Monocytic Cell Line (monocytic + cell_line)

Distribution by Scientific Domains

Kinds of Monocytic Cell Line

  • human monocytic cell line

  • Selected Abstracts

    Prevotella intermedia lipopolysaccharide stimulates release of tumor necrosis factor-, through mitogen-activated protein kinase signaling pathways in monocyte-derived macrophages

    Sung-Jo Kim
    Abstract The purpose of this study was to investigate the effects of lipopolysaccharide from Prevotella intermedia, a major cause of inflammatory periodontal disease, on the production of tumor necrosis factor (TNF)-, and the expression of TNF-, mRNA in differentiated THP-1 cells, a human monocytic cell line. The potential involvement of the three main mitogen-activated protein kinase (MAPK) signaling pathways in the induction of TNF-, production was also investigated. Lipopolysaccharide from P. intermedia ATCC 25611 was prepared by the standard hot phenol,water method. THP-1 cells were incubated in the medium supplemented with phorbol myristate acetate to induce differentiation into macrophage-like cells. It was found that P. intermedia lipopolysaccharide can induce TNF-, mRNA expression and stimulate the release of TNF-, in differentiated THP-1 cells without additional stimuli. Treatment of the cells with P. intermedia lipopolysaccharide resulted in a simultaneous activation of three MAPKs [extracellular signal-related kinase 1/2 (ERK1/2), c-Jun N-terminal kinase 1/2 (JNK1/2) and p38]. Pretreatment of the cells with MAPK inhibitors effectively suppressed P. intermedia lipopolysaccharide-induced TNF-, production without affecting the expression of TNF-, mRNA. These data thus provided good evidence that the MAPK signaling pathways are required for the regulation of P. intermedia lipopolysaccharide-induced TNF-, synthesis at the level of translation more than at the transcriptional level. [source]

    Toxicity to Candida albicans mediated by human serum and peripheral blood mononuclear cells

    Joseph M. Bliss
    Abstract This study evaluates the conditions in which peripheral blood mononuclear cells mediate toxicity to Candida albicans opsonized with heat-inactivated human serum. Serum concentrations as low as 1% resulted in 50% inhibition of C. albicans metabolic activity after incubation with peripheral blood mononuclear cells at an effector to target ratio of 8. Measurable inhibition was also achieved at lower effector to target ratios and lower serum concentrations, and at least a portion of the metabolic inhibition reflected fungal cell death. Depletion of C. albicans -specific antibody decreased the toxic effect while opsonization with purified human IgG restored toxicity, and cell,cell contact between peripheral blood mononuclear cells and fungus was required. Depletion of or enrichment for monocytes from the peripheral blood mononuclear cells preparation diminished the toxic effect and the monocytic cell line, THP-1, was likewise incapable of toxicity. These studies provide evidence that antibody augments antifungal host defense and underscore the complex interrelationship between humoral and cellular immunity in these infections. [source]

    Acholeplasma laidlawii up-regulates granulysin gene expression via transcription factor activator protein-1 in a human monocytic cell line, THP-1

    IMMUNOLOGY, Issue 3 2001
    Yutaka Kida
    Summary An antimicrobial protein granulysin is constitutively expressed in cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. However, little is known about the precise regulatory mechanisms underlying granulysin gene expression. In this study, we examined the regulatory mechanisms underlying granulysin gene expression using a human monocytic cell line, THP-1, treated with Acholeplasma laidlawii. The level of granulysin mRNA expression in THP-1 cells was significantly augmented in response to stimulation with A. laidlawii. The transfection of reporter gene constructs into THP-1 cells indicated that DNA sequences between residues ,329 and ,239, relative to the transcriptional start site of the granulysin gene, are responsible for mediating gene induction. In addition, mutagenesis of a putative activator protein-1 (AP-1)-binding site between residues ,277 and ,271 in the granulysin promoter resulted in the reduction of granulysin promoter activity. Electrophoretic mobility shift assays (EMSA) demonstrated that nuclear extract prepared from A. laidlawii- treated THP-1 cells can generate specific binding to DNA oligonucleotides encompassing the AP-1-binding site, whereas unstimulated nuclear extract from the cells failed to do so. Furthermore, competition and supershift assays confirmed that A. laidlawii can induce the activation of AP-1. These results indicate that AP-1 dominantly participates in the regulation of inducible granulysin gene expression in THP-1 cells. Therefore, the finding of inducible granulysin gene expression by A. laidlawii suggests that inducible granulysin in macrophages may function as a protective weapon when microbial invasion occurs. [source]

