scholarly journals C-Reactive Protein Uptake by Macrophage Cell Line via Class-A Scavenger Receptor

2010 ◽  
Vol 56 (3) ◽  
pp. 478-481 ◽  
Author(s):  
Yoshiko Fujita ◽  
Akemi Kakino ◽  
Mariko Harada-Shiba ◽  
Yuko Sato ◽  
Kazunori Otsui ◽  
...  
Keyword(s):  
Cell Line ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Scavenger Receptors ◽  
Dependent Manner ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Class A ◽  
Class A Scavenger Receptor

Abstract Background: C-reactive protein (CRP) increases in response to inflammation and is purported to be a risk factor for atherogenesis. We recently demonstrated that a scavenger receptor, lectin-like oxidized LDL receptor (LOX-1), is a receptor for CRP. In light of the overlapping ligand spectrum of scavenger receptors such as modified LDL, bacteria, and advanced glycation end products, we examined whether other scavenger receptors recognize CRP. Methods: We analyzed the uptake of fluorescently labeled CRP in COS-7 cells expressing a series of scavenger receptors and in a monocytic cell line, THP-1, differentiated into macrophage with phorbol 12-myristate 13-acetate (PMA). We applied small interfering RNA (siRNA) against class-A scavenger receptor (SR-A) to THP-1 cells to suppress the expression of SR-A. We also analyzed the binding of nonlabeled CRP to immobilized recombinant LOX-1 and SR-A in vitro using anti-CRP antibody. Results: COS-7 cells expressing LOX-1 and SR-A internalized fluorescently labeled CRP in a dose-dependent manner, but cells expressing CD36, SR-BI, or CD68 did not. The recombinant LOX-1 and SR-A proteins recognized nonlabeled purified CRP and native CRP in serum in vitro. THP-1 cells differentiated into macrophage-like cells by treatment with PMA-internalized fluorescently labeled CRP. siRNA against SR-A significantly and concomitantly inhibited the expression of SR-A (P < 0.01) and CRP uptake (P < 0.01), whereas control siRNA did not. Conclusions: CRP is recognized by SR-A as well as LOX-1 and taken up via SR-A in a macrophage-like cell line. This process might be of significance in the pathogenesis of atherosclerotic disease.

scholarly journals C-Reactive Protein Induces Release of Both Endothelial Microparticles and Circulating Endothelial Cells In Vitro and In Vivo: Further Evidence of Endothelial Dysfunction

2011 ◽  
Vol 57 (12) ◽  
pp. 1757-1761 ◽  
Author(s):  
Sridevi Devaraj ◽  
Pappanaicken R Kumaresan ◽  
Ishwarlal Jialal
Keyword(s):  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Oxidized Ldl ◽  
Circulating Endothelial Cells ◽  
Early Event ◽  
C Reactive Protein ◽  
Endothelial Microparticles ◽  
Reactive Protein

BACKGROUND Inflammation is pivotal in atherosclerosis. A key early event in atherosclerosis is endothelial dysfunction. C-reactive protein (CRP), the prototypic marker of inflammation in humans, is a risk marker for cardiovascular disease, and there is mounting evidence to support its role in atherothrombosis. CRP has been shown to promote endothelial dysfunction both in vitro and in vivo. Emerging biomarkers of endothelial dysfunction include circulating endothelial cells (CECs) and endothelial microparticles (EMPs). However, there is a paucity of data examining the effect of CRP on CEC and EMP production in vitro and in vivo. METHODS In this report, we treated human aortic endothelial cells (HAECs) with increasing concentrations of CRP (0–50 μg/mL) or boiled CRP. We counted CECs and EMPs by flow cytometry. RESULTS Although CRP treatment resulted in a significant increase in release of both CECs and EMPs, boiled CRP failed to have an effect. Pretreatment of HAECs with sepiapterin or diethylenetriamine NONOate, both of which preserve nitric oxide (NO), resulted in attenuation of CRP's effects on CECs and EMPs. CD32 and CD64 blocking antibodies but not CD16 antibody or lectin-like oxidized LDL receptor 1 small interfering RNA (LOX-1 siRNA) prevented CRP-induced production of CECs and EMPs. Furthermore, delivery of human CRP to Wistar rats compared with human serum albumin resulted in significantly increased CECs and EMPs, corroborating the in vitro findings. CONCLUSIONS We provide novel data that CRP, via NO deficiency, promotes endothelial dysfunction by inducing release of CECs and EMPs, which are biomarkers of endothelial dysfunction.

