Reactive Oxygen Species Production In Blood Research Articles

Distinct behavior of bovine-associated staphylococci species in their ability to resist phagocytosis and trigger respiratory burst activity by blood and milk polymorphonuclear leukocytes in dairy cows

Mastitis affects a high proportion of dairy cows and is still one of the greatest challenges faced by the dairy industry. Staphylococcal bacteria remain the most important cause of mastitis worldwide. We investigated how distinct staphylococcal species evade some critical host defense mechanisms, which may dictate the establishment, severity, and persistence of infection and the outcome of possible therapeutic and prevention interventions. Thus, the present study investigated variations among distinct bovine-associated staphylococci in their capability to resist phagocytosis and to trigger respiratory burst activity of blood and milk polymorphonuclear neutrophil leukocytes (PMNL) in dairy cows. To do so, PMNL of 6 primiparous and 6 multiparous dairy cows were used. A collection of 38 non-aureus staphylococci (NAS) and 12 Staphylococcus aureus were included. The phagocytosis and intracellular reactive oxygen species (ROS) production by blood and milk PMNL were analyzed by flow cytometry. Phagocytosis, by both blood and milk PMNL, did not differ between S. aureus and NAS as a group, although within-NAS species differences were observed. Staphylococcus chromogenes (a so-called milk-adapted NAS species) better resisted phagocytosis by blood PMNL than the so-called environmental (i.e., Staphylococcus fleurettii) and opportunistic (i.e., Staphylococcus haemolyticus) NAS species. Otherwise, S. haemolyticus was better phagocytosed by blood PMNL than S. aureus, S. fleurettii, and S. chromogenes. No influence of the origin of the isolates within the staphylococci species in the resistance to phagocytosis by blood and milk PMNL was found. Overall, both S. aureus and NAS did not inhibit intracellular ROS production in blood and milk PMNL. Non-aureus staphylococci induced fewer ROS by milk PMNL than S. aureus, which was not true for blood PMNL, although species-specific differences in the intensity of ROS production were observed. Staphylococcus chromogenes induced more blood PMNL ROS than S. fleurettii and S. haemolyticus, and as much as S. aureus. Conversely, S. chromogenes induced fewer milk PMNL ROS than S. aureus. The origin of the isolates within the staphylococci species did not affect the ROS production by blood and milk PMNL. In conclusion, our study showed differences in staphylococci species in evading phagocytosis and triggering ROS production, which may explain the ability of some staphylococci species (i.e., S. aureus and S. chromogenes) to cause persistent infection and induce inflammation.

Abstract 272: Chronic Hyperlipidemia Alters the Population of Endothelial Progenitor Cells in Bone Marrow and Peripheral Circulation via Both ROS-dependent and Independent Mechanisms

Background/Aims: Bone marrow (BM)-derived endothelial progenitor cells (EPCs) make significant contribution to the function and integrity of vasculature. The number of EPCs is significantly decreased in hyperlipidemic patients. Reactive oxygen species (ROS) and oxidative stress were considered an important mechanism for the development of atherosclerosis in hyperlipidemia. The present study was to determine the role of ROS production in the changes of EPC population in chronic hyperlipidemia. Methods and Results: EPC numbers and ROS formation in BM and blood were determined in wild-type (WT) male C57BL/6 mice and hyperlipidemic LDL receptor knockout (LDLR-/-) mice with high fat diet for 4 months. Intracellular blood, extracellular BM and blood ROS production was significantly increased in hyperlipidemic LDLR-/- mice that was effectively blocked with N-acetylcysteine treatment. Hyperlipidemia produced complex changes in EPC populations in BM and blood. The c-Kit+/CD31+ cell number was significantly decreased in BM and blood, and the numbers of CD34+/CD133+ cells and Sca-1+/Flk-1+ cells were significantly decreased in blood without change in BM, which were not affected by inhibition of ROS production. Interestingly, blood CD34+/Flk-1+ cell number was significantly increased in hyperlipidemic mice that was prevented when ROS formation was inhibited. Conclusions: Chronic hyperlipidemia produced significant and complex changes in EPC populations in both BM and circulation through both ROS-dependent and ROS-independent mechanisms in mice.

Green tea extract supplementation ameliorates CCl4-induced hepatic oxidative stress, fibrosis, and acute-phase protein expression in rat

We evaluated the long-term effects of green tea extract (GTE) supplementation on oxidative stress, biliary acute phase protein expression, and liver function in CCl(4)-induced chronic liver injury. We evaluated the antioxidant activity of GTE in comparison with those of vitamin C, vitamin E, and β-carotene in vitro by using an ultrasensitive chemiluminescence analyzer. Chronic liver injury was induced by intraperitoneally administering carbon tetrachloride (CCl(4)) (1 mL/kg body weight, twice weekly) to female Wistar rats for 8 weeks. The effects of low (4 mg/kg body weight per day) and high (20 mg/kg body weight per day) doses of intragastric GTE on CCl(4)-induced liver dysfunction and fibrosis were examined by measuring the bile and blood reactive oxygen species levels and biochemical parameters by using Western blot and two-dimensional polyacrylamide gel electrophoresis techniques. GTE has greater scavenging activity against O(2)(-), H(2)O(2), and Hypochlorous acid (HOCl) in vitro than vitamin C, vitamin E, and β-carotene do. In vivo, CCl(4) markedly increased bile and blood reactive oxygen species production, lipid accumulation, number of infiltrated leukocytes, fibrosis, hepatic hydroxyproline content, and plasma alanine aminotransferase and aspartate aminotransferase activities, and reduced plasma albumin levels. Two-dimensional polyacrylamide gel electrophoresis revealed that CCl(4) increased the acute-phase expression of six biliary proteins and decreased hepatic B-cell lymphoma 2 (Bcl-2), catalase, and CuZn superoxide dismutase protein expression. GTE supplementation attenuated CCl(4)-enhanced oxidative stress, levels of biochemical parameters, pathology, and acute-phase protein secretion, and preserved antioxidant/antiapoptotic protein expression. GTE supplementation attenuates CCl(4)-induced hepatic oxidative stress, fibrosis, acute phase protein excretion, and hepatic dysfunction via the antioxidant and antiapoptotic defense mechanisms.

Mechanism of Blood Coagulation by Non-Thermal Atmospheric Pressure Dielectric Barrier Discharge Plasma.

Introduction: Non-thermal atmospheric pressure dielectric barrier discharge plasma (cold plasma due to its non-thermal nature) has emerged as a promising new tool in medicine due to its ability to coagulate blood rapidly, sterilize tissue without thermal damage and induce apoptosis in malignant tissue. The potential clinical applicability of non-thermal plasma lies in its use in controlling intra-operative microvascular bleeding in organs and in endoscopy. Non-thermal plasma can also be used to treat superficial wounds in trauma through hemostasis while simultaneously inducing surface sterilization. We have previously demonstrated that non-thermal plasma hastens blood coagulation on cut tissue surfaces and accelerates clot formation in whole blood five times faster than natural coagulation. A series of experiments were undertaken to investigate the mechanism of coagulation by non-thermal plasma.Methods/Results: We initially postulated that changes in pH and/or extracellular Ca2+ as a possible mechanism for non-thermal plasma mediated coagulation. Our studies however showed no significant changes in pH or Ca2+ in treated blood. Thermal energy triggered coagulation as seen in conventional electrocautery as well as electric field effects were eliminated as other possible mechanisms. The role of reactive oxygen species (ROS) in coagulation was studied, as non-thermal plasma is known to produce ROS in water. ROS production in blood was blocked with sodium pyruvate, an ROS scavenger, and the results showed no effect on non-thermal plasma induced coagulation. Specific effects of non-thermal plasma on citrated blood samples revealed extremely rapid coagulation with surface gel formation, while clotting studies (PT, aPTT) performed on the plasma beneath the gel revealed consumption of coagulation factors. Examination of the clot formed by non-thermal plasma using Scanning Electron Microscopy (SEM) showed platelet activation with pseudopodia formation, aggregation, and fibrin formation. The effects of non-thermal plasma on fibrinogen solution treated at physiologic pH showed a change in opacity suggesting clot formation. Dynamic Light Scattering (DLS) was used to measure particle size distributions of treated and untreated fibrinogen solutions. Treated fibrinogen exhibited a multi-modal distribution of sizes with the largest size corresponding to the size of fibrin-like structures. This suggests that non-thermal plasma may coagulate blood by the conversion of fibrinogen to fibrin. Evaluation of albumin, our control protein given its non-involvement in coagulation, showed no changes upon exposure to non-thermal plasma.Conclusion: Non-thermal plasma likely promotes coagulation by enhancing the physiologic coagulation process through direct activation of fibrinogen as well as platelet activation and aggregation. Future research will further evaluate the mechanisms of non-thermal plasma induced platelet activation and effects on other proteins in the coagulation cascade. This will lead to newer insights into the physiological aspects of coagulation and clinical utility of non-thermal plasma in medicine.