Desmoglein 2 mutant mice develop cardiac fibrosis and dilation

Desmosomes are cell–cell adhesion sites and part of the intercalated discs, which couple adjacent cardiomyocytes. The connection is formed by the extracellular domains of desmosomal cadherins that are also linked to the cytoskeleton on the cytoplasmic side. To examine the contribution of the desmosomal cadherin desmoglein 2 to cardiomyocyte adhesion and cardiac function, mutant mice were prepared lacking a part of the extracellular adhesive domain of desmoglein 2. Most live born mutant mice presented normal overall cardiac morphology at 2 weeks. Some animals, however, displayed extensive fibrotic lesions. Later on, mutants developed ventricular dilation leading to cardiac insufficiency and eventually premature death. Upon histological examination, cardiomyocyte death by calcifying necrosis and replacement by fibrous tissue were observed. Fibrotic lesions were highly proliferative in 2-week-old mutants, whereas the fibrotic lesions of older mutants showed little proliferation indicating the completion of local muscle replacement by scar tissue. Disease progression correlated with increased mRNA expression of c-myc, ANF, BNF, CTGF and GDF15, which are markers for cardiac stress, remodeling and heart failure. Taken together, the desmoglein 2-mutant mice display features of dilative cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy, an inherited human heart disease with pronounced fibrosis and ventricular arrhythmias that has been linked to mutations in desmosomal proteins including desmoglein 2.     

Glycine N-methyltransferase-/- mice develop chronic hepatitis and glycogen storage disease in the liver

Glycine N-methyltransferase (GNMT) affects genetic stability by regulating DNA methylation and interacting with environmental carcinogens. To establish a Gnmt knockout mouse model, 2 lambda phage clones containing a mouse Gnmt genome were isolated. At 11 weeks of age, the Gnmt-/- mice had hepatomegaly, hypermethioninemia, and significantly higher levels of both serum alanine aminotransferase and hepatic S-adenosylmethionine. Such phenotypes mimic patients with congenital GNMT deficiencies. A real-time polymerase chain reaction analysis of 10 genes in the one-carbon metabolism pathway revealed that 5,10-methylenetetrahydrofolate reductase, S-adenosylhomocysteine hydrolase (Ahcy), and formiminotransferase cyclodeaminase (Ftcd) were significantly down-regulated in Gnmt-/- mice. This report demonstrates that GNMT regulates the expression of both Ftcd and Ahcy genes. Results from pathological examinations indicated that 57.1% (8 of 14) of the Gnmt-/- mice had glycogen storage disease (GSD) in their livers. Focal necrosis was observed in male Gnmt-/- livers, whereas degenerative changes were found in the intermediate zones of female Gnmt-/- livers. In addition, hypoglycemia, increased serum cholesterol, and significantly lower numbers of white blood cells, neutrophils, and monocytes were observed in the Gnmt-/- mice. A real-time polymerase chain reaction analysis of genes involved in the gluconeogenesis pathways revealed that the following genes were significantly down-regulated in Gnmt-/- mice: fructose 1,6-bisphosphatase, phosphoenolpyruvate carboxykinase, and glucose-6-phosphate transporter. CONCLUSION: Because Gnmt-/- mice phenotypes mimic those of patients with GNMT deficiencies and share several characteristics with GSD Ib patients, we suggest that they are useful for studies of the pathogenesis of congenital GNMT deficiencies and the role of GNMT in GSD and liver tumorigenesis.     

