Extracellular matrix remodelling in the endometrium and its possible relevance to the pathogenesis of endometriosis.
(1/2260)
Essential features of endometrial physiology involve the extracellular matrix (ECM). In the pathogenesis of endometriosis, interactions of endometriosis cells with ECM can be postulated. Two systems of secreted proteases in the endometrium, the plasmin(ogen) activator/inhibitor and the matrix metalloproteinases and their inhibitors were examined in cell cultures of uterine endometrial cells from women with and without endometriosis. Soluble urokinase receptor secretion is increased, and mRNA transcription of tissue inhibitor of metalloproteinases-2 (TIMP-2) is upregulated by progestin in endometriosis. These findings are compatible with an altered ECM turnover in the endometrium of these patients that may explain a higher invasive potential of retrogradely menstruated endometrial fragments. (+info)
Roles of Pseudomonas aeruginosa las and rhl quorum-sensing systems in control of twitching motility.
(2/2260)
Pseudomonas aeruginosa is a ubiquitous environmental bacterium and an important human pathogen. The production of several virulence factors by P. aeruginosa is controlled through two quorum-sensing systems, las and rhl. We have obtained evidence that both the las and rhl quorum-sensing systems are also required for type 4 pilus-dependent twitching motility and infection by the pilus-specific phage D3112cts. Mutants which lack the ability to synthesize PAI-1, PAI-2, or both autoinducers were significantly or greatly impaired in twitching motility and in susceptibility to D3112cts. Twitching motility and phage susceptibility in the autoinducer-deficient mutants were partially restored by exposure to exogenous PAI-1 and PAI-2. Both twitching motility and infection by pilus-specific phage are believed to be dependent on the extension and retraction of polar type 4 pili. Western blot analysis of whole-cell lysates and enzyme-linked immunosorbent assays of intact cells were used to measure the amounts of pilin on the cell surfaces of las and rhl mutants relative to that of the wild type. It appears that PAI-2 plays a crucial role in twitching motility and phage infection by affecting the export and assembly of surface type 4 pili. The ability of P. aeruginosa cells to adhere to human bronchial epithelial cells was also found to be dependent on the rhl quorum-sensing system. Microscopic analysis of twitching motility indicated that mutants which were unable to synthesize PAI-1 were defective in the maintenance of cellular monolayers and migrating packs of cells. Thus, PAI-1 appears to have an essential role in maintaining cell-cell spacing and associations required for effective twitching motility. (+info)
Nicotine increases plasminogen activator inhibitor-1 production by human brain endothelial cells via protein kinase C-associated pathway.
(3/2260)
BACKGROUND AND PURPOSE: Smoking both increases stroke risk and reduces the risk of thrombolysis-associated intracerebral hemorrhage. Plasminogen activator inhibitor-1 (PAI-1) is a major regulator of fibrinolysis; elevation of PAI-1 is associated with an increased risk of thrombotic disorders. We studied the effect of nicotine, an important constituent of cigarette smoke, on PAI-1 production by human brain endothelial cells. METHODS: Adult human central nervous system endothelial cells (CNS-EC) were used for tissue culture experiments. We analyzed culture supernatant for PAI-1 protein and measured PAI-1 mRNA (by Northern blot analysis) and protein kinase C (PK-C) activity. RESULTS: Nicotine at 100 nmol/L increased PAI-1 protein production and mRNA expression by CNS-EC. After 72 hours of exposure to nicotine, the concentration of secreted PAI-1 in the cell supernatant was increased 1.90+/-0.2 fold compared with untreated cells. PAI-1 mRNA also increased approximately twofold. Inhibition of PK-C completely abolished this effect. Nicotine had no effect on the concentration of tissue plasminogen activator. CONCLUSIONS: Nicotine increases brain endothelial cell PAI-1 mRNA expression and protein production via PK-C-dependent pathway. These findings provide new insights into why smoking may be associated with predisposition to thrombosis and inversely associated with intracerebral hemorrhage after therapeutic tissue plasminogen activator therapy. (+info)
Vitronectin inhibits the thrombotic response to arterial injury in mice.
