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

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.

[Regulation of hepatic stellate cell activation by interleukin-10/platelet derived growth factor/mitogen-activated protein kinase pathway].

OBJECTIVE: To investigate the regulatory effect of interleukin-10 (IL10) on the activation of hepatic stellate cells (HSC) through platelet derived growth factor (PDGF) and mitogen-activated protein kinase (MAPK) pathways. METHODS: HSC were divided randomly into 4 groups. Group 1 served as a control. HSC were incubated with 1 ng/ml, 5 ng/ml, and 25 ng/ml IL-10 in groups 2, 3 and 4. RT-PCR and western blot were used to detect the expression of PDGF and MAPK protein ERK and p38 and alpha-SMA. RESULTS: Compared with the control group, expressions of ERK, p38 and alpha-SMA of groups 2, 3 and 4 were significantly lower (F values were 240.47, 21.39, 28.86 respectively. IL-10 inhibited PDGF and MAPK protein ERK and p38 and alpha-SMA expression in a dose-dependent way. CONCLUSION: IL-10 inhibits activation of HSC through the PDGF/MAPK pathway.

[The effect of somatostatin analogue on expression of connective tissue growth factor gene of rat hepatic stellate cells].

OBJECTIVE: To investigate the effect of somatostatin analogue-octreotide (OCT) on expression of connective tissue growth factor (CTGF) gene of murine hepatic stellate cells (HSCs) in vitro. METHODS: HSCs separated from Sprague Dawley rats by in situ perfusion and Nycodenz gradient were divided into 5 groups. HSCs in 4 out of 5 groups were co-cultured with octreotide at different dosages, and the remaining group served as control. The expression of CTGF and TGF-beta mRNA were assessed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: OCT down-regulates the expression of CTGF and TGF-beta mRNA in HSCs. The effect is increased with a dose dependent manner. CONCLUSIONS: OCT could exert the inhibitory effect on HSCs by down-regulating the expression of CTGF and TGF-beta. This provides a potential for the prevention and management of hepatic fibrosis.

Expression of subtypes of somatostatin receptors in hepatic stellate cells.

AIM: To elucidate the mechanism by which somatostatin and its analogue exert the influence on liver fibrosis, and to investigate the mRNA expression of somatostatin receptors subtypes (SSTRs) and the distribution of somatostatin analogue octreotide in rat hepatic stellate cells (HSCs). METHODS: HSCs were isolated from Sprague Dawley (SD) rats by in situ perfusion and density gradient centrifugation. After several passages, the mRNA expression of 5 subtypes of SSTRs were assessed by reverse transcription-polymerase chain reaction (RT-PCR). HSCs were planted on coverslip and co-cultured with octreotide tagged by FITC. Then the distribution of FITC fluorescence was observed under laser scanning confocal microscope (LSCM) in 12-24 h. RESULTS: There were mRNA expression of SSTR2, SSTR3 and SSTR5 but not SSTR1 and SSTR4 in SD rat HSCs. The mRNA expression level of SSTR2 was significantly higher than that of other subtypes (P<0.01). FITC fluorescence of octreotide was clearly observed on the surface and in the cytoplasm, but not in the nuclei of HSCs under LSCM. CONCLUSION: The effect exerted by somatostatin and its analogues on HSCs may mainly depend on the expression of SSTR2, SSTR3 and SSTR5. Octreotide can perfectly combine with HSCs, and thereby exerts its biological activity on regulating the characters of active HSCs. This provides a potential prevention and management against liver fibrosis.