基质金属蛋白酶-2与肝纤维化

肝纤维化是各种慢性肝病向肝硬化发展的共同病理过程 ,其实质是以Ⅰ、Ⅲ型为主的胶原纤维等细胞外基质 (ＥＣＭ )合成与降解失衡 ,导致ＥＣＭ在肝内过度沉积而形成的。研究表明 ,参与ＥＣＭ降解的主要是基质金属蛋白酶类 (ＭＭＰｓ) ,其中基质金属蛋白酶 2 (ＭＭＰ 2 )在ＥＣＭ的降解与重塑中起着非常重要的作用 ,并有其独特的性质。本文就ＭＭＰ 2的来源、性质、结构及其在肝纤维化的发生、发展中的作用等作一介绍。一、ＭＭＰ 2的来源、结构ＭＭＰ 2又名明胶酶Ａ ,为Ⅳ型胶原酶的一种。相对分子质量为 72× 10 3 ,无糖基形式 ,主要由各种…     

Cyp1a2(-/-) null mutant mice develop normally but show deficient drug metabolism.

Cytochrome P450 1A2 (CYP1A2) is a predominantly hepatic enzyme known to be important in the metabolism of numerous foreign chemicals of pharmacologic, toxicologic, and carcinogenic significance. CYP1A2 substrates include aflatoxin B1, acetaminophen, and a variety of environmental arylamines. To define better the developmental and metabolic functions of this enzyme, we developed a CYP1A2-deficient mouse line by homologous recombination in embryonic stem cells. Mice homozygous for the targeted Cyp1a2 gene, designated Cyp1a2(-/-), are completely viable and fertile; histologic examination of 15-day embryos, newborn pups, and 3-week-old mice revealed no abnormalities. No CYP1A2 mRNA was detected by Northern blot analysis. Moreover, mRNA levels of Cyp1a1, the other gene in the same subfamily, appear unaffected by loss of the Cyp1a2 gene. Because the muscle relaxant zoxazolamine is a known substrate for CYP1A2, we studied the Cyp1a2(-/-) genotype by using the zoxazolamine paralysis test: the Cyp1a2(-/-) mice exhibited dramatically lengthened paralysis times relative to the Cyp1a2(+/+) wild-type animals, and the Cyp1a2(+/-) heterozygotes showed an intermediate effect. Availability of a viable and fertile CYP1A2-deficient mouse line will provide a valuable tool for researchers wishing to define the precise role of CYP1A2 in numerous metabolic and pharmacokinetic processes.     

Angiostatin inhibits experimental liver fibrosis in mice

Background and aims Liver fibrosis is a response to chronic hepatic damage, which ultimately leads to liver failure and necessitates liver transplantation. A characteristic of fibrosis is pathological vessel growth. This type of angiogenesis may contribute to the disturbance of hepatocyte perfusion dynamics and lead to aggravation of disease. We hypothesized that angiostatin can inhibit pathological vessel growth and, consequently, the development of hepatic fibrosis.Methods Hepatic fibrosis was induced by injection of carbon tetrachloride for 5 weeks. Angiostatin mice received carbon tetrachloride for 5 weeks and angiostatin during weeks 4 and 5. After 5 weeks, immunohistochemistry for endothelial cell marker von Willebrand factor and for cell proliferation was performed. Angiogenesis was quantified by counting the number of immunopositive microvessels. Also, the relative fibrotic surface was determined using Sirius Red histostaining and computer image analysis.Results Immunohistochemistry revealed increased expression for von Willebrand factor in fibrotic livers. Immunopositive microvessels were localized in fibrotic areas surrounding larger vessels and in emerging fibrotic septa. Angiostatin reduced the number of immunopositive microvessels by 69% (p<0.001). In addition, angiostatin reduced the relative fibrotic area in the liver by 63±0.1% (p<0.001). Finally, angiostatin treatment was not associated with differences in cell proliferation.Conclusions Angiostatin inhibits the development of pathological angiogenesis and liver fibrosis in mice. These results warrant further evaluation of angiostatin as an antifibrotic agent, potentially contributing to the deferment of liver transplantation and reduced recurrence of fibrotic disease in the transplanted liver.     

