Premium
Effects of Cytokines, Butyrate and Dexamethasone on Serum Amyloid A and Apolipoprotein A‐I Synthesis in Human HUH‐7 Hepatoma Cells
Author(s) -
Ernst Malle,
B. Leonhard,
Gabriele Knipping,
Wolfgang Sattler
Publication year - 1999
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1046/j.1365-3083.1999.00574.x
Subject(s) - serum amyloid a , apolipoprotein b , intracellular , endocrinology , butyrate , acute phase protein , medicine , secretion , serum amyloid a protein , chemistry , sodium butyrate , apolipoprotein e , dexamethasone , biochemistry , biology , inflammation , cholesterol , disease , fermentation , gene
Serum amyloid A (SAA) and apolipoprotein A‐I (apo A‐I) are secreted by the liver. As concentrations of both apolipoproteins are inversely related under normal and acute‐phase conditions, human HUH‐7 hepatoma cells were stimulated with interleukin (IL)‐1α (100 and 200 U), IL‐6 (50 and 100 U), butyrate (2 m m ) and dexamethasone (2 × 10 −7 m and 1 × 10 −6 m ), alone or in combination. Changes in SAA and apo A‐I synthesis were monitored after metabolic labelling of the cells with [ 35 S]‐methionine. Intracellular and secreted SAA and apo A‐I were immunoprecipitated, separated by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE), and the radioactivity in the corresponding bands was counted. Intracellular apolipoprotein levels were increased by all stimuli, either alone or in combination, between 2.7‐ and 5.5‐fold (SAA) and between 2.8‐ and 4.1‐fold (apo A‐I), respectively. In a similar manner, apolipoprotein levels secreted by HUH‐7 cells were increased between 3.1‐ and 4.3‐fold (SAA) and between 1.9‐ and 3.3‐fold (apo A‐I). Co‐administration of cytokines, butyrate and/or dexamethasone had no pronounced synergistic effect on intracellular biosynthesis and secretion of SAA and apo A‐I. The results from the present study suggest that apo A‐I must not necessarily be considered as a negative acute‐phase reactant.