The acute-phase induction of alpha 2-macroglobulin in rat hepatocyte primary cultures: action of a hepatocyte-stimulating factor, triiodothyronine and dexamethasone.
During inflammation a number of liver-derived plasma proteins increases in concentration. In the rat these so-called acute-phase proteins are mainly proteinase inhibitors, such as alpha 1-proteinase inhibitor, alpha 1-acute-phase globulin and alpha 2-macroglobulin. At present, the mechanisms responsible for the enhanced synthesis of acute-phase proteins are poorly understood. Therefore, we have studied the induction of alpha 2-macroglobulin synthesis in rat hepatocyte primary cultures. Adrenaline, triiodothyronine, estradiol and progesterone were tested for their ability to stimulate alpha 2-macroglobulin synthesis. Only triiodothyronine induced alpha 2-macroglobulin synthesis markedly. However, the presence of dexamethasone was a prerequisite for alpha 2-macroglobulin induction indicating a permissive action of glucocorticoids. Besides glucocorticoids and triiodothyronine a non-dialyzable factor (HSF) derived from rat Kupffer cells or human peripheral blood monocytes was found to be able to stimulate alpha 2-macroglobulin synthesis in hepatocytes. Equal amounts of HSF activity were found in conditioned media from lipopolysaccharide-stimulated and unstimulated rat Kupffer cells as well as in human monocytes. Since the supernatants of unstimulated rat Kupffer cells or human monocytes did not exhibit interleukin 1 activity, HSF activity distinct from interleukin 1 must exist. No HSF activity was found in media conditioned by rat Kupffer cells which had been treated with dexamethasone. Hepatocyte primary cultures were incubated with [35S]methionine-labeled proteins secreted by rat Kupffer cells. A 30 kDa polypeptide was found to be bound to or internalized by rat hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
Bauer
J
J
Tran-Thi
T A
TA
Northoff
H
H
Hirsch
F
F
Schlayer
H J
HJ
Gerok
W
W
Heinrich
P C
PC
D000818:Animals; D001711:Biotransformation / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media / Q000032:analysis; D003907:Dexamethasone / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004837:Epinephrine / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D007728:Kupffer Cells / Q000187:drug effects / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000166:cytology* / Q000187:drug effects; D008970:Molecular Weight; D009000:Monocytes / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D014284:Triiodothyronine / Q000494:pharmacology*; D000511:alpha-Macroglobulins / Q000096:biosynthesis*
D003470:Culture Media; D007375:Interleukin-1; D008070:Lipopolysaccharides; D000511:alpha-Macroglobulins; D014284:Triiodothyronine; D011374:Progesterone; D004958:Estradiol; D003907:Dexamethasone; D004837:Epinephrine