Effects of interleukin-10 on activation and apoptosis of hepatic stellate cells in fibrotic rat liver

Abstract

Aim: To study the effects of interleukin-10 (IL-10) on the expression of alpha-smooth muscle actin (alpha-SMA), nuclear factor- kappa B(NF- kappa B) and Fas/Fas ligand (FasL) in hepatic stellate cells of experimental rats with hepatic fibrosis.

Methods: Sixty clean SD rats were randomly divided into control group (group N), liver fibrotic group (group C) and IL-10 treatment group (group I). Control group received intraperitoneal injection of saline (2 mL/kg), twice a week. Fibrotic group was injected intraperitoneally with 50% carbon tetrachloride (CCl(4)) (2 mL/kg), twice a week. IL-10 treatment group was given IL-10 at a dose of 4 microg/kg 20 minutes before CCl(4) administration from the third week. Hepatic stellate cells (HSCs) were isolated from these rats at the seventh and eleventh weeks during the course of liver fibrosis, respectively. The expression of alpha-SMA and NF- kappa B in HSCs was measured by S-P immunohistochemistry. The expression of Fas and FasL mRNA was measured by RT-PCR. Furthermore, liver tissues were harvested from three groups at the same time.

Results: The CCl(4)- induced experimental rat hepatic fibrosis model was established successfully. The purity of extracted hepatic stellate cells was about 95% and the yield of hepatic stellate cells was 1.2-2.3 x 10(6)/g liver tissue averagely. The positive expression of alpha-SMA and NF- kappa B was 36.5% and 28.5% respectively in group N. The positive levels of alpha-SMA and NF- kappa B were increased significantly in group C compared to group N (P<0.01). The positive signals decreased significantly (P<0.05) in group I. In the 11th week, the HSCs of group I became round with visible pyknotic nuclei. The expression of NF- kappa B in group C was significantly increased in a time-dependent manner (P<0.01), but there was no difference in the alpha-SMA expression (P>0.05). The mRNA of Fas and FasL in group C was significantly increased in a time-dependent manner compared to that in control group. After treated with IL-10, the expression level of Fas and FasL was higher in group I than in group C.

Conclusion: The positive expression of alpha-SMA and NF- kappa B in hepatic stellate cells is decreased by ectogenic IL-10 in liver fibrosis induced by CCl(4). The expression of Fas and FasL is increased in the course of liver fibrosis, and is further increased by IL-10. IL-10 could inhibit the activation of HSCs and cause apoptosis of activated HSCs.

Figure 1

Liver of rats in groups C (A) and I (B) (week 11, H-E staining, ×100)

Figure 2

Autofluorescence (A) and desmin staining (B) of HSCs.

Figure 3

α-SMA in HSCs of group C (A) in week 11 and group I (B) in week 7; NF-κB in HSCs of group C (C) in week 11 and group I (D) in week 7; and changes of HSCs in group I (E) in week 11.

Figure 4

Expressions of α-SMA (A), NF-κB (B), Fas mRNA (C), FasL mRNA (D), Fas (E), and FasL (F) in HSCs.