title: Regulation of pattern recognition receptors by the apolipoprotein A-I mimetic peptide 4F.
abstract: OBJECTIVE
  The apolipoprotein A-I (apoA-I) mimetic peptide 4F favors the differentiation of human monocytes to an anti-inflammatory phenotype and attenuates lipopolysaccharide (LPS)-induced inflammatory responses. We investigated the effects of LPS on the Toll-like receptor (TLR) signaling pathway in 4F-differentiated monocyte-derived macrophages.
  
  
  RESULTS
  Monocyte-derived macrophages were pretreated with 4F or vehicle for 7 days. 4F downregulated cell-surface TLRs (4, 5, and 6) as determined by flow cytometry. 4F attenuated the LPS-dependent upregulation of genes encoding TLR1, 2, and 6 and genes of the MyD88-dependent (CD14, MyD88, TRAF6, interleukin-1 receptor-associated kinase 4, and inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase beta) and MyD88-independent (interferon regulatory factor 3, TANK-binding kinase 1, and Toll-interleukin 1 receptor domain-containing adaptor-inducing interferon-β) pathways as determined by microarray analysis and quantitative reverse transcriptase polymerase chain reaction. Functional analyses of monocyte-derived macrophages showed that 4F reduced LPS-dependent TLR4 recycling, phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha, activation and translocation of nuclear factor-κB and inhibited the secretion of tumor necrosis factor-α and interleukin-6 induced by LPS or lipoteichoic acid. These changes were associated with depletion of cellular cholesterol and caveolin, components of membrane lipid rafts.
  
  
  CONCLUSIONS
  These data suggest that disruption of rafts by 4F alters the assembly of TLR-ligand complexes in cell membranes and inhibits proinflammatory gene expression in monocyte-derived macrophages, thus attenuating the responsiveness of macrophages to LPS.
authors.affiliation: University of Alabama at Birmingham, Department of Medicine, Boshell Diabetes Bldg, Room 650, 1808 7th Ave S Birmingham, AL 35294, USA.
authors.forename: C Roger
authors.initials: CR
authors.lastname: White
authors.forename: Lesley E
authors.initials: LE
authors.lastname: Smythies
authors.forename: David K
authors.initials: DK
authors.lastname: Crossman
authors.forename: Mayakonda N
authors.initials: MN
authors.lastname: Palgunachari
authors.forename: G M
authors.initials: GM
authors.lastname: Anantharamaiah
authors.forename: Geeta
authors.initials: G
authors.lastname: Datta
mesh_terms: D021581:Active Transport, Cell Nucleus; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D016632:Apolipoprotein A-I / Q000494:pharmacology*; D051242:Caveolin 1 / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005434:Flow Cytometry; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000517:prevention & control*; D018836:Inflammation Mediators / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D021962:Membrane Microdomains / Q000187:drug effects / Q000276:immunology; D020411:Oligonucleotide Array Sequence Analysis; D010455:Peptides / Q000494:pharmacology*; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D051193:Toll-Like Receptors / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: C475156:AP-4F peptide; D000893:Anti-Inflammatory Agents; D016632:Apolipoprotein A-I; C495540:CAV1 protein, human; D051242:Caveolin 1; D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D010455:Peptides; C498143:RELA protein, human; D051193:Toll-Like Receptors; D051996:Transcription Factor RelA; D002784:Cholesterol