title: N-Acetylcysteine Amide Protects Against Oxidative Stress-Induced Microparticle Release From Human Retinal Pigment Epithelial Cells.
abstract: OBJECTIVE
  Oxidative stress is a major factor involved in retinal pigment epithelium (RPE) apoptosis that underlies AMD. Drusen, extracellular lipid- and protein-containing deposits, are strongly associated with the development of AMD. Cell-derived microparticles (MPs) are small membrane-bound vesicles shed from cells. The purpose of this study was to determine if oxidative stress drives MP release from RPE cells, to assess whether these MPs carry membrane complement regulatory proteins (mCRPs: CD46, CD55, and CD59), and to evaluate the effects of a thiol antioxidant on oxidative stress-induced MP release.
  
  
  METHODS
  Retinal pigment epithelium cells isolated from human donor eyes were cultured and treated with hydrogen peroxide (H2O2) to induce oxidative stress. Isolated MPs were fixed for transmission electron microscopy or processed for component analysis by flow cytometry, Western blot analysis, and confocal microscopy.
  
  
  RESULTS
  Transmission electron microscopy showed that MPs ranged in diameter from 100 to 1000 nm. H2O2 treatment led to time- and dose-dependent elevations in MPs with externalized phosphatidylserine and phosphatidylethanolamine, known markers of MPs. These increases were strongly correlated to RPE apoptosis. Oxidative stress significantly increased the release of mCRP-positive MPs, which were prevented by a thiol antioxidant, N-acetylcysteine amide (NACA).
  
  
  CONCLUSIONS
  This is the first evidence that oxidative stress induces cultured human RPE cells to release MPs that carry mCRPs on their surface. The levels of released MPs are strongly correlated with RPE apoptosis. N-acetylcysteine amide prevents oxidative stress-induced effects. Our findings indicate that oxidative stress reduces mCRPs on the RPE surface through releasing MPs.
authors: Kyle A
authors: KA
authors: Carver
authors: Dongli
authors: D
authors: Yang
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015153:Blotting, Western; D018958:CD55 Antigens / Q000378:metabolism; D018957:CD59 Antigens / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008297:Male; D051916:Membrane Cofactor Protein / Q000378:metabolism; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism
chemical_list: C497857:CD46 protein, human; D018958:CD55 Antigens; D018957:CD59 Antigens; D051916:Membrane Cofactor Protein; D016877:Oxidants; C051590:CD59 protein, human; C487056:N-Acetylcysteinamide; D006861:Hydrogen Peroxide; D000111:Acetylcysteine