Discrepancies in the in vitro and in vivo role of scavenger receptors in clearance of nanoparticles by Kupffer cells

Nanoparticles are recognized and cleared by Kupffer cells (KCs) in the liver. This process complicates the development of targeted nanoparticles because of significant reduction of number of nanoparticles that can reach target tissues. Macrophage scavenger receptor SR type AI/II is the central phagocytic receptor that has been shown to promote in vitro uptake of many nanoparticle types. In this paper, the authors set out to clarify the role of SR-AI/II in the in vivo liver clearance of 10kDa dextran superparamagnetic iron oxide (SPIO) Feridex-IV® and 20kDa dextran-coated SPIO nanoworms (SPIO NWs). Feridex showed efficient SR-AI/II-dependent uptake by isolated KCs in vitro, whereas SPIO NWs showed no uptake by KCs. Both Feridex and SPIO NWs showed a very short and nearly identical circulation half-life and efficient uptake by KCs in vivo. The SR-AI/II inhibitor, polyinosinic acid, prolonged the circulation half-life of both Feridex and SPIO NWs, but did not reduce the KC uptake. The circulation half-life and KC uptake of Feridex and SPIO NWs were identical in SR-AI/II-deficient mice and wild-type mice. These data suggest: (1) there is a limited correlation between in vitro and in vivo uptake mechanisms of nanoparticles in KCs; and (2) redundant, SR-AI/II independent mechanisms play a significant role in the nanoparticle recognition by KCs in vivo. Understanding the complexity of nanoparticle clearance assays and mechanisms is an important step to improving the design of “stealthy” nanoparticles.

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Increased Susceptibility of Thymocytes to Apoptosis in Mice Lacking AIM, a Novel Murine Macrophage-derived Soluble Factor Belonging to the Scavenger Receptor Cysteine-rich Domain Superfamily

Journal of Experimental Medicine ◽

10.1084/jem.189.2.413 ◽

1999 ◽

Vol 189 (2) ◽

pp. 413-422 ◽

Cited By ~ 102

Author(s):

Toru Miyazaki ◽

Yumiko Hirokami ◽

Nobuyuki Matsuhashi ◽

Hisakazu Takatsuka ◽

Makoto Naito

Keyword(s):

Scavenger Receptor ◽

The Body ◽

Murine Macrophage ◽

Double Positive ◽

Differential Signal ◽

Rich Domain ◽

Macrophage Scavenger Receptor ◽

Cysteine Rich Domain

Apoptosis of cells must be regulated both positively and negatively in response to a variety of stimuli in the body. Various environmental stresses are known to initiate apoptosis via differential signal transduction cascades. However, induction of signals that may inhibit apoptosis is poorly understood, although a number of intracellular molecules that mediate inhibition of apoptosis have been identified. Here we present a novel murine macrophage-specific 54-kD secreted protein which inhibits apoptosis (termed AIM, for apoptosis inhibitor expressed by macrophages). AIM belongs to the macrophage scavenger receptor cysteine-rich domain superfamily (SRCR-SF), members of which share a highly homologous conserved cysteine-rich domain. In AIM-deficient mice, the thymocyte numbers were diminished to half those in wild-type mice, and CD4/CD8 double-positive (DP) thymocytes were strikingly more susceptible to apoptosis induced by both dexamethasone and irradiation in vivo. Recombinant AIM protein significantly inhibited cell death of DP thymocytes in response to a variety of stimuli in vitro. These results indicate that in the thymus, AIM functions in trans to induce resistance to apoptosis within DP cells, and thus supports the viability of DP thymocytes before thymic selection.

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cdk1- and cdk2-Mediated Phosphorylation of MyoD Ser200 in Growing C2 Myoblasts: Role in Modulating MyoD Half-Life and Myogenic Activity

Molecular and Cellular Biology ◽

10.1128/mcb.19.4.3167 ◽

1999 ◽

Vol 19 (4) ◽

pp. 3167-3176 ◽

Cited By ~ 81

Author(s):

Magali Kitzmann ◽

Marie Vandromme ◽

Valerie Schaeffer ◽

Gilles Carnac ◽

Jean-Claude Labbé ◽

...

Keyword(s):

Half Life ◽

Site Directed Mutagenesis ◽

Cyclin B ◽

Wild Type ◽

E Box ◽

Integral Role ◽

Phosphopeptide Mapping

ABSTRACT We have examined the role of protein phosphorylation in the modulation of the key muscle-specific transcription factor MyoD. We show that MyoD is highly phosphorylated in growing myoblasts and undergoes substantial dephosphorylation during differentiation. MyoD can be efficiently phosphorylated in vitro by either purified cdk1-cyclin B or cdk1 and cdk2 immunoprecipitated from proliferative myoblasts. Comparative two-dimensional tryptic phosphopeptide mapping combined with site-directed mutagenesis revealed that cdk1 and cdk2 phosphorylate MyoD on serine 200 in proliferative myoblasts. In addition, when the seven proline-directed sites in MyoD were individually mutated, only substitution of serine 200 to a nonphosphorylatable alanine (MyoD-Ala200) abolished the slower-migrating hyperphosphorylated form of MyoD, seen either in vitro after phosphorylation by cdk1-cyclin B or in vivo following overexpression in 10T1/2 cells. The MyoD-Ala200 mutant displayed activity threefold higher than that of wild-type MyoD in transactivation of an E-box-dependent reporter gene and promoted markedly enhanced myogenic conversion and fusion of 10T1/2 fibroblasts into muscle cells. In addition, the half-life of MyoD-Ala200 protein was longer than that of wild-type MyoD, substantiating a role of Ser200 phosphorylation in regulating MyoD turnover in proliferative myoblasts. Taken together, our data show that direct phosphorylation of MyoD Ser200 by cdk1 and cdk2 plays an integral role in compromising MyoD activity during myoblast proliferation.

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Advanced glycation end products are eliminated by scavenger-receptor-mediated endocytosis in hepatic sinusoidal Kupffer and endothelial cells

Biochemical Journal ◽

10.1042/bj3220567 ◽

1997 ◽

Vol 322 (2) ◽

pp. 567-573 ◽

Cited By ~ 130

Author(s):

Bård SMEDSRØD ◽

Jukka MELKKO ◽

Norie ARAKI ◽

Hiroyuki SANO ◽

Seikoh HORIUCHI

Keyword(s):

Advanced Glycation End Products ◽

Kupffer Cells ◽

Scavenger Receptor ◽

Type I ◽

Advanced Glycation ◽

Liver Uptake ◽

Glycation End Products ◽

End Products

Long-term incubation of proteins with glucose leads to the formation of advanced glycation end products (AGE). Physiological aspects of the catabolism of non-enzymically glycated proteins were studied in vivo and in vitro. AGE-modified BSA (AGE-BSA) was a mixture of high-Mr (cross-linked), monomeric and low-Mr (fragmented) AGE-BSA. After intravenous administration in rat, all three fractions of AGE-BSA accumulated extremely rapidly and almost exclusively in liver. Uptake in liver endothelial, Kupffer and parenchymal cells accounted for approx. 60%, 25% and 10–15% respectively of hepatic elimination. Both cross-linked and monomeric AGE-BSA were efficiently taken up and degraded in cultures of purified liver endothelial and Kupffer cells. Endocytosis of AGE-BSA by these cells was inhibited by several ligands for the scavenger receptor. Although 125I-Hb was not endocytosed in vitro, 125I-AGE-Hb was effectively endocytosed by a mechanism that was subject to inhibition by AGE-BSA. Endocytosis of N-terminal propeptide of type I procollagen, a physiological ligand for the scavenger receptor, was effectively inhibited by AGE-Hb and AGE-BSA. We conclude that AGE-modification renders macromolecules susceptible for elimination via the scavenger receptor of both liver endothelial and Kupffer cells.

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Polyinosinic acid enhances delivery of adenovirus vectors in vivo by preventing sequestration in liver macrophages

Journal of General Virology ◽

10.1099/vir.0.83495-0 ◽

2008 ◽

Vol 89 (5) ◽

pp. 1097-1105 ◽

Cited By ~ 55

Author(s):

Hidde J. Haisma ◽

Jan A. A. M. Kamps ◽

Gera K. Kamps ◽

Josee A. Plantinga ◽

Marianne G. Rots ◽

...

Keyword(s):

Gene Therapy ◽

Kupffer Cells ◽

Transgene Expression ◽

Liver Toxicity ◽

Viral Vector ◽

Adenovirus Vector ◽

Liver Macrophages ◽

Polyinosinic Acid

Adenovirus is among the preferred vectors for gene therapy because of its superior in vivo gene-transfer efficiency. However, upon systemic administration, adenovirus is preferentially sequestered by the liver, resulting in reduced adenovirus-mediated transgene expression in targeted tissues. In the liver, Kupffer cells are responsible for adenovirus degradation and contribute to the inflammatory response. As scavenger receptors present on Kupffer cells are responsible for the elimination of blood-borne pathogens, we investigated the possible implication of these receptors in the clearance of the adenovirus vector. Polyinosinic acid [poly(I)], a scavenger receptor A ligand, was analysed for its capability to inhibit adenovirus uptake specifically in macrophages. In in vitro studies, the addition of poly(I) before virus infection resulted in a specific inhibition of adenovirus-induced gene expression in a J774 macrophage cell line and in primary Kupffer cells. In in vivo experiments, pre-administration of poly(I) caused a 10-fold transient increase in the number of adenovirus particles circulating in the blood. As a consequence, transgene expression levels measured in different tissues were enhanced (by 5- to 15-fold) compared with those in animals that did not receive poly(I). Finally, necrosis of Kupffer cells, which normally occurs as a consequence of systemic adenovirus administration, was prevented by the use of poly(I). No toxicity, as measured by liver-enzyme levels, was observed after poly(I) treatment. From our data, we conclude that poly(I) can prevent adenovirus sequestration by liver macrophages. These results imply that, by inhibiting adenovirus uptake by Kupffer cells, it is possible to reduce the dose of the viral vector to diminish the liver-toxicity effect and to improve the level of transgene expression in target tissues. In systemic gene-therapy applications, this will have great impact on the development of targeted adenoviral vectors.

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Uncoupling Scavenger Receptor A-Mediated Phagocytosis of Bacteria from Endotoxic Shock Resistance

Infection and Immunity ◽

10.1128/iai.00727-09 ◽

2009 ◽

Vol 77 (10) ◽

pp. 4567-4573 ◽

Cited By ~ 17

Author(s):

Eyal Amiel ◽

Julie L. Acker ◽

Ryan M. Collins ◽

Brent Berwin

Keyword(s):

Endotoxic Shock ◽

Scavenger Receptor ◽

Multiple Organ ◽

Reciprocal Relationship ◽

Bacterial Strains ◽

Gram Negative ◽

Trafficking Receptor

ABSTRACT Unresolved infection by gram-negative bacteria can result in the potentially lethal condition known as endotoxic shock, whereby uncontrolled inflammation can lead to multiple organ failure and death of the infected host. Previous results have demonstrated that animals deficient in class A scavenger receptor (SRA), a trafficking receptor for bacteria and bacterium-derived molecules, are more susceptible to endotoxic shock. This has been proposed to be a result of impaired SRA-dependent phagocytic clearance of bacteria resulting in stronger proinflammatory stimuli. In this report, we test the hypothesis that there is an obligate reciprocal relationship between SRA-mediated phagocytosis of bacteria and susceptibility to endotoxic shock. Here, we demonstrate that both SRA-dependent and -independent gram-negative bacterial strains elicit SRA-dependent increased cytokine production in vitro and in vivo and increased susceptibility to endotoxic shock in SRA-deficient mice. This is the first evidence showing that SRA-mediated clearance of LPS is functionally distinct from the role of SRA in bacterial phagocytosis and is a formal demonstration that the SRA-dependent cytokine responses and the resultant endotoxic shock are not coupled to SRA-mediated clearance of bacteria.

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The Scavenger Receptor MARCO Is Required for Lung Defense against Pneumococcal Pneumonia and Inhaled Particles

Journal of Experimental Medicine ◽

10.1084/jem.20040731 ◽

2004 ◽

Vol 200 (2) ◽

pp. 267-272 ◽

Cited By ~ 231

Author(s):

Mohamed Arredouani ◽

Zhiping Yang ◽

YaoYu Ning ◽

Guozhong Qin ◽

Raija Soininen ◽

...

Keyword(s):

Pneumococcal Pneumonia ◽

Inflammatory Responses ◽

Scavenger Receptor ◽

Pneumococcal Infection ◽

Innate Defense ◽

Inhaled Particles ◽

Lung Defense

Alveolar macrophages (AMs) express the class A scavenger receptor macrophage receptor with collagenous structure (MARCO), but its role in vivo in lung defense against bacteria and environmental particles has not been studied. We used MARCO-deficient mice to directly test the in vivo role of AM MARCO in innate defense against pneumococcal infection and environmental particles. In a murine model of pneumococcal pneumonia, MARCO−/− mice displayed an impaired ability to clear bacteria from the lungs, increased pulmonary inflammation and cytokine release, and diminished survival. In vitro binding of Streptococcus pneumoniae and in vivo uptake of unopsonized particles by MARCO−/− AMs were dramatically impaired. MARCO−/− mice treated with the “inert” environmental particle TiO2 showed enhanced inflammation and chemokine expression, indicating that MARCO-mediated clearance of inert particles by AMs prevents inflammatory responses otherwise initiated by other lung cells. Our findings point to an important role of MARCO in mounting an efficient and appropriately regulated innate immune response against inhaled particles and airborne pathogens.

