ASPIRIN AND SALICYLATE SUPPRESS POLYMORPHONUCLEAR APOPTOSIS DELAY MEDIATED BY PROINFLAMMATORY STIMULI

NEGROTTO, SOLEDAD; MALAVER, ELISA; PACIENZA, NATALIA; D’ATRI, LINA P; URDINEZ, PATRICIO; POZNER, ROBERTO G; GOMEZ, RICARDO M; SCHATTNER, MIRTA

Roma, Italia

Simposio; XIV International Symposium on Atherosclerosis; 2006

Objectives: Aspirin (ASA) and sodium salicylate (NaS) are widely drugs used to treat inflammation. During inflammation, several factors prolong polymorphonuclear leukocytes (PMN) survival. We examined whether salicylates interfere with PMN apoptosis. Methods: Apoptosis was assessed by cell staining with acridine orange and ethidium bromide (fluorescence microscopy) or with propidium iodide or annexin-V (flow cytometry). IkB alpha degradation was measured by western blot. Phagocytosis was quantified by May Grunwald-Giemsa. Results: PMN preincubation with ASA or NaS suppressed LPS (0.5ug/ml) (EC50: 1.35mM and 1.53mM) or IL-1 alpha (1.39mM and 1.28mM, n=6) prolonged PMN survival through inhibition of IkB alpha degradation. Although ASA and NaS did not trigger PMN death (1-3mM, n=5), both drugs significantly increased Zymosan-mediated apoptosis (15, 22, 28% of control, 1 and 3mM ASA or NaS, n=4). Indomethacin and ibuprofen did not inhibit LPS antiapoptotic activity (n=4). The cytokines-prolonged PMN survival was no longer observed in PMN from donors who had ingested ASA (2g, n=7). Using a thioglycolate-induced peritonitis model, we observed that in ASA or NaS-treated mice there was not only a decrease in the number of total cells recruited (1.3±0.3, 1.7±0.4 x106 cells/ml) but also an increase in both, percentage of apoptotic PMN (28±5, 23±2%) and enhanced macrophages phagocytosis (45±4, 48±6%) compared with controls (3.3±0.3, 9±2, 17±5 respectively, n=5). Conclusion: Another mechanism by which salicylates exert its antiinflammatory action is by shortening PMN life span.