Red Blood Cell Membrane Cholesterol Research Articles

Bisphenol S remodels red blood cell membrane lipids by altering plasma lipid levels, causing the risk of venous thrombosis in SD rats and zebrafish embryos

Bisphenol S (BPS) is a raw material that is used extensively in various manufacturing processes but possesses a high detection rate in human red blood cells (RBCs). Accordingly, BPS is a potential toxicant in disturbing the function of RBCs and causing RBC-related diseases. To date, the effects and mechanisms of BPS-induced RBC-related diseases have not been elucidated. Here, using different models, including rats, zebrafish embryos and RBCs, the underlying mechanism of RBC-related diseases induced by BPS was explored. The accumulation of BPS in tissue was colon > kidney > liver > plasma > testicle > heart > brain in SD rats orally administered BPS (10 and 50 mg/kg bw/day) for 32 days, which was similar in both 10 mg/kg bw/day and 50 mg/kg bw/day group. Rats given BPS orally developed hyperlipidemia and increased RBC membrane cholesterol, as well as changes in RBC morphology and function. Moreover, BPS at the concentrations measured in rats plasma caused oxidative stress and phosphatidylserine exposure in vitro RBCs. These combined factors led to RBC aggregation in blood and an increasing in the number of RBCs in the blood vessels of the liver in rats. The dynamic visual observation of RBCs in vein vessels of zebrafish embryos exposed to BPS at 0, 1, 10 and 100 μg/L further found that the flow of RBCs in the tail vein is slow or even immobile, posing the risk of venous thrombosis. The present study provides new insight into the links between environmental pollutants and venous thrombosis.

Red Blood Cell Membrane Cholesterol May Be a Key Regulator of Sickle Cell Disease Microvascular Complications.

Cell membrane lipid composition, especially cholesterol, affects many functions of embedded enzymes, transporters and receptors in red blood cells (RBC). High membrane cholesterol content affects the RBCs' main vital function, O2 and CO2 transport and delivery, with consequences on peripheral tissue physiology and pathology. A high degree of deformability of RBCs is required to accommodate the size of micro-vessels with diameters significantly lower than RBCs. The potential therapeutic role of high-density lipoproteins (HDL) in the removal of cholesterol and its activity regarding maintenance of an optimal concentration of RBC membrane cholesterol have not been well investigated. On the contrary, the focus for HDL research has mainly been on the clearance of cholesterol accumulated in atherosclerotic macrophages and plaques. Since all interventions aiming at decreasing cardiovascular diseases by increasing the plasma level of HDL cholesterol have failed so far in large outcome studies, we reviewed the potential role of HDL to remove excess membrane cholesterol from RBC, especially in sickle cell disease (SCD). Indeed, abundant literature supports a consistent decrease in cholesterol transported by all plasma lipoproteins in SCD, in addition to HDL, low- (LDL) and very low-density lipoproteins (VLDL). Unexpectedly, these decreases in plasma were associated with an increase in RBC membrane cholesterol. The concentration and activity of the main enzyme involved in the removal of cholesterol and generation of large HDL particles-lecithin cholesterol ester transferase (LCAT)-are also significantly decreased in SCD. These observations might partially explain the decrease in RBC deformability, diminished gas exchange and tendency of RBCs to aggregate in SCD. We showed that incubation of RBC from SCD patients with human HDL or the HDL-mimetic peptide Fx5A improves the impaired RBC deformability and decreases intracellular reactive oxygen species levels. We propose that the main physiological role of HDL is to regulate the cholesterol/phospholipid ratio (C/PL), which is fundamental to the transport of oxygen and its delivery to peripheral tissues.

Discerning Membrane Steady-State Oxygen Flux by Monte Carlo Markov Chain Modeling.

