Effects of Plant Sterols or β-Cryptoxanthin at Physiological Serum Concentrations on Suicidal Erythrocyte Death

Abstract

The eryptotic and hemolytic effects of a phytosterol (PS) mixture (β-sitosterol, campesterol, stigmasterol) or β-cryptoxanthin (β-Cx) at physiological serum concentration and their effect against oxidative stress induced by tert-butylhydroperoxide (tBOOH) (75 and 300 μM) were evaluated. β-Cryptoxanthin produced an increase in eryptotic cells, cell volume, hemolysis, and glutathione depletion (GSH) without ROS overproduction and intracellular Ca influx. Co-incubation of both bioactive compounds protected against β-Cx-induced eryptosis. Under tBOOH stress, PS prevented eryptosis, reducing Ca influx, ROS overproduction and GSH depletion at 75 μM, and hemolysis at both tBOOH concentrations. β-Cryptoxanthin showed no cytoprotective effect. Co-incubation with both bioactive compounds completely prevented hemolysis and partially prevented eryptosis as well as GSH depletion induced by β-Cx plus tBOOH. Phytosterols at physiological serum concentrations help to prevent pro-eryptotic and hemolytic effects and are promising candidate compounds for ameliorating eryptosis-associated diseases.

Increased eryptosis in smokers is associated with the antioxidant status and C-reactive protein levels

“…Furthermore, these authors indicated the alteration of erythrocytes morphology with an increase in stomatocytes (increased volume potentially linked with hemolysis) and spherocytes (associated with reduced pliability and osmotic fragility) (Sikdar et al, 2017). Moreover, we have previously reported ex vivo that tert-butylhydroperoxide induced oxidative stress in erythrocytes resulted in two cell populations, with low size (FSC < 20, associated with eryptosis) and big size (FSC > 80, associated with a preliminary step of hemolysis) (Álvarez-Sala et al, 2018). In line with this, we have shown in the present study a marginal increase (non significant trend) of FSC (higher cell volume) in erythrocytes from smokers to be possibly ascribed to the presence of high quantities of stomatocytes.…”

“…On the other hand, according to the geo mean values derived from FSC (Fig. 1B), a growing trend of cell volume was observed in smokers compared to non-smokers (554.30 ± 32.31 vs. 536.30 ± 30.76 tvalue: 1.8260; p-value: 0.0756), possibly due to changes in morphology associated with preliminary steps of hemolysis (Álvarez-Sala et al, 2018). Representative histograms of Annexin V-binding and FSC of erythrocytes from one non-smoker and one smoker volunteer are also shown ( Fig.…”

“…GSH content was determined with 1 μM (final concentration) of 5chloromethylfluorescein diacetate (Green CMFDA) (Abcam, Cambridge, UK) according to Álvarez-Sala et al (2018). The CMFDA was added to a RBCs sample adjusted at 2.0 × 10 6 cells/mL with PBS.…”

“…These events can be linked with atherosclerosis and cardiovascular disease since eryptotic erythrocytes adhere to endothelial cells of the vascular wall by interaction of phosphatidylserine exposed at the membrane surface with endothelial CXCL16 (Borst et al, 2012;Silva-Herdade et al, 2016), triggering blood clotting and thrombosis (Andrews and Low, 1999), thus interfering with microcirculation (Closse et al, 1999;Lang et al, 2013;Briglia et al, 2017). In addition, increase in ROS, hemolysis, lipid peroxidation, PGE-2 release and decrease in GSH are common features in oxidative stress-induced eryptosis (Bissinger et al, 2014;Mischitelli et al, 2016aMischitelli et al, , 2016bTesoriere et al, 2014;Álvarez-Sala et al, 2018).…”

Oxidative stress, eryptosis and anemia: a pivotal mechanistic nexus in systemic diseases

“…The process of eryptosis is characterized by cell membrane scrambling leading to breakdown of the cell membrane asymmetry and translocation of phosphatidylserine from the interior to the cell membrane surface . The cell membrane scrambling is typically paralleled by erythrocyte shrinkage and by the formation of blebs on the erythrocyte surface.…”