title: Enhanced apoptotic death of erythrocytes induced by the mycotoxin ochratoxin A.
abstract: BACKGROUND
  The mycotoxin ochratoxin A, an agent responsible for endemic Balkan nephropathy is known to trigger apoptosis and thus being toxic to several organs including the kidney. The mechanisms involved in ochratoxin A induced apoptosis include oxidative stress. Sequelae of ochratoxin intoxication include anemia. Similar to apoptosis of nucleated cells, erythrocytes may undergo suicidal cell death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling resulting in phosphatidylserine-exposure at the cell surface. Eryptosis could be triggered by Ca2+ -entry through oxidant sensitive unspecificcation channels increasing cytosolic Ca2+ activity ([Ca2+]i). The Ca2+ -sensitivity of cell membrane scrambling could be enhanced and eryptosis thus triggered by ceramide. The removal of suicidal erythrocytes may lead to anemia. Moreover, eryptotic erythrocytes could adhere to the vascular wall thus impeding microcirculation. The present study explored, whether ochratoxin A stimulates eryptosis.
  
  
  METHODS
  Fluo3-fluorescence was utilized to determine [Ca2+]i, forward scatter to estimate cell volume, annexin-V-binding to identify phosphatidylserine-exposing cells, fluorescent antibodies to detect ceramide formation and hemoglobin release to quantify hemolysis. Moreover, adhesion to human vascular endothelial cells (HUVEC) was determined utilizing a flow chamber.
  
  
  RESULTS
  A 48 h exposure to ochratoxin A was followed by significant increase of Fluo3-fluorescencei (≥ 2.5 µM), increase of ceramide abundance (10 µM), decrease of forward scatter (≥ 5 µM) and increase of annexin-V-binding (≥ 2.5 µM). Ochratoxin A exposure slightly but significantly enhanced hemolysis (10 µM). Ochratoxin (10 µM) enhanced erythrocyte adhesion to HUVEC. Removal of extracellular Ca2+ significantly blunted, but did not abrogate ochratoxin A-induced annexin V binding.
  
  
  CONCLUSIONS
  Ochratoxin A triggers suicidal erythrocyte death or eryptosis, an effect partially but not fully due to stimulation of Ca2+ -entry.
authors.affiliation: Department of Physiology, University of Tuebingen, Gmelinstraße 5, 72076 Tuebingen, Germany.
authors.forename: Kashif
authors.initials: K
authors.lastname: Jilani
authors.forename: Adrian
authors.initials: A
authors.lastname: Lupescu
authors.forename: Mohanad
authors.initials: M
authors.lastname: Zbidah
authors.forename: Majed
authors.initials: M
authors.lastname: Abed
authors.forename: Nazneen
authors.initials: N
authors.lastname: Shaik
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D004912:Erythrocytes / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D009183:Mycotoxins / Q000494:pharmacology*; D009793:Ochratoxins / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects
chemical_list: D002518:Ceramides; D009183:Mycotoxins; D009793:Ochratoxins; C025589:ochratoxin A; D002118:Calcium