title: Syk-kinase inhibition prevents mast cell activation in nasal polyps.
abstract: BACKGROUND
  Mast cells are crucial effector cells in the allergic cascade. The cross-linking of the high affinity IgE receptor (FcεRI) activates mast cells and basophils. Spleen tyrosine kinase (Syk) is positioned upstream of the IgE receptor signal transducing pathway and may represent an important target for the treatment of nasal inflammatory diseases.
  
  
  OBJECTIVE
  We measured effects of a specific Syk inhibitor in the release of mast cell mediators in human cord blood-derived mast cells (CBDMCs) (in-vitro) and in human nasal tissue (ex-vivo).
  
  
  METHODS
  Surgical samples were collected from patients with nasal polyposis who underwent sinus surgery. Tissue cubes of +- 0.9 mm3 were primed with myeloma IgE (1 microg/ml), preincubated with Syk inhibitor NVP-QAB205 in different concentrations and then stimulated with tissue culture medium, anti-IgE 10 microg/ml and anti-IgE 30 microg/ml. Supernatants were analysed for concentrations of histamine, LTC4/LTD4/LTE4 and PGD2. CBDMCs were likewise pre-incubated with compound, prior to stimulation with anti-IgE at 10 microg/ml.
  
  
  RESULTS
  In CBDMCs, the Syk inhibitor prevented degranulation assessed by measurement of histamine release and the production of LTC4/LTD4/LTE4 and PGD2. Furthermore, the Syk inhibitor was similarly able to significantly inhibit the release of these granules and newly synthesized mediators by nasal polyp mast cells in a dose dependent manner.
  
  
  CONCLUSIONS
  Although the critical role of Syk in the IgE receptor signal transduction pathway has been well documented in vitro, this study supports the importance of Syk in IgE receptor-mediated degranulation of mast cells ex-vivo within nasal tissue. Thus, inhibition of Syk may represent an important therapeutic strategy for the treatment of upper airway disease with mast cell involvement, such as allergic rhinitis.
authors.affiliation: Upper Airways Research Laboratory, Department of Otorhinolaryngology, Ghent University, Ghent, Belgium. Joke.Patou@Ugent.be
authors.forename: Joke
authors.initials: J
authors.lastname: Patou
authors.forename: Gabriele
authors.initials: G
authors.lastname: Holtappels
authors.forename: Karen
authors.initials: K
authors.lastname: Affleck
authors.forename: Paul
authors.initials: P
authors.lastname: van Cauwenberge
authors.forename: Claus
authors.initials: C
authors.lastname: Bachert
mesh_terms: D000209:Acute-Phase Proteins / Q000187:drug effects / Q000276:immunology; D015550:Cell Degranulation / Q000276:immunology; D006636:Histamine Release / Q000187:drug effects / Q000276:immunology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology*; D008407:Mast Cells / Q000276:immunology*; D009297:Nasal Mucosa / Q000276:immunology; D009298:Nasal Polyps / Q000276:immunology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology*; D017455:Receptors, IgE / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects; D000072377:Syk Kinase
chemical_list: D000209:Acute-Phase Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017455:Receptors, IgE; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase