A functional role for eicosanoid-lysophospholipids in activating monocyte signaling

Area of Science:

• Lipid metabolism and signaling
• Immunology
• Inflammation research

Background:

• Eicosanoid-lysophospholipids are novel metabolites from arachidonoyl-lysophospholipids.
• Their signaling functions are largely unknown.
• Arachidonoyl-plasmalogens are precursors to these compounds.

Purpose of the Study:

• To investigate the signaling functions of eicosanoid-lysophospholipids.
• To determine if 12(S)-HETE-lysophospholipids activate immune cells.
• To elucidate the role of these lipids in inflammatory responses.

Main Methods:

• Activation of THP-1 human monocytic cells with 12(S)-HETE-lysophospholipids.
• Measurement of TNFα and IL8 production.
• Inhibition studies using TNFα converting enzyme inhibitor TAPI-0.
• Western blotting for NFκB p65 phosphorylation.
• Stereoselective activation assays.
• RP-HPLC analysis of activated platelet lipid extracts.

Main Results:

• Low nanomolar concentrations of 12(S)-HETE-lysophospholipids potently activated THP-1 cells to produce TNFα.
• TNFα release was mediated by normal TNFα processing and involved NFκB signaling pathway activation.
• Activation was stereoselective, favoring 12(S)-HETE over 12(R)-HETE.
• 12(S)-HETE-lysophosphatidylcholine showed higher potency (EC50 2.1 nm) than free 12(S)-HETE (EC50 23 nm).
• Platelet lipid extracts confirmed coelution of 12(S)-HETE with fractions inducing TNFα release.

Conclusions:

• 2-12(S)-HETE-lysophospholipids and 12(S)-HETE are potent lipid mediators.
• They activate THP-1 cells to release TNFα and activate NFκB signaling.
• These findings reveal a previously unrecognized role for 2-12(S)-HETE-lysophospholipids in mediating inflammatory responses.