title: Selective functional inhibition of JAK-3 is sufficient for efficacy in collagen-induced arthritis in mice.
abstract: OBJECTIVE
  All gamma-chain cytokines signal through JAK-3 and JAK-1 acting in tandem. We undertook this study to determine whether the JAK-3 selective inhibitor WYE-151650 would be sufficient to disrupt cytokine signaling and to ameliorate autoimmune disease pathology without inhibiting other pathways mediated by JAK-1, JAK-2, and Tyk-2.
  
  
  METHODS
  JAK-3 kinase selective compounds were characterized by kinase assay and JAK-3-dependent (interleukin-2 [IL-2]) and -independent (IL-6, granulocyte-macrophage colony-stimulating factor [GM-CSF]) cell-based assays measuring proliferation or STAT phosphorylation. In vivo, off-target signaling was measured by IL-22- and erythropoietin (EPO)-mediated models, while on-target signaling was measured by IL-2-mediated signaling. Efficacy of JAK-3 inhibitors was determined using delayed-type hypersensitivity (DTH) and collagen-induced arthritis (CIA) models in mice.
  
  
  RESULTS
  In vitro, WYE-151650 potently suppressed IL-2-induced STAT-5 phosphorylation and cell proliferation, while exhibiting 10-29-fold less activity against JAK-3-independent IL-6- or GM-CSF-induced STAT phosphorylation. Ex vivo, WYE-151650 suppressed IL-2-induced STAT phosphorylation, but not IL-6-induced STAT phosphorylation, as measured in whole blood. In vivo, WYE-151650 inhibited JAK-3-mediated IL-2-induced interferon-gamma production and decreased the natural killer cell population in mice, while not affecting IL-22-induced serum amyloid A production or EPO-induced reticulocytosis. WYE-151650 was efficacious in mouse DTH and CIA models.
  
  
  CONCLUSIONS
  In vitro, ex vivo, and in vivo assays demonstrate that WYE-151650 is efficacious in mouse CIA despite JAK-3 selectivity. These data question the need to broadly inhibit JAK-1-, JAK-2-, or Tyk-2-dependent cytokine pathways for efficacy.
authors.affiliation: Ligand Pharmaceuticals, Inc., Cranbury, New Jersey, USA.
authors.forename: Tsung H
authors.initials: TH
authors.lastname: Lin
authors.forename: Martin
authors.initials: M
authors.lastname: Hegen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Quadros
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Nickerson-Nutter
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Appell
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Cole
authors.forename: Yuefei
authors.initials: Y
authors.lastname: Shao
authors.forename: Steve
authors.initials: S
authors.lastname: Tam
authors.forename: Michael
authors.initials: M
authors.lastname: Ohlmeyer
authors.forename: Bojing
authors.initials: B
authors.lastname: Wang
authors.forename: Debra G
authors.initials: DG
authors.lastname: Goodwin
authors.forename: Earl F
authors.initials: EF
authors.lastname: Kimble
authors.forename: Jorge
authors.initials: J
authors.lastname: Quintero
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.forename: Peter
authors.initials: P
authors.lastname: Symanowicz
authors.forename: Christopher
authors.initials: C
authors.lastname: Wrocklage
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lussier
authors.forename: Scott H
authors.initials: SH
authors.lastname: Schelling
authors.forename: Amha G
authors.initials: AG
authors.lastname: Hewet
authors.forename: Dejun
authors.initials: D
authors.lastname: Xuan
authors.forename: Rustem
authors.initials: R
authors.lastname: Krykbaev
authors.forename: Jenny
authors.initials: J
authors.lastname: Togias
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Richard
authors.initials: R
authors.lastname: Harrison
authors.forename: Tarek
authors.initials: T
authors.lastname: Mansour
authors.forename: Mary
authors.initials: M
authors.lastname: Collins
authors.forename: James D
authors.initials: JD
authors.lastname: Clark
authors.forename: Maria L
authors.initials: ML
authors.lastname: Webb
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Seidl
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001169:Arthritis, Experimental / Q000188:drug therapy* / Q000378:metabolism; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D053613:Janus Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053616:Janus Kinase 3