Serotonin and its metabolites reduce oxidative stress in murine RAW264.7 macrophages and prevent inflammation

In this study, we focused on comparing the effects of serotonin and its metabolites on the functions of RAW264.7 cells (emphasis on oxidative burst and production of nitric oxide and cytokines), thereby expanding the scope of existing knowledge with advent of novel findings in this field. Changes in production of reactive oxygen species (ROS) by RAW264.7 cells after treatment with serotonin, N-acetylserotonin and melatonin were determined using the chemiluminescence (CL) assay. To exclude the direct scavenging effects of the studied compounds on the CL response, the antioxidant properties of all respective compounds were measured using TRAP and amperometrical method. Nitric oxide (NO) production was measured by Griess reagent and inducible NO synthase (iNOS) expression by Western blot. Cytokine production was assessed using the Mouse Cytokine Panel A Array kit and ELISA. We showed that all tested compounds were able to reduce oxidative stress, as well as inhibit production of inflammatory cytokines by macrophages. Of the tested compounds, serotonin and N-acetylserotonin were markedly better antioxidants than melatonin. In comparison, other effects of tested compounds were very similar. It can be concluded that antioxidant capacity of tested compounds is a major advantage in the early stages of inflammation. Since plasma concentrations of N-acetylserotonin and melatonin are lower than serotonin, it can be deduced that serotonin plays a key role in modulation of inflammation and the regulatory functions of immune cells, while also protecting cells against oxidative stress.

Analysis of Plant Extracts Antimutagenicity Using the Ames Test and the Cytogenetic Analysis of Peripheral Blood Lymphocytes

This work was focused on comparison of antimutagenic effect of selected plant extracts (carrot, paprika, tomato, spinach, onion, kiwi and green tea) analysed by two independent tests of genotoxicity: i) the Ames test with Salmonella typhimurium TA98 and ii) cytogenetic analysis of peripheral blood lymphocytes (CAPL). Both methods were proved without and/or with metabolic activation. Samples were allowed to be positive antimutagens based on their ability to inhibit the mutagenic effects of standard mutagens. High positive results (more than 60% of inhibition of mutagenic effect) were obtained with extract from green tea. Extracts from paprika, carrot and spinach as well as solutions of standard alltrans-carotene and some standard flavonoids showed antimutagenic (40-60% of inhibition) or weakly antimutagenic (20-40% of inhibition) effects. Positive antimutagenic effects of extracts from spinach and green tea were determined using CAPL method too. Further, the comparison of antimutagenic activity and antioxidant capacity of tested samples analysed using TRAP (total radical-trapping antioxidant parameter) method was proved. Extract from green tea showed the highest antioxidant as well as antimutagenic capacity, but no correlation was found between these parameters in all tested extracts.

The Influence of Some Immunosuppressive Drugs on the Metabolic Activity of Human Phagocytes and Lymphocytes in vitro

The effect of azathioprine, cyclosporine A and FK 506 on the production of reactive oxygen species by polymorphonuclear leukocytes (Iuminol-dependent chemiluminescence) and on the blast transformation of lymphocytes ([3H]thymidine incorporation) was studied in dose-response experiments under in vitro conditions. Although there were no significant effects of immunosuppressives on non-stimulated blast transformation, FK 506 and cyclosporine A significantly inhibited the blast transformation stimulated by concanavaline A and protein A and the effects made it possible to build 2nd-order polynomial dose-response models. Azathioprine was found to be a relatively weak inhibitor of [3H]thymidine incorporation in lymphocytes (76% of control value). Spontaneous production of reactive oxygen species by polymorphonuclear leukocytes was significantly inhibited, particularly by FK 506 (1–100 ng.ml−1) in comparison to the control value, while there was no effect of the immunosuppressives on this system activated either by starch grains or zymosan. Only the highest applied concentrations of azathioprine (100 ng.ml−1) and cyclosporine A (1000 ng.ml−1) led to a significant decline in spontaneous phagocytosis. The direct effect of immunosuppressives on activated production of reactive oxygen species by neutrophiles was not proved.

Modulation of neutrophil oxidative burst via histamine receptors

Histamine has the ability to influence the activity of immune cells including neutrophils and plays a pivotal role in inflammatory processes, which are a complex network of cellular and humoral events. One of the main functions manifested by activated neutrophils is oxidative burst, which is linked to the production of reactive oxygen species; therefore, the effects of histamine receptor agonists and antagonists on the oxidative burst of neutrophils is reviewed. A role for the well-characterized histamine H1 and H2 receptors in this process is discussed and compared to that of the recently discovered H4 receptor.

The effects of chloroquine and hydroxychloroquine on nitric oxide production in RAW 264.7 and bone marrow-derived macrophages

Chloroquine, an antimalarial drug, can also be used in the regulation of the immune system, e.g. it is used in the treatment of autoimmune diseases. In this study we investigated the effects of chloroquine and its hydroxy-derivative on nitric oxide (NO) production in two different cell types: (i) immortalized mouse macrophage cell line RAW 264.7 and (ii) mouse bone marrow-derived macrophages (BMDM). The cells were treated with different concentrations (1-100 μM) of chloroquine or hydroxychloroquine and stimulated with lipopolysaccharide for 24 h to induce NO production. Measurement of nitrites by the Griess reaction was used to evaluate the production of NO. Expression of inducible NO synthase was evaluated with Western blot and ATPcytotoxicity test was used to measure the viability of the cells. Our results showed that both chloroquine and its hydroxy-derivative inhibited NO production in both cell types. However, based on the results of LD50 these inhibitory effects of both derivatives were due to their cytotoxicity. The LD50 values for chloroquine were 24.77 μM (RAW 264.7) and 24.86 μM (BMDM), the LD50 for hydroxychloroquine were 13.28 μM (RAW 264.7) and 13.98 μM (BMDM). In conclusion, hydroxychloroquine was more cytotoxic than its parent molecule. Comparing the two cell types tested, our data suggest that there are no differences in cytotoxicity of chloroquine or hydroxychloroquine for primary cells (BMDM) or immortalized cell line (RAW 264.7).

