Correlation of oxidative stress parameters and inflammatory markers in coronary artery disease patients

OBJECTIVES

In addition to many traditional risk factors for coronary artery disease (CAD) development, enhanced oxidative stress and inflammation are serious conditions that may also be classified as novel risk factors. In the present study, we assessed the relationship between several parameters of oxidative stress status [malonaldehyde (MDA), superoxide anion (O(2)(-)) and plasma and erythrocyte superoxide dismutase (SOD) activities] with high sensitivity C-reactive protein (hsCRP) and fibrinogen as inflammation markers.

DESIGN AND METHODS

Oxidative stress status parameters, inflammation markers and lipid status parameters were measured in 385 subjects [188 coronary heart disease (CHD) patients with angiographically diagnosed coronary artery disease (CAD), 141 patients with occlusion >50% in at least one major coronary artery (CAD+) and 47 patients with occlusion less than 50% (CAD-), and 197 CHD-free middle-aged subjects (the control group)].

RESULTS

The plasma MDA concentration and the level of O(2)(-) in plasma were significantly higher in combination with significantly lower SOD activity in the CAD+ group vs. the control group. By using multiple stepwise regression analysis, fibrinogen and hsCRP showed independent correlation with MDA. Binary logistic regression analysis indicated that both MDA and O(2)(-) were significantly associated with CAD development and adjustment for inflammatory markers weakened this association in the case of MDA.

CONCLUSIONS

The relationship between oxidative stress parameters and inflammatory species suggest their strong mutual involvement in atherosclerosis development that leads to CAD progression.

Singlet oxygen (1O(2)) disrupts platelet aggregates

INTRODUCTION

Important mediators of activated polymorphonuclear leukocytes (PMN) are the oxidants HOCl and chloramine, which generate the nonradical photon-emitting oxidant singlet oxygen (1O(2)). Since 1O(2) inhibits platelet aggregation, we became interested in a possible oxidant mediated reversibility of platelet aggregation.

METHODS

Chloramine T (CT) is a stable 1O(2) generator that mimics the natural chloramine N-chloro-taurine. Platelet-rich plasma (PRP) was incubated with CT 0-8 min after addition of the aggregation agonist (10 microM adenosine-5'-diphosphate, ADP, or 5 microg/ml collagen) and the aggregation was monitored. Platelet function was also analyzed by the platelet function analyzer, PFA-100. Fifty microliters of 200 micromol/l ADP was added to 400 microl PRP. After 1 min at 37 degrees C, 50 microl of 0 or 30 mmol/l CT was added, and after an incubation for 3 min at 37 degrees C, 50 microl of 25% glutaraldehyde was added. The samples were analyzed in a transmission microscope at x3000 and x7000 magnification.

RESULTS

Chloramines inhibit platelet function in PRP: about 1 mM CT suppresses 50% of the aggregatory capacity of thrombocytes in normal PRP (effective dose 50%, ED(50)=1 mM chloramine), which is identical to the ED(50) for CT in whole blood. The ADP- or collagen-induced platelet aggregation can be reversed by addition of CT: up to 2 min after the addition of ADP as the aggregation inducer, the aggregation is reversible to more than 70% by addition of a 1O(2) release-inducer (3 mM CT). In contrast, addition of CT 8 min after the addition of ADP results only in about 50% reversal of platelet aggregation. The electron microscopic images of platelets before ADP, after incubation for 4 min at 20 micromol/l ADP, after incubation for 1 min at 20 micromol/l ADP, and a further incubation for 3 min at 3 mmol/l CT demonstrate an ADP-dependent formation of platelet aggregates, which are disrupted by 1O(2) into the single platelets; a phenomenon comparable to the decomposition of a puzzle or the continental drift of the major earth plates. The morphology of oxidized and unoxidized platelets is similar.

CONCLUSION

This study demonstrates that 1O(2) inhibits and reverses platelet aggregation. The physiologic signal action and the direct anticoagulant action of 1O(2) might be a new principle for pharmacologic intervention in atherothrombosis.

Singlet oxygen quenching activity of human serum

Singlet oxygen is regarded as contributing to the pathogenesis of various diseases including light-induced skin disorders and inflammatory response. In this study, the correlation between singlet oxygen quenching activity (SOQA) of human serum and blood biochemistry or life-style was evaluated. Healthy volunteers were recruited and carried out a measurement of SOQA by using electron paramagnetic resonance (EPR) and a questionnaire survey about a smoking. It was demonstrated that major quenchers of singlet oxygen in serum are proteins, and small molecular anti-oxidants relatively play a minor role. SOQA of whole sera showed no correlation with protein concentration, but positively correlated with SOQA of small molecular fraction. In vitro studies demonstrated that the decrease of sulfhydryl groups by NO or superoxide significantly attenuated SOQA of albumin. Together, these results may imply that the underlying oxidative condition in each individual influences both small molecular antioxidant states and the sulfhydryl content of serum proteins. SOQA of sera from women with a smoking history was significantly lower compared to non-smoking women, suggesting that the smoking habit impaired the defense mechanism against singlet oxygen.

