肝星状细胞与肝纤维化的研究进展

Expression of adiponectin during hepatic stellate cell (HSC) activation and the effect of adiponectin on expression of matrix metalloproteinase-13 in primary HSCs

AIM: To study trends in the expression of adiponectin during hepatic stellate cell (HSC) activation and the effects of adiponectin on mRNA and protein expression of matrix metalloproteinase-13 (MMP-13), which was closely related to liver fibrosis in primary HSCs.

METHODS: We isolated primary HSCs through improved two-step liver in situ perfusion, and investigated changes in expression of adiponectin during activation of primary HSCs. MTT was used to study the effect of adiponectin on proliferation of activated HSCs. We chose proper concentration of adiponectin and then divided primary HSCs into five groups according to the concentration of adiponectin. Real-time PCR was used to detect the difference of a-smooth muscle actin, adiponectin and MMP-13 expression between the groups. Enzyme linked immunosorbent assay (ELISA) was used to detect the quantity of MMP-13 protein secreted into the medium.

RESULTS: The survival rate of HSCs showed a linear correlation with adiponectin concentration (OR = 0.828). Expression of adiponectin was down-regulated during HSC activation. Adiponectin was able to inhibit the proliferation of HSCs. When the concentration of adiponectin was 500 mg/L, MMP-13 mRNA expression, in contrast with that in the control group, increased by 5.54 times. MMP-13 protein expression in adiponectin-treated cells increased significantly in contrast with that in the control group (30.951 mg/L vs 24.127 mg/L).

CONCLUSION: Expression of adiponectin was decreased during HSC activation. As a member of the adipokines, adiponectin can exert its potential anti-fibrotic activity through inhibition of HSC proliferation and up-regulation of expression of MMP-13 in primary HSCs.

Screening for genes regulated by gamma aminobutyric acid in hepatic stellate cells using suppression subtractive hybridization

AIM: To screen for genes regulated by gamma aminobutyric acid (GABA) in hepatic stellate cells (HSC) using suppression subtractive hybridization (SSH), and to investigate the biological function of GABA in the liver.

METHODS: The hepatic stellate cell line HSC-T6 was co-cultured with 10 μmol/L GABA for 24 h, after which mRNA was extracted and reverse transcribed into cDNA. HSC-T6 cells co-cultured with phosphate buffer saline (PBS) were used as controls. mRNAs upregulated by GABA were identified by SSH. Thirty one randomly selected clones were sequenced and analyzed bioinformatically.

RESULTS: Fifteen genes were found to be significantly up-regulated, including genes involved in DNA synthesis, apoptosis, mitochondrial function and tumor suppression. These results showed that GABA might promote HSC-T6 cell proliferation and inhibit apoptosis.

CONCLUSION: SSH technology successfully enabled the identification of genes that are differentially expressed in the presence and absence of GABA, demonstrating that GABA can affect the gene expression profiles of HSCs.

Effects of interferon-α on the early apoptosis of activated hepatic stellate cells

AIM: To investigate the effects of interferon-α on the early apoptosis of activated hepatic stellate cells (HSCs), and to further explore the anti-fibrosis mechanism of interferon-α (IFN-α).

METHODS: Rat HSCs were cultured in vitro, and then treated with different concentrations of IFN-α for 24 h. The viable cell count was measured by MTT assay, and the early apoptosis of HSCs was detected by flow cytometry using AnnexinV/PI-staining.

RESULTS: MTT assay showed a decrease of HSCs after IFN-α treatment, and the absorbency was significantly different from that of the control cells when 1 × 10⁷ and 1 × 10⁸ U/L IFN-α was used (t = 2.82, 5.44, both P < 0.05). Flow cytometry demonstrated that the early apoptosis rate of HSCs was increased with the elevation of IFN-α concentration, and the apoptosis rate was markedly different from that of the control cells when IFN-α was adopted at the concentrations of 1 × 10⁷ and 1 × 10⁸ U/L (t = 4.31, 5.07, both P < 0.05).

CONCLUSION: IFN-α can induce the early apoptosis of HSCs, which is probably one of the anti-fibrosis mechanism of interferon-α.

Effects of Ginkgo biloba extract on liver fibrosis induced by carbon tetrachloride in rats

AIM: To study the effects of Ginko biloba extract (EGb) on hepato-fibrosis induced by carbon tetrachloride (Cl₄) in rat model.

METHODS: Rat liver fibrosis model was induced by Cl₄ administration. Wistar rats were randomly divided into 5 groups: normal control group, a model group, a interven-tional group, a therapeutic group, and a EGb group. The EGb interventional group, apart from administration of Cl₄, was treated concurrently with EGb 0.3 g/kg, ig once a day; the EGb therapeutic group was treated with EGb 0.3 g/kg, ig once a day after cirrhosis was induced successfully, and the EGb group was treated only with EGb 0.3 g/kg, ig once a day. At the end of wk 8 and 16, all the rats were sacrificed. The pathological changes of liver were observed by H-E and Von-Gieson staining.The expression of mRNA and proteins of collagen I/TGF₁ in liver were determined by RT-PCR and immunohistochemistry.

RESULTS: The degree of liver fibrosis and level of mRNA and proteins of collagen I/TGF₁ in liver were significantly reduced in the EGb interventional and therapeutic groups compared with those in the model group (type I collagen mRNA: 0.0 778±0.054 vs 0.2 361±0.113, 0.1 075±0.007 vs 0.2 361±0.113, P < 0.01; type I collagen proteins: 0.2 563±0.0 009 vs 0.2 885±0.0 025, 0.2 541±0.0 076 vs 0.2 885±0.0 025 , P < 0.01; TGF₁ mRNA: 0.523±0.015 vs 0.956±0.049 , 0.524±0.009 vs 0.956±0.049, P < 0.01; TGF₁ proteins: 0.2 785±0.0 012 vs 0.3 015±0.0 012, 0.2 791±0.0 016 vs 0.3 015±0.0 012, P < 0.01).The EGb group had the same results as the normal control group.

CONCLUSION: EGb has prophylactic and therapeutic effects on CCl₄-induced rat liver fibrosis, probably through its anti-lipoperoxidation, suppressing the activation of hepatic stellate cells and transition and reducing the synthesis of hepatic type I collagen and TGF₁.