence supports a strong link between the complement system, complement regulatory proteins and the pathogenesis of diabetes vascular complications. We previously reported that the complement regulatory protein CD59 is inactivated by glycation in humans with diabetes. Our objective for this study is to assess experimentally how the deficiency of CD59 impacts the development of diabetic atherosclerosis in vivo. METHODS We crossed mCD59 sufficient and deficient mice into the ApoE-/- background to generate mCd59ab+/+/ApoE-/- and mCd59ab-/-/ApoE-/- mice, and induced diabetes by multiple low dose injections of streptozotocin. Atherosclerosis was detected by hematoxylin and eosin (H&E) and oil red-O staining. Membrane attack complex (MAC) deposition and macrophage infiltration were detected by immunostaining. RESULTS Diabetic mCD59 deficient (mCD59ab-/-/ApoE-/-) mice developed nearly 100% larger atherosclerotic lesion areas in the aorta (7.5%±0.6 vs 3.6%±0.7; p<0.005) and in the aortic roots (H&E: 26.2%±1.9 vs. 14.3%±1.1; p<0.005), in both cases associated with increased lipid (Oil red-O: 14.9%±1.1 vs. 7.8%±1.1; p<0.05) and MAC deposition (6.8%±0.8 vs. 3.0%±0.7; p<0.005) and macrophage infiltration (31.5%±3.7 vs. 16.4%±3.0; p<0.05) in the aortic roots as compared to their diabetic mCD59 sufficient (mCD59ab+/+/ApoE-/-) counterpart. CONCLUSIONS The deficiency of CD59 accelerates the development of diabetic atherosclerosis.
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MESH Headings
- Animals
- Aorta
- Apolipoproteins E/genetics
- Apolipoproteins E/metabolism
- Atherosclerosis/complications
- Atherosclerosis/immunology
- Atherosclerosis/metabolism
- Atherosclerosis/pathology
- Blood Glucose/analysis
- CD59 Antigens/deficiency
- CD59 Antigens/genetics
- CD59 Antigens/metabolism
- Complement Activation/drug effects
- Complement Membrane Attack Complex/metabolism
- Crosses, Genetic
- Diabetes Mellitus, Type 1/blood
- Diabetes Mellitus, Type 1/chemically induced
- Diabetes Mellitus, Type 1/complications
- Diabetic Angiopathies/immunology
- Diabetic Angiopathies/metabolism
- Diabetic Angiopathies/pathology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/immunology
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Lipid Metabolism/drug effects
- Macrophage Activation/drug effects
- Mice, Inbred C57BL
- Mice, Knockout
- Streptozocin/toxicity
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Affiliation(s)
- Fengming Liu
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Rupam Sahoo
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Xiaowen Ge
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Lin Wu
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Pamela Ghosh
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Xuebin Qin
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jose A Halperin
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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16
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Pulanco MC, Cosman J, Ho MM, Huynh J, Fing K, Turcu J, Fraser DA. Complement Protein C1q Enhances Macrophage Foam Cell Survival and Efferocytosis. THE JOURNAL OF IMMUNOLOGY 2016; 198:472-480. [PMID: 27895181 DOI: 10.4049/jimmunol.1601445] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/01/2016] [Indexed: 12/12/2022]
Abstract
In the atherosclerotic lesion, macrophages ingest high levels of damaged modified low-density lipoproteins (LDLs), generating macrophage foam cells. Foam cells undergo apoptosis and, if not efficiently cleared by efferocytosis, can undergo secondary necrosis, leading to plaque instability and rupture. As a component of the innate immune complement cascade, C1q recognizes and opsonizes modified forms of LDL, such as oxidized or acetylated LDL, and promotes ingestion by macrophages in vitro. C1q was shown to be protective in an atherosclerosis model in vivo. Therefore, this study aimed to investigate whether ingestion of modified LDL in the presence of C1q alters macrophage foam cell survival or function. In an unbiased transcriptome analysis, C1q was shown to modulate expression of clusters of genes involved in cell death and apoptosis pathways in human monocyte-derived macrophages ingesting modified LDL; this was validated by quantitative PCR in human and murine macrophages. C1q downregulated levels and activity of active caspase-3 and PARP-1 in human and mouse macrophages during ingestion of modified LDL. This led to a measurable increase in survival and decrease in cell death, as measured by alamarBlue and propidium iodide assays, respectively. C1q opsonization also increased phagocytosis and efferocytosis in macrophage foam cells. These data suggest that C1q promotes macrophage survival during ingestion of excess cholesterol, as well as improves foam cell efferocytic function. This may be important in slowing disease progression and provides insight into the protective role of C1q in early atherosclerosis.
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Affiliation(s)
- Marc C Pulanco
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
| | - Jason Cosman
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
| | - Minh-Minh Ho
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
| | - Jessica Huynh
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
| | - Karina Fing
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
| | - Jacqueline Turcu
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
| | - Deborah A Fraser
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840
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17
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Abstract
C1q, historically viewed as the initiating component of the classical complement pathway, also exhibits a variety of complement-independent activities in both innate and acquired immunity. Recent studies focusing on C1q's suppressive role in the immune system have provided new insight into how abnormal C1q expression and bioactivity may contribute to autoimmunity. In particular, molecular networks involving C1q interactions with cell surface receptors and other ligands are emerging as mechanisms involved in C1q's modulation of immunity. Here, we discuss the role of C1q in controlling immune cell function, including recently elucidated mechanisms of action, and suggest how these processes are critical for maintaining tissue homeostasis under steady-state conditions and in preventing autoimmunity.
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Affiliation(s)
- Myoungsun Son
- Center for Autoimmune and Musculoskeletal Diseases, The Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, NY, 11030, USA
| | - Betty Diamond
- Center for Autoimmune and Musculoskeletal Diseases, The Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, NY, 11030, USA.
| | - Frances Santiago-Schwarz
- Center for Autoimmune and Musculoskeletal Diseases, The Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, NY, 11030, USA
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18
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Ho MM, Manughian-Peter A, Spivia WR, Taylor A, Fraser DA. Macrophage molecular signaling and inflammatory responses during ingestion of atherogenic lipoproteins are modulated by complement protein C1q. Atherosclerosis 2016; 253:38-46. [PMID: 27573737 DOI: 10.1016/j.atherosclerosis.2016.08.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/08/2016] [Accepted: 08/19/2016] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND AIMS This study investigated the effect of innate immune protein C1q on macrophage programmed responses during the ingestion of atherogenic lipoproteins. C1q plays a dual role in atherosclerosis where activation of complement by C1q is known to drive inflammation and promote disease progression. However, C1q is atheroprotective in early disease using mouse models. Our previous studies have highlighted a non-complement associated role for C1q in polarizing macrophages towards an M2-like anti-inflammatory phenotype during ingestion of targets such as atherogenic lipoproteins. This study aims to investigate the molecular mechanisms involved. METHODS We investigated the molecular signaling mechanisms involved in macrophage polarization using an unbiased examination of gene expression profiles in human monocyte derived macrophages ingesting oxidized or acetylated low density lipoproteins in the presence or absence of C1q. RESULTS Expression of genes involved in Janus kinase and signal transducer and activator of transcription (JAK-STAT) signaling, peroxisome proliferator activating receptor (PPAR) signaling and toll-like receptor (TLR) signaling were modulated by C1q in this screen. C1q was also shown to significantly suppress JAK-STAT pathway activation (a maximum 55% ± 13% reduction, p = 0.044) and increase transcriptional activation of PPARs (a maximum 229% ± 54% increase, p = 0.0002), consistent with an M2-like polarized response. These pathways were regulated in macrophages by C1q bound to different types of modified atherogenic lipoprotein and led to a reduction in the release of pro-inflammatory cytokine IL-6. CONCLUSIONS This study identifies potential molecular mechanisms for the beneficial role C1q plays in early atherosclerosis.
