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Biomedical subjects

J M Freyssinet

Publications and source records attributed to J M Freyssinet.

At least 19 recordsLinked to original sources
PubMed2005

Elevated levels of procoagulant microparticles in a patient with myocardial infarction, antiphospholipid antibodies and multifocal cardiac thrombosis.

Circulating procoagulant microparticles (MP) are pathogenic markers of enhanced coagulability associated to a variety of disorders and released from stimulated vascular cells. When derived from endothelial cells, MP were found characteristic of thrombotic propensity in primary antiphospholipid syndrome (APS). The prothrombotic status of a patient with antiphospholipid antibodies (APL), a past history of mesenteric vein thrombosis and presenting myocardial infarction and extensive intracardiac thrombosis was examined by measurement of circulating procoagulant MP. MP of platelet and endothelial origins were highly elevated with respect to values detectable in patients with myocardial infarction and no history of APS (6- and 3-fold elevation, respectively) or in healthy volunteers (13- and 25-fold elevation, respectively). In this particular patient, with moderate APL titer, a drastic release of procoagulant MP could have contributed to thrombus growth and the development of extensive intracardiac thrombosis.

Journal Article↗
PubMed2005

[The significance of circulating microparticles in physiology, inflammatory and thrombotic diseases].

BACKGROUND: In multicellular organisms, apoptosis and subsequent microparticle shedding play a key role in homeostasis. Having long been considered as << cellular dust >>, microparticles released in biological fluids upon cell activation or apoptosis appear as multifunctional bioeffectors involved in the modulation of key functions including immunity, inflammation, hemostasis and thrombosis, angiogenesis. MP constitute reliable markers of vascular damage, accessible to biological detection whilst the cells they originate from remain sequestered in tissues or are promptly submitted to phagocytosis. RECENT FINDINGS: MP modulate biological functions of target cells through the transfer of cytoplasmic content, lipids and membrane receptors. The pharmacological modulation of circulating levels of microparticles could be of particular interest in thrombotic or inflammatory diseases, cancer or hemophilia. CONCLUSION: MP can now be viewed not only as a hallmark of cell damage but also as a true biological tool.

Adult↗
PubMed2005

[Microparticles and cardiovascular disease].

Microparticles are membrane fragments liberated by activated or apoptopic cells. Thought for a long time to be cellular debris with no specific biologic function, in the vascular compartment they are a circulating reservoir of cellular effectors involved in thrombosis, inflammation, vascular remodelling and angiogenesis. High concentrations of circulating procoagulating microparticles found in many cardiovascular diseases indicate the importance of platelet, endothelial and monocytic activation and could contribute to the persistence of atherothrombotic disease. Pharmacological modulation of circulating microparticle concentrations could become a major therapeutic target in the future.

Blood Coagulation↗
PubMed2004

[Procoagulant membranous microparticles and atherothrombotic complications in diabetics].

Endothelial apoptosis and platelet activation play a key role in atherothrombotic event. These two mechanisms resulting membrane thickening leading to procoagulant microparticle (MP) liberation into the blood stream. In the vascular compartment, MP contribute to increased thrombin formation, to platelet activation, and prolong inflammation of the arterial wall by inducing the synthesis of cytokines and adhesion of glycoproteins by the endothelial cells. In diabetic patients, increased endothelial apoptosis associated with intense platelet and monocytic activation could contribute to accelerated atherothrombosis. Endothelial, platelet and monocytic derived MP, found in high concentrations in these patients, induce a prothrombotic, proadhesive and proinflammatory tendency in the vascular comportment which could directly impact on the vascular prognosis. In diabetes, increased platelet or monocytic MP is a marker for microvascular disease. Likewise, in acute coronary syndromes of diabetic patients, high concentrations of procoagulant MP could be associated with a poor cardiovascular prognosis. In these diabetic patients, many treatments (antioxidant, antiplatelet, lipid lowering, antihypertensive) significantly reduce the levels of MP and parameters associated with inflammation. MP are one of the key factors linking inflammation, oxidative stress, apoptosis and thrombosis in accelerated atherothrombotic disease of the diabetic. In future, the measurement of MP should help evaluate the efficacy of antioxidant and antiplatelet therapy, especially in diabetic patients.

Antioxidants↗
PubMed2001

Vitamin C inhibits endothelial cell apoptosis in congestive heart failure.

