Lipid peroxidation affects red blood cells membrane properties in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune, chronic inflammatory, non-organ specific disease with an important morbimortality affecting several organs and systems. Oxidative stress is a well documented mechanism of red blood cells (RBC) mechanical impairment. Free radicals could produced, through lipid peroxidation, physical and chemical alterations in the cellular membrane properties modifying its composition, packing and lipid distribution on the membrane erythrocyte. The aim of the present work is to study the lipid peroxidation in the RBC membrane in SLE patients (n = 42) affecting so far the lipid membrane fluidity and erythrocyte deformability in comparison with healthy controls (n = 52). Malonildialdehyde (MDA) is a subrogate assessing lipidic peroxidation, rigidity index estimating erythrocyte deformability and the anisotropy coefficient estimating lipid membrane fluidity were used. Our results show that MDA values are increased, while erythrocyte deformability and membrane fluidity are significantly decreased in erythrocyte membrane from SLE patients in comparison with normal controls. The association of thiobarbituric acid reactive substances (TBARS) with membrane lipid fluidity and erythrocyte deformability confirms that the damage of membrane properties is produced by lipid peroxidation.

Erythrocyte aggregation in patients with systemic lupus erythematosus.

Systemic Lupus Erythematosus (SLE) is an autoimmune, chronic inflammatory, non-organ specific disease. SLE patients present a high prevalence of thrombotic and arteriosclerotic disease. The aim of the present work was to study the erythrocyte aggregation kinetics, and the effect of plasma factors, namely, immunoglobulin and fibrinogen concentration, as well as cell factors such as deformability and erythrocyte membrane lipid fluidity on the erythrocyte aggregation, in SLE patients and healthy controls. The results show that SLE patients red blood cells aggregate at higher rate and the aggregates size are also greater than controls due to an increase of immunoglobulin and plasma fibrinogen. The negative correlation between aggregation parameters and rigidity index could point out that the altered deformability diminishes the erythrocyte aggregation. Correlation between rigidity index and anisotropy suggests that the decrease of membrane lipid fluidity might be a cause of deformability decrease. The erythrocyte aggregation increase in these patients could induce a decreased flow that might contribute to the thromboembolic process present in SLE patients.

In vitro and ex vivo effect of hyaluronic acid on erythrocyte flow properties.

BACKGROUND: Hyaluronic acid (HA) is present in many tissues; its presence in serum may be related to certain inflammatory conditions, tissue damage, sepsis, liver malfunction and some malignancies. In the present work, our goal was to investigate the significance of hyaluronic acid effect on erythrocyte flow properties. Therefore we performed in vitro experiments incubating red blood cells (RBCs) with several HA concentrations. Afterwards, in order to corroborate the pathophysiological significance of the results obtained, we replicated the in vitro experiment with ex vivo RBCs from diagnosed rheumatoid arthritis (RA) patients, a serum HA-increasing pathology. METHODS: Erythrocyte deformability (by filtration through nucleopore membranes) and erythrocyte aggregability (EA) were tested on blood from healthy donors additioned with purified HA. EA was measured by transmitted light and analyzed with a mathematical model yielding two parameters, the aggregation rate and the size of the aggregates. Conformational changes of cytoskeleton proteins were estimated by electron paramagnetic resonance spectroscopy (EPR). RESULTS: In vitro, erythrocytes treated with HA showed increased rigidity index (RI) and reduced aggregability, situation strongly related to the rigidization of the membrane cytoskeleton triggered by HA, as shown by EPR results. Also, a significant correlation (r: 0.77, p < 0.00001) was found between RI and serum HA in RA patients. CONCLUSIONS: Our results lead us to postulate the hypothesis that HA interacts with the erythrocyte surface leading to modifications in erythrocyte rheological and flow properties, both ex vivo and in vitro.

Erythrocyte aggregation in rheumatoid arthritis: Cell and plasma factor's role.