(4/2260)
Vitronectin (VN) binds to plasminogen activator inhibitor-1 (PAI-1) and integrins and may play an important role in the vascular response to injury by regulating fibrinolysis and cell migration. However, the role of VN in the earliest response to vascular injury, thrombosis, is not well characterized. The purpose of this study was to test the hypothesis that variation in vitronectin expression alters the thrombotic response to arterial injury in mice. Ferric chloride (FeCl3) injury was used to induce platelet-rich thrombi in mouse carotid arteries. Wild-type (VN +/+, n = 14) and VN-deficient (VN -/-, n = 15) mice, matched for age and gender, were studied. Time to occlusion after FeCl3 injury was determined by application of a Doppler flowprobe to the carotid artery. Occlusion times of VN -/- mice were significantly shorter than those of VN +/+ mice (6.0 +/- 1.2 minutes v 17.8 +/- 2.3 minutes, respectively, P < .001). Histologic analysis of injured arterial segments showed that thrombi from VN +/+ and VN -/- mice consisted of dense platelet aggregates. In vitro studies of murine VN +/+ and VN -/- platelets showed no significant differences in ADP-induced aggregation, but a trend towards increased thrombin-induced aggregation in VN -/- platelets. Purified, denatured VN inhibited thrombin-induced platelet aggregation, whereas native VN did not. Thrombin times of plasma from VN -/- mice (20.5 +/- 2.1 seconds, n = 4) were significantly shorter than those of VN +/+ mice (34.2 +/- 6.7 seconds, n = 4, P < .01), and the addition of purified VN to VN -/- plasma prolonged the thrombin time into the normal range, suggesting that VN inhibits thrombin-fibrinogen interactions. PAI-1-deficient mice (n = 6) did not demonstrate significantly enhanced arterial thrombosis compared with wild-type mice (n = 6), excluding a potential indirect antithrombin function of VN mediated by interactions with PAI-1 as an explanation for the accelerated thrombosis observed in VN -/- mice. These results suggest that vitronectin plays a previously unappreciated antithrombotic role at sites of arterial injury and that this activity may be mediated, at least in part, by inhibiting platelet-platelet interactions and/or thrombin procoagulant activity. (+info)
Luteinization and proteolysis in ovarian follicles of Meishan and Large White gilts during the preovulatory period.
(5/2260)
This experiment was conducted to determine why follicles luteinize faster in the Meishan breed than in the Large White breed of pig. Follicles were recovered during the late follicular phase from ovaries of both breeds before and after administration of hCG given to mimic the LH surge. First, the patterns of cholesterol transporters (high and low density lipoproteins: HDL and LDL) were compared. Cholesterol transporters detected in follicular fluid consisted of HDL only. Similar amounts of Apolipoprotein A-I were found in all samples. There was no obvious breed effect on minor lipoproteins found in the HDL-rich fraction, and this pattern was altered similarly by hCG in the two breeds. The LDL-rich samples of serum from both breeds contained similar amounts of protein. Second, three steroidogenic enzymes, adrenodoxin, 17 alpha-hydroxylase-lyase (P450(17) alpha) and 3 beta-hydroxysteroid-dehydrogenase (3 beta-HSD) were detected by immunohistochemistry and quantified by image analysis on sections of the two largest follicles. Before hCG treatment, theca interna cells demonstrated immunoreactivities for adrenodoxin (strong), P450(17) alpha and 3 beta-HSD (very strong), whereas granulosa cells displayed immunoreactivities for adrenodoxin only. After hCG treatment, the localization of the enzymes was unchanged but the staining intensity of adrenodoxin on granulosa cells and 3 beta-HSD on theca cells increased (P < 0.01 and P < 0.05, respectively). Breed effects were detected for the amounts of adrenodoxin in theca cells (Meishan > Large White; P < 0.05) and of 17 alpha-hydroxylase (Large White > Meishan, P < 0.01). Breed x treatment interactions were never detected. Finally, gelatinases, plasminogen activator, plasminogen activator inhibitor, tissue inhibitors of metalloproteases (TIMP-1 and TIMP-2) were visualized by direct or reverse zymography or western blotting. Whatever the stage relative to LH administration, follicular fluid from Large White gilts contained more TIMP-1, and TIMP-2 (P < 0.02 and P < 0.01, respectively). No breed effect was detected for the amounts of gelatinases and plasminogen activator inhibitor 1. However, for these parameters, a significant breed x time interaction was obvious, as the Meishan follicles had a greater response to hCG (P < 0.01). Since proteolysis plays a key role in the bioavailability of growth factors such as insulin-like growth factor 1, fibroblast growth factor and transforming growth factor beta, which have the ability to alter gonadotrophin-induced progesterone production in pigs, the differences observed in its control in the present study may explain, at least in part, the different patterns of luteinization observed in Meishan and Large White follicles. (+info)
Fibrinolytic activation markers predict myocardial infarction in the elderly. The Cardiovascular Health Study.