Generation of Singlet Oxygen Induces Phospholipid Scrambling in Human Erythrocytes

Maintenance of phospholipid asymmetry of the plasma membrane is essential for cells to prevent phagocytic removal or acceleration of coagulation. Photodynamic treatment (PDT), which relies on the generation of reactive oxygen species to achieve inactivation of pathogens, might be a promising approach in the future for decontamination of red blood cell concentrates. To investigate whether PDT affects phospholipid asymmetry, erythrocytes were illuminated in the presence of 1,9-dimethyl-methylene blue (DMMB) as photosensitizer and subsequently labeled with FITC-labeled annexin V. This treatment resulted in about 10% annexin V positive cells, indicating exposure of phosphatidylserine (PS). Treatment of erythrocytes with N-ethylmaleimide (NEM) prior to illumination, to inhibit inward translocation of PS via the aminophospholipid translocase, resulted in enhanced PS exposure, while treatment with H(2)O(2) (previously shown to inhibit phospholipid scrambling) greatly diminished PS exposure, indicating the induction of phospholipid scrambling by PDT. Only erythrocytes illuminated in the presence of DMMB showed translocation of NBD-phosphatidylcholine (NBD-PC), confirming scrambling induction. Double label experiments indicated that PS exposure does not occur without concurrent scrambling activity. Induction of scrambling was only moderately affected by Ca(2+) depletion of the cells. In contrast, scavengers of singlet oxygen were found to prevent phospholipid scrambling induced by PDT. The results of this study show that phospholipid scrambling is induced in human erythrocytes by exposure to singlet oxygen.

Reduced intracellular oxygen radical production in whole blood leukocytes from COPD patients and asymptomatic smokers

RATIONALE AND OBJECTIVES

COPD is characterized by irreversible airflow obstruction. It has, however, become clear that COPD also is a systemic disease. In the present study, we sought to investigate its impact on different peripheral leukocyte subpopulations that are recognized as important effector cells in the lung tissue.

METHODS

We enrolled 20 patients with stable, moderate COPD (FEV1, 33 to 69%). Ten asymptomatic smokers and 10 nonsmokers served as control groups. Flow cytometry and whole blood analysis were used to minimize unwanted ex vivo modulation. Oxidative burst and adhesion molecule mobilization were analyzed on freshly drawn cells and after in vitro activation.

MEASUREMENTS AND MAIN RESULTS

We found reduced oxidative burst in neutrophils, monocytes, and eosinophils after in vitro stimulation with tumor necrosis factor (TNF) and the bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) in both COPD patients and asymptomatic smokers as compared to nonsmoking control subjects. Vascular involvement was determined as increased soluble intercellular adhesion molecule-1 (sICAM-1) in the COPD group. There were no differences in adhesion molecule expression among the three groups. However, in COPD patients who had smoked the same morning prior to blood sampling, we found a reduced ability to mobilize adhesion molecule CD11b after TNF plus fMLP activation in all investigated cell types. "Acute" smoking did not significantly alter respiratory burst measurements.

CONCLUSIONS

Both COPD patients and asymptomatic smokers have increased levels of sICAM-1 and a reduced intracellular oxidative burst in vitro, indicating a vascular endothelial activation and a possible state of refractoriness in circulating phagocytes in COPD. Although expression and mobilization of adhesion molecules were similar between groups, the acute smoke effect on CD11b points out the value of information on smoking behavior when analyzing function of peripheral inflammatory cells in a smoking population.

Rapid on-site dual optical system to measure specific reactive oxygen species (O2-• and OCl-) in a tiny droplet of whole blood

Oxidative stress has been implicated in various disorders and controlling it would be important for healthy life. We have developed a new optical system for easily and accurately measuring oxidative stress in whole blood. It is optimized for simultaneously detecting reactive oxygen species (ROS) and highly reactive ROS (hROS), elicited mostly by white blood cells in a few microliters of blood. Results obtained by using this system show at least four important findings. 1) chemiluminescence of MCLA was confirmed to be attributable to O2-•. 2) PMA-stimulated cells released O2-• longer and more slowly than fMLP-stimulated ones. 3) fluorescence produced by APF oxidation was confirmed to be attributable to hROS, mostly OCl-, produced by myeloperoxidase. 4) the generation of OCl- was found to be a slower process than the O2-• generation. We also conducted pilot studies of oxidative stress in healthy volunteers.