UNLABELLED: Increase in erythrocyte aggregation (EA) is pathognomonic for rheumatoid arthritis (RA), and its estimation through erythrocyte sedimentation rate (ESR) is part of DAS 28-4 activity diagnosis, with low correlation with EA and that does not discriminate the contribution of cell factors that increase aggregation. OBJECTIVE: To analyse cell and plasma factors that might be involved in EA increase, to understand how RA affects blood components, thus modifying blood fluid behavior. METHODOLOGY: One hundred women presenting active RA were compared with age-matched controls (C). EA was measured by transmitted light, obtaining two parameters: 2k2n0, characterizing the aggregation process kinetics and s0/n0, estimating aggregates size. Cell factors assays: erythrocyte deformability, by filtration through nucleopore membranes, cell shape, by microscopy, and membrane fluidity by EPR. Plasma: total proteins and CRP, albumin, fibrinogen (Fb), by gravimetry, and IgG and IgM by single radial immuno-diffusion. RESULTS: AR and C (x+/-SE). 2k2n0: 31.83+/-2.84, 23.75+/-1.91; s0/n0: 0.92+/-0.05, 0.87+/-0.04. Rigidity index (RI): 14.79+/-4.71, 6.92+/-1.31. Morphological index: 0.28+/-0.03, 0.30+/-0.05, n.s. Fb (mg/dl): 382+/-80, 299+/-70. IgG (mg/dl): 1580+/-219, 1296+/-158; IgM (mg/dl) 233+/-28, 183+/-23; albumin (g/dl) 3.84+/-0.44, 3.77+/-0.51 n.s. p<0.05 accepted. Correlations: 2k2n0 vs. Fb r=0.66; s0/n0 vs. Fb r=0.51; 2k2n0 vs. Igs r=0.65; s0/n0 vs. Igs r=0.56. 2k2n0 vs. RI r=-0.59; s0/n0 vs. RI=-0.52, p<0.05. CONCLUSIONS: Plasma factors, Igs and Fb increased aggregation, since RI is altered, this reduces the process efficiency regarding aggregation. Patients with active RA present an increased EA, with values modifications associated with the activity index DAS 28-4, thus becoming an RA activity indicator.

Nifedipine effect on red cell rheological properties in patients with systemic scleroderma.

Systemic scleroderma is an autoimmune disease, due to a connective tissue alteration characterized by extracellular matrix increase in the skin and internal organs. It is already known that the Raynaud's phenomenon and the microcapillary obliteration lead to ischemia and peripheral tissue injury. The ischemia-reperfusion phenomenon releases free radicals, that react with red blood cells (RBCs) membrane components originating lipid peroxidation and impairment of the ATP-Ca(++) pump, two possible mechanisms responsible of disease pathogenesis. Nifedipine is a Ca(++)-channel antagonist that has been used for a long time in Raynaud's phenomenon treatment. In the present study we were able to demonstrate that erythrocyte deformability and two other related variables such as membrane fluidity and osmotic fragility improve significantly with nifedipine therapy. It is likely that nifedipine inhibiting cytoplasmic calcium accumulation could restore some red blood cell membrane properties.

Haemorheological variables as a rheumatoid arthritis activity indicator.

OBJECTIVE: To investigate if blood hyperviscosity in RA patients is due to a reduced erythrocyte deformability and, therefore, turning it into a reliable activity indicator, as well as a therapy follow-up marker for this pathology. METHODS: (1) The haemorheological profile consisting of erythrocyte deformability, blood and plasma viscosity, and erythrocyte membrane fluidity was determined in 24 AR patients and 17 healthy controls. (2) A 4 year follow-up was carried on in 16 patients monitoring blood viscosity, erythrocyte deformability and biochemical variables in relation to clinical assessment of disease activity (Disease Activity Score "DAS 28-4"). RESULTS: Erythrocyte deformability and membrane fluidity were impaired in RA patients compared to controls (p<0.001). Blood viscosity was significantly increased and correlated with the cell rigidity index (r=0.85, p<0.0000) in RA patients. The follow-up showed a good correlation between haemorheological parameters and DAS 28-4 during disease evolution. CONCLUSION: our results support the hypothesis that in RA, blood hyperviscosity is determined by deformability loss, which in turn is due to a membrane rigidization. This could evidenced that a widespread cell membrane damage is expressed through an impaired erythrocyte deformability, turning haemorheological parameters into reliable tools to study disease evolution. The follow-up study enabled us to confirm that erythrocyte deformability is an efficient indicator of rheumatoid arthritis activity.

Association between capillaroscopy, haemorheological variables and plasma proteins in patients bearing Raynaud's phenomenon.