BACKGROUND: Proinflammatory cytokines like tumor necrosis factor-alpha and oxidative stress induce apoptotic cell death in endothelial cells (ECs). Systemic inflammation and increased oxidative stress in congestive heart failure (CHF) coincide with enhanced EC apoptosis and the development of endothelial dysfunction. Therefore, we investigated the effects of antioxidative vitamin C therapy on EC apoptosis in CHF patients. METHODS AND RESULTS: Vitamin C dose dependently suppressed the induction of EC apoptosis by tumor necrosis factor-alpha and angiotensin II in vitro as assessed by DNA fragmentation, DAPI nuclear staining, and MTT viability assay. The antiapoptotic effect of vitamin C was associated with reduced cytochrome C release from mitochondria and the inhibition of caspase-9 activity. To assess EC protection by vitamin C in CHF patients, we prospectively randomized CHF patients in a double-blind trial to vitamin C treatment versus placebo. Vitamin C administration to CHF patients markedly reduced plasma levels of circulating apoptotic microparticles to 32+/-8% of baseline levels, whereas placebo had no effect (87+/-14%, P<0.005). In addition, vitamin C administration suppressed the proapoptotic activity on EC of the serum of CHF patients (P<0.001). CONCLUSIONS: Administration of vitamin C to CHF patients suppresses EC apoptosis in vivo, which might contribute to the established functional benefit of vitamin C supplementation on endothelial function.

Administration, Oral↗
PubMed2001

Deciphering the plasma membrane hallmarks of apoptotic cells: phosphatidylserine transverse redistribution and calcium entry.

BACKGROUND: During apoptosis, Ca2+-dependent events participate in the regulation of intracellular and morphological changes including phosphatidylserine exposure in the exoplasmic leaflet of the cell plasma membrane. The occurrence of phosphatidylserine at the surface of specialized cells, such as platelets, is also essential for the assembly of the enzyme complexes of the blood coagulation cascade, as demonstrated by hemorrhages in Scott syndrome, an extremely rare genetic deficiency of phosphatidylserine externalization, without other apparent pathophysiologic consequences. We have recently reported a reduced capacitative Ca2+ entry in Scott cells which may be part of the Scott phenotype. RESULTS: Taking advantage of these mutant lymphoblastoid B cells, we have studied the relationship between this mode of Ca2+ entry and phosphatidylserine redistribution during apoptosis. Ca2+ ionophore induced apoptosis in Scott but not in control cells. However, inhibition of store-operated Ca2+ channels led to caspase-independent DNA fragmentation and decrease of mitochondrial membrane potential in both control and Scott cells. Inhibition of cytochrome P450 also reduced capacitative Ca2+ entry and induced apoptosis at comparable extents in control and Scott cells. During the apoptotic process, both control and more markedly Scott cells externalized phosphatidylserine, but in the latter, this membrane feature was however dissociated from several other intracellular changes. CONCLUSIONS: The present results suggest that different mechanisms account for phosphatidylserine transmembrane migration in cells undergoing stimulation and programmed death. These observations testify to the plasticity of the plasma membrane remodeling process, allowing normal apoptosis even when less fundamental functions are defective.

Apoptosis↗
PubMed2001

The clonal analysis of anticardiolipin antibodies in a single patient with primary antiphospholipid syndrome reveals an extreme antibody heterogeneity.

The mechanism underlying the prothrombotic state that characterizes the primary antiphospholipid syndrome proves to be difficult to define mainly because of the variety of the phospholipid and protein targets of antiphospholipid antibodies that have been described. Much of the debate is related to the use of polyclonal antibodies during the different antiphospholipid assays. To better describe the antiphospholipid antibodies, a strategy was designed to analyze the reactivity of each one antibody making up the polyclonal anticardiolipin activity, breaking down this reactivity at the clonal level. This was performed in a single patient with primary antiphospholipid syndrome by combining (1) the antigen-specific selection of single cells sorted by flow cytometry using structurally bilayered labeled anionic phospholipids and (2) the cloning of immunoglobulin (Ig) variable (V) region genes originating from individual IgG anticardiolipin-specific B cells by a single-cell polymerase chain reaction technique. The corresponding V regions were cloned in order to express human recombinant antibodies in insect cells by a baculovirus expression system. The molecular analysis, the fine specificity, and the protein cofactor dependency of the first 5 monoclonal IgG anticardiolipins are reported here. This clonal analysis reveals the extreme heterogeneity of these antibodies, which could account for the difficulties in the previous attempts to define the pathogenic antiphospholipid response. This approach should help to unravel the complex antiphospholipid immune response and the mechanism of the prothrombotic state associated with these antibodies, but it could also shed some light on their possible origins. (Blood. 2001;97:3820-3828)

Adult↗
PubMed2001

Circulating procoagulant microparticles in women with unexplained pregnancy loss: a new insight.

