The
HIV protease inhibitor,
nelfinavir, primarily used for the treatment of
HIV infections, has later been shown to be effective in various
infectious diseases including
malaria.
Nelfinavir may trigger mitochondria-independent cell death. Erythrocytes may undergo eryptosis, a mitochondria-independent suicidal cell death characterized by cell shrinkage and
phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include oxidative stress and increase of cytosolic Ca2+-activity ([Ca2+]i). During
malaria, accelerated death of infected erythrocytes may decrease
parasitemia and thus favorably influence the
clinical course of the disease. In the present study,
phosphatidylserine abundance at the cell surface was estimated from
annexin V binding, cell volume from forward scatter, reactive
oxidant species (ROS) from
2',7'-dichlorodihydrofluorescein diacetate (
DCFDA) fluorescence, and [Ca2+]i from Fluo3-fluorescence. A 48 h treatment of human erythrocytes with
nelfinavir significantly increased the percentage of
annexin-V-binding cells (≥5µg/mL), significantly decreased forward scatter (≥2.5µg/mL), significantly increased ROS abundance (10 µg/mL), and significantly increased [Ca2+]i (≥5 µg/mL). The up-regulation of
annexin-V-binding following
nelfinavir treatment was significantly blunted, but not abolished by either addition of the
antioxidant N-acetylcysteine (1 mM) or removal of extracellular Ca2+. In conclusion, exposure of erythrocytes to
nelfinavir induces oxidative stress and Ca2+ entry, thus leading to suicidal erythrocyte death characterized by erythrocyte shrinkage and erythrocyte membrane scrambling.