Inflammation at a glance: erythrocyte adhesiveness/aggregation test to reveal the presence of inflammation in people with atherothrombosis

The erythrocyte adhesiveness/aggregation test is a new biomarker to detect low-grade inflammation in patients with atherothrombosis. In a group of 30 individuals with an acute ischemic event, the variability of EAAT during a follow-up period was similar to those obtained for other commonly used markers of the acute phase response, suggesting the potential clinical use of this novel marker.     

Erythrocyte deformability and erythrocyte aggregation in preeclampsia

One of the features of preeclampsia is impaired blood rheology due to altered erythrocyte aggregation and erythrocyte deformability. We investigated these two parameters which affect the viscosity of blood, along with serum and intraerythrocytic magnesium concentrations, immunoglobulin titres and fibrinogen concentration in 12 preeclamptic women. Eighteen (18) other non-preeclamptic, gestation-matched women acted as controls. Erythrocyte deformability, expressed as elongation index (EI), and erythrocyte aggregation expressed as aggregation half-time (t 1/2) were measured with the Laser-assisted Optical Rotational Cell Analyser (LORCA). Serum and intraerythrocytic magnesium concentrations were analysed by atomic absorption spectrometry, immunoglobulin titres by radial immunodiffusion and fibrinogen concentration by a clot weight technique. There was no statistically significant difference in these parameters between preeclamptics and controls suggesting that erythrocyte deformability and aggregation as well as serum and intraerythrocytic concentrations, fibrinogen levels and immunoglobulin titres are not altered in preeclampsia. Further investigations are required in severe preeclampsia and in preeclamptic women taking magnesium sulphate supplement.     

Mechanism of erythrocyte aggregation and sedimentation

Unstirred suspensions of erythrocytes form stable spherical aggregates of uniform size. The radius of the spheres depends upon the suspending medium and the hematocrit. Erythrocyte suspensions will undergo sedimentation only after these aggregates are formed. Aggregation is a two-step process: first, erythrocytes associate in long chains (rouleau formation). Next, these chains form spheres of uniform size. The requirements for this well-defined process are an electrolyte and a neutral or negatively charged macromolecule in the solution and a metabolically active red cell. If these conditions are not met, red cells either will not aggregate at all or will form amorphous aggregates. Rouleau formation and sedimentation are inhibited by 4,4'- diisothiocyanatostilbene-2,2'-disulfonic acid, an inhibitor of anion transport, but not by ouabain, a cation transport inhibitor. The kinetics of erythrocyte sedimentation reflects the aforementioned mechanism: no sedimentation occurs during rouleau formation. Once the spheres of uniform size are formed, they will settle according to the Einstein-Stokes equation. In this model, parameters of sedimentation kinetics are the delay before sedimentation starts, the rate of sedimentation in the steady state, and the radius of the sedimenting aggregate. The radius can be calculated from the rate of fall of the aggregates and agrees well with the microscopically observed radius. It is inversely proportional to the hematocrit, which explains the elevated sedimentation rates in anemia.     

Kinetic model for erythrocyte aggregation

It is well known that light transmission through blood is the most widely utilized method for the study of erythrocyte aggregation. The curves obtained had been considered empirically as exponential functions. In consequence, the process becomes characterized by an only parameter that varies with all the process factors without discrimination. In the present paper a mathematical model for RBC aggregation process is deduced in accordance with von Smoluchowski's theory about the kinetics of colloidal particles agglomeration. The equation fitted the experimental pattern of the RBC suspension optical transmittance closely and contained two parameters that estimate the most important characteristics of the aggregation process separately, i.e., (1) average size of rouleaux at equilibrium and (2) aggregation rate. The evaluation of the method was assessed by some factors affecting erythrocyte aggregation, such as temperature, plasma dilutions, Dextran 500, Dextran 70 and PVP 360, at different media concentrations, cellular membrane alteration by the alkylating agent TCEA, and decrease of medium osmolarity. Results were interpreted considering the process characteristics estimated by the parameters, and there were also compared with similar studies carried out by other authors with other methods. This analysis allowed us to conclude that the equation proposed is reliable and useful to study erythrocyte aggregation.     

Inflammation-sensitive plasma proteins are associated with increased incidence of heart failure: a population-based cohort study

BackgroundAlthough inflammation has been associated with different cardiovascular diseases, the relationships with future heart failure (HF) are unclear. This population-based study explored whether elevated plasma levels of inflammatory proteins are associated with incidence of HF.MethodsFive inflammation-sensitive plasma proteins (ISPs, fibrinogen, ceruloplasmin, haptoglobin, orosomucoid, and α1-antitrypsin) was measured in 6071 men (mean age 46 years) without history of myocardial infarction (MI) or stroke. Incidence of hospitalizations due to HF (primary diagnosis) was monitored over 22 years of follow-up, in relation to the number of elevated ISPs (i.e., in the 4th quartile). Subjects with myocardial infarction during follow-up were censored.ResultsDuring the follow-up, 159 men were hospitalized due to HF. Baseline levels of all ISPs, except for haptoglobin, were significantly higher in men who developed HF. After adjustments for confounding factors, the hazard ratios (HR) of HF were 1.00 (reference), 1.7 (95% CI: 1.1–2.7), 2.0 (CI: 1.2–3.3) and 2.6 (CI: 1.6–4.1), respectively, in men with none, one, two and three or more ISPs in the 4th quartile (trend: p < 0.001). Of the individual ISPs, fibrinogen, ceruloplasmin and α1-antitrypsin showed significant relationships with incidence of HF after adjustment for risk factors.ConclusionPlasma levels of inflammatory markers are associated with long-term incidence of hospitalizations due to HF in middle-aged men.     