One of the frequently proposed mechanisms for pregnancy losses refers to uteroplacental thrombosis. However the contribution of classical thrombotic risk factors remains questionable and, if real, does not account for a large number of pregnancy losses. The aim of this study was to investigate the presence of circulating procoagulant microparticles, a new marker of cell activation already associated with various prothrombotic clinical settings. Microparticles were assessed by an original prothrombinase assay on platelet depleted plasma obtained from 74 women with a history of pregnancy loss without apparent cause and 50 controls. Patients were studied at least 2 months after the last obstetrical event and were classified into 2 groups: 49 women with at least 3 consecutive spontaneous abortions at or before the 10th postmenstrual week and 25 with at least one fetal death beyond the 10th postmenstrual week. Among the 74 patients, 41 had increased levels of circulating microparticles, 29 belonging to the group of early pregnancy loss (59%) and 12 to the group of late pregnancy loss (48%). The high prevalence of increased levels of procoagulant microparticles in both groups makes this new marker very promising for the understanding, follow up and therapeutical handling of pregnancy loss.

Abortion, Habitual↗
PubMed2000

Relation between phosphatidylserine exposure and store-operated Ca(2+) entry in stimulated cells.

A significant increase in intracellular Ca(2+) is required to trigger the remodeling of the cell plasma membrane. Scott syndrome is an extremely rare inherited disorder of the transmembrane migration of phosphatidylserine toward the exoplasmic leaflet in blood cells. We have recently reported a reduced capacitative Ca(2+) entry in Scott cells [Martínez et al. (1999) Biochemistry 38, 10092-10098]. We have investigated here the links between defective phosphatidylserine exposure and Ca(2+) signaling in Scott cells by focusing on the Ca(2+) entry following the emptying of intracellular stores. After depletion of caffeine- or thapsigargin-sensitive stores, Ca(2+) entry was lower in Scott compared to control lymphoblasts. However, the simultaneous depletion of both types of stores restored a normal Ca(2+) influx across the plasma membrane in Scott cells and phosphatidylserine externalization ability was improved concomitantly with capacitative Ca(2+) entry. These observations point to the essential role of capacitative Ca(2+) entry in the control of phosphatidylserine exposure of stimulated cells.

Aged↗
PubMed2000

Regulation of phosphatidylserine transbilayer redistribution by store-operated Ca2+ entry: role of actin cytoskeleton.

The phosphatidylserine transmembrane redistribution at the cell surface is one of the early characteristics of cells undergoing apoptosis and also occurs in cells fulfilling a more specialized function, such as the phosphatidylserine-dependent procoagulant response of platelets after appropriate activation. Although an increase in cytoplasmic Ca2+ is essential to trigger the remodeling of the plasma membrane, little is known about intracellular signals leading to phosphatidylserine externalization. Here, the role of store-operated Ca2+ entry on phosphatidylserine exposure was investigated in human erythroleukemia HEL cells, a pluripotent lineage with megakaryoblastic properties. Ca2+ entry inhibitors (SKF-96365, LaCl(3), and miconazole) inhibited store-operated Ca2+ entry in A23187- or thapsigargin-stimulated cells and reduced the degree of phosphatidylserine externalization concomitantly, providing evidence for a close link between the two processes. In cells pretreated with cytochalasin D, an agent that disrupts the microfilament network of the cytoskeleton, store-operated Ca2+ entry and phosphatidylserine externalization at the cell surface were inhibited. In a context where most of the key actors remain to be identified, these results provide evidence for the implication of both store-operated Ca2+ entry and cytoskeleton architectural organization in the regulation of phosphatidylserine transbilayer migration.

Actins↗
PubMed2000

Elevated levels of shed membrane microparticles with procoagulant potential in the peripheral circulating blood of patients with acute coronary syndromes.

