ic-87114 and Hypersensitivity

Trafficking and recruitment of eosinophils during allergic airway inflammation is mediated by the phosphatidylinositol 3-kinase (PI3K) family of signaling molecules. The role played by the p110δ subunit of PI3K (PI3K p110δ) in regulating eosinophil trafficking and recruitment was investigated using a selective pharmacological inhibitor (IC87114). Treatment with the PI3K p110δ inhibitor significantly reduced murine bone marrow-derived eosinophil (BM-Eos) adhesion to VCAM-1 as well as ICAM-1 and inhibited activation-induced changes in cell morphology associated with reduced Mac-1 expression and aberrant cell surface localization/distribution of Mac-1 and α4. Infused BM-Eos demonstrated significantly decreased rolling and adhesion in inflamed cremaster muscle microvessels of mice treated with IC87114 compared with vehicle-treated mice. Furthermore, inhibition of PI3K p110δ significantly attenuated eotaxin-1-induced BM-Eos migration and prevented eotaxin-1-induced changes in the cytoskeleton and cell morphology. Knockdown of PI3K p110δ with siRNA in BM-Eos resulted in reduced rolling, adhesion, and migration, as well as inhibition of activation-induced changes in cell morphology, validating its role in regulating trafficking and migration. Finally, in a mouse model of cockroach antigen-induced allergic airway inflammation, oral administration of the PI3K p110δ inhibitor significantly inhibited airway eosinophil recruitment, resulting in attenuation of airway hyperresponsiveness in response to methacholine, reduced mucus secretion, and expression of proinflammatory molecules (found in inflammatory zone-1 and intelectin-1). Overall, these findings indicate the important role played by PI3K p110δ in mediating BM-Eos trafficking and migration by regulating adhesion molecule expression and localization/distribution as well as promoting changes in cell morphology that favor recruitment during inflammation.

Topics: Adenine; Animals; Asthma; Bone Marrow Cells; Cell Adhesion; Cell Movement; Chemokine CCL11; Class I Phosphatidylinositol 3-Kinases; Eosinophilia; Eosinophils; Hypersensitivity; Intercellular Adhesion Molecule-1; Macrophage-1 Antigen; Methacholine Chloride; Mice; Mice, Inbred BALB C; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Quinazolines; Respiratory System; RNA Interference; RNA, Small Interfering; Vascular Cell Adhesion Molecule-1

We have previously described critical and nonredundant roles for the phosphoinositide 3-kinase p110delta during the activation and differentiation of naive T cells, and p110delta inhibitors are currently being developed for clinical use. However, to effectively treat established inflammatory or autoimmune diseases, it is important to be able to inhibit previously activated or memory T cells. In this study, using the isoform-selective inhibitor IC87114, we show that sustained p110delta activity is required for interferon-gamma production. Moreover, acute inhibition of p110delta inhibits cytokine production and reduces hypersensitivity responses in mice. Whether p110delta played a similar role in human T cells was unknown. Here we show that IC87114 potently blocked T-cell receptor-induced phosphoinositide 3-kinase signaling by both naive and effector/memory human T cells. Importantly, IC87114 reduced cytokine production by memory T cells from healthy and allergic donors and from inflammatory arthritis patients. These studies establish that previously activated memory T cells are at least as sensitive to p110delta inhibition as naive T cells and show that mouse models accurately predict p110delta function in human T cells. There is therefore a strong rationale for p110delta inhibitors to be considered for therapeutic use in T-cell-mediated autoimmune and inflammatory diseases.

Topics: Adenine; Animals; Arthritis; CD4-Positive T-Lymphocytes; Cell Proliferation; Class I Phosphatidylinositol 3-Kinases; Cytokines; Humans; Hypersensitivity; Immunity; Immunologic Memory; Lymphocyte Activation; Mice; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Quinazolines; Receptors, Antigen, T-Cell; Signal Transduction

Eosinophil differentiation, activation, and survival are largely regulated by IL-5. IL-5-mediated transmembrane signal transduction involves both Lyn-mitogen-activated protein kinases and Janus kinase 2-signal transducer and activator of transcription pathways.. We sought to determine whether additional signaling molecules/pathways are critically involved in IL-5-mediated eosinophil survival.. Eosinophil survival and apoptosis were measured in the presence and absence of IL-5 and defined pharmacologic inhibitors in vitro. The specific role of the serine/threonine kinase proviral integration site for Moloney murine leukemia virus (Pim) 1 was tested by using HIV-transactivator of transcription fusion proteins containing wild-type Pim-1 or a dominant-negative form of Pim-1. The expression of Pim-1 in eosinophils was analyzed by means of immunoblotting and immunofluorescence.. Although pharmacologic inhibition of phosphatidylinositol-3 kinase (PI3K) by LY294002, wortmannin, or the selective PI3K p110delta isoform inhibitor IC87114 was successful in each case, only LY294002 blocked increased IL-5-mediated eosinophil survival. This suggested that LY294002 inhibited another kinase that is critically involved in this process in addition to PI3K. Indeed, Pim-1 was rapidly and strongly expressed in eosinophils after IL-5 stimulation in vitro and readily detected in eosinophils under inflammatory conditions in vivo. Moreover, by using specific protein transfer, we identified Pim-1 as a critical element in IL-5-mediated antiapoptotic signaling in eosinophils.. Pim-1, but not PI3K, plays a major role in IL-5-mediated antiapoptotic signaling in eosinophils.

Topics: Adenine; Androstadienes; Apoptosis; Cells, Cultured; Chromones; Eosinophils; Humans; Hypersensitivity; Interleukin-5; Janus Kinase 2; Microscopy, Confocal; Morpholines; Myeloid Cell Leukemia Sequence 1 Protein; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-pim-1; Quinazolines; Tyrphostins; Wortmannin; Xanthenes