Interleukin-4 enhances 15-lipoxygenase activity and incorporation of 15(S)-HETE into cellular phospholipids in cultured pulmonary epithelial cells.
15(S)-Hydroxyeicosatetraenoic acid (15[S]-HETE) is a 15-lipoxygenase (15-LO) metabolite that may play an important role in different pulmonary diseases. 15-HETE is synthesized by different epithelial cells and may be subsequently incorporated into cellular phospholipids. We studied the role of interleukin-4 (IL-4) on 15-LO activity and on 15(S)-HETE incorporation into cellular phospholipids by WI-26 pulmonary epithelial cells. 15-LO activity was evaluated by measuring 15(S)-HETE production, through combined reverse-phase-high-pressure liquid chromatography (RP-HPLC) separation and specific radioimmunoassay (RIA), after incubation with arachidonic acid (AA). We also studied 15-LO messenger RNA (mRNA) expression, using primed in situ (PRINS) labeling. IL-4 (10 ng/ml) markedly increased the percentage of 15-LO mRNA-bearing cells as well as 15-LO activity after 24, 48, and 72 h, with a maximal response at 48 h. Uptake and incorporation into cellular phospholipid was studied with [3H]15(S)-HETE, which showed that IL-4 was able to increase significantly 15(S)-HETE incorporation into WI-26 cells, with a maximal effect observed at 72 h. Cellular-lipid-associated [3H]15(S)-HETE, evaluated with RP-HPLC after base-catalyzed hydrolysis, increased concomitantly with disappearance of the radiolabel from the supernatant. Class separation of cellular lipids with normal-phase HPLC (NP-HPLC) showed that IL-4 increased [3H]15(S)- HETE incorporation mainly in the phosphatidylinositol (PI) fraction. The ability of IL-4 to promote 15-LO activity and incorporation into cellular phospholipids of human lung epithelial cells may be important in airway inflammation and in modulation of the potential autocrine function of 15(S)-HETE.
Profita
M
M
Istituto di Fisiopatologia Respiratoria, Consiglio Nazionale delle Ricerche, Italy.
Vignola
A M
AM
Sala
A
A
Mirabella
A
A
Siena
L
L
Pace
E
E
Folco
G
G
Bonsignore
G
G
D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D015847:Interleukin-4 / Q000494:pharmacology*; D008168:Lung / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014316:Tritium
D006893:Hydroxyeicosatetraenoic Acids; D010743:Phospholipids; D012333:RNA, Messenger; D014316:Tritium; D015847:Interleukin-4; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D001093:Arachidonate 15-Lipoxygenase