Hepatic stellate cells in hepatitis C patients: relationship with liver iron deposits and severity of liver disease

BACKGROUND AND AIM: To determine the relationship between hepatic stellate cell (HSC) populations and severity of liver disease and liver iron deposits in patients with chronic hepatitis C virus (HCV). We also studied the relationship between iron cellular distribution and HSC population and the role of HFE mutations in the determination of iron deposits. METHODS: Forty-nine chronic HCV patients with varying degrees of liver damage and liver iron deposits were studied. A liver biopsy was scored for histology activity index (HAI), fibrosis and iron deposits. The number of HSC in the liver was evaluated by an immunohistochemical double-staining method to identify glial fibrillary acid protein (GFAP) and smooth muscle alpha-actin (alpha-SMA). RESULTS: The HSC population was significantly higher in HCV patients than in normal controls and was predominant in zones 1 and 3. Liver iron deposits were observed in 49% of patients and were mild/moderate in most cases. We found a significantly higher number of GFAP and alpha-SMA positive cells in patients with liver iron deposits compared with those without iron deposits, and a positive correlation between liver iron scores and number (%) of GFAP and alpha-SMA positive cells. We observed a significantly higher number of GFAP and alpha-SMA positive cells in moderate/severe hepatitis than in minimal/mild hepatitis, and a positive correlation between GFAP and alpha-SMA positive cells and HAI and fibrosis scores. CONCLUSIONS: Liver iron deposits in chronic HCV are common and are associated with activation of HSC. Thus, even mild iron deposits might stimulate HSC and contribute to liver damage.     

Intrahepatic expression of the hepatic stellate cell marker fibroblast activation protein correlates with the degree of fibrosis in hepatitis C virus infection

BACKGROUND: Activated hepatic stellate cells (HSCs), recognised by their alpha smooth muscle actin immunoreactivity, are primarily responsible for liver fibrosis. However, the presence of alpha smooth muscle actin positive HSCs is not always associated with the development of liver fibrosis. Recently, other markers of human HSCs including the gelatinase fibroblast activation protein (FAP) and glial fibrillary acidic protein have been identified. AIMS: We examined the relationship between the expression of these HSC markers and the severity of liver injury in patients with chronic hepatitis C virus infection. METHODS: Liver tissue from 27 patients was examined using immunohistochemistry. Linear correlation analysis was used to compare staining scores with the stage and grade of liver injury. RESULTS-CONCLUSIONS: FAP expression, seen at the tissue-remodelling interface, was strongly and significantly correlated with the severity of liver fibrosis. A weaker correlation was seen between glial fibrillary acidic protein expression and fibrosis stage. This contrasted with the absence of a relationship between alpha smooth muscle actin and the fibrotic score. A correlation was also observed between FAP expression and necroinflammatory score. In summary, FAP expression identifies a HSC subpopulation at the tissue-remodelling interface that is related to the severity of liver fibrosis.     

Vascular endothelial growth factor and receptor interaction is a prerequisite for murine hepatic fibrogenesis

BACKGROUND: It has been shown that expression of the potent angiogenic factor, vascular endothelial growth factor (VEGF), and its receptors, flt-1 (VEGFR-1) and KDR/Flk-1 (VEGFR-2), increased during the development of liver fibrosis. AIMS: To elucidate the in vivo role of interaction between VEGF and its receptors in liver fibrogenesis. METHODS: A model of CCl(4) induced hepatic fibrosis was used to assess the role of VEGFR-1 and VEGFR-2 by means of specific neutralising monoclonal antibodies (R-1mAb and R-2mAb, respectively). R-1mAb and R-2mAb were administered after two weeks of treatment with CCl(4), and indices of fibrosis were assessed at eight weeks. RESULTS: Hepatic VEGF mRNA expression significantly increased during the development of liver fibrosis. Both R-1mAb and R-2mAb treatments significantly attenuated the development of fibrosis associated with suppression of neovascularisation in the liver. Hepatic hydroxyproline and serum fibrosis markers were also suppressed. Furthermore, the number of alpha-smooth muscle actin positive cells and alpha1(I)-procollagen mRNA expression were significantly suppressed by R-1mAb and R-2mAb treatment. The inhibitory effect of R-2mAb was more potent than that of R-1mAb, and combination treatment with both mAbs almost completely attenuated fibrosis development. Our in vitro study showed that VEGF treatment significantly stimulated proliferation of both activated hepatic stellate cells (HSC) and sinusoidal endothelial cells (SEC). VEGF also significantly increased alpha1(I)-procollagen mRNA expression in activated HSC. CONCLUSIONS: These results suggest that the interaction of VEGF and its receptor, which reflected the combined effects of both on HSC and SEC, was a prerequisite for liver fibrosis development.     

