Erythrocyte membrane band 3 profile imposed by cellular aging, by activated neutrophils and by neutrophilic elastase

A Case-Control Study Utilizing Red Cell Distribution Width as a Bio-Inflammatory Marker in Pre-eclampsia

INTRODUCTION

This research was conducted to assess the effectiveness of red cell distribution width (RDW) as an indicator for pre-eclampsia (PE), a condition characterized by elevated blood pressure and the presence of protein in the urine occurring beyond the 20th week of pregnancy.

METHODOLOGY

The case-control investigation spanned 10 months, following the acquisition of informed consent and the receipt of ethical clearance. The study sample comprised a total of 70 pregnant women, evenly divided into two groups: 35 cases of PE and 35 normotensive pregnant controls. Both the cases and controls provided 3 ml venous blood samples. The study employed a semi-automated three-part hematological analyzer to establish the baseline RDW for all individuals.

RESULTS

This study showed that the individuals with pre-eclampsia had a greater RDW compared to the healthy pregnant women. The observed difference was found to be statistically significant, with a p-value of 0.004. The receiver operating curve (ROC) analysis showed that RDW exhibited significant diagnostic accuracy in differentiating between cases and controls (area under the curve [AUC] = 0.71, P = 0.004) when employing a cut-off value of >= 18.25. The sensitivity was 80% and the specificity was 71.4%.

CONCLUSION

In contrast to other indicators of inflammation, RDW is a cost-effective and easily accessible biomarker that can be acquired from routine complete blood counts. It has the potential to be valuable in predicting and diagnosing pre-eclampsia.

Erythrocytes Functionality in SARS-CoV-2 Infection: Potential Link with Alzheimer's Disease

Coronavirus disease 2019 (COVID-19) is a rapidly spreading acute respiratory infection caused by SARS-CoV-2. The pathogenesis of the disease remains unclear. Recently, several hypotheses have emerged to explain the mechanism of interaction between SARS-CoV-2 and erythrocytes, and its negative effect on the oxygen-transport function that depends on erythrocyte metabolism, which is responsible for hemoglobin-oxygen affinity (Hb-O2 affinity). In clinical settings, the modulators of the Hb-O2 affinity are not currently measured to assess tissue oxygenation, thereby providing inadequate evaluation of erythrocyte dysfunction in the integrated oxygen-transport system. To discover more about hypoxemia/hypoxia in COVID-19 patients, this review highlights the need for further investigation of the relationship between biochemical aberrations in erythrocytes and oxygen-transport efficiency. Furthermore, patients with severe COVID-19 experience symptoms similar to Alzheimer's, suggesting that their brains have been altered in ways that increase the likelihood of Alzheimer's. Mindful of the partly assessed role of structural, metabolic abnormalities that underlie erythrocyte dysfunction in the pathophysiology of Alzheimer's disease (AD), we further summarize the available data showing that COVID-19 neurocognitive impairments most probably share similar patterns with known mechanisms of brain dysfunctions in AD. Identification of parameters responsible for erythrocyte function that vary under SARS-CoV-2 may contribute to the search for additional components of progressive and irreversible failure in the integrated oxygen-transport system leading to tissue hypoperfusion. This is particularly relevant for the older generation who experience age-related disorders of erythrocyte metabolism and are prone to AD, and provide an opportunity for new personalized therapies to control this deadly infection.

Relationship of red cell distribution width with the presence and severity of preeclampsia

AIM

Although the relationship between red cell distribution width (RDW) and hypertension has been well documented, there is an absence of data on the association between RDW and preeclampsia. In the present study, we have aimed to investigate the correlation of RDW with preeclampsia and its severity.

METHODS

The study population consisted of 52 (35 mild and 17 severe) patients with preeclampsia and 50 control pregnancy patients. For the entire study population, baseline RDW was measured using an automatic blood counter.

RESULTS

Although there were no significant differences between the preeclampsia group and the control group in terms of hemoglobin and platelet counts, the RDW (14.1 ± 1.1 vs 16.9 ± 1.7, P < .001), systolic and diastolic blood pressure, proteinuria, white blood cell, and high-sensitivity C-reactive protein levels were significantly higher in the preeclampsia group. Moreover, subgroup analysis revealed that RDW levels were significantly increased in patients with severe preeclampsia when compared to the patients with mild preeclampsia (18 ± 1.5 vs 16.4 ± 1.5, P < .001).