Leptin administration exacerbates thioacetamide-induced liver fibrosis in mice

AIM: To investigate the effects of leptin administration on liver fibrosis induced by thioacetamide (TAA). METHODS: Twenty-four male C57Bl/6 mice were randomly allocated into four groups, which were intra-peritoneally given saline (2 mL/kg), leptin (1 mg/kg), TAA (200 mg/kg), TAA (200 mg/kg) plus leptin (1 mg/kg) respectively, thrice a week. All mice were killed after 4 wk. The changes in biochemical markers, such as the levels of alanine aminot-ransferase (ALT) and aspartate aminotransferase (AST) in serum and superoxide dismutase (SOD), malondialdehyde (MDA) in liver were determined. For histological analysis, liver tissues were fixed with 10% buffered formalin, embedded with paraffin. Hematoxylin-eosin (HE) staining and picric acid-Sirius red dyeing were performed. The level of α1(I) procollagen mRNA in liver tissues was analyzed by RT-PCR. RESULTS: Apparent liver fibrosis was found in TAA group and TAA plus leptin group. Compared to saline group, the levels of ALT and AST in serum and MDA in liver increased in TAA group (205.67±27.69 U/L vs50.67±10.46 U/L, 177.50±23.65 U/L vs 76.33±12.27 U/L, 2.60±0.18 nmol/mg pro vs 1.91±0.14 nmol/mg pro, P<0.01) and in TAA plus leptin group (256.17±22.50 U/L vs 50.67±10.46 U/L, 234.17±27.37 U/L vs 76.33±12.27 U/L, 2.97±0.19 nmol/mg pro vs 1.91±0.14 nmol/mg pro,P<0.01). The level of SOD in livers decreased (51.80±8.36 U/mg pro vs 81.52±11.40 U/mg pro, 35.78±6.11 U/mg pro vs 81.52± 11.40 U/mg pro, P<0.01) and the level of α1(I) procollagen mRNA in liver tissues also increased (0.28±0.04 vs 0.11± 0.02, 0.54±0.07 vs 0.11±0.02, P<0.01). But no significant changes were found in leptin group and saline group. Compared to TAA group, ALT, AST, MDA, and α1(I) procollagen mRNA and grade of liver fibrosis in TAA plus leptin group increased (256.17±22.50 U/L vs 205.67± 27.69 U/L, P<0.05; 234.17±27.37 U/L vs 177.50±23.65 U/L, P<0.05; 2.97±0.19 nmol/mg pro vs 2.60±0.18 nmol/mg pro,P<0.05; 0.54±0.07 vs 0.28±0.04, P<0.01; 3.17 vs 2.00, P<0.05), and the level of SOD in liver decreased (35.78±6.11 U/mg pro vs 51.80±8.36 U/mg pro, P<0.05). There were similar changes in the degree of type I collagen deposition confirmed by picric acid-Sirius red dyeing. CONCLUSION: Leptin can exacerbate the degree of TAA-induced liver fibrosis in mice. Leptin may be an important factor in the development of liver fibrosis.     

罗格列酮对小鼠日本血吸虫病肝纤维化基质金属蛋白酶-2的影响

目的:研究PPARγ配体罗格列酮治疗小鼠血吸虫病肝纤维化,血清MMP-2与TIMP-2的变化及肝组织MMP-2与TIMP-2的基因表达方法:昆明小鼠50只,随机分为正常对照组A、感染对照组B、吡喹酮治疗组C、罗格列酮治疗组D及罗格列酮加吡喹酮治疗组E.除正常对照组外,其余各组均建立血吸虫病肝纤维化小鼠模型.用ELISA法检测血清MMP-2及TIMP-2的含量,实时荧光定量PCR反应观察小鼠肝组织MMP-2 mRNA及TIMP-2 mRNA的表达.结果:D,E组血清MMP-2的含量(306.0±62.3μg/L,312.0±54.3μg/L)及肝组织MMP-2 mRNA的表达[-19.1±(-6.0),-20.4±(-6.2)]高于A组[221.3±39.2μg/L,-26.3±(-5.3):P<0.051,但明显低于B组[411.3±57.5μg/L,-12.2±(-4.4),P<0.05]和C组[402.9±57.2μg/ L,-12.8±(-4.0),P<0.051.B,C,D和E组血清TIMP-2的含量及肝组织TIMP-2 mRNA的表达均显著高于正常对照组[209.3±60.5μg/L,-20.5±(-4.7);213.5±66.0μg/L,-19.9±(-5.1);223.6±65.3μg/L,-18.8±(-5.5);224.5±64.4μg/L,-19.7±(-4.3) vs 150.4±46.5μg/L,-27.2±(-6.0),P<0.05],但这4组间TIMP-2值无显著性差异(P>0.05).结论:MMP-2在血吸虫病肝纤维化形成中起促进作用,PPARγ配体罗格列酮的抗肝纤维化机制与其下调MMP-2的表达有一定关系.     

