Ginkgo biloba extract alleviates liver fibrosis induced by CCl in rats.

AIMS: To investigate the protective effect of Ginkgo biloba extract (GbE) on liver fibrosis induced by carbon tetrachloride (CCl4) in rats and expressions of transforming growth factor beta1 (TGF-beta1) and collagen I during this period. METHODS: The effect of GbE on liver fibrogenesis was detected by hematoxylin and eosin staining (H&E staining), Masson's trichrome staining, and electron microscope study. Blood samples were collected for measurement of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin. Malondialdehyde (MDA) in liver tissue was detected by the thiobarbituric acid (TBA) method. Immunohistochemistry assay and RT-PCR were used to examine the protein expressions and mRNA levels of TGF-beta1 and collagen I, respectively. RESULTS: H&E, Masson's trichrome stainings and electron microscope study showed liver fibrosis in rats was greatly alleviated when treated with GbE. Additionally, there was a remarkable improvement of serum ALT, AST, albumin and MDA in the GbE-treated group. Immunohistochemistry and RT-PCR results showed GbE intervention significantly inhibited TGF-beta1 and collagen I expressions in rat liver. No side effects of GbE were found during these experiments. But GbE could not reverse the pathological changes of liver fibrosis completely when compared with normal control. CONCLUSION: GbE can partially protect rat liver from the fibrogenesis induced by CCl4. The mechanism may lie in its effect of inhibiting oxidative stress caused by liver injury and expressions of signal molecules such as TGF-beta1. GbE may thus be of potential help as a medicament or food additive for alleviation of liver fibrogenesis.     

Inhibitory effect of human interferon-beta-1a on activated rat and human hepatic stellate cells

Background and Aims: Hepatic stellate cells (HSC) are the primary cell type mediating hepatic fibrosis. Although known for its antiviral effects, the inhibitory effects of interferon‐beta (IFN‐β) on HSC treatment have not yet been established. Methods: Both human and rat activated HSC cell lines were incubated with increasing concentrations of recombinant human IFN‐β1a (rhIFN‐β1a) for 24, 48 or 72 h. The effects of rhIFN‐β1a on α‐smooth muscle actin (α‐SMA), collagen types I and III, transforming growth factor‐β1 (TGF‐β1), platelet‐derived growth factor‐BB (PDGF‐BB), and mothers against decapentaplegic homolog (Smad4, Smad7) expression in HSC were examined using Western blotting and immunocytochemistry. Proliferation of HSC was evaluated via bromodeoxyuridine assay. Results: rhIFN‐β1a treatment had a dose‐dependent, inhibitory effect on α‐SMA and collagen type I protein expression. In addition, rhIFN‐β1a decreased the expression of collagen type III, TGF‐β1, PDGF‐BB and Smad4 protein expression in HSC compared with untreated cells. We also observed increased Smad7 protein expression and decreased proliferation in rhIFN‐β1a‐treated HSC. Conclusions: Our data suggest that rhIFN‐β1a treatment decreased α‐SMA and collagen expression and inhibited the activation of HSC through the inhibition of the TGF‐β and PDGF pathways.     

龙血素B对肝星状细胞增殖及细胞外基质分泌的影响

目的观察龙血素B对大鼠肝星状细胞(HSC)增殖及细胞外基质分泌的影响。方法用不同浓度的龙血素B处理大鼠HSC;MTT法计算药物的抑制率;放射免疫法测定细胞上清中透明质酸(HA)、层粘连蛋白(LN)和Ⅳ型胶原(Ⅳ-C)。结果随药物浓度的升高,龙血素B对HSC-T6增殖的抑制作用逐渐增强,有明显的量效关系。细胞上清中HA、LN和Ⅳ-C的含量与对照组相比降低,其中龙血素B浓度为0.300μg/μL时降低最明显。结论龙血素B可抑制HSC-T6增殖,并不同程度抑制HA、LN和Ⅳ-C的分泌。     

