scholarly journals Differential glycosylation of alpha-1-acid glycoprotein (AGP-1) contributes to its functional diversity

2020 ◽  
Author(s):  
Mosale Seetharam Sumanth ◽  
Shancy P Jacob ◽  
Kandahalli Venkataranganayaka Abhilasha ◽  
Bhanu Kanth Manne ◽  
Venkatesha Basrur ◽  
...  
Keyword(s):  
Acute Phase ◽  
Platelet Reactivity ◽  
Platelet Activating Factor ◽  
Human Platelets ◽  
Peptide Sequence ◽  
Human Neutrophils ◽  
Intracellular Camp ◽  
Acid Glycoprotein ◽  
Dose Dependent Fashion ◽  
Dose Dependent

AbstractAlpha-1-acid glycoprotein (AGP-1) is a positive acute phase glycoprotein with uncertain functions. Serum AGP-1 (sAGP-1) is primarily derived from hepatocytes and circulates as 12 to 20 different glycoforms. We isolated a glycoform secreted from stimulated human neutrophils (nAGP-1). Its peptide sequence was identical to hepatocyte-derived sAGP-1, but nAGP-1 differed from sAGP-1 in its chromatographic behaviour, electrophoretic mobility, and glycosylation. The function of these two glycoforms also differed. sAGP-1 activated neutrophil adhesion, migration and NETosis in a dose-dependent fashion, while nAGP-1 was ineffective as an agonist for these events. Furthermore, sAGP-1, but not nAGP-1, inhibited LPS-stimulated NETosis. However, nAGP-1 inhibited sAGP-1-stimulated neutrophil NETosis. The discordant effect of the differentially glycosylated AGP-1 glycoforms was also observed in platelets where neither of the AGP-1 glycoforms alone stimulated aggregation of washed human platelets, but sAGP-1, and not nAGP-1, inhibited aggregation induced by Platelet-activating Factor (PAF) or ADP, but not by thrombin. These functional effects of sAGP-1 correlated with intracellular cAMP accumulation and were accompanied by phosphorylation of the PKA substrate Vasodialator stimulated phosphoprotein (VASP) and reduction of Akt, ERK, and p38 phosphorylation. Thus, the sAGP-1 glycoform limits platelet reactivity while nAGP-1 glycoform also limits pro-inflammatory actions of sAGP-1. These studies identify new functions for this acute phase glycoprotein and demonstrate that the glycosylation of AGP-1 controls its effects on two critical cells of acute inflammation.

Inhibition of neutrophil L-selectin shedding: a potential anti-inflammatory effect of aprotinin

Perfusion ◽  
2000 ◽  
Vol 15 (6) ◽  
pp. 495-499 ◽  
Author(s):  
George Asimakopoulos ◽  
Kenneth M Taylor ◽  
Dorian O Haskard ◽  
R Clive Landis
Keyword(s):  
Endothelial Cell ◽  
Venous Blood ◽  
Platelet Activating Factor ◽  
Surface Expression ◽  
Cell Interaction ◽  
Dose Dependent Fashion ◽  
Anti Inflammatory ◽  
Dose Dependent ◽  
Inflammatory Action ◽  
Inflammatory Effect

The cardiopulmonary bypass (CPB)-related inflammatory response involves leucocyte activation and increased leucocyte-endothelial cell interaction. L-selectin is an adhesion molecule expressed on the surface of leucocytes which participates in the initial rolling step of the leucocyte-endothelial cell adhesion cascade. L-selectin is proteolytically cleaved off the surface of leucocytes when they become activated, an event that is regarded as a marker of leucocyte activation. Aprotinin is a protease inhibitor that has been used in cardiac surgery as a haemostatic agent and also exhibits certain anti-inflammatory properties. In this study, peripheral venous blood from volunteers was pre-incubated with aprotinin at 200, 800 and 1600 kallikrein inhibiting units (kiu)/ml and stimulated with the chemoattractants N-formyl-methyl-leucyl-phenylalanine (fMLP) or platelet activating factor (PAF). Surface expression of L-selectin on neutrophils was measured using a monoclonal antibody and flow cytometry. The results demonstrate that aprotinin inhibits shedding of L-selectin in a dose-dependent fashion ( p=0.0278 and 0.0005, respectively, at 800 and 1600 kiu/ml for fMLP-stimulated shedding; p=0.0017 and 0.0010, respectively, at 200 and 800 kiu/ml for PAF-stimulated shedding). This effect may be of significance with respect to the anti-inflammatory action of aprotinin in patients undergoing CPB.

