Characterization of Suicidal Erythrocyte Death (Eryptosis) in Dogs

Suicidal erythrocyte death (eryptosis) is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface following a Ca²⁺ entry in the cell. Eryptosis is stimulated by increased cytosolic Ca²⁺ ([Ca²⁺]i), oxidative stress, energy depletion, or high osmotic shock. Eryptosis signaling includes p38 mitogen-activated protein kinase (MAPK), caspases, casein kinase 1 (CK1), janus kinase 3 (JAK3), and protein kinase C (PKC). Dog and human erythrocytes have different characteristics, for example, dog erythrocytes lack Na⁺/K⁺- ATPase activity. Whether eryptosis occurs in dog erythrocytes in an analogous way as that in humans remains unclear. Eryptosis in dogs has not been investigated. This study aimed to explore which stimulator and signaling molecules are involved in eryptosis in healthy dog erythrocytes.

Erythrocytes were isolated from 10 dogs, and eryptosis was stimulated by oxidative stress with tert-butyl hydroperoxide (tBOOH), high osmotic shock with excessive sucrose condition, energy depletion with minus glucose condition, and high [Ca²⁺]i with ionomycin. Phosphatidylserine exposure was estimated using annexin V binding. Erythrocyte volume and [Ca²⁺]i were measured by forward scatter and Fluo3-fluorescence, respectively. In addition, the role of certain mediators was assessed using the following inhibitors to determine the detailed mechanisms of eryptosis in dog erythrocytes: p38MAPK, caspase family, CK1, JAK3, and PKC inhibitors.

All eryptosis-inducing factors resulted in phosphatidylserine exposures, except for ionomycin. In addition, the erythrocyte volume increased with ionomycin and tBOOH but decreased with excessive sucrose and minus glucose condition. All treatments increased [Ca²⁺]i. Furthermore, WH1-P154 and chelerythrine significantly blunted the increase of annexin V binding erythrocytes following the tBOOH treatment.

Eryptosis in dogs is triggered by oxidative stress, hyperosmotic shock, and energy depletion. It is suggested that JAK3 and PKC play an important role in eryptosis following an oxidative stress in dog erythrocytes.