Novel insights into the electrochemical detection of nitric oxide in biological systems

In recent years, microsensor technologies have made a rapid expansion into different fields of physical sciences, engineering, and biomedicine. For analyses of various biomolecules, novel sensors and detection platforms in the electrochemical field have been reported recently. The most important applications based on microelectromechanical systems dramatically reduce the need of manipulation steps with samples, while improving data quality and quantitative capabilities. This is also the case of a special class of electrochemical sensors that allow direct, real-time and non-invasive measurements of nitric oxide, whose determination is crucial for the purposes of basic research, as well as of preclinical and clinical studies. Therefore, this minireview will focus on the description of recent discoveries in the electrochemical determination of nitric oxide, released in different in vitro systems.

Uric acid modulates vascular endothelial function through the down regulation of nitric oxide production

Endothelial dysfunction characterized by decreased nitric oxide (NO) bioavailability is the first stage of coronary artery disease. It is known that one of the factors associated with an increased risk of coronary artery disease is a high plasma level of uric acid. However, causative associations between hyperuricaemia and cardiovascular risk have not been definitely proved. In this work, we tested the effect of uric acid on endothelial NO bioavailability. Electrochemical measurement of NO production in acetylcholine-stimulated human umbilical endothelial cells (HUVECs) revealed that uric acid markedly decreases NO release. This finding was confirmed by organ bath experiments on mouse aortic segments. Uric acid dose-dependently reduced endothelium-dependent vasorelaxation. To reveal the mechanism of decreasing NO bioavailability we tested the effect of uric acid on reactive oxygen species production by HUVECs, on arginase activity, and on acetylcholine-induced endothelial NO synthase phosphorylation. It was found that uric acid increases arginase activity and reduces endothelial NO synthase phosphorylation. Interestingly, uric acid significantly increased intracellular superoxide formation. In conclusion, uric acid decreases NO bioavailability by means of multiple mechanisms. This finding supports the idea of a causal association between hyperuricaemia and cardiovascular risk.

Arginine-based inhibitors of nitric oxide synthase: therapeutic potential and challenges

In the past three decades, nitric oxide has been well established as an important bioactive molecule implicated in regulation of cardiovascular, nervous, and immune systems. Therefore, it is not surprising that much effort has been made to find specific inhibitors of nitric oxide synthases (NOS), the enzymes responsible for production of nitric oxide. Among the many NOS inhibitors developed to date, inhibitors based on derivatives and analogues of arginine are of special interest, as this category includes a relatively high number of compounds with good potential for experimental as well as clinical application. Though this group of inhibitors covers early nonspecific compounds, modern drug design strategies such as biochemical screening and computer-aided drug design have provided NOS-isoform-specific inhibitors. With an emphasis on major advances in this field, a comprehensive list of inhibitors based on their structural characteristics is discussed in this paper. We provide a summary of their biochemical properties as well as their observed effects both in vitro and in vivo. Furthermore, we focus in particular on their pharmacology and use in recent clinical studies. The potential of newly designed specific NOS inhibitors developed by means of modern drug development strategies is highlighted.

Differentiating between intra- and extracellular chemiluminescence in diluted whole-blood samples

INTRODUCTION

The differentiation between extra- and intracellular production of reactive oxygen species (ROS) in whole blood was measured by luminol- and isoluminol-enhanced chemiluminescence (CL).

METHODS

Azide (total CL inhibition), azide + horseradish peroxidase (HRP, restoring extracellular CL), superoxide dismutase + catalase (depleting extracellular ROS) and HRP (enhancing extracellular CL) were used to modulate luminol- and isoluminol-enhanced CL (10(-6) -10(-3) m luminophores) of 125× diluted whole blood which was activated by both calcium ionophore A23187 (Ca-I) and opsonized zymosan particles (OZP) separately.

RESULTS

Both activators stimulated intra- and extracellular production of ROS. Luminol-enhanced CL of Ca-I-activated samples detected the intracellular ROS, and with the addition of HRP detected the extracellular CL as well. CL enhanced with isoluminol in concentrations of 10(-4) m or less was mostly extracellular. There was a mixture of intra- and extracellular CL in OZP-activated samples, probably because of the ingestion of luminophore molecules.

CONCLUSION

Measurement of Ca-I-activated CL enhanced with 10(-4) m luminol is recommended for the detection of intracellular ROS. The addition of HRP leads to the detection of overall ROS production while the OZP-activated system with its addition of HRP can only be used to detect overall ROS production. Ca-I-activated CL enhanced with 10(-4) m isoluminol and with addition of HRP is recommended for the detection of extracellular CL.

Soluble glucomannan isolated from Candida utilis primes blood phagocytes

It is well documented that the polysaccharide glucomannan (GM), an abundant constituent of the fungal cell wall, in the form of particulate induces strong activation of phagocytes, however, the effects of soluble GM are not known. Activation of phagocyte anti-microbial mechanisms is a crucial part of the innate host defense against invading pathogens. However, under uncontrolled inflammatory conditions they contribute to damage of surrounding tissues. Thus, to prevent these deleterious effects, the activation of phagocytes is a tightly regulated process. Therefore, in this study we analyzed the effect of soluble GM on some neutrophil functions such as reactive oxygen species production, degranulation, and receptor mobilization at the plasma membrane. Soluble GM at the tested concentrations did not stimulate oxidative burst of phagocytes directly but significantly potentiated oxidative burst in response to opsonized zymosan particles. GM induced significant phosphorylation of p47phox subunit of NADPH oxidase on Ser345. This priming effect of GM was accompanied by time and concentration dependent degranulation characterized by increased surface expression of receptors stored in neutrophil granules (CD10, CD11b, CD14, CD35, and CD66b). Degranulation was further confirmed by increase of elastase activity in media. Thus, it could be suggested that soluble GM induces priming of phagocytes connected with their degranulation, the increase of surface receptor expression, and potentiation of oxidative burst response to opsonized particles through the activation of NADPH oxidase.

