Cytokine gene expression by Kupffer cells in experimental alcoholic liver disease

Abstract

Kupffer cell-derived cytokines are believed to play pivotal paracrine roles in the pathogenesis of alcoholic liver disease (ALD). To evaluate this hypothesis, Kupffer cell gene expression of tumor necrosis factor-alpha (TNF alpha), interleukin (IL)-6, and transforming growth factor-beta 1 (TGF beta 1) were directly examined in the rat model of ALD. Kupffer cells were isolated from the model after 10 and 17 weeks of intragastric ethanol infusion. These two durations resulted in focal hepatocellular injury and liver fibrogenesis, respectively. Oxidative stress as assessed by the hepatic level of thiobarbituric acid reacting substances, was evident at 10 weeks but more pronounced at 17 weeks. The steady state messenger RNA (mRNA) levels of the cytokines were examined by Northern blot analysis using RNA samples from freshly isolated Kupffer cells, and the release of the cytokines was quantitated ex vivo using a 3-day culture. The mRNA levels of TNF alpha and TGF beta 1 were significantly increased by 183% and 204% at 10 weeks and 231% and 295% at 17 weeks in the ethanol-fed rats, respectively. Ex vivo release of TNF activity by control Kupffer cells was undetectable or very low (< 2U/10(5) cells/18 hours) at both time points, but the cells from the ethanol-fed animals secreted appreciably more TNF (27.8 +/- 7.6 U at 10 weeks and 40.4 +/- 10.3 U at 17 weeks). The release of the latent TGF beta 1 protein was also coordinately increased by 143% at 10 weeks and 238% at 17 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)