Inhibition of monocyte chemotaxis to c-c chemokines by antisense oligonucleotide for cytosolic phospholipase A2 (cPLA2)

Monocyte chemotactic protein (MCP)-1, a prototypic C-C chemokine, at chemotactic concentrations, induced a rapid release of [³H]arachidonic acid(AA), but not of [¹⁴C]oleic acid, from prelabeled human monocytes. This effect was paralleled by the phosphorylation of cPLA2. To address the role of cPLA2 in monocyte chemotaxis, cells were treated with a specific antisense oligonucleotide. Monocytes cultured with 10 μM antisense oligonucleotide for 48 h showed a decrease (57±5 %) of cPLA2 expression and a strong inhibition of both [³H]AA release (81.814.2%) and chemotaxis in response to MCP-1 (IC50 = 1.9±1.1 μM). No effect was observed with a mismatched control oligonucleotide. Migration to MCP-3, RANTES and MIP-1a/LD78, but not to fMLP and C5a, also was inhibited in antisense oligonucleotide-treated cells. These data show that cPLA2 is the major effector enzyme responsible for [³H]AA release by MCP-1 and provide direct evidence for a role of cPLA2 in C-C chemokine-induced monocyte chemotaxis. The signaling pathway(s) for AA release in 293 cells cotransfected with cPLA2 and chemokine receptors are under investigations.