(6/2260)
Coagulation factor levels predict arterial thrombosis in epidemiological studies, but studies of older persons are needed. We studied 3 plasma antigenic markers of fibrinolysis, viz, plasminogen activator inhibitor-1 (PAI-1), fibrin fragment D-dimer, and plasmin-antiplasmin complex (PAP) for the prediction of arterial thrombosis in healthy elderly persons over age 65. The study was a nested case-control study in the Cardiovascular Health Study cohort of 5201 men and women >/=65 years of age who were enrolled from 1989 to 1990. Cases were 146 participants without baseline clinical vascular disease who developed myocardial infarction, angina, or coronary death during a follow-up of 2.4 years. Controls remained free of cardiovascular events and were matched 1:1 to cases with respect to sex, duration of follow-up, and baseline subclinical vascular disease status. With increasing quartile of D-dimer and PAP levels but not of PAI-1, there was an independent increased risk of myocardial infarction or coronary death, but not of angina. The relative risk for D-dimer above versus below the median value (>/=120 microg/L) was 2.5 (95% confidence interval, 1.1 to 5.9) and for PAP above the median (>/=5.25 nmol/L), 3.1 (1.3 to 7.7). Risks were independent of C-reactive protein and fibrinogen concentrations. There were no differences in risk by sex or presence of baseline subclinical disease. D-dimer and PAP, but not PAI-1, predicted future myocardial infarction in men and women over age 65. Relationships were independent of other risk factors, including inflammation markers. Results indicate a major role for these markers in identifying a high risk of arterial disease in this age group. (+info)
Relationship of plasmin generation to cardiovascular disease risk factors in elderly men and women.
(7/2260)
Plasmin-alpha2-antiplasmin complex (PAP) marks plasmin generation and fibrinolytic balance. We recently observed that elevated levels of PAP predict acute myocardial infarction in the elderly, yet little is known about the correlates of PAP. We measured PAP in 800 elderly subjects who were free of clinical cardiovascular disease in 2 cohort studies: the Cardiovascular Health Study and the Honolulu Heart Program. Median PAP levels did not differ between the Cardiovascular Health Study (6.05+/-1.46 nmol/L) and the Honolulu Heart Program (6.11+/-1.44 nmol/L), and correlates of PAP were similar in both cohorts. In CHS, PAP levels increased with age (r=0. 30), procoagulant factors (eg, factor VIIc, r=0.15), thrombin activity (prothrombin fragment F1+2, r=0.29), and inflammation-sensitive proteins (eg, fibrinogen, r=0.44; factor VIIIc, r=0.37). PAP was associated with increased atherosclerosis as measured by the ankle-arm index (AAI) (P for trend, +info)
PPARgamma activation in human endothelial cells increases plasminogen activator inhibitor type-1 expression: PPARgamma as a potential mediator in vascular disease.
(8/2260)
Plasminogen activator inhibitor type-1 (PAI-1) is a major physiological inhibitor of fibrinolysis, with its plasma levels correlating with the risk for myocardial infarction and venous thrombosis. The regulation of PAI-1 transcription by endothelial cells (ECs), a major source of PAI-1, remains incompletely understood. Adipocytes also produce PAI-1, suggesting possible common regulatory pathways between adipocytes and ECs. Peroxisomal proliferator-activated receptor-gamma (PPAR)gamma is a ligand-activated transcription factor that regulates gene expression in response to various mediators such as 15-deoxy-Delta12, 14-prostaglandin J2 (15d-PGJ2) and oxidized linoleic acid (9- and 13-HODE). The present study tested the hypotheses that human ECs express PPARgamma and that this transcriptional activator regulates PAI-1 expression in this cell type. We found that human ECs contain both PPARgamma mRNA and protein. Immunohistochemistry of human carotid arteries also revealed the presence of PPARgamma in ECs. Bovine ECs transfected with a PPAR response element (PPRE)-luciferase construct responded to stimulation by the PPARgamma agonist 15d-PGJ2 in a concentration-dependent manner, suggesting a functional PPARgamma in ECs. Treatment of human ECs with 15d-PGJ2, 9(S)-HODE, or 13(S)-HODE augmented PAI-1 mRNA and protein expression, whereas multiple PPARalpha activators did not change PAI-1 levels. Introduction of increasing amounts of a PPARgamma expression construct in human fibroblasts enhanced PAI-1 secretion from these cells in proportion to the amount of transfected DNA. Thus, ECs express functionally active PPARgamma that regulates PAI-1 expression in ECs. Our results establish a role for PPARgamma in the regulation of EC gene expression, with important implications for the clinical links between obesity and atherosclerosis. (+info)