scholarly journals Endothelial cells potentiate phagocytic killing by macrophages via platelet-activating factor release

2000 ◽  
Vol 278 (1) ◽  
pp. H269-H276 ◽  
Author(s):  
Tetsuhiro Owaki ◽  
Avedis Meneshian ◽  
Kosei Maemura ◽  
Sonshin Takao ◽  
Dajie Wang ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Platelet Activating Factor ◽  
Peritoneal Macrophages ◽  
Dependent Manner ◽  
Macrophage Phagocytosis ◽  
Monocytes And Macrophages ◽  
Paf Receptor ◽  
Factor Α ◽  
Dose Dependent ◽  
Phagocytic Killing

The immunomodulatory function of endothelial cells (EC) includes the initiation of leukocyte margination, diapedesis, and activation through the upregulation of various cell surface-associated molecules. However, the effect that EC have on the phagocytic function of neighboring monocytes and macrophages is less well described. To address this issue, microvascular EC were cocultured with murine peritoneal macrophages, first in direct contact, then in a noncontact coculture system, and macrophage phagocytosis and phagocytic killing were assessed. The presence of increasing concentrations of EC resulted in a dose-dependent increase in macrophage phagocytic killing. This stimulatory effect was inhibited in a dose-dependent manner by the pretreatment of macrophage/EC cocultures with WEB-2086 or CV-6209, specific platelet-activating factor (PAF)-receptor antagonists, but not by anti-tumor necrosis factor-α, anti-interleukin (IL)-1α, or anti-IL-1β. Furthermore, the effect was reproduced in the absence of EC by the exogenous administration of nanomolar concentrations of PAF. Microvascular EC potentiate macrophage phagocytic killing via the release of a soluble signal; PAF appears to be an important component of that signal.

scholarly journals Effects of esculentoside A on turnour necrosis factor production by mice peritoneal macrophages

1992 ◽  
Vol 1 (6) ◽  
pp. 375-377 ◽  
Author(s):  
Fang Jun ◽  
Zheng Qin Yue ◽  
Wang Hong Bin ◽  
Ju Dian Wen ◽  
Yi Yang Hua
Keyword(s):  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Inflammatory Mediator ◽  
Platelet Activating Factor ◽  
Peritoneal Macrophages ◽  
Dependent Manner ◽  
Anti Inflammatory ◽  
Dose Dependent ◽  
Necrosis Factor ◽  
Inflammatory Effect

Esculentoside A (EsA) is a saponin isolated from the roots of Phytolacca esculenta. Previous experiments showed that it had strong anti-inflammatory effects. Tumour necrosis factor (TNF) is an important inflammatory mediator. In order to study the mechanism of the anti-inflammatory effect of EsA, it was determined whether TNF production from macrophages was altered by EsA under lipopolysaccharide (LPS) stimulated conditions. EsA was found to decrease both extracellular and cell associated TNF production in a dose dependent manner at concentrations higher than 1 μmol/l EsA. Previous studies have showed that EsA reduced the releasing of platelet activating factor (PAF) from rat macrophages. The reducing effects of EsA on the release of TNF and PAF may explain its anti-inflammatory effect.

scholarly journals GAS6 Inhibits Granulocyte Adhesion to Endothelial Cells

Blood ◽  
1998 ◽  
Vol 91 (7) ◽  
pp. 2334-2340
Author(s):  
Gian Carlo Avanzi ◽  
Margherita Gallicchio ◽  
Flavia Bottarel ◽  
Loretta Gammaitoni ◽  
Giuliana Cavalloni ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Platelet Activating Factor ◽  
Polymorphonuclear Cells ◽  
Vascular Endothelial ◽  
Tnf Α ◽  
High Concentrations ◽  
Adhesive Interactions ◽  
Factor Α ◽  
Dose Dependent

GAS6 is a ligand for the tyrosine kinase receptors Rse, Axl, and Mer, but its function is poorly understood. Previous studies reported that both GAS6 and Axl are expressed by vascular endothelial cells (EC), which play a key role in leukocyte extravasation into tissues during inflammation through adhesive interactions with these cells. The aim of this work was to evaluate the GAS6 effect on the adhesive function of EC. Treatment of EC with GAS6 significantly inhibited adhesion of polymorphonuclear cells (PMN) induced by phorbol 12-myristate 13-acetate (PMA), platelet-activating factor (PAF), thrombin, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), but not that induced by FMLP and IL-8. GAS6 did not affect adhesion to resting EC. Titration experiments showed that high concentrations of GAS6 were needed to inhibit PMN adhesion and that inhibition was dose-dependent at the concentration range of 0.1 to 1 μg/mL. One possibility was that high concentrations were needed to overwhelm the effect of endogenous GAS6 produced by EC. In line with this possibility, treatment of resting EC with soluble Axl significantly potentiated PMN adhesion. Analysis of localization of GAS6 by confocal microscopy and cytofluorimetric analysis showed that it is concentrated along the plasma membrane in resting EC and treatment with PAF induces depletion and/or redistribution of the molecule. These data suggest that GAS6 functions as a physiologic antiinflammatory agent produced by resting EC and depleted when proinflammatory stimuli turn on the proadhesive machinery of EC.

scholarly journals GAS6 Inhibits Granulocyte Adhesion to Endothelial Cells

Blood ◽  
1998 ◽  
Vol 91 (7) ◽  
pp. 2334-2340 ◽  
Author(s):  
Gian Carlo Avanzi ◽  
Margherita Gallicchio ◽  
Flavia Bottarel ◽  
Loretta Gammaitoni ◽  
Giuliana Cavalloni ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Platelet Activating Factor ◽  
Polymorphonuclear Cells ◽  
Vascular Endothelial ◽  
Tnf Α ◽  
High Concentrations ◽  
Adhesive Interactions ◽  
Factor Α ◽  
Dose Dependent

Abstract GAS6 is a ligand for the tyrosine kinase receptors Rse, Axl, and Mer, but its function is poorly understood. Previous studies reported that both GAS6 and Axl are expressed by vascular endothelial cells (EC), which play a key role in leukocyte extravasation into tissues during inflammation through adhesive interactions with these cells. The aim of this work was to evaluate the GAS6 effect on the adhesive function of EC. Treatment of EC with GAS6 significantly inhibited adhesion of polymorphonuclear cells (PMN) induced by phorbol 12-myristate 13-acetate (PMA), platelet-activating factor (PAF), thrombin, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), but not that induced by FMLP and IL-8. GAS6 did not affect adhesion to resting EC. Titration experiments showed that high concentrations of GAS6 were needed to inhibit PMN adhesion and that inhibition was dose-dependent at the concentration range of 0.1 to 1 μg/mL. One possibility was that high concentrations were needed to overwhelm the effect of endogenous GAS6 produced by EC. In line with this possibility, treatment of resting EC with soluble Axl significantly potentiated PMN adhesion. Analysis of localization of GAS6 by confocal microscopy and cytofluorimetric analysis showed that it is concentrated along the plasma membrane in resting EC and treatment with PAF induces depletion and/or redistribution of the molecule. These data suggest that GAS6 functions as a physiologic antiinflammatory agent produced by resting EC and depleted when proinflammatory stimuli turn on the proadhesive machinery of EC.

Lysophosphatidylcholine transduces Ca2+ signaling via the platelet-activating factor receptor in macrophages

1997 ◽  
Vol 272 (1) ◽  
pp. H17-H24 ◽  
Author(s):  
T. Ogita ◽  
Y. Tanaka ◽  
T. Nakaoka ◽  
R. Matsuoka ◽  
Y. Kira ◽  
...  
Keyword(s):  
Chinese Hamster Ovary Cells ◽  
Platelet Activating Factor ◽  
Chinese Hamster ◽  
Receptor Activation ◽  
Peritoneal Macrophages ◽  
Free Calcium ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Paf Receptor ◽  
Web 2086

To clarify the molecular mechanism underlying the lysophosphatidylcholine (LPC) signaling, we studied the effect of LPC on the intracellular free calcium concentration ([Ca2+]i) in murine peritoneal macrophages. LPC when added alone induced biphasic elevation of [Ca2+]i, which consisted of a rapid increase followed by sustained elevation. LPC, when added with equimolar cholesterol, induced only the rapid increase in [Ca2+]i, which was blocked by WEB-2086, a selective platelet-activating factor (PAF) receptor antagonist. These results suggest LPC exerts a specific Ca2+ signaling. The sustained elevation reflected the cell lysis. Furthermore, we confirmed its pathway in a more specific manner using cloned PAF receptors expressed in Chinese hamster ovary cells. LPC induced an elevation of [Ca2+]i in a concentration-dependent manner only when the PAF receptor had been expressed, and the elevation of [Ca2+]i was blocked by WEB-2086. Taken together, LPC transduces Ca2+ signaling via the PAF receptor. Activation of the PAF receptor by LPC may indicate its novel important role in the pathogenesis of atherosclerosis.

Appraisal of Immunological Impacts of Melaleuca leucadendra Extract over Macrophage Performance in Vitro

2020 ◽  
Keyword(s):  
Nitric Oxide ◽  
Interleukin 2 ◽  
Dependent Manner ◽  
Reduced Pressure ◽  
Medical Plant ◽  
Dose Dependent ◽  
Level Production ◽  
Melaleuca Leucadendra ◽  
Phagocytic Killing

This trial research was performed to discuss the immune-influence of Melaleuca leucadendra ‘paper-bark tree’ dried leaves which is an important medical plant known in many regions in the world. The leaves were dissolved in a mixture of (ethanol + water) (3:1) mixture, then filtered, evaporated and dried under reduced pressure to obtain leaves extract. The macrophages of blood derived origin were provided from rats and mixed with three different leaves extracts doses in tissue culture plates and incubated then stained with fluorescent acridine orange and examined under fluorescent microscope to assess the phagocytic and killing potency. The wells contents were aspirated and assayed for nitric oxide and interleukin-2 levels. The results displayed an obvious increase in phagocytic, killing performance as well as nitric oxide and IL-2 level production than control in a dose dependent manner. The obtained results suggested the immune-stimulant impact of the paper-bark tree leaves.

scholarly journals Biochemical and biological activity of arginine deiminase from Streptococcus pyogenes M22

2016 ◽  
Vol 94 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Eleonora A. Starikova ◽  
Alexey V. Sokolov ◽  
Anna Yu. Vlasenko ◽  
Larisa A. Burova ◽  
Irina S. Freidlin ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Endothelial Cells ◽  
Streptococcus Pyogenes ◽  
Group A Streptococcus ◽  
Bacterial Pathogen ◽  
Arginine Deiminase ◽  
Dependent Manner ◽  
Group A ◽  
Micro Organisms ◽  
Dose Dependent

Streptococcus pyogenes (group A Streptococcus; GAS) is an important gram-positive extracellular bacterial pathogen responsible for a number of suppurative infections. This micro-organism has developed complex virulence mechanisms to avoid the host’s defenses. We have previously reported that SDSC from GAS type M22 causes endothelial-cell dysfunction, and inhibits cell adhesion, migration, metabolism, and proliferation in a dose-dependent manner, without affecting cell viability. This work aimed to isolate and characterize a component from GAS type M22 supernatant that suppresses the proliferation of endothelial cells (EA.hy926). In the process of isolating a protein possessing antiproliferative activity we identified arginine deiminase (AD). Further study showed that this enzyme is most active at pH 6.8. Calculating Km and Vmax gave the values of 0.67 mmol·L–1 and 42 s−1, respectively. A distinctive feature of AD purified from GAS type M22 is that its optimum activity and the maximal rate of the catalytic process is close to neutral pH by comparison with enzymes from other micro-organisms. AD from GAS type M22 suppressed the proliferative activity of endothelial cells in a dose-dependent mode. At the same time, in the presence of AD, the proportion of cells in G0/G1 phase increased. When l-Arg was added at increasing concentrations to the culture medium containing AD (3 μg·mL–1), the enzyme’s capacity to inhibit cell proliferation became partially depressed. The proportion of cells in phases S/G2 increased concomitantly, although the cells did not fully recover their proliferation activity. This suggests that AD from GAS type M22 has potential for the suppression of excessive cell proliferation.

Calcium dependence of the thrombin-induced increase in endothelial albumin permeability

1989 ◽  
Vol 66 (3) ◽  
pp. 1471-1476 ◽  
Author(s):  
H. Lum ◽  
P. J. Del Vecchio ◽  
A. S. Schneider ◽  
M. S. Goligorsky ◽  
A. B. Malik
Keyword(s):  
Endothelial Cells ◽  
Endothelial Permeability ◽  
Base Line ◽  
Dependent Manner ◽  
Extracellular Medium ◽  
Influx Rate ◽  
Before And After ◽  
Dependent Inhibition ◽  
Permeability Increase ◽  
Dose Dependent

We examined whether the increase in endothelial albumin permeability induced by alpha-thrombin is dependent on extracellular Ca2+ influx. Permeability of 125I-albumin across confluent monolayers of cultured bovine pulmonary artery endothelial cells was measured before and after the addition of 0.1 microM alpha-thrombin. In the presence of normal extracellular Ca2+ concentration ([Ca2+]o, 1000 microM), alpha-thrombin produced a 175 +/- 10% increase in 125I-albumin permeability. At lower [Ca2+]o (100, 10, 1, or less than 1 microM), alpha-thrombin caused a 140% increase in permeability (P less than 0.005). LaCl3 (1 mM), which competes for Ca2+ entry, blunted 38% of the increase in permeability. Preloading endothelial monolayers with quin2 to buffer cytosolic Ca2+ (Cai2+) produced a dose-dependent inhibition of the increase in 125I-albumin permeability. Preincubation with nifedipine or verapamil was ineffective in reducing the thrombin-induced permeability increase. A 60 mM K+ isosmotic solution did not alter base-line endothelial permeability. alpha-Thrombin increased [Ca2+]i in a dose-dependent manner and the 45Ca2+ influx rate. Extracellular medium containing 60 mM K+ did not increase 45Ca2+ influx, and nifedipine did not block the rise in 45Ca2+ influx caused by alpha-thrombin. Ca2+ flux into endothelial cells induced by alpha-thrombin does not occur through voltage-sensitive channels but may involve receptor-operated channels. In conclusion, the increase in endothelial albumin permeability caused by alpha-thrombin is dependent on Ca2+ influx and intracellular Ca2+ mobilization.