Inhibition Of Platelet Aggregation, Malonyldialdehyde And Thromboxane Formation By Hydroperoxides Of Arachidonic Acid

1981 ◽  
Author(s):  
D Aharonv ◽  
J B Smith ◽  
M J Silver
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Lipoxygenase Pathway ◽  
Dose Dependent Fashion ◽  
Induced Aggregation ◽  
Layer Chromatography ◽  
Dose Dependent ◽  
Thromboxane Formation

The arachidonate hydroperoxides 12-HPETE and 15-HPETE were biosynthesized from arachidonic acid using partially purified human platelet lipoxygenase or soybean lipoxidase respectively, and isolated by thin layer chromatography. Both compounds inhibited the arachidonic acid- induced aggregation of washed human platelets, suspended in calcium-free Krebs Henseleit solution, in a dose dependent fashion at concentrations between 1 and 50 uM. No inhibition was seen with up to 100 uM of these hydroperoxides when platelet -rich plasma was used. 12-HPETE (in micromolar concentrations) inhibited the formation of both thromboxane B2 (radioimmunoassay) and malonyldialdehyde (spectrophotometrie assay) when washed platelets were incubated with arachidonic acid. The 12-hydroxide, 12-HETE also inhibited platelet aggregation and thromboxane formation, but was less potent than 12-HPETE. We suggest that arachidonate hydroperoxide generated in platelets via the lipoxygenase pathway modulates platelet aggregation induced by arachidonic acid by inhibiting thromboxane formation.

Platelet-activating factor increases platelet-dependent glycoconjugate secretion from tracheal submucosal gland

1989 ◽  
Vol 257 (6) ◽  
pp. L373-L378 ◽  
Author(s):  
T. Sasaki ◽  
S. Shimura ◽  
K. Ikeda ◽  
H. Sasaki ◽  
T. Takishima
Keyword(s):  
Platelet Activating Factor ◽  
Thromboxane A2 ◽  
Submucosal Gland ◽  
Thromboxane Receptor ◽  
Significant Stimulation ◽  
Submucosal Glands ◽  
Dose Dependent Fashion ◽  
Thromboxane Receptor Antagonist ◽  
Dose Dependent ◽  
Thromboxane A2 Analogue

Using isolated glands from feline trachea, we examined the effect of platelet-activating factor (PAF) on radiolabeled glycoconjugate release and glandular contraction by measuring induced tension in the absence or presence of platelets. PAF alone did not produce any significant glandular contraction nor any significant change in glycoconjugate release from isolated glands. In the presence of purified platelets containing no plasma, PAF (10(-8) to 10(-5) M) produced significant glycoconjugate secretion in a dose-dependent fashion, but it produced no significant glandular contraction. PAF-evoked glycoconjugate secretion was time dependent, reaching a peak response of 277% of control 15-30 min after the exposure of isolated glands to 10(-5) M PAF in the presence of platelets and returning to 135% of controls at 2 h. Platelets alone did not produce any significant stimulation in glycoconjugate release. CV-3988, a known PAF antagonist, inhibited the secretory response to PAF. Methysergide, a known antagonist to receptors for 5-hydroxytryptamine, did not alter PAF-evoked glycoconjugate secretion. Both indomethacin and SQ 29,548, a thromboxane receptor antagonist, abolished the PAF-evoked glycoconjugate secretion from isolated submucosal glands. Epithiomethanothromboxane A2, a stable thromboxane A2 analogue, produced a significant increase in glycoconjugate secretion in a dose-dependent fashion. These findings indicate that PAF increases glycoconjugate release in the presence of platelets and that the increase is dependent on some aspect of platelet function, namely thromboxane generation.

scholarly journals Monoclonal antibody-defined functional epitopes on the adhesion- promoting glycoprotein complex (CDw18) of human neutrophils

Blood ◽  
1986 ◽  
Vol 67 (4) ◽  
pp. 1007-1013 ◽  
Author(s):  
WJ Wallis ◽  
DD Hickstein ◽  
BR Schwartz ◽  
CH June ◽  
HD Ochs ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Active Site ◽  
Bacterial Infections ◽  
Quaternary Structure ◽  
Alpha Subunit ◽  
Human Neutrophils ◽  
Glycoprotein Complex ◽  
Dose Dependent Fashion ◽  
Alpha Beta ◽  
Dose Dependent

