High-density lipoprotein enhancement of anticoagulant activities of plasma protein S and activated protein C

Key Points High-density lipoprotein and apolipoprotein A-I enhance activated protein C cytoprotective activity. High-density lipoprotein and apolipoprotein A-I significantly increase the rate at which activated protein C degrades cytotoxic extracellular histones.

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Determination of Protein C Antigen Levels in Hospitalized Patients with Blood Coagulative Defects

Clinical Oncology Research and Reports ◽

10.31579/2693-4787/020 ◽

2021 ◽

Vol 2 (1) ◽

pp. 1-04

Author(s):

George Zhu

Keyword(s):

Plasma Protein ◽

Protein C ◽

Activated Protein C ◽

Protein S ◽

Promyelocytic Leukemia ◽

Hospitalized Patients ◽

Cancer Cell Proliferation ◽

Healthy Individuals ◽

Acute Leukemias

Protein C, a vitamin K-dependent anticoagulant serine protease, is involved in blood coagulation. Activated protein C inactivates Va and VIIIa in purified protein systems and stimulates fibrinolysis by indirectly increasing the level of circulating plasminogen activator. In this process, protein S serve as an important factor for activated protein C. In recent years, excess protein S drives cancer cell proliferation and cell survival through oncogenic receptor Axl (Anexelekto). We determined changes of plasma protein C antigen by using rocket immunoassay both in 50 healthy individuals and 103 distinct hospitalized patients. In healthy individuals protein C antigen(PC:Ag) ranges o.6439- 1.4752 µ/ml. The results showed that plasma protein C antigen was considerably high in 22 diabetes mellitus. In contrast, the PC:Ag was significantly decreased in 19 liver cirrhosis(p< 0.001) and in closely line with serum albumin levels(p< 0.05). In 31 acute leukemias, on the average, there was slightly lower values in PC:Ag, and accompanied with the distribution of significant decrease of PC:Ag values in 5 FAB M5 subtype and in 9 hyperleukocytic leukemias. However, the 3 acute promyelocytic leukemia (APL) with overt laboratory criteria of disseminated intravascular coagulation (DIC) had protein C concentration no lower than the remaining 2 patients with infectious DIC, which suggested the coagulopathy in APL might be due to mechanisms different from other forms of DIC.

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Plasma protein S contains zinc essential for efficient activated protein C‐independent anticoagulant activity and binding to factor Xa, but not for efficient binding to tissue factor pathway inhibitor

The FASEB Journal ◽

10.1096/fj.08-123174 ◽

2009 ◽

Vol 23 (7) ◽

pp. 2244-2253 ◽

Cited By ~ 24

Author(s):

Mary J. Heeb ◽

Duane Prashun ◽

John H. Griffin ◽

Bonno N. Bouma

Keyword(s):

Tissue Factor ◽

Plasma Protein ◽

Protein C ◽

Tissue Factor Pathway Inhibitor ◽

Anticoagulant Activity ◽

Activated Protein C ◽

Factor Xa ◽

Protein S ◽

Tissue Factor Pathway

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Abstract 521: Apolipoprotein M Links High-density Lipoprotein to Myocardial Autophagy

Circulation Research ◽

10.1161/res.127.suppl_1.521 ◽

2020 ◽

Vol 127 (Suppl_1) ◽

Author(s):

Ali Javaheri ◽

Zhen Guo ◽

Ezhil Chandamarai ◽

Terrence Riehl ◽

Carla Valenzuela Ripoll ◽

...

Keyword(s):

