LPS differentially regulates adhesion and transendothelial migration of human monocytes under static and flow conditions

Bradfield, Paul F.; Johnson‐Léger, Caroline; Zimmerli, Claudia; Imhof, Beat A.

doi:10.1093/intimm/dxm136

Cited by 26 publications

(30 citation statements)

References 58 publications

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“…A key aspect of this recruitment is the upregulation of adhesion molecules on endothelial cells by proinflammatory cytokines. Consistent with previous findings, we observed a vast increase in monocyte adhesion on TNF and flow-stimulated endothelium (Bradfield et al 2008). Using functional grade antibodies, we showed that in vitro adhesion mainly relies on CD11b/CD18-ICAM-1 interaction, also in agreement with previous findings (Ikuta et al 1991).…”

Section: Discussionsupporting

confidence: 93%

Generation of Mature Murine Monocytes from Heterogeneous Bone Marrow and Description of Their Properties

Francke

Herold

Weinert

et al. 2011

J Histochem Cytochem.

104

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Monocytes are involved in a wide range of physiological and pathological processes, many of which are studied in mouse models. Current protocols to isolate murine monocytes are few and result in unsatisfactory cell yield and purity. Here, we describe a novel approach to efficiently differentiate large numbers of mature inflammatory monocytes from heterogeneous bone marrow cell suspensions. Bone marrow cell suspensions were isolated by flushing femurs and tibias from Balb/c and C57Bl/6 mice, supplemented with macrophage colony–stimulating factor (M-CSF), and were cultured on ultra-low attachment surfaces to inhibit adherence-mediated maturation. Cells were harvested at indicated time points, underwent time-line analysis of the differentiation processes, and were subsequently extensively phenotyped to verify their monocytotic properties. In order to confirm downstream compatibility, we tested for typical monocyte behavior. Our protocol yielded 24 ± 6 × 106 differentiated cells per donor mouse, 10-fold higher than yields obtained using previously described peripheral blood isolation methods. Differentiated cells consisted of approximately 47% ± 12% monocytes, the rest being mature macrophages. We increased monocyte purity to 86% ± 6% by depleting adherent macrophages. Our findings indicate that bone marrow–derived monocytes (BMDMs) are an attractive tool to study, for example, the innate and adaptive immune system, atherosclerosis, and cellular migration during infection. Moreover, BMDM transplantation could be used to test novel, therapeutic in vivo approaches in mice disease models.

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Section: Discussionsupporting

confidence: 93%

Generation of Mature Murine Monocytes from Heterogeneous Bone Marrow and Description of Their Properties

Francke

Herold

Weinert

et al. 2011

J Histochem Cytochem.

104

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“…CDK6 has been shown to play a role in the cell cycle but also cellular adhesion (25)(26)(27). LPS is a weak inducer of cellular proliferation, but it promotes cell adhesion.…”

Section: Inhibition Of Tnf-␣ Secretion and Adhesion By Cellsmentioning

confidence: 99%

Toll-like Receptor-4 (TLR4) Down-regulates MicroRNA-107, Increasing Macrophage Adhesion via Cyclin-dependent Kinase 6

