Rod and spherical selenium nanoparticles: Physicochemical properties and effects on red blood cells and neutrophils.

The influence of selenium (Se) nanoparticles in the form of rods (SeNrs) and spheres (SeSps), synthesized by laser ablation, on the structural and functional properties of human blood erythrocytes and neutrophils was studied for anticancer activity in vitro. SeNrs and SeSps do not have cytotoxicity towards neutrophils and do not cause hemolysis. The elastic modulus and resistance of erythrocytes to HOCl-induced hemolysis increased after binding of Se nanoparticles to the plasma membrane.

Hypochlorous Acid-Modified Serum Albumin Causes NETosis in the Whole Blood Ex Vivo and in Isolated Neutrophils.

Type 2 diabetes mellitus (T2DM) is accompanied by halogenative stress resulting from the excessive activation of neutrophils and neutrophilic myeloperoxidase (MPO) generating highly reactive hypochlorous acid (HOCl). HOCl in blood plasma modifies serum albumin (Cl-HSA). We studied the formation of neutrophil extracellular traps (NETs) in the whole blood and by isolated neutrophils under the action of Cl-HSA.

Influence of natural polysaccharides on the morphology and properties of hybrid vaterite microcrystals.

Co-precipitation of biopolymers into calcium carbonate crystals changes their physicochemical and biological properties. This work studies hybrid microcrystals of vaterite obtained in the presence of natural polysaccharides, as carriers for the delivery of proteins and enzymes. Hybrid microcrystals with dextran sulfate, chondroitin sulfate, heparin, fucoidan, and pectin were obtained and compared.

Incorporation of Pectin into Vaterite Microparticles Prevented Effects of Adsorbed Mucin on Neutrophil Activation.

The application of vaterite microparticles for mucosal delivery depends on their interaction with mucin and immune cells. As we have shown previously, the binding of mucin onto particles enhances the generation of reactive oxygen species by neutrophils. The attenuation of the pro-oxidant effect of the bound mucin through the modification of vaterite could improve its biocompatibility.

Methylglyoxal-Modified Human Serum Albumin Binds to Leukocyte Myeloperoxidase and Inhibits its Enzymatic Activity.

Hyperglycemia in diabetes mellitus induces modification of proteins by glucose and its derivative methylglyoxal (MG). Neutrophils perform their bactericidal activity mainly via reactive halogen (RHS) and oxygen (ROS) species generation catalyzed by myeloperoxidase (MPO) stored in neutrophil azurophilic granules (AGs) and membrane NADPH oxidase, respectively. Herein, we study the binding of human serum albumin (HSA) modified with MG (HSA-MG) to MPO and its effects on MPO activity and release by neutrophils.

New Application of the Commercially Available Dye Celestine Blue B as a Sensitive and Selective Fluorescent "Turn-On" Probe for Endogenous Detection of HOCl and Reactive Halogenated Species.

Hypochlorous acid (HOCl) derived from hydrogen peroxide and chloride anion by myeloperoxidase (MPO) plays a significant role in physiological and pathological processes. Herein we report a phenoxazine-based fluorescent probe Celestine Blue B (CB) that is applicable for HOCl detection in living cells and for assaying the chlorinating activity of MPO. A remarkable selectivity and sensitivity (limit of detection is 32 nM), along with a rapid "turn-on" response of CB to HOCl was demonstrated.

Neutrophil Activation by Mineral Microparticles Coated with Methylglyoxal-Glycated Albumin.

Hyperglycemia-induced protein glycation and formation of advanced glycation end-products (AGEs) plays an important role in the pathogenesis of diabetic complications and pathological biomineralization. Receptors for AGEs (RAGEs) mediate the generation of reactive oxygen species (ROS) via activation of NADPH-oxidase. It is conceivable that binding of glycated proteins with biomineral particles composed mainly of calcium carbonate and/or phosphate enhances their neutrophil-activating capacity and hence their proinflammatory properties.

Structure-biological activity relationships of myeloperoxidase to effect on platelet activation.

