title: Activated human mast cells induce LOX-1-specific scavenger receptor expression in human monocyte-derived macrophages.
abstract: OBJECTIVE
  Activated mast cells in atherosclerotic lesions degranulate and release bioactive compounds capable of regulating atherogenesis. Here we examined the ability of activated human primary mast cells to regulate the expression of the major scavenger receptors in cultured human primary monocyte-derived macrophages (HMDMs).
  
  
  RESULTS
  Components released by immunologically activated human primary mast cells induced a transient expression of lectin-like oxidized LDL receptor (LOX-1) mRNA in HMDMs, while the expression of two other scavenger receptors, MSR1 and CD36, remained unaffected. The LOX-1-inducing secretory components were identified as histamine, tumor necrosis factor alpha (TNF-α), and transforming growth factor beta (TGF-β1), which exhibited a synergistic effect on LOX-1 mRNA expression. Histamine induced a transient expression of LOX-1 protein. Mast cell -induced increase in LOX-1 expression was not associated with increased uptake of oxidized LDL by the macrophages.
  
  
  CONCLUSIONS
  Mast cell-derived histamine, TNF-α, and TGF-β1 act in concert to induce a transient increase in LOX-1 expression in human primary monocyte-derived macrophages. The LOX-1-inducing activity potentially endows mast cells a hitherto unrecognized role in the regulation of innate immune reactions in atherogenesis.
authors.affiliation: Wihuri Research Institute, Helsinki, Finland.
authors.forename: Mervi
authors.initials: M
authors.lastname: Alanne-Kinnunen
authors.affiliation: Wihuri Research Institute, Helsinki, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Lappalainen
authors.affiliation: Wihuri Research Institute, Helsinki, Finland.
authors.forename: Katariina
authors.initials: K
authors.lastname: Öörni
authors.affiliation: Wihuri Research Institute, Helsinki, Finland.
authors.forename: Petri T
authors.initials: PT
authors.lastname: Kovanen
mesh_terms: D018955:CD36 Antigens / Q000235:genetics; D002478:Cells, Cultured; D006632:Histamine / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008407:Mast Cells / Q000166:cytology / Q000276:immunology*; D051117:Scavenger Receptors, Class A / Q000235:genetics; D051127:Scavenger Receptors, Class E / Q000235:genetics* / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology
chemical_list: D018955:CD36 Antigens; C495139:MSR1 protein, human; C495137:OLR1 protein, human; D051117:Scavenger Receptors, Class A; D051127:Scavenger Receptors, Class E; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; D006632:Histamine