Serum resistance to singlet oxygen in patients with diabetes mellitus in comparison to healthy donors

Diabetes mellitus causes endothelial injury through oxidative stress involving reactive oxygen species and peroxides as well as inflammation, both of which consume antioxidant defenses. Singlet oxygen ((1)O(2)) is produced by leukocytes during inflammatory and biochemical reactions and deactivated by producing reactive oxygen species and peroxides. To determine whether serum was capable of deactivating (1)O(2), we triggered a photo reaction in sera from 53 healthy donors and 52 diabetic patients. Immediately after light delivery, dichlorofluorescein was added and then its fluorescence was recorded. The mean capacity of (1)O(2) or secondary oxidant deactivation was reduced in patients with diabetes mellitus. Hemolysis reduced deactivation of (1)O(2)-induced secondary oxidants in both healthy and diabetic patients. Body mass index, age, platelet counts, and blood cell numbers exerted a nonlinear influence. High levels of glycated hemoglobin were associated with an increased deactivation of oxidative species, whereas high-density lipoprotein cholesterol, total cholesterol, and the total cholesterol to high-density lipoprotein cholesterol ratio decreased the serum deactivation capacity. Oral antidiabetics bore no influence on deactivation, which was restored by insulin in women. Deactivation capacity was lower in women, who had half the complications found in men, suggesting that, with more severe diabetes mellitus, protection was maintained against complications. Resistance to (1)O(2) should be considered during the monitoring of diabetes mellitus.

Singlet Oxygen Enhances Intrinsic Thrombolysis: The Intrinsic Oxidative Clot Lysis Assay (INOXCLA)

Granulocytes are important cells of inflammation and cellular thrombolysis. They produce urokinase (u-PA) and chloramines. In this study, u-PA/chloramine—mediated fibrinolysis is imitated in a microtiter-plate. Seventy-five microliters plasma are incubated with 50 μL 50% Pathromtin SL, 6% BSA, and 38 mM CaCl2 for 30 minutes (37°C). Then, 50 μL 10 mM chloramine-T in PBS are added. After 30 minutes (37°C), 50 μL 0, 100, or 10 IU/mL u-PA in 6% BSA-PBS are added and the turbidity is determined at 405 nm after 0, 3, or 16 hours. Clot lysis was increased more than tenfold by 0.5 to 1 μmoles chloramine (ED50 after 3h = about 0.25 μmoles = 2mM final concentration). The normal range for the present intrinsic oxidative clot lysis assay (INOXCLA) is 100% ± 25% (MV ± SD; 100 relative % of norm; the normal lysis being 60 absolute %; CVs < 10%). Fifty percent lysis of adherent microclots occurred after 0.75 hours, 2 hours, 14 hours, 13 days, or 17 days when using 1000, 100, 10, 1, or 0 IU/mL u-PA reagent. If the u-PA activity is quenched by PAI-2, no clot lysis appears. Chloramines are important physiologic generators of nonradical excited singlet oxygen and enhance u-PA—mediated lysis of plasma clots. Based on the u-PA/chloramines coaction, a new global fibrinolysis assay has been derived.

Direct measurement of free radicals in the brain cortex and the blood serum after nociceptive stimulation in rats

The concentrations of ROS were measured in samples of the sensorimotor brain cortex and in the rat blood. We measured the following parameters: The six lines spectra, nitroxide radical, free hydroxyl radical and singleton oxygen. Their concentration was measured under physiological conditions, after the nociceptive stimulation and after the application of melatonin, both in normal and stimulated animals. In the brain cortex only the singleton oxygen decreased after the nociceptive stimulation, whereas the nitroxide radicals and six lines spectra increased. The free hydroxyl radicals did not change significantly. In the blood serum the six lines spectra and nitroxide radical increased, the concentration of the free hydroxyl radicals did not change. Melatonin increased both the hydroxyl and nitroxide radicals. There was a non-significant decrease in the six lines spectra. The estimation of ROS can be used as a tool for detecting metabolic changes and the consequences of different environmental influences, in our case the influence of nociception and melatonin.

[Nitric oxide system in blood of newborn infants at elevated risk of perinatal pathology]

The study was designed to evaluate activity of the blood nitric oxide (NO) system in newborns at high risk of perinatal pathology. The observed rise in NO production should be regarded as a compensatory and adaptive reaction facilitating the maintenance of microcirculation and hemodynamics in organs and their systems of newborn infants. The inter-relation and inter-dependence between NO levels and enzymatic activities (NOS, HP, O2-, ONOO-, and SOD) make up an integral pathogenetic mechanism determining severity and progress of affection of vitally important organs and systems as well as associated clinical symptoms in full-term and premature infants at high perinatal risk.