Molecular oxygen (O2) permeability coefficients for lipid bilayers have previously been estimated using both electron paramagnetic resonance (EPR) oximetry and molecular dynamics simulation data. Yet, neither technique captures the fluxes that exist physiologically. Here, the dynamic steady state is modeled using a stochastic approach built on atomic resolution molecular dynamics simulation data. A Monte Carlo Markov chain technique is used to examine membrane-level fluxes of oxygen in lipid-water systems. At steady state, the concentration of oxygen is found to be higher inside the model membranes than in surrounding water, consistent with the known favorable partitioning of O2 toward the lipid phase. Pure phospholipid 1-palmitoyl,2-oleoyl-phosphatidylcholine (POPC) bilayers accrue ~40% more O2 molecules at steady state than POPC/cholesterol bilayers (1:1 molecular ratio) mimicking the red blood cell membrane. Steady-state levels of oxygen were reached inside both bilayer types within the same timeframe, but depletion of oxygen from the bilayer interior occurred 17% faster for POPC than for POPC/cholesterol. Likewise, first-order rate constants estimated for accrual to steady state were the same for POPC and POPC/cholesterol, at 190μs-1, while first-order rate constants for depletion of the accrued O2 from the bilayers differed, at 95μs-1 for POPC and 81μs-1 for POPC/cholesterol (lower by 15%). These results are consistent with prior experiments in red blood cells (RBCs) with varying membrane cholesterol content, in which additional cholesterol slowed oxygen uptake and release. Further work is needed to understand whether differences in RBC membrane cholesterol content would affect the delivery of oxygen to tissues.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Involvement of potassium channel in AQP1-mediated water and gas transport in erythrocytes

Elevated plasma cholesterol affects nearly 100 million Americans, a third of the US population, resulting in devastating health consequences and nearly one million deaths annually. Although the long-term effect of elevated plasma cholesterol is known for its accretion in arterial walls, little was understood of its immediate effects until recently (Jena and Lee, 2010). Cholesterol in blood plasma is known to rapidly enter and incorporate into the red blood cell (RBC) plasma membrane (Tall, 1993; Glomset et al., 1995; Ishizake et al., 1994). As early as the 1970s, it was demonstrated in human studies that blood plasma and RBC membrane cholesterol levels are inversely associated with the transmembrane O2 diffusion rate of RBC (Steinbach et al., 1974): as cholesterol levels in the blood plasma and consequently in the RBC membrane decrease, O2 diffusion in RBC increases (Steinbach et al., 1974; Menchaca et al., 2004). Then in 2010 (Jena and Lee, 2010), we reported for the first time that the immediate effect of elevated plasma cholesterol is dysfunction of active water and CO2 transport via the AQP1 channel through the RBC membrane. The effect of the phospholipase A2 (PLA2) inhibitor ONO-RS-082 (ONO) on ameliorating the detrimental effects of cholesterol was further demonstrated from that study (Jena and Lee, 2010). In the past decade, the tetradecapeptide wasp venom mastoparan, GTP, the GTP-binding heterotrimeric Gαi/ Gαo proteins, vH +-ATPase, PLA2, the K+ and Cl– channels, and aquaporins (Abu-Hamdah et al., 2004), have been implicated in the gating of water into secretory vesicles. A similar mechanism operating at the RBC membrane is therefore hypothesized. Gαi3 has been implicated in various tissues to regulate both K+ and Cl– ion channels at the plasma membrane (Delport et al., 1997; Knepper and Inoue, 1994, 1997). PLA2 has also been found to regulate both K+ and Cl– ion channels. Since Gαi3 and PLA2 are present at the RBC membrane (Mukherjee and Maxfield, 2004; Hillman et al., 2005), I hypothesize the involvement of both Gαi3 and PLA2 in the regulation of AQP1 activity. Furthermore, since K+ and Cl– ion channels are present at the RBC membrane (Hillman et al., 2005), the involvement of Gαi3 in the regulation of K+ and Cl– ion channels at the RBC membrane and its possible implication for AQP1-mediated water entry were investigated. Results from my studies demonstrate that K+ and Cl– ion channels are associated with AQP1 at the RBC membrane, and that the K+ channel inhibitor Glyburide currently used in treating diabetes reverses the detrimental effects of cholesterol on RBC function. Involvement of potassium channel in AQP1-mediated water and gas transport in erythrocytes Siddhartha G. Jena*

