Technotes

Technotes

Liver Fibrosis and Cirrhosis

Introduction



Liver fibrosis results from chronic injury such as viral hepatitis (especially hepatitis B and C), alcohol abuse, drugs, metabolic diseases due to overload of iron or copper, congenital abnormalities or autoimmune attack of hepatocytes or bile duct epithelium. It is characterized by the encapsulation or replacement of injured tissue by a collagenous scar. Liver fi brosis is reversible, whereas cirrhosis, the later stage of fibrosis progression, featuring regenerative nodules surrounded by fibrous bands, is generally irreversible. Liver cirrhosis leads to an impaired liver function with an increased intrahepatic resistance (portal hypertension) and the development of hepatocellular carcinoma (HCC).

Carbon tetrachloride (CCl4)-induced hepatic fibrosis and cirrhosis in rodents is a well established and widely accepted experimental model for the study of liver fi brosis and cirrhosis. In many aspects it mirrors the pattern of human disease associated with toxic damage. For example, the α-SMA expression, Stellate cell activation and key matrix components including collagen-1, MMPs and their inhibitors TIMPs have been indicated in the pathogenesis of this model. CCl4 induction elicits a reproducible and predictable fi brotic response in liver, making it a valuable basis for preclinical pharmacology studies of anti-fibrotic and anti-cirrhotic therapeutics and the pathophysiology study of liver fi brosis-cirrhosis-HCC changes.


PharmaLegacy Models and Research Tools





Model

Acute liver injury & fi brogenesis model

Fibrosis and cirrhosis model

Animal

BALB/c mice

Wistar rats

Toxin

CCl4

CCl4

Bile duct ligation

Disease time

Onset Day 1-3, with recovery

EarlyReversible Early Micronodular

Self-limiting fi brosis: fi brosis:cirrhosis:cirrhosis: injury: 1 wk

4wks6 wks8 wks12 wks

Onset 1-10 weeks, no recovery

Similarities to

human disease

Acute injury with signifi cant hepatocellular necrosis

Chronic progression with fi brosis, cirrhosis, ascites and liver failure

Chronic progression

with fi brosis, cirrhosis. Irreversible

Characteristics

Reliable; Ideal model for studying the eff ects on acute liver injury and early fi brotic changes

The duration required for cirrhosis mainly depends upon the CCl4 dosage. Liver carcinogenesis may develop due to the carcinogenic eff ect of CCl4 as well as CCl4-induced liver cirrhosis. Good for investigating hepatocarcinoma growth in the liver cirrhosis environment

Rapid progression to cirrhosis. Short term for cholangitic injury; long-term for fi brosis/ cirrhosis

Primary endpoints

                  Liver functions: Serum ALT, AST, bilirubin, globulin and albumin

    Liver fi brogenic stress: Hepatic hydroxyproline

                Histopathology:        Collagen by Sirius red staining, connective tissue by Masson’s trichrome staining, SMA-α and collagen IHC

                         Biomarkers: Collagen I, collagen III, TGF-α, β by quantitative RT-PCR                                   Ascites:      Incidence and volume

Additional endpoints

         Fibrosis biomarkers: MMP, TIMP, HGF, TNF-α, cyclin by quantitative RT-PCR, Western blot, or ELISA Hepatocyte regeneration: IHC for PCNA, Ki67, BrdU

                           Apoptosis:    TUNEL

Special endpoints

TBARS, Hepatic glutathione, MDA content, Cytochrome P450 2E1

Cyclooxygenase-2 (COX-2)