PMA-activated neutrophils decrease ectoenzyme activities in rabbit aortic endothelial cells in culture

1992 ◽  
Vol 263 (6) ◽  
pp. L657-L663
Author(s):  
X. Chen ◽  
M. Tzanela ◽  
M. K. Baumgartner ◽  
J. R. McCormick ◽  
J. D. Catravas
Keyword(s):  
Endothelial Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Aortic Endothelial Cells ◽  
Endothelial Monolayers ◽  
Activated Neutrophils ◽  
Ace Activity ◽  
Dose Dependent Decrease ◽  
Dose Dependent ◽  
Aortic Endothelial

We have studied the effects of phorbol 12-myristate 13-acetate (PMA)-activated neutrophils [polymorphonuclear leukocytes (PMN)] on endothelial ectoenzyme [angiotensin-converting enzyme (ACE) and 5'-nucleotidase (NCT)] activities in cultured rabbit aortic endothelial cells (EC) with the use of [3H]benzoyl-Phe-Ala-Pro and 14C-labeled AMP as substrates, respectively, under first-order reaction conditions. PMA (1–1,000 ng/ml) or PMN alone had no effect on ACE activity. When PMA was incubated together with PMN (PMN/EC = 1.25:1 or 2.5 x 10(5) neutrophils/ml) for 4 h in Earle's salts, a PMA dose-dependent decrease in ACE activity was observed. Threshold PMA concentration was 2 ng/ml. At 8 ng PMA/ml, ACE activity was totally abolished, without any evidence of cytotoxicity, as inferred from release of 51Cr from prelabeled EC. The decrease in ACE activity was also dependent on PMN concentration and was detectable at PMN/EC values as low as 1.25:10 (0.25 x 10(5) PMN/ml). Inhibition of ACE occurred as early as 1 h after incubation (PMA 10 ng/ml, PMN/EC = 1.25:1). PMA alone caused a small but significant increase in NCT activity, whereas PMA coincubation with PMN produced a significant decrease in NCT activity (20–29%), which was PMA and PMN concentration independent. PMA increased PMN adherence to endothelial monolayers in a concentration-dependent manner. Pretreating PMN with monoclonal antibody 60.3 (raised against the adhesion glycoprotein CD18) or placing a 2-microns filter between PMN and EC, protected the decrease in ACE activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Exogenous xanthine promotes neutrophil adherence to cultured endothelial cells

1997 ◽  
Vol 273 (2) ◽  
pp. G342-G347
Author(s):  
H. Ichikawa ◽  
R. E. Wolf ◽  
T. Y. Aw ◽  
N. Ohno ◽  
L. Coe ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Tissue Injury ◽  
Umbilical Vein ◽  
Platelet Activating Factor ◽  
Adhesion Assay ◽  
Neutrophil Adherence ◽  
Paf Receptor ◽  
Umbilical Vein Endothelial Cells ◽  
Adhesive Effect ◽  
Paf Receptor Antagonist

Oxidants generated by endothelial xanthine oxidase (XO) can help trigger free radical-mediated tissue injury. An important event in oxidant-mediated tissue injury is neutrophil-endothelial adhesion. Although activation of endothelial XO increases adhesion, little is known about xanthine in the adhesive effect of XO. This study examined administered xanthine on the adhesion of neutrophils. Endothelial [human umbilical vein endothelial cells (HUVEC)] monolayers were exposed to xanthine (15 min), and neutrophils were allowed to adhere to HUVEC in an adhesion assay. Adhesion was dose dependently increased by xanthine (3-100 microM). Either catalase (1,000 U/ml), oxypurinol (XO inhibitor; 100 microM), or platelet-activating factor (PAF) receptor antagonist (WEB 2086; 10 microM) reduced neutrophil adhesion. Superoxide dismutase (1,000 U/ml) had no effect. Pretreatment of HUVEC with 50 microM tungsten also blocked xanthine-induced adherence. Adhesion was also inhibited by preincubation with 100 U/ml heparin. Finally, anti-P-selectin antibody (PB1.3; 20 micrograms/ml) attenuated adhesion. Our results indicate that xanthine may promote neutrophil-endothelial adhesion via a hydrogen peroxide- and PAF-mediated P-selectin expression.

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