Metallothionein induction in cultured rat hepatocytes by arthritic rat serum, activated macrophages, interleukin-6, interleukin-11 and leukaemia inhibitory factor.
Potential mediators of hepatic metallothionein (MT) synthesis in adjuvant-induced arthritis were investigated in cultured rat hepatocytes. Sera from arthritic rats (14 d post-adjuvant treatment) in the presence of Zn (50 mumol/L)+dexamethasone (Dex; 1 mumol/L) increased metallothionein (MT) accumulation by 34% above that obtained with control rat serum with Zn+Dex. Endogenous IL-6 activity in serum from arthritic rats was 93 +/- 49 U/mL and was undetectable in control rat serum. The activities of TNF, IL-1 and corticosterone concentrations were the same in control and arthritic rats. The accumulation of MT in hepatocytes in the presence of Zn (10 mumol/L)+Dex (1 mumol/L) was enhanced 29% and 49% by media from lipopolysaccharide (LPS)-stimulated peritoneal macrophage (PMM) and Kupffer cell cultures (KCM), respectively. The response with PMM and KCM was quantitatively the same as that with interleukin-6 (IL-6). Analysis of PMM and KCM showed activities of 1,000-10,000 U/mL for IL-6, 100-1000 U/mL for TNF and < 10,000 U/mL for IL-1, the latter detected only in PMM. LPS alone enhanced the accumulation of MT above Zn+Dex in a dose dependent manner. A significant LPS response was obtained at 5 mg/L with a maximal stimulation above Zn+Dex of 38% at 10 mg/L. This direct stimulation of MT by LPS was not part of the response observed with PMM and KCM where the final LPS concentration in culture was only 0.1 mg/L. Other cytokines capable of synergy with Zn+Dex on MT synthesis were investigated. Interleukin-11 (IL-11) increased the Zn+Dex induction in a dose dependent manner with maximal stimulation at 100 U/mL of 40%. A small stimulation of 12% above Zn+Dex was obtained with leukaemia inhibitory factor (LIF) at concentrations greater than 100 U/mL. No enhancement of the Zn+Dex response was obtained with interleukin-3 (1000 U/mL), interleukin-4 (10 micrograms/L), platelet activating factor (5 nmol/L) or granulocyte-colony stimulating factor (5 micrograms/L). Neither IL-11 nor LIF enhanced the response obtained with Zn+Dex+IL-6. The results demonstrate that mediators present in arthritic rat serum and in LPS-stimulated PMM and KCM cause a quantitatively similar response on MT accumulation as IL-6. IL-11 and to a lesser extent LIF, are also potential mediators of MT synthesis in inflammation.
Coyle
P
P
Division of Clinical Biochemistry, Institute of Medical and Veterinary Science, Adelaide, Australia.
Philcox
J C
JC
Rofe
A M
AM
D000818:Animals; D001169:Arthritis, Experimental / Q000097:blood*; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology*; D017370:Interleukin-11 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology*; D053605:Leukemia Inhibitory Factor; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008222:Lymphokines / Q000494:pharmacology*; D008262:Macrophage Activation; D008264:Macrophages / Q000502:physiology*; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis*; D051381:Rats; D015032:Zinc / Q000494:pharmacology
D006131:Growth Inhibitors; D017370:Interleukin-11; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008070:Lipopolysaccharides; D008222:Lymphokines; D003907:Dexamethasone; D008668:Metallothionein; D015032:Zinc