Scavenger receptor class A type I/II (CD204) null mice fail to develop fibrosis following silica exposure

2005 ◽  
Vol 289 (2) ◽  
pp. L186-L195 ◽  
Author(s):  
Celine A. Beamer ◽  
Andrij Holian
Keyword(s):  
Scavenger Receptor ◽  
Lavage Fluid ◽  
Type I ◽  
Dependent Manner ◽  
Wild Type ◽  
Focal Lesions ◽  
Silica Exposure ◽  
Class A

Alveolar macrophages express the class A scavenger receptor (CD204) (Babaev VR, Gleaves LA, Carter KJ, Suzuki H, Kodama T, Fazio S, and Linton MF. Arterioscler Thromb Vasc Biol 20: 2593–2599, 2000); yet its role in vivo in lung defense against environmental particles has not been clearly defined. In the current study, CD204 null mice (129Sv background) were used to investigate the link between CD204 and downstream events of inflammation and fibrosis following silica exposure in vivo. CD204−/− macrophages were shown to recognize and uptake silica in vitro, although this response was attenuated compared with 129Sv wild-type mice. The production of tumor necrosis factor-α in lavage fluid was significantly enhanced in CD204 null mice compared with wild-type mice following silica exposure. Moreover, after exposure to environmental particles, CD204−/− macrophages exhibited improved cell viability in a dose-dependent manner compared with wild-type macrophages. Finally, histopathology from a murine model of chronic silicosis in 129Sv wild-type mice displayed typical focal lesions, interstitial thickening with increased connective tissue matrix, and cellular infiltrate into air space. In contrast, CD204−/− mice exhibited little to no deposition of collagen, yet they demonstrated enhanced accumulation of inflammatory cells largely composed of neutrophils. Our findings point to an important role of CD204 in mounting an efficient and appropriately regulated immune response against inhaled particles. Furthermore, these results indicate that the functions of CD204 are critical to the development of fibrosis and the resolution of inflammation.

scholarly journals C reactive protein impairs adaptive immunity in immune cells of patients with melanoma

2020 ◽  
Vol 8 (1) ◽  
pp. e000234
Author(s):  
Tatsuya Yoshida ◽  
Junya Ichikawa ◽  
Iulia Giuroiu ◽  
Andressa S Laino ◽  
Yuhan Hao ◽  
...  
Keyword(s):  
T Cells ◽  
Adaptive Immunity ◽  
Cd8 T Cells ◽  
Immune Checkpoint ◽  
Dependent Manner ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Link Type ◽  
Serum Crp

BackgroundHigh C reactive protein (CRP) levels have been reported to be associated with a poor clinical outcome in a number of malignancies and with programmed cell death protein 1 immune checkpoint blockade in patients with advanced cancer. Little is known about the direct effects of CRP on adaptive immunity in cancer. Therefore, we investigated how CRP impacted the function of T cells and dendritic cells (DCs) from patients with melanoma.MethodsThe effects of CRP on proliferation, function, gene expression and phenotype of patient T cells and DCs, and expansion of MART-1 antigen-specific T cells were analyzed by multicolor flow cytometry and RNA-seq. Additionally, serum CRP levels at baseline from patients with metastatic melanoma treated on the Checkmate-064 clinical trial were assessed by a Luminex assay.ResultsIn vitro, CRP inhibited proliferation, activation-associated phenotypes and the effector function of activated CD4+ and CD8+ T cells from patients with melanoma. CRP-treated T cells expressed high levels of interleukin-1β, which is known to enhance CRP production from the liver. CRP also suppressed formation of the immune synapse and inhibited early events in T-cell receptor engagement. In addition, CRP downregulated the expression of costimulatory molecules on mature DCs and suppressed expansion of MART-1-specific CD8+ T cells in a dose-dependent manner by impacting on both T cells and antigen-presenting cells. High-serum CRP levels at baseline were significantly associated with a shorter survival in both nivolumab-treated and ipilimumab-treated patients.ConclusionsThese findings suggest that high levels of CRP induce an immunosuppressivemilieuin melanoma and support the blockade of CRP as a therapeutic strategy to enhance immune checkpoint therapies in cancer.Trial registration numberNCT01783938andNCT02983006.