姜黄素对肝星状细胞增殖及分泌细胞外基质的影响

观察姜黄素对大鼠肝星状细胞 (HSC)增殖及分泌细胞外基质的影响。用不同浓度的姜黄素处理大鼠肝星状细胞 ;以MTT比色法测定细胞的增殖 ;放射免疫法测定透明质酸和层粘连蛋白 ;酶联免疫吸附法 (ELISA)测定Ⅰ型胶原的水平。姜黄素可剂量依赖性地抑制HSC增殖 ,不同程度抑制Ⅰ型胶原、透明质酸和层粘连蛋白分泌。姜黄素可显著抑制HSC的增殖及分泌细胞外基质。     

Melatonin prevents H2O2-induced activation of rat hepatic stellate cells

Considerable evidence shows therapeutic effects of melatonin on liver injury and the involvement of hepatic stellate cells (HSCs) in vivo. In the present studies, we investigate the protective effect of melatonin on H2O2-induced activation of HSCs in vitro. Compared with that in control HSCs, synthesis of collagen type I was increased in H2O2-treated cells. Melatonin pretreatment significantly inhibited the above effects of H2O2 in HSCs. CCAAT/enhancer-binding protein alpha (C/EBP-alpha), which could partially reverse the phenotype of activated HSCs, augmented in HSCs pretreated with melatonin. Moreover, secretion of the most important fibrotic cytokine transforming growth factor beta 1 (TGF-beta1) diminished in melatonin-pretreated HSCs. These results suggest that melatonin prevents H2O2-induced activation of HSCs and that the mechanism involves, at least in part, differential regulation of TGF-beta1 and C/EBP-alpha gene expression.     

Cell survival,activation and apoptosis of hepatic stellate cells: modulation by extracellular matrix proteins

Aim: Cytokines and growth factors released by various hepatic cells exert both paracrine and autocrine effects on hepatic stellate cell (HSC) activation during liver injury. The aim of the present study was to examine whether the surrounding extracellular matrix (ECM) influences the activation, transdifferentiation and survival of HSCs. Methods: An in vitro model system of isolated HSCs maintained in culture on different matrix protein substrata was employed. Results: The rate of loss of HSC‐specific retinol uptake activity and gain of myofibroblast‐like activity such as ³⁵[S] proteoglycan synthesis varied in cells maintained on different matrix proteins and was in the order collagen I > collagen IV ≥ laminin. ³[H]‐thymidine incorporation by HSCs maintained on different matrix proteins varied and was in the order collagen I > collagen IV > laminin. MTT assay revealed that the growth inhibition in response to curcumin was significantly low in cells maintained on collagen I. Apoptotic marker activities such as DNA fragmentation, 4′,6′‐diamidino‐2‐phenylindole dihydrochloride (DAPI) staining, annexin staining and caspase‐3 activities showed that cells maintained on collagen I showed minimal apoptosis than those maintained on collagen IV, laminin and polylysine, showing the influence of ECM on HSC apoptosis. Experiments using blocking antibodies showed that the collagen I effect was mediated through α₂β₁ integrin. Conclusions: These results indicate that ECM influences activation, transdifferentiation and survival of HSCs, and suggest that apart from diffusible factors, the surrounding ECM also influences HSC behavior critical in both the progression of the fibrosis and the restitution of the liver during recovery after hepatic injury.     

Effects of rhubarb on migration of rat hepatic stellate cells

Background and Aims:  In chronic liver injury, hepatic stellate cells (HSCs) acquire an activated phenotype, migrate to the injured region in response to chemotactic factors, and produce extracellular matrix proteins including collagen. In this study, we investigated the effects of rhubarb ( Rheum palmatum L.) on transforming growth factor (TGF)-β1-induced expressions of α-smooth-muscle actin (SMA) and collagen, and the migration of HSCs.
Methods:  HSC-T6, a cell line of rat HSCs, was used in the in vitro experiments. An enzyme-linked immunosorbent assay and Sircol red assay were used to detect the expressions of α-SMA and collagen, respectively. HSC-T6 migration was assayed with a transwell apparatus. Phosphorylations of Smad2/3 and mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK) 1/2, p38, and c-jun N-terminal kinase (JNK), were analyzed with Western blotting. Matrix metalloproteinase (MMP)-2 activity was examined by gelatin zymography.
Results:  The results revealed that a rhubarb extract concentration-dependently attenuated TGF-β1-induced α-SMA and collagen expressions and migration of HSCs. The inhibitory effect of rhubarb was associated with (i) down-regulation of the phosphorylation of Smad2/3 and JNK, and (ii) attenuation of MMP-2 activity. Within the working concentrations used, the rhubarb extract did not affect cell viability of HSCs.
Conclusion:  The results suggest that rhubarb attenuated TGF-β1-mediated migration of HSCs possibly by interfering with Smad2/3 phosphorylation, the MAPK pathway, and MMP-2 activity.     

