ic-87114 and Bronchial-Hyperreactivity

The Th2 cytokine interleukin (IL) 13 can elicit a number of responses consistent with a key role in the pathogenesis of asthma. We have used pharmacological and genetic approaches to demonstrate the role of signaling via the class I phosphoinositide 3-kinase p110delta isoform in IL-13-induced hyper-responsiveness of murine tracheal smooth muscle contractility in vitro. IL-13 treatment of tracheal tissue is associated with an early activation of phosphoinositide 3-kinase (PI3K), as assessed by phosphorylation of Akt. Tracheal smooth muscle contractility is enhanced by overnight incubation with IL-13, resulting in increased maximal contractions (E(max)) to carbachol (CCh) and KCl. Inhibition of PI3K by the non-isoform-selective inhibitors wortmannin or 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), or the selective inhibitor of the PI3K p110delta isoform 2-(6-aminopurin-9-ylmethyl)-5-methyl-3-O-tolyl-3H-quinazolin-4-one (IC87114), prevented IL-13-induced hyper-responsiveness. Consistent with a role for PI3K p110delta in IL-13-induced hyper-responsiveness, IL-13 was unable to induce hyper-responsiveness in tissues from mice expressing the catalytically inactive form of p110delta (p110delta(D910A)). These data indicate that IL-13 contributes to tracheal smooth muscle hyper-responsiveness via the PI3K p110delta isoform. In addition to previously reported effects on airway inflammation, inhibition of PI3K p110delta may be a useful target for the treatment of asthma by preventing IL-13-induced airway smooth muscle hyper-responsiveness.

Topics: Adenine; Animals; Bronchial Hyperreactivity; Carbachol; Chromones; Class I Phosphatidylinositol 3-Kinases; In Vitro Techniques; Interleukin-13; Isoenzymes; Lung; Mice; Mice, Mutant Strains; Morpholines; Muscle Contraction; Muscle, Smooth; Mutant Proteins; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Potassium Chloride; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Quinazolines; Tissue Extracts; Trachea

P110delta phosphoinositide 3-kinase (PI3K) plays a pivotal role in the recruitment and activation of certain inflammatory cells. Recent findings revealed that the activity of p110delta also contributes to allergen-IgE-induced mast cell activation and vascular permeability. We investigated the role of p110delta in allergic airway inflammation and hyperresponsiveness using IC87114, a selective p110delta inhibitor, in a mouse asthma model. BALB/c mice were sensitized with OVA and, upon OVA aerosol challenge, developed airway eosinophilia, mucus hypersecretion, elevation in cytokine and chemokine levels, up-regulation of ICAM-1 and VCAM-1 expression, and airway hyperresponsiveness. Intratracheal administration of IC87114 significantly (P<0.05) attenuated OVA-induced influx into lungs of total leukocytes, eosinophils, neutrophils, and lymphocytes, as well as levels of IL-4, IL-5, IL-13, and RANTES in a dose-dependent manner. IC87114 also significantly (P<0.05) reduced the serum levels of total IgE and OVA-specific IgE and LTC(4) release into the airspace. Histological studies show that IC87114 inhibited OVA-induced lung tissue eosinophilia, airway mucus production, and inflammation score. In addition, IC87114 significantly (P<0.05) suppressed OVA-induced airway hyperresponsiveness to inhaled methacholine. Western blot analyses of whole lung tissue lysates shows that IC87114 markedly attenuated the OVA-induced increase in expression of IL-4, IL-5, IL-13, ICAM-1, VCAM-1, RANTES, and eotaxin. Furthermore, IC87114 treatment markedly attenuated OVA-induced serine phosphorylation of Akt, a downstream effector of PI3K signaling. Taken together, our findings implicate that inhibition of p110delta signaling pathway may have therapeutic potential for the treatment of allergic airway inflammation.

Topics: Adenine; Animals; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Cell Adhesion Molecules; Chemokines; Chemotaxis, Leukocyte; Class I Phosphatidylinositol 3-Kinases; Cytokines; Eosinophilia; Female; Lung; Methacholine Chloride; Mice; Mice, Inbred BALB C; Models, Animal; Mucus; Ovalbumin; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Quinazolines

Bronchial asthma is characterized by inflammation of the airways, which is usually accompanied by increased vascular permeability, resulting in plasma exudation. Vascular endothelial growth factor (VEGF) has been implicated in contributing to asthmatic tissue edema through its effect on vascular permeability. Many cellular responses of VEGF are regulated by the lipid products of phosphoinositide 3-kinase (PI3K). However, the effect of PI3K catalytic subunit p110delta on VEGF-mediated signaling is unknown. Recently, an isoform-specific small molecule inhibitor, IC87114, which is selective for p110delta catalytic activity, has been identified.. We have sought to investigate the role of PI3K-delta, more specifically in the increase of vascular permeability.. Female BALB/c mice were sensitized and challenged with ovalbumin. We have investigated the effect of IC87114 on airway inflammation, T(H)2 cytokines expression, airway hyperresponsiveness, plasma extravasation, hypoxia-inducible factor 1alpha expression, and VEGF expression in a murine model of asthma.. Our current study has revealed that IC87114 reduces antigen-induced airway infiltration of inflammatory cells, secretion of T(H)2 cytokines in lungs, airway hyperresponsiveness, and vascular permeability. Moreover, we have found that inhibition of p110delta reduces ovalbumin-induced upregulation of VEGF level.. These results suggest that PI3K-delta inhibitor attenuates antigen-induced airway inflammation and hyperresponsiveness by preventing vascular leakage in mice.. These findings provide a crucial molecular mechanism for the potential role of PI3K-delta in asthma and other airway inflammatory disorders.

Topics: Adenine; Animals; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Capillary Permeability; Cinnamates; Class I Phosphatidylinositol 3-Kinases; Cytokines; Disease Models, Animal; Enzyme Inhibitors; Female; Hypoxia-Inducible Factor 1, alpha Subunit; Indoles; Leukocyte Count; Lung; Mice; Mice, Inbred BALB C; Ovalbumin; Phosphoinositide-3 Kinase Inhibitors; Pneumonia; Quinazolines; Receptors, Vascular Endothelial Growth Factor; Vascular Endothelial Growth Factor A