Precision-cut liver slices as a model for the early onset of liver fibrosis to test antifibrotic drugs

Protective effects of Lycium barbarum polysaccharides against carbon tetrachloride-induced hepatotoxicity in precision-cut liver slices in vitro and in vivo in common carp (Cyprinus carpio L.)

The protective effects of Lycium barbarum polysaccharides (LBPs) against carbon tetrachloride-induced hepatotoxicity in common carp were investigated in vitro and in vivo. Precision-cut liver slices (PCLSs) were employed as an in vitro model system. LBPs (0.1, 0.3 and 0.6 mg/ml) was added to PCLSs culture system before (pre-treatment), after (post-treatment) and both before and after (pre- and post-treatment) the exposure of PCLSs to 12 mM CCl4. The supernatants and PCLSs were collected for biochemical analyses. Results showed that LBPs inhibited the elevations of the marker enzymes (GOT, GPT, LDH and AKP) and MDA induced by CCl4 in all LBPs treatments and it also enhanced the suppressed antioxidant enzymes (SOD, CAT, GSH-Px, GST) and GSH, in the pre-treatment and pre- and post-treatment. In vivo, fish were fed diets containing LBPs at 0.1, 0.5 and 1% for 60 d before an intraperitoneal injection of 30% CCl4 in olive oil at a volume of 0.05 ml/10 g body weight. At 72 h post-injection, blood and liver samples were taken for biochemical analyses. Results showed that LBPs at 0.5 and 1% significantly reduced the levels of GOT, GPT and LDH in the serum; the decreases of the antioxidant enzymes and the increase of MDA in the liver tissue were inhibited markedly. Moreover, LBPs even at lower concentration exerted a potent DPPH scavenging activity. Overall results prove the hepatoprotective and antioxidant effects of LBPs and support the use of LBPs as a hepatoprotective agent in fish.

Developing an in vitro screening assay platform for evaluation of antifibrotic drugs using precision-cut liver slices

Background

Precision-cut liver slices present different cell types of liver in a physiological context, and they have been explored as effective in vitro model systems to study liver fibrosis. Inducing fibrosis in the liver slices using toxicants like carbon tetrachloride is of less relevance to human disease conditions. Our aim for this study was to establish physiologically relevant conditions in vitro to induce fibrotic phenotypes in the liver slices.

Results

Precision-cut liver slices of 150 μm thickness were obtained from female C57BL/6 J mice. The slices were cultured for 24 hours in media containing a cocktail of 10 nM each of TGF-β, PDGF, 5 μM each of lysophosphatidic acid and sphingosine 1 phosphate and 0.2 μg/ml of lipopolysaccharide along with 500 μM of palmitate and were analyzed for triglyceride accumulation, stress and inflammation, myofibroblast activation and extracellular matrix (ECM) accumulation. Incubation with the cocktail resulted in increased triglyceride accumulation, a hallmark of steatosis. The levels of Acta2, a hallmark of myofibroblast activation and the levels of inflammatory genes (IL-6, TNF-α and C-reactive protein) were significantly elevated. In addition, this treatment resulted in increased levels of ECM markers - collagen, lumican and fibronectin.

Conclusions

This study reports the experimental conditions required to induce fibrosis associated with steatohepatitis using physiologically relevant inducers. The system presented here captures various aspects of the fibrosis process like steatosis, inflammation, stellate cell activation and ECM accumulation and serves as a platform to study the liver fibrosis in vitro and to screen small molecules for their antifibrotic activity.

Murine precision-cut liver slices (PCLS): a new tool for studying tumor microenvironments and cell signaling ex vivo

Background

One of the most insidious characteristics of cancer is its spread to and ability to compromise distant organs via the complex process of metastasis. Communication between cancer cells and organ-resident cells via cytokines/chemokines and direct cell-cell contacts are key steps for survival, proliferation and invasion of metastasized cancer cells in organs. Precision-cut liver slices (PCLS) are considered to closely reflect the in vivo situation and are potentially useful for studying the interaction of cancer cells with liver-resident cells as well as being a potentially useful tool for screening anti-cancer reagents. Application of the PCLS technique in the field of cancer research however, has not yet been well developed.