    Regulation of osteoclastogenesis and RANK expression by TGF-,1

    Tao Yan
    Abstract Transforming growth factor-, (TGF-,) has been shown to both inhibit and to stimulate bone resorption and osteoclastogenesis. This may be due, in part, to differential effects on bone marrow stromal cells that support osteoclastogenesis vs. direct effects on osteoclastic precursor cells. In the present study, we used the murine monocytic cell line, RAW 264.7, to define direct effects of TGF-, on pre-osteoclastic cells. In the presence of macrophage-colony stimulating factor (M-CSF) (20 ng/ml) and receptor activator of NF-,B ligand (RANK-L) (50 ng/ml), TGF-,1 (0.01,5 ng/ml) dose-dependently stimulated (by up to 120-fold) osteoclast formation (assessed by the presence of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and expression of calcitonin and vitronectin receptors). In addition, TGF-,1 also increased steady state RANK mRNA levels in a time- (by up to 3.5-fold at 48 h) and dose-dependent manner (by up to 2.2-fold at 10 ng/ml). TGF-,1 induction of RANK mRNA levels was present both in undifferentiated RAW cells as well as in cells that had been induced to differentiate into osteoclasts by a 7-day treatment with M-CSF and RANK-L. Using a fluorescence-labeled RANK-L probe, we also demonstrated by flow cytometry that TGF-,1 resulted in a significant increase in the percentage of RANK+ RAW cells (P,<,0.05), as well as an increase in the fluorescence intensity per cell (P,<,0.05), the latter consistent with an increase in RANK protein expression per cell. These data thus indicate that TGF-, directly stimulates osteoclastic differentiation, and this is accompanied by increased RANK mRNA and protein expression. J. Cell. Biochem. 83: 320,325, 2001. 2001 Wiley-Liss, Inc. [source]

    Salvianolic acid B attenuates VCAM-1 and ICAM-1 expression in TNF-,-treated human aortic endothelial cells

    Yung-Hsiang Chen
    Abstract Attachment to, and migration of leukocytes into the vessel wall is an early event in atherogenesis. Expression of cell adhesion molecules by the arterial endothelium may play a major role in atherosclerosis. It has been suggested that antioxidants inhibit the expression of adhesion molecules and may thus attenuate the processes leading to atherosclerosis. In the present study, the effects of a potent water-soluble antioxidant, salvianolic acid B (Sal B), and an aqueous ethanolic extract (SME), both derived from a Chinese herb, Salvia miltiorrhiza, on the expression of endothelial-leukocyte adhesion molecules by tumor necrosis factor-, (TNF-,)-treated human aortic endothelial cells (HAECs) were investigated. When pretreated with SME (50 and 100 ,g/ml), the TNF-,-induced expression of vascular adhesion molecule-1 (VCAM-1) was notably attenuated (77.2,,3.2% and 80.0,,2.2%, respectively); and with Sal B (1, 2.5, 5, 10, and 20 ,g/ml), 84.5,,1.9%, 78.8,,1.2%, 58.9,,0.4%, 58.7,,0.9%, and 57.4,,0.3%, respectively. Dose-dependent lowering of expression of intercellular cell adhesion molecule-1 (ICAM-1) was also seen with SME or Sal B. In contrast, the expression of endothelial cell selectin (E-selectin) was not affected. SME (50 ,g/ml) or Sal B (5 ,g/ml) significantly reduced the binding of the human monocytic cell line, U937, to TNF-,-stimulated HAECs (45.7,,2.5% and 55.8,,1.2%, respectively). SME or Sal B significantly inhibited TNF-,-induced activation of nuclear factor kappa B (NF-,B) in HAECs (0.36- and 0.48-fold, respectively). These results demonstrate that SME and Sal B have anti-inflammatory properties and may explain their anti-atherosclerotic properties. This new mechanism of action of Sal B and SME, in addition to their previously reported inhibition of LDL, may help explain their efficacy in the treatment of atherosclerosis. J. Cell. Biochem. 82:512,521, 2001. 2001 Wiley-Liss, Inc. [source]

    Herpes simplex virus type 1 dysregulates anti-fungal defenses preventing monocyte activation and downregulating toll-like receptor-2