The effects of membrane cholesterol and simvastatin on red blood cell deformability and ATP release

It is known that deformation of red blood cells (RBCs) is linked to ATP release from the cells. Further, membrane cholesterol has been shown to alter properties of the cell membrane such as fluidity and bending stiffness. Membrane cholesterol content is increased in some cardiovascular diseases, for example, in individuals with acute coronary syndromes and chronic stable angina, and therefore, because of the potential clinical relevance, we investigated the influence of altered RBC membrane cholesterol levels on ATP release. Because of the correlation between statins and reduced membrane cholesterol in vivo, we also investigated the effects of simvastatin on RBC deformation and ATP release. We found that reducing membrane cholesterol increases cell deformability and ATP release. We also found that simvastatin increases deformability by acting directly on the membrane in the absence of the liver, and that ATP release was increased for cells with enriched cholesterol after treatment with simvastatin.

Determination of RBC membrane and serum lipid composition in Trinidadian type II diabetics with and without nephropathy.

The rheological properties of erythrocytes are impaired in diabetes mellitus, especially because of changes in their membrane lipid composition.The aim of this study was to determine and examine the relationship between red blood cell (RBC) membrane and serum lipid composition in type II diabetes subjects with and without nephropathy. Trinidadian subjects aged 18-65 years were recruited for the study regardless of gender and ethnicity. Fasting blood samples were collected from 60 subjects of whom 20 were healthy individuals, 20 had type II diabetes without complications, and 20 were type II diabetics with nephropathy. Weight, height, waist/hip ratio, and blood pressure were recorded. All the blood samples were analysed to determine the serum lipid concentration, membrane lipid composition and plasma glucose concentration. The body mass index and the systolic blood pressure of the diabetics (28.17 +/- 4.98 kg/m2, 153.21 +/- 22.10 mmHg) and those with nephropathy (25.87 +/- 4.68, 158.60 +/- 22.49 mmHg) were higher when compared with controls (24.67 +/- 5.18, 119.15 +/- 13.03 mmHg). The diabetic (175.89 +/- 102.73 microg/mgprotein) and diabetic nephropathy (358.80 +/- 262.66) subjects showed significantly higher levels of RBC membrane cholesterol compared with controls (132.27 +/- 66.47). The membrane phospholipids, protein and Na+/K+ATPase concentrations were altered in diabetics and diabetic nephropathy patients when compared with controls. The trends of increased serum cholesterol and decreased high-density lipoprotein in diabetics and diabetic nephropathy patients were noted as compared with controls but they are not significant as expected. The low-density lipoprotein cholesterol was significantly higher in diabetics when compared with diabetic nephropathy and control subjects. Our data suggest that there is a relationship between RBC membrane and serum lipid composition in subjects with type II diabetes with and without nephropathy. This relationship shows that diet and lifestyle plays a significant role in the alterations of the lipids both in serum and RBC membrane. The membrane and serum lipid composition may be used as possible indicators for type II diabetic patients with and without nephropathy to control their diet in the beginning stages to prevent them from further complications.

Cyclosporin A-Associated Changes in Red Blood Cell Membrane Composition, Deformability, Blood and Plasma Viscosity in Rats

Most of the studies concerning the effects of cyclosporin A (Cs A) on red blood cell (RBC) rheology were carried out in human transplant recipients who may still have residual insufficiency and concomitant administration of other immunosuppressive and antihypertensive drugs. The aim of this study is to evaluate the effects of Cs A on red cell rheology and membrane composition in nontransplant healthy rats. Female Wistar albino rats were divided into two groups of 10 animals each. Rats received 10 mg/kg Cs A, i.p. or saline for 4 weeks. Cs A administration significantly increased the RBC deformability, and plasma and blood viscosity (p < 0.001, p < 0.01 and p < 0.01, respectively). Cs A administration to the rats increased RBC membrane cholesterol (CHO) levels and the CHO/phospholipid (PL) ratio significantly (p < 0.01 and p < 0.05, respectively) but did not change RBC membrane proteins and membrane PL levels. These results suggest that Cs A changes the rheological functions of RBC and lipid content of RBC membrane in healthy rats and thereby it may play an important role in the regulation of microcirculation.