Raynaud's phenomenon is a paroxysmal and reversible vasospasm affecting generally the acral circulatory regions. The relevance of the haemorheological alterations in these patients, as a source of ischemic events has been neglected. The objective of the present work was to evaluate and correlate the rheological blood properties, some biochemical parameters, e.g., plasma fibrinogen and immunoglobulin levels, and periungual capillaroscopy. The explicative variables considered were: blood viscosity, plasma viscosity, erythrocyte rigidity index, plasma fibrinogen, erythrocyte sedimentation rate, erythrocyte aggregate size, erythrocyte aggregation rate and serum immunoglobulin (IgG and IgM). The response variable was the nailfold capillary pattern categorised as either normal or pathological. Fibrinogen, erythrocyte aggregation rate and IgM are significantly higher in patients with a pathological pattern in comparison with patients bearing a normal one. The statistical analysis enabled us the modelling of the pathological pattern occurrence probability in function of plasma fibrinogen. Consequently, 100 mg/dl plasma fibrinogen increase, increases twice the probability of presenting a pathological pattern. Therefore, we can conclude that high levels of fibrinogen in Raynaud's phenomenon patients are associated with impaired skin microcirculation assessed by periungual capillaroscopy.

Evidence that antisulfatide autoantibodies from rats experimentally infected with Trypanosoma cruzi bind to homologous neural tissue.

Earlier studies in Trypanosoma cruzi-infected rats revealed an increased antibody activity against sulfatide, a specific constituent of both myelin sheaths of peripheral nerves and T. cruzi epimastigotes. To investigate further the characteristics of such anti-sulfatide antibodies, we analyzed their IgG isotypes as well as their ability to bind to homologous neural host structures. Antisulfatide IgG-enriched fractions were obtained from rats acutely infected with T. cruzi. Immunoglobulin isotypes were determined by an enzyme-linked immunosorbent assay (ELISA) method to show that IgG2a and, more significantly, IgG2b were the predominant isotypes of antisulfatide autoantibodies. Further immunofluorescence studies carried out in coronal sections of the rat forebrain revealed, in turn, that antisulfatide antibodies were capable of reacting with homologous neural tissues. Specific binding of these rat autoantibodies to sulfocerebroside on cell surfaces in vivo may in theory play some detrimental role, given the reported ability of rat IgG2b to fix complement or to mediate antibody-dependent cell-mediated cytotoxicity reactions.

Low occurrence of arthritic manifestations in patients with pulmonary tuberculosis. T cell subsets and humoral studies.

Given the suspected role of mycobacteria in the establishment of disorders with an autoimmune background and joint damage, a study was conducted to analyze whether rheumatic symptoms were likely to be present in tuberculosis (TB) patients. To this end, 330 patients with a bacteriologic confirmation of tuberculosis were investigated for the presence of arthritic complaints. The latter were recorded in five of them with rheumatic symptoms mostly involving interphalangeal and metacarpophalangeal joints, and preceding the clinical manifestations of the TB illness. Three out of these five patients remained arthritic by the time of the bacteriologic conversion and fulfilled the criteria for the diagnosis of rheumatoid arthritis. In the two remaining patients sputum negativization was accompanied by a disappearance of rheumatic manifestations. These patients were also assessed for their peripheral levels of major T cell subsets as well as for the presence of autoantibodies. Comparisons with a series of non-arthritic TB cases, rheumatoid arthritis patients, and controls revealed that presence of rheumatic manifestations was associated with a different profile of autoantibody formation and T cell subset changes. Evidence recorded in the present study indicates that joint affectation in TB is a rare event, being rather the exception than the rule.

[Importance of the diagnosis of Blastocystis hominis in the parasitological examination of feces]. / Importancia del diagnóstico de Blastocystis hominis en el examen parasitológico de heces.

Feces of 798 male and female patients who attended the Parasitology Laboratory of the "Facultad de Ciencias Bioquímicas y Farmacéuticas de la Universidad Nacional de Rosario (República Argentina)" were examined. Out of the total number of samples, 281 were collected after a purgative, and 517 by serial collection. The samples were examined applying the routine parasitological analysis. Those which presented Blastocysts hominis were processed for their quantification and classification in different categories according to the number of cells per microscopic field with a magnification of 400 x. B. hominis appeared in 25.2% of the patients. Practically the same percentage was detected with either collection method. B. hominis was associated with other parasites, appearing as the only parasite in only 29.4% of the cases. Both its statistical association with the patient's age and its independence from sex were determined. The most frequent symptomatology in patients with B. hominis only was: abdominal pains, pruritus, flatulence, malaise, anorexia and diarrhea. Only 14.9% did not present any symptoms at all. The search for this protozoa should be a parasitological routine analysis since it is the cause of frequent intestinal disorders.