scholarly journals Class A Scavenger Receptor-mediated Macrophage Adhesion Requires Coupling of Calcium-independent Phospholipase A2 and 12/15-Lipoxygenase to Rac and Cdc42 Activation

2007 ◽  
Vol 282 (46) ◽  
pp. 33405-33411 ◽  
Author(s):  
Dejan M. Nikolic ◽  
Ming C. Gong ◽  
John Turk ◽  
Steven R. Post
Keyword(s):  
Actin Polymerization ◽  
Inflammatory Responses ◽  
Scavenger Receptor ◽  
Matrix Proteins ◽  
Scavenger Receptors ◽  
Class A ◽  
Macrophage Adhesion ◽  
Calcium Independent Phospholipase A2 ◽  
Dependent Pathway ◽  
Class A Scavenger Receptor

Class A scavenger receptors (SR-A) participate in multiple macrophage functions including adhesion to modified extracellular matrix proteins present in various inflammatory disorders such as atherosclerosis and diabetes. By mediating macrophage adhesion to modified proteins and increasing macrophage retention, SR-A may contribute to the inflammatory process. Eicosanoids produced after phospholipase A2 (PLA2)-catalyzed release of arachidonic acid (AA) are important regulators of macrophage function and inflammatory responses. The potential roles of AA release and metabolism in SR-A-mediated macrophage adhesion were determined using macrophages adherent to modified protein. SR-A-dependent macrophage adhesion was abolished by selectively inhibiting calcium-independent PLA2 (iPLA2) activity and absent in macrophages isolated from iPLA2 β–/– mice. Our results further demonstrate that 12/15-lipoxygenase (12/15-LOX)-derived, but not cyclooxygenase- or cytochrome P450-dependent epoxygenase-derived AA metabolites, are specifically required for SR-A-dependent adhesion. Because of their role in regulating actin polymerization and cell adhesion, Rac and Cdc42 activation were also examined and shown to be increased via an iPLA2- and LOX-dependent pathway. Together, our results identify a novel role for iPLA2-catalyzed AA release and its metabolism by 12/15-LOX in coupling SR-A-mediated macrophage adhesion to Rac and Cdc42 activation.

scholarly journals New Scavenger Receptor-Like Receptors for the Binding of Lipopolysaccharide to Liver Endothelial and Kupffer Cells

1998 ◽  
Vol 66 (11) ◽  
pp. 5107-5112 ◽  
Author(s):  
Marijke van Oosten ◽  
Erika van de Bilt ◽  
Theo J. C. van Berkel ◽  
Johan Kuiper
Keyword(s):  
Endothelial Cells ◽  
Kupffer Cells ◽  
Binding Sites ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Scavenger Receptors ◽  
Liver Endothelial Cells ◽  
Parenchymal Cells

ABSTRACT Lipopolysaccharide (LPS) is cleared from the blood mainly by the liver. The Kupffer cells are primarily responsible for this clearance; liver endothelial and parenchymal cells contribute to a lesser extent. Although several binding sites have been described, only CD14 is known to be involved in LPS signalling. Among the other LPS binding sites that have been identified are scavenger receptors. Scavenger receptor class A (SR-A) types I and II are expressed in the liver on endothelial cells and Kupffer cells, and a 95-kDa receptor, identified as macrosialin, is expressed on Kupffer cells. In this study, we examined the role of scavenger receptors in the binding of LPS by the liver in vivo and in vitro. Fucoidin, a scavenger receptor ligand, significantly reduced the clearance of 125I-LPS from the serum and decreased the liver uptake of 125I-LPS about 40%. Within the liver, the in vivo binding of 125I-LPS to Kupffer and liver endothelial cells was decreased 72 and 71%, respectively, while the binding of 125I-LPS to liver parenchymal cells increased 34% upon fucoidin preinjection. Poly(I) inhibited the binding of 125I-LPS to Kupffer and endothelial cells in vitro 73 and 78%, respectively, while poly(A) had no effect. LPS inhibited the binding of acetylated low-density lipoprotein (acLDL) to Kupffer and liver endothelial cells 40 and 55%, respectively, and the binding of oxidized LDL (oxLDL) to Kupffer and liver endothelial cells 65 and 61%, respectively. oxLDL and acLDL did not significantly inhibit the binding of LPS to these cells. We conclude that on both endothelial cells and Kupffer cells, LPS binds mainly to scavenger receptors, but SR-A and macrosialin contribute to a limited extent to the binding of LPS.

