Impaired deformability of circulating erythrocytes obtained from nondiabetic hypertensive patients: investigation by a nickel mesh filtration technique

Deformability of Heterogeneous Red Blood Cells in Aging and Related Pathologies

Aging is interrelated with changes in red blood cell parameters and functionality. In this article, we focus on red blood cells (RBCs) and provide a review of the known changes associated with the characterization of RBC deformability in aging and related pathologies. The biophysical parameters complement the commonly used biochemical parameters and may contribute to a better understanding of the aging process. The power of the deformability measurement approach is well established in clinical settings. Measuring RBCs' deformability has the advantage of relative simplicity, and it reflects the complex effects developing in erythrocytes during aging. However, aging and related pathological conditions also promote heterogeneity of RBC features and have a certain impact on the variance in erythrocyte cell properties. The possible applications of deformability as an early biophysical biomarker of pathological states are discussed, and modulating PIEZO1 as a therapeutic target is suggested. The changes in RBCs' shape can serve as a proxy for deformability evaluation, leveraging single-cell analysis with imaging flow cytometry and artificial intelligence algorithms. The characterization of biophysical parameters of RBCs is in progress in humans and will provide a better understanding of the complex dynamics of aging.

Hypertension Increases Susceptibility to Experimental Malaria in Mice

Global prevalence of hypertension is on the rise, burdening healthcare, especially in developing countries where infectious diseases, such as malaria, are also rampant. Whether hypertension could predispose or increase susceptibility to malaria, however, has not been extensively explored. Previously, we reported that hypertension is associated with abnormal red blood cell (RBC) physiology and anemia. Since RBC are target host cells for malarial parasite, Plasmodium, we hypothesized that hypertensive patients with abnormal RBC physiology are at greater risk or susceptibility to Plasmodium infection. To test this hypothesis, normotensive (BPN/3J) and hypertensive (BPH/2J) mice were characterized for their RBC physiology and subsequently infected with Plasmodium yoelii (P. yoelii), a murine-specific non-lethal strain. When compared to BPN mice, BPH mice displayed microcytic anemia with RBC highly resistant to osmotic hemolysis. Further, BPH RBC exhibited greater membrane rigidity and an altered lipid composition, as evidenced by higher levels of phospholipids and saturated fatty acid, such as stearate (C18:0), along with lower levels of polyunsaturated fatty acid like arachidonate (C20:4). Moreover, BPH mice had significantly greater circulating Ter119+ CD71+ reticulocytes, or immature RBC, prone to P. yoelii infection. Upon infection with P. yoelii, BPH mice experienced significant body weight loss accompanied by sustained parasitemia, indices of anemia, and substantial increase in systemic pro-inflammatory mediators, compared to BPN mice, indicating that BPH mice were incompetent to clear P. yoelii infection. Collectively, these data demonstrate that aberrant RBC physiology observed in hypertensive BPH mice contributes to an increased susceptibility to P. yoelii infection and malaria-associated pathology.

Prevalence of anemia and associated factors among adult hypertensive patients in Referral Hospitals, Amhara Regional State

Anemia is a risk factor for adverse cardiovascular disease outcomes in hypertensive patients. Chronic anemia increases preload, reduces afterload, and leads to increased cardiac output in hypertension patients. In the long term, this may result in maladaptive left ventricular hypertrophy, which in turn is a well-recognized risk factor for cardiovascular disease outcomes and all-cause mortality in hypertension. Low hemoglobin and hematocrit levels might be strongly indicate hypertensive end-organ damage, specifically kidney failure. Therefore, this study determined the prevalence of anemia and associated factors among hypertensive patients in Referral Hospitals, Amhara Regional State, Ethiopia, in 2020. An institution-based cross-sectional study was conducted in Amhara Regional Referral Hospitals from February 20 to April 30, 2020. Random and systemic sampling techniques were used to select 428 study participants. Data were entered and coded in to Epi data version 3.0 and then exported into STATA 14 for analysis. In bivariable logistic regression, variables with a p-value of < 0.25 were included in multivariable logistic regression. Using a 95% confidence interval, variables having a p-value ≤ 0.05 in multivariable logistic regression were declared as statistically significant variables. In this study, a total of 428 study participants were involved with 99.5% response rate. The prevalence of anemia among hypertensive patients was 17.6%, with a 95% CI (14.3-21.5%). Estimated glomerular filtration rate (eGFR) < 90 ml/min (AOR = 2.77, 95% CI 1.56- 4.92)], duration of hypertension (HTN) ≥ 5 years (AOR = 2.37, 95% CI 1.36-4.15), uncontrolled blood pressure (AOR = 1.91, 95% CI 1.08-3.35), and higher pulse pressure (AOR = 1.05 (95% CI 1.02-1.08) were significantly associated with anemia. Nearly one out of five hypertensive patients had anemia. Impaired estimated glomerular filtration rate, duration of HTN, blood pressure status, and pulse pressure were the independent predictors of anemia among hypertensive patients. Screening hemoglobin level at a regular interval is recommended for the hypertensive patients to take an appropriate intervention.

