1. ¹Department of Medicine II, Gastroenterology, Justus-Liebig-University Giessen, University Hospital Giessen and Marburg, Giessen, Germany
2. ²Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen, University Hospital Aachen, Aachen, Germany
3. ³Department of Anesthesiology and Intensive Care Medicine, Philipps-University Marburg, University Hospital Giessen and Marburg, Marburg, Germany
4. ⁴Department of Cardiovascular Surgery, Philipps-University Marburg, University Hospital Giessen and Marburg, Marburg, Germany

Correspondence: Professor Dr E Roeb, MD, Department of Medicine II, Gastroenterology, Justus-Liebig-University Giessen, University Hospital Giessen and Marburg, Paul-Meimberg-Str. 5, 35392 Giessen, Germany. E-mail: elke.roeb@innere.med.uni-giessen.de

^*These authors contributed equally to this study.

Received 17 March 2008; Revised 8 July 2008; Accepted 16 July 2008; Published online 15 September 2008.

Abstract

The pathophysiological mechanisms of thioacetamide (TAA)-induced hepatic fibrogenesis are not yet fully understood. In particular, the role of hepatic stellate cells (HSCs) remains unclear. We therefore examined proliferation and transdifferentiation of HSC as well as the underlying molecular mechanisms in TAA-induced fibrosis. Hepatic fibrogenesis was induced in mice by addition of TAA to drinking water. Liver damage was determined by assessment of alanine aminotransferase and aspartate aminotransferase levels, and measurement of collagen deposition. Additionally, expression patterns of -smooth muscle actin, glial fibrillary acidic protein (GFAP, specific hepatic biomarker for HSC), cysteine- and glycine-rich protein 2 (CRP2, specific marker of HSC transdifferentiation), tissue inhibitor of metalloproteinases-1, matrix metalloproteinase-9 (MMP-9), interleukins (IL-1, IL-6), platelet-derived growth factors (PDGF-B, PDGF-D) , tumor necrosis factor (TNF)-, and (transforming growth factor (TGF)-1 were assessed by real-time PCR. Transcription of GFAP and CRP2 were transiently upregulated during TAA-induced fibrogenesis (punctum maxima (p.m.) week 10 for GFAP and week 14 for CRP2). Similar transient expression patterns were demonstrated for IL-1, IL-6, TGF-1, and PDGF-B (p.m. week 12) whereas TNF- and PDGF-D continuously increased with ongoing liver injury. In particular, not only neutrophil granulocytes, but also macrophages and leukocytes served as a major source for MMP-9 expression. GFAP and CRP2 expression patterns demonstrated transiently increased HSC-activation during TAA-induced hepatic fibrogenesis. The rate of increase of transcription of GFAP correlated best with PDGF-B, whereas CRP2 levels correlated with PDGF-B, PDGF-D, and IL-1 expression. This study demonstrates for the first time that transiently increased activation patterns of HSC are observed in toxically induced hepatic fibrosis. Thus, TAA in drinking water is an effective and elegant model to induce reproducible states of liver fibrosis without parenchymal damage in mice.