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Affiliation(s)
- Minh-Minh Ho
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA
| | - Ayla Manughian-Peter
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA
| | - Weston R Spivia
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA
| | - Adam Taylor
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA
| | - Deborah A Fraser
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA.
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19
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Pilely K, Rosbjerg A, Genster N, Gal P, Pál G, Halvorsen B, Holm S, Aukrust P, Bakke SS, Sporsheim B, Nervik I, Niyonzima N, Bartels ED, Stahl GL, Mollnes TE, Espevik T, Garred P. Cholesterol Crystals Activate the Lectin Complement Pathway via Ficolin-2 and Mannose-Binding Lectin: Implications for the Progression of Atherosclerosis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:5064-74. [PMID: 27183610 DOI: 10.4049/jimmunol.1502595] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 04/13/2016] [Indexed: 12/16/2023]
Abstract
Cholesterol crystals (CC) play an essential role in the formation of atherosclerotic plaques. CC activate the classical and the alternative complement pathways, but the role of the lectin pathway is unknown. We hypothesized that the pattern recognition molecules (PRMs) from the lectin pathway bind CC and function as an upstream innate inflammatory signal in the pathophysiology of atherosclerosis. We investigated the binding of the PRMs mannose-binding lectin (MBL), ficolin-1, ficolin-2, and ficolin-3, the associated serine proteases, and complement activation products to CC in vitro using recombinant proteins, specific inhibitors, as well as deficient and normal sera. Additionally, we examined the deposition of ficolin-2 and MBL in human carotid plaques by immunohistochemistry and fluorescence microscopy. The results showed that the lectin pathway was activated on CC by binding of ficolin-2 and MBL in vitro, resulting in activation and deposition of complement activation products. MBL bound to CC in a calcium-dependent manner whereas ficolin-2 binding was calcium-independent. No binding was observed for ficolin-1 or ficolin-3. MBL and ficolin-2 were present in human carotid plaques, and binding of MBL to CC was confirmed in vivo by immunohistochemistry, showing localization of MBL around CC clefts. Moreover, we demonstrated that IgM, but not IgG, bound to CC in vitro and that C1q binding was facilitated by IgM. In conclusion, our study demonstrates that PRMs from the lectin pathway recognize CC and provides evidence for an important role for this pathway in the inflammatory response induced by CC in the pathophysiology of atherosclerosis.
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Affiliation(s)
- Katrine Pilely
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen O, Denmark
| | - Anne Rosbjerg
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen O, Denmark
| | - Ninette Genster
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen O, Denmark
| | - Peter Gal
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences, 1113 Budapest, Hungary
| | - Gábor Pál
- Department of Biochemistry, Eötvös Loránd University, 1117 Budapest, Hungary
| | - Bente Halvorsen
- Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, 0424 Oslo, Norway; K.G. Jebsen Inflammation Research Center, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway
| | - Sverre Holm
- Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, 0424 Oslo, Norway; Hospital for Rheumatic Diseases, 2609 Lillehammer, Norway
| | - Pål Aukrust
- Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, 0424 Oslo, Norway; K.G. Jebsen Inflammation Research Center, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway
| | - Siril Skaret Bakke
- Center of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Bjørnar Sporsheim
- Center of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Ingunn Nervik
- Section for Children's and Women's Health, Department of Laboratory Medicine, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Nathalie Niyonzima
- Center of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Emil D Bartels
- Department of Clinical Biochemistry, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen O, Denmark
| | - Gregory L Stahl
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | - Tom Eirik Mollnes
- K.G. Jebsen Inflammation Research Center, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway; Department of Immunology, Oslo University Hospital Rikshospitalet, 0424 Oslo, Norway; Research Laboratory, Nordland Hospital, 8038 Bodø, Norway; and K.G. Jebsen Thrombosis Research and Expertise Center, University of Tromsø, 9019 Tromsø, Norway
| | - Terje Espevik
- Center of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Peter Garred
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen O, Denmark;
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20
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Moreau C, Bally I, Chouquet A, Bottazzi B, Ghebrehiwet B, Gaboriaud C, Thielens N. Structural and Functional Characterization of a Single-Chain Form of the Recognition Domain of Complement Protein C1q. Front Immunol 2016; 7:79. [PMID: 26973654 PMCID: PMC4774423 DOI: 10.3389/fimmu.2016.00079] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 02/18/2016] [Indexed: 11/17/2022] Open
Abstract
Complement C1q is a soluble pattern recognition molecule comprising six heterotrimeric subunits assembled from three polypeptide chains (A–C). Each heterotrimer forms a collagen-like stem prolonged by a globular recognition domain. These recognition domains sense a wide variety of ligands, including pathogens and altered-self components. Ligand recognition is either direct or mediated by immunoglobulins or pentraxins. Multivalent binding of C1q to its targets triggers immune effector mechanisms mediated via its collagen-like stems. The induced immune response includes activation of the classical complement pathway and enhancement of the phagocytosis of the recognized target. We report here, the first production of a single-chain recombinant form of human C1q globular region (C1q-scGR). The three monomers have been linked in tandem to generate a single continuous polypeptide, based on a strategy previously used for adiponectin, a protein structurally related to C1q. The resulting C1q-scGR protein was produced at high yield in stably transfected 293-F mammalian cells. Recombinant C1q-scGR was correctly folded, as demonstrated by its X-ray crystal structure solved at a resolution of 1.35 Å. Its interaction properties were assessed by surface plasmon resonance analysis using the following physiological C1q ligands: the receptor for C1q globular heads, the long pentraxin PTX3, calreticulin, and heparin. The 3D structure and the binding properties of C1q-scGR were similar to those of the three-chain fragment generated by collagenase digestion of serum-derived C1q. Comparison of the interaction properties of the fragments with those of native C1q provided insights into the avidity component associated with the hexameric assembly of C1q. The interest of this functional recombinant form of the recognition domains of C1q in basic research and its potential biomedical applications are discussed.