Gender differences in the associations of circulating erythrocytes and hemoglobin with hypertension risk

OBJECTIVE

Studies on associations of erythrocytes parameters with hypertension risk are scarce. We aimed to examine associations of the erythrocytes parameters with the hypertension risk and potential effect modification by gender using data from the China Health and Nutrition Survey.

METHODS

A total of 5419 eligible participants (2468 men, 45.5%) without hypertension at baseline in 2009 were included and followed for a median of 6.1 years. Parameters of erythrocytes and hemoglobin were measured at baseline. Multivariable Cox proportional hazards models were used to estimate the hazard ratio for the associations between these parameters and hypertension risk. Data were collected from 2009 to 2015 and analyzed in 2021.

RESULTS

A total of 1178 incident cases of hypertension were identified during the follow-up. In women, erythrocytes and hemoglobin were positively associated with risk of hypertension, yielding the highest hazard ratio in the third quartile of 1.59 (95% confidence interval, 1.28-1.97, P trend < 0.001) for erythrocytes and in the fourth quartile of 1.64 (95% confidence interval, 1.23-2.17, P trend < 0.001) for hemoglobin compared with their first quartile, respectively. In addition, quartiles of erythrocytes and hemoglobin were not associated with risk of hypertension in men ( P trend > 0.050).

CONCLUSION

Erythrocytes and hemoglobin were associated with an increased risk of hypertension in women, but not in men. Our findings suggest that special attention for the prevention of hypertension should be given to those women with the moderate to high level of circulating erythrocytes and higher level of hemoglobin.

Rheological Abnormalities in Human Erythrocytes Subjected to Oxidative Inflammation

Erythrocytes are oxygen carriers and exposed to redox cycle in oxygenation and deoxygenation of hemoglobin. This indicates that circulating erythrocytes are vulnerable to the oxidative injury occurring under the imbalance of redox homeostasis. In this review article, two topics are presented concerning the human erythrocytes exposed to the oxidative inflammation including septic and sterile conditions. First, we demonstrate rheological derangement of erythrocytes subjected to acute oxidative injury caused by exogenous generators of reactive oxygen species (ROS). Erythrocyte filterability as whole-cell deformability has been estimated by the gravity-based nickel mesh filtration technique in our laboratory and was dramatically impaired in a time-dependent manner after starting exposure to the ROS generators, that is associated with concurrent progression of membrane protein degradation, phospholipid peroxidation, erythrocyte swelling, methemoglobin formation, and oxidative hemolysis. Second, we introduce an impairment of erythrocyte filterability confirmed quantitatively in diabetes mellitus and hypertension of animal models and patients under treatment. Among the cell geometry, internal viscosity, and membrane property as the three major determinants of erythrocyte deformability, erythrocyte membrane alteration is supposed to be the primary cause of this impairment in these lifestyle-related diseases associated with persistent oxidative inflammation. Excessive ROS trigger the inflammatory responses and reduce the erythrocyte membrane fluidity. Oxidative inflammation increasing erythrocyte membrane rigidity underlies the impaired systemic microcirculation, which is observed in diabetic and/or hypertensive patients. On the other hand, elevated internal viscosity caused by sickle hemoglobin polymerization is a primary cause of impaired erythrocyte filterability in sickle cell disease (SCD). However, oxidative inflammation is also involved in the pathophysiology of SCD. The physiologic level of ROS acts as signaling molecules for adaptation to oxidative environment, but the pathological level of ROS induces suicidal erythrocyte death (eryptosis). These findings provide further insight into the ROS-related pathophysiology of many clinical conditions.

