Preclinical evaluation of an inhibitor of cytosolic phospholipase A2α for the treatment of asthma

J Pharmacol Exp Ther. 2012 Mar;340(3):656-65. doi: 10.1124/jpet.111.186379. Epub 2011 Dec 7.

Abstract

Asthma is a chronic inflammatory lung disease with considerable unmet medical needs for new and effective therapies. Cytosolic phospholipase A(2)α (cPLA(2)α) is the rate-limiting enzyme that is ultimately responsible for the production of eicosanoids implicated in the pathogenesis of asthma. We investigated a novel cPLA(2)α inhibitor, PF-5212372, to establish the potential of this drug as a treatment for asthma. PF-5212372 was a potent inhibitor of cPLA(2)α (7 nM) and was able to inhibit prostaglandin (PG)D(2) and cysteinyl leukotriene release from anti-IgE-stimulated human lung mast cells (0.29 and 0.45 nM, respectively). In a mixed human lung cell population, PF-5212372 was able to inhibit ionomycin-stimulated release of leukotriene B(4), thromboxane A(2), and PGD(2) (2.6, 2.6, and 4.0 nM, respectively) but was significantly less effective against PGE(2) release (>301 nM; p < 0.05). In an in vitro cell retention assay, PF-5212372 retained its potency up to 24 h after being washed off. In a sheep model of allergic inflammation, inhalation of PF-5212372 significantly inhibited late-phase bronchoconstriction (78% inhibition; p < 0.001) and airway hyper-responsiveness (94% inhibition; p < 0.001), and isolated sheep lung mast cell assays confirmed species translation via effective inhibition of PGD(2) release (0.78 nM). Finally, PF-5212372 was assessed for its ability to inhibit the contraction of human bronchi induced by AMP. PF5212372 significantly inhibited AMP-induced contraction of human bronchi (81% inhibition; p < 0.001); this finding, together with the ability of this drug to be effective in a wide range of preclinical asthma models, suggests that inhibition of cPLA(2)α with PF-5212372 may represent a new therapeutic option for the treatment of asthma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Anti-Idiotypic / pharmacology
  • Asthma / drug therapy*
  • Bronchoconstriction / drug effects
  • Calcium Ionophores / pharmacology
  • Cell Line
  • Cytosol / enzymology*
  • Enzyme Inhibitors / therapeutic use*
  • Group IV Phospholipases A2 / antagonists & inhibitors*
  • Humans
  • Mast Cells / physiology
  • Phenylpropionates / pharmacology*
  • Prostaglandin D2 / metabolism
  • Sheep
  • Sulfonamides / pharmacology*

Substances

  • Antibodies, Anti-Idiotypic
  • Calcium Ionophores
  • Enzyme Inhibitors
  • PF-5212372
  • Phenylpropionates
  • Sulfonamides
  • anti-IgE antibodies
  • Group IV Phospholipases A2
  • Prostaglandin D2