Molecular mechanisms in the reversible regulation of morphology,proliferation and collagen metabolism in hepatic stellate cells by the three-dimensional structure of the extracellular matrix

Hepatic stellate cells (vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells, Ito cells) exist in the perisinusoidal space of the hepatic lobule and store 80% of the body's retinoids as retinyl palmitate in lipid droplets in the cytoplasm. Under physiological conditions, these cells play pivotal roles in the regulation of retinoid homeostasis; they express specific receptors for retinol-binding protein (RBP), a binding protein specific for retinol, on their cell surface, and take up the complex of retinol and RBP by receptor-mediated endocytosis. However, in pathological conditions such as liver fibrosis, these cells lose retinoids and synthesize a large amount of extracellular matrix (ECM) components including collagen, proteoglycan and adhesive glycoproteins. The morphology of these cells also changes from star-shaped stellate cells to that of fibroblasts or myofibroblasts. The three-dimensional structure of ECM components was found to regulate reversibly the morphology, proliferation and functions of hepatic stellate cells. Molecular mechanisms in the reversible regulation of stellate cells by ECM imply cell surface integrin binding to ECM components followed by signal transduction processes and then cytoskeleton assembly.     

高糖对大鼠胰星状细胞增殖和细胞外基质合成的影响

目的 探讨高糖刺激对大鼠胰星状细胞(pancreatic stellate cell,PSC)增殖和细胞外基质(extracellular matrix,ECM)合成的影响。方法 分离培养大鼠PSC,取传第3～5代细胞,分别用正常葡萄糖(5.6mmol/L葡萄糖)(正常对照)、高葡萄糖(25mmol/L葡萄糖)(高糖组)和甘露醇(5.6mmol/L葡萄糖+19.4mmol/L甘露醇)(等渗对照组)处理5天后,用MTT法、~3H-Thymidine掺入和~3H-Proline掺入法分别检测细胞增殖、DNA合成和总胶原合成,同时用放免法检测细胞培养上清中Ⅲ型前胶原氨基末端多肽(amino-terminal propeptide of type Ⅲ procollagen,P Ⅲ NP)和透明质酸(hyaluronic acid,HA)含量。结果 与等渗对照组比较,高糖组PSC增殖、DNA合成、总胶原合成和细胞上清HA含量均显著增加(P<0.05),但细胞上清P Ⅲ NP含量无显著性差异(P>0.05)。结论 高糖可刺激PSC增殖与胶原合成,参与PSC活化。体内高糖血症可能是PSC活化的机制之一。     

Proanthocyanidin derived from the leaves of Vaccinium virgatum suppresses platelet‐derived growth factor‐induced proliferation of the human hepatic stellate cell line LI90

Aim: Hepatic stellate cell (HSC) proliferation plays a pivotal role in liver fibrogenesis, and agents that suppress HSC activation, including platelet‐derived growth factor (PDGF)‐induced HSC proliferation, are good candidates for antifibrogenic therapies. In this report, we use the LI90 HSC line to elucidate the antifibrogenic effects of proanthocyanidin derived from the leaves of Vaccinium virgatum. Methods: Proanthocyanidin (PAC) was extracted from the leaves of blueberry V. virgatum (BB‐PAC), grape seeds (GS‐PAC) and Croton lechleri (CL‐PAC). These extracts were examined for their effects on PDGF‐BB‐induced LI90 cell proliferation and DNA synthesis. Extracellular signal‐regulated kinase (ERK) and Akt phosphorylation and PDGF receptor‐β (PDGFR‐β) expression were evaluated by western blot analysis. Results: BB‐PAC potently suppressed PDGF‐BB‐induced proliferation and DNA synthesis of LI90 cells. BB‐PAC also suppressed PDGF‐BB‐induced DNA synthesis in primary cultured rat HSC. Moreover, GS‐PAC and CL‐PAC suppressed PDGF‐BB‐induced DNA synthesis in LI90 cells. In contrast, the monomeric PAC catechin and epicatechin and dimeric PAC procyanidin B2 only slightly suppressed PDGF‐BB‐induced DNA synthesis. Western blot analysis showed that BB‐PAC completely or partially inhibited PDGF‐BB‐induced ERK and Akt phosphorylation, respectively. In addition, BB‐PAC partially inhibited the PDGF‐BB‐induced degradation of PDGFR‐β. Conclusion: Our results suggest that BB‐PAC suppresses activated HSC by inhibiting the PDGF signaling pathway. In addition, these results provide novel findings that may facilitate the development of antifibrogenic agents.     