BACKGROUND: Apoptotic microparticles are responsible for almost all tissue factor activity of the plaque lipid core. We hypothesized that elevated levels of procoagulant microparticles could also circulate in the peripheral blood of patients with recent clinical signs of plaque disruption and thrombosis. METHODS AND RESULTS: We studied 39 patients with coronary heart disease, including 12 patients with stable angina and 27 patients with acute coronary syndromes (ACS), and 12 patients with noncoronary heart disease. We isolated the circulating microparticles by capture with annexin V and determined their procoagulant potential with a prothrombinase assay. The cell origins of microparticles were determined in an additional 22 patients by antigenic capture with specific antibodies. The level of procoagulant microparticles did not differ between stable angina patients and noncoronary patients (10.1+/-1.6 nmol/L phosphatidylserine [PS] equivalent versus 9.9+/-1.6 nmol/L PS equivalent, respectively). However, procoagulant microparticles were significantly elevated in patients with ACS (22.2+/-2.7 nmol/L PS equivalent) compared with other coronary (P<0.01) or noncoronary (P<0.01) patients. Microparticles of endothelial origin were significantly elevated in patients with ACS (P<0.01), which suggests an important role for endothelial injury in inducing the procoagulant potential. CONCLUSIONS: High levels of procoagulant endothelial microparticles are present in the circulating blood of patients with ACS and may contribute to the generation and perpetuation of intracoronary thrombi.

Acute Disease↗
PubMed2000

Congestive heart failure induces endothelial cell apoptosis: protective role of carvedilol.

OBJECTIVES: The purposes of this study were to determine whether the serum of patients with congestive heart failure (CHF) can induce apoptosis of endothelial cells and to elucidate the underlying mechanisms. Moreover, the effect of the beta-blocker carvedilol was investigated. BACKGROUND: Congestive heart failure is associated with impaired endothelial function in the peripheral systemic vasculature and with systemic release of inflammatory cytokines. Pro-inflammatory cytokines have been shown to induce endothelial cell apoptosis in vitro. Therefore, we hypothesized that CHF is associated with enhanced apoptosis of endothelial cells. METHODS: Human umbilical vein endothelial cells were exposed to the serum of patients with CHF (n = 15) or healthy volunteers (n = 11), and apoptosis was determined by fluorescence staining of the nuclei and demonstration of deoxyribonucleic acid laddering. Moreover, apoptotic membrane particles were detected in plasma samples of patients with CHF. RESULTS: The serum of patients with CHF revealed a significantly enhanced pro-apoptotic activity as compared with age- and gender-matched healthy volunteers (p < 0.001). Furthermore, patients with CHF revealed significantly elevated plasma concentrations of apoptotic membrane particles. Apoptosis of endothelial cells correlated with elevated tumor necrosis factor-alpha (TNF-alpha) (r = 0.585, p = 0.002) and soluble TNF receptor serum levels (r = 0.517, p = 0.007). Carvedilol completely suppressed the increase in apoptosis induced by the serum of patients with CHF. Moreover, carvedilol dose-dependently inhibited TNF-alpha-induced apoptosis. The antiapoptotic activity of carvedilol was mediated by reduced activation of the caspase cascade through inhibition of mitochondrial cytochrome c release. The suppression of apoptosis by carvedilol was due to its antioxidative rather than beta-blocking effects, as the analogue BM91.0228, which has no beta-blocking activity, exerted similar effects. CONCLUSIONS: These findings indicate that endothelial cell apoptosis may play a role in the pathophysiology of heart failure. Inhibition of endothelial cell apoptosis by carvedilol may contribute to the beneficial effects of carvedilol in patients with heart failure.

Adrenergic beta-Antagonists↗
PubMed2000

ABC1 promotes engulfment of apoptotic cells and transbilayer redistribution of phosphatidylserine.

ATP-binding-cassette transporter 1 (ABC1) has been implicated in processes related to membrane-lipid turnover. Here, using in vivo loss-of-function and in vitro gain-of-function models, we show that ABC1 promotes Ca2+-induced exposure of phosphatidylserine at the membrane, as determined by a prothrombinase assay, membrane microvesiculation and measurement of transbilayer redistribution of spin-labelled phospholipids. That ABC1 promotes engulfment of dead cells is shown by the impaired ability of ABC1-deficient macrophages to engulf apoptotic preys and by the acquisition of phagocytic behaviour by ABC1 transfectants. Release of membrane phospholipids and cholesterol to apo-AI, the protein core of the cholesterol-shuttling high-density lipoprotein (HDL) particle, is also ABC1-dependent. We propose that both the efficiency of apoptotic-cell engulfment and the efflux of cellular lipids depend on ABC1-induced perturbation of membrane phosphatidylserine turnover. Transient local exposure of anionic phospholipids in the outer membrane leaflet may be sufficient to alter the general properties of the membrane and thus influence discrete physiological functions.