Role of hepatic vitamin A and lipocyte distribution in experimental hepatic fibrosis

ABSTRACT— Lipocytes are the major site of hepatic vitamin A storage, and they have been demonstrated to lose their vitamin A content in the process of hepatic fibrosis. To investigate the relationship between hepatic vitamin A content and the degree of hepatic fibrosis, we measured levels of retinyl palmitate and retinol in the CCl₄-induced fibrotic liver using high-performance liquid chromatography. We estimated hepatic collagen content using a spectrophotometric analysis with sirius red, and also by measuring hydroxyproline levels. Lipocytes were detected by an immunoperoxidase method with anti-desmin antibody, and were counted morphometrically through a Texture Analyzing System. A significant negative correlation was observed between the level of retinyl palmitate and collagen content (r = –0.64) as well as the hydroxyproline level (r = –0.69) in the CCl₄-induced fibrotic liver. In the process of fibrosis, hepatic retinol levels were elevated in association with a decrease in retinyl palmitate. In particular in the early stage of fibrosis, lipocytes increased remarkably in number in fibrotic areas in spite of a decrease in total hepatic vitamin A. The present study suggests that an increase in hepatic retinol as well as a decrease in retinyl palmitate may facilitate the process of hepatic fibrosis produced by lipocytes.     

大鼠纤维化肝组织中PTEN的动态表达及其与肝星状细胞增殖和活化的关系

目的 探讨第10号染色体缺失的磷酸酶张力蛋白同源物基因(PTEN)在大鼠纤维化肝组织中的动态表达及其对在体肝星状细胞(HSC)活化、增殖的影响. 方法 采用胆总管结扎法建立大鼠肝纤维化模型;应用免疫组织化学染色、Western blot和实时荧光定量PCR技术测定大鼠肝组织中PTEN的表达;应用免疫荧光双标记共聚焦激光扫描显微术测定大鼠肝组织中活化HSC的PTEN表达;采用免疫组织化学染色检测大鼠肝组织中α-平滑肌肌动蛋白的表达.结果 免疫组织化学染色显示正常大鼠肝组织中PTEN有广泛表达,主要表达于细胞质,随着肝纤维化的发展,PTEN表达逐渐减少(P<0.01),而α-平滑肌肌动蛋白阳性细胞明显增多(P<0.01);造模1、2、3周及4周不同时间大鼠纤维化肝组织中PTEN的mRNA(分别为假手术组的0.66、0.53、0.44和0.37)及蛋白质表达(吸光度比值分别为1.20±0.13,1.07±0.16,0.88±0.08,0.73±0.07)均低于假手术组(P<0.01),并随着肝纤维化的进展逐渐降低(P<0.01);免疫荧光双标记共聚焦激光扫描显微术显示PTEN在活化HSC广泛表达,主要表达于细胞质,随着肝纤维化的进展,表达PTEN的活化HSC占总的活化HSC的比例逐渐减少(P<0.01). 结论 大鼠纤维化肝组织中PTEN的mRNA及蛋白质表达均下调;在体HSC的PTEN表达亦降低;肝组织中PTEN的动态表达与HSC的活化、增殖呈显著负相关.     

Hepatic hydrothorax associated with vitamin a toxicity

We report the first case of an adult presenting with respiratory symptoms caused by hepatic hydrothorax secondary to vitamin A intoxication. The patient was a 52-year-old woman who presented to the hospital with progressive dyspnea. Evaluation demonstrated mild elevation of her liver function tests, ascites, and a right pleural effusion. The patient consumed a variety of vitamins, including vitamin A. Her estimated vitamin A intake was at least 162,300,000 international units (IU) during 18 years. She dramatically escalated her dose the year before admission for a total acute dose of 98,550,000 IU, with a daily intake of 270,000 IU. The recommended daily allowance is 4,000 IU. A transjugular liver biopsy revealed histopathologic changes consistent with vitamin A toxicity: hypertrophy and hyperplasia of hepatic stellate cells, focal pericellular fibrosis, mild perivenular fibrosis, and minimal, predominantly microvesicular steatosis. Despite the absence of cirrhosis, pressure readings demonstrated portal hypertension. During her hospitalization, the patient's symptoms and biochemical profile improved. As the large and generally unregulated United States dietary supplement industry continues to grow, it is increasingly likely that individuals will present with the signs and symptoms of vitamin excess rather than vitamin deficiency. Physicians need to remain alert to the varied presentations and toxic manifestations of excessive vitamin use.     

