Quantification of reactive oxygen species generated by alveolar macrophages using lucigenin-enhanced chemiluminescence--methodical aspects

Association of zinc ion release and oxidative stress induced by intratracheal instillation of ZnO nanoparticles to rat lung

Zinc oxide (ZnO) nanoparticles are one of the important industrial nanoparticles. The production of ZnO nanoparticles is increasing every year. On the other hand, it is known that ZnO nanoparticles have strong cytotoxicity. In vitro studies using culture cells revealed that ZnO nanoparticles induce severe oxidative stress. However, the in vivo influence of ZnO nanoparticles is still unclear. In the present study, rat lung was exposed to ZnO nanoparticles by intratracheal instillation, and the influences of ZnO nanoparticles to the lung in the acute phase, particularly oxidative stress, were examined. Additionally, in vitro cellular influences of ZnO nanoparticles were examined using lung carcinoma A549 cells and compared to in vivo examinations. The ZnO nanoparticles used in this study released zinc ion in both dispersions. In the in vivo examinations, ZnO dispersion induced strong oxidative stress in the lung in the acute phase. The oxidative stress induced by the ZnO nanoparticles was stronger than that of a ZnCl(2) solution. Intratracheal instillation of ZnO nanoparticles induced an increase of lipid peroxide, HO-1 and alpha-tocopherol in the lung. The ZnO nanoparticles also induced strong oxidative stress and cell death in culture cells. Intracellular zinc level and reactive oxygen species were increased. These results suggest that ZnO nanoparticles induce oxidative stress in the lung in the acute phase. Intracellular ROS level had a high correlation with intracellular Zn(2+) level. ZnO nanoparticles will stay in the lung and continually release zinc ion, and thus stronger oxidative stress is induced.

Characterization of nanomaterials for toxicological studies

The scientific community, regulatory agencies, environmentalists, and most industry representatives all agree that more effort is required to ensure the responsible and safe development of new nanotechnologies. Characterizing nanomaterials is a key aspect in this effort. There is no universally agreed upon minimum set of characteristics although certain common properties are included in most recommendations. Therefore, characterization becomes more like a puzzle put together with various measurements rather than a single straightforward analytical measurement. In this chapter, we emphasize and illustrate the important elements of nanoparticle characterization with a systematic approach to physicochemical characterization. We start with an overview describing the properties that are most significant to toxicological testing along with suggested methods for characterizing an as-received nanomaterial and then specifically address the measurement of size, surface properties, and imaging.

Differences in functional activity and antigen expression of granulocytes primed in vivo with filgrastim, lenograstim, or pegfilgrastim

BACKGROUND

Granulocyte-colony-stimulating factor (G-CSF) is known to affect functional activity and antigen expression of neutrophil granulocytes. Beside nonglycosylated filgrastim and glycosylated lenograstim, pegylated filgrastim (pegfilgrastim) has recently been introduced for single administration into clinical use.

STUDY DESIGN AND METHODS

Here, granulocytes from 27 patients with nonmyeloid malignancies were compared functionally (migration, reactive oxygen species production, and G-CSF serum levels) and phenotypically (cell surface antigen expression) before and after G-CSF administration.

RESULTS

After exposure to G-CSF, chemotaxis was reduced significantly in the filgrastim group. Immunophenotypically, in vivo G-CSF-primed granulocytes were more mature in the lenograstim than in the filgrastim and to lesser extent in the pegfilgrastim groups as shown by the expression profile for CD11b, CD14, and CD16. Of note, G-CSF serum levels were similar among the groups.

CONCLUSION

Our data suggest that granulocytes exposed to glycosylated G-CSF in vivo seem to resemble more closely their steady-state phenotype than after treatment with nonglycosylated and to lesser extent pegylated G-CSF.

