Animal models for liver disease - A practical approach for translational research

Animal models are crucial for improving our understanding of human pathogenesis, enabling researchers to identify therapeutic targets and test novel drugs. In the current review, we provide a comprehensive summary of the most widely used experimental models of chronic liver disease, starting from early stages of fatty liver disease (non-alcoholic and alcoholic) to steatohepatitis, advanced cirrhosis and end-stage primary liver cancer. We focus on aspects such as reproducibility and practicality, discussing the advantages and weaknesses of available models for researchers who are planning to perform animal studies in the near future. Additionally, we summarise current and prospective models based on human tissue bioengineering.

Pan-PPAR agonist lanifibranor improves portal hypertension and hepatic fibrosis in experimental advanced chronic liver disease

BACKGROUND & AIMS

In advanced chronic liver disease (ACLD), deregulated hepatic necroinflammatory processes play a key role in the development of liver microvascular dysfunction, fibrogenesis, and increased hepatic vascular tone, resulting in progression of ACLD and portal hypertension. Given the current lack of an effective treatment, we aimed to characterise the effects of the pan-peroxisome proliferator-activated receptor (pan-PPAR) agonist lanifibranor in 2 preclinical models of ACLD, as well as in liver cells from patients with ACLD.

METHODS

Cirrhotic rats (thioacetamide or common bile duct ligation; TAA or cBDL) randomly received lanifibranor (100 mg/kg/day, po) or vehicle for 14 days (n = 12/group). PPAR expression, systemic and hepatic haemodynamics, presence of ascites, liver sinusoidal endothelial cell (LSEC) phenotype, hepatic stellate cell (HSC) activation, serum transaminases and albumin, hepatic macrophage infiltration, cytokine expression, and liver fibrosis were determined. Hepatic cells were isolated from the livers of patients with cirrhosis and their phenotype was evaluated after treatment with either lanifibranor or vehicle.

RESULTS

TAA-cirrhotic rats receiving lanifibranor showed significantly lower portal pressure compared with vehicle-treated animals (-15%; p = 0.003) without decreasing portal blood flow, indicating improved hepatic vascular resistance. Moreover, lanifibranor-treated TAA-rats showed decreased ascites, improved LSEC and HSC phenotypes, ameliorated hepatic microvascular function, reduced hepatic inflammation, and significant fibrosis regression (-32%; p = 0.020). These findings were confirmed in the cBDL rat model as well as in human liver cells from patients with cirrhosis, which exhibited phenotypic improvement upon treatment with lanifibranor.

CONCLUSIONS

Lanifibranor ameliorates fibrosis and portal hypertension in preclinical models of decompensated cirrhosis. Promising results in human hepatic cells further support its clinical evaluation for the treatment of ACLD.

LAY SUMMARY

Advanced chronic liver disease (ACLD) constitutes a serious public health issue for which safe and effective treatments are lacking. This study shows that lanifibranor improves portal hypertension and liver fibrosis, 2 key elements of the pathophysiology of ACLD, in preclinical models of the disease. Evaluation of lanifibranor in liver cells from patients with ACLD further supports its beneficial effects.

New Rat Model of Advanced NASH Mimicking Pathophysiological Features and Transcriptomic Signature of The Human Disease

Non-alcoholic steatohepatitis (NASH) is a major cause of chronic liver disease. However, most available animal models fail to reflect the whole spectrum of the disease. Liver fibrosis and portal hypertension are the strongest prognostic markers in advanced NASH. We herein aimed at developing a new model of NASH in male rats, obtained using a multi-hit protocol that combines the administration of a high fat and high-cholesterol diet with CCl4 and phenobarbital. Following this protocol, rats showed the full characteristics of advanced human NASH after 10 weeks and NASH with cirrhosis by 24 weeks. Specifically, our NASH rats exhibited: steatosis and metabolic syndrome, lipotoxicity, hepatocellular ballooning necrosis, inflammation and importantly, marked hepatic fibrosis and significant portal hypertension. Furthermore, a whole transcriptomic analysis of liver tissue from our rat model using next generation sequencing was compared with human NASH and illustrated the similarity of this pre-clinical model with the human disease. Pathway enrichment analysis showed that NASH animals shared a relevant number of central pathways involved in NASH pathophysiology, such as those related with cell death, as well as inflammatory or matrix remodeling. The present study defines a pre-clinical model of moderate and advanced NASH that mimics the human disease, including pathophysiologic characteristics and transcriptomic signature.