Erythrocyte Deformability and Na,K-ATPase Activity in Various Pathophysiological Situations and Their Protection by Selected Nutritional Antioxidants in Humans

The physicochemical and functional properties of erythrocytes are worsened in a variety of diseases. Erythrocyte deformability refers to their ability to adjust their shape according to external forces exerted against them in the circulation. It is influenced by the functionality of the Na,K-ATPase enzyme, which is localized in their membranes. The proposed review is focused on knowledge regarding changes in erythrocyte Na,K-ATPase activity, and their impact on erythrocyte deformability in various pathophysiological situations observed exclusively in human studies, as well as on the potential erytroprotective effects of selected natural nutritional antioxidants. A clear link between the erythrocyte properties and the parameters of oxidative stress was observed. The undesirable consequences of oxidative stress on erythrocyte quality and hemorheology could be at least partially prevented by intake of diverse antioxidants occurring naturally in foodstuffs. Despite intensive research concerning the effect of antioxidants, only a small number of investigations on erythrocyte properties in humans is available in databases. It is worth shifting attention from animal and in vitro experiments and focusing more on antioxidant administration in human studies in order to establish what type of antioxidant, in what concentration, and in which individuals it may provide a beneficial effect on the human organism, by protecting erythrocyte properties.

Can erythrocytes behavior in microcirculation help the understanding the physiopathology and improve prevention and treatment for covid-19?

Low plasma estrogens, vitamin D deficiency, obesity, diabetes, cardiovascular diseases, thromboembolism, and impaired microcirculation are linked to the severity of covid-19. Studies have suggested that these comorbidities also are related to erythrocyte factors linked to increased blood viscosity in microcirculation such as erythrocyte aggregation and erythrocyte deformability. Increased blood viscosity in microcirculation can lead to a decrease in oxygenation and nutrition of tissues. Therefore erythrocyte aggregation and erythrocyte deformability may be involved in covid-19 severity, leading to tissue hypoxia and a decrease of drug concentration in affected organs. If this relationship is demonstrated, erythrocytes factors can be used to monitor treatments for improve microcirculatory fluidity that may decrease covid-19 severity. Lifestyle improvement and treatments such as vitamin D and estrogens supplementation are some possible approaches to improve microcirculation and covid-19 prevention and treatment.

Association between erythrocyte dynamics and vessel remodelling in developmental vascular networks

Sprouting angiogenesis is an essential vascularization mechanism consisting of sprouting and remodelling. The remodelling phase is driven by rearrangements of endothelial cells (ECs) within the post-sprouting vascular plexus. Prior work has uncovered how ECs polarize and migrate in response to flow-induced wall shear stress (WSS). However, the question of how the presence of erythrocytes (widely known as red blood cells (RBCs)) and their impact on haemodynamics affect vascular remodelling remains unanswered. Here, we devise a computational framework to model cellular blood flow in developmental mouse retina. We demonstrate a previously unreported highly heterogeneous distribution of RBCs in primitive vasculature. Furthermore, we report a strong association between vessel regression and RBC hypoperfusion, and identify plasma skimming as the driving mechanism. Live imaging in a developmental zebrafish model confirms this association. Taken together, our results indicate that RBC dynamics are fundamental to establishing the regional WSS differences driving vascular remodelling via their ability to modulate effective viscosity.

Red Blood Cell Morphodynamics: A New Potential Marker in High-Risk Patients

In the last years, a substantial contribution of red blood cells (RBCs) in cardiovascular homeostasis has been evidenced, as these cells are able to regulate cardiovascular function by the export of adenosine triphosphate and nitric oxide as well as to maintain redox balance through a well-developed antioxidant system. Recently a link between high-risk plaque (HRP) features and myocardial ischemia, in the absence of severe lumen stenosis, has been evidenced. Nonobstructive coronary artery disease (nonob CAD) has been associated in fact with a greater 1-year risk of myocardial infarction and all-cause mortality compared with no apparent CAD. This new evidence increases interest in searching new triggers to identify these high-risk patients, in the absence/or on top of traditional hazard markers. In this study, we investigated the existence of any association between RBC morphodynamics and HRP features in individuals with different grades of coronary stenosis detected by coronary computed tomography angiography (CCTA). Ninety-one consecutive individuals who underwent CCTA [33 no CAD; 26 nonobstructive (nonob), and 32 obstructive (ob) CAD] were enrolled. RBC morphodynamic features, i.e., RBC aggregability and deformability, were analyzed by means of Laser Assisted Optical Rotation Cell Analyzer (LoRRca MaxSis). The putative global RBC morphodynamic (RMD) score and the related risk chart, associating the extent of HRP (e.g., the non-calcified plaque volume) with both the RMD score and the max % stenosis were computed. In nonob CAD group only positive correlations between RBC rigidity, osmotic fragility or aggregability and HRP features (plaque necrotic core, fibro-fatty and fibro-fatty plus necrotic core plaque volumes) were highlighted. Interestingly, in this patient cohort three of these RBC morphodynamic features result to be independent predictors of the presence of non-calcified plaque volume in this patients group. The risk chart created shows that only in nonob CAD plaque vulnerability increases according to the score quartile. Findings of this work, by evidencing the association between erythrocyte morphodynamic characteristics assessed by LoRRca and plaque instability in a high-risk cohort of nonob CAD, suggest the use of these blood cell features in the identification of high-risk patients, in the absence of severe coronary stenosis.