Malaria circumsporozoite protein inhibits the respiratory burst in Kupffer cells

After transmission by infected mosquitoes, malaria sporozoites rapidly travel to the liver. To infect hepatocytes, sporozoites traverse Kupffer cells, but surprisingly, the parasites are not killed by these resident macrophages of the liver. Here we show that Plasmodium sporozoites and recombinant circumsporozoite protein (CSP) suppress the respiratory burst in Kupffer cells. Sporozoites and CSP increased the intracellular concentration of cyclic adenosyl mono-phosphate (cAMP) and inositol 1,4,5-triphosphate in Kupffer cells, but not in hepatocytes or liver endothelia. Preincubation with cAMP analogues or inhibition of phosphodiesterase also inhibited the respiratory burst. By contrast, adenylyl cyclase inhibition abrogated the suppressive effect of sporozoites. Selective protein kinase A (PKA) inhibitors failed to reverse the CSP-mediated blockage and stimulation of the exchange protein directly activated by cAMP (EPAC), but not PKA inhibited the respiratory burst. Both blockage of the low-density lipoprotein receptor-related protein (LRP-1) with receptor-associated protein and elimination of cell surface proteoglycans inhibited the cAMP increase in Kupffer cells. We propose that by binding of CSP to LRP-1 and cell surface proteoglycans, malaria sporozoites induce a cAMP/EPAC-dependent, but PKA-independent signal transduction pathway that suppresses defence mechanisms in Kupffer cells. This allows the sporozoites to safely pass through these professional phagocytes and to develop inside neighbouring hepatocytes.

Mode of action of poly(vinylpyridine-N-oxide) in preventing silicosis: effective scavenging of carbonate anion radical

Small particles of crystalline silicon dioxide (crystallites) are exceptionally toxic. Inhalation of quartz crystallites causes silicosis, a devastating lung disease afflicting miners, particularly coal and stone workers. Poly(vinylpyridine-N-oxide)s (PVPNOs) have been applied in the prevention and treatment of silicosis, but their mode of action has been obscure. Recently, the sites of inducible *NO synthase activation and of nitrotyrosine formation were associated anatomically with the pathological quartz particle-caused lesions in the lungs. It has been suggested that the *NO formed combines rapidly with O2*- to yield ONOO-, a potential mediator of lung injury following silica exposure. Here, we show that PVPNOs do not react with peroxynitrite but scavenge exceptionally rapidly CO3*- radicals, which are produced in the decomposition of ONOO- in bicarbonate solutions. The rate constant for the reaction of CO3*- with PVPNO was found to be independent of the type and size of PVPNO, i.e., k = (1.9 +/- 0.2) x 10(5) M(-1) s(-1) per monomer. In contrast, the rate constant for the reaction of CO3*- with the small molecule 4-methylpyridine N-oxide did not exceed 1 x 10(4) M(-1) s(-1). The underlying reason for the difference is that, in the dissolved polymeric PVPNOs, the electrostatic repulsion between the N-oxide zwitterions destabilizes them, increasing dramatically their pKa. The protonated N-oxides at physiological pH have abstractable hydrogen atoms and are expected to react rapidly with CO3*-, just as cyclic hydroxylamines do. It is also shown that PVPNO inhibits tyrosine nitration by peroxynitrite at pH 7.6 in the presence of excess of CO2 in a concentration-dependent manner. Hence, binding of PVPNO to the quartz particles and eliminating CO3*- could prevent the killing of macrophages, the associated release of macrophage-recruiting cytokines, and the amplification of the local concentration of *NO by the recruited macrophages. The latter causes necrosis of the macrophage-infiltrated lung tissue and, upon repair of the necrotic lesion, results in the growth of the dysfunctional fibrotic tissue, which is the hallmark of silicosis.

Determination of reactive oxygen species in single human erythrocytes using microfluidic chip electrophoresis

Reactive oxygen species (ROS) are known to not only mediate the damage of cellular constituents but also to regulate cellular signaling. Analysis of ROS is essential if we wish to understand the mechanisms of cellular alterations. In this paper, a microfluidic chip-based approach to the determination of ROS in single erythrocyte was developed by using a simple crossed-channel glass chip with integrated operational functions, including cell sampling, single cell loading, docking, lysing, and capillary electrophoretic (CE) separation with laser-induced fluorescence (LIF) detection. Non-fluorescent dihydrorhodamine 123 (DHR 123), which can be oxidized intracellularly by ROS to the fluorescent rhodamine 123 (Rh 123), was used as the fluorogenic reagent. The effect of pH on the migration time of Rh 123 and detection sensitivity was discussed. The present method minimized dilution of intracellular ROS during reaction with DHR 123 and determination. As a result, an extremely low detection limit of 0.8 amol has been achieved. The time required for complete analysis of one human erythrocyte was less than 3 min. A migration time precision of 4.1% RSD was obtained for six consecutively-injected cells. Upon stimulation with 4 mmol/l H2O2 for 10 min, the intracellular ROS concentration was found to increase on average by about a factor of 8.4.

