6-ketoprostaglandin-f1-alpha and Anemia--Sickle-Cell

Pregnancy increases the risk of morbidity and mortality in sickle cell disease. We previously showed pregnant women with sickle cell disease to have a relatively low plasma renin concentration in late pregnancy, associated with a lack of the expected plasma volume expansion. We hypothesized this to be due to increased systemic vascular resistance through an imbalance between the vasodilator prostacyclin and vasoconstrictor thromboxane, associated with decreased glomerular filtration rate (GFR).. To compare estimated prostacyclin, thromboxane and GFR in non-pregnant and pregnant women with hemoglobin SS (HbSS) and AA (HbAA).. Four groups of 20 normotensive, nulliparous women were studied in Lagos, Nigeria: pregnant HbSS or HbAA women at 36-40 weeks gestation; non-pregnant HbSS and HbAA controls. We measured stable metabolites of prostacyclin and thromboxane A2 by enzyme-linked immunosorbent assay; GFR using the Cockcroft-Gault equation. Data analysis was by independent (Student's) t-test or Mann-Whitney U test for comparisons between any two groups of continuous variables, univariate ANOVA for multiple groups and Pearson's correlation coefficient for degree of association between variables.. HbSS women had lower serum 6-keto-PGF1α concentrations than HbAA, whether pregnant or non-pregnant (P<0.001; P<0.004 respectively). Conversely, pregnant HbSS women had higher serum TxB2 (P<0.001); non-pregnant HbSS women had non-significantly higher TxB2 concentrations. The 6-keto-PGF1α:TxB2 ratio was markedly increased (pro-vasodilatory) in HbAA pregnancy (P<0.001) but reduced in HbSS pregnancy (P = 0.037). GFRs (mL/min) were higher in non-pregnant HbSS than HbAA (P<0.008) but only marginally raised in HbSS women in late pregnancy (P = 0.019) while markedly raised in HbAA pregnancy (P<0.001).. The lower ratio of prostacyclin-thromboxane metabolites in HbSS pregnancy may indicate endothelial damage and an increased tendency to vasoconstriction and clotting. If confirmed by subsequent longitudinal studies, interventions to increase prostacyclin and reduce thromboxane, such as low dose aspirin, may be potentially useful in their management.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Anemia, Sickle Cell; Blood Pressure; Creatinine; Cross-Sectional Studies; Eicosanoids; Epoprostenol; Female; Genotype; Glomerular Filtration Rate; Humans; Longitudinal Studies; Pregnancy; Pregnancy Outcome; Thromboxane A2; Thromboxane B2; Thromboxanes; Young Adult

We investigated the effects of sickle erythrocytes on the production of vasotone mediators in endothelial cells (ECs) using an in vitro recirculating flow system. Sickle erythrocytes increased the EC production of two important vasoactivators, prostacyclin and endothelin-1, under venous wall shear stress conditions of 1dyncm2. The presence of interleukin-1 in the perfusion system, as a model for inflammatory cytokine effects, enhanced the overall amounts of released prostacyclin but did not affect the production of endothelin-1. This study demonstrates the effects of sickle erythrocytes on the function and metabolism of ECs under vascular flow environments. The altered production of vasoactivators may contribute to the vasotone instability and vasoocclusive crises in sickle cell anemia.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Anemia, Sickle Cell; Cells, Cultured; Endothelin-1; Endothelium, Vascular; Epoprostenol; Erythrocytes, Abnormal; Hemolysis; Hemorheology; Humans; Interleukin-1; Kinetics

Plasma levels of 6-keto-prostaglandin F1 alpha (6kPGF1 alpha) and thromboxane (Tx) B2 have been assessed in sickle cell disease (SCD) with discrepant results. Inasmuch as direct measurement of plasma prostanoids is fraught with the problem of interfering substances, we assessed plasma 6kPGF1 alpha and TxB2 levels in patients with SCD by RIA after extraction of eicosanoids and separation by HPLC. We demonstrate that the 6kPGF1 alpha and TxB2 levels in children with SCD in steady state as well as in vaso-occlusive crisis (VOC) are significantly lower when compared with those from age-matched controls. The VOC plasma 6kPGF1 alpha and TxB2 levels were, however, significantly elevated when compared with those from children in steady state. Changes similar to those noted with unpaired plasma samples were also observed when paired steady state and VOC plasmas from the same patients were assessed. The ratio of TxB2 to 6kPGF1 alpha was, however, significantly elevated in patients with SCD in crisis when compared with eicosanoid ratios obtained during steady state. In an attempt to understand whether the abnormality in 6kPGF1 alpha was due to an impairment in endothelial cell prostacyclin-regenerating ability, we compared the ability of plasma from controls and children with SCD to activate arachidonic acid (AA) release and prostacyclin production by [14C]AA-prelabeled bovine aortic endothelial cells. Our results suggest that the decreased 6kPGF1 alpha levels in plasma from children with SCD was not due to an effect on substrate AA release but rather a modulatory effect of sickle plasma components on endothelial cell cyclooxygenase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Anemia, Sickle Cell; Animals; Arachidonic Acid; Case-Control Studies; Cattle; Cells, Cultured; Child; Child, Preschool; Chromatography, High Pressure Liquid; Constriction, Pathologic; Endothelium, Vascular; Epoprostenol; Humans; Thromboxane B2; Vascular Diseases; Vasoconstrictor Agents; Vasodilator Agents

