IL-1 beta and TNF-alpha suppress apolipoprotein (apo) E secretion and apo A-I expression in HepG2 cells.
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.
Song
H
H
Department of Laboratory Medicine, Gifu University School of Medicine, Japan.
Saito
K
K
Fujigaki
S
S
Noma
A
A
Ishiguro
H
H
Nagatsu
T
T
Seishima
M
M
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
D016632:Apolipoprotein A-I; D001057:Apolipoproteins E; D016207:Cytokines; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha