title: Lexipafant inhibits platelet activating factor enhanced neutrophil functions.
abstract: Platelet activating factor (PAF) enhances polymorphonuclear leukocyte (PMN) superoxide (.O2-) production, CD11b expression, and elastase release, all essential components in the pathophysiology of multiple-organ failure. This study was designed to determine the effects of Lexipafant, a PAF receptor antagonist, on PAF-mediated PMN functions. PMNs from 10 healthy volunteers were isolated and pretreated with various concentrations of Lexipafant (0-100 microM). PMNs were then incubated for 5 min with 200 nM PAF for .O2- detection or 2000 nM PAF for elastase measurement and activated with 1 microM N-formylmethionylleucylphenylalanine. The mean rate of .O2- production was determined by a cytochrome c reduction assay (nmole .O2-/min/1.33 x 10(5) PMN +/- SEM). Elastase release was measured by the cleavage of the synthetic elastase substrate Meo-Suc-Ala-Ala-Pro-Val-pNA (mean elastolytic activity +/- SEM). In parallel experiments, PMNs were incubated with 200 nM PAF for 30 min following pre-treatment with Lexipafant and CD11b expression was determined by flow cytometry (mean fluorescence intensity +/- SEM). Statistical analysis was performed using repeated-measures ANOVA (P < 0.05). Lexipafant inhibited PAF-enhanced PMN .O2- generation, CD11b expression and elastase release in a dose dependent fashion. The IC50 of Lexipafant for .O2- production, CD11b expression, and elastase release was 0.046, 0.285, and 0.05 microM, respectively. Lexipafant attenuated the PAF-mediated upregulation of PMN .O2- production, CD11b expression, and elastase release in a dose dependent fashion. These data support the hypothesis that Lexipafant may reduce the severity of the inflammatory response to injury produced by PAF-enhanced activation of PMNs.
authors.affiliation: New York University School of Medicine, Department of Surgery, S. Arthur Localio, Surgical Research Laboratory, New York 10016, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Schwartz
authors.forename: P
authors.initials: P
authors.lastname: Shamamian
authors.forename: E A
authors.initials: EA
authors.lastname: Grossi
authors.forename: D S
authors.initials: DS
authors.lastname: Schwartz
authors.forename: S G
authors.initials: SG
authors.lastname: Marcus
authors.forename: F
authors.initials: F
authors.lastname: Steiner
authors.forename: C E
authors.initials: CE
authors.lastname: Jacobs
authors.forename: M
authors.initials: M
authors.lastname: Tayyarah
authors.forename: K
authors.initials: K
authors.lastname: Eng
authors.forename: S B
authors.initials: SB
authors.lastname: Colvin
authors.forename: A C
authors.initials: AC
authors.lastname: Galloway
mesh_terms: D004305:Dose-Response Relationship, Drug; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019272:Leukocyte Elastase / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects*; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016897:Respiratory Burst / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D013696:Temperature
chemical_list: D005609:Free Radicals; D007093:Imidazoles; D016177:Macrophage-1 Antigen; D010972:Platelet Activating Factor; D013481:Superoxides; D019272:Leukocyte Elastase; D007930:Leucine; C103289:lexipafant