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Affiliation(s)
- Christophe Moreau
- IBS, University of Grenoble Alpes, Grenoble, France; CNRS, IBS, Grenoble, France; IBS, CEA, Grenoble, France
| | - Isabelle Bally
- IBS, University of Grenoble Alpes, Grenoble, France; CNRS, IBS, Grenoble, France; IBS, CEA, Grenoble, France
| | - Anne Chouquet
- IBS, University of Grenoble Alpes, Grenoble, France; CNRS, IBS, Grenoble, France; IBS, CEA, Grenoble, France
| | - Barbara Bottazzi
- Immunopharmacology Laboratory, Humanitas Research Hospital , Rozzano , Italy
| | | | - Christine Gaboriaud
- IBS, University of Grenoble Alpes, Grenoble, France; CNRS, IBS, Grenoble, France; IBS, CEA, Grenoble, France
| | - Nicole Thielens
- IBS, University of Grenoble Alpes, Grenoble, France; CNRS, IBS, Grenoble, France; IBS, CEA, Grenoble, France
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21
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Jiang S, Li H, Zhang D, Zhang H, Wang L, Sun J, Song L. A C1q domain containing protein from Crassostrea gigas serves as pattern recognition receptor and opsonin with high binding affinity to LPS. FISH & SHELLFISH IMMUNOLOGY 2015; 45:583-591. [PMID: 26002640 DOI: 10.1016/j.fsi.2015.05.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/10/2015] [Accepted: 05/11/2015] [Indexed: 06/04/2023]
Abstract
C1q proteins serve as pattern recognition receptors and involve in the pathogen recognition and complement pathway activation. In the present study, a novel C1q domain containing protein from Crassostrea gigas (designated CgC1qDC-1) was isolated by liposaccharide-Sepharose 6B affinity chromatography. The coding sequence of CgC1qDC-1 gene was determined by performing a homologous search of eight tryptic peptides identified by MALDI-TOF/TOF-MS against the genome of C. gigas. The coding sequence of CgC1qDC-1 was of 387 bp encoding a polypeptide of 128 amino acids containing a typical globular C1q domain. The globular C1q domain possessed eight β strands with a jelly-roll topology structure, which was similar to the structure of human gC1q domain. The mRNA transcripts of CgC1qDC-1 were dominantly expressed in mantle and hemocytes, while low expressed in hepatopancreas, gonad, gill and muscle. The expression level of CgC1qDC-1 increased drastically at 6 h after Vibrio splendidus stimulation, and then gradually fell to the normal level at about 24 h. ELISA assay quantified that CgC1qDC-1 bound to LPS with high binding affinity (Kd = 0.09 × 10(-6) M). Moreover, CgC1qDC-1 significantly enhanced the phagocytosis of oyster hemocytes towards Gram-negative bacteria Escherichia coli and V. splendidus. These results collectively indicated that CgC1qDC-1 could serve as pattern recognition receptor and opsonin in the innate immune response against invading Gram-negative bacteria.
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Affiliation(s)
- Shuai Jiang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Hui Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Daoxiang Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Huan Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Lingling Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Jinsheng Sun
- Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin 300387, China
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Klop B, van der Pol P, van Bruggen R, Wang Y, de Vries MA, van Santen S, O'Flynn J, van de Geijn GJM, Njo TL, Janssen HW, de Man P, Jukema JW, Rabelink TJ, Rensen PCN, van Kooten C, Cabezas MC. Differential complement activation pathways promote C3b deposition on native and acetylated LDL thereby inducing lipoprotein binding to the complement receptor 1. J Biol Chem 2014; 289:35421-30. [PMID: 25349208 DOI: 10.1074/jbc.m114.573840] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Lipoproteins can induce complement activation resulting in opsonization and binding of these complexes to complement receptors. We investigated the binding of opsonized native LDL and acetylated LDL (acLDL) to the complement receptor 1 (CR1). Binding of complement factors C3b, IgM, C1q, mannose-binding lectin (MBL), and properdin to LDL and acLDL were investigated by ELISA. Subsequent binding of opsonized LDL and acLDL to CR1 on CR1-transfected Chinese Hamster Ovarian cells (CHO-CR1) was tested by flow cytometry. Both native LDL and acLDL induced complement activation with subsequent C3b opsonization upon incubation with normal human serum. Opsonized LDL and acLDL bound to CR1. Binding to CHO-CR1 was reduced by EDTA, whereas MgEGTA only reduced the binding of opsonized LDL, but not of acLDL suggesting involvement of the alternative pathway in the binding of acLDL to CR1. In vitro incubations showed that LDL bound C1q, whereas acLDL bound to C1q, IgM, and properdin. MBL did neither bind to LDL nor to acLDL. The relevance of these findings was demonstrated by the fact that ex vivo up-regulation of CR1 on leukocytes was accompanied by a concomitant increased binding of apolipoprotein B-containing lipoproteins to leukocytes without changes in LDL-receptor expression. In conclusion, CR1 is able to bind opsonized native LDL and acLDL. Binding of LDL to CR1 is mediated via the classical pathway, whereas binding of acLDL is mediated via both the classical and alternative pathways. Binding of lipoproteins to CR1 may be of clinical relevance due to the ubiquitous cellular distribution of CR1.
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Affiliation(s)
- Boudewijn Klop
- From the Departments of Internal Medicine, Diabetes and Vascular Center
| | | | | | - Yanan Wang
- Department of Endocrinology and Metabolic Diseases, Einthoven Laboratory for Experimental Vascular Medicine, and
| | | | | | | | | | | | | | - Peter de Man
- Medical Microbiology, Sint Franciscus Gasthuis, 3004 BA Rotterdam, the Netherlands
| | - J Wouter Jukema
- Department of Cardiology, Leiden University Medical Center, 1006 AN Leiden, the Netherlands, and
| | | | - Patrick C N Rensen
- Department of Endocrinology and Metabolic Diseases, Einthoven Laboratory for Experimental Vascular Medicine, and
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Ma W, Paik DC, Barile GR. Bioactive lysophospholipids generated by hepatic lipase degradation of lipoproteins lead to complement activation via the classical pathway. Invest Ophthalmol Vis Sci 2014; 55:6187-93. [PMID: 25205869 DOI: 10.1167/iovs.14-14352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We determined bioactivity of lysophospholipids generated by degradation of the low-density (LDL), very low-density (VLDL), and high-density (HDL) lipoproteins with hepatic lipase (HL), cholesterol esterase (CE), and lipoprotein-associated phospholipase A2 (Lp-PLA2). METHODS The LDL, VLDL, and HDL were treated with HL, CE, and Lp-PLA2 after immobilization on plates, and complement activation studies were performed with diluted human serum. Complement component 3 (C3) fixation, a marker for complement activation, was determined with a monoclonal anti-human C3d antibody. Enzymatic properties of HL and CE were assayed with triglyceride and phosphatidylcholine substrates for triglyceride hydrolase and phospholipase A activities. The ARPE-19 cells were used for viability studies. RESULTS The HL degradation of human lipoproteins LDL, VLDL, or HDL results in the formation of modified lipoproteins that can activate the complement pathway. Complement activation is dose- and time-dependent upon HL and occurs via the classical pathway. Enzymatic studies suggest that the phospholipase A1 activity of HL generates complement-activating lysophospholipids. C-reactive protein (CRP), known to simultaneously interact with complement C1 and complement factor H (CFH), further enhances HL-induced complement activation. The lysophospholipids, 1-Palmitoyl-sn-glycero-3-phosphocholine and 1-Oleoyl-sn-glycero-3-phosphocholine, can be directly cytotoxic to ARPE-19 cells. CONCLUSIONS The HL degradation of lipoproteins, known to accumulate in the outer retina and in drusen, can lead to the formation of bioactive lysophospholipids that can trigger complement activation and induce RPE cellular dysfunction. Given the known risk associations for age-related macular degeneration (AMD) with HL, CRP, and CFH, this study elucidates a possible damage pathway for age-related macular degeneration (AMD) in genetically predisposed individuals, that HL activity may lead to accumulation of lysophospholipids to initiate complement activation, with CFH dysregulation exacerbating the effects of this process.