Statins in atherothrombosis

Clinical studies have shown that hydroxy-methyl glutaryl coenzyme A reductase inhibitors (statins) may favorably affect atherothrombosis. In addition to their potent cholesterol-lowering properties, statins reduce atheroma progression as well as the incidence of acute thrombosis-related vascular events and their dreadful clinical consequences. Available data indicate that statins exert significant antithrombotic effects in clinical practice by reducing the occurrence of vascular atherothrombotic events, with a more prominent effect in high-risk patients. The mechanisms by which statins inhibit thrombosis have been extensively investigated, and several pathways appear to be involved. In particular, statins have been proposed to reduce platelet activation and to exert favorable effects on fibrinolysis, but no clear-cut conclusion can be drawn from available studies. Moreover, statins do not consistently influence fibrinogen or factor VII levels in plasma. In contrast, in vitro and in vivo data indicate that these compounds profoundly affect thrombin generation driven by tissue factor/factor VII pathway. In vitro studies indicate that this effect is not dependent on plasma cholesterol lowering but, rather, on the inhibition of isoprenoid biosynthesis. The relative contribution of reduced levels of prenylated proteins and of cholesterol pathway to the modulation of tissue factor expression is, however, hardly to be established in clinical settings.     

Effects of ticlopidine on erythrocyte aggregation in thrombotic disorders

The authors investigated the involvement of red blood cell aggregation in thrombosis by comparing erythrocyte aggregation in patients with myocardial infarction (28 patients) or cerebrovascular accidents (68 patients) with that in a normal control group (38 subjects). The erythrocyte aggregation was assessed by light transmission aggregometer, and aggregation was induced by hexadimethrine-bromide. Increased erythrocyte aggregation was detected in all patients with thrombotic disorders. In addition, patients with diabetes mellitus showed a marked increase in erythrocyte aggregation as compared with those without diabetes. The effect of ticlopidine on erythrocyte aggregation was also studied. It was demonstrated that ticlopidine inhibited aggregation in vitro. An inhibitory effect was shown to be dose dependent, with 10 microM ticlopidine inhibiting aggregation completely. After four weeks' oral administration of 200 mg ticlopidine, there was significant decrease of abnormally increased erythrocyte aggregation in patients with thrombosis.     

Combined leukocyte and erythrocyte aggregation in patients with acute myocardial infarction

OBJECTIVES: To determine whether the increased aggregability of both white and red blood cells previously reported in acute myocardial infarction (aMI) correlates with each other. DESIGN: Cross-sectional study comparing two groups of patients and a group of healthy controls. SETTING: A tertiary university affiliated hospital (Intensive Cardiac Care Unit and Department of General Internal Medicine). PATIENTS: Consecutive patients with aMI, patients with chest pain and no infarction, and healthy controls. MEASUREMENTS AND RESULTS: We adapted a simple slide test and image analysis to reveal the state of both leukocyte and erythrocyte adhesiveness/aggregation in the peripheral blood of patients with aMI. A significant (P=0.0001) increment in the aggregation of both cellular populations was noted in 48 patients with aMI as opposed to the 141 patients with ischemic heart disease and no infarction and in 45 matched controls. In addition, a significant correlation was noted between the various variables of the leukocyte and erythrocyte adhesiveness/aggregation tests. CONCLUSIONS: The significant correlation between the aggregability of white and red blood cells in patients with aMI is suggestive of there being a commonly shared adhesive protein(s). The prompt identification of patients with increased aggregation might have clinical and therapeutic implications.     

Folding and aggregation of designed proteins

Protein aggregation is studied by following the simultaneous folding of two designed identical 20-letter amino acid chains within the framework of a lattice model and using Monte Carlo simulations. It is found that protein aggregation is determined by elementary structures (partially folded intermediates) controlled by local contacts among some of the most strongly interacting amino acids and formed at an early stage in the folding process.     

Coagulation pathways in atherothrombosis

Atherosclerosis is a disease recognized as the main cause of death in industrial countries. The current paradigm establishes thrombosis to be the major reason for complications of atherosclerosis, such as myocardial infarction and stroke, and the major factor responsible for atherosclerosis-related mortality. Development of adequate treatment of patients with risk of atherothrombosis requires the comprehensive understanding of mechanisms underlying coagulation processes at the site of atherosclerotic lesion. The present review discusses contribution of the extrinsic and intrinsic pathways of blood coagulation in thrombogenicity of atherosclerotic plaque and factors determining the overall procoagulant/anticoagulant balance.     

Increase of erythrocyte aggregation in hypertensive men with dyslipidemia]

We have already reported that erythrocyte aggregation (EA) is increased in hypertensive subjects. To study the influence of other risk factors in EA, we have measured aggregation index IA and disaggregation shear rate threshold (gamma c) by a laser technique and the biochemical parameters in 16 normotensive normocholesterolemic subjects (NT/NCT) and 45 hypertensive subjects where 17 were normocholesterolemic (HT/NCT), 18 were pure hypercholesterolemic (HT/HCTIIa) and 10 were hypercholesterolemic hypertriglyceridemic (HT/HCTIIb). The results show that IA and gamma c are more important in HT/NCT than NT/NCT patients and much more in patients with hypercholesterolemia and hypertriglyceridemia. The cumulative effects of hypertension and hyperlipidemia merit take into consideration in pathophysiology of cardiovascular complications and could help to new strategy therapeutic developments for treatment of these complications.