Hennessy

Sheedy

Santamarı́a

et al. 2011

Journal of Biological Chemistry

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Toll-like receptors (TLRs) modulate the expression of multiple microRNAs (miRNAs). Here, we report the down-regulation of miR-107 by TLR4 in multiple cell types. The miR-107 sequence occurs in an intron within the sequence encoding the gene for pantothenate kinase 1␣ (PanK1␣), which is regulated by the transcription factor peroxisome proliferator-activating receptor ␣ (PPAR-␣). PanK1␣ is also decreased in response to lipopolysaccharide (LPS). The effect on both miR-107 and PanK1␣ is consistent with a decrease in PPAR-␣ expression. We have found that the putative miR-107 target cyclin-dependent kinase 6 (CDK6) expression is increased by TLR4 as a result of the decrease in miR-107. This effect is required for increased adhesion of macrophages in response to LPS, and CDK6-deficient mice are resistant to the lethal effect of LPS. We have therefore identified a mechanism for LPS signaling which involves a decrease in miR-107 leading to an increase in CDK6.Toll-like receptors (TLRs) 2 are among the first line of defense in the body where they recognize conserved structures from bacteria, viruses, or fungi (1, 2). They play a critical role in innate immunity, and their activation leads to the transcription of genes involved in the immune and inflammatory responses. MicroRNAs (miRNAs) are an important family of small, noncoding RNAs that act as regulators of gene expression in a tissue-and cell-specific manner by base-pairing to a target messenger RNA (mRNA) sequence called a seed sequence. This leads to the partial or full degradation of the mRNA by RNases and the inhibition of its translation into a functional protein (3-5). miRNAs were originally found to have a role in cellular development, differentiation, adhesion, and apoptosis and are now known to function in cancer and immunity (5-8). Stimulation of cells with the TLR4-specific ligand LPS from Gramnegative bacteria results in an increase in the expression of several miRNAs including miR-21, miR-146a, and miR-155. miR-21 has been linked to cell migration, invasion, and adhesion, with target genes that include tropomyosin, programmed cell death protein 4 (PDCD4), and phosphatase and tensin homolog (PTEN). It was recently shown to regulate the immune response negatively by promoting the anti-inflammatory response by eliminating PDCD4 and up-regulating IL-10 (9, 10). miR-146a acts as a negative regulator of TLR signaling and cytokine production. Two genes known to be involved in TLR4 signaling, those encoding TRAF6 and IRAK1, are targets of miR-146a, and it was shown that LPS-induced activation of miR-146a is NF-B-dependent (11). miR-155 has been shown to target suppressor of cytokine signaling 1 (SOCS1) and SH2 (Src homology 2)-containing inositol phosphatase-1 (SHIP-1) directly. Mice lacking miR-155 have defects in B cell differentiation as well as having severe deficiencies in immune responses when exposed to pathogens (12-14). miRNAs have also been shown to be down-regulated in expression in response to LPS, including Let-7i and miR-125b, which have been show...

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“…Previous work has shown that adhesion of monocytes to the endothelium, the initial step in the development of atherosclerotic plaque, is increased by LPS stimulation of either human monocytes or HECs. 19,20 In this study, we assessed the effect of Lipo/GOT on monocyte adhesion to HECs induced by LPS. To this end, HEC and THP1 monocytes were first activated separately for 24 hours with LPS before starting the adhesion assay.…”

mentioning

confidence: 99%

Lipopolysaccharide-induced inflammation in monocytes/macrophages is blocked by liposomal delivery of G<sub>i</sub>-protein inhibitor

Pirvulescu¹,

Rebleanu²,

Constantinescu³

et al. 2017

IJN

106

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Background Lipopolysaccharide (LPS) is widely recognized as a potent activator of monocytes/macrophages, and its effects include an altered production of key mediators, such as inflammatory cytokines and chemokines. The involvement of G i protein in mediating LPS effects has been demonstrated in murine macrophages and various cell types of human origin. Purpose The aim of the present work was to evaluate the potential of a G i -protein inhibitor encapsulated in liposomes in reducing the inflammatory effects induced by LPS in monocytes/macrophages. Materials and methods Guanosine 5′- O -(2-thiodiphosphate) (GOT), a guanosine diphosphate analog that completely inhibits G-protein activation by guanosine triphosphate and its analogs, was encapsulated into liposomes and tested for anti-inflammatory effects in LPS-activated THP1 monocytes or THP1-derived macrophages. The viability of monocytes/macrophages after incubation with different concentrations of free GOT or liposome-encapsulated GOT was assessed by MTT assay. MAPK activation and production of IL1β, TNFα, IL6, and MCP1 were assessed in LPS-activated monocytes/macrophages in the presence or absence of free or encapsulated GOT. In addition, the effect of free or liposome-encapsulated GOT on LPS-stimulated monocyte adhesion to activated endothelium and on monocyte chemotaxis was evaluated. Results We report here that GOT-loaded liposomes inhibited activation of MAPK and blocked the production of the cytokines IL1β, TNFα, IL6, and MCP1 induced by LPS in monocytes and macrophages. Moreover, GOT encapsulated in liposomes reduced monocyte adhesion and chemotaxis. All demonstrated events were in contrast with free GOT, which showed reduced or no effect on monocyte/macrophage activation with LPS. Conclusion This study demonstrates the potential of liposomal GOT in blocking LPS proinflammatory effects in monocytes/macrophages.

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LPS differentially regulates adhesion and transendothelial migration of human monocytes under static and flow conditions

Cited by 26 publications

References 58 publications

Generation of Mature Murine Monocytes from Heterogeneous Bone Marrow and Description of Their Properties

Generation of Mature Murine Monocytes from Heterogeneous Bone Marrow and Description of Their Properties

Toll-like Receptor-4 (TLR4) Down-regulates MicroRNA-107, Increasing Macrophage Adhesion via Cyclin-dependent Kinase 6

Lipopolysaccharide-induced inflammation in monocytes/macrophages is blocked by liposomal delivery of G<sub>i</sub>-protein inhibitor

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