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Affiliation(s)
- Wanchao Ma
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - David C Paik
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Gaetano R Barile
- Department of Ophthalmology, Columbia University, New York, New York, United States
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24
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Bohlson SS, O'Conner SD, Hulsebus HJ, Ho MM, Fraser DA. Complement, c1q, and c1q-related molecules regulate macrophage polarization. Front Immunol 2014; 5:402. [PMID: 25191325 PMCID: PMC4139736 DOI: 10.3389/fimmu.2014.00402] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 08/07/2014] [Indexed: 12/22/2022] Open
Abstract
Complement is a critical system of enzymes, regulatory proteins, and receptors that regulates both innate and adaptive immune responses. Natural mutations in complement molecules highlight their requirement in regulation of a variety of human conditions including infectious disease and autoimmunity. As sentinels of the immune system, macrophages are specialized to respond to infectious microbes, as well as normal and altered self, and dictate appropriate immune responses. Complement components such as anaphylatoxins (C3a and C5a) and opsonins [C3b, C1q, mannan binding lectin (MBL)] influence macrophage responses. While anaphylatoxins C3a and C5a trigger inflammasome activation, opsonins such as C1q and related molecules (MBL and adiponectin) downregulate inflammasome activation and inflammation, and upregulate engulfment of apoptotic cells consistent with a pro-resolving or M2 macrophage phenotype. This review summarizes our current understanding of the influence of the complement system on macrophage polarization with an emphasis on C1q and related molecules.
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Affiliation(s)
- Suzanne S Bohlson
- Department of Microbiology and Immunology, Des Moines University , Des Moines, IA , USA
| | - Sean D O'Conner
- Department of Microbiology and Immunology, Des Moines University , Des Moines, IA , USA
| | - Holly Jo Hulsebus
- Department of Microbiology and Immunology, Des Moines University , Des Moines, IA , USA
| | - Minh-Minh Ho
- Department of Biologicial Sciences, California State University Long Beach , Long Beach, CA , USA
| | - Deborah A Fraser
- Department of Biologicial Sciences, California State University Long Beach , Long Beach, CA , USA
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25
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Recognition functions of pentameric C-reactive protein in cardiovascular disease. Mediators Inflamm 2014; 2014:319215. [PMID: 24948846 PMCID: PMC4052174 DOI: 10.1155/2014/319215] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 05/07/2014] [Accepted: 05/07/2014] [Indexed: 02/02/2023] Open
Abstract
C-reactive protein (CRP) performs two recognition functions that are relevant to cardiovascular disease. First, in its native pentameric conformation, CRP recognizes molecules and cells with exposed phosphocholine (PCh) groups, such as microbial pathogens and damaged cells. PCh-containing ligand-bound CRP activates the complement system to destroy the ligand. Thus, the PCh-binding function of CRP is defensive if it occurs on foreign pathogens because it results in the killing of the pathogen via complement activation. On the other hand, the PCh-binding function of CRP is detrimental if it occurs on injured host cells because it causes more damage to the tissue via complement activation; this is how CRP worsens acute myocardial infarction and ischemia/reperfusion injury. Second, in its nonnative pentameric conformation, CRP also recognizes atherogenic low-density lipoprotein (LDL). Recent data suggest that the LDL-binding function of CRP is beneficial because it prevents formation of macrophage foam cells, attenuates inflammatory effects of LDL, inhibits LDL oxidation, and reduces proatherogenic effects of macrophages, raising the possibility that nonnative CRP may show atheroprotective effects in experimental animals. In conclusion, temporarily inhibiting the PCh-binding function of CRP along with facilitating localized presence of nonnative pentameric CRP could be a promising approach to treat atherosclerosis and myocardial infarction. There is no need to stop the biosynthesis of CRP.
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26
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Complement monitoring of Pluronic 127 gel and micelles: Suppression of copolymer-mediated complement activation by elevated serum levels of HDL, LDL, and apolipoproteins AI and B-100. J Control Release 2013; 170:167-74. [DOI: 10.1016/j.jconrel.2013.05.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/23/2013] [Accepted: 05/28/2013] [Indexed: 01/06/2023]
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27
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Terrasse R, Tacnet-Delorme P, Moriscot C, Pérard J, Schoehn G, Vernet T, Thielens NM, Di Guilmi AM, Frachet P. Human and pneumococcal cell surface glyceraldehyde-3-phosphate dehydrogenase (GAPDH) proteins are both ligands of human C1q protein. J Biol Chem 2012; 287:42620-33. [PMID: 23086952 DOI: 10.1074/jbc.m112.423731] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C1q, a key component of the classical complement pathway, is a major player in the response to microbial infection and has been shown to detect noxious altered-self substances such as apoptotic cells. In this work, using complementary experimental approaches, we identified the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a C1q partner when exposed at the surface of human pathogenic bacteria Streptococcus pneumoniae and human apoptotic cells. The membrane-associated GAPDH on HeLa cells bound the globular regions of C1q as demonstrated by pulldown and cell surface co-localization experiments. Pneumococcal strains deficient in surface-exposed GAPDH harbored a decreased level of C1q recognition when compared with the wild-type strains. Both recombinant human and pneumococcal GAPDHs interacted avidly with C1q as measured by surface plasmon resonance experiments (K(D) = 0.34-2.17 nm). In addition, GAPDH-C1q complexes were observed by transmission electron microscopy after cross-linking. The purified pneumococcal GAPDH protein activated C1 in an in vitro assay unlike the human form. Deposition of C1q, C3b, and C4b from human serum at the surface of pneumococcal cells was dependent on the presence of surface-exposed GAPDH. This ability of C1q to sense both human and bacterial GAPDHs sheds new insights on the role of this important defense collagen molecule in modulating the immune response.
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Affiliation(s)
- Rémi Terrasse
- Pneumococcus (PG), Université Joseph Fourier Grenoble, France
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28
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Gaboriaud C, Frachet P, Thielens NM, Arlaud GJ. The human c1q globular domain: structure and recognition of non-immune self ligands. Front Immunol 2012; 2:92. [PMID: 22566881 PMCID: PMC3342031 DOI: 10.3389/fimmu.2011.00092] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 12/21/2011] [Indexed: 11/13/2022] Open
Abstract
C1q, the ligand-binding unit of the C1 complex of complement, is a pattern recognition molecule with the unique ability to sense an amazing variety of targets, including a number of altered structures from self, such as apoptotic cells. The three-dimensional structure of its C-terminal globular domain, responsible for its recognition function, has been solved by X-ray crystallography, revealing a tightly packed heterotrimeric assembly with marked differences in the surface patterns of the subunits, and yielding insights into its versatile binding properties. In conjunction with other approaches, this same technique has been used recently to decipher the mechanisms that allow this domain to interact with various non-immune self ligands, including molecules known to provide eat-me signals on apoptotic cells, such as phosphatidylserine and DNA. These investigations provide evidence for a common binding area for these ligands located in subunit C of the C1q globular domain, and suggest that ligand recognition through this area down-regulates C1 activation, hence contributing to the control of the inflammatory reaction. The purpose of this article is to give an overview of these advances which represent a first step toward understanding the recognition mechanisms of C1q and their biological implications.
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29
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Agrawal A, Hammond DJ, Singh SK. Atherosclerosis-related functions of C-reactive protein. Cardiovasc Hematol Disord Drug Targets 2011; 10:235-40. [PMID: 20932269 DOI: 10.2174/187152910793743841] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Accepted: 09/13/2010] [Indexed: 11/22/2022]
Abstract
C-reactive protein (CRP) is secreted by hepatocytes as a pentameric molecule made up of identical monomers, circulates in the plasma as pentamers, and localizes in atherosclerotic lesions. In some cases, localized CRP was detected by using monoclonal antibodies that did not react with native pentameric CRP but were specific for isolated monomeric CRP. It has been reported that, once CRP is bound to certain ligands, the pentameric structure of CRP is altered so that it can dissociate into monomers. Accordingly, the monomeric CRP found in atherosclerotic lesions may be a stationary, ligand-bound, by-product of a ligand-binding function of CRP. CRP binds to modified forms of low-density lipoprotein (LDL). The binding of CRP to oxidized LDL requires acidic pH conditions; the binding at physiological pH is controversial. The binding of CRP to enzymatically-modified LDL occurs at physiological pH; however, the binding is enhanced at acidic pH. Using enzymatically-modified LDL, CRP has been shown to prevent the formation of enzymatically-modified LDL-loaded macrophage foam cells. CRP is neither pro-atherogenic nor atheroprotective in ApoE⁻(/)⁻ and ApoB¹⁰⁰(/)¹⁰⁰Ldlr ⁻(/)⁻ murine models of atherosclerosis, except in one study where CRP was found to be slightly atheroprotective in ApoB¹⁰⁰(/)¹⁰⁰Ldlr ⁻(/)⁻ mice. The reasons for the ineffectiveness of human CRP in murine models of atherosclerosis are not defined. It is possible that an inflammatory environment, such as those characterized by acidic pH, is needed for efficient interaction between CRP and atherogenic LDL during the development of atherosclerosis and to observe the possible atheroprotective function of CRP in animal models.