High,but not low,dietary retinoids aggravate manifestation of rat liver fibrosis

BACKGROUND: Although there is strong implication that retinoids regulate Ito cell proliferation and collagen synthesis, results from in vivo studies on the relationship between vitamin A and liver fibrosis are conflicting. The present study focuses on the role of vitamin A in carbon tetrachloride (CCl4)-induced fibrosis by chronic feeding of rats with either a vitamin A-supplemented or -depleted diet. METHODS AND RESULTS: In animals with high dietary hepatic retinoid levels, liver fibrosis was more pronounced and was associated with an increased CCl4-toxicity resulting in high mortality (73%). Enhanced liver fibrosis was confirmed by in vivo fluorescence microscopic determination of both collagen deposits (7.4 +/- 1.1 vs 3.9 +/- 0.3% in high vitamin A diet-fed and standard diet-fed fibrotic animals, respectively; P < 0.05) and rarefication of sinusoids (1.5 +/- 0.2 vs 2.4 +/- 0.2 sinusoids/200 microm in high vitamin A diet-fed and standard diet-fed fibrotic animals, respectively; P < 0.05). It was further associated with decreased bile flow and increased parenchymal cell damage. CCl4 reduced hepatic retinoid levels in high vitamin A diet-fed animals, but restored hepatic retinoid levels in animals fed with a vitamin A-deficient diet, implying major interference of vitamin A metabolism with hepatotoxic agents such as CCl4. Low vitamin A feeding did not modulate liver fibrogenesis and caused no mortality. CONCLUSIONS: These results show that the vitamin A status of the liver plays an important role in liver fibrogenesis. While dietary vitamin A shortage does not promote liver fibrogenesis, high levels of vitamin A have the potential to increase systemic and hepatic toxicity of CCl4. Thus, the narrow therapeutic window for nutritional vitamin A substitution must take into account that liver fibrotic patients may display enhanced susceptibility to the adverse effects of vitamin A.     

Vitamin A toxicity in a physical culturist patient: a case report and review of the literature

Excessive intake of vitamin A may produce acute or chronic toxicity. Vitamin A can be consumed in foods, fortified products and supplements. We present a case of a young physical culturist man who was referred to our Unit because of chronic liver disease of unknown origin. The patient had a history of increased vitamin A intake from natural source with the addition of high dose of vitamin A supplements with the purpose of improving his muscular development. Our patient showed chronic liver disease with severe fibrosis, signs of portal hypertension and marked hyperplasia of Ito cells. In conclusion, chronic vitamin A toxicity may produce severe liver damage and should be recognized in the differential diagnosis of chronic liver diseases.     

细胞间粘附分子-1表达与肝纤维化关系的研究

目的:探讨细胞间粘附分子-1(ICAM-1)表达与肝纤维化的关系。方法:建立四氯化碳大鼠实验性肝纤维化模型。用链酶蛋白和胶原酶原位灌流,Nycodenz密度梯度离心分离正常大鼠HSC,并进行体外培养,应用免疫组织化学方法分别观察静息或活化状态下的HSC及造模肝组织中ICAM-1的表达。结果:肝纤维化模型组织中,ICAM-1表达明显增加,ICAM-1阳性细胞多分布在汇管区周围,肝小叶内炎性细胞浸润区和坏死灶内,其阳性强度及分布与肝脏炎症、肝纤维化程度和分布相一致;静息的HSC不表达ICAM-1,而活化的HSC表达ICAM-I,且随着培养时间的延长ICAM-1表达量逐渐增加。结论:动物体内实验和体外细胞培养表明,ICAM-1表达与HSC活化、肝脏炎性损伤及肝纤维化的发生有关。     

ICAM．1表达与肝纤维化关系的研究

探讨细胞间粘附分子-1(ICAM-1)表达与肝纤维化的关系。方法：建立四氯化碳大鼠实验性肝纤维化模型。用链酶蛋白酶和胶原酶原位灌流,Nycodenz密度梯度离心分离正常大鼠肝星状细胞(HSC),并进行体外培养,应用免疫组织化学方法分别观察静息或活化状态下HSC及造模肝组织中ICAM-1的表达。结果：肝纤维化模型组织中ICAM—1表达明显增加,ICAM-1M性细胞多分布在汇昔区周围、肝小叶内炎性细胞浸润区和坏死灶内,其阳性强度及分布与肝脏炎症、肝纤维化程度和分布相一致;静息的HSc不表达ICAM-1,而活化的HSC表达ICAM-1,且随着培养时间的延长,ICAM-1表达量逐渐增加。结论：动物体内实验和体外细胞培养表明,ICAM-1表达与HSC活化、肝脏炎性损伤及肝纤维化的发生有关。     

Liver in obesity.

