title: Reactive oxygen species produced up- or downstream of calcium influx regulate proinflammatory mediator release from mast cells: role of NADPH oxidase and mitochondria.
abstract: Earlier studies have demonstrated that mast cells produce reactive oxygen species (ROS), which play a role in regulating Ca(2+) influx, while in other cell types ROS are produced in a Ca(2+)-dependent manner. We sought to determine whether ROS are produced downstream of the extracellular Ca(2+) entry in mast cells. Thapsigargin (TG), a receptor-independent agonist, could evoke a robust burst of intracellular ROS. However, this response was distinct from the antigen-induced burst of ROS with respect to time course and dependence on Ca(2+) and phosphatidylinositol-3-kinase (PI3K). The antigen-induced ROS generation occurred immediately, while the TG-induced ROS generation occurred with a significant lag time (~2 min). Antigen but not TG caused extracellular release of superoxide (O(2)(*-))/hydrogen peroxide (H(2)O(2)), which was blocked by diphenyleneiodonium, apocynin, and wortmannin. A capacitative Ca(2+) entry resulted in the generation of O(2)(*-) in the mitochondria in a PI3K-independent manner. Blockade of ROS generation inhibited TG-induced mediator release. Finally, when used together, antigen and TG evoked the release of leukotriene C(4), tumor necrosis factor-alpha, and interleukin-13 as well as ROS generation synergistically. These results suggest that ROS produced upstream of Ca(2+) influx by NADPH oxidase and downstream of Ca(2+) influx by the mitochondria regulate the proinflammatory response of mast cells.
authors.affiliation: Division of Molecular Cell Immunology and Allergology, Advanced Medical Research Center, Nihon University Graduate School of Medical Sciences, Tokyo, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Inoue
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yoshimaru
authors.forename: Chisei
authors.initials: C
authors.lastname: Ra
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D006861:Hydrogen Peroxide / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism*; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D019255:NADPH Oxidases / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000941:Antigens; D018836:Inflammation Mediators; D017382:Reactive Oxygen Species; D013481:Superoxides; D019284:Thapsigargin; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D002118:Calcium