title: Stimulation of Erythrocyte Cell Membrane Scrambling by C-Reactive Protein.
abstract: BACKGROUND
  Eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and phosphatidylserine-translocation, is triggered by fever and inflammation. Signaling includes increased cytosolic Ca2+-activity ([Ca2+]i), caspase activation, and ceramide. Inflammation is associated with increased plasma concentration of C-reactive protein (CRP). The present study explored whether CRP triggers eryptosis.
  
  
  METHODS
  Phosphatidylserine abundance at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ceramide abundance and caspase-3-activity utilizing FITC-conjugated antibodies. Moreover, blood was drawn from patients with acute appendicitis (9♀,11♂) and healthy volunteers (10♀,10♂) for determination of CRP, blood count and phosphatidylserine.
  
  
  RESULTS
  A 48h CRP treatment significantly increased the percentage of annexin-V-binding cells (≥5µg/ml), [Ca2+]i (≥5µg/ml), ceramide (20µg/ml) and caspase-activity (20µg/ml). Annexin-V-binding was significantly blunted by caspase inhibitor zVAD (10µM). The percentage of phosphatidylserine-exposing erythrocytes in freshly drawn blood was significantly higher in appendicitis patients (1.83±0.21%) than healthy volunteers (0.81±0.09%), and significantly higher following a 24h incubation of erythrocytes from healthy volunteers to patient plasma than to plasma from healthy volunteers. The percentage of phosphatidylserine-exposing erythrocytes correlated with CRP plasma concentration.
  
  
  CONCLUSIONS
  C-reactive protein triggers eryptosis, an effect at least partially due to increase of [Ca2+]i, increase of ceramide abundance and caspase activation.
authors.forename: Majed
authors.initials: M
authors.lastname: Abed
authors.forename: Christian
authors.initials: C
authors.lastname: Thiel
authors.forename: Syeda T
authors.initials: ST
authors.lastname: Towhid
authors.forename: Kousi
authors.initials: K
authors.lastname: Alzoubi
authors.forename: Sabina
authors.initials: S
authors.lastname: Honisch
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
authors.forename: Alfred
authors.initials: A
authors.lastname: Königsrainer
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D001064:Appendicitis / Q000097:blood / Q000473:pathology; D002097:C-Reactive Protein / Q000032:analysis / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D016022:Case-Control Studies; D053148:Caspase 3 / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D002518:Ceramides / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D000072817:Eryptosis / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects*; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D010718:Phosphatidylserines / Q000378:metabolism; D055815:Young Adult
chemical_list: D002518:Ceramides; D010718:Phosphatidylserines; D002097:C-Reactive Protein; D053148:Caspase 3; D002118:Calcium
keywords: Appendicitis; C-reactive protein; Calcium; Cell volume; Eryptosis; Inflammation; Phosphatidylserine