We report on clinical, nutritional, and hepatic histological findings in 50 non-selected obese subjects (mean overweight +74%; range +21-138%). The pathogenesis of the liver damage was assessed with the help of multidimensional analysis of a number of clinical variables. According to the severity of the hepatic lesions, the patients have been ranged in five groups: O (normal liver) 10%; I (fatty liver) 48%; II (fatty hepatitis) 26%; III (fatty fibrosis) 8%; IV (fatty cirrhosis) 8%. The more severe changes (groups III and IV) were constantly associated with excessive alcohol intake. The multidimensional analysis was unable to find a relationship between obesity and the development of fibrosis and cirrhosis whereas it showed that: (a) there was a highly significant correlation between the daily ethanol intake and the degree of overweight, (b) severe fatty metamorphosis was significantly associated with the degree of overweight, the existence of diabetes mellitus, and the amount of alcohol and fat intake, (c) nutritional factors, in particular deficient protein intake, have only an accessory effect in the development of mild inflammation and fibrosis, (d) the consumption of potentially hepatotoxic drugs, very high in the obese (about five drugs per day) could have a role in the development of cirrhosis. In conclusion in our study, there was no evidence that obesity per se could result in severe liver damage.     

体外四氯化碳损伤肝细胞对肝星状细胞活化的影响及其丹酚酸A的干预效果

目的 体外观察肝细胞四氯化碳过氧化损伤后肝星状细胞（ＨＳＣ）活化的影响,并观察丹参水溶性成分丹酚酸Ａ的干预效果,以研究脂质过氧化损伤与肝纤维化的关系和丹酚酸Ａ的作用机理。方法 肝细胞分离后分组,分别添加不同浓度的丹酚酸Ａ以及对照药维生素Ｅ,同时以四氯化碳熏蒸２４ｈ并测定各组细胞上清液ＡＬＴ、ＡＳＴ活性后,换液培养２４ｈ并测定ＭＤＡ含量,再以此上清液作为“肝细胞条件培养液”作用于ＨＳＣ４８ｈ,观察Ｈ     

肝星状细胞凋亡机制研究进展

肝纤维化是肝脏对慢性损伤的一种修复反应,其特征性变化为细胞外基质过度沉积。肝星状细胞（HSC）活化是肝纤维化形成的中心环节,诱导活化的HSC凋亡有望逆转肝纤维化。本文从死亡受体途径、线粒体途径、内质网途径、神经生长因子途径、过氧化物酶体增生物激活受体-γ途径、核因子-κB途径对HSC的凋亡机制作一综述。     

A novel MCP-1 gene polymorphism is associated with hepatic MCP-1 expression and severity of HCV-related liver disease

BACKGROUND AND AIMS: Factors influencing the progression of chronic hepatitis C virus (HCV) infection are poorly understood. Monocyte chemotactic protein-1 (MCP-1) is a potent chemokine, and its hepatic expression is up-regulated during chronic HCV infection mainly in activated hepatic stellate cells (HSC). In this study, we investigated the correlation of the functional -2518 MCP-1 promoter polymorphism with hepatic MCP-1 expression and the disease outcome in patients with HCV. METHODS: MCP-1 genotyping was performed in 206 patients and 139 healthy controls. Hepatic MCP-1 messenger RNA (mRNA) expression was quantified by real-time PCR in 58 HCV patients. Cytokine-induced MCP-1 secretion of activated human HSC (n = 13) was determined by enzyme-linked immunosorbent assay (ELISA). Mobility-shift assays were performed using probes corresponding to the MCP-1 promoter sequence (-2511 to -2528) with or without the A to G mutation at -2518. RESULTS: Frequency of MCP-1 genotypes did not differ between HCV patients and controls. However, carriers of the G allele were significantly more frequent in HCV patients with more advanced fibrosis and severe inflammation. In accordance, hepatic MCP-1 mRNA levels were significantly higher in patients with more advanced fibrosis and in patients carrying the G allele. Furthermore, cytokine-induced MCP-1 secretion of HSC isolated from carriers of the G allele was significantly higher, and there was binding activity in nuclear extracts from activated HSC specifically to the G allele, providing a potential mechanism for the differences seen. CONCLUSIONS: Inheritance of the -2518 MCP-1 G allele, which appears to affect hepatic MCP-1 expression, may predispose HCV patients to more severe hepatic inflammation and fibrosis.     