Molecular mechanisms of tumor necrosis factor alpha gene expression in monocytic cells via hyperglycemia-induced oxidant stress-dependent and -independent pathways

Increased oxidative stress has been reported in vivo in the diabetic state via the production of reactive oxygen species (ROS). Such stress is bound to play a key role on activation of circulating monocytes, leading to the accelerated atherosclerosis observed in diabetics. However the exact molecular mechanisms of monocyte activation by high glucose is currently unclear. Here, we demonstrate that chronic high glucose (CHG) causes a dramatic increase in the release of the inflammatory cytokine tumor necrosis factor alpha (TNFalpha), at least in part through enhanced TNFalpha mRNA transcription, mediated by ROS via activation of transcription factors nuclear factor kappaB (NF-kappaB) and activating protein-1 (AP-1). TNFalpha accumulation in the conditioned media was increased 10-fold and mRNA levels were increased 11.5-fold by CHG. The following observations supported that both NF-kappaB and AP-1 mediated enhanced TNFalpha transcription by CHG: 1) A 295-base pair fragment of the proximal TNFalpha promoter containing NF-kappaB and AP-1 sites reproduced the effects of CHG on TNFalpha transcription in a luciferase reporter assay, 2) mutational analyses of both NF-kappaB and the AP-1 sites abrogated 90% of the luciferase activity, 3) gel-shift analysis using the binding sites showed activation of NF-kappaB and AP-1 in CHG nuclear extracts, and 4) Western blot analyses demonstrated elevated nuclear levels of p65 and p50 and decreased cytosolic levels of IkappaBalpha in CHG-treated monocytes. That ROS acted as a key intermediate in the CHG pathway was supported by the following evidence: 1) increased superoxide levels similar to those observed with PMA or TNFalpha, 2) increased phosphorylation of stress-responsive mitogen-activated protein kinases p38 and JNK-1, 3) counteraction of the effects of CHG on TNFalpha production, the 295TNFluc reporter activity, activation of NF-kappaB, and repression of IkappaBalpha by antioxidants and p38 mitogen-activated protein kinase inhibitors. The study suggests that ROS function as key components in the regulatory pathway progressing from elevated glucose to monocyte activation.

Production of reactive oxygen species by phagocytic cells after exposure to glass wool and stone wool fibres - effect of fibre preincubation in aqueous solution

The potential of four man-made vitreous fibres (MMVFs) (glass wool Code A, stone wool Code G, HT-N and MMVF 21) and of two natural mineral fibres (crocidolite, erionite) to induce production of reactive oxygen species (ROS) by differentiated HL-60 cells (HL-60-M cells) was investigated by determination of luminol-enhanced chemiluminescence (CL). Quartz served as positive control. The same system was used to uncover possible influences of fibre preincubation in aqueous solutions on the ROS-generating potential. Following preincubation in unbuffered saline over about 4 weeks, Code A and G fibres showed decreased ROS-generating potential as compared to freshly suspended fibres. On the other hand, MMVF 21 and HT-N fibres as well as crocidolite and erionite showed no decreased CL after incubation in aqueous solutions. The observed decrease of the ROS-generating potential of Code A and G fibres after preincubation may be an expression of fibre surface alterations (leaching, initiation of dissolution) that influences the response of exposed phagocytic cells. After incubation of both fibres in buffered solutions at different pH values (5.0, 7.4) a reduced ROS-generating potential was still discernible as compared to freshly suspended fibres.

Enzymatic quantification of cell-matrix and cell-cell adhesion

Adhesion assays are powerful tools to investigate the adhesive properties of cells. The quantification of cell adhesion enables determination of the capacity of cells to stick to a target, screening for novel adhesion involved binding molecules, exploration of structure-function relationships of adhesion molecules, evaluation of adhesion targets, and examination of compounds interfering with cell adhesion. Thus, quantification of cell adhesion needs simple and reliable methods that might be applied for both research and diagnostic purposes. This review presents methodological principles of enzymatic approaches for quantification of cell adhesion. In particular, the advantages of exogenous cell labelling with horseradish peroxidase are described.