Impaired deformability and association with density distribution of erythrocytes in patients with type 2 diabetes mellitus under treatment

BACKGROUND

Disturbed microcirculation is related to diabetic complications, and erythrocyte deformability is a critical factor regulating microcirculation.

OBJECTIVES

To know the relationship between the impaired deformability and density profile in diabetic erythrocytes.

METHODS

We recruited patients with type 2 diabetes (n = 15, diabetic group) and age- and sex-matched non-diabetic subjects (n = 15, control group). Erythrocyte density (ED) profile was obtained by the phthalate ester separation technique. ED distribution was fitted by sigmoidal curve, yielding specific gravity of phthalate ester allowing passage of half erythrocytes population (ED50) and slope factor. Erythrocyte deformability was estimated by our specific filtration technique.

RESULTS

Diabetic group showed significantly (p < 0.001) higher HbA1c and fasting blood glucose concentration. Erythrocyte deformability in diabetic group was impaired as compared with that in control group (p < 0.001) and proportional to HbA1c (p = 0.009). However, ED50 and the slope factor in diabetic group did not differ from respective parameters in control group.

CONCLUSIONS

This study demonstrated that erythrocyte deformability was impaired in diabetic patients even under treatment. HbA1c up to 7.5% is concluded not to alter the erythrocyte density but to impair the deformability, which might be a warning to clinicians for prevention of diabetic complications.

Simultaneous measurement method of erythrocyte sedimentation rate and erythrocyte deformability in resource-limited settings

OBJECTIVE

The individual effects of plasma and red blood cells (RBCs) on the biophysical properties of blood can be monitored by measuring the erythrocyte sedimentation rate (ESR) and RBC deformability simultaneously. However, the previous methods require bulky and expensive facilities (i.e. microscope, high-speed camera, and syringe pump) to deliver blood or capture blood flows.

APPROACH

To resolve these issues, a simple method for sequential measurement of the ESR and RBC deformability is demonstrated by quantifying the cell-free volume (V _CF ), cell-rich volume (V _CR ), and blood volume (V _B ) inside an air-compressed syringe (ACS). A microfluidic device consists of multiple micropillar channels, an inlet, and outlet. After the ACS is filled with air (V _air   =  0.4 ml) and a blood sample (V _B   =  0.6 ml, hematocrit  =  30%) sequentially, the ACS is fitted into the inlet. The cavity inside the ACS is compressed to V _comp   =  0.4 ml after closing the outlet with a stopper. A smartphone camera is employed to capture variations in the V _CF , V _CR , and V _B inside the ACS. The ESR index suggested in this study (ESR _PM ) is obtained by dividing the V _CF (t  =  t ₁) with an elapse of t ₁. By removing the stopper, ΔV _B (ΔV _B   =  V _B [t  =  t ₁]  -  V _B ) is obtained and fitted as a two-term exponential model ([Formula: see text]. As a performance demonstration, the proposed method is employed to detect an ESR-enhanced blood sample, homogeneous hardened blood sample, and heterogeneous blood sample.

MAIN RESULTS

From the experimental results, it is found that the proposed method has the ability to detect various bloods by quantifying the ESR _PM and two coefficients (a, b) simultaneously.

SIGNIFICANCE

In conclusion, the present method can be effectively used to measure the ESR and RBC deformability in resource-limited settings.