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Affiliation(s)
- Alok Agrawal
- Department of Pharmacology, East Tennessee State University, Johnson City, TN 37614, USA.
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30
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Complement and non-complement activating functions of C1q: A prototypical innate immune molecule. Innate Immun 2011; 18:350-63. [DOI: 10.1177/1753425910396252] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
C1q is a versatile innate immune molecule that serves as the initiation subcomponent of the classical complement pathway. In addition, it is also a potent pattern recognition molecule, the versatility of which has fuelled its functional flexibility. C1q recognises an array of self, non-self and altered-self ligands. The broad-spectrum ligand-binding potential of C1q is facilitated by the modular organisation of the heterotrimeric globular head region, its ability to change its conformation in a very subtle way, and the manner in which this ancient molecule appears to have evolved to deal with the different types of ligands. Over recent years, molecules that resemble C1q have been put together to form the C1q family. In this review, we briefly summarise complement-dependent and complement-independent functions of C1q, its cognate receptors and key members of the rapidly growing C1q family.
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31
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Enzymatically modified low-density lipoprotein is recognized by c1q and activates the classical complement pathway. J Lipids 2011; 2011:376092. [PMID: 21490800 PMCID: PMC3066639 DOI: 10.1155/2011/376092] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 12/18/2010] [Indexed: 11/17/2022] Open
Abstract
Several studies suggest that the complement system is involved in atherogenesis. To further investigate this question, we have studied the ability of native and modified forms of LDL to bind and activate C1, the complex protease that triggers the classical pathway of complement. Unlike native LDL, oxidized (oxLDL) and enzymatically modified (E-LDL) derivatives were both recognized by the C1q subunit of C1, but only E-LDL particles, obtained by sequential treatment with a protease and then with cholesterol esterase, had the ability to trigger C1 activation. Further investigations revealed that C1q recognizes a lipid component of E-LDL. Several approaches, including reconstitution of model lipid vesicles, cosedimentation, and electron microscopy analyses, provided evidence that C1 binding to E-LDL particles is mediated by the C1q globular domain, which senses unesterified fatty acids generated by cholesterol esterase. The potential implications of these findings in atherogenesis are discussed.
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32
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Païdassi H, Tacnet-Delorme P, Verneret M, Gaboriaud C, Houen G, Duus K, Ling WL, Arlaud GJ, Frachet P. Investigations on the C1q-calreticulin-phosphatidylserine interactions yield new insights into apoptotic cell recognition. J Mol Biol 2011; 408:277-90. [PMID: 21352829 DOI: 10.1016/j.jmb.2011.02.029] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 02/02/2011] [Accepted: 02/11/2011] [Indexed: 02/09/2023]
Abstract
Both C1q and calreticulin (CRT) are involved in the recognition of apoptotic cells. CRT was initially characterized as a receptor for the C1q collagen-like fragment (CLF), whereas C1q was shown to bind apoptotic cells through its globular region (GR). Using purified CRT and recombinant CRT domains, we now provide unambiguous experimental evidence that, in addition to its CLF, the C1q GR also binds CRT and that both types of interactions are mediated by the CRT globular domain. Surface plasmon resonance analyses revealed that the C1q CLF and GR domains each bind individually to immobilized CRT and its globular domain with K(D) values of (2.6-8.3) × 10(-7) M. Further evidence that CRT binds to the C1q GR was obtained by electron microscopy. The role of CRT in the recognition of apoptotic HeLa cells by C1q was analyzed. The C1q GR partially colocalized with CRT on the surface of early apoptotic cells, and siRNA (small interfering RNA)-induced CRT deficiency resulted in increased apoptotic cell binding to C1q. The interaction between CRT and phosphatidylserine (PS), a known C1q ligand on apoptotic cells, was also investigated. The polar head of PS was shown to bind to CRT with a 10-fold higher affinity (K(D)=1.5 × 10(-5) M) than that determined for C1q, and, accordingly, the C1q GR-PS interaction was impaired in the presence of CRT. Together, these observations indicate that CRT, C1q, and PS are all closely involved in the uptake of apoptotic cells and strongly suggest a combinatorial role of these three molecules in the recognition step.
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Affiliation(s)
- Helena Païdassi
- Université Joseph Fourier Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble, France
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33
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Ling WL, Biro A, Bally I, Tacnet P, Deniaud A, Doris E, Frachet P, Schoehn G, Pebay-Peyroula E, Arlaud GJ. Proteins of the innate immune system crystallize on carbon nanotubes but are not activated. ACS NANO 2011; 5:730-737. [PMID: 21214219 DOI: 10.1021/nn102400w] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The classical pathway of complement is an essential component of the human innate immune system involved in the defense against pathogens as well as in the clearance of altered self-components. Activation of this pathway is triggered by C1, a multimolecular complex comprising a recognition protein C1q associated with a catalytic subunit C1s-C1r-C1r-C1s. We report here the direct observation of organized binding of C1 components C1q and C1s-C1r-C1r-C1s on carbon nanotubes, an ubiquitous component in nanotechnology research. Electron microscopy imaging showed individual multiwalled carbon nanotubes with protein molecules organized along the length of the sidewalls, often over 1 μm long. Less well-organized protein attachment was also observed on double-walled carbon nanotubes. Protein-solubilized nanotubes continued to attract protein molecules after their surface was fully covered. Despite the C1q binding properties, none of the nanotubes activated the C1 complex. We discuss these results on the adsorption mechanisms of macromolecules on carbon nanotubes and the possibility of using carbon nanotubes for structural studies of macromolecules. Importantly, the observations suggest that carbon nanotubes may interfere with the human immune system when entering the bloodstream. Our results raise caution in the applications of carbon nanotubes in biomedicine but may also open possibilities of novel applications concerning the many biochemical processes involving the versatile C1 macromolecule.
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Affiliation(s)
- Wai Li Ling
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble, France.
