Stimulation of suicidal erythrocyte death by ipratropium bromide

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.

Triggers, inhibitors, mechanisms, and significance of eryptosis: the suicidal erythrocyte death

Suicidal erythrocyte death or eryptosis is characterized by erythrocyte shrinkage, cell membrane blebbing, and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include Ca(2+) entry, ceramide formation, stimulation of caspases, calpain activation, energy depletion, oxidative stress, and dysregulation of several kinases. Eryptosis is triggered by a wide variety of xenobiotics. It is inhibited by several xenobiotics and endogenous molecules including NO and erythropoietin. The susceptibility of erythrocytes to eryptosis increases with erythrocyte age. Phosphatidylserine exposing erythrocytes adhere to the vascular wall by binding to endothelial CXC-Motiv-Chemokin-16/Scavenger-receptor for phosphatidylserine and oxidized low density lipoprotein (CXCL16). Phosphatidylserine exposing erythrocytes are further engulfed by phagocytosing cells and are thus rapidly cleared from circulating blood. Eryptosis eliminates infected or defective erythrocytes thus counteracting parasitemia in malaria and preventing detrimental hemolysis of defective cells. Excessive eryptosis, however, may lead to anemia and may interfere with microcirculation. Enhanced eryptosis contributes to the pathophysiology of several clinical disorders including metabolic syndrome and diabetes, malignancy, cardiac and renal insufficiency, hemolytic uremic syndrome, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, and Wilson's disease. Facilitating or inhibiting eryptosis may be a therapeutic option in those disorders.

Ipratropium bromide-mediated myocardial injury in in vitro models of myocardial ischaemia/reperfusion

Ipratropium bromide, a nonselective muscarinic antagonist, is widely prescribed for the treatment of chronic obstructive pulmonary disease (COPD). Analyses of COPD patients, with underlying ischaemic heart disease, receiving anticholinergics, have indicated increased risk of severity and occurrence of cardiovascular events (including myocardial infarction). The present study explored whether ipratropium bromide induces myocardial injury in nonclinical models of simulated myocardial ischaemia/reperfusion injury. Adult Sprague Dawley rat hearts/primary ventricular myocytes were exposed to simulated ischaemia/hypoxia prior to administration of ipratropium at the onset of reperfusion/reoxygenation. Infarct to risk ratio and cell viability was measured via triphenyl tetrazolium chloride staining and thiazolyl blue tetrazolium bromide (MTT) assay. The involvement of apoptosis and necrosis was evaluated by flow cytometry. Mitochondrial-associated responses were detected by tetramethylrhodamine methyl ester fluorescence and myocyte contracture. Ipratropium (1 × 10⁻¹¹ M - 1 × 10⁻⁴ M) significantly increased infarct/risk ratio and decreased cell viability in a dose-dependent manner. Increased levels of necrosis and apoptosis were observed via flow cytometry, accompanied by increased levels of cleaved caspase-3 following ipratropium treatment. Levels of endogenous myocardial acetylcholine were verified via use of an acetylcholine assay. In these experimental models, exogenous acetylcholine (1 × 10⁻⁷ M) showed protective properties, when administered alone, as well as abrogating the exacerbation of myocardial injury during ischaemia/reperfusion following ipratropium coadministration. In parallel experiments, under conditions of myocardial ischaemia/reperfusion, a similar injury was observed following atropine (1 × 10⁻⁷ M) administration. These data demonstrate for the first time in a nonclinical setting that ipratropium exacerbates ischaemia/reperfusion injury via apoptotic- and necrotic-associated pathways.

Resveratrol up-regulates the erythrocyte plasma membrane redox system and mitigates oxidation-induced alterations in erythrocytes during aging in humans

Reactive oxygen/nitrogen species (ROS/RNS)-mediated oxidative damage followed by disturbed cellular homeostasis is involved in aging and related consequences. Lipid peroxidation, post-translational modifications of proteins, and an impaired defense system due to increased oxidative stress jeopardize cell fate and functions, resulting in cell senescence. Resveratrol, a natural stilbene, has extensively been reported to elicit a plethora of health-promoting effects. The present study carried out on 97 healthy human subjects (62 males and 35 females) of both sexes provides experimental evidence that resveratrol confers ability to up-regulate the plasma membrane redox system (PMRS) along with ascorbate free radical reductase, a compensatory system operating in the cell to maintain cellular redox state. Furthermore, resveratrol provided significant protection against lipid peroxidation and protein carbonylation and restored the cellular redox homeostasis measured in terms of glutathione (GSH) and sulfhydryl (-SH) group levels during oxidation injury in erythrocytes of different age groups in humans. Findings suggest a possible role of resveratrol in retardation of age-dependent oxidative stress.