Potential Diagnostic Hemorheological Indexes for Chronic Kidney Disease in Patients With Type 2 Diabetes

Many studies have demonstrated that an alteration in hemorheological properties is closely correlated with diabetic microcirculatory diseases. However, most of these studies have been limited to animal studies or used a small number of clinical samples, due to a lack of effective point-of-care (POC) devices to measure such properties within clinical environments. Owing to recent developments in microfluidic technology, several hemorheological POC devices have been designed that allow for the possibility of conducting extensive clinical studies using hemorheological measurements. Here, we reviewed recent clinical studies of diabetic kidney disease (DKD) associated with hemorheological parameters. We found that RBC deformability alone did not show a significant difference according to the degree of DKD, whereas critical shear stress (CSS) was found to be closely related to the ratio of albumin to creatinine and glomerular filtration rate. We also reviewed studies that alteration of hemorheological properties are associated with the development of DKD, which showed that CSS could be considered as a potential index to diagnose other diabetic complications as well as DKD.

Biological activities of (-)-epicatechin and (-)-epicatechin-containing foods: Focus on cardiovascular and neuropsychological health

Recent studies have suggested that certain (-)-epicatechin-containing foods have a blood pressure-lowering capacity. The mechanisms underlying (-)-epicatechin action may help prevent oxidative damage and endothelial dysfunction, which have both been associated with hypertension and certain brain disorders. Moreover, (-)-epicatechin has been shown to modify metabolic profile, blood's rheological properties, and to cross the blood-brain barrier. Thus, (-)-epicatechin causes multiple actions that may provide unique synergy beneficial for cardiovascular and neuropsychological health. This review summarises the current knowledge on the biological actions of (-)-epicatechin, related to cardiovascular and brain functions, which may play a remarkable role in human health and longevity.

The role of red blood cell deformability and Na,K-ATPase function in selected risk factors of cardiovascular diseases in humans: focus on hypertension, diabetes mellitus and hypercholesterolemia

Deformability of red blood cells (RBC) is the ability of RBC to change their shape in order to pass through narrow capillaries in circulation. Deterioration in deformability of RBC contributes to alterations in microcirculatory blood flow and delivery of oxygen to tissues. Several factors are responsible for maintenance of RBC deformability. One of them is the Na,K-ATPase known as crucial enzyme in maintenance of intracellular ionic homeostasis affecting thus regulation of cellular volume and consequently RBC deformability. Decreased deformability of RBC has been found to be the marker of adverse outcomes in cardiovascular diseases (CVD) and the presence of cardiovascular risk factors influences rheological properties of the blood. This review summarizes knowledge concerning the RBC deformability in connection with selected risk factors of CVD, including hypertension, hyperlipidemia, and diabetes mellitus, based exclusively on papers from human studies. We attempted to provide an update on important issues regarding the role of Na,K-ATPase in RBC deformability. In patients suffering from hypertension as well as diabetes mellitus the Na,K-ATPase appears to be responsible for the changes leading to alterations in RBC deformability. The triggering factor for changes of RBC deformability during hypercholesterolemia seems to be the increased content of cholesterol in erythrocyte membranes.

Early Erythrolysis in the Hematoma After Experimental Intracerebral Hemorrhage

Erythrolysis occurs in the clot after intracerebral hemorrhage (ICH), and the release of hemoglobin causes brain injury, but it is unclear when such lysis occurs. The present study examined early erythrolysis in rats. ICH rats had an intracaudate injection of 100 μl autologous blood, and sham rats had a needle insertion. All rats had T2 and T2* magnetic response imaging (MRI) scanning, and brains were used for histology and CD163 (a hemoglobin scavenger receptor) and DARPP-32 (a neuronal marker) immunohistochemistry. There was marked heterogeneity within the hematoma on T2* MRI, with a hyperintense or isointense core and a hypointense periphery. Hematoxylin and eosin staining in the same animals showed significant erythrolysis in the core with the formation of erythrocyte ghosts. The degree of erythrolysis correlated with the severity of perihematomal neuronal loss. Perihematomal CD163 was increased by day 1 after ICH and may be involved in clearing hemoglobin caused by early hemolysis. Furthermore, ICH resulted in more severe erythrolysis, neuronal loss, and perihematomal CD163 upregulation in spontaneously hypertensive rats compared to Wistar-Kyoto rats. In conclusion, T2*MRI-detectable early erythrolysis occurred in the clot after ICH and activated CD163. Hypertension is associated with enhanced erythrolysis in the hematoma.