title: Sphingosine-1-phosphate receptor 2 protects against anaphylactic shock through suppression of endothelial nitric oxide synthase in mice.
abstract: BACKGROUND
  Sphingosine-1-phosphate receptor 2 (S1P(2)) is expressed in vascular endothelial cells (ECs). However, the role of S1P(2) in vascular barrier integrity and anaphylaxis is not well understood. Endothelial nitric oxide synthase (eNOS) generates nitric oxide to mediate vascular leakage, compromising survival in patients with anaphylaxis. We recently observed that endothelial S1P(2) inhibits Akt, an activating kinase of eNOS.
  
  
  OBJECTIVE
  We tested the hypothesis that endothelial S1P(2) might suppress eNOS, exerting a protective effect against endothelial barrier disruption and anaphylaxis.
  
  
  METHODS
  Mice deficient in S1P(2) and eNOS underwent antigen challenge or platelet-activating factor (PAF) injection. Analyses were performed to examine vascular permeability and the underlying mechanisms.
  
  
  RESULTS
  S1pr2 deletion augmented vascular leakage and lethality after either antigen challenge or PAF injection. PAF injection induced activation of Akt and eNOS in the aortas and lungs of S1pr2-null mice, which were augmented compared with values seen in wild-type mice. Consistently, PAF-induced increase in cyclic guanosine monophosphate levels in the aorta was enhanced in S1pr-null mice. Genetic Nos3 deletion or pharmacologic eNOS blockade protected S1pr2-null mice from aggravation of barrier disruption after antigen challenge and PAF injection. ECs isolated from S1pr2-null mice exhibited greater stimulation of Akt and eNOS, with enhanced nitric oxide production in response to sphingosine-1-phosphate or PAF, compared with that seen in wild-type ECs. Moreover, S1pr2-deficient ECs showed more severe disassembly of adherens junctions with augmented S-nitrosylation of β-catenin in response to PAF, which was restored by pharmacologic eNOS blockade.
  
  
  CONCLUSIONS
  S1P(2) diminishes harmful robust eNOS stimulation and thereby attenuates vascular barrier disruption, suggesting potential usefulness of S1P(2) agonists as novel therapeutic agents for anaphylaxis.
authors.affiliation: Department of Physiology, School of Medicine, Kanazawa University, Kanazawa, Japan.
authors.forename: Hong
authors.initials: H
authors.lastname: Cui
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Wa
authors.initials: W
authors.lastname: Du
authors.forename: Noriko
authors.initials: N
authors.lastname: Takuwa
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Masahide
authors.initials: M
authors.lastname: Asano
authors.forename: Toshishige
authors.initials: T
authors.lastname: Shibamoto
authors.forename: Yoh
authors.initials: Y
authors.lastname: Takuwa
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D000707:Anaphylaxis / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D000818:Animals; D001011:Aorta / Q000276:immunology / Q000378:metabolism; D002199:Capillary Permeability / Q000235:genetics / Q000276:immunology; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation; D017353:Gene Deletion; D008168:Lung / Q000276:immunology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051176:beta Catenin / Q000378:metabolism
chemical_list: D010972:Platelet Activating Factor; D049349:Receptors, Lysosphingolipid; D051176:beta Catenin; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D019331:NG-Nitroarginine Methyl Ester
keywords: AJ; Adherens junction; Cyclic guanosine monophosphate; EC; Endothelial cell; Endothelial nitric oxide synthase; L-NAME; MLEC; Mouse lung endothelial cell; NO; Nitric oxide; Nω-L-nitro-arginine methyl ester; OVA; Ovalbumin; PAF; PI3K; PTEN; Phosphatase and tensin homolog deleted from chromosome 10; Phosphatidylinositol 3-kinase; Platelet-activating factor; S1P; S1P(2); Sphingosine-1-phosphate; VE-cadherin; VEGF; Vascular endothelial growth factor A; WT; Wild-type; adherens junction; anaphylaxis; cGMP; eNOS; endothelial nitric oxide synthase; nitric oxide; nitrosylation; vascular permeability; β-catenin