Jc. Pfau et al., A COMPARISON OF THE EFFECTS OF LIPOPOLYSACCHARIDE AND CERAMIDE ON ARACHIDONIC-ACID METABOLISM IN THP-1 MONOCYTIC CELLS, Cellular immunology (Print), 186(2), 1998, pp. 147-153
Ceramide has been shown to be an important second messenger for signal
transduction in cells of myeloid lineage. Studies have suggested that
lipopolysaccharide (LPS) may activate signaling pathways by mimicking
the action of ceramide. We explored this hypothesis with THP-1 cells
in terms of the effects of LPS, C2 ceramide, and sphingomyelinase on a
rachidonic acid metabolism as measured by the release of radiolabeled
eicosanoids. Arachidonic acid metabolism was activated by both LPS and
ceramide. However, the ratio of prostaglandin E-2 to leukotriene C-4
was 10 times higher in cells treated with LPS than with ceramide. Unli
ke LPS, prior exposure to ceramide did not desensitize the cells to su
bsequent challenge with either LPS or ceramide, nor could LPS desensit
ize the cells to challenge with ceramide. The results suggest that, al
though LPS and ceramide may share signaling components, the signaling
pathways are not identical. (C) 1998 Academic Press.