Abstract We have evaluated the functional and immunochemical activities of three monoclonal antibodies (MoAbs) minimally reactive with adherence- defective neutrophils (PMN) from a patient with recurrent bacterial infections. In studies with normal PMN, MoAbs OKM1 and 60.1 both precipitate the same 165kd alpha-subunit (alpha M) within an alpha-beta heterodimer complex (CD11). The CD11 complex is part of a larger complex composed of four glycoproteins (CDw18) precipitated by MoAb 60.3, with properties suggesting that the CDw18 complex is equivalent to the Mac-1, LFA-1, p150, 95 glycoprotein family implicated in adherence-dependent leukocyte functions. PMN adherence to endothelium, spreading on surfaces, aggregation, and phagocytosis of zymosan particles were all inhibited in a dose-dependent fashion by MoAb 60.1 (analogous to previous studies with MoAb 60.3) while MoAb OKM1 had no effect. These findings unify previously disparate observations and suggest that a functionally active site on the adherence promoting glycoprotein complexes CD11 and CDw18 is distant from the alpha M epitope recognized by MoAb OKM1 but closely associated with the alpha M epitope recognized by MoAb 60.1 and the beta-epitope (or epitope created by alpha-beta quaternary structure) recognized by MoAb 60.3.

scholarly journals Effect of Platelet-activating Factor onin vitroandin vivoInterleukin-6 Production

1994 ◽  
Vol 3 (4) ◽  
pp. 281-285 ◽  
Author(s):  
B. Pignol ◽  
T. Maisonnet ◽  
P. Guinot ◽  
J. M. Mencia-Huertac ◽  
P. Braquet
Keyword(s):  
Platelet Activating Factor ◽  
Similar Extent ◽  
Rat Serum ◽  
Mouse Fibroblasts ◽  
Dose Dependent Fashion ◽  
The One ◽  
Dose Dependent ◽  
Peak Increase

The aim of the present study was to investigate the possible effect of platelet-activating factor (PAF), by comparison with interleukin-1β and polyriboinositic/polyribocytidylic (poly I–C) acid, on IL-6 production by L 929 mouse fibroblasts. At concentrations above 1 μM PAF, the production of IL-6 by mouse fibroblasts was enhanced in a dose dependent fashion. At 5 μM PAF, the peak increase (60.1 ± 19.4 U/ml) was similar to that induced by 50 μg/ml poly I–C (60.0 ± 35.0 U/ml) and higher than the one evoked by 100 U/ml IL-1β (3.8 ± 1.8 U/ml). The increase of 11-6 activity induced by 5 μM PAF was maximal after a 22 h incubation period with L 929 cells. Lyso-PAF (5 μM) also increased IL-6 activity from fibroblasts to a similar extent compared with 5 μM PAF. In addition, the IL-6 activity induced by 5 μM PAF was still observed when the specific PAF antagonist, BN 52021 (10 μM), was added to the incubation medium of L 929 cells. The result suggests that the production of IL-6 by L 929 cells evoked by PAFin vitrois not receptor mediated. Thein vivoeffect of PAF on IL-6 production was also investigated in the rat. Two hours after intravenous injection of PAF (2 to 4 μg/kg), a dramatic increase of IL-6 activity in rat serum was observed, this effect being dose dependent. The increase of IL-6 induced by 3 μg/kg PAF was not observed when the animals were treated with the PAF antagonist, BN 52021 (1 to 60 mg/kg0. These results demonstrate that PAF modulates IL-6 production and that thein vivoeffect is receptor mediated.

scholarly journals Monoclonal antibody-defined functional epitopes on the adhesion- promoting glycoprotein complex (CDw18) of human neutrophils

Blood ◽  
1986 ◽  
Vol 67 (4) ◽  
pp. 1007-1013 ◽  
Author(s):  
WJ Wallis ◽  
DD Hickstein ◽  
BR Schwartz ◽  
CH June ◽  
HD Ochs ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Active Site ◽  
Bacterial Infections ◽  
Quaternary Structure ◽  
Alpha Subunit ◽  
Human Neutrophils ◽  
Glycoprotein Complex ◽  
Dose Dependent Fashion ◽  
Alpha Beta ◽  
Dose Dependent

We have evaluated the functional and immunochemical activities of three monoclonal antibodies (MoAbs) minimally reactive with adherence- defective neutrophils (PMN) from a patient with recurrent bacterial infections. In studies with normal PMN, MoAbs OKM1 and 60.1 both precipitate the same 165kd alpha-subunit (alpha M) within an alpha-beta heterodimer complex (CD11). The CD11 complex is part of a larger complex composed of four glycoproteins (CDw18) precipitated by MoAb 60.3, with properties suggesting that the CDw18 complex is equivalent to the Mac-1, LFA-1, p150, 95 glycoprotein family implicated in adherence-dependent leukocyte functions. PMN adherence to endothelium, spreading on surfaces, aggregation, and phagocytosis of zymosan particles were all inhibited in a dose-dependent fashion by MoAb 60.1 (analogous to previous studies with MoAb 60.3) while MoAb OKM1 had no effect. These findings unify previously disparate observations and suggest that a functionally active site on the adherence promoting glycoprotein complexes CD11 and CDw18 is distant from the alpha M epitope recognized by MoAb OKM1 but closely associated with the alpha M epitope recognized by MoAb 60.1 and the beta-epitope (or epitope created by alpha-beta quaternary structure) recognized by MoAb 60.3.

Neutrophil CD11B Expression and Neutrophil Activation in Pre-Eclampsia

1997 ◽  
Vol 92 (1) ◽  
pp. 37-44 ◽  
Author(s):  
A. Barden ◽  
D. Graham ◽  
L. J. Beilin ◽  
J. Ritchie ◽  
R. Baker ◽  
...  
Keyword(s):  
Vascular Dysfunction ◽  
Post Partum ◽  
Platelet Activating Factor ◽  
Normal Pregnancy ◽  
Neutrophil Activation ◽  
Cd11b Expression ◽  
Similar Dose ◽  
Dose Dependent Fashion ◽  
Dose Dependent

1. Neutrophil activation was examined in 22 women with pre-eclampsia and 22 age- and gestation-matched control subjects using whole-blood flow cytometry to assess basal and platelet-activating factor stimulated CD11b and CD18. 2. Basal neutrophil CD11b expression was significantly increased in women with pre-eclampsia compared with normal pregnancy before delivery. A similar non-significant trend for CD18 was also observed. 3. Before delivery, neutrophil CD11b expression increased in a dose-dependent fashion after platelet-activating factor stimulation, with the differences between the groups maintained. A similar dose-dependent increase in CD18 expression was observed after platelet-activating factor. 4. There were no between-group differences in expression of either CD11b or CD18 at either 6 weeks or 6 months post partum, either before or after platelet-activating factor stimulation. 5. Neutrophil CD11b was positively correlated with plasma uric acid (r = 0.44, P = 0.04) in women with pre-eclampsia, suggesting that the extent of neutrophil activation correlates with disease severity. 6. An increase in basal neutrophil CD11b expression in women with pre-eclampsia is likely to be an index of neutrophil activation in vivo. Neutrophil release of free radicals and proteases may then help perpetuate a vicious cycle of endothelial and vascular dysfunction in the placental and systemic circulations. The cause of this activation is not known but could involve platelet activation, increased production of endothelin-1 or release of cytokines. Further studies will be required to elucidate the consequences of neutrophil activation in pre-eclampsia.

The Antiheparin And Antiplatelet-Aggregating Effects Of Human α1-Acid Glycoprotein; Influence On Heparin Tolerance In Acute Phase Reactions

1981 ◽  
Author(s):  
P Andersen ◽  
P Kierulf ◽  
H C Godal
Keyword(s):  
Acute Phase ◽  
Platelet Reactivity ◽  
Inhibitory Effect ◽  
Acute Phase Reaction ◽  
Phase Reaction ◽  
Clotting Time ◽  
Acid Glycoprotein ◽  
Disease States ◽  
Time Systems ◽  
Acute Phase Reactions

The antiheparin effect of human α1-n-acid glycoprotein (α1-acid GP), in thrmbin clotting time systems, was originally observed after the addition of purified α1-acid GP to heparinized, citrated human plasma. The α1-acid GP used in that and other studies was rather crude. In the present study, however, a similar antiheparin effect has been observed with highly purified, non-desialyzed α1-n-acid GP. Furthermore, the inhibitory effect of this highly purified α1-acid GP on the thronbin-induced platelet aggregation was identical to that of the less purified preparation. The antiheparin effect of highly purified α1-acid GP isolated in parallel frcm pooled plasma of patients with acute phase reactions and from healthy controls was likewise identical.In patients (n=10), with acute phase reaction, only the concentration of α1-acid GP was negatively correlated with the heparin thrcrnbin clotting time (r=0.42), indicating α1-acid GP to be a major contributor to the increased heparin tolerance observed during such disease states.Removal of α1-acid GP by precipitating with rabbit anti- human α1-acid GP antibodies failed to danonstrate the heparin-neutralizing effect of α1-acid GP, probably because inmunoglobulins per se possess heparin-neutralizing activity.Our findings suggest that α1-acid GP, during the acute phase reaction, interacts in a way to reduce untimely consequences of plasma hypercoagulability and/or platelet reactivity.