Inhibition of chemiluminescence by carvedilol in the cell‐free system, whole human blood and blood cells

Carvedilol inhibits luminol-enhanced chemiluminescence of reactive oxygen metabolites in vitro. In this study it was found that, in the cell-free system, carvedilol dose-dependently decreased chemiluminescence in the following ranking order of radicals: hydroxyl radical > hydrogen peroxide > superoxide radical. The inhibition of myeloperoxidase was significant with carvedilol concentrations of 10 and 100 micromol/l and manifested in the concentration-dependent shift of chemiluminescence peaks to the right. In whole blood, carvedilol in concentrations of 10 and 100 micromol/l significantly inhibited chemiluminescence induced by both receptor-bypassing stimuli (A23187, PMA) and receptor-operating stimuli (fMLP, OpZ). Carvedilol dose-dependently inhibited chemiluminescence of isolated human polymorphonuclear leucocytes in the ranking order of stimuli: A23187 > OpZ > fMLP. In the presence of blood platelets, carvedilol did not substantially change chemiluminescence induced by fMLP and OpZ, while it was much more effective on chemiluminescence stimulated with calcium ionophore A23187. This could be the result of the supportive effect of serotonin liberated from platelets by A23187.

The effects of H1-antihistamines on the nitric oxide production by RAW 264.7 cells with respect to their lipophilicity

H1-antihistamines are known to be important modulators of inflammatory response. However, the information about the influence of these drugs on reactive nitrogen species generation is still controversial. The main aim of the present study was to investigate the effects of selected H1-antihistamines on nitric oxide production by lipopolysaccharide-stimulated murine macrophages RAW 264.7, measured as changes in inducible nitric oxide synthase (iNOS) protein expression in cell lysates by Western blotting and nitrite formation in cell supernatants using the Griess reaction. In pharmacological non-toxic concentrations, H1-antihistamines significantly inhibited nitrite accumulation that was not caused by the scavenging ability of drugs against nitric oxide, measured amperometrically. The degree of inhibition of nitrite accumulation positively correlated with the degree of tested lipophilicity, measured by reversed-phase thin layer chromatography. Furthermore, H1-antihistamines differentially modulated the iNOS protein expression. In conclusion, as was shown in this study, the modulation of nitric oxide production could be caused by the downregulation of iNOS protein expression and/or the iNOS protein activity.

Carvedilol and adrenergic agonists suppress the lipopolysaccharide-induced NO production in RAW 264.7 macrophages via the adrenergic receptors

The interaction of adrenergic agonists and/or antagonists with the adrenergic receptors expressed on immunologically active cells including macrophages plays an important role in regulation of inflammatory responses. Our study investigated the effects of carvedilol, a unique vasodilating beta-adrenergic antagonist, and endogenous adrenergic agonists (adrenalin, noradrenalin, and dopamine) and/or antagonists (prazosin, atenolol) on lipopolysaccharide-stimulated nitric oxide (NO) production from murine macrophage cell line RAW 264.7. The production of NO was determined as the concentration of nitrites in cell supernatants (Griess reaction) and inducible nitric oxide synthase (iNOS) protein expression (Western blot analysis). Scavenging properties against NO were measured electrochemically. Carvedilol in a concentration range of 1, 5, 10 and 25 microM inhibited iNOS protein expression and decreased the nitrite concentration in cell supernatants. Adrenalin, noradrenalin or dopamine also inhibited the iNOS protein expression and the nitrite accumulation. Prazosine and atenolol prevented the effect of both carvedilol and adrenergic agonists on nitrite accumulation and iNOS expression in lipopolysaccharide-stimulated cells. These results, together with the absence of scavenging properties of carvedilol against NO, imply that both carvedilol and adrenergic agonists suppress the lipopolysaccharide-evoked NO production by macrophages through the activation and modulation of signaling pathways connected with adrenergic receptors.

Ultrafiltered pig leukocyte extract (IMUNOR®) decreases nitric oxide formation and hematopoiesis-stimulating cytokine production in lipopolysaccharide-stimulated RAW 264.7 macrophages

A low-molecular-weight (<12 kDa) ultrafiltered pig leukocyte extract, IMUNOR, was tested in experiments in vitro on non-stimulated and lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages in order to assess modulation of nitric oxide (NO) production (measured indirectly as the concentration of nitrites), hematopoiesis-stimulating activity of the supernatant of the macrophage cells (ascertained by counting cell colonies growing from progenitor cells for granulocytes and macrophages (GM-CFC) in vitro), and the release of hematopoiesis-stimulating cytokines. No hematopoiesis-stimulating activity and cytokine or NO production were found in the supernatant of non-stimulated macrophages. It was found that IMUNOR does not influence this status. Supernatant of LPS-stimulated macrophages was characterized by hematopoiesis-stimulating activity, as well as by the presence of nitrites, interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF). A key role in the hematopoiesis-stimulating activity of the supernatant of LPS-stimulated macrophages could be ascribed to G-CSF since the formation of the colonies could be abrogated nearly completely by monoclonal antibodies against G-CSF. IMUNOR was found to suppress all the mentioned manifestations of the LPS-activated macrophages. When considering these results together with those from our previous in vivo study revealing stimulatory effects of IMUNOR on radiation-suppressed hematopoiesis, a hypothesis may be formulated which postulates a homeostatic role of IMUNOR, consisting in stimulation of impaired immune and hematopoietic systems but also in cutting back the production of proinflammatory mediators in cases of overstimulation which threats with undesirable consequences.

p53 arrests growth and induces differentiation of v-Myb-transformed monoblasts

The p53 protein can control cell cycle progression, programmed cell death, and differentiation of many cell types. Ectopic expression of p53 can resume capability of cell cycle arrest, differentiation, and apoptosis in various leukemic cell lines. In this work, we expressed human p53 protein in v-Myb-transformed chicken monoblasts. We found that even this protein possessing only 53% amino acid homology to its avian counterpart can significantly alter morphology and physiology of these cells causing the G2-phase cell cycle arrest and early monocytic differentiation. Our results document that the species-specific differences of the p53 molecules, promoters/enhancers, and co-factors in avian and human cells do not interfere with differentiation- and cell cycle arrest promoting capabilites of the p53 tumor suppressor even in the presence of functional v-Myb oncoprotein. The p53-induced differentiation and cell cycle arrest of v-Myb-transformed monoblasts are not associated with apoptosis suggesting that the p53-driven pathways controlling apoptosis and differentiation/proliferation are independent.