Results

We established the mouse PCLS system using perfluorodecalin (PFD) as an artificial oxygen carrier. Using this system we show that the adherence of green fluorescent protein (GFP) labeled MDA-MB-231 (highly invasive) cells to liver tissue in the PCLS was 5-fold greater than that of SK-BR-3 (less invasive) cells. In addition, we generated PCLS from THOC5, a member of transcription/export complex (TREX), knockout (KO) mice. The PCLS still expressed Gapdh or Albumin mRNAs at normal levels, while several chemokine/growth factor or metalloprotease genes, such as Cxcl12, Pdgfa, Tgfb, Wnt11, and Mmp1a genes were downregulated more than 2-fold. Interestingly, adhesion of cancer cells to THOC5 KO liver slices was far less (greater than 80% reduction) than to wild-type liver slices.

Conclusion

Mouse PCLS cultures in the presence of PFD may serve as a useful tool for screening local adherence and invasiveness of individual cancer cells, since single cells can be observed. This method may also prove useful for identification of genes in liver-resident cells that support cancer invasion by using PCLS from transgenic liver.

The effect of antifibrotic drugs in rat precision-cut fibrotic liver slices

Two important signaling pathways in liver fibrosis are the PDGF- and TGFβ pathway and compounds inhibiting these pathways are currently developed as antifibrotic drugs. Testing antifibrotic drugs requires large numbers of animal experiments with high discomfort. Therefore, a method to study these drugs ex vivo was developed using precision-cut liver slices from fibrotic rat livers (fPCLS), representing an ex vivo model with a multicellular fibrotic environment. We characterized the fibrotic process in fPCLS from rat livers after 3 weeks of bile duct ligation (BDL) during incubation and tested compounds predominantly inhibiting the TGFβ pathway (perindopril, valproic acid, rosmarinic acid, tetrandrine and pirfenidone) and PDGF pathway (imatinib, sorafenib and sunitinib). Gene expression of heat shock protein 47 (Hsp47), α smooth muscle actin (αSma) and pro-collagen 1A1 (Pcol1A1) and protein expression of collagens were determined. During 48 hours of incubation, the fibrosis process continued in control fPCLS as judged by the increased gene expression of the three fibrosis markers, and the protein expression of collagen 1, mature fibrillar collagen and total collagen. Most PDGF-inhibitors and TGFβ-inhibitors significantly inhibited the increase in gene expression of Hsp47, αSma and Pcol1A1. Protein expression of collagen 1 was significantly reduced by all PDGF-inhibitors and TGFβ-inhibitors, while total collagen was decreased by rosmarinic acid and tetrandrine only. However, fibrillar collagen expression was not changed by any of the drugs. In conclusion, rat fPCLS can be used as a functional ex vivo model of established liver fibrosis to test antifibrotic compounds inhibiting the PDGF- and TGFβ signalling pathway.

The role of chemokines in hepatitis C virus-mediated liver disease

The hepatitis C virus (HCV) is a global health problem affecting more than 170 million people. A chronic HCV infection is associated with liver fibrosis, liver cirrhosis and hepatocellular carcinoma. To enable viral persistence, HCV has developed mechanisms to modulate both innate and adaptive immunity. The recruitment of antiviral immune cells in the liver is mainly dependent on the release of specific chemokines. Thus, the modulation of their expression could represent an efficient viral escape mechanism to hamper specific immune cell migration to the liver during the acute phase of the infection. HCV-mediated changes in hepatic immune cell chemotaxis during the chronic phase of the infection are significantly affecting antiviral immunity and tissue damage and thus influence survival of both the host and the virus. This review summarizes our current understanding of the HCV-mediated modulation of chemokine expression and of its impact on the development of liver disease. A profound knowledge of the strategies used by HCV to interfere with the host's immune response and the pro-fibrotic and pro-carcinogenic activities of HCV is essential to be able to design effective immunotherapies against HCV and HCV-mediated liver diseases.