scholarly journals Mammalian actin-related protein 2/3 complex localizes to regions of lamellipodial protrusion and is composed of evolutionarily conserved proteins

1997 ◽  
Vol 328 (1) ◽  
pp. 105-112 ◽  
Author(s):  
M. Laura MACHESKY ◽  
Emer REEVES ◽  
Frans WIENTJES ◽  
J. Frederick MATTHEYSE ◽  
Ann GROGAN ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protein Complex ◽  
Human Platelets ◽  
Peptide Sequence ◽  
Platelet Derived Growth Factor ◽  
Human Neutrophils ◽  
Sequence Information ◽  
Related Protein ◽  
Novel Proteins ◽  
Evolutionarily Conserved

Human neutrophils contain a complex of proteins similar to the actin-related protein 2/3 (Arp2/3) complex of Acanthamoeba. We have obtained peptide sequence information for each member of the putative seven-protein complex previously described for Acanthamoeba and human platelets. From the peptide sequences we have identified cDNA species encoding three novel proteins in this complex. We find that in addition to Arp2 and Arp3, this complex contains a relative of the human (Suppressor of Profilin) SOP2Hs protein and four previously unknown proteins. These proteins localize in the cytoplasm of fibroblasts that lack lamellipodia, but are enriched in lamellipodia on stimulation with serum or platelet-derived growth factor. We propose a conserved and dynamic role for this complex in the organization of the actin cytoskeleton.

MODE OF ACTION OF A NOVEL ANTI-PLATELET AGENT (E-5510)

1987 ◽  
Author(s):  
T Saeki ◽  
K HARADA ◽  
T Youshimura ◽  
Y Nakamura ◽  
T Fujimori ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Human Platelets ◽  
Cyclooxygenase Inhibitor ◽  
Inhibit Platelet Aggregation ◽  
Camp Content ◽  
Anti Platelet Agent ◽  
Intracellular Ca ◽  
Dose Dependent Fashion ◽  
Dose Dependent

A novel anti-platelet agent, 4-cyano-5,5-bis(4-methoxy-phenyl)-4-pentenoic acid(E-5510), has been shown to inhibit platelet aggregation and secretion induced by thrombin as well as by other inducers such as ADP, collagen and PAF. Although E-5510 can act as a cyclooxygenase inhibitor,inhibition of cyclooxygenase may not be the primary mode of action since this compound effectively inhibits thrombin-induced platelet activation. In this paper, effects^of E-5510 on arachidonic acid (AA) metabolism, intracellular Ca++ and cAMP in human platelets are examined.(1) Effect on AA metabolism. Platelets prelabeled with [14 C]-AA were stimulated with thrombin. E-5510 inhibited not only thromboxane A2 and HHT generation but also 12-HETE generation in a dose-dependent fashion. The total AA released was also reduced by E-5510. An almost 50% reduction was obtained by 10 uM of this compound. On the other hand, a cyclooxygenase inhibitor such as U-53059 increased 12-HETE generation in a dose-dependent fashion. In addition to the inhibition of AA metabolism, E-5510 exerted inhibitory effects on phosphatidic acidgeneration, which suggests the possible inhibition of phospholipase C activity by this compound.(2) Effect on intracellular Ca++ and protein phosphorylation. Intracellular Ca++ mobilization was examined using Fura-2 loaded human platelet suspension. The increase in intracellular Ca induced by thrombin was inhibited by E-5510 and the increase in phosphorylation of 40 K protein was also suppressed by this compound after the stimulation of human platelets by thrombin.(3) Effect on cAMP. Platelets were incubated with 10-100 uM of E-5510 and the cAMP content in human platelets was measured. E-5510 increased the cAMP content in a dose-dependent fashion. In platelet homogenate, E-5510 inhibited phosphodiesterase activity with an IC50 of 10 uM.These results suggest that E-5510 may inhibit platelet aggregation and secretion through the multiple modes of action, such as inhibition of phospholipase C, phosphodiesterase and cyclooxygenase, in the process of platelet activation.

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