Dealcoholized red and white wines decrease oxidative stress associated with inflammation in rats

In vitroexperiments have demonstrated that polyphenols exhibit antioxidant and anti-inflammatory activities. The present study was designed to test whether dealcoholized red (DRW) and white (DWW) wines can decrease the oxidative stress associated with inflammationin vivo. Rats were fed for 15 d either a control diet or one supplemented with DRW or DWW. Finally, a granuloma was induced by subcutaneous administration of carrageenan. Although DRW showed higher antioxidant activityin vitrothan DWW, both wines decreased the number of cells recruited into the granuloma pouch. Malondialdehyde decreased in plasma and inflammatory exudate from rats fed with DRW- and DWW-rich diets. Moreover, the concentration of NO increased in exudate, which correlates with the increase in the citrulline:arginine ratio. Polymorphonuclear leucocytes from the inflammatory exudate of rats fed dealcoholized wines showed decreased superoxide anion (O2∙−) production and increased NO productionex vivo. This change in NO production resulted from increased expression and activity of inducible NO synthase (EC 1.14.13.39). Moreover, the up regulation of cyclo-oxygenase-2 (EC 1.14.99.1) protein expression observed in rats fed the DRW-rich diet was not related to a direct effect of NO. The present results indicate that the non-alcoholic compounds of wines not only improve antioxidant status in an inflammatory situation, but also limit cell infiltration, possibly through a decrease in O2∙−and an increase in NO production.

Nitric oxide sensor based on carbon fiber covered with nickel porphyrin layer deposited using optimized electropolymerization procedure

Electropolymerization regime of meso-tetrakis(3-methoxy-4-hydroxyphenyl) porphyrin is optimized to yield films possessing both electrocatalytical and permselective properties towards nitric oxide oxidation. The sensor composed of electrochemically oxidized carbon fiber, covered solely with nickel porphyrin derivative layer electropolymerized using our method, is characterized by high selectivity towards nitrite (1:600), ascorbate (1:8000) and dopamine (>1:80), determined by constant potential amperometry at 830 mV (vs. Ag/AgCl). Selectivity for ascorbate and dopamine as well as detection limit for NO (1.5 nM at S/N=3) is 5-10 times better than parameters usually reported for Nafion coated porphyrinic sensors. Nafion coating can further enhance selectivity properties as well as aids to the stability of the sensors' responses.

Seasonal changes of immunocompetence and parasitism in chub (Leuciscus cephalus), a freshwater cyprinid fish

Seasonal variation of water characteristics, predominantly temperature, is considered to strongly affect fish physiology and immunology. In nature, this variation directly influences the life cycle especially in fish parasites, but the infection of parasites is also altered by the host immune response. This study is aimed to analyze the seasonal changes in selected physiological and immunological parameters, the latter a potential measure of fish immunocompetence. Moreover, the seasonal changes in metazoan parasite infection were investigated, and the potential associations between fish physiology, immunocompetence, and parasitism were estimated. No differences in gender were recognized for immunological parameters. The significant differences in the spleen-somatic index were found among fish samples of different seasons indicating higher investment in spleen size in April (after winterizing) and August (post-breeding with low gonado-somatic index [GSI]). The significant seasonal differences in erythrocyte and leukocyte cell counts, as well as in phagocyte count affecting respiratory burst, were recorded. The general trend of leukocyte composition was similar in all seasons investigated; however, the changes in proportion of different neutrophilic cells were reported. The parasite diversity and the infection parameters in parasite communities were highest in spring and early summer. When comparing parasite abundance in infracommunities among seasons, the statistically highest values were observed in April and June for Monogenea, in April and November for Acanthocephala, and in April for Cestoda. The positive correlations between GSI and the parasite abundance of groups with higher infection parameters were found in males. Moreover, the positive association between Monogenea as the dominant parasite group and respiratory burst was observed. The higher investment in condition and the seasonal variation in GSI were associated with a decrease immune function measured by spleen size or leukocyte cell count especially for males suggesting the seasonal energy allocation between immune function and somatic or reproductive investment.

The influence of wine polyphenols on reactive oxygen and nitrogen species production by murine macrophages RAW 264.7

The aim was to study the antioxidant properties of four wine polyphenols (flavonoids catechin, epicatechin, and quercetin, and hydroxystilbene resveratrol). All three flavonoids exerted significant and dose-dependent scavenging effects against peroxyl radical and nitric oxide in chemical systems. The scavenging effect of resveratrol was significantly lower. All polyphenols decreased production of reactive oxygen species (ROS) by RAW264.7 macrophages. Only quercetin quenched ROS produced by lipopolysaccharide-stimulated RAW264.7 macrophages incubated for 24 h with polyphenols. Quercetin and resveratrol decreased the release of nitric oxide by these cells in a dose-dependent manner which corresponded to a decrease in iNOS expression in the case of quercetin. In conclusion, the higher number of hydroxyl substituents is an important structural feature of flavonoids in respect to their scavenging activity against ROS and nitric oxide, while C-2,3 double bond (present in quercetin and resveratrol) might be important for inhibition of ROS and nitric oxide production by RAW 264.7 macrophages.

Phagocyte-derived oxidants and plasma antioxidants in haemodialysed patients

OBJECTIVE

Oxidative stress is one of the important complications occurring in haemodialysis. The aim of the study was to determine haemodialysis-induced changes in oxidative burst of phagocytes and the antioxidative properties of plasma.

METHODS

Twenty-seven patients and 50 healthy controls were examined. Oxidative burst of phagocytes and plasma antioxidative potential were measured luminometrically. Concentrations of major plasma antioxidants (vitamin E, bilirubin and uric acid) were also determined.

RESULTS

Phagocyte chemiluminescence was higher in patients before haemodialysis compared with that in controls and decreased after haemodialysis compared with predialysis status. A significant increase in plasma antioxidative potential and uric acid was found in patients before haemodialysis. These parameters decreased after haemodialysis compared with both predialysis and control values.

CONCLUSIONS

The higher generation of phagocyte-derived oxidants and the decline in plasma antioxidative properties after haemodialysis confirm insufficient antioxidant defence in patients with chronic renal failure.

In vitro Effect of Carvedilol on Professional Phagocytes

AIM

Superfluous reactive nitrogen and oxygen species generation is implicated in the damage of tissues at sites of inflammation where activated neutrophils and macrophages are involved. This study was conducted to investigate whether the beneficial effects of carvedilol involve modulation of respiratory burst, degranulation-myeloperoxidase release and inducible nitric oxide synthase (iNOS) expression.

