title: β-Arrestin-2 mediates the proinflammatory effects of proteinase-activated receptor-2 in the airway.
abstract: Proteinase-Activated receptor-2 (PAR(2)), a G-protein-coupled Receptor, activated by serine proteinases, is reported to have both protective and proinflammatory effects in the airway. Given these opposing actions, both inhibitors and activators of PAR(2) have been proposed for treating asthma. PAR(2) can signal through two independent pathways: a β-arrestin-dependent one that promotes leukocyte migration, and a G-protein/Ca(2+) one that is required for prostaglandin E(2) (PGE(2)) production and bronchiolar smooth muscle relaxation. We hypothesized that the proinflammatory responses to PAR(2) activation are mediated by β-arrestins, whereas the protective effects are not. Using a mouse ovalbumin model for PAR(2)-modulated airway inflammation, we observed decreased leukocyte recruitment, cytokine production, and mucin production in β-arrestin-2(-/-) mice. In contrast, PAR(2)-mediated PGE(2) production, smooth muscle relaxation, and decreased baseline airway resistance (measures of putative PAR(2) "protective" effects) were independent of β-arrestin-2. Flow cytometry and cytospins reveal that lung eosinophil and CD4 T-cell infiltration, and production of IL-4, IL-6, IL-13, and TNFα, were enhanced in wild-type but not β-arrestin-2(-/-) mice. Using the forced oscillation technique to measure airway resistance reveals that PAR(2) activation protects against airway hyperresponsiveness by an unknown mechanism, possibly involving smooth muscle relaxation. Our data suggest that the PAR(2)-enhanced inflammatory process is β-arrestin-2 dependent, whereas the protective anticonstrictor effect of bronchial epithelial PAR(2) may be β-arrestin independent.
authors.affiliation: Division of Biomedical Sciences, University of California, Riverside, CA 92521, USA.
authors.forename: Heddie L
authors.initials: HL
authors.lastname: Nichols
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Saffeddine
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Theriot
authors.forename: Akhil
authors.initials: A
authors.lastname: Hegde
authors.forename: Daniel
authors.initials: D
authors.lastname: Polley
authors.forename: Tamer
authors.initials: T
authors.lastname: El-Mays
authors.forename: Harissios
authors.initials: H
authors.lastname: Vliagoftis
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: Emma H
authors.initials: EH
authors.lastname: Wilson
authors.forename: Julia K L
authors.initials: JK
authors.lastname: Walker
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: DeFea
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D001249:Asthma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016535:Bronchial Hyperreactivity / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D005434:Flow Cytometry; D007249:Inflammation / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018793:Interleukin-13 / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism / Q000473:pathology; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D044464:Receptor, PAR-2 / Q000235:genetics / Q000378:metabolism*; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
chemical_list: C000605258:Arrb2 protein, mouse; D019390:Arrestins; D016207:Cytokines; D018793:Interleukin-13; D044464:Receptor, PAR-2; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D015232:Dinoprostone