There is evidence for increased factor VII turnover and the associated increased thrombin generation and fibrinolytic activities in sickle cell disease (SCD) that may affect in vivo platelet and endothelial cell reactivity. We studied the release of specific eicosanoids that are indicative of in vivo platelet activation and endothelial cell injury. The circulating and urinary levels of 2,3-dinor thromboxane B2(2,3-dinor-TxB2),TxB2,PGI2 [as 6-keto-PGF1 alpha], and PGE2 were measured in 15HbSS patients, eight HbAA non-haemolytic anaemic individuals and 12 healthy HbAA controls using specific RIAs. The mean urinary 2,3-dinor-TxB2 in the HbSS patients was significantly higher than in both the healthy HbAA and the anaemic controls. 6-keto-PGF1 alpha was undetected in the urines of the healthy HbAA controls, but was measured insignificant amounts in the HbSS and the HbAA anaemic patients. The urinary concentrations of PGE2 and TxB2 in HbSS patients' samples were also significantly higher than those of both control groups (P < 0.05). PGE2 and TxB2 levels were below the detection limit in the plasmas of the HbAA subjects, but were measurable in the HbSS and HbAA anaemic plasmas. The plasma level of 6-keto-PGF1 alpha in the HbSS patients was also significantly higher than in the control groups. The data indicates a persistent inflammatory process in the HbSS patients, and is consistent with the hypothesis that there is platelet and endothelial cell activation in SCD.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Anemia, Sickle Cell; Blood Platelets; Dinoprostone; Endothelium, Vascular; Humans; Middle Aged; Thromboxane B2

Thrombosis represents an important cause of mortality in patients with sickle cell disease, in addition to the complications caused by the primary defect of inherited abnormal hemoglobin. To study the involvement of platelets in these complications, we assessed the biosynthesis of thromboxane A2 in samples from 49 patients with sickle cell disease and in 33 control subjects. The urinary excretion of the major arachidonic acid metabolite of platelet origin (11-dehydro-thromboxane B2) and of the vascular endothelial cell (2,3-dinor-6-ketoprostaglandin F1 alpha) were very significantly increased (p < 0.0002) in the patients. In a small group of patients (n = 14), we further investigated the ex vivo response of their platelets to U46619, a stable analogue of thromboxane A2. We observed decreased aggregation and [14C]serotonin release compared with control (p < 0.05); similarly, we found impaired p47 protein phosphorylation (p < 0.05). In contrast, platelets from these patients responded normally to thrombin (0.1 unit/mL). In vivo desensitization of platelets from these patients to thromboxane may constitute a form of regulation that may prevent the propagation of aggregation by this potent inducer, as has been hypothesized in in vitro studies. Our results may also provide a rationale for using antiplatelet drugs in the prophylaxis of thrombotic complications in sickle cell patients.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Anemia, Sickle Cell; Aspirin; Blood Platelets; Female; Humans; Male; Phosphorylation; Prostaglandin Endoperoxides, Synthetic; Thrombin; Thromboxane A2; Thromboxane B2

We compared the effects of normal (AA) and sickle (SS) erythrocytes (RBC) on endothelial cell release of prostacyclin by perfused human umbilical cord veins. Two equal-length segments of fresh umbilical cords were perfused first with serum-free Dulbecco's modified Eagle's medium (DMEM) to establish the basal prostacyclin production rate for each segment; then one segment was perfused with SS RBC and/or plasma, while the other segment was simultaneously perfused with AA RBC and/or plasma. Aliquots of perfusate were removed at intervals for measurement of the stable prostacyclin metabolite 6-keto-prostaglandin F1 alpha (6-keto-PGF). Basal prostacyclin production by segments from the same cord was very similar, but it varied considerably among segments from different cords. Therefore, the ratio of prostacyclin release with RBC and/or plasma to basal prostacyclin release for each segment was used to compare prostacyclin release among segments from different cords. Mean prostacyclin release was significantly higher from segments perfused with SS RBC in autologous plasma than from segments perfused with AA RBC in autologous plasma at 15, 30, and 60 min. However, no significant differences in mean prostacyclin production were observed between segments perfused with SS vs. AA RBC in DMEM or between segments perfused with SS vs. AA plasma alone. No significant correlations were observed between prostacyclin production and either the viscosity of SS and AA RBC in autologous plasma or DMEM or the adhesiveness of SS and AA RBC to cultured human umbilical vein endothelial cells. We conclude that SS RBC in autologous plasma cause increased prostacyclin release from perfused human umbilical cord veins. The perfused human umbilical cord vein system may be a useful model for comparing the response of vascular endothelium to SS and AA RBC and plasma under controlled-flow conditions.