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34
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Fraser DA, Tenner AJ. Innate immune proteins C1q and mannan-binding lectin enhance clearance of atherogenic lipoproteins by human monocytes and macrophages. THE JOURNAL OF IMMUNOLOGY 2010; 185:3932-9. [PMID: 20833838 DOI: 10.4049/jimmunol.1002080] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Atherosclerosis is a chronic inflammatory disorder that is characterized by the accumulation of modified lipoproteins in the arterial intima. C1q and mannan-binding lectin (MBL) are not only recognition components involved in activation of inflammation via the complement cascade, but they are also able to directly modulate phagocyte activation. Studies in C1q(-/-) and MBL(-/-) mice suggest that these molecules play a protective role in the early atherosclerotic lesion in the absence of, or prior to, expression of other complement components. However, in later stages, complement activation becomes an inappropriate inflammatory response, contributing to disease pathology. Therefore, to investigate possible molecular interactions of C1q and MBL in atherosclerotic lesions, we examined the influence of C1q and MBL in the clearance of native and modified lipoproteins by human monocytes and monocyte-derived macrophages. Both C1q and MBL are shown to bind and enhance the monocyte/monocyte-derived macrophage clearance of modified forms of low-density lipoprotein (LDL), including oxidized LDL and acetylated LDL, but not native LDL. Modified forms of LDL activate the classical complement pathway, but no lectin pathway activation was detected. Interestingly, monocytes that ingested modified LDL in the presence of C1q or MBL upregulated surface CD80 and CD31, as well as CCL2 chemokine gene expression. However, C1q and MBL also significantly reduced levels of free cholesterol accumulation in monocytes and human monocyte-derived macrophages that ingested oxidized LDL, while enhancing high-density lipoprotein-specific cholesterol efflux from these cells. These results suggest a novel pathway in which C1q and MBL influence removal and metabolism of atherogenic forms of LDL in the early stages of atherosclerosis.
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Affiliation(s)
- Deborah A Fraser
- Department of Molecular Biology and Biochemistry, Institute for Immunology, University of California, Irvine, CA 92697, USA.
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35
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Erlich P, Dumestre-Pérard C, Ling WL, Lemaire-Vieille C, Schoehn G, Arlaud GJ, Thielens NM, Gagnon J, Cesbron JY. Complement protein C1q forms a complex with cytotoxic prion protein oligomers. J Biol Chem 2010; 285:19267-76. [PMID: 20410306 DOI: 10.1074/jbc.m109.071860] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A growing number of studies have investigated the interaction between C1q and PrP, but the oligomeric form of PrP involved in this interaction remains to be determined. Aggregation of recombinant full-length murine PrP in the presence of 100 mm NaCl allowed us to isolate three different types of oligomers by size-exclusion chromatography. In contrast to PrP monomers and fibrils, these oligomers activate the classical complement pathway, the smallest species containing 8-15 PrP protomers being the most efficient. We used Thioflavine T fluorescence to monitor PrP aggregation and showed that, when added to the reaction, C1q has a cooperative effect on PrP aggregation and leads to the formation of C1q-PrP complexes. In these complexes, C1q interacts through its globular domains preferentially with the smallest oligomers, as shown by electron microscopy, and retains the ability to activate the classical complement pathway. Using two cell lines, we also provide evidence that C1q inhibits the cytotoxicity induced by the smallest PrP oligomers. The cooperative interaction between C1q and PrP could represent an early step in the disease, where it prevents elimination of the prion seed, leading to further aggregation.
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Affiliation(s)
- Paul Erlich
- Laboratoire Adaptation et Pathogénie des Micro-organismes, Université Joseph Fourier, 38042 Grenoble cedex 9, France
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36
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Biro A, Ling WL, Arlaud GJ. Complement Protein C1q Recognizes Enzymatically Modified Low-Density Lipoprotein through Unesterified Fatty Acids Generated by Cholesterol Esterase. Biochemistry 2010; 49:2167-76. [DOI: 10.1021/bi9021022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Wai Li Ling
- Laboratoire de Microscopie Electronique Structurale
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Tulamo R, Frösen J, Junnikkala S, Paetau A, Kangasniemi M, Peláez J, Hernesniemi J, Niemelä M, Meri S. Complement system becomes activated by the classical pathway in intracranial aneurysm walls. J Transl Med 2010; 90:168-79. [PMID: 19997064 DOI: 10.1038/labinvest.2009.133] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Inflammation and activation of the complement system in the intracranial aneurysm (IA) wall predispose to IA rupture. We have previously shown that increased C5b-9 accumulation correlates with IA rupture and wall degeneration. To elucidate the underlying mechanisms, we investigated initiators and the pathway of complement activation in unruptured and ruptured IAs. Unruptured and ruptured IA wall samples were studied in parallel sections by immunohistochemical and immunofluorescence stainings for the location and relations of classical and alternative pathway complement components (C1q, C3b/iC3b, C3d, C4b/iC4b; n=35 and properdin, n=10), putative complement activators IgG (n=90), IgM, CRP and OxLDL (n=10), and complement activation endproduct C5b-9. Classical pathway components were seen in all IAs, and they were located mostly in the extracellular matrix. The early pathway complement components colocalized with each other, but were present in larger areas than C5b-9. The areas positive for complement component accumulation were significantly broader in ruptured than in unruptured IAs. The potential complement activators IgG, IgM, CRP and OxLDL were found mostly in the extracellular matrix and in partial overlap with C5b-9. Lipids were seen in Oil-Red-O staining in colocalization with C5b-9. Complement becomes activated by the classical pathway in the IA wall. The activation appears to be induced by multiple factors, which, in addition to the traditional activators (immunoglobulins, CRP, OxLDL), could involve vascular pressure-induced tissue damage. Despite wide early pathway activation, the terminal pathway is focused on a distinct lipid-rich layer. The profile of the complement components and the association of C5b-9 with lipids in the extracellular matrix indicate a long-term chronic inflammatory process rather than an acute targeted inflammatory reaction. The observed pattern of complement activation may be the consequence of local stress-induced insufficiency of complement regulation in IA walls.
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Affiliation(s)
- Riikka Tulamo
- Neurosurgery Research Group, Biomedicum Helsinki, Helsinki, Huch FI-00029, Finland.
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Hair PS, Gronemus JQ, Crawford KB, Salvi VP, Cunnion KM, Thielens NM, Arlaud GJ, Rawal N, Krishna NK. Human astrovirus coat protein binds C1q and MBL and inhibits the classical and lectin pathways of complement activation. Mol Immunol 2009; 47:792-8. [PMID: 19896716 DOI: 10.1016/j.molimm.2009.10.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 10/06/2009] [Indexed: 02/07/2023]
Abstract
Human astroviruses (HAstVs) constitute a family of non-enveloped, RNA viruses which cause infantile gastroenteritis. We have previously demonstrated that purified HAstV coat protein (CP), multiple copies of which compose the viral capsid, bind C1q resulting in inhibition of classical complement pathway activity. The objective of this study was to further analyze the mechanism by which CP inhibits C1 activation. CP inhibited C1 activation, preventing cleavage of C1s to its active form in the presence of heat-aggregated IgG, a potent classical pathway activator. CP also inhibited generation of the potent anaphylatoxin C5a. CP dose-dependently bound to C1q, the isolated globular heads and the collagen-like regions of the C1q molecule. When CP was added to C1, C1s dissociated from C1q suggesting that CP functionally displaces the protease tetramer (C1s-C1r-C1r-C1s). Given the structural and functional relatedness of C1q and MBL, we subsequently investigated the interactions between CP and MBL. CP bound to purified MBL and was able to inhibit mannan-mediated activation of the lectin pathway. Interestingly, CP did not bind to a variant of MBL that replaces a lysine residue (Lys55) critical for binding to MASP-2, a functional homolog of C1s. Finally, CP was shown to cross the species barrier to inhibit C3 activation and MAC formation in rat serum. These findings suggest CP inhibits C1 and MBL activation via a novel mechanism of interference with the normal interaction of the recognition molecule with its cognate serine proteases.
