OBJECTIVETo investigate the anti-fibrosis effects and mechanisms of fenofibrate on hepatic fibrosis using a mouse model of fibrosis induced by carbon tetrachloride (CCl4).

METHODSTwenty-six male C57BL mice were divided into the following three groups: CCL4-induced untreated model control (n = 10), CCl4-induced fenofibrate-treated model (n = 10), and uninduced/untreated normal control (n = 6). All animals were sacrificed after the 5 weeks of induction and treatment. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), hyaluronic acid (HA) and procollagen III amino-terminal peptide (PIIINP) were determined by routine biochemistry assays. Liver content of hydroxyproline (HYP) was measured by spectrophotometry. Liver content of malonic aldehyde (MDA) and superoxide dismutase (SOD) was measured by enzymatic assays. mRNA expression levels of liver fibrosis-associated factors were determined by PCR, and included alpha-smooth muscle actin (a-SMA), transforming growth factor-beta1 (TGFbeta1), type I collagen-alpha (Collagen1a), peroxisome proliferator-activated receptor-alpha (PPARa), and the inflammatory cytokines tumor necrosis factor alpha (TNFa) and interleukin-6 (IL-6). Finally, the degree of inflammation and fibrosis were assessed by histological analysis using hematoxylin-eosin and Sirius red staining.

RESULTSCompared to the untreated model group, the fenofibrate-treated model group showed significantly lower levels of serum ALT (55.72+/-1.20 vs. 38.72+/-1.25 IU/L), HA (236.20+/-17.57 vs. 152.9+/-13.06 mug/L) and PIIINP (41.66+/-1.89 vs. 34.32+/-1.53 mug/L) (all P less than 0.05). The fenofibrate-treated group also showed a significantly higher level of hepatic SOD content (untreated model: 67.00+/-4.65 vs. 101.1+/-5.32) but significantly lower level of hepatic MDA content (14.67+/-0.93 vs. 10.17+/-0.60 nmol/mg) and lower level of hepatic HYP content (0.67+/-0.80 vs. 0.41+/-0.50 mg/g) (all, P less than 0.05). In addition, the fenofibrate-treated group showed significantly reduced mRNA expression levels of a-SMA (6.83+/-0.88 vs. untreated model: 11.57+/-1.31), TGFbeta1 (67.83+/-4.65 vs. 112.30+/-4.81), Collagen1a (67.83+/-4.65 vs. 112.30+/-4.81), TNFa (17.43+/-2.32 vs. 37.83+/-4.69), and IL-6 (4.00+/-0.49 vs. 5.62+/-0.54), but significantly increased PPARa (0.30+/-0.03 vs. 0.18+/-0.03) (all, P less than 0.05). Finally, the degree of CCL4-induced hepatic fibrosis was attenuated by the fenofibrate treatment.

CONCLUSIONFenofibrate can reduce the degree of liver fibrosis in mice induced by CCl4. The mechanism may involve up-regulation of PPARa, inhibition of the inflammatory response, and enhancement of SOD antioxidant activity.