Heart Failure ◽

High Density Lipoprotein ◽

Plasma Protein ◽

Density Lipoprotein ◽

High Density ◽

Autophagic Flux ◽

Doxorubicin Treatment ◽

Apolipoprotein M ◽

Protein Levels ◽

Doxorubicin Cardiotoxicity

Background: Apolipoprotein M (APOM) is a lipoprotein that binds sphingosine-1-phosphate (S1P) and high-density lipoprotein (HDL). APOM/S1P attenuate myocardial ischemia/reperfusion injury by reducing infarct size. We recently published that reduced APOM plasma protein levels are associated with mortality across the spectrum of human heart failure. With the goal of uncovering mechanisms by which APOM impacts heart failure mortality, we modeled doxorubicin cardiotoxicity in hepatocyte specific APOM overexpression (APOM TG ) and littermate controls. Results: Doxorubicin treatment acutely reduces APOM plasma protein levels in control mice. APOM TG mice exhibit ~3-5 fold increased APOM and ~2.5 fold increased S1P. In acute and chronic doxorubicin cardiotoxicity models, APOM TG mice were protected from mortality and reductions in left-ventricular mass and ejection fraction observed in littermate controls. In murine models of acute leukemia, doxorubicin effectively killed leukemic cells in control and APOM TG mice. In the myocardium, APOM TG mice and controls had similar levels of γ-H2AX foci after doxorubicin treatment, indicating similar levels of DNA damage, and electron microscopy indicated similar mitochondrial morphology. However, APOM TG mice exhibited enhanced autophagic flux, and APOM prevented doxorubicin-induced reductions in autophagic flux observed in littermate control mice (Figure). Mechanistically, treatment of neonatal rat cardiomyocytes with S1P mimetics attenuated doxorubicin-induced loss of lysosomal pH, suggesting that APOM may enhance lysosomal function via S1P. In the murine myocardium, doxorubicin reduced the nuclear protein content of transcription factor EB (TFEB), a master regulator of autophagy and lysosomal biogenesis, in control mice but not APOM TG mice. Furthermore, adeno-associated virus mediated knockdown of TFEB completely reversed the beneficial effects of APOM on the myocardium, leading to cardiomyopathy and mortality in APOM TG mice. Conclusions: Our studies identify APOM and S1P as regulators of TFEB in the myocardium, hence providing a mechanistic link between HDL and the autophagy-lysosome pathway in the murine heart. The role of APOM in myocardial autophagy may explain our observed clinical associations between reduced APOM and mortality.

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Protein S Released From Stimulated Platelets Has Anticoagulant Activity Independent of Activated Protein C and Tissue Factor Pathway Inhibitor (TFPI).

Blood ◽

10.1182/blood.v116.21.1137.1137 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1137-1137

Author(s):

Mary J. Heeb ◽

Erning Duan

Keyword(s):

Plasma Protein ◽

Neutralizing Antibodies ◽

Protein C ◽

Thrombin Generation ◽

Conflicts Of Interest ◽

Anticoagulant Activity ◽

Activated Protein C ◽

Protein S ◽

Platelet Protein ◽

Presence And Absence

Abstract Abstract 1137 Background: Platelets contain in their alpha granules ∼2.5% of the protein S in blood. It has been suggested that this protein S supports the anticoagulant activity of exogenous activated protein C (APC), but it is not known whether protein S that is released from stimulated platelets can exert anticoagulant activity that is independent of APC and TFPI. We recently showed that at least some of the anticoagulant activity of plasma protein S is independent of APC and TFPI, although data suggested that plasma protein S may also have TFPI-dependent activity. Objective and methods: To determine if platelet protein S has anticoagulant activity that is independent of APC and TFPI, prothrombinase and extrinsic FXase reactions were initiated on the surface of fresh stimulated or unstimulated washed platelets in the presence and absence of blocking antibodies against APC, TFPI, and/or protein S, or in the presence and absence of purified plasma-derived protein S. Platelets were adjusted to a concentration of 0.7 to 2 × 10e8/ml, which contained 2.3–6.5 nM total platelet protein S. The last platelet wash contained negligible amounts of plasma protein S. Results: Neutralizing anti-protein S antibodies allowed up to 5.7-fold (mean: 2.1 ± 1.5 –fold, n=13) more thrombin generation on calcium ionophore-stimulated platelets following supplementation with 50–500 pM FXa and 600 nM prothrombin, and allowed up to 2.5-fold (mean: 1.7 ± 0.7 –fold, n=11) more thrombin generation on platelets that were not ionophore-stimulated but were gradually stimulated following FXa and prothrombin supplementation. Anti-protein S antibodies had no effect on thrombin generation on platelets that were treated with prostaglandin E1 (PGE1) to suppress platelet activation and then supplemented with procoagulants. This implies that platelet protein S is released from stimulated platelets and downregulates thrombin generation on platelets, and that neutralizing anti-protein S antibodies block this activity of protein S. Anti-protein S antibodies allowed up to 1.8-fold (mean 1.5 ± 0.2 –fold, n=8) more FXa generation on the surface of stimulated platelets supplemented with 5 pM TF, 100 pM FVIIa, and 160 nM FX, but anti-protein S antibodies had no effect on FXa generation on platelets treated with PGE1. Most of these experiments were performed in the presence of neutralizing antibodies against TFPI and APC, but thrombin and FXa generation on platelets under the varying conditions described were unaffected by the presence of these neutralizing antibodies. Purified plasma-derived zinc-containing protein S downregulated thrombin and FXa generation on platelets (IC50 = 6–18 nM PS) and in plasma >10-fold more potently than zinc-deficient protein S. We could not demonstrate a synergistic anticoagulant effect when TFPI was combined with zinc-deficient protein S in the presence of stimulated platelets and procoagulant proteins. Conclusion: Protein S that is released from stimulated platelets exerts anticoagulant activity that is independent of TFPI and APC. Disclosures: No relevant conflicts of interest to declare.

