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![A representative RBC from a type 2 diabetes patient (Raw data from [83]. Erythrocyte deformability is often found to be moderately impaired in diabetes mellitus patients, due to several metabolic and hormonal disturbances (glycation and oxidative stress) that may also promote eryptosis. This is an example of "covertly abnormal blood rheology", which is supposed to induce microcirculatory disturbances. The main glucose-regulating hormones insulin and glucagon have also been reported to exert an influence on red cell deformability, whose pathophysiological relevance remains unclear.](publication/357244539/figure/fig2/AS:1103794712653827@1640176575765/A-representative-RBC-from-a-type-2-diabetes-patient-Raw-data-from-83-Erythrocyte.png)
A representative RBC from a type 2 diabetes patient (Raw data from [83]. Erythrocyte deformability is often found to be moderately impaired in diabetes mellitus patients, due to several metabolic and hormonal disturbances (glycation and oxidative stress) that may also promote eryptosis. This is an example of "covertly abnormal blood rheology", which is supposed to induce microcirculatory disturbances. The main glucose-regulating hormones insulin and glucagon have also been reported to exert an influence on red cell deformability, whose pathophysiological relevance remains unclear.
Source publication
![Figure 1. A brief overview of eryptosis (adapted from [47]) showing the...](publication/357244539/figure/fig1/AS:1103794712657922@1640176575662/A-brief-overview-of-eryptosis-adapted-from-47-showing-the-pathways-that-initiate-it_Q320.jpg)
Many factors in the surrounding environment have been reported to influence erythrocyte deformability. It is likely that some influences represent reversible changes in erythrocyte rigidity that may be involved in physiological regulation, while others represent the early stages of eryptosis, i.e., the red cell self-programmed death. For example, e...
Contexts in source publication
Context 1
... changes in blood glucose concentration may be associated with some hemorheological alterations, but when these changes reach a pathological range, they may be associated with red cell damage due to free radicals or other factors and thus trigger irreversible alterations and eryptosis. Figure 3 shows an RBC from an individual with diabetes. Figure 3 shows an RBC from an individual with diabetes. ...
Context 2
... 3 shows an RBC from an individual with diabetes. Figure 3 shows an RBC from an individual with diabetes. Figure 3. ...
Citations
... Glucose is a main substrate for energetic metabolism of erythrocytes, and it is well known that in the presence of long-lasting hyperglycemia in DM, the morphology, metabolism, and function of erythrocytes are inevitably subject to a series of changes that further affect hemorheology and microcirculation (Zhou et al. 2018;Sprague et al. 2006). Nevertheless, DM still represents an example of "covertly abnormal" blood rheology (Schmid-Schönbein, 1987, Brun et al. 2022) since it cannot be always determined by commercially available point-of-care (POC) devices within clinical environment. Ektacytometry, a laser diffraction technique, is the primary method for evaluating the deformability of erythrocytes in both research and clinical settings (Piety et al. 2021), based on the calculated EI from the diffraction images recorded on different shear stresses. ...
Comparative analysis of erythrocyte deformability in individuals with Diabetes Mellitus (DM) and healthy individuals (Control) was represented, focusing on the Elongation index (EI) calculation based on diffraction images. While no statistically significant differences in EI values were observed between the groups, we determined specific points along the deformability curve and revealed the first derivative of deformability curve (dEI / dSS) as a potential metric for quantifying erythrocyte response to deformation, where SS represents shear stress in Pa (Pascal). Statistically significant differences in dEI / dSS at the half maximum value of the deformability curve were identified, suggesting a slower erythrocyte response to shear stress in DM patients. Scatter plot analysis demonstrated a linear declining trend in dEI / dSS index with an increase in shear stress, indicating decaying erythrocyte responsiveness to higher shear stress values, particularly pronounced in DM patients. Although pilot, this study suggests that dEI / dSS can provide valuable insights into the hemorheological aspects of DM pathology and contribute to a comprehensive understanding of erythrocyte mechanobiological behavior in response to varying shear stress levels. Correlations between the proposed measure of RBC mechanical properties and established clinical markers of DM and its complications (serum cholesterol, creatinine, and urea level) are obtained to get preliminary insight into dEI / dSS application for better diagnosis and/or patient management.
... Recently, considerable experimental evidence has been accumulated about the mechanisms of adaptive regulation of RBC deformability in response to hypoxia, oxidative stress and various physiological requirements of the organism (Brun et al. 2022;Cilek et al. 2023). Majority of these mechanisms involve molecular signaling cascades, which are directed to the re-arrangements of the cytoskeleton proteins to weaken their interaction with each other and provide a better flexibility of the whole cytoskeletal network (Barshtein et al. 2023). ...