METHODS

Spectrophotometry and chemiluminescence were used to evaluate the effect of carvedilol on opsonized zymosan (0.5 mg/ml)- or N-formyl-methionyl-leucyl-phenyl-alanine (fMLP, 0.1 micromol/l)-stimulated superoxide generation and myeloperoxidase release in human neutrophils. Western blot analysis was used for iNOS expression and Griess reagent for nitric oxide production in RAW 264.7 macrophages (lipopolysaccharide (0.1 microg/ml) stimulated).

RESULTS

Carvedilol (10 and 100 micromol/l) significantly decreased opsonized zymosan- and fMPL-stimulated superoxide generation and myeloperoxidase release. Carvedilol (100 micromol/l) enhanced the effect of wortmannin (50 nmol/l), a specific inhibitor of 1-phosphatidylinositol 3-kinase and decreased iNOS expression and nitric oxide production.

CONCLUSION

Carvedilol appears to have a non-specific effect on membranes and to interfere with the phospholipase D signaling pathway, with subsequent inhibition of reactive oxygen species generation and myeloperoxidase release, without affecting iNOS expression.

Effect of carvedilol on reactive oxygen species and enzymes linking innate and adaptive immunity

OBJECTIVES

Neutrophils and macrophages are critical components of our innate host defenses. They are a potential source of nitric oxide (NO) and superoxide, known to play an important role in many physiological processes including defense, immune and inflammatory responses. Myeloperoxidase (MPO), a major NO scavenger and a marker of oxidative stress, as well as increased inducible nitric oxide synthase (iNOS) expression, may affect the NO-superoxide balance, critical for cellular redox balance in the cardiovascular system at physiologic conditions. The effect of carvedilol was studied on stimulated superoxide generation, MPO release and iNOS expression in phagocytes by using receptor operating stimuli [N-formyl-Met-Leu-Phe (FMLP), lipopolysaccharide (LPS) and specific inhibitors (wortmannin, propranolol).

METHODS

Superoxide generation was measured as superoxide dismutase inhibitable reduction of cytochrome c (550 nm), MPO activity as the oxidation of o-dianisidine in the presence of hydrogen peroxide in a spectrophotometer Hewlet Packard 8452 A (463 nm). Expression of iNOS (Western-blot analysis) in RAW 264.7 cell line (murine macrophages) was stimulated by lipopolysaccharide (LPS).

RESULTS

Carvedilol dose-dependently decreased superoxide generation and MPO release from intact neutrophils stimulated by FMLP. In the highest concentration tested, carvedilol pronounced the effect of wortmannin [inhibitor of phospholipase D (PLD) regulatory pathway] and significantly decreased LPS stimulated iNOS expression in RAW 264.7 cell line.

CONCLUSION

The conceivable cumulative non-specific membrane effect of carvedilol and its effect on PLD signalling pathway contribute to the decrease of both superoxide generation and MPO release, thus supporting the restoration of NO-superoxide balance.

Alterations in plasma antioxidants during reperfusion of the ischemic small intestine in rats

The aim of this study was to evaluate the contribution of three plasma antioxidants (albumin, uric acid, SH groups) to the plasma total peroxyl radical-trapping antioxidant capacity (TRAP) in 2 and 4 h of intestinal reperfusion in rats. TRAP increased significantly both after 2 and 4 h of reperfusion. Neither albumin nor SH groups contributed significantly to this increase. TRAP was strongly influenced by the increase in uric acid concentration and also probably by the cell destruction caused by oxidative stress. Since the TRAP increase was accompanied by an increase in the level of thiobarbituric acid reactive substances (TBARS, a marker of lipid peroxidation), we can conclude that even such a large increase in TRAP is not sufficient to prevent the progression of lipid peroxidation and oxidative stress.

Blood phagocyte activation during open heart surgery with cardiopulmonary bypass

Open heart surgery with a cardiopulmonary bypass (CPB) is associated with a systemic inflammatory response which significantly contributes to adverse postoperative complications. The purpose of this study was to characterize the activation of blood phagocytes during open heart surgery with CPB. Blood samples were collected during and up to 24 h after surgery. The production of reactive oxygen species (ROS) in whole blood, the expression of surface molecules by blood phagocytes and complement activity in the plasma were determined. A cDNA microarray analysis of leukocyte RNA profile of genes was performed related to the inflammatory response. Activation of the complement was already observed at the beginning of CPB. This was followed by an increase in the neutrophil number and in both spontaneous and opsonized zymosan-activated ROS production after the onset of reperfusion. The activation of blood phagocytes was affirmed by changes in surface receptors involved in the adhesion and migration of leukocytes (CD11b, CD62L and CD31). Gene arrays also confirmed the activation of leukocytes 4 h after reperfusion. In conclusion, open heart surgery with a cardiopulmonary bypass was found to be associated with a rapid and pronounced activation of blood phagocytes and complement activation which was partly independent at the onset of CPB.

[Determination of the antioxidant activity of potential scavengers of nitric oxide]

Nitrogen oxide is a relatively stable, highly reactive radical, which develops in the organism by oxidation of the guanidine nitrogen of the amino acid L-arginine by the action of NO-synthase with the development of L-citrulline. It participates in a number of physiological and pathological processes. The difference between the physiological and pathological concentration of nitrogen oxide is very small, and for that reason we search for suitable methods of its determination and the substances influencing the level of nitrogen and thus decreasing its overproduction. Testing of scavenger activity against NO was performed by the method following Griess (spectrophotometric determination of nitrites as the oxidation products of NO), which was compared with the HPLC (high-performance liquid chromatography) method developed by the present authors. The antiradical effect of the compounds being assayed (acetylsalicylic acid, piracetam, paracetamol, serotonin, stobadin dihydrochloride, 5-hydroxy-L-tryptophan, N-acetyl-L-cysteine, L-glutathion, and N-acetyl-DL-penicillamine) against NO was compared with the so-called total antioxidant activity--TRAP (total radical-trapping antioxidant parameter), which corresponds to the capability to trap peroxyl radicals. On the basis of the obtained data, piracetam and acetylsalicylic acid show no antioxidant activity, paracetamol shows probably moderate scavenging action against nitrogen oxide, and other compounds tested (primarily 5-hydroxy-L-tryptophan, serotonin, stobadin) are strong antioxidants against both NO and peroxyl radical.