TIMP-1/-2 and transient elastography allow non invasive diagnosis of cystic fibrosis associated liver disease

BackgroundCystic fibrosis (CF) associated liver disease develops in approximately 30% of CF patients. However, routine sensitive diagnostic tools are lacking.AimsWe aimed to compare the value of transient elastography and experimental fibrosis markers for the detection of liver disease in CF patients.Methods145 CF patients (75 children, 70 adults) were prospectively studied and received transient elastography. CF liver disease was diagnosed according to recent guidelines. Serum concentrations of YKL-40, HA, PIIIP, MMP-9, TIMP-1 and TIMP-2 were determined by ELISA.ResultsTransient elastography was increased in adults and children with CF hepatopathy compared to those without and exhibited a high diagnostic accuracy for CF liver disease. In adults with portal hypertension, elastography was further enhanced. TIMP-2 was elevated in adults with CF hepatopathy associated portal hypertension and exhibited a high diagnostic accuracy for portal hypertension in adults and for CF hepatopathy in children. TIMP-1 had a high diagnostic accuracy for CF hepatopathy in adults. Diagnostic sensitivities were increased when elastography and respective biomarkers were combined for the detection of CF hepatopathy and portal hypertension.ConclusionsTIMP-1 and TIMP-2 represent powerful biomarkers for CF associated liver disease and portal hypertension. Their determination may confirm and improve the diagnostic accuracy of transient elastography.     

Enhanced carbon tetrachloride-induced liver fibrosis in mice lacking adiponectin

BACKGROUND & AIMS: Obesity is one of the risk factors for liver fibrosis, in which plasma adiponectin, an adipocytokine, levels are decreased. Hepatic stellate cells play central roles in liver fibrosis. When they are activated, they undergo transformation to myofibroblast-like cells. Adiponectin suppresses the proliferation and migration of vascular smooth muscle cells, whose characteristics are similar to those of hepatic stellate cells. Adiponectin could have biological significances in liver fibrosis. METHODS: The role of adiponectin on liver fibrosis induced by the administration of carbon tetrachloride twice a week for 12 weeks was tested by using adiponectin-knockout mice and an adenovirus-mediated adiponectin-expression system. We also investigated the effect of adiponectin in activated hepatic stellate cells. RESULTS: When mice were administered carbon tetrachloride (300 microL/kg body weight) twice a week for 12 weeks, knockout mice showed extensive liver fibrosis with an enhanced expression of transforming growth factor-beta 1 and connective tissue growth factor compared with wild-type mice (P < 0.05). Injection of adenovirus producing adiponectin (AdADN) before carbon tetrachloride (1000 microL/kg body weight) treatment prevented liver fibrosis in wild-type mice (P < 0.001). Injection of AdADN at 6 weeks attenuated liver fibrosis even though carbon tetrachloride was given for an additional 6 weeks (total of 12 weeks). In cultured hepatic stellate cells, adiponectin suppressed platelet-derived growth factor-induced proliferation and migration and attenuated the effect of transforming growth factor-beta 1 on the gene expression of transforming growth factor-beta 1 and connective tissue growth factor and on nuclear translocation of Smad2. CONCLUSIONS: The findings indicate that adiponectin attenuates liver fibrosis and could be a novel approach in its prevention.     

