The Effects Hyperoxia On The NADPH Oxidase Activity And The Restraint Of Gliotoxin In Human Neutrophils In Vitro

Neutrophils play an essential role in the body's innate defense mechanismand is one damage of the inflammatory response. Upon activation neutrophilsproduce A great deal of superoxide radical species, a process known as the respiratoryburst. During this, neutrophils engulf bacteria and kill tumor cells. Sometimes it causetissue damage, such as oxidative stress in the ischaemia-reperfusion heart and brain.The reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, acritical enzyme in respiratory burst, have been always observed in studies aroundoxidative stress. Oxygen therapy is given to the critically ill, while prolongedexposure to high concentrations of oxygen will result in ventilator-inducedlung injury. Reactive oxygen species (ROS) from the NADPH oxidase may contributeto this injury. Gliotoxin, produced by Blastomyces albicans, has a variety of toxiceffects such as suppression of antigen processing and induction of apoptosis.Gliotoxin inhibits the activity of NADPH oxidase and reveals potential way used indiseases caused by oxidative stress. The purpose of our study was to observe theeffects of hyperoxia on the NADPH oxidase activity of neutrophils in vitro.Neutrophils were isolated from the whole blood obtained from healthyvolunteers by Kobayashi's method, then suspended in phosphate buffersolution(PBS) and divided into two groups. In experiment group, neutrophilswas pretreated with hyperoxia for 30 min, and exposed to phorbol 12-myristate13-acetate(PMA) and Gliotoxin. In control group, neutrophils exposed to PMA andtreated with Gliotoxin. Data of random block design are expressed asmeans±S.E.M and treated with Analysis of variance (ANOVA).Multiple comparisons between groups were made by the Student-Newman-keuls.The Neutrophils exposed to hyperoxia and PMA have many deposition of denseparticles observed with electron microscope and fluorescence microscope. Whilethe specimens of PMA group take second place, the specimens of the hyperoxia+Gliotoxin+PMA group have little deposition of dense particles. And the specimens of Gliotoxin+PMA group have no deposition of dense particles. Thefluorescence microscope show 4624.2045±324.5822; 2484.8409±41.1539;1256.2045±76.5873 and 808.1136±34.0449. They tallies with the front andan associated probability of p＜0.01 was considered to be significant.In our study, the activity of NADPH oxidase increased in humanneutrophils protreated with hyperoxia. And exposure to PMA results in enhancement.Gliotoxin reduced this effect.In the finality, the problems requiring further studies arediscussed.