Stimulation of Erythrocyte Membrane Blebbing by Naproxen Sodium

Hemocompatibility studies in nanotoxicology: Hemolysis or eryptosis? (A review)

Hemocompatibility evaluation is an important step in nanotoxicological studies. It is generally accepted that nanomaterials promote lysis of erythrocytes, blood clotting, alter phagocytosis, and upregulate pro-inflammatory cytokines. However, there are no standardized guidelines for testing nanomaterials hemocompatibility despite the fact that nanomaterials enter the bloodstream and interact with blood cells. In this review, the current knowledge on the ability of nanomaterials to induce distinct cell death modalities of erythrocytes is highlighted primarily focusing on hemolysis and eryptosis. This review aims to summarize the molecular mechanisms underlying erythrotoxicity of nanomaterials and critically compare the sensitivity and efficiency of hemolysis or eryptosis assays for nanomaterials blood compatibility testing. The list of eryptosis-inducing nanomaterials is growing, but it is still difficult to generalize how physico-chemical properties of nanoparticles affect eryptosis degree and molecular mechanisms involved. Thus, another aim of this review is to raise the awareness of eryptosis as a nanotoxicological tool to encourage the corresponding studies. It is worthwhile to consider adding eryptosis to in vitro nanomaterials hemocompatibility testing protocols and guidelines.

Apoptosis and eryptosis: similarities and differences

Eryptosis is a regulated cell death (RCD) of mature erythrocytes initially described as a counterpart of apoptosis for enucleated cells. However, over the recent years, a growing number of studies have emphasized certain differences between both cell death modalities. In this review paper, we underline the hallmarks of eryptosis and apoptosis and highlight resemblances and dissimilarities between both RCDs. We summarize and critically discuss differences in the impact of caspase-3, Ca2+ signaling, ROS signaling pathways, opposing roles of casein kinase 1α, protein kinase C, Janus kinase 3, cyclin-dependent kinase 4, and AMP-activated protein kinase to highlight a certain degree of divergence between apoptosis and eryptosis. This review emphasizes the crucial importance of further studies that focus on deepening our knowledge of cell death machinery and identifying novel differences between cell death of nucleated and enucleated cells. This might provide evidence that erythrocytes can be defined as viable entities capable of programmed cell destruction. Additionally, the revealed cell type-specific patterns in cell death can facilitate the development of cell death-modulating therapeutic agents.

Casein kinase 1α mediates eryptosis: a review

Eryptosis is a coordinated non-lytic cell death of erythrocytes characterized by cell shrinkage, cell membrane scrambling, Ca²⁺ influx, ceramide accumulation, oxidative stress, activation of calpain and caspases. Physiologically, it aims at removing damaged or aged erythrocytes from circulation. A plethora of diseases are associated with enhanced eryptosis, including metabolic diseases, cardiovascular pathology, renal and hepatic diseases, hematological disorders, systemic autoimmune pathology, and cancer. This makes eryptosis and eryptosis-regulating signaling pathways a target for therapeutic interventions. This review highlights the eryptotic signaling machinery containing several protein kinases and its small molecular inhibitors with a special emphasis on casein kinase 1α (CK1α), a serine/threonine protein kinase with a broad spectrum of activity. In this review article, we provide a critical analysis of the regulatory role of CK1α in eryptosis, highlight triggers of CK1α-mediated suicidal death of red blood cells, cover the knowledge gaps in understanding CK1α-driven eryptosis and discover the opportunity of CK1α-targeted pharmacological modulation of eryptosis. Moreover, we discuss the directions of future research focusing on uncovering crosstalks between CK1α and other eryptosis-regulating kinases and pathways.

Induction of Erythrocyte Membrane Blebbing by Methotrexate-Induced Oxidative Stress

Methotrexate (MTX) is a common chemotherapeutical agent and folate antagonist with reported apoptotic activity in nucleated cells. The presented research work was planned to investigate the eryptotic effects of methotrexate after the exposure of erythrocytes to therapeutical doses (10–15 μM) of methotrexate. Eryptosis and the role of calcium in the stimulation of membrane blebbing were evaluated through the determination of mean cell volume. Oxidative stress induced by methotrexate (10–15 μM) was determined by antioxidative enzyme activities. Cytotoxic activity against human erythrocytes was examined through hemolysis assay. Exposure of erythrocytes to methotrexate results in significant reduction of superoxide dismutase, catalase, and superoxide dismutase activities at 10 and 15 μM in comparison to the untreated cells. Erythrocytes mean cell volume (MCV) was increased after 48 hours exposure of erythrocytes to methotrexate (10 μM). Significantly increased hemolysis percentage was observed at 10 μM after 48 hours incubation of erythrocytes with methotrexate. The results of the study suggested that the therapeutical doses (10–15 μM) of methotrexate may lead to increase in eryptotic and hemolytic activity of erythrocytes through free radical generation and subsequent calcium entry.

Stimulation of Erythrocyte Membrane Blebbing by Bifenthrin Induced Oxidative Stress

Background

Bifenthrin is an insecticide and anti-estrogenic compound primarily used to control residential pests by depolarizing sodium gated voltage channels in the nervous system. Eryptosis, the suicidal death of erythrocytes, featured by PS exposure, membrane blebbing and cell shrinkage. Anemia is an outcome of uncontrolled eryptosis.

Research Design

In this study, erythrocytes were treated with different concentrations (.5-1-1.5 μM) of bifenthrin over a period of 48 hours. In order to investigate the oxidative stress induced by bifenthrin, catalase, superoxide dismutase, and glutathione peroxidase activities were investigated.

Results

Obtained data indicated the decrease in the enzymes (superoxide dismutase, glutathione peroxidase, and catalase) activities in bifenthrin treated cells at 1 μM concentration. In addition, measurement of cell size and confirmation of the role of calcium in the stimulation of the eryptotic activity of bifenthrin were performed. A significant increase in mean cell volume was found in the presence of bifenthrin and a decrease in mean cell volume in the presence of calcium channel blocker was observed. Similarly, there was also a significant increase in the percentage of hemolysis indicating the necrotic activity of bifenthrin.

Conclusions

It is concluded that the indicated doses of bifenthrin triggered oxidative stress which may lead to early cell death by eryptosis and hemolysis.

Induction of Erythrocyte Shrinkage by Omeprazole

Omeprazole, a proton pump inhibitor blocks the H⁺/K⁺-ATPase channels of gastric parietal cells. It is used for the treatment of peptic ulcer. Prolonged use of omeprazole may involve in inducing anemia. The key marker of eryptosis includes membrane blebbing, cell shrinkage and phosphatidylserine (PS) exposure at the cell surface. In current study, the eryptotic, oxidative as well as hemolytic effects of therapeutical doses (0.5, 1 and 1.5 µM) of omeprazole were investigated after exposing erythrocytes for 48 hours. Investigation of eryptosis was done by cell size measurement, PS exposure determination and calcium channel inhibition. As a possible mechanism of omeprazole induced eryptosis, oxidative stress was investigated by determining the catalase, glutathione peroxidase and superoxide dismutase activities. Similarly, necrotic effect of omeprazole on erythrocytes was also evaluated through hemolysis measurement. Results of our study illustrated that 1.5 µM of omeprazole may induce significant decrease in superoxide dismutase, glutathione peroxidase and catalase activities as well as triggered the erythrocytes shrinkage, PS exposure and hemolysis. Role of calcium was also confirmed in inducing erythrocyte shrinkage. It is concluded that the exposure of erythrocytes with 1.5 µM omeprazole may enhance the rate of eryptosis and hemolysis by inducing oxidative stress.