Compensatory enlargement and stenosis develop in apoE(-/-) and apoE*3-Leiden transgenic mice

Atherosclerotic mouse models develop little ischemic organ damage and no infarctions, despite the presence of large atherosclerotic lesions. Therefore, we hypothesize that luminal changes do not follow atherosclerotic lesion development. Because a phenomenon that may explain the discrepancy between luminal changes and lesion size is vascular remodeling, we measured parameters of vascular remodeling in the carotid arteries (CAs), thoracic aorta (TA), and abdominal aorta (AA) of apolipoprotein E (apoE)-deficient (apoE(-/-)) and apoE*3-Leiden mice, 2 well-known mouse models of atherosclerosis. Atherosclerotic lesions were classified (American Heart Association [AHA] types II through V), and plaque thickness, compensatory enlargement versus constrictive remodeling, lumen diameter, stenosis, and media thickness were measured relative to the nondiseased arterial wall. In CAs, plaque thickness increased during atherogenesis. CAs showed compensatory enlargement (apoE(-/-) 55%, apoE*3-Leiden 38%). Regression analysis revealed a positive correlation between plaque and lumen area (for apoE(-/-), R=0.95; for apoE*3-Leiden, R=0.90). Medial thinning and elastolysis were also observed. During atherogenesis, lumen diameter decreased (apoE(-/-) -69%, apoE*3-Leiden -40%), and stenosis >70% developed. TA and AA showed similar features, but neither developed a progressive decrease in lumen diameter or stenosis >70%. In CAs, TA, and AA of apoE(-/-) and apoE*3-Leiden mice, atherogenesis is associated with compensatory enlargement, medial thinning, and elastolysis. A progressive decrease in lumen diameter and stenoses >70% occur only in CAs. Vascular remodeling is more prominent in apoE(-/-) mice.     

Protease-activated receptor 2 promotes experimental liver fibrosis in mice and activates human hepatic stellate cells

Protease-activated receptor (PAR) 2 is a G-protein-coupled receptor that is activated after proteolytic cleavage by serine proteases, including mast cell tryptase and activated coagulation factors. PAR-2 activation augments inflammatory and profibrotic pathways through the induction of genes encoding proinflammatory cytokines and extracellular matrix proteins. Thus, PAR-2 represents an important interface linking coagulation and inflammation. PAR-2 is widely expressed in cells of the gastrointestinal tract, including hepatic stellate cells (HSCs), endothelial cells, and hepatic macrophages; however, its role in liver fibrosis has not been previously examined. We studied the development of CCl(4) -induced liver fibrosis in PAR-2 knockout mice, and showed that PAR-2 deficiency reduced the progression of liver fibrosis, hepatic collagen gene expression, and hydroxyproline content. Reduced fibrosis was associated with decreased transforming growth factor beta (TGFβ) gene and protein expression and decreased matrix metalloproteinase 2 and tissue inhibitor of matrix metalloproteinase 1 gene expression. In addition, PAR-2 stimulated activation, proliferation, collagen production, and TGFβ protein production by human stellate cells, indicating that hepatic PAR-2 activation increases profibrogenic cytokines and collagen production both in vivo and in vitro. CONCLUSION: Our findings demonstrate the capacity of PAR-2 activation to augment TGFβ production and promote hepatic fibrosis in mice and to induce a profibrogenic phenotype in human HSCs. PAR-2 antagonists have recently been developed and may represent a novel therapeutic approach in preventing fibrosis in patients with chronic liver disease.     