Silkworm (Bombyx mori) hemocytes do not produce reactive oxygen metabolites as a part of defense mechanisms

To investigate whether hemocytes of Bombyx mori (Lepidoptera) larvae produce reactive oxygen species (ROS) as part of the oxidative killing of invading pathogens, the production of ROS was measured as a luminol- and lucigenin-enhanced chemiluminescence of unstimulated or stimulated (zymosan particles, phorbol myristate acetate, calcium ionophore, rice starch or Xenorhabdus nematophila) hemolymph. No detectable ROS production was found. The spontaneous and activated ROS production measured with hemocytes, i.e. under the conditions when the antioxidative potential of hemolymph plasma was eliminated, was again undetectable. Likewise, ROS production by isolated hemocytes was observed by spectrophotometric (NBT test, cytochrome c assay) and fluorimetric (using dihydrorhodamine and hydroethidine probes) methods. Hence none of the experimental approaches used indicated the production of ROS by hemocytes of B. mori larvae as part of their immune response.

Comparison of the bioluminescence ofPhotorhabdus species and subspecies type strains

Natural bioluminescence of all recently accepted Photorhabdus species and subspecies type strains (bacterial symbionts of entomopathogenic nematodes) was measured using a commercial luminometer; optimum conditions for the measurement were described. Cultures emitted reliably measurable bioluminescence with characteristic level and kinetics for each strain. Bioluminescence of all strains was significantly higher at 37 than at 25 degrees C at the beginning of the measurement, no effect of bacterial concentration on the intensity of bioluminescence was observed. The technique can provide reliable and quick information for the determination of Photorhabdus taxons.

Time course of leukocyte response and free radical release in an early reperfusion injury of the superior mesenteric artery

The sequence of changes in circulating immune cells and in free radical production was studied during the small intestine reperfusion. Rat small intestine ischemia/reperfusion was induced by a 45 min superior mesenteric artery occlusion followed by a 4-hour reperfusion. Samples of peripheral blood were collected every 20 min during reperfusion. While the number of polymorphonuclear leukocytes increased significantly both in the sham-operated controls and the experimental group (about 400 per cent at the end of reperfusion), a decrease in lymphocyte counts to 60 per cent was observed in the experimental group only. Although there were no changes in the counts of total T lymphocytes, a significant reduction in B cell counts was observed. Flow-cytometrical measurements showed no changes in the Tc subpopulation, while the Th subpopulation increased in the experimental group only. Free radical generation in blood (luminometric measurements) increased gradually and reached an eight-fold level by the end of reperfusion in both groups. Thus, it has been shown that the increase in free radical production is mainly due to the increased number of polymorphonuclear leukocytes mobilized already at the initial stages of reperfusion. The reduction in B lymphocyte population is probably due to homing mechanisms

Interaction of polyunsaturated fatty acids and sodium butyrate during apoptosis in HT-29 human colon adenocarcinoma cells

BACKGROUND

Dysregulation of the balance between cell growth and death in the colonic epithelium is associated with cancer promotion. Understanding how cell death in this self-renewing tissue is regulated and how it is influenced by interaction of specific dietary components, especially fat and fibre, could lead to improved treatment and prevention strategies for cancer.

AIM OF THE STUDY

The effects of two types of polyunsaturated fatty acids (PUFAs)--arachidonic (AA, 20:4, n-6) or docosahexaenoic (DHA, 22:6, n-3)--on the response of human colon adenocarcinoma HT-29 cells to sodium butyrate (NaBt) were investigated.

METHODS

The parameters reflecting cell proliferation and cell death were studied together with oxidative response, mitochondrial membrane potential (MMP) and changes of selected regulatory molecules associated with cell cycle (p27(Kip1) and p21(Cip1/WAF1)) and apoptosis (caspase-3, caspase-9, poly (ADP-ribose) polymerase--PARP, Bcl-2, Bax, Bak,Mcl-1).

RESULTS

We demonstrated that pre-treatment with either AA or DHA attenuated cell cycle arrest caused by NaBt which is associated with modulation of p27(Kip1), but not p21(Cip1/WAF1) protein expression. On the other hand, PUFAs sensitised HT-29 cells to NaBt-induced apoptosis. An increased amount of floating cells and cells in the subG(0)/G(1) population was associated with increased reactive oxygen species production, lipid peroxidation, decrease of MMP, activation of caspase-3 and -9, PARP cleavage, and decrease in the expression of antiapoptotic Mcl-1 protein. The observed effects were modulated by the addition of a protein synthesis inhibitor, cycloheximide, and partially reversed by the antioxidant Trolox.

CONCLUSIONS

PUFAs may have beneficial effects in the colon enhancing apoptosis induced by NaBt. Alteration of cell membrane lipid composition and potentiation of oxidative processes accompanied by changes in mitochondria followed by stimulation of apoptotic cascade components play a role in these effects.

Effect of Stobadine on Opsonized Zymosan Stimulated Generation of Reactive Oxygen Species in Human Blood Cells

To predict more precisely the effect of stobadine, a pyridoindole antioxidant agent, in the whole organism, we studied its effect on opsonized zymosan-stimulated free radical generation in whole blood, on superoxide generation in the mixture of PMNL : platelets (1:50), as well as on superoxide generation and myeloperoxidase release in isolated PMNL. Without stimulation, stobadine had no effect on reactive oxygen species (ROS) generation and myeloperoxidase release. Stobadine in a concentration of 10 or 100 micromol/l significantly decreased luminol-enhanced chemiluminescence in opsonized zymosan-stimulated whole blood. In concentrations of 10 and 100 micromol/l, it reduced myeloperoxidase release from isolated neutrophils. Stobadine significantly decreased superoxide generation in isolated neutrophils in 100 micromol/l concentration. Its effect was much less pronounced in the mixture of neutrophils and platelets in the ratio close to physiological conditions (1:50). Our results suggest that stobadine might exert a beneficial effect in diseases or states where superfluous ROS generation could be deleterious.