In this study, fluorescence recovery after photobleaching (FRAP) experiments were performed on RBC labeled by lipophilic fluorescent dye CM-DiI to evaluate the role of adenylyl cyclase cascade activation in changes of lateral diffusion of erythrocytes membrane lipids. Stimulation of adrenergic receptors with epinephrine (adrenaline) or metaproterenol led to the significant acceleration of the FRAP recovery, thus indicating an elevated membrane fluidity. The effect of the stimulation of protein kinase A with membrane-permeable analog of cAMP followed the same trend but was less significant. The observed effects are assumed to be driven by increased mobility of phospholipids resulting from the weakened interaction between the intermembrane proteins and RBC cytoskeleton due to activation of adenylyl cyclase signaling cascade.
Graphical abstract
... We could observe significantly lower EIs at middle shear stress in patients not on target TG. In the background the RBC membrane damage could be assumed, caused by increased RBC aggregation and WBV [33]. ...
... We could also observe lower RBC deformability values at all shear stresses in diabetes. Impaired RBC deformability is in connection with higher glucose, significantly higher TG level and the stimulated oxidative stress leading to RBC membrane injuries [33]. The decrease in RBC deformability could contribute to reduced tissue oxygenation and nutritional supply, which could lead to life-threatening microcirculatory complications like peripheral artery disease, ulcers, amputations as well as to limited quality of life [29]. ...
Background and aims
This study aimed to validate the role of high low-density lipoprotein cholesterol [LDL-C] and triglyceride [TG] treatment target levels on the microcirculation in a very high and high cardiovascular risk group.
Methods
119 patients with high or very high cardiovascular [CV] risk were included. We have registered the main co-morbidities, smoking habits, body mass index [BMI] and the lipid lowering medication. Hematocrit, whole blood viscosity [WBV] and plasma viscosity [PV], red blood cell [RBC] aggregation and deformability and fibrinogen, total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], LDL-C and TG levels were determined.
Results
The investigation found significantly higher PV values in patients with non-target LDL-C, associated with higher fibrinogen level. Non-target TG was related to deteriorated microcirculatory parameters, as significantly higher RBC aggregation, lower RBC deformability, and higher WBV and PV. The main microcirculatory benefit in diabetes could be gained from target level of TG, in chronic coronary syndrome [CCS] patients it is more advantageous to reach both LDL-C and TG target.
Conclusion
The results could highlight, that TG should play a role in failing microcirculation and cause potentially life-threatening complications, which would worsen the survival and quality of life of high or very high risk CV patients.
... The deformability of erythrocytes is primarily related to membrane properties and morphology (Brun et al., 2021), and reduced deformability of erythrocytes can easily result in hemolysis. In individuals who rapidly ascend to high altitudes, a significant number of abnormal erythrocytes are present. ...
Introduction: High-altitude polycythemia (HAPC) is a common chronic high-altitude disease characterized by significantly increased erythrocyte, hemoglobin (Hb), and hematocrit values and decreased arterial oxygen saturation. The mechanisms underlying HAPC development are unclear; we aimed to investigate this in an HAPC rat model.
Methods: Twelve Sprague–Dawley rats were divided into control and HAPC groups. The HAPC group was exposed to hypobaric hypoxia. This HAPC model was assessed using routine blood tests and blood gas analyses. Bone marrow, peripheral blood reticulocytes (RETs), and peripheral blood erythrocyte apoptosis were measured using flow cytometry. Erythrocyte osmotic fragility (EOF) tests were conducted. Abnormal erythrocytes were counted using electron microscopy. Plasma-free hemoglobin, 5′-nucleotidase (CD73), adenosine, erythrocyte cytosolic adenosine, sphingosine-1-phosphate (S1P), and 2,3-bisphosphoglycerate (BPG) levels were measured using enzyme-linked immunosorbent assays. Erythrocyte metabolic pathway-related protein [adenosine A2B receptor (ADORA2B), erythrocyte equilibrative nucleoside transporter 1 (eENT1), sphingosine kinase 1 (SPHK1), phospho-SPHK1, bisphosphoglycerate mutase (BPGM), and glyceraldehyde 3-phosphate dehydrogenase (GAPDH)] levels were assessed by Western blotting.