Induction of heme oxygenase 1 prevents progression of liver fibrosis in Mdr2 knockout mice

Induction or overexpression of the heme-degrading enzyme, heme oxygenase 1 (HO-1), has been shown to protect mice from liver damage induced by acute inflammation. We have investigated the effects of HO-1 induction in a mouse model of chronic liver inflammation and fibrogenesis with progression to hepatocellular carcinoma (HCC) (Mdr2ko; FVB.129P2-Abcb4(tm1Bor)). HO-1 was induced in vivo by treatment with cobalt protoporphyrin IX, starting at week 5 or 12 of mice lifespan, and continued for 7 weeks. Our results showed that HO-1 induction reduced liver damage and chronic inflammation by regulating immune cell infiltration or proliferation as well as tumor necrosis factor receptor signaling. Fibrosis progression was significantly reduced by HO-1 induction in mice with mild, as well as established, portal and lobular fibrosis. HO-1 induction significantly suppressed hepatic stellate cell activation. During established fibrosis, HO-1 induction was able to revert portal inflammation and fibrosis below levels observed at the start of treatment. Moreover, hepatocellular proliferation and signs of dysplasia were decreased after HO-1 induction. CONCLUSION: Induction of HO-1 interferes with chronic inflammation and fibrogenesis and, in consequence, might delay progression to HCC.     

Transplantation of fetal liver epithelial progenitor cells ameliorates experimental liver fibrosis in mice

INTRODUCTION The incidence of hepatic injury and end-stage liver f ibrosis is high in China. Cirrhosis represents a serious health care problem worldwide. The prognosis of patients with the disease is poor, although liver transplantation is a successful t…     

Human platelets inhibit liver fibrosis in severe combined immunodeficiency mice

AIM:To investigate the role of human platelets in liver fibrosis.METHODS:Severe combined immunodeficiency(SCID)mice were administered CCl4and either phosphate-buffered saline(PBS group)or human platelet transfusions(hPLT group).Concentrations of hepatocyte growth factor(HGF),matrix metallopeptidases(MMP)-9,and transforming growth factor-β(TGF-β)in the liver tissue were compared between the PBS and the hPLT groups by enzyme-linked immunosorbent assay(ELISA)and Western blotting.The effects of a human platelet transfusion on liver fibrosis included the fibrotic area,hydroxyproline content,and-smooth muscle actin(α-SMA)expression,which were evaluated by picrosirius red staining,ELISA,and immunohistochemical staining using an anti-mouse-SMA antibody,respectively.Phosphorylations of mesenchymal-epithelial transition factor(Met)and SMAD3,downstream signals of HGF and TGF-β,were compared between the two groups by Western blotting and were quantified using densitometry.Hepatocyte apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling.Furthermore,the accumulation of human platelets in the liver 2 h after platelet transfusion was compared between normal and fibrotic livers by immunohistochemical staining using an anti-human CD41 antibody.RESULTS:The fibrotic area and hydroxyproline content in the liver were both significantly lower in the hPLT group when compared to the PBS group(fibrotic area,1.7%±0.6%vs 2.5%±0.6%,P=0.03;hydroxyproline content,121±26 ng/g liver vs 156±47 ng/g liver,P=0.04).There was less α-smooth muscle actin staining in the hPLT group than in the PBS group(0.5%±0.1%vs 0.8%±0.3%,P=0.02).Hepatic expression levels of mouse HGF and MMP-9were significantly higher in the hPLT group than in the PBS group(HGF,109±13 ng/g liver vs 88±22 ng/g liver,P=0.03;MMP-9,113%±7%/GAPDH vs 92%±11%/GAPDH,P=0.04).In contrast,the concentration of mouse TGF-β in the liver tissue was significantly lower in the hPLT group than in the PBS group(22±5ng/g liver vs 39±6 ng/g liver,P=0.     

