title: L-4F inhibits lipopolysaccharide-mediated activation of primary human neutrophils.
abstract: Human apolipoprotein A-I (apoA-I) mimetic L-4F inhibits acute inflammation in endotoxemic animals. Since neutrophils play a crucial role in septic inflammation, we examined the effects of L-4F, compared to apoA-I, on lipopolysaccharide (LPS)-mediated activation of human neutrophils. We performed bioassays in human blood, isolated human neutrophils (incubated in 50 % donor plasma), and isolated human leukocytes (incubated in 5 and 50 % plasma) in vitro. In whole blood, both L-4F and apoA-I inhibited LPS-mediated elevation of TNF-α and IL-6. In LPS-stimulated neutrophils, L-4F and apoA-I (40 μg/ml) also decreased myeloperoxidase and TNF-α levels; however, L-4F tended to be superior in inhibiting LPS-mediated increase in IL-6 levels, membrane lipid rafts abundance and CD11b expression. In parallel experiments, when TNF-α and IL-8, instead of LPS, was used for cell stimulation, L-4F and/or apoA-I revealed only limited efficacy. In LPS-stimulated leukocytes, L-4F was as effective as apoA-I in reducing superoxide formation in 50 % donor plasma, and more effective in 5 % donor plasma (P<0.05). Limulus ambocyte lysate (LAL) and surface plasmon resonance assays showed that L-4F neutralizes LAL endotoxin activity more effectively than apoA-I (P<0.05) likely due to avid binding to LPS. We conclude that (1) direct binding/neutralization of LPS is a major mechanism of L-4F in vitro; (2) while L-4F has similar efficacy to apoA-I in anti-endotoxin effects in whole blood, it demonstrates superior efficacy to apoA-I in aqueous solutions and fluids with limited plasma components. This study rationalizes the utility of L-4F in the treatment of inflammation that is mediated by endotoxin-activated neutrophils.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, BDB-101, 1808 7th Avenue South, Birmingham, AL, 35294-0012, USA.
authors.forename: Oleg F
authors.initials: OF
authors.lastname: Sharifov
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Amit
authors.initials: A
authors.lastname: Gaggar
authors.forename: Edlue M
authors.initials: EM
authors.lastname: Tabengwa
authors.forename: C Roger
authors.initials: CR
authors.lastname: White
authors.forename: Mayakonda N
authors.initials: MN
authors.lastname: Palgunachari
authors.forename: G M
authors.initials: GM
authors.lastname: Anantharamaiah
authors.forename: Himanshu
authors.initials: H
authors.lastname: Gupta
mesh_terms: D000595:Amino Acid Sequence; D016632:Apolipoprotein A-I / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000633:toxicity; D018716:Molecular Mimicry / Q000187:drug effects* / Q000502:physiology; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000494:pharmacology*
chemical_list: C505693:APOA1 protein, human; D016632:Apolipoprotein A-I; C472885:L-4F peptide; D008070:Lipopolysaccharides; D010455:Peptides