    Claudio Cermelli
    ABSTRACT We investigated the interplay occurring between pathogens in the course of dual infections, using an in vitro model in which the THP-1 monocytic cell line is first infected with HSV-1 and then exposed to Ca or Cn. These three pathogens share some pathogenic features: they cause opportunistic infections, target macrophages and are neurotropic. Here, we show that HSV-1-infected THP-1 cells exhibited augmented phagocytosis against the two opportunistic fungi but reduced capability to counteract fungal infection: the better ingestion by monocytes was followed by facilitated fungal survival and replication. Reduced IL-12 production was also observed. Cytofluorimetric analysis showed that HSV-1-infected monocytes exhibit: (i) downregulated TLR-2 and TLR-4, critical structures in fungal recognition; (ii) reduced expression of CD38 and CD69, known to be important markers of monocyte activation; and (iii) enhanced expression of apoptosis and necrosis markers, in the absence of altered cell proliferation. Overall, these findings imply that HSV-1 infection prevents monocyte activation, thus leading to a significant dysfunction of the monocyte-mediated anti- Candida response; HSV-1 induced apoptosis and necrosis of monocytes further contribute to this impairment. [source]

    Leishmania donovani -induced macrophages cyclooxygenase-2 and prostaglandin E2 synthesis

    Claudine Matte
    Prostaglandin E2 (PGE2) secretion during Leishmania infection has been reported. However, the signalling mechanisms mediating this response are not well understood. Since cyclooxygenase-2 (COX-2) and cytosolic phospholipase A2 (cPLA2) are involved in PGE2 synthesis in response to various stimuli, the implication of these enzymes was evaluated in Leishmania -infected phorbol myristate acetate-differentiated U937 human monocytic cell line. Time-course experiments showed that PGE2 synthesis increased significantly in parallel with COX-2 expression when cells were incubated in the presence of Leishmania donovani promastigotes or lipopolysaccharides (LPS). Increase in cPLA2 mRNA expression was only detected when cells were stimulated with LPS. Indomethacin, genistein, and H7, which are antagonists of COX-2, protein tyrosine kinase (PTK) and protein kinase C (PKC), respectively, inhibited PGE2 production induced by L. donovani and LPS. However, only H7 inhibited COX-2 mRNA synthesis, and there was a significant correlation between PGE2 inhibition and reduced COX-2 expression. Collectively, our results indicate that infection of U937 by L. donovani leads to the generation of PGE2 in part through a PKC-dependent signalling pathway involving COX-2 expression. They further reveal that PTK-dependent events are necessary for Leishmania -induced PGE2 generation, but not for COX-2 expression. A better understanding of the mechanisms by which Leishmania can induce PGE2 production could provide insight into the pathophysiology of leishmaniasis and may help to improve therapeutic approaches. [source]

    Granulocyte/macrophage colony-stimulating factor treatment of human chronic ulcers promotes angiogenesis associated with de novo vascular endothelial growth factor transcription in the ulcer bed

    F. Cianfarani
    Summary Background, Granulocyte/macrophage colony-stimulating factor (GM-CSF), a cytokine with pleiotropic functions, has been successfully employed in the treatment of chronic skin ulcers. The biological effects underlying GM-CSF action in impaired wound healing have been only partly clarified. Objectives, To investigate the effects of GM-CSF treatment of chronic venous ulcers on lesion vascularization and on the local synthesis of the angiogenic factors vascular endothelial growth factor (VEGF) and placenta growth factor (PlGF). Methods, Patients with nonhealing venous leg ulcers were treated with intradermal injection of recombinant human GM-CSF, and biopsies were taken at the ulcer margin before and 5 days after administration. Wound vascularization was analysed by immunohistochemistry using antiplatelet endothelial cell adhesion molecule-1/CD31 and anti-,-smooth muscle actin antibodies. VEGF and PlGF transcription was assessed by in situ hybridization. To identify the cell populations transcribing VEGF within the ulcer bed, the VEGF hybridization signal was correlated with the immunostaining for different cell type markers on serial sections. Direct induction of VEGF transcription by GM-CSF was investigated in GM-CSF-treated cultured macrophages and keratinocytes. Results, Blood vessel density was significantly increased in the ulcer bed following GM-CSF treatment. VEGF transcripts were localized in keratinocytes at the ulcer margin both before and after GM-CSF treatment, whereas a VEGF hybridization signal was evident within the ulcer bed only following administration. PlGF mRNA was barely detectable in keratinocytes at the ulcer margin and was not visibly increased after treatment. Unlike VEGF, a specific PlGF hybridization signal could not be detected in cells within the ulcer following GM-CSF administration. Monocytes/macrophages were the main cell population transcribing VEGF after GM-CSF treatment. In vitro analysis demonstrated that VEGF transcription can be directly stimulated by GM-CSF in a differentiated monocytic cell line, but not in keratinocytes. Conclusions, Our data show that increased vascularization is associated with GM-CSF treatment of chronic venous ulcers and indicate that inflammatory cell-derived VEGF may act as an angiogenic mediator of the healing effect of GM-CSF in chronic ulcers. [source]

