Endotoxin-stimulated macrophages decrease bile acid uptake in WIF-B cells, a rat hepatoma hybrid cell line.
Endotoxemia leads to cytokine-mediated alterations of the hepatocellular sodium-taurocholate-cotransporting polypeptide (ntcp). We hypothesized that stimulated macrophages are essential transducers for down-regulating hepatocellular bile salt uptake in response to endotoxin (lipopolysaccharide [LPS]) exposure. Using an in vitro model, we exposed mouse macrophages (IC-21 cell line) to LPS for 24 hours. Concentrations of cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 increased 10.6-fold, 12.5-fold, and 444-fold, respectively, in LPS-conditioned IC-21 medium (CM) versus unconditioned IC-21 medium (UM). WIF-B rat hepatoma hybrid cells were incubated with either CM or UM or treated directly with medium containing recombinant TNF-alpha, IL-1beta, and IL-6. [(3)H]Taurocholate ([(3)H]TC) uptake decreased in WIF-B cells exposed to either TNF-alpha (54% of control), IL-1beta (78%), IL-6 (55%) as single additives, or in triple combination (TCC) (43%). A virtually identical decrease was observed after exposing WIF-B cells to CM (52%, P <.001). LPS had no direct effect on [(3)H]TC uptake. CM treatment did not decrease L-alanine transport in WIF-B cells. Blocking antibodies against TNF-alpha, IL-1beta, and IL-6 restored the diminished [(3)H]TC uptake in cells exposed to TCC and CM to 87% and 107% of controls, respectively. Northern blotting revealed that ntcp messenger RNA (mRNA) expression was significantly reduced in WIF-B cells after exposure to CM, and in primary rat hepatocytes exposed to CM or TNF-alpha (68%, 14%, and 29% of control, respectively). We conclude that macrophages and their ability to secrete the cytokines TNF-alpha, IL-1beta, and IL-6 may be essential in mediating the endotoxin-induced cholestatic effect of decreased hepatocellular bile salt uptake.
Sturm
E
E
Program in Gastrointestinal Pathology, Yale Liver Center and Yale University Medical School, New Haven, CT, USA.
Zimmerman
T L
TL
Crawford
A R
AR
Svetlov
S I
SI
Sundaram
P
P
Ferrara
J L
JL
Karpen
S J
SJ
Crawford
J M
JM
D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D002460:Cell Line; D017077:Culture Media, Conditioned; D007375:Interleukin-1 / Q000096:biosynthesis / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D008262:Macrophage Activation; D008264:Macrophages / Q000502:physiology*; D008297:Male; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D013656:Taurocholic Acid / Q000378:metabolism; D014316:Tritium; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000494:pharmacology
D001647:Bile Acids and Salts; D017077:Culture Media, Conditioned; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D014316:Tritium; D013656:Taurocholic Acid