Myeloperoxidase (MPO), an oxidant-producing enzyme of neutrophils, has been shown to prime platelet activity promoting immunothrombosis. Native MPO is a homodimer, consisting of two identical protomers (monomer) connected by a single disulfide bond. But in inflammatory foci, MPO can be found both in the form of a monomer and in the form of a dimer.

Lactoferrin modified by hypohalous acids: Partial loss in activation of human neutrophils.

Previously we have shown that lactoferrin (LTF), a protein of secondary neutrophilic granules, can be efficiently modified by hypohalous acids (HOCl and HOBr), which are produced at high concentrations during inflammation and oxidative/halogenative stress by myeloperoxidase, an enzyme of azurophilic neutrophilic granules. Here we compared the effects of recombinant human lactoferrin (rhLTF) and its halogenated derivatives (rhLTF-Cl and rhLTF-Br) on functional responses of neutrophils. Our results demonstrated that after halogenative modification, rhLTF lost its ability to induce mobilization of intracellular calcium, actin cytoskeleton reorganization, and morphological changes in human neutrophils.

The effect of myeloperoxidase isoforms on biophysical properties of red blood cells.

Myeloperoxidase (MPO), an oxidant-producing enzyme, stored in azurophilic granules of neutrophils has been recently shown to influence red blood cell (RBC) deformability leading to abnormalities in blood microcirculation. Native MPO is a homodimer, consisting of two identical protomers (monomeric MPO) connected by a single disulfide bond but in inflammatory foci as a result of disulfide cleavage monomeric MPO (hemi-MPO) can also be produced. This study investigated if two MPO isoforms have distinct effects on biophysical properties of RBCs.

Effects of recombinant human lactoferrin on calcium signaling and functional responses of human neutrophils.

Lactoferrin is a non-heme iron-binding glycoprotein with multiple health-beneficial functions including antimicrobial, antioxidant, anticarcinogenic, and immunomodulatory effects. There is emerging evidence that neutrophils may serve as targets of lactoferrin in vivo, and here we show how recombinant human lactoferrin (rhLf) can contribute to this regulation. Indeed, our results demonstrate that rhLf binds efficiently to human neutrophils and induces a variety of early cellular responses such as mobilization of intracellular Ca, remodeling of actin cytoskeleton, and degranulation (release of lysozyme and myeloperoxidase).

Protective Effect of Dinitrosyl Iron Complexes with Glutathione in Red Blood Cell Lysis Induced by Hypochlorous Acid.

Hypochlorous acid (HOCl), one of the major precursors of free radicals in body cells and tissues, is endowed with strong prooxidant activity. In living systems, dinitrosyl iron complexes (DNIC) with glutathione ligands play the role of nitric oxide donors and possess a broad range of biological activities. At micromolar concentrations, DNIC effectively inhibit HOCl-induced lysis of red blood cells (RBCs) and manifest an ability to scavenge alkoxyl and alkylperoxyl radicals generated in the reaction of HOCl with -butyl hydroperoxide.

Neutrophil activation in response to monomeric myeloperoxidase.

Myeloperoxidase (MPO) is an oxidant-producing enzyme that can also regulate cellular functions via its nonenzymatic effects. Mature active MPO isolated from normal human neutrophils is a 145 kDa homodimer, which consists of 2 identical protomers, connected by a single disulfide bond. By binding to CD11b/CD18 integrin, dimeric MPO induces neutrophil activation and adhesion augmenting leukocyte accumulation at sites of inflammation.

[Exocytosis of myeloperoxidase from activated neutrophils in the presence of heparin].

Exocytosis of myeloperoxidase (MPO) from activated neutrophils in the presence of the anionic polysaccharide heparin was studied. It was determined that the optimal concentration of heparin (0.1 u/ml), at which there is no additional activation of cells (absence of amplification of exocytosis of lysozyme contained in specific and azurophilic granules).

Enzymatic and bactericidal activity of myeloperoxidase in conditions of halogenative stress.