cytoplasmic domain of tissue factor promotes liver fibrosis in mice

AIM To evaluate the role of tissue factor(TF) and protease activated receptor(PAR)-2 in liver fibrosis.METHODS Using CCl4 administration for eight weeks, we induced hepatic fibrosis in wild-type C57BL/6 mice and in mice with deletion of the cytoplasmic signalling domain of TF(TF§CT/§CT), deletion of PAR-2(PAR-2-/-) and combined deletion of TF signalling domain and PAR-2(TF§CT/§CT/PAR-2-/-). Hepatic fibrosis area was assessed by quantitative imaging of picrosirius red staining. Hepatic collagen content was assessed by hydroxyproline levels. Hepatic stellate cells(αSMA positive) and hepatic macrophages(CD68 positive) were identified by immunohistochemistry. Hepatic gene expression was determined by PCR and liver TGFβ1 content by ELISA.RESULTS CCl4 treated mice with deletion of the PAR-2 gene(PAR-2-/-) and the cytoplasmic domain of TF(TF§CT/§CT) developed significantly less hepatic fibrosis, characterised by reduced liver fibrosis area and hydroxyproline content, compared to control wildtype mice treated with CCl4. The observed reduction in histological fibrosis was accompanied by a significant decrease in the hepatic content of TGFβ, the prototypic fibrogenic cytokine, as well as fewer activated hepatic stellate cells and hepatic macrophages. Deletion of the TF cytoplasmic signalling domain reduced hepatic fibrosis to levels similar to thoseobserved in mice lacking PAR-2 signalling but combined deletion provided no added protection against fibrosis indicating a lack of mutual modulating effects that have been observed in other contexts such as angiogenic responses.CONCLUSION Tissue factor cytoplasmic domain is involved in TF-PAR-2 signalling initiating hepatic fibrosis and is a potential therapeutic target, as its deletion would not impact coagulation.     

Platelets contribute to the reduction of liver fibrosis in mice

Background and Aim:  Several recent studies have reported that liver cirrhosis (LC) can be ameliorated, but few adequate strategies are available against liver fibrosis. Although LC clinically shows thrombocytopenia and hypersplenism, the correlation with liver fibrosis and platelets remains unclear. The aim of the present study was to investigate the effect of platelets on liver fibrosis in mouse models.
Methods:  To induce liver fibrosis, C57BL6 female mice were injected i.p. with 1 mL/kg carbon tetrachloride (CCl₄) twice a week for 8 weeks. Thrombocytosis was achieved by giving thrombopoietin or splenectomy in addition to CCl₄ intoxication. At 8 weeks, whole blood and liver specimens were obtained for studies as follows: peripheral platelet counts, histopathological examination, hydroxyproline assay, immunostaining, quantification of mRNA expression, and microarray analysis.
Results:  Thrombocytosis significantly reduced liver fibrosis and hydroxyproline content of liver tissues compared to mice with CCl₄ administration alone. Platelets suppressed increments in mRNA expression for transforming growth factor-β, and increased matrix metalloproteinase-9 expression in the liver. Microarray analysis of the liver revealed that platelets upregulated gene expressions involved in cell proliferation compared to expression in mice with CCl₄ intoxication alone. Platelets also increased liver volume, proliferative cell nuclear antigen labeling index, and mitotic index in fibrotic mice.
Conclusion:  These results clearly show that platelets reduce liver fibrosis and promote liver regeneration, even under cirrhotic conditions. We, therefore, propose that platelets could offer a potent tool in the treatment of liver cirrhosis.     

ACE2-Ang(1-7)-Mas受体轴与肝纤维化

肾素血管紧张素系统(renin angiotensin system,RAS)是人类生理功能的一个重要调节机制,在维持血压稳态、水盐平衡及局部组织器官的正常功能等方面具有重要作用。经典的RAS作用轴ACE-AngⅡ-AT1R在肝纤维化的发生过程中起促进作用,而ACE2-Ang(1-7)-Mas受体轴是新发现的RAS作用轴,是ACE-AngⅡ-ATR1的反向调节轴,对肝纤维化的发生具有保护作用。本文将ACE2-Ang(1-7)-Mas受体轴与肝纤维化关系的研究进展介绍如下。