软肝化坚颗粒调节肝星状细胞分泌胶原及相关细胞因子的研究

目的:观察软肝化坚颗粒药物血清对肝星状细胞(HSC)分泌Ⅰ、Ⅲ型胶原及肝纤维化相关细胞因子的影响.方法:通过灌胃制备小鼠软肝化坚颗粒及秋水仙碱药物血清.将HSC-T6细胞分为3组,分别加入含10％软肝化坚颗粒血清、10％秋水仙碱血清和10％正常小鼠血清的培养基,培养24小时后,收集培养上清.采用ELISA法检测Ⅰ型胶原、转化生长因子β1 (TGF-β1)、瘦素(LP)及血小板衍生生长因子(PDGF)的含量;采用放射免疫法检测Ⅲ型胶原含量.结果:与正常血清对照组相比,秋水仙碱血清组和软肝化坚颗粒血清组培养上清中Ⅰ型胶原含量均显著降低,P值均为0.000;Ⅲ型胶原的含量也均显著降低,P值分别为0.005和0.001.与正常血清对照组相比,秋水仙碱血清组培养上清中TGF-β1、LP和PDGF的含量均明显降低,P值均为0.000;软肝化坚血清组也均显著降低,P值均为0.000;软肝化坚颗粒血清组与秋水仙碱血清组相比,培养上清中TGF-β1、LP的含量均明显降低,P值分别为0.006和0.043.结论:软肝化坚颗粒可抑制活化的HSC产生TGF-β1、PDGF及LP等细胞因子,从而对HSC分泌胶原产生抑制作用.     

Contribution of hepatic stellate cells and matrix metalloproteinase 9 in acute liver failure

Background/Aims: Fulminant hepatitis or acute liver failure (ALF), initiated by viral infection or hepatic toxin, is a devastating medical complication without effective therapeutic treatment. In this study, we addressed the potential roles of hepatic stellate cells (HSCs) and their produced matrix metalloproteinases (MMPs) in development of ALF. Methods: Mice were given lipopolysaccharide (LPS) and beta‐galactosamine (GA) or carbon tetrachloride to create ALF and establish the association of IL‐1, MMP‐9, and caspase‐3 in acute liver failure. Results: In response to the hepatic toxin, IL‐1 and MMP‐9 were promptly induced within 1 hour, followed by caspase‐3 activation at 2 hours, and dehiscence of sinusoids at 4 hours, and consequent lethality. In contrast, MMP‐9 knockout mice were resistant to lethality and absent of caspase‐3 activation, demonstrating an MMP‐9‐dependent activation of caspase in vivo. Further, IL‐1‐receptor knockout mice were resistant to lethality in MMP‐9 dependent manner, indicating a causative relationship. Although many hepatic cells are capable to produce MMP‐9 in vitro, HSCs were demonstrated here as the major hepatic cells to express MMP‐9 in liver injury. To recapitulate the sinusoidal microenvironment we cultured primary HSCs in 3‐dimensional ECM. In response to IL‐1, massive MMP‐9 was produced by the 3D culture concomitantly with degradation of type‐IV collagen. Conclusions: Based on these evidences, we propose a novel model to highlight the initiation of acute liver failure: IL‐1‐induced MMPs by HSCs within the space of Disse and thereafter ECM degradation may provoke the collapse of sinusoids, leading parenchymal cell death and loss of liver functions.