姜黄素预防肝纤维化作用与肝星状细胞的关系

目的观察姜黄素预防大鼠肝纤维化作用及活化肝星状细胞(HSC)的数目、分布、凋亡等变化,并探讨两者间的关系。方法以四氯化碳制作大鼠肝纤维化模型,同时按每100 g体重分别给予20、10、5 mg姜黄素灌胃处理,设立正常对照组、肝纤维化组和阳性对照组;8周后处死大鼠,留取肝左叶行HE、Masson染色,参照肝纤维化半定量计分系统进行肝纤维化程度评分,免疫组织化学方法检测α-平滑肌肌动蛋白以了解活化HSC的数量变化, TUNEL与肌源性特异性标志物结合蛋白(Desmin)免疫组织化学双染法检测HSC凋亡。结果姜黄素可明显改善四氯化碳所致大鼠肝纤维化的病理学改变;α-平滑肌肌动蛋白在肝纤维化时表达明显增多,姜黄素使活化HSC数量减少, }[SC凋亡增加,与对照组比较差异具有统计学意义(P<0．05),且具有量效关系。结论姜黄素可抑制HSC活化、增殖,诱导HSC凋亡,可能为预防肝纤维化的作用机制之一。     

Role of angiotensin‐1 receptor blockade in cirrhotic liver resection

Background: The regeneration capacity of cirrhotic livers might be affected by angiotensin‐1 (AT1) receptors located on hepatic stellate cells (HSC). The effect of AT1 receptor blockade on microcirculation, fibrosis and liver regeneration was investigated. Materials and methods: In 112 Lewis rats, cirrhosis was induced by repetitive intraperitoneal injections of CCl₄. Six hours, 3, 7 and 14 days after partial hepatectomy or sham operation, rats were sacrificed for analysis. Animals were treated with either vehicle or 5 mg/kg body weight losartan pre‐operatively and once daily after surgery by gavage. Microcirculation and portal vein flow were investigated at 6 h. The degree of cirrhosis was assessed by Azan Heidenhein staining, activation of HSC by desmin staining, apoptosis by ssDNA detection and liver regeneration by Ki‐67 staining. Changes in expression of various genes important for liver regeneration and fibrosis were analysed at 6 h and 3 days. Haemodynamic parameters and liver enzymes were monitored. Results: Losartan treatment increased sinusoidal diameter, sinusoidal blood flow and portal vein flow after partial hepatectomy (P<0.05), but not after sham operation. AT1 receptor blockade resulted in increased apoptosis early after resection. HSC activation was reduced and after 7 days, a significantly lower degree of cirrhosis in resected animals was observed. Losartan increased the proliferation of hepatocytes at late time‐points and of non‐parenchymal cells early after partial hepatectomy (P<0.05). Tumour necrosis factor (TNF)‐α was significantly upregulated at 6 h and stem cell growth factor (SCF) was downregulated at 3 days (P<0.05). Conclusion: Losartan increased hepatic blood flow, reduced HSC activation and liver fibrosis, but interfered with hepatocyte proliferation after partial hepatectomy in cirrhotic livers.     

Vitamin K1 intake and coronary calcification

OBJECTIVES: The activity of matrix Gla-protein (MGP), a potent inhibitor of vascular calcification, is dependent on carboxylation using vitamin K as a co-factor. In animals, low intake of total vitamin K has been shown to accelerate vascular calcification via the MGP mechanism. This has led to the hypothesis that low levels of dietary vitamin K intake may be a risk factor for accelerated vascular calcification in humans due to decreased MGP activity. Additionally, some authors have suggested that current recommended daily intake values for vitamin K might be insufficient to fully inhibit vascular calcification via the MGP mechanism. The aim of this study was to examine the relationship between dietary vitamin K1 (the most prevalent dietary form of vitamin K) intake and premature coronary artery calcification (CAC) in an asymptomatic screening population. METHODS: We conducted a prospective study of 807 consecutive active-duty US Army personnel, 39-45 years of age, without known coronary heart disease. Vitamin K1 intake was measured with the Block Dietary Questionnaire and CAC was identified using electron-beam computed tomography (EBCT). RESULTS: We found no significant correlation between CAC score and vitamin K1 intake (r = 0.132, P = 0.106). Multivariate analysis with adjustment for cardiac risk factors showed no association between dietary vitamin K1 intake and CAC. CONCLUSIONS: Dietary vitamin K1 (phylloquinone) intake appears to be unrelated to premature coronary calcification in a screening population. Further investigation into the relationship of vascular calcification and other forms of vitamin K1 (menaquinones) is indicated.