Results: The HAPC rat model was successfully established (Hb > 210 g/L). Indices of bone marrow and peripheral blood RET proportions were significantly higher in the HAPC than the control group (p = 0.04 and p < 0.001, respectively). The proportion of peripheral blood erythrocytes in early apoptosis was significantly lower in the HAPC than the control group (p < 0.001). Vesicular erythrocyte and acanthocyte proportions were significantly higher in the HAPC than the control group (p < 0.001 and p = 0.019, respectively). The EOF tests revealed that 50% erythrocyte hemolysis occurred at 4.0–4.5 and 4.5–5.0 g/L NaCl in the control and HAPC groups, respectively. Plasma-free hemoglobin, CD73, adenosine, erythrocyte cytosolic adenosine, S1P, and 2,3-BPG levels and ADORA2B, eENT1, phospho-SPHK1, S1P, BPGM, and GAPDH erythrocyte expression levels (all p ≤ 0.02) were significantly higher in the HAPC than the control group.
Conclusion: In model rats, an HAPC-related erythrocyte increase was associated with enhanced bone marrow hematopoietic function and reduced erythrocyte apoptosis, whereas numerous abnormal erythrocytes, increased EOF, and reduced hemolysis resistance were associated with erythrocyte metabolism. CD73/adenosine/S1P/2,3-BPG and eENT1/adenosine/BPGM/2,3-BPG metabolic pathways in erythrocytes were activated in HAPC rats, facilitating oxygen release. These findings further reveal the intrinsic HAPC mechanism and forms a basis for future development of preventive and therapeutic strategies for HAPC.
... Taken together, these findings suggest a central role for RBCs in systemic NO metabolism; not just as "pools", but also as storers, producers, and transporters. Nonetheless, RBCs are not solely mediators in these events, rather NO has been implicated in modulating several RBC properties, including deformability and removal (Brun et al., 2021). ...
Red blood cells, the most abundant cell type in circulation, were thought to be quite simple in terms of structure and function. However, we hereby present several paradoxes and peculiarities which question the notion that they are just hemoglobin carriers. As examples, they retain their nucleus and/or mitochondria in specific settings; they are characterized by an impressively plastic proteome, transcriptome, and metabolome, all of which change under pathological conditions; their structural proteins are not only there to maintain shape and integrity, but also exhibit noncanonical functions; and hemoglobin is not solely dedicated to oxygen transport. Their versatile nature, and especially their ability to undergo changes in disease states, combined with their generalized circulation throughout the body, showcase them as ideal indicators of the whole organism’s homeostasis. Indeed, red blood cells are known to carry disease-related signatures with biomarker potential in hematological, neurodegenerative, and autoimmune disorders, and in cancer and infections. This potential could be useful for diagnostic, prognostic, and monitoring purposes. Additionally, in hematological conditions and other pathologies, red blood cells and their cargo can serve as drug targets to ameliorate disease manifestations, while their effectiveness in drug delivery has been examined in animal models and clinical trials. We hope this perspective will appeal to the scientific community to focus on the utility and potential of this underappreciated cell.
... Eryptotic cells pose various threats to homeostasis as the risk of thrombotic events is augmented by the adherence of PS-exposing RBCs to the endothelium. Moreover, dead RBCs have been shown to lose their deformability thereby forming aggregates that increase blood viscosity, obstruct the microcirculation, and hinder oxygen transport and tissue perfusion [18]. In this regard, the eryptotic activity of TAM is consistent with previous reports showing the stimulation of apoptosis by TAM in breast cancer cells [10,[19][20][21]. ...
Chemotherapy-related anemia is a major obstacle in anticancer therapy. Tamoxifen (TAM) is an antiestrogen prescribed for breast cancer patients with hemolytic potential and apoptotic properties in nucleated cells. However, the eryptotic activity of TAM has hitherto escaped the efforts of investigators. RBCs from apparently healthy volunteers were treated with 1–50 μM of TAM for 24 h at 37 °C. Hemoglobin leakage and LDH, AST, and AChE activities were photometrically determined while K⁺, Na⁺, and Mg²⁺ were detected by ion-selective electrode. Flow cytometry was used to identify eryptotic cells by annexin-V-FITC, intracellular Ca²⁺ by Fluo4/AM, sell size and morphology by FSC and SSC signals, respectively, and oxidative stress by H2DCFDA. Whole blood was also exposed to 30 μM of TAM for 24 h at 37 °C to examine the toxicity of TAM to WBCs and platelets. TAM caused Ca²⁺-independent, dose-responsive hemolysis accompanied by K⁺, LDH, and AST leakage without improving the mechanical stability of RBCs in hypotonic environments. TAM treatment also increased the proportion of cells positive for annexin-V-FITC, Fluo4, and DCF, along with diminished FSC and SSC signals and AChE activity. Notably, TAM toxicity was aggravated by sucrose but abrogated by vitamin C, PEG 8000, and urea. Moreover, TAM exhibited distinct cytotoxic profiles against leukocytes and platelets. TAM-induced eryptosis is characterized by breakdown of membrane asymmetry, inhibition of AChE activity, Ca²⁺ accumulation, cell shrinkage, and oxidative stress. Vitamin C, PEG 8000, and urea may hold promise to subvert the undesirable toxic effects of TAM on RBCs.
