Effect of ligand of peroxisome proliferator-activated receptor gamma on the biological characters of hepatic stellate cells

Abstract

Aim: To study the effect of rosiglitazone, which is a ligand of peroxisome proliferator-activated receptor gamma (PPARgamma), on the expression of PPARgamma in hepatic stellate cells (HSCs) and on the biological characteristics of HSCs.

Methods: The activated HSCs were divided into three groups: control group, 3 micromol/L rosiglitazone group, and 10 micromol/L rosiglitazone group. The expression of PPARgamma, alpha-smooth muscle actin (alpha-SMA), and type I and III collagen was detected by RT-PCR, Western blot and immunocytochemical staining, respectively. Cell proliferation was determined with methylthiazolyltetrazolium (MTT) colorimetric assay. Cell apoptosis was demonstrated with flow cytometry.

Results: The expression of PPARgamma at mRNA and protein level markedly increased in HSCs of 10 micromol/L rosiglitazone group (t value was 10.870 and 4.627 respectively, P<0.01 in both). The proliferation of HSCs in 10 micromol/L rosiglitazone group decreased significantly (t = 5.542, P<0.01), alpha-SMA expression level and type I collagen synthesis ability were also reduced vs controls (t value = 10.256 and 14.627 respectively, P<0.01 in both). The apoptotic rate of HSCs significantly increased in 10 micromol/L rosiglitazone group vs control (chi(2) = 16.682, P<0.01).

Conclusion: By increasing expression of PPARgamma in activated HSCs, rosiglitazone, an agonist of PPARgamma, decreases alpha-SMA expression and type I collagen synthesis, inhibits cell proliferation, and induces cell apoptosis.

Figure 1

PPARγ mRNA level. A: Expression of PPARγ mRNA. Lane 1, 10 µmol/L rosiglitazone group; lane 2, 3 µmol/L rosiglitazone group; lane 3, control group; B: Expression of β-actin.

Figure 2

PPARγ protein was assessed with Western blotting. Lane 1, 10 µmol/L rosiglitazone group; lane 2, 3 µmol/L rosiglitazone group; lane 3, control group.

Figure 3

Immunocytochemistry of rHSC-99 ×100. A: Positive of PPARγ in 10 µmol/L rosiglitazone group; B: positive of α-SMA in control group; C: weak positive of α-SMA in 10 µmol/L rosiglitazone group.