Cytokine Regulation of Hepatic Stellate Cells in Liver Fibrosis

Cytokines constitute a major class of mediators responsible for “activation” of hepatic stellate cells (HSCs) in vitro and in vivo. They are largely divided into mitogenic (transforming growth factor-α, platelet-derived growth factor, interleukin-1, tumor necrosis factor-α, and insulin-like growth factor) and fibrogenic (transforming growth factor-β and interleukin-6) cytokines. In addition to their mitogenic (stimulation of cell proliferation) and fibrogenic (induction of matrix proteins) properties, they are also shown to confer in vitro unique cellular changes known to be the key features of HSC “activation,” including loss of vitamin A, stimulation of migration, enhanced cellular contractility, and matrix metalloproteinase and tissue inhibitor of metalloproteinase induction. Potential cellular sources of the cytokines consist of hepatic macrophages, endothelial cells, biliary epithelial cells, lymphocytes, platelets, hepatocytes, and activated HSCs. To better understand the mode of actions and the pathogenetic significance of cytokineskhemokines involved in “activation” of HSCs, the following four questions need to be addressed: (1) What other cytokines are expressed by HSCs to establish critical autocrine stimulation? (2) What are endogenous or exogenous priming factors for HSC stimulation? (3) What is the mechanism of activation for transforming growth factor-β, the pivotal fibrogenic cytokine? (4) How important are HSC-derived proinflammatory mediators in liver fibrosis? This review will discuss these questions, along with the current understanding of the role of cytokines in HSC activation.     

Roles of Kupffer Cells in Alcoholic Liver Disease

This article summarizes presentations at the 2004 International Society for Biomedical Research on Alcoholism held in Heidelberg/Mannheim, Germany. The organizers and chairpersons were Yoshiyuki Takei and Gavin E Arteel. The presentations were on 1) Kupffer cell–derived mediators involved in alcoholic liver disease: reactive oxygen and nitrogen species, by Gavin E. Arteel; 2) Kupffer cell–derived mediators in alcoholic liver disease: tumor necrosis factor-α, by Laura E. Nagy; 3) metformin prevents acute alcohol-induced fat accumulation in mouse liver, by Ina Bergheim; 4) gender difference in alcoholic liver disease, by Nobuyuki Enomoto; and 5) Kupffer cells as a therapeutic target of alcoholic liver disease, by Yoshiyuki Takei.     

氧化苦参碱对大鼠肝星状细胞增殖的影响

目的:研究氧化苦参碱对大鼠肝星状细胞增殖的影响,探讨其抗肝纤维化的机理。方法:用链霉蛋白酶和胶原酶原位灌流,Nycodenz密度梯度离心分离大鼠肝星状细胞,并以MTT比色法观察氧化苦参碱对肝星状细胞增殖的效应。结果:氧化苦参碱可影响肝星状细胞的增殖,氧化苦参碱浓度在0.5～16μg/ml时对肝星状细胞增殖有抑制作用(P<0.01)。结论:氧化苦参碱可抑制肝星状细胞增殖,有抗肝纤维化的作用。     

Acetaldehyde-Mediated Collagen Regulation in Hepatic Stellate Cells

Alcohol-induced liver cirrhosis is one of the major causes of death worldwide. Strong evidence has established that ethanol's first metabolite, acetaldehyde, is highly fibrogenic and enhances the deposition of many extracellular matrix components by hepatic stellate cells. This article reviews our current knowledge of the molecular mechanisms whereby acetaldehyde induces these activities, with particular emphasis on those related to the upregulation of type I collagen.     

肝纤维化大鼠药物血清对肝星状细胞增殖及活性型TGFβ1含量的影响

目的:观察肝纤维化大鼠药物血清对肝星状细胞(hepatic stellate cells,HSC)增殖及活性型TGFβ_1,含量的影响。方法:采用二甲基亚硝胺(dimethylnitrosamine,DMN)造成大鼠肝纤维化模型,经丹参酚酸B盐(Salvianolic-acid B,SA-B)与虫草多糖(Cordyceps sinensis polysaccharide,CP)联合治疗后采集大鼠血清,通过体外培养HSC,运用比色法、噻唑蓝(MTT)法及生物学检测法来观察药物血清对HSC增殖及活性型TGFβ_1含量的影响。结果:①细胞培养上清乳酸脱氢酶(LDH)活力测定显示,模型大鼠血清和药物血清无细胞毒性,正常大鼠血清组、模型大鼠血清组、药物血清组细胞培养上清LDH活力分别为(95±7.88)U/L,(72.2±11.42)U/L,(48.13±62.16)U/L,正常大鼠血清组与模型大鼠血清组比,差异有统计学意义(P<0.05)。②在对HSC增殖的影响方面,正常大鼠血清与模型大鼠血清之间的差异无统计学意义。与模型大鼠血清比较,药物血清能抑制HSC增殖(P<0.05)。③与模型大鼠血清比较,正常大鼠血清与药物血清均能减少活性型TGFβ_1含量,差异均有统计学意义(P<0.05)。结论:DMN肝纤维化大鼠血清与正常大鼠血清对HSC的影响不尽相同;SA-B合CP能抑制HSC增殖,并能减少活性型TGFβ_1含量。     

Oxysterols and Alcoholic Liver Disease

A new theory is presented implicating oxidative cholesterol metabolism and oxysterols as possible factors in the development of alcoholic liver disease. Our present studies have revealed the accumulation of cholesta-3,5-dien-7-one, 13.05 +/- 2.75 micrograms/g (n = 8), and cholesta-4,6-dien-3-one, 2.26 +/- 0.88 micrograms/g (n = 8) in fatty alcoholic liver, as compared with controls, 0.21 +/- 0.12 microgram/g (n = 7) and 0.3 +/- 0.33 microgram/g (n = 7), respectively. Acetaldehyde at 1 to 6 micromolar concentration in the blood and tissues of alcoholics cannot account for the extent of tissue damage, nor can it adequately explain liver steatosis characterized by accumulation of cholesterol and fatty acids and their esters in the liver of alcoholics known for their poor dietary habits. Oxysterols may be the primary cause for the development of alcoholic liver diseases and damage to accessory tissues. Significantly lower levels of 7-ketocholesterol in fatty liver, 6.8 +/- 3.5 micrograms/g (n = 8), as compared with control, 36.85 +/- 22.25 micrograms/g (n = 7), may be responsible for the increased cholesterol content of the alcoholic liver due to the inhibitory properties of this sterol on HMG-CoA reductase in cholesterol biosynthesis.     

Alcoholic Liver Disease and Apoptosis

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Carol A. Casey and Amin Nanji. The presentations were (1) Mechanisms of apoptosis in alcoholic liver disease, by Amin A. Nanji; (2) Impaired receptor-mediated endocytosis: Its role in alcoholic apoptosis, by Carol A. Casey; (3) Toxicity of ethanol in HepG2 cells that express CYP2E1, by Arthur I. Cederbaum; (4) Mitochondrial regulation of ethanol-induced hepatocyte apoptosis, by M. Adachi; and (5) Apoptosis in alcoholic hepatitis, by T. Takahashi.