Topics: 6-Ketoprostaglandin F1 alpha; Anemia, Sickle Cell; Cells, Cultured; Endothelium, Vascular; Epoprostenol; Erythrocytes; Erythrocytes, Abnormal; Humans; Models, Biological; Perfusion; Plasma; Rheology; Umbilical Veins; Vasodilation

Topics: 6-Ketoprostaglandin F1 alpha; Anemia, Sickle Cell; Epoprostenol; Humans; Vascular Diseases

The addition of prostaglandin I2 (PGI2) enhanced the adhesion of red cells from normals and patients with diabetes mellitus or sickle cell anemia (SCA) to human cultured endothelial cells (p less than 0.025). The maximal effect was reached with 10(-11) M PGI2 after 30 min incubation. Red cell adhesion was also increased by PGD2 but PGE1 and 6-keto-PGF1 alpha had no significant effect. Since enhanced adhesion of red cell to endothelium and increased red cell calcium content have been proposed to be related in SCA, we have investigated the calcium binding to human resealed normal erythrocyte membrane by using (45Ca) calcium in presence of the different PG which alter red cell adhesion or not. Calcium binding was time-dependent and potentiated in presence of PGI2 (p less than 0.01) but not of PGD2. The fact that erythrocyte adhesion is enhanced by both PGI2 and PGD2 while calcium binding is increased only by PGI2 suggests that the two phenomenon can be dissociated.

Topics: 6-Ketoprostaglandin F1 alpha; Anemia, Sickle Cell; Calcium; Cell Adhesion; Diabetes Mellitus; Endothelium, Vascular; Epoprostenol; Erythrocyte Membrane; Humans; In Vitro Techniques

Endothelial cell damage is considered to be the initial step in the genesis of thrombosis and atherosclerosis. Recently, the adhesion of erythrocytes from patients with diabetes or sickle cell anemia to endothelial cells was found to be increased and correlated with the severity of vascular complications. We have measured by radioimmunoassay the release of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) as an index of prostacyclin (PGI2) production, during red cell adhesion to endothelial cells in culture. The amount of 6-keto-PGF1 alpha released after incubation with normal red cells was similar to that observed with buffer (1.07 +/- 0.32 nmol/10(6) endothelial cells). However, after the adhesion of erythrocytes from patients with diabetes or sickle cell anemia, the amount of 6-keto-PGF1 alpha produced was significantly increased (P less than 0.01) and was correlated with the extent of erythrocyte adhesion (P less than 0.05). Tritium-labeled PGI2 was found to bind to erythrocytes, and the binding was time and concentration dependent. PGI2 release was inhibited by the cyclooxygenase inhibitor (flurbiprofen), whereas red cell adhesion remained unchanged. Fibrinogen potentiated erythrocyte adhesion and PGI2 production. The increase in PGI2 production after the adhesion of red cells from patients with diabetes or sickle cell anemia to endothelial cells indicates that endothelium may be damaged by abnormal erythrocyte adhesion.

Topics: 6-Ketoprostaglandin F1 alpha; Adenosine Diphosphate; Adenosine Triphosphate; Adult; Anemia, Sickle Cell; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Blood Proteins; Blood Vessels; Cell Adhesion; Cells, Cultured; Cyclooxygenase Inhibitors; Diabetes Mellitus; Endothelium; Epoprostenol; Erythrocytes; Fibrinogen; Flurbiprofen; Humans; Leukocytes; Middle Aged; Plasma; Prostaglandins F; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Anemia, Sickle Cell; Epoprostenol; Humans; Prostaglandins

Patients with sickle cell disease have been described to have decreased platelet aggregation. The cause of this decrease is believed to be the refractory state of platelets from continual in vivo activation. In this study, plasma 6-keto PGF1 alpha (stable metabolite of vessel wall-derived prostaglandin, prostacyclin) levels were measured to study the mechanism of decreased platelet aggregation. Plasma 6-keto PGF1 alpha levels were measured by radioimmunoassay in ten patients with sickle cell disease and in ten control subjects. Plasma 6-keto PGF1 alpha levels in normal subjects ranged from 0 to 100 pg/ml (mean 40 +/- 14 pg/ml), but were significantly higher in patients with sickle cell disease (range 170 to 880 ng/ml, mean 446 +/- 89 pg/ml, P less than .002). Platelet aggregation in response to an endoperoxide analog in these patients was lower compared with that of the control subjects. This study suggests that prostacyclin activity is increased in subjects with sickle cell disease. This increased activity is probably due to persistent stress to the endothelium from hemolysis and continual platelet activation. Decreased platelet aggregation seen in these patients may be due to elevated prostacyclin activity.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Anemia, Sickle Cell; Child; Child, Preschool; Female; Humans; Infant; Male; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic