Abstract
To investigate the role of phospholipase C (PLC) in inflammatory processes, we tested 1-(6-((17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122), a widely used PLC inhibitor, in several in vitro and in vivo assays. We first examined the effects of U73122 on human phospholipase C-β (PLC-β) isozymes and found that U73122 significantly inhibited recombinant human PLC-β2, with an IC50 of ∼6 μM. U73122 had little effect on PLC-β1, PLC-β3, or PLC-β4. Consistent with its ability to inhibit PLC-β2 enzymatic activity, U73122 reduced interleukin-8 and leukotriene B4-induced Ca2+ flux and chemotaxis in human neutrophils in a concentration-dependent manner. In vivo, U73122 blocked carrageenan-induced hind paw edema in rats, carrageenan-induced macrophage and lymphocyte accumulation into subcutaneous chambers in dogs, lipopolysaccharide-induced macrophage, lymphocyte infiltration and prostaglandin E2 production in a mouse peritonitis model, and 12-O-tetradecanoylphorbol-13-acetate-induced ear edema in mice. These results implicate PLC-dependent signaling pathways in the development of acute and chronic inflammatory responses in vivo.
Footnotes
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DOI: 10.1124/jpet.103.060574.
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ABBREVIATIONS: PLC, phospholipase C; PIP2, phosphatidylinositol 4,5-bisphosphate; PKC, protein kinase C; LTB4, leukotriene B4; IL-8, interleukin-8; U73122, 1-(6-((17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; U73343, 1-(6-((17β-3-methoxylestra-1,3,5(10)-trien-17yl)amino)hexyl)-2,5-pyrrolidine-dione; LPS, lipopolysaccharide; TPA, 12-O-tetradecanoylphorbol-13-acetate; PGE2, prostaglandin E2; PBS, phosphate-buffered saline; HBSS, Hanks' balanced salt solution; COX, cyclooxygenase; ER, estrogen receptor; AR, androgen receptor.
- Received September 26, 2003.
- Accepted December 22, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
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