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Overexpression of granulocyte-macrophage colony-stimulating factor in mouse liver enhances the susceptibility of lipopolysaccharide leading to massive apoptosis of hepatocytes

Authors


Yukihiro Shimizu, MD, PhD, The Third Department of Internal Medicine Toyama Medical and Pharmaceutical University 2630 Sugitani, Toyama 930-0194, Japan.
Tel: 81 76 434 7301
Fax: 81 76 434 5027
e-mail: yukihiro-tym@cc.umin.ac.jp

Abstract

Abstract: Background/Aims: We examined whether antigen-nonspecific accumulation of dendritic cells (DCs) and macrophages in the liver by the overexpression of granulocyte macrophage-colony stimulating factor (GM-CSF) could prime severe liver injury after LPS injection.

Methods: We injected a recombinant adenovirus encoding GM-CSF intravenously (AdGM), and LPS was administered 7 days later. Liver histology, serum alanine aminotransferase (ALT) levels and apoptosis of hepatocytes were examined.

Results: Liver histology of the AdGM-primed mice showed marked infiltrates of mononuclear cells (DCs and macrophages) without granuloma formation on day 7. Expression of toll-like receptor-4 on intrahepatic mononuclear cells isolated from AdGM-primed mice was up-regulated. After LPS injection, serum ALT levels in AdGM-primed mice reached about 6000 IU/l at 12 h, and all those mice died within 24 h. Hemorrhagic liver injury with massive apoptosis of hepatocytes was histologically recognized. When AdGM and LPS were injected in FasL-deficient C57BL/6J-gld/gld mice, serum ALT levels were not elevated by the pretreatment with a neutralizing anti-TNF-α antibody.

Conclusions: Our present study provides a new model of severe liver injury, in which antigen-nonspecific accumulation of DCs and macrophages in the liver by overexpressing GM-CSF enhances the susceptibility to LPS, leading to hemorrhagic liver injury with massive hepatocyte apoptosis after LPS injection.

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