Hypothalamic digoxin and hypomagnesemia in human pre‐eclampsic toxemia, cortical venous thrombosis, and postpartum psychosis

AbstractThe isoprenoid pathway produces three key metabolites—digoxin (membrane sodium‐potassium ATPase inhibitor and regulator of neurotransmitter transport), dolichol (regulates N‐glycosylation of proteins), and ubiquinone (free radical scavenger). The pathway was assessed in patients with pre‐eclampsic toxaemia, cortical venous thrombosis, and postpartum psychosis. It was also studied for comparison in patients with right hemispheric, left hemispheric, and bihemispheric dominance. The results of the study showed that the isoprenoid pathway was upregulated with increased digoxin synthesis in all the three groups of patients. There was also a reduction in red blood cell (RBC) membrane Na+–K+ ATPase activity and serum magnesium levels. There was an increase in serum tryptophan catabolites and reduction in tyrosine catabolites. The serum dolichol and glycoconjugate levels were increased and lysosomal stability reduced with increased plasma lysosomal enzymes in all the three groups. The serum ubiquinone levels were low, and RBC free radical parameters increased. The RBC membrane cholesterol: phospholipid ratio was increased, and glycoconjugate was reduced in the membrane of these patients. This pattern correlated with those in right hemispheric dominance. The isoprenoid pathway and hypothalamic digoxin may thus play a crucial role in the pathogenesis of CVT, PET, and postpartum psychosis. J. Trace Elem. Exp. Med. 15:171–190 2002. © 2002 Wiley‐Liss, Inc.

Effect of plasma cholesterol on red blood cell oxygen transport.

1. Oxygen (O2) transfer from the blood to tissues is a function of the red blood cell (RBC) O2 saturation (SO2), the plasma O2 content being negligible. Under conditions of increased tissue O2 demand, the SO2 of arterial blood does not change appreciably (97%); however, the SO2 of mixed venous blood, equal to that of the perfused tissues, can go as low as 20%. 2. Tissue O2 availability is limited by the exposure time to a RBC, which decreases under conditions of maximum stress (< 1 s). If the O2 unloading time was to increase significantly, because of a decrease in the RBC diffusion constant or an increase in the RBC membrane thickness, the RBC O2 unloading time would exceed tissue (e.g. cardiac) transit time and O2 transfer would be impaired. 3. Cholesterol constitutes the non-polar, hydrophobic lipid of the enveloping layer of the RBC membrane. As the cholesterol content of the RBC increases, the fluidity of the membrane decreases and the lipid shell stiffens. 4. Early studies demonstrated that high blood cholesterol concentrations were associated with reduced blood O2 transport; in essence, the haemoglobin dissociation curve was shifted to the left. 5. Current investigations have shown that the cholesterol RBC membrane barrier to O2 diffusion delayed O2 entry into the RBC during saturation and delayed O2 release from the RBC during desaturation. In an analysis of 93 patients divided by their cholesterol concentration into five groups, the percentage change in blood O2 diffusion was inversely proportional to the cholesterol concentration. 6. The RBC membrane cholesterol is in equilibrium with the plasma cholesterol concentration. It stands to reason that as the plasma cholesterol increases, the RBC membrane becomes impaired and O2 transport is reduced. 7. The implications of this new perspective on O2 transport include the ability to increase tissue oxygenation by lowering plasma cholesterol.

