Activation of hepatic stellate cells is associated with cytokine expression in thioacetamide-induced hepatic fibrosis in mice

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 a-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-1b, IL-6), platelet-derived growth factors (PDGF-B, PDGF-D) , tumor necrosis factor (TNF)-a, and (transforming growth factor (TGF)-b1 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-1b, IL-6, TGF-b1, and PDGF-B (p.m. week 12) whereas TNF-a 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-1b 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.

F-actin cytoskeleton reorganization is associated with hepatic stellate cell activation

“…Increased expression levels of α-SMA and collagen type 1 are considered to be the major markers of HSC activation (12,13). Compared with the control group, treatment with Jas increased the mRNA levels of α-SMA and collagen type 1.…”

Mesenchymal Stem/Stromal Cells in Liver Fibrosis: Recent Findings, Old/New Caveats and Future Perspectives

“…Other trackers, such as magnetic nanoparticles, quantum dots or DiI/DiR can be uptaken in vivo by macrophages [72]. In different liver fibrosis/cirrhosis in vivo models, abundant highly autofluorescent ceroid-ladden macrophage cells are found in proximity to portal areas and fibrotic bridges [74,75], which makes difficult to truly identify cells under the fluorescence microscope. By mean of chromogenic immunostaining techniques and using green fluorescent protein (GFP) as marker we were able to show that significant numbers of MSCs are present within liver fibrotic parenchyma at least during the first 7 days after their systemic application [76].…”

Novel Mouse Models of Hepatocarcinogenesis with Stepwise Accumulation of Genetic Alterations

“…Mouse models of HCC are divided into two types: chemical induced and genetically engineered. Chemical-induced models of HCC include mice exposed to diethylnitrosamine [22], aflatoxin B1 [23] and thioacetamide [24], but these models mainly reflect chemical-induced carcinogenesis, although chronic inflammation might be related to cancer development to some extent. Genetically engineered mouse models of HCC include c-myc/TGF-α transgenic mice [25], Trp53 knockout mice [26] and others.…”