Ligands for peroxisome proliferator-activated receptor γ (PPAR-γ), such as 15-deoxy-Δ12,14-prostaglandin J 2 (15d-PGJ2) have been implicated as a new class of anti-inflammatory compounds with possible clinical applications. Based on this concept, this investigation was designed to determine the effect of 15d-PGJ 2-mediated activation of PPAR-γ ligand on neutrophil migration after an inflammatory stimulus and clarify the underlying molecular mechanisms using a mouse model of peritonitis. Our results demonstrated that 15d-PGJ 2 administration decreases leukocyte rolling and adhesion to the inflammated mesenteric tissues by a mechanism dependent on NO. Specifically, pharmacological inhibitors of NO synthase remarkably abrogated the 15d-PGJ 2-mediated suppression of neutrophil migration to the inflammatory site. Moreover, inducible NOS-/- mice were not susceptible to 15d-PGJ2-mediated suppression of neutrophil migration to the inflammatory sites when compared with their wild type. In addition, 15d-PGJ 2-mediated suppression of neutrophil migration appeared to be independent of the production of cytokines and chemokines, since their production were not significantly affected in the carrageenan-injected peritoneal cavities. Finally, upregulation of carrageenan-triggered ICAM-1 expression in the mesenteric microcirculation vessels was abrogated by pretreatment of wild-type mice with 15d-PGJ2, whereas 15d-PGJ 2 inhibited F-actin rearrangement process in neutrophils. Taken together these findings demonstrated that 15d-PGJ2 suppresses inflammation-initiated neutrophil migration in a mechanism dependent on NO production in mesenteric tissues. Copyright © 2007 by The American Association of Immunologists, Inc.
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