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Defects in the protein C pathway

10.1055/s-0038-1643715 ◽

1987 ◽

Author(s):

P C Comp ◽

C T Esmon

Keyword(s):

Plasminogen Activator ◽

Plasma Protein ◽

Skin Necrosis ◽

Protein C ◽

Binding Protein ◽

Active Form ◽

Activated Protein C ◽

Protein S ◽

Receptor Protein ◽

Protein C Deficiency

Activated protein C functions as an anticoagulant by enzymatically degrading factors Va and Villa in the clotting cascade. Protein C may be converted to its enzymatically active form bythrombin. The rate at which thrombin cleavage of the zymogen occurs is greatly enhanced when thrombin is bound to an endothelial cell receptor protein, thrombomodulin. Activated proteinC has a relatively long half-life in vivo and the formation of activated protein C in response to low level thrombin infusion suggests that the protein C system may provide a feedback mechanism to limit blood clotting. Clinical support for such a physiologic role for activated protein C includes an increased incidence of thrombophlebitis and pulmonary emboli in heterozygous deficient individuals, and severe, often fatal, cutaneous thrombosis in homozygous deficient newborns. A third thrombotic condition associated with protein C deficiency is coumarin induced skin (tissue) necrosis. This localized skin necrosis occurs shortly after the initiation of coumarin therapy and is hypothesized to bedue to the rapid disappearance of protein C activity in the plasma beforean adequate intensity of anticoagulation is achieved. Recent estimates of heterozygous protein C deficiency range as high as 1 in 300 individuals in the general population. Since coumarin compounds are in routine clinical use throughout the world and skin necrosis remains a relatively rare clinical finding, this suggests that factors other than protein C deficiency alone may be involved in the pathogenesis of the skin necrosis.The anticoagulant properties of activated protein C are greatly enhanced by another vitamin K-dependent plasma protein, protein S. Protein S functions by increasing the affinity of activated protein C for cell surfaces.Protein S is found in two forms in plasma: free and in complex with C4b-binding protein, "an inhibitor of the complement system. Free protein S is functionally active and the complexed protein S is not active. Individuals congenitally deficient in protein S ae subject to recurrent thromboembolicevents. At least two classes of protin S deficiency occur.Some patienshavedecreased levels of protein S antigen and reduced protein S functional activity. A second group of deficient individuals have normal levels of protein S antigen but most or all their protein S is complexed to C4b-binding protein and they have little or no functional protein S activity. Such a protein S distribution could result from abnormal forms of protein S or C4b-binding protein or some other abnormal plasma or cellular component. Patients with functionally inactive forms of protein S have yet to be identified. Identification of protein S deficient individuals is complicated by thepossible effect of sex hormones on plasma protein S levels. Total protein S antigen is reduced during pregnancyand during oral contraceptive administration. This finding is of practicalclinical importance since the decrease in protein S which occurs during pregnancy may be an added risk factor for congenitally protein S deficient women and may explain why some proteinS deficient women experience their first episode of thrombosis during pregnancy.In addition to having anticoagulant properties, activated protein C enhances fibrinolysis, at least in part,by inhibiting the inhibitor of tissueplasminogen activator. This profibrinolytic effect is enhanced by protein S and cell surfaces. This protection of plasminogen activator activity suggests that the combination of tissue plasminogen activator and activated protein C may be useful in the treatment of coronary artery thrombi. Tissueplasminogen activator would promote clot lysis while activated protein C protected the plasminogen activatorfrom inhibition and also prevented further clot deposition. There is no evidence at present that fibrinolytic activity is reduced in protein C deficient individuals. The possible clinical relevance of this aspect of protein Cfunction in the predisposition of protein C deficient individuals to thrombosis remains to be defined.

