title: Leukotriene D4 and prostaglandin E2 signals synergize and potentiate vascular inflammation in a mast cell-dependent manner through cysteinyl leukotriene receptor 1 and E-prostanoid receptor 3.
abstract: BACKGROUND
  Although arachidonic acid metabolites, cysteinyl leukotrienes (cys-LTs; leukotriene [LT] C4, LTD4, and LTE4), and prostaglandin (PG) E2 are generated at the site of inflammation, it is not known whether crosstalk exists between these 2 classes of inflammatory mediators.
  
  
  OBJECTIVE
  We sought to determine the role of LTD4-PGE2 crosstalk in inducing vascular inflammation in vivo, identify effector cells, and ascertain specific receptors and pathways involved in vitro.
  
  
  METHODS
  Vascular (ear) inflammation was assessed by injecting agonists into mouse ears, followed by measuring ear thickness and histology, calcium influx with Fura-2, phosphorylation and expression of signaling molecules by means of immunoblotting, PGD2 and macrophage inflammatory protein 1β generation by using ELISA, and expression of transcripts by using RT-PCR. Candidate receptors and signaling molecules were identified by using antagonists and inhibitors and confirmed by using small interfering RNA.
  
  
  RESULTS
  LTD4 plus PGE2 potentiated vascular permeability and edema, gearing the system toward proinflammation in wild-type mice but not in Kit(W-sh) mice. Furthermore, LTD4 plus PGE2, through cysteinyl leukotriene receptor 1 (CysLT1R) and E-prostanoid receptor (EP) 3, enhanced extracellular signal-regulated kinase (Erk) and c-fos phosphorylation, inflammatory gene expression, macrophage inflammatory protein 1β secretion, COX-2 upregulation, and PGD2 generation in mast cells. Additionally, we uncovered that this synergism is mediated through Gi, protein kinase G, and Erk signaling. LTD4 plus PGE2-potentiated effects are partially sensitive to CysLT1R or EP3 antagonists but completely abolished by simultaneous treatment both in vitro and in vivo.
  
  
  CONCLUSIONS
  Our results unravel a unique LTD4-PGE2 interaction affecting mast cells through CysLT1R and EP3 involving Gi, protein kinase G, and Erk and contributing to vascular inflammation in vivo. Furthermore, current results also suggest an advantage of targeting both CysLT1R and EP3 in attenuating inflammation.
authors.affiliation: Department of Chemistry, University of Akron, Akron, Ohio.
authors.forename: Vinay
authors.initials: V
authors.lastname: Kondeti
authors.affiliation: Department of Chemistry, University of Akron, Akron, Ohio.
authors.forename: Nosayba
authors.initials: N
authors.lastname: Al-Azzam
authors.affiliation: Department of Chemistry, University of Akron, Akron, Ohio.
authors.forename: Ernest
authors.initials: E
authors.lastname: Duah
authors.affiliation: Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio.
authors.forename: Charles K
authors.initials: CK
authors.lastname: Thodeti
authors.affiliation: Department of Medicine, Harvard Medical School, Boston, Mass; Department of Pediatrics, Harvard Medical School, Boston, Mass; Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Mass.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Boyce
authors.affiliation: Department of Chemistry, University of Akron, Akron, Ohio. Electronic address: sp97@uakron.edu.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Paruchuri
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D002460:Cell Line; D045744:Cell Line, Tumor; D015232:Dinoprostone / Q000276:immunology*; D004487:Edema / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology; D017998:Leukotriene D4 / Q000276:immunology*; D008407:Mast Cells / Q000276:immunology*; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018077:Receptors, Leukotriene / Q000276:immunology*; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000276:immunology*
chemical_list: D018077:Receptors, Leukotriene; D058308:Receptors, Prostaglandin E, EP3 Subtype; D017998:Leukotriene D4; D015232:Dinoprostone; C083169:leukotriene D4 receptor
keywords: CysLT(1)R; E-prostanoid receptor 3; Mast cells; c-fos; extracellular signal-regulated kinase; leukotriene D(4); macrophage inflammatory protein 1β; prostaglandin D(2); prostaglandin E(2); protein kinase G