Stimulation of Suicidal Erythrocyte Death by Lipoxygenase Inhibitor Bay-Y5884

Abstract

The prostaglandin PGE₂, a metabolite of the cyclooxygenase pathway, activates Ca²⁺-permeable cation channels in erythrocyte cell membranes leading to entry of Ca²⁺ with subsequent eryptosis, i.e. cell shrinkage, breakdown of phosphatidylserine (PS) asymmetry and membrane blebbing, all features typical for apoptosis in nucleated cells. PS exposing cells are recognized by macrophages, engulfed, degraded and thus cleared from circulating blood. The present study explored whether the specific lipoxygenase inhibitor Bay-Y5884 influences eryptosis. As determined by competitive ELISA, Bay-Y5884 (20 µM) enhanced the release of PGE₂ from human erythrocytes. According to whole-cell patch-clamp, Bay-Y5884 (20 µM) activated nonselective cation channels. The effect of Bay-Y5884 on cation channels was abolished by the cyclooxygenase inhibitor diclophenac (10 µM). Bay-Y5884 (30-40 µM) significantly increased erythrocyte free Ca²⁺ concentration and PS exposure as analyzed in flow cytometry by Fluo3 fluorescence and annexin-V binding, respectively. PS exposure triggered by 20 µM (but not by 40 µM) Bay-Y5884 was blunted by cyclooxygenase inhibitors acetylsalicylic acid (50 µM) and diclophenac (10 µM). In conclusion, the lipoxygenase inhibitor Bay-Y5884 enhances erythrocyte PGE₂ formation with subsequent activation of non-selective cation channels, Ca²⁺ entry and phospholipid scrambling.