CONCLUSION

Our study results revealed that RDW levels were associated with both the presence and the severity of preeclampsia.

Eryptotic phenotype in chronic myeloid leukemia: contribution of neutrophilic cathepsin g

In pathological conditions with concurrent neutrophilia, modifications of erythrocyte membrane proteins are reported. In chronic myeloid leukemia (CML), a myeloproliferative disease wherein neutrophilia is accompanied by enhanced erythrophagocytosis, we report for the first time excessive cleavage of erythrocyte band 3. Distinct fragments of band 3 serve as senescent cell antigens leading to erythrophagocytosis. Using immunoproteomics, we report the identification of immunogenic 43 kDa fragment of band 3 in 68% of CML samples compared to their detection in only 38% of healthy individuals. Thus, excessive fragmentation of band 3 in CML, detected in our study, corroborated with the eryptotic phenotype. We demonstrate the role of neutrophilic cathepsin G, detected as an immunogen on erythrocyte membrane, in band 3 cleavage. Cathepsin G from serum adsorbs to the erythrocyte membrane to mediate cleavage of band 3 and therefore contribute to the eryptotic phenotype in CML.

Erythroid disturbances before and after treatment of Portuguese psoriasis vulgaris patients: a cross-sectional and longitudinal study

BACKGROUND

A few studies in psoriasis vulgaris patients have reported changes suggesting red blood cell (RBC) damage is linked to neutrophil activation, oxidative stress, and psoriasis worsening.

OBJECTIVE

The aim of this study was to evaluate erythroid disturbances in Portuguese psoriasis vulgaris patients, before, during, and after treatment.

METHODS

A cross-sectional study (n = 73 patients vs 40 healthy control subjects) followed by a longitudinal study (n = 47 patients) was performed, with assessments before, and at 3, 6, and 12 weeks of therapy (10 patients started topical treatment, 17 narrow-band UVB, and 20 photochemotherapy [psoralen plus UVA; PUVA]). Evaluations included hematologic data, total bilirubin levels, membrane-bound hemoglobin (MBH), membrane protein band 3 profile, total plasma antioxidant status (TAS), lipid peroxidation (thiobarbituric acid [TBA] assay), elastase, lactoferrin, and C-reactive protein (CRP).

RESULTS

Before treatment, patients presented with higher leukocyte/neutrophil and reticulocyte counts, elastase, lactoferrin, TBA, TBA/TAS, reticulocyte production index, total bilirubin and MBH values, lower RBC and hematocrit, higher percentages of high-molecular-weight aggregates, and lower percentages of band 3 monomer. After treatment, we observed a reversal in most of the parameters. However, patients still presented with values suggestive of accelerated RBC damage, removal, and production, as most of the parameters were still higher than those in the control group; the same occurred with CRP.

CONCLUSION

Our data suggest that psoriasis vulgaris triggers an inflammatory response, with release of acute-phase reactants, reactive oxygen species, cationic proteins, and proteases, leading to enhanced RBC damage/aging and, ultimately, to enhanced RBC removal. These assumptions were strengthened by the observation that, with treatment, all of these changes were reversed, the inflammation was reduced, the production of reticulocytes was increased, and the RBCs presented changes usually observed in younger/less damaged RBCs. These erythroid changes were enhanced with PUVA therapy, probably due to the more pronounced clearing of the lesions, as suggested by Psoriasis Area and Severity Index (PASI) scores. Finally, after treatment, a residual inflammation still persisted that might contribute to the observed erythroid disturbances.

Erythrocyte changes in preeclampsia: relationship between maternal and cord blood erythrocyte damage

Our aim was to evaluate red blood cell (RBC) changes in normal and preeclamptic cases, and to assess the relationship between maternal and umbilical cord blood (UCB) changes. We evaluated markers of RBC damage: membrane bound hemoglobin (MBH) and band 3 profile - high molecular weight aggregates (HMWSAg), monomer and proteolytic fragments. RBCs are marked for removal by a rise in MBH and in HMWAg. Preeclamptic mothers had significantly higher MBH, RBC count, hemoglobin, hematocrit, reticulocytes and reticulocyte production index (RPI). In UCB from newborns of preeclamptic mothers, we found similar HMWAg, RBC count, hemoglobin and hematocrit; significantly higher MBH, mean cell hemoglobin concentration, mean cell volume, RPI and reticulocyte count. Maternal MBH and HMWAg values were positively and significantly correlated with MBH and HMWAg values in UCB, in normal as well as in preeclamptic pregnancies; in preeclampsia, a significant positive correlation between UCB and maternal bilirubin, and between RPI and proteinuria were found. We conclude that markers of RBC damage/production are altered in preeclampsia, in both UCB and maternal circulation. Our data show similarities between UCB and maternal RBC changes, as suggested by the correlations of markers of RBC damage.