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Affiliation(s)
- Pamela S Hair
- Department of Pediatrics, Eastern Virginia Medical School, 855 West Brambleton Avenue, Norfolk, VA 23510, United States
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Leung VWY, Yun S, Botto M, Mason JC, Malik TH, Song W, Paixao-Cavalcante D, Pickering MC, Boyle JJ, Haskard DO. Decay-accelerating factor suppresses complement C3 activation and retards atherosclerosis in low-density lipoprotein receptor-deficient mice. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 175:1757-67. [PMID: 19729477 DOI: 10.2353/ajpath.2009.090183] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Decay-accelerating factor (DAF; CD55) is a membrane protein that regulates complement pathway activity at the level of C3. To test the hypothesis that DAF plays an essential role in limiting complement activation in the arterial wall and protecting from atherosclerosis, we crossed DAF gene targeted mice (daf-1(-/-)) with low-density lipoprotein-receptor deficient mice (Ldlr(-/-)). Daf-1(-/-)Ldlr(-/-) mice had more extensive en face Sudan IV staining of the thoracoabdominal aorta than Ldlr(-/-) mice, both following a 12-week period of low-fat diet or a high-fat diet. Aortic root lesions in daf-1(-/-)Ldlr(-/-) mice on a low-fat diet showed increased size and complexity. DAF deficiency increased deposition of C3d and C5b-9, indicating the importance of DAF for downstream complement regulation in the arterial wall. The acceleration of lesion development in the absence of DAF provides confirmation of the proinflammatory and proatherosclerotic potential of complement activation in the Ldlr(-/-) mouse model. Because upstream complement activation is potentially protective, this study underlines the importance of DAF in shielding the arterial wall from the atherogenic effects of complement.
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Affiliation(s)
- Viola W Y Leung
- Vascular Science Section, Imperial College, National Heart and Lung Institute, the Division of Investigative Sciences, Imperial College London, Hammersmith Hospital, London W12 0NN, United Kingdom
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40
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Singh SK, Suresh MV, Hammond DJ, Rusiñol AE, Potempa LA, Agrawal A. Binding of the monomeric form of C-reactive protein to enzymatically-modified low-density lipoprotein: effects of phosphoethanolamine. Clin Chim Acta 2009; 406:151-5. [PMID: 19545552 DOI: 10.1016/j.cca.2009.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 06/11/2009] [Accepted: 06/12/2009] [Indexed: 01/11/2023]
Abstract
BACKGROUND The 5 subunits of native pentameric C-reactive protein (CRP) are dissociated to generate the monomeric form of CRP (mCRP) in some in vitro conditions, both physiological and non-physiological, and also in vivo. Many bioactivities of mCRP generated by urea-treatment of CRP and of mCRP generated by mutating the primary structure of CRP have been reported. The bioactivities of mCRP generated by spontaneous dissociation of CRP are largely unexplored. METHODS We purified mCRP generated by spontaneous dissociation of CRP and investigated the binding of mCRP to enzymatically-modified low-density lipoprotein (E-LDL). RESULTS mCRP was approximately 60 times more potent than CRP in binding to E-LDL. In the presence of the small-molecule compound phosphoethanolamine (PEt), at 37 degrees C, the binding of mCRP to E-LDL was enhanced <2-fold, while the binding of CRP to E-LDL was enhanced >10-fold. In contrast, PEt inhibited the binding of both CRP and mCRP to pneumococcal C-polysaccharide, another phosphocholine-containing ligand to which CRP and mCRP were found to bind. We have not investigated yet whether PEt alters the structure of CRP at 37 degrees C. CONCLUSIONS Combined data suggest that the targeting of CRP with the aim to monomerize CRP in vivo may be an effective approach to capture modified forms of LDL.
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Affiliation(s)
- Sanjay K Singh
- Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States
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41
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Macrophage-Specific Expression of Mannose-Binding Lectin Controls Atherosclerosis in Low-Density Lipoprotein Receptor–Deficient Mice. Circulation 2009; 119:2188-95. [DOI: 10.1161/circulationaha.108.830661] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Background—
With consideration of the central role of the innate immune system in atherogenesis and mannose-binding lectin (MBL) as an innate regulator of immunity, the role of MBL in experimental and human atherosclerosis was assessed.
Methods and Results—
With the use of immunohistochemistry and polymerase chain reaction, deposition and gene expression of MBL-A and -C were assessed in murine atherosclerosis from mice deficient for the low-density lipoprotein receptor (LDLR
−/−
) after 10 or 18 weeks of high-fat feeding. MBL was present and was produced in 10-week-old lesions, whereas deposition and gene expression were minimal after 18 weeks of high-fat feeding and absent in healthy vasculature. Interestingly, deposition of MBL-A and -C differed: MBL-A predominantly localized in upper medial layers, whereas MBL-C was found in and around intimal macrophages. To further study the role of local MBL production by monocytic cells in atherosclerosis, LDLR
−/−
mice with MBL-A and -C
−/−
monocytic cells were construed by bone marrow transplantation. Mice carrying MBL-A and -C double deficient macrophages had increased (30%) atherosclerotic lesions compared with wild-type controls (
P
=0.015) after 10 weeks of high-fat diet. Subsequently, analysis of MBL deposition and gene expression in advanced human atherosclerotic lesions revealed the presence of MBL protein in ruptured but not stable atherosclerotic lesions. Putatively in agreement with murine data, no MBL gene expression could be detected in advanced human atherosclerotic lesions.
Conclusions—
These results are the first to show that MBL is abundantly present and locally produced during early atherogenesis. Local MBL expression, by myeloid cells, is shown to critically control development of atherosclerotic lesions.
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Wu G, Hu W, Shahsafaei A, Song W, Dobarro M, Sukhova GK, Bronson RR, Shi GP, Rother RP, Halperin JA, Qin X. Complement regulator CD59 protects against atherosclerosis by restricting the formation of complement membrane attack complex. Circ Res 2009; 104:550-8. [PMID: 19131645 DOI: 10.1161/circresaha.108.191361] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Complement is a central effector system within the immune system and is implicated in a range of inflammatory disorders. CD59 is a key regulator of complement membrane attack complex (MAC) assembly. The atherogenic role of terminal complement has long been suspected but is still unclear. Here, we demonstrate that among mice deficient in apolipoprotein (Apo)E, the additional loss of murine CD59 (mCd59ab(-/-)/ApoE(-/-)) accelerated advanced atherosclerosis featuring occlusive coronary atherosclerosis, vulnerable plaque, and premature death and that these effect could be attenuated by overexpression of human CD59 in the endothelium. Complement inhibition using a neutralizing anti-mouse C5 antibody attenuated atherosclerosis in mCd59ab(-/-)/ApoE(-/-) mice. Furthermore, MAC mediated endothelial damage and promoted foam cell formation. These combined results highlight the atherogenic role of MAC and the atheroprotective role of CD59 and suggest that inhibition of MAC formation may provide a therapeutic approach for the treatment of atherosclerosis.