scholarly journals Monomeric C-Reactive Protein Binds and Neutralizes Receptor Activator of NF-κB Ligand-Induced Osteoclast Differentiation

2018 ◽  
Vol 9 ◽  
Author(s):  
Zhe-Kun Jia ◽  
Hai-Yun Li ◽  
Yu-Lin Liang ◽  
Lawrence Albert Potempa ◽  
Shang-Rong Ji ◽  
...  
Keyword(s):  
Bone Erosion ◽  
Osteoclast Differentiation ◽  
Joint Inflammation ◽  
Dependent Manner ◽  
C Reactive Protein ◽  
Native Conformation ◽  
Reactive Protein ◽  
Receptor Activator ◽  
Binding Sequence

C-reactive protein (CRP) is an established marker of rheumatoid arthritis (RA) but with ill-defined actions in the pathogenesis. Here, we show that CRP regulates the differentiation of osteoclasts, a central mediator of joint inflammation and bone erosion in RA, in a conformation- and receptor activator of NF-κB ligand (RANKL)-dependent manner. CRP in the native conformation is ineffective, whereas the monomeric conformation (mCRP) actively modulates osteoclast differentiation through NF-κB and phospholipase C signaling. Moreover, mCRP can bind RANKL, the major driver of osteoclast differentiation, and abrogate its activities. The binding and inhibition of RANKL are mediated by the cholesterol binding sequence (CBS) of mCRP. Corroborating the in vitro results, CRP knockout exacerbates LPS-induced bone resorption in mice. These results suggest that mCRP may be protective in joint inflammation by inhibiting pathological osteoclast differentiation and that the CBS peptide could be exploited as a potential RANKL inhibitor.

scholarly journals Interactions of ferritin with scavenger receptor class A members

2020 ◽  
Vol 295 (46) ◽  
pp. 15727-15741 ◽  
Author(s):  
Bowen Yu ◽  
Chen Cheng ◽  
Yichun Wu ◽  
Luqiang Guo ◽  
Dandan Kong ◽  
...  
Keyword(s):  
Scavenger Receptor ◽  
Scavenger Receptors ◽  
Dependent Manner ◽  
Class A ◽  
Srcr Domain ◽  
Scavenger Receptor Class ◽  
Biochemical Assays ◽  
Potential Binding ◽  
Membrane Bound ◽  
Human And Mouse

Scavenger receptors are a superfamily of membrane-bound receptors that recognize both self and nonself targets. Scavenger receptor class A (SR-A) has five known members (SCARA1 to -5 or SR-A1 to -A5), which are type II transmembrane proteins that form homotrimers on the cell surface. SR-A members recognize various ligands and are involved in multiple biological pathways. Among them, SCARA5 can function as a ferritin receptor; however, the interaction between SCARA5 and ferritin has not been fully characterized. Here, we determine the crystal structures of the C-terminal scavenger receptor cysteine-rich (SRCR) domain of both human and mouse SCARA5 at 1.7 and 2.5 Å resolution, respectively, revealing three Ca2+-binding sites on the surface. Using biochemical assays, we show that the SRCR domain of SCARA5 recognizes ferritin in a Ca2+-dependent manner, and both L- and H-ferritin can be recognized by SCARA5 through the SRCR domain. Furthermore, the potential binding region of SCARA5 on the surface of ferritin is explored by mutagenesis studies. We also examine the interactions of ferritin with other SR-A members and find that SCARA1 (SR-A1, CD204) and MARCO (SR-A2, SCARA2), which are highly expressed on macrophages, also interact with ferritin. By contrast, SCARA3 and SCARA4, the two SR-A members without the SRCR domain, have no detectable binding with ferritin. Overall, these results provide a mechanistic view regarding the interactions between the SR-A members and ferritin that may help to understand the regulation of ferritin homeostasis by scavenger receptors.

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