Myeloperoxidase (MPO), found mainly in neutrophils, is released in inflammation. MPO produces reactive halogen species (RHS), which are bactericidal agents. However, RHS overproduction, i.

Capacity of ceruloplasmin to scavenge products of the respiratory burst of neutrophils is not altered by the products of reactions catalyzed by myeloperoxidase.

CP is a copper-containing ferroxidase of blood plasma, which acts as an acute phase reactant during inflammation. The effect of oxidative modification of CP induced by oxidants produced by MPO, such as HOCl, HOBr, and HOSCN, on its spectral, enzymatic, and anti-inflammatory properties was studied. We monitored the chemiluminescence of lucigenin and luminol along with fluorescence of hydroethidine and scopoletin to assay the inhibition by CP of the neutrophilic respiratory burst induced by PMA or fMLP.

Myeloperoxidase Stimulates Neutrophil Degranulation.

Myeloperoxidase, heme enzyme of azurophilic granules in neutrophils, is released into the extracellular space in the inflammation foci. In neutrophils, it stimulates a dose-dependent release of lactoferrin (a protein of specific granules), lysozyme (a protein of specific and azurophilic granules), and elastase (a protein of azurophilic granules). 4-Aminobenzoic acid hydrazide, a potent inhibitor of peroxidase activity of myeloperoxidase, produced no effect on neutrophil degranulation.

[Myeloperoxidase activity in blood plasma as a criterion of therapy for patients with cardiovascular disease].

A significant increase in the myeloperoxidase (MPO) activity has been found in plasma of patients with stable angina and with acute coronary syndrome (ACS) in comparison with the control group. MPO concentration was significantly increased in plasma of ACS patients. Reduced MPO activity in the treated ACS patients correlated with a favorable outcome of the disease.

Binding of human myeloperoxidase to red blood cells: Molecular targets and biophysical consequences at the plasma membrane level.

Myeloperoxidase (MPO) is an oxidant-producing enzyme that can also bind to cellular surface proteins. We found that band 3 protein and glycophorins A and B were the key MPO-binding targets of human red blood cells (RBCs). The interaction of MPO with RBC proteins was mostly electrostatic in nature because it was inhibited by desialation, exogenic sialic acid, high ionic strength, and extreme pH.

Hypohalous acid-modified human serum albumin induces neutrophil NADPH oxidase activation, degranulation, and shape change.

Halogenated lipids, proteins, and lipoproteins formed in reactions with myeloperoxidase (MPO)-derived hypochlorous acid (HOCl) and hypobromous acid (HOBr) can contribute to the regulation of functional activity of cells and serve as mediators of inflammation. Human serum albumin (HSA) is the major plasma protein target of hypohalous acids. This study was performed to assess the potency of HSA modified by HOCl (HSA-Cl) and HOBr (HSA-Br) to elicit selected neutrophil responses.

Myeloperoxidase modulates human platelet aggregation via actin cytoskeleton reorganization and store-operated calcium entry.

Myeloperoxidase (MPO) is a heme-containing enzyme released from activated leukocytes into the extracellular space during inflammation. Its main function is the production of hypohalous acids that are potent oxidants. MPO can also modulate cell signaling and inflammatory responses independently of its enzymatic activity.

Measurement of plasma hemoglobin peroxidase activity.

We described a spectrophotometric method for measuring hemoglobin peroxidase activity in human plasma using o-dianisidine (o-DA) as the substrate and myeloperoxidase specific inhibitor 4-aminobensoic acid hydrazide (ruling out the probable contribution of myeloperoxidase to the measured parameter value). The optimal conditions (pH 5.5; 2 mM H2O2) have been determined, at which hemoglobin makes the main contribution to plasma oxidation of o-DA.

Gas chromatographic investigation of volatile nitrogen containing bases of Antarctic krill Euphausia superba Dana.

The composition of the volatile nitrogen-containing bases of fresh-caught Antarctic krill E. superba has been investigated by gas chromatography. The analysis was carried out on three packed columns with Apiezon L, Triton X-305, PEG-1000 and one glass capillary column with Triton X-305.