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Affiliation(s)
- Gongxiong Wu
- Department of Medicine, Brigham and Women's Hospital, Laboratory forTranslational Research, Harvard Medical School, Cambridge, MA 02139, USA
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43
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Cyclosporine A aggravates vascular endothelial injury in hyperlipidemic rats by down-regulating decay-accelerating factor. Biochem Biophys Res Commun 2009; 379:27-31. [DOI: 10.1016/j.bbrc.2008.11.153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 11/26/2008] [Indexed: 11/21/2022]
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44
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Rich RL, Myszka DG. Survey of the year 2007 commercial optical biosensor literature. J Mol Recognit 2008; 21:355-400. [DOI: 10.1002/jmr.928] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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45
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Abstract
PURPOSE OF REVIEW Although it has long been recognized that atherosclerotic lesions show evidence of complement activation, the functional roles of the complement system in atherogenesis are not yet fully resolved. This article highlights recent publications on the complement system in the atherosclerosis field. RECENT FINDINGS There have been a number of recent papers reporting on the association of complement proteins and complement regulators with high density lipoproteins, complement activation by enzymatically-modified LDL, signalling pathways downstream of C3a and C5a receptors and membrane C5b-9 assembly, and the prevention of C5b-9 assembly on endothelial cells via upregulation of CD59 expression in response to arterial laminar flow. C1q has been found to play a protective role in early lesion formation in LDL receptor deficient mice, and Crry-Ig and soluble C1 inhibitor have both been shown to have therapeutic effects in models of vascular injury in ApoE deficient mice. The possibility that the Y402H Factor H polymorphism influences atherosclerosis has been supported in a recent paper showing increased risk in white hypertensive individuals. SUMMARY The articles that have emerged over the last year highlight the relevance of the complement system to the atherosclerosis field.
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Affiliation(s)
- Dorian O Haskard
- Bywaters Centre for Vascular Inflammation, National Heart and Lung Institute, Imperial College, Hammersmith Hospital, London, UK.
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46
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Bibliography. Current world literature. Atherosclerosis: cell biology and lipoproteins. Curr Opin Lipidol 2008; 19:525-35. [PMID: 18769235 DOI: 10.1097/mol.0b013e328312bffc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Païdassi H, Tacnet-Delorme P, Lunardi T, Arlaud GJ, Thielens NM, Frachet P. The lectin-like activity of human C1q and its implication in DNA and apoptotic cell recognition. FEBS Lett 2008; 582:3111-6. [PMID: 18703056 DOI: 10.1016/j.febslet.2008.08.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 07/24/2008] [Accepted: 08/05/2008] [Indexed: 12/16/2022]
Abstract
C1q, the binding subunit of the C1 complex of complement, is an archetypal pattern recognition molecule known for its striking ability to recognize a wide variety of targets, ranging from pathogenic non self to altered self. DNA is one of the C1q ligands, but the precise region of C1q and the DNA motifs that support interaction have not been characterized yet. Here, we report for the first time that the peripheral globular region of the C1q molecule displays a lectin-like activity, which contributes to DNA binding through interaction with its deoxy-d-ribose moiety and may participate in apoptotic cell recognition.
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Affiliation(s)
- Helena Païdassi
- Institut de Biologie Structurale Jean-Pierre Ebel, F-38027 Grenoble Cedex 1, France
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48
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Singh SK, Suresh MV, Prayther DC, Moorman JP, Rusiñol AE, Agrawal A. C-reactive protein-bound enzymatically modified low-density lipoprotein does not transform macrophages into foam cells. THE JOURNAL OF IMMUNOLOGY 2008; 180:4316-22. [PMID: 18322245 DOI: 10.4049/jimmunol.180.6.4316] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The formation of low-density lipoprotein (LDL) cholesterol-loaded macrophage foam cells contributes to the development of atherosclerosis. C-reactive protein (CRP) binds to atherogenic forms of LDL, but the role of CRP in foam cell formation is unclear. In this study, we first explored the binding site on CRP for enzymatically modified LDL (E-LDL), a model of atherogenic LDL to which CRP binds. As reported previously, phosphocholine (PCh) inhibited CRP-E-LDL interaction, indicating the involvement of the PCh-binding site of CRP in binding to E-LDL. However, the amino acids Phe66 and Glu81 in CRP that participate in CRP-PCh interaction were not required for CRP-E-LDL interaction. Surprisingly, blocking of the PCh-binding site with phosphoethanolamine (PEt) dramatically increased the binding of CRP to E-LDL. The PEt-mediated enhancement in the binding of CRP to E-LDL was selective for E-LDL because PEt inhibited the binding of CRP to another PCh-binding site-ligand pneumococcal C-polysaccharide. Next, we investigated foam cell formation by CRP-bound E-LDL. We found that, unlike free E-LDL, CRP-bound E-LDL was inactive because it did not transform macrophages into foam cells. The function of CRP in eliminating the activity of E-LDL to form foam cells was not impaired by the presence of PEt. Combined data lead us to two conclusions. First, PEt is a useful compound because it potentiates the binding of CRP to E-LDL and, therefore, increases the efficiency of CRP to prevent transformation of macrophages into E-LDL-loaded foam cells. Second, the function of CRP to prevent formation of foam cells may influence the process of atherogenesis.
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Affiliation(s)
- Sanjay K Singh
- Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
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49
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Singh SK, Suresh MV, Prayther DC, Moorman JP, Rusiñol AE, Agrawal A. Phosphoethanolamine-complexed C-reactive protein: a pharmacological-like macromolecule that binds to native low-density lipoprotein in human serum. Clin Chim Acta 2008; 394:94-8. [PMID: 18486609 DOI: 10.1016/j.cca.2008.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/16/2008] [Accepted: 04/16/2008] [Indexed: 11/19/2022]
Abstract
BACKGROUND C-reactive protein (CRP) is an acute phase plasma protein. An important binding specificity of CRP is for the modified forms of low-density lipoprotein (LDL) in which the phosphocholine-binding sites of CRP participate. CRP, however, does not bind to native LDL. METHODS We investigated the interaction of CRP with native LDL using sucrose density gradient ultracentrifugation. RESULTS We found that the blocking of the phosphocholine-binding sites of CRP with phosphoethanolamine (PEt) converted CRP into a potent molecule for binding to native LDL. In the presence of PEt, CRP acquired the ability to bind to fluid-phase purified native LDL. Because purified native LDL may undergo subtle modifications, we also used whole human serum as the source of native LDL. In the presence of PEt, CRP bound to native LDL in serum also. The effect of PEt on CRP was selective for LDL because PEt-complexed CRP did not bind to high-density lipoprotein in the serum. CONCLUSIONS The pharmacologic intervention of endogenous CRP by PEt-based compounds, or the use of exogenously prepared CRP-PEt complexes, may turn out to be an effective approach to capture native LDL cholesterol in vivo to prevent the development of atherosclerosis.
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Affiliation(s)
- Sanjay K Singh
- Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
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50
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Abstract
The connection between C-reactive protein (CRP) and atherosclerosis lies on three grounds. First, the concentration of CRP in the serum, which is measured by using highly sensitive (a.k.a. 'hs') techniques, correlates with the occurrence of cardiovascular disease. Second, although CRP binds only to Fcgamma receptor-bearing cells and, in general, to apoptotic and damaged cells, almost every type of cultured mammalian cells has been shown to respond to CRP treatment. Many of these responses indicate proatherogenic functions of CRP but are being reinvestigated using CRP preparations that are free of endotoxins, sodium azide, and biologically active peptides derived from the protein itself. Third, CRP binds to modified forms of low-density lipoprotein (LDL), and, when aggregated, CRP can bind to native LDL as well. Accordingly, CRP is seen with LDL and damaged cells at the atherosclerotic lesions and myocardial infarcts. In experimental rats, human CRP was found to increase the infarct size, an effect that could be abrogated by blocking CRP-mediated complement activation. In the Apob (100/100) Ldlr (-/-) murine model of atherosclerosis, human CRP was shown to be atheroprotective, and the importance of CRP-LDL interactions in this protection was noted. Despite all this, at the end, the question whether CRP can protect humans from developing atherosclerosis remains unanswered.
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Affiliation(s)
- Sanjay K Singh
- Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
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