ATP Binding Cassette Transporter 1↗
PubMed2000

The influence exerted by a restricted phospholipid microenvironment on the expression of tissue factor activity at the cell plasma membrane surface.

Phosphatidylserine (PhtdSer) is an anionic aminophospholipid necessary for the development of optimal tissue factor (TF) activity at the cell surface. This study investigates the implication of a restricted lipid environment with respect to PhtdSer availability on TF expression and activity. K562 cells, showing a reduced ability to externalize PhtdSer, were transfected with human TF cDNA. PhtdSer exposure and TF activity were examined in transfected cells and compared to monocytic THP-1 cells expressing constitutive and inducible TF or megakaryocytic HEL cells showing a high PhtdSer externalization potency. TF expression was evidenced by flow cytometry and its activity measured using functional assays. PhtdSer exposure was monitored by enzymatic prothrombinase assay. One clone (DC9) expressed a stable amount of TF antigen without global modification of its membrane status. Despite a noticeable TF expression level, clone DC9 presented only a weak TF activity even after ionophore stimulation. The apparent Km, relative to factor X (FX) activation by TF-factor VIIa (FVIIa) complex, was 335 nM versus 70 nM for THP-1 cells. The velocity of the reaction was found 3-fold slower in DC9 than THP-1 cells. Ionophore treatment resulting in slightly enhanced amounts of available PhtdSer abolished this difference. The DC9 clone appears suitable for further investigations on the biology of TF expressed at the surface of cells where the contribution of PhtdSer is significantly attenuated. Such cells should enable further assessment of the role of TF as a receptor coupled to intracellular signaling pathways and its fate during apoptotic cell death.

Antigens, Surface↗
PubMed1999

Annexin V counteracts apoptosis while inducing Ca(2+) influx in human lymphocytic T cells.

We have previously shown that when annexin V is present during the execution of a cell death program, apoptosis is delayed. This is reflected by the inhibition of DNA cleavage and of the release of apoptotic membrane particles, and by reduction of the proteolytic processing of caspase-3. Here, we have studied the mechanism(s) through which annexin V counteracts apoptosis in the human CEM T cell line. The degree of apoptosis inhibition was associated with an increase of intracellular Ca(2+) concentration ([Ca(2+)](i)). Reduction of the extracellular Ca(2+) concentration by EGTA abolished the anti-apoptotic effect, suggesting that annexin V favors Ca(2+) influx and that Ca(2+) acts as an inhibitor rather than an activator of apoptosis in CEM T cells. The effects on apoptosis and [Ca(2+)](i) of several modified annexins with different electrophysiological properties indicate that the N-terminal domain of annexin V is necessary for the Ca(2+)-dependent anti-apoptotic action of annexin V. These results suggest that annexin V regulates membrane Ca(2+) permeability and is protective against apoptosis by increasing [Ca(2+)](i) in CEM T cells.

Annexin A1↗
PubMed1999

Significance of capacitative Ca2+ entry in the regulation of phosphatidylserine expression at the surface of stimulated cells.

The transverse redistribution of plasma membrane phosphatidylserine is one of the hallmarks of cells undergoing apoptosis and also occurs in cells fulfilling a more specialized function, such as platelets after appropriate activation. Although an increase in intracellular Ca2+ is required to trigger the remodeling of the plasma membrane, little information regarding intracellular signals leading to phosphatidylserine externalization has been provided. Scott syndrome is an extremely rare inherited disorder of the migration of phosphatidylserine toward the exoplasmic leaflet of the plasma membrane of stimulated blood cells. We have studied here the intracellular Ca2+ mobilization and Ca2+ entry involved in tyrosine phosphorylation in Epstein Barr virus (EBV)-infected B cells derived from a patient with Scott syndrome, her daughter, and control subjects. An alteration of Ca2+ entry through the plasma membrane and subsequent tyrosine phosphorylation induced by Ca2+ were observed in Scott EBV-B cells, but the release of Ca2+ from intracellular stores was normal. Furthermore, phosphatidylserine externalization at the surface of stimulated cells does not depend on tyrosine kinases. These results suggest that the defect of phosphatidylserine exposure in Scott syndrome cells is related to the alteration of a particular way of Ca2+ entry, referred to as capacitative Ca2+ entry, although some differences may be related to the cell type. Hence, this genetic mutant testifies to the prime significance of Ca2+ signaling in the regulation of phosphatidylserine expression at the surface of stimulated cells.

Aged↗