Modulatory effect of chiral nonsteroidal anti-inflammatory drugs on apoptosis of human neutrophils

Polymorphonuclear neutrophils (PMNs) are short-lived leukocytes that die by apoptosis. Although PMNs are crucial in the defense against infection, they have been implicated in the pathogenesis of tissue injury observed in inflammatory diseases. The induction or prevention of PMN apoptosis is currently discussed as a key event in the control of inflammation. Caspase-3 activation is the first step in the execution phase of apoptosis. In the study, effect of racemic mixtures and enantiomers of 2-arylpropionic acid derivatives: ketoprofen, flurbiprofen (FBP), and (+)-S-naproxen and 2-arylbutyric acid: indobufen on apoptosis activation via caspase-3 and phosphatidylserine (PS) translocation (annexin-V binding) in human neutrophils in vitro has been investigated. Caspase-3 activation was detected by Western blotting, fluorometric assay of DEVD-AMC cleavage, and flow cytometry with carboxyfluorescein (FAM) labeled caspase inhibitor. PMNs were isolated and cultured up to 24 h. The chiral nonsteroidal anti-inflammatory drugs (NSAIDs) were found to modulate human PMN apoptosis in a dose- and time-dependent manner. The greater activation of caspase was found at 75-150 mu g/ml concentration of racemates as well enantiomers, especially for FBP, whereas NSAIDs at smaller quantities (15 mu g/ml) were inactive. At concentration of 75 mu g/ml, NSAIDs increased the rate of PS externalization in PMA-stimulated and non-stimulated neutrophils. Additionally, no cytotoxic effect of the NSAIDs was observed at concentration up to 75 mu g/ml that induce apoptosis. Regulation of caspase activity by NSAIDs may represent a potent target to trigger apoptosis and resolve inflammatory disorders.