title: IL-1 beta and TNF-alpha suppress apolipoprotein (apo) E secretion and apo A-I expression in HepG2 cells.
abstract: The effect of cytokines on apolipoprotein E (apo E) production and secretion was investigated in a human hepatoma cell line HepG2. Incubation of HepG2 cells with interleukin 1 beta (IL-1 beta) or tumour necrosis factor alpha (TNF-alpha) for 48 h resulted in a significant dose-related decrease of apo E concentration in the culture medium, while intracellular apo E content increased without change in mRNA level. In contrast, IL-1 beta and TNF-alpha decreased both intracellular and medium apo A-I. Elution profiles of cholesterol and apolipoproteins revealed that apo E was present in apo E-rich high density lipoprotein (HDL) fraction and apo A-I was in apo E-rich HDL and small HDL fractions. IL-1 beta and TNF-alpha decreased both apo E and apo A-I in these fractions. The present results suggest that IL-1 beta and TNF-alpha suppress hepatic apo A-I expression and secretion but not expression of apo E, which could contribute to the abnormal lipid metabolism in certain cytokine-mediated inflammatory diseases.
authors.affiliation: Department of Laboratory Medicine, Gifu University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Song
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: S
authors.initials: S
authors.lastname: Fujigaki
authors.forename: A
authors.initials: A
authors.lastname: Noma
authors.forename: H
authors.initials: H
authors.lastname: Ishiguro
authors.forename: T
authors.initials: T
authors.lastname: Nagatsu
authors.forename: M
authors.initials: M
authors.lastname: Seishima
mesh_terms: D016632:Apolipoprotein A-I / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D001057:Apolipoproteins E / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D016632:Apolipoprotein A-I; D001057:Apolipoproteins E; D016207:Cytokines; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha