Pro- and Anti-Inflammatory Gene Expression in the Murine Small Intestine and Liver After Chronic Exposure to Alcohol

Authors

  • Sherry Fleming,

    1. Departments of Microbiology and Immunology (SF, ST, SNV, ESM), and Medicine (TS-D, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, and the Department of Microbiology (ST, YK), Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
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    • *

      SF and ST contributed equally to the work presented in this study.

  • Satoshi Toratani,

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    • *

      SF and ST contributed equally to the work presented in this study.

  • Terez Shea-Donohue,

    1. Departments of Microbiology and Immunology (SF, ST, SNV, ESM), and Medicine (TS-D, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, and the Department of Microbiology (ST, YK), Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
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  • Yoshiko Kashiwabara,

    1. Departments of Microbiology and Immunology (SF, ST, SNV, ESM), and Medicine (TS-D, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, and the Department of Microbiology (ST, YK), Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
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  • Stefanie N. Vogel,

    1. Departments of Microbiology and Immunology (SF, ST, SNV, ESM), and Medicine (TS-D, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, and the Department of Microbiology (ST, YK), Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
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  • Eleanor S. Metcalf

    Corresponding author
    1. Departments of Microbiology and Immunology (SF, ST, SNV, ESM), and Medicine (TS-D, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, and the Department of Microbiology (ST, YK), Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
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  • Supported by NIH Grant AA11622, USUHS RO73FE, and a Fellowship from the Japan Health Sciences Foundation ST), and by NIH Grant RO3 AA11622 (ESM), USUHS Grant RO73FE (ESM), and a grant from Genetics Institute, Cambridge, MA (ESM).

  • The opinions or assertions contained within are the private views of the authors and should not be construed as official or necessarily reflecting the views of the Uniformed Services University of the Health Sciences or the Department of Defense.

Reprint requests: Dr. Eleanor S. Metcalf, Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814; Fax: 301-295-3773; E-mail: emetcalf@usuhs.mil

Abstract

Background: Endotoxin has been proposed to play a primary role in ALD, by initiating an inflammatory cascade within the liver. Although the source of these cytokines has been presumed to be circulating monocytes or tissue macrophages, ethanol-induced, nonhepatic sources of soluble mediators recently have been identified. One potential, but not clearly defined, extrahepatic source of cytokines in ALD is the intestine. In the current study, we hypothesized that alcohol would alter cytokine expression within the small intestine of mice exposed to ethanol and that LPS would alter levels of cytokine expression even more dramatically.

Methods: Mice were fed a modified Lieber-DeCarli liquid ethanol or control diet for up to 14 days prior to injecting either saline or LPS. Plasma alanine aminotransferase (ALT) and cytokine levels, histology, and RT-PCR of pro- and anti-inflammatory cytokine gene expression were determined from distal ileum and liver samples. Translocation of intestinal bacterial flora also was assessed.

Results: Ethanol exposure upregulated basal gene expression of IL-1β, TNF-α, IL-6, and iNOS in the distal ileum, but similar effects of ethanol on the liver were not observed. In contrast, LPS challenge of ethanol-exposed mice increased intestinal gene expression of some cytokines, but decreased expression of others. These effects were not associated with bacterial translocation. Also, ethanol alone induced a modest increase in both ICAM-1 and TLR4 mRNA expression in the intestine, but expression of both molecules was inhibited in mice that received both ethanol and LPS. Finally, whereas basal levels of hepatic IL-11 mRNA were not elevated by exposure to ethanol, intestinal IL-11 mRNA levels were increased more than100-fold.

Conclusions: These studies are the first to show that ethanol affects cytokine gene expression in the ileum and identifies the ileum as a potential target for ethanol effects. In addition, our results suggest that IL-11 expression may be enhanced in the intestine to help repair or protect this organ from alcohol-induced damage. Collectively, these studies suggest that both pro- and anti-inflammatory soluble mediators in the intestine maintain and exacerbate the local hepatic response to ethanol.

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