title: Multiple-site activation of the cysteinyl leukotriene receptor 2 is required for exacerbation of ischemia/reperfusion injury.
abstract: OBJECTIVE
  Transgenic overexpression of the human cysteinyl leukotriene receptor 2 (CysLT2R) in murine endothelium exacerbates vascular permeability and ischemia/reperfusion injury. Here, we explore the underlying mechanisms of CysLT2R activation-mediated inflammation and delineate the relative contributions of endogenous murine CysLT2R and the transgene-derived receptor.
  
  
  RESULTS
  We created a novel mouse with only endothelial-expressed CysLT2R (endothelium-targeted overexpression mice [EC]/CysLT2R-knockout mice [KO]) by crossing EC with KO to dissect the role of endothelial CysLT2R in tissue injury. Surprisingly, we discovered that damage in EC/KO mice was not elevated (24% versus 47% EC) after ischemia/reperfusion. We examined vascular permeability and leukocyte recruitment/rolling responses in the cremaster vasculature after cysteinyl leukotriene (cysLT) stimulation. Mice possessing transgenic endothelial CysLT2R overexpression, whether EC or EC/KO, when stimulated with cysLTs, exhibited vascular hyperpermeability, declining leukocyte flux, and a transient increase in slow-rolling leukocyte fraction. Mice lacking endogenous CysLT2R (both KO [20 ± 3 cells/min] EC/KO [24 ± 3]) showed lower-rolling leukocyte flux versus wild-type (38 ± 6) and EC (35 ± 6) mice under unstimulated conditions. EC/KO mice differed from EC counterparts in that vascular hyperpermeability was not present in the absence of exogenous cysLTs.
  
  
  CONCLUSIONS
  These results indicate that endothelial and nonendothelial CysLT2R niches have separate roles in mediating inflammatory responses. Endothelial receptor activation results in increased vascular permeability and leukocyte slow-rolling, facilitating leukocyte transmigration. Nonendothelial receptors, likely located on resident/circulating leukocytes, facilitate endothelial receptor activation and leukocyte transit. Activation of both receptor populations is required for injury exacerbation.
authors.affiliation: From the Department of Biomedical and Molecular Sciences (N.C.N., L.L.B., C.D.F.) and Cancer Research Institute (J.D.M.), Queen's University, Kingston, ON, Canada.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Ni
authors.forename: Laurel L
authors.initials: LL
authors.lastname: Ballantyne
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Mewburn
authors.forename: Colin D
authors.initials: CD
authors.lastname: Funk
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D003545:Cysteine / Q000494:pharmacology; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D036904:Leukocyte Rolling; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D015289:Leukotrienes / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000098:blood supply*; D009203:Myocardial Infarction / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D009206:Myocardium / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D018077:Receptors, Leukotriene / Q000819:agonists / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D015289:Leukotrienes; D018077:Receptors, Leukotriene; C112381:cysteinyl-leukotriene; C412375:cysteinyl leukotriene receptor 2; D003545:Cysteine
keywords: cysteinyl leukotriene receptor 2; inflammation; leukocytes; myocardial infarction; permeability