肝纤维化发病机制与临床诊断的研究进展

Progress in research of Chinese herbal medicines with anti-hepatic fibrosis activity

Hepatic fibrosis is a common pathological process for various kinds of chronic liver diseases to progress to cirrhosis and even liver cancer. Currently, many natural medicines have been reported and demonstrated to be effective in preventing and curing hepatic fibrosis with few side effects. In China, these medicines are easily available because of the wide raw material source here. These medicines exert anti-fibrosis effects via multiple targets at multiple levels. Therefore, they have their own advantages in healing hepatic fibrosis. This paper summarizes the mechanism of hepatic fibrosis and the progress in research of natural medicines and their active ingredients that have anti-hepatic fibrosis activity, with an aim to provide some clues to preventing and curing hepatic fibrosis with Chinese herbal medicines.

Effect of saikosaponin-d on expression of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 in activated HSC-T6 cells: Underlying mechanism

AIM: To investigate the effect of saikosaponin-d (SSd) on the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and matrix metalloproteinase-1 (MMP-1) in activated HSC-T6 cells and the underlying mechanism, and to explore the mechanism of action of phytoestrogens on liver fibrosis to provide a theoretical basis for their clinical application.

METHODS: Rat hepatic stellate cell line HSC-T6 was used. Cells were seeded into cell culture plates with DMEM high glucose medium containing 10% fetal bovine serum for 24 h. After 1 h pretreatment with estrogen receptor (ER) antagonist (1 µmol/L) or P38 MAPK antagonist SB203580 (50 µmol/L), cells were incubated with SSd (5 µmol/L) or estradiol (E₂) (1 µmol/L) for 24 h. ELISA was used to detect the contents of type I collagen (COL-I), MMP-1, and TIMP-1 in cell culture supernatants. Western blot analysis was used to detect the expression of MMP-1, TIMP-1, P38 and PP38 in HSC-T6 cells.

RESULTS: Compared with the control group, SSd or E₂ treatment significantly decreased COL-1 (140.95 ± 12.14, 143.58 ± 4.81 vs 198.98 ± 15.08) and TIMP-1 contents (0.23 ± 0.01, 0.21 ± 0.01 vs 0.31 ± 0.01) in cell culture supernatants and P-P38 expression (0.51 ± 0.14, 0.52 ± 0.12 vs 1.00 ± 0.11), and significantly elevated MMP-1 content (0.0127 ± 0.0008, 0.0116 ± 0.0004 vs 0.0049 ± 0.0001, P < 0.01). In the inhibitor group, the expression levels of COL-1, TIMP-1 and P-P38 increased (P < 0.01) and MMP-1 content decreased (P < 0.01). MMP-1 expression was significantly increased in cells treated with P38 inhibitor SB203580 for 24 h compared with the control group (3.58 ± 0.35 vs 1.00 ± 0.15, P < 0.01), and TIMP-1 expression was significantly decreased (0.52 ± 0.14 vs 1.00 ± 0.18, P < 0.05).

CONCLUSION: The anti-fibrotic effect of SSd may be attributed to its inhibition of P38/MAPK activation and modulation of downstream molecules MMP-1 and TIMP-1 expression, which can promote the degradation of extracellular matrix via stimulating ERβ.

Interventional effects of Plumbago zeylanica L. decoction on CCl4-induced hepatic fibrosis in rats

AIM: To investigate the intervention effects of Plumbago zeylanica L. decoction (PZL) on carbon tetrachloride (CCl4)-induced hepatic fibrosis in rats.

METHODS: A model of hepatic fibrosis was established by subcutaneous injection of 40% CCl₄ in rats. SD rats were randomly divided into five groups (10 rats in each group): a model group, a positive control group (colchicines 0.25 mg/kg), high-, medium- and low-dose PZL groups. A blank control group was also established. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were tested using a ultraviolet-visible pectrophotometer (UV). Serum levels of total bilirubin (TBIL), direct bilirubin (DBIL) and indirect bilirubin (IBIL) were detected by the method of vanadate oxidation. The contents of hyaluronic acid (HA), laminin (LN), procollagen type Ⅲ (P3NP), and type Ⅳ collagen (CⅣ) were detected by radioimmunoassay. HE staining was used to examine the degree of hepatic fibrosis, and the expression of collagen type Ⅰ and Ⅲ and α-SMA in hepatic tissues was detected by immunohistochemistry.

RESULTS: Compared with the model group, the levels of ALT, AST, TBIL, DBIL and IBIL were significantly decreased in the PZL groups. PZL could also significantly reduce the contents of HA, LN, P3NP, and CⅣ. HE staining showed that PZL could significantly reduce the degree of hepatic fibrosis. Immunohistochemistry showed that the expression of collagen type Ⅰ and Ⅲ and α-SMA in hepatic tissues was decreased by PZL (P < 0.05 or P < 0.01), and the effect was dose-dependent.

CONCLUSION: PZL has a protective effect against CCl₄-induced liver fibrosis in rats possibly by improving the liver function, inhibiting liver cell degeneration and necrosis, reducing secretion of collagen by hepatic stellate cells and promoting extracellular matrix degradation.

Effect of fluid shear stress on activation of hepatic stellate cells and expression of α-SMA, collogen-Ⅰ, collogen-Ⅲ, MMP-2, and MMP-9

AIM: To investigate the effects of different types of fluid shear stress on the activation of hepatic stellate cells-T6 (HSC-T6) and expression of α-SMA, collogen-Ⅰ, collogen-Ⅲ, MMP-2, and MMP-9.

METHODS: HSC-T6 cells were seeded on slides precoated with rat tail collagen and exposed to different types of fluid shear stress (6, 12, 20 dyn/cm²) for 3 h, and static cells served as controls. The gene expression of α-SMA, collogen-Ⅰ, collogen-Ⅲ, MMP-2 and MMP-9 was assayed by real-time RT-PCR. Intracellular α-SMA protein was analyzed by FACS.

RESULTS: After treatment by fluid shear stress, the expression of α-SMA and collogen-Ⅲ was lower in the low shear stress (6 dyn/cm²) group than that in the control group. However, the expression of α-SMA was higher in the moderate (12 dyn/cm²) and high (20 dyn/cm²) shear stress groups than that in the control group, and the expression of collogen-Ⅲ was higher in the high shear stress group than that in the control group. There was no significant difference in the expression of collogen-Ⅰ among different fluid shear stress groups. The expression of MMP-2 was higher that in three fluid shear stress groups than in the control group.

CONCLUSION: High fluid shear stress can lead to the activation of HSC-T6 cells and promote the mRNA expression of α-SMA, collogen-Ⅲ and MMP-2.

Effect of total flavone of Litchi chinensis Sonn on the expression of Bcl-2 and Bax in hepatic fibrosis in rats

AIM: To study the effect of total flavone of Litchi chinensis Sonn (TFL) on liver cell apoptosis in rats with hepatic fibrosis and to explore possible mechanisms involved.

METHODS: Fifty rats were randomly divided into five groups: blank control group, colchicine group, model group, low- and high-dose TFL groups. Hepatic fibrosis was induced in rats by intraperitoneal injection of dimethylnitrosamine. The TFL groups were intragastrically administered with different doses of TFL for 6 wk, while the blank control group and colchicine group were given normal saline and colchicine, respectively. After treatment, liver samples were taken to examine the degree of liver fibrosis by HE and Masson staining and to detect Bcl-2 and Bax expression by immunohistochemistry. Serum ALT and AST levels were also measured.

RESULTS: The expression of Bcl-2 and Bax in the model group was significantly higher than that in the normal group (both P = 0.000). The expression of Bcl-2 was higher and that of Bax was lower in the TFL groups and colchicine group than in the model group (Bcl-2: P = 0.000, 0.047, 0.021; Bax: P = 0.000, 0.014, 0.007), and in the high-dose TFL group than in the low-dose TFL group (P = 0.018, 0.002). Bcl-2 and Bax expression showed no significant difference between the low-dose TFL group and colchicine group (P = 0.726, 0.767). The severity of liver fibrosis was positively correlated with Bax expression (P = 0.000) but negatively with Bcl-2 expression (P = 0.000). Serum levels of ALT and AST were significantly lower in the blank control group, TFL groups and colchicine group than in the model group (all P = 0.000), but showed no significant difference between the low-dose TFL group and colchicine group (P = 0.597, 0.669).

CONCLUSION: TFL can resist hepatic fibrosis and improve liver function possibly by up-regulating Bcl-2 expression and down-regulating Bax expression to inhibit liver cell apoptosis.

Roles and relation between C/EBPα and PARs in the activation of hepatic stellate cells

Protease activated receptors (PARs) are main components of the fibrotic cascade mediated by the trypsin and thrombin that amplifies liver inflammation and fibrosis. Gene transcription initiation induced by PARs plays an important role in the activation of hepatic stellate cells (HSCs). HSC activation can be inhibited by the expression of transcription factor CCAAT enhancer binding proteins α (C/EBPα). Further research of the relation between C/EBPα and PARs will contribute to the understanding of the pathogenesis of liver fibrosis and provide a theoretical basis for further exploration of anti-fibrotic strategies.

Cytokines, liver fibrosis, and principles of nutritional support in patients with liver fibrosis

The rapid development of molecular biology has provided new paths for and led to great breakthroughs in the treatment of liver fibrosis. Now the research of targets for anti-fibrosis therapy mainly focuses on hepatic stellate cells (HSC) and cytokines related to HSC activation. Researchers are getting more concerned about the features of nutritional metabolism in patients with liver fibrosis and their relationship with prognosis because of special roles the liver plays in nutritional metabolism. Reasonable principles of nutritional support can help ameliorate symptoms, reduce complications and facilitate recovery in patients with liver fibrosis.