Decreased blood oxygen diffusion in hypercholesterolemia

Background: Improvement of angina pectoris symptoms after cholesterol lowering has raised questions as to the underlying mechanisms. Methods: Rabbit experiment: We compared arterial blood samples from New Zealand White cholesterol-supplemented rabbits (n = 6) with nonsupplemented rabbit samples (n = 4) in a closed-loop circulation diffusion system. The pH and partial pressures of oxygen (pO2) and carbon dioxide (pCO2) were measured continuously. The samples were first oxygen (O2) saturated (pO2, 160 mm Hg; pCO2, 4 mm Hg) and then desaturated in 100% nitrogen. Cholesterol levels were determined in whole blood, plasma (P Chol), red blood cells (RBCs), and RBC membranes. Human experiment: We exposed quadruple desaturated venous blood samples (n = 4) with P Chol levels of 87 to 400 mg/dL in a gas exchanger to capillary gas conditions (pO2, 23 mm Hg; pCO2, 46 mm Hg). After 15 minutes we performed blood gas analyses and compared our results to baseline values. Results: In the rabbit experiment the cholesterol-supplemented group as compared to the control group showed higher plasma pO2 levels during the saturation phase and lower plasma pO2 levels during the desaturation phase. It also had a markedly increased RBC membrane cholesterol content: 121 ± 3 (standard error of the mean [SEM]) mg/dL versus 22 ± 1.7 mg/dL in the control group (P <.05). This barrier to RBC membrane O2 diffusion caused delayed O2 entry into the RBCs during saturation, with a higher plasma pO2, and delayed O2 release from the RBCs during desaturation, with a lower plasma pO2. In the human experiment the P Chol level was inversely correlated with the percentage change of O2 content in milliliters of O2 per deciliter of blood (P <.05). Conclusions: Increased RBC membrane cholesterol in hypercholesterolemia appears to decrease the transmembrane O2 diffusion rate. (Surgery 1998;124:692-8.)

Improved Red Blood Cell Preservation Correlates With Decreased Loss of Bands 3, 4.1, Acetylcholinestrase, and Lipids in Microvesicles

In earlier studies we have shown that a final concentration of 0.69% glycerol in blood mixed with an experimental additive solution, EAS 25, improves the in vitro quality and in vivo survival of red blood cells (RBCs). The objective of this study was to determine if the better preservation of RBCs in EAS 25 is correlated with the improved maintenance of membrane lipids and proteins and decreased vesiculation. Split units of RBCs were stored in Adsol or EAS 25 (mmol/L: adenine 2/2, dextrose 122/110, mannitol 42/55, glycerol 0/150, NaCl 154/50). After 12 weeks storage, RBC and microvesicle membranes were analyzed for cholesterol, phospholipid, diphenyl hexatriene fluorescence anisotropy, and acetylcholinesterase (AchE) activity. Bands 3 and 4.1 were identified in the microvesicle membranes by immunoblotting. The RBC membrane cholesterol, phospholipids, and AchE remained higher in EAS 25 than in Adsol (P < .001). Vesicle membrane lipids and AchE in EAS 25 were significantly less than in Adsol (P < .001). The fluidity of stored cells in both the solutions was greater than the prestorage samples. Immunoblotting analyses showed that bands 3 and 4.1 were greatly reduced in the microvesicle membranes shed by the RBCs stored in EAS 25 compared with those formed in Adsol.

Studies in Red Blood Cell Preservation 2. Comparison of Vesicle Formation, Morphology, and Membrane Lipids during Storage in AS‐1 and CPDA‐1

The changes in morphology, the quantitative changes in membrane lipids and the shedding of exocytic vesicles by red blood cells (RBC) stored for 42 and 56 days in AS-1 and CPDA-1 were compared. RBC stored in AS-1 shed significantly less vesicle membrane cholesterol, phospholipid and protein and maintained better morphology scores. RBC membrane cholesterol remained higher after 56 days in AS-1 than in CPDA-1. The data suggest that during the first weeks of storage cholesterol is lost from the RBC membrane followed by a larger release of phospholipids accompanied by alterations in the phosphoinositides. The shedding of exocytic vesicles appears to be secondary to the changes in morphology resulting from the perturbation of the membrane lipids.

Studies in Red Blood Cell Preservation - 2. Comparison of Vesicle Formation, Morphology, and Membrane Lipids during Storage in AS-1 and CPDA-1

The changes in morphology, the quantitative changes in membrane lipids and the shedding of exocytic vesicles by red blood cells (RBC) stored for 42 and 56 days in AS-1 and CPDA-1 were compared. RBC stored in AS-1 shed significantly less vesicle membrane cholesterol, phospholipid and protein and maintained better morphology scores. RBC membrane cholesterol remained higher after 56 days in AS-1 than in CPDA-1. The data suggest that during the first weeks of storage cholesterol is lost from the RBC membrane followed by a larger release of phospholipids accompanied by alterations in the phosphoinositides. The shedding of exocytic vesicles appears to be secondary to the changes in morphology resulting from the perturbation of the membrane lipids.

