TY - JOUR
T1 - Acute hepatotoxicant exposure induces TNFR-mediated hepatic injury and cytokine/apoptotic gene expression
AU - Horn, Thomas L.
AU - O'Brien, Timothy D.
AU - Schook, Lawrence B.
AU - Rutherford, Mark S.
PY - 2000
Y1 - 2000
N2 - Tumor necrosis factor receptor knockout (TNFR KO) mice were used to examine the role of tumor necrosis factor-α (TNFα) signaling during acute hepatotoxicant exposure. Mice were exposed intraperitoneally (ip) to either vehicle, phosphate-buffered saline (PBS), or dimethylnitrosamine (DMN, 100 mg/kg) for 24 h. Histological evaluation showed that DMN-treated TNFR-2 KO mice had increased liver damage compared to wild type (WT), TNFR-1 KO, or TNFR double KO (DKO) mice. Also, 3 of 8 TNFR-2 KO mice died following DMN treatment, suggesting that hepatic TNFR-2 signaling produces protective responses that counteract TNFR-1-mediated damage. DMN-induced cellular infiltration was absent in TNFR-1-deficient mice, indicating that infiltrating cells do not exacerbate acute hepatotoxic events. In separate experiments, mice were exposed ip to either DMN (5.0 or 100 mg/kg), carbon tetrachloride (CCl4, 0.3 or 1.0 ml/kg), or corresponding PBS/corn oil controls for 6 or 24 h to compare the hepatic mRNA expression of cytokine- and apoptotic-associated genes. Following 24 h of DMN (100 mg/kg) or 6-24 h of CCl4 treatment, hepatic transcripts for TNFα, interferon (IFN)-γ, IL (interleukin)-1RI, and transforming growth factor (TGF)-βRII were induced. Hepatotoxicant-treated WT and TNFR DKO mice induced liver transcripts for the pro- and anti-apoptotic genes, Bax and Bcl-X(L), respectively, indicating TNF-independent gene activation. The anti-apoptotic gene, Bfl-1, was highly expressed in CCl4-treated, TNFR-positive strains, but minimally expressed in TNFR DKO mice, suggesting that hepatic Bfl-1 is TNF-regulated. Taken together, these data show that acute hepatotoxicant exposure is followed by upregulation of liver cytokine, cytokine receptor, and apoptotic transcripts, and that TNFα regulates various aspects of liver inflammation and injury in a TNFR-specific fashion.
AB - Tumor necrosis factor receptor knockout (TNFR KO) mice were used to examine the role of tumor necrosis factor-α (TNFα) signaling during acute hepatotoxicant exposure. Mice were exposed intraperitoneally (ip) to either vehicle, phosphate-buffered saline (PBS), or dimethylnitrosamine (DMN, 100 mg/kg) for 24 h. Histological evaluation showed that DMN-treated TNFR-2 KO mice had increased liver damage compared to wild type (WT), TNFR-1 KO, or TNFR double KO (DKO) mice. Also, 3 of 8 TNFR-2 KO mice died following DMN treatment, suggesting that hepatic TNFR-2 signaling produces protective responses that counteract TNFR-1-mediated damage. DMN-induced cellular infiltration was absent in TNFR-1-deficient mice, indicating that infiltrating cells do not exacerbate acute hepatotoxic events. In separate experiments, mice were exposed ip to either DMN (5.0 or 100 mg/kg), carbon tetrachloride (CCl4, 0.3 or 1.0 ml/kg), or corresponding PBS/corn oil controls for 6 or 24 h to compare the hepatic mRNA expression of cytokine- and apoptotic-associated genes. Following 24 h of DMN (100 mg/kg) or 6-24 h of CCl4 treatment, hepatic transcripts for TNFα, interferon (IFN)-γ, IL (interleukin)-1RI, and transforming growth factor (TGF)-βRII were induced. Hepatotoxicant-treated WT and TNFR DKO mice induced liver transcripts for the pro- and anti-apoptotic genes, Bax and Bcl-X(L), respectively, indicating TNF-independent gene activation. The anti-apoptotic gene, Bfl-1, was highly expressed in CCl4-treated, TNFR-positive strains, but minimally expressed in TNFR DKO mice, suggesting that hepatic Bfl-1 is TNF-regulated. Taken together, these data show that acute hepatotoxicant exposure is followed by upregulation of liver cytokine, cytokine receptor, and apoptotic transcripts, and that TNFα regulates various aspects of liver inflammation and injury in a TNFR-specific fashion.
KW - Apoptosis
KW - Bfl-1
KW - Carbon tetrachloride (CCl)
KW - Cytokines
KW - Dimethylnitrosamine (DMN)
KW - Hepatotoxicity
KW - Inflammation
KW - Necrosis
KW - TNF
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U2 - 10.1093/toxsci/54.1.262
DO - 10.1093/toxsci/54.1.262
M3 - Article
C2 - 10746953
AN - SCOPUS:0034118381
SN - 1096-6080
VL - 54
SP - 262
EP - 273
JO - Toxicological Sciences
JF - Toxicological Sciences
IS - 1
ER -