title: Transient targeting of phosphoinositide 3-kinase acts as a roadblock in mast cells' route to allergy.
abstract: BACKGROUND
  Tissue mast cell numbers are dynamically regulated by recruitment of progenitors from the vasculature. It is unclear whether progenitors are recruited during allergic sensitization and whether recruitment promotes allergic responses.
  
  
  OBJECTIVE
  We sought to (1) determine the effect of mast cell recruitment on acute allergic responses and (2) to define the role of phosphoinositide 3-kinase (PI3K) isoforms in sequential steps to allergic responses.
  
  
  METHODS
  Gene-targeted mice for PI3Kγ or PI3Kδ or mice treated with isoform-specific PI3K inhibitors (a novel PI3Kγ-specific inhibitor [NVS-PI3-4] and the PI3Kδ inhibitor IC87114) were used to monitor IgE-mediated mast cell recruitment, migration, adhesion by means of intravital microscopy, degranulation, TNF-α release, and subsequent endothelial cell activation in vivo or in bone marrow-derived mast cells.
  
  
  RESULTS
  Functional PI3Kγ, but not PI3Kδ, was crucial for mast cell accumulation in IgE-challenged skin, TNF-α release from IgE/antigen-stimulated mast cells, and mast cell/endothelial interactions and chemotaxis. PI3Kγ-deficient bone marrow-derived mast cells did not adhere to the endothelium in TNF-α-treated cremaster muscle, whereas PI3Kδ was not required. Depletion of TNF-α blocked IgE-induced mast cell recruitment, which links tissue mast cell-derived cytokine release to endothelial activation and mast cell recruitment. Interference with mast cell recruitment protected against anaphylaxis and was superior to blockage of tissue mast cell degranulation.
  
  
  CONCLUSIONS
  Interference with mast cell recruitment to exacerbated tissues provides a novel strategy to alleviate allergic reactions and surpassed attenuation of tissue mast cell degranulation. This results in prolonged drug action and allows for reduction of drug doses required to block anaphylaxis, an important feature for drugs targeting inflammatory disease in general.
authors.affiliation: Institute of Biochemistry and Genetics, Department of Biomedicine, University of Basel, Basel, Switzerland.
authors.forename: Emilie
authors.initials: E
authors.lastname: Collmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Bohnacker
authors.forename: Romina
authors.initials: R
authors.lastname: Marone
authors.forename: Janet
authors.initials: J
authors.lastname: Dawson
authors.forename: Markus
authors.initials: M
authors.lastname: Rehberg
authors.forename: Rowan
authors.initials: R
authors.lastname: Stringer
authors.forename: Fritz
authors.initials: F
authors.lastname: Krombach
authors.forename: Christoph
authors.initials: C
authors.lastname: Burkhart
authors.forename: Emilio
authors.initials: E
authors.lastname: Hirsch
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Hollingworth
authors.forename: Matthew
authors.initials: M
authors.lastname: Thomas
authors.forename: Matthias P
authors.initials: MP
authors.lastname: Wymann
mesh_terms: D000707:Anaphylaxis / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D000818:Animals; D018926:Anti-Allergic Agents / Q000627:therapeutic use; D015550:Cell Degranulation / Q000276:immunology; D002465:Cell Movement; D058544:Class Ib Phosphatidylinositol 3-Kinase / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000276:immunology; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy / Q000276:immunology* / Q000378:metabolism; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors
chemical_list: D018926:Anti-Allergic Agents; D058544:Class Ib Phosphatidylinositol 3-Kinase; D004791:Enzyme Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors
keywords: 2,4,6-Trinitrophenol; 2,4-Dinitrophenol; BMMC; Bone marrow–derived mast cell; DNP; FACS; Fluorescence-activated cell sorting; G protein–coupled receptor; GPCR; HUVEC; Half-maximal inhibitory concentration; Human umbilical vein endothelial cell; IC(50); IMDM; Iscove modified Dulbecco medium; MAPK; Mast cells; Mitogen-activated protein kinase; PCA; PI3K; PKB/Akt; Passive cutaneous anaphylaxis; Phosphatidylinositol; Phosphoinositide 3-kinase; Phosphorylated PKB; Protein kinase B; PtdIns; SCF; SDF-1α; Stem cell factor; Stromal cell–derived factor 1α; TNP; VCAM-1; VLA; Vascular cell adhesion molecule 1; Very late antigen; allergy; anaphylaxis; inflammation; migration; pPKB; phosphoinositide 3-kinase; recruitment