Influences of Diet and Postnatal Age on the Lipid Composition of Red Blood Cell Membrane in Newborn Infants

The fatty acid and cholesterol contents of tissue membranes are determinants of their stability and functionality. This study was designed to evaluate the influences of diet and postnatal age on the polyunsaturated fatty acid (PUFA) composition of erythrocyte membrane phospholipid fractions and on the red blood cell membrane cholesterol and phosphorus contents in newborn infants during the 1st month of life. A group of infants was fed on human milk and another group on adapted milk formula. Blood samples were obtained at birth, from cord blood, and at 7 and 30 days of age. Long-chain w6 PUFA declined with advancing age in all membrane phosphoglycerides and sphingomyelin (SM) in those infants fed formula. w6 PUFA also decreased in phosphatidylcholine (PC) and phosphatidylserine (PS) in infants fed human milk and were maintained constant in phosphatidylethanolamine (PE) and SM. w3 PUFA were less affected by postnatal age. PE and SM showed significantly higher percentages of w6 and w3 long-chain PUFA in infants fed human milk than in those fed formula. Membrane cholesterol content increased in all infants from birth to 1 month of life but phosphorus levels were unaffected by diet and postnatal age. These results suggest that diets with a low content of long-chain PUFA, such as adapted cow's milk formulas, may induce changes in membrane functionality and that incorporation of PUFA to the diet in amounts similar to those found in human milk should be considered at least in early life.

Membrane lipid composition of red blood cells in liver disease: regression of spur cell anaemia after infusion of polyunsaturated phosphatidylcholine.

The morphology of red blood cells was studied in 30 patients with severe liver cirrhosis, in 10 patients with extrahepatic jaundice, and in 10 control subjects. In all the patients with extrahepatic jaundice more than 30% of red blood cells were target cells with increased resistance to osmotic lysis. In 12 patients with liver cirrhosis more than 30% of red blood cells were spur cells. The cholesterol: phospholipids (C/PL) molar ratio was 0.89 in target cells, 1.33 in spur cells, and 0.74 in normal red blood cells. The red blood cell membrane cholesterol and phospholipids exchanged with plasma lipoproteins, the lipid composition of which was studied in eight patients with spur cells; the free cholesterol: phospholipid (FC/PL) molar ratio was 0.33 (0.16 in the controls) in high density lipoproteins (HDL) and 1.40 (0.82 in the controls) in low density lipoproteins (LDL); in these patients the polyunsaturated fatty acid content was low in both phospholipids and cholesterol esters of lipoproteins. The irregular folds of the spur cells regressed when polyunsaturated lecithin was infused (2 g daily for five days) in eight patients with spur cell anaemia; the infusions decreased both C/PL ratio in RC to 0.88 and the concentration of unconjugated bilirubin (104.3 to 82.0 mumol/l (6.1 to 4.8 mg%)), whereas the activity of the plasma lecithin:cholesterol acyltransferase (LCAT) increased from 31.2 to 54.4 mumol/l/h. Polyunsaturated fatty acid content of RC lecithin increased after the infusion as it did in HDL, the FC/PL ratio of which decreased to 0.23.

Changes in the red blood cell membrane in protein-calorie malnutrition1–3

Ten children with protein-calorie malnutrition (five with kwashiorkor, three with marasmus, and two with marasmic-kwashiorkor) were studied at hospital admission and during recovery for evidence of changes in red blood cell lipids, osmotic fragility, and chromium survival. On admission, the children had significantly higher-than-normal red blood cell membrane cholesterol and phospholipid, and an elevated cholesterol:phospholipid ratio. Both red blood cell osmotic fragility and red cell survivals were depressed. These measurements returned to normal limits with recovery.