Structural alterations of erythrocyte membrane components induced by exhaustive exercise

Physical exercise was used as a model of the physiological modulator of free radical production to examine the effects of exercise-induced oxidative modifications on the physico-biochemical properties of erythrocyte membrane. The aim of our work was to investigate conformational changes of erythrocyte membrane proteins, membrane fluidity, and membrane susceptibility to disintegration. Venous blood was taken before, immediately after, and 1 h after an exhaustive incremental cycling test (30 W·min–1ramp), performed by 11 healthy untrained males on balanced diets (mean age, 22 ± 2 years; mean body mass index, 25 ± 4.5 kg·m–2). In response to this exercise, individual maximum heart rate was 195 ± 12 beats·min–1and maximum wattage was 292 ± 27 W. Electron paramagnetic resonance spectroscopy was used to investigate alterations in membrane proteins and membrane dynamics, and to measure production of radical species. The reducing potential of plasma (RPP) was measured using the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the ferric-reducing ability of plasma. Exercise induced decreases in erythrocyte membrane fluidity in the polar region (p < 0.0001) and alterations in the conformational state of membrane proteins (p < 0.05). An increase in RPP was observed immediately after exercise (p < 0.001), with a further increase 1 h postexercise (p < 0.0001). Supporting measurements of lipid peroxidation showed an increase in thiobarbituric acid reactive substances immediately after exercise (p < 0.05) and at 1 h of recovery (p < 0.001); however, free radicals were not detected. Results indicate the existence of early postexercise mild oxidative stress after single-exercise performance, which induced structural changes in erythrocyte membrane components (protein aggregation) and in the membrane organization (lipids rigidization) that followed lipid peroxidation but did not lead to cellular hemolysis.

Erythrocyte damage in mild and severe psoriasis

BACKGROUND

Psoriasis is a common chronic and recurrent inflammatory skin disorder. Oxygen metabolites and proteases released by activated inflammatory cells may induce oxidative and proteolytic damage to plasma constituents and red blood cells (RBCs). RBCs have a limited biosynthesis capacity and poor repair mechanisms.

OBJECTIVES

To study RBCs as a potential cumulative marker of oxidative and proteolytic stress in psoriasis, and as a marker of worsening of the disease.

METHODS

The study was performed in 70 patients with mild or severe psoriasis and in 40 control individuals. We evaluated total and differential leucocyte count and, as markers of leucocyte activation, plasma elastase and lactoferrin. Besides the basic RBC study (RBC count, haematocrit, haemoglobin concentration and haematimetric indices) we evaluated antioxidant defences (catalase, superoxide dismutase, glutathione peroxidase and selenium), osmotic fragility and reticulocyte count; in the RBC membrane we evaluated lipid peroxidation and susceptibility to lipid peroxidation, membrane fluidity, levels of cholesterol and phospholipids, membrane-bound haemoglobin, band 3 profile and levels of vitamin E; serum levels of bilirubin, total plasma antioxidant capacity, lipid profile and lipid peroxidation were also evaluated.

RESULTS

Psoriasis patients showed a rise in leucocytes, mainly neutrophils, which was associated with a rise in elastase and lactoferrin. Patients had a reduced RBC count, antioxidant defences and membrane fluidity, elevated membrane lipid peroxidation, membrane-bound haemoglobin, osmotic fragility and reticulocyte count, and a different band 3 profile. Most of these modifications were enhanced in severe psoriasis.

CONCLUSIONS

In summary, our data show that the RBCs are at a lower number in psoriasis patients, and present several changes denoting an enhanced damage and/or ageing process, which seem to be strongly connected with neutrophil activation, oxidative stress and worsening of psoriasis.

