Premium
De novo C 16 ‐ and C 24 ‐ceramide generation contributes to spontaneous neutrophil apoptosis
Author(s) -
Seumois Grégory,
Fillet Marianne,
Gillet Laurent,
Faccinetto Céline,
Desmet Christophe,
François Cédric,
Dewals Benjamin,
Oury Cécile,
Vanderplasschen Alain,
Lekeux Pierre,
Bureau Fabrice
Publication year - 2007
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.0806529
Subject(s) - ceramide , apoptosis , ceramide synthase , lipid signaling , biology , sphingomyelin , fumonisin b1 , microbiology and biotechnology , biochemistry , enzyme , membrane , botany , mycotoxin
Neutrophils rapidly undergo spontaneous apoptosis following their release from the bone marrow. Although central to leukocyte homeostasis, the mechanisms that regulate neutrophil apoptosis remain poorly understood. We show here that apoptosis of cultured neutrophils is preceded by a substantial increase in the intracellular levels of 16 and 24 carbon atom (C 16 ‐ and C 24 )‐ceramides, which are lipid second messengers of apoptosis and stress signaling. Treatment of neutrophils with fumonisin B 2 , a selective inhibitor of the de novo pathway of ceramide synthesis, prevented accumulation of C 16 ‐ and C 24 ‐ceramides. Moreover, fumonisin B 2 significantly reduced caspase‐3, ‐8, and ‐9 activation and apoptosis in these cells. Conversely, 3‐O‐methylsphingomyelin and fantofarone, which are specific inhibitors of neutral and acid sphingomyelinases, respectively, neither inhibited C 16 ‐ and C 24 ‐ceramide production nor decreased the apoptosis rate in neutrophils, indicating that in these cells, ceramides are not generated from membrane sphingomyelin. Further experiments showed that increasing endogenous C 16 ‐ and C 24 ‐ceramide levels by using DL‐threo‐1‐phenyl‐2‐palmitoylamino‐3‐morpholino‐1‐propanol and (1S,2R)‐D‐erythro‐2‐(N‐myristoylamino)‐1‐phenyl‐1‐propanol, two inhibitors of ceramide metabolism, enhances caspase‐3, ‐8, and ‐9 activity and increases neutrophil apoptosis. Similarly, apoptosis was induced rapidly when synthetic C 16 ‐ and/or C 24 ‐ceramides were added to neutrophil cultures. Finally, GM‐CSF, a cytokine that delays neutrophil apoptosis, abrogated C 16 ‐ and C 24 ‐ceramide accumulation totally in cultured neutrophils, whereas Fas ligation accelerated apoptosis in these cells without affecting de novo ceramide production. We conclude that de novo generation of C 16 ‐ and C 24 ‐ceramides contributes to spontaneous neutrophil apoptosis via caspase activation and that GM‐CSF exerts its antiapoptotic effects on neutrophils, at least partly through inhibition of ceramide accumulation.