The effect of intestinal ischemia duration on changes in plasma antioxidant defense status in the rats

The purpose of this study was to follow up the changes in antioxidative adaptive mechanisms induced by various periods of small intestinal ischemia in Wistar rats. The superior mesenteric artery was occluded for 15, 30, 45, 60 and 90 min. After the respective ischemic intervals, a reperfusion was set for 120 min. Samples of the serum and intestinal mucosa were taken at the end of ischemia or at the end of reperfusion. Total radical-trapping antioxidant parameter (TRAP) of the serum and the oxidative burst of neutrophils were evaluated using luminol-enhanced chemiluminescence. Individual antioxidants in the serum and the concentration of thiobarbituric acid reactive substances (TBARs) in both serum and intestinal mucosa were measured spectrophotometrically. Increased activation of circulating neutrophils was found after the reperfusion irrespective of the duration of ischemia. TRAP of the serum was increased at the end of the ischemia lasting from 30 to 90 min. This effect was further enhanced by the subsequent reperfusion period. Ascorbate and urate contributed considerably to the TRAP value especially after reperfusion following 60 and 90 min of ischemia. On the other hand, no significant changes in albumin and bilirubin serum concentrations were observed. Contrary to the mobilized antioxidative mechanisms, increased lipid peroxidation was observed in both serum and mucosa samples.

The effect of intestinal ischemia duration on changes in plasma antioxidant defense status in rats

The purpose of this study was to follow up the changes in antioxidative adaptive mechanisms induced by various periods of small intestinal ischemia in Wistar rats. The superior mesenteric artery was occluded for 15, 30, 45, 60 and 90 min. After the respective ischemic intervals, a reperfusion was set for 120 min. Samples of the serum and intestinal mucosa were taken at the end of ischemia or at the end of reperfusion. Total radical-trapping antioxidant parameter (TRAP) of the serum and the oxidative burst of neutrophils were evaluated using luminol-enhanced chemiluminescence. Individual antioxidants in the serum and the concentration of thiobarbituric acid reactive substances (TBARs) in both serum and intestinal mucosa were measured spectrophotometrically. Increased activation of circulating neutrophils was found after the reperfusion irrespective of the duration of ischemia. TRAP of the serum was increased at the end of the ischemia lasting from 30 to 90 min. This effect was further enhanced by the subsequent reperfusion period. Ascorbate and urate contributed considerably to the TRAP value especially after reperfusion following 60 and 90 min of ischemia. On the other hand, no significant changes in albumin and bilirubin serum concentrations were observed. Contrary to the mobilized antioxidative mechanisms, increased lipid peroxidation was observed in both serum and mucosa samples.

IL-10 does not affect oxidative burst and expression of selected surface antigen on human blood phagocytes in vitro

Cytokines play a major role in the control of inflammatory responses, participate in the regulation of blood phagocyte activities and as such are used for immunomodulatory therapy. In the present study, the influence of IL-10 on human blood phagocyte activity in the presence/absence of IL-6, IL-8 and TNF-a was tested in vitro. Our research analyzed the effects of cytokines on the production of reactive oxygen species measured by chemiluminescence and flow cytometry, and on the expression of surface molecules (CD11b, CD15, CD62L, CD31) measured by flow cytometry. IL-10 had no inhibitory effect on reactive oxygen species production and the expression of any examined adhesion molecule by resting or stimulated blood phagocytes within 3 h of incubation. Conversely, TNF-, IL-6, and IL-8 increased reactive oxygen species production and the expression of CD11b and CD15 on both neutrophils and monocytes and decreased the expression of CD62L. These priming effects of the tested pro-inflammatory cytokines were not affected by IL-10. The obtained results suggest that IL-10 does not directly control blood phagocyte activation. These results also provide better information about the contribution of IL-6, IL-8 and TNF- to the regulation of blood phagocyte-mediated inflammatory processes.

IL-10 does not affect oxidative burst and expression of selected surface antigen on human blood phagocytes in vitro

Cytokines play a major role in the control of inflammatory responses, participate in the regulation of blood phagocyte activities and as such are used for immunomodulatory therapy. In the present study, the influence of IL-10 on human blood phagocyte activity in the presence/absence of IL-6, IL-8 and TNF-alpha was tested in vitro. Our research analyzed the effects of cytokines on the production of reactive oxygen species measured by chemiluminescence and flow cytometry, and on the expression of surface molecules (CD11b, CD15, CD62L, CD31) measured by flow cytometry. IL-10 had no inhibitory effect on reactive oxygen species production and the expression of any examined adhesion molecule by resting or stimulated blood phagocytes within 3 h of incubation. Conversely, TNF-alpha, IL-6, and IL-8 increased reactive oxygen species production and the expression of CD11b and CD15 on both neutrophils and monocytes and decreased the expression of CD62L. These priming effects of the tested pro-inflammatory cytokines were not affected by IL-10. The obtained results suggest that IL-10 does not directly control blood phagocyte activation. These results also provide better information about the contribution of IL-6, IL-8 and TNF-alpha to the regulation of blood phagocyte-mediated inflammatory processes.

[Antioxidative action of pyridoindoles and N-(alkoxyphenyl)-2-(2-oxo-1-aza-1-cycloalkyl) acetamides in biological, enzymatic and chemical systems]

The luminol-enhanced chemiluminiscence method was used to investigate the antioxidative activity of N-(alkoxyphenyl)-2-(2-oxo-1-aza-1-cykloalkyl) acetamides studied as potential cognitive enhancers and stobadine acylderivatives which form prodrugs with increased lipophilicity. The effect on the production of reactive oxygen metabolites by activated leukocytes was studied in vitro. Furthermore, the total radical-trapping antioxidant parameter was evaluated as the peroxyl radical-trapping capacity and the scavenging effect on the superoxide anion radical (generated by the enzymatic system hypoxanthine/xanthine oxidase) and on the hydroxyl radical (produced in Fenton reaction) were studied. The antioxidative properties of the tested substances were compared with that of stobadine dihydrochloride. Only stobadine and its butyrylderivative have been demonstrated to possess free radical scavenging activity in all systems. Cinnamoylstobadine inhibited only the leukocyte chemiluminiscence activity. The potential cognitive enhancers did not show any antioxidant activity.