Graphical abstract
... The mechanisms underlying the association between elevated RAR and rheumatic disease patients admitted in ICU have not been fully elucidated. Oxidative stress in the body and systemic inflammatory response can lead to the inhibition of erythropoiesis, the promotion of erythrocyte apoptosis, the reduction of iron metabolism, the modifying of erythrocyte membranes and the altering of erythrocyte morphology (25)(26)(27)(28)(29)(30). These pathological changes result in increased heterogeneity of red blood cell volume, which manifests as an elevated RDW. ...
Background
Patients with rheumatic diseases have an increased likelihood of being admitted to the intensive care unit (ICU), highlighting the importance of promptly identifying high-risk individuals to enhance prognosis. This study aimed to assess the correlation of red blood cell distribution width to albumin ratio (RAR) with the 90-days and 360-days survival rates among critically ill rheumatic patients.
Methods
Adult rheumatic patients admitted to the ICU from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database were included. The participants were categorized into two groups, survivors ( n = 436) and non-survivors ( n = 192), based on their 90-days survival outcome. The population was further classified into tertiles using RAR values, with RAR < 4.63 ( n = 208), 4.63–6.07 ( n = 211), and > 6.07 ( n = 209). Kaplan–Meier curves were utilized to evaluate the cumulative survival rates at 90-days and 360-days. The association between RAR and mortality was assessed using restricted cubic splines (RCS) and multivariate Cox regression analysis. Additional subgroup analyses and sensitivity analyses were conducted to further explore the findings. Receiver operating characteristic (ROC) curves were generated to evaluate the predictive performance of RAR.
Results
This study involved 628 critically ill patients with rheumatic diseases, and they had an all-cause mortality of 30.57% at 90-days and 38.69% at 360-days. Kaplan–Meier analysis showed a gradual decrease in both 90-days and 360-days cumulative survival with increasing RAR (χ2 = 24.400, p < 0.001; χ2 = 35.360, p < 0.001). RCS revealed that RAR was linearly related to 90-days and 360-days all-cause mortality risk for critically ill patients with rheumatic diseases (χ2 = 4.360, p = 0.225; χ2 = 1.900, p = 0.594). Cox regression analysis indicated that elevated RAR (> 6.07) was significantly correlated with mortality. The ROC curves demonstrated that an optimal cut-off value of RAR for predicting 90-days mortality was determined to be 5.453, yielding a sensitivity of 61.5% and specificity of 60.3%.
Conclusion
Elevated RAR (> 6.07) was associated with all-cause mortality at 90-days and 360-days among critically ill patients with rheumatic diseases, serving as an independent risk factor for unfavorable prognosis.
... Other adipokines may be also involved. This may represent a physiological axis allowing body's energy stores to modulate microcirculatory exchanges of energetic substances [3]. On the whole, this report on a limited sample confirms that two hemorheological factors: hematocrit and erythrocyte aggregation, are related to body composition. ...
The size of body compartments is a determinant of several factors of blood viscosity. Red cell aggregation is proportional to fat mass while hematocrit is proportional to both fat-free mass and abdominal adiposity, but which parts of these body components are involved in this relationship is not known. Segmental bioelectrical impedance analysis (sBIA) provides a possibility to delineate the relationships more precisely between various subdivisions of the body and blood viscosity factors, going farther than preceding studies using non segmental BIA. In this study we investigated in 38 subjects undergoing a standardized breakfast test with mathematical modelling of glucose homeostasis and a segmental bioelectrical impedance analysis (sBIA) the relationships between the various compartments of the body and viscosity factors. Blood and plasma viscosity were measured with the Anton Paar rheometer and analyzed with Quemada’s model. The parameters better correlated to hematocrit are fat free mass (r = 0.562) and its two components muscle mass (r = 0.516) and non-muscular fat-free mass (r = 0.452), and also trunk fat mass (r = 0.383) and waist-to hip ratio (r = 0.394). Red cell aggregation measurements were correlated with both truncal and appendicular fat mass (r ranging between 0.603 and 0.728). Weaker correlations of M and M1 are found with waist circumference and hip circumference. This study shows that the correlation between lean mass and hematocrit involves both muscle and non-muscle moieties of lean mass, and that both central and appendicular fat are determinants of red cell aggregation.