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Precision Nanomedicine Volume 1 Issue 1 Table of Contents

Precision Nanomedicine ◽

10.33218/prnano1(1).toc ◽

2018 ◽

Vol 1 (1) ◽

pp. 1-5

Keyword(s):

Drug Testing ◽

Scavenger Receptor ◽

Cell Communication ◽

Superparamagnetic Iron Oxide ◽

The Body ◽

In Vivo Model ◽

Hypersensitivity Reactions ◽

Good Biocompatibility

The inaugural issue is introduced by several editorials: "The Story of Precision Nanomedicine-the Journal", "Balancing Interests of Science, Scientists, and the Publishing Business", and "Improving Innovation in Nano-Healthcare Funding". The Clinical Editor's comments on research papers: Prec. Nanomed. 2018, Apr; 1(1):18-42. Extracellular vesicles (EVs) are involved in various biological processes such as cargo trafficking, cell-cell communication, and signal transduction. The advances in nanotechnology have enabled researchers to utilize EVs for potential use in clinical applications, within the so-called precision medicine approach. In this review article, the authors discuss the techniques used in EV isolation in length, together with their applications in clinical diagnosis and therapeutics. Prec. Nanomed. 2018 Apr;1(1):63-75. Due to potential hypersensitivity reactions to nanodrugs, thorough testing is required before these drugs can be used in the clinical setting. Here the authors provide a succinct review on the use of pigs as a reliable in-vivo model for pre-clinical drug testing. Prec. Nanomed. 2018 Apr;1(1):76-85. One of the ways that nanoparticles are cleared in the body is via Kupffer cells. The authors of the next paper tested the role of scavenger receptor SR-AI/II in the clearance of dextran superparamagnetic iron oxide (SPIO) Feridex-IV® and dextran-coated SPIO nanoworms (SPIO NWs). Results here show that multiple pathways and mechanisms exist in nanoparticle clearance. Thus, further understanding of nanoparticle clearance would be required to prolong in vivo half-life. Prec. Nanomed. 2018 Apr;1(1):43-62. Liposomes have been used in clinical practice for some years, this delivery system often result in significant systemic effects due to hypersensitivity reactions, via the activation of the complement system. The authors here show good biocompatibility of Rad-PC-Rad liposomes in terms of complement activation and pro-inflammatory cytokines production in-vitro.

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

Infection and Immunity ◽

10.1128/iai.66.11.5107-5112.1998 ◽

1998 ◽

Vol 66 (11) ◽

pp. 5107-5112 ◽

Cited By ~ 41

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.

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Novel macrophage receptor for glucose-modified proteins is distinct from previously described scavenger receptors.

Journal of Experimental Medicine ◽

10.1084/jem.164.4.1301 ◽

1986 ◽

Vol 164 (4) ◽

pp. 1301-1309 ◽

Cited By ~ 98

Author(s):

H Vlassara ◽

M Brownlee ◽

A Cerami

Keyword(s):

Protein Modification ◽

Scavenger Receptor ◽

Specific Pattern ◽

Scavenger Receptors ◽

Polycytidylic Acid ◽

Protein Receptor ◽

Polyinosinic Acid ◽

Modified Proteins

A high-affinity macrophage receptor has been identified that recognizes proteins modified by a common in vivo process, long-term nonenzymatic reaction of glucose with proteins (AGE proteins). This receptor for glucose-modified proteins is now shown to be distinct from previously described scavenger receptors, using competition and crosscompetition experiments between AGE-modified protein and a variety of in vitro-modified scavenger receptor ligands, including unmodified BSA, unmodified low-density lipoproteins (LDL), acetyl-LDL, maleyl-BSA, and formaldehyde-treated BSA. Furthermore, the specific pattern of AGE-protein receptor inhibition by the polyanionic compounds polyinosinic acid, polyadenylic acid, polyglutamic acid, polycytidylic acid, fucoidin, and heparin was distinctly different from that of acetyl-LDL. By thus selectively recognizing a time-dependent in vivo protein modification, macrophages may preferentially degrade senescent macromolecules, thereby having an important role in the regulation of extracellular protein turnover.

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