Band 3 as a marker of erythrocyte changes in pregnancy

Modifications in the erythrocyte membrane protein band 3 seem to mark the cell for death. A decrease in band 3 high molecular weight aggregates (HMWAg) and a rise in its proteolytic fragments (Pfrag) were described for younger erythrocytes. The aim of this work was to study the band 3 profile as a marker of erythrocyte changes in pregnancy and postpartum. We performed a cross-sectional study in non-pregnant controls (n = 24), in women in the first (n = 64), second (n = 48) and third (n = 67) trimesters of gestation, and also in the puerperium (24-48 h after delivery; n = 32); we also carried out a longitudinal study (n = 23) during the three trimesters of normal pregnancy. We evaluated the band 3 profile (% of band 3 monomer, HMWAg, and Pfrag) and the membrane-bound haemoglobin. Total serum bilirrubin, glutathione peroxidase activity, red blood cell (RBC) count, haematocrit (Ht), haemoglobin (Hb) concentration, the haematimetric indices, and red cell distribution width were also evaluated. Similar results were found in pregnancy in both the cross-sectional and longitudinal studies. We found that the RBC count, Hb, and Ht decreased significantly in pregnancy and in puerperium. Band 3 profile in the first trimester of pregnancy, when compared with controls, presented significantly reduced HMWAg and increased Pfrag. Comparing the first with the third trimester, we found a significant reduction in band 3 and a significant rise in Pfrag. However, between these same periods, HMWAg did not decrease. Our data suggest band 3 profile as a marker of erythrocyte changes in pregnancy, which are independent of the 'physiological anaemia' of pregnancy. These changes suggest an increase in damaged RBCs, but also an increase in younger RBCs in the maternal circulation.

Erythrocyte damage and leukocyte activation in ischemic stroke

BACKGROUND

The traditional lipid risk factors can only predict some of the cardiovascular events. Our work has focused on new potential biological markers of risk, namely leukocyte activation and erythrocyte membrane damage, in ischemic stroke cases.

METHODS

Besides the traditional lipid profile, we evaluated the plasma levels of elastase and lactoferrin as markers of leukocyte activation, and membrane band 3 protein profile and membrane bound hemoglobin as markers of erythrocyte damage. Total and differential leukocyte counts and erythrocyte counts, hematocrit and hemoglobin concentrations were also evaluated. The lipid study included the evaluation of triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), apolipoprotein AI (Apo AI) and B (Apo B), and lipoprotein (a) (Lp(a)). The work was performed in a control group (n=29) with no history of cardiovascular events, presenting normal hematological and lipid values, and in a pathologic group (n=21) of ischemic stroke cases diagnosed by computed tomographic imaging.

RESULTS

We found that ischemic stroke was associated with significantly higher values of leukocytes, which seem to be activated, as shown by significant higher levels of elastase and lactoferrin. This activation seems to impose erythrocyte damage, as suggested by a significant increase in membrane bound hemoglobin and by a different band 3 profile.

CONCLUSIONS

Our data suggest that plasma levels of elastase and lactoferrin, together with levels of erythrocyte membrane bound hemoglobin and band 3 profile, could be used as powerful new markers of risk for cardiovascular events.

Leukocyte activation, erythrocyte damage, lipid profile and oxidative stress imposed by high competition physical exercise in adolescents

BACKGROUND

The aim of this study was to evaluate and to compare the lipid profile and the levels of leukocyte activation, red blood cell (RBC) damage and of oxidative stress in two groups of adolescents, with similar body mass index: high competition swimmers and adolescents practising moderate regular physical exercise.

METHODS

As markers of leukocyte activation, we measured plasma lactoferrin, elastase and granulocyte-monocyte colony stimulating factor. We studied RBC membrane band 3 profile and membrane-bound hemoglobin, as markers of RBC damage and aging; total and differential leukocyte count and RBC count, hematocrit, hemoglobin concentration and hematimetric indexes were also measured. Lipid profile included the evaluation of triglycerides (TG), total cholesterol (Chol), high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), apolipoproteins AI and B (Apo AI and B), and lipoprotein (a) (Lp(a)). To evaluate oxidative stress, lipoperoxidation products and total antioxidant capacity were measured.

RESULTS

We found that high competition adolescents presented increased plasma levels of leukocyte activation products, increased RBC damage suggesting aging and premature removal, and higher oxidative stress. Lipid profile showed some risk and some protective changes.

CONCLUSIONS

Our data suggest that high competition exercise, by imposing a higher and sustained oxidative and proteolytic stress, may contribute in the future to a higher risk of cardiovascular disease. We believe these findings warrant a reevaluation of current views in the intensity, duration and regularity of physical exercise, and that the evaluation of leukocyte activation products, RBC damage, oxidative stress and lipid profile may represent good markers to establish putative protective thresholds.