... Within circulation, RBCs are exposed to varying physiologic and pathologic environments from which they accrue damages leading to the activation of various ion channels and intracellular enzymes [96,97]. These changes, in turn, cascade into alterations of the phospholipid pattern of the cell membrane, leading to flipping of the aminophospholipid phosphatidylserine [98] on the membrane's surface [99][100][101]. ...
... In the laboratory, RBC deformability is quantified using an ektacytometer, a laser-diffraction viscometer that detects changes in cell water content, surface area, and heterogeneity in these cellular properties [194]. In various systemic diseases, including DM, a myriad of factors dictates RBC deformability changes, such as the physiochemical properties of the extracellular environment, purinergic signaling, oxidative damage, NO, and ionic balance [96]. ...
Diabetes Mellitus (DM) is a complex metabolic disorder associated with multiple microvascular complications leading to nephropathy, retinopathy, and neuropathy. Mounting evidence suggests that red blood cell (RBC) alterations are both a cause and consequence of disturbances related to DM-associated complications. Importantly, a significant proportion of DM patients develop varying degrees of anemia of confounding etiology, leading to increased morbidity. In chronic hyperglycemia, RBCs display morphological, enzymatic, and biophysical changes, which in turn prime them for swift phagocytic clearance from circulation. A multitude of endogenous factors, such as oxidative and dicarbonyl stress, uremic toxins, extracellular hypertonicity, sorbitol accumulation, and deranged nitric oxide metabolism, have been implicated in pathological RBC changes in DM. This review collates clinical laboratory findings of changes in hematology indices in DM patients and discusses recent reports on the putative mechanisms underpinning shortened RBC survival and disturbed cell membrane architecture within the diabetic milieu. Specifically, RBC cell death signaling, RBC metabolism, procoagulant RBC phenotype, RBC-triggered endothelial cell dysfunction, and changes in RBC deformability and aggregation in the context of DM are discussed. Understanding the mechanisms of RBC alterations in DM provides valuable insights into the clinical significance of the crosstalk between RBCs and microangiopathy in DM.
... However, eryptosis activation is not observed in women with AUB alone. Thyroid hormones are generally reported to be antiapoptotic [29] and mature erythrocytes possess receptors for thyroid hormones [30]. Conversely, there is some evidence that thyroid hormones can induce apoptosis of red blood cell progenitors [31]. ...
Aim. To analyze the eryptosis degree, the state of cell membranes and redox status of circulating red blood cells and leukocytes in patients with abnormal uterine bleeding and its combination with hypothyroidism. Materials and methods. Patients, 74 women aged 18 to 49 years, were examined, which were divided into 3 groups: group I - women with abnormal uterine bleeding (AUB) (24 patients); group II - with AUB and thyroid pathology (30 patients, of whom 18 women had primary hypothyroidism and 2 - secondary hypothyroidism); group III - control group (20 healthy women, who had never had menstrual irregularities). Eryptosis of circulating erythrocytes was assessed by flow cytometry using annexin V staining and 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) staining. Fluorescent probes O1O (2-(2¢-hydroxy-phenyl)-5-phenyl-1,3-oxazole) and PH7 (2-(2¢-hydroxy-phenyl)-phenanthro[9,10-d]-1,3-oxazole) were used to characterize changes in phospholipid bilayers of circulating erythrocytes and leukocytes. Lysed blood samples were stained with antibodies to CD45, 7-aminoactinomycin D and H2DCFDA to analyze the redox status of circulating viable leukocytes. Results. Annexin V staining revealed eryptosis activation in females with abnormal uterine bleeding combined with hypothyroidism. In addition, in these patients, oxidative stress developed in red blood cells, evidenced by an increase in intracellular reactive oxygen species (ROS) levels. Oxidative stress was accompanied by changes in the physico-chemical properties of erythrocyte membranes, namely a decrease in membrane hydration and an increase in lipid order, which can indicate enhanced lipid peroxidation. These changes were observed in women with abnormal uterine bleeding alone, however, to a lesser extent. In this study, the redox state of leukocytes and phospholipid bilayers of their cell membranes were not affected in the patients from both groups. Conclusions. Abnormal uterine bleeding combined with hypothyroidism is associated with eryptosis activation, oxidative stress development in erythrocytes and changes in the physico-chemical properties of phospholipid bilayer of cell membranes in red blood cells.