Inhibition of FMLP-stimulated neutrophil chemiluminescence by blood platelets increased in the presence of the serotonin-liberating drug chloroquine

INTRODUCTION

Previously, we reported that human blood platelets significantly decreased the concentration of reactive oxygen species (chemiluminescence) produced by Ca(2+)-ionophore-stimulated neutrophils and that the reduction was partially mediated by serotonin liberated from platelets during their activation. The aim of the present study was to investigate whether platelet inhibition can occur independently of serotonin liberation and whether it can be pharmacologically enhanced.

MATERIALS AND METHODS

Chemiluminescence was measured after stimulation of human neutrophils with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in the presence of luminophore luminol. Concentration of platelet serotonin was estimated fluorometrically.

RESULTS

Platelets, added to neutrophils in the physiological cell ratio 50:1, decreased neutrophil chemiluminescence by 47%. The inhibition was not accompanied with liberation of platelet serotonin and rose after addition of chloroquine to platelet-neutrophil samples. In the absence of platelets, this drug did not affect neutrophil chemiluminescence. Chloroquine actively liberated serotonin; amine concentrations found in platelet supernatants were sufficient to inhibit neutrophil chemiluminescence.

CONCLUSIONS

The presented results indicate that unstimulated platelets decreased neutrophil chemiluminescence by a serotonin-independent mechanism, yet their inhibitory effect could be enhanced pharmacologically through chloroquine-induced serotonin liberation.

Perioperative and postoperative course of cytokines and the metabolic activity of neutrophils in human cardiac operations and heart transplantation

OBJECTIVES

The purpose of this study was to compare systemic inflammatory responses after heart transplantation and nontransplant cardiac operations, both involving cardiopulmonary bypass with a focus on the role of polymorphonuclear leukocytes.

METHODS

Lipid peroxidation, blood phagocyte radical production, and interleukin 6, 8, and 10 plasma concentrations during surgical intervention and on the first and seventh postoperative days were evaluated in patients undergoing heart transplantation (n = 24) and in patients not undergoing transplantation (n = 30).

RESULTS

Levels of interleukin 6, 8, and 10 increased in both groups of patients during early reperfusion. They normalized within the first postoperative day in the transplant group, whereas the nontransplant group's interleukin 6 and 8 levels remained increased on the seventh day after the operation. Interleukin 10 plasma levels were higher in the heart transplant group during reperfusion. Lipid peroxidation was increased after the operation in both groups of patients. Phagocyte activity was enhanced at reperfusion and at all other sampling times only in the nontransplant group. On the other hand, phagocyte activity oscillated around the preoperative level during heart transplantation, or it was even decreased.

CONCLUSION

Both cardiac operations involving heart transplantation and those without transplantation are associated with increased oxidative stress and an enhanced production of proinflammatory and anti-inflammatory cytokines. Differences in interleukin 10 production and phagocyte activity could be caused mainly by the immunosuppressive therapy in heart transplant operations.

Influence of polysulfone and hemophan hemodialysis membranes on phagocytes

The aim of the study was to compare the effect of hemophane and polysulfone membranes on the phagocyte-derived production of reactive oxygen species (ROS) as well as on neutrophil CD11b and CD62L expression in patients undergoing regular hemodialysis. The effects of hemodialysis membranes were also studied in in vitro conditions after coincubating them with differentiated HL-60 cells. ROS production was measured using chemiluminometric and flow cytometric methods. Expression of CD11b, CD62L and mitochondrial membrane potential were detected by monoclonal antibodies and by the JC-1 fluorescent probe, respectively. Depressed ROS production was observed in patients already before dialysis. Further decrease in ROS production and an increase in CD11b expression were observed especially in patients after hemophan hemodialysis. Decreased ROS production and increased CD11b expression were observed also after incubation of HL-60 cells with hemophan membranes. Mitochondrial membrane potential dropped only after incubating cells with hemophan membranes proving its more serious adverse effects in comparison with the polysulfone membrane. In conclusion, deleterious effects of hemodialysis on the metabolic activity of phagocytes were proved. Combining chemiluminescent and flow cytometric methods for the detection of ROS production and determining mitochondrial membrane potential can be useful tools for the analysis of material biocompatibility.

Effect of H1-antagonist Dithiaden on human PMN-leukocyte aggregation and chemiluminescence is stimulus-dependent

OBJECTIVE AND DESIGN

Contradictory data published on histamine-PMN leukocyte interactions stimulated us to study to the role of histamine and H1-antagonist Dithiaden in generation of reactive oxygen species (ROS) and aggregation of human neutrophils.

METHODS AND MATERIALS

Whole blood or isolated PMN-leukocytes were exposed in a dose-dependent way to histamine or H1-antagonist Dithiaden and subsequently stimulated. Whole blood was stimulated with opsonised zymosan (OZ). Isolated cells were stimulated with membrane stimuli (OZ, N-formyl-methionyl-leucyl-phenylalanine--fMLP), or membrane bypassing stimuli (Ca2+-ionophore A23187, phorbol-myristate-acetate--PMA). The luminol-enhanced chemiluminescence (CL) was measured separately (whole blood) in a luminometer or simultaneously with neutrophil aggregation in a whole blood lumiaggregometer.

RESULTS

Depending on the concentration used, Dithiaden" was 1.5- to 25.0-times more effective in inhibiting activated CL of whole blood than histamine. In isolated neutrophils both histamine and Dithiaden inhibited OZ- and A23187-stimulated CL dose-dependently, with potentiation observed after stimulation with PMA and fMLP. Histamine did not alter aggregation with any of the stimuli tested. Dithiaden inhibited A23187-, OZ- and PMA-stimulated PMN-leukocytes but potentiated fMLP-induced aggregation of isolated neutrophils. Simultaneous application of Dithiaden and histamine abolished the effect of Dithiaden on fMLP-stimulated CL.

CONCLUSIONS

Dithiaden, depending on the stimuli applied, inhibited human neutrophils, both isolated or in whole blood, more markedly than histamine. The inhibition of aggregation and CL was dose- and stimulus-dependent. Histamine administered simultaneously abolished the effect of Dithiaden on fMLP-stimulated PMN-leukocytes. It seems likely that the interaction of Dithiaden with neutrophils operated both at an extra- and intracellular level.