Korean J Physiol Pharmacol.  1998 Apr;2(2):241-249.

Study on the action by PAF on IL-1 modulation in alveolar macrophages: Involvement of endogenous arachidonate metabolites and intracellular Ca++ mobilization

• Lee J
• Kim WK
• Hah JS

Abstract

Platelet-activating factor (PAF) enhanced interleukin-1 (IL-1) activity by the interaction with a specific receptor in rat alveolar macrophages. In this study, we investigated the role of endogenous arachidonate metabolites and intracellular calcium mobilization in the PAF-induced IL-1 activity. Alveolar macrophages were preincubated with 5-lipoxygenase and cyclooxygenase inhibitors 30 min before the addition of PAF and lipopolysaccharide (LPS). After 24 h culture, IL-1 activity was measured in the supernate of sample using the thymocyte proliferation assay. Inhibition of 5-lipoxygenase by nordihydroguaiaretic acid and AA-861 completely blocked the PAF-induced enhancement of IL-1 activity with IC50 of 2 micrometer and 5 micrometer, respectively. In contrast, the inhibition of cyclooxygenase pathway by indomethacin and ibuprofen resulted in the potentiation in PAF-induced IL-1 activity with maximal effect at 1 micrometer and 5 micrometer, respectively. In addition, leukotriene B4 and prostaglandin E2 production were observed in PAF-stimulated alveolar macrophage culture. As could be expected, 5-lipoxygenase and cyclooxygenase inhibitors abolished PAFstimulated leukotriene B4 and prostaglandin E2 production, respectively. The effects of PAF on intracellular calcium mobilization in alveolar macrophages were evaluated using the calcium-sensitive dye fura-2 at the single cell level. PAF at any dose between 10-16 and 10-8M did not increase intracellular calcium. Furthermore, there was no effective change of intracellular calcium level when PAF was added to alveolar macrophages in the presence of LPS or LPS + LTB4, and 4, 24 and 48h after treatment of these stimulants. Together, the results indicate that IL-1 activity induced by PAF is differently regulated through subsequent induction of endogenous 5-lpoxygenase and cyclooxygenase pathways, but not dependent on calcium signalling pathway.

Keyword

PAF; IL-1; Alveolar Macrophages; Lipoxygenase inhibitors; Cyclooxygenase inhibitors; Leukotriene B4; Prostaglandin E2; Intracellular Ca++ mobilization

MeSH Terms

Animals
Arachidonate 5-Lipoxygenase
Calcium
Cyclooxygenase Inhibitors
Dinoprostone
Fura-2
Ibuprofen
Indomethacin
Inhibitory Concentration 50
Interleukin-1*
Leukotriene B4
Lipoxygenase Inhibitors
Macrophages, Alveolar*
Masoprocol
Prostaglandin-Endoperoxide Synthases
Rats
Thymocytes
Arachidonate 5-Lipoxygenase
Calcium
Cyclooxygenase Inhibitors
Dinoprostone
Fura-2
Ibuprofen
Indomethacin
Interleukin-1
Leukotriene B4
Lipoxygenase Inhibitors
Masoprocol
Prostaglandin-Endoperoxide Synthases