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Lipid transfers between reconstituted high density lipoprotein complexes and low density lipoproteins: effects of plasma protein factors

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)38436-4 ◽

1988 ◽

Vol 29 (10) ◽

pp. 1349-1357

Author(s):

A Jonas ◽

K E Kézdy ◽

M I Williams ◽

K A Rye

Keyword(s):

High Density Lipoprotein ◽

Plasma Protein ◽

Density Lipoprotein ◽

Low Density Lipoproteins ◽

High Density ◽

Low Density

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Transfer of phosphatidylcholine, phosphatidylethanolamine and sphingomyelin from low- and high-density lipoprotein to human platelets

Biochemical Journal ◽

10.1042/bj3150781 ◽

1996 ◽

Vol 315 (3) ◽

pp. 781-789 ◽

Cited By ~ 35

Author(s):

Bernd ENGELMANN ◽

Christine KÖGL ◽

Robert KULSCHAR ◽

Barbara SCHAIPP

Keyword(s):

Membrane Protein ◽

High Density Lipoprotein ◽

Phospholipase C ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Protein S ◽

Human Platelets ◽

High Density ◽

Low Density ◽

Monomer Fluorescence

Following a 1 h incubation of human platelets with low-density lipoprotein (LDL) labelled in the apoprotein fraction (125I-apoB) or in phospholipid fractions [14C-labelled phosphatidylcholine (PC), phosphatidylethanolamine (PE) or sphingomyelin (SM)], the percentage of total 14C associated with the cells was about 3-fold higher than the percentage of 125I. Differences in temperature sensitivity also indicated differential interactions of phospholipids and apoprotein with platelets. In order to assess the amount of [14C]phospholipid transferred from LDL or high-density lipoprotein (HDL) to the cells, the quantity of bound lipoproteins was estimated by adding an excess of unlabelled lipoprotein, or by selectively degrading LDL- and HDL-associated [14C]PC and [14C]PE with phospholipase C. Incubation of platelets with LDL or HDL containing pyrenedecanoic acid-labelled PC or SM (py-PC, py-SM) increased pyrene monomer fluorescence, indicating incorporation of the phospholipids into platelets. With HDL as donor, incorporation of py-SM was greater than uptake of py-PC. Pretreating platelets with elastase dose-dependently inhibited uptake of py-SM and py-PC. Treatment of cells with phospholipase C indicated that the uptake of [14C]PC by platelets, and not the binding of lipoproteins to the cells, was partially inhibited by elastase. In conclusion, LDL and HDL rapidly deliver SM, PC and PE to platelets. Incorporation of LDL-derived phospholipids into platelets is unlikely to be mediated by endocytosis of lipoprotein particles. The uptake of the two choline-containing phospholipids appears to require the presence of specialized platelet membrane protein(s).

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Plasma protein S deficiency in familial thrombotic disease

Blood ◽

10.1182/blood.v64.6.1297.1297 ◽

1984 ◽

Vol 64 (6) ◽

pp. 1297-1300 ◽

Cited By ~ 316

Author(s):

HP Schwarz ◽

M Fischer ◽

P Hopmeier ◽

MA Batard ◽

JH Griffin

Keyword(s):

Plasma Protein ◽

Protein C ◽

Anticoagulant Activity ◽

Oral Anticoagulant Therapy ◽

Activated Protein C ◽

Protein S ◽

Factor X ◽

Protein C Deficiency ◽

Thrombotic Disease ◽

Disease Protein

Abstract A family with a history of severe recurrent venous thromboembolic disease was studied to determine if a plasma protein deficiency could account for observed disease. Protein S levels in plasma were determined immunologically using the Laurell rocket technique. The propositus, his mother, his aunt, and his cousin who were clinically affected had 17% to 65% of the control levels of protein S antigen (normal range, 71% to 147%). Since three of these patients were receiving oral anticoagulant therapy, the ratios of protein S to prothrombin, factor X, and protein C in these patients were compared with values for a group of orally anticoagulated controls. These results suggested that protein S is half-normal in all family members with thrombotic disease. Other proteins known to be associated with familial thrombotic disease, including antithrombin III, plasminogen, fibrinogen, and protein C, were normal. Because plasma protein S serves as a cofactor for the anticoagulant activity of activated protein C and because protein C deficiency is associated with recurrent thrombotic disease, it is suggested that recurrent thrombotic disease in this family is the result of an inherited deficiency of protein S.

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