    Synthesis and Proinflammatory Properties of Muramyl Tripeptides Containing Lysine and Diaminopimelic Acid Moieties

    CHEMBIOCHEM, Issue 11 2005
    Abhijit Roychowdhury Dr.
    Abstract The unusual amino acid diaminopimelic acid (DAP) was prepared by cross metathesis of appropriately protected vinyl glycine and allyl glycine derivatives. Catalytic hydrogenation of the cross-coupling product resulted in reduction of the double bond and the removal of protecting groups. The resulting compounds were appropriately protected for the polymer-supported and solution-phase synthesis of muramyl tripeptides 2 and 3, which differ in the amidation of the ,-carboxylic acids of the isoglutamine and DAP moieties. Muramyl dipeptide (1, MDP), the DAP-containing muramyl tripeptide 3, and the lysine-containing muramyl tripeptides 4 and 5 induced TNF-, gene expression without TNF-, protein production in a human monocytic cell line. The observed block in translation could be removed by co-incubation with LPS, resulting in an apparent synergistic effect. Compound 2 did not induce TNF-, gene expression, neither did it exhibit a synergistic effect with LPS; this indicates that amidation of the ,-carboxylic acids of the isoglutamine and DAP moieties results in a loss of biological activity. It is proposed that amidation of ,-carboxylic acids is a strategy that may be used by pathogens to avoid detection by the innate immune system. Furthermore, the pattern recognition receptors Nod1 and Nod2 have been implicated in the possible induction of a synergistic effect of muropeptides with LPS. [source]

    Suppression of lipopolysaccharide- and tumour necrosis factor-,-induced interleukin (IL)-8 expression by glucocorticoids involves changes in IL-8 promoter acetylation

    L. G. Tsaprouni
    Summary There is accumulating evidence that the transrepressional effect of glucocorticoids in down-regulating proinflammatory gene expression might be regulated by an action on histone acetylation. To investigate this, we studied the effect of two glucocorticoids (dexamethasone and triamcinolone acetonide) on reducing lipopolysaccharide (LPS)- and tumour necrosis factor (TNF)-,-induced interleukin (IL)-8 release in a monocytic cell line and two lymphocytic cell lines (HUT-78 and Jurkat). The effect of the histone deacetylase inhibitor trichostatin A (TSA) on LPS- and TNF-,-induced IL-8 release and its repression by glucocorticoids was also examined. LPS and TNF-, induced IL-8 release in all three cell lines and this induction was inhibited by both dexamethasone and triamcinolone. Pretreatment of cells with TSA enhanced basal and LPS- and TNF,-stimulated IL-8 release in all three cell lines. TSA also attenuated the inhibitory effect of glucocorticoids on stimulated IL-8 release. Chromatin immunoprecipitation assays confirmed that LPS and TNF-, enhanced histone acetylation at the IL-8 promoter and that this was inhibited by triamcinolone in all three cell types. Changes in histone acetylation at the IL-8 are important in its regulation by proinflammatory and anti-inflammatory agents, and modulation of this activity may have therapeutic potential in inflammatory conditions. [source]

    Interactions between major histocompatibility complex class II surface expression and HIV: implications for pathogenesis

    W. Kamp
    Although it has been almost 20 years since the first cases of acquired immunodeficiency syndrome (AIDS) were documented, the pathogenesis is still not completely understood. Interactions between major histocompatibility complex (MHC) Class I and human immunodeficiency virus (HIV), resulting in down-regulation of MHC-I surface expression, have been reported to contribute to pathogenesis by suppressing the host's immune response. Interactions between MHC Class II and HIV have also been described, but it is unclear how these contribute to the pathogenesis. MHC-II surface expression on HIV-infected monocytes and monocytic cell lines has been described to be increased as well as decreased when compared to uninfected control monocytes. HIV-specific mechanisms appear to down-regulate MHC-II expression on blood monocytes during HIV-1 infection, whereas host mechanisms up-regulate MHC-II expression in response to infection of blood monocytes as well as brain macrophages. A balance between these two may determine MHC-II expression levels in individual patients. Altogether, HIV seems to be able to benefit from both low and high levels of MHC-II surface expression. The first results in reduced immune surveillance of the host, allowing the virus to replicate faster; the second increases infectivity of the virus as a result of higher MHC-II density on macrophages and virion particles. [source]