title: Interleukin-1β induces tumor necrosis factor-α secretion from rat hepatocytes.
abstract: OBJECTIVE
  Tumor necrosis factor-α (TNF-α) is a pleiotropic cytokine involved in various inflammatory diseases. The only production of TNF-α in the liver is thought to be from hepatic macrophages known as Kupffer cells, predominantly in response to bacterial lipopolysaccharide (LPS).
  
  
  METHODS
  Primary cultured rat hepatocytes were used to analyze TNF-α expression in response to the pro-inflammatory cytokine, interleukin-1β (IL-1β). Livers of rats subjected to LPS-induced endotoxemia were analyzed.
  
  
  RESULTS
  Immunocytochemistry and enzyme-linked immunosorbent assays demonstrated that IL-1β-treated rat hepatocytes secreted TNF-α, and RNA analyses indicated that TNF-α mRNA was induced specifically by IL-1β. Northern blot analysis showed that not only mRNA, but also a natural antisense transcript (asRNA), was transcribed from the rat Tnf gene in IL-1β-treated hepatocytes. TNF-α was detected in the hepatocytes of LPS-treated rats. Both TNF-α mRNA and asRNA were expressed in the hepatocytes of LPS-treated rats, human hepatocellular carcinoma and human monocyte/macrophage cells. To disrupt the interaction between TNF-α asRNA and TNF-α mRNA, sense oligonucleotides corresponding to TNF-α mRNA were introduced into rat hepatocytes resulting in significantly increased levels of TNF-α mRNA. One of these sense oligonucleotides increased a half-life of TNF-α mRNA, suggesting that the TNF-α asRNA may reduce the stability of TNF-α mRNA.
  
  
  CONCLUSIONS
  IL-1β-stimulated rat hepatocytes are a newly identified source of TNF-α in the liver. TNF-α mRNA and asRNA are expressed in rats and humans, and the TNF-α asRNA reduces the stability of the TNF-α mRNA. Hepatocytes and TNF-α asRNA may be therapeutic targets to regulate levels of TNF-α mRNA.
authors: Department of Biomedical Sciences, College of Life Sciences, Shiga, Japan.
authors: Emi
authors: E
authors: Yoshigai
authors: Takafumi
authors: T
authors: Hara
authors: Hiroyuki
authors: H
authors: Inaba
authors: Iwao
authors: I
authors: Hashimoto
authors: Yoshito
authors: Y
authors: Tanaka
authors: Masaki
authors: M
authors: Kaibori
authors: Tominori
authors: T
authors: Kimura
authors: Tadayoshi
authors: T
authors: Okumura
authors: A-Hon
authors: AH
authors: Kwon
authors: Mikio
authors: M
authors: Nishizawa
keywords: antisense transcript; cancer; gene expression; inflammation; mRNA stability