Abstract
Interstitial cystitis (IC) is an inflammatory bladder condition of unknown etiology. Tryptase released from elevated numbers of activated mast cells is a proposed mediator of the inflammatory process in IC. We have previously shown that tryptase increases human bladder microvascular endothelial cell (HBMEC) calcium-independent phospholipase A2 (iPLA2) activity, resulting in the production of multiple biologically active phospholipid metabolites, including platelet-activating factor (PAF), that can mediate inflammation. Because the design of selective PLA2 inhibitors may provide a useful therapeutic strategy to reduce the inflammatory process in IC, we tested several frequently used PLA2 inhibitors on PAF production in tryptase-stimulated HBMEC. Among the inhibitors tested, methyl arachidonyl fluorophosphonate (MAFP) was found to be a potent inhibitor of PAF-acetylhydrolase activity. Pretreatment of HBMEC with MAFP significantly increased PAF production in both unstimulated and tryptase-stimulated cells. In addition, MAFP pretreatment of tryptase-stimulated HBMEC increased both surface expression of P-selectin and polymorphonuclear leukocyte adherence to the HBMEC monolayer. These effects suggest that MAFP has a proinflammatory effect, irrespective of its ability to inhibit PLA2.
Footnotes
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This research was supported by the National Institutes of Health Grant DK-66119 (to J.M.) and was previously presented at the 2005 Federation of American Societies for Experimental Biology meeting, San Diego, CA, Mar 31-Apr 5.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.105.085365.
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ABBREVIATIONS: IC, interstitial cystitis; HBMEC, human bladder microvascular endothelial cell(s); iPLA2, calcium-independent phospholipase A2; PAF, platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine); PMN, polymorphonuclear leukocyte(s); lysoPlsEtn, lysoplasmenylethanolamine; PAF-AH, platelet-activating factor-acetylhydrolase; MAFP, methyl arachidonyl fluorophosphonate; cPLA2, cytosolic PLA2; BEL, bromoenol lactone [(E)-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one]; AACOCF3, arachidonyl trifluoromethyl ketone; PX-18, 2-[N,N-bis(2-oleoyloxyethyl)amine]-1-ethanesulfonic acid; MPO, myeloperoxidase; SEM, scanning electron microscopy; sPLA2, secreted phospholipase A2.
- Received February 23, 2005.
- Accepted June 2, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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