Bromfenvinphos induced suicidal death of human erythrocytes

• Bromfenvinphos triggers shrinkage of human erythrocytes.
• Bromfenvinphos triggers erythrocyte cell membrane scrambling.
• Bromfenvinphos increases cytosolic Ca2 + concentration.
• Bromfenvinphos increases reactive oxygen species abundance.
• Bromfenvinphos thus induces eryptosis, the suicidal erythrocyte death.

The organophosphorus pesticide bromfenvinphos ((E,Z)-O,O-diethyl-O-[1-(2,4-dichlorophenyl)-2-bromovinyl] phosphate) has been shown to decrease hematocrit and hemoglobin levels in blood presumably by triggering oxidative stress of erythrocytes. Oxidative stress is known to activate erythrocytic Ca2 + permeable unselective cation channels leading to Ca2 + entry and increase of cytosolic Ca2 + activity ([Ca2 +]i), which in turn triggers eryptosis, the suicidal death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. The present study explored, whether and how bromfenvinphos induces eryptosis. To this end, phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, hemolysis from hemoglobin release, [Ca2 +]i from Fluo3-fluorescence, and ROS formation from DCFDA dependent fluorescence. As a result, a 48 hour exposure of human erythrocytes to bromfenvinphos (≥ 100 μM) significantly increased the percentage of annexin-V-binding cells, significantly decreased forward scatter, significantly increased Fluo3-fluorescence, and significantly increased DCFDA fluorescence. The effect of bromfenvinphos on annexin-V-binding and forward scatter was significantly blunted, but not abolished by removal of extracellular Ca2 +. In conclusion, bromfenvinphos triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect in part due to stimulation of ROS formation and Ca2 + entry.

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