Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10739893 | Free Radical Biology and Medicine | 2005 | 13 Pages |
Abstract
In ambient aerosols, ultrafine particles (UFP) and their agglomerates are considered to be major factors contributing to adverse health effects. Reactivity of agglomerated UFP of elemental carbon (EC), Printex 90, Printex G, and diesel exhaust particles (DEP) was evaluated by the capacity of particles to oxidize methionine in a cell-free in vitro system for determination of their innate oxidative potential and by alveolar macrophages (AMs) to determine production of arachidonic acid (AA), including formation of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), reactive oxygen species (ROS), and oxidative stress marker 8-isoprostane. EC exhibiting high oxidative potential induced generation of AA, PGE2, LTB4, and 8-isoprostane in canine and human AMs. Printex 90, Printex G, and DEP, showing low oxidative capacity, still induced formation of AA and PGE2, but not that of LTB4 or 8-isoprostane. Aging of EC lowered oxidative potential while still inducing production of AA and PGE2 but not that of LTB4 and 8-isoprostane. Cellular ROS production was stimulated by all particles independent of oxidative potential. Particle-induced formation of AA metabolites and ROS was dependent on mitogen-activated protein kinase kinase 1 activation of cytosolic phospholipase A2 (cPLA2) as shown by inhibitor studies. In conclusion, cPLA2, PGE2, and ROS formation was activated by all particle types, whereas LTB4 production and 8-isoprostane were strongly dependent on particles' oxidative potential. Physical and chemical parameters of particle surface correlated with oxidative potential and stimulation of AM PGE2 and 8-isoprostane production.
Keywords
Mkk1cPLA2BELLTB4PGE2DEPsPLA2AMSTXB25-LOESRiPLA2Ca2+-independent phospholipase A2COX5-Lipoxygenase8-Isoprostanep38 MAPKcyclooxygenasephospholipase A2Secretory phospholipase A2bromoenol lactonethromboxane B2Oxidative stressUltrafine particlesDiesel exhaust particlesFree radicalsElectron spin resonancecytosolic phospholipase A2Leukotriene B4Alveolar macrophagesChemiluminescenceLipid mediatorsmitogen-activated protein kinase kinase 1p38 mitogen-activated protein kinaseProstaglandin E2elemental carbon
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Authors
Ingrid Beck-Speier, Niru Dayal, Erwin Karg, Konrad L. Maier, Gabriele Schumann, Holger Schulz, Manuela Semmler, Shinji Takenaka, Kurt Stettmaier, Wolf Bors, Andy Ghio, James M. Samet, Joachim Heyder,