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Critical role of acidic sphingomyelinase in murine hepatic ischemia‐reperfusion injury
Author(s) -
Llacuna Laura,
Marí Montserrat,
GarciaRuiz Carmen,
FernandezCheca José C.,
Morales Albert
Publication year - 2006
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.21285
Subject(s) - ceramide , acid sphingomyelinase , sphingomyelin phosphodiesterase , sphingomyelin , liver injury , pharmacology , sphingolipid , reperfusion injury , ischemia , chemistry , biology , endocrinology , medicine , biochemistry , apoptosis , cholesterol
The molecular mechanisms of hepatic ischemia/reperfusion (I/R) damage are incompletely understood. We investigated the role of ceramide in a murine model of warm hepatic I/R injury. This sphingolipid induces cell death and participates in tumor necrosis factor (TNF) signaling. Hepatic ceramide levels transiently increased after the reperfusion phase of the ischemic liver in mice, because of an early activation of acidic sphingomyelinase (ASMase) followed by acid ceramidase stimulation. In vivo administration of an ASMase inhibitor, imipramine, or ASMase knockdown by siRNA decreased ceramide generation during I/R, and attenuated serum ALT levels, hepatocellular necrosis, cytochrome c release, and caspase‐3 activation. ASMase‐induced ceramide generation activated JNK resulting in Bim L phosphorylation and translocation to mitochondria, as the inhibition of ASMase by imipramine prevented these events. In contrast, blockade of ceramide catabolism by N‐oleyolethanolamine (NOE), a ceramidase inhibitor, enhanced ceramide levels and potentiated I/R injury compared with vehicle‐treated mice. Pentoxifylline treatment prevented TNF upregulation and ASMase activation. Furthermore, 9 of 11 mice treated with imipramine survived 7 days after total liver ischemia, compared with 4 of 12 vehicle‐treated mice, whereas 8 of 8 NOE‐treated mice died within 2 days of total liver ischemia. In conclusion , ceramide generated from ASMase plays a key role in I/R‐induced liver damage, and its modulation may be of therapeutic relevance. (H EPATOLOGY 2006.)